Skip Navigation LinksHome > August 2008 - Volume 109 - Issue 2 > Regulation of Apoptotic and Inflammatory Cell Signaling in C...
doi: 10.1097/ALN.0b013e31817f4ce0
Review Articles

Regulation of Apoptotic and Inflammatory Cell Signaling in Cerebral Ischemia: The Complex Roles of Heat Shock Protein 70

Giffard, Rona G. M.D., Ph.D.*; Han, Ru-Quan M.D., Ph.D.†; Emery, John F. Ph.D.‡; Duan, Melissa B.S.§; Pittet, Jean Francois M.D.∥

Free Access
Article Outline
Collapse Box

Author Information

Collapse Box


Although heat shock proteins have been studied for decades, new intracellular and extracellular functions in a variety of diseases continue to be discovered. Heat shock proteins function within networks of interacting proteins; they can alter cellular physiology rapidly in response to stress without requiring new protein synthesis. This review focuses on the heat shock protein 70 family and considers especially the functions of the inducible member, heat shock protein 72, in the setting of cerebral ischemia. In general, inhibiting apoptotic signaling at multiple points and up-regulating survival signaling, heat shock protein 70 has a net prosurvival effect. Heat shock protein 70 has both antiinflammatory and proinflammatory effects depending on the cell type, context, and intracellular or extracellular location. Intracellular effects are often antiinflammatory with inhibition of nuclear factor-κB signaling. Extracellular effects can lead to inflammatory cytokine production or induction of regulatory immune cells and reduced inflammation.
HEAT shock proteins (HSP), also called stress proteins, are induced by specific types of stress, including heat, and they are highly conserved from bacteria to humans.1–4 The HSP70 family facilitates the folding of newly synthesized polypeptides in an adenosine triphosphate (ATP)–dependent manner, plays an important role in maintaining the dynamic stability of protein folding and protein–protein interactions within the cell, and inhibits protein aggregation.5,6 These are referred to collectively as chaperone functions. By interacting with a range of cochaperones and client proteins, both constitutive and inducible HSPs regulate the functioning of other proteins and indeed whole signaling cascades. These interactions allow a cell to rapidly respond to stresses and changes in its environment without requiring protein synthesis, though induction of stress protein synthesis provides the next line of response. HSPs are divided into families on the basis of molecular weight. HSPs that are present as a single copy in bacteria (e.g., dna K), are generally represented by multiple related genes in eukaryotes (e.g., HSP70 family).
HSP70 family members have long been recognized to have cytoprotective effects. The human HSP70 family consists of at least 12 members.7 The best known members are the heat inducible form, Hsp70/Hsp72; the constitutively expressed Hsc70/Hsp73/Hsc73; the endoplasmic reticulum form, Grp78/BiP; and Hsp75/mtHsp70/mortalin, which is localized largely to mitochondria. Of these, the cytosolic inducible Hsp72 plays a major role in mediating cytoprotective, antiapoptotic, and immune regulatory effects and is by far the best studied. Enhanced expression of Hsp72 in experimental models of stroke, sepsis, acute respiratory distress syndrome, renal failure, and myocardial ischemia has been shown to reduce organ injury and in some cases improve survival.8–11 Deletion of the hsp70.1/3 gene is associated with poorer outcome in mice.12 In addition to their intracellular protective and antiapoptotic role, HSPs also function as extracellular signals.13 We will use HSP70 to refer to the entire family, and Hsp70 in instances where either Hsp72 or 73 is referred to, because some reports and some antibodies do not distinguish between these two cytosolic family members, though the majority of studies focus on the stress inducible Hsp72.
Clinical studies have begun to identify correlations between Hsp70 and outcome in a variety of diseases. A reduced ability to induce Hsp72 in peripheral lymphocytes was noted in patients with sepsis.14 Higher serum Hsp72 levels correlated with improved survival after trauma15 and severe sepsis.16,17 Several studies have evaluated Hsp70 expression after myocardial infarction and cardiac surgery with bypass and found significant increases in Hsp70 expression in all cases.18–20 Therefore, increased levels of Hsp70 can indicate tissue damage, but they may also indicate the successful mounting of a stress response that correlates with tissue protection and better outcome.21 Hsp70 seems to participate in protection against organ dysfunction both in critically ill patients and in patients during the perioperative period. Overexpression by gene therapy or chemical induction of a stress response is under investigation as a potential treatment for ischemia in several organ systems, including the use of glutamine to increase Hsp70 in critically ill patients.17,22 We will focus primarily on data from cerebral ischemia in this review.
Back to Top | Article Outline

Hsp72 in Cell Death Signaling Pathways in Cerebral Ischemia

Fig. 1
Fig. 1
Image Tools
Hsp72 has been shown to provide neuroprotection from cerebral ischemia in animal and cell-culture models of stroke.10,23–25 Although the mechanism of this protection was initially attributed to chaperone functions (i.e., maintaining correct protein folding and blocking aggregation), recent work has shown that Hsp72 may also directly interfere with cell death pathways such as apoptosis and necrosis (fig. 1) and may modulate inflammation.10,26–34
Programmed cell death occurs by multiple pathways. Apoptosis occurs primarily by one of two pathways.35 The intrinsic pathway responds to stress and intracellular changes; it relies on the release of mitochondrial proapoptotic molecules, opening of the mitochondrial permeability transition pore, and activation of caspases.36 The second well-described pathway is the extrinsic pathway, which is triggered by the activation of plasma membrane receptors, which then signal through their death domains. This signaling activates caspase 8 and can proceed independently of the intrinsic pathway, but it can also lead to activation of the intrinsic pathway.37 In addition, caspase-independent forms of cell death have been described,38,39 and depletion of Hsp70 can trigger caspase-independent cell death in cancer cells.40,41
Back to Top | Article Outline
Hsp72 Reduces Mitochondria-dependent Apoptotic Signaling
Mitochondria are central to both necrotic and apoptotic cell death; the pathway followed often depends on the severity of the injury.42 The resulting death reflects the signaling cascade activated by the stress or apoptotic stimulus.43–46 In most instances, severe cerebral ischemia rapidly renders mitochondria unable to produce ATP, which ensures necrotic cell death. Mitochondrial alterations that occur during both global and focal cerebral ischemia and contribute to cell death include changes in mitochondrial respiratory function,47,48 production of reactive oxygen species,49,50 changes in mitochondrial membrane potential and permeability,51,52 and release of regulatory and signaling molecules from the mitochondrial intermembrane space.53
Activation of the intrinsic mitochondrial pathway in ischemic brain has been demonstrated in both neonatal and adult models by the release of mitochondrial cytochrome c.46,52,54 Cytochrome c translocates from the mitochondria to the cytosol, where it interacts with the CED-4 homolog, apoptosis protease activating factor 1, and dATP to form the apoptosome and activate caspase 9.35,36 Caspase 9 activates caspase 3, one of the executioner caspases, as well as caspases 2, 6, 8, and 10.55 Caspase 3 also activates caspase-activated DNase, which fragments DNA. In cerebral ischemia, caspases 3 and 9 have been shown to play a key role in neuronal death after both global ischemia56,57 and focal ischemia,58–61 with caspase 3–dependent apoptosis more prominent in neonatal than adult ischemia, and more prominent in global than focal ischemia. In cerebral ischemia, the downstream caspases cleave many substrate proteins, including poly(ADP-ribose) polymerase (PARP).56,57,62 With cleavage of multiple targets within the cell and DNA fragmentation, apoptotic cell death results.63–67
Hsp70 affects several different steps in the apoptosis cascade (fig. 1). Hsp72 interacts with components of the programmed cell death machinery upstream68,69 and potentially downstream70 of mitochondrial events. Hsp72 can inhibit cytochrome c release in both neonatal and adult ischemia,54,71,72 and inhibit apoptosis inducing factor translocation to the nucleus34,73 while reducing ischemic brain injury in both adult and neonatal models. Several of the studies on effects of Hsp72 in cerebral ischemia have been performed in transgenic mice overexpressing this gene. These findings in cerebral ischemia are consistent with observations in other systems where Hsp72 has been shown to interfere with recruitment of procaspase 9 into the apoptosome, and to sequester apoptosis inducing factor.74 Hsp72 also inhibited release of the proapoptotic protein Smac/DIABLO from myocyte mitochondria.75
Mitochondrial Hsp70/Hsp75/mortalin helps to maintain mitochondrial membrane potential, which may contribute to the preservation of mitochondrial function76 and mitochondrial protein import.77,78 Several authors have postulated an involvement of Hsp75 in preventing electron leak between complexes III and IV, by binding and consequently reducing cytochrome c loss from mitochondrial membranes, thereby averting an increase in state IV respiration rates and induction of cytochrome c–linked apoptosis.79 Overexpression of Hsp75 in astrocytes reduced their vulnerability to oxygen glucose deprivation, an in vitro model of ischemia, and maintained higher ATP levels in stressed cells.80 Overexpression of Hsp72 in astrocytes was associated with reduced reactive oxygen species formation and better maintained mitochondrial membrane potential after ischemia in vitro 81 and with better preservation of glutathione levels.27 In myocardial cells, overexpression of Hsp72 was shown to increase the activity of the mitochondrial antioxidant enzyme manganese superoxide dismutase.82
Back to Top | Article Outline
Hsp72 and the Bcl-2 Family Regulators of Apoptosis
Viral vector–mediated Hsp72 overexpression was associated with increased levels of Bcl-2 protein in brain cells.83 Bcl-2 is a key antiapoptotic protein; its increased expression blocks release of cytochrome c and apoptosis inducing factor and reduces caspase activation. The balance between proapoptotic and antiapoptotic members of the large Bcl-2 family determines whether cells undergo apoptosis by regulating the mitochondrial membrane permeability transition.84,85 Transgenic overexpression of Bcl-2 decreased infarction after focal cerebral ischemia,86 whereas Bcl-2 knockout mice had increased infarct area.87 Therefore, increased Hsp72 expression can reduce induction of apoptosis upstream of mitochondria in cerebral ischemia both directly and via increased Bcl-2 levels. Hsp72 blocks heat-induced apoptosis primarily by inhibiting translocation of the proapoptotic Bcl-2 family member Bax, thereby preventing the release of proapoptotic factors from mitochondria.69 Hsp72 also interferes with the activity of apoptosis protease activating factor 1, which is required for formation of the apoptosome and activation of caspase 9,54,74,88 but also see Steel et al.,68 who demonstrated lack of direct interaction with apoptosis protease activating factor-1.
Back to Top | Article Outline
Hsp72 and Regulation of Transcription Factors in Cell Death Signaling
Hsp72 interacts with pathways leading to activation of transcription factors important in regulating cell death. Hsp72 has been shown to inhibit c-Jun N-terminal kinase (JNK) dephosphorylation, thereby blocking its activation.89–91 Activated JNK phosphorylates the transcription factor c-JUN to up-regulate a specific group of proteins.91 JNK activation plays both direct and indirect roles in neuronal apoptosis,92 and it is a proposed target for stroke therapy.93,94 JNK is implicated in apoptosis triggered by Fas, a member of the tumor necrosis factor superfamily of membrane receptors,95 as well as figuring prominently in the apoptosis of neurons induced by growth factor withdrawal.92 JNK is one of the mitogen-activated protein kinases. These kinases constitute one of the central signaling pathways in intracellular response,96 often determining whether a cell responds with apoptosis or differentiation and survival. JNK signaling in the nervous system is not solely for promoting apoptosis. There is a high level of basal JNK signaling activity in the nervous system compared with other tissues, suggesting normal physiologic functions.94 Increasing evidence suggests that the downstream events of JNK activation leading to apoptosis involve both transcription97,98 and mitochondrial mechanisms.92,93
In ischemic stroke, increased c-JUN phosphorylation colocalized with terminal deoxynucleotidyl transferase–mediated dUTP-biotin end labeling in the penumbral area in an experimental model of focal ischemia.99 Subsequent studies showed that Jnk3-deficient mice have increased resistance to global ischemia–hypoxia.94 JNK3 deficiency causes reduced Bim and Fas expression after stroke, and Jnk3-null hippocampal neurons released less cytochrome c after oxygen-glucose deprivation.94 Furthermore, mice lacking the JNK signaling scaffold protein JIP1 have increased resistance to glutamate excitotoxicity100 and reduced infarct volume in a focal ischemia model of stroke.101 These studies suggest that JNK signaling may play an important role in determining cell death or survival for neurons at risk in the ischemic penumbra.
Hsp72 also interacts with topoisomerase 1, which is also implicated as a regulator of apoptosis.102,103 These interactions were shown to be independent of the ATP binding domain.102 Hsp72 is also an effector for the important antiapoptotic prosurvival kinase Akt/protein kinase B104,105 and acts upstream of the transcription factor nuclear factor κB (NFκB), reducing its activation, as discussed below.
Back to Top | Article Outline

Hsp72 and Inflammation

Hsp72 also plays a role in modulating inflammation caused by cerebral ischemia. Inflammation can contribute to the damage resulting from stroke.106–109 Inflammatory responses include the activation of resident microglia and astrocytes, as well as recruitment of peripheral inflammatory cells. Inflammation and the concomitant release of reactive oxygen species and reactive nitrogen species by inflammatory cells exacerbate damage caused by direct ischemic production of reactive oxygen species. Blocking the neutrophil integrin CD11/CD18 with an antibody reduced injury in focal ischemia in association with a marked reduction of neutrophil infiltration.110 Recruitment of peripheral leukocytes weakens the blood–brain barrier, leading to further damage. HSP70 family members play a crucial role in modulating these responses.33,111
Back to Top | Article Outline
Hsp72 and Inflammatory Cytokines
Fig. 2
Fig. 2
Image Tools
Intracellular Hsp72 has a range of antiinflammatory actions. It can prevent responses to inflammatory cytokines such as tumor necrosis factor α (TNF) and interleukin 1 (IL-1). Mice subjected to heat shock are protected from normally lethal inflammatory shock after systemic administration of high doses of TNF, whereas mice missing the hsp70.1 gene are no longer protected.112 Liposomally delivered Hsp72 protein protected rats from IL-1–induced impaired pancreatic β-cell function in a diabetes model.113 However, such protection from inflammatory responses may come at a price, because Hsp72 can actually make cells more liable to undergo apoptosis in response to TNF.114,115 In addition to modulating the response to inflammatory cytokines, Hsp72 also down-regulates their production (fig. 2). Overexpression of Hsp72 in human macrophages blocked lipopolysaccharide-induced increases in the production of TNF, IL-1, IL-10, and IL-12.116 In the setting of focal cerebral ischemia, overexpression of Hsp72 was associated with reduced production of TNF and IL-1b,111 likely a reflection of reduced NFκB activation.
Back to Top | Article Outline
Hsp72, iNOS, NADPH Oxidase, and Matrix Metalloproteinases
Hsp72 may limit production of reactive oxygen species via several routes. Inflammation leads to the production of reactive oxygen species by activation of both the inducible form of nitric oxide synthase (iNOS) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Induction of iNOS occurs in response to cytokine release.117 Mice lacking the iNOS gene are protected from cerebral ischemia relative to wild-type mice. At high levels of production, nitric oxide reacts with superoxide to produce the highly toxic strong oxidant, peroxynitrite.117 However, iNOS can be beneficial in facilitating neurogenesis in ischemia.118,119 Hsp72 suppresses iNOS activation in glial cells exposed to bacterial lipopolysaccharide.120
NADPH oxidase is one source of superoxide induced by inflammation. NADPH oxidase produces the oxidative burst of phagocytic leukocytes.121 Recent work suggests that it may be activated in neurons as well as in microglia. That neuronal NADPH oxidase plays a role in aging and hypoglycemic injury was also suggested.122,123 Heat shock induction of Hsp72 reduces NADPH oxidase activity in neutrophils and increases superoxide dismutase, which scavenges superoxide, in phagocytes.124,125 Hsp72 has also been linked to regulation of matrix metalloproteinases. Matrix metalloproteinases are involved in remodeling of the extracellular matrix; they are associated with breakdown of the blood–brain barrier and hemorrhage after cerebral ischemia.126 Hsp72 overexpressing astrocyte cultures down-regulated matrix metalloproteinase 9 after oxygen glucose deprivation, compared with wild-type cell cultures,127 consistent with involvement of Hsp72 in regulation of this aspect of inflammation.
Back to Top | Article Outline
Hsp72 and NFκB
Much, if not most, of intracellular Hsp72’s modulatory effects on inflammation can be attributed to its regulation of the NFκB pathway (fig. 2). Transcription factors of the NFκB family are key players in the initiation of the inflammatory response.128 NFκB is comprised of four related proteins that function as dimers. The most well studied of these is the p50/p65 heterodimer, which is normally sequestered in the cytoplasm by its interaction with inhibitor of κB (IκB). Phosphorylation of IκB by the IκB kinase complex leads to ubiquitination and degradation of IκB, freeing the NFκB dimer to translocate to the nucleus, where it induces the expression of a multitude of genes involved in inflammatory and immune responses, including TNF, IL-1, iNOS, and matrix metalloproteinase 9.128,129
Induction of Hsp72 inhibits the nuclear translocation of NFκB in response to inflammatory cytokines or other stimuli.130 Mice overexpressing Hsp72 showed reduced NFκB activation after stroke.111 This reduced activation may be accomplished through direct interaction of Hsp72 with NFκB proteins or by interactions with other proteins in the NFκB regulatory pathway. Guzhova et al.130 were able to coimmunoprecipitate Hsp72 with three members of the NFκB family (p65, p50, and c-Rel) after heat shock. IκB, however, did not coprecipitate. Feinstein et al.120 demonstrated that heat shock or Hsp72 expression decreased the accumulation of NFκB p65 in the nucleus. Wong et al.131 found that heat shock prevented degradation of IκB, thereby preventing activation of NFκB. Later studies identified interactions between Hsp72 and the γ subunit of the IκB kinase complex.114 Hsp72 may also interact directly with upstream inducers of the NFκB pathway. Another recent study found that Hsp72 directly associated with the IκB–NFκB complex and suggested stabilization of the complex as another mechanism.111 Chen et al.132 found a direct interaction between Hsp72 and tumor necrosis factor receptor–associated protein 6. Ubiquitination of tumor necrosis factor receptor–associated protein 6 is a crucial step in the activation of the NFκB pathway by bacterial lipopolysaccharide and IL-1.133–135 Hsp72 prevents this ubiquitination, which in turn prevents activation of the IκB kinase complex. It is likely that Hsp72 can operate at many levels of the NFκB pathway to inhibit or dampen its activation. Likely independent of its effects on inflammation, NFκB has frequently been associated with cell survival, acting downstream of the kinases Akt and RIP-1. Although there is also a report that NFκB may be involved in induction of apoptosis by ceramide, the majority of reports find it to have antiapoptotic actions.136
Back to Top | Article Outline

Extracellular HSP70s

Although most experiments to date address the intracellular functions of HSP70s, studies have now clearly demonstrated that Hsp72/Hsc73 can be released from cells. The mechanisms of release and the extracellular effects of HSP70 are growing areas of study. One of the first observations suggesting extracellular release of Hsp70 was made in the nervous system; exposure to heat caused an increase in production of heat shock–like proteins in the glial sheath surrounding the squid giant axon (reviewed by Tytell).137 These proteins were transferred from the glial sheath to the interior of the axon. Work from several laboratories now suggests that Hsp72/Hsc73 is released from astrocytes or Schwann cells and can be transferred to and affect neighboring neurons/axons.138–142 Hsp70 release has been documented from a variety of nonneuronal cell types, including epithelial cells,143 rat embryo cells,144 B lymphocytes and dendritic cells,145,146 maturing erythrocytes,147 and tumor cells.148 Hsp70 and anti-Hsp70 antibodies have been identified in human serum.149 Since then, numerous studies have examined levels of extracellular Hsp70 in relation to diseases and pathologic states, as mentioned in the introduction, though in some instances Hsp72 and Hsc73 were not distinguished. Current thinking suggests that HSPs are released physiologically, as well as by dying cells, and can act on a variety of receptors.13,150
Back to Top | Article Outline
Mechanism of Release of Extracellular HSP70
Because Hsp72 and Hsc73 do not contain a leader sequence for membrane targeting or localization to membrane vesicles of the secretory pathway, several alternative mechanisms for extracellular release have been proposed. One hypothesis is release from lysosomes. Lysosomal inhibitors were shown to block Hsp72 release and release correlated with increased expression of the intralysosomal protein LAMP1 on cell surfaces,151 though others found little effect with lysosomal inhibitors. Release of Hsp72 by exosomes is the mechanism supported by the most evidence at this point.145–148,152 Exosomes are membrane-bound vesicles containing various cytosolic proteins, including Hsp72/Hsc73 as well as peripheral and integral membrane proteins.146 Some investigators found that lipid rafts, which are sphingolipid cholesterol–rich microdomains in cell membranes, play a role in HSP70 release.143,153,154 In contrast, others saw no effect on Hsp72 release when either lipid rafts or the classic secretory pathway were disrupted.152
Back to Top | Article Outline
Effects of Extracellular Hsp72
Fig. 3
Fig. 3
Image Tools
If there are physiologic mechanisms for the release of HSP70, there must also be physiologic functions for these extracellular proteins. Although HSP release from dying cells can serve as a danger signal, release from live cells can signal a successful stress response21 and suggests a modulatory or signaling role. Several reports demonstrated that extracellular Hsp72 could induce release of cytokines, including TNF, interleukin-6 (IL-6), and IL-1β, from monocytes.155–158 Other reports cast doubt on those conclusions, suggesting that at least in some cases, the response is due to contamination with lipopolysaccharide, a potent inducer of cytokine release.159–161 Extracellular Hsp72- induced cytokine release was found to be mediated through Toll-like receptor 2 (TLR2), TLR4, and downstream activation of NFκB (fig. 3).155 This contrasts with the aforementioned inhibition of NFκB activation observed in mice overexpressing Hsp72 after cerebral ischemia,111 which is likely due to intracellular effects.
TLR4 initiates the signaling cascade triggered by lipopolysaccharide from gram-negative bacteria, whereas TLR2 mediates the signaling cascade triggered by bacterial lipoproteins, gram-positive bacteria, mycoplasma, yeast, and spirochetes. A role for HSP70 in the response to lipopolysaccharide has been identified. The details of the activation complex induced by lipopolysaccharide are still being worked out, but elegant studies of the mobility of lipopolysaccharide and some of the relevant receptors in the plasma membrane suggest that Hsp70 and 90 can be immobilized in the plasma membrane and colocalize with lipopolysaccharide and TLR4, after an initial transient interaction of lipopolysaccharide with CD14.159 Lipopolysaccharide signaling is thus mediated by a large complex that can include Hsp70. The composition of the complex determines whether signaling results in induction or inhibition of immune response.162,163 There is still discussion in the literature on the extent to which Hsp70 binding is directly mediated by TLR2 or 4, and whether the interaction of these receptors with Hsp70 is of high affinity, because overexpression of either receptor alone does not increase binding of Hsp70 to cells that previously did not bind Hsp70.150
Arispe et al.164 showed a direct interaction of Hsp72/Hsc73 with lipid components. Hsc73 was shown to incorporate into the lipid bilayer and create an ATP-dependent cation channel.164 These investigators also showed that Hsp72 and Hsc73 are able to aggregate liposomes by interacting with phosphatidylserine.165 Although phosphatidylserine is generally found on the cytosolic side of the plasma membrane, it is present on the surface of apoptotic cells. Hsp72 and Hsc73 seem to accelerate cell death by interacting with phosphatidylserine on the surfaces of apoptotic cells.165
Internalization of extracellular Hsp72 is thought to be via cell surface receptors. Hsp72 was found to interact with two main families of cell surface proteins: the scavenger receptor family members LOX-1 and SR-A,166 and the C-type lectins of the natural killer family. These proteins could mediate internalization of Hsp72 protein from the extracellular space.167 Extracellular Hsp72 has been extensively studied for its role in antigen presentation via the major histocompatibility complex pathway, a function important for recognition of tumor cells.168 Extracellular Hsp70 is important in triggering the activity of natural killer cells. Multhoff et al. identified an N-terminal 14–amino acid peptide of Hsp70 that was as active in stimulating natural killer cell cytolytic activity as full-length Hsp70 protein.169 The activation of the cytolytic activity of natural killer cells by Hsp70 is mediated through C-type lectin receptor CD94 and the adhesion molecule CD56.170
Interestingly, administration of Hsp70 in vivo promoted wound healing by stimulating macrophage phagocytic activity,171 and in some chronic inflammatory diseases it is now appreciated that HSPs can prevent or arrest inflammatory damage and promote production of antiinflammatory cytokines.172 Pretreatment with Hsp70 has also been shown to reduce the inflammatory response of monocytes to a subsequent challenge with lipopolysaccharide.173 Therefore, several different functions have already been described for extracellular HSP70, including protection of neurons and modulation of immune cell function.
Back to Top | Article Outline
Extracellular Hsp70 and Cardiovascular Disease
As the importance of inflammation in cardiovascular disease is increasingly recognized, the likelihood that immunomodulatory effects of HSP70 may be relevant increases. A significant correlation between elevated levels of serum Hsp70 and reduced progression of atherosclerosis assessed as carotid intima–media thickness was found.174 A study of coronary artery disease patients observed significantly higher serum Hsp70 levels in patients found not to have coronary artery disease on angiogram, and disease severity was inversely correlated with serum Hsp70 levels.175
Although higher serum Hsp72 levels were associated with reduced risk of atherosclerosis, Hsp72 is released with myocardial infarction; serum levels after acute myocardial infarction were higher than in patients with angina.18 Levels of extracellular Hsp72 also correlated with levels of IL-6 and IL-8. In atherosclerosis, endothelial cells are activated and macrophages release inflammatory cytokines. Oxidized low-density lipoproteins accumulate in macrophages. Svensson et al.156 found that oxidized low-density lipoprotein–treated macrophages released increased amounts of Hsp72, and this released Hsp72-induced IL-1β and IL-12 production by naive macrophages. While elevated serum Hsp72 was associated with slower progression of carotid intimal thickening, it may also have some proinflammatory effects. The role of Hsp72 in cerebral atherosclerosis and stroke is thus complex.
Back to Top | Article Outline


Many studies support the protective effect of Hsp72 in cerebral ischemia. These studies employed transgenic overexpression of Hsp72 in neonatal and adult models of ischemia,54,72,73,176 the use of mice in which the Hsp70.1 gene was knocked out,71 and transfection or viral vector mediated overexpression.10,34 Although each method has its own caveats, the consistent result strongly suggests that Hsp72 is efficacious at reducing cerebral ischemic injury. However, in evaluating the different mechanisms discussed in this article, much work remains to define the relative contributions of each to protection in the setting of cerebral ischemia, and differences between different models should be expected. Although there is already strong evidence for both antiinflammatory and anti–cell death effects of Hsp72 in cerebral ischemia, the relative importance of these mechanisms remains to be determined. In marked contrast, the role of extracellular Hsp72 in stroke has not yet been studied in animal models, and at this moment we are in the curious position of having more data on the association of serum Hsp70 with ischemic disease in patients than in animal models. Future studies should address this issue.
Hsp70 has many physiologic roles, both intracellular and extracellular, and participates in the regulation of many intracellular processes. Hsp70 holds great promise as a potential therapeutic approach to many diseases involving abnormalities of protein folding or increased aggregation as found in both acute and chronic neurodegenerative diseases. Hsp70 is also an important immune modulator and is now appreciated to play a role as an extracellular signaling molecule. Current understanding suggests active release of HSP from live cells to modulate the function of other cells as well as release from dying cells as a danger signal. The use of serum Hsp70 as a marker in diverse disease states and its possible use in prognosis are just being investigated. Therefore, Hsp70 holds promise as both a therapeutic strategy and a biomarker for severity of stress.
The authors thank Jenny Hu, Erin Reiland, and Jessica Howard (Secretaries, Department of Anesthesia, Stanford University School of Medicine, Stanford, California) for help in preparing the manuscript and figures.
Back to Top | Article Outline


1. Lindquist S, Craig EA: The heat-shock proteins. Annu Rev Genet 1988; 22:631–77

2. Welch WJ: Mammalian stress response: Cell physiology, structure/function of stress proteins, and implications for medicine and disease. Physiol Rev 1992; 72:1063–81

3. Morimoto RI, Kline MP, Bimston DN, Cotto JJ: The heat-shock response: Regulation and function of heat-shock proteins and molecular chaperones. Essays Biochem 1997; 32:17–29

4. Cotto JJ, Morimoto RI: Stress-induced activation of the heat-shock response: Cell and molecular biology of heat-shock factors. Biochem Soc Symp 1999; 64:105–18

5. Hartl FU, Hayer-Hartl M: Molecular chaperones in the cytosol: From nascent chain to folded protein. Science 2002; 295:1852–8

6. Bukau B, Weissman J, Horwich A: Molecular chaperones and protein quality control. Cell 2006; 125:443–51

7. Tavaria M, Gabriele T, Kola I, Anderson RL: A hitchhiker’s guide to the human Hsp70 family. Cell Stress Chaperones 1996; 1:23–8

8. Weiss YG, Maloyan A, Tazelaar J, Raj N, Deutschman CS: Adenoviral transfer of HSP-70 into pulmonary epithelium ameliorates experimental acute respiratory distress syndrome. J Clin Invest 2002; 110:801–6

9. Chen HW, Hsu C, Lu TS, Wang SJ, Yang RC: Heat shock pretreatment prevents cardiac mitochondrial dysfunction during sepsis. Shock 2003; 20:274–9

10. Giffard RG, Yenari MA: Many mechanisms for hsp70 protection from cerebral ischemia. J Neurosurg Anesthesiol 2004; 16:53–61

11. Jo SK, Ko GJ, Boo CS, Cho WY, Kim HK: Heat preconditioning attenuates renal injury in ischemic ARF in rats: Role of heat-shock protein 70 on NF-κB-mediated inflammation and on tubular cell injury. J Am Soc Nephrol 2006; 17:3082–92

12. Singleton KD, Wischmeyer PE: Effects of HSP70.1/3 gene knockout on acute respiratory distress syndrome and the inflammatory response following sepsis. Am J Physiol Lung Cell Mol Physiol 2006; 290:L956–61

13. Schmitt E, Gehrmann M, Brunet M, Multhoff G, Garrido C: Intracellular and extracellular functions of heat shock proteins: Repercussions in cancer therapy. J Leukoc Biol 2007; 81:15–27

14. Schroeder S, Lindemann C, Hoeft A, Putensen C, Decker D, von Ruecker AA, Stuber F: Impaired inducibility of heat shock protein 70 in peripheral blood lymphocytes of patients with severe sepsis. Crit Care Med 1999; 27:1080–4

15. Pittet JF, Lee H, Morabito D, Howard MB, Welch WJ, Mackersie RC: Serum levels of Hsp 72 measured early after trauma correlate with survival. J Trauma 2002; 52:611–7

16. Bruemmer-Smith S, Stuber F, Schroeder S: Protective functions of intracellular heat-shock protein (HSP) 70-expression in patients with severe sepsis. Intensive Care Med 2001; 27:1835–41

17. Ziegler TR, Ogden LG, Singleton KD, Luo M, Fernandez-Estivariz C, Griffith DP, Galloway JR, Wischmeyer PE: Parenteral glutamine increases serum heat shock protein 70 in critically ill patients. Intensive Care Med 2005; 31:1079–86

18. Dybdahl B, Slordahl SA, Waage A, Kierulf P, Espevik T, Sundan A: Myocardial ischaemia and the inflammatory response: Release of heat shock protein 70 after myocardial infarction. Heart 2005; 91:299–304

19. Dybdahl B, Wahba A, Lien E, Flo TH, Waage A, Qureshi N, Sellevold OF, Espevik T, Sundan A: Inflammatory response after open heart surgery: Release of heat-shock protein 70 and signaling through toll-like receptor-4. Circulation 2002; 105:685–90

20. Schmitt JP, Schunkert H, Birnbaum DE, Aebert H: Kinetics of heat shock protein 70 synthesis in the human heart after cold cardioplegic arrest. Eur J Cardiothorac Surg 2002; 22:415–20

21. Ganter MT, Ware LB, Howard M, Roux J, Gartland B, Matthay MA, Fleshner M, Pittet JF: Extracellular heat shock protein 72 is a marker of the stress protein response in acute lung injury. Am J Physiol Lung Cell Mol Physiol 2006; 291:L354–61

22. Singleton KD, Wischmeyer PE: Glutamine’s protection against sepsis and lung injury is dependent on heat shock protein 70 expression. Am J Physiol Regul Integr Comp Physiol 2007; 292:R1839–45

23. Hoehn B, Ringer TM, Xu L, Giffard RG, Sapolsky RM, Steinberg GK, Yenari MA: Overexpression of HSP72 after induction of experimental stroke protects neurons from ischemic damage. J Cereb Blood Flow Metab 2001; 21:1303–9

24. van der Weerd L, Lythgoe MF, Badin RA, Valentim LM, Akbar MT, de Belleroche JS, Latchman DS, Gadian DG: Neuroprotective effects of HSP70 overexpression after cerebral ischaemia: An MRI study. Exp Neurol 2005; 195:257–66

25. Rajdev S, Hara K, Kokubo Y, Mestril R, Dillmann W, Weinstein PR, Sharp FR: Mice overexpressing rat heat shock protein 70 are protected against cerebral infarction. Ann Neurol 2000; 47:782–91

26. Papadopoulos MC, Sun XY, Cao J, Mivechi NF, Giffard RG: Over-expression of HSP-70 protects astrocytes from combined oxygen-glucose deprivation. Neuroreport 1996; 7:429–32

27. Xu L, Giffard RG: HSP70 protects murine astrocytes from glucose deprivation injury. Neurosci Lett 1997; 224:9–12

28. Vayssier M, Polla BS: Heat shock proteins chaperoning life and death. Cell Stress Chaperones 1998; 3:221–7

29. Buzzard KA, Giaccia AJ, Killender M, Anderson RL: Heat shock protein 72 modulates pathways of stress-induced apoptosis. J Biol Chem 1998; 273:17147–53

30. Jaattela M: Heat shock proteins as cellular lifeguards. Ann Med 1999; 31:261–71

31. Kelly S, Yenari MA: Neuroprotection: Heat shock proteins. Curr Med Res Opin 2002; 18:s55–60

32. Takayama S, Reed JC, Homma S: Heat-shock proteins as regulators of apoptosis. Oncogene 2003; 22:9041–7

33. Yenari MA, Liu J, Zheng Z, Vexler ZS, Lee JE, Giffard RG: Antiapoptotic and anti-inflammatory mechanisms of heat-shock protein protection. Ann N Y Acad Sci 2005; 1053:74–83

34. Sun Y, Ouyang YB, Xu L, Chow AM, Anderson R, Hecker JG, Giffard RG: The carboxyl-terminal domain of inducible Hsp70 protects from ischemic injury in vivo and in vitro. J Cereb Blood Flow Metab 2006; 26:937–50

35. Leist M, Jaattela M: Four deaths and a funeral: From caspases to alternative mechanisms. Nat Rev Mol Cell Biol 2001; 2:589–98

36. Gogvadze V, Orrenius S: Mitochondrial regulation of apoptotic cell death. Chem Biol Interact 2006; 163:4–14

37. Thorburn A: Death receptor-induced cell killing. Cell Signal 2004; 16:139–44

38. Kroemer G, Martin SJ: Caspase-independent cell death. Nat Med 2005; 11:725–30

39. Culmsee C, Landshamer S: Molecular insights into mechanisms of the cell death program: Role in the progression of neurodegenerative disorders. Curr Alzheimer Res 2006; 3:269–83

40. Nylandsted J, Rohde M, Brand K, Bastholm L, Elling F, Jaattela M: Selective depletion of heat shock protein 70 (Hsp70) activates a tumor- specific death program that is independent of caspases and bypasses Bcl- 2. Proc Natl Acad Sci U S A 2000; 97:7871–6

41. Nylandsted J, Wick W, Hirt UA, Brand K, Rohde M, Leist M, Weller M, Jaattela M: Eradication of glioblastoma, and breast and colon carcinoma xenografts by Hsp70 depletion. Cancer Res 2002; 62:7139–42

42. Leist M, Single B, Castoldi AF, Kuhnle S, Nicotera P: Intracellular adenosine triphosphate (ATP) concentration: A switch in the decision between apoptosis and necrosis. J Exp Med 1997; 185:1481–6

43. Ankarcrona M: Glutamate induced cell death: Apoptosis or necrosis? Prog Brain Res 1998; 116:265–72

44. Green DR, Reed JC: Mitochondria and apoptosis. Science 1998; 281:1309–12

45. Fujimura M, Morita-Fujimura Y, Noshita N, Sugawara T, Kawase M, Chan PH: The cytosolic antioxidant copper/zinc-superoxide dismutase prevents the early release of mitochondrial cytochrome c in ischemic brain after transient focal cerebral ischemia in mice. J Neurosci 2000; 20:2817–24

46. Chan PH: Mitochondria and neuronal death/survival signaling pathways in cerebral ischemia. Neurochem Res 2004; 29:1943–9

47. Sims NR, Anderson MF: Mitochondrial contributions to tissue damage in stroke. Neurochem Int 2002; 40:511–26

48. Dugan LL, Kim-Han JS: Astrocyte mitochondria in in vitro models of ischemia. J Bioenerg Biomembr 2004; 36:317–21

49. Fiskum G, Rosenthal RE, Vereczki V, Martin E, Hoffman GE, Chinopoulos C, Kowaltowski A: Protection against ischemic brain injury by inhibition of mitochondrial oxidative stress. J Bioenerg Biomembr 2004; 36:347–52

50. Christophe M, Nicolas S: Mitochondria: A target for neuroprotective interventions in cerebral ischemia-reperfusion. Curr Pharm Des 2006; 12:739–57

51. Iijima T: Mitochondrial membrane potential and ischemic neuronal death. Neurosci Res 2006; 55:234–43

52. Matsumoto S, Friberg H, Ferrand-Drake M, Wieloch T: Blockade of the mitochondrial permeability transition pore diminishes infarct size in the rat after transient middle cerebral artery occlusion. J Cereb Blood Flow Metab 1999; 19:736–41

53. Plesnila N: Role of mitochondrial proteins for neuronal cell death after focal cerebral ischemia. Acta Neurochir Suppl 2004; 89:15–9

54. Matsumori Y, Northington FJ, Hong SM, Kayama T, Sheldon RA, Vexler ZS, Ferriero DM, Weinstein PR, Liu J: Reduction of caspase-8 and -9 cleavage is associated with increased c-FLIP and increased binding of Apaf-1 and Hsp70 after neonatal hypoxic/ischemic injury in mice overexpressing Hsp70. Stroke 2006; 37:507–12

55. Slee EA, Harte MT, Kluck RM, Wolf BB, Casiano CA, Newmeyer DD, Wang HG, Reed JC, Nicholson DW, Alnemri ES, Green DR, Martin SJ: Ordering the cytochrome c-initiated caspase cascade: Hierarchical activation of caspases-2, -3, -6, -7, -8, and -10 in a caspase-9-dependent manner. J Cell Biol 1999; 144:281–92

56. Chen J, Nagayama T, Jin K, Stetler RA, Zhu RL, Graham SH, Simon RP: Induction of caspase-3-like protease may mediate delayed neuronal death in the hippocampus after transient cerebral ischemia. J Neurosci 1998; 18:4914–28

57. Sugawara T, Noshita N, Lewen A, Gasche Y, Ferrand-Drake M, Fujimura M, Morita-Fujimura Y, Chan PH: Overexpression of copper/zinc superoxide dismutase in transgenic rats protects vulnerable neurons against ischemic damage by blocking the mitochondrial pathway of caspase activation. J Neurosci 2002; 22:209–17

58. Ferrer I, Planas AM: Signaling of cell death and cell survival following focal cerebral ischemia: Life and death struggle in the penumbra. J Neuropathol Exp Neurol 2003; 62:329–39

59. Manabat C, Han BH, Wendland M, Derugin N, Fox CK, Choi J, Holtzman DM, Ferriero DM, Vexler ZS: Reperfusion differentially induces caspase-3 activation in ischemic core and penumbra after stroke in immature brain. Stroke 2003; 34:207–13

60. Zhao H, Yenari MA, Cheng D, Sapolsky RM, Steinberg GK: Bcl-2 overexpression protects against neuron loss within the ischemic margin following experimental stroke and inhibits cytochrome c translocation and caspase-3 activity. J Neurochem 2003; 85:1026–36

61. Gill R, Soriano M, Blomgren K, Hagberg H, Wybrecht R, Miss MT, Hoefer S, Adam G, Niederhauser O, Kemp JA, Loetscher H: Role of caspase-3 activation in cerebral ischemia-induced neurodegeneration in adult and neonatal brain. J Cereb Blood Flow Metab 2002; 22:420–30

62. Kang SJ, Wang S, Hara H, Peterson EP, Namura S, Amin-Hanjani S, Huang Z, Srinivasan A, Tomaselli KJ, Thornberry NA, Moskowitz MA, Yuan J: Dual role of caspase-11 in mediating activation of caspase-1 and caspase-3 under pathological conditions. J Cell Biol 2000; 149:613–22

63. Kauppinen TM, Swanson RA: The role of poly(ADP-ribose) polymerase-1 in CNS disease. Neuroscience 2007; 145:1267–72

64. Garnier P, Ying W, Swanson RA: Ischemic preconditioning by caspase cleavage of poly(ADP-ribose) polymerase-1. J Neurosci 2003; 23:7967–73

65. Kauppinen TM, Swanson RA: Poly(ADP-ribose) polymerase-1 promotes microglial activation, proliferation, and matrix metalloproteinase-9-mediated neuron death. J Immunol 2005; 174:2288–96

66. Koh DW, Dawson TM, Dawson VL: Poly(ADP-ribosyl)ation regulation of life and death in the nervous system. Cell Mol Life Sci 2005; 62:760–8

67. Andrabi SA, Kim NS, Yu SW, Wang H, Koh DW, Sasaki M, Klaus JA, Otsuka T, Zhang Z, Koehler RC, Hurn PD, Poirier GG, Dawson VL, Dawson TM: Poly(ADP-ribose) (PAR) polymer is a death signal. Proc Natl Acad Sci U S A 2006; 103:18308–13

68. Steel R, Doherty JP, Buzzard K, Clemons N, Hawkins CJ, Anderson RL: Hsp72 inhibits apoptosis upstream of the mitochondria and not through interactions with Apaf-1. J Biol Chem 2004; 279:51490–9

69. Stankiewicz AR, Lachapelle G, Foo CP, Radicioni SM, Mosser DD: Hsp70 inhibits heat-induced apoptosis upstream of mitochondria by preventing Bax translocation. J Biol Chem 2005; 280:38729–39

70. Ravagnan L, Gurbuxani S, Susin SA, Maisse C, Daugas E, Zamzami N, Mak T, Jaattela M, Penninger JM, Garrido C, Kroemer G: Heat-shock protein 70 antagonizes apoptosis-inducing factor. Nat Cell Biol 2001; 3:839–43

71. Lee SH, Kwon HM, Kim YJ, Lee KM, Kim M, Yoon BW: Effects of hsp70.1 gene knockout on the mitochondrial apoptotic pathway after focal cerebral ischemia. Stroke 2004; 35:2195–9

72. Tsuchiya D, Hong S, Matsumori Y, Shiina H, Kayama T, Swanson RA, Dillman WH, Liu J, Panter SS, Weinstein PR: Overexpression of rat heat shock protein 70 is associated with reduction of early mitochondrial cytochrome C release and subsequent DNA fragmentation after permanent focal ischemia. J Cereb Blood Flow Metab 2003; 23:718–27

73. Matsumori Y, Hong SM, Aoyama K, Fan Y, Kayama T, Sheldon RA, Vexler ZS, Ferriero DM, Weinstein PR, Liu J: Hsp70 overexpression sequesters AIF and reduces neonatal hypoxic/ischemic brain injury. J Cereb Blood Flow Metab 2005; 25:899–910

74. Beere HM, Wolf BB, Cain K, Mosser DD, Mahboubi A, Kuwana T, Tailor P, Morimoto RI, Cohen GM, Green DR: Heat-shock protein 70 inhibits apoptosis by preventing recruitment of procaspase-9 to the Apaf-1 apoptosome. Nat Cell Biol 2000; 2:469–75

75. Jiang B, Xiao W, Shi Y, Liu M, Xiao X: Heat shock pretreatment inhibited the release of Smac/DIABLO from mitochondria and apoptosis induced by hydrogen peroxide in cardiomyocytes and C2C12 myogenic cells. Cell Stress Chaperones 2005; 10:252–62

76. Geissler A, Rassow J, Pfanner N, Voos W: Mitochondrial import driving forces: Enhanced trapping by matrix Hsp70 stimulates translocation and reduces the membrane potential dependence of loosely folded preproteins. Mol Cell Biol 2001; 21:7097–104

77. Geissler A, Krimmer T, Bomer U, Guiard B, Rassow J, Pfanner N: Membrane potential-driven protein import into mitochondria: The sorting sequence of cytochrome b(2) modulates the deltapsi-dependence of translocation of the matrix-targeting sequence. Mol Biol Cell 2000; 11:3977–91

78. Strub A, Lim JH, Pfanner N, Voos W: The mitochondrial protein import motor. Biol Chem 2000; 381:943–9

79. Samali A, Orrenius S: Heat shock proteins: Regulators of stress response and apoptosis. Cell Stress Chaperones 1998; 3:228–36

80. Voloboueva LA, Duan M, Ouyang Y, Emery JF, Stoy C, Giffard RG: Overexpression of mitochondrial Hsp70/Hsp75 protects astrocytes against ischemic injury in vitro. J Cereb Blood Flow Metab 2008; 28:1009–16

81. Ouyang YB, Xu LJ, Sun YJ, Giffard RG: Overexpression of inducible heat shock protein 70 and its mutants in astrocytes is associated with maintenance of mitochondrial physiology during glucose deprivation stress. Cell Stress Chaperones 2006; 11:180–6

82. Suzuki K, Murtuza B, Sammut IA, Latif N, Jayakumar J, Smolenski RT, Kaneda Y, Sawa Y, Matsuda H, Yacoub MH: Heat shock protein 72 enhances manganese superoxide dismutase activity during myocardial ischemia-reperfusion injury, associated with mitochondrial protection and apoptosis reduction. Circulation 2002; 106:I270–6

83. Kelly S, Zhang ZJ, Zhao H, Xu L, Giffard RG, Sapolsky RM, Yenari MA, Steinberg GK: Gene transfer of HSP72 protects cornu ammonis 1 region of the hippocampus neurons from global ischemia: Influence of Bcl-2. Ann Neurol 2002; 52:160–7

84. Yuan J, Yankner BA: Apoptosis in the nervous system. Nature 2000; 407:802–9

85. Merry DE, Korsmeyer SJ: Bcl-2 gene family in the nervous system. Annu Rev Neurosci 1997; 20:245–67

86. Martinou JC, Dubois-Dauphin M, Staple JK, Rodriguez I, Frankowski H, Missotten M, Albertini P, Talabot D, Catsicas S, Pietra C: Overexpression of BCL-2 in transgenic mice protects neurons from naturally occurring cell death and experimental ischemia. Neuron 1994; 13:1017–30

87. Hata R, Gillardon F, Michaelidis TM, Hossmann KA: Targeted disruption of the bcl-2 gene in mice exacerbates focal ischemic brain injury. Metab Brain Dis 1999; 14:117–24

88. Saleh A, Srinivasula SM, Balkir L, Robbins PD, Alnemri ES: Negative regulation of the Apaf-1 apoptosome by Hsp70. Nat Cell Biol 2000; 2:476–83

89. Park HS, Lee JS, Huh SH, Seo JS, Choi EJ: Hsp72 functions as a natural inhibitory protein of c-Jun N-terminal kinase. Embo J 2001; 20:446–56

90. Yaglom JA, Gabai VL, Meriin AB, Mosser DD, Sherman MY: The function of HSP72 in suppression of c-Jun N-terminal kinase activation can be dissociated from its role in prevention of protein damage. J Biol Chem 1999; 274:20223–8

91. Lee JS, Lee JJ, Seo JS: HSP70 deficiency results in activation of c-Jun N-terminal kinase, extracellular signal-regulated kinase, and caspase-3 in hyperosmolarity-induced apoptosis. J Biol Chem 2005; 280:6634–41

92. Becker EB, Howell J, Kodama Y, Barker PA, Bonni A: Characterization of the c-Jun N-terminal kinase-BimEL signaling pathway in neuronal apoptosis. J Neurosci 2004; 24:8762–70

93. Kuan CY, Burke RE: Targeting the JNK signaling pathway for stroke and Parkinson’s diseases therapy. Curr Drug Targets CNS Neurol Disord 2005; 4:63–7

94. Kuan CY, Whitmarsh AJ, Yang DD, Liao G, Schloemer AJ, Dong C, Bao J, Banasiak KJ, Haddad GG, Flavell RA, Davis RJ, Rakic P: A critical role of neural-specific JNK3 for ischemic apoptosis. Proc Natl Acad Sci U S A 2003; 100:15184–9

95. Kitamura C, Ogawa Y, Nishihara T, Morotomi T, Terashita M: Transient co-localization of c-Jun N-terminal kinase and c-Jun with heat shock protein 70 in pulp cells during apoptosis. J Dent Res 2003; 82:91–5

96. Davis RJ: Signal transduction by the JNK group of MAP kinases. Cell 2000; 103:239–52

97. Hunot S, Vila M, Teismann P, Davis RJ, Hirsch EC, Przedborski S, Rakic P, Flavell RA: JNK-mediated induction of cyclooxygenase 2 is required for neurodegeneration in a mouse model of Parkinson’s disease. Proc Natl Acad Sci U S A 2004; 101:665–70

98. Whitfield J, Neame SJ, Paquet L, Bernard O, Ham J: Dominant-negative c-Jun promotes neuronal survival by reducing BIM expression and inhibiting mitochondrial cytochrome c release. Neuron 2001; 29:629–43

99. Herdegen T, Claret FX, Kallunki T, Martin-Villalba A, Winter C, Hunter T, Karin M: Lasting N-terminal phosphorylation of c-Jun and activation of c-Jun N-terminal kinases after neuronal injury. J Neurosci 1998; 18:5124–35

100. Whitmarsh AJ, Kuan CY, Kennedy NJ, Kelkar N, Haydar TF, Mordes JP, Appel M, Rossini AA, Jones SN, Flavell RA, Rakic P, Davis RJ: Requirement of the JIP1 scaffold protein for stress-induced JNK activation. Genes Dev 2001; 15:2421–32

101. Im JY, Lee KW, Kim MH, Lee SH, Ha HY, Cho IH, Kim D, Yu MS, Kim JB, Lee JK, Kim YJ, Youn BW, Yang SD, Shin HS, Han PL: Repression of phospho-JNK and infarct volume in ischemic brain of JIP1-deficient mice. J Neurosci Res 2003; 74:326–32

102. Ciavarra RP, Goldman C, Wen KK, Tedeschi B, Castora FJ: Heat stress induces hsc70/nuclear topoisomerase I complex formation in vivo: Evidence for hsc70-mediated, ATP-independent reactivation in vitro. Proc Natl Acad Sci U S A 1994; 91:1751–5

103. Kroeger PE, Rowe TC: Interaction of topoisomerase 1 with the transcribed region of the Drosophila HSP 70 heat shock gene. Nucleic Acids Res 1989; 17:8495–509

104. Barati MT, Rane MJ, Klein JB, McLeish KR: A proteomic screen identified stress-induced chaperone proteins as targets of Akt phosphorylation in mesangial cells. J Proteome Res 2006; 5:1636–46

105. Rafiee P, Theriot ME, Nelson VM, Heidemann J, Kanaa Y, Horowitz SA, Rogaczewski A, Johnson CP, Ali I, Shaker R, Binion DG: Human esophageal microvascular endothelial cells respond to acidic pH stress by PI3K/AKT and p38 MAPK-regulated induction of Hsp70 and Hsp27. Am J Physiol Cell Physiol 2006; 291:C931–45

106. Iadecola C, Alexander M: Cerebral ischemia and inflammation. Curr Opin Neurol 2001; 14:89–94

107. Zheng Z, Yenari MA: Post-ischemic inflammation: Molecular mechanisms and therapeutic implications. Neurol Res 2004; 26:884–92

108. Wang X, Feuerstein GZ: The Janus face of inflammation in ischemic brain injury. Acta Neurochir Suppl 2004; 89:49–54

109. Wang J, Dore S: Inflammation after intracerebral hemorrhage. J Cereb Blood Flow Metab 2007; 27:894–908

110. Yenari MA, Kunis D, Sun GH, Onley D, Watson L, Turner S, Whitaker S, Steinberg GK: Hu23F2G, an antibody recognizing the leukocyte CD11/CD18 integrin, reduces injury in a rabbit model of transient focal cerebral ischemia. Exp Neurol 1998; 153:223–33

111. Zheng Z, Kim JY, Ma H, Lee JE, Yenari MA: Anti-inflammatory effects of the 70 kDa heat shock protein in experimental stroke. J Cereb Blood Flow Metab 2007; 28:53–63

112. Van Molle W, Wielockx B, Mahieu T, Takada M, Taniguchi T, Sekikawa K, Libert C: HSP70 protects against TNF-induced lethal inflammatory shock. Immunity 2002; 16:685–95

113. Margulis BA, Sandler S, Eizirik DL, Welsh N, Welsh M: Liposomal delivery of purified heat shock protein hsp70 into rat pancreatic islets as protection against interleukin 1 beta-induced impaired beta-cell function. Diabetes 1991; 40:1418–22

114. Ran R, Lu A, Zhang L, Tang Y, Zhu H, Xu H, Feng Y, Han C, Zhou G, Rigby AC, Sharp FR: Hsp70 promotes TNF-mediated apoptosis by binding IKK gamma and impairing NF-kappa B survival signaling. Genes Dev 2004; 18:1466–81

115. Feng X, Bonni S, Riabowol K: HSP70 induction by ING proteins sensitizes cells to tumor necrosis factor alpha receptor-mediated apoptosis. Mol Cell Biol 2006; 26:9244–55

116. Ding XZ, Fernandez-Prada CM, Bhattacharjee AK, Hoover DL: Over-expression of hsp-70 inhibits bacterial lipopolysaccharide-induced production of cytokines in human monocyte-derived macrophages. Cytokine 2001; 16:210–9

117. Beckman JS, Beckman TW, Chen J, Marshall PA, Freeman BA: Apparent hydroxyl radical production by peroxynitrite: Implications for endothelial injury from nitric oxide and superoxide. Proc Natl Acad Sci U S A 1990; 87:1620–4

118. Iadecola C: Bright and dark sides of nitric oxide in ischemic brain injury. Trends Neurosci 1997; 20:132–9

119. Zhu DY, Liu SH, Sun HS, Lu YM: Expression of inducible nitric oxide synthase after focal cerebral ischemia stimulates neurogenesis in the adult rodent dentate gyrus. J Neurosci 2003; 23:223–9

120. Feinstein DL, Galea E, Aquino DA, Li GC, Xu H, Reis DJ: Heat shock protein 70 suppresses astroglial-inducible nitric-oxide synthase expression by decreasing NFκB activation. J Biol Chem 1996; 271:17724–32

121. Robinson JM, Badwey JA: The NADPH oxidase complex of phagocytic leukocytes: A biochemical and cytochemical view. Histochem Cell Biol 1995; 103:163–80

122. Suh SW, Gum ET, Hamby AM, Chan PH, Swanson RA: Hypoglycemic neuronal death is triggered by glucose reperfusion and activation of neuronal NADPH oxidase. J Clin Invest 2007; 117:910–8

123. Park L, Anrather J, Girouard H, Zhou P, Iadecola C: Nox2-derived reactive oxygen species mediate neurovascular dysregulation in the aging mouse brain. J Cereb Blood Flow Metab 2007; 27:1908–18

124. Maridonneau-Parini I, Clerc J, Polla BS: Heat shock inhibits NADPH oxidase in human neutrophils. Biochem Biophys Res Commun 1988; 154:179–86

125. Polla BS, Stubbe H, Kantengwa S, Maridonneau-Parini I, Jacquier-Sarlin MR: Differential induction of stress proteins and functional effects of heat shock in human phagocytes. Inflammation 1995; 19:363–78

126. Rosenberg GA: Matrix metalloproteinases in neuroinflammation. Glia 2002; 39:279–91

127. Lee JE, Kim YJ, Kim JY, Lee WT, Yenari MA, Giffard RG: The 70 kDa heat shock protein suppresses matrix metalloproteinases in astrocytes. Neuroreport 2004; 15:499–502

128. Gilmore TD: Introduction to NF-κB: Players, pathways, perspectives. Oncogene 2006; 25:6680–4

129. Matthews JR, Hay RT: Regulation of the DNA binding activity of NF-kappa B. Int J Biochem Cell Biol 1995; 27:865–79

130. Guzhova IV, Darieva ZA, Melo AR, Margulis BA: Major stress protein Hsp70 interacts with NF-kB regulatory complex in human T-lymphoma cells. Cell Stress Chaperones 1997; 2:132–9

131. Wong HR, Ryan M, Wispe JR: The heat shock response inhibits inducible nitric oxide synthase gene expression by blocking I kappa-B degradation and NF-kappa B nuclear translocation. Biochem Biophys Res Commun 1997; 231:257–63

132. Chen H, Wu Y, Zhang Y, Jin L, Luo L, Xue B, Lu C, Zhang X, Yin Z: Hsp70 inhibits lipopolysaccharide-induced NF-κB activation by interacting with TRAF6 and inhibiting its ubiquitination. FEBS Lett 2006; 580:3145–52

133. Janssens S, Beyaert R: Functional diversity and regulation of different interleukin-1 receptor-associated kinase (IRAK) family members. Mol Cell 2003; 11:293–302

134. Kopp E, Medzhitov R: Recognition of microbial infection by Toll-like receptors. Curr Opin Immunol 2003; 15:396–401

135. Qian Y, Commane M, Ninomiya-Tsuji J, Matsumoto K, Li X: IRAK-mediated translocation of TRAF6 and TAB2 in the interleukin-1-induced activation of NFκB. J Biol Chem 2001; 276:41661–7

136. Seegers H, Grillon E, Trioullier Y, Vath A, Verna JM, Blum D: Nuclear factor-kappa B activation in permanent intraluminal focal cerebral ischemia in the rat. Neurosci Lett 2000; 288:241–5

137. Tytell M: Release of heat shock proteins (Hsps) and the effects of extracellular Hsps on neural cells and tissues. Int J Hyperthermia 2005; 21:445–55

138. Guzhova I, Kislyakova K, Moskaliova O, Fridlanskaya I, Tytell M, Cheetham M, Margulis B: In vitro studies show that Hsp70 can be released by glia and that exogenous Hsp70 can enhance neuronal stress tolerance. Brain Res 2001; 914:66–73

139. Robinson MB, Tidwell JL, Gould T, Taylor AR, Newbern JM, Graves J, Tytell M, Milligan CE: Extracellular heat shock protein 70: A critical component for motoneuron survival. J Neurosci 2005; 25:9735–45

140. Taylor AR, Robinson MB, Gifondorwa DJ, Tytell M, Milligan CE: Regulation of heat shock protein 70 release in astrocytes: Role of signaling kinases. Dev Neurobiol 2007; 67:1815–29

141. Edbladh M, Ekstrom PA, Edstrom A: Retrograde axonal transport of locally synthesized proteins, e.g., actin and heat shock protein 70, in regenerating adult frog sciatic sensory axons. J Neurosci Res 1994; 38:424–32

142. Sheller RA, Smyers ME, Grossfeld RM, Ballinger ML, Bittner GD: Heat-shock proteins in axoplasm: High constitutive levels and transfer of inducible isoforms from glia. J Comp Neurol 1998; 396:1–11

143. Broquet AH, Thomas G, Masliah J, Trugnan G, Bachelet M: Expression of the molecular chaperone Hsp70 in detergent-resistant microdomains correlates with its membrane delivery and release. J Biol Chem 2003; 278:21601–6

144. Hightower LE, Guidon PT Jr: Selective release from cultured mammalian cells of heat-shock (stress) proteins that resemble glia-axon transfer proteins. J Cell Physiol 1989; 138:257–66

145. Clayton A, Turkes A, Navabi H, Mason MD, Tabi Z: Induction of heat shock proteins in B-cell exosomes. J Cell Sci 2005; 118:3631–8

146. Thery C, Regnault A, Garin J, Wolfers J, Zitvogel L, Ricciardi-Castagnoli P, Raposo G, Amigorena S: Molecular characterization of dendritic cell-derived exosomes: Selective accumulation of the heat shock protein hsc73. J Cell Biol 1999; 147:599–610

147. Mathew A, Bell A, Johnstone RM: Hsp-70 is closely associated with the transferrin receptor in exosomes from maturing reticulocytes. Biochem J 1995; 308(pt 3):823–30

148. Gastpar R, Gehrmann M, Bausero MA, Asea A, Gross C, Schroeder JA, Multhoff G: Heat shock protein 70 surface-positive tumor exosomes stimulate migratory and cytolytic activity of natural killer cells. Cancer Res 2005; 65:5238–47

149. Pockley AG, Shepherd J, Corton JM: Detection of heat shock protein 70 (Hsp70) and anti-Hsp70 antibodies in the serum of normal individuals. Immunol Invest 1998; 27:367–77

150. Calderwood SK, Mambula SS, Gray PJ Jr, Theriault JR: Extracellular heat shock proteins in cell signaling. FEBS Lett 2007; 581:3689–94

151. Mambula SS, Calderwood SK: Heat shock protein 70 is secreted from tumor cells by a nonclassical pathway involving lysosomal endosomes. J Immunol 2006; 177:7849–57

152. Lancaster GI, Febbraio MA: Exosome-dependent trafficking of HSP70: A novel secretory pathway for cellular stress proteins. J Biol Chem 2005; 280:23349–55

153. Foster LJ, De Hoog CL, Mann M: Unbiased quantitative proteomics of lipid rafts reveals high specificity for signaling factors. Proc Natl Acad Sci U S A 2003; 100:5813–8

154. Li N, Shaw AR, Zhang N, Mak A, Li L: Lipid raft proteomics: Analysis of in-solution digest of sodium dodecyl sulfate-solubilized lipid raft proteins by liquid chromatography-matrix-assisted laser desorption/ionization tandem mass spectrometry. Proteomics 2004; 4:3156–66

155. Asea A, Rehli M, Kabingu E, Boch JA, Bare O, Auron PE, Stevenson MA, Calderwood SK: Novel signal transduction pathway utilized by extracellular HSP70: Role of toll-like receptor (TLR) 2 and TLR4. J Biol Chem 2002; 277:15028–34

156. Svensson PA, Asea A, Englund MC, Bausero MA, Jernas M, Wiklund O, Ohlsson BG, Carlsson LM, Carlsson B: Major role of HSP70 as a paracrine inducer of cytokine production in human oxidized LDL treated macrophages. Atherosclerosis 2006; 185:32–8

157. Vabulas RM, Ahmad-Nejad P, Ghose S, Kirschning CJ, Issels RD, Wagner H: HSP70 as endogenous stimulus of the Toll/interleukin-1 receptor signal pathway. J Biol Chem 2002; 277:15107–12

158. Lehner T, Wang Y, Whittall T, McGowan E, Kelly CG, Singh M: Functional domains of HSP70 stimulate generation of cytokines and chemokines, maturation of dendritic cells and adjuvanticity. Biochem Soc Trans 2004; 32:629–32

159. Triantafilou K, Triantafilou M, Ladha S, Mackie A, Dedrick RL, Fernandez N, Cherry R: Fluorescence recovery after photobleaching reveals that LPS rapidly transfers from CD14 to hsp70 and hsp90 on the cell membrane. J Cell Sci 2001; 114:2535–45

160. Gao B, Tsan MF: Endotoxin contamination in recombinant human heat shock protein 70 (Hsp70) preparation is responsible for the induction of tumor necrosis factor alpha release by murine macrophages. J Biol Chem 2003; 278:174–9

161. Bausinger H, Lipsker D, Ziylan U, Manie S, Briand JP, Cazenave JP, Muller S, Haeuw JF, Ravanat C, de la Salle H, Hanau D: Endotoxin-free heat-shock protein 70 fails to induce APC activation. Eur J Immunol 2002; 32:3708–13

162. Triantafilou M, Lepper PM, Briault CD, Ahmed MA, Dmochowski JM, Schumann C, Triantafilou K: Chemokine receptor 4 (CXCR4) is part of the lipopolysaccharide “sensing apparatus.” Eur J Immunol 2008; 38:192–203

163. Triantafilou M, Brandenburg K, Kusumoto S, Fukase K, Mackie A, Seydel U, Triantafilou K: Combinational clustering of receptors following stimulation by bacterial products determines lipopolysaccharide responses. Biochem J 2004; 381:527–36

164. Arispe N, De Maio A: ATP and ADP modulate a cation channel formed by Hsc70 in acidic phospholipid membranes. J Biol Chem 2000; 275:30839–43

165. Arispe N, Doh M, Simakova O, Kurganov B, De Maio A: Hsc70 and Hsp70 interact with phosphatidylserine on the surface of PC12 cells resulting in a decrease of viability. FASEB J 2004; 18:1636–45

166. Delneste Y, Magistrelli G, Gauchat J, Haeuw J, Aubry J, Nakamura K, Kawakami-Honda N, Goetsch L, Sawamura T, Bonnefoy J, Jeannin P: Involvement of LOX-1 in dendritic cell-mediated antigen cross-presentation. Immunity 2002; 17:353–62

167. Theriault JR, Adachi H, Calderwood SK: Role of scavenger receptors in the binding and internalization of heat shock protein 70. J Immunol 2006; 177:8604–11

168. Binder RJ, Blachere NE, Srivastava PK: Heat shock protein-chaperoned peptides but not free peptides introduced into the cytosol are presented efficiently by major histocompatibility complex I molecules. J Biol Chem 2001; 276:17163–71

169. Multhoff G, Pfister K, Gehrmann M, Hantschel M, Gross C, Hafner M, Hiddemann W: A 14-mer Hsp70 peptide stimulates natural killer (NK) cell activity. Cell Stress Chaperones 2001; 6:337–44

170. Gross C, Schmidt-Wolf IG, Nagaraj S, Gastpar R, Ellwart J, Kunz-Schughart LA, Multhoff G: Heat shock protein 70-reactivity is associated with increased cell surface density of CD94/CD56 on primary natural killer cells. Cell Stress Chaperones 2003; 8:348–60

171. Kovalchin JT, Wang R, Wagh MS, Azoulay J, Sanders M, Chandawarkar RY: In vivo delivery of heat shock protein 70 accelerates wound healing by up-regulating macrophage-mediated phagocytosis. Wound Repair Regen 2006; 14:129–37

172. van Eden W, van der Zee R, Prakken B: Heat-shock proteins induce T-cell regulation of chronic inflammation. Nat Rev Immunol 2005; 5:318–30

173. Aneja R, Odoms K, Dunsmore K, Shanley TP, Wong HR: Extracellular heat shock protein-70 induces endotoxin tolerance in THP-1 cells. J Immunol 2006; 177:7184–92

174. Pockley AG, Georgiades A, Thulin T, de Faire U, Frostegard J: Serum heat shock protein 70 levels predict the development of atherosclerosis in subjects with established hypertension. Hypertension 2003; 42:235–8

175. Zhu J, Quyyumi AA, Wu H, Csako G, Rott D, Zalles-Ganley A, Ogunmakinwa J, Halcox J, Epstein SE: Increased serum levels of heat shock protein 70 are associated with low risk of coronary artery disease. Arterioscler Thromb Vasc Biol 2003; 23:1055–9

176. Zheng Z, Kim JY, Ma H, Lee JE, Yenari MA: Anti-inflammatory effects of the 70 kDa heat shock protein in experimental stroke. J Cereb Blood Flow Metab 2007; 28:53–63

Cited By:

This article has been cited 19 time(s).

Current Drug Targets
microRNAs: Innovative Targets for Cerebral Ischemia and Stroke
Ouyang, YB; Stary, CM; Yang, GY; Giffard, R
Current Drug Targets, 14(1): 90-101.

Translational Stroke Research
Comparison of Three Hypothermic Target Temperatures for the Treatment of Hypoxic Ischemia: mRNA Level Responses of Eight Genes in the Piglet Brain
Olson, L; Faulkner, S; Lundstromer, K; Kerenyi, A; Kelen, D; Chandrasekaran, M; Aden, U; Olson, L; Golay, X; Lagercrantz, H; Robertson, NJ; Galter, D
Translational Stroke Research, 4(2): 248-257.
The effect of glutamine on cerebral ischaemic injury after cardiac arrest
Kim, KS; Suh, GJ; Kwon, WY; Lee, HJ; Jeong, KY; Jung, SK; Kwak, YH
Resuscitation, 84(9): 1285-1290.
Journal of Cerebral Blood Flow and Metabolism
Epigenetic mechanisms in cerebral ischemia
Schweizer, S; Meisel, A; Marschenz, S
Journal of Cerebral Blood Flow and Metabolism, 33(9): 1335-1346.
Journal of Clinical Investigation
The future of molecular chaperones and beyond
Giffard, RG; Macario, AJL; de Macario, EC
Journal of Clinical Investigation, 123(8): 3206-3208.
Ceftriaxone improves spatial learning and memory in chronic cerebral hypoperfused rats
Koomhin, P; Tilokskulchai, K; Tapechum, S
Scienceasia, 38(4): 356-363.
Expert Opinion on Therapeutic Targets
HSP 70 and atherosclerosis protector - or activator?
Bielecka-Dabrowa, A; Barylski, M; Mikhailidis, DP; Rysz, J; Banach, M
Expert Opinion on Therapeutic Targets, 13(3): 307-317.
Plos One
Helicobacter pylori-Induced Histone Modification, Associated Gene Expression in Gastric Epithelial Cells, and Its Implication in Pathogenesis
Ding, SZ; Fischer, W; Kaparakis-Liaskos, M; Liechti, G; Merrell, DS; Grant, PA; Ferrero, RL; Crowe, SE; Haas, R; Hatakeyama, M; Goldberg, JB
Plos One, 5(3): -.
ARTN e9875
Cell Biology and Toxicology
Hsp70 expression in monocytes from patients with peripheral arterial disease and healthy controls
Madden, J; Coward, JC; Shearman, CP; Grimble, RF; Calder, PC
Cell Biology and Toxicology, 26(3): 215-223.
High Dietary Taurine Reduces Apoptosis and Atherosclerosis in the Left Main Coronary Artery Association With Reduced CCAAT/Enhancer Binding Protein Homologous Protein and Total Plasma Homocysteine but not Lipidemia
Zulli, A; Lau, E; Wijaya, BPP; Jin, X; Sutarga, K; Schwartz, GD; Learmont, J; Wookey, PJ; Zinellu, A; Carru, C; Hare, DL
Hypertension, 53(6): 1017-U226.
Rejuvenation Research
Over-Expression of Heat Shock Protein 70 in Mice Is Associated with Growth Retardation, Tumor Formation, and Early Death
Vanhooren, V; Liu, XE; Desmyter, L; Fan, YD; Vanwalleghem, L; Van Molle, W; Dewaele, S; Praet, M; Contreras, R; Libert, C; Chen, CY
Rejuvenation Research, 11(6): 1013-1020.
Astrocyte Targeted Overexpression of Hsp72 or SOD2 Reduces Neuronal Vulnerability to Forebrain Ischemia
Xu, LJ; Emery, JF; Ouyang, YB; Voloboueva, LA; Giffard, RG
Glia, 58(9): 1042-1049.
American Journal of Rhinology & Allergy
Protein microarray analysis of nasal polyps from aspirin-sensitive and aspirin-tolerant patients with chronic rhinosinusitis
Zander, KA; Saavedra, MT; West, J; Scapa, V; Sanders, L; Kingdom, TT
American Journal of Rhinology & Allergy, 23(3): 268-272.
Journal of Cerebral Blood Flow and Metabolism
TAT-Hsp70-mediated neuroprotection and increased survival of neuronal precursor cells after focal cerebral ischemia in mice
Doeppner, TR; Nagel, F; Dietz, GPH; Weise, J; Tonges, L; Schwarting, S; Bahr, M
Journal of Cerebral Blood Flow and Metabolism, 29(6): 1187-1196.
Neurochemistry International
Responses of astrocyte to simultaneous glutamate and arachidonic acid treatment
Xu, ZY; Liu, HD; Lau, LT; Yingge, Z; Zhao, R; Tong, GL; Chan, PH; Yu, ACH
Neurochemistry International, 55(): 143-150.
British Journal of Surgery
Heat-shock protein 70 gene polymorphism is associated with the severity of diabetic foot ulcer and the outcome of surgical treatment
Mir, KA; Pugazhendhi, S; Paul, MJ; Nair, A; Ramakrishna, BS
British Journal of Surgery, 96(): 1205-1209.
Journal of Periodontal Research
Expression of heat shock proteins, Hsp70 and Hsp25, in the rat gingiva after irradiation with a CO2 laser in coagulation mode
Yamasaki, A; Ito, H; Yusa, J; Sakurai, Y; Okuyama, N; Ozawa, R
Journal of Periodontal Research, 45(3): 323-330.
Dental Traumatology
The expression of heat shock protein 70 in the dental pulp following trauma
Pileggi, R; Holland, GR
Dental Traumatology, 25(4): 426-428.
Molecular Immunology
Differential transcriptomic responses of Biomphalaria glabrata (Gastropoda, Mollusca) to bacteria and metazoan parasites, Schistosoma mansoni and Echinostoma paraensei (Digenea, Platyhelminthes)
Adema, CM; Hanington, PC; Lun, CM; Rosenberg, GH; Aragon, AD; Stout, BA; Richard, MLL; Gross, PS; Loker, ES
Molecular Immunology, 47(4): 849-860.
Back to Top | Article Outline

© 2008 American Society of Anesthesiologists, Inc.

Publication of an advertisement in Anesthesiology Online does not constitute endorsement by the American Society of Anesthesiologists, Inc. or Lippincott Williams & Wilkins, Inc. of the product or service being advertised.

Article Tools