BACKGROUND: Hemorrhagic shock (HS) followed by an infection (“second hit”) can lead to severe systemic inflammatory response and multiple-organ failure. Studies have shown that resuscitation with hypertonic saline (HTS) can blunt the inflammatory response. We demonstrated that large doses of valproic acid (VPA, 300 mg/kg), a histone deacetylase inhibitor, improves survival in a rodent two-hit model (HS followed by cecal ligation and puncture [CLP]). In the present study, we examined whether combination of HTS with VPA would allow us to achieve survival advantage at a lower dose of VPA (200 mg/kg).
METHODS: Male Sprague-Dawley rats were subjected to HS (50% blood loss) and randomized into five groups (n = 7–8 per group) as follows: (1) isotonic sodium chloride solution (ISCS), (2) 7.5% saline, (3) VPA, (4) ISCS + VPA, and (5) HTS + VPA. After 24 hours, they underwent CLP, followed by the same doses of ISCS, HTS, and/or VPA and were monitored for 10 days. In a parallel experiment, blood, peritoneal irrigation fluid and lung homogenate were subjected to enzyme-linked immunosorbent assay 3 hours and 24 hours after CLP to measure myeloperoxidase activity and proinflammatory cytokines tumor necrosis factor α and interleukin 1β levels. Western blotting was performed to investigate the expression of pentraxin 3 protein in the lung homogenate at 24 hours after CLP. Hematoxylin and eosin staining of lungs at the 24 hours were performed to quantify the degree of acute lung injury.
RESULTS: HTS + VPA treatment significantly improved survival (87.5%), compared with the other groups (14.3%; p < 0.05), while attenuating peritoneal myeloperoxidase levels and proinflammatory cytokine tumor necrosis factor α and interleukin 1β levels in the serum, peritoneal cavity, and lung. The degree of acute lung injury and expression of pentraxin 3 in the lung were significantly reduced in the HTS + VPA group.
CONCLUSION: This is the first study to show that VPA and HTS can work synergistically to attenuate inflammation and improve survival in a lethal two-hit model.
From the Division of Trauma, Emergency Surgery and Surgical Critical Care (Z.L., Y.L., B.L., D.K.D., T.Z., W.C., P.Z., G.C.V., H.B.A.), Department of Surgery, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts; Department of Pathology (X.D.), Loyola University Medical Center, Maywood, Illinois; Department of Surgery (H.B.A.), University of Michigan, Ann Arbor, Michigan; and Emergency Department (W.C.), the First Hospital, China Medical University, Shenyang; and Department of Hepatobiliary Surgery (Z.L.), Xijing Hospital, Fourth Military Medical University, Xi’an, China.
Submitted: October 8, 2012, Revised: December 24, 2012, Accepted: December 26, 2012.
This study was presented at the 71st annual meeting of the American Association for the Surgery of Trauma, September 12–15, 2012, in Kauai, Hawaii.
Address for reprints: Hasan B. Alam, MD, Section of General Surgery, University of Michigan Hospital, 2920 Taubman Center/5331, 1500 E. Medical Center Dr, Ann Arbor, MI 48109-5331; email: email@example.com.