Expression Levels of Aqueous Humor Cytokines in Pediatric Patients With Incontinentia Pigmenti : The Asia-Pacific Journal of Ophthalmology

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Expression Levels of Aqueous Humor Cytokines in Pediatric Patients With Incontinentia Pigmenti

Peng, Jie MD*; Zou, Yihua MD*; Zhang, Xiang MD*; Si, Dayong PhD; Xu, Yu MD, PhD*; Zhao, Peiquan MD, PhD*

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Asia-Pacific Journal of Ophthalmology 12(2):p 264-265, March/April 2023. | DOI: 10.1097/APO.0000000000000507
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Incontinentia pigmenti (IP) is a rare X-linked hereditary disease caused by NEMO gene mutation. IP-associated retinopathy (IPR) was classified into 5 stages.1 No report focused on the levels of intraocular cytokines in IPR patients. We measured the aqueous humor cytokines in pediatric IPR eye and analyzed their associations with IPR severity, hoping to provide new insights on pathogenesis and lay the theoretical foundations for treatment.

Materials and Methods

Between March 2015 and March 2017, aqueous humor of eyes receiving intraocular treatment (8 eyes of 6 IPR patients, 18 eyes of 12 congenital cataract patients as control) was enrolled. IPR stages, study design, and procedures followed our previous study1,2 (Supplemental Digital Content 1, Materials and Methods, http://links.lww.com/APJO/A128).

Results

Demographic information and fundus images were collected (Supplemental Digital Content 2, http://links.lww.com/APJO/ A129 and Supplemental Digital Content 3, http://links.lww.com/APJO/A130). Twenty-two tested cytokines concentrations were summarized (Table 1). Three [vascular endothelial growth factor (VEGF), IP-10, intercellular cell adhesion molecule-1 (ICAM-1 )] were significantly higher and 2 [interleukin (IL)-4, granulocyte colony-stimulating factor (G-CSF)] were lower in IPR patients than the control group (P < 0.05). VEGF, IL-8, IP-10 (Interferon-inducible protein), ICAM-1 were significantly increasing and IL-4, G-CSF were significantly decreasing in parallel with increasing IPR stages (P< 0.05).

Table 1 - Aqueous Humor Cytokine Concentrations (pg/mL) in the IPR Group and the Control Group
IPR Stages of IPR
Cytokines Stage 2 (n = 2), Mean Stage 3 (n = 4), Mean Stage 4 (n = 2), Mean P value Between IPR Subgroups Total (n = 8) Control Group (n = 18) LOD P value Between IPR Group and Control Group r P value§
IL-10 0 1.39 0.065 0.374 0.00 (0.00,1.44) 0.00 (0.00, 2.19) 0.1 0.311* −0.197 0.334
IL-6 5.25 7.6075 7.7 0.327 7.04 ±4.27 0.93 (0.40, 53.32) 1.6 0.08* 0.367 0.065
bFGF 3.875 13.54 11.75 0.513 6.83 ±10.97 13.01 ±6.73 3.4 0.51 −0.135 0.509
IL-lβ 0 2.0425 0.31 0.194 0.00 (0.00, 2.37) 1.05 ± 1.12 2.3 0.16* −0.263 0.194
TNF-α 0 2.82 1.62 0.147 0.00 (0.00, 3.22) 3.24 ±1.77 3.4 0.062* −0.329 0.101
VEGF 225.005 243.6625 191.705 0.024 226.01 ±86.60 23.93 (16.83, 68.24) 4.5 0.001 * 0.592 0.001
[FN-γ 0 2.735 1.44 0.161 0.00 (0.00, 4.07) 3.00 ±1.48 0.8 0.115* −0.284 0.159
GM-CSF 0 1.3825 0.225 0.174 0.00 (0.00, 1.73) 1.18 ± 1.05 1.6 0.129* −0.288 0.154
MlP-lα 0 0.9575 0.525 0.276 0.00 (0.00, 1.32) 0.28 (0.05, 0.82) 0.2 0.461* −0.09 0.661
IL-2 0 5.165 2.975 0.11 3.33 ±4.64 4.81 ±2.63 11.2 0.31* −0.271 0.181
IL-5 0 0.615 0.555 0.271 0.00 (0.00, 1.06) 0.62 ±0.36 1.1 0.238* −0.187 0.361
IL-lα 0 0.765 0 0.307 0.00 (0.00, 0.34) 0.00 (0.00, 0.00) 1.0 0.724* 0.111 0.590
IL-4 0.03 0.825 0.585 0.015 0.57 ±0.42 1.12 ±O.29 1.4 0.01 −0.546 0.004
IL-8 13.375 6.43 24.715 0.115 12.74±11.37 12.46 ±27.20 1.2 0.98 0.438 0.025
IP-10 106.805 168.2025 176.63 0.182 154.96±lll.20 54.58 (8.29, 127.46) 0.5 0.041 * 0.434 0.027
G-CSF 0.1 0.825 0.615 0.05 0.59 ± 0.56 1.21 (0.87, 1.37) 1.6 0.019 * −0.429 0.029
MCP-1 381.925 213.455 738.31 0.303 280.63 (192.25, 445.88) 408.36 (219.01, 780.87) 1.3 0.531* −0.118 0.565
RANTES 1.905 0.145 0.17 0.284 0.14 (0.00, 0.33) 0.47 (0.13, 1.56) 0.0 0.09* −0.365 0.066
lL-12 0.245 0.0075 0 0.599 0.00 (0.00, 0.18) 0.00 (0.00, 0.17) 0.1 0.605* −0.163 0.427
Fractalkine 23.945 11.5925 4.145 0.136 8.70 ± 9.82 4.32 (2.26, 11.25) 22.3 0.144* 0.227 0.266
VCAM-1 16321.72 3232.4225 13423.49 0.072 5515.540 ±7873.21 2097.26 (650.16, 7734.86) 12.2 0.41* 0.388 0.050
lCAM-1 1670.56 669.665 1669.84 0.043 858.080 ±759.11 173.66 (18.53, 528.14) 25.7 0.008 * 0.512 0.007
Values in bold font are statistically significant at P < 0.05.
bFGF indicates basic fibroblast growth factor; G-CSF, granulocyte colony-stimulating factor; GM-CSF, granulocyte-macrophage colony-stimulating factor; ICAM, intercellular cell adhesion molecule; IFN-γ, interferon-γ; IL, interleukin; IP-10, interferon-inducible protein-10; IPR, incontinentia pigmenti-associated retinopathy; LOD, limit of detection; MCP-1, monocyte chemoattractant protein-1; MlP-lα, macrophage inflammatory protein-lα; RANTES, regulated upon the activation of normal T cell expressed and secreted; TNF-α, tumor necrosis factor-α; VCAM, vascular cell adhesion molecule; VEGF, vascular endothelial growth factor.
*Mann-Whitney U test.
Student t test.
Kruskal-Wallis igtest.
§Spearman correlation test.

Discussion

NEMO protein, product of NEMO gene, is a regulatory subunit to activate nuclear factor kappa B (NF-kB), which plays a central role in the regulation of immune functions.3 NF-kB activations resulted in the resistance to transforming growth factor (TGF)-β-mediated suppression of IL-4 signaling.4 In IPR patients, malfunctional NF-kB results in low expression of IL-4.

ICAM-1 and VCAM-1 are major adhesion molecules, expressing during intraocular inflammation and destructing blood-retinal barrier. VCAM-1 (P = 0.05) and ICAM-1 (P = 0.007) significantly increased in parallel with increasing IPR stages, which may be responsive to the pathological change of vascular permeability and leakage as common in IPR.

G-CSF has neuroprotective and antiinflammation effects during retinal ischemia.5 G-CSF decreased in IPR groups, associating with disease severity, which led to dysfunction of retinal pigment epithelium cells and photoreceptor and retinal ganglion cell death. The decline of G-CSF may be an indicator of IPR deterioration.

Inflammatory cytokines, including IL-6, IL-8, monocyte chemoattractant protein-1, macrophage inflammatory protein-1a, and IP-10, were reported to be involved in ocular angiogenic activities and inflam-mation.6,7 Retinal pigment epithelium cells produce IP-10 and IL-8 in response to stimulation of proinflammatory cytokines and T-lymphocyte secretions. The IL-6 (P = 0.08) is elevated in IPR group, and IL-8 and IP-10 are increased and linearly associated with increased IPR severity (P < 0.05). This implies T-lymphocyte infiltration and stimulation, and its mediated inflammation may be involved in the pathogenesis of IPR.

Elevation of VEGF led to pathologic changes of vascular permeability, development of neovascularization and retinal detachment.2 VEGF is linearly associated with increased IPR severity (P = 0.001), and an indicator for bad prognosis. This laid the theoretical foundation for anti-VEGF therapy. Considering elevated VEGF concentration in the stage 2 IPR without NV, the peripheral avascular zone could upregulate VEGF levels indicating need for ablations. In severe stage 2 case with dilated or tortuous vessels, anti-VEGF therapy with laser treatment may offer a better choice.

These altered cytokines are involved with activation of inflammation, angiogenesis, damage on the retina, and blood-retina breakdown in pathogenesis of IPR. The retinal vasculopathy was primary retinal changes of IPR.1 We hypothesize inflammation of the retinal vessels, possibly caused by T cell-mediated inflammation, could be the first pathogenesis followed by vascular occlusion or malformation, VEGF upregulation, vitreous hemorrhage, and tractional retinal detachment. Our results also implied inflammatory cytokines and VEGF elevations may be involved in the pathological changes of IPR. Considering this, anti-inflammation agents, anti-VEGF agents, laser ablations, or a combination may offer a potential treatment for IPR.

Conclusions

Elevated levels of VEGF, IP-10, ICAM-1 and decreased levels of IL-4 and G-CSF may be associated with the pathogenesis of IPR. T-lymphocyte infiltration and stimulation may play a role in IPR. Proinflammatory and proangiogenic cytokines may be potential therapeutic targets for IPR.

References

1. Peng J, Zhang Q, Long X, et al. Incontinentia pigmenti-associated ocular anomalies of paediatric incontinentia pigmenti patients in China. Acta Ophthalmol. 2019;97:265–272.
2. Liang T, Xu Y, Zhu X, et al. Aqueous humour cytokines profiles in eyes with Coats disease and the association with the severity of the disease. BMC Ophthalmol. 2020;20:178.
3. Ding Y, Fan Z, Yao B, et al. Nanoparticle-based fluorescence probe for detection of NF-kB transcription factor in single cell via steric hindrance. Mikrochim Acta. 2021;188:226.
4. Yamamoto T, Imoto S, Sekine Y, et al. Involvement of NF-kappaB in TGF-beta-mediated suppression of IL-4 signaling. Biochem Biophys Res Commun. 2004;313:627–634.
5. Kojima H, Otani A, Oishi A, et al. Granulocyte colony-stimulating factor attenuates oxidative stress-induced apoptosis in vascular endothelial cells and exhibits functional and morphologic protective effect in oxygen-induced retinopathy. Blood. 2011;117:1091–1100.
6. Ghasemi H. Roles of IL-6 in ocular inflammation: a review. Ocul Immunol Inflamm. 2018;26:37–50.
7. Elner SG, Delmonte D, Bian ZM, et al. Differential expression of retinal pigment epithelium (RPE) IP-10 and interleukin-8. Exp Eye Res. 2006;83:374–379.
Keywords:

aqueous humor; cytokine; incontinentia pigmenti; retinopathy

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