Abstract
Object Retinal ischemia-reperfusion (I/R) injury is a common pathological process in many ophthalmic diseases; there are no effective therapeutic approaches available currently. Increasing evidence indicates that microglia mediated neuroinflammation plays an important role in the retinal I/R injury. In this study, we aimed to investigate the roles of chemokine receptor CXCR5 in the pathological process of retinal I/R injury model. Method Retinal I/R injury model was established in CXCR5 knockout and wild mice by the acute elevation of intraocular pressure (AOH) for 60 minutes, and the eyes were harvested for further analyses. The cellular location of CXCR5 was detected by immunofluorescence staining; the expressions of CXCR5 and CXCL13 after I/R injury were analyzed by quantitative RT-PCR. The retinal microglia were detected as stained for Iba1 (+). Leakage of inflammatory cells was observed on the H&E stained cryosections. The protein expression and quantification of zonula occludens (ZO-1) were determined by Western blotting and densitometry. Capillary degeneration was identified on the intact retinal vasculatures prepared by trypsin digestion. Results The number of activated microglia marked by Iba1 antibody in the retina was increased after retinal I/R injury in both KO and WT mice, more significant in KO mice. The leakage of inflammatory cells was observed largely at 2 days after injury, but there was no or little leakage at 7 days. The number of inflammatory cells (mainly neutrophils) was greater in CXCR5 KO mice than in WT mice, mainly located under internal limiting membrane. CXCR5 deficiency led to more ZO-1 degradation in CXCR5 KO mice compared to C57BL6 WT mice 2 days after reperfusion. The cellular capillaries were also significantly increased in the KO mice compared to the WT mice. Conclusion Our findings suggest that the chemokine receptor CXCR5 may protect retina from ischemia-reperfusion injury by its anti-inflammatory effects. Thus, CXCR5 may be a promising therapeutic target for the treatment of retinal I/R injury.
Highlights
Retinal ischemia-reperfusion (I/R) injury is a common pathological process in many ophthalmic diseases, including retinal vascular occlusion, glaucoma, and diabetic retinopathy [1, 2]
To investigate whether CXCR5 signaling pathway is implicated in retina, we examined the expression of CXCR5 and CXCL13, which is the only ligand for CXCR5 in a mouse model of retinal ischemiareperfusion injury induced by acute elevation of intraocular pressure (AOH)
Immunolocalization analysis released that the cellular location of CXCR5 was present in the ganglion cell layer (GCL) and outer nuclear layer (ONL) in noninjured retina
Summary
Retinal ischemia-reperfusion (I/R) injury is a common pathological process in many ophthalmic diseases, including retinal vascular occlusion, glaucoma, and diabetic retinopathy [1, 2]. The I/R damage is a dual process, in which timely restoration of blood flow after ischemia is very critical to reduce neuronal apoptosis; it results in local and systemic inflammatory responses and aggravates oxidative stress and inflammatory damage [3]. Increasing researches suggest that neuroinflammation plays a pivotal role in the pathogenesis of retinal I/R injury, which is typical of inflammatory responses induced by microglial proinflammatory activation [4,5,6,7]. Microglia activation is associated with increased cytokine expression and oxidative stress, which in turn leads to further activation
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