ObjectiveTo investigate the potential role of immune cells in retinal ischemia-reperfusion injury (RIRI)-associated diseases, employing Mendelian randomization (MR) and colocalization analysis. MethodsGenome-wide association study (GWAS) datasets of immune cells were obtained for conducting two-sample bidirectional MR analysis and colocalization analysis. A total of 731 immune cell phenotypes from the GWAS datasets were selected as exposure variables, and four RIRI-related diseases, namely diabetic retinopathy (DR), primary angle-closure glaucoma (PACG), retinal artery occlusion (RAO), and retinal vein occlusion (RVO), were chosen as outcome variables. The 731 immune cell phenotypes included seven cell types: B cells, classical dendritic cells, T cell maturation stages, monocytes, myeloid cells, TBNK cell group [T cells, B cells, and natural killer cells], and regulatory T cells. The inverse variance weighted (IVW) method was used to assess the causal relationship between immune cell phenotypes and RIRI-related diseases; colocalization analysis was performed to verify the possibility of shared causal variants between immune cell phenotypes and outcomes. ResultsThe IVW method analysis results showed that 117 were related to RIRI. After adjusting the false discovery rate (FDR) (PFDR＜0.05) and conducting reverse MR analysis, 19, 49, 37, 13, and 9 types of immune cell phenotypes were respectively associated with potential causal relationships with non-proliferative diabetic retinopathy (NPDR), proliferative diabetic retinopathy (PDR), PACG, RAO, and RVO. Among them, in the monocyte group, CD64 on CD14+ CD16+ monocyte significantly increased the risk of NPDR occurrence [odds ratio (OR)=1.544, 95% confidence interval (CI) 1.184-2.014, P=0.011], and CX3CR1 on monocyte significantly decreased the risk of NPDR occurrence (OR=0.823, 95% CI 0.727-0.933, P=0.012); in the TBNK cell group, CD4+ CD8dim% T cells significantly increased the risk of PACG occurrence (OR=1.262, 95%CI 1.075-1.483, P=0.025), and CD8 on EM CD8+ T cells was a risk factor for PACG occurrence (OR=1.156, 95%CI 1.049-1.275, P=0.026). The colocalization analysis results showed that 32 types of immune cell phenotypes had significant common causal variant signals with outcome variables (posterior probability H4＞0.8), located at 14 gene loci. Five immune cell phenotypes related to B-cell activating factor receptors and PDR were jointly located at the CENPM and TNFRSF13C gene loci. the specific T cell subsets CD45RA-CD4+ T cells and cytotoxic T cell phenotype CD28+CD45RA-CD8dim T cells (a type of memory CD8dim T cell) were colocalized with PACG at the PTPRC gene. The CD33 and RVO on myeloid cell phenotype monocyte-like myeloid-derived suppressor cells are jointly located at the CD33 locus (rs3865444) of their encoding gene. ConclusionMR and colocalization analysis results reveal complex genetic causal relationships between multiple immune cell phenotypes and four RIRI-related diseases.
CD4+ T cells play a dual role in both the protection and injury of retinal ganglion cells (RGC), participating in the critical immunopathological processes associated with retinal ischemia reperfusion injury (RIRI). T helper (Th) 1 and Th17 cells drive retinal inflammation by secreting pro-inflammatory cytokines, leading to RGC damage. In contrast, Th2 and regulatory T (Treg) cells secrete anti-inflammatory factors that modulate immune responses and reduce inflammation, thereby playing a crucial role in protecting RGC. However, under certain disease conditions, their roles may be reversed. Additionally, an imbalance between Th1 and Th2 cells, specifically the imbalance in the cytokines they secrete can influence disease progression. Therefore, a deeper understanding of the complex functions of CD4+ T cells and their subsets in both protecting and damaging retinal health is essential for immune-targeted therapies for RIRI.
ObjectiveTo observe the effects of overexpression of S100A4 protein on retinal capillary cells and retinal ganglion cells (RGC) after retinal ischemia-reperfusion injury (RIRI). MethodsOne hundred healthy adult male C57BL/6 mice were randomly divided into normal control group (group C), RIRI group, adeno-associated virus (AAV2)-S100A4 green fluorescent protein (GFP) intravitreal injection group (group S), RIRI+AAV2-GFP intravitreal injection group (group GIR), and RIRI+AAV2-S100A4-GFP intravitreal injection group (group SIR), with 20 mice in each group. The RIRI model was established using the high intraocular pressure anterior chamber method in the RIRI, GIR and SIR groups of mice. Eyes were enucleated 3 days after modelling by over anaesthesia. The number of retinal capillary endothelial cells and pericytes in the retinal capillaries of mice in each group was observed by retinal trypsinised sections and hematoxylin-eosin and periodic acid-Schiff staining; immunofluorescence staining was used to observe endothelial cell, pericyte coverage and RGC survival; The relative expression of Toll-like receptor 4 (TLR4), p38 MAPK and nuclear factor erythroid 2-related factor 2 (NRF2) in retinal tissues was measured by Western blot. One-way analysis of variance was used to compare data between groups. ResultsThree days after modeling, the endothelial cell to pericyte ratio in group C was compared with group S and SIR, and the difference was not statistically significant (F=106.30, P＞0.05); the SIR group was compared with group RIRI and GIR, and the difference was statistically significant (F=106.30, P＜0.000 1). Comparison of endothelial cell coverage in each group, the difference was not statistically significant (F=3.44, P＞0.05); compared with the pericyte coverage in group C, the RIRI group and the GIR group were significantly lower, and the difference was statistically significant (F=62.69, P＜0.001). Compared with the RGC survival rate in group C, it was significantly lower in RIRI and GIR groups, and the difference was statistically significant (F=171.60, P＜0.000 1); compared with RIRI and GIR groups, the RGC survival rate in SIR group was significantly higher, and the difference was statistically significant (F=171.60, P＜0.000 1). The relative expression levels of TLR4, p38 and NRF2 proteins were statistically significant among all groups (F=42.65, 20.78, 11.55; P＜0.05). ConclusionsPericytes are more sensitive to ischemia than endothelial cells after retinal RIRI in mice, and early vascular cell loss is dominated by pericytes rather than endothelial cells. The overexpression of S100A4 protein protects against loss of pericytes and RGC after RIRI by inhibiting the TLR4/p38/NRF2 signaling pathway.