Rorex Colin, Cardona Sandra M, Church Kaira A, Rodriguez Derek, Vanegas Difernando, Saldivar Reina A, El-Sheikh Amira, Wang Yufeng, Gyoneva Stefka, Cotleur Anne C, Cardona Astrid E
Department of Molecular Microbiology and Immunology, The University of Texas at San Antonio, San Antonio, TX 78249, USA.
South Texas Center for Emerging Infectious Diseases, The University of Texas at San Antonio, San Antonio, TX 78249, USA.
Int J Mol Sci. 2025 Jan 28;26(3):1131. doi: 10.3390/ijms26031131.
Diabetic retinopathy (DR) causes vision loss due to sustained inflammation and vascular damage. The vascular damage is evident by fibrinogen leakage, angiogenesis, and hypoxia. Neuronal regulation of microglia via the CX3CL1 (Fractalkine or FKN)-CX3CR1 pathway plays a significant role in retinal pathology. Defects in FKN or CX3CR1 exacerbate inflammation, vascular damage, and vision impairment. However, the contribution of hypoxic astrocytes to the pathological process of DR is unclear. A hypoxic model (7 days of systemic 7.5% O) was utilized to induce retinal damage in adult mice in the absence of systemic inflammatory signals. This model induced vascular and microglial responses similar to 10 weeks of STZ-induced hyperglycemia. The goal of this study is to characterize retinal damage in WT and mice with defects in the FKN-CX3CR1 signaling axis and hence assess the impact of the microglial inflammatory responses to hypoxic retinopathy. Tissues were analyzed by immunostaining, RNA sequencing, and cytokine quantification. We found that CX3CR1 deficiency in hypoxic animals induced reactive astrogliosis and that Müller glial responses to hypoxia and systemic inflammation were dependent on FKN signaling. Exacerbated microglial reactivity to hypoxic conditions significantly altered the expression of HIF transcripts. Microglial dysregulation was found to reduce the anti-inflammatory response to hypoxic conditions, downregulate hypoxia-responsive gene expression, and restrained LPS-induced inflammatory responses. We found that microglia dysregulation alters the hypoxic response by inhibiting the upregulation of HIF2α/3α, increasing CD31 immunoreactivity, and altering the expression of ECM-associated transcripts such as type I, III, and XVIII collagens to hypoxic conditions.
糖尿病视网膜病变（DR）由于持续的炎症和血管损伤导致视力丧失。血管损伤表现为纤维蛋白原渗漏、血管生成和缺氧。通过CX3CL1（趋化因子或FKN）-CX3CR1途径对小胶质细胞进行神经元调节在视网膜病理中起重要作用。FKN或CX3CR1的缺陷会加剧炎症、血管损伤和视力损害。然而，缺氧星形胶质细胞对DR病理过程的贡献尚不清楚。利用缺氧模型（全身7.5%氧气，持续7天）在无全身炎症信号的情况下诱导成年小鼠视网膜损伤。该模型诱导的血管和小胶质细胞反应类似于10周链脲佐菌素诱导的高血糖症。本研究的目的是表征野生型和FKN-CX3CR1信号轴存在缺陷的小鼠的视网膜损伤，从而评估小胶质细胞炎症反应对缺氧性视网膜病变的影响。通过免疫染色、RNA测序和细胞因子定量分析组织。我们发现，缺氧动物中CX3CR1缺陷诱导了反应性星形胶质细胞增生，并且Müller胶质细胞对缺氧和全身炎症的反应依赖于FKN信号。小胶质细胞对缺氧条件的反应性增强显著改变了HIF转录本的表达。发现小胶质细胞失调会降低对缺氧条件的抗炎反应，下调缺氧反应基因表达，并抑制脂多糖诱导的炎症反应。我们发现，小胶质细胞失调通过抑制HIF2α/3α的上调、增加CD31免疫反应性以及改变缺氧条件下I型、III型和XVIII型胶原蛋白等细胞外基质相关转录本的表达来改变缺氧反应。
