A Comprehensive Analysis of Sex-Biased Gene Expression in the Aging Human Retina Through a Combination of Single-Cell and Bulk RNA Sequencing

Purpose: Previous studies have reported divergent sexual responses to aging; however, specific variations in gene expression between aging males and females and their potential association with age-related retinal diseases remain unclear. This study collected data from public databases and developed a comprehensive comparison of retina between aging females and males. Methods: Single-cell RNA (scRNA) and bulk RNA sequencing data of the aging retina from females and males in public databases were utilized for integrated analysis to investigate sex-biased expression in retina. Additionally, in vitro experiments were conducted on individuals with retinitis pigmentosa (RP) to validate the sex difference in degenerative retina. Results: Bulk RNA analysis revealed sex-biased expression of specific genes in retina of aging individuals, with immune pathway-related genes exhibiting higher expression in females compared to males. The scRNA analysis demonstrated that sex-biased gene expression was cell-type specific in aging retina. Furthermore, susceptibility genes for age-related macular degeneration and RP exhibited variation across different cell types and sexes. Cell-to-cell communication unveiled an increased interaction associated with TGFB1, CCL7, and VEGFA in Müller glia, microglia, and astrocytes of female retina. Notably, we observed female-biased chemokine expression in microglia contributing to heightened susceptibility to immune inflammation in female retina. Finally, we confirmed a more pronounced inflammatory response during degeneration in female rd10 mouse retina compared to males. Conclusions: This study provides a comprehensive comparison of retina between females and males in healthy aging human retina and highlights the significance of sex as an influential factor in retinal diseases.