Phenylacetylglutamine is associated with diabetic retinopathy via transgelin-mediated ferroptosis in hyperglycemic retinal epithelial cells

Hyperglycemia is a pivotal risk factor in the pathogenesis of diabetic retinopathy (DR), with accumulating evidence implicating the intestinal microbial metabolite phenylacetylglutamine (PAGln) in disease progression. However, the precise mechanisms underlying PAGln's role in DR remain incompletely understood. This study aimed to investigate the effects of PAGln on hyperglycemia-induced retinal pigment epithelial (RPE) cell dysfunction, with a focus on Ferroptosis as a potential mechanistic pathway. Clinical analysis via enzyme-linked immunosorbent assay (ELISA) revealed significantly elevated serum PAGln levels in DR patients compared to healthy controls (11.09 ± 9.80 vs. 2.75 ± 2.56 nmol/mL, P < 0.01), which exhibited a strong correlation with oxidative stress markers (MDA, H₂O₂) and disease severity. An in vitro DR model was established by exposing ARPE-19 cells to high glucose (HG), followed by PAGln treatment. Comprehensive analyses demonstrated that PAGln exacerbated oxidative stress (elevated ROS and MDA, reduced GSH/SOD), induced iron overload (Fe²⁺), promoted lipid peroxidation, and suppressed GPX4 expression, all hallmark features of Ferroptosis. Ferrostatin-1 (Fer-1), a Ferroptosis inhibitor, mitigated these effects, restoring cellular viability and GPX4 levels. Integrative mechanistic studies, including RNA Sequencing and RT-qPCR, identified transgelin (TAGLN) as a critical mediator upregulated by PAGln. Knockdown of TAGLN alleviated Ferroptosis, reduced oxidative damage, and restored cellular viability. Collectively, these findings suggest a potential involvement of the PAGln-TAGLN-ferroptosis pathway in DR progression, providing new insights into the metabolic regulation of retinal degeneration and potential therapeutic targets.

Diabetic retinopathy; Ferroptosis; Phenylacetylglutamine; Retinal pigment epithelial cells; TAGLN.