Macrophage Iron Dyshomeostasis Promotes Aging-Related Kidney Fibrosis

Background: Renal aging, marked by the accumulation of senescent cells and chronic low-grade inflammation, leads to renal interstitial fibrosis and impaired function. However, the mechanism of macrophages in renal aging remains unclear. Here, by analyzing single-cell RNA sequencing data and constructing aging models in vivo and in vitro, we further explore the role and mechanism of macrophages in promoting kidney aging. Methods: We analyzed kidney single-cell RNA sequencing data (GSE198832) of C57BL/6J mice aged 8 weeks to 24 months to describe the dynamic changes in the proportion and function of kidney cell types during kidney aging. CellChat analysis uncovered changes in the intercellular communications between macrophages and tubular cells. SCENIC analysis revealed key regulons in a network of aging-related genes within kidney macrophages. Molecular docking and virtual screening revealed potential anti-aging agents. Results: Our findings elucidate the dynamic changes in the proportion of kidney cell types during renal aging and reveal that increased macrophage infiltration contributes to chronic low-grade inflammation, with these macrophages exhibiting senescence and activation of ferroptosis signaling. CellChat analysis indicates enhanced communications between macrophages and tubular cells during aging. Suppressing ferroptosis alleviates macrophage-mediated tubular partial epithelial-mesenchymal transition in vitro. Using SCENIC analysis, we infer Stat1 as a key age-related transcription factor promoting iron dyshomeostasis and ferroptosis in macrophages by repressing the expression of Pcbp1, an iron chaperone protein that inhibits ferroptosis. Knockdown of Pcbp1 aggravated the drug-induced macrophage senescence phenotypes, whereas overexpression of Pcbp1 alleviated macrophage senescence phenotypes. Through virtual screening and molecular docking from a library of anti-aging compounds, we construct a docking model targeting Pcbp1, which indicates that the natural small molecule compound Rutin can suppress macrophage senescence and ferroptosis by preserving Pcbp1. Conclusion: Our study underscores the crucial role of macrophage iron dyshomeostasis and ferroptosis in renal aging.Our results also suggest Stat1 and Pcbp1 as intervention targets in aging-related renal fibrosis, and highlight Rutin as a potential therapeutic agent in mitigating age-related renal chronic low-grade inflammation and fibrosis.