Cellular senescence is recognized as a key mechanism contributing to maladaptive renal recovery and the development of fibrosis after acute kidney injury (AKI). Intermittent fasting (IF), a non-pharmacological dietary strategy, influences aging pathways and tissue homeostasis; however, its contribution to kidney fibrosis is still not well characterized. This study aimed to evaluate how IF influences renal fibrosis and cellular senescence using a murine model of AKI resulting from ischemia-reperfusion injury (IRI). Male C57BL/6 mice underwent unilateral IRI, followed by assignment of the IF group to a 5:2 schedule incorporating two 24-h fasts each week for eight weeks. Animals were divided into four groups: sham, IF, IRI, and IF + IRI. Two months after surgery, the IRI group developed pronounced tubulointerstitial fibrosis, while fibrosis was markedly attenuated in the IF + IRI group. Molecular analyses revealed that IF reduced protein expression of p21 and downregulated Cdkn1a and Cdkn2a transcripts, two key senescence markers. Furthermore, IF suppressed the expression of senescence-associated secretory phenotype (SASP) cytokines, including TNF-α, TGF-β, IL-6, IL-1α, and IL-1β. In parallel, IF restored the expression of major metabolic regulators related to energy homeostasis, such as SIRT1, phosphorylated AMPK, and PGC-1α. Collectively, these findings demonstrate that IF confers protection against renal fibrosis after IRI-induced AKI, and suggest that its beneficial effects may be mediated, at least in part, through the inhibition of cellular senescence and the enhancement of metabolic resilience.
