In CKD mice, a pronounced increase in cellular senescence was observed. The senescence-associated biomarker SA-β-gal exhibited a sharp elevation, rising nearly five-fold compared with controls. Consistent with this, cell cycle arrest proteins were markedly upregulated, with p21 increased by approximately 1.8-fold and p16^INK4a by 1.7-fold. In contrast, the expression of key cyclin-dependent kinases was strongly suppressed, including a 67% reduction in CDK1/2 and a 75% reduction in CDK4, confirming the establishment of a senescent phenotype in the myocardium.
Concomitantly, fibrotic remodeling was evident, as demonstrated by significant upregulation of fibrosis-associated proteins, including vimentin, α-SMA, and connective tissue growth factor (CTGF), in the uremic heart. Treatment with the senolytic cocktail dasatinib plus quercetin (D&Q) effectively attenuated both senescence- and fibrosis-related markers. Functional assessment by echocardiography further revealed that CKD mice displayed an enlarged left ventricular end-diastolic dimension (LVEDD), a hallmark of ventricular dilation, which was normalized following D&Q administration.
Inflammatory responses were also activated in the uremic heart, as indicated by increased levels of TNF-α, IL-1β, and IL-6. These cytokines were significantly reduced after D&Q treatment. Serum measurements confirmed elevated indoxyl sulfate (IS) levels in CKD mice. In vitro, exposure of primary cultured cardiomyocytes to 1 mM IS markedly induced p21, p16^INK4a, and γH2AX, accompanied by increased SA-β-gal activity and oxidative stress, indicating that IS directly drives cardiomyocyte senescence. Importantly, D&Q treatment reversed these IS-induced alterations.
Mechanistically, IS exposure sharply upregulated AhR, TGF-β, and NF-κB, while suppressing PGC-1α, a master regulator of mitochondrial biogenesis and oxidative metabolism. D&Q treatment restored this balance, reducing pro-fibrotic and pro-inflammatory signaling while rescuing PGC-1α expression. Collectively, these findings demonstrate that cardiomyocyte senescence, driven by IS accumulation and AhR-dependent signaling, is a critical mediator of fibrosis, inflammation, and functional impairment in uremic cardiomyopathy, and that senolytic therapy offers a promising strategy to mitigate these pathological changes.
Our findings demonstrate that senescent cardiomyocytes are key drivers of myocardial fibrosis and functional deterioration in CKD, acting primarily through indoxyl sulfate (IS)-mediated activation of the aryl hydrocarbon receptor (AhR) signaling pathway. Activation of AhR by IS promoted oxidative stress, chronic inflammation, and extracellular matrix deposition, thereby exacerbating structural remodeling of the heart. Importantly, intervention with the senolytic regimen of dasatinib and quercetin (D&Q) effectively suppressed AhR activation and its downstream pathological cascades. This led to a marked reduction in oxidative stress, pro-inflammatory cytokines, and fibrosis markers, accompanied by preservation of cardiac structure and function.
These results not only establish a mechanistic link between uremic toxin–induced senescence and cardiac dysfunction but also provide compelling evidence that targeting cellular senescence with senolytic therapy holds therapeutic potential for uremic cardiomyopathy. By attenuating the interplay between senescence, inflammation, and fibrosis, senolytic treatment may represent a novel strategy to improve cardiovascular outcomes in patients with CKD.
