Resolvin D1 attenuates senescence-associated secretory phenotype independently of TGF-β-driven cardiac fibroblasts differentiation to myofibroblast.

Cardiac fibroblasts (CF) are key regulators of myocardial inflammation through their ability to acquire senescent phenotypes and secrete inflammatory mediators. Although transforming growth factor-β (TGF-β) signaling is a central driver of myofibroblast differentiation, its contribution to inflammation-induced senescence and the senescence-associated secretory phenotype (SASP) remains poorly understood. In this study, we examined whether inflammatory stress induces senescence in adult rat CF independently of TGF-β signaling and evaluated the ability of Resolvin D1 (RvD1) to modulate the established SASP. Adult rat CF were treated with the ALK5 inhibitor SB431542 from isolation to prevent spontaneous myofibroblast differentiation. Cells were exposed to lipopolysaccharide (LPS, 1 μg/mL) under high (10%) serum conditions for 3 or 7 days. Senescence was assessed by cellular hypertrophy and SA-β-galactosidase activity. Following LPS stimulation, culture media were replaced and CF were treated with RvD1 for 48 h. Secreted cytokines, chemokines were quantified in conditioned media. LPS induced a robust senescent phenotype in CF, characterized by increased cell size and SA-β-galactosidase activity, regardless of TGF-β pathway inhibition or serum concentration. Inhibition of TGF-β signaling prevented myofibroblast differentiation but did not attenuate senescence induction. Importantly, RvD1 treatment significantly reshaped the SASP of senescent CF, reducing pro-inflammatory mediators including IL-1β, IL-6, TNF-α, and MCP-1, while preserving anti-inflammatory cytokines. These findings identify inflammatory stress as a driver of TGF-β–independent senescence in cardiac fibroblasts and highlight RvD1 as a potent modulator of senescence-associated inflammation.