Abstract Body: Obesity is a leading cause of chronic kidney disease and promotes systemic inflammation. Our lab previously reported that a two-week time restricted feeding (TRF, feeding during the 12-hour dark phase only) intervention at the end of a 20-week diet induced obesity (DIO, 45% fat) protocol in male mice significantly reduced kidney fibrosis and infiltrating CD8⁺ T cells. Further, we found that two-weeks of anti-CD8 treatment for systemic CD8⁺ T cell depletion diminished kidney fibrosis in DIO. We hypothesized that TRF significantly reduces cytotoxic and pro-inflammatory CD8⁺ T cells in DIO. Granzyme B and perforin are two major cytotoxic and pro-fibrotic markers of CD8⁺ T cells. In the kidneys, TRF significantly reduced granzyme B⁺ and perforin⁺ CD8⁺ T cells compared to DIO (Granzyme B: one-way ANOVA: p=0.007, normal diet (ND) vs DIO: p=0.009; DIO vs TRF: p=0.034; Perforin: one-way ANOVA: p=0.009, ND vs DIO: p=0.011; DIO vs TRF: p=0.041). Given the importance of the adipose tissue in obesity, we also assessed cytotoxic CD8⁺ T cells in the perirenal adipose tissue. Granzyme B⁺, but not perforin⁺, CD8⁺ T cells are significantly reduced with TRF compared to DIO (Granzyme B: one-way ANOVA: p=0.008, ND vs DIO: 0.962, DIO vs TRF: 0.016; Perforin: one-way ANOVA: p=0.697). Previous studies from our lab also revealed that infiltrating kidney CD8⁺ T cells are derived from the small intestine and its associated tissues, Peyer’s patches and mesenteric adipose tissue. Thus, we hypothesized that TRF also reduced cytotoxic CD8⁺ T cells in the Peyer’s patches and mesenteric adipose tissue compared to DIO. In both the Peyer’s patches and mesenteric adipose tissue, granzyme B⁺ CD8⁺ T cells were significantly reduced with TRF compared to DIO with no effect on perforin⁺ CD8⁺ T cells (Peyer’s patches – granzyme B: one-way ANOVA: p=0.016, ND vs DIO: p=0.450, DIO vs TRF: p=0.012; Peyer’s patches – perforin: one-way ANOVA: p=0.418; mesenteric adipose tissue – granzyme B: one-way ANOVA: p=0.021, ND vs DIO: p=0.037, DIO vs TRF: p=0.031; mesenteric adipose tissue – perforin: one-way ANOVA: p=0.152). Future research will evaluate the sensitivity of granzyme B, but not perforin, to TRF in multiple tissues on the consequences of DIO. Our data suggests that TRF reduces kidney fibrosis through diminishing the granzyme B producing CD8⁺ T cells.