Abstract Body: Obesity is a leading cause of chronic kidney disease (CKD). Our lab previously showed that a 20 week diet-induced obesity (DIO) protocol (45% high fat) significantly increased kidney medullary fibrosis in male mice. Further, we found that time restricted feeding (TRF, feeding during 12-hr dark phase only) during the final 2 weeks of the 20-week DIO protocol significantly reduced kidney fibrosis. DIO mice showed significantly greater CD8+ T cells, compared to mice on a normal diet (ND) only during the dark phase. TRF in the DIO mice normalized the CD8+ T cell to that similar to ND mice. We hypothesized that pro-fibrotic CD8+ T cells infiltrate the kidney and mediate damage in the DIO mice. We used anti (a)-CD8 treatment during the final 2 weeks of DIO to deplete all CD8+ T cells. Separate cohorts of ND and DIO mice received control a-IgG treatment during the final 2 weeks of the protocol. DIO mice treated with a-CD8 showed significantly reduced kidney fibrosis compared to DIO mice treated with a-IgG and similar to ND mice treated with a-IgG (assessed by blue trichrome and picrosirius red staining; one-way ANOVA, p=0.018; NDa-IgG vs DIOa-IgG: p=0.033; DIOa-IgG vs DIOa-CD8: p=0.032). We next investigated the intestinal mucosa (IM) as a source of the kidney-infiltrating CD8+ T cells in DIO mice since the IM is one of the primary non-lymphoid sites of T cells in the body. Previous studies have shown that migration of T cells from the IM to the kidney can drive acute kidney injury, but it is unclear if this occurs with chronic models such as DIO. We used the KikumeGreen (KikGr) mouse model to identify migrating cells into the kidney. When KikGR protein is exposed to 408 nm blue light it is photoconverted to a KikRed. We photoconverted the IM at the end of the ND, DIO, and DIO+TRF protocols. Kidneys were analyzed by flow cytometry at 2.5 days post-photoconversion. We detected significantly higher KikRed+ CD8+ T cells in the kidneys of DIO mice compared to ND mice indicating that CD8+ T cells migrate to the kidney from the IM. DIO+TRF mice showed reduced KikRed+ CD8+ T cells in the kidney compared to DIO mice (one-way ANOVA: p=0.006, ND vs DIO: p=0.008; DIO vs TRF: p=0.047). DIO did not have any significant effect on CD4+ T cell migration (one-way ANOVA: p=0.997). This study indicates that DIO induces migration and infiltration of pro-fibrotic CD8+ T cells from the IM to the kidney, while TRF specifically limits migration and infiltration of CD8+ T cells.