Time restricted feeding in diet induced obesity reverses diurnal T cell rhythms in the kidney
Authors: Edell Claudia , Colson Jackson , Luong Tha , Pati Paramita , De Miguel Carmen , Pollock David , Pollock Jennifer 
Published: May 2023

Diet induced obesity (DIO) is one of the leading risk factors for chronic kidney disease (CKD). Many studies have shown a role for pro-inflammatory T cells in mediating kidney damage in DIO. We previously found a 20-week model of DIO with time restricted feeding (TRF) to the 12-hour active phase during weeks 18-20 of diet significantly reduces kidney fibrosis and urinary NGAL excretion. We also found that TRF decreases total T cells (CD3+) in the vasa recta of the kidney medulla in DIO compared to ad libitum DIO. Immune cells, including T cells, have rhythms of migration through tissues. We hypothesized that DIO drives increased T cells in the kidney and that TRF in DIO mice reduces T cell infiltration and kidney damage. Utilizing our 20-week DIO protocol (45% high fat diet) and DIO with TRF intervention (DIO+TRF), we collected kidneys at 6 timepoints and assessed changes in Cd3, a T cell marker, in the outer medulla over a 24-hour period via qPCR. DIO increased Cd3 expression at Zeitgeber time (ZT) 9 (inactive period) and ZT13 (active period) compared to DIO+TRF, with an overall effect of diet and time of day (2-way ANOVA, time of day: p=0.051, diet: p=0.050). To assess diurnal changes in T cells by flow cytometry, we collected kidneys from the normal diet (ND), DIO, and DIO+TRF groups at ZT3 (inactive period) and ZT13 (active period). We found a significant diurnal rhythm for total immune cells (CD45+) in the DIO group with increased immune cells at ZT13 that is not seen in the ND or DIO+TRF groups (2-way ANOVA, interaction: p=0.027, time of day: p=0.0003, Tukey’s post hoc: DIO ZT3 vs DIO ZT13: p=0.005). Similarly, we found increased T cells at ZT13 compared to ZT3 in DIO mice. Interestingly, at ZT13 but not ZT3, DIO has significantly more T cells than both the ND and DIO+TRF group (2-way ANOVA, Interaction: p=0.01, time of day: p=<0.0001, diet: p=0.009; Tukey’s post hoc: DIO ZT3 vs DIO ZT13: p=<0.0001, ND ZT13 vs DIO ZT13: p=0.049, DIO ZT3 vs DIO+TRF ZT13: p=0.005). We investigated the T cell subtypes and found that DIO led to a diurnal rhythm of CD4+ T cells, with an increase at ZT13 compared to ZT3 (2-way ANOVA, Interaction: p=0.02, time of day: p=0.01, Tukey’s Post Hoc: DIO ZT3 vs DIO ZT13: p=0.008). CCR6 and CXCR3 are trafficking markers of T cells. We found a significant diurnal effect in kidneys of DIO mice with greater frequency of CCR6+ and CXCR3+ CD4+ T cells at ZT13 compared to ZT3 (2-way ANOVA, time of day: CCR6+: p=0.004; CXCR3+: p=0.03). Interestingly, we found no diurnal changes in the proliferation marker Ki-67 of CD4+ T cells. Taken together, these data suggest that the diurnal variation of kidney CD4+T cells during DIO is driven through T cell trafficking. Also, TRF intervention in DIO mice reverses the diurnal effect in CD4+ T cell trafficking to the kidney and may drive the reduced kidney damage. In conclusion, these findings suggest that DIO driven kidney damage is mediated through infiltrating pro-inflammatory T cells. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.