Trafficking of Intestinal Peyer Patches Immune Cells to Kidneys: Novel Mechanism by Which Gut Microbiome Modulates AKI

Background: The gut microbiome has been shown to modify outcomes from experimental AKI. However, the precise mechanisms are not known. One possible mechanism is by modulating immune cell trafficking and function into AKI kidney. We hypothesized that the intestinal Peyer’s patches were a potential source of kidney immune cells infiltration during AKI. Methods: Male B6 mice treated with AMX or vehicle for 15 days, and germ-free (GF) mice, underwent 50-minute unilateral ischemia-reperfusion injury (UIR). Peyer’s patches (PP) were labeled with CellTrace Far Red or CFSE dye, immediately or 48h post-surgery, followed by in vivo imaging. Kidney and small intestine were harvested at 72h or 7 days post-UIR for immunophenotyping. scRNAseq analysis on CD3+ sorted cells from gut and kidney were performed to identify potential chemokines involved in immune cell trafficking. After identification of chemokine CXCR6, mice received 100 µg anti-CXCR6 antibody or isotype every other day post-UIR, till day 7 followed by evaluation of kidney tissue and GFR measurements. Results: In vivo whole mouse imaging demonstrated that PP labeled cells migrated to the injured kidney. Flow data showed also migration of immune cells from PP to the kidney following AKI. At three days post-UIR, the percentage of CD3+ CFSE+ cells significantly increased in the kidneys of normal mice (Control: 37.4 ± 5.2, UIR: 76.8 ± 3.6, p<0.0001); however, it decreased in germ-free mice UIR compared to UIR in standard conditions (Control: 21.35±0.9, GF-control: 28.07 ± 1.8, UIR: 69.18 ± 10.31, GF-UIR: 40.5 ± 8.2, p < 0.0001). Similar observations were made in the 7-day groups. Blocking CXCR6 reduced CD3 cell migration (IgG:26.70±3.1, CXCR6:19.30±1.0, <0.0001) and renal fibrosis (IgG:21.20±3.8, CXCR6:16.60±3.7), but did not change GFR. scRNAseq data revealed CXCR6 and pdcd1 co-expression on effector memory cells and in the kidneys. Conclusion: Immune cells migrate from intestinal Peyer’s patches to the injured kidney after severe UIR, and the absence of gut microbiota reduced this migration. Blocking CXCR6 decreased PP migration of cells to kidney and reduced kidney fibrosis. This data identifies novel mechanisms by which the gut microbiome modulates outcomes from AKI. Funding: NIDDK Support