Slc26a6 overexpression in intestinal epithelium worsens, rather than prevents, oxalate diet–driven nephrolithiasis

Background: Intestinal SLC26A6 (PAT1) is known to eliminate oxalate via its secretion into the lumen. PAT-1 deficiency is associated with an increased risk of nephrolithiasis as PAT1-KO (global) mice exhibit hyperoxalemia, hyperoxaluria and kidney stone disease (KSD). Therefore, we hypothesized that the intestinal epithelial cell (IEC) specific PAT1-overexpression (OE) may protect against the oxalate diet induced nephrolithiasis by increased intestinal secretion of oxalate. Methods: We generated an inducible floxed PAT-1-V5 tagged mouse model and crossed with villin-CreERT2 to create a tamoxifen inducible IEC specific PAT-1-OE mouse model. Age-matched wild-type (WT) and PAT1-OE (POE) C57BL/6 mice were fed two different diets and sacrificed on day 8th: a) high oxalate (50 µmol/g, calcium-free), b) calcium carbonate (150 µmol/g) with oxalate (50 µmol/g) as a control diet (as calcium chelates oxalate to block its absorption). At the end of study, kidneys and intestines were harvested along with urine and blood samples. Kidney histology using H&E staining was done to measure KSD-related changes and slides were semi-quantitatively scored (blinded) by an expert renal pathologist. Serum oxalate and creatinine levels were quantified using kit-based assays and kidney RNA was extracted for RT-PCR to assess mRNA expression for KSD-associated genes. Results: Western blot analysis of PAT1-V5 (by V5 antibody) showed that tamoxifen treatment resulted in a significant induction of PAT1 in the intestine in PAT1-OE mice but not in controls. The kidneys from these mice did not show any PAT1-V5 expression, confirming the IEC specific overexpression. The detailed histological analysis of kidneys revealed significantly increased inflammation score (2.5 fold) and acute tubular injury score (2.2 fold) in POE + oxalate diet mice compared to WT + oxalate diet group. The oxalate stone abundance was 1.7 fold higher in POE + oxalate diet compared to the WT + oxalate diet group, and phosphate stones were only seen in POE + oxalate diet group. Increases in IL-1β and NLRP3 expression in kidneys were markedly higher in POE + oxalate diet group compared to WT + oxalate diet group. Serum oxalate levels were significantly higher (~60 %) in POE + oxalate diet compared to the control diet, whereas WT + oxalate diet mice did not show any significant change in serum oxalate. Urine oxalate levels remained unchanged in all the groups. Urine citrate levels were ~3 fold decreased in both the oxalate fed groups, while serum creatinine was only significantly increased in POE + oxalate diet compared to POE + control diet and WT + oxalate diet groups. Conclusion: This study has established an IEC specific PAT1-OE mouse model and showed that PAT1-OE does not protect against the oxalate induced-KSD, rather it further worsens the impact of the oxalate rich diet. These data warrant extensive studies into the role of PAT1 utilizing intestine and kidney specific knock-down and overexpression of PAT1 to further establish its precise role in oxalate homeostasis and KSD. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.