Targeted Inhibition of Gut-Microbial Trimethylamine N-Oxide Production Fosters Regression of CKD Phenotypes

BACKGROUND: Recent studies demonstrate gut-microbial trimethylamine N -oxide (TMAO) is clinically and mechanistically linked to chronic kidney disease (CKD) development. Prior studies showed selective targeting of gut-microbial TMAO production can prevent CKD initiation. A highly relevant clinical question is whether inhibiting TMAO generation can reverse established kidney dysfunction and fibrosis. METHODS: CD1 mice were first randomized (Phase 1) to unilateral nephrectomy or sham surgery and fed a high-fat diet ± 1% choline supplementation to document CKD through measures of multiple indices of kidney function, tissue remodeling/fibrosis, and uremic toxins. Mice were then randomized (Phase 2) to continue the same diet ± fluoromethylcholine (FMC), a mechanism-based gut-microbial TMAO inhibitor, for 8 additional weeks, and the impact on CKD related phenotypes assessed. RESULTS: After 12-weeks, choline-supplemented unilateral nephrectomized mice exhibited 15-fold higher circulating TMAO levels. In parallel, multiple kidney dysfunction indices progressed, including 48% reduction in measured glomerular filtration rate (mGFR), elevated Cystatin C and creatinine, 3.5-fold greater tubulointerstitial fibrosis, and upregulated profibrotic gene expression. Following Phase 2 (8 weeks ± FMC), choline-supplemented (high-TMAO) unilateral nephrectomized mice without FMC showed further elevation of circulating TMAO and multiple indices of progressive kidney function decline and fibrosis. Conversely, FMC-treated animals showed virtual elimination in circulating TMAO and significant improvements in all monitored CKD phenotypes including >50% higher mGFR, and improved (decreased) creatinine, Cystatin C, pseudouridine, urinary albumin/creatinine ratio, kidney fibrosis measures, and many uremic toxin levels (e.g. indoxyl sulfate and phenylacetylglycine). Beyond halting progression of kidney functional decline and fibrosis, there was frank regression in tubulointerstitial fibrosis (41% reduction) and significant improvement in mGFR (39% increase). CONCLUSIONS: Pharmacological targeting of gut-microbial TMAO production after CKD establishment halted disease progression and promoted regression of key CKD pathophysiological features.