Plasma TMAO (A) levels are increased after 6 week feeding TMAO (0.12%), or Choline (1.0%) diets vs chow (0.08% choline) fed mice. Representative Mason trichrome histology (B) quantitative morphometry (C) and its relationship with TMAO levels (D), SMAD3 activation by phosphorylation at serine 423/425 (E) and its relationship with TMAO levels (F) in mouse kidneys after 6 week feeding of chow (0.08% choline), TMAO (0.12%), and Choline (1.0%) diets. Scale bar represents 100 um. **P<0.01 vs. chow fed, n≥5 mice per group.