Trimethylamine N-oxide as a key microbial mediator in the progression of diabetic kidney disease

Table 1 Microbial-metabolic disturbances that promote trimethylamine N-oxide -driven pathways in diabetic kidney disease[4-8]

Pathway	Microbial derangement	Physiological consequence	Relevance to TMAO biology
Outer-membrane-vesicle-associated LPS production	Increase in gram-negative organisms	Activation of TLR4, NF-κB, and NLRP3 pathways	Enhances renal responsiveness to TGF-β-mediated fibrotic signalling
Depletion of short-chain-fatty-acid-producing taxa	Reduction in Faecalibacterium prausnitzii and Lachnospira	Loss of GPR43 and GPR109A anti-inflammatory signalling	Diminishes intrinsic anti-fibrotic buffering and lowers resistance to TMAO-driven injury
Enhanced microbial trimethylamine formation	Expansion of TMA-generating microbial communities	Increased luminal TMA availability	Greater hepatic conversion of TMA to TMAO, elevating systemic TMAO burden
Impaired intestinal barrier integrity	Reduced expression of ZO-1 and occludin	Increased translocation of microbial products into systemic circulation	Augments systemic inflammatory activation and magnifies TMAO-associated renal effects

LPS: Lipopolysaccharide; TLR4: Toll-like receptor 4; NF-κB: Nuclear factor-κB; NLRP3: NOD-like receptor family pyrin domain containing 3; TMA: Trimethylamine; TMAO: Trimethylamine-N-oxide; ZO-1: Zonula occludens-1.