Gut-kidney axis: Dysbiosis and renal disease

Table 1 Main uremic toxins and their effect on the kidney

Compound	Total plasma concentration in CKD	Lowest concentration active on cultured renal cells (μM)	Effects on cultured renal cells	Effects on kidneys in vivo
pCS	Median 50; maximum 500	100	Decreased viability, increased oxidative stress, increased inflammatory and profibrotic responses, decreased expression of nephroprotective factors	Progression of CKD, kidney fibrosis, promote epithelial-to-mesenchymal transition. Activate the renal-angiotensin system
pCG	Median 0.22; maximum 8	25	Decreased the function of proximal cell membrane transporters (MRP4)	Kidney fibrosis. Promotes epithelial-to-mesenchymal transition
IS	Median 221; maximum 1100	1000	Decreased viability, increased oxidative stress, increased inflammatory and profibrotic responses, decreased expression of nephroprotective factors	Accelerated fibrosis and CKD progression. Podocyte injury
IAA	Median 5; maximum 50	250	Reduced viability through induction of apoptosis in tubular cells	Accelerated CKD progression
TMAO	Median 25; upper quartile > 38	ND	No data	Kidney tubulointerstitial fibrosis

CKD: Chronic kidney disease; IAA: Indole-3 acetic acid; IS: Indoxyl sulfate; pCS: Para cresyl sulfate; pCG: P-cresyl-glucuronide; TMAO: Trimethylamine N-oxide.