Intestinal microbiome and fitness in kidney disease.

Environmental changes can induce diversity shifts within ecosystems that affect interactions between species. Similarly, the development of kidney disease induces shifts within the ecosystem of the intestinal microbiome, affecting host physiology and fitness. Renal failure itself, together with related changes in diet and medication, alters the microbiota and its secretome of micronutrients, nutrients and regulatory metabolites towards a phenotype characterized by the production of uraemic toxins, hence contributing to the clinical syndrome of uraemia and its complications. These alterations are associated with structural changes in the intestinal wall that impair barrier function and cause leakage of bacterial metabolites, bacterial wall products and live bacteria into the circulation. Thus, the intestinal microbiota represents a new therapeutic target to improve outcomes of chronic kidney disease (CKD), including symptoms of uraemia, metabolic changes, cardiovascular complications, aberrant immunity and disease progression. Initial interventional studies have shown promising effects of unselective probiotic preparations on kidney inflammation and uraemia in patients with CKD but longer-term studies are needed. Here, we take an ecological approach to understand the role of the intestinal microbiota in determining survival fitness in kidney disease.