Differences of the gut microbiota and metabolome in patients affected by different types of nephropathies: Chronic kidney disease, diabetic kidney disease, autosomal dominant polycystic kidney disease, and immunoglobulin a nephropathy

The impaired kidney function in nephropathic patients was linked to an unbalanced microbiota asset. To better detail the reasons of this dysbiosis, we here inspected the gut microbiota and volatile metabolome in four kidney pathologies: Chronic Kidney Disease (CKD), Diabetic Kidney Disease (DKD), Autosomal Dominant Polycystic Kidney Disease (ADPKD), and Immunoglobulin A nephropathy (IgAn). This observational study led to determining differences between the four groups, compared to a healthy control group (HC). Biochemical parameters and faecal samples were used to investigate the gut microbial population through an approach based on quantitative PCR and gas chromatography coupled with mass spectrometry. Blood biochemical variables highlighted four distinct profiles relative to the four groups of nephropathic patients. Looking at qPCR results, a discriminant analysis of principal components led to the separation of the above mentioned microbial profiles from HC and ADPKD with respect to CKD, DKD, and IgAn groups, that appeared to cluster together. Most impacting loading factors included Bifidobacterium, Lactobacillus, Bacteroides, and Clostridium species and Bifidobacterium, Prevotella, Desulfovibrio and Atopobium at the genus level. On the other hand, based on the volatile metabolic analysis, the investigated groups were plotted in three clusters. IgAn was characterized by greater amounts of esters and ketones, ADPK and CKD by aldehydes, terpenes, sulfuric compounds, and fatty acids, while DKD and HC by greater concentration of indoles, hydrocarbons, alcohols, phenols, and carboxylic acids. All the investigated nephropathy led to an altered homeostasis. By comparing the different kidney related pathologies, we detected some volatile organic metabolites and biochemical parameters that resemble differentiated host symptomatic conditions. In the presence of an impaired kidney function, these results shed light on the way the gut microbiota is shaped by different clinical pictures and on how some metabolites and taxa can be used as markers useful to predict and stratify patient groups.