Modifications of abundances of some bacteria are associated with the severity of IgA nephropathy in Chinese population

Abstract

<jats:title>Abstract</jats:title> <jats:p>Background Immunoglobulin A nephropathy (IgAN) is a common autoimmune glomerular disease, the classic manifestations of which are hematuria and proteinuria. The pathogenesis of IgAN has been associated with dysregulated intestinal mucosal immunity. However, whether gut microbial modifications play a part in IgAN remains unclear. Methods Blood and fecal samples were collected from 52 IgAN patients and 25 healthy controls (HCs). The gut microbiome was analyzed by 16S ribosomal RNA (rRNA) gene sequencing, followed by analyses of gut microbiota composition. Furthermore, the levels of galactose-deficient IgA1 (Gd-IgA1), soluble cluster of differentiation 14 (sCD14), lipopolysaccharide binding protein (LBP), intercellular adhesion molecule-1 (ICAM-1), and C-reactive protein (CRP) was quantified by enzyme-linked immunosorbent assay (ELISA). Results Substantial differences in gut microbiota were found between IgAN patients and HCs (P &lt; 0.05). The abundance of pathogenic bacteria (<jats:italic>Bacteroides</jats:italic> and <jats:italic>Escherichia-Shigella</jats:italic>) was significantly higher in IgAN patients than in HCs, while that of beneficial strains (<jats:italic>Bifidobacterium</jats:italic> and <jats:italic>Blautia</jats:italic> spp.) was lower. Higher proportions of <jats:italic>Escherichia-Shigella</jats:italic> and lower proportions of <jats:italic>Bifidobacterium</jats:italic> spp. were observed in IgAN patients with a high urine RBC count (≥ 10/HP) and proteinuria (≥ 1 g/24 h) levers. Spearman’s correlation analysis was used to assess the association between gut microbiota and biomarkers in IgAN patients. The results showed that the genus <jats:italic>Prevotella 7</jats:italic> was negatively correlated with Gd-IgA1, LBP, sCD14, and ICAM-1, while <jats:italic>Bifidobacterium</jats:italic> spp. presented a significant inverse relationship with LBP and Gd-IgA1. Additionally, <jats:italic>Escherichia-Shigella</jats:italic> was negatively correlated with <jats:italic>Prevotella 7</jats:italic>. Conclusions In IgAN patients, gut modifications were characterized by an increase in the numbers of pathogenic bacteria and a reduction in the levers of beneficial bacteria. Our results suggest that disturbance of the intestinal microflora might play a critical part in the severity of IgAN, and may be a potential therapeutic target.</jats:p>