Radix Isatidis polysaccharide-induced gut microbiota alleviates interstitial nephritis caused by infectious bronchitis virus via the gut-kidney axis.

Interstitial nephritis caused by Infectious Bronchitis Virus (IBV) is a primary cause of mortality in chickens. To investigate whether gut microbiota mediate this effect, chickens were treated with antibiotics to deplete intestinal flora, which exacerbated IBV infection and abolished RIP's protective effect. It was found that fecal microbiota transplantation (FMT) could reduce IBV copy numbers, decrease the production of metabolites, decrease the expression of NLRP3 pathway-related genes and proteins in the kidneys and intestines and increase the expression of tight intestinal junction proteins, and alleviate enteritis and interstitial nephritis. The 16S rRNA sequencing results indicated a significant increase in the abundance of harmful Escherichia_Shigella bacteria following IBV infection. However, in the RIP prevention group and FMT group, there was an increase in the abundance of probiotics such as Faecalibacterium, Lactobacillus, and Bifidobacterium. Furthermore, Lactobacillus reuteri, isolated from the feces of RIP-administered chickens and combined with sodium acetate (NaAc), alleviated interstitial nephritis and was associated with decreased expression of NLRP3 pathway-related molecules, reduced inflammatory factors, and enhanced intestinal tight junction proteins. This study not only confirms the vital role of gut microbiota in the treatment of IBV-induced nephritis but also opens avenues for the development of targeted probiotic therapies in viral infections and kidney diseases.