Predominant Bacterial Diversity in Rheumatoid Arthritis Rat After Treated with Caprine CSN1S2 Protein

Rheumatoid arthritis (RA) is an autoimmune and systemic inflammatory disease that is affected to microbial abnormalities in the gut and altered the metabolism and immune system. Bioactive peptides have many functions in the body that related to health. This study aimed to investigate the effect of caprine CSN1S2 protein and to identify the predominant bacterial diversity in rheumatoid arthritis rats through fecal analysis based on PCR-DGGE and phylogenetic analysis. The animals were divided into 6 groups with 2 types of the rat model, namely control rats (untreated (C), treated with caprine CSN1S2 protein from milk (CM), and treated with caprine CSN1S2 protein from yogurt (CY)) and rheumatoid arthritis rats (rheumatoid arthritis (RA), treated with caprine CSN1S2 protein from milk (RAM), and treated with caprine CSN1S2 protein from yogurt (RAY). Predominant cultivable bacteria were obtained by direct culture and analyzed using PCR-DGGE with several specific primers. The DNA sequences were analyzed and aligned using bioinformatics software to construct the phylogenetic tree. The results showed that bacterial composition in all control groups was dominated by Lactobacillus group but in the rheumatoid arthritis rat (RA) group was dominated by Enterococcus group, particularly Enterococcus faecium and Enterococcus faecalis. Meanwhile, Bacillus coagulans dominated in rheumatoid arthritis rats after treated with caprine CSN1S2 protein. The caprine CSN1S2 protein has effects in rheumatoid arthritis rats with the emergence of predominant bacteria that can promote the growth of B. coagulans and it might be suppressed pathogenic bacteria in the development of rheumatoid arthritis disease.