Changes in intestinal florae and serum inflammation in rheumatoid arthritis rats and the effects of probiotics

OBJECTIVE The aim of this study was to explore the changes in intestinal florae and serum inflammation in rats with rheumatoid arthritis (RA), and to investigate the effects of probiotics. MATERIALS AND METHODS A total of 30 Sprague Dawley (SD) rats were randomly divided into three groups, namely, control group, model group, and probiotic group. The rats in the model group were prepared into models of collagen II-induced arthritis. Meanwhile, the rats in probiotic group were treated with probiotics for 6 weeks via intragastric administration in addition to the treatment in the model group. Next, the feces of rats in the control group, model group, and probiotic group were sampled to detect the composition of intestinal florae. In addition, peripheral blood was collected from rats to determine the changes in the content of inflammatory factors, including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and IL-1β through enzyme-linked immunosorbent assay (ELISA). RESULTS Compared with the control group, the levels of serum inflammatory factors TNF-α, IL-6 and IL-1β were significantly upregulated in the model group (p<0.05). This suggested successful modeling. However, they decreased notably in probiotic group when compared with the model group (p<0.05), indicating that probiotics could inhibit inflammatory response in rats. The levels of microbes Bacteroidetes, Streptococcus and Clostridiales were significantly higher in the control group (p<0.05). The levels of Ruminococcaceae, Asoccbarobacler, Coriobacteriaceae, and fecal anaerobic coryneform bacteria were remarkably higher in the model group (p<0.05). Meanwhile, the levels of Porphyromonadaceae, Barnsiella, Actinobacteria, Alloscardovia, Bifidobacteria and Parabacteroides were remarkably higher in probiotic group (p<0.05). The intestinal level of Bacteroides was the highest in rats of control group, which decreased significantly in the model group (p=0.000). However, the intestinal level of Bacteroides in probiotic group was overtly higher than that in the model group (p=0.000), whereas was lower than the control group. The intestinal level of Bifidobacteria in the model group was significantly lower than that in the control group (p=0.024). However, it was evidently higher in the probiotic group than that in both model group and control group (p=0.000). The intestinal level of Asoccbarobacler was remarkably higher in the model group than that in control group (p=0.005). However, it was lower in probiotic group than that in model group (p=0.003), showing the highest in model group. There was an evidently negative correlation between Firmicuteria and Clostridium (r=-0.82, p=0.000), and a positive association between Firmicuteria and Bacteroides (r=0.77, p=0.000). Bacteroides was negatively correlated with Clostridium (r=-0.89, p=0.002) and Enterococcus (r=-0.63, p=0.021). In addition, Enterococcus had a highly positive correlation with Clostridium (r=0.6, p=0.001). CONCLUSIONS Evident changes in intestinal florae and serum inflammation are detected in rats with RA, and such changes can be partially reversed by probiotics.