Lactobacillus johnsonii GLJ001 prevents DSS-induced colitis in mice by inhibiting M1 macrophage polarization via gut microbiota-SCFAs axis

• Lactobacillus johnsonii GLJ001 improved symptoms in colitis mice such as weight loss, colon shorting and colon tissue damage . • Lactobacillus johnsonii GLJ001 enhanced abundance of short-chain fatty acids -producing bacteria in colitis mice. • Lactobacillus johnsonii GLJ001 increased the levels of short-chain fatty acids in colitis mice. • Short-chain fatty acids inhibited M1 polarization of macrophages derived from THP-1 cells. Inflammatory Bowel Disease (IBD) is increasing worldwide and has become a global emergent disease. Probiotics have been reported to be effective in relieving colitis. Previous studies found ripened Pu-erh tea (RPT) promoted gut microbiota resilience against dextran sulfate sodium (DSS)-induced colitis in mice by increasing relative abundance of Lactobacillus . However, whether and how it alleviated DSS-induced colitis in mice need to be explored. Here, we screened a probiotic Lactobacillus johnsonii GLJ001 from feces of ripened Pu-erh tea (RPT)-administrated mice. In this study, L. johnsonii GLJ001 attenuated symptoms of DSS-induced colitis in mice, including weight loss, increased disease activity index (DAI), colon shortening and colon tissue damage, as well as high expression of inflammatory cytokines and disturbances of intestine barrier function. Furthermore, abundances of short-chain fatty acids (SCFAs)-producing bacteria (i.e. Clostridium cluster IV and XIVa, Lachnospiracea_incertae_sedis and Ruminococcus ) were enhanced in the cecum of mice treated with L. johnsonii GLJ001, accompanying by an increase of SCFAs. It was also found that SCFAs inhibited mRNA expression of M1 macrophage markers ( Inos and CD86 ), inflammatory cytokines (TNF-α and Il-1β ) and SCFAs receptors ( Gpr41 and Gpr43 ) induced by lipopolysaccharide (LPS) and interferon-γ (IFN-γ) in THP-1 cell line. Collectively, L. johnsonii GLJ001 prevented DSS-induced colitis in mice by inhibiting M1 macrophage polarization via gut microbiota-SCFAs axis, and can be administered for management of colitis.