Immunomodulatory effects of the Bifidobacterium longum BL-10 on lipopolysaccharide-induced intestinal mucosal immune injury

Abstract

The intestine is the largest digestive and immune organ in the human body, with an intact intestinal mucosal barrier. <i>Bifidobacterium longum</i> is the specific gut commensals colonized in the human gut for boosting intestinal immunity to defend against intestinal mucosal immune injury. In the LPS-induced intestinal injury model, the <i>Bifidobacterium longum</i> BL-10 was suggested to boost the intestinal immune. Detailly, compared with the LPS-induced mice, the BL10 group significantly reduced intestine (jejunum, ileum, and colon) tissue injury, pro-inflammatory cytokines (TNF-α, IFN-γ, IL-2, IL-6, IL-17, IL-22, and IL-12) levels and myeloperoxidase activities. Moreover, the <i>B. longum</i> BL-10 significantly increased the number of immunocytes (CD4+ T cells, IgA plasma cells) and the expression of tight junction protein (Claudin1 and Occludin). <i>B. longum</i> BL-10 regulated the body's immune function by regulating the Th1/Th2 and Th17/Treg balance, which showed a greater impact on the Th1/Th2 balance. Moreover, the results also showed that <i>B. longum</i> BL-10 significantly down-regulated the intestinal protein expression of TLR4, <i>p</i>-IκB, and NF-κB p65. The <i>B. longum</i> BL-10 increased the relative abundance of the genera, including <i>Lachnospiraceae_</i>NK4A136_group and <i>Clostridia_</i>UCG-014, which were related to declining the levels of intestinal injury. Overall, these results indicated that the <i>B. longum</i> BL-10 had great functionality in reducing LPS-induced intestinal mucosal immune injury.