Dietary fiber regulates intestinal flora and suppresses liver and systemic inflammation to alleviate liver fibrosis in mice

Liver fibrosis is a common pathologic process related to chronic liver disease. However, there are currently no effective methods to reverse liver fibrosis. Chronic liver disease is typically associated with a major imbalance in the intestinal flora, and targeting the regulation of the intestinal flora structure may facilitate the prevention and treatment of chronic liver disease. Therefore, in this study, we explored the effects of dietary fiber on the prevention of liver fibrosis in mice. C57BL/6J mice were randomly divided into 4 groups: olive oil group (control), fibrosis (CCl4) group, resistant maltodextrin (RM) + CCl4 group, and wheat fiber (WF) + CCl4 group. In the latter 3 groups, liver fibrosis was established by treatment with CCl4. In the RM + CCl4 and WF + CCl4 groups, the mice were treated with soluble dietary fiber (RM) or insoluble dietary fiber (WF) for 3 wk before receiving CCl4. The effects of dietary fiber on various indexes of liver fibrosis in mice induced by CCl4 were observed. The results showed that increasing dietary fiber intake prevented liver fibrosis in mice, reduced serum levels of proinflammatory factors (e.g., tumor necrosis factor-alpha, interleukin [IL] 1-beta and IL-6) and increased IL-10 and interferon-gamma levels. Moreover, increased dietary fiber intake also reduced the infiltration of cluster of differentiation (CD) 3+, 4+, and 8+ T lymphocytes in the liver, regulated the structure of the intestinal flora, and increased the Bacteroidetes/Firmicutes ratio. Our findings revealed the complex relationships between dietary fiber, intestinal flora, and immunity, and suggested that dietary therapy could alleviate liver fibrosis.