The active ingredient β-sitosterol in the anti-inflammatory agents alleviates perianal inflammation in rats by inhibiting the expression of Srebf2, activating the PPAR signaling pathway, and altering the composition of gut microbiota

Background: Anti-inflammatory herbal formulations are common in traditional Chinese medicine for clearing heat and detoxifying; however, the specific active components and their mechanisms remain unclear.

Objective: This study investigates the role of Sitosterol in alleviating perianal inflammation and its underlying mechanisms.

Methods: Sitosterol was identified as a key active ingredient through the TCMSP database. Its structure was analyzed using PubChem, target genes were explored with STITCH, and KEGG pathways related to Srebf2 were revealed by STRING. An animal model of perianal inflammation was induced with 75 % acetic acid and treated with Sitosterol, water, normal saline, or Antibiotics. The effects on gut microbiota were assessed using 16S rRNA Sequencing, and inflammation was evaluated through HE stains, IHC, and TUNEL assays. In vitro, LPS-treated Caco-2 cells were used to measure proliferation, Apoptosis, and cytokine levels, with PPAR pathway involvement examined using GW6471.

Results: Sitosterol emerged as the primary active ingredient targeting Srebf2, with KEGG analysis highlighting the PPAR signaling pathway. In rats, Sitosterol reduced weight loss, inflammatory cell infiltration, edema, and vasodilation in perianal tissue. Additionally, it decreased PCNA levels, increased Apoptosis, and elevated serum levels of IL-1β, IL-6, and TNF-α, particularly at high doses compared to Antibiotics. Sitosterol also restored gut microbiota. Srebf2 knockdown improved tissue conditions and modulated cytokine levels, effects that were countered by GW6471. In LPS-treated Caco-2 cells, Sitosterol reversed reductions in cell viability and proliferation and modulated the expression of proteins and cytokines.

Conclusion: Sitosterol restores gut microbiota composition and further alleviates perianal inflammation in rats by inhibiting Srebf2 expression and activating the PPAR signaling pathway.

Gut microbiota; PPAR signaling pathway; Perianal inflammation; Sitosterol; Srebf2.