Anti-fibrogenic Potential of Mesenchymal Stromal Cells in Treating Fibrosis in Crohn's Disease.

BACKGROUND: Intestinal fibrosis is a major complication of CD and may result in stricture formation leading to intestinal obstruction. MSCs play multiple roles in active CD and fibrosis-associated diseases.

AIMS: This study was designed to investigate the role of MSCs in CD-associated intestinal fibrosis.

METHODS: Intestinal fibrosis was induced over 7 weeks of enema with increasing doses of TNBS and assessed by Masson's trichrome staining. Transcriptome sequencing and gene set enrichment analysis were conducted to reveal the transcriptome changes among groups at the mRNA level. Immunofluorescence assays were used to validate the role of EMT in intestinal fibrosis. Quantitative real-time PCR and immunohistochemistry analyses were performed to clarify the association between the anti-fibrogenic properties of MSCs and the immune microenvironment. Western blotting was used to verify the potential signaling pathways.

RESULTS: Fibrotic tissue accumulation and inflammatory cell infiltration were detected in the colon tissue after TNBS induction treatment. Prophylactic MSCs treatment inhibited colon shortening, while therapeutic treatment decreased colon weight. Prophylactic treatment with MSCs inhibited the accumulation of fibrotic tissue, the expression of fibrotic proteins and EMT. Therapeutic MSCs treatment reversed the established intestinal fibrosis and reduced EMT. The secretion of the fibrogenic factors IL-1beta, IL-6 and IL-13 was down-regulated after both MSCs treatment approaches, while IL-10, an anti-fibrogenic factor, was up-regulated. Both MSCs therapies inhibited the expression of TGF-beta and the phosphorylation of Smad2 and Smad3 after TNBS induction.

CONCLUSION: MSCs exert anti-fibrogenic activity against CD-associated fibrosis by regulating the inflammatory environment, inhibiting the TGF-beta/Smad signaling pathway and ameliorating EMT.