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DOP68 Thiomyristoyl ameliorates colitis by blocking the differentiation of Th17 cells via STAT3/IL-6 signal pathway

Y. XU1, M. zhang2, G. Xu2, X. Zou2

1Department of Gastroenterology, Nanjing Medical University Affiliated Drum Tower Clinical Medical College, Nanjing, China, 2Department of Gastroenterology, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, China

Background

The pathogenesis of inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), has not been fully elucidated, but a strong correlation between IBD and the immune dysregulation of the host has been persistently detected. Sirtuin 2 (SIRT2), a histone deacetylase, has recently been found to play an important role in inflammation, infection and immunomodulatory. As a potent SIRT2-specific inhibitor, thiomyristoyl (TM) has an extensive anticancer activity, but its anti-inflammatory property remains unclear.

Methods

Human peripheral blood mononuclear cells (PBMC) were differentiated into T helper 17 (Th17) cells in vitro and were treated with TM simultaneously. Interleukin (IL)-17A in the culture supernatant, the ratio of T cells, the levels of phosphorylated-signal transducer and activator of transcription (p-stat3) and phosphorylated-nuclear factor kappa-B (p-NF κB) were determined by enzyme-linked immunosorbent assay (ELISA), flow cytometry or western blotting, respectively. Then, colitis C57BL/6J mice induced by 2.5% dextran sulphate sodium salt (DSS) were treated with TM, and were evaluated by disease activity index (DAI) and haematoxylin-eosin (HE) staining. T-cell subsets in the mice spleen, IL-6, IL-10 and IL-17A in serum, related factors retinoic acid receptor-related orphan receptor-γ t (ROR-γt), forkhead box protein P3 (FOXP3), IL-17A, interferon γ γ (IFN-γ), IL-23, IL-10 and hypoxia-inducible factor (HIF)-1α in mice colon were measured by flow cytometry, ELISA, quantitative real-time polymerase chain reaction (Q-PCR) and western blotting, respectively.

Results

Compared with the positive control group, the levels of IL-17A in culture supernatant, the percentage of Th17, the levels of p-stat3 and p-NF kappa B in cell lysate were lower in the TM group. Compared with PBS-treated colitis mice, TM-treated colitis mice had longer colons, fewer weight-losses, lower DAI and histopathologic scores. Interestingly, although the expression of IFN-γ, IL-17A, and ROR-γt was inhibited in the colons of TM-treated mice, the level of FOXP3 did not change. Consistently, the percentage of spleen Th17 cells was decreased in the TM group while the percentage of Treg cells was not affected. In addition, the TM group had reduced levels of IL-23 and HIF-1α, and an increased level of IL-10 in the colon, compared with colitis group.

Conclusion

TM ameliorates DSS-induced experimental colitis by blocking the differentiation of Th17 cells, which may be associated with the STAT3/IL-6 signal pathway. SIRT2 may represent a potential target for the treatment of IBD.

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