Beta-hydroxy-beta-methylbutyrate (HMB) ameliorates DSS-induced colitis by inhibiting ERK/NF-κB activation in macrophages

Background: beta-Hydroxy beta-Methylbutyrate (HMB), derived from leucine, is known for its role in anti-oxidation and anti-inflammation. But, the application of HMB in IBD treatment is not fully understood, highlighting the requirement for further research. Purpose: We aimed to examine the effects of HMB treatment on DSS-induced chronic colitis in mice and explore its underlying mechanisms. Methods: To simulate colonic inflammation, a murine colitis model was generated by using DSS induction. Critical indicators such as body weight, colon length, disease activity index (DAI), and gross pathology were thoroughly monitored. Immunohistochemistry assay was conducted to assess the expression of Occludin and F4/ 80. Flow cytometry was employed to evaluate the expression levels of CD80 and CD86. qPCR was performed to measure cytokine expression (IL-6, IL-1 beta, TNF-alpha, IL-22, CXCL2, iNOS). RNA sequencing was carried out using bone-marrow derived dendritic macrophage cells (BMDMs). Results: Our study indicates that HMB treatment substantially mitigated colonic damage in murine models of DSS-induced colitis, highlighting its anti-inflammatory potential. Notably, HMB significantly enhanced the expression of Occludin in these mice. Furthermore, HMB downregulated proinflammatory markers such as IL-6, IL-1 beta, and TNF-alpha as well as CXCL2 in the colon tissue. In vitro experiments also revealed that HMB reduced production of proinflammatory cytokines induced by DSS and suppressed the expression levels of CD80 and CD86 in macrophage cells. On a mechanistic level, we demonstrated the anti-inflammatory effects of HMB by reducing the phosphorylation of p-ERK and p-p65, thereby limiting cytokine production in both in vivo and in vitro settings. Conclusion: These findings indicate that HMB possesses anti-inflammation against intestinal inflammation and may hold promise as a potential therapeutic candidate for IBD treatment. There's growing interest in combining traditional anti-inflammatory agents with supplements like HMB to improve outcomes in complex IBD cases. HMB's role in established muscle preservation and reduction of systemic inflammation as described in this study could make it a valuable adjunct in IBD therapy.