Butyrate‐producing gut bacteria and luminal butyrate levels are reduced in Inflammatory Bowel Diseases (IBDs). Butyrate has anti‐inflammatory properties through mechanisms not well‐characterized in IBDs. Here, we determined the butyrate anti‐inflammatory effect on primary IBD tissues and intestinal cell models to identify key target cells and pathway(s) involved. Cytokines, monocarboxylate transporter‐1 (MCT1), G‐protein‐coupled receptor‐109A (GPR109A), and histone deacetylase‐3 (HDAC3) levels were analyzed in IBD and healthy tissues using cytometric bead arrays, RNA‐seq analysis and immunofluorescence. Inflammatory markers and phagocytosis in butyrate‐treated colonic organoids, primary monocytes or THP‐1 macrophages, were assessed by qPCR, flow cytometry and amikacin protection assays, when relevant combined with GPR109A or HDAC3 antagonists. Butyrate suppressed TNF and IL‐6 secretion by > 50% in ex vivo ‐cultured inflamed IBD biopsies. MCT1 expression was reduced in inflamed epithelium and cytokine‐exposed organoids, while IL‐18 was reduced 0.5‐fold in organoids, and both were restored by butyrate, without suppressing pro‐inflammatory gene expression. GPR109A and HDAC3 were elevated in IBD tissues and upregulated by butyrate in cultured mucosa. Butyrate also suppressed IL‐6, TNF‐α, CD40, and CD80 by > 50% and enhanced adherent‐invasive Escherichia coli (AIEC) phagocytosis by 62% in monocytes/macrophages. Histone acetylation (H3K9ac) increased > 5‐fold, mimicking the HDAC inhibitor SAHA. Contrary, specific GPR109A inhibition and gene G‐protein‐coupled receptor inhibition did not alter butyrate's effects. Butyrate restores MCT1 and IL‐18 gene expression in inflamed epithelial cells, showing limited anti‐inflammatory effects. Instead, butyrate targets HDAC3 in mononuclear cells, suppressing inflammation in IBD gut mucosa. The cell‐type‐specific effects of butyrate offer mechanistic insights that support its therapeutic relevance in IBDs.
Parada-Venegas et al. (2025) studied this question.