RESUMEN
BACKGROUND & AIMS: No effective therapeutic intervention exists for intestinal fibrosis in Crohn's disease [CD]. We characterised fibroblast subtypes, epigenetic and metabolic changes, and signalling pathways in CD fibrosis to inform future therapeutic strategies. METHODS: We undertook immunohistochemistry, metabolic, signalling pathway and Epigenetic [Transposase-Accessible Chromatin using sequencing] analyses associated with collagen production in CCD-18Co intestinal fibroblasts and primary fibroblasts isolated from stricturing [SCD] and non-stricturing [NSCD] CD small intestine. SCD/ NSCD fibroblasts were cultured with TGFß and valproic acid [VPA]. RESULTS: Stricturing CD was characterised by distinct histone deacetylase [HDAC] expression profiles, particularly HDAC1, HDAC2, and HDAC7. As a proxy for HDAC activity, reduced numbers of H3K27ac+ cells were found in SCD compared to NSCD sections. Primary fibroblasts had increased extracellular lactate [increased glycolytic activity] and intracellular hydroxyproline [increased collagen production] in SCD compared to NSCD cultures. The metabolic effect of TGFß-stimulation was reversed by the HDAC inhibitor VPA. SCD fibroblasts appear "metabolically primed" and responded more strongly to both TGFß and VPA. Treatment with VPA revealed TGFß-dependent and independent Collagen-I production in CCD-18Co cells and primary fibroblasts. VPA altered the epigenetic landscape with reduced chromatin accessibility at the COL1A1 and COL1A2 promoters. CONCLUSIONS: Increased HDAC expression profiles, H3K27ac hypoacetylation, a significant glycolytic phenotype, and metabolic priming, characterise SCD-derived as compared to NSCD fibroblasts. Our results reveal a novel epigenetic component to Collagen-I regulation and TGFß-mediated CD fibrosis. HDAC inhibitor therapy may 'reset' the epigenetic changes associated with fibrosis.
