Fibroblast pentose phosphate pathway activation upon decreased circPLCE1 exacerbates intestinal fibrosis in Crohns disease

Background Intestinal fibrosis, a hallmark complication of Crohn's disease (CD), frequently progresses to stricture formation and surgical intervention. Fibroblast metabolic reprogramming is important in organ fibrosis.

However, its role in intestinal fibrogenesis of CD remains elusive. Objective We aim to explore the metabolic reprogramming of fibroblasts and its upstream regulators during intestinal fibrosis of CD.

Design We performed metabolome, single-cell RNA sequencing and spatial transcriptome on paired mucosal and submucosal tissue from the strictured and adjacent non-strictured intestinal segments. The candidate metabolite and metabolic enzymes were verified in primary human intestinal myofibroblasts (HIMFs) and dextran sulfate sodium-induced intestinal fibrotic mice.

Next, we identified fibrosis-associated circPLCE1 to regulate the pentose phosphate pathway (PPP) using the circRNA transcriptome. Finally, we studied the functions and mechanisms of circPLCE1 using metabolome, transcriptome, metabolic flux, seahorse assay and RNA pull-down assay in HIMFs and fibroblast-specific circPLCE1 knockdown mice.

Results Multilayer integrated analysis identified activation of PPP in fibroblasts during intestinal fibrosis of CD. Specifically, xylulokinase (XYLB)-generated xylulose-5-phosphate (Xu5P) promoted extracellular matrix synthesis by epigenetic upregulation of collagen transcription.