Expression Alterations and Correlative Analysis of TPH1/hsa-miR-194-5p/NEAT1 and MAOA/hsa-miR-1276/NEAT1 Axes in Pediatric Inflammatory Bowel Disease

Pediatric inflammatory bowel disease (pIBD), comprising ulcerative colitis (UC) and Crohn’s disease (CD), involves complex mechanisms that include non-coding RNAs (ncRNAs), such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), alongside enzymes regulating serotonin metabolism. Tryptophan hydroxylase 1 (TPH1) and monoamine oxidase A (MAOA) play critical roles in serotonin turnover and may contribute to intestinal inflammation. We investigated the expression of TPH1, MAOA, hsa-miR-194-5p, hsa-miR-1276, and the lncRNA Nuclear Enriched Abundant Transcript 1 (NEAT1) in intestinal tissue biopsies and peripheral blood from pIBD patients and controls. TPH1 was significantly elevated in the inflamed transverse colon (p = 0.034), whereas MAOA was reduced in the ileum (p = 0.041) and descending colon (p = 0.001), with further decreases in inflamed ileum (p < 0.001), ascending (p = 0.008), and descending colon (p = 0.001). Subgroup analysis revealed decreased MAOA in the ascending colon of UC patients (p = 0.011). hsa-miR-194-5p was upregulated in the transverse colon (p = 0.015), inflamed transverse (p = 0.013) and descending colon (p = 0.015), and in blood of UC patients (p = 0.01). NEAT1 expression increased in the ascending colon (p = 0.042) but decreased in the ileum (p = 0.006). Correlation analysis showed strong positive associations between TPH1 and NEAT1 in the ileum (r = 0.945, p < 0.01) and transverse colon (r = 0.609, p < 0.01). These results highlight region-specific dysregulation of serotonin-related genes and ncRNAs in pIBD, with the TPH1/miR-194-5p/NEAT1 axis potentially contributing to disease pathophysiology and warranting further mechanistic investigation.