Serum regenerative islet-derived protein 1α: a novel and sensitive biomarker for endoscopic disease activity in...

Mucosal healing (MH) has established as a long-term therapeutic goal for inflammatory bowel disease (IBD). Regenerative Islet-derived Protein 1α (reg1α) was reported to be closely related to gastrointestinal mucosal injury; however, its potential in monitoring MH remains unexplored.

Serum reg1α levels were quantified in 156 consecutive IBD patients (January 2021-December 2023) and stratified by endoscopic findings into MH (n = 136) and non-mucosal healing (NMH) groups. Diagnostic performance of reg1α was evaluated and compared to C-reactive protein (CRP) using receiver operating characteristic analysis.

A total of 136 patients (85 with CD and 51 with UC) were finally included. Serum reg1α levels were significantly correlated with endoscopic activity. Patients in NMH group demonstrating markedly higher reg1α levels than those in MH group (92.6 vs. 55.5 ng/ml, p < 0.001). In UC, reg1α outperformed CRP in sensitivity (82.4% vs. 55.9%, p = 0.012) and accuracy (80.4% vs. 70.6%, p = 0.001) for monitoring MH. This superiority persisted in UC subgroups with non-or mild clinical symptoms. Combined index (reg1α + CRP) and multivariate model (incorporating clinical indices, reg1α and CRP) also enhanced sensitivity and accuracy over CRP alone in UC (all p < 0.05). However, reg1α showed no significantly higher efficacy in monitoring NMH compared to CRP in CD. In CRP-normal patients, patients with NMH had higher reg1α levels than those with MH in UC (77.6 vs. 49.8 ng/ml, p = 0.018), but not in CD.

Reg1α represents as a novel and sensitive biomarker of endoscopic disease activity in patients with UC, even in patients with non- or mild clinical symptoms or normal CRP levels.