SERUM REG3α biomarker testing was associated with clinical and endoscopic disease activity in patients with ulcerative colitis, supporting its potential as a blood-based adjunct for disease monitoring. The findings also suggest improved performance when interpreted alongside C reactive protein (CRP), although further validation is needed.
Serum REG3α Biomarker Linked to Disease Activity
Current biomarkers including serum CRP and faecal calprotectin have recognised limitations when monitoring disease activity in ulcerative colitis. REG3α is constitutively produced by Paneth cells and functions as a bactericidal C-type protein against Gram-positive bacteria. Preliminary evidence has suggested that it may have potential as a novel blood-based biomarker.
The prospective study enrolled 128 patients with ulcerative colitis. Blood samples were collected on the same day as endoscopy and investigators measured serum REG3α, CRP, albumin, and serum calprotectin. Clinical disease activity was assessed using the total Mayo score, while endoscopic activity was evaluated using the Mayo endoscopic subscore.
Serum REG3α, CRP, albumin, and serum calprotectin all demonstrated significant correlations with clinical activity defined as a Mayo score of at least 6. The correlations were reported as follows: REG3α: ρ=0.362; p<0.001; CRP: ρ=0.429; p<0.001; albumin: ρ=−0.312; p<0.001; serum calprotectin: ρ=0.253; p=0.004.
Combined Biomarkers Improve Predictive Performance
For endoscopic activity defined as a Mayo endoscopic subscore of at least 2, serum REG3α, CRP, and albumin remained significantly associated with disease severity, whereas serum calprotectin did not. Correlations were reported as follows: REG3α: ρ=0.362; p<0.001; CRP: ρ=0.420; p<0.001; albumin: ρ=−0.240; p=0.006; serum calprotectin: ρ=0.147; p=0.098.
Investigators also evaluated the performance of combining serum REG3α with CRP. The combined approach predicted clinical activity with an area under the curve of 0.847 and endoscopic activity with an area under the curve of 0.783, outperforming either biomarker alone within this study cohort.
Serial Monitoring Findings Require Validation
Serial assessment was available for 19 patients who underwent follow up measurement of serum REG3α. Levels decreased significantly during periods of clinical improvement: p=0.005. Although these findings support the potential value of repeated blood testing, the investigators noted that they should be interpreted as preliminary because of the limited sample size.
Conclusion
Overall, the findings indicate that the serum REG3α biomarker may provide a useful adjunct for assessing both clinical and endoscopic activity in ulcerative colitis when interpreted alongside CRP. The authors concluded that further validation in larger independent cohorts, including direct comparison with faecal calprotectin, is required before broader clinical application can be considered.
Reference
Kim SJ et al. Serum REG3α as a biomarker for clinical and endoscopic activity in ulcerative colitis. Sci Rep. 2026;DOI:10.1038/s41598-026-61266-3.
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