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Tissue expression of neutrophil elastase is better than histologic activity for predicting long-term relapse in patients with ulcerative colitis in remission.

The tissue expression level of neutrophil elastase is better than histologic activity for predicting long-term relapse in patients with ulcerative colitis (UC) who have achieved clinical and endoscopic remission, according to study findings published in Inflammatory Bowel Diseases.

“Neutrophils, the most abundant human leukocytes, are the first responders of the innate immune system to infections and inflammatory processes,” researchers wrote. “They recruit and activate a broad spectrum of immune cells by releasing cytokines and chemokines. They also produce proteases that directly contribute to epithelial barrier dysfunction, as well as intra- and extracellular degradation.”

The study investigated whether tissue expression of neutrophil elastase or calprotectin, which is also produced by neutrophils, could predict risk of relapse in 218 patients in clinical and endoscopic UC remission who underwent rectal biopsies. Investigators used the Robarts Histological Index to score histologic activity and immunohistochemistry to evaluate tissue neutrophil elastase and calprotectin levels in biopsy samples.

Researchers followed up 204 patients for an average of 18.6 months to investigate the cumulative risk of clinical relapse.

Findings Based on Low Versus High Tissue Neutrophil Elastase

Patients with histologic activity had significantly higher tissue neutrophil elastase and calprotectin levels than patients in histologic remission, according to the results.

Investigators found a significantly lower 3-year clinical relapse risk in the low-tissue neutrophil elastase group (<22.08 per mm²) compared with the high-tissue neutrophil elastase group (≥22.08 per mm²). However, the risk did not differ between the groups with low-tissue calprotectin (<10.61 per mm²) and high-tissue calprotectin (≥10.61 per mm²).

Unlike histologic index and tissue calprotectin, a low level of tissue neutrophil elastase expression was independently associated with a decreased risk for 3-year clinical relapse (adjusted hazard ratio, 0.453) on multivariate analysis.

The study also found a decreased risk of 3-year relapse with the use of biologics for maintenance treatment but an increased risk with previous steroid exposure.

“Based on our findings, the low tissue expression level of neutrophil elastase in quiescent UC may be used to predict long-term outcomes more accurately than the histological index,” researchers wrote. “Future studies are needed to demonstrate whether altering management strategies based on tissue neutrophil elastase is clinically beneficial.”