LEUCINE-RICH ALPHA 2 GLYCOPROTEIN: A USEFUL BIOMARKER TO DISCRIMINATE SMALL INTESTINAL MUCOSAL HEALING IN C-REACTIVE PROTEIN-NEGATIVE CROHN’S DISEASE
Authors: Tanaka Akihito , Kanmura Shuji , Maeda Nobuhisa , Kuwazuru Kosuke , Komaki Fukiko , Komaki Yuga , Ido Akio 
Published: January 2024

Abstract

BACKGROUND
The treatment goals for inflammatory bowel disease, including Crohn's disease (CD), have shifted from clinical remission to mucosal healing. However, frequent endoscopies burden patients. Leucine-rich alpha 2 glycoprotein (LRG), produced by hepatocytes, neutrophils, and the intestinal epithelium, is more gut-specific than C-reactive protein (CRP). We examined whether LRG, as a biomarker, can detect small intestinal mucosal healing in CD patients, especially in those who are CRP-negative.

METHOD
1) This study examined CD patients who visited our department from May 2021 to April 2023, had LRG measured, and underwent image evaluation using capsule endoscopy or balloon-assisted endoscopy. We analyzed their clinical background, looked for a correlation between LRG and CRP, assessed the ROC-AUC of LRG and CRP for mucosal healing, and measured the LRG and CRP cutoff values to determine mucosal healing. 2) Next, in CRP-negative CD patients, we analyzed the ROC-AUC of LRG for mucosal healing and LRG cutoff value to determine mucosal healing. Endoscopic evaluation was done within 3 months before and after LRG measurement. Absent open ulcers indicated mucosal healing. The upper limit of normal CRP value was &lt;3 mg/L. We used the Spearman correlation coefficient to determine the correlation.

RESULTS
1) Here, 67 CD patients were analyzed; 43 (64%) were men. The median age (range) of onset was 25.6 (3-57) years. The median disease duration (range) was 7.6 (0-27) years. B1, B2, and B3 of Montreal Classification were established in 31 (46.2%), 21 (31.3%), and 15 (22.3%) patients, respectively. The median (range) of LRG was 21.7 (7.6-67.4) μg/mL. The median (range) of CRP was 10.8 (0.0-86.9) mg/L. LRG and CRP were strongly correlated (r=0.878, p&lt;0.001). The ROC-AUC of LRG for mucosal healing was 0.839 (95% confidence interval [CI] 0.760-0.918). LRG cutoff value for discriminating mucosal healing was 15.5 μg/mL (sensitivity 77%, specificity 75%). The ROC-AUC of CRP for mucosal healing was 0.811 (95% CI 0.721-0.900). The CRP cutoff value to differentiate mucosal healing was 0.9 mg/L (sensitivity 55%, specificity 90%). 2) Forty CRP-negative CD patients were analyzed; 23 (57%) were men. The median age (range) of onset was 21.9 (3-57) years. The median disease duration (range) was 7.0 (0-27) years. B1, B2, and B3 of Montreal Classification were established in 17 (42.5%), 12 (30.0%), and 11 (27.5%) patients, respectively. The median (range) of LRG was 12.3 (7.6-23.5) μg/mL. The ROC-AUC of LRG for mucosal healing was 0.817 (95% CI 0.696-0.938). The LRG cutoff value to differentiate mucosal healing was 14.1 μg/mL (sensitivity 61%, specificity 76%).

CONCLUSION
LRG may be a better biomarker than CRP for assessing endoscopic remission of the small intestinal mucosa in CD. In CRP-negative CD patients, LRG level of ≥14.1 μg/mL could indicate small intestinal ulcers.