[Tumor necrosis factor-related apoptosis-inducing ligand gene polymorphism and its plasma phenotype in relation to Crohn's disease]

Objectives: To investigate the associations of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) gene polymorphism and plasma soluble TRAIL level (sTRAIL) with Crohn's disease (CD) and to retrospectively analyze the effects of TRAIL gene variants and plasma sTRAIL levels on clinical response to infliximab (IFX). Methods: From January 2012 to January 2021, 312 CD patients [205 males, 107 females, average age (33.9±9.8) years] and 514 age-and gender-matched healthy controls [304 males, 210 females, average age (34.9±9.4) years] were recruited from the Department of Gastroenterology, the Second Affiliated Hospital of Wenzhou Medical University. Among them, 72 patients with active CD who were ineffective or intolerant to traditional drug therapy regularly received IFX (5 mg/kg) treatment. According to the changes in the Harvey-Bradshaw index (HBI) and the Simplified Endoscopic Score for Crohn's Disease (SES-CD) in the 14^th week, these patients were classified into response group (a decrease in HBI≥3 or a decrease in SES-CD≥50%) and non-response group. TRAIL (rs1131568) gene polymorphism was analyzed by matrix-assisted laser desorption/ionization time of flight mass spectrometry technique. The plasma sTRAIL level was examined by enzyme-linked immunosorbent assay (ELISA). Based on the Montreal CD classification criteria, all CD patients were divided into different subgroups. Finally, a comprehensive analysis was performed to investigate the relationship between TRAIL (rs1131568) gene polymorphism, the plasma sTRAIL level and the risk of CD, the clinicopathological characteristics of CD patients, and the clinical response to IFX. Results: The recessive model analysis showed that the homozygous variant genotype (CC) was more prevalent in patients with moderately to severely active CD than in those with mildly active CD (45.34% vs 29.23%, P=0.005). Both variant allele (C) and homozygous variant genotype (CC) in patients with stricturing and penetrating CD were more frequent than those in patients with non-stricturing and non-penetrating CD (65.48% vs 57.53%, P=0.046; 49.21% vs 31.18%, P=0.001). The dominant model analysis showed that variant allele (C) and variant genotype (TC+CC) was higher in CD patients with perianal lesions than in those without perianal lesions (66.83% vs 58.17%, P=0.037; 92.31% vs 78.37%, P=0.002). The average plasma sTRAIL level was higher in CD patients than in healthy controls [(243.04±42.74) ng/L vs (194.16±31.14) ng/L, P<0.001]. Compared with the patients with mildly active CD, the plasma sTRAIL level was increased in those with moderately to severely active CD [263.47(242.09, 281.91) ng/L vs 231.13(211.11, 247.11) ng/L, P<0.001]. The same conclusion was also drawn for the patients with stricturing and penetrating CD in contrast to those with non-stricturing and non-penetrating CD [266.18 (246.68, 289.91) ng/L vs 227.19 (204.57, 249.59) ng/L, P<0.001]. The plasma sTRAIL level was also higher in patients with perianal disease than in those without perianal disease [(261.40±41.51) ng/L vs (233.86±40.41) ng/L, P<0.001]. Multiple linear regression analysis further showed that disease activity (β=22.640, P<0.001) and homozygous variant genotype (CC) (β=16.814, P<0.001) may be positively related to the plasma sTRAIL level in CD patients independently. At the 14^th week of IFX treatment, the plasma sTRAIL level in the response group was lower than that in the non-response group [205.98(190.72, 214.56) ng/L vs (238.33±29.38) ng/L, P<0.001]. Compared with week 0, the plasma sTRAIL level was decreased in the response group in the 14^th week [(205.98 (190.72, 214.56) ng/L vs (239.89±42.43) ng/L, P<0.001]. Non-conditional logistic regression analysis showed that variant allele (C) and variant genotype (TC+CC) were less frequent in the response group than in the non-response group (53.33% vs 70.83%, P=0.037; 70.00% vs 91.67%, P=0.036). Conclusions: The increased plasma sTRAIL level may be a risk factor for CD. TRAIL (rs1131568) gene variation and the increase of plasma sTRAIL level may be associated with the increased disease activity of CD and may be the risk factors for stenosis, penetration, and perianal lesions in CD patients. In addition, TRAIL (rs1131568) gene variation or the increase of plasma sTRAIL level may be related to no response to IFX treatment in CD patients.