Pattern recognition receptor and autophagy gene variants are associated with development of antimicrobial antibodies in Crohn's disease

BACKGROUND

We sought to investigate whether variants in genes involved in bacterial sensing and autophagy (NOD2, TLR5, IRGM, ATG16L1) and the interleukin-23 signaling pathway (IL12B, IL23R, STAT3) were associated with development of antimicrobial antibodies in patients with Crohn's disease (CD).

METHODS

A cohort of 616 CD patients from a tertiary referral hospital (Mount Sinai Hospital, Toronto) was evaluated. DNA was tested for three CD-associated NOD2 variants (3020insC, G908R, R702W), variants in IRGM, ATG16L1, IL12B, IL23R, STAT3, and a TLR5-stop mutation. Serum was analyzed by enzyme-linked immunosorbent assay (ELISA) for anti-Saccharomyces cerevisiae (ASCA) IgG and IgA, anti-outer membrane porin C (anti-ompC), anti-Cbir1 flagellin, and anti-Pseudomonas fluorescens (anti-I2).

RESULTS

NOD2 3020insC was associated with cumulative seroreactivity by quartile sum (P = 0.003) and number of positive antibodies (P = 0.02). NOD2 G908R was also associated with quartile sum (P = 0.05). Increased ASCA seropositivity was associated with NOD2 3020insC (odds ratio [OR] = 1.9, P = 0.02) and G908R (OR = 1.8, P = 0.05), and ATG16L1 T300A (OR = 1.4, P = 0.01) variants; ASCA-positive patients had an increased cumulative number of NOD2 3020insC and ATG16L1 T300A variants (P = 0.007). TLR5-stop mutation abrogated development of anti-flagellin in a dominant-negative fashion (OR = 0.5, P = 0.009). The IRGM CD risk variant was associated with increased anti-flagellin seropositivity (OR = 1.5, P = 0.03). IL12B, IL23R, and STAT3 variants did not contribute to development of antimicrobial antibodies.

CONCLUSIONS

Variants in innate immune genes involved in pattern recognition and autophagy but not the interleukin-23 signaling pathway influence antimicrobial seroreactivity in CD. In particular, the additive effect of NOD2 3020insC and ATG16L1 T300A suggests a role for autophagy in development of ASCA.

Biomarkers in inflammatory bowel disease: current practices and recent advances

Crohn's disease and ulcerative colitis represent the two main forms of the idiopathic chronic inflammatory bowel diseases (IBD). Currently available blood and stool based biomarkers provide reproducible, quantitative tools that can complement clinical assessment to aid clinicians in IBD diagnosis and management. C-reactive protein and fecal based leukocyte markers can help the clinician distinguish IBD from noninflammatory diarrhea and assess disease activity. The ability to differentiate between forms of IBD and predict risk for disease complications is specific to serologic tests including antibodies against Saccharomyces cerevisiae and perinuclear antineutrophil cytoplasmic proteins. Advances in genomic, proteomic, and metabolomic array based technologies are facilitating the development of new biomarkers for IBD. The discovery of novel biomarkers, which can correlate with mucosal healing or predict long-term disease course has the potential to significantly improve patient care. This article reviews the uses and limitations of currently available biomarkers and highlights recent advances in IBD biomarker discovery.

Family history and serology predict Crohn's disease after ileal pouch-anal anastomosis for ulcerative colitis

PURPOSE

Approximately 5 to 10 percent of patients undergoing ileal pouch-anal anastomosis with a diagnosis of ulcerative colitis are subsequently diagnosed with Crohn's disease. Preoperative predictors for Crohn's disease post-ileal pouch-anal anastomosis have not been prospectively defined.

METHODS

A total of 238 consecutive patients with ulcerative colitis or indeterminate colitis undergoing ileal pouch-anal anastomosis were prospectively enrolled into a longitudinal database. Clinical factors were assessed perioperatively. Serum drawn preoperatively was assayed for anti-Saccharomyces cerevisiae, antiouter membrane porin-C, anti-CBir1, and perinuclear antineutrophil cytoplasmic antibody using enzyme-linked immunosorbent assay. Crohn's disease was defined by small bowel inflammation proximal to the ileal pouch or a perianal fistula identified at least three months after ileostomy closure. Predictors were assessed in a multivariate Cox proportional hazards model to predict the rate of Crohn's disease after ileostomy closure.

RESULTS

Sixteen patients (7 percent) were diagnosed with Crohn's disease; median time to Crohn's disease was 19 (range, 1-41) months. Significant factors for postoperative Crohn's disease after ileal pouch-anal anastomosis included family history of Crohn's disease (hazard ratio, 8.4; 95 percent confidence interval, 2.96-24.1; P < 0.0001) and anti-Saccharomyces cerevisiae immunoglobulin-A seropositivity (hazard ratio, 3.14; 95 percent confidence interval, 1.1-9.81; P = 0.04). Crohn's disease developed in only 8 of 198 patients (4 percent) without these predictors vs. 8 of 40 patients (20 percent) in those with at least one of these factors (P = 0.002). The cumulative risk of Crohn's disease among patients with two risk factors (67 percent) was higher than in patients with either risk factor (18 percent) or neither risk factor (4 percent, P < 0.001).

CONCLUSIONS

Patients with ulcerative colitis and indeterminate colitis with a family history of Crohn's disease or preoperative anti-Saccharomyces cerevisiae immunoglobulin-A seropositivity are more likely to be diagnosed with Crohn's disease after ileal pouch-anal anastomosis.