Interaction between seroreactivity to microbial antigens and genetics in Crohn's disease: is there a role for defensins?

ABSTRACT

Antibodies against different microbial epitopes are associated with disease phenotype, may be of diagnostic importance and may reflect a loss of tolerance in Crohn's disease (CD). Recently, an association was reported between the presence of these antibodies and mutations in pattern receptor genes. Our aim was to investigate whether mutations in various genes other than NOD2/CARD15 or TLR4 associated with CD (NOD1/CARD4, DLG5 and DEFB1) may influence the presence of antibodies against bacterial proteins and carbohydrates in a Hungarian cohort of CD patients. Three hundred and seventy-six well-characterized, unrelated, consecutive CD patients (male/female 191/185, age at onset 29.1 +/- 12.9 years, duration 7.9 +/- 11.7 years) were investigated. Sera were assayed for anti-Omp, anti-Saccharomyces cerevisiae antibodies (ASCAs) immunoglobulin (Ig) A and IgG, and antibodies against a mannan epitope of S. cerevisiae (gASCA), laminaribioside (ALCA), chitobioside (ACCA), and mannobioside (AMCA). NOD1/CARD4, DLG5 and DEFB1 variants were tested by polymerase chain reaction-restriction fragment length polymorphism, and DEFB1 was genotyped in a subgroup of 160 patients. Detailed clinical phenotypes were determined by reviewing the patients' medical charts. The carriage of DEFB1 20A variant alleles less frequently led to antiglycan positivity compared with patients without (29.6% vs 46.2%, OR 0.49, 95% CI 0.25-0.97), regardless of disease location or behavior. Similar tendency was observed for DEFB1 44G (present 21.6% vs absent 10.2%, P = 0.06) and ALCA. A gene or serology dosage effect was not observed. However, no association was found between the DEFB1 G52A, DLG5 R30Q, and NOD1/CARD4 E266K variants and any of the serology markers. We found that variants in human beta-defensin 1 gene are inversely associated with antiglycan antibodies, further confirming an important role for innate immunity in the pathogenesis of CD.