Mannose-binding lectin (MBL) in adult patients with inflammatory bowel disease

Inflammatory bowel disease (IBD) refers to disorders associated with progressive inflammatory processes in the gastrointestinal system. IBD consists of two major forms, Crohn's disease (CD), and ulcerative colitis (UC). IBD became a global disease in the 21^st century. Its pathogenesis is still not fully understood. Mannose-binding lectin (MBL) is a pattern-recognising molecule, involved in anti-microbial and anti-cancer immunity. It is able to opsonize microorganisms and abnormal host cells, and to initiate complement activation. The aim of this study was to investigate possible involvement of MBL in inflammatory bowel disease in adults. Forty persons diagnosed with CD and 28 with ulcerative colitis were recruited. The control group consisted of 136 healthy persons. Single nucleotide polymorphisms of the MBL2 gene (localised to both promoter and exon 1) were determined as were serum MBL concentrations. The exon 1 variant alleles and MBL deficiency-associated genotypes were more frequent among patients compared with controls, although this difference was not statistically significant. No differences of MBL levels were found between the major groups. However in MBL2 A/A homozygous IBD patients, the median was significantly higher than in corresponding healthy subjects. That was particularly evident in the case of active Crohn's disease (1493 ng/ml vs. 800 ng/ml, p = 0.021). It may suggest that MBL and MBL-dependent complement activation contributes to excessive inflammation and its adverse effects in the course of CD. It cannot also be excluded that high MBL activity constitutes in some cases part of a multifactorial network conducing to development of CD.