Molecular Discoveries Alter Our View of Inflammatory Bowel Disease

Exacerbated tissue destruction in DSS-induced acute colitis of OPN-null mice is associated with downregulation of TNF-alpha expression and non-programmed cell death

Osteopontin (OPN), a pro-inflammatory mediator, is constitutively expressed in normal gut and is upregulated in inflammatory colitis. To determine the significance of OPN in inflammatory bowel disease, we studied the development of acute, experimental colitis induced by dextran sulfate sodium (DSS) in OPN-null and wild-type (WT) mice. OPN expression was markedly increased in WT diseased colons, while a higher disease activity index, including spleen enlargement, bowel shortening, and mucosal destruction, was observed in OPN-null mice. Although peripheral blood neutrophil numbers were lower in DSS-treated OPN-null mice, tissue myeloperoxidase levels, reflecting enhanced neutrophil activity, were increased in the diseased colons. In comparison, lymphocyte numbers in peripheral blood were increased earlier than in DSS-treated WT mice. Despite a significantly greater spleen enlargement, flow cytometric analysis of splenocytes from the DSS-treated OPN-null mice revealed lower numbers of differentiated macrophages and (CD4+ and CD8alpha+) lymphocytes. Whereas pro-inflammatory cytokines, including G-CSF, RANTES, MIP1alpha, and TNF-alpha, were increased < 10-fold in DSS-treated WT splenocytes, expression of these cytokines was dramatically suppressed in the DSS-treated OPN-null splenocytes as well as gut tissues. The suppressed TNF-alpha response in OPN-null mice was reflected in a marked increase in non-apoptotic cell death in diseased colons. Collectively, these studies demonstrate that OPN is required for mucosal protection in acute inflammatory colitis.

Crohn's disease is associated with polymorphism of CARD15/NOD2 gene in a Hungarian population

Crohn's disease (CD) is commonly classified as an immune-mediated disorder, but genetic and environmental factors seem to be important in its pathogenesis. Mutations within the CARD15/NOD2 gene have been associated with CD in the Caucasian population. The aim of our work was to investigate the allele frequency and clinical impact of the three common mutations in Hungarian CD patients and healthy controls. Seventy-four CD patients and 107 controls were examined. The genotyping of the three common CARD15/NOD2 mutations (Arg702Trp, Gly908Arg, and Leu1007fsinsC) was carried out by restriction fragment length polymorphism (RFLP) and amplification refractory mutation system (ARMS) techniques. The demographic and clinical parameters were correlated with chi(2) analysis. The overall prevalence of CARD15/NOD2 mutations in the Hungarian CD patients (33.78%) was significantly higher than in healthy control individuals (16.23%) (P < 0.025). The allele frequency of the Gly908Arg mutation did not differ, but the Arg702Trp and Leu1007fsinsC mutation were more common in CD patients than in controls. The onset of CD occurs about three years earlier in CARD15/NOD2 carriers. Carriage of the Arg702Trp and Leu1007fsinsC allele within the CARD15/NOD2 gene is associated with CD. These data are in line with similar findings showing a role of the CARD15/NOD2 protein in the etiopathogenesis of CD. The genotyping of these mutations might be used to identify high-risk patients.