Analysis of single nucleotide polymorphisms in the region of CLDN2-MORC4 in relation to inflammatory bowel disease

AIM:To investigate a possible genetic influence of claudin(CLDN)1,CLDN2 and CLDN4 in the etiology of inflammatory bowel disease.METHODS:Allelic association between genetic regions of CLDN1,CLDN2 or CLDN4 and patients with inflammatory bowel disease,Crohn's disease(CD)or ulcerative colitis were investigated using both a casecontrol study approach(one case randomly selected from each of 191 Swedish inflammatory bowel disease families and 333 controls)and a family-based study(463 non-Swedish European inflammatory bowel disease-families).A nonsynonymous coding single nucleotide polymorphism in MORC4,located on the same linkage block as CLDN2,was investigated for association,as were two novel CLDN2 single nucleotide polymorphism markers,identified by resequencing.RESULTS:A single nucleotide polymorphism marker(rs12014762)located in the genetic region of CLDN2 was significantly associated to CD(case-control allelic OR = 1.98,95%CI:1.17-3.35,P = 0.007).MORC4 was present on the same linkage block as this CD marker.Using the case-control approach,a significant association(case control allelic OR = 1.61,95%CI:1.08-2.41,P = 0.018)was found between CD and a nonsynonymous coding single nucleotide polymorphism(rs6622126)in MORC4.The association between the CLDN2 marker and CD was not replicated in the familybased study.Ulcerative colitis was not associated to any of the single nucleotide polymorphism markers.CONCLUSION:These findings suggest that a variant of the CLDN2-MORC4 region predisposes to CD in a Swedish population.

Differences in the expression of hepatocyte growth factor in acute and chronic bowel inflammation—Implications for diagnosis?

Background: Hepatocyte growth factor (HGF) acts as an acute phase protein with regenerative properties. HGF is produced systemically and locally during inflammation but exhibits decreased binding affinity to heparan sulphate proteoglycan (HSPG)/glycosaminoglycan during chronic inflammation. We previously observed a high faecal concentration and binding affinity of HGF to HSPG during acute gastroenteritis. High faecal concentrations of calprotectin and HGF have been reported in chronic inflammatory bowel disease (IBD). Methods: Stool samples from patients with ulcerative colitis in remission (n = 11) or exacerbation (n = 5), microscopic colitis (n = 11), colon cancer (n = 6), or acute gastroenteritis caused by Clostridium difficile (n = 20), as well as healthy controls (n = 7), were analysed for the presence of HGF by ELISA, surface plasmon resonance, SDS-PAGE, and Western blot. Then in two patients with ulcerative colitis exacerbation and C. difficile infection, the expression of HGF and calprotectin was studied in colonic biopsies. Results: The faecal concentration of HGF was significantly higher in patients with ulcerative colitis compared to the other groups. The binding affinity to dextran was lower in all groups compared to acute inflammation. HGF receptor binding was similar across groups. In a patient with concomitant C. difficile infection and distal ulcerative colitis, HGF was highly expressed in the part of the bowel unaffected by ulcerative colitis, but no expression was found at the site of chronic inflammation. In the patient with total colitis the biopsies showed low expression of HGF. The areas with chronic inflammation exhibited infiltrating calprotectin-stained neutrophils. Conclusion: HGF is produced locally during inflammation of the bowel. The HGF produced during acute inflammation or exacerbations of chronic inflammation by the unaffected area shows binding affinity to glucosaminoglycans. Measuring HGF binding in faeces and biopsies may be a tool for differentiating between acute and chronic bowel inflammation, which should be assessed thoroughly in future studies.