Relationship between methylation and colonic inflammation in inflammatory bowel disease

AIM:To investigate the relationship between the methylation status in the SLIT2 and TGFB2 promoters and colonic inflammation in inflammatory bowel disease patients.METHODS:We evaluated the methylation status of 2genes(SLIT2 and TGFB2)in 226 biopsies taken from62 colonoscopies of 38 patients(29 ulcerative colitis and 9 Crohn’s colitis)using methylation-specific melting curve analysis.The relationships between methylation status and clinical,biological,endoscopic and histological activities were evaluated.Twenty-three of the 38patients had a second colonoscopy and were included in a longitudinal analysis.Numerical results were given as the means±SD of the sample and range,except when specified.Student t analysis,U Mann Whitney and ANOVA factor were used to compare the means.Qualitative results were based on theχ2 test.RESULTS:SLIT2 methylation was more frequent in samples with endoscopic activity than with endoscopic remission(55%vs 18%,P<0.001).SLIT2 methylation was also higher in samples with acute inflammation(56.5%)than in samples with chronic(24%)or absent inflammation(15%)(P<0.001).For TGFB2methylation,the correlation was only significant with endoscopic activity.Methylation was higher in the distal colon for both genes(P<0.001 for SLIT2 and P=0.022for TGFB2).In the multivariate analysis,only inflammation status(and not disease duration or extension)was independently associated with SLIT2 methylation[OR=6.6(95%CI:1.65-27.36),P=0.009].In the longitudinal analysis,the maintenance of endoscopic remission was protective for methylation.CONCLUSION:Endoscopic and histological inflammation are predictive for SLIT2 methylation.