Tu1913 Differential Regulation of Oxidative Stress and Apoptosis Related Genes During Active and Inactive Crohn's Disease (CD)

Background: An increase of oxidative stress (OxS) and a decrease of apoptosis have been reported as key factors in Crohn's disease (CD) pathogenesis.We have previously shown that OxS in CD depends on an increased production of H2O2 which detoxification is independent of catalase (CAT) enzyme because CAT showed permanently inhibited in CD patients1.CAT could be more implicated in regulating cellular processes, as apoptosis, than in detoxifying H2O2.Aims: To characterize the genetic expression of CAT and other OxS and apoptosis related genes in CD at beginning of the disease and when remission has been achieved.Methods: Blood samples were obtained from 18 healthy subjects (H), 20 patients at onset of CD and yet to begin any specific medication (active CD, aCD) and from 10 patients who achieved clinical, analytical and morphological remission (inactive CD, iCD).Patients were diagnosed according to Leonard-Jones criteria and disease activity was scored based on the Harvey-Bradshaw index, serological markers of inflammation (CRP, fibrinogen) and evaluation of morphological lesions (magnetic resonance enterography, colonoscopy or capsule endoscopy).PWMC were isolated by Histopaque sedimentation.Total RNA from leukocytes was extracted according to manufacturer's protocol (LeukoLOCK™; Ambion).mRNA expression was measured by Sequenom's MassARRAY® quantitative gene expression analysis application.The genes analyzed were: CAT, SOD2, NOS2A, STAT1, NFKB1, PKCgamma, PKCzeta, PSKH1, PPID, ABCB1, ASK1, FASR, FASLG, TERT, IL-2, IL23R.Results: Genes differentially expressed in CD are summarized in the table.Specific upregulated genes during flair were SOD2, STAT1, and PSKH1, and down-regulated were FASL and ABCB1.In iCD, FASR and NFKB1 were up-regulated.The down-regulation of CAT gene expression was persistent.Conclusions: Up regulation of SOD2, STAT1 and PSKH1 only during a flare, indicates the relation between OxS and aCD.Down regulation of FASL and ABCB1 shows an apoptotic and multidrug resistance alteration at onset of the disease.Increased expression of FASR and NFKB1 in iCD could indicate that apoptosis are genetically affected in CD.Permanent inhibition of CAT activity in CD patients correlates to a persistent down regulation of the CAT-gene mRNA.The implications of CAT inhibition in regulating cellular processes such as apoptosis should be studied.1)