Francisco Rausell

Role of oxidative stress and antioxidant enzymes in Crohn's disease.

There is increasing interest in oxidative stress being a potential aetiological factor and/or a triggering factor in Crohns disease, rather than a concomitant occurrence during the pathogenesis of the disease. Recent research has shown that the immune mononuclear cells of Crohns disease patients are induced to produce hydrogen peroxide (H2O2). Similarly, the regulation of antioxidant enzymes during disease in these cells has been unravelled, showing that SOD (superoxide dismutase) activity and GPx (glutathione peroxidase) activity is increased during active disease and returns to normal in remission phases. However, catalase remains constantly inhibited which supports the idea that catalase is not a redox-sensitive enzyme, but a regulator of cellular processes. ROS (reactive oxygen species) can be produced under the stimulus of different cytokines such as TNFα (tumour necrosis factor α). It has been shown in different experimental models that they are also able to regulate apoptosis and other cellular processes. The status of oxidative stress elements in Crohns disease and their possible implications in regulating cellular processes are reviewed in the present paper.

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 Crohns 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 manufacturers protocol (LeukoLOCKTM; Ambion). mRNA expression was measured by Sequenoms 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) Beltran B, et al. Inflamm Bowel Dis. 2010 16:76-86.

Different Genetic Expression Profiles of Oxidative Stress and Apoptosis-Related Genes in Crohn’s Disease

Background/Aims: Increased oxidative stress and decreased immune cell apoptosis have been reported to be important factors in the pathogenesis of Crohn’s disease (CD). Our aim was to characterize the genetic expression of molecules implicated in the regulation of oxidative stress and apoptosis in peripheral white mononuclear cells of 18 healthy volunteers (controls) and 20 patients at the onset of CD (active CD [aCD]): 10 who achieved remission (inactive CD [iCD]) and 10 who did not present a complete and deep response to treatment (aCD-T). Methods: mRNA expression was measured by the Agena MassARRAY quantitative gene expression analysis application. The genes analyzed were Fas-receptor (FASR), Fas-ligand (FASL), signal transducer and activator of transcription 1 (STAT1), nuclear factor kappa-light-chain-enhancer of activated B cells (NFKB1), apoptosis signal-regulating kinase 1 (ASK1), serine/threonine-protein kinase H1 (PSKH1), ATP-binding cassette sub-family B1 (ABCB1) and peptidylprolyl isomerase D (PPID). Results: During a CD flare, we found specific upregulated expression of the genes STAT1 and PSKH1, whereas ABCB1 and FASL were downregulated. In the patients with iCD, FASR and NFKB1 were upregulated. The expression levels of NFKB1, STAT1 and ABCB1 did not show any difference in patients with aCD at the onset of the disease and after treatment (aCD-T). The expression levels of PPID and ASK1 did not show any differences in the patients with aCD, iCD and the controls. We have also reviewed the cellular function and role of these genes in CD. Conclusions: These findings contribute to improving the understanding of the pathogenesis of CD and highlight potential genes involved.