Aspects of free radical oxidation in the large bowel in ulcerative colitis and Crohn’s disease
Research into the accumulation patterns of protein oxidative modification (POM) products and lipids in Crohn’s disease (CD) and ulcerative colitis (UC) could have important implications for understanding the pathogenesis and improving the diagnosis and therapy for these diseases. The aim of this study was to investigate the aspects of free radical oxidation (FRO) in the large bowel and their possible correlations with clinical symptoms of UC and CD. In the Wistar rat model used in the experiment, CD was induced with 2,4,6-trinitrobenzenesulfonic acid, and UC was induced with oxazolone. Clinical status was assessed using the Disease activity index (DAI). Lipid peroxidation (LPO) products were measured in the heptane and isopropanol phases of the intestinal mucosa extract. POM products were measured following spontaneous and stimulated oxidation. The DAI ( Me (Q25–Q75)) was increased in both CD and UC on days 3 and 7 of the experiment: for CD, it was equally increased on days 3 and 7 (7 (3-7)) and was 11 (11–11) and 11 (9–11) for UC on days 3 and 7, respectively. The amount of primary, secondary and end LPO products in the heptane and isopropanol phases, as well as the total amount of POM products, was increased in the homogenized mucosa of the large bowel. In the CD group, the relative content of secondary basic POM products was increased on day 7 of the experiment. The following patterns of FRO were revealed: accumulation of LPO products in the UC group and accumulation of POM products in the CD group; UC is characterized by the accumulation of mostly LPO products in the heptane phase and secondary LPO products in the isopropanol phase; CD is characterized by the accumulation of secondary basic POM products. DAI scores were correlated with the amount of LPO products in the isopropanol phase and the amount of POM products in the spontaneous oxidation mode. The highest number of strong correlations was observed in the UC group. Our findings suggest a very serious contribution of FRO changes to the pathogenesis of UC and CD, meaning that LPO and POM products could be regarded as diagnostic markers and indicators of treatment efficacy.
Keywords: lipid peroxidation, oxidative stress, protein oxidative modification, large bowel, ulcerative colitis, Crohn's disease