Clinical and Morphological Analysis of Efficacy of Intraperitoneal Ozone Application in Experimental Colitis: Preclinical Randomized Experimental Study

Background. Inflammatory bowel diseases — Crohn’s disease and ulcerative colitis — are chronic gastrointestinal diseases affecting young people of working age. An alternative to basic therapy (5-aminosalicylic acid) for inflammatory bowel disease is the use of ozone, which has anti-inflammatory, immunomodulatory, antibacterial properties and no side effects in therapeutic concentrations. Objective. To perform clinical and morphological analysis of efficacy of intraperitoneal ozone application in experimental colitis.

Methods. The study was conducted on 73 male Wistar rats weighing 200-250 g. The animals were divided into four groups by simple randomization. Check studies were performed on the second, fourth and sixth days. Oxazolone-induced colitis was simulated in two stages using a 3%-alcohol oxazolone solution. Ozone-acid mixture was obtained on “UOTA-60-01” unit (“Medozone”, Russia). Rectal suppositories with 5-aminosalicylic acid were prepared on the basis of rectal suppositories “Salofalk”. Clinical status was assessed daily according to the disease activity index (DAI) scale. Morphological evaluation of colon lesion tissue fragments was carried out using a PrimoStar microscope (CarlZeiss, Germany). Colon tissue damage was assessed using tissue damage index (TDI). Statistical analysis was conducted with SPSS Statistics 19 (IBM, USA).

Results. Clinical and morphological picture of the large intestine lesion in oxazolone-induced colitis on days 2, 4 and 6 is consistent with the changes typical of inflammatory bowel disease in humans. Daily intraperitoneal insufflation of ozone at a dose of 0.05 mg/kg in oxazolone-induced colitis leads to partial restoration of DAI, reduction in neutrophils, eosinophils, histiocytes, and fibroblasts in the lesion, as well as to a decrease in ulcerous defect diameter and TDI. The effects of intraperitoneal insufflations of ozone in oxazolone-induced colitis as compared to rectal suppositories with 50 mg of 5-aminosalicylic acid every 12 hours were less marked for the DAI index on day 4; for the number of eosinophils, plasma cells, histiocytes — on day 2, 4 and 6; for lymphocytes — on day 6.

Conclusion. Clinical and morphological picture of the large intestine lesion in ozone-induced colitis correlates with the changes typical of inflammatory bowel disease in humans. The positive effect of ozone in ozone-induced colitis was driven by its anti-inflammatory properties through the activation of Nrf2 and by its antioxidant properties through the inhibition of Keap1.