INTESTINAL BARRIER INTEGRITY UNDER EFFECT OF PARTICULATE MATTER FROM COTTONWOOD COMBUSTION

Abstract

The epidemiological data pointed out that exposure to ambient air pollution particulate matter (PM) may increase the risk of irritable bowel syndrome and ulcerative colitis. Air pollutants might affect the intestine through blood, mucociliary clearance of PM from the lungs, by polluted food or water intake. In the present study, we tested the hypothesis that water-suspended smoke preparations (SP) derived from the combustion of cottonwood might affect the integrity of the intestinal mucosa, induce an inflammatory response, and increase the susceptibility to chemically-induced colonic inflammation. Smoke from cottonwood was collected under laboratory conditions during the entire flaming, smouldering, and mixed combustion phases. Male Wistar rats (180-200 g) were injected with SP in two ways: 1) into the tail vein at a dose of 500 µg/100 g; 2) by gavage at a dose of 180 µg/100 g. The experimental colitis was induced 1 hour after SP injection by a single rectal injection of 0.1 ml 6% iodoacetamide (7 cm from the anus). Rats were euthanized in 2 h after colitis induction. We examined colonic vascular permeability by Evans blue extravasation (mg/g wet colon), myeloperoxidase level, total glycoprotein level at surface mucus by PAS-staining, and intestinal permeability by the translocation of bacteria into the blood of the portal vein. This study demonstrates that intravenous administration of the SP decreases the amount of surface mucus in the large intestine and increases myeloperoxidase activity in the rat colon. It did not increase the negative effect of iodoacetamide-induced colitis on changes in the state of the endothelial barrier. But, intravenous administration of SP led to the appearance of blood in the urine, which may be due to the damage to the fenestrated capillaries of the glomerulus. At the same time, oral administration of SP increased the translocation of bacteria into the blood of the portal vein which represents the increased gut permeability accompanied by a reduced level of total glycoprotein of colonic surface mucus. However, oral administration of SP did not have a significant effect on colonic vascular permeability and the activity of myeloperoxidase vs. the placebo group with colitis. The airborne PM obtained from the combustion of natural precursors such as cottonwood can cause primary pro-inflammatory changes in the intestines in a very short time after penetration into the organism through the blood and oral ingestion. Moreover, they can contribute to the violation of the integrity of the intestinal barrier.