Morphological Condition of the Small Intestine after Prolonged Intake of Food Additive Carrageenan

Gubinа-Vakulik G. I., Tkachenko A. S., Orlova M. A.

MORPHOLOGY

Scentific article

One of the potential etiological factors of chronic inflammatory bowel disease is known to be a food additive E407 (carrageenan), used in the food industry as a thickener. The aim of the investigation was to study the morphological status of the small intestine and features of inflam-mation and regeneration of small intestine enterocytes during prolonged systematic intake of the food additive carrageenan. Adult female Wistar rats were used for experiment. Rats of the basic group (10 animals) received a 1% solution of carrageenan in drinking water during 4 weeks. The control group consisted of 10 intact animals. Pieces of the small intestine (5 cm above the transition to the large intestine) were taken for morphological examination. Paraffin sections were stained with hematoxylin-eosin, Einarsson’s gallocyanin-chrome alum and van Gieson’s picrofuch-sin. PAS-reaction was done. Immunohistochemical reaction to Ki-67 was used for evaluation of proliferative activity of epithelial cells and immunohistochemical reaction to IL-1α was used to evaluate the intensivity of inflammatory process. Quantitative assessment of antigen Ki-67 was performed by determining the expression level in conventional units of lumines-cence, and quantitative assessment of IL-1α was performed by determining the optical density of the cytoplasmic IL-1α-producing cells in conventional units of optical density. Intake of carrageenan during 4 weeks caused damage to the mucosal epithelium and the development of chronic interstitial inflammation. Immunohistochemical study using antibodies to IL-1α revealed significant notice-able increase not only of IL-1α-synthesizing cells number in the small intestine, but also the level of IL-1α produc-tion. It was confirmed by significant increase in conventional optical density of the cytoplasm of IL-1α-synthesizing cells in the intestinal mucosa of the basic group compared to the control group (control group – 0. 17±0. 01, basic group – 0. 31±0. 02 conventional units of optical density, p < 0. 0001). Also increased expression of Ki-67 antigen in the proliferative zone of intestinal glands was found (control group – 0. 59±0. 02, basic group – 0. 66 ± 0. 01 con-ventional units of luminescence, p < 0. 01). It was experimentally established found that the intake of food additive carrageenan within 28 days resulted in accelerated injuring of epithelial cells and the development of interstitial inflammation in small intestine. Immuno-histochemically detected activation of IL-1α synthesis and release in the mucosa of the small intestine confirms the intensity of the current inflammatory process. Reinforced death of epithelial cells is accompanied by activation of proliferative processes, confirmed by the increase in the expression of Ki-67 antigen. Active proliferation of entero-cytes is a reparative reaction for the carrageenan intake that allows us to make a suggestion that further use of car-rageenan may lead to the exhaustion of reparative capacity with the formation of erosions and ulcers in the intestine.

carrageenan, rats, inflammation, Ki-67, IL-1α

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