Recent studies have demonstrated that members of the chemokine family play a pivotal role in modulating migration of immune cells. They also contribute to various physiological and pathological processes, including embryogenesis, immune system development, inflammation, tumor formation and metastasis. Chronic inflammatory diseases are characterized by leukocyte infiltration at the site of inflammation due to excessive production of chemokines. The ability of chemokines to induce a chemical attraction of immune cells explains the interest of researchers to the investigation of the chemokine system characteristics in various pathological processes. Fractalkine or CX3CL1 is a chemokine that promotes chemotaxis and adhesion of inflammatory cells via its highly selective receptor CX3CR1. Nowadays, the role of CX3CL1 in the progression of intestinal inflammation is poorly understood. The aim of the research is to study serum fractalkine levels in the dynamics of development of carrageenan-induced chronic gastroenterocolitis in rats. Materials and methods. The experiment was carried out on thirty white WAG rats. They were randomly divided into 3 groups. Each group consisted of ten rats. Animals of group 1 and group 2 received 1% λ-carrageenan solution daily orally for 2 weeks and 4 weeks, respectively. Carrageenan is a gelling substance produced by water extraction from algae Chondrus crispus. This heteropolysaccharide is used as a food additive. Oral exposure to carrageenan led to chronic gastroenterocolitis in animals from both group 1 and group 2. The third group consisted of intact animals. The fractalkine content in blood serum was determined by ELISA. To register the optical density of solutions, the Awareness Technology Stat Fax 303 Plus Microstrip Reader was used. The data obtained in the research were statistically processed using the Graph Pad Prism 5 application. Results and discussion. It was found out that the fractalkine content in serum of the animals from group 1 was significantly 1.5 times higher compared to the control group. Its concentration in the control group was 14.34 (13.37; 15.41) pg/ml, whereas its serum level in the rats of group 1 reached 25.48 (23.73; 28.61) pg/ml. The progression of the disease was associated with more pronounced elevated fractalkine concentrations. In animals from group 2 the serum concentration of fractalkine reached 82.11 (51.97; 87.68) pg/ml which was 5.5-fold higher than in the control group. The role of fraktalkine in chronic carrageenan-induced gastroenterocolitis most likely involves the recruitment of new monocytes and cytotoxic cells to the inflammation area. The dynamics of changes in the content of this cytokine in blood serum of rats during the development of chronic carrageenan-induced gastroenterocolitis indicates a significant role of CX3CL1 in disease progressing and maintaining the intensity of the inflammatory process by recruiting new immune cells. Conclusions. Chronic carrageenan-induced gastroenterocolitis is accompanied by the increased blood serum level of fractalkine, which increases with the progression of the disease. Fractalkine is involved in the progression of chronic carrageenan-induced gastroenterocolitis by activating chemotaxis of cytotoxic T-cells and monocytes.

Keywords: carrageenan, gastroenterocolitis, chronic inflammation, fractalkine, chemokines

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