Combined effect of methotrexate and phytoextracts of medow clover and common chicory on the <i>in vitro</i> production of pro-inflammatory cytokines

Usage of herbal remedies may present a tool limiting toxicity of methotrexate (MTX). The herbal products are characterized by availability, safety, high biological activity, and very low toxicity. One should highlight the meadow clover and common chicory among medicinal plants containing a variety of biologically active polyphenolic substances, possessing antioxidant, anti-inflammatory, immunocorrective and other favorable properties. Phytoextracts obtained from these plants may be used in order to protect against immunosuppressive effects of MTX and enhance its anti-inflammatory properties without inducing MTX toxicity. At the same time, it should be noted that information on the mechanisms of anti-inflammatory activity of individual phytoextracts is multidirectional. The aim of our work was to evaluate the effect of clover and chicory phytoextracts on secretion of proinflammatory cytokines TNFα, IL-6 and IL-17 by human peripheral blood mononuclear cells under MTX-induced immunosuppression. Dry extracts from clover grass and chicory grass were obtained by percolation with ethyl alcohol. The production of cytokines TNFα, IL-6 and IL-17 in the supernatants of unstimulated and concanavalin A (Con A)- stimulated human peripheral blood mononuclear cell cultures was assessed using the enzyme immunoassay method. Evaluation of immunoregulatory activity of dry extracts from clover and chicory grass, as well as their combinations with MTX using the in vitro model of human peripheral blood mononuclear cells showed that the phytoextracts suppressed the production of proinflammatory cytokines in this system, both spontaneous (TNFα, IL-6), and induced (TNFα, IL-6 and IL-17). It should be noted that the degree of inhibitory effect caused by phytoextracts was not inferior, and, in relation to individual cytokines (TNFα and IL-17), was superior to Immunal, an Echinacea-derived preparation. We have revealed inhibitory effects of clover and chicory phytoextracts, as well as their combinations with MTX, on the production of proinflammatory cytokines (TNFα, IL-6, IL-17) by human peripheral blood mononuclear leukocytes. Potentiating action of phytoextracts manifested as enhanced inhibitory effect of cytostatic MTX on the production of IL-6 by lymphocytes and the appearance of an anti-inflammatory effect on TNFα and IL-17. The most pronounced immunoregulatory effect and potentiation of anti-inflammatory MTX action was obtained by the chicory phytoextract, with both extracts exceeding the effect of Immunal, a commercial comparison drug.