The effect of hydrogen sulfide on cytokine production by blood mononuclear leukocytes in <i>in vitro</i> culture of rats with different metabolic status

BACKGROUND: Despite the established role of hydrogen sulfide (H2S) in the regulation of many cellular functions, the mechanisms of its effects continue to come to light, especially concerning pathogenetic significance of the gasotransmitter in chronic systemic inflammation accompanying metabolic syndrome (MS). AIM: To conduct a comparative evaluation of changes in the cytokine-producing activity of peripheral blood mononuclear leukocytes under the influence of H2S in in vitro culture of rats with an experimental model of MS and animals with normal metabolic status. METHODS: The studies were conducted on a primary culture of mononuclear leukocytes isolated from heparinized blood of laboratory animals (rats) with modeled MS by gradient centrifugation method. A series of experimental samples of cell suspension was obtained from animals with MS, and a control series was obtained from intact animals. Cells were cultured in a complete nutrient medium (based on RPMI-1640) for 24 hours in 2 variants: without and with the addition of the hydrogen sulfide donor sodium hydrosulfide (NaHS) at a final concentration of 100 μM. In the conditioned medium, the concentration of cytokines was determined using the enzyme-linked immunosorbent assay method: tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), interleukin 10 (IL-10), monocyte chemoattractant protein 1 (MCP-1), and transforming growth factor beta (TGF-â). RESULTS: Blood mononuclear leukocytes of animals with different metabolic status differently responded to addition of hydrogen sulfide donor in in vitro culturing: in healthy rats, a decrease in IL-6 production was observed (on average 1.4 times compared to the baseline secretion level, р = 0.03), whereas in the group of animals with MS, on the contrary, an increase in the concentration of IL-6 (on average, 1.4 times, р = 0.025), TNF-α (on average, 2 times, р = 0.028) and MCP-1 (on average, 1.4 times, р = 0.039) was recorded. CONCLUSION: Multidirectional action of hydrogen sulfide on the synthesis of proinflammatory cytokines and its more prominent modulating effect on cells of animals with MS suggests that the effects of H2S on leukocytes depend on in vivo metabolic conditions (the concentration of glucose, triacylglycerols, humoral inflammatory factors, adipokines, etc.), which mediate epigenetic mechanisms regulating the expression of genes responsible for the final effects of the gasotransmitter.