Influence of microbial polyamines on the IL-10 production by peripheral blood leukocytes of healthy donors

As is known, bacterial polyamines, which include cadaverine and putrescine, are capable of influencing the activity of immunocompetent cells in many ways. In particular, this situation is observed in long-term inflammatory diseases, especially with intensive reproduction of microorganisms capable of producing polyamines. It is of interest to study the production of one of the main anti-inflammatory cytokines, IL-10, under the influence of bacterial polyamines. For research, a population of mononuclear leukocytes was isolated from the peripheral blood of healthy donors by gradient centrifugation. The cell suspension was placed in a round-bottomed plates with preliminarily added polyamines at concentrations of 5, 25, 50, 75, and 100 mmol/L. Wells not containing polyamines were used as a control. After incubation for 72 h at 37 °C and 5% CO2, the supernatants were harvested and used to determine the concentration of IL-10. We used a kit for determining the concentration of IL-10 using the enzyme immunoassay method (Russia). Statistical analysis was performed using the Statistica 6.0 software package. In the case of a distribution close to normal, Student’s t-test was used; in the rest, the Mann–Whitney test was used to assess the significance of differences. Studies have shown that leukocytes in the presence of concanavalin A produce IL-10 at a concentration of 17.13±6.08 pg/mL. It has been established that under the influence of polyamines of bacterial origin, the production of IL-10 is enhanced only if putrescine and cadaverine are at concentrations of 50 mmol/L and higher. At low concentrations of polyamines, no significant increase in IL-10 production was detected. Since IL-10 is an anti- inflammatory cytokine, for which the analgesic effect is also known, it should be expected that with an increase in its concentration in the focus of invasion of opportunistic bacteria, the inflammatory process will develop latently, when the symptoms are mild. In general, it can be expected that polyamine-producing bacteria will contribute to the maintenance of few symptomatic inflammation.