Interleukin-10 administration inhibits TNF-α and IL-1β, but not IL-6, secretion of LPS-stimulated peritoneal macrophages

We hypothesize that exogenous administration of anti-inflammatory cytokine interleukin (IL)-10 would affect the secretion of pro-inflammatory cytokines such as IL-1β, IL-6, or tumor necrosis factor (TNF)-α using lipopolysaccharide (LPS)-stimulated macrophages exuded from the peritoneal cavity of female BALB/c mice. The LPS-stimulated macrophages were incubated for 48 hr to investigate the secretions of pro- and anti-inflammatory cytokine. The results indicated that the secretion levels of IL-1β, IL-6, IL-10, and TNF-α by LPS-stimulated macrophages elevated in a time dependent manner during 48-hr incubation period. The amount of cytokines secretion by LPS-stimulated macrophages varied: IL-6 > TNF-α > IL-10 > IL-1β. However, the secretion of IL-10 started to decrease at 18 hr of incubation. Therefore, the macrophage cultures were extra-administrated with various concentrations (0, 75, 150, and 225 pg/ mL) of exogenous IL-10 after 18-hr incubation in order to evaluate the effect of exogenous IL-10 administration on inflammation. IL-10, 1L-1β, IL-6, and TNF-α in LPS-stimulated macrophage cultures before and after exogenous IL-10 administration were determined by ELISA. The results demonstrated that exogenous IL-10 administration inhibited IL-1β (21.3-38.6%) and TNF-α (44.7-66.8%) secretion. However, the administration did not inhibit IL-6 secretion. Low dose (75 pg/mL) of exogenous IL-10 exerted maximal effects. IL-10 levels in LPS-stimulated macrophage cultures after exogenous IL-10 administration increased from 18.4% to 35.5%. Furthermore, only low dose of exogenous IL-10 administration increased endogenous IL-10 secretion (by 10.4%), while higher doses of exogenous IL-10 inhibited endogenous IL-10 production (from 31.7% to 41.9%). The results suggest that low dose administration of exogenous IL-10 might exhibit antiinflammatory effects via inhibiting TNF-α and IL-1β, but not IL-6, secretion and increasing endogenous IL-10 production by LPS-stimulated peritoneal macrophages.