Melatonin modulates TLR4‐mediated inflammatory genes through MyD88‐ and TRIF‐dependent signaling pathways in lipopolysaccharide‐stimulated RAW264.7 cells

Abstract

Increasing evidence demonstrates that melatonin has an anti-inflammatory effect. Nevertheless, the molecular mechanisms remain obscure. In this study, we investigated the effect of melatonin on toll-like receptor 4 (TLR4)-mediated molecule myeloid differentiation factor 88 (MyD88)-dependent and TRIF-dependent signaling pathways in lipopolysaccharide (LPS)-stimulated macrophages. RAW264.7 cells were incubated with LPS (2.0 μg/mL) in the absence or presence of melatonin (10, 100, 1000 μm). As expected, melatonin inhibited TLR4-mediated tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-6, IL-8, and IL-10 in LPS-stimulated macrophages. In addition, melatonin significantly attenuated LPS-induced upregulation of cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) in macrophages. Further analysis showed that melatonin inhibited the expression of MyD88 in LPS-stimulated macrophages. Although it had no effect on TLR4-mediated phosphorylation of c-Jun N-terminal kinase (JNK), p38, and extracellular regulated protein kinase (ERK), melatonin significantly attenuated the activation of nuclear factor kappa B (NF-κB) in LPS-stimulated macrophages. In addition, melatonin inhibited TLR4-mediated Akt phosphorylation in LPS-stimulated macrophages. Moreover, melatonin significantly attenuated the elevation of interferon (IFN)-regulated factor-3 (IRF3), which was involved in TLR4-mediated TRIF-dependent signaling pathway, in LPS-stimulated macrophages. Correspondingly, melatonin significantly alleviated LPS-induced IFN-β in macrophages. In conclusion, melatonin modulates TLR4-mediated inflammatory genes through MyD88-dependent and TRIF-dependent signaling pathways.

Melatonin Inhibits Endoplasmic Reticulum Stress and Epithelial-Mesenchymal Transition during Bleomycin-Induced Pulmonary Fibrosis in Mice

“…Melatonin has an anti-inflammatory effect. Several studies have demonstrated that melatonin alleviates lipopolysaccharide (LPS)-evoked inflammatory cytokines/chemokines [21]–[26]. According to a recent report, melatonin attenuates LPS-induced acute lung inflammation in sleep-deprived mice [27].…”

A role for melatonin in maintaining the pro- and anti-inflammatory balance by influencing leukocyte migration and apoptosis in carp

“…In human macrophages, a preincubation with LPS led to inhibition of IL-12 production by melatonin (Cutolo et al, 1999). Also, in LPS-stimulated mouse RAW 264.7 cells, melatonin inhibited the expression of TNF-a, IL-1b, IL-6, IL-8 and IL-10 (Xia et al, 2012). Melatonin pretreatment however had no effect on TNF-a, IL-1b and IL-6 synthesis in LPS stimulated rat and mice alveolar, splenic and peritoneal macrophages or mice RAW 264.7 and rat NR8383 macrophages cell lines (Shafer et al, 2001;Williams et al, 1998).…”

Impact of melatonin on immunity: a review

“…Moreover, the anti-inflammatory effect is readily proven using cell lines. For example, melatonin attenuated up-regulation of cyclooxygenase-2, iNOS, TNF-α, IL-1β and IL-6 in lipopolysaccharide-stimulated murine RAW264.7 macrophages [52]. The authors concluded that melatonin modulates inflammation through TLR-4 inflammatory genes.…”