[Nle4, D-Phe7]-α-MSH Inhibits Toll-Like Receptor (TLR)2- and TLR4-Induced Microglial Activation and Promotes a M2-Like Phenotype

PLoS One. 2016 Jun 30;11(6):e0158564. doi: 10.1371/journal.pone.0158564. eCollection 2016.

Abstract

α-melanocyte stimulating hormone (α-MSH) is an anti-inflammatory peptide, proved to be beneficial in many neuroinflammatory disorders acting through melanocortin receptor 4 (MC4R). We previously determined that rat microglial cells express MC4R and that NDP-MSH, an analog of α-MSH, induces PPAR-γ expression and IL-10 release in these cells. Given the great importance of modulation of glial activation in neuroinflammatory disorders, we tested the ability of NDP-MSH to shape microglial phenotype and to modulate Toll-like receptor (TLR)-mediated inflammatory responses. Primary rat cultured microglia were stimulated with NDP-MSH followed by the TLR2 agonist Pam3CSK4 or the TLR4 agonist LPS. NDP-MSH alone induced expression of the M2a/M2c marker Ag1 and reduced expression of the M2b marker Il-4rα and of the LPS receptor Tlr4. Nuclear translocation of NF-κB subunits p65 and c-Rel was induced by LPS and these effects were partially prevented by NDP-MSH. NDP-MSH reduced LPS- and Pam3CSK4-induced TNF-α release but did not affect TLR-induced IL-10 release. Also, NDP-MSH inhibited TLR2-induced HMGB1 translocation from nucleus to cytoplasm and TLR2-induced phagocytic activity. Our data show that NDP-MSH inhibits TLR2- and TLR4-mediated proinflammatory mechanisms and promotes microglial M2-like polarization, supporting melanocortins as useful tools for shaping microglial activation towards an alternative immunomodulatory phenotype.

MeSH terms

  • Animals
  • Cells, Cultured
  • Interleukin-10 / metabolism
  • Lipopeptides / pharmacology
  • Lipopolysaccharides / pharmacology
  • Microglia / drug effects*
  • Microglia / metabolism
  • Rats
  • Toll-Like Receptor 2 / agonists*
  • Toll-Like Receptor 2 / metabolism
  • Toll-Like Receptor 4 / agonists*
  • Toll-Like Receptor 4 / metabolism
  • Tumor Necrosis Factor-alpha / metabolism
  • alpha-MSH / analogs & derivatives*
  • alpha-MSH / pharmacology

Substances

  • Lipopeptides
  • Lipopolysaccharides
  • Pam(3)CSK(4) peptide
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Tumor Necrosis Factor-alpha
  • Interleukin-10
  • alpha-MSH
  • MSH, 4-Nle-7-Phe-alpha-

Grants and funding

This research was supported by grants from ANPCyT (Agencia Nacional de Promoción Científica y Técnica) PICT 0894, CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas) PIP 630 and University of Buenos Aires 20020130100120BA. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.