Inhibition of CD40-TRAF6 interactions by the small molecule inhibitor 6877002 reduces neuroinflammation

J Neuroinflammation. 2017 May 12;14(1):105. doi: 10.1186/s12974-017-0875-9.

Abstract

Background: The influx of leukocytes into the central nervous system (CNS) is a key hallmark of the chronic neuro-inflammatory disease multiple sclerosis (MS). Strategies that aim to inhibit leukocyte migration across the blood-brain barrier (BBB) are therefore regarded as promising therapeutic approaches to combat MS. As the CD40L-CD40 dyad signals via TNF receptor-associated factor 6 (TRAF6) in myeloid cells to induce inflammation and leukocyte trafficking, we explored the hypothesis that specific inhibition of CD40-TRAF6 interactions can ameliorate neuro-inflammation.

Methods: Human monocytes were treated with a small molecule inhibitor (SMI) of CD40-TRAF6 interactions (6877002), and migration capacity across human brain endothelial cells was measured. To test the therapeutic potential of the CD40-TRAF6-blocking SMI under neuro-inflammatory conditions in vivo, Lewis rats and C57BL/6J mice were subjected to acute experimental autoimmune encephalomyelitis (EAE) and treated with SMI 6877002 for 6 days (rats) or 3 weeks (mice).

Results: We here show that a SMI of CD40-TRAF6 interactions (6877002) strongly and dose-dependently reduces trans-endothelial migration of human monocytes. Moreover, upon SMI treatment, monocytes displayed a decreased production of ROS, tumor necrosis factor (TNF), and interleukin (IL)-6, whereas the production of the anti-inflammatory cytokine IL-10 was increased. Disease severity of EAE was reduced upon SMI treatment in rats, but not in mice. However, a significant reduction in monocyte-derived macrophages, but not in T cells, that had infiltrated the CNS was eminent in both models.

Conclusions: Together, our results indicate that SMI-mediated inhibition of the CD40-TRAF6 pathway skews human monocytes towards anti-inflammatory cells with reduced trans-endothelial migration capacity, and is able to reduce CNS-infiltrated monocyte-derived macrophages during neuro-inflammation, but minimally ameliorates EAE disease severity. We therefore conclude that SMI-mediated inhibition of the CD40-TRAF6 pathway may represent a beneficial treatment strategy to reduce monocyte recruitment and macrophage activation in the CNS and has the potential to be used as a co-treatment to combat MS.

Keywords: Co-stimulation; EAE; Inflammation; Monocytes; Multiple sclerosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Inflammatory Agents / pharmacology
  • Anti-Inflammatory Agents / therapeutic use*
  • CD40 Antigens / metabolism*
  • Cell Movement / drug effects
  • Cell Movement / genetics
  • Cells, Cultured
  • Cerebellum / metabolism
  • Disease Models, Animal
  • Encephalomyelitis, Autoimmune, Experimental / chemically induced
  • Encephalomyelitis, Autoimmune, Experimental / drug therapy*
  • Encephalomyelitis, Autoimmune, Experimental / pathology
  • Gene Expression Regulation / drug effects
  • Gene Expression Regulation / immunology
  • Humans
  • Matrix Metalloproteinase 9 / genetics
  • Matrix Metalloproteinase 9 / metabolism
  • Mice
  • Monocytes / drug effects*
  • Monocytes / immunology
  • Myelin-Oligodendrocyte Glycoprotein / toxicity
  • Nitric Oxide Synthase Type I / metabolism
  • Peptide Fragments / toxicity
  • Rats
  • Rats, Inbred Lew
  • Reactive Oxygen Species / metabolism
  • Spinal Cord / metabolism
  • TNF Receptor-Associated Factor 6 / metabolism*
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • Anti-Inflammatory Agents
  • CD40 Antigens
  • Myelin-Oligodendrocyte Glycoprotein
  • Peptide Fragments
  • Reactive Oxygen Species
  • TNF Receptor-Associated Factor 6
  • Tumor Necrosis Factor-alpha
  • myelin oligodendrocyte glycoprotein (35-55)
  • Nitric Oxide Synthase Type I
  • Nos1 protein, mouse
  • Matrix Metalloproteinase 9
  • Mmp9 protein, mouse