A cell-penetrating CD40-TRAF2,3 blocking peptide diminishes inflammation and neuronal loss after ischemia/reperfusion

FASEB J. 2021 Mar;35(3):e21412. doi: 10.1096/fj.201903203RR.

Abstract

While the administration of anti-CD154 mAbs in mice validated the CD40-CD154 pathway as a target against inflammatory disorders, this approach caused thromboembolism in humans (unrelated to CD40 inhibition) and is expected to predispose to opportunistic infections. There is a need for alternative approaches to inhibit CD40 that avoid these complications. CD40 signals through TRAF2,3 and TRAF6-binding sites. Given that CD40-TRAF6 is the pathway that stimulates responses key for cell-mediated immunity against opportunistic pathogens, we examined the effects of pharmacologic inhibition of CD40-TRAF2,3 signaling. We used a model of ischemia/reperfusion (I/R)-induced retinopathy, a CD40-driven inflammatory disorder. Intravitreal administration of a cell-penetrating CD40-TRAF2,3 blocking peptide impaired ICAM-1 upregulation in retinal endothelial cells and CXCL1 upregulation in endothelial and Müller cells. The peptide reduced leukocyte infiltration, upregulation of NOS2/COX-2/TNF-α/IL-1β, and ameliorated neuronal loss, effects that mimic those observed after I/R in Cd40-/- mice. While a cell-penetrating CD40-TRAF6 blocking peptide also diminished I/R-induced inflammation, this peptide (but not the CD40-TRAF2,3 blocking peptide) impaired control of the opportunistic pathogen Toxoplasma gondii in the retina. Thus, inhibition of the CD40-TRAF2,3 pathway is a novel and potent approach to reduce CD40-induced inflammation, while likely diminishing the risk of opportunistic infections that would otherwise accompany CD40 inhibition.

Keywords: endothelial; muller cell; polymorphonuclear leukocyte; retina; toxoplasma.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CD40 Antigens / drug effects*
  • CD40 Antigens / genetics
  • CD40 Antigens / metabolism
  • Endothelial Cells / drug effects
  • Endothelial Cells / metabolism
  • Female
  • Humans
  • Inflammation / drug therapy*
  • Inflammation / metabolism
  • Ischemia / drug therapy
  • Ischemia / metabolism
  • Male
  • Mice
  • Neurons / cytology
  • Neurons / drug effects*
  • Peptides / pharmacology*
  • Reperfusion / methods
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • TNF Receptor-Associated Factor 2 / drug effects
  • TNF Receptor-Associated Factor 2 / metabolism*

Substances

  • CD40 Antigens
  • Peptides
  • TNF Receptor-Associated Factor 2