Mechanism of short-term antiinflammatory effect of 5,5-dimethyl- 1- pyrroline n-oxide,

MUÑOZ MARCOS; GUTIERREZ LUCAS JOEL; ENRIZ, RICARDO D.; ALVAREZ SERGIO; RAMIREZ DARIO

Congreso; Society for Redox Biology and Medicine; 2016

5,5-dimethyl-1-pirroline N-oxide (DMPO) is a nitrone spin traporiginally synthesized as a nitrone spin trap to study free radicalsby electron spin resonance spectroscopy and recentlyby immuno-spin trapping. Herein we envisioned at studyingwhat are the mechanisms involved in these anti-inflammatoryeffects of this old drug with new properties. To accomplish thisgoal we used a well known model of macrophage-like cells(RAW264.6) primed with LPS; which induce a well known MAPKsignaling cascade that ends in activation of NF-kB?the masterregulator of inflammation, inducible nitric oxide (iNOS)expression and nitric oxide synthesis. DMPO blocked NOsynthesis, iNOS induction and MAPK signaling; but it did notaffect LPS binding to LPS to membrane receptors. Thus wehypothesized that DMPO, and likewise other nitrones, maysomehow affect very early LPS triggered signaling downstreamof LPS-receptor binding. In silico data showed that DMPO bindsto a very narrow sequence of aminoacids inside the TIR domainof TLR-2. TIR domains are conserved throughout TLRs (TLR-4;6; 10) and species, particularly in a region called BB-loop whichis responsible for downstream signal transduction. Moleculardynamics data shows that DMPO binds almost exclusively tothese residues located at the BB-loop. Taking together, our dataindicate that DMPO anti-inflammatory effect, is at least in partdue to its binding to specific residues in the cytoplasmic portionof TLRs, thus further signaling is damped.