Mechanism of Short Term Anti-Inflammatory Effect of 5,5-Dimethyl-1-Pyrroline N-Oxide

MARCOS D MUNOZ; LUCAS J GUTIERREZ1; DANIEL R ENRIZ; SERGIO E ALVAREZ; ROBERT A FLOYD; SANDRA E GOMEZ MEJIBA; DARIO C RAMIREZ

Congreso; SFRBM; 2016

">98Mechanism of Short Term Anti-Inflammatory Effectof 5,5-Dimethyl-1-Pyrroline N-OxideMarcos D Munoz1, Lucas J Gutierrez1, Daniel R Enriz2, Sergio EAlvarez2, Robert A Floyd2, Sandra E Gomez Mejiba2, And Dario CRamirez11Conicet-Unsl, San Luis, Argentina, 2 OMRFf, Oklahoma City, USA5,5-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 recently by immunospin trapping. Herein we envisioned at studying what are themechanisms involved in these anti-inflammatory effects of this olddrug with new properties. To accomplish this goal we used a wellknown model of macrophage-like cells (RAW264.6) primed withLPS; which induce a well known MAPK signaling cascade thatends in activation of NF-kB?the master regulator of inflammation,inducible nitric oxide (iNOS) expression and nitric oxide synthesis.DMPO blocked NO synthesis, iNOS induction and MAPK signaling;but it did not affect LPS binding to LPS to membrane receptors.Thus we hypothesized that DMPO, and likewise other nitrones,may somehow affect very early LPS triggered signalingdownstream of LPS-receptor binding. In silico data showed thatDMPO binds to a very narrow sequence of aminoacids inside theTIR domain of TLR-2. TIR domains are conserved throughoutTLRs (TLR-4; 6; 10) and species, particularly in a region called BBloop which is responsible for downstream signal transduction.Molecular dynamics data shows that DMPO binds almostexclusively to these residues located at the BB-loop. Takingtogether, our data indicate that DMPO anti-inflammatory effect, isat least in part due to its binding to specific residues in thecytoplasmic portion of TLRs, thus further signaling is damped.Supported by PROICO 2-3214 & PICT-2014-3369 (to DCR),PROICO 10-0414 (To SEGM) and PIP2015-2017-112215-0100603CO (To DCR, SEA & SEGM).doi: 10.1016/j.freeradbiomed.2016.10.139