SHORT-TERM ANTI-INFLAMMATORY EFFECTS OF 5,5-DIMETHYL-1-PYRROLINE N-OXIDE (DMPO)

MUNOZ, MD; LUCAS J. GUTIERREZ,; DANIEL RICARDO ENRIZ; ALVAREZ, S.; GOMEZ-MEJIBA S.E; RAMIREZ, DC

Congreso; SAIC; 2016

">5,5-dimethyl-1-pirroline N-oxide (DMPO) is a nitrone spintrap originally synthesized as a nitrone spin trap to study freeradicals by electron spin resonance spectroscopy and recently byimmuno-spin trapping. Herein we envisioned at studying what arethe mechanisms involved in these anti-inflammatory effects of thisold drug with new properties. To accomplish this goal we used awell known model of macrophage-like cells (RAW264.6) primedwith LPS; 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 MAPKsignaling; but it did not affect LPS binding to LPS to membranereceptors. Thus we hypothesized that DMPO, and likewise othernitrones, 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 región calledBB-loop which is responsible for downstream signal transduction.Molecular dynamics data shows that DMPO binds almost exclusively to these residues located at the BB-loop. Taking together,our data indicate that DMPO anti-inflammatory effect, is at leastin part due to its binding to specific residues in the cytoplasmicportion of TLRs, thus further signaling is damped. Supported byPROICO 2-3214 & PICT-2014-3369 (to DCR), PROICO 10-0414(To SEGM) and PIP2015-2017-112215-0100603CO (To DCR,SEA & SEGM).