The nitrone 5,5-dimethyl-1-pyrroline N-oxide is an antagonist of lipopolysaccharide triggered TLR-signaling

ENRIZ RD,; DI SCIULLO MP,; MUÑOZ, M.D.; AIRTON ROMAN AGUILAR; GOMEZ MEJIBA, SANDRA;; GUTIERREZ LJ,; FLORENCIA NAHIR CLAVELES CASAS,; DARIO C RAMIREZ

LAS Vegas Nevada

Congreso; S. of Free Radical Biology and Medicine; 2019

SFRBM

Inflammatory activation of macrophages plays an important role in tissue damage during chronic inflammatory processes. Toll-like receptor (TLR)-mediated inflammatory activation of macrophages is a well known model of macrophage activation at chronic inflammation microenvironments. Previously we have shown that the nitrone spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) traps protein radicals and dampens endotoxin-induced and TLR4-driven priming of macrophages, but the mechanism remains unknown. The available information suggests a direct binding of DMPO to the TIR domain, which is shared between TLRs. However, TLR2-TIR domain is the only TLR that has been crystallized. Our in silico data show that DMPO tightly binds to four specific residues within the BB-loop at the TLR2-TIR domain. Our functional analysis using hTLR2.6-expressing HEKs cells showed that DMPO can block zymosan-triggered-TLR2-mediated NF-kb activation. However, DMPO did not affect the overall TLR2-MyD88 protein-protein interaction. DMPO binds to the BB-loop in the TIR-domain and dampens downstream signaling without affecting the overall TIR-MyD88 interaction. These data encourage the development and use of DMPO-derivatives as potential mechanism-based safe antagonists of TLR-triggered inflammation.