The nitrone 5,5-dimethyl-1-pyrroline-N-oxide prevents Pseudomonas aeruginosa-induced pulmonary neutrophilic inflammation and DNA-radical formation

CRISTOFER MARTÍN LOPEZ ; MARIA AIDA MATTAR DOMINGUEZ ; DARIO C. RAMIREZ 3 , ; SANDRA GOMEZ-MEJIBA

Congreso; SOCIETY OF FREE RADICAL BIOLOGY AND MEDICINE; 2024

Lipopolysaccharide (LPS), is a component of the outer membrane of Gram-negative bacteria, suchas Pseudomonas aeruginosa (Pa) that causes redox changes and inflammatory NF-kB-controledgene expression. In the pulmonary microvasculature, the latest controls the expression of adhesionmolecules which can slow down neutrophil migration and further activation (a process known aspulmonary neutrophilic inflammation, PNI). During PNI, myeloperoxidase (MPO) is released andcan be taken up by surrounding airway epithelial cells, where it can oxidize chloride anions toHOCl. HOCl is a powerful oxidant that can damage the genomic DNA by free radical-operatedmechanisms. Herein we aimed to test in vivo whether the nitrone 5,5,dimethyl-1-pyrroline N-oxide(DMPO) can prevent DNA-centered radical formation in C57 male mice exposed to dead Pa. After24 h of oropharyngeal exposure (o.e.) to Pa (5x107 cells), we found a marked PNI, as assessed by alarge infiltration of neutrophils, MPO (content and activity), and chlorotyrosine-modified proteins inthe BALF and lung parenchyma. We also found increased expression of ICAM-1, inducible nitricoxide synthase, and content of nitrotyrosine-modified proteins in the lung parenchyma, as well asincreased pro-inflammatory cytokines in serum. These changes were blocked when DMPO (2.5mmol/mice) was administrated 1h before the exposure to Pa. DMPO also trapped protein and DNAradicals in the lung parenchyma forming protein- and DNA-nitrone adducts (immuno-spin trappingtechnique). These data indicate that DMPO reduces Pa-induced genotoxicity and proteotoxic stress.Taken together, these data, in agreement with our recent publications, are consistent with an effect ofDMPO interfering with the LPS-triggered signaling causing inhibition of the expression of genesunder the transcriptional control of NF-kB, thus blocking PNI. The nitrone spin trap can serve as anovel structural platform for the design of novel drugs to reduce death associated with sepsis andgenotoxic damage to the airways.