DMPO traps DNA-centered radicals preventing hrpt gene mutagenesis: a model of genotoxicity induced at sites of neutrophilic inflammation

LOPEZ CM; DI SCIULLO MP,; CLAVELES, F.N; RAMÍREZ, DC.; BARRERAS, FS; GOMEZ MEJIBA, SANDRA;

LAS Vegas Nevada

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

SFRBM

Pulmonary neutrophilic inflammation is an acute response to airway irritation, and includes recruitment and activation of neutrophils with production of HOCl-a highly reactive species. HOCl produced by myeloperoxidase (MPO) generates radical events in the genomic DNA. Co-incubation of lung epithelial cells with activated human neutrophils results in accumulation of MPO inside the epithelial cells?a system that resembles neutrophilic inflammation in the irritated airways. Herein we sought to test whether DNA radicalization produced by intracellularly produced HOCl can cause hypoxanthine-guanine phosporibosyltransferase (hrpt)-gene mutation in A549 airway epithelial cells and how the nitrone spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) can modulate this process. Exposure of A549 cells loaded with active MPO and exposed to a flow or bolus addition of H2O2, produced HOCl inside them. Intracellularly produced HOCl caused DNA radicalization, 8-oxo-7,8-dihydro-2´ ?deoxyguanosine (8-oxo-dGuo), p53 translocation within the nucleus and hrtp gene mutation. DNA radicalization precedes 8-oxo-dGuo formation and hrpt gene mutation. The DMPO trapped DNA-centered radicals, reduced 8-oxo-dGuo accumulation, and blocked hrpt gene mutation. The mechanism and potential use of DMPO, or its structural derivatives, to reduce accumulation of mutations at sites of neutrophilic inflammation is discussed.