8-Nitroguanosine formation in viral pneumonia and its implication for pathogenesis

Abstract

For many diseases, mediation of pathogenesis by nitric oxide (NO) has been suggested. In this study, we explored NO-induced viral pathogenesis with a focus on nucleic acid damage as evidenced by 8-nitroguanosine formation in vivo. Wild-type mice and littermate mice deficient in inducible NO synthase (iNOS) were infected with influenza or Sendai virus. Formation of 8-nitroguanosine in virusinfected lungs was assessed immunohistochemically with an antibody specific for 8-nitroguanosine. Extensive nitration of RNA either treated with peroxynitrite or obtained from cultured RAW 264 cells expressing iNOS was readily detected by this antibody. Strong 8-nitroguanosine immunostaining was evident primarily in the cytosol of bronchial and bronchiolar epithelial cells of virus-infected wild-type mice but not iNOS-deficient mice. This staining colocalized with iNOS immunostaining in the lung. 8-Nitroguanosine staining disappeared after addition of exogenous authentic 8-nitroguanosine during the antibody reaction and after pretreatment of tissues with sodium hydrosulfite, which reduces 8-nitroguanosine to 8-aminoguanosine. NO was generated in excess in lungs of wild-type mice but was eliminated in iNOSdeficient mice after virus infection; this result also correlated well with formation of 8-nitroguanosine and 3-nitrotyrosine. One consequence of the lack of iNOS expression was marked improvement in histopathological changes in the lung and the lethality of the infection without effects on cytokine responses and viral clearance. It is intriguing that 8-nitroguanosine markedly stimulated superoxide generation from cytochrome P450 reductase and iNOS in vitro. The present data constitute a demonstration of 8-nitroguanosine formation in vivo and suggest a potential role for NO-induced nitrative stress in viral pathogenesis.

Chronic inflammation and oxidative stress in human carcinogenesis

“…41,42 NO reacts with superoxide (O 2 2 ) to form peroxynitrite (ONOO 2 ), a highly reactive species that induce nitrative and oxidative DNA damage. In fact, ONOO 2 mediates the formation of 8-oxo-7,8-dihydro-2 0 -deoxyguanosine 43 and 8-nitroguanine, 44,45 which has also been suggested as a potential biomarker of inflammation-related carcinogenesis. 42,46 Recent evidences indicate that 8-nitroguanosine is a highly redox-active molecule 47,48 and that 8-nitroguanine is a mutagenic substance, which preferentially leads to G>T transversions.…”

Nitrostative stress status during seasonal and pdmH1N1 infection in Iraq

“…This observation indicates that influenza A virus infection is associated with nitrosative stress. Further evidence of involvement of nitrosative stress in influenza A is the demonstration of strong 8-nitroguanosine immunostaining in the cytosol of bronchial and bronchiolar epithelial cells of influenza virus-infected wild-type mice but not iNOS-deficient mice [15]. Moreover, a number of studies have demonstrated that reactive oxygen species contribute to the exacerbation of lung inflammation and lethality in influenza-infected mice, while the use of glutathione precursor promotes survival in influenza-infected mice [16,17].…”

Practical strategies for targeting NF-kappaB and NADPH oxidase may improve survival during lethal influenza epidemics

“…In transgenic mice overexpressing extracellar superoxide dismutase, influenza infection evokes far less lung pathology than in wildtype mice. 7 Induction of the inducible isoform of nitric oxide synthase also contributes notably to lung damage during influenza infection in mice, as such infection was less lethal and produced less lung pathology in mice genetically deficient in iNOS; 31 in wild type mice, administration of the iNOS inhibitor L-NMMA reduced the lethality of influenza. 32 This likely points to a role for peroxynitrite in influenza-associated lung pathology -implying that a reduction in superoxide production could provide protection by decreasing peroxynitrite formation.…”