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A7425 - Modeling Acute Exacerbation of Chronic Obstructive Pulmonary Disease by Combining Cigarette Smoke Inhalation and H1N1 Infection in Mice
Author Block: M. Ferrero1, J. Torres1, T. P. Teixeira Ferreira1, A. Arantes1, D. d. Coutinho1, C. Couto Garcia2, M. A. Martins1; 1Inflammation, Oswaldo Cruz Foundation - Fiocruz, Rio de Janeiro, Brazil, 2Respiratory Virus and Measles, Oswaldo Cruz Foundation - Fiocruz, Rio de Janeiro, Brazil.
RATIONALE. Chronic obstructive pulmonary disease (COPD) highly reduces the life quality of people and can be fatal. Infections strongly exacerbate symptoms and severity of COPD (AECOPD), and massive neutrophil infiltration into the lung tissue is a pivotal underlying component. As animal models reproducing AECOPD will be helpful in the identification of associated mechanisms and novel therapies, we studied here whether H1N1 virus would exacerbate cigarette smoke (CS)-induced lung inflammation in C57Bl/6 mice. METHODS. We exposed female mice to ambient air or CS for 12 days and at day 7 we infected them with 100 or 1000 pfu of H1N1 A/PR/8/34 strain intranasally. Groups (n=7): ambient air (AA), AA+100 pfu (AA100), AA+1000 pfu (AA1000), cigarette-smoke (CS), CS+100 pfu (CS100) and CS+1000 pfu (CS1000). Mice weight loss, lung mechanics, as well as inflammatory and oxidative/anti-oxidative changes in lung tissue were assessed 24 h after the last exposure to CS. In another experimental setting, the effect of dexamethasone (1 mg/Kg) or Roflumilast (3,75 mg/kg) treatments, starting 24 h after infection, for four consecutive days, in AA1000 and CS1000 groups were also assessed. RESULTS. We found that levels of neutrophil accumulation in BAL fluid, as well as lung MPO, TNF-α, IL-6, KC, MIP-1-α and MCP-1 appeared significantly exacerbated in CS1000 but not in CS100 group when compared to AA100 and AA1000. Lung histological sections also showed cellular infiltrate exacerbation in CS1000 mice, which was not restricted to airway surroundings as it was in AA1000 group. Viral infection alone decreased catalase activity while augmented lipid peroxidation in a load dependent way. CS exposure exacerbated lipid peroxidation in the CS100 group only, but had no effect on catalase activity. Survival experiment showed that CS exposure exacerbated H1N1-induced lethality (37.5% in AA1000 versus 75% in CS1000). Dexamethasone treatment in CS1000 failed to prevent neutrophil exacerbated levels in BAL, MPO levels in lung tissue and increased mortality rate, but reduced mononuclear cell infiltration. Roflumilast also failed to interfere with pathological changes in CS1000 group. CONCLUSION. Our results show that combination of CS and H1N1 infection led to synergistic exacerbation of pivotal lung inflammatory changes in C57Bl/6 mice including increased neutrophilic activity, which was clearly non-responsive to glucocorticoid or roflumilast treatment. This short-term AECOPD model may be suitable for investigation of mechanisms and putative therapies relevant in COPD exacerbations. Financial support: INCT-INOFAR, CNPq and FAPERJ. CEUA – L030/15, L048/16.