Superoxide mediates cigarette smoke-induced infiltration of neutrophils into the airways through nuclear factor-kappaB activation and IL-8 mRNA expression in guinea pigs in vivo

We examined the hypothesis that superoxide mediates infiltration of neutrophils to the airways through nuclear factor (NF)-kappaB and interleukin-8 (IL-8) after acute exposure to cigarette smoke (CS) in vivo. Male Hartley strain guinea pigs were exposed to air or 20 puffs of CS and killed 5 h after the exposure. The differential cell count of bronchoalveolar lavage fluid and specific myeloperoxidase enzyme assay demonstrated that acute exposure to CS caused neutrophil accumulation to the airways and parenchyma, respectively. Acute exposure to CS increased DNA-binding activity of NF-kappaB in the lung. Acute exposure to CS also increased IL-8 messenger RNA (mRNA) expression in the lung. Pretreatment of guinea pigs with recombinant human superoxide dismutase (rhSOD) aerosols reduced the CS-induced neutrophil accumulation to the airways. Both activation of NF-kappaB and increased IL-8 mRNA expression were also inhibited by the pretreatment of rhSOD aerosols. Strong immunoreactivities for p65 and p50 were detected in the nuclei of alveolar macrophages after acute exposure to CS. The signal for IL-8 mRNA expression was demonstrated in the alveolar space after acute exposure to CS. Neither significant immunoreactivities for p65 and p50 nor IL-8 mRNA signals were observed in airway epithelium. These observations suggest that acute exposure to CS initiates superoxide-dependent mechanism that, through NF-kappaB activation and IL-8 mRNA expression, produces infiltration of neutrophils to the airways in vivo. It was also suggested that the alveolar macrophage is one potential source of NF-kappaB activation and IL-8 mRNA expression after acute exposure to CS.     

Perflubron decreases inflammatory cytokine production by human alveolar macrophages

OBJECTIVE: To determine whether inflammatory cytokine production by stimulated human alveolar macrophages is affected by perflubron exposure. DESIGN: Controlled laboratory investigation of alveolar macrophage function in vitro. SETTING: Research laboratory. SUBJECTS: Cultured alveolar macrophages obtained by bronchoalveolar lavage from eleven normal volunteers. INTERVENTIONS: Endotoxin-stimulated alveolar macrophages were treated with perflubron. MEASUREMENTS AND MAIN RESULTS: Alveolar macrophages were stimulated for 1 hr with lipopolysaccharide and then treated with perflubron for 23 hrs. Cell-free supernatants were collected and cytokines were assayed by enzyme-linked immunosorbent assay. Tumor necrosis factor-alpha, interleukin-1, and interleukin-6 were stimulated by lipopolysaccharide (endotoxin) and all of these cytokines were significantly (p < .05) inhibited by perflubron. Cell viability was not affected by perflubron. Basal cytokine concentrations from unstimulated alveolar macrophages were not altered by perflubron. CONCLUSIONS: Exposure of stimulated human alveolar macrophages to perflubron in vitro decreases cytokine production. This observation suggests that perflubron may have anti-inflammatory activity.