Influence of different therapeutic strategies on exhaled NO and lung inflammation in asthma and COPD

Nitric Oxide Metabolites and Lung Cancer Incidence: A Matched Case-Control Study Nested in the ESTHER Cohort

Studies suggest that nitric oxide (NO) may have a possible role in lung carcinogenesis. This study is aimed to evaluate the association of the NO metabolites, namely, nitrite and nitrate, with lung cancer incidence. We conducted a matched case-control study (n = 245 incident lung cancer cases and n = 735 controls) based on the German ESTHER cohort (n = 9,940). Controls were matched to cases on age, sex, smoking status (never/former/current smoking), and pack-years of smoking. The sum of nitrite and nitrate was measured in urine samples using a colorimetric assay and was standardized for renal function by urinary creatinine. Conditional logistic regression models, adjusted for lifestyle factors, asthma prevalence, and family history of lung cancer, were used to estimate odds ratios (ORs) and 95% confidence intervals (95% CI). Among incident lung cancer cases, high nitrite/nitrate levels were statistically significantly associated with current smoking, a low BMI, and the oxidative stress biomarker 8-isoprostane levels. Nitrite/nitrate levels in the top quintile were statistically significantly associated with lung cancer incidence: the OR (95% CI) was 1.37 (1.04-1.82) for comparison with the bottom quintile. This association was unaltered after additional adjustment for 8-isoprostane levels and C-reactive protein (CRP). In conclusion, this large cohort study suggested that subjects with high urinary nitrite/nitrate concentrations had an increased risk of lung cancer and this association was independent of smoking, CRP, 8-isoprostane levels, and other established lung cancer risk factors. Further studies are needed to validate these findings and to confirm the hypothesis that pathologically high levels of NO are involved in lung cancer development.

Repeated lipopolysaccharide exposure causes corticosteroid insensitive airway inflammation via activation of phosphoinositide-3-kinase δ pathway

Corticosteroid resistance is one of major barriers to effective management of chronic inflammatory respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and severe asthma. These patients often experience exacerbations with viral and/or bacterial infection, which may cause continuous corticosteroid insensitive inflammation. In this study, we observed that repeated exposure of lipopolysaccharide (LPS) intranasally attenuated the anti-inflammatory effects of the corticosteroid fluticasone propionate (FP) on neutrophils and CXCL1 levels in bronchoalveolar lavage (BAL) fluid in an in vivo murine model. Histone deacetylase-2 (HDAC2) and NF-E2 related factor 2 (Nrf2) levels in lungs after LPS administration for 3 consecutive days were significantly decreased to 38.9±6.3% (mean±SEM) and 77.5±2.7% of the levels seen after only one day of LPS exposure, respectively. In addition, 3 days LPS exposure resulted in an increase of Akt phosphorylation, indicating activation of the phosphoinositide-3-kinase (PI3K) pathway by 4-fold in lungs compared with 1 day of exposure. Furthermore, combination treatment with theophylline and FP significantly decreased the neutrophil accumulation and CXCL1 concentrations in BAL fluid from 22.5±1.8×10⁴ cells/mL and 214.6±20.6 pg/mL to 7.9±0.5×10⁴ cells/mL and 61.9±13.3 pg/mL, respectively. Combination treatment with IC87114, a selective PI3Kδ inhibitor, and FP also significantly decreased neutrophils and CXCL1 levels from 16.8±0.7×10⁴ cells/mL and 182.4±4.6 pg/mL to 5.9±0.3×10⁴ cells/mL and 71.4±2.7 pg/mL, respectively. Taken together, repeated exposure of LPS causes corticosteroid-insensitive airway inflammation in vivo, and the corticosteroid-resistance induced by LPS is at least partly mediated through the activation of PI3Kδ, resulting in decreased levels of HDAC2 and Nrf2. These findings provide a potentially new therapeutic approach to COPD and severe asthma.

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We first time proposed clinically relevant steroid insensitive exacerbation model.

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LPS caused corticosteroid insensitive airway inflammation via PI3Kδ activation.

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This murine model are useful to discover new therapies for airway inflammation.