Effects of in utero and Postnatal Exposure to Secondhand Smoke on Lung Function by Gender and Asthma Status: The Seven Northeastern Cities (SNEC) Study.

BACKGROUND: Little information exists on whether gender or asthma status modifies the effects of secondhand smoke (SHS) exposure on lung function. OBJECTIVE: To evaluate whether gender or asthma status modifies the association of SHS exposure with lung function. METHODS: A total of 6,740 children (average 11.6 years) were recruited from 24 districts of 7 cities in northeast China in 2012. SHS exposure included exposure to environmental and maternal smoking both in utero and during early childhood (postnatal). Lung function was measured using electronic spirometers. Two-step regressions were used to analyze the association between SHS and lung function. RESULTS: In utero and postnatal exposure to SHS was independently associated with decreased lung function in both genders; however, this association was greater among males. For example, when exposed to maternal smoking during pregnancy, the adjusted odds ratio (aOR) for decreased forced vital capacity (FVC) was 6.46 (95% confidence interval [CI]: 2.58-16.17) among males, while only 2.16 (95% CI: 0.96-4.88) among females. More positive associations between SHS exposure and decreased lung function were detected among nonasthmatic compared with asthmatic children. Nonasthmatics had significantly larger deficits from in utero exposure to maternal smoking, which concerned decreased lung FVC function (aOR = 2.58, 95% CI: 1.28-5.21) and decreased lung forced expiratory volume in 1 s (FEV1) function (aOR = 2.32, 95% CI: 1.01-5.33). A similar pattern was also observed for the associations between SHS exposure and continuous pulmonary function test measurements. CONCLUSIONS: SHS exposure was associated with decreased lung function. Males and nonasthmatics seem to be more susceptible than their respective counterparts.

Role of double-stranded RNA pattern recognition receptors in rhinovirus-induced airway epithelial cell responses.

Rhinovirus (RV), a ssRNA virus of the picornavirus family, is a major cause of the common cold as well as asthma and chronic obstructive pulmonary disease exacerbations. Viral dsRNA produced during replication may be recognized by the host pattern recognition receptors TLR-3, retinoic acid-inducible gene (RIG)-I, and melanoma differentiation-associated gene (MDA)-5. No study has yet identified the receptor required for sensing RV dsRNA. To examine this, BEAS-2B human bronchial epithelial cells were infected with intact RV-1B or replication-deficient UV-irradiated virus, and IFN and IFN-stimulated gene expression was determined by quantitative PCR. The separate requirements of RIG-I, MDA5, and IFN response factor (IRF)-3 were determined using their respective small interfering RNAs (siRNA). The requirement of TLR3 was determined using siRNA against the TLR3 adaptor molecule Toll/IL-1R homologous region-domain-containing adapter-inducing IFN-beta (TRIF). Intact RV-1B, but not UV-irradiated RV, induced IRF3 phosphorylation and dimerization, as well as mRNA expression of IFN-beta, IFN-lambda1, IFN-lambda2/3, IRF7, RIG-I, MDA5, 10-kDa IFN-gamma-inducible protein/CXCL10, IL-8/CXCL8, and GM-CSF. siRNA against IRF3, MDA5, and TRIF, but not RIG-I, decreased RV-1B-induced expression of IFN-beta, IFN-lambda1, IFN-lambda2/3, IRF7, RIG-I, MDA5, and inflammatory protein-10/CXCL10 but had no effect on IL-8/CXCL8 and GM-CSF. siRNAs against MDA5 and TRIF also reduced IRF3 dimerization. Finally, in primary cells, transfection with MDA5 siRNA significantly reduced IFN expression, as it did in BEAS-2B cells. These results suggest that TLR3 and MDA5, but not RIG-I, are required for maximal sensing of RV dsRNA and that TLR3 and MDA5 signal through a common downstream signaling intermediate, IRF3.