Epidemiological data indicate an increased incidence of asthma in overweight adults and children. Ozone (O3) is a common trigger for asthma. Accordingly, the purpose of this study was to compare O3-induced airway hyperresponsiveness and airway inflammation in lean, wild-type (C57BL/6J) mice and mice that are obese as a consequence of a genetic defect in the gene encoding the satiety hormone leptin (ob/ob mice). The ob/ob mice eat excessively and weighed more than twice as much as age- and gender-matched wild-type mice. Airway responsiveness to intravenous methacholine was measured by forced oscillation. In air-exposed controls, baseline pulmonary resistance was greater, and the dose of methacholine required to double pulmonary resistance was lower in ob/ob than wild-type mice. Exposure to O3 (2 parts/million for 3 h) caused AHR and airway inflammation in both groups of mice, but responses to O3 were enhanced in ob/ob compared with wild-type mice. Administration of exogenous leptin did not reverse the enhanced inflammatory response observed in ob/ob mice, but augmented airway inflammation in wild-type mice. The inhaled dose of O3 per gram of lung tissue was greater in ob/ob than wild-type mice. Our results indicate that O3-induced airway responses are enhanced in ob/ob mice and suggest that inhaled O3 dose may be one factor contributing to this difference, but other aspects of the obese phenotype may also contribute. Our results also indicate that the hormone leptin, which is increased in the obese, has the capacity to increase airway inflammation.

These results demonstrate that obesity enhances OVA-induced changes in pulmonary resistance and serum IgE and that these changes are not the result of increased Th2 type airway inflammation.

Background Asthma severity is reflected in many aspects of the disease, including impairment and future risks, particularly for exacerbations. According to the EPR-3, however, to assess more comprehensively the severity of asthma the level of current treatment needed to maintain a level of control should be included. Objective Development and validation of a new instrument, the Composite Asthma Severity Index (CASI), which can quantify disease severity by taking into account impairment, risk and the amount of medication needed to maintain control. At present, there is no instrument available to measure and assess the multidimensional nature of asthma. Methods Twenty-six established asthma investigators, who are part of the NIH-supported Inner City Asthma Consortium (ICAC), participated in a modified Delphi consensus process to identify and weight the dimensions of asthma. Factor analysis was performed to identify independent domains of asthma using the Asthma Control Evaluation (ACE) trial. CASI was validated using the Inner City Anti-IgE Therapy for Asthma (ICATA) trial. Results CASI scores include five domains: day symptoms and albuterol use, night symptoms and albuterol use, controller treatment, lung function measures, and exacerbations. At ACE enrollment, CASI ranged from 0 to 17 with a mean of 6.2. CASI was stable, with minimal change in variance after 1 year of treatment. In external validation, CASI detected a 32% larger improvement than symptoms alone. Conclusion CASI retained its discriminatory ability even with low levels of symptoms reported after months of guidelines-directed care. Thus, CASI has the ability to determine the level of asthma severity, and provide a composite clinical characterization of asthma.

Obesity is an important risk factor for asthma. We recently reported increased ozone (O(3))-induced hyperresponsiveness to methacholine in obese mice (Shore SA, Rivera-Sanchez YM, Schwartzman IN, and Johnston RA. J Appl Physiol 95: 938-945, 2003). The purpose of this study was to determine whether this increased hyperresponsiveness is the result of changes in the airways, the lung tissue, or both. To that end, we examined the effect of O(3) (2 parts/million for 3 h) on methacholine-induced changes in lung mechanics with the use of a forced oscillation technique in wild-type C57BL/6J mice and mice obese because of a genetic deficiency in leptin (ob/ob mice). In ob/ob mice, O(3) increased baseline values for all parameters measured in the study: airway resistance (Raw), lung tissue resistance (Rtis), lung tissue damping (G) and elastance (H), and lung hysteresivity (eta). In contrast, no effect of O(3) on baseline mechanics was observed in wild-type mice. O(3) exposure significantly increased Raw, Rtis, lung resistance (Rl), G, H, and eta responses to methacholine in both groups of mice. For G, Rtis, and Rl there was a significant effect of obesity on the response to O(3). Our results demonstrate that both airways and lung tissue contribute to the hyperresponsiveness that occurs after O(3) exposure in wild-type mice. Our results also demonstrate that changes in the lung tissue rather than the airways account for the amplification of O(3)-induced hyperresponsiveness observed in obese mice.

In 2 samples of adolescents, overall serum 25(OH)D concentrations were low and were not consistently associated with the presence of asthma, multiple asthma characteristics, asthma morbidity, or response to treatment. The ACE trial was registered at clinicaltrials.gov as NCT0011441.