Influence of obesity on allergic asthma development

Author(s)

Marina Ciarallo Calixto

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas
• Defense date: 2012-07-21

Examining board members

Edson Antunes; Eliana Pereira de Araujo; Alessandra Gambero; Iolanda de Fátima Lopes Calvo Tibério; Soraia Katia Pereira Costa

• Advisor: Edson Antunes

Abstract

Obesity and asthma are prevalent and increasing diseases, and both have significant impact on global public health. The increase in prevalence of asthma and obesity has led researchers to suggest that obesity may be an important factor in the development of asthma, or even worse the pre-existing asthma. Numerous populational studies conducted around the world indicate that the prevalence of asthma is higher in obese versus lean person. In addition, several prospective studies, both in adults and in children, indicate that the relative risk of incident asthma increases with body mass index (BMI). Obesity also worsens the drug therapy of asthma and the severity of this disease. Recently, several data emerged showing that the inflammation associated with obesity increase the propensity for development of asthma. It is believed that insulin resistance associated with obesity plays an important role in the development of asthma, explaining, at least in part, asthma associated with obesity. Recent reports indicate a high prevalence of insulin resistance in obese asthmatics versus obese non-asthmatics patients, suggesting that insulin resistance may contribute to this phenotype. Based on this information, the purpose of this study was to determine whether metabolic diseases associated with obesity such as insulin resistance, are involved in asthma exacerbation associated with obesity. In the present study we observed that obese mice treated with metformin, impairs the resistantance to the systemic action of insulin. Furthermore, in obese mice challend with OVA, metformin normalizes the transit of eosinophils from bone marrow to the lung lumen. This normalization is mediated by AMPK activation in the lung, as well as decreased concentrations of TNF-? and nitrite and nitrate in BAL fluid accompanied by the inhibition of NF-?B induced iNOS expression in the lung. Furthermore, by normalizing the eosinophils trafficking from peribronchiolar region to airway lumen, metformin treatment induces concomitant reduction in the accumulation of eosinophils in bone marrow through the upregulation of adhesion molecules VLA-4 and Mac-1 on cell surface and subsequent increase in the adhesive response to plates coated with ICAM-1 and VCAM-1. Our data seem to confirm the hypothesis that insulin resistance resulting from obesity mediates the exacerbation of airway inflammation in high fat-diet mice. Thus, by normalizing the systemic insulin resistance through the atictivation of AMPK, obese sensitized mice progress to resolution of allergic airway inflammation (AU)

• FAPESP's process: 09/02169-7 - Physiopathology of eosinophilic recruitment from bone marrow to the airway in allergic and obese mice: potential therapeutic of anti-asthmatic and anti-diabetogenic drugs.
• Grantee: Marina Ciarallo Calixto
• Support Opportunities: Scholarships in Brazil - Doctorate