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How Leptin Exacerbates Asthma in Obese Persons
As if people who are obese didn't have enough to worry about already, this study finds that the appetite-regulating hormone, Leptin, also increases the risk of asthma.
Study findings provide further evidence linking the appetite-regulating hormone leptin to obesity and asthma, indicating that it may exacerbate asthma in obese individuals.
"Both asthma and obesity are prevalent and growing problems, and epidemiologic data indicate an increased incidence of asthma in overweight or obese adults and children," observe Stephanie Shore (Harvard School of Public Health, Boston, Massachusetts, USA) and colleagues.
Furthermore, they postulate: "It is likely that the relationship between obesity and asthma is causal. Longitudinal studies indicate that obesity antedates asthma and that the relative risk of incident asthma increases with increasing obesity."
Noting also that the serum levels of "the satiety hormone and proinflammatory cytokine leptin" are increased in obese individuals, the researchers sought to determine whether allergic airway responses are augmented by leptin.
For the study, they implanted micro-osmotic pumps that delivered a continuous infusion of either saline or leptin into mice sensitized to ovalbumin. After 2 days the animals were challenged with ovalbumin once daily for 3 days.
Publishing their findings in the Journal of Allergy and Clinical Immunology, the researchers report that leptin infusion increased serum leptin concentrations, and these were increased further by ovalbumin sensitization and challenge.
Furthermore, ovalbumin challenge resulted in increased bronchoalveolar lavage fluid cells and cytokines, serum immunoglobulin E, lung cytokine messenger RNA expression, and responses to inhaled methacholine in leptin-infused compared with saline-infused mice.
"In summary, our data indicate that? ovalbumin sensitization and challenge increases serum leptin and that even relatively modest increases in serum leptin can increase some aspects of the allergic airway response," write the researchers.
They conclude: "The results suggest that leptin, which is markedly increased in severe obesity, has the potential to exacerbate asthma in these individuals."
J Allergy Clin Immunol 2005; 115: 103-109
Last updated 18 January 2005
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