Am. J. Respir. Crit. Care Med., Vol 151, No. 3, 03 1995, 809-814.
Allergen-induced airway inflammation in rats. Role of insulin
EO Vianna and J Garcia-Leme
Department of Pulmonology, School of Medicine, University of Sao Paulo, Brazil.
Clinical asthma appears to be less severe when diabetes mellitus is
superimposed. To examine whether insulin influences the development of
allergic reactions in the airway mucosa antigen challenge, normal and
diabetic rats sensitized against ovalbumin (OA) were used. Compared with
controls, animals rendered diabetic by the injection of alloxan presented
markedly decreased cell yields from bronchoalveolar lavage after OA
challenge. The impaired response was not related to antibody production
because enhanced IgE antibody titers of the same magnitude were found in
both control and diabetic animals. Similarly, the mechanism underlying the
inhibited responses could not be ascribed to hyperglycemia or intracellular
glucopenia, first, because correction of blood glucose levels through
fasting did not restore the decreased response, and second, because
administration of 2-deoxyglucose, which blocks glucose utilization, did not
affect the bronchoalveolar reaction to OA challenge in normal animals.
Reversal of the impaired responses was attained by treatment of diabetic
animals with insulin. There is evidence that insulin exerts proinflammatory
effects. We conclude that insulin might modulate the inflammatory component
of asthmatic responses.
