As
pulmonary emphysema and
diabetes mellitus are common diseases, concomitance of both is correspondingly expected to occur frequently. To examine whether
insulin influences the development of
inflammation in the alveolar septa, diabetic male Wistar rats (
alloxan, 42 mg/kg, i.v., n = 37) and matching controls (n = 31) were used. Ten days after
alloxan injection, diabetic and control rats were instilled with physiologic
saline solution containing porcine
pancreatic elastase (PPE, 0.25 IU/0.2 ml, right lung) or saline only (left lung). The following analyses were performed: (i) number of leucocytes in the bronchoalveolar lavage (BAL) fluid of the animals, 6 h after PPE/saline instillation (early time point); and (ii) mean alveolar diameter (μm) and quantification of elastic and
collagen fibres (%) 50 days after PPE/saline instillation (late time point). Relative to controls,
alloxan-induced diabetic rats showed a 42% reduction in the number of neutrophils in BAL fluid, a 20% increase in the mean alveolar diameter and a 33% decrease in elastic fibre density in the alveolar septa. Treatment of diabetic rats with 4 IU neutral
protamine Hagedorn (
NPH) insulin, 2 h before
elastase instillation, restored the number of neutrophils in the BAL fluid. The mean alveolar diameter and elastic fibre content in alveolar septa matched the values observed in control rats if diabetic rats were treated with 4 IU
NPH insulin 2 h before instillation followed by 2 IU/day for the next 50 days. Density of
collagen fibres did not differ between the various groups. Thus, the data presented suggest that
insulin modulates the inflammatory and repair responses in
elastase-induced
emphysema, and assures normal repair and tissue remodelling.