LEP and pulmonary emphysema: We found that nicotine upregulated leptin 70x, but subsequent addition of elastase did not further elevate the expression of leptin. On the other hand, the level of leptin in the controls instilled with elastase was 700 × higher when compared to saline samples, suggesting that nicotine pretreatment predisposes the offspring to a different leptin-mediated response in the emphysema model.