Date of Award
MS in Pharmaceutical Science
To determine whether cigarette smoke exposure predisposes lungs to secondary injury, our laboratory developed a hamster model using lipopolysaccharide (LPS) to induce pulmonary inflammation following exposure to second-hand smoke. With this model, inflammatory effects of LPS on smoke-exposed hamsters was measured by various morphological and biochemical parameters. Additional experiments studied the effects of exogenous ET-1 and BQ123, which modulate the adherence of inflammatory cells to lung capillary endothelium. Total bronchoalveolar lavage fluid (BALF) leukocytes, percent BALF neutrophils, and elastin-specific desmosine and isodesmosine (DID) crosslinks (free and peptide-bound) in BALF and whole lungs were measured 24 hours (hrs) after LPS treatment. Morphometric changes were evaluated with the mean linear intercept (MLI) method which measures airspace enlargement, and a disease index was used to quantify the thickness of interstitial walls and the intensity of inflammatory infiltrates 24 hrs post-LPS treatment. Animals treated with smoke and LPS showed a significant increase in BALF neutrophils (15.0% vs 5.1%, respectively) and free lung DID (359 vs 93.1 ng/mg wet lung) compared to the room-air/LPS group. There was also a significant increase in the disease index in the smoke/LPS group compared to room air/LPS controls (1.6 vs 0.9 respectively). As a measure of irreversible lung injury, MLI was significantly elevated in the smoke/LPS group compared to room air/LPS controls (83.6 vs 55.7 um, respectively). Conversely, animals treated with BQ123 before smoke/LPS administration showed a significant decrease in BALF neutrophils compared to smoke/LPS alone (8.5% vs 15.8% respectively). While BALF neutrophils were significantly increased in room air-exposed animals given ET-1 compared to room air alone (13.9% vs 5.2%, respectively), the addition of ET-1 to animals given smoke and/or LPS had anti-inflammatory effects, suggesting ET-1 counteracts the proinflammatory activity of these other agents. The results of these studies demonstrate that the combination of cigarette smoke and secondary inflammation induced by LPS causes severe acute lung injury that degrades lung elastic fibers and enlarges airspaces. Treatment with BQ123 reduced this inflammatory process, suggesting it may have a therapeutic role in reducing the risk of lung damage in smokers with pneumonia or other types of secondary injury.
Gu, George, "Short-Term Second-Hand Smoke Exposure Predisposes the Lung to Inflammation, Elastic Fiber Injury, and Pulmonary Emphysema" (2021). Theses and Dissertations. 297.