Author ORCID Identifier
Semester
Summer
Date of Graduation
2026
Document Type
Dissertation (Campus Access)
Degree Type
PhD
College
Statler College of Engineering and Mineral Resources
Department
Chemical and Biomedical Engineering
Committee Chair
Margaret Bennewitz
Committee Member
Duaa Dakhlallah
Committee Member
Cerasela Zoica Dinu
Committee Member
Moriah Katt
Committee Member
Timothy Nurkiewicz
Abstract
E-cigarettes are frequently perceived as safer than traditional cigarettes. However, there is a growing body of evidence that this perception is flawed, as e-cigarette (EC) exposure leads to altered immune function and injury to the pulmonary system. Recent studies have shown that the plasma of e-cigarette users had elevated biomarkers such as platelet-derived growth factor (PDGF-BB) and tumor necrosis factor alpha compared to non-smokers. Currently, the cellular and molecular mechanism of EC-mediated lung vascular damage is poorly defined. Here, the behavior of immune cells in the lung microvasculature following nicotine-free EC exposure was investigated. The goal was to define the role of PDGF-BB in recruiting neutrophils and enhancing neutrophil-platelet aggregates. Neutrophils are the most abundant type of white blood cells, and when stimulated, release neutrophil extracellular traps (NETs). These webs of sticky extruded DNA fibers are decondensed nuclear chromatin with antimicrobial proteins such as myeloperoxidase (MPO) and neutrophil elastase (NE) that if unregulated, provoke an inflammatory response and vascular damage. We hypothesize that PDGF, released from activated platelets during the initial steps of hemostasis following a vascular injury, binds to PDGF-BB receptors (PDGFRβ) on the surface of pericytes and endothelial cells and initiate phosphorylation, reactive oxygen species generation (ROS) through the NADPH oxidase 2 (NOX2) pathway, neutrophil-platelet aggregation and subsequent NET release.
Male and female BALB/c mice underwent 150 puffs/day of EC exposure for 3, 6, or 9 days to test the impact of sex and EC exposure duration on the lung inflammatory response. Control mice received room air. Other groups of mice received either PDGF-BB or imatinib mesylate to stimulate or inhibit PDGFRβ binding, respectively. Intravital imaging revealed a significant increase of neutrophils and neutrophil-platelet aggregates in the pulmonary microvasculature of mice receiving EC exposure, with sex-mediated differences. Male mice generated a severe aggregation response after 6 days of EC exposure, while it took females 9 days of EC exposure to mount the same inflammatory response. PDGF-BB alone recapitulated the inflammatory responses seen in EC mice, while imatinib mesylate prevented neutrophil-platelet aggregate formation, supporting the role of PDGF-BB in EC-mediated blood cell aggregation. The cytokine expression of collected plasma showcased dysregulation of 8 pro-inflammatory cytokines in EC mice which direct further recruitment of neutrophils, macrophages, eosinophils, and lymphocytes. Mass spectrometry of digested lungs revealed a host of upregulated and downregulated proteins post EC exposure. Most notable was the EC-mediated downregulation of surfactant protein A1, suggesting an impairment to surfactant production that will make breathing more difficult. Additional studies were performed on isolated proteins and purified DNA/RNA from EC exposed mouse lungs to further investigate the role of PDGF-BB in mediating neutrophil-induced NETosis and tissue damage. Finally, the role of flavored EC in driving inflammation was evaluated, as flavorings contain undisclosed chemicals that upon heating, can create harmful substances including toxins, carcinogens and diacetyl. Using a commercial BioFlux microfluidics system, the behavior of neutrophils and platelets were examined in the blood and bronchoalveolar lavage fluid collected from mice exposed to different flavors of EC. These results suggest that PDGF-BB may contribute to lung inflammation following an EC exposure. The finding of this dissertation further highlights the immune damage caused by ECs, which can better educate the public and youths about its dangers.
Recommended Citation
Alkhadrawi, Hassan, "E-cigarette-induced neutrophil–platelet aggregates in the lung microvasculature: roles of platelet-derived growth factor, sex differences, and flavoring" (2026). Graduate Theses, Dissertations, and Problem Reports (ETD). 13409.
https://researchrepository.wvu.edu/etd/13409