Potential Use of VYN202, a Novel Small Molecular Bromodomain and Extra-Terminal Inhibitor, in Mitigating Secondhand Smoke (SHS)-Induced Pulmonary Inflammation.

Inflammation underpins pulmonary disease progression during tobacco smoke exposure, which may culminate in irreversible pulmonary disease. While primary smoke poses a notable risk, nearly half of the US population is also susceptible due to frequent exposure to secondhand smoke (SHS). In the present study, we assessed the potential role of VYN202, a novel small molecular bromodomain and extra-terminal inhibitor, as a possible means of attenuating SHS-mediated inflammation. We exposed wild-type mice to an acute time course of room air (RA), SHS via a nose-only delivery system (Scireq Scientific, Montreal, Canada), or to both SHS and 10 mg/kg VYN202 (efficacious dose from prior inflammatory models) via oral gavage three times a week. Specific smoke exposure delivery to mice involved SHS from two cigarettes over 10 min, equilibration in room air for 10 min, followed by exposure to SHS from one cigarette for an additional 10 min, for a total SHS exposure of 20 min per day, five days a week for 30 days. We evaluated leukocyte abundance and the secretion of inflammatory mediators in bronchoalveolar lavage fluid (BALF). We also assessed general morphology via histology staining and the activation of receptor tyrosine kinase (RTK) family members. While standard hematoxylin and eosin (H&E) staining resulted in unchanged morphology, SHS-mediated increases in BALF protein abundance, total cellularity, and percent PMNs were attenuated with concomitant administration of VYN202. We also discovered SHS-induced activation of RTKs that were pro-inflammatory (JAK1, JAK3, ABL1, and ACK1), as well as RTKs related to endothelial and vascular remodeling (VEGFR3, VEGFR2, EphB4, EphB6, and FAK). Furthermore, inflammatory cytokines including GCSF, IFN-γ, IL-12p70, IL-17A, LIX, and TNF-α were all augmented by SHS exposure. Despite SHS exposure, each of these RTKs and cytokines/chemokines was significantly attenuated by VYN202. In summary, inflammatory responses induced by SHS exposure were mitigated by VYN202. These data reveal fascinating potential for the utility of VYN202 in lessening smoke-induced pulmonary exacerbations.