Pulmonary and hepatic adverse effects associated with repeated intratracheal instillation of heated tobacco product emission-derived extract

Heated tobacco products (HTP) have emerged as reduced-risk alternatives for adult smokers seeking to continue smoking. Even though there’s still a lack of evidence regarding safety, HTP have rapidly garnered considerable attention. Thus, there is a need for research on the effects of HTP on human health. This study explored the harmful effects of intratracheal instillation (ITI) of HTP-EE in Sprague–Dawley rats. HTP emission-derived extract (HTP-EE; 0, 10, 20, or 30 mg/mL) was administered via ITI once daily for 1 or 2 weeks. Repeated administration of HTP-EE induced weight loss and altered levels of neutrophils and inflammatory cytokines (Interleukin (IL)-1 beta, IL-4, IL-6, Chemokine (C-C motif) ligand (CCL) 2, CCL3, CCL20, tumor necrosis factor-alpha, and interferon-gamma) in bronchoalveolar lavage fluid. Blood biochemical analysis revealed that exposure to HTP-EE led to alterations in indicators (blood urea nitrogen, creatinine, total bilirubin, triglycerides, and creatine kinase). Histopathological examination indicated the infiltration of inflammatory cells in both lung and liver tissues of the 1- and 2-week HTP-EE-exposed groups. These findings suggest that HTP-EE may induce inflammatory responses, particularly in the lungs and liver.