Biological changes in C57BL/6 mice following 3 weeks of inhalation exposure to cigarette smoke or e-vapor aerosols

Introduction:
This article presents the results of a subacute (3 weeks) mouse inhalation study comparing the biological changes induced by exposure to MarkTenVR e-vapor products and 3R4F cigarettes. The study aimed to consistently generate and expose e-vapor aerosols to mice via a nose-only inhalation exposure system and evaluate the resulting biological changes.

Key Points:

* Four exposure systems were used, including a rotary smoking machine and a nose-only exposure chamber for each group (Sham Control, Carrier, Test-1, Test-2, and 3R4F).
* Mice were exposed up to 4 hours/day, 5 days/week for 3 weeks, with daily exposure duration progressively increased during the first exposure week.
* Exposure concentrations were checked daily for TPM, CO, temperature, humidity, and particle size.
* PG, VG, nicotine, carbonyls, and other analytes were measured in cigarette smoke or e-vapor aerosols.
* Mice were checked daily for mortality, morbidity, and clinical signs. Body weight, food consumption, respiratory physiology, BaLF cytology, and plasma biomarkers were also measured.
* The 3R4F group showed significant increases in lung weight, BaLF cytology, and gene/protein expression changes in the lung compared to e-vapor groups.
* E-vapor groups had minimal microscopic changes, while the 3R4F group displayed microscopic lesions in the respiratory tract.

Main Message:
The study demonstrates that 3 weeks of exposure to MarkTenVR e-vapor products result in substantially reduced physiological, molecular, and microscopic changes compared to 3R4F cigarettes. The e-vapor aerosols showed significantly lower biological activities, while the 3R4F cigarette smoke induced biological responses associated with smoking-related adverse effects in the respiratory tract.

Lee, K. Monica, Julia hoeng, Sam harbo, Ulrike Kogel, William Gardner, Michael Oldham, Eric Benson, et al. “Biological Changes in C57BL/6 Mice Following 3 Weeks of Inhalation Exposure to Cigarette Smoke or e-Vapor aerosols.” Inhalation Toxicology 30, no. 13–14 (December 6, 2018): 553–67. https://doi.org/10.1080/08958378.2019.1576807.