Modulation of mouse laryngeal inflammatory and immune cell responses by low and high doses of mainstream cigarette smoke

Mediating Effect of White Blood Cells and Tobacco Exposure on Cervical Neoplasm Risk Among Taiwanese Women

Background: Both the high-risk human papillomavirus (HR-HPV) infection and tobacco exposure are significantly associated with cervical neoplasm risk. Immune cells play important roles in carcinogenesis. However, it is still unclear whether immune cells have a mediating effect on the HR-HPV infection and tobacco exposure with cervical neoplasm development. Aim: The aim of this study was to determine how the increased white blood cell (WBC) count affects the relationship between HR-HPV DNA load and tobacco exposure in the development of cervical neoplasia. Methods: A hospital-based case-control study design was conducted with a total of 108 cases of Taiwanese women with ≥ cervical intraepithelial neoplasia (CIN) I confirmed by biopsy, and 222 healthy Taiwanese female subjects with negative findings on a Pap smear were assigned to the control group. The study evaluated HR-HPV status and immune cell counts (WBCs, natural killer (NK) cells) and tobacco exposure by a self-construct questionnaire. Results: Both HR-HPV DNA load and tobacco exposure significantly independently increased cervical neoplasm risk (AORs: 1.28 and 1.42, respectively). Similar significant results were found for WBCs and NK cells, with respective AORs of 1.20 and 1.00. Moreover, increased WBCs (β = 0.04, 95% CI corrected: 0.01-0.07) and tobacco exposure (β = 0.02, 95% CI corrected: 0.01-0.04) mediated the relationship between the high-risk HPV DNA load and cervical neoplasm risk. Conclusions: Elevated WBC count acts as both predictor and mediator in cervical neoplasm development linked to HR-HPV DNA load. Monitoring and maintaining WBC levels within the normal range could be a preventive strategy for cervical neoplasm development.

Effects of Short-term Electronic(e)-Cigarette Aerosol Exposure in the Mouse Larynx

OBJECTIVES

The effects of electronic cigarettes (e-cigarettes) on the larynx are relatively unknown. This study examined the short-term effects of e-cigarette inhalation on cellular and inflammatory responses within the mouse laryngeal glottic and subglottic regions after exposure to pod-based devices (JUUL).

METHODS

Male C57BL6/J mice (8-9 weeks) were assigned to control (n = 9), JUUL flavors Mint (JMi; n = 10) or Mango (JMa; n = 10). JUUL mice were exposed to 2 h/day for 1, 5, and 10 days using the inExpose inhalation system. Control mice were in room air. Vocal fold (VF) epithelial thickness, cell proliferation, subglandular area and composition, inflammatory cell infiltration, and surface topography were evaluated in the harvested larynges. Mouse body weight and urinary nicotine biomarkers were also measured. Chemical analysis of JUUL aerosols was conducted using selective ion flow tube mass spectrometry.

RESULTS

JUUL-exposed mice had reduced body weight after day 5. Urinary nicotine biomarker levels indicated successful JUUL exposure and metabolism. Quantitative analysis of JUUL aerosol indicated that chemical constituents differ between JMi and JMa flavors. VF epithelial thickness, cellular proliferation, glandular area, and surface topography remained unchanged after JUUL exposures. Acidic mucus content increased after 1 day of JMi exposure. VF macrophage and T-cell levels slightly increased after 10 days of JMi exposures.

CONCLUSIONS

Short-term e-cigarette exposures cause minimal flavor- and region-specific cellular and inflammatory changes in the mouse larynx. This work provides a foundation for long-term studies to determine if these responses are altered with multiple e-cigarette components and concentrations.

LEVEL OF EVIDENCE

N/A Laryngoscope, 134:1316-1326, 2024.

Method for Collecting Single Epithelial Cells from the Mouse Larynx

OBJECTIVE

The larynx is lined by specialized epithelial cell populations. Studying molecular changes occurring in individual epithelial cell types requires a reliable method for removing these cells from the larynx. Our objective was to develop a method to harvest individual epithelial cells from the mouse larynx while minimizing contamination from non-laryngeal sites and non-epithelial laryngeal cells.

METHODS

Mice were euthanized, and the larynx was carefully exposed and separated from non-laryngeal sites. A small dental brush was inserted into the laryngeal inlet and rotated to obtain epithelial cells. Cells were transferred to collection media, counted, and cytospin preparations stained for laryngeal epithelial (i.e., Pan-Keratin, EpCAM, NGFR, p63, K5, β-tubulin, MUC5AC) and non-epithelial (i.e., vimentin) cell markers. Histopathology was completed on brushed laryngeal tissue sections to evaluate the depth of cell collection. Preliminary Single-cell RNA sequencing (scRNA-seq) was performed to confirm this method can capture diverse laryngeal cell types.

RESULTS

We collected 6000-8000 cells from a single larynx and 35000-40000 cells from combining brushings from three tissues. Histopathology demonstrated brushing removed the epithelial layer of the larynx and some underlying tissue. Immunofluorescence staining demonstrated the phenotype of harvested cells was primarily epithelial. Preliminary scRNA-seq was successfully conducted and displayed nine unique cell clusters.

CONCLUSION

We developed a reliable method of harvesting individual epithelial cells from the mouse larynx. This method will be useful for collection of laryngeal cells for a variety of downstream cellular and molecular assays, including scRNA-seq, protein analyses, and cell-culture-based experiments, following laryngeal injury.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:786-794, 2024.