Epithelial L2

Investigating Vaping and Airway Surface Liquid (ASL)

Aim

To explore the effects of vaping on airway ion channels, mucous, and the airway surface liquid (ASL).

Objectives

• Impact of E-cigarette Vehicles:
  Analyze how e-cigarette vehicles affect CFTR (Cystic Fibrosis Transmembrane Conductance Regulator), mucin, and inflammatory markers.

• Impact of E-cigarette Flavours:
  Evaluate the consequences that different e-cigarette flavours have on CFTR function.

• Comparison Between E-cigarettes and Cigarettes:
  Assess and compare the effects of both e-cigarettes and traditional cigarettes on ENaC (Epithelial Sodium Channel), CFTR, and ASL.

• Evidence Evaluation:
  Critically evaluate existing evidence regarding these effects.

Health Hazards of Smoking and Vaping

Introduction

The necessity to understand the implications of vaping and smoking stems from established health hazards associated with smoking tobacco. Current global trends show significant tobacco use among individuals aged 15 years and older, with growing interest in the youth population's engagement with e-cigarettes.

References

• WHO Global Tobacco Use Trends (January 2024).

• Williams et al., 2023. Analysis of Tobacco and E-cigarette Use Among Youth in Great Britain: A cross-sectional survey (Tob Induc Dis, 2023; 21:05; doi: 10.18332/tid/156459).

Safety Concerns

Although vaping is popular, there remains a notable lack of long-term safety data regarding its effects on health.

Composition of E-cigarettes

E-cigarettes primarily consist of several components, including:

1. Nicotine

2. Vehicle Components:

   • Glycerine

   • Propylene glycol

3. Flavouring Agents

Vehicle Impact on Ion Channel Function

Key Study

• Kim et al. (2022). Impact of Vehicle on CFTR Function (Front. Pharmacol 13:1012723; doi: 10.3389/fphar.2022.1012723).

  • Findings indicate that both vegetable glycerine (VG) and propylene glycol (PG) reduce CFTR function through alterations in membrane fluidity.

Further Impact Analysis

• Effects on mucin and the ciliary beat frequency (CBF) were noted, with mucins being impacted negatively, resulting in reduced CBF.

• The study also identified a connection between cytokines and their effects on both ENaC and CFTR which is crucial for future discussions on COVID-19 implications.

Flavouring Compounds and Their Effects

• Sherwood and Boitano (2016). Impact of Flavourings on CFTR Function

  • Specifically studied 2,5-dimethylpyrazine, a roasted nut flavouring, which has been observed to activate CFTR function in mouse tracheal cells.

  • Results showed variations in CFTR activation measured under different treatments, highlighting its potential positive impact.

Overall Impact and Need for Review

A comprehensive review of the overall impacts of vaping and smoking has become vital to understand the emerging health implications.

Impact of Smoking and Vaping on Ion Channel Function

Rayner et al. Study (2019)

This research focuses on the implications of smoking vs. vaping on ion channel functionality:

• Investigated factors include:

  • Cigarette total particulate matter (TPM) and conditioned media.

  • E-cigarette total particulate matter (e-TPM) and aerosol-conditioned media (ACM).

Measured Parameters

• Ion channel functions were tracked over time in primary normal human bronchial epithelial (NHBE) cells, measuring short-circuit current (Isc) responses to evaluate ENaC and CFTR functions. Amiloride and Forskolin shifts provided insights on ion channel activation.

Data Interpretation

The data correlated the concentration of nicotine (in micrograms per milliliter) to both cigarette and e-cigarette impacts on ENaC and CFTR functionality.

Overall Vaping and Smoking Data Summary

Beyond the presence of nicotine, other molecules also play a significant role in the observed data:

1. Impact on ASL and CBF:

   • Research noted no significant changes in ASL and CBF related to smoking or vaping, although literature presents contrasting evidence.

ENaC Function and Proteolytic Cleavage

• ENaC undergoes proteolytic cleavage modulated by various proteases such as neutrophil elastase.

  • Cleavage results in shifts that influence ENaC functionality (uncleaved vs. cleaved states).

• A formula representing the relationship can be expressed as:
  $I = N imes Po imes g imes (V<em>m - E</em>i)$

Impact of Bronchoalveolar Lavage Fluid

Research Approach

• Bronchoalveolar lavage fluid (BALF) was obtained from individuals categorized as non-smokers, smokers, and vapers.

• The study aimed to discern the effects of smoking/vaping on BALF and its implications for ENaC, CFTR, and ASL.

Key Findings

• Chronic e-cigarette use has been shown to increase levels of neutrophil elastase and matrix metalloproteases in the lung, contributing to altered ENaC and CFTR function due to increased proteolytic activity.

Clinical Implications of Smoking and Vaping

• A study by Oliveira et al. (2024) investigated the impacts of smoking on COVID-19 mortality rates, tabulating ICU admission rates, invasive ventilator support rates, and mortality rates across non-smokers and smokers.

Data Points

• Admission Rate

  • Non-smokers: 37.2%

  • Smokers: 51.6%

• Invasi ve Ventilator Support Rate

  • Non-smokers: 20.2%

  • Smokers: 31.5%

• Mortality Rate

  • Non-smokers: 31.8%

  • Smokers: 43.7%

Summary of Findings

• Evaluation of vaping vehicle effects on CFTR and documentation of literature controversy related to ENaC functionality.

• The potential for enhanced ENaC function leading to reduced ASL, indicating significant health implications.