Cellular and Transcriptional Responses of Human Bronchial Epithelial Cells to Delta-9-Tetrahydrocannabinol In Vitro

TL;DR

This study shows how THC exposure harms human bronchial cells by causing cell death and altering gene activity, especially through a process called ferroptosis.

Contribution

The study identifies ferroptosis as a key pathway in THC-induced bronchial epithelial cell death and provides insights into the molecular mechanisms involved.

Findings

THC exposure significantly reduced cell viability in a dose-dependent manner.

Transcriptome analysis revealed activation of pathways like ferroptosis and HIF-1 signaling.

Inhibiting ferroptosis reduced THC-induced cell death, confirming its role in the process.

Abstract

Delta-9-tetrahydrocannabinol (Δ-9-THC or THC), the primary psychoactive constituent of cannabis, can lead to adverse health conditions, including mental health issues, brain impairment, and cardiac and respiratory problems. The amount of THC in cannabis has steadily climbed over the past few decades, with today’s cannabis having three times the concentration of THC compared to 25 years ago. Inhalation is a major route of exposure, allowing substances to enter the body via the respiratory tract. THC exposure causes cell death in the airway epithelium; however, the molecular underpinning of THC exposure-induced bronchial epithelial cell death is not clearly understood. To address the mechanisms involved in this process, the present study examined the cell viability, oxidative stress, lipid peroxidation, and transcriptional alterations caused by various concentrations of Δ-9-THC (0, 800, 1000, 1200, and 1500 ng/mL) in a human bronchial epithelial cell line (BEAS-2B) in vitro. Δ-9-THC exposure caused a significant dose-dependent decrease in cell viability after 24 h exposure. Transcriptome analysis showed a distinct dose-dependent response. HIF-1 signaling, ferroptosis, AMPK signaling, and immunogenic pathways were activated by Δ-9-THC-upregulated genes. Glutathione and fatty acid metabolic pathways were significantly altered by Δ-9-THC-dependent downregulated genes. Ingenuity Pathway Analysis (IPA) revealed several top canonical pathways altered by Δ-9-THC exposure, including ferroptosis, NRF-2-mediated oxidative stress response, caveolar-mediated endocytosis (loss of cell adhesion to the substrate), tumor microenvironment, HIF1alpha signaling, and the unfolded protein response pathway. Δ-9-THC-induced cell death was ameliorated by inhibiting the ferroptosis pathway, whereas treatments with ferroptosis agonist exacerbated the cell death process, suggesting that Δ-9-THC-induced bronchial epithelial cell death potentially involves the ferroptosis pathway.

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