Clarifying CB2 receptor-dependent and independent effects of THC on human lung epithelial cells

Journal Article · Mon Sep 15 04:00:00 EDT 2008 · Toxicology and Applied Pharmacology

DOI:https://doi.org/10.1016/j.taap.2008.05.001· OSTI ID:21140952

Sarafian, Theodore ^[1]; Montes, Cindy; Harui, Airi ^[1]; Beedanagari, Sudheer R ^[2]; Kiertscher, Sylvia ^[1]; Stripecke, Renata ^[3]; Hossepian, Derik ^[1]; Kitchen, Christina ^[4]; Kern, Rita; Belperio, John ^[1]; Roth, Michael D ^[1]

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1. Division of Pulmonary and Critical Care, Department of Medicine, David Geffen School of Medicine at UCLA, 37-131 CHS, Los Angeles, CA 90095 (United States)
2. Interdepartmental Program in Molecular Toxicology, David Geffen School of Medicine at UCLA, 37-131 CHS, Los Angeles, CA 90095 (United States)
3. Division of Gastroenterology, Department of Medicine, David Geffen School of Medicine at UCLA, 37-131 CHS, Los Angeles, CA 90095 (United States)
4. Department of Biostatistics, UCLA School of Public Health, 37-131 CHS, Los Angeles, CA 90095 (United States)

Marijuana smoking is associated with a number of abnormal findings in the lungs of habitual smokers. Previous studies revealed that {delta}{sup 9}-tetrahydrocannabinol (THC) caused mitochondrial injury in primary lung epithelial cells and in the cell line, A549 [Sarafian, T. A., Kouyoumjian, S., Khoshaghideh, F., Tashkin, D. P., and Roth, M. D. (2003). Delta 9-tetrahydrocannabinol disrupts mitochondrial function and cell energetics. Am J Physiol Lung Cell Mol Physiol 284, L298-306; Sarafian, T., Habib, N., Mao, J. T., Tsu, I. H., Yamamoto, M. L., Hsu, E., Tashkin, D. P., and Roth, M. D. (2005). Gene expression changes in human small airway epithelial cells exposed to Delta9-tetrahydrocannabinol. Toxicol Lett 158, 95-107]. The role of cannabinoid receptors in this injury was unclear, as was the potential impact on cell function. In order to investigate these questions, A549 cells were engineered to over-express the type 2 cannabinoid receptor (CB2R) using a self-inactivating lentiviral vector. This transduction resulted in a 60-fold increase in CB2R mRNA relative to cells transduced with a control vector. Transduced cell lines were used to study the effects of THC on chemotactic activity and mitochondrial function. Chemotaxis in response to a 10% serum gradient was suppressed in a concentration-dependent manner by exposure to THC. CB2R-transduced cells exhibited less intrinsic chemotactic activity (p < 0.05) and were 80- to 100-fold more sensitive to the inhibitory effects of THC. Studies using SR144528, a selective CB2R antagonist, verified that these effects were mediated by the CB2R. Marijuana smoke extract, but not smoke extracts from tobacco or placebo marijuana cigarettes, reproduced these effects (p < 0.05). THC decreased ATP level and mitochondrial membrane potential ({psi}{sub m}) in both control and CB2R-transduced cells. However, these decreases did not play a significant role in chemotaxis inhibition since cyclosporine A, which protected against ATP loss, did not increase cell migration. Moreover, CB2R-transduced cells displayed higher {psi}{sub m} than did control cells. Since both {psi}{sub m} and chemotaxis are regulated by intracellular signaling, we investigated the effects of THC on the activation of multiple signaling pathways. Serum exposure activated several signaling events of which phosphorylation of I{kappa}B-{alpha} and JNK was regulated in a CB2R- and THC-dependent manner. We conclude that airway epithelial cells are sensitive to both CB2R-dependent and independent effects mediated by THC.

• OSTI ID: 21140952
• Journal Information: Toxicology and Applied Pharmacology, Journal Name: Toxicology and Applied Pharmacology Journal Issue: 3 Vol. 231; ISSN TXAPA9; ISSN 0041-008X
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
ATP
CYCLOSPORINE
INJURIES
LUNGS
MARIHUANA
MITOCHONDRIA
PHOSPHORYLATION
RECEPTORS
RESPIRATORY TRACT CELLS
SMOKES
TOBACCO