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Published on: April 2, 2013
Enhanced growth of Legionella pneumophila in tetrahydrocannabinol-treated macrophages
1Department of Medical Microbiology and Immunology, University of South Florida College of Medicine, Tampa 33612.
Abstract:
Legionella pneumophila is an opportunistic intracellular pathogen that infects macrophages, both in vivo and in vitro. Tetrahydrocannabinol is a major psychoactive component of marijuana and can affect the functional activity of macrophages. In the present study, it was found that the treatment of macrophage cultures from permissive A/J mice with THC enhanced the growth of Legionella in these cells. Legionella grew much better in macrophages treated with low doses of THC, which caused no alteration in the number or viability of macrophages, as compared with growth in untreated cells. Furthermore, lipopolysaccharide-treated A/J mouse macrophages restricted the growth of Legionella, but this growth restriction was overcome by the addition of THC to LPS-treated macrophage cultures after infection. Thus, it is apparent that THC has the ability to enhance the growth of the intracellular opportunistic pathogen Legionella that grows in A/J mouse macrophages.
Insights
Tetrahydrocannabinol (THC), a marijuana component, enhances the growth of Legionella pneumophila, an opportunistic pathogen, within macrophages. This effect occurs even at low THC doses without impacting macrophage viability, highlighting a potential risk.
Area of Science:
- Immunology
- Microbiology
- Pharmacology
Background:
- Legionella pneumophila is an opportunistic intracellular pathogen.
- Tetrahydrocannabinol (THC) is the primary psychoactive compound in marijuana.
- THC can modulate macrophage functional activity.
Purpose of the Study:
- To investigate the effect of THC on Legionella pneumophila growth in macrophages.
- To determine if THC influences macrophage-pathogen interactions.
Main Methods:
- Macrophage cultures from A/J mice were treated with varying doses of THC.
- Legionella pneumophila growth was assessed in both untreated and THC-treated macrophages.
- The impact of THC on lipopolysaccharide (LPS)-induced growth restriction was evaluated.
Main Results:
- Low doses of THC significantly enhanced Legionella pneumophila growth in macrophages.
- THC treatment did not alter macrophage number or viability.
- THC reversed the growth-inhibitory effect of LPS on Legionella in macrophages.
Conclusions:
- THC promotes the intracellular growth of Legionella pneumophila in macrophages.
- THC may impair the host immune response against Legionella infection.
