How cannabis suppresses immune functions: Cannabis compounds found to trigger unique immune cells which promote cancer growth
November 26, 2010
Science Daily/Wiley-Blackwell
An international team of immunologists studying the effects of cannabis have discovered how smoking marijuana can trigger a suppression of the body's immune functions. The research, published in the European Journal of Immunology, reveals why cannabis users are more susceptible to certain types of cancers and infections.
The team, led by Dr Prakash Nagarkatti from the University of South Carolina, focused their research on cannabinoids, a group of compounds found inside the cannabis plant, including THC (delta-9 tetahydrocannabinol) which is already used for medical purposes such as pain relief.
"Cannabis is one of the most widely used drugs of abuse worldwide and it is already believed to suppress immune functions making the user more susceptible to infections and some types of cancer," said Dr Nagarkatti. "We believe the key to this suppression is a unique type of immune cell, which has only recently been identified by immunologists, called myeloid-derived suppressor cells, MDSCs."
While most immune cells fight against infections and cancers to protect the host, MDSCs actively suppress the immune system. The presence of these cells is known to increase in cancer patients and it is believed that MDSCs may suppress the immune system against cancer therapy, actually promoting cancer growth.
Dr Nagarkatti's team demonstrated that cannabinoids can trigger a massive number of MDSCs through activation of cannabinoid receptors. This research reveals, for the first time, that marijuana cannabinoids may suppress the immune system by activating these unique cells.
"These results raise interesting questions on whether increased susceptibility to certain types of cancers or infections caused from smoking marijuana results from induction of MDSCs," said Nagarkatti. "MDSCs seem to be unique and important cells that may be triggered by inappropriate production of certain growth factors by cancer cells or other chemical agents such as cannabinoids, which lead to a suppression of the immune system's response."
In a related study, also published in the European journal of Immunology, Dr Christian Vosshenrich from the Institut Pasteur in Paris, reveals that when cancer cells grow they produce a molecule called interleukin-1 β (IL-1β), which also triggers MDSCs. This study identifies how MDSCs produced during cancer growth also weaken the ability of immune cells to kill cancer cells.
"Marijuana cannabinoids present us with a double edged sword," concluded Dr Nagarkatti. "On one hand, due to their immunosuppressive nature, they can cause increased susceptibility to cancer and infections. However, further research of these compounds could provide opportunities to treat a large number of clinical disorders where suppressing the immune response is actually beneficial."
https://www.sciencedaily.com/releases/2010/11/101124214728.htm
Cannabis extract can have dramatic effect on brain cancer
November 14, 2014
Science Daily/University of St George's London
Experts have shown that when certain parts of cannabis are used to treat cancer tumours alongside radio therapy treatment the growths can virtually disappear.
The new research by specialists at St George's, University of London, studied the treatment of brain cancer tumours in the laboratory and discovered that the most effective treatment was to combine active chemical components of the cannabis plant which are called cannabinoids.
Two of these called tetrahydrocannabinol (THC) and cannabidiol (CBD) were tested as part of the research into brain cancer which is particularly difficult to treat and claims the lives of about 5,200 each year. It also has a particularly poor prognosis as the rate of survival after five years of patients' diagnosis is around 10%.
Cannabinoids are the active chemicals in cannabis and are also known more specifically as phytocannabinoids. There are 85 known cannabinoids in the cannabis plant.
The new research is the first to show a drastic effect when combining THC and CBD with irradiation. Tumours growing in the brains of mice were drastically slowed down when THC/CBD was used with irradiation.
Dr Wai Liu, Senior Research Fellow and lead researcher on the project, said: "The results are extremely exciting. The tumours were treated in a variety of ways, either with no treatment, the cannabinoids alone, and irradiation alone or with both the cannabinoids and irradiation at the same time.
"Those treated with both irradiation and the cannabinoids saw the most beneficial results and a drastic reduction in size. In some cases, the tumours effectively disappeared in the animals. This augurs well for further research in humans in the future. At the moment this is a mostly fatal disease.
"The benefits of the cannabis plant elements were known before but the drastic reduction of brain cancers if used with irradiation is something new and may well prove promising for patients who are in gravely serious situations with such cancers in the future."
The research team are discussing the possibility of combining cannabinoids with irradiation in a human clinical trial.
The research has been published in the Molecular Cancer Therapeutics journal.
Cannabinoids are the active chemicals in cannabis and are also known more specifically as phytocannabinoids. There are 85 known cannabinoids in the cannabis plant. The primary psychoactive component of cannabis is called tetrahydrocannabinol (THC).
https://www.sciencedaily.com/releases/2014/11/141114085629.htm