Marijuana as a possible treatment for HIV and cancer

There’s been some interesting research on using THC (tetrahydrocannabinol), the principal psychoactive drug in marijuana, to help fight HIV, and damage cancer cells in some leukemias and possibly malignant tumors.

This research is still just that, research, and is years away from actually being used to control HIV. But the possibility exists that information from both of these research studies may produce beneficial results in the treatment of HIV and cancer.

Let me walk you through the studies.

Marijuana

Marijuana via Shutterstock

How macrophages spread HIV in your system

Macrophages are a specific type of white blood cell that is often targeted by HIV when an infection begins. Macrophages have several functions. One is that they act as scavengers. They move through tissues, picking up tiny particles of debris (or viruses), destroy dead or damaged cells, send out signals to lymphocytes, etc. When they pick up viruses, they may continue to travel around as they normally do. If a macrophage has already been targeted by HIV in your system, as the macrophage moves through your body it can spread HIV to uninfected cells.

So the ability to slow or stop HIV entry into the macrophages could drastically slow the spread of the HIV virus to uninfected cells.  But how do we do that?  Enter THC.

How THC might be able to stop macrophages from spreading HIV

Cells have any number of different receptors and receptor types on their cell membranes. When something that is specific to that receptor binds there (think of a specific key fitting into a specific lock) it signals the cell to do something – produce a chemical, move away, activate a gene, etc.

Among the many different types of receptors on macrophages (and other cells) are CB1 and CB2 receptors. When marijuana is smoked, THC activates both of these receptors. When the CB1 receptor is activated in certain cells, the classic marijuana “high” is produced. Activation of the CB2 receptor doesn’t produce the marijuana “buzz”.

In macrophages, activating the CB2 receptor makes them more effective at resisting HIV infection. These macrophages are then less likely to pick up the HIV virus even when exposed to it at fairly high concentrations.

The chemicals that the researchers from Temple University School of Medicine used are similar to THC, and work in a similar manner. The investigators feel that a drug may be developed that will selectively stimulate the CB2 receptors, and not produce the psychoactive effects of smoking marijuana.

To date, this research has only been done in white blood cells in tissue culture. Much more work is needed before human trials can even be considered.

The above research was published last May and work is continuing.

THC and Cancer

In a journal article from just this month, researchers in Louisiana demonstrated another benefit of THC in viral infections. It has been known for a few years that THC (and possibly some other compounds in marijuana) are effective in not only working against HIV, but also playing a role in doing damage to cancer cells in some types of leukemias and possibly malignant tumors.

The researchers from Louisiana State University Health Sciences Center used THC in male rhesus monkeys. The monkeys were first given an intravenous dose of simian immunodeficiency virus (SIV), the rhesus’ equivalent of HIV. The monkeys were confirmed to have acquired the infection. Next, they were given intramuscular injections of THC twice a day for 17 months.

Samples of duodenal (small bowel) tissue were taken. The results showed that the monkeys’ duodenal tissue had a higher level of memory T cells and Th2 cytokines (regulating the immune response.) The THC medicated monkeys also showed a lower viral load than their control counterparts.

In various parts of the intestines, there are localized areas of lymphoid tissue, called Gut-Associated Lymphoid Tissue (GALT). HIV infects this tissue and reproduces there. The virus can then spread from the areas of GALT to other cells and tissues. And, it can cause gut inflammation and local problems with the bowel, as well.

So, the injections of THC had direct, positive effects on these three things: larger numbers of T cells, higher Th2 cytokines and lower viral load. With additional research, it may be that THC, or some form of it, may be useful as a drug to decrease the spread of HIV in an already infected patient.


Mark Thoma, MD, is a physician who did his residency in internal medicine. Mark has a long history of social activism, and was an early technogeek, and science junkie, after evolving through his nerd phase. Favorite quote: “The most exciting phrase to hear in science... is not 'Eureka!' (I found it!) but 'That's funny.'” - Isaac Asimov

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