This article discusses cannabinoids, which are a non-psychoactive derivative of cannabis. This is not to be confused with recreational cannabis use or medical marijuana, neither of which are discussed or endorsed in this post.
In recent years cannabis-derived chemicals have been studied in clinical trials to assess their potential for medical use, such as treatment for chronic pain, spasticity, nausea following chemotherapy, anorexia, for treating seizures or to combat autoimmune diseases. Researchers have also investigated the use of cannabis-derived chemicals for the treatment of skin conditions including pruritus, inflammatory skin disease, and skin cancer. One of the most promising roles for cannabinoids in dermatology is in the treatment of psoriasis and there is hope that people with psoriasis may be able to find relief with the use of non-psychotropic topical cannabinoids. (1)
What are Cannabinoids?
The cannabinoids are a class of chemical compounds that acts on specific receptors (cannabinoid receptors). The cannabinoid receptors are located in the brain and also throughout the body and are involved in a variety of physiological processes including appetite, pain-sensation, mood, regulation of the immune system and memory. Substances that bind to these receptors include the endocannabinoids (produced naturally in the body), the phytocannabinoids (found in cannabis and some other plants), and synthetic cannabinoids (produced artificially). (2)
What does the science say?
Studies indicate that several cannabinoids found in cannabis are a potential treatment for psoriasis as they could affect the immune system by suppressing the functions of some cells of the immune system - white blood cells such as macrophages and T cells (3, 4). T cells are proven to be very important in the internal process of psoriasis. T cells naturally circulate throughout the body looking for foreign substances. These foreign substances, called antigens, are usually an outside invader like a bacterium or a virus that activates the T cell, which then initiates an immune response to neutralize the antigen.
In psoriasis, activated T cells end up in the skin. It is not clear why this happens, but it may be directly related to the genetic susceptibility in people who develop psoriasis. Four of the major cannabinoids found in cannabis (tetrahydrocannabinol, cannabidiol, cannabinol and cannabigerol) have been shown to inhibit T cells responses (5) and there is hope that topical cannabinoids could help treat psoriasis symptoms by managing the overactivity of T cells. This suppressive action of cannabinoids on the immune system is not unique to these chemicals. In fact, many important and widely-used drugs to treat psoriasis suppress the immune function, and it has to be said that such immune-suppressive medications could be potentially detrimental if the patients on these drugs have to fight a concurrent infection.
Additionally, it has been found that cannabinoids inhibit the proliferation of keratinocytes, a type of skin cells that have an abnormally excessive and rapid growth in psoriasis. One study found that several of the plant cannabinoids inhibit keratinocyte proliferation in a concentration-dependent manner and supported a potential role for cannabinoids in the treatment of psoriasis through this different mechanism (6).
Although cannabinoids may have immune-suppressive effects and inhibitory effects on the keratinocyte proliferation, it has to be said that further clinical research is needed before they can be used widely for the treatment of psoriasis.
- Mounessa, J.S., Siegel, J.A., Dunnick, C.A, Dellavalle, R.P. The role of cannabinoids in dermatology Journal of the American Academy of Dermatology. 2017, 77(1), 188–190
- Croxford, J.L., and Yamamura, T. Cannabinoids and the immune system: potential for the treatment of inflammatory diseases? Journal of Neuroimmunology, 2005, 166(1-2), 3-18.
- Tanasescu, R. and Constantinescu, C.S. Cannabinoids and the immune system: An overview. Immunobiology. 2010 Aug, 215 (8): 588-597
- Eisenstein, T.K. Effects of Cannabinoids on T-cell Function and Resistance to Infection. J Neuroimmune Pharmacol. 2015 Jun; 10(2): 204–216.
- Wilkinson, J.D., and Williamson, E.M. (2007, February). Cannabinoids inhibit human keratinocyte proliferation through a non-CB1/CB2 mechanism and have a potential therapeutic value in the treatment of psoriasis. Journal of Dermatological Science, 45(2), 87-92.