Psoriasis is a type of skin disorder caused by autoimmune-like attacks on skin cells by the body’s immune system. Patches of affected skin appear most often on elbows, knees, scalp, belly, and lower back. Triggers can include infection with the streptococcal bacteria, irritation or injury to the skin, smoking or alcohol use, and stress. Once an area has been affected there will often be a cycle during which the inflammation and rapid growth of the skin forms the hallmark plaque, then fades before returning. The inflammation that occurs with psoriasis involves many different cell types creating a positive feedback cycle. The innate immune cells like dendritic cells and macrophages that live in or near the skin become activated by one of the previous triggers and signal for other immune cells from the adaptive immune system (T and B cells) to come to the location. Dendritic cells release antimicrobial proteins in response to injury to the skin which are recognized by keratinocytes - a type of skin cell - which begin to divide more rapidly to replace damaged cells. T cells bring the most inflammation though. Recruited by factors released by dendritic cells, T cells encourage the skin to divide rapidly, and they prevent cell death, keeping skin from sloughing off. B cells are also important for warding off infection and usually help T cells. However, with psoriasis, regulatory types of B cells can reduce inflammation, working against T cells. They produce a factor known as IL-10 that works to suppress the body’s immune system. B regulatory cells tend to be absent in psoriasis plaques and are generally decreased compared to a healthy individual. However, it has been found that treatments that deliver IL-10s reduce psoriasis symptoms, which indicates that strengthening the production of these cells in individuals with psoriasis could relieve some of their symptoms. Further strengthening this link, patients treated with the drug Rituximab which suppresses B cell function developed psoriasis-like patches on their skin. Furthermore, in mice who were genetically engineered to lack B cells, it was found that chronic inflammation occurred with psoriasis-like inflammation of the skin being one of the symptoms. More research must be done on the topic, since previous research has focused mainly on T cells, but this provides an interesting avenue for discussion and hope for better treatments for those with psoriasis at some point in the future.
Grän, F, et al. (2020). Current Developments in the Immunology of Psoriasis. Yale Journal of Biology and Medicine, 93(1): 97-110. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7087066/
Psoriasis is classified as a psychophysiological disorder because stress is not the primary cause, but stress triggers and worsens the symptoms. Stressors negatively impact the immune system, which directly correlates to the inflammatory response related to flares in skin disorders. Stressors trigger the nervous system to release hormones into the blood that affect skin physiology. Many studies have shown that psychological interventions may play an integral role in the management of psoriasis. Efficacious psychological interventions include arousal reduction therapy and cognitive behavior therapy. Arousal reduction is a mindfulness meditation-based therapy aimed at reducing stress by listening to an audio-tape recording. Arousal reduction combined with phototherapy, a traditional medical treatment with proven success in treating psoriasis, showed significant improvement in the rate of psoriasis clearance when compared to phototherapy alone (Moon et al., 2013). One study provided support for the addition of cognitive behavior therapy with the standard medical care of psoriasis. Patients who received adjunctive cognitive behavior therapy had significantly reduced severity of psoriatic lesions, with 64% of patients achieving 75% psoriasis clearance at the six-month follow-up when compared with 23% of the control group (Moon et al., 2013). The CBT group also showed reductions in anxiety and depression scores and almost double the reduction in self-reported disability and life stress scores at the six-month follow-up (Moon et al., 2013).
ReplyDeleteMoon, H.-S., Mizara, A., & McBride, S. R. (2013). Psoriasis and Psycho-Dermatology. Dermatology and Therapy, 3(2), 117–130. https://doi.org/10.1007/s13555- 013-0031-0