Causes of Psoriasis
Psoriasis is an immune system disorder. Several factors may influence psoriatic flare-ups or outbreaks.
Psoriasis is recognized as having a strong genetic basis. Human DNA sequencing has revealed several different regions of human DNA that seem to be linked, more or less often, to psoriasis. Psoriasis has a strong inheritance pattern, meaning patients with psoriasis often have other family members with the disease. The different regions of human DNA and how they interact to bring about the disease is not well understood. It is commonly believed that certain environmental triggers in combination with activity from various portions of the patient’s DNA bring about the manifestation of the disease.
One theory of how a psoriatic lesion forms is that an antigen, a foreign molecule recognized by the immune system, is released in the region of the would-be lesion, triggering the psoriatic process. It is thought that skin cells, specifically keratinocytes (which makeup 95% of epidermis cells), release the antigen due to injury, the presence of certain interleukin and interferon-gamma molecules, and certain medications. The keratinocyte is considered “activated” once it starts releasing these danger signals.
Certain other cells in the skin recognize the antigen and become “antigen-presenting-cells” (APCs). These cells migrate through the lymphatic system to areas where they interact with the patient’s T-cells (a form of white blood cell). The T-cells become activated and begin to signal various forms of activity at the site of injury, the would-be psoriatic lesion. Certain growth factors and other signaling chemicals are released causing skin cells to rapidly reproduce. Blood supply becomes increased due to capillary dilation and proliferation (hence the red color of the lesions). This process in turn generates more antigen and a positive feedback system is setup which can cause the psoriatic lesion to form and develop. The outer most abnormally proliferating skin cells die, building into thick, hard, silver-white patches called scale.
The exact process by which a psoriatic lesion forms is not fully understood.
Some factors may cause a psoriasis flare-up or outbreak including:
- Skin injury including scrape or cut
- Cold weather or climate changes
- Certain types of medication including lithium beta-blockers
- Withdrawal from certain medications (including corticosteroids)
- Quality-of-Life (QoL) Score