pSo Facts

What Causes Psoriasis?

Psoriasis is an autoimmune disease. Although the cause of psoriasis is not fully understood, researchers believe that a combination of genetic and environmental factors will trigger the body’s immune system.

A type of white blood cell, called a T-cell that usually fights off bacteria, attacks healthy cells by mistake. The immune system also produces proteins called cytokines, which normally have a role in fighting infection. Tumor Necrosis Factor Alpha (TNF-a), Interleukin 12/23 (1L12 + 1L23) and Interleukin 17A all play a part.

Heightened levels of the cytokines trigger an abnormal immune response that causes inflammation, itchy skin, and rashes.

Two main factors contribute to changes in the skin:

Skin Cell Changes

Certain types of skin cells (the keratin layer – see the diagram below) do not develop normally.

Changes in the Cell Cycle

Skin can also appear scaly as the skin cells reproduce, but do not die off as fast as they normally would. This causes skins cells to proliferate and build-up in thickened, flaky layers.

Psoriasis causes skin inflammation, with thickening of the skin as skin cells build up, and abnormal skin cell development in the keratin layer of the skin, resulting in scaly plaques.

Plaques are patches of skin with psoriasis symptoms. They can be raised red patches covered with a silvery white buildup of dead skin cells or “scale”. Plaques can be itchy and painful, and may crack and bleed. The scalp, knees, elbows and lower back are areas most often affected.

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