Researchers identify immune cells that trigger psoriasis

By Ernest Gill Dec 7, 2009, 2:08 GMT

Hamburg - Researchers have discovered a novel type of immune cell in the skin of individuals with chronic skin inflammations which could lead to long-lasting therapies against asthma, COPD, psoriasis, as well as assist healing.

In their findings, published in the Journal of the American Society for Clinical Investigation, the scientists report that the so-called Th22 cells boosted inflammation against invading bacteria or viruses when the immune messengers interleukin-22 (IL-22) and the pro-inflammatory cytokine tumour necrosis factor alpha (TNF alpha) were expressed.

However, in the absence of TNF, they calmed inflammatory processes, and improved wound healing and tissue repair.

This mode of action is in line with the previous discovery that IL-22 triggers psoriasis in mice in a dose-dependent manner, and that inhibition of the cytokine improves psoriasis symptoms.

To date, the researchers have found Th22 cells in the outer skin layer (epidermis) of patients with atopic eczema, psoriasis, and allergic skin diseases.

They appear to be a part of the body's first line of defence against infections, dubbed the innate immune system. In healthy skin, the cells contribute to immune protection and wound healing.

Now the German researchers are seeking to crack the detailed mechanisms by which the cells contribute to allergic diseases. Their findings could help with the development of future therapies against the serious disorders.

The researchers from Italy, Britain and Germany headed by Stefanie Eyerich from Helmholtz Centre Munich said the discovery is a milestone on the path towards the development of new treatment methods for psoriasis and allergic reactions, as well as against asthma.

Like other T helper cells, Th22 cells belong to a part of the immune system that can recognise damaging pathogens even after a longer period of time. This means that any treatment targeting these cells would potentially have a long-term effect.