Some of the immune cells that cause the inflammatory skin disease psoriasis may also stave off viral infections, a new study suggests.
Psoriasis and another skin disease called eczema both lead to broken, inflamed skin, yet psoriasis sufferers are less prone to viral skin infections than people with eczema are. To find out why, Kerstin Wolk of the Charité University Hospital in Berlin and colleagues compared levels of virus-fighting proteins in skin samples from people with the diseases. People with psoriasis had much higher levels of antiviral proteins than those with eczema did, the team reports September 25 in Science Translational Medicine.
In healthy people, the cue for cells to make antiviral proteins comes from immune chemicals called interferons. But people with psoriasis, the researchers found, turn on virus defenses through a different chemical: an immune protein called interleukin-29, or IL-29. Immune cells called T helper 17 cells make the IL-29; in turn, the IL-29 raises the alarm against viral invaders.
In contrast, people with eczema make a protein that lowers IL-29 production, leaving them more vulnerable to viral infections.
