After decades of modest advances, psoriasis research has caught fire. In the past ten years, immunosuppressant drugs developed for other autoimmune diseases, such as rheumatoid arthritis, have had a powerful effect in treating severe cases. What's more, this success underscores the crucial role the immune system plays in psoriasis — and points to new ways to treat this inflammatory skin disease. Digging deeper into the underlying causes of psoriasis has unearthed a host of new drug targets. And several promising treatments are nearing clinical approval (see page S58).

Building on this knowledge, genetic studies have provided clues to which parts of the immune system have gone awry in psoriasis — and hinted at where this enigmatic disease might start (S56).

Indeed, psoriasis has become something of a therapeutic test bed for other immune-mediated and inflammatory conditions. Its visible plaques are easy to measure and biopsy to assess treatment efficacy (S50). Psoriasis research has shown the skin to be a vibrant, immunologically active organ (S52). And the skin is home to a variety of microbial communities — disturbances in the skin microbiome may well be what opens the door to psoriasis in the first place (S60).

Although its most obvious impact is on the skin, psoriasis runs deep. Patients are at increased risk of cardiovascular disease, have a higher incidence of metabolic syndrome, and often get psoriatic arthritis. Dermatologist Henning Boehncke outlines the implications of these effects on general healthcare (S55). Psoriasis takes a psychological toll too. In certain individuals, stress can cause the disease to flare up (S62), but holistic treatments using cognitive behavioural therapy seem to help (S64).

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