Psoriasis is a chronic inflammatory skin disease of unknown etiology that affects between 1 and 3% of the population. There is increased proliferation of the epidermis with infiltration of inflammatory cells within the dermis and epidermis, coupled with dilation of the upper dermal capillaries. Psoriasis tends to run in families and may be associated with certain HLA phenotypes; individuals with first-degree relatives with psoriasis are more likely to develop the disease themselves. Abnormalities of arachidonic acid metabolism have been demonstrated within psoriatic plaques, and it is possible that arachidonic acid and its metabolites may be intimately involved in the psoriatic process. An increase in the levels of prostaglandins (PGs) may cause vasodilation and erythema, and leukotrienes, such as 5,12-dihydroxy-6,14-c;'s-8,10-trans-eicosatetraenoic acid (LT-B4) and 12-hydroxy-5,8,14-c;'s-10-trans-eicosatetrae-noic acid (12-HETE), as well as interleukin (IL)-8, and the complement product C5a des arg may cause neutrophil accumulation (1-4). Raised levels of calmodulin, a cellular receptor protein for calcium, have been demonstrated in psoriatic lesions. The calcium-calmodulin complex may influence cell proliferation in psoriasis by modulating the activities of phospholipase-A2 (which releases arachidonic acid from cell membranes) and phosphodiesterase. Drugs such as anthralin (dithranol) and cy-closporine, which are beneficial in psoriasis, are calmodulin antagonists. Intracellular cAMP levels are decreased within psoriatic lesions and drugs that decrease cAMP levels, such as ^-blockers or lithium, may worsen psoriasis. Conversely, drugs such as benoxaprofen (now withdrawn) which elevate cAMP levels may improve psoriasis.
The role of T lymphocytes in psoriasis is unclear. However, T-helper lymphocytes form a major part of the dermal inflammatory cell infiltrate, and thus the effect of cyclosporine in psoriasis may be partly due to its anti-T-helper cell activity.
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Do You Suffer From the Itching and Scaling of Psoriasis? Or the Chronic Agony of Psoriatic Arthritis? If so you are not ALONE! A whopping three percent of the world’s populations suffer from either condition! An incredible 56 million working hours are lost every year by psoriasis sufferers according to the National Psoriasis Foundation.