How do topical steroids inhibit cutaneous inflammation?

The steroid molecule binds to specific cytoplasmic steroid receptors that are transported to the cell nucleus, where it interacts with high-affinity binding sites on nuclear DNA. Steroid-induced proteins, called lipocortins, are then synthesized by the target cells. There is good evidence that these proteins inhibit phospholipase A₂, an enzyme necessary for formation of inflammatory mediators (e.g., arachidonic acid, prostaglandins, leukotrienes, and plateletactivating factor) that decrease vascular permeability. Another immediate effect of topical steroids is to produce vasoconstriction, thus decreasing tissue edema, erythema, and heat. The steroid molecule can also bind to cell membranes, altering their function. Inflammatory cells show reduced migration and function at sites of inflammation.