The inflammatory process is controlled by the glucocorticoids’ activity, enhancing the transcription of anti-inflammatory genes and decreasing the transcription of inflammatory genes (Figure 3 ) [ 15 ].
Glucocorticoids induce the expression of annexin A1 (also known as lipocortin 1; encoded by ANXA 1) and ALXR (the annexin A1 receptor) by mechanisms still not known. Annexin A1 is a protein mainly located on basal keratinocytes of the basement membrane. Although in normal skin annexin A1 has been identified within cytoplasm, in diseased skin the intracellular localization of annexin A1 is apparently modified. In lesional psoriatic skin, annexin A1 appears only in the cell membrane, suggesting a translocation of the protein. This transition may occur to promote the binding of annexin A1 to phospholipids, therefore reducing the production of inflammatory prostanoids [ 37 ].
Annexin A1 inhibits phospholipase A 2 (PLA 2 ), thus blocking the synthesis of arachidonate-derived eicosanoids (prostaglandins, prostacyclins, leukotrienes, and thromboxanes) [ 32 ]. This blocking is furthered by the repression of glucocorticoid-mediated cyclooxygenase 2 transcription [ 38 – 41 ]. It remains unclear if the reduction of these substances levels come first and then plaque resolution, or if the normalization of prostanoid levels follows plaque clearance [ 37 ].
Exogenous and endogenous annexin A1 may regulate the innate immune cells activities controlling its levels of activation. Annexin A1 signals throw a formyl peptide receptor 2 (FPR2, ALXR in humans). Despite the activation of ALXR singnalling can occur by the annexin A1 autocrine, paracrine, and juxtacrine functions, the juxtacrine interaction seems to be the mechanism by which the anti-inflammatory process occurs. Concerning the innate response, it seems that the upregulation of the annexin A1 expression by leukocytes induced by glucocorticoids may be responsible for the inhibition of leukocytes response. Glucocorticoids also increase the secretion of annexin A1 by macrophages and the annexin A1 secreted by mast cells and monocytes, promotes the clearance of apoptotic neutrophils by macrophages. Endogenous annexin A1 is also released from apoptotic neutrophils and acts on macrophages promoting phagocytosis and removal of the apoptotic cells. The ALXR may be one mediator of this mechanism. Contrasting with the innate immunity, the adaptive immune system seems to act in a different way. Activation of T cells results in the release of annexin A1 and in the expression of ALXR. Although, glicocorticoids may reduce the annexin A1 expression within T-cell exposure as a consequence, there is an inhibition of T-cell activation and T cells differentiate into T helper 2 [ 42 , 43 ].
Topical steroids are available as creams, lotions, gels and ointments; selection of an appropriate product can also provide good moisturization of the skin. The wide spectrum of potencies and bases allows these mediations to be used both effectively and safely while under the care of an experienced physician.
During flares, over-the-counter moisturizing preparations that include a topical corticosteroid (such as clobetasone butyrate and hydrocortisone) are helpful to control inflammation and restore the skin barrier. The intensive use of emollient-based products can reduce the need for topical steroids.
Corticosteroids have been used as drug treatment for some time. Lewis Sarett of Merck & Co. was the first to synthesize cortisone, using a complicated 36-step process that started with deoxycholic acid, which was extracted from ox bile .  The low efficiency of converting deoxycholic acid into cortisone led to a cost of US $200 per gram. Russell Marker , at Syntex , discovered a much cheaper and more convenient starting material, diosgenin from wild Mexican yams . His conversion of diosgenin into progesterone by a four-step process now known as Marker degradation was an important step in mass production of all steroidal hormones, including cortisone and chemicals used in hormonal contraception .  In 1952, . Peterson and . Murray of Upjohn developed a process that used Rhizopus mold to oxidize progesterone into a compound that was readily converted to cortisone.  The ability to cheaply synthesize large quantities of cortisone from the diosgenin in yams resulted in a rapid drop in price to US $6 per gram, falling to $ per gram by 1980. Percy Julian's research also aided progress in the field.  The exact nature of cortisone's anti-inflammatory action remained a mystery for years after, however, until the leukocyte adhesion cascade and the role of phospholipase A2 in the production of prostaglandins and leukotrienes was fully understood in the early 1980s.