How steroids Work
The corticosteroids we use to treat eczema, called glucocorticoids, act to block the production of several chemicals involved in the immune system response that triggers inflammation. One of the mechanisms by which they do this is by constricting capillaries to reduce blood flow to the inflamed areas, resulting in a reduction of histamines and other inflammatory chemicals flowing to those areas.
Another mechanism is the interaction with DNA in the cell nucleus which causes the cell to produce proteins called lipocortins. These lipocortins then disable the production of arachidonic acid which in turn blocks the production of various chemicals involved in inflammation, including leukotrienes, prostaglandins, and platelet-activating factor.
Glucocorticoids also impact the production and distribution of certain white blood cells, called T and B lymphocytes, which are responsible for identifying and responding to very specific antigens. Lymphocytes are involved in the memorising of bacteria, virus, and other pathogens via the B lymphocyte produced immunoglobulin (Ig) proteins. Ig proteins, especially IgE, are involved in increased allergic responses, including various dermatoses.
Inflammation happens to be an integral part of the process by which our bodies fight infection, but in eczema and other diseases it can proceed out of control, and even occur when there is no real infection at all.
The body naturally produces its own steroids in a part of the adrenal gland called the adrenal cortex. The primary steroids produced here are cortisol, corticosterone, aldosterone, and dehydroepiandrosterone. Cortisol, which is most import to this discussion, is essential for metabolism, stress control, vascular and immune function, and the central nervous system.
Modern topical coricosteroids, which are similar to cortisol, have been engineered to very selectively block glucocorticoid receptors, helping to reduce some of the negative side effects of the medications, and to enhance effectiveness at treating skin inflammations.