How is cortisol effective in treatment of arthritis?

Corticosteroids are used in arthritis for two reasons:

1. First they are anti-inflammatory i.e., they inhibit the inflammatory and allergic reactions.
2. And second, they are immunosuppressive i.e., they reduce the activity of immune system.

Glucocorticoids stabilize the lysosomal membranes and prevents the secretion of enzymes that normally occurs during inflammation. They also inhibit the infiltration of leukocytes into the affected tissue.

Interleukin-1 (IL-1), polypeptides produced by activated monocytes has an important role in eliciting a variety of physiological reactions observed during infection and inflammation. Stimulation of ACTH release is in one of those important nonimmune responses, which is induced by IL-1-beta. Increased hypothalamic-pituitary-adrenal activity results in an increased secretion of glucocorticoids that suppress immune responses, and hence, unfavorable overstimulation of the immune reaction, during infection or other conditions.