Preliminary Studies of in vitro and in vivo Effects of Misoprostol on Th-1 and Th-2 Cytokine Production.

Prostaglandins of the E series are known to suppress in vitro production of Th-1 cytokines such as interleukin-2 (IL-2) and interferon-gamma but have not been shown to suppress production of Th-2 cytokines such as IL-4 or IL-10. The present study used two new synthetic prostaglandin E(1) (PGE(1)) analogs with oral bioavailability, misoprostol (MP), and enisoprost (EP), to determine if these agents (1) exert suppressive effects in vitro on cytokine production by fresh unseparated mouse splenocytes and (2) are beneficial in vivo when used in conditions mediated by excessive Th-1 or Th-2 cytokine production. Preliminary in vitro studies demonstrated that both MP and EP can inhibit mitogen-stimulated Th-1 and Th-2 cytokine production in a dose-dependent fashion. Interestingly, at low doses, a stimulatory effect on interferon-gamma production was seen for both agents. In vivo studies tested the ability of parenteral administration of MP to alter outcome in the parent-into-F1 model of acute or chronic graft-vs-host disease (GVHD), entities thought to be mediated by excessive Th-1 or Th-2 cytokine production, respectively. Administration of MP to mice undergoing acute GVHD resulted in little detectable effect. However, in three independent experiments, MP administration in chronic GVHD mice consistently blocked GVHD-associated lymphoproliferation. In two of three experiments, GVHD-associated autoantibody production was significantly reduced. Variability between individual mice and between experiments suggests that dosing regimens and MP preparation are of critical importance. Nevertheless, these findings raise the possibility that MP may be of benefit in the treatment of human diseases characterized by excessive Th-2 cytokine production and humoral autoimmunity, for example, human lupus.