Hymenolepis diminuta and H. microstoma: uptake of cyclosporin A and drug binding to parasite cyclophilins

Immunosuppressive and antiparasitic effects of cyclosporin A on Hymenolepis nana infection in mice

The effect of cyclosporin A, which is known to act both as immunosuppressant and as an antiparasitic drug in many host-parasite systems, was examined in a mouse-Hymenolepis nana system. When BDF1 mice were injected s.c. with cyclosporin A (100 mg kg-1 day-1) every 48 h from 11 days p.i. with eggs, expulsion of the adult worms from the intestines of mice was prevented completely until at least 30 days p.i. Worm burden, dry weight and the number of gravid proglottids were not significantly reduced. By contrast, in untreated mice most of the worms were eliminated by 19 days p.i. The drug also completely abolished acquired resistance to a challenge infection with eggs when mice were injected s.c. with cyclosporin A (100 mg kg-1 day-1) around the time of challenge infection (Days -2, -1, 0, 1 and 2 relative to challenge). Such immunosuppressive effects of cyclosporin A on worm expulsion and protective immunity to reinfection were similar to those of another immunosuppressant, cyclophosphamide. As for the antiparasitic action of cyclosporin A against H. nana, a smaller number of cysticercoids developed from eggs in mice given cyclosporin A (100 mg kg-1 day-1) for 5 days beginning 1 day before infection, than in untreated controls.

The antiparasite effects of cyclosporin A: possible drug targets and clinical applications

1. The immunosuppressive drug cyclosporin A, and some of its nonimmunosuppressive derivatives, are potent inhibitors of a range of parasites of humans. 2. Cyclosporin A and the structurally unrelated immunosuppressant FK506 are known to act on T-lymphocytes as complexes with their binding proteins, cyclophilins and FKBPs, respectively. 3. Cyclophilins and FKBPs have been structurally identified in a number of parasites and, in some instances, are believed to play roles in the antiparasitic actions of these drugs. 4. Nonimmunosuppressive cyclosporins and FK506 derivatives may have clinical potential in certain parasitic diseases, especially malaria and schistosomiasis, and identification of the targets of these drugs in parasites may lead to development of novel chemotherapeutic agents.