Host nuclear abnormalities and depletion of nuclear antigens induced in Trichinella spiralis-infected muscle cells by the anthelmintic mebendazole.

Infection by the parasitic nematode Trichinella spiralis induces cell cycle repositioning (chronic suspension in apparent G2/M) and genetic reprogramming in differentiated mammalian skeletal muscle cells. These changes occur in association with dramatic enlargement of infected host cell nuclei (as large as 17 microm in diameter) and nucleoli. Nuclear antigens (NA) that colocalize with host chromatin have been detected by antibodies to T. spiralis antigens, but the functions of these NA are unresolved. Mebendazole (MBZ) preferentially binds parasite versus host beta-tubulins, is implicated in inhibiting secretion in nematodes and induces cytoplasmic changes in muscle cells infected with T. spiralis. These infected cell changes might be indirect via MBZ inhibition of parasite secretions. This effect would have implications for host/parasite interactions and was evaluated here. MBZ treatment of chronically infected mice caused: (1) a significant deformation of host nuclei and diminution of nucleoli by 4 and 6 days of treatment (dot), respectively; (2) a reduction of nuclear lamins A/C in infected cell nuclei that was concomitant with nuclear deformation; and (3) significant reductions in total RNA, general protein and acid phosphatase activity levels. These changes were associated with the depletion of NA from host nuclei detected by 4 dot. However, DNA content of infected cell nuclei was not detectably reduced and muscle gene expression was not reactivated. The cellular changes documented are likely to account for previously described cytoplasmic alterations induced by MBZ. Concomitant depletion of NA from infected cell nuclei suggests a role of these products in regulating nuclear functions of host cells.