Arginase activity is associated with fibrosis in experimental infection with Taenia crassiceps, but does not play a major role in resistance to infection.

Murine infection with Taenia crassiceps cysticerci is used as an experimental model for human and animal cysticercosis. In this infection parasites can be found associated with an inflammatory infiltrate enriched with macrophages. Experimental evidence exists supporting a role for either NO-producing classically activated (CAMΦ) or arginase- and CD301-expressing alternatively activated macrophages (AAMΦ) in T. crassiceps resistance. In both cell types, arginine is utilized as an important mediator in macrophage effector functions. To investigate whether there is an association between arginine availability, susceptibility to T. crassiceps and other parameters such as fibrosis, BALB/c mice were infected intraperitoneally with cysticerci and treated daily with the arginase inhibitor nor-NOHA or supplemented with l-arginine and followed for eight weeks. The numbers and developmental stages of parasites were evaluated as well as the presence of CD301+ AAMΦ, arginase activity and collagen deposition in the peritoneal membrane. Treatment with the arginase inhibitor or supplementation with l-arginine did not change the parasitic load or profile of the infection. However, the arginase inhibitor significantly decreased the deposition of collagen. These results suggest that arginase activity does not interfere with parasite control during experimental infection with T. crassiceps, but it is important for fibrosis in cysticercosis.

Treatment with dehydroepiandrosterone in vivo and in vitro inhibits reproduction, growth and viability of Taenia crassiceps metacestodes.

The aim of this work was to explore the effect of dehydroepiandrosterone (DHEA) on the establishment, growth and reproduction of the metacestode stage of the tapeworm Taenia crassiceps, both in vivo and in vitro. Administration of DHEA prior to infection in mice of both sexes reduced the parasite load by 50% compared with untreated mice. This protective effect was not associated with the immune response, since there was no effect of DHEA treatment on mRNA levels of IL-2, IFN-gamma, IL-4 or IL-10. DHEA treatment of infected mice increased androgen receptor expression in splenocytes of both sexes. Moreover, in vitro treatment of T. crassiceps with DHEA reduced reproduction, motility and viability in a dose- and time-dependent fashion. Results indicate that DHEA has strong negative direct modulatory effects on murine cysticercosis. We suggest the use of hormonal-analogues for protective purposes as a therapeutic approach to prevent murine cysticercosis.

Gonadectomy and progesterone treatment induce protection in murine cysticercosis.

The effects of progesterone on castrated mice of both sexes infected with Taenia crassiceps cysticerci were studied. Gonadectomy and treatment with progesterone before infection decreased parasite loads by 100% compared with intact uninfected mice. mRNA levels of IFN-gamma and IL-2 (typically associated to Th1-like profiles) were markedly decreased in infected gonadectomized (Gx) mice, whereas progesterone treatment of infected Gx mice did not affected its expression. mRNA levels of IL-4, and IL-10 (typically associated with Th2-like profiles) were reduced by gonadectomy, whereas restitution with progesterone did not affected this pattern in infected Gx progesterone-treated mice. Infection markedly induced expression of progesterone receptor isoform A in splenocytes of Gx mice (5-fold), whereas isoform B had no changes. Progesterone metabolism to dehydroepiandrosterone (DHEA) in Gx animals was increased 3-fold only in infected progesterone-treated uninfecteds of both sexes, but was not detectable in infected Gx progesterone-treated mice. Conversely, DHEA levels increased 100-fold in infected Gx progesterone-treated mice. However, androgen receptor expression in splenocytes of male mice showed a reduction by gonadectomy, and by infection, whereas in females AR expression showed no changes in the different mouse groups. These results suggest that progesterone, through its metabolism to DHEA, negatively affects the establishment, growth, and reproduction of Taenia crassiceps, by a mechanism that does not implicate a classic genomic pathway involving a nuclear androgen receptor.

Evaluation of the efficacy of albendazole against the larvae of Taenia solium in experimentally infected pigs, and kinetics of the immune response.

Cysticercosis, a disease of economic and public health importance, is caused by Cysticercus cellulosae, the metacestode stage of Taenia solium. Experimental induction of cysticercosis was achieved in young pigs by feeding an optimum dose of 20,000 T. solium (Indian strain) eggs after immunosuppression, to assess the effect of albendazole and development of the immune response to cysticercus antigens before and after treatment. Histopathological studies revealed the presence of cysticerei in liver, lungs and muscles. Treatment with albendazole at 15 mg kg-1 body weight daily for 30 days starting from day 0 or 15 days post-infection resulted in 100% cure rates. Increases in antibody titre to crude soluble extract and a Sephadek G-200 purified antigenic fraction of Cysticercus cellulosae were found on days 25, 40 and 55 post-infection in untreated pigs and those in which treatment started on day 15 post-infection, whereas no increase in antibody response was observed in pigs in which treatment started on day 0.