Doxycycline hyclate: A schistosomicidal agent in vitro with immunomodulatory potential on granulomatous inflammation in vivo.

We investigated the effect in vitro and in vivo of doxycycline hyclate (Dx), a broad-spectrum antibiotic inhibitor of matrix metaloproteinases (MMPs), on adult Schistosoma mansoni worms and granulomatous liver inflammation in infected mice. Adult S. mansoni worms in culture treated with different concentrations of Dx (50-180 µg/mL) were studied for eight days to assess its morphology, eggs production, and mortality. Uninfected mice and those infected with S. mansoni, untreated and treated with praziquantel (Pz; 200 mg/kg) or Dx (50 mg/kg), were evaluated for 60 days. Our results indicated that Dx induced dose-dependent integumentary lesions (bubbles, tubercle collapse, spicule disappearance, peeling, and erosion), reduced mating rate and eggs-laying in adult S. mansoni worms. The effective lethal dose required to kill 50% of worms was 112.0 µg/mL Dx (DL50). In mice, S. mansoni infection induced hepatomegaly, intense IL-4, IL-10, TNF-α and TGF-ß production, granulomatous inflammation and hepatic glycogen depletion. The number and size of the granulomas was similar in untreated and Dx-treated animals. Untreated animals showed a predominance of productive granulomas, and intense MMP-2 and MMP-9 activities. Dx-treated mice exhibited a significant increase in IL-4 levels, tissue inflammation, proportion of involutive granulomas, and hepatic collagenogenesis, as well as attenuated MMP-2 and MMP-9 activities. Our findings indicated that Dx is toxic to adult S. mansoni worms in vitro. However, in vitro beneficial effects were not reproduced in vivo, since Dx treatment increased liver granulomatous inflammation and collagenogenesis in S. mansoni-infected mice by a process potentially associated with Dx-mediated hepatic MMP-2 and MMP-9 inhibition.

Biological and immunological activity of new imidazolidines against adult worms of Schistosoma mansoni.

The only drug available for treating schistosomiasis is praziquantel, however there are already reports of resistance to its use in treatment, making it necessary to search and develop new compounds to combat schistosomiasis. We tested, in vitro, two new products, Laboratório de Planejamento de Síntese de Fármacos (LPSF)/5-(4-chloro-benzylidene-3-(4-nitrebenzyl)-4-thioxo-imidazolidin-2-one (RZS-2) and LPSF/5-(4-fluoride-benzylidene-3-(4-nitrebenzyl)-4-thioxo-imidazolidin-2-one (RZS-5) imidazolidines, against adult worms of Schistosoma mansoni. Efficacy and safety of these compounds were analyzed through IC50 cytotoxicity, immune response and cell viability tests. At different concentrations ranging from 40-640 microM, the imidazolidines produced motor abnormalities, inhibition of pairing and oviposition and mortality within 24 h at the higher concentrations. Although not triggering changes in IFN-gamma and IL-10, LPSF/RZS-2 and LPSF/RZS-5 induced production of nitric oxide and showed similar behavior to praziquantel in the cell death test.

The immune response to a schistosomacide, amoscanate. I. Serum antibody responses.

A potent antischistosomal drug, Amoscanate, was found to be immunogenic to mice and Cebus apella monkeys. The drug was readily haptenated to proteins under relatively mild conditions. The Amoscanate-protein conjugates were observed to be immunogenic when injected into the footpads of several strains of mice. However, such protein conjugates were not found to raise IgE antibody to the drug in high-responder strains using several procedures. When the formulated drug (dissolved in oil) was fed to CD 1 mice, a rise in serum antibody against the drug was noted 1 week following the primary dose. This is preliminary evidence that the drug, or a cross-reactive metabolite, becomes covalently bound to proteins in vivo. Cebus apella monkeys fed the drug exhibited a rise in anti-Amoscanate antibody one month after a second oral dose. These data suggest that the immunogenicity of Amoscanate is readily detected; furthermore, since there is no lasting immunity to schistosomiasis, thus necessitating multiple administration of the drug, the possibility that serum antibody titers to Amoscanate may interfere with its therapeutic efficacy cannot be overlooked.

The immune response to a schistosomacide, amoscanate. II. Cell-mediated immune responses.

A potent antischistosomal drug, Amoscanate, was found to induce vigorous serum antibody responses when either fed or administered parenterally as a drug-protein conjugate. Because of preliminary evidence that the drug could bind covalently to proteins in vivo, we decided to investigate the possibility that the drug could act as a contact sensitizing agent like DNCB. It was found that Amoscanate could induce a delayed-type hypersensitivity (DTH) response when painted on the shaved skin of guinea pigs. Moreover, the type of DTH response elicited was found to be cutaneous basophilic hypersensitivity (CBH). The significance of these findings are discussed.