Schistosoma mansoni infection reduces the incidence of murine cerebral malaria.

BACKGROUND: Plasmodium and Schistosoma are two of the most common parasites in tropical areas. Deregulation of the immune response to Plasmodium falciparum, characterized by a Th1 response, leads to cerebral malaria (CM), while a Th2 response accompanies chronic schistosomiasis. METHODS: The development of CM was examined in mice with concomitant Schistosoma mansoni and Plasmodium berghei ANKA infections. The effect of S. mansoni egg antigen injection on disease development and survival was also determined. Cytokine serum levels were estimated using ELISA. Statistical analysis was performed using t-test. RESULTS: The results demonstrate that concomitant S. mansoni and P. berghei ANKA infection leads to a reduction in CM. This effect is dependent on infection schedule and infecting cercariae number, and is correlated with a Th2 response. Schistosomal egg antigen injection delays the death of Plasmodium-infected mice, indicating immune involvement. CONCLUSIONS: This research supports previous claims of a protective effect of helminth infection on CM development. The presence of multiple parasitic infections in patients from endemic areas should therefore be carefully noted in clinical trials, and in the development of standard treatment protocols for malaria. Defined helminth antigens may be considered for alleviation of immunopathological symptoms.

Methyl jasmonate induces cell death with mixed characteristics of apoptosis and necrosis in cervical cancer cells.

In the present study the effectiveness of methyl jasmonate (MJ) against cervical cancer cell lines was investigated. We show that MJ is cytotoxic to a range of cervical cancer lines including SiHa, CaSki and HeLa that carry human papillomavirus (HPV) DNA and wild type p53, and C33A that is negative for HPV and contains mutant p53. Primary human foreskin keratinocytes were almost resistant to the drug. Cytotoxicity of MJ was dose and time dependent, and associated mainly with the induction of cell death and to a less extent with inhibition of cell growth. Cell death induced by MJ displayed features characteristic to both apoptosis and necrosis, and was associated with different changes in the levels of p53, p21, bcl-2 and bax in the various cervical cancer lines. In conclusion, MJ a novel anticancer agent, acts via multiple pathways to induce death of cervical cancer cells, thus making it a promising candidate for treatment of cervical cancer.

Mitochondria-mediated ATP depletion by anti-cancer agents of the jasmonate family.

Jasmonates are plant stress hormones that induce suppression of proliferation and death in cancer cells, while being selectively inactive towards non-transformed cells. Jasmonates can overcome apoptotic blocks and exert cytotoxic effects on drug-resistant cells expressing p53 mutations. Jasmonates induce a rapid depletion of ATP in cancer cells. Indeed, this steep drop occurs when no signs of cell death are detectable yet. Experiments using modulators of ATP synthesis via glycolysis or oxidative phosphorylation suggest that the latter is the pathway suppressed by jasmonates. Consequently, the direct effects of jasmonates on mitochondria were evaluated. Jasmonates induced cytochrome c release and swelling in mitochondria isolated from cancer cells but not from normal ones. Thus, the selectivity of jasmonates against cancer cells is rooted at the mitochondrial level, and probably exploits differences between mitochondria from normal versus cancer cells. These findings position jasmonates as promising anti-cancer drugs acting via energetic depletion in neoplastic cells.

Cooperative cytotoxicity of methyl jasmonate with anti-cancer drugs and 2-deoxy-D-glucose.

The anti-cancer agent methyl jasmonate (MJ) acts in vitro and in vivo against various cancer cell lines, as well as leukemic cells from chronic lymphocytic leukemia (CLL) patients. Given the importance of multi-agent combinations in cancer chemotherapy, the purpose of this study was to identify super-additive combinations of MJ and currently-available chemotherapeutic drugs. We identified such cooperative effects in six cell lines arising from different major types of malignancies, i.e., breast, lung, prostate and pancreas carcinomas as well as leukemia. The chemotherapeutic drugs tested were adriamycin, taxol, BCNU and cisplatin. For instance, MJ exhibited strong cooperative effects with BCNU in MIA PaCa-2 pancreatic carcinoma cells. Furthermore, MJ enhanced significantly (pV=0.028) the anti-leukemic effect of adriamycin in vivo, in a CLL mouse model. Finally, MJ cooperated with the glycolysis inhibitor 2-deoxy-D-glucose in inducing death of several types of carcinoma cells. We conclude that administration of MJ with common chemotherapeutic drugs and glycolysis inhibitors bears a promise for effective anti-cancer therapy.

Jasmonates: novel anticancer agents acting directly and selectively on human cancer cell mitochondria.

We reported previously that jasmonates can kill human cancer cells. Many chemotherapeutic drugs induce mitochondrial membrane permeability transition, membrane depolarization, osmotic swelling, and release of cytochrome c, involving the opening of the permeability transition pore complex (PTPC). Because jasmonates exert their cytotoxic effects independent of transcription, translation, and p53 expression, we hypothesized that these compounds may act directly on mitochondria. Mitochondrial membrane depolarization was determined by flow cytometry, and cytochrome c release by Western blotting. Mitochondria were isolated by mechanical lysis and differential centrifugation. Cytotoxicity was measured by a tetrazolium-based assay, and mitochondrial swelling by spectrophotometry. Jasmonates induced membrane depolarization and cytochrome c release in intact human cancer cell lines. Jasmonates induced swelling in mitochondria isolated from Hep 3B hepatoma cells, but not in mitochondria isolated from 3T3 nontransformed cells or from normal lymphocytes, in a PTPC-mediated manner. Methyl jasmonate induced the release of cytochrome c from mitochondria isolated from cancer cell lines in a PTPC-mediated manner, but not from mitochondria isolated from normal lymphocytes. A correlation was found between cytotoxicity of methyl jasmonate and the percentage of leukemic cells in the blood of patients with chronic lymphocytic leukemia (CLL). Jasmonates induced membrane depolarization in CLL cells, and swelling and release of cytochrome c in mitochondria isolated from these cells. In conclusion, jasmonates act directly on mitochondria derived from cancer cells in a PTPC-mediated manner, and could therefore bypass premitochondrial apoptotic blocks. Jasmonates are promising candidates for the treatment of CLL and other types of cancer.

Determination of idiotype-specific T cells in idiotype-vaccinated mice.

Immunoglobulin idiotypes (Id) of malignant B lymphocytes and plasma cells are tumor-specific antigens that were extensively used in immunotherapy studies. The effector mechanisms, involved in resistance to tumor following Id vaccination, are a controversial issue. Since cell-mediated responses, rather than antibody responses, constitute powerful effectors against tumors, recent studies focused on the generation of Id-specific T cells. Traditional methods for assessment of cellular responses in murine models of Id vaccination are inadequate because of their low sensitivity and because they do not determine actual frequency of antigen-reactive T cells. Here, we use the highly sensitive enzyme-linked immunospot (ELISPOT) assay for enumeration of interferon gamma (IFN-gamma)-secreting cells in Id-vaccinated mice. Our experimental model consists of the murine B-lymphocyte tumor 38C-13, which expresses surface IgM, and the plasma cell tumor D2, which secretes IgM with idiotypic specificity identical to that of 38C-13. Vaccination of mice with purified 38C-13 IgM induced resistance to 38C-13 as well as to D2 tumor cells. Although immunized mice produced high levels of anti-Id antibodies that bound to 38C-13 cells, no binding of antibodies to D2 occurred, suggesting that cellular mechanisms mediated resistance to the plasma cell tumor. ELISPOT assays revealed that immunization induced a significant increase in the frequency of Id-specific IFN-gamma-secreting T cells. Depletion of T cell subsets demonstrated that both CD4(+) and CD8(+) T cells were involved in the response to Id. This is the first report on application of the ELISPOT assay for enumeration of Id-reactive T cells in a murine model of Id vaccination, providing a tool to study Id-specific T cell responses and to evaluate the efficacy of Id vaccines.