Cytokine,Antibody and Proliferative Cellular Responses Elicited by Taenia solium Calreticulin upon Experimental Infection in Hamsters

Taenia solium causes two diseases in humans, cysticercosis and taeniosis. Tapeworm carriers are the main risk factor for neurocysticercosis. Limited information is available about the immune response elicited by the adult parasite, particularly the induction of Th2 responses, frequently associated to helminth infections. Calreticulin is a ubiquitous, multifunctional protein involved in cellular calcium homeostasis, which has been suggested to play a role in the regulation of immune responses. In this work, we assessed the effect of recombinant T. solium calreticulin (rTsCRT) on the cytokine, humoral and cellular responses upon experimental infection in Syrian Golden hamsters (Mesocricetus auratus). Animals were infected with T. solium cysticerci and euthanized at different times after infection. Specific serum antibodies, proliferative responses in mesenteric lymph nodes and spleen cells, as well as cytokines messenger RNA (mRNA) were analyzed. The results showed that one third of the infected animals elicited anti-rTsCRT IgG antibodies. Interestingly, mesenteric lymph node (MLN) cells from either infected or non-infected animals did not proliferate upon in vitro stimulation with rTsCRT. Additionally, stimulation with a tapeworm crude extract resulted in increased expression of IL-4 and IL-5 mRNA. Upon stimulation, rTsCRT increased the expression levels of IL-10 in spleen and MLN cells from uninfected and infected hamsters. The results showed that rTsCRT favors a Th2-biased immune response characterized by the induction of IL-10 in mucosal and systemic lymphoid organs. Here we provide the first data on the cytokine, antibody and cellular responses to rTsCRT upon in vitro stimulation during taeniasis.     

The role of the idiotypic network in the induction of experimental systemic lupus erythematosus

Systemic lupus erythematosus (SLE) has been induced in C3H.SW mice by their immunization with a human monoclonal anti-DNA antibody that bears a common idiotype-16/6 Id. Following immunization, high levels of murine anti-16/6 and anti-anti-16/6 antibodies were detected in the sera of the immunized mice. Elevated titers of autoantibodies reacting with ssDNA, dsDNA, poly(I), poly(G), RNP, Ro, and La were also observed. The serological findings were associated with significant proteinuria, leukopenia, and elevated erythrocyte sedimentation rate. Immune complex deposition in the glomerular mesangium and sclerosis of the glomeruli were demonstrated. To study whether or not anti-idiotype antibodies are involved in the induction of the disease, a murine monoclonal antibody against the 16/6 Id was prepared and injected into C3H.SW mice. The anti-16/6 Id antibody induced experimental SLE similarly to the 16/6 Id with an accelerated kidney pathology. A study performed on different mouse strains indicated that the susceptibility to the induction of SLE by the 16/6 Id is strain dependent and directly correlates to their ability to produce anti-16/6 Id specific antibodies.     

Taenia solium: Immune response against oral or systemic immunization with purified recombinant calreticulin in mice

Recombinant functional Taenia solium calreticulin (rTsCRT) confers different degrees of protection in the experimental model of intestinal taeniosis in hamsters. The aim of this study was to evaluate the immune response induced after oral or systemic immunization with an electroeluted rTsCRT in BALB/c mice. Oral immunization elicited high fecal IgA and the production of IL-4 and IL-5 by mesenteric lymph node cells after in vitro stimulation with rTSCRT, indicating a Th2 response. Mice subcutaneously immunized produced high amounts of serum IgG, being IgG1 (Th2-related) the predominant isotype, while in vitro stimulated spleen cells synthesized IL-4, IL-5 and also IFN-γ, indicating a mixed Th1/Th2 cellular response after systemic immunization. Our data show that purified rTsCRT induces polarized Th2 responses after oral immunization of mice, a common characteristic of protective immunity against helminths and, consequently, a desirable hallmark in the search for a vaccine.     

Cloning, characterization, and functional expression of Taenia solium calreticulin

Calreticulin is an endoplasmic reticulum protein involved in the homeostasis of intracellular Ca++ and other physiological processes. A complementary DNA clone containing the complete coding sequence of Taenia solium calreticulin (TsCRT) was isolated and characterized. Recombinant TsCRT was expressed in bacteria as a 50-kDa protein that specifically bound calcium when tested in a radioassay. The deduced amino acid sequence has 47-50% identity with other reported calreticulins. Poor recognition of TsCRT by human and pig sera with confirmed cysticercosis discourages its use for diagnosis of the disease. However, further characterization and localization studies could provide insights into the role of TsCRT in T. solium physiology and host-parasite interactions.     

Differential expression of calreticulin in developmental stages of Taenia solium

Taenia solium, a cestode that causes neurocysticercosis and taeniasis in humans, has a complex life cycle. The adult tapeworm develops in the intestine of human beings and is also responsible for neurocysticercosis, which is caused by the metacestode or cysticercus that develops in the brain. Recently, we have cloned the coding region for T. solium calreticulin (TsCRT) as a functional Ca(2+)-binding protein. Calreticulin is a ubiquitous protein involved in cellular Ca2+ homeostasis and protein folding. These important functions affect several aspects of cell physiology. To explore the expression of TsCRT during the T. solium life cycle, we used a specific polyclonal antibody raised against recombinant TsCRT to localize this protein by immunolabeling techniques. In sections of cysticerci obtained from swine muscle, as well as of adult tapeworms obtained after infection of hamsters with cysticerci, TsCRT was preferentially localized in tegumentary and muscle cytons of the suckers and rostellum. In mature proglottids obtained from infected humans, positive staining was observed in spermatogonia, ovogonia, uterine epithelium, and cells of the vas deferens. In the gravid uterus, the morula and early stage embryos were highly positive to TsCRT. However, expression diminished as embryonic development progressed and was absent in fully developed oncospheres that were surrounded by an embryophore. A similar down regulation was observed during spermatogenesis. Although early spermatocytes showed a high expression of TsCRT, mature spermatozoa present in the vas deferens were completely negative. These data indicate that calreticulin expression is spatially and temporally regulated during development of T. solium, especially during germ cell development and embryogenesis. In addition, these original images illustrate, for the first time, these processes at a histological level.     

Increased apoptosis in patients with major depression: A preliminary study.

Apoptosis is a programmed cell death that can be observed in normal cells. Major depression poses a combination of a depressed and destructive autoimmune reaction. We measured apoptosis in the PBLs of seven patients with major depression and in age- and sex-matched controls. We observed significantly increased apoptosis in the PBLs of depressive patients (p < 0.05). These preliminary results could contribute to an understanding of the interactions of the CNS with the immune system, which could lead to the increased vulnerability of the CNS in depressive disorders. Further studies are needed to establish these results.     

Characterization of alkaline phosphatase from primordial germ cells and ontogenesis of this enzyme in the mouse

The physical characteristics of nonspecific alkaline phosphatase (ALP) from both mouse primordial germ cells (PGCs) and gonads were compared with corresponding samples from other organs at different developmental stages. Combining a cytochemical approach with polyacrylamide gel electrophoresis and the use of specific inhibitors, as well as neuraminidase treatment, heat sensitivity tests, and molecular-mass criteria, it was found that only one ALP isoenzyme was present in all organs up to day 14 of gestation. Distinct ALP isoenzymes first appeared in the small intestine on day 15 and, thereafter, in all other tissues except the gonads. In these organs, the embryonal ALP isoenzyme seemed to be retained until adulthood. Although the placenta had a different ALP isoenzyme than the embryo at all stages, this isoenzyme was found to be similar to that in the maternal decidual tissues. Therefore, we conclude that the mouse embryo only expresses one type of ALP that can be considered "embryonal", regardless of the organ in which it first appears, and that this ALP is conserved in the gonads.     

Possible involvement of cyclooxygenase products in the actions of platelet-activating factor and of lipoxygenase products in the vascular effects of epinephrine in perfused rat liver

Platelet-activating factor (PAF) stimulates glycogenolysis and induces vasoconstriction in perfused rat liver. The effect of PAF was rapid but transient and it was blocked by indomethacin and bromophenacyl bromide which suggests a role of cyclooxygenase metabolites in its action. The homologous desensitization of glycogenolysis produced by PAF and the sensitivity of its actions to inhibitors of cyclooxygenase and phospholipase A2 markedly differentiate the mechanism of action of this agent with that of alpha 1-adrenergic agents, vasopressin or angiotensin II. No effect of PAF in isolated hepatocytes was observed which suggest that cells other than hepatocytes could be involved in its action in perfused liver. In addition nordihydroguaiaretic acid and bromophenacyl bromide abolished the vascular effect (but not the glycogenolysis) produced by epinephrine which suggest a role for lipoxygenase products in this effect.