The effect of interleukin-2 on parasitemia and myocarditis in experimental Chagas' disease

Correlation of plasma butyrylcholinesterase concentration with Acethylcholinesterase H353N polymorphism in the inflammatory response of Chagas disease patients

Trypanosoma cruzi infection triggers an intense production of pro-inflammatory cytokines mediated by T helper 1 lymphocytes, inducing the anti-inflammatory reflex of acetylcholine (ACh). The ACh concentration modulation is associated to the two major esterases, the acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). AChE H353N protein polymorphism is related to low Chagas chronic disease prognostic. In order to evaluate the correlation of plasmatic BuChE concentration and the presence of AChE H353N polymorphism in Chagas disease patients and healthy individuals, we studied two groups of individuals, one of 61 Chagas disease patients and another of 74 healthy individuals. Plasma concentration of BuChE was measured by the chemiluminescent method and AChE H353N polymorphism was investigated by PCR-RFLP and sequencing of the respective encoding AChE gene fragment. The BuChE concentration was statistically higher in Chagas disease patients, with no AChE genotype significant influence. AChE genotypes YT*A/YT*A, YT*A/YT*B and YT*B/YT*B, respectively, were expressed in 53 (86.88%), 7 (11.46%) and one (1.64%) chagasic patients, and in 68 (91.89%), 6 (8.10%) and none healthy individuals. BuChE activity may represent an important marker for chronic Chagas disease inflammatory process and prognostic. Lower BuChE concentration correlated with AChE YT*B allele, although without statistical power.

Characterization of cytokine production in murine Trypanosoma cruzi infection by in situ immunocytochemistry: lack of association between susceptibility and type 2 cytokine production

Cytokine production in the spleens of mice infected with the protozoan parasite Trypanosoma cruzi was analyzed in three models which differ in the outcome of the infection. Using immunocytochemical techniques to detect cytokine-producing cells, the production of type 1 [interleukin-2 (IL-2) and interferon (IFN)-gamma], type 2 (IL-4, IL-5, IL-10), inflammatory [tumor necrosis factor (TNF)-alpha, IL-1 alpha, IL-6] and regulatory (transforming growth factor-beta) cytokines were examined. With the exception of IL-4 and IL-5, cells producing all of the cytokines assayed were detected in both the resistant and susceptible models of T. cruzi infection. Cells producing IL-4 and IL-5 were not detected until later in infection in the resistant mice (> 34 days), at about the time animals of the susceptible strain succumb to the infection. Mice of the susceptible model showed a slight delay in the appearance of cells producing the type 1 cytokines IL-2 and IFN-gamma and an earlier appearance of TNF-producing cells, in comparison to resistant mice. Cells producing IL-2 or IL-10 were transient in their appearance in the spleen while cells producing IL-1, IL-4, IL-5, IL-6, IFN-gamma, TNF, or TGF-beta were first detectable in either the acute or post-acute stage of the infection and persisted up to 700 days post infection in two different resistant models of the infection. Cells producing IFN-gamma, TNF-alpha and TGF-beta were particularly numerous even very late in the infection. Double-staining techniques were used to show that the vast majority of the IFN-gamma-producing cells in the spleen were CD4-, CD8- alpha/beta TCR+T cells. This study confirms the transience of IL-2 production in the acute stage of T. cruzi infection and the persistent and simultaneous production of type 1 and type 2 cytokines during the late-acute and chronic stages of the infection. Susceptibility or resistance to T. cruzi infection does not associate with a Th2 pattern of cytokine production in the three models examined in this study. The overlapping pattern of type 1 and type 2 cytokine-producing cells in both the acute and chronic stages of T. cruzi infection demonstrates that longterm infections do not necessarily lead to a dominance of either type 1 or type 2 cytokine production.

Augmentation of suppressed antibody responses in mice during experimental Chagas' disease by T helper cells activated in a time-dependent mode of immunization

Mice infected with the protozoan parasite Trypanosoma cruzi, the causative agent of human Chagas' disease, develop immunosuppressed responses to heterologous antigens. Experiments were performed using infected mice in the acute stage of infection to assess immunoregulatory activities during induction of direct plaque-forming cells (DPFC) to sheep erythrocytes (SRBC), hapten-conjugated SRBC (TNP-SRBC), and horse erythrocytes (TNP-HRBC). Studies in vivo demonstrated that anti-SRBC responses were best enhanced when T. cruzi-infected mice were injected with primed T cells derived from normal or infected mice immunized four days previously. The presence of enhancing capacities for DPFC responses by T cells from T. cruzi-infected mice were also supported by experiments examining the hapten-carrier effect. Preimmunization of infected mice with SRBC or HRBC four days before injection of hapten-homologous (TNP-SRBC or TNP-HRBC) carrier resulted in markedly augmented anti-hapten antibody responses. These results show that functional help provided by T cells activated during priming and exposed to a challenge dose of antigen (SRBC) in a time-dependent mode can overcome the effect of immunosuppression in T. cruzi-infected mice.