Heligmosomoides bakeri antigen rescues CD4-positive T cells from glucocorticoid-induced apoptosis by Bcl-2 protein expression

Heligmosomoides bakeri infection in mice is associated with a dominant CD4(+) T-cell response and with the activity of natural Treg cells with CD4(+) CD25(+) phenotype. The polarization of Th2 T-cell phenotype and the increase in the CD4(+) CD25(+) T cell population are regulated by glucocorticoids that induce apoptosis in CD4(+) CD25(-) T cells and inhibit apoptosis in CD4(+) CD25(+) T cells. However, exposure of mice to H. bakeri antigen induces a high glucocorticoid concentration in serum and a reduction in the number of CD4-positive; CD4(+) CD25(-) and CD4(+) CD25(+) apoptotic T cells in mesenteric lymph node cells. In this study to evaluate the in vitro effect of the anti-apoptotic property of H. bakeri antigen on T cells, apoptosis of these cells was induced by glucocorticoids-dexamethasone (Dex). Excretory-secretory (ES) antigen of the nematode prevented Dex-induced apoptosis in CD4-positive T cells with CD4(+) CD25(-) and CD4(+) CD25(High) phenotype by Bcl-2 protein expression. Contrary to the effect on CD4-positive T cells, survival of CD8(+) T cells was not connected with expression of Bcl-2 protein. This suggest that H. bakeri antigen modulates CD4-positive T cell sensitivity to glucocorticoid-induced apoptosis by induction of Bcl-2 protein.

The role of TGF-β in mice infected with Heligmosomoides polygyrus

Hyporesponsiveness induced by Heligmosomoides polygyrus was quantified and the relationship between TGF-beta and inflammation was identified in BALB/c mice. The immune response and pathological changes modified by neutralization of TGF-beta were characterized in vivo. Nine and twelve days following infection, BALB/c mice were injected intraperitoneally with anti-TGF-beta (1,2,3) antibodies, isotype control antibodies or isosmotic solution. We assessed both Th1 and Th2 related cytokines production ex vivo and in vitro, IgA, the number of CD4+ cells, and eosinophils in the lamina propria and the villus : crypt ratio in the small intestine 6 weeks after infection. The pattern of cytokine production differed in the intestine, peritoneal fluid and serum. In mice infected with H. polygyrus the concentrations of IL-5, IL-12, TNF-alpha and IL-10 were raised in the intestine, but in serum the level of cytokines was diminished below the value observed in uninfected mice. The neutralization of TGF-beta converted the pattern of immune response induced by H. polygyrus. The elevation of cytokines in serum coincided with the reduction of cytokine concentration in the intestine or peritoneum. Neutralization of TGF-beta restored infiltration of eosinophils into the lamina propria of the intestine despite the low level of IL-5. We conclude that H. polygyrus infection suppresses the immune response through pathways involving TGF-beta production or activity and that the Th2 related immune response was not affected by neutralization.

[Apoptosis in the regulation of immune response in mice infected with Heligmosomoides polygyrus]

An unbalanced Th1 and Th2 cell subsets response was proposed as the main downregulating mechanisms operating in mice infected with H. polygyrus. During worm infections nonspecific inflammatory and specific immune reactions which might be regulated by apoptosis, coordinate the host protective response. The intensity of apoptosis and proliferation of lymphocytes, the concentration of Th1 and Th2 related cytokines were measured in BALB/c and C57BL6 mice on day 3, 6, 12, 24, 30 after infection with H. polygyrus. Mesenteric lymph nodes (MLN) and popliteal lymph nodes (PLN) lymphocytes underwent an apoptosis, with a different kinetics to the proliferation. Interleukine 5 and IL-6 concentrations increased on time when apoptosis was reduced. No changes in the level of IL-12 were related to intensity of proliferation or apoptosis in both examined strains of mice.

Environmental contamination with helminth infective stages implicated in water and foodborne diseases

The number of parasites increased followed the rapid growing of human population on the Earth. Zoonoses with other medical disorders such allergy accompanied to the parasitic infection are under very carefull investigation. A zoonosis can be transmitted from animals to humans in various ways, depending on life cycle of parasite, the kind of hosts and geographical distribution of species. There are many diseases that can be linked to transmission from not only domestic but also from wild animals (for example Trichinella, Echinococcus, Toxocara, Anisakis). The greater abundance of wild animals may contribute to the wider distribution and increasing prevalence of their parasites (red fox for Echinococcus multilocularis or Trichinella britovi). Zoonotic infections can be transmissed directly from environment when infective stages of parasite contamine water or food. Very important source of zoonoses in humans comes also from foodstuffs of animal origin. Environmental contamination with helminth infective stages needs regular indication for recognition of parasitic species under molecular data and improvement of effective measures to prevent of human zoonotic diseases.