Health-promoting properties of common herbs.
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Herbs have been used as food and for medicinal purposes for centuries. Research interest has focused on various herbs that possess hypolipidemic, antiplatelet, antitumor, or immune-stimulating properties that may be useful adjuncts in helping reduce the risk of cardiovascular disease and cancer. In different herbs, a wide variety of active phytochemicals, including the flavonoids, terpenoids, lignans, sulfides, polyphenolics, carotenoids, coumarins, saponins, plant sterols, curcumins, and phthalides have been identified. Several of these phytochemicals either inhibit nitrosation or the formation of DNA adducts or stimulate the activity of protective enzymes such as the Phase II enzyme glutathione transferase (EC 2.5.1.18). Research has centered around the biochemical activity of the Allium sp. and the Labiatae, Umbelliferae, and Zingiberaceae families, as well as flaxseed, licorice root, and green tea. Many of these herbs contain potent antioxidant compounds that provide significant protection against chronic diseases. These compounds may protect LDL cholesterol from oxidation, inhibit cyclooxygenase and lipoxygenase enzymes, inhibit lipid peroxidation, or have antiviral or antitumor activity. The volatile essential oils of commonly used culinary herbs, spices, and herbal teas inhibit mevalonate synthesis and thereby suppress cholesterol synthesis and tumor growth. (+info)
Susceptibility to myocarditis is dependent on the response of alphabeta T lymphocytes to coxsackieviral infection.
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Viral myocarditis is an important cause of heart failure and dilated cardiomyopathy. T lymphocytes are implicated in myocardial damage in murine models of coxsackievirus B3 (CVB3) myocarditis. We used knockout mice lacking CD4 (CD4(-/-)), CD8 (CD8(-/-)), both coreceptors (CD4(-/-)CD8(-/-)), or the T-cell receptor beta chain (TCRbeta(-/-)) to address the contribution of T-cell subpopulations to host susceptibility to CVB3 myocarditis. Severity of disease was magnified in CD8(-/-) mice but attenuated in CD4(-/-) mice, consistent with a pathogenic role for CD4(+) lymphocytes. Elimination of both CD4 and CD8 molecules from T lymphocytes by genetic knockout better protected mice from myocarditis, demonstrating that both CD4(+) and CD8(+) T cells contribute to host susceptibility. The same benefit occurred in TCRbeta(-/-) mice, with prolonged survival and minimal myocardial disease observed after CVB3 infection. Elevated interferon-gamma and decreased tumor necrosis factor-alpha expression are associated with attenuated myocardial damage in CD4(-/-)CD8(-/-) mice. These results show that the presence of TCRalphabeta(+) T cells enhances host susceptibility to myocarditis. The severity of myocardial damage and associated mortality are dependent on the predominant T-cell type available to respond to CVB3 infection. One mechanism by which CD4(+) and CD8(+) T-cell subsets influence the pathogenesis of myocarditis may involve specific cytokine expression patterns. (+info)
Prenatal immunotoxicant exposure and postnatal autoimmune disease.
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Reports in humans and rodents indicate that immune development may be altered following perinatal exposure to immunotoxic compounds, including chemotherapeutics, corticosteroids, polycyclic hydrocarbons, and polyhalogenated hydrocarbons. Effects from such exposure may be more dramatic or persistent than following exposure during adult life. For example, prenatal exposure to the insecticide chlordane or to the polycyclic aromatic hydrocarbon benzo[(italic)a(/italic)]pyrene produces what appears to be lifelong immunosuppression in mice. Whether prenatal immunotoxicant exposure may predispose the organism to postnatal autoimmune disease remains largely unknown. In this regard, the therapeutic immunosuppressant cyclosporin A (CsA) crosses the placenta poorly. However, lethally irradiated rodents exposed to CsA postsyngeneic bone marrow transplant (i.e., during re-establishment of the immune system) develop T-cell-mediated autoimmune disease, suggesting this drug may produce a fundamental disruption in development of self-tolerance by T cells. The environmental contaminant 2,3,7, 8-tetrachlorodibenzo-(italic)p(/italic)-dioxin (TCDD) crosses the placenta and produces fetal thymic effects (italic)in vivo(/italic) similar to effects of CsA in fetal thymic organ culture, including inhibited thymocyte maturation and reduced expression of thymic major histocompatability complex class II molecules. These observations led to the suggestion that gestational exposure to TCDD may interfere with normal development of self-tolerance. Possibly supporting this hypothesis, when mice predisposed to development of autoimmune disease were treated with TCDD during gestation, postnatal autoimmunity was exacerbated. Similar results have been reported for mice exposed to diethylstilbestrol during development. These reports suggest that prenatal exposure to certain immunotoxicants may play a role in postnatal expression of autoimmunity. (+info)
The role of the immune system in hexachlorobenzene-induced toxicity.
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Hexachlorobenzene (HCB) is a persistent environmental pollutant. The toxicity of HCB has been extensively studied after an accidental human poisoning in Turkey and more recently it has been shown that HCB has immunotoxic properties in laboratory animals and probably also in man. Oral exposure of rats to HCB showed stimulatory effects on spleen and lymph node weights and histology, increased serum IgM levels, and an enhancement of several parameters of immune function. Moreover, more recent studies indicate that HCB-induced effects in the rat may be related to autoimmunity. In Wistar rats exposed to HCB, IgM antibodies against several autoantigens were elevated; in the Lewis rat, HCB differently modulated two experimental models of autoimmune disease. Oral exposure of rats to HCB induces skin and lung pathology in the rat. Recently several studies have been conducted to investigate whether these skin and lung lesions can be related to HCB-induced immunomodulation, and these studies will be discussed in this review. HCB-induced skin and lung lesions probably have a different etiology; pronounced strain differences and correlation of skin lesions with immune parameters suggest a specific involvement of the immune system in HCB-induced skin lesions. The induction of lung lesions by HCB was thymus independent. Thymus-dependent T cells were not likely to be required for the induction of skin lesions, although T cells enhanced the rate of induction and the progression of the skin lesions. No deposition of autoantibodies was observed in nonlesional or lesional skin of HCB-treated rats. Therefore, we concluded that it is unlikely that the mechanism by which most allergic or autoimmunogenic chemicals work, i.e., by binding to macromolecules of the body and subsequent T- and B-cell activation, is involved in the HCB-induced immunopathology in the rat. Such a thymus-independent immunopathology is remarkable, as HCB strongly modulates T-cell-mediated immune parameters. This points at a very complex mechanism and possible involvement of multiple factors in the immunopathology of HCB. (+info)
Persistent changes in the immune system 4-10 years after ABMT.
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The aim of the present study was to investigate whether the early changes in the immune system observed after ABMT would persist over years. Eighty-five patients with malignant lymphoma were treated with ABMT in Norway from 1987 until 1993. Of the 46 patients in CR by 1997, 36 were enrolled in our study. Median time from ABMT was 5 years (4-10 years). Immunophenotyping showed an increase in the median number of B cells (0.35 x 109/l in patients vs 0.28 x 109/l in controls), and a decrease in T cells (1.08 vs 1.35 x 109/l). Furthermore, a lower median count of CD4+ T cells (0.54 x 109/l in patients vs0.87 x 109/l in controls) resulted in reduced CD4/CD8 ratios (0.8 in patients vs 1.6 in controls). The subgroup of CD4+ T cells expressing the 'naive' phenotype CD45RA was 19.5% in patients vs 38% in controls. In contrast, the fraction expressing the 'memory' phenotype CD45RO was higher in the ABMT group (76% vs 54%). When stimulated, larger fractions of CD3+CD4+ cells in patients produced IFN-gamma (32% vs 16%) or IL-4 (7% vs 1%) compared to controls; thus a differentiation into the functionally separate subgroups Th1 and Th2, with a dominant Th2 response. Our data further suggest that the decrease in CD4+ T cell counts and the imbalance between CD45RA+ and CD45RO+ subsets persists 4-10 years after ABMT. (+info)
Evaluation of multivariate statistical methods for analysis and modeling of immunotoxicology data.
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In immunotoxicology, the critical functions of the immune system (host resistance to infection and neoplasia) cannot be measured directly in humans. It is theoretically possible to predict changes in host resistance based on changes in immunological functions known to mediate host resistance. However, quantitative predictive models of this type have not yet been achieved in humans or in animal models. Multivariate statistical methods were developed for analysis and modeling of the effects of several explanatory variables on a dependent variable, and they seem well suited for attempts to predict host resistance changes caused by changes in immunological parameters. However, these methods were developed with the assumption that all variables can be measured for each experimental subject. For a number of reasons, this generally cannot be done in comprehensive immunotoxicology evaluations. In the present study, the suitability of multivariate methods for analysis of variables measured in different experiments was examined, using a limited data set consisting of immunological parameters that could all be measured for each mouse. Analysis was done on the original data set and test data sets produced by randomizing data within dosage groups. This was done to simulate the random pairing of data that would occur if measurements were obtained from different sets of mice in different experiments. Statistical theory indicates that randomization will disrupt the correlation matrices that are central in multivariate analyses. However, the present results demonstrate empirically that for at least one immunotoxicant (dexamethasone), remarkably similar multivariate models were obtained for the original and 109 randomized data sets. In contrast, the randomized data sets produced substantially different multivariate models when data obtained with a different immunotoxicant (cyclosporin A) were analyzed. The major difference between the two data sets was that dexamethasone strongly and dose-responsively suppressed many more parameters than did cyclosporin A. Additional work is needed to determine whether there are consistent criteria that could be used to identify immunotoxicology data sets, which would be amenable to multivariate analysis. (+info)
Prevention of UVB-induced immunosuppression in mice by the green tea polyphenol (-)-epigallocatechin-3-gallate may be associated with alterations in IL-10 and IL-12 production.
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UV exposure of the skin, particularly UVB (290-320 nm), causes adverse biological effects, including alterations in cutaneous immune cells, photoaging and photocarcinogenesis. Several studies have shown that polyphenolic compounds isolated from green tea afford protection against UVB-induced inflammatory responses and photocarcinogenesis in murine models. In this study we show that topical application of (-)-epigallocatechin-3-gallate (EGCG) (3 mg/mouse), a major polyphenolic component of green tea, before a single low dose UVB exposure (72 mJ/cm(2)) to C3H/HeN mice prevented UVB-induced inhibition of the contact hypersensitivity response and tolerance induction to the contact sensitizer 2, 4-dinitrofluorobenzene. Topical application of EGCG before UVB exposure reduced the number of CD11b+ monocytes/macrophages and neutrophils infiltrating into skin inflammatory lesions, which are considered to be responsible for creating the UV-induced immunosuppressive state. In addition, application of EGCG before UVB exposure decreased UVB-induced production of the immunomodulatory cytokine interleukin (IL)-10 in skin as well as in draining lymph nodes (DLN), whereas production of IL-12, which is considered to be a mediator and adjuvant for induction of contact sensitivity, was found to be markedly increased in DLN when compared with UVB alone-exposed mice. Taken together, our data demonstrate that EGCG protects against UVB-induced immunosuppression and tolerance induction by: (i) blocking UVB-induced infiltration of CD11b+ cells into the skin; (ii) reducing IL-10 production in skin as well as in DLN; (iii) markedly increasing IL-12 production in DLN. Protection against UVB-induced immunosuppression by EGCG may be associated with protection against UVB-induced photocarcinogenesis. (+info)
Ontogeny of the immune system of the brushtail possum, Trichosurus vulpecula.
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The numbers and distribution of T and B cells in the thoracic thymus, spleen and intestinal tissue and the proliferation of T lymphocytes were examined during pouch life and in the adult to determine when the developing brushtail possum reaches immunological maturity. CD3-positive cells were observed in the thoracic thymus at day 2 post-partum indicating that the thymus produces T lymphocytes at or soon after birth. By day 25 the thymus was fully populated with CD3-positive T lymphocytes and they were observed in distinct regions of the cortex and medulla. By day 48 post-partum, B and T lymphocytes were identified in the follicles and parafollicular areas of the spleen. Although the numbers of T and B cells in the spleen increased significantly from day 25 to day 100 post-partum (P < 0.005), fewer cells were present at day 150 post-partum than in the adult (P < 0.05). Peyer's patches were not observed in the intestines up to day 73 post-partum. However, both T and B cells were observed in the intestinal lymph nodes. Although the T lymphocytes at weaning showed a proliferative response, the response was not as great as that observed in the adult possum. Thus, the immune system of the possum is not fully developed at weaning but continues its development after pouch life. (+info)