| Tuberculosis(TB) is one of greatest public health challenges in the world and remains the leading cause of death among infectious diseases. One third of the world's population is infected with it. The rise in the number of individuals with compromised immune systems is one of the major reasons that increase the rate of reactivation of TB. As a result ,the percentage that progresses to disease is increasing. In addition to the increasing incidence of TB, there have been a global emergence of drug-resistant strains and a long stagnant period in tuberculosis drug development, posing a threat to existing therapeutic possibilities . Hence, new prophylactic and therapeutic strategies are required for the control of TB.The patients with TB frequently fall into imbanlance between Thl/Th2-like cytokines due to a shift towards a Th2-dominant condition. Such a pathological condition could depress the cleaning of pathogen .And now , it is well known that a Thl immune response conveys protection against infection with Mycobacterium tuberculosis ,while Th2 immune response is associated with impaired immunological function.Unmethylated CpG motifs within synthetic oligodeoxynucleotides (ODN) can activate vertebrate immune system contributing to host defense mechanisms that could recognize invading microbial agents .CpG motifs can stimulate B cells, NK cells, T cells, and macrophages to secrete Thl-like cytokines ,e.g Interferon(EFN)-gamma ,interleukin(IL)-12,IL-2 . A number of studies indicated that CpG could switch on T helper 1 (Thl) immunity and a Thl-dominated cytokine profile .Indeed, protective Thl-biased immune responses could be induced by the administration of CpG ODN in animal models of Listeria and Leishmania infections .At present ,the useof CpG ODN in imunotherapy for tuberculosis is in an infancy stage .And some questions are to be elicidated such as the effect of CpG ODN on Thl/Th2 immune response in peripheral blood mononuclear cells (PBMC) from patients with tuberculosis, the molecular mechanism of immune protection induced by CpG ODN .Purpose1.Observe the imbanlance of Thl/Th2 immunity and the regulation of CpG ODN on Thl/Th2 immunity in PBMC from patients with pulmonary TB.2.Investigate the protective effect of CpG ODN in mice infected with mycobacterium tuberculosis.3.Detect the regulatory effects of CpG ODN on Thl/Th2 immunity in mice infected with mycobacterium tuberculosis.MethodsPart one Venous blood samples were obtained from 20 healthy donors and from 20 HIV-seronegative patients with pulmonary tuberculosis prior to receiving antituberculosis therapy . PBMC were isolated from blood samples by differential centrifugation over Ficoll-Paque . PBMC were suspended in medium (RPMI 1640 ) with or without lOug of tuberculin purified protein derivative (PPD). PBMC were harvested after a 48h incubation at 37癈 in 5% C02, and the expression of EFN-gamma mRNA and IL-lOmRNA were analyzed by reverse transcription-polymerase chain reaction(RT-PCR), Meanwhile the proportions of CD4+/CD8+T lymphocytes producing EFN-gamma or EL-4 in PBMC was assessed by flow cytometry.Part two The every specimens of PBMC from 20 healthy donors and from 20 HIV-seronegative patients with pulmonary tuberculosis were divided into 4 parts , and cultured with none stimulator, PPD, CpG ODNs , CpG ODNs plus PPD separatively. The PBMC were harvested after a 48h incubation at 37癈 in 5% CO2, and the expression of IFN-gamma mRNA , EL-10 mRNA and EL-12 mRNA were analyzed with a real-time PCR techniquePart three 96 female BALB/c mice were randomized into 4 groups, namely CpG ODN treatment (A group),control ODN treatment (B group), infectious control (C group) and healthy control (D group) (n=24). A group and B group were treated once with CpG ODN or control ODN (30 u g/mouse) intraperitoneally 2 weeks before infection with mycobacterium tuberculosis. 1 X 106 bacili in a volume of 300 u 1 saline were injected into the tail vein of mice from A group ,B group and C group.The 12 mice from each group were sacrificed at 3 weeks postin...
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