Splenic PGE2-releasing macrophages regulate Th1 and Th2 immune responses in mice treated with heat-killed BCG

Hosts infected with low doses of mycobacteria develop T helper cell type 1 (Th1) immunity, but at relatively higher doses, a switch to Th2 immunity occurs. Prostaglandin E2 (PGE2) is a proposed mediator of the Th1-to-Th2 shift of immune responses, and mycobacterial products induce PGE2-releasing macrophages (PGE2-M?) in the mouse spleen in a dose-dependent manner. Splenic PGE2-M ? from Balb/c mice, given 0.01 or 1 mg heat-killed (HK) Mycobacterium bovis bacillus Calmette-Guerin (BCG) intraperitoneally (i.p.), were characterized by the ex vivo release of PGE2 (>10 ng/10(6) cells), cytokine production, and expression of PGG/H synthase (PGHS)-1, PGHS-2, cytosolic PGE synthase (PGES), and microsomal PGES-1. At Day 14 after the treatment, mice treated with 1 mg, but not 0.01 mg, BCG had increased levels of PGHS-2+ PGE2-M?, total serum immunoglobulin E (IgE), and serum IgG1 antibodies (Th2 responses) against heat shock protein 65 and purified protein derivative. Cultures of spleen cells isolated from these mice expressed interleukin (IL)-4 and IL-10 in recall responses. Treatment of mice receiving 1 mg BCG with NS-398 (a PGHS-2 inhibitor, 10 mg/kg i.p., daily) resulted in enhanced interferon-gamma (IFN-gamma) production with reduced IL-4 and IL-10 production in recall responses. This treatment also resulted in decreased total serum IgE levels. Treatment of C57Bl/6 mice with HK-BCG (0.5 mg dose) also induced a mixture of Th1 and Th2 responses, although IFN-gamma production was markedly increased, and IL-4 was decreased compared with Balb/c mice. Thus, our results indicate that by 14 days following treatment of mice with high doses of HK-BCG, splenic PGE2-M? formation is associated with a PGHS-2-dependent shift from Th1-to-Th2 immune responses.     

Histamine upregulates Th1 and downregulates Th2 responses due to different patterns of surface histamine 1 and 2 receptor expression

Histamine, which acts via G protein-coupled receptors, is an important mediator of immediate hypersensitivity and is also able to influence the nature of T cell responses. We demonstrated that TH1 and Th2 cells express distinct surface histamine receptor patterns and that Th1-type responses are enhanced by histamine, whereas Th2-type responses are negatively regulated, due to different intracellular signals generated by histamine stimulation. These findings account for negative feedback regulation in a wide variety of pathologies.     

rIL-18对肺炎链球菌肺炎小鼠Th1/Th2免疫应答的影响

目的 研究重组白细胞介素18(rIL-18)对肺炎链球菌肺炎小鼠Th1/ Th2免疫应答的影响.方法 鼻腔接种肺炎链球菌建立小鼠肺炎链球菌肺炎模型,将Balb/c小鼠24只随机分为3组,分别为对照组,肺炎组和肺炎rIL-18干预组(n=8 ),RT-PCR法检测各组小鼠肺组织中IFN-γ、IL-4 mRNA 的表达,同时支气管肺泡灌洗液(BALB)进行活菌计数,有核细胞分类计数.结果 ①肺炎rIL-18干预组BA LF中性粒细胞和巨噬细胞计数显著高于肺炎组和对照组(P＜0.001);②肺炎rIL-18 干预组BALF活菌计数显著低于肺炎组(P＜0.001);③肺炎rIL-18干预组肺组织IFN- γ mRNA表达上调而IL-4 mRNA表达下调(P＜0.001).结论 在小鼠肺炎链球菌肺炎早期给予rIL-18可诱导IFN-γ的合成,促进Th1免疫应答,使Th1/ Th2免疫平衡向Th1免疫偏移、促进宿主对肺炎链球菌的防御.     

A recombinant BCG vaccine generates a Th1-like response and inhibits IgE synthesis in BALB/c mice

The tubercle vaccine, bacille Calmette-Guérin (BCG), is a strong inducer of T-helper type 1 (Th1) responsiveness, and it has been suggested that recombinant BCG (rBCG), which produces and secretes antigens, may be used to prevent allergic diseases. The effects of rBCG vaccination on allergic responses in a murine model were examined in this study. A BCG-Escherichia coli shuttle vector was developed with the promoter and signal sequence of the alpha-antigen of Mycobacterium bovis, and the vector was tested using E. coli beta-galactosidase as the model antigen and allergen. This vector enabled the expression of the E. coli beta-galactosidase gene in BCG, which was detected in its protein extract by immunoblotting analysis. Vaccination of mice with a single dose of 106 recombinant BCG generated a beta-galactosidase-specific antibody response. The splenocytes of vaccinated mice compared with controls produced significantly higher amounts of interferon-gamma (IFN-gamma) (P<0. 01) and interleukin-2 (IL-2) (P<0.05) and lower amounts of IL-5 (P<0. 01). Mice vaccinated with rBCG had significantly less (P<0.01) serum IgE compared with controls. These results together demonstrate that rBCG secreting antigens or allergens may be utilized for the induction of a Th1-like response and the down-regulation of IgE antibody response.     

Severe hypercholesterolaemia leads to strong Th2 responses to an exogenous antigen

Severe hypercholesterolaemia is associated with decreased levels of immunoglobulin G2a (IgG2a) antibodies [T-helper 1 (Th1) response] to modified malondialdehyde-modified low-density lipoprotein (MDA-LDL) and increased levels of Th2-dependent IgG1 antibodies in apolipoprotein E-deficient (apoE(-/-)) mice. To investigate whether this reflects a general pattern of metabolic regulation of the humoral immune response, apoE(-/-) mice were fed diets resulting in different degrees of hypercholesterolaemia and immunized with keyhole limpet haemocyanin (KLH) in aluminium hydroxide. Cholesterol levels for different treatment groups ranged from 14 to 77 mmol/l in serum and from 10 to 39 mmol/g in liver. Mice with severe hypercholesterolaemia had increased IgG1 antibodies to MDA-LDL and decreased IgG2a anti-MDA-LDL. Importantly, titres of IgG2a antibodies to KLH were also decreased, while IgE anti-KLH was increased, with a corresponding induction of interleukin-4 (IL-4) and IL-10 and a decrease in interferon-gamma (IFN-gamma) in KLH-stimulated spleen cells in vitro. Thus, hypercholesterolaemia clearly affects antibody production both to the autoantigen MDA-LDL and to the exogenous antigen KLH, favouring antibody isotypes (IgG1 and IgE) that are dependent on Th2 help to B cells. Nuclear receptors ligated by oxidized lipid derivatives modulate T-cell responses, and it is speculated that this mechanism may cause the switch to Th2 in severe hypercholesterolaemia.     

HCV多表位基因重组BCG的筛选及对其诱导的免疫应答研究

目的将丙型肝炎病毒（HCV）多表位基因的穿梭质粒pDE22-CtEm电转化BCG，筛选重组BCG（rBCG），免疫BALB／c小鼠，研究其诱导的免疫应答。方法培养并制备BCG感受态，将重组穿梭质粒pDE22-CtEm电转化BCG，筛选rBCG。rBCG免疫小鼠，同时进行基因免疫，测定血清中特异性抗体，分离小鼠脾淋巴细胞，体外测定淋巴细胞刺激指数、IFN-γ和进行CTL杀伤实验，观察rBCG在小鼠体内诱导的体液和细胞免疫应答。结果筛选出HCV多表位基因rBCG，免疫小鼠后在小鼠体内诱导出特异性的体液和细胞免疫应答，免疫应答水平均高于重组的基因免疫。结论构建的HCV多表位抗原rBCG活疫苗优于基因疫苗。     

The complement component C3 plays a critical role in both Th1 and Th2 responses to antigen

BACKGROUND: Complement component C3 is synthesized by keratinocytes and is activated after skin injury. C3 is also synthesized by peritoneal macrophages, which are activated by the adjuvant alum. OBJECTIVE: We sought to investigate the role of C3 in inciting allergic skin Inflammation and systemic immune responses after epicutaneous sensitization or intraperitoneal sensitization with antigen. METHODS: C3-deficient (C3-/-) mice and wild-type (WT) control animals were subjected to epicutaneous sensitization with the antigen ovalbumin (OVA) on shaved and tape-stripped skin or intraperitoneal immunization with OVA in alum. RESULTS: Skin Infiltration by eosinophils and expression of mRNA encoding the TH2 cytokines IL-4 and IL-5 in OVA-sensitized skin sites was impaired in C3-/- mice. Splenocytes from epicutaneously sensitized C3-/- mice secreted less IL-4, IL-5, IL-13, and IFN-gamma in response to OVA stimulation than splenocytes from WT control animals. The defect in cytokine secretion by splenocytes was also observed after intraperitoneal immunization of C3-/- mice. C3-/- mice had impaired IgG1, IgG2a, and IgE antibody responses after both epicutaneous and intraperitoneal immunization. The defect in cytokine secretion of C3-/- mice was not due to defective proliferation to antigen, was not observed after anti-CD3 stimulation, and was corrected by the addition of purified C3 protein. CONCLUSION: These results suggest that C3 plays an important role in both the TH1 and TH2 response to antigen in vivo. CLINICAL IMPLICATIONS: The complement pathway might be a potential target in the therapy of allergic diseases.     

Specific immune response and pathological findings in BALB/c mice inoculated with recombinant BCG expressing HIV-1 antigen

Recombinant BCGs (rBCGs) containing extrachromosomal plasmids with different HIV-1 insert sequences: nef, env (V3J1 and E9Q), gag p17 or whole gag p55 were evaluated for their immunogenicity, safety and persistent infection in BALB/c mice. Animal injected with, rBCG-plJKV3J1, rBCG-pSO gag p17 or rBCG-pSO gag p55 could elicit lymphocyte proliferation as tested by specific HIV-1 peptides or protein antigen. Inoculation with various concentration of rBCG-pSO gag p55 generated satisfactory specific lymphocyte proliferation in dose escalation trials. The rBCG-pSO gag p55 recovered from spleen tissues at different time interval post-inoculation could express the HIV protein as determined by ELISA p24 antigen detection kit. This result indicated that the extrachromosomal plasmid was stable and capable to express Gag protein. It was also demonstrated that rBCGs did not cause serious pathological change in the inoculated animals. The present study suggested the role of BCG as a potential vehicle for using in HIV vaccine development.     

Enhanced Th2-like responses in IL-1 type 1 receptor-deficient mice

IL-1 has a number of effects on T cell growth but a specific role for IL-1 in T cell responses in vivo has not been elucidated. In this study the role of IL-1 in Th1/Th2 responses was examined in mice deficient for the IL-1 type 1 receptor (IL-1RI −/−) during cutaneous Leishmania major infection or following immunization with keyhole limpet hemocyanin (KLH). After inoculation of L. major stationary phase promastigotes into the hind footpad, both IL-1RI−/− and wild-type (WT) mice developed small lesions which resolved spontaneously. Lymphnode cells from infected IL-1RI−/− mice produced significantly more IL-4 and IL-10 than those from WT mice following antigenic stimulation in vitro. Splenocytes from IL-1RI−/− and WT mice showed similar levels of antigen-induced proliferation. In contrast, splenocyte cultures from the IL-1RI−/− mice contained significantly more IL-4 than those from WT mice. Similar results were also obtained after immunization with KLH. While lymph node cells from both IL-1RI−/− and WT mice displayed similar levels of KLH-specific proliferation, those from IL-1RI −/− mice produced significantly more IL-4 than those from WT mice. Conversely, antigen-stimulated lymph node cells from WT mice secreted significantly greater amounts of IFN-γ as compared with those from IL-1RI −/− mice. These data indicate that while IL-1 is not required for mounting an immune response or antigen-dependent proliferation, it appears to be required for normal regulation of Th1/Th2 responses and may function to negatively regulate IL-4 expression.     

泡球蚴原头蚴抗原和卡介苗对Th1/Th2转录因子和细胞因子的影响

目的探讨泡球蚴原头蚴抗原和卡介苗免疫小鼠对泡球蚴攻击感染的调节机制。方法用实时定量聚合酶链反应检测鼠脾组织中GATA-3及T-bet的mRNA表达水平;酶联免疫吸附法检测鼠血清中白介素4和γ干扰素的含量。结果卡介苗免疫攻击组与PBS对照组的转录因子(T-bet mRNA)和其标志性细胞因子(INF-γ)的表达量,差异有统计学意义(P<0.05)。结论实验证明卡介苗(BCG)有上调Th1型免疫反应的作用,用BCG可以干预或治疗由泡球蚴抗原诱导的晚期泡球蚴(AE)动物的免疫抑制状态。     

过敏小鼠模型Th1/Th2漂移和纠正

目的：研究炒紫苏子醇提物对过敏小鼠模型Th1／Th2漂移和纠正作用。方法：设正常对照组、过敏模型组、炒紫苏子醇提取物0．32、0．64和1．28g／kg各剂量组小鼠共5组。利用流式细胞仪技术测定Th1型细胞因子IL-2、IFN-γTNF-α和Th2型细胞因子IL4、IL-5水平。结果：过敏模型小鼠IFN-γ／IL4为0．87，而正常小鼠IFN-γ／IL4为3．93，说明过敏小鼠Th1／Th2异常偏向Th2漂移。0．32、0．64和1．28g／kg各剂量组能明显提高IFN-γ水平（P〉0．05、P〈0．05和P〈0．01），降低IL-4水平（P〉0．05、P〉0．05和P〈0．05），其相应的IFN-γ／IL-4分别为1．92、2．85和3．14。结论：炒紫苏子醇提物能够纠正过敏小鼠Th1／Th2异常偏向Th2漂移，恢复正常，其作用呈剂量依赖关系。     

Dendritic cell subsets and the regulation of Th1/Th2 responses

Cells of the dendritic family are suited to perform two distinct functions at two discrete locations. In the peripheral tissues, dendritic cells (DC) act as sentinels for "dangerous" antigens. They then migrate into the lymphoid organ, where they initiate activation of T lymphocytes which are specific for these antigens. During their migration, DC shift from an antigen-capturing mode to a T cell sensitizing mode. In addition to switching on the immune response, subtypes of DC appear to influence the character of T cell differentiation, i.e. the Th1/Th2 balance. We will review the cellular and molecular bases of Th1-Th2 development by DC subsets, and will focus primarily, although not exclusively, on mouse DC.     

Th1/Th2 cytokine responses following HIV-1 immunization in seronegative volunteers

The Th1/Th2 profile that follows human vaccination may profoundly influence the subsequent course of disease after infection. However, the ability to detect IL-4 has been limited outside trials of live vaccination. By using methods in which memory effector cells are allowed to antigenically expand by short term culture, followed by low-dose mitogenic stimulation, we have been able to follow the Th1/Th2 profile in HIV-1^?volunteers enrolled in two phase I studies of HIV immunogens (a recombinant gp120 and a multivalent, octomeric V3 loop peptide). Antigen-specific interferon-gamma (IFN-γ) could be detected in primary stimulation, but IL-4 was observed only after antigenic expansion and restimulation. In both of these studies the responses after initial immunizations were dominated by IFN-γ, with IL-4 appearing only after multiple rounds of immunization, and IL-4 was temporally related to antibody production. Concomitant with the IL-4 production, the amount of supernatant IFN-γ declined. Antigen-specific IL-10 was not detected in either study. Such techniques, which have been shown to correlate with outcomes in immunotherapy, may prove useful as future surrogates of human vaccine response.     

A novel recombinant BCG-expressing pro-apoptotic protein BAX enhances Th1 protective immune responses in mice

One-third of the world's population is infected with Mycobacterium tuberculosis (MTB). The protective efficacy of bacille Calmette Guérin (BCG) vaccine against tuberculosis (TB) in adults is highly controversial even though the BCG vaccine has been available for more than 90 years. Because BCG is effective against infantile tuberculosis meningitis and miliary tuberculosis in young children and provides cost-effective prevention from tuberculosis for developing countries, it would be desirable to modify the existing BCG vaccine to provide more comprehensive protection. In our study, we constructed a novel recombinant BCG strain expressing pro-apoptotic BAX (rBCG::BAX) and demonstrated that it significantly induced the apoptosis of macrophages infected with rBCG::BAX both in vitro and in vivo. In addition, it significantly enhanced Ag85B-specific IFN-γ enzyme-linked immunospot responses, IFN-γ secretion, IL-2 secretion and the ratio of Ag85B-specific IgG2b/IgG1, and it significantly decreased Ag85B-specific IL-4. Furthermore, it presumably facilitated antigen presentation by inducing a significant up-regulation in the expression of MHC-II and B7.1 (CD80) co-stimulatory molecules on macrophages. In conclusion, these results suggest that the rBCG::BAX strain elicited predominantly a Th1 protective immune responses and might be a potential tuberculosis vaccine candidate for further study.     

Intravenous IgA complexed with antigen reduces primary antibody response to the antigen and anaphylaxis upon antigen re-exposure by inhibiting Th1 and Th2 activation in mice

Context: Serum IgG, IgE and IgM have been shown to enhance the primary antibody responses upon exposure to the soluble antigens recognized by those antibodies. However, how IgA affects these responses remains unknown.

Objective: We investigated the effects of intravenously administered monoclonal IgA on the immune responses in mice.

Materials and methods: DBA/1J mice were immunized with ovalbumin in the presence or absence of anti-ovalbumin monoclonal IgA. The Th1 and Th2 immune responses to ovalbumin and the anaphylaxis induced by re-exposure to ovalbumin were measured.

Results: IgA complexed with antigen attenuated the primary antibody responses to the antigen in mice, in contrast to IgG2b and IgE. The primary antibody responses, i.e. the de novo synthesis of anti-ovalbumin IgG2a, IgG1 and IgE in the serum, and the subsequent anaphylaxis induced with re-exposure to ovalbumin were reduced by the co-injection of anti-ovalbumin monoclonal IgA at ovalbumin immunization. The Th1, Th2 and Tr1 cytokines interferon-γ, interleukin-4 and interleukin-10, respectively, released from ovalbumin-restimulated cultured splenocytes collected from allergic mice were also reduced by the treatment. The induction of interferon-γ and interleukin-4 secretion by splenocytes from ovalbumin-immunized mice stimulated in vitro with ovalbumin was also significantly reduced by the antigen complexed with anti-ovalbumin IgA.

Conclusion: These data suggest that the direct inhibition of Th1 and Th2 activation by anti-ovalbumin monoclonal IgA participates in the inhibition of the primary antibody responses. IgA plays important immunosuppressive roles under physiological and pathological conditions and is a promising candidate drug for the treatment of immune disorders.     

A recombinant virus-like particle system derived from parvovirus as an efficient antigen carrier to elicit a polarized Th1 immune response without adjuvant

Hybrid virus-like particles (VLP) were prepared by self-assembly of the modified porcine parvovirus (PPV) VP2 capsid protein carrying a CD8⁺ or CD4⁺ T cell epitope. Immunization of mice with a single dose of these hybrid pseudo-particles, without adjuvant, induced strong cytotoxic T lymphocyte and T helper (Th) responses against the reporter epitope. The Th response was characterized by a Th1 phenotype. We also analyzed in vitro the uptake mechanism of these parvovirus-like particles and the processing requirements associated with presentation by MHC molecules. Although previously shown to be presented by MHC class I molecules, these particles also enter very efficiently the MHC class II endocytic pathway, and behave as conventional exogenous antigens. Indeed, the processing of chimeric PPV : VLP was performed in endosomal/lysosomal acidic vesicles and the presentation of the foreign epitope carried by these particles was sensitive to brefeldin A and cycloheximide, showing that the foreign peptide was loaded on nascent MHC class II molecules. These results give some indication of how PPV : VLP can be presented by MHC class I and class II molecules, and underscore the wide potency of such VLP system to deliver foreign antigens for vaccine design.     

Genetic control of antibody responses induced by recombinant Mycobacterium bovis BCG expressing a foreign antigen.

Recombinant Mycobacterium bovis BCG expressing foreign antigens represents a promising candidate for the development of future vaccines and was shown in several experimental models to induce protective immunity against bacterial or parasitic infections. Innate resistance to BCG infection is under genetic control and could modify the immune responses induced against an antigen delivered by such engineered microorganisms. To investigate this question, we analyzed the immune responses of various inbred strains of mice to recombinant BCG expressing beta-galactosidase. These experiments demonstrated that BALB/c mice developed strong antibody responses against BCG expressing beta-galactosidase under the control of two different promoters. In contrast, C57BL/6, C3H, and CBA mice produced high anti-beta-galactosidase antibody titers only when immunized with recombinant BCG expressing beta-galactosidase under the control of the pblaF* promoter, which induced the production of high levels of this antigen. This difference in mouse responsiveness to recombinant BCG was not due to innate resistance to BCG infection, since similar immune responses were induced in Ity(r) and Ity(s) congenic strains of mice. In contrast, the analysis of anti-beta-galactosidase antibody responses of H-2 congenic mice in two different genetic backgrounds demonstrated that H-2 genes are involved in the immune responsiveness to beta-galactosidase delivered by recombinant BCG. Together, these results demonstrate that immune responses to an antigen delivered by recombinant BCG are under complex genetic influences which could play a crucial role in the efficiency of future recombinant BCG vaccines.     

Adjuvant effect of zinc oxide on Th2 but not Th1 immune responses in mice

Background and aim: We investigated the effect of zinc oxide (ZnO) on Th1 and Th2 immune responses in mice.

Material and methods: Mice were intraperitoneally administered with ovalbumin (OVA) with or without varying doses of ZnO (day 0). On day 21, anti-OVA IgG, IgG2a, IgG1, and IgE antibodies in sera, OVA-specific proliferative responses of spleen cells, and production of Th1 cytokines including IFN-γ as well as Th2 cytokines such as IL-4 and IL-5 were measured.

Results: The results showed that administration of OVA with ZnO was followed by greater increases in anti-OVA IgG and the antigen-specific splenocyte proliferation compared to that of OVA alone. The production of anti-OVA IgG1 and IgE and secretion of IL-4 and IL-5 were markedly enhanced by ZnO. The enhancing effect of ZnO on these Th2 responses was as strong as aluminium hydroxide (Alum) that was widely used as an adjuvant. In contrast, treatment with OVA plus ZnO failed to affect production of anti-OVA IgG2a as well as IFN-γ. It was also observed that ZnO had a stimulating effect on the secretion of the proinflammatory cytokine IL-17 from a new lineage of effector Th cells.

Conclusion: These results suggest that ZnO appears to have an adjuvant effect on the immune system, especially Th2 but not Th1 immune responses.