Induction of HIV-1 Specific Mucosal Immune Responses by DNA Vaccination

DNA vaccination has been shown to induce immunity against several different pathogens including HIV-1. The authors demonstrate here that administration of DNA vaccines via the intranasal route is sufficient to induce immune responses both at distal mucosal sites and systemically. Since transmission of HIV-1 occurs largely across mucosal surfaces, the intranasal route provides a further means of application for DNA immunization.     

Toll样受体与Th1和Th2型免疫应答

Toll样受体是广泛表达在哺乳动物细胞表面的跨膜信号传导受体,其通过识别多种类型的病原体相关分子模式及一些内源性配体,激活天然免疫系统,同时通过诱导树突状细胞分化成熟,调控获得性免疫反应的建立。大多数TLRs的配体可诱导机体产生Th1型免疫应答,然而在某些条件下也可导致Th2型免疫应答的发生。弄清TLRs参与调节Th0分化的机制,可为今后在感染免疫、自身免疫、超敏反应等方面进行深入研究及相关疾病的治疗提供新的切入点。     

Th17 Cytokines and the Gut Mucosal Barrier

Local immune responses serve to contain infections by pathogens to the gut while preventing pathogen dissemination to systemic sites. Several subsets of T cells in the gut (T-helper 17 cells, γδ T cells, natural killer (NK), and NK-T cells) contribute to the mucosal response to pathogens by secreting a subset of cytokines including interleukin (IL)-17A, IL-17F, IL-22, and IL-26. These cytokines induce the secretion of chemokines and antimicrobial proteins, thereby orchestrating the mucosal barrier against gastrointestinal pathogens. While the mucosal barrier prevents bacterial dissemination from the gut, it also promotes colonization by pathogens that are resistant to some of the inducible antimicrobial responses. In this review, we describe the contribution of Th17 cytokines to the gut mucosal barrier during bacterial infections.     

Induction of Antigen-Specific Th1-Type Immune Responses by Gamma-Irradiated Recombinant Brucella abortus RB51

Brucella abortus strain RB51 is an attenuated rough mutant used as the live vaccine against bovine brucellosis in the United States and other countries. We previously reported the development of strain RB51 as a bacterial vaccine vector for inducing Th1-type immune responses against heterologous proteins. Because safety concerns may preclude the use of strain RB51-based recombinant live vaccines, we explored the ability of a gamma-irradiated recombinant RB51 strain to induce heterologous antigen-specific immune responses in BALB/c mice. Exposure of strain RB51G/LacZ expressing Escherichia coli β-galactosidase to a minimum of 300 kilorads of gamma radiation resulted in complete loss of replicative ability. These bacteria, however, remained metabolically active and continued to synthesize β-galactosidase. A single intraperitoneal inoculation of mice with 10⁹ CFU equivalents of gamma-irradiated, but not heat-killed, RB51G/LacZ induced a β-galactosidase-specific Th1-type immune response. Though no obvious differences were detected in immune responses to B. abortus-specific antigens, mice vaccinated with gamma-irradiated, but not heat-killed, RB51G/LacZ developed significant protection against challenge with virulent B. abortus. In vitro experiments indicated that gamma-irradiated and heat-killed RB51G/LacZ induced maturation of dendritic cells; however, stimulation with gamma-irradiated bacteria resulted in more interleukin-12 secretion. These results suggest that recombinant RB51 strains exposed to an appropriate minimum dose of gamma radiation are unable to replicate but retain their ability to stimulate Th1 immune responses against the heterologous antigens and confer protection against B. abortus challenge in mice.     

Induction of Systemic and Mucosal Immune Responses Following Immunization with Somatostatin-Avidin Complexes Incorporated Into Iscoms

Synthetic, biotinylated somatostatin-14 (Somatotropin Release-Inhibiting Factor; SRIF) was conjugated to avidin, and the resulting complex incorporated into immune-stimulating complexes (ISCOMS). The ISCOMS were used to study the systemic and mucosal immune responses induced by parenteral and gastrointestinal vaccination. Mice were immunized by intraperitoneal (IP) and intragastric (IG) routes and subsequently by either IP or IG secondary immunizations (groups-IP/IP; IP/IG; IG/IG). Antigen specific IgG and IgA antibody secreting cells (ASC) from the spleen, mesenteric lymph nodes (MLN) and Peyer's patches (PP's) were studied by an enzyme-linked immunospot assay (ELISPOT). Specific proliferative responses of spleen cells to avidin and to SRIF were measured.

Immunization IP/IP evoked the highest serum IgG levels to avidin and to SRIF as well as the highest numbers of splenic IgG isotype ASC. The greatest IgA response in MLN and PP's was induced by IP/IG immunization. Only marginal mucosal immunity and no splenic cell specific proliferative responses were found by IG/IG immunization.

These results indicate that ISCOMS are an effective delivery system for protein-peptide antigens. The ISCOMS system described elicited systemic and mucosal antibody immune responses, and primed specific proliferative response when administered IP/IG. This offers another approach for the design and delivery of mucosally administered peptide vaccines.     

Induction of Systemic and Mucosal Immune Responses Following Immunization with Somatostatin-Avidin Complexes Incorporated Into Iscoms

Synthetic, biotinylated somatostatin-14 (Somatotropin Release-Inhibiting Factor; SRIF) was conjugated to avidin, and the resulting complex incorporated into immune-stimulating complexes (ISCOMS). The ISCOMS were used to study the systemic and mucosal immune responses induced by parenteral and gastrointestinal vaccination. Mice were immunized by intraperitoneal (IP) and intragastric (IG) routes and subsequently by either IP or IG secondary immunizations (groups-IP/IP; IP/IG; IG/IG). Antigen specific IgG and IgA antibody secreting cells (ASC) from the spleen, mesenteric lymph nodes (MLN) and Peyer's patches (PP's) were studied by an enzyme-linked immunospot assay (ELISPOT). Specific proliferative responses of spleen cells to avidin and to SRIF were measured.

Immunization IP/IP evoked the highest serum IgG levels to avidin and to SRIF as well as the highest numbers of splenic IgG isotype ASC. The greatest IgA response in MLN and PP's was induced by IP/IG immunization. Only marginal mucosal immunity and no splenic cell specific proliferative responses were found by IG/IG immunization.

These results indicate that ISCOMS are an effective delivery system for protein-peptide antigens. The ISCOMS system described elicited systemic and mucosal antibody immune responses, and primed specific proliferative response when administered IP/IG. This offers another approach for the design and delivery of mucosally administered peptide vaccines.     

Infective Dose Modulates the Balance between Th1- and Th2-Regulated Immune Responses during Blood-Stage Malaria Infection

Plasmodium chabaudi infection of mice provides an excellent model for examining acquired immunity to the blood-borne stage of malaria infection. CD4⁺ T-cell receptor (TCR) αβ-bearing T lymphocytes play a critical role in mediating protection, ascribed to both T helper (Th) 1 and Th2 subsets. One factor that may influence the Th1/Th2 cell balance is infective dose. In this study, we found that the size of the infective dose of P. chabaudi , and thus the level of antigen presented to the immune system, correlated with the balance of responder CD4⁺ T-cell phenotypes. Increasing the infective dose in a resistant mouse strain enhanced the Th1 cytokine (interferon-γ; IFN-γ) response and reduced the Th2 cytokine (interleukin-4; IL-4) response. In contrast, increasing the infective dose in a susceptible mouse strain led to a prominent and accelerated up-regulation of IL-4 production. These data show that the dose of antigen can significantly affect the balance between Th1- and Th2-mediated immune functions during infection of the mammalian host with blood-stage malaria parasites. This demonstration that parasite numbers may modulate CD4⁺ T-cell regulation has novel implications for the successful implementation of antimalarial vaccination and chemotherapeutic strategies.     

Heat Denaturation of Egg-White Proteins Abrogates the Induction of Oral Tolerance of Specific Th2 Immune Responses in Mice

Human foods are usually prepared by cooking. Boiling of chicken egg-white (EW) led to decreased allergenicity, and abrogated intestinal uptake of immunoreactive ovalbumin (OVA) when fed to mice. Therefore, the effects of oral administration of boiled EW were examined further in BALB/c mice. Specific IgE, IgG₁ and IgG antibody responses were suppressed by raw EW, but not by EW boiled for 5 or 60 min, fed prior to sensitization with 10  μ g OVA or 1  μ g DNP–OVA in alum. Similar results were obtained when mice were sensitized with 10  μ g conalbumin, ovomucoid or lysozyme in alum. BALB/c spleen cell proliferation and secretion of Th2 cytokines IL-4 and IL-5 during in vitro stimulation with OVA were also suppressed by feeding raw EW, but not by boiled EW. Although heat denaturation of proteins can minimize allergenicity, the present results suggest that over-cooking of proteins may affect their intestinal antigen processing and thus prevent the induction of oral tolerance.     

Interleukin 7 Can Enhance Antigen-Specific Cytotoxic-T-Lymphocyte and/or Th2-Type Immune Responses In Vivo

Interleukin 7 (IL-7) protein has been reported to be important in the development of cytotoxic-T-lymphocyte (CTL) responses. However, other studies also support a partial Th2 phenotype for this cytokine. In an effort to clarify this unusual conflict, we compared IL-7 along with IL-12 (Th1 control) and IL-10 (Th2 control) for its ability to induce antigen (Ag)-specific CTL and Th1- versus Th2-type immune responses using a well established DNA vaccine model. In particular, IL-7 codelivery showed a significant increase in immunoglobulin G1 (IgG1) levels compared to IgG2a levels. IL-7 coinjection also decreased production of Th1-type cytokine IL-2, gamma interferon, and the chemokine RANTES but increased production of the Th2-type cytokine IL-10 and the similarly biased chemokine MCP-1. In herpes simplex virus (HSV) challenge studies, IL-7 coinjection decreased the survival rate after lethal HSV type 2 (HSV-2) challenge compared with gD plasmid vaccine alone in a manner similar to IL-10 coinjection, whereas IL-12 coinjection enhanced the protection, further supporting that IL-7 drives immune responses to the Th2 type, resulting in reduced protection against HSV-2 challenge. Moreover, coinjection with human immunodeficiency virus type 1 env and gag/pol genes plus IL-12 or IL-7 cDNA enhanced Ag-specific CTLs, while coinjection with IL-10 cDNA failed to influence CTL induction. Thus, IL-7 could drive Ag-specific Th2-type cellular responses and/or CTL responses. These results support that CTLs could be induced by IL-7 in a Th2-type cytokine and chemokine environment in vivo. This property of IL-7 allows for an alternative pathway for CTL development which has important implications for host-pathogen responses.     

Relationship between the Degree of Cardiovascular Adaptation and Th1/Th2 Polarization of Immune Response

The main parameters of humoral immunity during medium intensity exercise were studied in oarsmen with high and low cardiovascular adaptation. A relationship between high cardiovascular adaptation to exercise and immune response polarization by the Th2 mechanism was demonstrated. Increased production of IL-10 in response to physical stress plays a key role in this relationship. Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 146, No. 10, pp. 442–445, October, 2008     

Rapeseed Oil and Ginseng Saponins Work Synergistically To Enhance Th1 and Th2 Immune Responses Induced by the Foot-and-Mouth Disease Vaccine

Previous investigations demonstrated that saponins isolated from the root of Panax ginseng C. A. Meyer (i.e., ginseng root saponin [GS-R]) had adjuvant activity. In the present study, the combined effects of rapeseed oil (RO) and GS-R on the immune responses elicited by foot-and-mouth disease (FMD) vaccine were investigated by measuring FMD virus (FMDV)-specific antibody levels, cytokine levels, lymphocyte proliferation, and long-lived IgG-secreting plasma cells from bone marrow in a mouse model. The results indicated that RO in combination with GS-R significantly enhanced serum IgG and isotype concentrations, gamma interferon (IFN-γ) and interleukin 5 (IL-5) levels, splenocyte proliferative responses to stimulations with concanavalin A (ConA), lipopolysaccharide (LPS), and FMDV antigen, and the numbers of IgG-secreting plasma cells in the bone marrow, suggesting that RO/GS-R enhanced both Th1 and Th2 immune responses. In addition, no significant difference was found between RO/GS-R and the commercial adjuvant oil ISA 206 in the promotion of FMD vaccine-induced immune responses. Considering the vegetable origin of RO and GS-R and the potent adjuvant activity, RO/GS-R should be studied further for the development of veterinary vaccines, especially for use in food animals in order to promote food safety.     

The Th1/Th2 paradigm

The Th1/Th2 paradigm provides a useful model for understanding the pathogenesis of several diseases, as well as for developing novel immunotherapeutic strategies. Here, Sergio Romagnani examines Th1/Th2 polarization in the context of associated pathophysiological conditions.     

Vaccine-Induced Th1-Type Responses are Dominant over Th2-Type Responses in the Short Term whereas Pre-existing Th2 Responses are Dominant in the Longer Term

The effect of adjuvant on induction of human papillomavirus type 16 E7 protein-specific cytotoxic T lymphocytes (CTL) and immunoglobulin G (IgG)_2a antibody was studied in C57BL/6 J mice immunized with various adjuvants and E7 protein. Quil-A adjuvant, but not complete Freund's adjuvant (CFA) or Algammulin, induced a T-helper 1 (Th1)-type response to E7, which was characterized by CTL activity against a tumour cell line transfected with E7 protein and by E7-specific IgG_2a. All tested adjuvants elicited comparable levels of E7-specific IgG₁. The longest duration and greatest magnitude of CTL response was seen following two immunizations with the highest dose of E7 and Quil-A. Simultaneous immunization with a Th1 and a T helper 2 (Th2)-promoting adjuvant gave a Th1-type response. However, E7 and Quil-A were unable to induce a Th1-type response (as measured by the inability to generate anti-E7 IgG_2a antibody) in animals with a pre-existing Th2-type response to E7. These results suggest that saponin adjuvants may be suitable for immunotherapy in humans where a Th1-type response is sought, provided that there is no pre-existing Th2-type response to the antigen.     

细胞信号转导介导与日本血吸虫特异性Th1/Th2免疫偏移

分别于小鼠感染日本血吸虫后 0、 4、 6、 8和 12周 ,取脾淋巴细胞体外培养 ,进行细胞信号转导抑制试验 ,观察酪氨酸蛋白激酶 (TPK )、蛋白激酶C (PKC )和磷酯酰肌醇 3 激酶 (PI 3 K )特异性抑制剂 (Tyrphostin 2 5、D sphingosine和Wort mannin )分别特异性抑制和不同组合抑制TPK、PKC和PI 3K后 ,对小鼠脾淋巴细胞经虫卵可溶性抗原 (SEA )诱生IL 2、IFN γ和IL 4的表达水平及对Th1/Th2免疫偏移的影响。结果发现Tyrphostin 2 5对IL 2、IFN γ和IL 4水平的抑制作用均非常显著(P <0 0 1) ,D sphingosine主要影响IL 4的表达 (P <0 0 1) ,而Wortmannin则主要影响IFN γ的表达 (P <0 0 1) ,Tyrphostin 2 5和Wortmannin联合应用可完全阻断IL 2的表达及增强对IFN γ的抑制作用 ,Tyrphostin 2 5和D sphingosine联合应用可完全阻断IL 4的表达。对反映Th1/Th2免疫平衡的Th2分化指数分析表明 ,D sphingosine可使Th2免疫应答优势减弱 ,而Wort mannin则可使Th2免疫应答优势增强。研究结果表明 ,干预细胞信号转导可调节日本血吸虫特异性Th1/Th2细胞因子表达水平及Th1/Th2免疫偏移 ,为探索控制日本血吸虫卵肉芽肿病变的潜在新途径 ,提供了实验依据。     

天花粉蛋白诱导小鼠Th2/Tc2亚群分化与MHC背景相关

为阐明天花粉蛋白 (Tk )诱导免疫抑制和基因调控的机制 ,应用ELISA方法动态测定小鼠OVA特异性T淋巴细胞培养上清液中T细胞亚群相关细胞因子的含量 ,观察Tk对高、低易感品系小鼠T细胞分泌细胞因子格局的影响。发现Tk作用下 ,高易感品系C5 7BL/ 6 (H 2 b)IL 4、IL 10分泌量大幅度增高 ,IFN γ显著下降 ;而低易感品系C3H/He (H 2 k)相应的细胞因子变化极小。上述结果表明 :(1)Tk可诱导功能性T细胞亚群向Th2 /Tc2方向分化 ,并导致OVA特异性T细胞增殖受抑 ;(2 )T细胞亚群分化与MHC背景密切相关。提示Tk作用下T细胞亚群的分化受MHC基因调控     

Induction of transient immune suppression and Th1/Th2 disbalance by pediatric cardiac surgery with cardiopulmonary bypass

Cardiovascular surgery with cardiopulmonary bypass (CPB) can lead to postoperative complications like postpericardiotomy syndrome (PPS), capillary leak syndrome or multiple organ failure. PPS morbidity in children is up to 30%, mortality up to 4%. For these complications the CPB is made responsible. Their etiology is not yet clarified in detail, but it is thought to be of immunologic origin. The exact knowledge of these reactions is crucial for the selection of treatment strategies and is the issue of this overview. Cardiovascular surgery is accompanied by the release of proinflammatory cytokines (IL-6, IL-8) and the activation of the alternative complement pathway. This reaction is mainly a response to the surgical trauma and the medication. The exclusively CPB-specific response is the elevated activation of the alternative complement pathway. CPB also induces an antiinflammatory response. The immunosuppressive cytokine IL-10 is systemically released before the release of proinflammatory cytokines. Perioperatively T-helper (Th) cells shift transiently to the Th2 phenotype and indicate the prevalence for a humoral immune response. This shift starts immediately after the onset of the CPB. Increased immunosuppression may be involved in PPS development and seems to be linked to an allergic/atopic predisposition. CPB surgery induces population shifts of the leukocyte subsets, changes of their degree of activation and contributes to the peripheral phenotype of immune suppression. During CPB surgery, circulating neutrophils are inactivated and activated cells are selectively depleted by the CPB filters. In children, cardiovascular surgery with CPB induces a systemic antiinflammatory response. The following factors contribute to this response: elimination of activated cells; compensatory reaction to local, systemically not observable, proinflammatory responses; IL-10 release; anesthetics and medication; and leukocyte extravasation. The subsequent proinflammatory reaction is the reaction to surgical trauma and modulates the antiinflammatory reaction. Immune suppression seems to be an important response to CPB and PPS development and may lead to temporary anergy. Possible therapeutic consequences may include treatment strategies that modulate the antiinflammatory response. More studies in neonates and infants are needed to test this hypothesis. Novel microanalytical techniques have to be developed to achieve this goal.