Effects of Antigen and Genetic Adjuvants on Immune Responses to Human Immunodeficiency Virus DNA Vaccines in Mice

The effects of genetic adjuvants on humoral and cell-mediated immunity to two human immunodeficiency virus antigens, Env and Nef, have been examined in mice. Despite similar levels of gene expression and the same gene delivery vector, the immune responses to these two gene products differed following DNA immunization. Intramuscular immunization with a Nef expression vector plasmid generated a humoral response and antigen-specific gamma interferon (IFN-gamma) production but little cytotoxic-T-lymphocyte (CTL) immunity. In contrast, immunization with an Env vector stimulated CTL activity but did not induce a high-titer antibody response. The ability to modify these antigen-specific immune responses was investigated by coinjection of DNA plasmids encoding cytokine and/or hematopoietic growth factors, interleukin-2 (IL-2), IL-12, IL-15, Flt3 ligand (FL), and granulocyte-macrophage colony-stimulating factor (GM-CSF). Coadministration of these genes largely altered the immune responses quantitatively but not qualitatively. IL-12 induced the greatest increase in IFN-gamma and immunoglobulin G responses to Nef, and GM-CSF induced the strongest IFN-gamma and CTL responses to Env. A dual approach of expanding innate immunity by administering the FL gene, together with a cytokine that enhances adaptive immune responses, IL-2, IL-12, or IL-15, generated the most potent immune response at the lowest doses of Nef antigen. These findings suggest that intrinsic properties of the antigen determine the character of immune reactivity for this method of immunization and that specific combination of innate and adaptive immune cytokine genes can increase the magnitude of the response to DNA vaccines.     

Effect of Adjuvants on the Antibody Response to a Hapten on a Thymus-independent Carrier

IT has been demonstrated in mice that levan (polyfructose), an antigen which interacts only with B lymphocytes¹, can function as a carrier and produce a thymus-independent response to dinitrophenol (DNP)². Using this conjugate, antibody-production against the hapten is totally unaffected in thymectomized animals and is abolished in mice tolerant to levan. The DNP-levan conjugate produces only 19S antibody against DNP.     

Cathepsin-mediated Necrosis Controls the Adaptive Immune Response by Th2 (T helper type 2)-associated Adjuvants

Immunologic adjuvants are critical components of vaccines, but it remains unclear how prototypical adjuvants enhance the adaptive immune response. Recent studies have shown that necrotic cells could trigger an immune response. Although most adjuvants have been shown to be cytotoxic, this activity has traditionally been considered a side effect. We set out to test the role of adjuvant-mediated cell death in immunity and found that alum, the most commonly used adjuvant worldwide, triggers a novel form of cell death in myeloid leukocytes characterized by cathepsin-dependent lysosome-disruption. We demonstrated that direct lysosome-permeabilization with a soluble peptide, Leu-Leu-OMe, mimics the alum-like form of necrotic cell death in terms of cathepsin dependence and cell-type specificity. Using a combination of a haploid genetic screen and cathepsin-deficient cells, we identified specific cathepsins that control lysosome-mediated necrosis. We identified cathepsin C as critical for Leu-Leu-OMe-induced cell death, whereas cathepsins B and S were required for alum-mediated necrosis. Consistent with a role of necrotic cell death in adjuvant effects, Leu-Leu-OMe replicated an alum-like immune response in vivo, characterized by dendritic cell activation, granulocyte recruitment, and production of Th2-associated antibodies. Strikingly, cathepsin C deficiency not only blocked Leu-Leu-OMe-mediated necrosis but also impaired Leu-Leu-OMe-enhanced immunity. Together our findings suggest that necrotic cell death is a powerful mediator of a Th2-associated immune response.     

Cross-Talk Between Neurons and Astrocytes in Response to Bilirubin: Early Beneficial Effects

Hyperbilirubinemia remains one of the most frequent clinical diagnoses in the neonatal period. This condition may lead to the deposition of unconjugated bilirubin (UCB) in the central nervous system, causing nerve cell damage by molecular and cellular mechanisms that are still being clarified. To date, all the studies regarding bilirubin-induced neurological dysfunction were performed in monotypic nerve cell cultures. The use of co-cultures, where astrocyte-containing culture inserts are placed on the top of neuron cultures, provides the means to directly evaluate the cross-talk between these two different cell types. Therefore, this study was designed to evaluate whether protective or detrimental effects are produced by astrocytes over UCB-induced neurodegeneration. Our experimental model used an indirect co-culture system where neuron-to-astrocyte signaling was established concomitantly with the 24 h exposure to UCB. In this model astrocytes abrogated the well-known UCB-induced neurotoxic effects by preventing the loss of cell viability, dysfunction and death by apoptosis, as well as the impairment of neuritic outgrowth. To this protection it may have accounted the induced expression of the multidrug resistance-associated protein 1 and the 3.5-fold increase in the values of S100B, when communication between both cells was established independently of UCB presence. In addition, the presence of astrocytes in the neuronal environment preserved the UCB-induced increase in glutamate levels, but raised the basal concentrations of nitric oxide and TNF-α although no UCB effects were noticed. Our data suggest that bidirectional signalling during astrocyte-neuron recognition exerts pro-survival effects, stimulates neuritogenesis and sustains neuronal homeostasis, thus protecting cells from the immediate UCB injury. These findings may help explain why irreversible brain damage usually develops only after the first day of post-natal life.     

Current Research on the Immune Response to Experimental Sporotrichosis

Sporotrichosis is often manifested as a chronic granulomatous infection and the monocytes/macrophages play a central role in the host defense system. Surface components of Sporothrix schenckii have been characterized and suggestions have been made as to their possible role in pathogenicity. Ergosterol peroxide, cell-wall compounds (alkali-insoluble fraction-F1 and lipid extract-LEY), and exoantigen from the yeast form of the fungus have been characterized as virulence factors, activating both innate, by cytotoxins linked to the activation of reactive oxygen and nitrogen species (H₂O₂ and NO), and adaptive immune response to produce cytokines Th1 and Th2 profile. In this study, preliminary results have demonstrated that, in systemic sporotrichosis, TLR-4 triggers the innate immune response, activating an oxidative burst. These data represent the first report of the participation of TLR-4 in murine sporotrichosis, in the presence of lipids from the cell wall of S. schenckii. These results taken together may open new perspectives of study leading to an antifungal agent that could be used to benefit the entire population.     

Immune Response to Toxoplasma gondii

Peripheral blood leukocytes (PBL) from patients with toxoplasmosis were shown to be highly responsive to in vitro stimulation with Toxoplasma gondii extract as measured by incorporation of [³H]methylated thymidine. Analysis of Toxoplasma-specific proliferative cells in PBL by using monoclonal antibodies specific for human T cell subsets revealed that the Toxoplasma-specific proliferation response of PBL from the patients was mediated by Leu 1, Leu 3a positive cells, that is, helper/inducer T cells. Tests for the Toxoplasma-specific proliferation response may provide a readily available method for the diagnosis of congenital toxoplasmosis, especially during the newborn period.     

Polymyxins as Novel and Safe Mucosal Adjuvants to Induce Humoral Immune Responses in Mice

There is currently an urgent need to develop safe and effective adjuvants for enhancing vaccine-induced antigen-specific immune responses. We demonstrate here that intranasal immunization with clinically used polypeptide antibiotics, polymyxin B (PMB) and colistin (CL), along with ovalbumin (OVA), increases OVA-specific humoral immune responses in a dose-dependently manner at both mucosal and systemic compartments. Enhanced immunity by boosting was found to persist during 8 months of observation. Moreover, mice intranasally immunized with OVA plus various doses of PMB or CL showed neither inflammatory responses in the nasal cavity and olfactory bulbs nor renal damages, compared to those given OVA alone. These data suggest that polymyxins may serve as novel and safe mucosal adjuvants to induce humoral immune responses. The polymyxin adjuvanticity was found to be independent of endotoxins liberated by its bactericidal activity, as indicated by similar enhancing effects of PMB in lipopolysaccharide (LPS)-hyporesponsive and LPS-susceptible mice. However, despite the presence of preexisting anti-PMB antibodies, we observed no reduction in the adjuvant function of polymyxins when they were given intranasally. Furthermore, the titers of OVA-specific Abs in mice intranasally immunized with OVA plus PMB or CL were significantly higher than those in mice administered with polymyxin analogues, such as polymyxin B nonapeptide and colistin methanesulfonate. The levels of released β-hexosaminidase and histamine in mast cell culture supernatants stimulated by PMB or CL were also significantly higher than those stimulated by their analogues. These results suggest that both the hydrophobic carbon chain and hydrophilic cationic cyclic peptide contribute to the mucosal adjuvanticity of PMB and CL.     

Oligodendroglial Response to the Immune Cytokine Interferon Gamma

In the human demyelinating disorder multiple sclerosis, and its animal model experimental allergic encephalomyelitis, there is a breakdown of the blood-brain barrier and an infiltration of immune cells into the CNS. Infiltrating T lymphocytes and macrophages are believed to be key mediators of the disease process. Considerable circumstantial and experimental evidence has suggested that the pleiotropic cytokine interferon gamma (IFN-), which is exclusively expressed by T cells and natural killer cells, is a deleterious component of the immune response in these disorders. When experimentally introduced into the CNS IFN- promotes many of the pathological changes that occur in immune-mediated demyelinating disorders. In vitro, this cytokine elicits a number of effects on oligodendrocytes, including cell death. The harmful actions of IFN- on CNS myelin are likely mediated through direct effects on the myelinating cells, as well as through the activation of macrophages and microglia. In this review we summarize relevant studies concerning the action of IFN- in demyelinating disorders and discuss possible mechanisms for the observed effects.     

Beneficial Effects of Celastrol on Immune Balance by Modulating Gut Microbiota in Experimental Ulcerative Colitis Mice

Ulcerative colitis (UC) is a chronic inflammatory bowel disease caused by many factors including colonic inflammation and microbiota dysbiosis. Previous studies have indicated that celastrol (CSR) has strong anti-inflammatory and immune-inhibitory effects. Here, we investigated the effects of CSR on colonic inflammation and mucosal immunity in an experimental colitis model, and addressed the mechanism by which CSR exerts the protective effects. We characterized the therapeutic effects and the potential mechanism of CSR on treating UC using histological staining, intestinal permeability assay, cytokine assay, flow cytometry, fecal microbiota transplantation (FMT), 16S rRNA sequencing, untargeted metabolomics, and cell differentiation. CSR administration significantly ameliorated the dextran sodium sulfate (DSS)-induced colitis in mice, which was evidenced by the recovered body weight and colon length as well as the decreased disease activity index (DAI) score and intestinal permeability. Meanwhile, CSR down-regulated the production of pro-inflammatory cytokines and up-regulated the amount of anti-inflammatory mediators at both mRNA and protein levels, and improved the balances of Treg/Th1 and Treg/Th17 to maintain the colonic immune homeostasis. Notably, all the therapeutic effects were exerted in a gut microbiota-dependent manner. Furthermore, CSR treatment increased the gut microbiota diversity and changed the compositions of the gut microbiota and metabolites, which is probably associated with the gut microbiota-mediated protective effects. In conclusion, this study provides the strong evidence that CSR may be a promising therapeutic drug for UC.     

Microwaves in the Induction of Immune Response to VI-Antigen

In this work the possibility of using microwaves (MW) for immuno-modulation in the immunization of animals with thymus-independent antigen was studied. The projection zones of the thyroid and adrenal glands of the test animals were subjected to the action of decimeter MW, while the corresponding zones of control animals were subjected to imitation MW. The endocrine activity of rabbits was estimated by radioim-mune methods. Vi-antigen was shown to be a thymus-independent antigen for rabbits, according to the results of fluorescent probes to study the structural rearrangements in surfaces of thymocyte membranes and their nuclei, which reflect early changes during the physiological activation of cells. The irradiation by MW on the projection zone of the thyroid was accompanied by a decrease in the glucocorticoid activity of the adrenal cortex and a simultaneous pronounced immunostimulating effect. MW irradiation of the zone of the adrenal glands was accompanied by immunosuppression in combination with enhanced glucocorticoid activity of the adrenal cortex.     

Beneficial Effects of Sitostanol on the Attenuated Immune Function in Asthma Patients: Results of an In Vitro Approach

Background

In vitro and animal studies have suggested that plant sterols and stanols increase cytokine production by T-helper-1 cells. This may be beneficial for patient groups characterized by a T-helper-2 dominant immune response, e.g. asthma patients. (1) to evaluate whether sitostanol induces a T-helper-1 shift in peripheral blood mononuclear cells (PBMCs) from asthma patients, and (2) to unravel the role of regulatory T-cells in this respect.

Methodology/Principal Findings

PBMCs from 10 asthma patients and 10 healthy subjects were isolated and incubated with 1.2 µM sitostanol, while stimulated with 5 µg/ml PHA. Similar amounts of cholesterol were used to determine whether effects were specific for plant stanols or for sterols in general. Changes in cytokine production were measured using antibody arrays and ELISAs. Changes in regulatory T-cell population size were measured by flow cytometry, using intracellular Foxp3 staining. Sitostanol increased production of IFNγ by 6.5% and IL-2 by 6.0% compared to cholesterol (p<0.01). No changes in IL-4 and IL-13 were found. Interestingly, this effect was only present in PBMCs from asthma patients. The number of Foxp3+ cells tended to increase and their activity, measured by IL-10 production, increased after sitostanol treatment in PBMCs from asthma patients compared to controls by 32.3% (p = 0.077) and 13.3% (p<0.05), respectively.

Conclusions/Significance

Altogether, the sitostanol-induced Thelper-1 shift in PBMCs from asthma patients and the stimulating effects of sitostanol on Treg cell numbers and activity indicate a possible novel approach for plant stanol ester enriched functional foods in the amelioration of asthmatic symptoms. Functional effects, however, require further evaluation.     

维生素A对免疫功能的影响

维生素A已经作为一种营养补充剂用在临床治疗和日常膳食中,对机体的免疫系统有重要意义。近年来许多关于维生素A与免疫的关系和机制探讨也随着分子生物学的发展取得了很大进步。该介绍维生素A在体内、体外试验中对细胞免疫、体液免疫的作用,在临床应用中的效用,以及不同剂量作用于免疫系统产生的不同结果等。     

果寡糖和甘露寡糖对断奶仔猪免疫机能的影响

研究探讨了果寡糖和甘露寡糖对断奶仔猪免疫机能的影响。实验采用随机区组设计法将48头健康、体重一致的35日龄断奶杜洛克仔猪分为4组,每组3次重复,每个重复4头进行为期28天的饲养实验。4个处理组分别为:基础日粮 0.5%果寡糖(FOS组)、基础日粮 0.3%甘露寡糖(MOS组)、基础日粮 0.45%果寡糖 0.25%甘露寡糖(F M组)、基础日粮 75 mg/kg金霉素 40 mg/kg洛克沙生(ABT组)。实验结果表明:(1)寡糖组免疫器官指数较ABT组大(P>0.05)。(2)在断奶后第7天,FOS组(0.32±0.49)、MOS组(0.32±0.04)和F M组(0.32±0.07)均较ABT组(0.20±0.01)显著提高了血清免疫球蛋白A(IgA)的浓度(P<0.05),同时FOS组(3.50±0.49)较ABT组(2.68±0.47)显著提高了IgG浓度(P<0.05);F M组显著提高了断奶后第21天IgG浓度(P<0.05);MOS组显著提高了断奶后第21天IgM浓度(P<0.05)。(3)与ABT组相比,FOS显著提高了断奶后第7天胸腺(21.33±6.03对37.33±4.04)、脾脏(19.67±2.08对30.33±8.73)、淋巴结(24.67±4.16对37.67±2.52)CD4 T淋巴细胞百分数(P<0.05);FOS组(21.33±4.04对32.00±5.29)、MOS组(21.33±4.04对37.33±3.21)、F M组(21.33±4.04对32.00±3.60)显著提高了断奶后第28天胸腺CD4 T淋巴细胞百分数(P<0.05);MOS组(20.67±3.51对29.67±5.51)显著提高了断奶后第7天胸腺CD8 T淋巴细胞百分数;F M组(17.00±1.00对22.67±3.06)显著提高了断奶后第7天脾脏CD8 T淋巴细胞百分数(P<0.05);各寡糖组对断奶后第28天CD4 、CD8 T淋巴细胞百分数影响不显著(P>0.05);ABT组(34.33±5.03)在断奶后第7天较F M组(20.67±6.43)显著提高了淋巴结CD8 T淋巴细胞百分数(P<0.05);在断奶后第7天,FOS组(1.42±0.32)、MOS组(1.52±0.46)、F M组(1.51±0.30)淋巴结CD4 与CD8 比值显著(P<0.05)大于ABT组(0.71±0.03);在断奶后第28天,FOS组(1.36±0.21)和MOS组(1.34±0.16)脾脏CD4 与CD8 比值显著(P=0.01)大于ABT组(0.94±0.29),除此之外,各寡糖组CD4 与CD8 比值较寡糖组大(P>0.05),寡糖组间差异不显著。     

Thymus-independent Step in the Immune Response to Sheep Erythrocytes

THE nature of the T and B cell interaction in the response to erythrocyte antigens¹ has been an area of intense interest recently. Perhaps because of the influences of molecular biology, there has been a tendency to invoke specific mechanisms such as informational RNA and thymus specific immunoglobulins as mediators of this synergism. But once it was demonstrated that antigen specific receptors of immunoglobulin nature were on the surface of immune competent cells², it was possible to approach the problem more simply; that is from the viewpoint of control of protein synthesis and/or release of proteins from the cell surface. This communication outlines recent evidence concerning the role of non-specific mitogens in the control of antibody precursor (B cells) and antibody secreting cells.