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Concept: Cell-mediated immunity

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TOLL-like receptor (TLR) ligands activate both innate and adaptive immune cells, while modulating the cellular immune response. The outer membrane protein (OMP) from Neisseria meninigitidis, PorB, is a naturally occurring TLR2 ligand and functions as an adjuvant. Here, we demonstrate that PorB increases the level of OVA in the endo-/lysosomal cellular compartment of BMDCs, increases antigen presenting cell (APC) trafficking to draining lymph nodes, and enhances antigen cross-presentation. PorB is capable of mounting an antigen specific T cell response by efficiently stimulating antigen cross-presentation in vivo and in vitro assessed by BMDC OT-I cocultivation assays. The enhanced antigen cross-presentation and the increased APC recruitment to secondary lymphoid tissues expand the scope of known adjuvant effects of PorB on the immune system. Our findings lead to a better understanding of how TLR-ligand based adjuvants can alter and modulate immune responses.

Concepts: Immune system, Antibody, Bacteria, Humoral immunity, Adaptive immune system, Antigen, Dendritic cell, Cell-mediated immunity

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Exposure to dim light at night (dLAN) disrupts natural light/dark cycles and impairs endogenous circadian rhythms necessary to maintain optimal biological function, including the endocrine and immune systems. We have previously demonstrated that white dLAN compromises innate and cell mediated immune responses in adult Siberian hamsters (Phodopus sungorus). We hypothesized that dLAN has transgenerational influences on immune function. Adult male and female Siberian hamsters were exposed to either dark nights (DARK) or dLAN (~5 lux) for 9 weeks, then paired in full factorial design, mated, and thereafter housed under dark nights. Offspring were gestated and reared in dark nights, then tested as adults for cell-mediated and humoral immunity. Maternal exposure to dLAN dampened delayed type hypersensitivity (DTH) responses in male offspring. Maternal and paternal exposure to dLAN reduced DTH responses in female offspring. IgG antibodies to a novel antigen were elevated in offspring of dams exposed to dLAN. Paternal exposure to dLAN decreased splenic endocrine receptor expression and global methylation in a parental sex-specific manner. Together, these data suggest that exposure to dLAN has transgenerational effects on endocrine-immune function that may be mediated by global alterations in the epigenetic landscape of immune tissues.

Concepts: Immune system, Antibody, Hypersensitivity, Immunology, Humoral immunity, Immunity, Adaptive immune system, Cell-mediated immunity

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A core feature of protective T cell responses to infection is the robust expansion and diversification of naïve antigen-specific T cell populations into short-lived effector and long-lived memory subsets. By in vivo fate mapping, we find a striking variability of immune responses derived from individual CD8(+) T cells and show that robust acute and recall immunity requires the initial recruitment of multiple precursors. Unbiased mathematical modeling identifies the random integration of multiple differentiation and division events as the driving force behind this variability. Within this probabilistic framework, cell fate is specified along a linear developmental path that progresses from slowly proliferating long-lived to rapidly expanding short-lived subsets. These data provide insights into how complex biological systems implement stochastic processes to guarantee robust outcomes.

Concepts: Immune system, Mathematics, Humoral immunity, Immunity, Integral, Probability, Stochastic process, Cell-mediated immunity

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Pompe Disease is an inherited neuromuscular disease due to deficiency of lysosomal acid alpha-glucosidase (GAA) leading to glycogen accumulation in muscle and motoneurons. Cardiopulmonary failure in infancy leads to early mortality and GAA enzyme replacement therapy (ERT) results in improved survival, reduction of cardiac hypertrophy and developmental gains. However, many children have progressive ventilatory insufficiency and need additional support. Preclinical work shows that gene transfer restores phrenic neural activity and corrects ventilatory deficits. Here we present 180-day safety and ventilatory outcomes for five ventilator-dependent children in a phase I/II clinical trial of AAV-mediated GAA gene therapy (rAAV1-hGAA) following intradiaphragmatic delivery. We assessed if rAAV1-hGAA results in acceptable safety outcome and detectable functional changes, using general safety measures, immunological studies and pulmonary functional testing. All subjects required chronic, full-time mechanical ventilation due to respiratory failure that was unresponsive to both ERT and pre-operative muscle conditioning exercises. After receiving a dose of either 1 x 1012 vg (n=3) or 5 x 1012 vg (n=2) of rAAV1-hGAA, the subjects' unassisted tidal volume was significantly larger (median, IQR: 28.8% increase, 15.2-35.2, p<0.05). Further most patients tolerated appreciably longer periods of unassisted breathing (425% increase, 103-851%, p=0.08). Gene transfer did not improve maximal inspiratory pressure. Expected levels of circulating antibodies and no T cell-mediated immune responses to the vector (capsids) were observed. One subject demonstrated a slight increase in anti-GAA antibody that was not considered clinically significant. These results indicate that rAAV1-hGAA was safe and may lead to modest improvements in volitional ventilatory performance measures. Evaluation of the next five patients will determine if earlier intervention can further enhance the functional benefit.

Concepts: Immune system, Antibody, Virus, Immunology, Muscle, Glycogen storage disease type II, Cell-mediated immunity, Acid alpha-glucosidase

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Oral lichen planus (OLP) is generally accepted to be a T cell-mediated chronic inflammatory disease with an unclear pathogenesis. There have been numerous studies on the proliferation and apoptosis of T cells in situ. In contrast, research on the proliferation and apoptosis of peripheral blood mononuclear cells (PBMCs) in patients with OLP is rare. The aim of the present study was to investigate the proliferation and apoptosis of PBMCs in patients with OLP. PBMCs were isolated from 20 patients with reticular OLP, 20 patients with atrophic-erosive OLP, and 20 healthy volunteers. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-2,5-tetrazolium bromide assays were performed to investigate the proliferation of PBMCs, and caspase-3 colorimetric assays were performed to investigate the apoptosis of PBMCs. The proliferation rate of PBMCs in atrophic-erosive OLP subjects was significantly higher than that in both healthy (P < 0.05) and reticular OLP (P < 0.05) subjects. In contrast, the proliferation rate of PBMCs in reticular OLP subjects was significantly lower than that in healthy subjects (P < 0.05). The apoptosis rates of PBMCs in OLP subjects (P < 0.05) and atrophic-erosive OLP subjects (P < 0.05) were significantly lower than the apoptosis rate in the healthy group. Our findings reinforce the view that T cell-mediated immune responses play a critical role in the pathogenesis of OLP. It can reasonably be concluded that these abnormalities are linked to the presence of inflammatory infiltrates.

Concepts: Immune system, Inflammation, White blood cell, Blood, PBMC, Cell-mediated immunity, Lichen planus, Mucosal lichen planus

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Currently, killed-virus and modified-live porcine reproductive and respiratory syndrome virus (PRRSV) vaccines are used to control PRRS. However, both types of vaccines have inherent drawbacks and the development of novel PRRSV vaccines is urgently needed. Previous studies have suggested that yeast possesses adjuvant activities and has been used as an expression vehicle to elicit immune responses to foreign antigens. In this report, the recombinant Kluyveromyces lactis (K.lactis) expressing GP5 of HP-PRRSV (Yeast-GP5) was generated and the immune responses were analyzed in mice. Our results showed that intestinal mucosal PRRSV-specific sIgA antibody and higher levels of IFN-γ in spleen CD4+ and CD8+ T cells were induced by oral administration of Yeast-GP5. Yeast-GP5 administrated subcutaneously evoked vigorous cell-mediated immunity, and PRRSV-specific lymphocyte proliferation and IFN-γ secretion were detected in splenocytes of mice. These results suggest that Yeast-GP5 might have the potential to be a vaccine candidate for PRRSV in the future.

Concepts: Immune system, Antibody, Bacteria, Vaccination, Immunology, Humoral immunity, Antigen, Cell-mediated immunity

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Ebola virus (EBOV) is one of the most lethal filoviruses, with mortality rates of up to 90% in humans. Previously, we demonstrated 100% and 50% survival of EBOV-infected cynomologus macaques with a combination of 3 EBOV-GP-specific monoclonal antibodies (ZMAb) administered at 24 or 48 hours post-exposure, respectively. The survivors demonstrated EBOV-GP-specific humoral and cell-mediated immune responses. In order to evaluate whether the immune response induced in NHPs during the ZMAb treatment and EBOV challenge is sufficient to protect survivors against a subsequent exposure, animals that survived the initial challenge were rechallenged at 10 or 13 weeks after the initial challenge. The animals rechallenged at 10 weeks all survived whereas 4 of 6 animals survived a rechallenge at 13 weeks. The data indicate that a robust immune response was generated during the successful treatment of EBOV-infected NHPs with EBOV, which resulted in sustained protection against a second lethal exposure.

Concepts: Immune system, Antibody, Organism, Infection, Immunology, Humoral immunity, Immunity, Cell-mediated immunity

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In recent decades, accumulating evidence from both animal and clinical studies has suggested that a sufficiently activated immune system may strongly augment various types of cancer treatment, including photodynamic therapy (PDT). Through the generation of reactive oxygen species, PDT eradicates tumors by triggering localized tumor damage and inducing anti-tumor immunity. As the major component of anti-tumor immunity, the involvement of a cell-mediated immune response in PDT has been well investigated in the past decade, whereas the role of humoral immunity has remained relatively unexplored. In the present investigation, using the photosensitizer BAM-SiPc and the CT26 tumor-bearing BALB/c mouse model, it was demonstrated that both cell-mediated and humoral adaptive immune components could be involved in PDT. With a vascular PDT (VPDT) regimen, BAM-SiPc could eradicate the tumors of ∼70% of tumor-bearing mice and trigger an anti-tumor immune response that could last for more than 1 year. An elevation of Th2 cytokines was detected ex vivo after VPDT, indicating the potential involvement of a humoral response. An analysis of serum from the VPDT-cured mice also revealed elevated levels of tumor-specific antibodies. Moreover, this serum could effectively hinder tumor growth and protect the mice against further re-challenge in a T-cell-dependent manner. Taken together, these results show that the humoral components induced after BAM-SiPc-VPDT could assist the development of anti-tumor immunity.Cellular & Molecular Immunology advance online publication, 21 September 2015; doi:10.1038/cmi.2015.84.

Concepts: Immune system, Antibody, Cancer, Immunology, Humoral immunity, Immunity, Adaptive immune system, Cell-mediated immunity

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Adjuvants are essential components in vaccine formulations to induce robust immunity against pathogens. The most widely used adjuvants in human vaccines are aluminum salts, that can effectively elicit a T helper type-2 (Th2)-biased humoral immune response for producing a high antibody titer but with a limited cellular immune response. Biocompatible calcium phosphate nanoparticles (CaP-NPs) with tunable characteristics have potentials to function as adjuvants for inducing more balanced T helper type-1 (Th1) and Th2 immune responses. Areas covered: Here we review the preparation procedures and characteristics of CaP-NPs. The process can be well-controlled and readily scaled up. Antigen loading can take place as encapsulation during the particle formation or as passive adsorption post particle formation. Different modalities of immunogens were tested with CaP-NPs as adjuvants. The possible mechanisms of the CaP-NP-based adjuvants are discussed. Expert commentary: With good adjuvant effects and safety profiles, CaP-NPs have the potentials to be a new generation vaccine adjuvant. A more in-depth understanding of the mechanisms of their adjuvanticity could facilitate the process optimization for making adjuvants with preferred characteristics. Inter-disciplinary collaborations are essential for testing the biocompatible CaP-NPs in human vaccines for clinical development and eventually for use in marketed vaccines.

Concepts: Immune system, Antibody, Immunology, Humoral immunity, Immunity, Antigen, Immunologic adjuvant, Cell-mediated immunity

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To date, most of the licensed vaccines for mucosal delivery are based on live-attenuated viruses which carry the risk of regaining their pathogenicity. Therefore, the development of efficient nonviral vectors allowing the induction of potent humoral and cell-mediated immunity is regarded as an imperative scientific challenge as well as a commercial breakthrough for the pharma industries. For a successful translation to the clinic, such nanocarriers should protect the antigens from mucosal enzymes, facilitate antigen uptake by microfold cells and allow the copresentation of robust, safe for human use, mucosal adjuvants to antigen-presenting cells. Finally, the developed formulations should exhibit accuracy regarding the administered dose, a major drawback of mucosal vaccines in comparison with parenteral ones.

Concepts: Immune system, Antibody, Protein, Virus, Vaccination, Humoral immunity, Antigen, Cell-mediated immunity