miR-146a downregulates epidermal Langerhans cell-mediated antigen presentation / 中华微生物学和免疫学杂志

Objective:To investigate the role of miR-146a in regulating the homeostasis and function of epidermal Langerhans cells (LCs).Methods:Fresh and in vitro cultured epidermal LCs were isolated and purified by flow cytometry (FCM). The expression of miR-146a in LCs was detected by quantitative PCR (qPCR). The percentages of epidermal LCs in wild-type (WT) and miR-146a conventional knockout (miR-146a cKO) mice were analyzed by FCM. The expression of major histocompatibility complex Ⅱ (MHCⅡ) and co-stimulatory molecules (CD86 and CD80) was analyzed by FCM to evaluate the effect of miR-146a on the maturation of LCs. The percentage of Dextran-FITC + LCs was detected by FCM to evaluate the effect of miR-146a on the phagocytic function of LCs. In vitro and in vivo experiments were used to analyze the ability of miR-146a-deficient and -sufficient LCs to stimulate the proliferation of CD8 + OT-ⅠT cells and CD4 + OT-Ⅱ T cells. Results:The expression of miR-146a was significantly increased in mature LCs than in the freshly isolated LCs. There was no significant difference in the number of epidermal LCs between wild-type (WT) and miR-146a cKO mice. After a 48 h culture in vitro, the expression of MHCⅡ, CD86 and CD80 in the epidermal LCs of miR-146a cKO mice was similar to that of WT mice. Moreover, miR-146a deletion had no significant influence on antigen uptake by LCs. However, miR-146a deficiency enhanced the antigen-presenting ability of LCs that could stimulate the proliferation of OVA-specific CD8 + OT-Ⅰ T cells and CD4 + OT-Ⅱ T cells. Conclusions:miR-146a had no influence on the homeostasis, maturation and phagocytosis of LCs, but enhanced the antigen-presenting function.

Antigen presentation and T cell activation by dendritic cells in radiation damage / 中国辐射卫生

@#<b>Objective</b> To explore dendritic cells (DCs)-mediated antigen presentation for radiation-injured cells by using the <i>in vitro</i> cell co-culture technology to simulate the <i>in vivo </i>microenvironment of the lung tissue. <b>Methods</b> ⁶⁰Co γ-irradiated mouse lung epithelial cells (MLE-12) were cultured with bone marrow-derived DCs and/or splenic T lymphocytes for 48 hours. Flow cytometry was used to measure the expression levels of costimulatory molecules (CD80/86) and antigenic peptide recognition complexes (the major histocompatibility complex [MHC] class Ⅰ/Ⅱ) on DCs and T cell activation markers (CD69/28/152) as well as the numbers of CD4⁺ and CD8⁺ T cells. <b>Results</b> ⁶⁰Co γ irradiation significantly increased the apoptosis rate of MLE-12 cells in a dose-dependent manner, and significantly stimulated the expression of CD80/86 and MHC Ⅱ on DCs, without direct activation of T cells. After γ (6 Gy)-irradiated MLE-12 cells were co-cultured with DCs and T lymphocytes for 48 h, there were significant increases in the expression of CD69 and CD28 on T cells, the numbers of CD4⁺ and CD8⁺ T cells, and the expression of CD86 and MHC I on DCs, as compared with the control groups. <b>Conclusion</b> Radiation-injured cells can stimulate antigen presentation by DCs and activate T cells.

Tetrahedral DNA nanostructures synergize with MnO2 to enhance antitumor immunity via promoting STING activation and M1 polarization

Stimulator of interferon genes (STING) is a cytosolic DNA sensor which is regarded as a potential target for antitumor immunotherapy. However, clinical trials of STING agonists display limited anti-tumor effects and dose-dependent side-effects like inflammatory damage and cell toxicity. Here, we showed that tetrahedral DNA nanostructures (TDNs) actively enter macrophages to promote STING activation and M1 polarization in a size-dependent manner, and synergized with Mn2+ to enhance the expressions of IFN-β and iNOS, as well as the co-stimulatory molecules for antigen presentation. Moreover, to reduce the cytotoxicity of Mn2+, we constructed a TDN-MnO2 complex and found that it displayed a much higher efficacy than TDN plus Mn2+ to initiate macrophage activation and anti-tumor response both in vitro and in vivo. Together, our studies explored a novel immune activation effect of TDN in cancer therapy and its synergistic therapeutic outcomes with MnO2. These findings provide new therapeutic opportunities for cancer therapy.

Progress of phagosome maturation and function in neutrophil, macrophage and dendritic cell / 中华微生物学和免疫学杂志

Phagosomes undergo the fusion of early endosomes, late endosomes and lysosomes, and then degrade antigens and kill pathogenic microorganisms, which is called phagosome maturation. The functional differences of phagosomes after maturation in different immune cells lead to distinct characteristics on their processing of phagocytic antigens. It has been found that the antigen degradation ability of immune cells is opposite to their antigen presentation capacity through comparing the functional differences of phagosomes from neutrophils, macrophages and dendritic cells after antigens uptake. Among them, dendritic cells have the strongest antigen presentation capacity, followed by macrophages and neutrophils. The in-depth study of immune cell phagosome maturation and antigen presentation will provide new strategies for vaccine development and immunotherapy.

Direct interaction between Urease B of Helicobacter pylori and TLR2 negatively regulates immune fucntions of macrophages / 中华微生物学和免疫学杂志

Objective:To evaluate the regulatory role and potential mechanism of Urease B(UreB) on macrophages.Methods:Bone marrow-derived macrophages (M0) were stimulated by recombinant UreB protein and then flowcytometry and ELISA were used to detect the apoptosis, polarization and antigen presentation-related biomarkers expression. CD4 + T cell co-culture assay, CFSE stain and flowcytometry were used to evaluate the impacts of UreB on antigen presentation capacity of macrophages. Truncated UreB protein, NanoBiT assay and co-immunoprecipitation were used to identify the binding sites of UreB to TLR2. Results:UreB promoted apoptosis and skewed macrophages from M1 to M2 in the presence of M1-inducer LPS. Moreover, UreB inhibited the expression of antigen presentation biomarkers, MHCⅡ and CD86 on macrophages, and further inhibited the proliferation and IFN-γ expression of CD4 + T cells. Molecular analyses revealed that the binding between seven carboxy-terminal amino acid residues of UreB and TLR2 were required for the UreB-mediated inhibitory effects. Conclusions:The findings in this study demonstrate that UreB mainly depends on the binding between seven carboxy-terminal amino acid residues and TLR2 to perform immune-suppressive activities, and which may provide valuable information for the design and optimization of UreB-based vaccines against Helicobacter pylori infection.

Research progress on trogocytosis of immune cell in transplantation immunity / 器官移植

Trogocytosis is a process of exchanging part of the membrane fragment or cytoplasmic content of cells through direct contact, and it's an interaction mechanism that exists between cells. Immune cell can obtain some characteristics of other cells through trogocytosis, and the new cells generated through trogocytosis may play an important role in the induction of graft immune tolerance. In this article, the origin and development of research on cell trogocytosis, mechanism of cell trogocytosis and biological significance of trogocytosis of immune cell were reviewed.

N-glycosylation modification of heat shock protein gp96 affects its immunological function / 生物工程学报

N-glycosylation modification, one of the most common protein post-translational modifications, occurs in heat shock protein gp96. The purpose of this study is to investigate the effect of N-glycosylation modification on immunologic function of the recombinant gp96 using the mutant gp96 in N-glycosylation sites. Firstly, wild-type and mutant gp96 proteins were expressed by insect expression system and their glycosylation levels were detected. To determine the effect of N-glycosylation on gp96 antigen presentation function, the IFN-γ+ CD8+ T cells in gp96-immunized mice and secretion level of IFN-γ were examined by flow cytometry and ELISA. The ATPase activity of gp96 was further detected by the ATPase kit. Finally, the effect of N-glycosylation on adjuvant function of gp96 for influenza vaccine was investigated in immunized mice. It was found that total sugar content of mutant recombinant gp96 was reduced by 27.8%. Compared to the wild type recombinant gp96, mutations in N-glycosylation sites resulted in decreased antigen presentation ability and ATPase activity of gp96. Furthermore, influenza vaccine-specific T cell levels induced by mutant gp96 as adjuvant were dramatically reduced compared to those by wild type recombinant gp96. These results demonstrate that N-glycosylation modification is involved in regulation of ATPase activity and antigen presentation function of gp96, thereby affecting its adjuvant function. The results provide the technical bases for development of gp96- adjuvanted vaccines.

Conceptos básicos en inmunología de la reproducción: revisión narrativa de la bibliografía / Basic concepts in reproductive immunology: a narrative review of the literature

Resumen: ANTECEDENTES: La inmunología de la reproducción no es un área nueva: siempre ha estado relacionada con el aborto recurrente y con la falla repetida en la implantación, sobre todo en el contexto de una fertilización in vitro. Recientemente emergieron nuevos conceptos importantes que los ginecoobstetras deben considerar. OBJETIVO: Interrelacionar los conceptos básicos de inmunología, embriología y reproducción asistida para comprender mejor lo que la primera puede resolver y lo que no. METODOLOGÍA: Estudio retrospectivo efectuado con base en la búsqueda electrónica, llevada a cabo en febrero de 2020 en las bases de datos: PubMed y Google Scholar con los siguientes términos (MeSH): abortion, spontaneous/immunology; embryo implantation/immunology; HLA-c antigens/immunology; immune tolerance/immunology; immunity, maternally-acquired/immunology; uterus/immunology; killer cells, natural/immunology; placentation/immunology; receptors, kir/immunology; antigen presentation/genetics; antigen presentation/immunology; maternal-fetal exchange/genetics; maternal-fetal exchange/immunology. RESULTADOS: Se reunieron 289 artículos y se eliminaron 248 por no cumplir con los criterios de inclusión; solo se analizaron 41. Los artículos identificados sirvieron de base para actualizar la situación de la inmunología en el contexto de la medicina de la reproducción. Durante el proceso se revisaron otros artículos que sirvieran de soporte bibliográfico a los conceptos descritos en esta revisión. CONCLUSIONES: Debido al destacado interés en el estudio de la genética de los embriones, la medicina de la reproducción se enfocó más en ella y dejó de lado a la inmunología. Sin embargo, como la genética sigue sin poder explicar de manera adecuada las fallas en la implantación, la inmunología de la reproducción vuelve a cobrar impulso.

Abstract: BACKGROUND: Reproductive immunology is not a new area in reproductive medicine, it has always been related to recurrent miscarriage and repeated implantation failure, especially in the context of IVF. Recently, new concepts have emerged that are important for OBGYN specialists to keep in mind. OBJECTIVE: Interrelating the basic concepts of immunology, embryology and assisted reproduction to better understand what the former can and cannot solve. METHODOLOGY: Retrospective study based on the electronic search, carried out in February 2020, in the databases: PubMed and Google Scholar with the following terms (MeSH) The following MeSH terms were used: Abortion, Spontaneous/immunology; Embryo Implantation/immunology; HLA-C Antigens/immunology; Immune Tolerance/immunology; Immunity, Maternally-Acquired/immunology; Uterus/immunology; Killer Cells, Natural/immunology; Placentation/immunology; Receptors, KIR/immunology; Antigen Presentation/genetics; Antigen Presentation/immunology; Maternal-Fetal Exchange/genetics; Maternal-Fetal Exchange/immunology. RESULTS: 289 articles were collected, and 248 articles were deleted because they did not meet the inclusion criteria; only 41 were analyzed. The articles identified served as a basis for updating the status of immunology in the context of reproductive medicine. During the process, other articles were reviewed to serve as bibliographic support for the concepts described in this review. CONCLUSIONS: Due to the outstanding interest in the study of embryo genetics, reproductive medicine focused more on it and left immunology aside. However, since genetics still cannot adequately explain implantation failures, reproductive immunology is gaining momentum again.

Variability in the virulence of specific Mycobacterium tuberculosis clinical isolates alters the capacity of human dendritic cells to signal for T cells

BACKGROUND Once in the pulmonary alveoli, Mycobacterium tuberculosis (Mtb) enters into contact with alveolar macrophages and dendritic cells (DCs). DCs represent the link between the innate and adaptive immune system owing to their capacity to be both a sentinel and an orchestrator of the antigen-specific immune responses against Mtb. The effect that the virulence of Mtb has on the interaction between the bacilli and human DCs has not been fully explored. OBJECTIVE To evaluate the effect of Mtb virulence on human monocyte-derived DCs. METHODS We exposed human monocyte-derived DCs to Mtb clinical strains (isolated from an epidemiological Mtb diversity study in Mexico) bearing different degrees of virulence and evaluated the capacity of DCs to internalise the bacilli, control intracellular growth, engage cell death pathways, express markers for activation and antigen presentation, and expand to stimulate autologous CD4+ T cells proliferation. FINDINGS In the case of the hypervirulent Mtb strain (Phenotype 1, strain 9005186, lineage 3), we report that DCs internalise and neutralise intracellular growth of the bacilli, undergo low rates of apoptosis, and contribute poorly to T-cell expansion, as compared to the H37Rv reference strain. In the case of the hypovirulent Mtb strain (Phenotype 4, strain 9985449, lineage 4), although DCs internalise and preclude proliferation of the bacilli, the DCs also display a high level of apoptosis, massive levels of apoptosis that prevent them from maintaining autologous CD4+ T cells in a co-culture system, as compared to H37Rv. MAIN CONCLUSIONS Our findings suggest that variability in virulence among Mtb clinical strains affects the capacity of DCs to respond to pathogenic challenge and mount an immune response against it, highlighting important parallels to studies previously done in mouse models.

Two Distinct Subsets Are Identified from the Peritoneal Myeloid Mononuclear Cells Expressing both CD11c and CD115

To this date, the criteria to distinguish peritoneal macrophages and dendritic cells (DCs) are not clear. Here we delineate the subsets of myeloid mononuclear cells in the mouse peritoneal cavity. Considering phenotypical, functional, and ontogenic features, peritoneal myeloid mononuclear cells are divided into 5 subsets: large peritoneal macrophages (LPMs), small peritoneal macrophages (SPMs), DCs, and 2 MHCII⁺CD11c⁺CD115⁺ subpopulations (i.e., MHCII⁺CD11c⁺CD115⁺CD14⁻CD206⁻ and MHCII⁺CD11c⁺CD115⁺CD14⁺CD206⁺). Among them, 2 subsets of competent Ag presenting cells are demonstrated with distinct functional characteristics, one being DCs and the other being MHCII⁺CD11c⁺CD115⁺CD14⁻CD206⁻ cells. DCs are able to promote fully activated T cells and superior in expanding cytokine producing inflammatory T cells, whereas MHCII⁺CD11c⁺CD115⁺CD14⁻CD206⁻ cells generate partially activated T cells and possess a greater ability to induce Treg under TGF-β and retinoic acid conditions. While the development of DCs and MHCII⁺CD11c⁺CD115⁺CD14⁻CD206⁻ cells are responsive to the treatment of FLT3 ligand and GM-CSF, the number of LPMs, SPMs, and MHCII⁺CD11c⁺CD115⁺CD14⁺CD206⁺ cells are only influenced by the injection of GM-CSF. In addition, the analysis of gene expression profiles among MHCII⁺ peritoneal myeloid mononuclear cells reveals that MHCII⁺CD11c⁺CD115⁺CD14⁺CD206⁺ cells share high similarity with SPMs, whereas MHCII⁺CD11c⁺CD115⁺CD14⁻CD206⁻ cells are related to peritoneal DC2s. Collectively, our study identifies 2 distinct subpopulations of MHCII⁺CD11c⁺CD115⁺ cells, 1) MHCII⁺CD11c⁺CD115⁺CD14⁻CD206⁻ cells closely related to peritoneal DC2s and 2) MHCII⁺CD11c⁺CD115⁺CD14⁺CD206⁺ cells to SPMs.

miR-155 deficiency alleviates mouse skin inflammation through inhibiting the function of epidermal Langerhans cells / 中华微生物学和免疫学杂志

Objective@#To study the role of miR-155 in the development of allergic contact dermatitis in mice.@*Methods@#A mouse model of allergic contact dermatitis was induced by dinitrofluorobenzene (DNFB). Ear swelling was measured by caliper. Inflammatory changes in ears were observed with hematoxylin-eosin (HE) staining. Percentages of epidermal Langerhans cells (LC) and γδT cells in wild type (WT) and miR-155 knockout (miR-155KO) mice were detected by flow cytometry (FCM). Expression of major histocompatibility complex class Ⅱ (MHCⅡ) and costimulatory molecules on epidermal LC was tested by FCM to evaluate the maturation of LC in WT and miR-155KO mice. Fluorescein isothiocyanate-labeled Dextran (FITC-Dextran) was used to evaluate the phagocytotic abilities of LC by analyzing the percentages of FITC+ cells and mean fluorescence intensities (MFI) with FCM. Purified LC were co-cultured with antigen-specific CD4+ T cells sorted from OT Ⅱ mice for 72 h to analyze T cell proliferation by analyzing split peaks of CFSE. The co-culture system was stimulated with PMA and ionomycine, and blocked by Golgi stop at the same time to evaluate CD4+ T differentiation by analyzing the levels of IFN-γ and IL-17.@*Results@#Compared with WT mice, ear swelling was alleviated in miR-155KO mice. miR-155 deficiency had no significant influence on epidermal LC and γδT cells, but inhibited the maturation of in vitro-cultured LC through down-regulating the expression of MHC Ⅱ and costimulatory molecules. miR-155 deficiency did not affect the phagocytotic ability of LC, but inhibited the antigen-presenting ability of LC that could stimulate CD4+ T cell proliferation and differentiation.@*Conclusion@#miR-155 might play an important role in allergic contact dermatitis by enhancing the maturation and function of epidermal LC in mice.

Mecanismos de activación de las células T asesinas naturales invariantes (iNKT) / Mecanismos de ativação das células T assassinas naturais invariantes (iNKT) / Activation mechanisms of invariant natural killer T cells (iNKTs)

Aunque se ha logrado un conocimiento amplio acerca de las células T asesinas naturales (iNKT), aún no existe consenso sobre sus mecanismos de activación. Dichas células reconocen diferentes antígenos glicolipídicos presentados por medio de la molécula CD1d, los cuales pueden ser endógenos, exógenos derivados de organismos como bacterias y sintéticos desarrollados para aplicaciones clínicas. Existe mucho interés en entender cómo estas distintas variantes glicolipídicas inducen diferentes tipos de polarización, pero ha sido muy difícil llegar a un consenso, debido a que la respuesta depende de varios factores como la naturaleza, la internalización y el procesamiento de los glicolípidos. Además, la activación de las células iNKT la determinan el tipo y estado de activación de la célula presentadora de antígeno, las moléculas coestimuladoras, los mecanismos de transactivación y la localización de los complejos CD1d-glicolípido en distintas microrregiones de la membrana plasmática, como las balsas lipídicas. Esta revisión explora la evidencia sobre los factores que afectan la activación de las células iNKT con el fin de entender su potencial inmunomodulador.

A great amount of knowledge on natural killer T cells (iNKTs) is now available, but a consensus about their activation mechanisms has not been reached. These cells recognize different glycolipid antigens through the CD1d molecule. Such antigens may be endogenous, derived from bacteria (foreign) and synthetic, the latter have been developed for clinical applications. There exists much interest in understanding how these different glycolipid compounds induce different types of polarization, but it has been difficult to reach a consensus due to the fact that responses depend on different factors such as: the nature of the molecule, the internalization process and the presentation of the glycolipids. Moreover, activation of iNKT cells is determined by the type and state of the antigen presenting cell, the co-stimulatory molecules, the transactivation mechanisms and the location of the glycolipid-CD1d complexes on the plasma membrane, such as the lipid rafts. This review explores the evidence about the factors that affect activation of iNKT cells in order to understand their immune-modulatory potential.

Ainda que se conseguiu um conhecimento amplo a respeito das células T assassinas naturais (iNKT), ainda não existe consenso sobre seus mecanismos de ativação. Ditas células reconhecem diferentes antígenos glicolipídicos apresentados por meio da molécula CD1d, os quais pode ser: endógenos, exógenos derivados de organismos como bactérias e sintéticos desenvolvidos para aplicações clínicas. Existe muito interesse em entender como estas diferentes variantes glicolipídicas induzem diferentes tipos de polarização, mas foi muito difícil chegar a um consenso, devido a que a resposta depende de vários fatores como a natureza, a internalização e o processamento dos glicolípidos. Ademais, a ativação das células iNKT a determinam o tipo e estado de ativação da célula apresentadora de antígeno, as moléculas co-estimuladoras, os mecanismos de transativação e a localização dos complexos CD1d-glicolípido em diferentes microrregiões da membrana plasmática, como as balsas lipídicas. Esta revisão explora a evidência sobre os fatores que afetam a ativação das células iNKT com o fim de entender seu potencial imunomodulador.

Vanilloid Receptor 1 Agonists, Capsaicin and Resiniferatoxin, Enhance MHC Class I-restricted Viral Antigen Presentation in Virus-infected Dendritic Cells

DCs, like the sensory neurons, express vanilloid receptor 1 (VR1). Here we demonstrate that the VR1 agonists, capsaicin (CP) and resiniferatoxin (RTX), enhance antiviral CTL responses by increasing MHC class I-restricted viral antigen presentation in dendritic cells (DCs). Bone marrow-derived DCs (BM-DCs) were infected with a recombinant vaccinia virus (VV) expressing OVA (VV-OVA), and then treated with CP or RTX. Both CP and RTX increased MHC class I-restricted presentation of virus-encoded endogenous OVA in BM-DCs. Oral administration of CP or RTX significantly increased MHC class I-restricted OVA presentation by splenic and lymph node DCs in VV-OVA-infected mice, as assessed by directly measuring OVA peptide SIINFEKL-Kb complexes on the cell surface and by performing functional assays using OVA-specific CD8 T cells. Accordingly, oral administration of CP or RTX elicited potent OVA-specific CTL activity in VV-OVA-infected mice. The results from this study demonstrate that VR1 agonists enhance anti-viral CTL responses, as well as a neuro-immune connection in anti-viral immune responses.

MHC structure and function – antigen presentation. Part 1 / Estrutura do MHC e função – apresentação de antígenos. Parte 1

The setting for the occurrence of an immune response is that of the need to cope with a vast array of different antigens from both pathogenic and non-pathogenic sources. When the first barriers against infection and innate defense fail, adaptive immune response enters the stage for recognition of the antigens by means of extremely variable molecules, namely immunoglobulins and T-cell receptors. The latter recognize the antigen exposed on cell surfaces, in the form of peptides presented by the HLA molecule. The first part of this review details the central role played by these molecules, establishing the close connection existing between their structure and their antigen presenting function.

O cenário no qual ocorre a resposta imune é o da necessidade de fazer frente a uma vasta gama de antígenos diferentes, de fontes patogênicas e não patogênicas. Quando as primeiras barreiras contra infecção e a defesa inata falham, a resposta imune adaptativa entra em campo, para efetuar o reconhecimento dos antígenos, utilizando, para esse fim, moléculas extremamente variáveis, que são as imunoglobulinas e os receptores de células-T. Estes últimos reconhecem o antígeno, exposto na superfície das células como peptídeo apresentado pelas moléculas HLA. A primeira parte desta revisão detalha o papel central dessas moléculas, estabelecendo a conexão que existe entre a estrutura e a função de apresentação de antígenos.

MHC structure and function − antigen presentation. Part 2 / Estrutura do MHC e função − apresentação de antígenos. Parte 2

The second part of this review deals with the molecules and processes involved in the processing and presentation of the antigenic fragments to the T-cell receptor. Though the nature of the antigens presented varies, the most significant class of antigens is proteins, processed within the cell to be then recognized in the form of peptides, a mechanism that confers an extraordinary degree of precision to this mode of immune response. The efficiency and accuracy of this system is also the result of the myriad of mechanisms involved in the processing of proteins and production of peptides, in addition to the capture and recycling of alternative sources aiming to generate further diversity in the presentation to T-cells.

A segunda parte desta revisão trata das moléculas e processos envolvidos no processamento e apresentação dos fragmentos antigênicos ao receptor de célula-T. Apesar de variar a natureza do antígeno apresentado, a classe mais significativa é a das proteínas, as quais são processadas dentro da célula para enfim serem reconhecidas na forma de peptídeos, o que confere um grau extraordinário de precisão a essa forma de resposta imune. A eficiência e a precisão desse sistema se devem também à miríade de mecanismos envolvidos no processamento de proteínas e produção de peptídeos, além da captura e reciclagem de fontes alternativas de antígenos com o objetivo de gerar ainda maior diversidade na apresentação à célula-T.

murine colonic adenocarcinoma cell line CT26.WT / 实用医学杂志

Objective To explore the antigen presentation of CT26.WT via intra-peritoneal injection. Methods The intra-peritoneal injection model was made via injecting cell suspensions in mice. The spleen was isolated from BALB/c mice toco-culture with CT26.WT to detect tumor-killed ability. Phenotype identification methods and CCK8 massy were used to measure the ability of antigen presentation and stimulate T lymphocyte proliferation. IHC was used to detect the expression of B7H4 in normal and tumor tissues. Results Along with the extension of intra-peritoneal injection, the surviving number of cells was increased, contrary to the apoptosis. DC cells failed in maturation and impaired in stimulating T lymphocyte proliferation. B7H4 was higher in tumor tissues. Conclusions With the extension of intra-peritoneal injection, the mature DC cells were scared in number, resulting in the impairement of antigen-presentation. Moreover, the higher B7H4 expression in tumor tissues led to the lack of second signals which may stimulate T cells. Consequently, the ability of T cells in killing tumor cells was decreased so that they escape immunosurveillance.

Live bacterial vaccine vectors: An overview

Genetically attenuated microorganisms, pathogens, and some commensal bacteria can be engineered to deliver recombinant heterologous antigens to stimulate the host immune system, while still offering good levels of safety. A key feature of these live vectors is their capacity to stimulate mucosal as well as humoral and/or cellular systemic immunity. This enables the use of different forms of vaccination to prevent pathogen colonization of mucosal tissues, the front door for many infectious agents. Furthermore, delivery of DNA vaccines and immune system stimulatory molecules, such as cytokines, can be achieved using these special carriers, whose adjuvant properties and, sometimes, invasive capacities enhance the immune response. More recently, the unique features and versatility of these vectors have also been exploited to develop anti-cancer vaccines, where tumor-associated antigens, cytokines, and DNA or RNA molecules are delivered. Different strategies and genetic tools are constantly being developed, increasing the antigenic potential of agents delivered by these systems, opening fresh perspectives for the deployment of vehicles for new purposes. Here we summarize the main characteristics of the different types of live bacterial vectors and discuss new applications of these delivery systems in the field of vaccinology.

Phenotypes,distribution, and morphological features of antigen-presenting cells in the normal murine iris / 中华实验眼科杂志

Background The conventional study of antigen-presenting cells(APCs)in eye relies on in vitro histoimmunochemistry,but its outcome is influenced by many factors.The anterior chamber injection of fluoresceinmarked antibody was used as a new approach before,however,it is liable to lead to injury of cornea.The intravitreal injection of fluorescein-labeled antibody may be important for the in vivo study of the phenotype features of APCs in iris,which is significant for evaluating the function of APCs in immune homeostasis.Objective This study was to investigate the phenotype characters,distribution and morphology of different types of APCs in the normal murine iris.Methods Fifty-one SPF female BALB/c mice(from 6-to 8-week old)were randomized into 17 groups according to the injection of different antibodies.Alexa Fluor 594 or Alexa Fluor 488-tagged ovalbumin (OVA),CD11 c,major histocompatibility complex Ⅱ (MHC-Ⅱ),F4/80,B7-1 and B7-2 monoclonal antibodies or mixtures of two antibodies (2.0 μl)were intravitreally injected at 0.5 mm far from corneal limbus with microneedle under the biomicroscope.The iris tissues were isolated 24 hours after injection.The phenotype characters,precise distribution and morphology of different types of APCs were identified by epifluorescence microscope and laser confocal microscope.In vitro staining was also performed to validate the in vivo staining results.Results After in vivo staining via intravitreal injection,the cell positive for OVA as well as MHC-Ⅱ,F4/80,CD11 c,B7-1 and B7-2 were exhibited with the regular networkline appearance throughout the normal murine iris.Positive cells tagged with Alexa Fluor 594 or Alexa Fluor 488 presented the red or green fluorescence.Double-fluorescein staining showed that about 90％ of F4/80+ cells were OVA+,and MHC-Ⅱ was expressed in about 60％ of F4/80+ cells and CD11c+cells,and about 35％ of F4/80+ cells and CD1 1 c+ cells expressed B7-1 and B7-2 simultaneously,and over 70％ of OVA+ cells were positive to MHC-Ⅱ.These labeled cells were identified as two populations based on their shape.One type was dendritiform cell (DC) with a small cell body and many long dendrites,including OVA+,CD1 1 c+,F4/80+ cells and MHC-Ⅱ + cells ; and the other types were polymorphic population being round,pleomorphic or irregular shape with a large cell body and a few short dendrities,including B7-1 + and B7-2+ cells.Conclusions In vivo intravitreal injection of labeled antibodies can be adapted to visualize the labeled cells in the murine iris.APCs with distinct morphologies,phenotypes and distribution may contribute to the immunologically privileged feature and inflammation of the eye.

Lumazine synthase protein cage nanoparticles as antigen delivery nanoplatforms for dendritic cell-based vaccine development

PURPOSE: Protein cages are promising nanoplatform candidates for efficient delivery systems due to their homogenous size and structure with high biocompatibility and biodegradability. In this study, we investigate the potential of lumazine synthase protein cage as an antigen delivery system to dendritic cells (DCs), which induce antigen-specific T cell proliferation. MATERIALS AND METHODS: Ovalbumin (OVA) peptides OT-1 (SIINFEKL) and OT-2 (ISQAVHAAHAEINEAGR) were genetically inserted to lumazine synthase and each protein cage was over-expressed in Escherichia coli as a soluble protein. The efficiency of antigen delivery and the resulting antigen-specific T cell proliferation by DCs was examined in vitro as well as in vivo. RESULTS: We successfully generated and characterized OVA peptides carrying lumazine synthase protein cages. The OT-1 and OT-2 peptides carried by lumazine synthases were efficiently delivered and processed by DCs in vitro as well as in vivo, and induced proliferation of OT-1-specific CD8+T cells and OT-2-specific CD4+T cells. CONCLUSION: Our data demonstrate the potential of lumazine synthase protein cage being used as a novel antigen delivery system for DC-based vaccine development in future clinical applications.

Metformin Suppresses MHC-Restricted Antigen Presentation by Inhibiting Co-Stimulatory Factors and MHC Molecules in APCs

Metformin is widely used for T2D therapy but its cellular mechanism of action is undefined. Recent studies on the mechanism of metformin in T2D have demonstrated involvement of the immune system. Current immunotherapies focus on the potential of immunomodulatory strategies for the treatment of T2D. In this study, we examined the effects of metformin on the antigen-presenting function of antigen-presenting cells (APCs). Metformin decreased both MHC class I and class II-restricted presentation of OVA and suppressed the expression of both MHC molecules and co-stimulatory factors such as CD54, CD80, and CD86 in DCs, but did not affect the phagocytic activity toward exogenous OVA. The class II-restricted OVA presentation-regulating activity of metformin was also confirmed using mice that had been injected with metformin followed by soluble OVA. These results provide an understanding of the mechanisms of the T cell response-regulating activity of metformin through the inhibition of MHC-restricted antigen presentation in relation to its actions on APCs.