Targeting antigen to bone marrow stromal cell‐2 expressed by conventional and plasmacytoid dendritic cells elicits efficient antigen presentation

Bone marrow stromal cell‐2 (BST‐2) has major roles in viral tethering and modulation of interferon production. Here we investigate BST‐2 as a receptor for the delivery of antigen to dendritic cells (DCs). We show that BST‐2 is expressed by a panel of mouse and human DC subsets, particularly under inflammatory conditions. The outcome of delivering antigen to BST‐2 expressed by steady state and activated plasmacytoid DC (pDC) or conventional CD8⁺ and CD8^? DCs was determined. T‐cell responses were measured for both MHC class I (MHCI) and MHC class II (MHCII) antigen presentation pathways in vitro. Delivering antigen via BST‐2 was compared with that via receptors DEC205 or Siglec‐H. We show that despite a higher antigen load and faster receptor internalisation, when antigen is delivered to steady state or activated pDC via BST‐2, BST‐2‐targeted activated conventional DCs present antigen more efficiently. Relative to DEC205, BST‐2 was inferior in its capacity to deliver antigen to the MHCI cross‐presentation pathway. In contrast, BST‐2 was superior to Siglec‐H at initiating either MHCI or MHCII antigen presentation. In summary, BST‐2 is a useful receptor to target with antigen, given its broad expression pattern and ability to access both MHCI and MHCII presentation pathways with relative efficiency.     

Communication between human mast cells and CD4+ T cells through antigen‐dependent interactions

Mast cells (MCs) are immune cells residing in tissues where pathogens are first encountered. It has been indicated that MCs might also be involved in setting the outcome of T‐cell responses. However, little is known about the capacity of human MCs to express MHC class II and/or to capture and present antigens to CD4⁺ T cells. To study the T‐cell stimulatory potential of human MCs, CD34⁺ stem cell derived MCs were generated. These cells expressed HLA‐DR when stimulated with IFN‐γ, and, importantly, presented peptide and protein for activation of antigen‐specific CD4⁺ T cells. The interplay between MC and T cell led to increased HLA‐DR expression on MCs. MCs were present in close proximity to T cells in tonsil and expressed HLA‐DR and CD80, indicating their ability to present antigens to CD4⁺ T cells in T‐cell areas of human LNs. Our data show that MCs can present native antigens to human CD4⁺ T cells and that HLA‐DR expressing MCs are present in tonsil tissue, indicating that human MCs can directly activate T cells and provide a rationale to study the potential of MCs to prime and/or skew human T‐cell responses.     

The “Patient Presentation:” The Evolutions of a Practice,of Its Objectives,and of Its Effects on Training

ObjectivesThrough a review of the history of patient presentations and changes to this system, we will try to situate its function and challenges, particularly with regard to its effects on the training of professionals. The articulation of these effects with the necessary ethical questions raised by this practice will be highlighted.MethodThe review of the French-language literature on the practice of patient presentations makes it possible to note its permanence since the origins of psychiatry, its multiple challenges, the risks it has encountered over the course of its history, and the consequent changes that have resulted from it. A personal experience of patient presentations at the Centre Hospitalier Sainte-Anne over more than twenty years allows us to emphasize the essential elements of this exercise.ResultsPracticed mainly in recent years by psychoanalysts, the system of patient presentations has been considerably modified by taking into account the registers of language, speech, and the transference. The control or supervisory dimension also becomes a central function of this practice. This subversion makes it possible to significantly advance the controversies that run through its history. It also highlights its instructive effects, which, far from being limited to a pedagogical demonstration to inexperienced practitioners, involve practitioners in a place that allows them to question their position as well as their action, in their daily practice.DiscussionThe diversity of patient presentation systems, the variety of circumstances that led to their implementation in hospital services, the variable place they occupy in the organization of care, and the unequal interest that they can arouse on the part of healthcare teams justify identifying the essential benchmarks that make this practice so specific. The articulation of the three distinct places of the patient, the examiner, and the public – through the distinct knowledge attributed to each of these places – makes it possible to propose a reading of the structure of these presentations to examine their effects on the training of practitioners, as well as on clinical research.ConclusionIf clinical practice is developed and transmitted “at the patient's bedside” and in the dialogue between practitioners, then the presentation of the patient is one of the key places where clinical practice is developed. The ethical questions it raises thus constitute an opportunity for a renewal of the psychiatric clinic and its practice.     

A Role for MHC Class II Antigen Processing in B Cell Development

For mature B cells, the encounter with foreign antigen results in the selective expansion of the cells and their differentiation into antibody secreting cells or memory B cells. The response of mature B cells to antigen requires not only antigen binding to and signaling through the B cell antigen receptor (BCR) but also the processing and presentation of the BCR bound antigen to helper T cells. Thus, in mature B cells, the ability to process and present antigen to helper T cells plays a critical role in determining the outcome of antigen encounter. In immature B cells, the binding of antigen results in negative selection of the B cell, inducing apoptosis, anergy or receptor editing. Negative selection of immature B cells requires antigen induced signaling through the BCR, analogous to the signaling function of the BCR in mature B cells. However, the role of class II antigen processing and presentation in immature B cells is less well understood. Current evidence indicates that the ability to process and present antigen bound to the BCR is a late acquisition of developing B cells, suggesting that during negative selection B cells may not present BCR bound antigen and interact with helper T cells However, the expression of class II molecules is an early acquisition of B cells and recent evidence indicates that the expression of class II molecules early in development is required for the generation of long lived mature B cells. Here we review our current understanding of the processing and presentation of antigen by mature B cells and the role for antigen processing and class II expression during B cell development.     

Antigen-Antibody Complex as Therapeutic Vaccine for Viral Hepatitis B

In a previous study, hepatitis B surface antigen (HBsAg) complexed to human anti-HBs immunoglobulins (HBIG) in excess of HBsAg was used as therapeutic vaccine to treat chronic hepatitis B patients and promising results were obtained. To study the mechanisms of this approach, mice were immunized with HBsAg or IC (immunogenic complex, i.e. HBsAg complexed with mouse polyclonal anti-HBs). Studies indicate that IC induced enhanced immune responses by increasing uptake of HBsAg through Fc receptors on antigen presenting cells and modulated HBsAg processing and presentation. This modulation led to stimulation of T cell responses, and increased production of IL-2 and IFN-γ. Assay for antibody subclasses showed that higher ratio of IgG 2a was observed in the IC immunized group, which correlated with the production of lymphokine pattern. When alum was used as the adjuvant, though antibody response was enhanced, production of cytokines decreased. When DNA from a recombinant plasmid was added to IC as an adjuvant, the liter of anti-HBs was significantly higher than those in mice immunized only with the DNA or the IC. Since DNA immunization can induce both cellular and humoral immune responses, combined immunization using IC and DNA might serve as another type of therapeutic vaccine for viral hepatitis B.     

泛素编辑蛋白A20对呼吸机相关性肺炎患者单核细胞活性的影响

目的观察并分析泛素编辑蛋白A20对呼吸机相关性肺炎(ventilator associated pneumonia,VAP)患者单核细胞活性的影响。方法入选2019年2月至9月在郑州大学第一附属医院诊断为VAP的患者24例(VAP组)和健康对照12例(对照组)。分离VAP组外周血单个核细胞(peripheral blood mononuclear cells,PBMCs)、感染部位和非感染部位的支气管肺泡灌洗液(bronchial alveolar lavage fluid,BALF)及对照组PBMCs,检测CD14⁺单核细胞中A20水平。纯化VAP患者CD14⁺单核细胞和CD4⁺T细胞,使用A20 siRNA转染CD14⁺单核细胞。转染的CD14⁺单核细胞与自体CD4⁺T细胞直接/间接接触共培养,检测CD4⁺T细胞分泌干扰素-γ(interferon-γ,IFN-γ)和白细胞介素-17(interleukin-17,IL-17)水平。转染的CD14⁺单核与NCI-H889细胞直接/间接共培养,检测细胞毒性、分泌细胞因子、颗粒酶B水平及肿瘤坏死因子相关凋亡诱导配体(tumor necrosis factor-related apoptosis inducing ligand,TRAIL)、FasL配体(Fas ligand,FasL)水平。组间比较采用成组t检验或SNK-q检验。结果VAP组外周血CD14⁺A20⁺细胞比例高于对照组[(62.61±15.33)%vs.(47.13±11.82),P<0.05],A20平均荧光强度(mean fluorescence intensity,MFI)亦高于对照组[(227.9±64.18)vs.(178.2±58.62),P<0.05]。VAP组感染部位BALF中的CD14⁺A20⁺细胞比例高于未感染部位[(66.14±19.62)%vs.(52.52±13.71)%,P<0.05],A20 MFI亦高于未感染部位[(268.0±72.56)vs.(197.4±60.01),P<0.05]。A20 siRNA转染的VAP患者外周血和BALF中的CD14⁺单核细胞与自体CD4⁺T细胞直接接触共培养后,CD4⁺T细胞分泌IFN-γ和IL-17的细胞比例均高于未转染和siRNA转染(P<0.05),但间接接触共培养中,CD4⁺IFN-γ⁺和CD4⁺IL-17⁺细胞比例在未转染、对照siRNA转染和A20 siRNA转染中的差异无统计学意义(P>0.05)。A20 siRNA转染的VAP患者外周血和BALF中的CD14⁺单核细胞与NCI-H889细胞直接/间接接触共培养后,靶细胞死亡比例均高于未转染和siRNA转染(P<0.05),肿瘤坏死因子-α、IL-6、颗粒酶B水平及TRAIL MFI亦高于未转染和siRNA转染(P<0.05),但靶细胞死亡比例在直接接触和间接接触共培养之间的差异无统计学意义(P>0.05)。结论VAP患者单核细胞中A20水平升高,可能发挥抑制单核细胞活性的作用.     

A large‐scale computational study of inhibitor risk in non‐severe haemophilia A

Over 500 missense F8 mutations have been reported to cause non‐severe haemophilia A. Some F8 genotypes appear to confer a higher risk of inhibitor formation than others and individuals with the same F8 genotype may have differing risks of inhibitor formation. We present an in silico strategy demonstrating the heterogeneity of factor VIII (FVIII)‐derived antigen presentation whilst identifying patterns of human leucocyte antigen (HLA) peptide binding that might predict future inhibitor risk. A well‐validated computational tool, NetMHCII, enabled large‐scale comparison of predicted antigen presentation between endogenous, mutated FVIII‐derived peptides and wild‐type, therapeutic FVIII‐derived peptides spanning all F8 missense mutation positions reported to The Haemophilia A Mutation, Structure and Resource Site (HADB). We identify 40 F8 genotypes to be ‘low risk’ at a 50% inhibitory concentration (IC₅₀)‐binding threshold of 300 nmol/l (P = 0·00005), defined as absence of novel peptide‐major histocompatibility complex (MHC) surfaces for all 14 common HLA‐DR alleles assessed. Analysing each of the possible 7280 F8 genotype/HLA‐DR permutations individually at an IC₅₀ threshold of 300 nmol/l, 65% are predicted to not generate a novel peptide‐MHC surface that would be necessary to engage T cell help for subsequent anti‐FVIII antibody generation. This study demonstrates the future importance of interpreting F8 genotype in the context of an individual's HLA profile to personalize inhibitor risk prediction.