Human granzyme B regulatory B cells prevent effector CD4+CD25- T cell proliferation through a mechanism dependent from lymphotoxin alpha.

Introduction: Human Granzyme B (GZMB) regulatory B cells (Bregs) have suppressive properties on CD4+ effector T cells by a mechanism partially dependent on GZMB. Moreover, these cells may be easily induced in vitro making them interesting for cell therapy. Methods: We characterized this population of in vitro induced GZMB+Bregs using single cell transcriptomics. To investigate their regulatory properties, Bregs or total B cells were also co-cultured with T cells and scRNAseq was used to identify receptor ligand interactions and to reveal gene expression changes in the T cells. Results: We find that Bregs exhibit a unique set of 149 genes differentially expressed and which are implicated in proliferation, apoptosis, metabolism, and altered antigen presentation capacity consistent with their differentiated B cells profile. Notably, Bregs induced a strong inhibition of T cell genes associated to proliferation, activation, inflammation and apoptosis compared to total B cells. We identified and validated 5 receptor/ligand interactions between Bregs and T cells. Functional analysis using specific inhibitors was used to test their suppressive properties and we identified Lymphotoxin alpha (LTA) as a new and potent Breg ligand implicated in Breg suppressive properties. Discussion: We report for the first time for a role of LTA in GZMB+Bregs as an enhancer of GZMB expression, and involved in the suppressive properties of GZMB+Bregs in human. The exact mechanism of LTA/GZMB function in this specific subset of Bregs remains to be determined.

Extracellular Vesicles in Transplantation.

Extracellular vesicles (EVs) have been extensively studied in the last two decades. It is now well documented that they can actively participate in the activation or regulation of immune system functions through different mechanisms, the most studied of which include protein-protein interactions and miRNA transfers. The functional diversity of EV-secreting cells makes EVs potential targets for immunotherapies through immune cell-derived EV functions. They are also a potential source of biomarkers of graft rejection through donor cells or graft environment-derived EV content modification. This review focuses on preclinical studies that describe the role of EVs from different cell types in immune suppression and graft tolerance and on the search for biomarkers of rejection.

Exosomes as New Biomarkers and Drug Delivery Tools for the Prevention and Treatment of Various Diseases: Current Perspectives.

Exosomes are nano-sized vesicles secreted by most cells that contain a variety of biological molecules, such as lipids, proteins and nucleic acids. They have been recognized as important mediators for long-distance cell-to-cell communication and are involved in a variety of biological processes. Exosomes have unique advantages, positioning them as highly effective drug delivery tools and providing a distinct means of delivering various therapeutic agents to target cells. In addition, as a new clinical diagnostic biomarker, exosomes play an important role in many aspects of human health and disease, including endocrinology, inflammation, cancer, and cardiovascular disease. In this review, we summarize the development of exosome-based drug delivery tools and the validation of novel biomarkers, and illustrate the role of exosomes as therapeutic targets in the prevention and treatment of various diseases.

Implementation of a Medical Ethics Course in Undergraduate Dental Education and Assessment of Knowledge and Attitudes.

OBJECTIVES: A medical ethics course was launched in 2012 in a French University Dental School. We compared knowledge and attitudes, before and after implementation of that course. The aim of this study was to compare students who received an ethics course (third year) to those who did not have such training, however, most of them did have some clinical traineeship. MATERIALS AND METHODS: An anonymous questionnaire was sent to the second-, third-, and sixth-year students. It comprised questions with Likert item format answers and clinical vignettes with open responses. The results were analyzed by two approaches: a statistical analysis (chi-square or Fischer exact tests) and a content analysis using a predefined grid. RESULTS: A total of 299 respondents replied (75% students) the questionnaire. The analysis showed a statistically significant association between knowledge of the law and information procedures (P < 0.0001), access to medical files (P = 0.004), and recording consent (P = 0.049). It was also significant between knowledge of the law and the principles of biomedical ethics (P < 0.0001 for autonomy and beneficence). The third-year students could state the principles of medical ethics with their percentage always greater than the sixth-year students. After the third year, the students' attitudes switched from a social to a medical emphasis, and their point of view regarding patient's autonomy evolved. Patient's refusal of care raised potential conflicts between autonomy, professional judgment, information, and consent. CONCLUSION: Ethics teaching could offer a way to turn positive attitudes into real competencies and should be considered at an early stage.

Residual pulmonary vascular obstruction and recurrence after acute pulmonary embolism. A single center cohort study.

INTRODUCTION: Up to 50% of patients with pulmonary embolism (PE) present lung perfusion defects after six months of anticoagulant treatment, suggesting residual pulmonary vascular obstruction (RPVO). The risk of recurrence in patients with RPVO remains unknown. The present study aims to assess the risk of recurrent venous thromboembolism (VTE) in patients with RPVO after a first symptomatic episode of PE. METHODS: Consecutive patients who survived a first objectively proven acute PE, treated for at least three months with anticoagulants, were included and followed prospectively. RPVO was defined as a pulmonary vascular obstruction of >10% on ventilation/perfusion lung scan performed at inclusion. Objectively proven VTE recurrences were registered and confirmed by an investigator unaware of the result of the ventilation/perfusion lung scan. RESULTS: Among the 310 patients (median age: 61years) included in the study, 60 (19%) had RPVO. During a median follow-up of 51.3months, 66 patients (21.2%, 95% CI [17.5-26.7]) experienced recurrent VTE. In an adjusted cox proportional hazards analysis, we identified RPVO (HR 1.94; 95% CI [1.11-3.39]; p=0.026) and unprovoked PE (HR 3.56; 95% CI [1.79-7.07]; p=0.00051) as independent risk factors for recurrent VTE whereas extended anticoagulation therapy (HR 0.19; 95% CI [0.07-0.55]; p=0.00014) was associated with a low risk of recurrence. CONCLUSION: The results suggest that RPVO is an independent risk factor of recurrent VTE after a first PE.

A simple tool to identify infants at high risk of mild to severe childhood asthma: the persistent asthma predictive score.

BACKGROUND: Recurrent wheezing in infants is a recognized risk factor for the development of childhood asthma. We sought to develop an easy-to-use persistent asthma predictive score (PAPS) in a population of young recurrent wheezers. METHODS: We retrospectively studied clinical and biological data of infants under 2 years of age presenting recurrent wheezing and evaluated current asthma at 6 years of age using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Multivariate analysis was performed to select predictive variables to generate a PAPS. The score was then tested on another cohort for independent validation. RESULTS: Two hundred infants were included in the cohort used to create the PAPS, and 227 in the validation cohort. In the first population, 47% of the children had developed asthma at 6 years of age, including 33% with mild to severe persistent asthma. Three parameters independently predicted persistent asthma: family history of asthma, personal atopic dermatitis, and multiple allergen sensitizations. Based on these variables, the PAPS showed 42% sensitivity, 90% specificity, 67% positive predictive value, and 76% negative predictive value for the prediction of persistent asthma. It was able to discriminate future persistent asthmatic from nonfuture persistent asthmatic children, with an accuracy of 74% in the initial population and 67% in the validation population. CONCLUSIONS: The PAPS, based on three easy-to-obtain variables, could help the physician in clinical practice to identify infants at high risk for persistent childhood asthma, and thus better evaluate the need for secondary preventive measures.