Dendritic cell mediated modulation of immune responses by Mycobacterium vaccae

The contemporary hygiene hypothesis suggests that certain microorganisms that were present throughout human evolution modulate the host immune system to reduce allergy associated T helper 2 (Th2) responses and inflammatory diseases by augmenting regulatory T cells. The prototypic environmental mycobacterium, M. vaccae has been used in mouse models of asthma to support this hypothesis, but data from human models and possible mechanisms are very limited. In view of the role of dendritic cells (DCs) in shaping adaptive T cell responses, the effect of innate immune interactions between human DCs and M. vaccae on allogeneic and antigen specific DC-dependent polarisation of T cells was tested. M. vaccae can stimulate cellular activation via Toll-like receptor 2 (TLR2) and therefore was compared to a specific TLR2 ligand (Pam3CSK4) and alternative stimulation with a TLR4 ligand (LPS). M. vaccae alone induced DC-dependent inhibition of Th2 responses, in contrast to Pam3CSK4, which had the opposite effect and LPS, which had no polarising effect. Comparison of DC maturation, genome-wide transcriptional response, and cytokine production in response to each stimulus did not correlate with the specific functional effects. In particular, directly comparable DC transcriptional responses to M. vaccae and Pam3CSK4 suggested that TLR2-mediated transcriptional regulation was not sufficient for inhibition of Th2 responses. Exclusive transcriptional responses to M. vaccae implicated a role for CREB1-dependent gene expression and analysis of signalling events confirmed selective early activation of the CREB pathway by M. vaccae. Collectively, this work has established that M. vaccae interaction with DCs does inhibit human Th2 responses and that further study of the CREB pathway in this model may provide novel insight into the molecular mechanisms of DC-dependent T cell polarisation. The final chapter of results presents development and validation of a novel approach for using short interspersed elements (SINEs) as a tool for normalisation of RT-qPCR data

Differential immunogenicity of homologous versus heterologous boost in Ad26.COV2.S vaccine recipients.

BACKGROUND: Protection offered by coronavirus disease 2019 (COVID-19) vaccines wanes over time, requiring an evaluation of different boosting strategies to revert such a trend and enhance the quantity and quality of Spike-specific humoral and cellular immune responses. These immunological parameters in homologous or heterologous vaccination boosts have thus far been studied for mRNA and ChAdOx1 nCoV-19 vaccines, but knowledge on individuals who received a single dose of Ad26.COV2.S is lacking. METHODS: We studied Spike-specific humoral and cellular immunity in Ad26.COV2.S-vaccinated individuals (n = 55) who were either primed with Ad26.COV2.S only (n = 13) or were boosted with a homologous (Ad26.COV2.S, n = 28) or heterologous (BNT162b2, n = 14) second dose. We compared our findings with the results found in individuals vaccinated with a single (n = 16) or double (n = 44) dose of BNT162b2. FINDINGS: We observed that a strategy of heterologous vaccination enhanced the quantity and breadth of both Spike-specific humoral and cellular immunity in Ad26.COV2.S-vaccinated individuals. In contrast, the impact of the homologous boost was quantitatively minimal in Ad26.COV2.S-vaccinated individuals, and Spike-specific antibodies and T cells were narrowly focused to the S1 region. CONCLUSIONS: Despite the small sample size of the study and the lack of well-defined correlates of protection against COVID-19, the immunological features detected support the utilization of a heterologous vaccine boost in individuals who received Ad26.COV2.S vaccination. FUNDING: This study is partially supported by the Singapore Ministry of Health's National Medical Research Council under its COVID-19 Research Fund (COVID19RF3-0060, COVID19RF-001, and COVID19RF-008), The Medical College St. Bartholomew's Hospital Trustees - Pump Priming Fund for SMD COVID-19 Research

B-Cell Activating Factor Secreted by Neutrophils Is a Critical Player in Lung Inflammation to Cigarette Smoke Exposure.

Cigarette smoke (CS) is the major cause of chronic lung injuries, such as chronic obstructive pulmonary disease (COPD). In patients with severe COPD, tertiary lymphoid follicles containing B lymphocytes and B cell-activating factor (BAFF) overexpression are associated with disease severity. In addition, BAFF promotes adaptive immunity in smokers and mice chronically exposed to CS. However, the role of BAFF in the early phase of innate immunity has never been investigated. We acutely exposed C57BL/6J mice to CS and show early BAFF expression in the bronchoalveolar space and lung tissue that correlates to airway neutrophil and macrophage influx. Immunostaining analysis revealed that neutrophils are the major source of BAFF. We confirmed in vitro that neutrophils secrete BAFF in response to cigarette smoke extract (CSE) stimulation. Antibody-mediated neutrophil depletion significantly dampens lung inflammation to CS exposure but only partially decreases BAFF expression in lung tissue and bronchoalveolar space suggesting additional sources of BAFF. Importantly, BAFF deficient mice displayed decreased airway neutrophil recruiting chemokines and neutrophil influx while the addition of exogenous BAFF significantly enhanced this CS-induced neutrophilic inflammation. This demonstrates that BAFF is a key proinflammatory cytokine and that innate immune cells in particular neutrophils, are an unconsidered source of BAFF in early stages of CS-induced innate immunity

PD-1 blockade partially recovers dysfunctional virus-specific B cells in chronic hepatitis B infection.

Chronic HBV (CHB) infection suppresses virus-specific T cells, but its impact on humoral immunity has been poorly analyzed. Here, we developed a dual-staining method that utilizes hepatitis B virus (HBV) surface antigens (HBsAg) labeled with fluorochromes as "baits" for specific ex vivo detection of HBsAg-specific B cells and analysis of their quantity, function, and phenotype. We studied healthy vaccinated subjects (n = 18) and patients with resolved (n = 21), acute (n = 11), or chronic (n = 96) HBV infection and observed that frequencies of circulating HBsAg-specific B cells were independent of HBV infection status. In contrast, the presence of serum HBsAg affected function and phenotype of HBsAg-specific B cells that were unable to mature in vitro into Ab-secreting cells and displayed an increased expression of markers linked to hyperactivation (CD21lo) and exhaustion (PD-1). Importantly, B cell alterations were not limited to HBsAg-specific B cells, but affected the global B cell population. HBsAg-specific B cell maturation could be partially restored by a method involving the combination of the cytokines IL-2 and IL-21 and CD40L-expressing feeder cells and was further boosted by the addition of anti-PD-1 Abs. In conclusion, HBV infection has a marked impact on global and HBV-specific humoral immunity, yet HBsAg-specific B cells are amenable to a partial rescue by B cell-maturing cytokines and PD-1 blockade

Divergences in Real-Time Classical Field Theories at Non-Zero Temperature

The classical approximation provides a non-perturbative approach to time-dependent problems in finite temperature field theory. We study the divergences in hot classical field theory perturbatively. At one-loop, we show that the linear divergences are completely determined by the classical equivalent of the hard thermal loops in hot quantum field theories, and that logarithmic divergences are absent. To deal with higher-loop diagrams, we present a general argument that the superficial degree of divergence of classical vertex functions decreases by one with each additional loop: one-loop contributions are superficially linearly divergent, two-loop contributions are superficially logarithmically divergent, and three- and higher-loop contributions are superficially finite. We verify this for two-loop SU(N) self-energy diagrams in Feynman and Coulomb gauges. We argue that hot, classical scalar field theory may be completely renormalized by local (mass) counterterms, and discuss renormalization of SU(N) gauge theories.Comment: 31 pages with 7 eps figure

Definiteness across languages

Definiteness has been a central topic in theoretical semantics since its modern foundation. However, despite its significance, there has been surprisingly scarce research on its cross-linguistic expression. With the purpose of contributing to filling this gap, the present volume gathers thirteen studies exploiting insights from formal semantics and syntax, typological and language specific studies, and, crucially, semantic fieldwork and cross-linguistic semantics, in order to address the expression and interpretation of definiteness in a diverse group of languages, most of them understudied. The papers presented in this volume aim to establish a dialogue between theory and data in order to answer the following questions: What formal strategies do natural languages employ to encode definiteness? What are the possible meanings associated to this notion across languages? Are there different types of definite reference? Which other functions (besides marking definite reference) are associated with definite descriptions? Each of the papers contained in this volume addresses at least one of these questions and, in doing so, they aim to enrich our understanding of definiteness

Definiteness across languages

Definiteness has been a central topic in theoretical semantics since its modern foundation. However, despite its significance, there has been surprisingly scarce research on its cross-linguistic expression. With the purpose of contributing to filling this gap, the present volume gathers thirteen studies exploiting insights from formal semantics and syntax, typological and language specific studies, and, crucially, semantic fieldwork and cross-linguistic semantics, in order to address the expression and interpretation of definiteness in a diverse group of languages, most of them understudied. The papers presented in this volume aim to establish a dialogue between theory and data in order to answer the following questions: What formal strategies do natural languages employ to encode definiteness? What are the possible meanings associated to this notion across languages? Are there different types of definite reference? Which other functions (besides marking definite reference) are associated with definite descriptions? Each of the papers contained in this volume addresses at least one of these questions and, in doing so, they aim to enrich our understanding of definiteness

Definiteness across languages

Definiteness has been a central topic in theoretical semantics since its modern foundation. However, despite its significance, there has been surprisingly scarce research on its cross-linguistic expression. With the purpose of contributing to filling this gap, the present volume gathers thirteen studies exploiting insights from formal semantics and syntax, typological and language specific studies, and, crucially, semantic fieldwork and cross-linguistic semantics, in order to address the expression and interpretation of definiteness in a diverse group of languages, most of them understudied. The papers presented in this volume aim to establish a dialogue between theory and data in order to answer the following questions: What formal strategies do natural languages employ to encode definiteness? What are the possible meanings associated to this notion across languages? Are there different types of definite reference? Which other functions (besides marking definite reference) are associated with definite descriptions? Each of the papers contained in this volume addresses at least one of these questions and, in doing so, they aim to enrich our understanding of definiteness

Definiteness across languages

Definiteness has been a central topic in theoretical semantics since its modern foundation. However, despite its significance, there has been surprisingly scarce research on its cross-linguistic expression. With the purpose of contributing to filling this gap, the present volume gathers thirteen studies exploiting insights from formal semantics and syntax, typological and language specific studies, and, crucially, semantic fieldwork and cross-linguistic semantics, in order to address the expression and interpretation of definiteness in a diverse group of languages, most of them understudied. The papers presented in this volume aim to establish a dialogue between theory and data in order to answer the following questions: What formal strategies do natural languages employ to encode definiteness? What are the possible meanings associated to this notion across languages? Are there different types of definite reference? Which other functions (besides marking definite reference) are associated with definite descriptions? Each of the papers contained in this volume addresses at least one of these questions and, in doing so, they aim to enrich our understanding of definiteness