Regulatory B cells (Bregs) contribute to immune regulation. However, the mechanisms of action of Bregs remain elusive. Here, we report that T cell immunoreceptor with Ig and ITIM domains (TIGIT) ...expressed on human memory B cells especially CD19
CD24
CD27
CD39
IgD
IgM
CD1c
B cells is essential for effective immune regulation. Mechanistically, TIGIT on memory B cells controls immune response by directly acting on T cells and by arresting proinflammatory function of dendritic cells, resulting in the suppression of Th1, Th2, Th17, and CXCR5
ICOS
T cell response while promoting immune regulatory function of T cells. TIGIT
memory B cells are also superior to other B cells at expressing additional inhibitory molecules, including IL-10, TGFβ1, granzyme B, PD-L1, CD39/CD73, and TIM-1. Lack or decrease of TIGIT
memory B cells is associated with increased donor-specific antibody and TFH response, and decreased Treg response in renal and liver allograft patients. Therefore, TIGIT
human memory B cells play critical roles in immune regulation.
Cluster-weighted models (CWMs) are useful tools for identifying latent functional relationships between response variables and covariates. However, owing to excess distributional assumptions made on ...the covariates, these models can suffer misspecifications of component distributions, which could also undermine the estimation accuracy and render the model structure complicated for interpretation. To address this issue, we consider CWMs with univariate responses and propose a novel CWM by modelling each cluster as a finite mixture to enhance flexibility while retaining parsimony. We prove that the proposed method can provide more meaningful clusters in the data than those of existing methods. Additionally, we present a procedure to construct such a proposed CWM and a feasible expectation-maximization algorithm to estimate the model parameters. Numerical demonstrations, including simulations and real data analysis, are also provided.
In finite mixture of regression models, normal assumption for the errors of each regression component is typically adopted. Though this common assumption is theoretically and computationally ...convenient, it often produces inefficient and undesirable estimates which undermine the applicability of the model particularly in the presence of outliers. To reduce these defects, we propose to use nonparametric Gaussian scale mixture distributions for component error distributions. By this means, we can lessen the risk of misspecification and obtain robust estimators. In this paper, we study the identifiability of the proposed model and develop a feasible estimating algorithm. Numerical studies including simulation studies and real data analysis to demonstrate the performance of the proposed method are also presented.
The types and magnitude of Ag-specific immune responses can be determined by the functional plasticity of dendritic cells (DCs). However, how DCs display functional plasticity and control host immune ...responses have not been fully understood. In this study, we report that ligation of DC-asialoglycoprotein receptor (DC-ASGPR), a C-type lectin receptor (CLR) expressed on human DCs, resulted in rapid activation of Syk, followed by PLCγ2 and PKCδ engagements. However, different from other Syk-coupled CLRs, including Dectin-1, signaling cascade through DC-ASGPR did not trigger NF-κB activation. Instead, it selectively activated MAPK ERK1/2 and JNK. Rapid and prolonged phosphorylation of ERK1/2 led to sequential activation of p90RSK and CREB, which consequently bound to
promoter and initiated cytokine expression. In addition, DC-ASGPR ligation activated Akt, which differentially regulated the activities of GSK-3α/β and β-catenin and further contributed to IL-10 expression. Our observations demonstrate that DC-ASGPR induces IL-10 expression via an intrinsic signaling pathway, which provides a molecular explanation for DC-ASGPR-mediated programing of DCs to control host immune responses.
Background
Anti‐IgE (omalizumab) has been used for the treatment of moderate‐to‐severe asthma that is not controlled by inhaled steroids. Despite its success, it does not always provide patients with ...significant clinical benefits.
Objective
To investigate the transcriptional variations between omalizumab responders and non‐responders and to study the mechanisms of action of omalizumab.
Methods
The whole blood transcriptomes of moderate‐to‐severe adult asthma patients (N = 45:34 responders and 11 non‐responders) were analysed over the course of omalizumab treatment. Non‐asthmatic healthy controls (N = 17) were used as controls.
Results
Transcriptome variations between responders and non‐responders were identified using the genes significant (FDR < 0.05) in at least one comparison of each patient response status and time point compared with control subjects. Using gene ontology and network analysis, eight clusters of genes were identified. Longitudinal analyses of individual clusters revealed that responders could maintain changes induced with omalizumab treatment and become more similar to the control subjects, while non‐responders tend to remain more similar to their pre‐treatment baseline. Further analysis of an inflammatory gene cluster revealed that genes associated with neutrophil/eosinophil activities were up‐regulated in non‐responders and, more importantly, omalizumab did not significantly alter their expression levels. The application of modular analysis supported our findings and further revealed variations between responders and non‐responders.
Conclusion and Clinical Relevance
This study provides not only transcriptional variations between omalizumab responders and non‐responders, but also molecular insights for controlling asthma by omalizumab.
While viral antigens in human papillomavirus (HPV)-related oropharyngeal cancer (HPVOPC) are attractive targets for immunotherapy, the effects of existing standard-of-care therapies on immune ...responses to HPV are poorly understood. We serially sampled blood from patients with stage III-IV oropharyngeal cancer undergoing concomitant chemoradiotherapy with or without induction chemotherapy. Circulating immunocytes including CD4(+) and CD8(+) T cells, regulatory T cells (Treg), and myeloid-derived suppressor cells (MDSC) were profiled by flow cytometry. Antigen-specific T-cell responses were measured in response to HPV16 E6 and E7 peptide pools. The role of PD-1 signaling in treatment-related immunosuppression was functionally defined by performing HPV-specific T-cell assays in the presence of blocking antibody. While HPV-specific T-cell responses were present in 13 of 18 patients before treatment, 10 of 13 patients lost these responses within 3 months after chemoradiotherapy. Chemoradiotherapy decreased circulating T cells and markedly elevated MDSCs. PD-1 expression on CD4(+) T cells increased by nearly 2.5-fold after chemoradiotherapy, and ex vivo culture with PD-1-blocking antibody enhanced HPV-specific T-cell responses in 8 of 18 samples tested. Chemoradiotherapy suppresses circulating immune responses in patients with HPVOPC by unfavorably altering effector:suppressor immunocyte ratios and upregulating PD-1 expression on CD4(+) T cells. These data strongly support testing of PD-1-blocking agents in combination with standard-of-care chemoradiotherapy for HPVOPC.
Nuclear hormone receptors (NHRs) expressed by dendritic cells (DCs), the major immune inducers and regulators, could play important roles in host immunity. Assessment of NHRs expressed by DCs in the ...vaginal mucosa (VM), in comparison with those expressed by DCs in other tissues, will thus help us understand the immunology of human vagina. This study identified 16 NHR transcripts that are differentially expressed among 8 different antigen-presenting cell (APC) subsets isolated from human VM, skin, and blood. The expression profiles of NHRs were largely tissue specific. VM APCs expressed increased levels of
,
, and
, whereas skin and blood APCs expressed increased levels of
and
. Of interest, female sex hormone receptors,
and
, were found to be mainly expressed by non-APC cell types in the VM;
by HLA-DR
CD34
and
by HLA-DR
cells. ERα and PR were expressed by vimentin
cells in the VM, but not in human skin. ERα, but not PR, was also expressed in CD10
cells in the lamina propria of VM. In conclusion, NHR expression by APC subsets is tissue- and cell type-specific. Future studies on the roles of individual NHRs expressed by different cell types, including DC subsets, in the human VM are warranted.
Immunity results from a complex interplay between the antigen‐non‐specific innate immune system and the antigen‐specific adaptive immune system. The cells and molecules of the innate system employ ...non‐clonal recognition receptors including lectins, Toll‐like receptors, NOD‐like receptors, and helicases. B and T lymphocytes of the adaptive immune system employ clonal receptors recognizing antigens or their derived peptides in a highly specific manner. An essential link between innate and adaptive immunity is provided by dendritic cells (DCs). DCs can induce such contrasting states as immunity and tolerance. The recent years have brought a wealth of information on the biology of DCs revealing the complexity of this cell system. Indeed, DC plasticity and subsets are prominent determinants of the type and quality of elicited immune responses. In this article, we summarize our recent studies aimed at a better understanding of the DC system to unravel the pathophysiology of human diseases and design novel human vaccines.
The epithelium-associated cytokine thymic stromal lymphopoietin (TSLP) can induce OX40L and CCL17 expression by myeloid dendritic cells (mDCs), which contributes to aberrant Th2-type immune ...responses. Herein, we report that such TSLP-induced Th2-type immune response can be effectively controlled by Dectin-1, a C-type lectin receptor expressed by mDCs. Dectin-1 stimulation induced STAT3 activation and decreased the transcriptional activity of p50-RelB, both of which resulted in reduced OX40L expression on TSLP-activated mDCs. Dectin-1 stimulation also suppressed TSLP-induced STAT6 activation, resulting in decreased expression of the Th2 chemoattractant CCL17. We further demonstrated that Dectin-1 activation was capable of suppressing ragweed allergen (Amb a 1)-specific Th2-type T cell response in allergy patients
and house dust mite allergen (Der p 1)-specific IgE response in non-human primates
. Collectively, this study provides a molecular explanation of Dectin-1-mediated suppression of Th2-type inflammatory responses and suggests Dectin-1 as a target for controlling Th2-type inflammation.
Targeting HIV antigens directly to dendritic cells using monoclonal antibodies against cell-surface receptors has been shown to evoke potent cellular immunity in animal models. The objective of this ...study was to configure an anti-human CD40 antibody fused to a string of five highly conserved CD4 and CD8 T-cell epitope-rich regions of HIV-1 Gag, Nef and Pol (αCD40.HIV5pep), and then to demonstrate the capacity of this candidate therapeutic vaccine to target these HIV peptide antigens to human dendritic cells to expand functional HIV-specific T cells.
Antigen-specific cytokine production using intracellular flow cytometry and multiplex bead-based assay, and suppression of viral inhibition, were used to characterize the T cells expanded by αCD40.HIV5pep from HIV-infected patient peripheral blood mononuclear cell (PBMC) and dendritic cell/T-cell co-cultures.
This candidate vaccine expands memory CD4 and CD8 T cells specific to multiple epitopes within all five peptide regions across a wide range of major histocompatibility complex (MHC) haplotypes from HIV-infected patient PBMC and dendritic cell/T-cell co-cultures. These in vitro expanded HIV antigen-specific CD4 and CD8 T cells produce multiple cytokines and chemokines. αCD40.HIV5pep-expanded CD8 T cells have characteristics of cytotoxic effector cells and are able to kill autologous target cells and suppress HIV-1 replication in vitro.
Our data demonstrate the therapeutic potential of this CD40-targeting HIV candidate vaccine in inducing a broad repertoire of multifunctional T cells in patients.
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