Dynamics of B cells in germinal centres

Current Trends and Innovative Approaches in Cancer Immunotherapy

Immunotherapy is one of the most promising therapeutic approaches in the field of cancer treatment. As a tumor progresses, tumor cells employ an array of immune-regulatory mechanisms to suppress immune responses within the tumor microenvironment. Using our understanding of these mechanisms, cancer immunotherapy has been developed to enhance the immune system's effectiveness in treating cancer. Numerous cancer immunotherapies are currently in clinical use, yet many others are either in different stages of development or undergoing clinical studies. In this paper, we briefly discuss the features and current status of cancer immunotherapies. This includes the application of monoclonal antibodies, immune checkpoint inhibitors, adoptive cell therapy, cytokine therapy, cancer vaccines, and gene therapy, all of which have gained significant recognition in clinical practice. Additionally, we discuss limitations that may hinder successful clinical utilization and promising strategies, such as combining immunotherapy with nanotechnology.

Ascorbic acid alleviates rheumatoid arthritis by inhibiting the production of autoantibodies

BACKGROUND

Ascorbic acid can regulate the function of the immune system. This study aimed to investigate the underlying mechanisms of ascorbic acid in plasma cell differentiation and rheumatoid arthritis (RA).

METHODS

Mice were intraperitoneally injected with either ascorbic acid or an equivalent volume of phosphate-buffered saline (PBS). To elucidate the effects of ascorbic acid on arthritis, we utilized a collagen induced arthritis mouse model (CIA). To investigate the effects of ascorbic acid on antibody response, mice were immunized with (4-Hydroxy-3-nitrophenylacetyl)-Ficoll (NP-Ficoll) or (4-hydroxy-3-nitrophenyl) acetyl-keyhole limpet hemocyanin (NP-KLH) to elicit a T-cell independent (TI) or T-cell dependent (TD) antibody response. To clarify the ability of ascorbic acid on plasma cell production, we tracked the B cell differentiation fate on the NP-specific B1-8hi BCR transgenic background.

RESULTS

Ascorbic acid-injected mice demonstrated significantly delayed disease incidence and decreased disease severity compared to PBS-injected mice. Ascorbic acid can reduce the titers of autoantibodies in both arthritis and lupus mice models. Ascorbic acid can significantly reduce the number of plasma cells and the production of antigen-specific antibodies in TI and TD antibody response. In addition, ascorbic acid can disrupt the antibody affinity maturation. Through B1-8hi adoptive transfer experiments, it has been demonstrated that ascorbic acid restrains B cell differentiation into plasma cells in a cell-intrinsic manner. After in-depth exploration, we found that ascorbic acid can block the cell cycle of B cells and promote cell apoptosis. Mechanistically, ascorbic acid inhibited the production of autoreactive plasma cells by inhibiting the Stat3 signaling pathway.

CONCLUSION

Our study demonstrates that ascorbic acid has the ability to suppress the generation of autoreactive plasma cells, diminish the production of autoantibodies, and consequently delay the onset of rheumatoid arthritis.

Notch2 signaling governs activated B cells to form memory B cells

Memory B cells (MBCs) are essential for humoral immunological memory and can emerge during both the pre-germinal center (GC) and GC phases. However, the transcription regulators governing MBC development remain poorly understood. Here, we report that the transcription regulator Notch2 is highly expressed in MBCs and their precursors at the pre-GC stage and required for MBC development without influencing the fate of GC and plasma cells. Mechanistically, Notch2 signaling promotes the expression of complement receptor CD21 and augments B cell receptor (BCR) signaling. Reciprocally, BCR activation up-regulates Notch2 surface expression in activated B cells via a translation-dependent mechanism. Intriguingly, Notch2 is dispensable for GC-derived MBC formation. In summary, our findings establish Notch2 as a pivotal transcription regulator orchestrating MBC development through the reciprocal enforcement of BCR signaling during the pre-GC phase and suggest that the generation of GC-independent and -dependent MBCs is governed by distinct transcriptional mechanisms.

A laponite-based immunologically active gel delivery system for long-acting tumor vaccine

Traditional bolus vaccines typically require multiple doses, which complicates the vaccination process and may cause missed shots, leading to sub-optimal immunity and reduced vaccine effectiveness. Herein, a gel-based long-acting vaccine system with self-adjuvant properties based on laponite was constructed to simplify vaccination procedures and improve vaccine effectiveness. Firstly, the gel system could recruit multiple types of immune cells to form immune niches. Secondly, it could achieve sustained delivery of antigens to lymph nodes by active transport and passive drainage. Then, the gel system triggered the formation of a large number of germinal centers, which elicited enhanced and durable humoral immune responses, as well as strong cellular immune responses. As a result, it eventually showed good prophylactic and therapeutic effects in a variety of tumor models including melanoma, colorectal cancer and peritoneal metastasis models. By further combining the immunoadjuvant CpG ODN and cytokine IL-12, the effect of the gel-vaccine could be further enhanced. In a murine peritoneal metastasis model of colorectal carcinoma, a single administration of the gel-vaccine resulted in complete tumor eradication in 8/9 mice. In summary, this study developed an immunologically active gel-vaccine system. And as a robust and versatile vaccine platform, by loading different antigens and adjuvants, this gel-vaccine system is expected to realize its better therapeutic potential.

Monoclonal antibodies targeting interleukins for systemic lupus erythematosus: updates in early clinical drug development

INTRODUCTION

The advent of biological therapies has already revolutionized treatment strategies and disease course of several rheumatologic conditions, and monoclonal antibodies (mAbs) targeting cytokines and interleukins represent a considerable portion of this family of drugs. In systemic lupus erythematosus (SLE) dysregulation of different cytokine and interleukin-related pathways have been linked to disease development and perpetration, offering palatable therapeutic targets addressable via such mAbs.

AREAS COVERED

In this review, we provide an overview of the different biological therapies under development targeting cytokines and interleukins, with a focus on mAbs, while providing the rationale behind their choice as therapeutic targets and analyzing the scientific evidence linking them to SLE pathogenesis.

EXPERT OPINION

An unprecedented number of clinical trials on biological drugs targeting different immunological pathways are ongoing in SLE. Their success might allow us to tackle present challenges of SLE management, including the overuse of glucocorticoids in daily clinical practice, as well as SLE heterogenicity in treatment response among different individuals, hopefully paving the way toward precision medicine.

Case report: Persistent hypogammaglobulinemia and mixed chimerism after HLA class-II disparate-hematopoietic stem cell transplant

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for various hematological, immunological and metabolic diseases, replacing the patient's hematopoietic system with donor-derived healthy hematopoietic stem cells. HSCT can be complicated by early and late events related to impaired immunological recovery such as prolonged hypogammaglobulinemia post-HSCT. We present a 16-year-old female patient with sickle-cell disease who underwent HSCT with stem cells from a human leukocyte antigen (HLA) class-II mismatched family donor. While cellular recovery was good post-HSCT, the patient developed mixed chimerism and suffered from cervical lymphadenopathy, recurrent airway infections and cutaneous SLE. She presented with hypogammaglobulinemia and was started on immunoglobulin substitution therapy and antibiotic prophylaxis. B-cell phenotyping showed that she had increased transitional and naïve mature B cells, reduced memory B cells, and diminished marginal zone/natural effector cells. In-depth immunophenotyping and B-cell receptor repertoire sequencing ruled out an intrinsic B-cell defect by expression of activation-induced cytidine deaminase (AID), presence of somatic hypermutations and differentiation into IgG- and IgA-producing plasma cells in vitro. Immunohistochemistry and flow cytometry of lymph node tissue showed a clear block in terminal B-cell differentiation. Chimerism analysis of sorted lymph node populations showed that exclusively patient-derived B cells populated germinal centers, while only a minor fraction of follicular helper T cells was patient-derived. Given this discrepancy, we deduced that the HLA class-II disparity between patient and donor likely hinders terminal B-cell differentiation in the lymph node. This case highlights that studying disturbed cognate T-B interactions in the secondary lymphoid organs can provide unique insights when deciphering prolonged hypogammaglobulinemia post-HSCT.

Detection of disease-specific signatures in B cell repertoires of lymphomas using machine learning

The classification of B cell lymphomas-mainly based on light microscopy evaluation by a pathologist-requires many years of training. Since the B cell receptor (BCR) of the lymphoma clonotype and the microenvironmental immune architecture are important features discriminating different lymphoma subsets, we asked whether BCR repertoire next-generation sequencing (NGS) of lymphoma-infiltrated tissues in conjunction with machine learning algorithms could have diagnostic utility in the subclassification of these cancers. We trained a random forest and a linear classifier via logistic regression based on patterns of clonal distribution, VDJ gene usage and physico-chemical properties of the top-n most frequently represented clonotypes in the BCR repertoires of 620 paradigmatic lymphoma samples-nodular lymphocyte predominant B cell lymphoma (NLPBL), diffuse large B cell lymphoma (DLBCL) and chronic lymphocytic leukemia (CLL)-alongside with 291 control samples. With regard to DLBCL and CLL, the models demonstrated optimal performance when utilizing only the most prevalent clonotype for classification, while in NLPBL-that has a dominant background of non-malignant bystander cells-a broader array of clonotypes enhanced model accuracy. Surprisingly, the straightforward logistic regression model performed best in this seemingly complex classification problem, suggesting linear separability in our chosen dimensions. It achieved a weighted F1-score of 0.84 on a test cohort including 125 samples from all three lymphoma entities and 58 samples from healthy individuals. Together, we provide proof-of-concept that at least the 3 studied lymphoma entities can be differentiated from each other using BCR repertoire NGS on lymphoma-infiltrated tissues by a trained machine learning model.

Lipid metabolism in B cell biology

In recent years, the field of immunometabolism has solidified its position as a prominent area of investigation within the realm of immunological research. An expanding body of scientific literature has unveiled the intricate interplay between energy homeostasis, signalling molecules, and metabolites in relation to fundamental aspects of our immune cells. It is now widely accepted that disruptions in metabolic equilibrium can give rise to a myriad of pathological conditions, ranging from autoimmune disorders to cancer. Emerging evidence, although sometimes fragmented and anecdotal, has highlighted the indispensable role of lipids in modulating the behaviour of immune cells, including B cells. In light of these findings, this review aims to provide a comprehensive overview of the current state of knowledge regarding lipid metabolism in the context of B cell biology.

B cell lymphoma 6 promotes hepatocellular carcinoma progression by inhibiting tumor infiltrating CD4+T cell cytotoxicity through ESM1

Immunotherapy exhibited potential effects for advanced hepatocellular carcinoma, unfortunately, the clinical benefits are often countered by cancer adaptive immune suppressive response. Uncovering the mechanism how cancer cells evade immune surveillance would help to develop new immunotherapy approaches and combination therapy. In this article, by analyzing the transcriptional factors which modulate the differentially expressed genes between T cell infiltration high group and low group, we identified oncoprotein B cell lymphoma 6 (BCL6) suppresses the infiltration and activation of tumor infiltrating T lymphocytes, thus correlated with poorer clinical outcome. By using antibody deletion experiment, we further demonstrated that CD4+T cells but not CD8+T cells are the main lymphocyte population suppressed by Bcl6 to promote HCC development. Mechanistically, BCL6 decreases cancer cell expression of pro-inflammatory cytokines and T lymphocyte chemokines such as IL6, IL1F6, and CCL5. Moreover, BCL6 upregulates Endothelial cell-specific molecule 1 (ESM1) to inhibit T lymphocyte recruitment and activation possibly through ICAM-1/LFA-1 signaling pathway. Our findings uncovered an unappreciated paracrine mechanism how cancer cell-derived BCL6 assists cancer cell immune evasion, and highlighted the role of CD4+T cells in HCC immune surveillance.

Integrated analysis of tertiary lymphoid structures and immune infiltration in ccRCC microenvironment revealed their clinical significances: a multicenter cohort study

BACKGROUND

Tertiary lymphoid structures (TLSs) serve as organized lymphoid aggregates that influence immune responses within the tumor microenvironment. This study aims to investigate the characteristics and clinical significance of TLSs and tumor-infiltrating lymphocytes (TILs) in clear cell renal cell carcinoma (ccRCC).

METHODS

TLSs and TILs were analyzed comprehensively in 754 ccRCC patients from 6 academic centers and 532 patients from The Cancer Genome Atlas. Integrated analysis was performed based on single-cell RNA-sequencing datasets from 21 ccRCC patients to investigate TLS heterogeneity in ccRCC. Immunohistochemistry and multiplex immunofluorescence were applied. Cox regression and Kaplan-Meier analyses were used to reveal the prognostic significance.

RESULTS

The study demonstrated the existence of TLSs and TILs heterogeneities in the ccRCC microenvironment. TLSs were identified in 16% of the tumor tissues in 113 patients. High density (>0.6/mm2) and maturation of TLSs predicted good overall survival (OS) (p<0.01) in ccRCC patients. However, high infiltration (>151) of scattered TILs was an independent risk factor of poor ccRCC prognosis (HR=14.818, p<0.001). The presence of TLSs was correlated with improved progression-free survival (p=0.002) and responsiveness to therapy (p<0.001). Interestingly, the combination of age and TLSs abundance had an impact on OS (p<0.001). Higher senescence scores were detected in individuals with immature TLSs (p=0.003).

CONCLUSIONS

The study revealed the contradictory features of intratumoral TLSs and TILs in the ccRCC microenvironment and their impact on clinical prognosis, suggesting that abundant and mature intratumoral TLSs were associated with decreased risks of postoperative ccRCC relapse and death as well as favorable therapeutic response. Distinct spatial distributions of immune infiltration could reflect effective antitumor or protumor immunity in ccRCC.

A cocktail nanovaccine targeting key entry glycoproteins elicits high neutralizing antibody levels against EBV infection

Epstein-Barr virus (EBV) infects more than 95% of adults worldwide and is closely associated with various malignancies. Considering the complex life cycle of EBV, developing vaccines targeting key entry glycoproteins to elicit robust and durable adaptive immune responses may provide better protection. EBV gHgL-, gB- and gp42-specific antibodies in healthy EBV carriers contributed to sera neutralizing abilities in vitro, indicating that they are potential antigen candidates. To enhance the immunogenicity of these antigens, we formulate three nanovaccines by co-delivering molecular adjuvants (CpG and MPLA) and antigens (gHgL, gB or gp42). These nanovaccines induce robust humoral and cellular responses through efficient activation of dendritic cells and germinal center response. Importantly, these nanovaccines generate high levels of neutralizing antibodies recognizing vulnerable sites of all three antigens. IgGs induced by a cocktail vaccine containing three nanovaccines confer superior protection from lethal EBV challenge in female humanized mice compared to IgG elicited by individual NP-gHgL, NP-gB and NP-gp42. Importantly, serum antibodies elicited by cocktail nanovaccine immunization confer durable protection against EBV-associated lymphoma. Overall, the cocktail nanovaccine shows robust immunogenicity and is a promising candidate for further clinical trials.

The bidirectional relationship of depression and disturbances in B cell homeostasis: Double trouble

Major depressive disorder (MDD) is a recurrent, persistent, and debilitating neuropsychiatric syndrome with an increasing morbidity and mortality, representing the leading cause of disability worldwide. The dysregulation of immune systems (including innate and adaptive immune systems) has been identified as one of the key contributing factors in the progression of MDD. As the main force of the humoral immunity, B cells have an essential role in the defense against infections, antitumor immunity and autoimmune diseases. Several recent studies have suggested an intriguing connection between disturbances in B cell homeostasis and the pathogenesis of MDD, however, the B-cell-dependent mechanism of MDD remains largely unexplored compared to other immune cells. In this review, we provide an overview of how B cell abnormality regulates the progression of MMD and the potential consequence of the disruption of B cell homeostasis in patients with MDD. Abnormalities of B-cell homeostasis not only promote susceptibility to MDD, but also lead to an increased risk of developing infection, malignancy and autoimmune diseases in patients with MDD. A better understanding of the contribution of B cells underlying MDD would provide opportunities for identification of more targeted treatment approaches and might provide an overall therapeutic benefit to improve the long-term outcomes of patients with MDD.

A branching stochastic evolutionary model of the B-cell repertoire

We propose a stochastic framework to describe the evolution of the B-cell repertoire during germinal center (GC) reactions. Our model is formulated as a multitype age-dependent branching process with time-varying immigration. The immigration process captures the mechanism by which founder B cells initiate clones by gradually seeding GC over time, while the branching process describes the temporal evolution of the composition of these clones. The model assigns a type to each cell to represent attributes of interest. Examples of attributes include the binding affinity class of the B cells, their clonal family, or the nucleotide sequence of the heavy and light chains of their receptors. The process is generally non-Markovian. We present its properties, including as t → ∞ when the process is supercritical, the most relevant case to study expansion of GC B cells. We introduce temporal alpha and beta diversity indices for multitype branching processes. We focus on the dynamics of clonal dominance, highlighting its non-stationarity, and the accumulation of somatic hypermutations in the context of sequential immunization. We evaluate the impact of the ongoing seeding of GC by founder B cells on the dynamics of the B-cell repertoire, and quantify the effect of precursor frequency and antigen availability on the timing of GC entry. An application of the model illustrates how it may help with interpretation of BCR sequencing data.

The immunological understanding on germinal center B cells in psoriasis

The development of psoriasis is mainly driven by the dysregulation of T cells within the skin, marking a primary involvement of these cells in the pathogenesis. Although B cells are integral components of the immune system, their role in the initiation and progression of psoriasis is not as pivotal as that of T cells. The paradox of B cell suggests that, while it is crucial for adaptive immunity, B cells may contribute to the exacerbation of psoriasis. Numerous ideas proposed that there are potential relationships between psoriasis and B cells especially within germinal centers (GCs). Recent research projected that B cells might be triggered by autoantigens which then induced molecular mimicry to alter B cells activity within GC and generate autoantibodies and pro-inflammatory cytokines, form ectopic GC, and dysregulate the proliferation of keratinocytes. Hence, in this review, we gathered potential evidence indicating the participation of B cells in psoriasis within the context of GC, aiming to enhance our comprehension and advance treatment strategies for psoriasis thus inviting many new researchers to investigate this issue.

Biological changes in human B-cell line Ramos (RA.1) related to increasing doses of human parathyroid hormone

Background

The etiopathogenesis of autoimmune diseases is multifactorial, including hormonal factors. Remission of autoimmunity has been observed following treatment for concomitant hyperparathyroidism. Additionally, patients with autoimmune diseases have shown increased expression of parathyroid hormone receptor (PTH1R) and altered distribution of B cells subsets. Hence, this study aims to evaluate potential mechanisms and in vitro effects of PTH stimulation on B lymphocytes.

Methods

Using the human B-cell line Ramos (RA.1), various biological effects were evaluated with and without parathyroid hormone (PTH) stimulation at varying concentrations. Flow cytometry was employed to evaluate the phenotype of B lymphocytes based on IgD and CD38 expression, apoptosis induction via Annexin V and proliferation using CFSE. IgM production was quantified through ELISA, and Western blot analysis was performed to assess syk protein phosphorylation as an indicator of cell activation.

Results

Ramos cells (RA.1) evidenced a statistically significant change in the phenotype under human PTH stimulation, demonstrating an increased proportion of germinal centre cells (Bm3-Bm4) when stimulated with high concentrations of PTH.

Conclusions

The in vitro effects of PTH in B cells subsets align with previous findings of an altered phenotype in B lymphocytes expressing PTH1R among autoimmune disease patients, suggesting a potential role of this hormone in the pathophysiology of autoimmune diseases. However, further studies are necessary to elucidate the mechanisms by which PTH generates observed effects in B lymphocytes and to determine if PTH plays a role in autoimmunity.

Multi-omic Analysis of Human B-cell Activation Reveals a Key Lysosomal BCAT1 Role in mTOR Hyperactivation by B-cell receptor and TLR9

B-lymphocytes play major adaptive immune roles, producing antibody and driving T-cell responses. However, how immunometabolism networks support B-cell activation and differentiation in response to distinct receptor stimuli remains incompletely understood. To gain insights, we systematically investigated acute primary human B-cell transcriptional, translational and metabolomic responses to B-cell receptor (BCR), Toll-like receptor 9 (TLR9), CD40-ligand (CD40L), interleukin-4 (IL4) or combinations thereof. T-independent BCR/TLR9 co-stimulation, which drives malignant and autoimmune B-cell states, jointly induced PD-L1 plasma membrane expression, supported by NAD metabolism and oxidative phosphorylation. BCR/TLR9 also highly induced the transaminase BCAT1, which localized to lysosomal membranes to support branched chain amino acid synthesis and mTORC1 hyperactivation. BCAT1 inhibition blunted BCR/TLR9, but not CD40L/IL4-triggered B-cell proliferation, IL10 expression and BCR/TLR pathway-driven lymphoma xenograft outgrowth. These results provide a valuable resource, reveal receptor-mediated immunometabolism remodeling to support key B-cell phenotypes including PD-L1 checkpoint signaling, and identify BCAT1 as a novel B-cell therapeutic target.

Implications of Microbiota and Immune System in Development and Progression of Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most prevalent type of liver disease worldwide. The exact pathophysiology behind MASLD remains unclear; however, it is thought that a combination of factors or "hits" act as precipitants for disease onset and progression. Abundant evidence supports the roles of diet, genes, metabolic dysregulation, and the intestinal microbiome in influencing the accumulation of lipids in hepatocytes and subsequent progression to inflammation and fibrosis. Currently, there is no cure for MASLD, but lifestyle changes have been the prevailing cornerstones of management. Research is now focusing on the intestinal microbiome as a potential therapeutic target for MASLD, with the spotlight shifting to probiotics, antibiotics, and fecal microbiota transplantation. In this review, we provide an overview of how intestinal microbiota interact with the immune system to contribute to the pathogenesis of MASLD and metabolic dysfunction-associated steatohepatitis (MASH). We also summarize key microbial taxa implicated in the disease and discuss evidence supporting microbial-targeted therapies in its management.

SUMO-specific protease 1 regulates germinal center B cell response through deSUMOylation of PAX5

Humoral immunity depends on the germinal center (GC) reaction where B cells are tightly controlled for class-switch recombination and somatic hypermutation and finally generated into plasma and memory B cells. However, how protein SUMOylation regulates the process of the GC reaction remains largely unknown. Here, we show that the expression of SUMO-specific protease 1 (SENP1) is up-regulated in GC B cells. Selective ablation of SENP1 in GC B cells results in impaired GC dark and light zone organization and reduced IgG1-switched GC B cells, leading to diminished production of class-switched antibodies with high-affinity in response to a TD antigen challenge. Mechanistically, SENP1 directly binds to Paired box protein 5 (PAX5) to mediate PAX5 deSUMOylation, sustaining PAX5 protein stability to promote the transcription of activation-induced cytidine deaminase. In summary, our study uncovers SUMOylation as an important posttranslational mechanism regulating GC B cell response.

Clostridioides difficile toxin B subverts germinal center and antibody recall responses by stimulating a drug-treatable CXCR4-dependent mechanism

Recurrent Clostridioides difficile infection (CDI) results in significant morbidity and mortality. We previously established that CDI in mice does not protect against reinfection and is associated with poor pathogen-specific B cell memory (Bmem), recapitulating our observations with human Bmem. Here, we demonstrate that the secreted toxin TcdB2 is responsible for subversion of Bmem responses. TcdB2 from an endemic C. difficile strain delayed immunoglobulin G (IgG) class switch following vaccination, attenuated IgG recall to a vaccine booster, and prevented germinal center formation. The mechanism of TcdB2 action included increased B cell CXCR4 expression and responsiveness to its ligand CXCL12, accounting for altered cell migration and a failure of germinal center-dependent Bmem. These results were reproduced in a C. difficile infection model, and a US Food and Drug Administration (FDA)-approved CXCR4-blocking drug rescued germinal center formation. We therefore provide mechanistic insights into C. difficile-associated pathogenesis and illuminate a target for clinical intervention to limit recurrent disease.

Interleukin-1 regulates follicular T cells during the germinal center reaction

Introduction

Antibody production and the generation of memory B cells are regulated by T follicular helper (Tfh) and T follicular regulatory (Tfr) cells in germinal centers. However, the precise role of Tfr cells in controlling antibody production is still unclear. We have previously shown that both Tfh and Tfr cells express the IL-1R1 agonist receptor, whereas only Tfr cells express the IL-1R2 decoy and IL-1Ra antagonist receptors. We aimed to investigate the role of IL-1 receptors in the regulation of B cell responses by Tfh and Tfr.

Methods

We generated mice with IL-1 receptors inactivated in Tfh or Tfr and measured antibody production and cell activation after immunisation.

Results

While IL-1β levels are increased in the draining lymph node after immunisation, antigen-specific antibody levels and cell phenotypes indicated that IL-1β can activate both Tfh and Tfr cells through IL-1R1 stimulation. Surprisingly, expression of IL-1R2 and IL-1Ra on Tfr cells does not block IL-1 activation of Tfh cells, but rather prevents IL-1/IL-1R1-mediated early activation of Tfr cells. IL-1Rs also regulate the antibody response to autoantigens and its associated pathophysiology in an experimental lupus model.

Discussion

Collectively, our results show that IL-1 inhibitory receptors expressed by Tfr cells prevent their own activation and suppressive function, thus licensing IL-1-mediated activation of Tfh cells after immunisation. Further mechanistic studies should unravel these complex interactions between IL-1β and follicular helper and regulatory T cells and provide new avenues for therapeutic intervention.

B cell somatic hypermutation following COVID-19 vaccination with Ad26.COV2.S

The viral vector-based COVID-19 vaccine Ad26.COV2.S has been recommended by the WHO since 2021 and has been administered to over 200 million people. Prior studies have shown that Ad26.COV2.S induces durable neutralizing antibodies (NAbs) that increase in coverage of variants over time, even in the absence of boosting or infection. Here, we studied humoral responses following Ad26.COV2.S vaccination in individuals enrolled in the initial Phase 1/2a trial of Ad26.COV2.S in 2020. Through 8 months post vaccination, serum NAb responses increased to variants, including B.1.351 (Beta) and B.1.617.2 (Delta), without additional boosting or infection. The level of somatic hypermutation, measured by nucleotide changes in the VDJ region of the heavy and light antibody chains, increased in Spike-specific B cells. Highly mutated mAbs from these sequences neutralized more SARS-CoV-2 variants than less mutated comparators. These findings suggest that the increase in NAb breadth over time following Ad26.COV2.S vaccination is mediated by affinity maturation.

Multicomponent Pathogen-Mimicking Nanoparticles Induce Intestinal Immune Responses against Paratuberculosis

Given the worldwide problem posed by enteric pathogens, the discovery of safe and efficient intestinal adjuvants combined with novel antigen delivery techniques is essential to the design of mucosal vaccines. In this work, we designed poly (lactic-co-glycolic acid) (PLGA)-based nanoparticles (NPs) to codeliver all-trans retinoic acid (atRA), novel antigens, and CpG. To address the insolubility of the intestinal adjuvant atRA, we utilized PLGA to encapsulate atRA and form a "nanocapsid" with polydopamine. By leveraging polydopamine, we adsorbed the water-soluble antigens and the TLR9 agonist CpG onto the NPs' surface, resulting in the pathogen-mimicking PLPCa NPs. In this study, the novel fusion protein (HBf), consisting of the Mycobacterium avium subspecies paratuberculosis antigens HBHA, Ag85B, and Bfra, was coloaded onto the NPs. In vitro, PLPCa NPs were shown to promote the activation and maturation of bone marrow-derived dendritic cells. Additionally, we found that PLPCa NPs created an immune-rich microenvironment at the injection site following intramuscular administration. From the results, the PLPCa NPs induced strong IgA levels in the gut in addition to enhancing powerful systemic immune responses. Consequently, significant declines in the bacterial burden and inflammatory score were noted in PLPCa NPs-treated mice. In summary, PLPCa can serve as a novel and safe vaccine delivery platform against gut pathogens, such as paratuberculosis, capable of activating both systemic and intestinal immunity.

Regulation of B-cell function and expression of CD11c, T-bet, and FcRL5 in response to different activation signals

CD11c, FcRL5, or T-bet are commonly expressed by B cells expanding during inflammation, where they can make up >30% of mature B cells. However, the association between the proteins and differentiation and function in the host response remains largely unclear. We have assessed the co-expression of CD11c, T-bet, and FcRL5 in an in vitro B-cell culture system to determine how stimulation via the BCR, toll-like receptor 9 (TLR9), and different cytokines influence CD11c, T-bet, and FcRL5 expression. We observed different expression dynamics for all markers, but a largely overlapping regulation of CD11c and FcRL5 in response to BCR and TLR9 activation, while T-bet was strongly dependent on IFN-γ signaling. Investigating plasma cell differentiation and APC functions, there was no association between marker expression and antibody secretion or T-cell help. Rather the functions were associated with TLR9-signalling and B-cell-derived IL-6 production, respectively. These results suggest that the expression of CD11c, FcRL5, and T-bet and plasma cell differentiation and improved APC functions occur in parallel and are regulated by similar activation signals, but they are not interdependent.

Accelerated plasma-cell differentiation in Bach2-deficient mouse B cells is caused by altered IRF4 functions

Transcription factors BACH2 and IRF4 are both essential for antibody class-switch recombination (CSR) in activated B lymphocytes, while they oppositely regulate the differentiation of plasma cells (PCs). Here, we investigated how BACH2 and IRF4 interact during CSR and plasma-cell differentiation. We found that BACH2 organizes heterochromatin formation of target gene loci in mouse splenic B cells, including targets of IRF4 activation such as Aicda, an inducer of CSR, and Prdm1, a master plasma-cell regulator. Release of these gene loci from heterochromatin in response to B-cell receptor stimulation was coupled to AKT-mTOR pathway activation. In Bach2-deficient B cells, PC genes' activation depended on IRF4 protein accumulation, without an increase in Irf4 mRNA. Mechanistically, a PU.1-IRF4 heterodimer in activated B cells promoted BACH2 function by inducing gene expression of Bach2 and Pten, a negative regulator of AKT signaling. Elevated AKT activity in Bach2-deficient B cells resulted in IRF4 protein accumulation. Thus, BACH2 and IRF4 mutually modulate the activity of each other, and BACH2 inhibits PC differentiation by both the repression of PC genes and the restriction of IRF4 protein accumulation.

An Automated and Fast Sample Preparation Workflow for Laser Microdissection Guided Ultrasensitive Proteomics

Spatial tissue proteomics integrating whole-slide imaging, laser microdissection, and ultrasensitive mass spectrometry is a powerful approach to link cellular phenotypes to functional proteome states in (patho)physiology. To be applicable to large patient cohorts and low sample input amounts, including single-cell applications, loss-minimized and streamlined end-to-end workflows are key. We here introduce an automated sample preparation protocol for laser microdissected samples utilizing the cellenONE robotic system, which has the capacity to process 192 samples in 3 h. Following laser microdissection collection directly into the proteoCHIP LF 48 or EVO 96 chip, our optimized protocol facilitates lysis, formalin de-crosslinking, and tryptic digest of low-input archival tissue samples. The seamless integration with the Evosep ONE LC system by centrifugation allows 'on-the-fly' sample clean-up, particularly pertinent for laser microdissection workflows. We validate our method in human tonsil archival tissue, where we profile proteomes of spatially-defined B-cell, T-cell, and epithelial microregions of 4000 μm2 to a depth of ∼2000 proteins and with high cell type specificity. We finally provide detailed equipment templates and experimental guidelines for broad accessibility.

CD20 CAR T cells safely and reversibly ablate B cell follicles in a non-human primate model of HIV persistence

Chimeric antigen receptor (CAR) T cell therapies have demonstrated immense clinical success for B cell and plasma cell malignancies. We tested their impact on the viral reservoir in a macaque model of HIV persistence, comparing the functions of CD20 CAR T cells between animals infected with simian/human immunodeficiency virus (SHIV) and uninfected controls. We focused on the potential of this approach to disrupt B cell follicles (BCFs), exposing infected cells for immune clearance. In SHIV-infected animals, CAR T cells were highly functional, with rapid expansion and trafficking to tissue-associated viral sanctuaries, including BCFs and gut-associated lymphoid tissue (GALT). CD20 CAR T cells potently ablated BCFs and depleted lymph-node-associated follicular helper T (TFH) cells, with complete restoration of BCF architecture and TFH cells following CAR T cell contraction. BCF ablation decreased the splenic SHIV reservoir but was insufficient for effective reductions in systemic viral reservoirs. Although associated with moderate hematologic toxicity, CD20 CAR T cells were well tolerated in SHIV-infected and control animals, supporting the feasibility of this therapy in people living with HIV with underlying B cell malignancies. Our findings highlight the unique ability of CD20 CAR T cells to safely and reversibly unmask TFH cells within BCF sanctuaries, informing future combinatorial HIV cure strategies designed to augment antiviral efficacy.

BRWD1 establishes epigenetic states for germinal center initiation, maintenance, and function

Germinal center (GC) B cells segregate into three subsets that compartmentalize the antagonistic molecular programs of selection, proliferation, and somatic hypermutation. In bone marrow, the epigenetic reader BRWD1 orchestrates and insulates the sequential stages of cell proliferation and Igk recombination. We hypothesized BRWD1 might play similar insulative roles in the periphery. In Brwd1 -/- follicular B cells, GC initiation and class switch recombination following immunization were inhibited. In contrast, in Brwd1 -/- GC B cells there was admixing of chromatin accessibility across GC subsets and transcriptional dysregulation including induction of inflammatory pathways. This global molecular GC dysregulation was associated with specific defects in proliferation, affinity maturation, and tolerance. These data suggest that GC subset identity is required for some but not all GC-attributed functions. Furthermore, these data demonstrate a central role for BRWD1 in orchestrating epigenetic transitions at multiple steps along B cell developmental and activation pathways.

Lymphatic distribution considerations for subunit vaccine design and development

Subunit vaccines are an important platform for controlling current and emerging infectious diseases. The lymph nodes are the primary site generating the humoral response and delivery of antigens to these sites is critical to effective immunization. Indeed, the duration of antigen exposure within the lymph node is correlated with the antibody response. While current licensed vaccines are typically given through the intramuscular route, injecting vaccines subcutaneously allows for direct access to lymphatic vessels and therefore can enhance the transfer of antigen to the lymph nodes. However, protein subunit antigen uptake into the lymph nodes is inefficient, and subunit vaccines require adjuvants to stimulate the initial immune response. Therefore, formulation strategies have been developed to enhance the exposure of subunit proteins and adjuvants to the lymph nodes by increasing lymphatic uptake or prolonging the retention at the injection site. Given that lymph node exposure is a crucial consideration in vaccine design, in depth analyses of the pharmacokinetics of antigens and adjuvants should be the focus of future preclinical and clinical studies. This review will provide an overview of formulation strategies for targeting the lymphatics and prolonging antigen exposure and will discuss pharmacokinetic evaluations which can be applied toward vaccine development.

Antigen-specific Fab profiling achieves molecular-resolution analysis of human autoantibody repertoires in rheumatoid arthritis

The presence of autoantibodies is a defining feature of many autoimmune diseases. The number of unique autoantibody clones is conceivably limited by immune tolerance mechanisms, but unknown due to limitations of the currently applied technologies. Here, we introduce an autoantigen-specific liquid chromatography-mass spectrometry-based IgG1 Fab profiling approach using the anti-citrullinated protein antibody (ACPA) repertoire in rheumatoid arthritis (RA) as an example. We show that each patient harbors a unique and diverse ACPA IgG1 repertoire dominated by only a few antibody clones. In contrast to the total plasma IgG1 antibody repertoire, the ACPA IgG1 sub-repertoire is characterised by an expansion of antibodies that harbor one, two or even more Fab glycans, and different glycovariants of the same clone can be detected. Together, our data indicate that the autoantibody response in a prominent human autoimmune disease is complex, unique to each patient and dominated by a relatively low number of clones.

B cell development and antibody responses in human immune system mice: current status and future perspective

Humanized immune system (HIS) mice have been developed and used as a small surrogate model to study human immune function under normal or disease conditions. Although variations are found between models, most HIS mice show robust human T cell responses. However, there has been unsuccessful in constructing HIS mice that produce high-affinity human antibodies, primarily due to defects in terminal B cell differentiation, antibody affinity maturation, and development of primary follicles and germinal centers. In this review, we elaborate on the current knowledge about and previous attempts to improve human B cell development in HIS mice, and propose a potential strategy for constructing HIS mice with improved humoral immunity by transplantation of human follicular dendritic cells (FDCs) to facilitate the development of secondary follicles.

Mapping and modelling human B cell maturation in the germinal centre

The maturation of B cells within the germinal centre (GC) is necessary for antigen-specific immune responses and memory. Dysfunction in the GC can lead to immunodeficiencies, autoimmune diseases, or lymphomas. Here we describe how recent advances in single-cell and spatial genomics have enabled new discoveries about the diversity of human GC B cell states. However, with the advent of these hypothesis-generating technologies, the field should now transition towards testing bioinformatic predictions using experimental models of the human GC. We review available experimental culture systems for modelling human B cell responses and discuss the potential limitations of different methods in capturing bona fide GC B cell states. Together, the combination of cell atlas-based mapping with experimental modelling of lymphoid tissues holds great promise to better understand the maturation of human B cells in the GC response and generate new insights into human immune health and disease.

Repeated vaccination with homologous influenza hemagglutinin broadens human antibody responses to unmatched flu viruses

The on-going diversification of influenza virus necessicates annual vaccine updating. The vaccine antigen, the viral spike protein hemagglutinin (HA), tends to elicit strain-specific neutralizing activity, predicting that sequential immunization with the same HA strain will boost antibodies with narrow coverage. However, repeated vaccination with homologous SARS-CoV-2 vaccine eventually elicits neutralizing activity against highly unmatched variants, questioning this immunological premise. We evaluated a longitudinal influenza vaccine cohort, where each year the subjects received the same, novel H1N1 2009 pandemic vaccine strain. Repeated vaccination gradually enhanced receptor-blocking antibodies (HAI) to highly unmatched H1N1 strains within individuals with no initial memory recall against these historical viruses. An in silico model of affinity maturation in germinal centers integrated with a model of differentiation and expansion of memory cells provides insight into the mechanisms underlying these results and shows how repeated exposure to the same immunogen can broaden the antibody response against diversified targets.

The follicular dendritic cell: At the germinal center of autoimmunity?

Autoimmune diseases strain healthcare systems worldwide as their incidence rises, and current treatments put patients at risk for infections. An increased understanding of autoimmune diseases is required to develop targeted therapies that do not impair normal immune function. Many autoimmune diseases present with autoantibodies, which drive local or systemic inflammation. This indicates the presence of autoreactive B cells that have escaped tolerance. An important step in the development of autoreactive B cells is the germinal center (GC) reaction, where they undergo affinity maturation toward cognate self-antigen. Follicular dendritic cells (FDCs) perform the essential task of antigen presentation to B cells during the affinity maturation process. However, in recent years, it has become clear that FDCs play a much more active role in regulation of GC processes. Here, we evaluate the biology of FDCs in the context of autoimmune disease, with the goal of informing future therapeutic strategies.

The PD-1/PD-L1 Axis in the Biology of MASLD

Metabolic Dysfunction-Associated Steatotic Liver (MASL), previously named nonalcoholic fatty liver (NAFL), is a multifactorial disease in which metabolic, genetic, and environmental risk factors play a predominant role. Obesity and type 2 diabetes act as triggers of the inflammatory response, which contributes to the progression of MASL to Metabolic Dysfunction-Associated Steatohepatitis and the development of hepatocellular carcinoma. In the liver, several parenchymal, nonparenchymal, and immune cells maintain immunological homeostasis, and different regulatory pathways balance the activation of the innate and adaptative immune system. PD-1/PD-L1 signaling acts, in the maintenance of the balance between the immune responses and the tissue immune homeostasis, promoting self-tolerance through the modulation of activated T cells. Recently, PD-1 has received much attention for its roles in inducing an exhausted T cells phenotype, promoting the tumor escape from immune responses. Indeed, in MASLD, the excessive fat accumulation dysregulates the immune system, increasing cytotoxic lymphocytes and decreasing their cytolytic activity. In this context, T cells exacerbate liver damage and promote tumor progression. The aim of this review is to illustrate the main pathogenetic mechanisms by which the immune system promotes the progression of MASLD and the transition to HCC, as well as to discuss the possible therapeutic applications of PD-1/PD-L1 target therapy to activate T cells and reinvigorate immune surveillance against cancer.

Alternative DNA structures in hematopoiesis and adaptive immunity

Besides the canonical B-form, DNA also adopts alternative non-B form conformations which are highly conserved in all domains of life. While extensive research over decades has centered on the genomic functions of B-form DNA, understanding how non-B-form conformations influence functional genomic states remains a fundamental and open question. Recent studies have ascribed alternative DNA conformations such as G-quadruplexes and R-loops as important functional features in eukaryotic genomes. This review delves into the biological importance of alternative DNA structures, with a specific focus on hematopoiesis and adaptive immunity. We discuss the emerging roles of G-quadruplex and R-loop structures, the two most well-studied alternative DNA conformations, in the hematopoietic compartment and present evidence for their functional roles in normal cellular physiology and associated pathologies.

Follicular lymphoma B cells exhibit heterogeneous transcriptional states with associated somatic alterations and tumor microenvironments

Follicular lymphoma (FL) is an indolent non-Hodgkin lymphoma of germinal center origin, which presents with significant biologic and clinical heterogeneity. Using RNA-seq on B cells sorted from 87 FL biopsies, combined with machine-learning approaches, we identify 3 transcriptional states that divide the biological ontology of FL B cells into inflamed, proliferative, and chromatin-modifying states, with relationship to prior GC B cell phenotypes. When integrated with whole-exome sequencing and immune profiling, we find that each state was associated with a combination of mutations in chromatin modifiers, copy-number alterations to TNFAIP3, and T follicular helper cells (Tfh) cell interactions, or primarily by a microenvironment rich in activated T cells. Altogether, these data define FL B cell transcriptional states across a large cohort of patients, contribute to our understanding of FL heterogeneity at the tumor cell level, and provide a foundation for guiding therapeutic intervention.

Seven-chain adaptive immune receptor repertoire analysis in rheumatoid arthritis reveals novel features associated with disease and clinically relevant phenotypes

BACKGROUND

In rheumatoid arthritis (RA), the activation of T and B cell clones specific for self-antigens leads to the chronic inflammation of the synovium. Here, we perform an in-depth quantitative analysis of the seven chains that comprise the adaptive immune receptor repertoire (AIRR) in RA.

RESULTS

In comparison to controls, we show that RA patients have multiple and strong differences in the B cell receptor repertoire including reduced diversity as well as altered isotype, chain, and segment frequencies. We demonstrate that therapeutic tumor necrosis factor inhibition partially restores this alteration but find a profound difference in the underlying biochemical reactivities between responders and non-responders. Combining the AIRR with HLA typing, we identify the specific T cell receptor repertoire associated with disease risk variants. Integrating these features, we further develop a molecular classifier that shows the utility of the AIRR as a diagnostic tool.

CONCLUSIONS

Simultaneous sequencing of the seven chains of the human AIRR reveals novel features associated with the disease and clinically relevant phenotypes, including response to therapy. These findings show the unique potential of AIRR to address precision medicine in immune-related diseases.

B-cell intrinsic regulation of antibody mediated immunity by histone H2A deubiquitinase BAP1

Introduction

BAP1 is a deubiquitinase (DUB) of the Ubiquitin C-terminal Hydrolase (UCH) family that regulates gene expression and other cellular processes, through its direct catalytic activity on the repressive epigenetic mark histone H2AK119ub, as well as on several other substrates. BAP1 is also a highly important tumor suppressor, expressed and functional across many cell types and tissues. In recent work, we demonstrated a cell intrinsic role of BAP1 in the B cell lineage development in murine bone marrow, however the role of BAP1 in the regulation of B cell mediated humoral immune response has not been previously explored.

Methods and results

In the current study, we demonstrate that a B-cell intrinsic loss of BAP1 in activated B cells in the Bap1 fl/fl Cγ1-cre murine model results in a severe defect in antibody production, with altered dynamics of germinal centre B cell, memory B cell, and plasma cell numbers. At the cellular and molecular level, BAP1 was dispensable for B cell immunoglobulin class switching but resulted in an impaired proliferation of activated B cells, with genome-wide dysregulation in histone H2AK119ub levels and gene expression.

Conclusion and discussion

In summary, our study establishes the B-cell intrinsic role of BAP1 in antibody mediated immune response and indicates its central role in the regulation of the genome-wide landscapes of histone H2AK119ub and downstream transcriptional programs of B cell activation and humoral immunity.

B cell memory: from generation to reactivation: a multipronged defense wall against pathogens

Development of B cell memory is a conundrum that scientists are still exploring. Studies have been conducted in vitro and using advanced animal models to elucidate the mechanism underlying the generation of memory B cells (MBCs), the precise roles of MBCs against pathogens, and their protective functions against repeated infections throughout life. Lifelong immunity against invading diseases is mainly the result of overcoming a single infection. This protection is largely mediated by the two main components of B cell memory-MBCs and long-lived plasma cells (PCs). The chemical and cellular mechanisms that encourage fat selection for MBCs or long-lived PCs are an area of active research. Despite the fact that nearly all available vaccinations rely on the capacity to elicit B-cell memory, we have yet to develop successful vaccines that can induce broad-scale protective MBCs against some of the deadliest diseases, including malaria and AIDS. A deeper understanding of the specific cellular and molecular pathways that govern the generation, function, and reactivation of MBCs is critical for overcoming the challenges associated with vaccine development. Here, we reviewed literature on the development of MBCs and their reactivation, interaction with other cell types, strategies against invading pathogens, and function throughout life and discussed the recent advances regarding the key signals and transcription factors which regulate B cell memory and their relevance to the quest for vaccine development.

Characterization of the monoclonal antibody and the immunodominant B-cell epitope of African swine fever virus pA104R by using mouse model

The African swine fever virus (ASFV) structural protein pA104R is the only histone-like protein encoded by eukaryotic viruses. pA104R is an essential DNA-binding protein required for DNA replication and genome packaging of ASFV, which are vital for pathogen survival and proliferation. pA104R is an important target molecule for diagnosing, treating, and immune prevention of ASFV. This study characterized monoclonal antibodies (mAbs) against pA104R and found them to recognize natural pA104R in ASFV strains with different genotypes, showing high conservation. Confirmation analyses of pA104R epitopes using mAbs indicated the presence of immunodominant B-cell epitopes, and further characterization showed the high antigenic index and surface accessibility coefficients of the identified epitope. Furthermore, the pA104R protein functions through the polar interactions between the binding amino acid sites; however, these interactions may be blocked by the recognition of generated mAbs. Characterizing the immunodominant B-cell epitope of the ASFV critical proteins, such as pA104R, may contribute to developing sensitive diagnostic tools and vaccine candidate targets.IMPORTANCEAfrican swine fever (ASF) is a highly pathogenic, lethal, and contagious viral disease affecting domestic pigs and wild boars. As no effective vaccine or other treatments have been developed, the control of African swine fever virus (ASFV) relies heavily on virus detection and diagnosis. A potential serological target is the structural protein pA104R. However, the molecular basis of pA104R antigenicity remains unclear, and a specific monoclonal antibody (mAb) against this protein is still unavailable. In this study, mAbs against pA104R were characterized and found to recognize natural pA104R in ASFV strains with different genotypes. In addition, confirmation analyses of pA104R epitopes using mAbs indicated the presence of immunodominant B-cell epitopes, and further characterization showed the high antigenic index and surface accessibility coefficients of the identified epitope. Characteristics of the immunodominant B-cell epitope of ASFV proteins, such as pA104R, may contribute to developing sensitive diagnostic tools and identifying vaccine candidate targets.

Exercise Inhibits Doxorubicin-Induced Cardiotoxicity via Regulating B Cells

BACKGROUND

Doxorubicin is an effective chemotherapeutic agent, but its use is limited by acute and chronic cardiotoxicity. Exercise training has been shown to protect against doxorubicin-induced cardiotoxicity, but the involvement of immune cells remains unclear. This study aimed to investigate the role of exercise-derived B cells in protecting against doxorubicin-induced cardiotoxicity and to further determine whether B cell activation and antibody secretion play a role in this protection.

METHODS

Mice that were administered with doxorubicin (5 mg/kg per week, 20 mg/kg cumulative dose) received treadmill running exercise. The adoptive transfer of exercise-derived splenic B cells to μMT-/- (B cell-deficient) mice was performed to elucidate the mechanism of B cell regulation that mediated the effect of exercise.

RESULTS

Doxorubicin-administered mice that had undergone exercise training showed improved cardiac function, and low levels of cardiac apoptosis, atrophy, and fibrosis, and had reduced cardiac antibody deposition and proinflammatory responses. Similarly, B cell pharmacological and genetic depletion alleviated doxorubicin-induced cardiotoxicity, which phenocopied the protection of exercise. In vitro performed coculture experiments confirmed that exercise-derived B cells reduced cardiomyocyte apoptosis and fibroblast activation compared with control B cells. Importantly, the protective effect of exercise on B cells was confirmed by the adoptive transfer of splenic B cells from exercised donor mice to μMT-/- recipient mice. However, blockage of Fc gamma receptor IIB function using B cell transplants from exercised Fc gamma receptor IIB-/- mice abolished the protection of exercise-derived B cells against doxorubicin-induced cardiotoxicity. Mechanistically, we found that Fc gamma receptor IIB, an important B cell inhibitory receptor, responded to exercise and increased B cell activation threshold, which participated in exercise-induced protection against doxorubicin-induced cardiotoxicity.

CONCLUSIONS

Our results demonstrate that exercise training protects against doxorubicin-induced cardiotoxicity by upregulating Fc gamma receptor IIB expression in B cells, which plays an important anti-inflammatory role and participates in the protective effect of exercise against doxorubicin-induced cardiotoxicity.

Modularized viromimetic polymer nanoparticle vaccines (VPNVaxs) to elicit durable and effective humoral immune responses

Virus-like particle (VLP) vaccines had shown great potential during the COVID-19 pandemic, and was thought to be the next generation of antiviral vaccine technology due to viromimetic structures. However, the time-consuming and complicated processes in establishing a current recombinant-protein-based VLP vaccine has limited its quick launch to the out-bursting pandemic. To simplify and optimize VLP vaccine design, we herein report a kind of viromimetic polymer nanoparticle vaccine (VPNVax), with subunit receptor-binding domain (RBD) proteins conjugated to the surface of polyethylene glycol-b-polylactic acid (PEG-b-PLA) nanoparticles for vaccination against SARS-CoV-2. The preparation of VPNVax based on synthetic polymer particle and chemical post-conjugation makes it possible to rapidly replace the antigens and construct matched vaccines at the emergence of different viruses. Using this modular preparation system, we identified that VPNVax with surface protein coverage of 20%-25% had the best immunostimulatory activity, which could keep high levels of specific antibody titers over 5 months and induce virus neutralizing activity when combined with an aluminum adjuvant. Moreover, the polymer nano-vectors could be armed with more immune-adjuvant functions by loading immunostimulant agents or chemical chirality design. This VPNVax platform provides a novel kind of rapidly producing and efficient vaccine against different variants of SARS-CoV-2 as well as other viral pandemics.

A scalable synthesis of adjuvanting antigen depots based on metal-organic frameworks

Vaccines have saved countless lives by preventing and even irradicating infectious diseases. Commonly used subunit vaccines comprising one or multiple recombinant proteins isolated from a pathogen demonstrate a better safety profile than live or attenuated vaccines. However, the immunogenicity of these vaccines is weak, and therefore, subunit vaccines require a series of doses to achieve sufficient immunity against the pathogen. Here, we show that the biomimetic mineralization of the inert model antigen, ovalbumin (OVA), in zeolitic imidazolate framework-8 (ZIF-8) significantly improves the humoral immune response over three bolus doses of OVA (OVA 3×). Encapsulation of OVA in ZIF-8 (OVA@ZIF) demonstrated higher serum antibody titers against OVA than OVA 3×. OVA@ZIF vaccinated mice displayed higher populations of germinal center (GC) B cells and IgG1+ GC B cells as opposed to OVA 3×, indicative of class-switching recombination. We show that the mechanism of this phenomenon is at least partly owed to the metalloimmunological effects of the zinc metal as well as the sustained release of OVA from the ZIF-8 composite. The system acts as an antigen reservoir for antigen-presenting cells to traffic into the draining lymph node, enhancing the humoral response. Lastly, our model system OVA@ZIF is produced quickly at the gram scale in a laboratory setting, sufficient for up to 20 000 vaccine doses.

An atlas of cells in the human tonsil

Palatine tonsils are secondary lymphoid organs (SLOs) representing the first line of immunological defense against inhaled or ingested pathogens. We generated an atlas of the human tonsil composed of >556,000 cells profiled across five different data modalities, including single-cell transcriptome, epigenome, proteome, and immune repertoire sequencing, as well as spatial transcriptomics. This census identified 121 cell types and states, defined developmental trajectories, and enabled an understanding of the functional units of the tonsil. Exemplarily, we stratified myeloid slan-like subtypes, established a BCL6 enhancer as locally active in follicle-associated T and B cells, and identified SIX5 as putative transcriptional regulator of plasma cell maturation. Analyses of a validation cohort confirmed the presence, annotation, and markers of tonsillar cell types and provided evidence of age-related compositional shifts. We demonstrate the value of this resource by annotating cells from B cell-derived mantle cell lymphomas, linking transcriptional heterogeneity to normal B cell differentiation states of the human tonsil.

Genomic profiling and associated B cell lineages delineate the efficacy of neoadjuvant anti-PD-1-based therapy in oesophageal squamous cell carcinoma

BACKGROUND

Neoadjuvant chemoimmunotherapy has offered novel therapeutic options for patients with locally advanced oesophageal squamous cell carcinoma (ESCC). Depicting the landscape of genomic and immune profiles is critical in predicting therapeutic responses.

METHODS

We integrated whole-exome sequencing, single-cell RNA sequencing, and immunofluorescence data of ESCC samples from 24 patients who received neoadjuvant treatment with PD-1 inhibitors plus paclitaxel and platinum-based chemotherapy to identify correlations with therapeutic responses.

FINDINGS

An elevation of small insertions and deletions was observed in responders. DNA mismatch repair (MMR) pathway alternations were highly frequent in patients with optimal responses and correlated with tumour infiltrating lymphocytes (TILs). Among the TILs in ESCC, dichotomous developing trajectories of B cells were identified, with one lineage differentiating towards LMO2+ germinal centre B cells and another lineage differentiating towards CD55+ memory B cells. While LMO2+ germinal centre B cells were enriched in responding tumours, CD55+ memory B cells were found to correlate with inferior responses to combination therapy, exhibiting immune-regulating features and impeding the cytotoxicity of CD8+ T cells. The comprehensive evaluation of transcriptomic B cell lineage features was validated to predict responses to immunotherapy in patients with cancer.

INTERPRETATION

This comprehensive evaluation of tumour MMR pathway alternations and intra-tumoural B cell features will help to improve the selection and management of patients with ESCC to receive neoadjuvant chemoimmunotherapy.

FUNDING

National Science Foundation of China (82373371, 82330053), Eastern Scholar Program at Shanghai Institutions of Higher Learning, National Science and Technology Major Project of China (2023YFA1800204, 2020YFC2008402), and Science and Technology Commission of Shanghai Municipality (22ZR1410700, 20ZR1410800).

Germinal centres within tumour positive sentinel lymph nodes are positively associated with tumour infiltrating lymphocytes and tertiary lymphoid structures in breast cancer

BACKGROUND

Stromal tumour infiltrating lymphocytes (sTILs) and presence of tertiary lymphoid structures have been proposed as indicators of tumour-related immune response in breast cancer. An increased number of germinal centres (GCs) in lymph nodes is considered a sign of humoral immune reactivity.

AIMS

It is unclear whether a relationship exists between number and size of GCs within tumour positive sentinel lymph nodes (SLNpos), sTILs and tertiary lymphoid structures within matched primary breast cancer and breast cancer subtype.

METHODS

Axillary SLNpos from 175 patients with breast cancer were manually contoured in digitized haematoxylin and eosin stained sections. Total SLN area, GC number and GC area were measured in SLNpos with the largest metastatic area. To correct for SLN size, GC number and GC area were divided by SLN area. sTILs and presence of tertiary lymphoid structures were assessed in the primary breast cancer.

RESULTS

A higher GC number and larger GC area were found in patients with high sTILs (≥2%) (both P < 0.001) and in patients with presence of tertiary lymphoid structures (PGC number = 0.034 and PGC area = 0.016). Triple negative and HER2-positive (N = 45) breast cancer subtypes had a higher GC number and higher sTILs compared to hormone receptor positive, HER2-negative breast cancer (N = 130) (PGC number < 0.001 and PsTILs= 0.001).

CONCLUSION

This study suggests GCs measured within SLNpos might be useful indicators of the humoral anti-tumour immune response in breast cancer. Future studies are needed investigating underlying biological mechanisms and prognostic value of GCs in SLNs.

FcγRIIB modulates splenic germinal center response against immune subversion during acute influenza A virus infection

BACKGROUND

B cells are essential for providing humoral protection against acute influenza A virus (IAV) infection. FcγRIIB, a regulator of antibody (Ab) production, influences immune responses during pathogen infections, but its specific impact on humoral protection and B cell-mediated responses against IAV remains unclear.

METHODS

To investigate FcγRIIB's role in host defense and B cell function during acute IAV infection, we generated mice with systemic FcγRIIB deficiency, functional impairment, and B cell-specific FcγRIIB deletion. We infected these mice with PR8 (H1N1) or Hkx31 (H3N2) IAVs and evaluated body weight preservation, survival rates, Ab production, viral neutralization, Ab affinity maturation, and germinal center B cell development.

RESULTS

Mice lacking FcγRIIB or with impaired function showed improved protection, preserved body weight, and increased survival rates during IAV infection. Notably, mice with haploinsufficient FcγRIIB function displayed protective effects. Selective deficiency of FcγRIIB in B cells led to enhanced Ab production, resulting in elevated IAV-specific Abs in the serum with superior viral neutralizing potency. However, the impact on the affinity maturation index of virus-specific Abs was modest. Accordingly, FcγRIIB-deficient B cells maintained normal germinal center B cell development during IAV infection, whereas wild-type mice exhibited delayed differentiation.

CONCLUSION

Our research underscores the pivotal role of FcγRIIB in host defense and B cell-mediated immunity during acute IAV infection. Additionally, our discoveries hold implications for antiviral treatments, particularly during the initial stages of IAV infection, aimed at enhancing the host's humoral immune response.

The multilevel extensive diversity across the cynomolgus macaque captured by ultra-deep adaptive immune receptor repertoire sequencing

The extent to which AIRRs differ among and within individuals remains elusive. Via ultra-deep repertoire sequencing of 22 and 25 tissues in three cynomolgus macaques, respectively, we identified 84 and 114 novel IGHV and TRBV alleles, confirming 72 (85.71%) and 100 (87.72%) of them. The heterogeneous V gene usage patterns were influenced, in turn, by genetics, isotype (for BCRs only), tissue group, and tissue. A higher proportion of intragroup shared clones in the intestinal tissues than those in other tissues suggests a close intra-intestinal adaptive immunity network. Significantly higher mutation burdens in the public clones and the inter-tissue shared IgM and IgD clones indicate that they might target the shared antigens. This study reveals the extensive heterogeneity of the AIRRs at various levels and has broad fundamental and clinical implications. The data generated here will serve as an invaluable resource for future studies on adaptive immunity in health and diseases.

Arid1a-dependent canonical BAF complex suppresses inflammatory programs to drive efficient Germinal Center B cell responses

Differentiating B cells in germinal centers (GC) require tightly coordinated transcriptional and epigenetic transitions to generate efficient humoral immune responses. The mammalian Brg1/Brm-associated factor (BAF) complexes are major regulators of nucleosomal remodeling, crucial for cellular differentiation and development, and are commonly mutated in several cancers, including GC-derived B cell lymphomas. However, the specific roles of distinct BAF complexes in GC B cell biology and generation of functional humoral immune responses are not well understood. Here, we show that the A-T Rich Interaction Domain 1a (Arid1a) containing canonical BAF (cBAF) complex is required for maintenance of GCs and therefore high affinity antibody responses. While Arid1a-deficient B cells undergo activation to initiate GC responses, they fail to sustain the GC program resulting in premature GC collapse. We discovered that Arid1a-dependent cBAF activity establishes permissive chromatin landscapes during B cell activation and is concomitantly required to suppress inflammatory gene programs to maintain transcriptional fidelity in early GC B cells. Interestingly, the inflammatory signatures instigated by Arid1a deficiency in early GC B cells recruited neutrophils and inflammatory monocytes and eventually disrupted GC homeostasis. Dampening of inflammatory cues with anti-inflammatory glucocorticoid receptor signaling rescued GC B cell differentiation of Arid1a-deficient B cells, thus highlighting a critical role of inflammation in impeding GC responses. In sum, our work identifies essential functions of Arid1a-dependent BAF activity in promoting efficient GC responses. These findings further support an emerging paradigm in which unrestrained inflammation limits GC-derived humoral responses, as reported in the context of severe bacterial and viral infections.

The role of m6A RNA methylation in autoimmune diseases: Novel therapeutic opportunities

N6-methyladenosine (m6A) modifications, as one of the most common forms of internal RNA chemical modifications in eukaryotic cells, have gained increasing attention in recent years. The m6A RNA modifications exert various crucial roles in various biological processes, such as embryonic development, neurogenesis, circadian rhythms, and tumorigenesis. Recent advances have highlighted that m6A RNA modification plays an important role in immune response, especially in the initiation and progression of autoimmune diseases. In this review, we summarized the regulatory mechanisms of m6A methylation and its biological functions in the immune system and mainly focused on recent progress in research on the potential role of m6A RNA methylation in the pathogenesis of autoimmune diseases, thus providing possible biomarkers and potential targets for the prevention and treatment of autoimmune diseases.