IL-10-producing regulatory B cells and plasmocytes: Molecular mechanisms and disease relevance

Human chorionic gonadotropin regulates cytokine production by lymphocytes from patients with multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) that primarily affects young adults, predominantly females. This was partially attributed to sex differences in immunity, which are influenced by changes in sex hormones occurring during women's life, among other factors. Furthermore, MS patients experience significant improvement in their symptoms during pregnancy when levels of female sex-hormones significantly increase. This phenomenon was attributed to immune adaptations occurring during gestation which are regulated by paternal antigens and sex hormones. The human chorionic gonadotropin (hCG) was shown to have strong immunosuppressive abilities. We aimed to analyze here the capacity of the hCG to regulate pro- and anti-inflammatory cytokine production by PBMC from MS patients. PBMC isolated from 17 MS patients receiving IFNβ1a treatment were cultured with or without recombinant or urinary hCG. Cytokine production in the supernatants was assessed using a CBA array and cytokine production by lymphocytes and expression of co-stimulatory molecules in B-lymphocytes were evaluated by flow cytometry. hCG reduced the production of TNF by PBMC from MS patients while lowering the percentages of TNF producing T cells and diminishing the production of TNF by B cells. hCG significantly boosted the production of IL-10 by regulatory T cells and CD19high B cells from MS patients. Furthermore, hCG treatment lowered the percentages of CD80+CD86+ expressing B cells within PBMC from MS patients. Overall, our results described a novel and not yet explored mechanisms of action of hCG in the context of MS.

Tlr9 deficiency in B cells leads to obesity by promoting inflammation and gut dysbiosis

Toll-like receptor 9 (TLR9) recognizes bacterial, viral and self DNA and play an important role in immunity and inflammation. However, the role of TLR9 in obesity is less well-studied. Here, we generate B-cell-specific Tlr9-deficient (Tlr9fl/fl/Cd19Cre+/-, KO) B6 mice and model obesity using a high-fat diet. Compared with control mice, B-cell-specific-Tlr9-deficient mice exhibited increased fat tissue inflammation, weight gain, and impaired glucose and insulin tolerance. Furthermore, the frequencies of IL-10-producing-B cells and marginal zone B cells were reduced, and those of follicular and germinal center B cells were increased. This was associated with increased frequencies of IFNγ-producing-T cells and increased follicular helper cells. In addition, gut microbiota from the KO mice induced a pro-inflammatory state leading to immunological and metabolic dysregulation when transferred to germ-free mice. Using 16 S rRNA gene sequencing, we identify altered gut microbial communities including reduced Lachnospiraceae, which may play a role in altered metabolism in KO mice. We identify an important network involving Tlr9, Irf4 and Il-10 interconnecting metabolic homeostasis, with the function of B and T cells, and gut microbiota in obesity.

Oxidative phosphorylation regulates B cell effector cytokines and promotes inflammation in multiple sclerosis

Dysregulated B cell cytokine production contributes to pathogenesis of immune-mediated diseases including multiple sclerosis (MS); however, the underlying mechanisms are poorly understood. In this study we investigated how cytokine secretion by pro-inflammatory (GM-CSF-expressing) and anti-inflammatory (IL-10-expressing) B cells is regulated. Pro-inflammatory human B cells required increased oxidative phosphorylation (OXPHOS) compared with anti-inflammatory B cells. OXPHOS reciprocally modulated pro- and anti-inflammatory B cell cytokines through regulation of adenosine triphosphate (ATP) signaling. Partial inhibition of OXPHOS or ATP-signaling including with BTK inhibition resulted in an anti-inflammatory B cell cytokine shift, reversed the B cell cytokine imbalance in patients with MS, and ameliorated neuroinflammation in a myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalitis mouse model. Our study identifies how pro- and anti-inflammatory cytokines are metabolically regulated in B cells and identifies ATP and its metabolites as a "fourth signal" that shapes B cell responses and is a potential target for restoring the B cell cytokine balance in autoimmune diseases.

Myeloid-derived suppressor cells from tumour-bearing mice induce the population expansion of CD19hiFcγRIIbhi regulatory B cells via PD-L1

Myeloid-derived suppressor cells (MDSCs) increase in number and gain immunosuppressive functions in tumours and many other pathological conditions. MDSCs are characterized by their strong T-cell immunosuppressive capacity. The effects that MDSCs may have on B cells, especially within the tumour microenvironment, are less well understood. Here, we report that either monocytic MDSCs or polymorphonuclear MDSCs can promote increases in interleukin (IL)-10-expressing CD19hiFcγRIIbhi regulatory B cells in vitro and in vivo. Splenic transitional-1, -2, and -3 cells and marginal zone B cells, but not follicular B cells, differentiate into IL-10-expressing CD19hiFcγRIIbhi regulatory B cells. The adoptive transfer of CD19hiFcγRIIbhi regulatory B cells via tail vein injection can promote subcutaneous 3LL tumour growth in mice. The expression of programmed death-ligand 1 on MDSCs was found to be strongly associated with CD19hiFcγRIIbhi regulatory B cell population expansion. Furthermore, the frequency of circulating CD19+FcγRIIhi regulatory B cells was significantly increased in advanced-stage lung cancer patients. Our results unveil a critical role of MDSCs in regulatory B-cell differentiation and population expansion in lung cancer patients.

Effect of Alpha-1 Antitrypsin and Irisin on Post-Exercise Inflammatory Response: A Narrative Review

Physical activity has a positive effect on human health and emotional well-being. However, in both amateur and professional athletes, training poses a risk of acute or chronic injury through repetitive overloading of bones, joints, and muscles. Inflammation can be an adverse effect of intense exercise caused by several factors including oxidative stress. The present narrative review summarizes current knowledge on inflammatory markers induced by physical exercise. Post-exercise recovery may reduce inflammatory responses and is key to effective training and adaptation of muscle tissues to sustained physical exertion.

Analysis of Mutational Status of IGHV, and Cytokine Polymorphisms as Prognostic Factors in Chronic Lymphocytic Leukemia: The Romanian Experience

The aim of the current study was to assess the associations between genetic risk factors (such as the mutational status of the IGHV gene and polymorphisms of the IL-10 and TNF-α genes) and CLL risk, prognosis, and overall survival. Another goal of this study was to evaluate the multivariate effect of the combination of multiple genetic risk factors (mutational status of the IGHV gene, somatic mutations, DNA CNVs, and cytokine SNPs) on the clinical characteristics and survival of patients. A total of 125 CLL patients and 239 healthy controls were included for comparative SNP analysis. IL-10 (rs1800896 and rs1800872) and TNF-α (rs361525 and rs1800750) SNPs and haplotypes were not associated with CLL risk. The absence of hypermutation in the IGHV gene was shown to be of important prognostic value, being associated with short OS. Further individual risk factors for short OS were an age above 65 years at diagnosis and the presence of somatic mutations and/or CNVs. In our multivariable analysis, the presence of somatic mutations and the IL-10 rs1800872 variant allele, and the association of CNVs with the IL-10 rs1800896 variant allele, were identified as risk factors for short OS. Moreover, the OS in unmutated IGHV patients was additionally affected (decreased) by the presence of CNVs and/or somatic mutations. Similarly, IL-10 rs1800896 modulated the OS in unmutated IGHV patients with CNVs.

B-cell responses to ITP treatments

Deficiency in regulatory B cells has been suggested in immune thrombocytopenia. In this study, Stimpson et al. emphasize the importance of considering the treatments received for immunological analyses. Commentary on: Stimpson et al. Systemic immunosuppression depletes peripheral blood regulatory B cells in patients with immune thrombocytopenia. Br J Haematol 2024;204:644-648.

Portulaca oleracea L. polysaccharide alleviates dextran sulfate sodium-induced ulcerative colitis by regulating intestinal homeostasis

Portulaca oleracea L. (purslane) is a vegetable that contains a variety of active compounds with nutritional properties and has the potential to treat ulcerative colitis (UC). However, the mechanisms underlying the effects of Portulaca oleracea L. polysaccharide (POP) in alleviating UC remain unclear. In this study, we prepared an aqueous extract of purslane and separated a fraction with molecular weight >10 kDa using membrane separation. This fraction was used to isolate POP. The effect of POP on gut microbiota and colon transcriptome in dextran sulfate sodium-induced UC model mice was evaluated. POP treatment reduced inflammation and oxidative stress imbalance in UC mice. In addition, POP improved the intestinal barrier and regulated intestinal homeostasis. Importantly, POP was found to regulate gut microbiota, maintain the levels of retinol and short-chain fatty acids in the gut, promote the proliferation and differentiation of B cells in the colon, and increase the expression of immunoglobulin A. These results provide novel insights into the role of POP in regulating intestinal homeostasis, which should guide further development of POP as a functional food.

B-cell-specific checkpoint molecules that regulate anti-tumour immunity

The role of B cells in anti-tumour immunity is still debated and, accordingly, immunotherapies have focused on targeting T and natural killer cells to inhibit tumour growth1,2. Here, using high-throughput flow cytometry as well as bulk and single-cell RNA-sequencing and B-cell-receptor-sequencing analysis of B cells temporally during B16F10 melanoma growth, we identified a subset of B cells that expands specifically in the draining lymph node over time in tumour-bearing mice. The expanding B cell subset expresses the cell surface molecule T cell immunoglobulin and mucin domain 1 (TIM-1, encoded by Havcr1) and a unique transcriptional signature, including multiple co-inhibitory molecules such as PD-1, TIM-3, TIGIT and LAG-3. Although conditional deletion of these co-inhibitory molecules on B cells had little or no effect on tumour burden, selective deletion of Havcr1 in B cells both substantially inhibited tumour growth and enhanced effector T cell responses. Loss of TIM-1 enhanced the type 1 interferon response in B cells, which augmented B cell activation and increased antigen presentation and co-stimulation, resulting in increased expansion of tumour-specific effector T cells. Our results demonstrate that manipulation of TIM-1-expressing B cells enables engagement of the second arm of adaptive immunity to promote anti-tumour immunity and inhibit tumour growth.

Ten-eleven translocation-2 inactivation restrains IL-10-producing regulatory B cells to enable antitumor immunity in hepatocellular carcinoma

BACKGROUND AND AIMS

IL-10-producing regulatory B cells (IL-10 + B cells), a dominant regulatory B cell (Breg) subset, foster tumor progression. However, the mechanisms underlying their generation in HCC are poorly understood. Ten-eleven translocation-2 (TET2), a predominant epigenetic regulatory enzyme in B cells, regulates gene expression by catalyzing demethylation of 5-methylcytosine into 5-hydroxymethyl cytosine (5hmC). In this study, we investigated the role of TET2 in IL-10 + B cell generation in HCC and its prospects for clinical application.

APPROACH AND RESULTS

TET2 activation in B cells triggered by oxidative stress from the HCC microenvironment promoted IL-10 expression, whereas adoptive transfer of Tet2 -deficient B cells suppressed HCC progression. The aryl hydrocarbon receptor is required for TET2 to hydroxylate Il10 . In addition, high levels of IL-10, TET2, and 5hmc in B cells indicate poor prognosis in patients with HCC. Moreover, we determined TET2 activity using 5hmc in B cells to evaluate the efficacy of anti-programmed death 1 (anti-PD-1) therapy. Notably, TET2 inhibition in B cells facilitates antitumor immunity to improve anti-PD-1 therapy for HCC.

CONCLUSIONS

Our findings propose a TET2-dependent epigenetic intervention targeting IL-10 + B cell generation during HCC progression and identify the inhibition of TET2 activity as a promising combination therapy with immune checkpoint inhibitors for HCC.

Identification of IL-10 competent B cells in swine

Progress in the phenotypic characterisation of porcine B cells is ongoing, with recent advances in the identification of B1 cell subsets and plasma cells. However, regulatory B cells, commonly identified by interleukin (IL)-10 production, have not been studied in pigs so far. Here we investigate IL-10 expression in B cell subsets in response to CpG-oligodeoxynucleotides, phorbol 12-myristate 13-acetate and ionomycin stimulation in vitro. Our results reflect similar findings in human and mice. We identify a small subset of IL-10 competent B cells, present within both porcine B1 and B2 cell subsets across blood, spleen, mediastinal lymph nodes and lung tissue, with varied differentiation statuses. The capacity for IL-10 production coincided with CD95 expression, suggesting an activated phenotype of IL-10 competent B cells. These findings support the emerging paradigm that B cell IL-10 production is a function of various B cell subsets influenced by activation history and microenvironmental factors.

Current concepts of photosensitivity in cutaneous lupus erythematosus

Cutaneous lupus erythematosus (CLE) represents a complex autoimmune disease with a broad phenotypic spectrum ranging from acute to chronic destructive cutaneous lesions. Patients with CLE exhibit high photosensitivity and ultraviolet (UV) irradiation can lead to systemic flares in systemic lupus erythematosus. However, the exact mechanisms how UV irradiation enhances cutaneous inflammation in lupus are not fully understood. Recently, new molecular mechanisms of UV-driven immune responses in CLE were identified, offering potential therapeutic approaches. Especially the induction of type I interferons, central cytokines in lupus pathogenesis which are released by various skin cells, have become the focus of current research. In this review, we describe current pathogenic concepts of photosensitivity in lupus erythematosus, including UV-driven activation of intracellular nucleic acid sensors, cellular cytokine production and immune cell activation. Furthermore, we discuss activated pathways contributing to enhanced apoptosis as well as intracellular translocation of autoantigens thereby promoting CLE upon UV light exposure.

IL-10 revisited in systemic lupus erythematosus

IL-10 is a cytokine with pleiotropic functions, particularly known for its suppressive effects on various immune cells. Consequently, it can limit the pathogenesis of inflammatory diseases, such as multiple sclerosis (MS), inflammatory bowel disease, Crohn’s disease, and Epidermolysis bullosa acquisita, among others. Recent evidence however indicates that it plays dual roles in Systemic lupus Erythematosus (SLE) where it may inhibit pro-inflammatory effector functions but seems to be also a main driver of the extrafollicular antibody response, outside of germinal centers (GC). In line, IL-10 promotes direct differentiation of activated B cells into plasma cells rather than stimulating a GC response. IL-10 is produced by B cells, myeloid cells, and certain T cell subsets, including extrafollicular T helper cells, which are phenotypically distinct from follicular helper T cells that are relevant for GC formation. In SLE patients and murine lupus models extrafollicular T helper cells have been reported to support ongoing extrafollicular formation of autoreactive plasma cells, despite the presence of GCs. Here, we discuss the role of IL-10 as driver of B cell responses, its impact on B cell proliferation, class switch, and plasma cells.

Impact of DNA Prime/Protein Boost Vaccination against Campylobacter jejuni on Immune Responses and Gut Microbiota in Chickens

Campylobacteriosis is reported to be the leading zoonosis in Europe, and poultry is the main reservoir of Campylobacter. Despite all the efforts made, there is still no efficient vaccine to fight this bacterium directly in poultry. Recent studies have reported interactions between the chicken immune system and gut microbiota in response to Campylobacter colonisation. The present study was designed to analyse in more depth the immune responses and caecal microbiota following vaccination with a DNA prime/protein boost flagellin-based vaccine that induces some protection in specific-pathogen-free White Leghorn chickens, as shown previously. These data may help to improve future vaccination protocols against Campylobacter in poultry. Here a vaccinated and a placebo group were challenged by C. jejuni at the age of 19 days. A partial reduction in Campylobacter loads was observed in the vaccinated group. This was accompanied by the production of specific systemic and mucosal antibodies. Transient relatively higher levels of Interleukin-10 and antimicrobial peptide avian β-defensin 10 gene expressions were observed in the vaccinated and placebo groups respectively. The analysis of caecal microbiota revealed the vaccination's impact on its structure and composition. Specifically, levels of operational taxonomic units classified as Ruminococcaceae and Bacillaceae increased on day 40.

Cannabinoid Analogue WIN 55212-2 Protects Paraquat-Induced Lung Injury and Enhances Macrophage M2 Polarization

WIN 55212-2 is an endocannabinoids analogue that has been reported to have anti-inflammatory and anti-fibrosis effects on different models. In this study, we investigated the protective effects of WIN 55212-2 on paraquat (PQ)-induced poison on mice especially on lung injury. Mice were administrated with different dose of PQ and thereafter treated with 0.2 mg/kg or 1 mg/kg WIN 55212-2. The survival of mice was recorded during 4 weeks of observation. Twenty-eight days after PQ treatment, the cell population and inflammatory factors IL-6, IL-10, and TNF-α were measured in bronchoalveolar lavage fluid (BALF). Pulmonary fibrosis was evaluated by Masson staining. Our results showed that WIN 55212-2 treatment reduced PQ-induced mortality of mice in a dose dependent manner. It decreased the number of inflammation-associated cells, as well as the level of pro-inflammatory factors in BALF (P < 0.05). WIN 55212-2 increased M2 cells in BALF (P < 0.05), improved the lung histology, reduced fibrosis formation, and decreased TGF-β, α-SMA and PDGFRa expression. The protective effects of WIN 55212-2 on PQ-induced lung injury and fibrosis were associated with an increase inM2 cells and increased expressions of IL-10, CD163, and CD206, suggesting that polarization of M2 macrophages may be involved in WIN 55212-2 protective effects on PQ-induced lung injury.

Allogeneic lymphocytes immunotherapy in female infertility: Lessons learned and the road ahead

The endometrium is an essential tissue in the normal immunologic dialogue between the mother and the conceptus, which is necessary for the proper establishment and maintenance of a successful pregnancy. It's become evident that the maternal immune system plays a key role in the normal pregnancy's initiation, maintenance, and termination. In this perspective, the immune system contributes to regulating all stages of pregnancy, thus immunological dysregulation is thought to be one of the major etiologies of implantation failures. Many researchers believe that immune therapies are useful tactics for improving the live births rate in certain situations. Lymphocyte immunotherapy (LIT) is an active form of immunotherapy that, when used on the relevant subgroups of patients, has been shown in multiple trials to dramatically enhance maternal immunological balance and pregnancy outcome. The primary goal of LIT is to regulate the immune system in order to create a favorable tolerogenic immune milieu and tolerance for embryo implantation. However, there are a plethora of influential factors influencing its therapeutic benefits that merit to be addressed. The objective of our study is to discuss the mechanisms and challenges of allogeneic LIT.

Characterization of Definitive Regulatory B Cell Subsets by Cell Surface Phenotype, Function and Context

Regulatory B cell or “Breg” is a broad term that represents the anti-inflammatory activity of B cells, but does not describe their individual phenotypes, specific mechanisms of regulation or relevant disease contexts. Thus, given the variety of B cell regulatory mechanisms reported in human disease and their animal models, a more thorough and comprehensive identification strategy is needed for tracking and comparing B cell subsets between research groups and in clinical settings. This review summarizes the discovery process and mechanism of action for well-defined regulatory B cell subsets with an emphasis on the mouse model of multiple sclerosis experimental autoimmune encephalomyelitis. We discuss the importance of conducting thorough B cell phenotyping along with mechanistic studies prior to defining a particular subset of B cells as Breg. Since virtually all B cell subsets can exert regulatory activity, it is timely for their definitive identification across studies.

Glutaminolysis is required in maintaining immune regulatory functions in B cells

IL-10-expressing regulatory B cells (B10 cells) are dysfunctional in patients with many immune disorders. The underlying mechanism remains to be further elucidated. Glutamine is an essential nutrient for cell metabolism. This study aims to elucidate the role of glutaminolysis in maintaining the immune regulatory capacity in B10 cells. Peripheral blood samples were collected from 50 patients with allergic rhinitis and 50 healthy control subjects. B cells were isolated from blood samples by cell sorting with flow cytometry. The role of glutaminolysis in regulating B10 cell activities was assessed by immunological and biochemical approaches. The results showed that B cells from patients with allergic rhinitis expressed low levels of the transporter of glutamine and neutral amino acid. Glutaminolysis was required in the IL-10 expression in B cells. The glutamine catabolism was required in B10 cell generation. The mTOR activation mediated the glutaminolysis-associated B10 cell induction, and the suppression of the B cell glycogen synthase kinase-3 (GSK3) activation. GSK3 activation suppressed IL-10 expression in B cells. Inhibition of GSK3 enhanced IL-10 expression in B cells and alleviated experimental allergic rhinitis by generating immune competent type 1 regulatory T cells.

Glutamine promotes the generation of B10+ cells via the mTOR/GSK3 pathway

Alterations in cell metabolism can shift the differentiation of immune cells towards a regulatory or inflammatory phenotype, thus opening up new therapeutic opportunities for immune-related diseases. Indeed, growing knowledge on T cell metabolism has revealed differences in the metabolic programs of suppressive regulatory T cells (Tregs) as compared to inflammatory Th1 and Th17 cells. In addition to Tregs, IL-10-producing regulatory B cells are crucial for maintaining tolerance, inhibiting inflammation and autoimmunity. Yet, the metabolic networks regulating diverse B lymphocyte responses are not well known. Here, we show that glutaminase blockade decreased downstream mTOR activation and attenuated IL-10 secretion. Direct suppression of mTOR activity by rapamycin selectively impaired IL-10 production by B cells whereas secretion was restored upon GSK3 inhibition. Mechanistically, we found mTORC1 activation leads to GSK3 inhibition, identifying a key signalling pathway regulating IL-10 secretion by B lymphocytes. Thus, our results identify glutaminolysis and the mTOR/GSK3 signalling axis, as critical regulators of the generation of IL-10 producing B cells with regulatory functions. This article is protected by copyright. All rights reserved.

Targeting B cells in the pre-phase of systemic autoimmunity globally interferes with autoimmune pathology

Systemic lupus erythematosus (SLE) is characterized by a loss of self-tolerance, systemic inflammation, and multi-organ damage. While a variety of therapeutic interventions are available, it has become clear that an early diagnosis and treatment may be key to achieve long lasting therapeutic responses and to limit irreversible organ damage. Loss of humoral tolerance including the appearance of self-reactive antibodies can be detected years before the actual onset of the clinical autoimmune disease, representing a potential early point of intervention. Not much is known, however, about how and to what extent this pre-phase of disease impacts the onset and development of subsequent autoimmunity. By targeting the B cell compartment in the pre-disease phase of a spontaneous mouse model of SLE we now show, that resetting the humoral immune system during the clinically unapparent phase of the disease globally alters immune homeostasis delaying the downstream development of systemic autoimmunity.

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The clinically unapparent pre-phase of SLE impacts clinical disease

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Autoreactive IgM antibodies represent a biomarker for early therapeutic intervention

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Pre-phase B cells orchestrate clinical disease

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Depleting pre-phase B cells diminishes disease pathology

Loss of Lymphotoxin Alpha-Expressing Memory B Cells Correlates with Metastasis of Human Primary Melanoma

Activated antigen-experienced B cells play an unexpected complex role in anti-tumor immunity in human melanoma patients. However, correlative studies between B cell infiltration and tumor progression are limited by the lack of distinction between functional B cell subtypes. In this study, we examined a series of 59 primary and metastatic human cutaneous melanoma specimens with B cell infiltration. Using seven-color multiplex immunohistochemistry and automated tissue imaging and analysis, we analyzed the spatiotemporal dynamics of three major antigen-experienced B cell subpopulations expressing lymphotoxin alpha (LTA/TNFSF1) or interleukin-10 (IL-10) outside tertiary lymphoid structures. The expression of both LTA and IL-10 was not restricted to a particular B cell subtype. In primary melanomas, these cells were predominantly found at the invasive tumor-stroma front and, in metastatic melanomas, they were also found in the intratumoral stroma. In primary melanomas, decreased densities of LTA⁺ memory-like and, to a lesser extent, activated B cells were associated with metastasis. Compared with metastatic primary tumors, B cell infiltrates in melanoma metastases were enriched in both LTA⁺ memory-like and LTA⁺ activated B cells, but not in any of the IL-10⁺ B cell subpopulations. Melanoma disease progression shows distinct dynamics of functional B cell subpopulations, with the regulation of LTA⁺ B cell numbers being more significant than IL-10⁺ B cell subpopulations.

Immunoregulation by antibody secreting cells in inflammation, infection, and cancer

Antibody-secreting cells (ASCs) are considered work horses of the humoral immune response for their tireless effort to produce large amounts of antibodies that fulfill an array of functions in host defense, inflammation, and maintenance of homeostasis. While traditionally considered largely senescent cells, surprising recent findings demonstrate that subsets of ASCs downmodulate ongoing immune responses independent of antibody formation. Such regulatory ASCs produce IL-10 or IL-35 and are implicated in maintaining tissue and immune homeostasis. They also serve to suppress pathogenic leukocytes in infection, allergy, and inflammatory diseases that affect tissues, such as the central nervous system and the respiratory tract. Additionally, regulatory ASCs infiltrate various cancer types and restrict effective anti-tumor T cell responses. While incompletely understood, there is significant overlap in factors that control ASC differentiation, IL-10 expression by B cells and the generation of ASCs that secrete both antibodies and IL-10. In this review, we will cover the biology, phenotype, generation, maintenance and function of regulatory ASCs in various tissues under pathological and steady states. An improved understanding of the development of regulatory ASCs and their biological roles will be critical for generating novel ASC-targeted therapies for the treatment of inflammatory diseases, infection, and cancer.

TGF-β-secreting regulatory B cells: unsung players in immune regulation

Regulatory B cells contribute to the regulation of immune responses in cancer, autoimmune disorders, allergic conditions and inflammatory diseases. Although most studies focus on regulatory B lymphocytes expressing interleukin-10, there is growing evidence that B cells producing transforming growth factor β (TGF-β) can also regulate T-cell immunity in inflammatory diseases and promote the emergence of regulatory T cells that contribute to the induction and maintenance of natural and induced immune tolerance. Most research on TGF-β⁺ regulatory B cells has been conducted in models of allergy, cancer and autoimmune diseases, but there has, as yet, been limited scrutiny of their role in the transplant setting. Herein, we review recent investigations seeking to understand how TGF-β-producing B cells direct the immune response in various inflammatory diseases and whether these regulatory cells may have a role in fostering tolerance in transplantation.

Connection of BANK1, Tolerance, Regulatory B cells, and Apoptosis: Perspectives of a Reductionist Investigation

BANK1 transcript is upregulated in whole blood after kidney transplantation in tolerant patients. In comparison to patients with rejection, tolerant patients display higher level of regulatory B cells (Bregs) expressing granzyme B (GZMB⁺) that have the capability to prevent effector T cells proliferation. However, BANK1 was found to be decreased in these GZMB⁺ Bregs. In this article, we investigated seven different transcriptomic studies and mined the literature in order to make link between BANK1, tolerance and Bregs. As for GZMB⁺ Bregs, we found that BANK1 was decreased in other subtypes of Bregs, including IL10⁺ and CD24^hiCD38^hi transitional regulatory B cells, along with BANK1 was down-regulated in activated/differentiated B cells, as in CD40-activated B cells, in leukemia and plasma cells. Following a reductionist approach, biological concepts were extracted from BANK1 literature and allowed us to infer association between BANK1 and immune signaling pathways, as STAT1, FcγRIIB, TNFAIP3, TRAF6, and TLR7. Based on B cell signaling literature and expression data, we proposed a role of BANK1 in B cells of tolerant patients that involved BCR, IP3R, and PLCG2, and a link with the apoptosis pathways. We confronted these data with our experiments on apoptosis in total B cells and Bregs, and this suggests different involvement for BANK1 in these two cells. Finally, we put in perspective our own data with other published data to hypothesize two different roles for BANK1 in B cells and in Bregs.

The identification, development and therapeutic potential of IL-10-producing regulatory B cells in multiple sclerosis

Regulatory B cells are a rare B-cell subset widely known to exert their immunosuppressive function via the production of interleukin-10 (IL-10) and other mechanisms. B10 cells are a special subset of regulatory B cells with immunoregulatory function that is fully attributed to IL-10. Their unique roles in the animal model of multiple sclerosis (MS) have been described, as well as their relevance in MS patients. This review specifically focuses on the identification and development of B10 cells, the signals that promote IL-10 production in B cells, the roles of B10 cells in MS, and the potential and major challenges of the application of B10-based therapies for MS.

Characterization of Circulating IL-10-Producing Cells in Septic Shock Patients: A Proof of Concept Study

Sepsis is a worldwide health priority characterized by the occurrence of severe immunosuppression associated with increased risk of death and secondary infections. Interleukin 10 (IL-10) is a potent immunosuppressive cytokine which plasma concentration is increased in septic patients in association with deleterious outcomes. Despite studies evaluating IL-10 production in specific subpopulations of purified cells, the concomitant description of IL-10 production in monocytes and lymphocytes in septic patients' whole blood has never been performed. In this pilot study, we characterized IL-10 producing leukocytes in septic shock patients through whole blood intracellular staining by flow cytometry. Twelve adult septic shock patients and 9 healthy volunteers were included. Intracellular tumor necrosis factor-α (TNFα) and IL-10 productions after lipopolysaccharide stimulation by monocytes and IL-10 production after PMA/Ionomycine stimulation by lymphocytes were evaluated. Standard immunomonitoring (HLA-DR expression on monocytes, CD4+ T lymphocyte count) of patients was also performed. TNFα expression by stimulated monocytes was reduced in patients compared with controls while IL-10 production was increased. This was correlated with a reduced monocyte HLA-DR expression. B cells, CD4+, and CD4- T lymphocytes were the three circulating IL-10 producing lymphocyte subsets in both patients and controls. No difference in IL-10 production between patients and controls was observed for B and CD4- T cells. However, IL-10 production by CD4+ T lymphocytes significantly increased in patients in parallel with reduced CD4+ T cells number. Parameters reflecting altered monocyte (increased IL-10 production, decreased HLA-DR expression and decreased TNFα synthesis) and CD4+ T lymphocyte (increased IL-10 production, decreased circulating number) responses were correlated. Using a novel technique for intracellular cytokine measurement in whole blood, our results identify monocytes and CD4+ T cells as the main IL-10 producers in septic patients' whole blood and illustrate the development of a global immunosuppressive profile in septic shock. Overall, these preliminary results add to our understanding of the global increase in IL-10 production induced by septic shock. Further research is mandatory to determine the pathophysiological mechanisms leading to such increased IL-10 production in monocytes and CD4+ T cells.

Use of Toll-Like Receptor (TLR) Ligation to Characterize Human Regulatory B-Cells Subsets

Toll-like receptors (TLRs) are pattern recognition receptors (PRRs), which constitute key components in the recognition of pathogens, thereby initiating innate immune responses and promoting adaptive immune responses. In B cells, TLR ligation is important for their activation and, together with CD40, for their differentiation. TLR ligands are also strong promoters of regulatory B (Breg)-cell development, by enhancing the production of IL-10 and their capacity to induce tolerance. In inflammatory diseases, such as autoimmunity or allergies, Breg-cell function is often impaired, while in chronic infections, such as with helminths, or cancer, Breg-cell function is boosted. Following pathogen exposure, B cells can respond directly by producing cytokines and/or IgM (innate response) and develop into various memory B (Bmem)-cell subsets with class-switched immunoglobulin receptors. Depending on the disease state or chronic infection conditions, various Breg subsets can be recognized as well. Currently, a large array of surface markers is known to distinguish between these large range of B-cell subsets. In recent years, the development of mass cytometers and spectral flow cytometry has allowed for high-dimensional detection of up to 48 markers, including both surface and intracellular/intranuclear markers. Therefore, this novel technology is highly suitable to provide a comprehensive overview of Bmem/Breg-cell subsets in different disease states and/or in clinical intervention trials. Here, we provide detailed instructions of the steps necessary to obtain high-quality data for high-dimensional analysis of multiple human Breg-cell subsets using various TLR ligands.

The Potential Role of Regulatory B Cells in Idiopathic Membranous Nephropathy

Regulatory B cells (Breg) are widely regarded as immunomodulatory cells which play an immunosuppressive role. Breg inhibits pathological autoimmune response by secreting interleukin-10 (IL-10), transforming growth factor-β (TGF-β), and adenosine and through other ways to prevent T cells and other immune cells from expanding. Recent studies have shown that different inflammatory environments induce different types of Breg cells, and these different Breg cells have different functions. For example, Br1 cells can secrete IgG4 to block autoantigens. Idiopathic membranous nephropathy (IMN) is an autoimmune disease in which the humoral immune response is dominant and the cellular immune response is impaired. However, only a handful of studies have been done on the role of Bregs in this regard. In this review, we provide a brief overview of the types and functions of Breg found in human body, as well as the abnormal pathological and immunological phenomena in IMN, and propose the hypothesis that Breg is activated in IMN patients and the proportion of Br1 can be increased. Our review aims at highlighting the correlation between Breg and IMN and proposes potential mechanisms, which can provide a new direction for the discovery of the pathogenesis of IMN, thus providing a new strategy for the prevention and early treatment of IMN.

Regulation of neuroinflammation by B cells and plasma cells

The remarkable success of anti-CD20 B cell depletion therapies in reducing the burden of multiple sclerosis (MS) disease has prompted significant interest in how B cells contribute to neuroinflammation. Most focus has been on identifying pathogenic CD20⁺ B cells. However, an increasing number of studies have also identified regulatory functions of B lineage cells, particularly the production of IL-10, as being associated with disease remission in anti-CD20-treated MS patients. Moreover, IL-10-producing B cells have been linked to the attenuation of inflammation in experimental autoimmune encephalomyelitis (EAE), the animal model of MS. In addition to IL-10-producing B cells, antibody-producing plasma cells (PCs) have also been implicated in suppressing neuroinflammation. This review will examine regulatory roles for B cells and PCs in MS and EAE. In addition, we speculate on the involvement of regulatory PCs and the cytokine BAFF in the context of anti-CD20 treatment. Lastly, we explore how the microbiota could influence anti-inflammatory B cell behavior. A better understanding of the contributions of different B cell subsets to the regulation of neuroinflammation, and factors that impact the development, maintenance, and migration of such subsets, will be important for rationalizing next-generation B cell-directed therapies for the treatment of MS.

Phenotypes, Functions, and Clinical Relevance of Regulatory B Cells in Cancer

In immune system, B cells are classically positive modulators that regulate inflammation and immune responses. Regulatory B cells (Bregs) are a subset of B cells which play crucial roles in various conditions, including infection, allergies, autoimmune diseases, transplantation, and tumors. Until now, unequivocal surface markers for Bregs still lack consensus, although numerous Breg subsets have been identified. Generally, Bregs exert their immunoregulatory functions mainly through cytokine secretion and intercellular contact. In the tumor microenvironment, Bregs suppress effector T cells, induce regulatory T cells and target other tumor-infiltrating immune cells, such as myeloid-derived suppressor cells, natural killer cells and macrophages, to hamper anti-tumor immunity. Meanwhile, the cross-regulations between Bregs and tumor cells often result in tumor escape from immunosurveillance. In addition, accumulating evidence suggests that Bregs are closely associated with many clinicopathological factors of cancer patients and might be potential biomarkers for accessing patient survival. Thus, Bregs are potential therapeutic targets for future immunotherapy in cancer patients. In this review, we will discuss the phenotypes, functions, and clinical relevance of Bregs in cancer.

Association of CD200 expression in paternal lymphocytes with female Th1/Th2 balance and pregnancy establishment at immunotherapy of recurrent spontaneous abortion

PROBLEM

We hypothesized that expression of transmembrane glycoprotein CD200 on paternal lymphocytes used for pre-gestational lymphocyte immunotherapy (LIT) of recurrent spontaneous abortion (RSA) can suppress the pro-inflammatory Th1-type immunity required for successful implantation. To reveal the association between CD200 expression, female immune background after LIT, and pregnancy establishment, we have performed this work.

METHOD OF STUDY

Pre-gestational alloimmunizations were given to 37 women using paternal peripheral blood leukocytes, combined with additional alloimmunizations in case of pregnancy. Lymphocyte phenotypes were determined by flow cytometry. Cytokines produced by mitogen-stimulated female peripheral blood cells were estimated by FlowCytomix™ technology.

RESULTS

We have shown that 78.4% (29/37) of women became pregnant within 12 menstrual cycles after pre-gestational LIT. Pregnancy establishment depends on the intensity of CD200 expression, which is significantly higher on the CD200⁺ lymphocytes administered to women who later did not achieve pregnancy (P < .05). The expression of CD200 negatively correlates with the ratios of Th1/Th2 cytokines produced by female peripheral blood cells (P < .05) and positively correlates with the frequency of female circulating regulatory T cells after LIT (P < .05). The ROC analysis showed that the intensity of CD200 expression and the Th1/Th2 ratios are the significant predictors of pregnancy establishment after pre-gestational LIT (P < .05 and P < .01, respectively).

CONCLUSION

Elevated CD200 expression on allogeneic lymphocytes most likely suppresses the pro-inflammatory Th1-type immunity needed for successful embryo implantation. Therefore, a personalized approach of LIT should be applied to avoid negative effects of such immunomodulation on pregnancy establishment.

Astilbin combined with lipopolysaccharide induces IL-10-producing regulatory B cells via the STAT3 signalling pathway

OBJECTIVES

Astilbin exerts immunoregulatory activities and plays anti-inflammatory effects in inflammation-associated diseases. IL-10-producing B cells are the major subset of regulatory B cells (Bregs) and inhibit inflammation and autoimmune diseases. This study aimed to analyse the inducing effect of astilbin on Bregs and investigate the involved molecular mechanisms.

METHODS

The frequencies and activities of IL-10-producing Bregs were observed using the co-treatment of astilbin and lipopolysaccharide (LPS) ex vivo. The protective effect of astilbin/LPS-induced Bregs on dextran sulphate sodium (DSS)-induced colitis was confirmed in vivo. The molecular signalling events of Breg induction were checked via Western blot. CD40^-/- and toll-like receptor (TLR) 4^-/- B cells were treated with astilbin/LPS to determine the modulatory role of CD40 or TLR4 on astilbin/LPS-induced Bregs.

RESULTS

Although astilbin alone could not affect Bregs, the co-treatment of astilbin and LPS remarkably induced CD19⁺ CD1d^hi and CD19⁺ TIM-1⁺ cells which produced IL-10 ex vivo. Colonic CD19⁺ CD1d^hi and CD19⁺ TIM-1⁺ cells were also increased in astilbin-treated mice with DSS-induced colitis. The adoptive transfer of CD19⁺ TIM-1⁺ cells pre-induced by astilbin/LPS directly suppressed the progression of DSS-induced colitis. Combined astilbin and LPS stimulated the STAT3 activation of CD19⁺ TIM-1⁺ cells but had no effects on SOCS3, AKT, NF-κB, Erk, JNK nor P38. Inhibiting the STAT3 phosphorylation of CD19⁺ TIM-1⁺ cells abolished Breg induction by astilbin/LPS. Furthermore, Breg induction was weakened in CD40^-/- B cells with the decrease in STAT3 activation, but had disappeared in TLR4^-/- B cells with no STAT3 activation, thereby confirming the indispensable role of TLR4 signalling in the induction of IL-10-producing Bregs.

CONCLUSIONS

This study reports the new immunoregulatory role of astilbin for promoting IL-10-producing B cells and suggests the possible use of astilbin in the therapy of inflammatory diseases.

Correlation between serum levels of endothelin-1 and disease severity in patients with neuromyelitis optica spectrum disorders

AIMS

Neuromyelitis optica spectrum disorders (NMOSD) are aquaporin-4 antibody-mediated diseases of the central nervous system. Endothelin-1 (ET-1) is an inflammatory cytokine released by vascular endothelial cells and activated astrocytes. Previous studies have reported the aberrant expressions of cytokines/chemokines in patients diagnosed with NMOSD. However, the serum levels of ET-1 in NMOSD patients remain unknown. The purpose of this study was to measure the serum levels of ET-1 and other immune-related cytokines/chemokines in patients with NMOSD, and to investigate the correlation between serum ET-1 levels and clinical characteristics of NMOSD.

METHODS

Thirty-eight patients with NMOSD and twenty-eight healthy controls (HCs) were recruited in this study. The serum concentrations of ET-1 and other cytokines/chemokines were measured, and their correlations to the clinical features of patients with NMOSD were analyzed.

RESULTS

The serum levels of ET-1 in patients with NMOSD were significantly higher than those in HCs (P =  0.0001). The serum concentrations of ET-1 were positively correlated with the Expanded Disability Status Scale score (r = 0.428, P = 0.0183). High-dose intravenous methylprednisolone treatment significantly reduced the levels of ET-1 and interleukin (IL)-6 in blood, but significantly increased the serum concentrations of IL-10 in NMOSD patients. No correlations were found between serum ET-1 levels and the concentrations of other cytokines/chemokines in these patients.

CONCLUSION

ET-1 and IL-6 might exert pro-inflammatory effects in the pathogenesis of NMOSD, whereas IL-10 played an anti-inflammatory role in this process. ET-1 might be a potential biomarker for predicting the severity of NMOSD. However, the serum levels of ET-1 were not correlated with the changes of other cytokines/chemokines in patients with NMOSD. The involvement of ET-1 in the development of NMOSD needs to be further studied.

The immune response of inbred laboratory mice to Litomosoides sigmodontis: A route to discovery in myeloid cell biology

Litomosoides sigmodontis is the only filarial nematode where the full life cycle, from larval delivery to the skin through to circulating microfilaria, can be completed in immunocompetent laboratory mice. It is thus an invaluable tool for the study of filariasis. It has been used for the study of novel anti‐helminthic therapeutics, the development of vaccines against filariasis, the development of immunomodulatory drugs for the treatment of inflammatory disease and the study of basic immune responses to filarial nematodes. This review will focus on the latter and aims to summarize how the L sigmodontis model has advanced our basic understanding of immune responses to helminths, led to major discoveries in macrophage biology and provided new insights into the immunological functions of the pleural cavity. Finally, and most importantly L sigmodontis represents a suitable platform to study how host genotype affects immune responses, with the potential for further discovery in myeloid cell biology and beyond.

Vaccination Against Tuberculosis: Revamping BCG by Molecular Genetics Guided by Immunology

Tuberculosis (TB) remains a major health threat. Although a vaccine has been available for almost 100 years termed Bacille Calmette-Guérin (BCG), it is insufficient and better vaccines are urgently needed. This treatise describes first the basic immunology and pathology of TB with an emphasis on the role of T lymphocytes. Better understanding of the immune response to Mycobacterium tuberculosis (Mtb) serves as blueprint for rational design of TB vaccines. Then, disease epidemiology and the benefits and failures of BCG vaccination will be presented. Next, types of novel vaccine candidates are being discussed. These include: (i) antigen/adjuvant subunit vaccines; (ii) viral vectored vaccines; and (III) whole cell mycobacterial vaccines which come as live recombinant vaccines or as dead whole cell or multi-component vaccines. Subsequently, the major endpoints of clinical trials as well as administration schemes are being described. Major endpoints for clinical trials are prevention of infection (PoI), prevention of disease (PoD), and prevention of recurrence (PoR). Vaccines can be administered either pre-exposure or post-exposure with Mtb. A central part of this treatise is the description of the viable BCG-based vaccine, VPM1002, currently undergoing phase III clinical trial assessment. Finally, new approaches which could facilitate design of refined next generation TB vaccines will be discussed.