IL-10 produced by activated human B cells regulates CD4(+) T-cell activation in vitro

Posttransplantation cyclophosphamide mediates effective reconstitution of memory B cells after allogeneic hematopoietic cell transplantation

OBJECTIVES

Impaired B-cell reconstitution after allogeneic hematopoietic cell transplantation (allo-HCT) contributes to the pathogenesis of chronic graft-versus-host disease (cGVHD). Therefore, methods to consistently achieve effective B cell lymphogenesis are required. We assessed the long-term effects of posttransplantation cyclophosphamide (PTCy) use on immune reconstitution in clinical settings, an emerging strategy to suppress allogeneic immunological inflammation early after allo-HCT and prevent subsequent GVHD.

METHODS

We comprehensively analyzed peripheral immune cell subsets and measured serum immunoglobulin G (IgG) or cytokine levels in 39 patients who survived for >1 year after allo-HCT.

RESULTS

The absolute counts of B1 and IgM memory B cells were significantly lower in patients with severe cGVHD than in those without. The absolute count and percentage (among total CD19+ B cells) of switched memory B cells and serum IgG levels were significantly higher in patients transplanted with PTCy than in those transplanted with conventional GVHD prophylaxis. Interestingly, increased percentages of switched memory B cells and serum IgG levels were observed only in patients transplanted with PTCy and not in those transplanted with umbilical cord blood.

CONCLUSIONS

PTCy administration can mediate favorable memory B-cell reconstitution long after allo-HCT and may therefore suppress cGVHD.

Mechanisms of Resistance to Rituximab Used for the Treatment of Autoimmune Blistering Diseases

Autoimmune blistering diseases represent a group of chronic severe, disabling, and potentially fatal disorders of the skin and/or mucous membranes, primarily mediated by pathogenic auto-antibodies. Despite their rarity, these diseases are associated with significant morbidity and mortality and profound negative impact on the patient's quality of life and impose a considerable economic burden. Rituximab, an anti-CD-20 monoclonal antibody, represents the first line of therapy for pemphigus, regardless of severity and a valuable off-label therapeutic alternative for subepidermal autoimmune blistering diseases as it ensures high rates of rapid, long-lasting complete remission. Nevertheless, disease recurrence is the rule, all patients requiring maintenance therapy with rituximab eventually. While innate resistance to rituximab in pemphigus patients is exceptional, acquired resistance is frequent and may develop even in patients with initial complete response to rituximab, representing a real challenge for physicians. We discuss the various resistance mechanisms and their complex interplay, as well as the numerous therapeutic alternatives that may be used to circumvent rituximab resistance. As no therapeutic measure is universally efficient, individualization of rituximab treatment regimen and tailored adjuvant therapies in refractory autoimmune blistering diseases are mandatory.

The evolving landscape of IL-10, IL-22 and IL-26 in pleurisy especially in tuberculous pleurisy

Pleurisy can be categorized as primary or secondary, arising from immunological, tumorous, or microbial conditions. It often results in lung structure damage and the development of various respiratory issues. Among the different types, tuberculous pleurisy has emerged as a prominent focus for both clinical and scientific investigations. The IL-10 family, known for its anti-inflammatory properties in the human immune system, is increasingly being studied for its involvement in the pathogenesis of pleurisy. This review aims to present a detailed overview of the intricate role of IL-10 family members (specifically IL-10, IL-22, and IL-26) in human and animal pleuritic diseases or relevant animal models. These insights could serve as valuable guidance and references for further studies on pleurisy and potential therapeutic strategies.

Disrupted Microbiota of Colon Results in Worse Immunity and Metabolism in Low-Birth-Weight Jinhua Newborn Piglets

The Jinhua pig is well known in China due to its delicious meat. However, because of large litter size, low birth weight always happens. This experiment used this breed as a model to research bacterial evidence leading to growth restriction and provide a possible solution linked to probiotics. In this experiment, the differences in organs indexes, colonic morphology, short chain fatty acid (SCFA) concentrations, microbiome, and transcriptome were detected between piglets in the standard-birth-weight group (SG) and low-birth-weight group (LG) to find potential evidence leading to low birth weight. We found that LG piglets had a lower liver index (p < 0.05), deeper colonic crypt depth (p < 0.05), fewer goblet cells (p < 0.05), and more inflammatory factor infiltration. In addition, differentially expressed genes (DEGs) were mainly enriched in B-cell immunity and glucose metabolism, and LG piglets had lower concentrations of SCFAs, especially butyrate and isobutyrate (p < 0.05). Finally, most of the significantly differentially abundant microbes were fewer in LG piglets, which affected DEG expressions and SCFA concentrations further resulting in worse energy metabolism and immunity. In conclusion, colonic disrupted microbiota may cause worse glucose metabolism, immunity, and SCFA production in LG piglets, and beneficial microbes colonized in SG piglets may benefit these harmful changes.

Autoimmune Diseases and Plasma Cells Dyscrasias: Pathogenetic, Molecular and Prognostic Correlations

Multiple myeloma and monoclonal gammopathy of undetermined significance are plasma cell dyscrasias characterized by monoclonal proliferation of pathological plasma cells with uncontrolled production of immunoglobulins. Autoimmune pathologies are conditions in which T and B lymphocytes develop a tendency to activate towards self-antigens in the absence of exogenous triggers. The aim of our review is to show the possible correlations between the two pathological aspects. Molecular studies have shown how different cytokines that either cause inflammation or control the immune system play a part in the growth of immunotolerance conditions that make it easier for the development of neoplastic malignancies. Uncontrolled immune activation resulting in chronic inflammation is also known to be at the basis of the evolution toward neoplastic pathologies, as well as multiple myeloma. Another point is the impact that myeloma-specific therapies have on the course of concomitant autoimmune diseases. Indeed, cases have been observed of patients suffering from multiple myeloma treated with daratumumab and bortezomib who also benefited from their autoimmune condition or patients under treatment with immunomodulators in which there has been an arising or worsening of autoimmunity conditions. The role of bone marrow transplantation in the course of concomitant autoimmune diseases remains under analysis.

Red Blood Cell Alloimmunization in Pregnancy: A Review of the Pathophysiology, Prevalence, and Risk Factors

This review paper provides an overview of the risk factors and laboratory testing for red blood cell (RBC) alloimmunization in pregnancy. RBC alloimmunization is a significant medical issue that can cause haemolytic disease of the fetus and newborn (HDFN), leading to neonatal morbidity and mortality. Current HDFN prophylaxis targets only Rhesus D (RhD) alloimmunization, with no effective measures to prevent alloimmunization to other RBC antigen groups. Several factors can increase the risk of developing RBC alloimmunization during pregnancy, including fetomaternal haemorrhage, RBC and maternal genetic status, and previous transfusions. Identifying these risk factors is essential to execute the appropriate management strategies to minimize the risk of HDFN. The review also discusses the laboratory methods and overview of pregnancy management. The paper highlights the importance of identifying and managing the risk factors for RBC alloimmunization in pregnancy to minimize the risk of HDFN and improve neonatal outcomes.

Static electric field inhibits the proliferation and secretion functions of splenic lymphocytes in mice

In recent years, the effects of static electric field (SEF) generated by ultra-high voltage (UHV) direct current (DC) transmission lines on health has drawn public attention. To study the effects of SEF on the spleen, mice were exposed to 56.3 ± 1.4 kV/m SEF. Results showed that on the 28th day of SEF exposure, the contents of IL-10 and IFN-γ in the supernatant of homogenate, the proliferation levels of lymphocytes and the content of intracellular ROS decreased significantly, while the activity of SOD increased significantly. Meanwhile, the rupture of cellular membrane, the deficiency of mitochondrial cristae and the vacuolization of mitochondria appeared in lymphocytes. Analysis showed that the rupture of the cellular membrane caused the death of T lymphocytes, which would lead to the reduction of IL-10 and IFN-γ secretions. The damage of mitochondria could reduce the production of ATP and the content of ROS, which could inhibit the proliferation of splenic lymphocytes.

Advancing Biologic Therapy for Refractory Autoimmune Hepatitis

Biologic agents may satisfy an unmet clinical need for treatment of refractory autoimmune hepatitis. The goals of this review are to present the types and results of biologic therapy for refractory autoimmune hepatitis, indicate opportunities to improve and expand biologic treatment, and encourage comparative clinical trials. English abstracts were identified in PubMed by multiple search terms. Full-length articles were selected for review, and secondary and tertiary bibliographies were developed. Rituximab (monoclonal antibodies against CD20 on B cells), infliximab (monoclonal antibodies against tumor necrosis factor-alpha), low-dose recombinant interleukin 2 (regulatory T cell promoter), and belimumab (monoclonal antibodies against B cell activating factor) have induced laboratory improvement in small cohorts with refractory autoimmune hepatitis. Ianalumab (monoclonal antibodies against the receptor for B cell activating factor) is in clinical trial. These agents target critical pathogenic pathways, but they may also have serious side effects. Blockade of the B cell activating factor or its receptors may disrupt pivotal B and T cell responses, and recombinant interleukin 2 complexed with certain interleukin 2 antibodies may selectively expand the regulatory T cell population. A proliferation-inducing ligand that enhances T cell proliferation and survival is an unevaluated, potentially pivotal, therapeutic target. Fully human antibodies, expanded target options, improved targeting precision, more effective delivery systems, and biosimilar agents promise to improve efficacy, safety, and accessibility. In conclusion, biologic agents target key pathogenic pathways in autoimmune hepatitis, and early experiences in refractory disease encourage clarification of the preferred target, rigorous clinical trial, and comparative evaluations.

Expanding role of deoxyribonucleic acid-sensing mechanism in the development of lifestyle-related diseases

In lifestyle-related diseases, such as cardiovascular, metabolic, respiratory, and kidney diseases, chronic inflammation plays a causal role in their pathogenesis; however, underlying mechanisms of sterile chronic inflammation are not well-understood. Previous studies have confirmed the damage of cells in these organs in the presence of various risk factors such as diabetes, dyslipidemia, and cigarette smoking, releasing various endogenous ligands for pattern recognition receptors. These studies suggested that nucleic acids released from damaged tissues accumulate in these tissues, acting as an endogenous ligand. Undamaged DNA is an integral factor for the sustenance of life, whereas, DNA fragments, especially those from pathogens, are potent activators of the inflammatory response. Recent studies have indicated that inflammatory responses such as the production of type I interferon (IFN) induced by DNA-sensing mechanisms which contributes to self-defense system in innate immunity participates in the progression of inflammatory diseases by the recognition of nucleic acids derived from the host, including mitochondrial DNA (mtDNA). The body possesses several types of DNA sensors. Toll-like receptor 9 (TLR9) recognizes DNA fragments in the endosomes. In addition, the binding of DNA fragments in the cytosol activates cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) synthase (cGAS), resulting in the synthesis of the second messenger cyclic GMP-AMP (cGAMP). The binding of cGAMP to stimulator of interferon genes (STING) activates NF-κB and TBK-1 signaling and consequently the production of many inflammatory cytokines including IFNs. Numerous previous studies have demonstrated the role of DNA sensors in self-defense through the recognition of DNA fragments derived from pathogens. Beyond the canonical role of TLR9 and cGAS-STING, this review describes the role of these DNA-sensing mechanism in the inflammatory responses caused by endogenous DNA fragments, and in the pathogenesis of lifestyle-related diseases.

Regulatory Role of B Cells and Its Subsets in Hepatitis E Virus Infection

Antibodies as well as memory B cells are the potential correlates of a protective immune response against hepatitis E virus (HEV) infection. Literature on the role of B regulatory cells (Bregs) in acute viral infections is limited. We have evaluated the role of IL-10 expressing Bregs in HEV infection. A total of 108 acute hepatitis E patients, 55 hepatitis E recovered individuals and 128 HEV naïve healthy controls were enrolled. The percentages of peripheral CD19⁺, immature CD19⁺CD24^hiCD38^hi, mature CD19⁺CD24^intCD38^int and memory CD19⁺CD24^hiCD38⁻ B cells were analyzed by flowcytometry. Intracellular cytokine staining for IL-10 and TGF-β, HEV-rORF2p specific T cell response (IFN-γ expression) pre/post IL-10/IL-10R blocking and CD19⁺IL-10⁺ B cells-depletion based assays were carried out to assess the functionality of Bregs. The percentage of HEV-rORF2p specific immature B cell phenotype was significantly higher in acute hepatitis E patients compared to hepatitis E recovered individuals and controls. Significantly higher IL-10 expression on B and HEV-rORF2p stimulated immature B cells of acute hepatitis E patients compared to controls indicated that Bregs are functional and HEV-rORF2p specific. Enhanced IFN-γ expression on CD8⁺ T cells upon IL-10/IL-10R blocking and also post CD19⁺IL-10⁺ B cells depletion suggested that CD3⁺CD8⁺IFN-γ⁺ T cells corroborate the regulatory potential of Bregs via IL-10 dependent mechanism. We have identified HEV specific functional, immature CD19⁺CD24^hiCD38^hi B cells having IL-10 mediated regulatory activities and a potential to modulate IFN-γ mediated T cell response in Hepatitis E. The prognostic/pathogenic role of Bregs in recovery from severe hepatitis E needs evaluation.

Role of hormones in the pregnancy and sex-specific outcomes to infections with respiratory viruses

Pregnant women infected with pathogenic respiratory viruses, such as influenza A viruses (IAV) and coronaviruses, are at higher risk for mortality, hospitalization, preterm birth, and stillbirth. Several factors are likely to contribute to the susceptibility of pregnant individuals to severe lung disease including changes in pulmonary physiology, immune defenses, and effector functions of some immune cells. Pregnancy is also a physiologic state characterized by higher levels of multiple hormones that may impact the effector functions of immune cells, such as progesterone, estrogen, human chorionic gonadotropin, prolactin, and relaxin. Each of these hormones acts to support a tolerogenic immune state of pregnancy, which helps prevent fetal rejection, but may also contribute to an impaired antiviral response. In this review, we address the unique role of adaptive and innate immune cells in the control of pathogenic respiratory viruses and how pregnancy and specific hormones can impact their effector actions. We highlight viruses with sex-specific differences in infection outcomes and why pregnancy hormones may contribute to fetal protection but aid the virus at the expense of the mother's health.

Human IL-10-producing B cells have diverse states that are induced from multiple B cell subsets

Regulatory B cells (Bregs) suppress immune responses through the secretion of interleukin-10 (IL-10). This immunomodulatory capacity holds therapeutic potential, yet a definitional immunophenotype for enumeration and prospective isolation of B cells capable of IL-10 production remains elusive. Here, we simultaneously quantify cytokine production and immunophenotype in human peripheral B cells across a range of stimulatory conditions and time points using mass cytometry. Our analysis shows that multiple functional B cell subsets produce IL-10 and that no phenotype uniquely identifies IL-10+ B cells. Further, a significant portion of IL-10+ B cells co-express the pro-inflammatory cytokines IL-6 and tumor necrosis factor alpha (TNFα). Despite this heterogeneity, operationally tolerant liver transplant recipients have a unique enrichment of IL-10+, but not TNFα+ or IL-6+, B cells compared with transplant recipients receiving immunosuppression. Thus, human IL-10-producing B cells constitute an induced, transient state arising from a diversity of B cell subsets that may contribute to maintenance of immune homeostasis.

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.

Chronic obstructive pulmonary disease is characterized by reduced levels and defective suppressive function of regulatory B cells in peripheral blood

Chronic obstructive pulmonary disease (COPD) is characterized by a progressive, persistent immune response to cigarette smoke, and it has been suggested that immune dysregulation is involved in its pathogenesis. A subset of regulatory B cells (Bregs) with high levels of the surface markers CD24 and CD38 (CD24^hiCD38^hi) has previously been shown to exert an immunosuppressive function. This study investigated the levels and activity of CD24^hiCD38^hi Bregs in stable COPD (sCOPD). Testing the peripheral blood from 65 patients with sCOPD and 39 control subjects for CD24^hiCD38^hi Breg subsets by flow cytometry showed that the patients with sCOPD had significantly lower levels of CD24^hiCD38^hi Bregs and IL-10⁺ B cells. The patients with sCOPD had lower serum interleukin-10 levels than the controls. The patients with most severe sCOPD had the lowest levels of CD24^hiCD38^hi Bregs. Spearman correlation analysis showed that the levels of CD24^hiCD38^hi Bregs in the patients with sCOPD positively correlated with serum interleukin-10 concentrations but not with levels of C-reactive protein. Compared to healthy controls, functional studies showed that Breg cells from patients with sCOPD exhibit a decreased suppressive function. We conclude that sCOPD is characterized by the exhaustion of CD24^hiCD38^hi regulatory B cells compartment. Therefore, CD24^hiCD38^hi Bregs may contribute to the pathogenesis of sCOPD.

SDF-1α Facilitates Mesenchymal Stem Cells to Induce Regulatory B Cell Differentiation from Patients with Immune Thrombocytopenia

B cells play a central role in the pathogenesis of immune thrombocytopenia (ITP) by participating in humoral immunity. Meanwhile, regulatory B cells (Bregs), one subset of B cells, express negative regulatory effect on ITP. Mesenchymal stem cells (MSCs) have been demonstrated in the ability to induce immunosuppression, and stromal cell-derived factor-1α (SDF-1α) plays an important role in the migration and survival of MSCs. To investigate the mechanism of SDF-1α in controlling umbilical cord-derived MSCs (UC-MSCs) in inducing regulatory B cell differentiation of patients with ITP, we reconfirmed that SDF-1α promotes the proliferation of MSCs at the low doses of 0.05 μg/mL and 0.1 μg/mL but inhibits the proliferation and promotes the apoptosis of UC-MSCs at the high doses 0.5 μg/mL and 1 μg/mL; when UC-MSCs are cocultured with SDF-1α at 0.1 μg/mL, the decreased proportion of CD19⁺/CD24^hi/CD38^hi cells and IL-10-producing B cells (B 10 cell), considered as the Breg subset from ITP significantly enhanced, and the content of IL-10 in the supernatant is also obviously increased. The proportion of Bregs and the IL-10 secretion could be further promoted by the UC-MSCs treated with 0.1 μg/mL SDF-1α, which could also promote the miRNA-133 expression of UC-MSCs in an exosome-dependent manner; moreover, while the UC-MSCs were transfected with the miR-133 inhibitor, the proportion of induced Bregs decreased obviously when cocultured with peripheral blood mononuclear cells (PBMCs) of ITP. We conclude that UC-MSCs could effectively enhance the decreased proportion of Bregs from ITP; at appropriate concentrations, SDF-1α may promote the proliferating and survival ability of UC-MSCs and improve the production of Bregs induced by UC-MSCs through controlling miRNA-133 expression in the exosomes.

Review article: targeting the B cell activation system in autoimmune hepatitis

BACKGROUND

The B cell activation system, consisting of B cell activating factor and a proliferation-inducing ligand, may have pathogenic effects in autoimmune hepatitis.

AIMS

To describe the biological actions of the B cell activation system, indicate its possible role in autoimmune diseases, and evaluate its prospects as a therapeutic target in autoimmune hepatitis METHODS: English abstracts were identified in PubMed by multiple search terms. Full length articles were selected for review, and secondary and tertiary bibliographies were developed.

RESULTS

The B cell activating factor is crucial for the maturation and survival of B cells, and it can co-stimulate T cell activation, proliferation, and survival. It can also modulate the immune response by inducing interleukin 10 production by regulatory B cells. A proliferation-inducing ligand modulates and diversifies the antibody response by inducing class-switch recombination in B cells. It can also increase the proliferation, survival, and antigen activation of T cells. These immune stimulatory actions can be modulated by inducing proliferation of regulatory T cells. The B cell activation system has been implicated in diverse autoimmune diseases, and therapeutic blockade is a management strategy now being evaluated in autoimmune hepatitis.

CONCLUSIONS

The B cell activation system has profound effects on B and T cell function in autoimmune diseases. Blockade therapy is being actively evaluated in autoimmune hepatitis. Clarification of the critical pathogenic components of the B cell activation system will improve the targeting, efficacy, and safety of blockade therapy in this disease.

Regulatory B Cells in Autoimmune Diabetes

Since they were discovered almost three decades ago, a subset of B cells denoted as regulatory B cells (Bregs) have elicited interest throughout the immunology community. Many investigators have sought to characterize their phenotype and to understand their function and immunosuppressive mechanisms. Indeed, studies in murine models have demonstrated that Bregs possess varied phenotypic markers and could be classified into different subsets whose action and pivotal role depend on the pathological condition or stimuli. Similar conclusions were drawn in clinical settings delineating an analogous Breg population phenotypically resembling the murine Bregs that ultimately may be associated with a state of tolerance. Recent studies suggested that Bregs may play a role in the onset of autoimmune diabetes. This review will focus on deciphering the different subclasses of Bregs, their emerging role in autoimmune diabetes, and their potential use as a cell-based therapeutic.

Abatacept Promotes Regulatory B Cell Functions, Enhancing Their Ability to Reduce the Th1 Response in Rheumatoid Arthritis Patients through the Production of IL-10 and TGF-β

Abatacept mimics natural CD152 and competes with CD28 for binding to CD80/CD86 on APC, such as B cells, thereby preventing T cell activation. However, its potential impact on B cells has not been identified. The aim of this study was to assess whether abatacept can potentiate the immunoregulatory properties of B cells in vitro and in patients with rheumatoid arthritis (RA). T and B cells from healthy controls were purified. The suppressor properties of B cells in the presence of abatacept or control IgG1 were evaluated based on the ability of these cells to inhibit the polyclonal expansion (anti-CD3/CD28 stimulation) of T cells or their differentiation into Th1 or Th17 cells. Similar analyses were also performed with cells from RA patients before and 3 mo after abatacept initiation. Abatacept significantly potentiated regulatory B cell regulatory functions by enhancing their ability to produce IL-10 and TGF-β, resulting in the increased generation of regulatory T cells and limited T cell proliferation and differentiation into Th1 and Th17 cells. Interestingly, B cells isolated from patients that received a 3-mo treatment with abatacept had an increased ability to reduce T cell functions, confirming the above observations. Abatacept binding to CD80/CD86 induces and promotes regulatory B cell functions by enhancing the ability of these cells to produce IL-10 and TGF-β in vitro and in RA patients.

CpG-ODN Signaling via Dendritic Cells-Expressing MyD88, but Not IL-10, Inhibits Allergic Sensitization

Allergen-specific T helper (Th)2 cells orchestrate upon allergen challenge the development of allergic eosinophilic lung inflammation. Sensitization with alum adjuvant, a type 2 adjuvant, has been used extensively in animal models of allergic lung disease. In contrast, type 1 adjuvants like CpG-ODN, a synthetic toll-like receptor 9 agonist, inhibit the development of Th2 immunity. CpG-ODN induce type 1 and suppressive cytokines that influence Th2 cell differentiation. Here, we investigated the immune modulatory effect of CpG-ODN on allergic sensitization to OVA with alum focusing on dendritic cells (DCs) expressing the MyD88 molecule and the suppressive IL-10 cytokine. Using mice with specific cell deletion of MyD88 molecule, we showed that CpG-ODN suppressed allergic sensitization and consequent lung allergic inflammation signaling through the MyD88 pathway on dendritic cells, but not on B-cells. This inhibition was associated with an increased production of IL-10 in the bronchoalveolar lavage fluid. Sensitization to OVA with CpG-ODN of IL-10-deficient, but not wild-type mice, induced a shift towards Th1 pattern of inflammation. Employing bone marrow-derived dendritic cells (BM-DCs) pulsed with OVA for sensitizations with or without CpG-ODN, we showed that IL-10 is dispensable for the inhibition of allergic lung Th2 responses by CpG-ODN. Moreover, the lack of IL-10 on DCs was not sufficient for the CpG-ODN-induced immune-deviation towards a Th1 pattern. Accordingly, we confirmed directly the role of MyD88 pathway on DCs in the inhibition of allergic sensitization.

Immunosuppressive Mechanisms of Regulatory B Cells

Regulatory B cells (Bregs) is a term that encompasses all B cells that act to suppress immune responses. Bregs contribute to the maintenance of tolerance, limiting ongoing immune responses and reestablishing immune homeostasis. The important role of Bregs in restraining the pathology associated with exacerbated inflammatory responses in autoimmunity and graft rejection has been consistently demonstrated, while more recent studies have suggested a role for this population in other immune-related conditions, such as infections, allergy, cancer, and chronic metabolic diseases. Initial studies identified IL-10 as the hallmark of Breg function; nevertheless, the past decade has seen the discovery of other molecules utilized by human and murine B cells to regulate immune responses. This new arsenal includes other anti-inflammatory cytokines such IL-35 and TGF-β, as well as cell surface proteins like CD1d and PD-L1. In this review, we examine the main suppressive mechanisms employed by these novel Breg populations. We also discuss recent evidence that helps to unravel previously unknown aspects of the phenotype, development, activation, and function of IL-10-producing Bregs, incorporating an overview on those questions that remain obscure.

Regulatory B Cells Dysregulated T Cell Function in an IL-35-Dependent Way in Patients With Chronic Hepatitis B

Interleukin (IL)-35-secreting B (IL-35+B) cells are critical regulators in autoimmune and infectious diseases and exert suppressive functions in parallel with IL-10-producing B (B10) cells. However, the role of IL-35+B cells in persistent hepatitis B virus (HBV) infection remains unclear. To elucidate the role of IL-35+B cells in the progress of chronic HBV infection, we determined the frequency of IL-35+B cells and their relationship with the classical human regulatory B cell (Breg) subsets, namely, CD19+CD24^hiCD38^hi and CD19+CD24^hiCD27+. Then, the regulatory effect and mechanism of Bregs on effector T cells were investigated in vitro. Here, we found that compared with healthy controls, the frequency of IL-35+B cells was increased in patients with chronic HBV infection and was enriched in human classical Breg subset CD19+CD24^hiCD38^hi B cells. Moderate correlation was observed between the frequency of IL-35+B cells and alanine aminotransferase levels (Spearman r = 0.401), but only mild correlation was noted between the frequency of IL-35+B cells and HBV DNA level (Spearman r = 0.314). The frequency of IL-35+B cells was negatively correlated with interferon-γ (IFN-γ)-producing CD4+ and CD8+ cells but positively correlated with IL-4-producing T cells. Bregs dysregulated T cell function through an IL-35-dependent mechanism and depended on cell-to-cell contact. In conclusion, IL-35+ B cell was enriched in CD19+CD24hiCD38hi B cell subset during persistent HBV infection and Breg cells exerted dysregulation in T cell function through IL-35 dependent mechanism and depend on cell-to-cell contact.

Ex vivo characterization of Breg cells in patients with chronic Chagas disease

Despite the growing importance of the regulatory function of B cells in many infectious diseases, their immunosuppressive role remains elusive in chronic Chagas disease (CCD). Here, we studied the proportion of different B cell subsets and their capacity to secrete IL-10 ex vivo in peripheral blood from patients with or without CCD cardiomyopathy. First, we immunophenotyped peripheral blood mononuclear cells from patients according to the expression of markers CD19, CD24, CD38 and CD27 and we showed an expansion of total B cell and transitional CD24^highCD38^high B cell subsets in CCD patients with cardiac involvement compared to non-infected donors. Although no differences were observed in the frequency of total IL-10 producing B cells (B10) among the groups, CCD patients with cardiac involvement showed an increased proportion of naïve B10 cells and a tendency to a higher frequency of transitional B10 cells compared to non-infected donors. Our research demonstrates that transitional B cells are greatly expanded in patients with the cardiac form of CCD and these cells retain the ability to secrete IL-10. These findings provide insight into the phenotypic distribution of regulatory B cells in CCD, an important step towards new strategies to prevent cardiomyopathy associated with T. cruzi infection.

TNFR2 expression is a hallmark of human memory B cells with suppressive function

Tumor Necrosis Factor Receptor 2 (TNFR2) expression is increasingly being linked to tolerogenic immune reactions and cells with suppressor function including a subset of T-regulatory cells. B-regulatory cells play an important role in control of T-cell responses and inflammation. Recently, we described TNFR2 as a marker for IL-10-producing B cells, a hallmark of this cell subset. Here, we demonstrate that proliferation of T cells is reduced in the presence of TNFR2 positive human memory B cells generated with TLR9 ligand, while TNFR2- and TNFR2+CD27- B cells display costimulatory activity. Our data further reveal that IL-10 secretion is characteristic of IgM+ naïve and memory B cells but suppressive activity is not restricted to IL-10: (i) the inhibitory effect of TNFR2+ switched memory B cells was comparable to that exerted by TNFR2+ IgM+ memory B cells although IL-10 secretion levels in the cocultures were lower; (ii) supernatants from TNFR2+ memory B cells failed to suppress T-cell proliferation. Based on our findings, we propose that formation of Breg is a specific characteristic of human memory B cells undergoing terminal differentiation. Our data further corroborate that TNFR2 represents a viable marker for identification of memory B cells with regulatory function.

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.

Clinical and biological activity of rituximab in the treatment of pemphigus

B-cells are major effector cells in autoimmunity since they differentiate into plasmocytes that produce pathogenic auto-antibody such as anti-desmoglein antibodies in pemphigus patients. Major advances were obtained using whole B-cell depleting therapies including anti-CD20 antibodies in refractory pemphigus patients that lead to rituximab approval in pemphigus patients in EU and USA. This review summarizes the data supporting the efficacy of rituximab in pemphigus and provides an overview of the reported immunological changes underlying its therapeutic action. Short and long-term remission in pemphigus is explained by the removal of autoreactive B-cells involved in the production of pathogenic IgG auto-antibodies and by enhancement of the appearance of regulatory B-cells that could maintain long term immune tolerance.

The Multiple Functions of B Cells in Chronic HBV Infection

Chronic hepatitis B virus (HBV) infection is one of the main causes of liver diseases, of which the natural history and clinical outcomes are associated with the role of B cells. As humoral immune cells, B cells play a critical role in the process of anti-HBV antibody production. In addition, some studies have also characterized other B cell subsets involved in antigen presentation and regulating the immune response beyond antibody secretion. However, not all B cell subsets play a positive role in the immune response to chronic HBV infection, and various B cell subsets jointly mediate persistent HBV infection, tolerance, and liver damage. Thus, we further sought to elucidate the multiple functions of B cells to gain novel insight into the understanding of chronic hepatitis B (CHB) pathogenesis. We also reviewed the current immunotherapies targeting B cells to explore novel therapeutic interventions for the treatment of chronic HBV infection.

Impact of deranged B cell subsets distribution in the development of HCV-related cirrhosis and HCC in type two diabetes mellitus

Type II diabetes (T2D) may worsen the course of hepatitis C virus infection with a greater risk of liver cirrhosis (LC) and hepatocellular carcinoma (HCC). In chronic viral infections, the deranged B cell subset signifies uncontrolled disease. The study aimed to verify the relation between B cell subsets' distribution and liver disease progression in chronic hepatitis C (CHC) patients with T2D. A total of 67 CHC patients were divided into two groups; 33 non-diabetic and 34 with T2D. Each group was subdivided into CHC-without LC or HCC (N-CHC), CHC-with LC (CHC-LC), and CHC-with HCC (CHC-HCC). Twenty-seven healthy individuals also participated as controls. Flow cytometry was used to analyze CD19+ B cell subsets based on the expression of CD24 and CD38. CD19+CD24hiCD38hi Immature/transitional B cells elevated in diabetic than non-diabetic patients. In diabetic patients, while CD19+CD24+CD38- primarily memory B cells were higher in CHC-N and CHC-HCC groups than LC with a good predictive accuracy of LC, the opposite was observed for CD19+CD24-CD38- new memory B cells. Only in diabetic patients, the CD19+CD24intCD38int naïve mature B cells were high in CHC-HCC patients with good prognostic accuracy of HCC. Merely in diabetic patients, several correlations were observed between B cell subsets and liver function. Immature/transitional B cells increase remarkably in diabetic CHCpatients and might have a role in liver disease progression. Memory and Naïve B cells are good potential predictors of LC and HCCin diabetic CHCpatients, respectively. Further studies are needed to investigate the role of the CD19+CD24-CD38- new memory B cells in disease progression in CHC patients.

Innate B Cells: the Archetype of Protective Immune Cells

The innate B cell (IBC) population is heterogeneous and involved in the primary immune response. IBC functions include a high ability to produce natural antibodies with IgM isotype, the elimination of apoptotic cells, and a capacity to be cognate help to T cells. Among IBC subsets, B-1 cells and marginal zone B cells are the main producers of IgM, act as rapid immune responders that may relocate to follicular lymphoid and differentiate to cytokine and antibody-secreting cells shortly after infection. IBCs functions are highly dependent on their localization site and the nature of their B cell receptor repertoire, suggesting a high plasticity range of different immune responses. In this review, we will describe the nature and functions of the different innate-like B cell subsets, first in mice and then in humans. Besides this, we will emphasize the strong ability of these cells to undertake different protective functions from the first line of defense against pathogens to the regulatory role of the broader immune response.

Defective CD19+CD24hiCD38hi transitional B-cell function in patients with relapsing-remitting MS

Background:

Multiple sclerosis (MS) is characterized by central nervous system (CNS) infiltration of T and B cells, excess inflammatory cytokine and chemokine production and failure of immune regulation. CD19+CD24hiCD38hi transitional B cells producing interleukin (IL)-10 have been shown to suppress interferon-γ (IFNγ) and tumour necrosis factor-α (TNFα) production by CD4+ T cells and to be dysfunctional in autoimmune arthritis and systemic lupus erythematosus.

Objective:

We hypothesized that transitional B-cell-dependent immune regulation could be defective in MS and examined their function in healthy subjects and patients with relapsing-remitting multiple sclerosis (RRMS).

Methods:

A total of 62 healthy donors and 21 RRMS subjects donated peripheral blood for the study. IL-10-producing B cells, IFNγ and TNFα-producing T cells and proliferating T cells were quantified by flow cytometry.

Results:

In healthy individuals, CD19+CD24hiCD38hi transitional B cells produce more IL-10 than CD19+CD24+CD38+ naive and CD19+CD24hiCD38− memory B cells and are able to suppress CD4+ T-cell proliferation and IFNγ and TNFα-production. In subjects with RRMS, CD19+CD24hiCD38hi transitional B cells produce significantly less IL-10 and to fail to suppress effector T-cell function.

Conclusion:

CD19+CD24hiCD38hi transitional B cells physiologically represent the most potent regulatory B-cell subset and are functionally defective in patients with RRMS, an abnormality that may contribute to the immune pathological process.

Emerging roles of Toll-like receptor 9 in cardiometabolic disorders

Growing evidence suggests that damage-associated molecule patterns (DAMPs) and their receptors, pattern recognition receptors (PRRs), are associated with the progression of cardiometabolic disorders, including obesity-related insulin resistance and atherosclerosis. Cardiometabolic disorders share sterile chronic inflammation as a major cause; however, the exact mechanisms are still obscure. Toll-like receptor 9 (TLR9), one of the nucleic acid-sensing TLRs, recognizes DNA fragments derived from pathogens and contributes to self-defense by activation of the innate immune system. In addition, previous studies demonstrated that TLR9 recognizes DNA fragments released from host cells, accelerating sterile inflammation, which is associated with inflammatory diseases such as autoimmune diseases. In obese adipose tissue and atherosclerotic vascular tissue, various stresses release DNA fragments and/or nuclear proteins as DAMPs from degenerated adipocytes and vascular cells. Recent studies indicated that the activation of TLR9 in immune cells including macrophages and dendritic cells by recognition of these DAMPs promotes inflammation in these tissues, which causes cardiometabolic disorders. This review discusses recent advances in understanding the role of sterile inflammation associated with TLR9 and its endogenous ligands in cardiometabolic disorders. New insights into innate immunity may provide better understanding of cardiometabolic disorders and new therapeutic options for these major health threats in recent decades.

The immunoregulatory and neuroprotective effects of human adipose derived stem cells overexpressing IL-11 and IL-13 in the experimental autoimmune encephalomyelitis mice

Multiple sclerosis (MS) is an inflammatory demyelination disease in the central nervous system (CNS) characterized by incomplete endogenous remyelination in the chronic phase. A shift of the balance between pro and anti-inflammatory cytokines is one of the important markers in the pathogenesis of MS. This study aimed to evaluate the effects of human adipose derived stem cells (hADSCs) overexpressing interleukin 11 and interleukin 13 (IL-11, 13-hADSCs) on the experimental autoimmune encephalomyelitis (EAE), an animal model of MS.12 days after immunization of C57Bl/6 female mice with MOG35-55 and initial clinical symptoms appearance, the IL-11, 13-hADSCs were injected via the tail vein into the EAE mice. Then, the mice were sacrificed at 30 days post-immunization (DPI) and the spinal cords of experimental groups were extracted for histopathological and real-time RT-PCR studies.The results indicated that the clinical scores and mononuclear cells infiltration into the spinal cords of EAE mice were significantly reduced in mice treated with IL-11, 13-hADSCs. Likewise, the remyelination and oligodendrogenesis were significantly enhanced in the mentioned treatment group. Real-time results demonstrated that pro/anti-inflammatory cytokine genes expression was reversed in IL-11, 13-hADSCs treatment group in comparison to the untreated EAE group.Expression of IL-11 as a neurotrophic cytokine and IL-13 as an anti-inflammatory cytokine by hADSCs could increase the immunomodulatory and neuroprotective effects of hADSCs and be a powerful candidate in stem cell therapy for future treatment of MS.

Characterization of CD19+ CD24hi CD38hi B cells in Chinese adult patients with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease. Human interleukin-10⁺ B cells (B10 cells) is one of regulatory B cells and is enriched in CD19⁺ CD24^hi CD38^hi B cells. A little is known about these cells in atopic dermatitis.

OBJECTIVE

To study CD19⁺ CD24^hi CD38^hi B cells and their clinical significance in Chinese adult patients with atopic dermatitis.

METHODS

Thirty-two adult patients with AD and nineteen healthy controls were enrolled. Peripheral blood mononuclear cells (PBMCs) were isolated and stained with fluorescein-conjugated monoclonal antibodies for CD19, CD24, CD27, CD38 and Annexin V. The stained PBMCs were analysed by flow cytometry. B10 cells were prepared by stimulating PBMCs with CpG, LPS and CD40L followed by restimulation with phorbol12-myristate 13-acetate (PMA) and ionomycin. Serum IL-10, B-cell-activating factor (BAFF) and a proliferation-inducing ligand (APRIL) levels were measured by using the ELISA. Apoptosis and proliferation of CD19⁺ CD24^hi CD38^hi B cells were measured by flow cytometry. 4/P-signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase 1/2 (Erk) phosphorylation were also studied.

RESULTS

The number of CD19⁺ CD24^hi CD38^hi B cells in patients with AD was similar to that in healthy controls. However, B10 cells were decreased in patients with AD. The proportion of B10 cells was negatively associated with blood basophil counts but not associated with disease activity. CD19⁺ CD24^hi CD38^hi B cells from AD patients were more susceptible to apoptosis upon stimulation with CpG, LPS and CD40L. B cells from AD patients showed lower STAT3 and Erk phosphorylation.

CONCLUSIONS

CD19⁺ CD24^hi CD38^hi B cells were unchanged in atopic dermatitis while B10 cells were decreased. The increased B-cell apoptosis, decreased STAT3 and Erk phosphorylation might contribute to these changes.

The Role of Toll-like Receptors in Atherothrombotic Cardiovascular Disease

Toll-like receptors (TLRs) are dominant components of the innate immune system. Activated by both pathogen-associated molecular patterns and damage-associated molecular patterns, TLRs underpin the pathology of numerous inflammation related diseases that include not only immune diseases, but also cardiovascular disease (CVD), diabetes, obesity, and cancers. Growing evidence has demonstrated that TLRs are involved in multiple cardiovascular pathophysiologies, such as atherosclerosis and hypertension. Specifically, a trial called the Canakinumab Anti-inflammatory Thrombosis Outcomes Study showed the use of an antibody that neutralizes interleukin-1β, reduces the recurrence of cardiovascular events, demonstrating inflammation as a therapeutic target and also the research value of targeting the TLR system in CVD. In this review, we provide an update of the interplay between TLR signaling, inflammatory mediators, and atherothrombosis, with an aim to identify new therapeutic targets for atherothrombotic CVD.

Molecular Aspects and Future Perspectives of Cytokine-Based Anti-cancer Immunotherapy

Cytokine-based immunotherapy is a promising field in the cancer treatment, since cytokines, as proteins of the immune system, are able to modulate the host immune response toward cancer cell, as well as directly induce tumor cell death. Since a low dose monotherapy with some cytokines has no significant therapeutic results and a high dose treatment leads to a number of side effects caused by the pleiotropic effect of cytokines, the problem of understanding the influence of cytokines on the immune cells involved in the pro- and anti-tumor immune response remains a pressing one. Immune system cells carry CD makers on their surface which can be used to identify various populations of cells of the immune system that play different roles in pro- and anti-tumor immune responses. This review discusses the functions and specific CD markers of various immune cell populations which are reported to participate in the regulation of the immune response against the tumor. The results of research studies and clinical trials investigating the effect of cytokine therapy on the regulation of immune cell populations and their surface markers are also discussed. Current trends in the development of cancer immunotherapy, as well as the role of cytokines in combination with other therapeutic agents, are also discussed.

Effect of immune regulatory pathways after immunization with GMZ2 malaria vaccine candidate in healthy lifelong malaria-exposed adults

BACKGROUND

Despite appreciable immunogenicity in malaria-naive populations, many candidate malaria vaccines are considerably less immunogenic in malaria-exposed populations. This could reflect induction of immune regulatory mechanisms involving Human Leukocyte Antigen G (HLA-G), regulatory T (Treg), and regulatory B (Breg) cells. Here, we addressed the question whether there is correlation between these immune regulatory pathways and both plasmablast frequencies and vaccine-specific IgG concentrations.

METHODS

Fifty Gabonese adults with lifelong exposure to Plasmodium spp were randomized to receive three doses of either 30 µg or 100 µg GMZ2-CAF01, or 100 µg GMZ2-alum, or control vaccine (rabies vaccine) at 4-week intervals. Only plasma and peripheral blood mononuclear cells isolated from blood samples collected before (D0) and 28 days after the third vaccination (D84) of 35 participants were used to measure sHLA-G levels and anti-GMZ2 IgG concentrations, and to quantify Treg, Breg and plasmablast cells. Vaccine efficacy was assessed using controlled human malaria infection (CHMI) by direct venous inoculation of Plasmodium falciparum sporozoites (PfSPZ Challenge).

RESULTS

The sHLA-G concentration increased from D0 to D84 in all GMZ2 vaccinated participants and in the control group, whereas Treg frequencies increased only in those receiving 30 µg or 100 µg GMZ2-CAF01. The sHLA-G level on D84 was associated with a decrease of the anti-GMZ2 IgG concentration, whereas Treg frequencies on D0 or on D84, and Breg frequency on D84 were associated with lower plasmablast frequencies. Importantly, having a D84:D0 ratio of sHLA-G above the median was associated with an increased risk of P. falciparum infection after sporozoites injection.

CONCLUSION

Regulatory immune responses are induced following immunization. Stronger sHLA-G and Treg immune responses may suppress vaccine induced immune responses, and the magnitude of the sHLA-G response increased the risk of Plasmodium falciparum infection after CHMI. These findings could have implications for the design and testing of malaria vaccine candidates in semi-immune individuals.

The Traditional Chinese Medicine Fufang Shatai Heji (STHJ) Enhances Immune Function in Cyclophosphamide-Treated Mice

Fufang Shatai Heji (STHJ) is a mixture of traditional Chinese medicines, such as Radix Adenophorae, Radix Pseudostellariae, and Radix Astragali. STHJ is commonly used to treat diseases caused by low immune function, for example, Sjögren's syndrome (SS). The primary objective of this study was to assess the immunopotentiating effect of STHJ using an immunosuppressive mouse model receiving cyclophosphamide (CTX). Following CTX treatment, STHJ was administered by oral gavage for 30 consecutive days. The percentage of specific lymphocyte subpopulations in the spleen was measured by flow cytometry. Levels of inflammatory factors in serum were detected by enzyme-linked immunosorbent assays (ELISAs). The administration of STHJ significantly elevated thymus and spleen indices, increased B cell and natural killer (NK) cell activities, and decreased CD8⁺ T, CD8⁺CD122⁺ T, NKT, and γδT cell activities in the CTX-treated mice. In addition, STHJ upregulated the expression of interleukin- (IL-) 2, IL-6, and tumor necrosis factor-α (TNF-α) and downregulated IL-10 expression in CTX-treated mice. In conclusion, STHJ effectively remitted CTX-induced immunosuppression by modulating the balance of lymphocyte subsets and cytokines. Our results suggest STHJ treatment could be used as an effective therapeutic approach to improve immune function in patients with low immunity.

Abnormal B-Cell Subset and Blimp-1-Mediated Humoral Responses Associated With Visceral Leishmaniasis Pathogenesis

B-cells have a spectrum of functions ranging from antibody production to antigen presentation and have additional vital roles in immune mechanisms. There is rudimentary knowledge about the role of B-cells in intracellular infections with contradictory findings. We explored the role of B-cell dysfunctions in visceral leishmaniasis (VL) pathogenesis in terms of the phenotypic and functional properties of B-cells during the course of disease. This study was performed on blood and splenic aspirates (SA) of VL cases pre- and post-treatment. Whole blood was used for flow cytometric studies for determining the profiles of B-cells at different time-points of treatment. Peripheral blood mononuclear cells were used for magnetic purification of B-cells, for transcriptional studies by real-time polymerase chain reaction (RT-PCR). Serum/plasma was used for direct agglutination test for determining parasite-specific antibodies and SA were used for scoring the presence of parasite by microscopic examination. Flow cytometric studies depicted decreased B-cell percentages during the entire course of disease and attainment of exhaustive phenotype with tissue-like memory cell markers, indicative of B-cell dysfunctions in VL. In addition, B-cells had compromised abilities of antigen processing and presentation and altered levels of B-lymphocyte-induced maturation protein-1 (Blimp-1). Blimp-1 expression goes hand in hand with B-cell maturation antigen and transmembrane activator and calcium modulator (TACI) and cyclophilin ligand interactor, suggestive of its role in promoting plasma cell survival and antibody production. Elevated level of VL-specific antibody titre was directly correlated with exhausted phenotype and also with disease severity during VL. This study indicated for impaired B-cell functions during chronic infection which may lead to pathological consequences in human VL.

Regulatory B Cells

B cells are typically characterized by their ability to produce antibodies, function as secondary antigen-present cells, and produce various immunoregulatory cytokines. The regulatory B (Breg)-cell population is now widely accepted as an important modulatory component of the immune system that suppresses inflammation. Recent studies indicate that Breg-cell populations are small under physiological conditions but expand substantially in both human patients and murine models of chronic inflammatory diseases, autoimmune diseases, infection, transplantation, and cancer. Almost all B-cell subsets can be induced to form Breg cells. In addition, there are unique Breg-cell subsets such as B10 and Tim-1⁺ B cells. Immunoregulatory function may be mediated by production of cytokines such as IL-10 and TGF-β and ensuing suppression of T cells, by direct cell-cell interactions, and (or) by altering the immune microenvironment. In this chapter, we describe in detail the discovery of Breg cells, their phenotypes, differentiation, function, contributions to disease, and therapeutic potential.

Toll-like Receptors as a Potential Drug Target for Diabetes Mellitus and Diabetes-associated Complications

Diabetes mellitus (DM) is a chronic endocrine disease distinguished by hyperglycemia due to disturbance in carbohydrate or lipid metabolism or insulin function. To date, diabetes, and its complications, is established as a global cause of morbidity and mortality. The intended aim during the management of diabetes is to maintain blood glucose close to normal because the majority of patients have poor control of their elevated blood glucose and are highly prone to severe macrovascular and microvascular complications. To decrease the burden of the disease and its complications, scientists from various disciplines are working intensively to identify novel and promising drug targets for diabetes and its complications. Increased and ongoing investigations on mechanisms relating to diabetes and associated complications could potentially consider inflammatory cascades as a promising component of the strategy in the prevention and control of diabetes and its complications. The potential of targeting mediators of inflammation like toll-like receptors (TLRs) are part of current investigation by the scientific community. Hence, the aim of the present review is to discuss the role of TLRs as a potential drug target for diabetes and diabetes associated complications.

Circulating exosomes from esophageal squamous cell carcinoma mediate the generation of B10 and PD-1high Breg cells

As one of the most frequently diagnosed cancers, esophageal squamous cell carcinoma (ESCC) remains the leading cause of malignancy‐related death worldwide. Many studies have focused on the potential role of cancer cells in educating B cells during cancer progression. Here, we aim to explore the role of circulating exosomes from ESCC in the generation of two main regulatory B (Breg) subsets, including interleukin‐10⁺ Bregs (B10) and programmed cell death (PD)‐1^high Bregs. Firstly, we observed an elevated percentage of B10 cells in peripheral blood of ESCC patients compared with healthy controls. Then we isolated and characterized exosomes from the peripheral blood of ESCC patients and an ESCC cell line. Exosomes from ESCC patients and the ESCC cell line suppressed the proliferation of B cells and induced the augmentation of B10 and PD‐1^high Breg cells. By comparing the long non‐coding RNA and mRNA expression profiles in exosomes from ESCC patients or healthy controls, we identified a series of differentially expressed genes. Finally, we undertook gene annotation and pathway enrichment analyses on differentially expressed genes to explore the potential mechanism underlying the modulatory role of cancer exosomes in B cells. Our findings contribute to the study on B cell‐mediated ESCC immunosuppression and shed light on the possible application of exosomes in anticancer therapies.

Phenotypic and functional alterations of regulatory B cell subsets in adult allergic asthma patients

BACKGROUND

IL-10-producing regulatory B cells (Bregs) are widely ascribed immune regulatory functions. However, Breg subsets in human asthma have not been fully investigated.

OBJECTIVE

We studied Breg subsets in adult allergic asthma patients by assessing two major parameters, frequency and IL-10 expression. We then investigated factors that affect these two parameters in patients.

METHODS

Peripheral blood mononuclear cells (PBMCs) of adult allergic asthma patients (N = 26) and non-asthmatic controls (N = 28) were used to assess the frequency of five subsets of transitional B cells (TBs), three subsets of CD24^high CD27⁺ B cells and B1 cells. In addition to clinical data, IL-10 expression by individual Breg subsets was assessed by flow cytometry.

RESULTS

Asthma patients had decreases of CD5⁺ and CD1d⁺ CD5⁺ , but an increase of CD27⁺ TBs which was significant in patients with moderate asthma (60 < FEV1 < 80). Regardless of asthma severity, there was no significant alteration in the frequencies of 6 other Breg subsets tested. However, we found that oral corticosteroid (OCS) significantly affected the frequency of Bregs in Breg subset-specific manners. OCS decreased CD5⁺ and CD1d⁺ CD5⁺ TBs, but increased CD27⁺ TBs and CD10⁺ CD24^high CD27⁺ cells. Furthermore, OCS decreased IL-10 expression by CD27⁺ TBs, all 3 CD24^high CD27⁺ B cell subsets (CD5⁺ , CD10⁺ and CD1d⁺ ) and B1 cells. OCS-mediated inhibition of IL-10 expression was not observed in the other Breg subsets tested.

CONCLUSION & CLINICAL RELEVANCE

Alterations in the frequency of Bregs and their ability to express IL-10 are Breg subset-specific. OCS treatment significantly affects the frequency as well as their ability to express IL-10 in Breg subset-specific manners.

Neuregulin-1/ErbB network: An emerging modulator of nervous system injury and repair

Neuregulin-1 (Nrg-1) is a member of the Neuregulin family of growth factors with essential roles in the developing and adult nervous system. Six different types of Nrg-1 (Nrg-1 type I-VI) and over 30 isoforms have been discovered; however, their specific roles are not fully determined. Nrg-1 signals through a complex network of protein-tyrosine kinase receptors, ErbB2, ErbB3, ErbB4 and multiple intracellular pathways. Genetic and pharmacological studies of Nrg-1 and ErbB receptors have identified a critical role for Nrg-1/ErbB network in neurodevelopment including neuronal migration, neural differentiation, myelination as well as formation of synapses and neuromuscular junctions. Nrg-1 signaling is best known for its characterized role in development and repair of the peripheral nervous system (PNS) due to its essential role in Schwann cell development, survival and myelination. However, our knowledge of the impact of Nrg-1/ErbB on the central nervous system (CNS) has emerged in recent years. Ongoing efforts have uncovered a multi-faceted role for Nrg-1 in regulating CNS injury and repair processes. In this review, we provide a timely overview of the most recent updates on Nrg-1 signaling and its role in nervous system injury and diseases. We will specifically highlight the emerging role of Nrg-1 in modulating the glial and immune responses and its capacity to foster neuroprotection and remyelination in CNS injury. Nrg-1/ErbB network is a key regulatory pathway in the developing nervous system; therefore, unraveling its role in neuropathology and repair can aid in development of new therapeutic approaches for nervous system injuries and associated disorders.

Decreased number of CD19+CD24hiCD38hi regulatory B cells in Diabetic nephropathy

BACKGROUND

Regulatory B cells participate in the pathogenesis of autoimmune disease. This study aimed to examine the putative contribution of regulatory B cells to the pathogenesis of DN. The number of circulating CD19⁺CD24^hiCD38^hi B cells, CD19⁺CD24^hiCD38^hiCD5⁺ B cells, and CD19⁺CD24^hiCD38^hiIL-10⁺ B cells were significantly lower in DN patients (p < 0.05) than the control group. The number of circulating CD19⁺CD24^hiCD38^hi B cells was positively correlated with the levels of eGFR and serum IL-10 levels, but negatively correlated with urinary protein levels in DN patients. Treatment significantly increased the number of CD19⁺CD24^hiCD38^hi B cells, CD19⁺CD24^hiCD38^hiCD5⁺ B cells, CD19⁺CD24^hiCD38^hiIL-10⁺ B cells, and the levels of serum IL-10 (p < 0.05). We conclude that regulatory B cells may present new targets for intervention of DN.

Regulatory B cells and advances in transplantation

The effects of B cell subsets with regulatory activity on the immune response to an allograft have evoked increasing interest. Here, we summarize the function and signaling of regulatory B cells (Bregs) and their potential effects on transplantation. These cells are able to suppress the immune system directly via ligand-receptor interactions and indirectly by secretion of immunosuppressive cytokines, particularly IL-10. In experimental animal models, the extensively studied IL-10-producing B cells have shown unique therapeutic advantages in the transplant field. In addition, adoptive transfer of B cell subsets with regulatory activity may reveal a new approach to prolonging allograft survival. Recent clinical observations on currently available therapies targeting B cells have revealed that Bregs play an important role in immune tolerance and that these cells are expected to become a new target of immunotherapy for transplant-related diseases.

Unstimulated Adult Human B Cells Include an IL-10+ Population with Suppressive Properties and an Activated Phenotype

B cells with regulatory properties have been recently identified and described in different immune disorders, including autoimmunity, infection, cancer, and allergy. in vitro studies of regulatory B cells are usually performed following prolonged cell culture and stimulation in order to obtain B cells capable of IL-10 secretion. We describe the isolation of viable IL-10-positive B cells directly from ex vivo unstimulated samples using the IL-10 secretion assay from Miltenyi Biotec, which was originally designed for IL-10-positive T cell analysis and isolation. IL-10-positive B cells from unstimulated samples represented approximately 2% of all B cells in healthy individuals, suppressed T cell proliferation and were enriched for surface markers of B cell activation. This tool has a potential to boost functional studies of IL-10-secreting B cells in health and disease. © 2018 International Society for Advancement of Cytometry.

Frequency of IL-10-producing regulatory B cells associated with disease activity in thyroid-associated orbitopathy

AIM

To investigate the association between IL-10-producing regulatory B (B10) cells and the clinical features of thyroid-associated orbitopathy (TAO).

METHODS

A total of 30 patients with TAO were recruited at Zhongshan Ophthalmic Center from May 2015 to December 2015. Peripheral blood mononuclear cells (PBMCs) were separated from blood samples of 30 TAO patients and 16 healthy controls and stimulated with CD40 ligand and CpG for 48h. The frequency of IL-10⁺ B cells was examined by flow cytometry and the correlation between the frequency of IL-10⁺ B cells and clinical features of TAO was analyzed by SPSS.

RESULTS

The frequency of IL-10⁺ B cells among CD19⁺ B cells in TAO patients was significantly lower than in healthy controls (TAO: 4.66%±1.88% vs healthy control: 6.82%±2.40%, P<0.01). The frequency of IL-10⁺ B cells showed a positive correlation with disease activity of TAO measured by Clinical Activity Score (CAS) (r=0.50, P<0.01), and became higher in TAO patients with family history of Graves' disease (GD) (P=0.04).

CONCLUSION

The decrease of the frequency of IL-10⁺ B cells in TAO patients indicates the deficiency of B10 cells in TAO, and the positive association with disease activity suggests its important role in TAO inflammation regulation.