B10 cells induced by Schistosoma japonicum soluble egg antigens modulated regulatory T cells and cytokine production of T cells

Deficiency in TLR4 impairs regulatory B cells production induced by Schistosome soluble egg antigen

Regulatory B cells (Bregs) producing IL-10 have negative regulatory function. Several studies have shown the important roles for Toll-like receptor 2 (TLR2), TLR4, and TLR9 ligation in the development of Bregs. We have reported that Schistosome soluble egg antigen (SEA) induced the production of Bregs. However, it remains unclear whether such activation is via the TLR pathway. The present study showed that IL-10 and TLR4 mRNA expression in spleen B cells of significantly increased in C57BL/10 J mice spleen B cells following SEA stimulation. The level of secreted IL-10 and IL-10⁺ B cell proportion decreased in spleen B cells derived from TLR4-deficient C57BL/10ScNJ (TLR4^-/^-) mice following SEA or LPS stimulation compared with C57BL/10 J mice. The CD1d^hiCD5⁺ B cells proportion decreased in spleen B cells of TLR4^-/^- mice following SEA stimulation compared with control mice. NF-κB, ERK, p38MAPK and JNK signal transduction inhibitors significantly suppressed IL-10 secretion in CD1d^hiCD5⁺ B cells induced by SEA or LPS. The phosphorylation levels of IκBα, p65, ERK, JNK and p38 were increased in CD1d^hiCD5⁺ B cell of C57BL/10 J mice treated with LPS or SEA. In conclusion, this study suggests that TLR4 plays a critical role in Bregs activation induced by SEA. And the TLR4-triggered NF-κB and MAPK pathways activation in CD1d^hiCD5⁺ B cells stimulated with SEA. The findings elucidated the mechanism of SEA induction of CD1d^hiCD5⁺ B cells and helped us to understand the immune regulation during Schistosoma japonicum infection.

Inhibition of COX-2 ameliorates murine liver schistosomiasis japonica through splenic cellular immunoregulation

Background

We have reported the positive association of the cyclooxygenase 2 (COX-2)/prostaglandin E2 (PGE2) axis with liver fibrosis induced by Schistosoma japonicum (Sj) infection, and TLR4 signaling controlled this axis. However, how COX-2 regulates immune response during Sj infection is still unclear.

Methods

Hematoxylin and eosin staining was used to evaluate the effect of the COX-2-specific inhibitor NS398 on liver granulomatous inflammation and fibrosis. Flow cytometry was used to explore the frequency and amount of different immune cell infiltration in the spleen during Sj infection.

Results

NS398 significantly reduced the size of liver granuloma, spleen, and mesenteric lymph node (MLN) and alleviated chronic granulomatous inflammation. Mechanically, this might be by decreasing the number of Sj-induced macrophages and T helper type 1 (Th1), Th2, T follicular helper (Tfh), T follicular regulatory (Tfr), and germinal center B (GC B) cells. There were no differences in the number of neutrophils, myeloid-derived suppressor cells, Th17 cells, regulatory T cells (Treg), or total B cells in the spleen of the mice with or without NS398 treatment.

Conclusions

COX-2/PGE2 inhibition may represent a potential therapeutic approach for schistosomiasis japonica through splenic cellular immunoregulation.

Graphical Abstract

TLR7 modulating B-cell immune responses in the spleen of C57BL/6 mice infected with Schistosoma japonicum

B cells played an important role in Schistosoma infection-induced diseases. TLR7 is an intracellular member of the innate immune receptor. The role of TLR7 on B cells mediated immune response is still unclear. Here, C57BL/6 mice were percutaneously infected by S. japonicum for 5-6 weeks. The percentages and numbers of B cells increased in the infected mice (p < 0.05), and many activation and function associated molecules were also changed on B cells. More splenic cells of the infected mice expressed TLR7, and B cells were served as the main cell population. Moreover, a lower level of soluble egg antigen (SEA) specific antibody and less activation associated molecules were found on the surface of splenic B cells from S. japonicum infected TLR7 gene knockout (TLR7 KO) mice compared to infected wild type (WT) mice (p < 0.05). Additionally, SEA showed a little higher ability in inducing the activation of B cells from naive WT mice than TLR7 KO mice (p < 0.05). Finally, the effects of TLR7 on B cells are dependent on the activation of NF-κB p65. Altogether, TLR7 was found modulating the splenic B cell responses in S. japonicum infected C57BL/6 mice.

Regulatory B cells improve ventricular remodeling after myocardial infarction by modulating monocyte migration

Overactivated inflammatory responses contribute to adverse ventricular remodeling after myocardial infarction (MI). Regulatory B cells (Bregs) are a newly discovered subset of B cells with immunomodulatory roles in many immune and inflammation-related diseases. Our study aims to determine whether the expansion of Bregs exerts a beneficial effect on ventricular remodeling and explore the mechanisms involved. Here, we showed that adoptive transfer of Bregs ameliorated ventricular remodeling in a murine MI model, as demonstrated by improved cardiac function, decreased scar size and attenuated interstitial fibrosis without changing the survival rate. Reduced Ly6C^hi monocyte infiltration was found in the hearts of the Breg-transferred mice, while the infiltration of Ly6C^lo monocytes was not affected. In addition, the replenishment of Bregs had no effect on the myocardial accumulation of T cells or neutrophils. Mechanistically, Bregs reduced the expression of C-C motif chemokine receptor 2 (CCR2) in monocytes, which inhibited proinflammatory monocyte recruitment to the heart from the peripheral blood and mobilization from the bone marrow. Breg-mediated protection against MI was abrogated by treatment with an interleukin 10 (IL-10) antibody. Finally, IL-10 neutralization reversed the effect of Bregs on monocyte migration and CCR2 expression. The present study suggests a therapeutic value of Bregs in limiting ventricular remodeling after MI through decreasing CCR2-mediated monocyte recruitment and mobilization.

Context-dependent roles of B cells during intestinal helminth infection

The current approaches to reduce the burden of chronic helminth infections in endemic areas are adequate sanitation and periodic administration of deworming drugs. Yet, resistance against some deworming drugs and reinfection can still rapidly occur even after treatment. A vaccine against helminths would be an effective solution at preventing reinfection. However, vaccines against helminth parasites have yet to be successfully developed. While T helper cells and innate lymphoid cells have been established as important components of the protective type 2 response, the roles of B cells and antibodies remain the most controversial. Here, we review the roles of B cells during intestinal helminth infection. We discuss the potential factors that contribute to the context-specific roles for B cells in protection against diverse intestinal helminth parasite species, using evidence from well-defined murine model systems. Understanding the precise roles of B cells during resistance and susceptibility to helminth infection may offer a new perspective of type 2 protective immunity.

New insights into regulatory B cells biology in viral, bacterial, and parasitic infections

B lymphocytes are primarily well known for their contribution to immunity by antibody production, antigen presentation and, the production of cytokines. In recent years several studies demonstrated the existence of B cells with regulatory functions, which have been termed regulatory B cells (B_regs), similar to regulatory T cells (T_regs). B_regs are a subpopulation of B cells that have immunosuppressive effects via the production of regulatory cytokines including interleukin-10 (IL-10), transforming growth factor-β (TGF-β), and IL-35. B_regs limit host defense against various pathogens. In addition, B_regs contribute to increased levels of regulatory cytokines and leads to an induction of suppressive T_regs, which exert broader suppressive functions against various pathogens. The high percentage of B_regs is positively associated with viral and bacterial load and can contribute to poor vaccine responses. B_regs can also facilitate pathogen survival at an early stage of infection, and subsequently cause increased severity of disease by inhibiting pro-inflammatory cytokine production, macrophage activation, and inflammatory T cells activation such as Th1, Th17, and Th22. Also, B_regs afford protection against the hyper-inflammatory response in parasitic infections. Here we review the central role of B_regs in many major bacterial and viral human infections, and provide an overview of the immunoregulatory mechanisms used by B_regs.

Endothelin receptors promote schistosomiasis-induced hepatic fibrosis via splenic B cells

Endothelin receptors (ETRs) are activated by vasoactive peptide endothelins and involved in the pathogenesis of hepatic fibrosis. However, less is known about the role of ETRs in Schistosoma (S.) japonicum-induced hepatic fibrosis. Here, we show that the expression of ETRs is markedly enhanced in the liver and spleen tissues of patients with schistosome-induced fibrosis, as well as in murine models. Additional analyses have indicated that the expression levels of ETRs in schistosomiasis patients are highly correlated with the portal vein and spleen thickness diameter, both of which represent the severity of fibrosis. Splenomegaly is a characteristic symptom of schistosome infection, and splenic abnormality may promote the progression of hepatic fibrosis. We further demonstrate that elevated levels of ETRs are predominantly expressed on splenic B cells in spleen tissues during infection. Importantly, using a well-studied model of human schistosomiasis, we demonstrate that endothelin receptor antagonists can partially reverse schistosome-induced hepatic fibrosis by suppressing the activation of splenic B cells characterized by interleukin-10 (IL-10) secretion and regulatory T (Treg) cell-inducing capacity. Our study provides insights into the mechanisms by which ETRs regulate schistosomiasis hepatic fibrosis and highlights the potential of endothelin receptor antagonist as a therapeutic intervention for fibrotic diseases.

Schistosomiasis is a serious but neglected tropical infectious disease. which can lead to hepatic fibrosis and death. To date, there are still no approved antifibrotic therapies. Hepatic fibrosis results in portal hypertension and variceal bleeding, and it is the primary cause of mortality from schistosomiasis. Splenomegaly and hypersplenism can manifest following the development of portal hypertension. Accumulating evidence suggests that the spleen plays a critical role in the development of hepatic fibrosis. In this study, using Schistosoma (S.) japonicum in both humans and mice, we show that progressive hepatic schistosomiasis caused elevation of endothelin receptors (ETRs) both in liver and spleen tissues, and the endothelin receptor-producing cells are mainly located in splenic B cells. More importantly, we demonstrate that endothelin receptor antagonists can partially reverse schistosome-induced hepatic fibrosis by suppressing the activation of splenic B cells during infection. Thus, our study highlights the potential of endothelin receptor antagonist as a therapeutic intervention for schistosomiasis and other fibrotic diseases.

The Potential Role of Schistosome-Associated Factors as Therapeutic Modulators of the Immune System

The parasites and eggs of helminths, including schistosomes, are associated with factors that can modulate the nature and outcomes of host immune responses, particularly enhancing type 2 immunity and impairing the effects of type 1 and type 17 immunity. The main species of schistosomes that cause infection in humans are capable of generating a microenvironment that allows survival of the parasite by evasion of the immune response. Schistosome infections are associated with beneficial effects on chronic immune disorders, including allergies, autoimmune diseases, and alloimmune responses. Recently, there has been increasing research interest in the role of schistosomes in immunoregulation during human infection, and the mechanisms underlying these roles continue to be investigated. Further studies may identify potential opportunities to develop new treatments for immune disease. In this review, we provide an update on the advances in our understanding of schistosome-associated modulation of the cells of the innate and adaptive immune systems as well as the potential role of schistosome-associated factors as therapeutic modulators of immune disorders, including allergies, autoimmune diseases, and transplant immunopathology. We also discuss potential opportunities for targeting schistosome-induced immunoregulation for future translation to the clinical setting.

B cells induced by Schistosoma japonicum infection display diverse regulatory phenotypes and modulate CD4+ T cell response

Background

The increased activity of regulatory B cells (Breg) is known to be involved in immunosuppression during helminth infection, which is characterized by inducing IL-10-producing Breg cells. However, the current knowledge of B cell subsets differentiation and IL-10-independent immunoregulatory mechanisms of B cells in schistosomiasis is insufficient.

Methods

BALB/c mice were percutaneously infected with cercariae for investigating the profile of B cell subsets during Schistosoma japonicum infection. B cells isolated from the spleen or peritoneal cavity were analyzed for the regulatory phenotype after stimulation with soluble egg antigens (SEA) in vitro. CD4⁺ T cells were then cocultured with B cells pretreated with or without anti-PD-L1 antibody for investigating the role of B cells from infected mice on regulating CD4⁺ T cells. Furthermore, the in vivo administration of anti-PD-L1 antibody was conducted to investigate the role of PD-L1 in regulating host immunity during infection.

Results

The percentages of peritoneal and splenic B-1a cells, as well as marginal zone B (MZB) cells were decreased at eight and twelve weeks after infection compared to those from uninfected mice. In splenic B cells, TGF-β expression was increased at eight weeks but declined at twelve weeks of infection, and PD-L1 expression was elevated at both eight and twelve weeks of infection. In addition, SEA stimulation in vitro significantly promoted the expression of IL-10 in peritoneal B cells and CD5 in splenic B cells, and the SEA-stimulated splenic and peritoneal B cells preferentially expressed PD-L1 and TGF-β. The splenic B cells from infected mice were able to suppress the function of Th1 and Th2 cells in vitro but to expand the expression of Tfh transcription factor Bcl6, which was further enhanced by blocking PD-L1 of B cells before co-cultivation. Moreover, Th2 response and Bcl6 expression in CD4⁺ T cells were also increased in vivo by blocking PD-L1 after infection, although the hepatic pathology was slightly influenced.

Conclusions

Our findings revealed that S. japonicum infection modulates the differentiation of B cell subsets that have the capability to affect the CD4⁺ T cell response. This study contributes to a better understanding of B cells immune response during schistosomiasis.

Type I interferons provide additive signals for murine regulatory B cell induction by Schistosoma mansoni eggs

The helminth Schistosoma mansoni (S. mansoni) induces a network of regulatory immune cells, including interleukin (IL)-10-producing regulatory B cells (Bregs). However, the signals required for the development and activation of Bregs are not well characterized. Recent reports suggest that helminths induce type I interferons (IFN-I), and that IFN-I drive the development of Bregs in humans. We therefore assessed the role of IFN-I in the induction of Bregs by S. mansoni. Mice chronically infected with S. mansoni or i.v. injected with S. mansoni soluble egg antigen (SEA) developed a systemic IFN-I signature. Recombinant IFN-α enhanced IL-10 production by Bregs stimulated with S. mansoni SEA in vitro, while not activating Bregs by itself. IFN-I signaling also supported ex vivo IL-10 production by SEA-primed Bregs but was dispensable for activation of S. mansoni egg-induced Bregs in vivo. These data indicate that although IFN-I can serve as a coactivator for Breg IL-10 production, they are unlikely to participate in the development of Bregs in response to S. mansoni eggs.

Schistosoma japonicum Soluble Egg Antigen Protects Against Type 2 Diabetes in Lepr db/db Mice by Enhancing Regulatory T Cells and Th2 Cytokines

Type 2 diabetes is a metabolic disorder characterized by persistently elevated glucose levels. There is no effective treatment strategy for this condition, and it poses a massive economic burden globally. Schistosoma soluble egg antigen (SEA)-induced immunomodulatory mechanisms have been reported in the treatment of autoimmune disease. This study aimed to determine the ability of Schistosoma japonicum SEA to protect against type 2 diabetes in Lepr^db/db mice and understand the associated mechanisms. The mice were divided into four groups: C57BL/6 (the normal group), SEA (C57BL/6 mice treated with SEA), Lepr^db/db, and SEA and Lepr^db/db co-treatment groups. The mice in the SEA and co-treatment groups were injected with 50 μg of SEA (twice a week for 6 weeks), and the same volume of PBS was used as control. Blood glucose, insulin, and HOMA-IR levels were measured in all mice, which were sacrificed 6 weeks after the last SEA administration. Flow cytometry was used to detect the percentages of regulatory T cells in splenocytes. ELISA was used to detect the levels of IFN-γ, IL-2, IL-4, and IL-5 in cell culture supernatants. Compared with the mice in the Lepr^db/db group, the mice in the SEA + Lepr^db/db group exhibited significantly reduced insulin resistance, as evidenced by the enhancement of wound healing. The frequency of spleen regulatory T cells increased significantly after SEA administration; meanwhile, the secretion of IL-4 and IL-5 in spleen cells was elevated. These results indicate that SEA can reduce insulin resistance and provide new targets for the treatment of type 2 diabetes. The potential mechanisms might be associated with increases in regulatory T cells and Th2 cytokines in Lepr^db/db mice, which warrants further investigation.

CD9+ Regulatory B Cells Induce T Cell Apoptosis via IL-10 and Are Reduced in Severe Asthmatic Patients

CD9 was recently identified as a marker of murine IL-10-competent regulatory B cells. Functional impairments or defects in CD9⁺ IL-10-secreting regulatory B cells are associated with enhanced asthma-like inflammation and airway hyperresponsiveness. In mouse models, all asthma-related features can be abrogated by CD9⁺ B cell adoptive transfer. We aimed herein to decipher the profiles, features, and molecular mechanisms of the regulatory properties of CD9⁺ B cells in human and mouse. The profile of CD9⁺ B cells was analyzed using blood from severe asthmatic patients and normal and asthmatic mice by flow cytometry. The regulatory effects of mouse CD9⁺ B cells on effector T cell death, cell cycle arrest, apoptosis, and mitochondrial depolarization were determined using yellow dye, propidium iodide, Annexin V, and JC-1 staining. MAPK phosphorylation was analyzed by western blotting. Patients with severe asthma and asthmatic mice both harbored less CD19⁺CD9⁺ B cells, although these cells displayed no defect in their capacity to induce T cell apoptosis. Molecular mechanisms of regulation of CD9⁺ B cells characterized in mouse showed that they induced effector T cell cycle arrest in sub G0/G1, leading to apoptosis in an IL-10-dependent manner. This process occurred through MAPK phosphorylation and activation of both the intrinsic and extrinsic pathways. This study characterizes the molecular mechanisms underlying the regulation of CD9⁺ B cells to induce effector T cell apoptosis in mice and humans via IL-10 secretion. Defects in CD9⁺ B cells in blood from patients with severe asthma reveal new insights into the lack of regulation of inflammation in these patients.

Helminth parasites and immune regulation

Helminth parasites are complex metazoans that belong to different taxonomic families but that collectively share the capacity to downregulate the host immune response directed toward themselves (parasite-specific immunoregulation). During long-standing chronic infection, these helminths appear able to suppress immune responses to bystander pathogens/antigens and atopic, autoimmune, and metabolic disorders. Helminth-induced immunoregulation occurs through the induction of regulatory T cells or Th2-type cells (or both). However, secreted or excreted parasite metabolites, proteins, or extracellular vesicles (or a combination of these) may also directly induce signaling pathways in host cells. Therefore, the focus of this review will be to highlight recent advances in understanding the immune responses to helminth infection, emphasizing the strategies/molecules and some of the mechanisms used by helminth parasites to modulate the immune response of their hosts.

Helminth Modulation of Lung Inflammation

Parasitic helminths must establish chronic infections to complete their life cycle and therefore are potent modulators of multiple facets of host physiology. Parasitic helminths have coevolved with humans to become arguably master selectors of our immune system, whereby they have impacted on the selection of genes with beneficial mutations for both host and parasite. While helminth infections of humans are a significant health burden, studies have shown that helminths or helminth products can alter susceptibility to unrelated infectious or inflammatory diseases. This has generated interest in the use of helminth infections or molecules as therapeutics. In this review, we focus on the impact of helminth infections on pulmonary immunity, especially with regard to homeostatic lung function, pulmonary viral and bacterial (co)infections, and asthma.

Immunity and Fibrogenesis: The Role of Th17/IL-17 Axis in HBV and HCV-induced Chronic Hepatitis and Progression to Cirrhosis

Cirrhosis is a common final pathway for most chronic liver diseases; representing an increasing burden worldwide and is associated with increased morbidity and mortality. Current evidence has shown that, after an initial injury, the immune response has a significant participation in the ongoing damage, and progression from chronic viral hepatitis (CVH) to cirrhosis, driving the activation and maintenance of main fibrogenic pathways. Among immune deregulations, those related to the subtype 17 of T helper lymphocytes (Th17)/interleukin-17 (IL-17) axis have been recognized as key immunopathological and prognostic elements in patients with CVH. The Th17/IL-17 axis has been found involved in several points of fibrogenesis chain from the activation of stellate cells, increased expression of profibrotic factors as TGF-β, promotion of the myofibroblastic or epithelial–mesenchymal transition, stimulation of the synthesis of collagen, and induction of imbalance between matrix metalloproteinases and tissue inhibitors of metalloproteinases (TIMPs). It also promotes the recruitment of inflammatory cells and increases the expression of proinflammatory cytokines such as IL-6 and IL-23. So, the Th17/IL-17 axis is simultaneously the fuel and the flame of a sustained proinflammatory and profibrotic environment. This work aims to present the immunopathologic and prognostic role of the Th17/IL-17 axis and related pathways in fibrogenesis and progression to cirrhosis in patients with liver disease due to hepatitis B virus (HBV) and hepatitis C virus (HCV).

B10 Cells Alleviate Periodontal Bone Loss in Experimental Periodontitis

B10 cells can regulate inflammatory responses in innate immunity. Toll-like receptors (TLRs) play an important role in B cell-mediated immune responses in periodontal disease. This study aimed to determine the effects of TLR-activated B10 cells on periodontal bone loss in experimental periodontitis. Spleen B cells isolated from C57BL/6J mice were cultured with Porphyromonas gingivalis lipopolysaccharide (LPS) and cytosine-phospho-guanine (CpG) oligodeoxynucleotides for 48 h. B10-enriched CD1d^hi CD5⁺ B cells were sorted by flow cytometry and were adoptively transferred to recipient mice through tail vein injection. At the same time, P. gingivalis-soaked ligatures were placed subgingivally around the maxillary second molars and remained there for 2 weeks before the mice were euthanized. Interleukin-10 (IL-10) production and the percentage of CD1d^hi CD5⁺ B cells were significantly increased with treatment with P. gingivalis LPS plus CpG compared to those in mice treated with P. gingivalis LPS or CpG alone. Mice with CD1d^hi CD5⁺ B cell transfer demonstrated reduced periodontal bone loss compared to the no-transfer group and the group with CD1d^lo CD5^- B cell transfer. Gingival IL-10 mRNA expression was significantly increased, whereas expressions of receptor activator of NF-κB ligand (RANKL)/osteoprotegerin (OPG), tumor necrosis factor alpha (TNF-α), and IL-1β were significantly inhibited in the CD1d^hi CD5⁺ B cell transfer group. The percentages of CD19⁺ IL-10⁺ cells, CD19⁺ CD1d^hi CD5⁺ cells, and P. gingivalis-binding CD19⁺ cells were significantly higher in recovered mononuclear cells from gingival tissues of the CD1d^hi CD5⁺ B cell transfer group than in tissues of the no-transfer group and the CD1d^lo CD5^- B cell transfer group. This study indicated that the adoptive transfer of B10 cells alleviated periodontal inflammation and bone loss in experimental periodontitis in mice.

Schistosome egg antigens, including the glycoprotein IPSE/alpha-1, trigger the development of regulatory B cells

Infection with the helminth Schistosoma (S.) mansoni drives the development of interleukin (IL)-10-producing regulatory B (Breg) cells in mice and man, which have the capacity to reduce experimental allergic airway inflammation and are thus of high therapeutic interest. However, both the involved antigen and cellular mechanisms that drive Breg cell development remain to be elucidated. Therefore, we investigated whether S. mansoni soluble egg antigens (SEA) directly interact with B cells to enhance their regulatory potential, or act indirectly on B cells via SEA-modulated macrophage subsets. Intraperitoneal injections of S. mansoni eggs or SEA significantly upregulated IL-10 and CD86 expression by marginal zone B cells. Both B cells as well as macrophages of the splenic marginal zone efficiently bound SEA in vivo, but macrophages were dispensable for Breg cell induction as shown by macrophage depletion with clodronate liposomes. SEA was internalized into acidic cell compartments of B cells and induced a 3-fold increase of IL-10, which was dependent on endosomal acidification and was further enhanced by CD40 ligation. IPSE/alpha-1, one of the major antigens in SEA, was also capable of inducing IL-10 in naïve B cells, which was reproduced by tobacco plant-derived recombinant IPSE. Other major schistosomal antigens, omega-1 and kappa-5, had no effect. SEA depleted of IPSE/alpha-1 was still able to induce Breg cells indicating that SEA contains more Breg cell-inducing components. Importantly, SEA- and IPSE-induced Breg cells triggered regulatory T cell development in vitro. SEA and recombinant IPSE/alpha-1 also induced IL-10 production in human CD1d⁺ B cells. In conclusion, the mechanism of S. mansoni-induced Breg cell development involves a direct targeting of B cells by SEA components such as the secretory glycoprotein IPSE/alpha-1.

Infection with helminth parasites is known to be inversely associated with hyper-inflammatory disorders. While Schistosoma (S.) mansoni has been described to exert its down-modulatory effects on inflammation by inducing a network of regulatory immune cells such as regulatory B (Breg), the mechanisms of Breg cell induction remain unclear. Here, we use in vivo and in vitro approaches to show that antigens from S. mansoni eggs, among which the major glycoprotein IPSE/alpha-1, directly interact with splenic marginal zone B cells of mice which triggers them to produce the anti-inflammatory cytokine IL-10 and their capacity to induce regulatory T (Treg) cells. We also found that IPSE/alpha-1 induces IL-10 in human CD1d⁺ B cells, and that both natural and recombinant IPSE/alpha-1 are equally effective in driving murine and human Breg cells. Our study thus provides insight into the mechanisms of Breg cell induction by schistosomes, and an important step towards the development of helminth-based treatment strategies against hyper-inflammatory diseases.

Regulatory B cells in infectious disease (Review)

Regulatory B cells (Bregs) are a subset of B cells, which reportedly exert significant immunomodulatory effects through the production of interleukin (IL)-10, IL-35 and transforming growth factor-β. Over the last decade, studies have indicated that Bregs function in autoimmune and allergic diseases through antigen-specific and non-specific immunoregulatory mechanisms. However, only a limited number of reviews have focused on the role of Bregs during infection, particularly their functions in intracellular infections. The present review discusses the role of Bregs in infectious diseases in animal models and human studies, and provides an overview of the immunoregulatory mechanisms used by Bregs.

The dynamic changes of CD3e-CD11c+ dendritic cells in spleens and bone marrow of mice infected with Schistosoma japonicum

Schistosoma japonicum as a pathogeny requires dendritic cells to activate immune response. So, the research is to study the dynamic changes of CD3e^-CD11c⁺ dendritic cells in mice infected with S. japonicum. Zero, 7, 28, 35, and 63 days were selected to study the variation of dendritic cells, and the proportions of CD3e^-CD11c⁺ dendritic cells and CD86⁺ mature dendritic cells in spleens and bone marrow were tested by flow cytometry. As a result, the variation trends of dendritic cells in spleen and bone marrow are similar as follows: the proportions of CD3e^-CD11c⁺ dendritic cells increased first and then decreased from day 35, but the percentages of CD86⁺ mature dendritic cells decreased from day 28 and increased in day 63. In vitro, cultured dendritic cells treated with SEA and SAWA were tested by flow cytometry, the variation trends of CD86 on dendritic cells are consistent with the results in days 28 and 63. Besides CD86, the expression of MHC-II also hints immune regulation. In conclusion, it is speculated that dendritic cells play a role of immune regulation through MHC-II and CD86 in S. japonicum infection. Immune regulation of dendritic cells is not only in favor of the survival of host and parasite but also can be used in the therapy for immune diseases.

The Tao survivorship of schistosomes: implications for schistosomiasis control

Schistosomiasis, caused by blood flukes of the genus Schistosoma, is a major public health problem which contributes substantially to the economic and financial burdens of many nations in the developing world. An array of survival strategies, such as the unique structure of the tegument which acts as a major host-parasite interface, immune modulation mechanisms, gene regulation, and apoptosis and self-renewal have been adopted by schistosome parasites over the course of long-term evolution with their mammalian definitive hosts. Recent generation of complete schistosome genomes together with numerous biological, immunological, high-throughput "-omics" and gene function studies have revealed the Tao or strategies that schistosomes employ not only to promote long-term survival, but also to ensure effective life cycle transmission. New scenarios for the future control of this important neglected tropical disease will present themselves as our understanding of these Tao increases.