Mast cells counteract regulatory T-cell suppression through interleukin-6 and OX40/OX40L axis toward Th17-cell differentiation

OX40L induces helper T cell differentiation during cell immunity of asthma through PI3K/AKT and P38 MAPK signaling pathway

Background

The aim of this study was to investigate the mechanisms of OX40L in regulating helper T (Th) cells differentiation through phosphoinositide 3-kinase (PI3K)/AKT and p38 mitogen-activated protein kinase signaling pathway in vitro and in vivo experiments.

Methods

Serum samples of patients with asthma and healthy controls were used to explore the association between OX40L and Th cells. Enzyme-linked immunosorbent assay (ELISA) was used to measure the serum concentrations of OX40L, IL-4, IFN-γ, IL-17 and TGF-β. Flow cytometry method was used to analyze Th1, Th2, Th17 and Treg cells. 3H-thymidine was used to determine the proliferation of T cells. Western Blot was used to detect protein expression and phosphorylation. Immunohistochemistry was used to detect the expression of OX40L in lung tissues.

Results

OX40L, IL-4, IL-17 increased in patient serum compared to healthy control and in the ovalbumin (OVA)-primed mononuclear cells compared to normal cells, while IFN-γ and TGF-β were decreased. Besides, the OVA-primed CD4⁺ T cells treated with OX40L-Ig fusion protein promoted the proliferation of T cells and Th2 and Th17 cells differentiation as well as PI3K/AKT and p38 MAPK signaling pathway, but suppressed Th1 and Treg cells differentiation. Moreover, helper T cells differentiation in OVA-primed CD4⁺ T cells could be markedly reversed by the addition of PI3K/AKT inhibition, p38 MAPK inhibition and anti-OX40L monoclonal antibody.

Conclusions

In this study, we revealed that OX40L could regulate differentiation of helper T cells via PI3K/AKT and p38 MAPK signaling pathway in asthma. Besides, blockade of OX40/OX40L could inhibit the proliferation of CD4⁺ T cells and regulate polarization of helper T cells.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1436-4) contains supplementary material, which is available to authorized users.

Autoimmunity in multiple sclerosis: role of sphingolipids, invariant NKT cells and other immune elements in control of inflammation and neurodegeneration

Multiple sclerosis (MS) is the most common demyelinating disease of the central nervous system. It is classified as being an autoimmune response in the genetically susceptible individual to a persistent but unidentified antigen(s). Both the adaptive and the innate immune systems are likely to contribute significantly to MS pathogenesis. This review summarizes current understanding of the characteristics of MS autoimmunity in the initiation and progression of the disease. In particular we find it timely to classify the autoimmune responses by focusing on the immunogenic features of myelin-derived lipids in MS including molecular mimicry; on alterations of bioactive sphingolipids mediators in MS; and on functional roles for regulatory effector cells, including innate lymphocyte populations, like the invariant NKT (iNKT) cells which bridge adaptive and innate immune systems. Recent progress in identifying the nature of sphingolipids recognition for iNKT cells in immunity and the functional consequences of the lipid-CD1d interaction opens new avenues of access to the pathogenesis of demyelination in MS as well as design of lipid antigen-specific therapeutics.

Therapeutic application of T regulatory cells in composite tissue allotransplantation

With growing number of cases in recent years, composite tissue allotransplantation (CTA) has been improving the quality of life of patient who seeks reconstruction and repair of damaged tissues. Composite tissue allografts are heterogeneous. They are composed of a variety of tissue types, including skin, muscle, vessel, bone, bone marrow, lymph nodes, nerve, and tendon. As a primary target of CTA, skin has high antigenicity with a rich repertoire of resident cells that play pivotal roles in immune surveillance. In this regard, understanding the molecular mechanisms involved in immune rejection in the skin would be essential to achieve successful CTA. Although scientific evidence has proved the necessity of immunosuppressive drugs to prevent rejection of allotransplanted tissues, there remains a lingering dilemma due to the lack of specificity of targeted immunosuppression and risks of side effects. A cumulative body of evidence has demonstrated T regulatory (Treg) cells have critical roles in induction of immune tolerance and immune homeostasis in preclinical and clinical studies. Presently, controlling immune susceptible characteristics of CTA with adoptive transfer of Treg cells is being considered promising and it has drawn great interests. This updated review will focus on a dominant form of Treg cells expressing CD4+CD25+ surface molecules and a forkhead box P3 transcription factor with immune tolerant and immune homeostasis activities. For future application of Treg cells as therapeutics in CTA, molecular and cellular characteristics of CTA and immune rejection, Treg cell development and phenotypes, Treg cell plasticity and stability, immune tolerant functions of Treg cells in CTA in preclinical studies, and protocols for therapeutic application of Treg cells in clinical settings are addressed in this review. Collectively, Treg cell therapy in CTA seems feasible with promising perspectives. However, the extreme high immunogenicity of CTA warrants caution.

Deciphering new mechanisms on T-cell costimulation by human mast cells

It is well established that full activation of T cells to recognize a specific antigen requires additional signals. These secondary signals are generated by the interaction of costimulatory molecules expressed on APCs. Classical APCs include DCs, macrophages, Langerhans cells, and B cells. However, in recent years, several haematopoietic and nonhaematopoietic cells have been described to express MHC class II antigens and, in appropriate conditions, costimulatory molecules. In this issue, Suurmond et al. [Eur. J. Immunol. 2016. 46: 1132-1141] show, for the first time, that human mast cells not only express costimulatory molecules of the TNF-receptor and CD28 families, but can also costimulate T cells through a yet-to-be-defined CD28-independent interaction.

Skin Immunity

Skin is the largest organ of the body with a complex network of multitude of cell types that perform plastic and dynamic cellular communication to maintain several vital processes such as inflammation, immune response including induction of tolerance and disease prevention, wound healing, and angiogenesis. Of paramount importance are immunological functions of the skin that protect from harmful exposure coming from external and internal environments. Awareness of skin immunity can provide a better comprehension of inflammation, autoimmunity, cancer, graft-versus-host disease, vaccination, and immunotherapy approaches. This paper will update on what we currently know about immune sentinels contributing to skin immunity.

Fifty years later: Emerging functions of IgE antibodies in host defense, immune regulation, and allergic diseases

Fifty years ago, after a long search, IgE emerged as the circulating factor responsible for triggering allergic reactions. Its extremely low concentration in plasma created significant hurdles for scientists working to reveal its identity. We now know that IgE levels are invariably increased in patients affected by atopic conditions and that IgE provides the critical link between the antigen recognition role of the adaptive immune system and the effector functions of mast cells and basophils at mucosal and cutaneous sites of environmental exposure. This review discusses the established mechanisms of action of IgE in pathologic immediate hypersensitivity, as well as its multifaceted roles in protective immunity, control of mast cell homeostasis, and its more recently revealed immunomodulatory functions.

Allergen-specific IgG antibody signaling through FcγRIIb promotes food tolerance

BACKGROUND

Patients with food allergy produce high-titer IgE antibodies that bind to mast cells through FcεRI and trigger immediate hypersensitivity reactions on antigen encounter. Food-specific IgG antibodies arise in the setting of naturally resolving food allergy and accompany the acquisition of food allergen unresponsiveness in oral immunotherapy.

OBJECTIVE

In this study we sought to delineate the effects of IgG and its inhibitory Fc receptor, FcγRIIb, on both de novo allergen sensitization in naive animals and on established immune responses in the setting of pre-existing food allergy.

METHODS

Allergen-specific IgG was administered to mice undergoing sensitization and desensitization to the model food allergen ovalbumin. Cellular and molecular mechanisms were interrogated by using mast cell- and FcγRIIb-deficient mice. The requirement for FcγRII in IgG-mediated inhibition of human mast cells was investigated by using a neutralizing antibody.

RESULTS

Administration of specific IgG to food allergy-prone IL4raF709 mice during initial food exposure prevented the development of IgE antibodies, T_H2 responses, and anaphylactic responses on challenge. When given as an adjunct to oral desensitization in mice with established IgE-mediated hypersensitivity, IgG facilitated tolerance restoration, favoring expansion of forkhead box protein 3-positive regulatory T cells along with suppression of existing T_H2 and IgE responses. IgG and FcγRIIb suppress adaptive allergic responses through effects on mast cell function.

CONCLUSION

These findings suggest that allergen-specific IgG antibodies can act to induce and sustain immunologic tolerance to foods.

Th17 cell-mediated immune responses promote mast cell proliferation by triggering stem cell factor in keratinocytes

Although mast cells are traditionally thought to function as effector cells in allergic responses, they have increasingly been recognized as important regulators of various immune responses. Mast cells mature locally; thus, tissue-specific influences are important for promoting mast cell accumulation and survival in the skin and the gastrointestinal tract. In this study, we determined the effects of keratinocytes on mast cell accumulation during Th17-mediated skin inflammation. We observed increases in dermal mast cells in imiquimod-induced psoriatic dermatitis in mice accompanied by the expression of epidermal stem cell factor (SCF), a critical mast cell growth factor. Similar to mouse epidermal keratinocytes, SCF was highly expressed in the human HaCaT keratinocyte cell line following stimulation with IL-17. Further, keratinocytes promoted mast cell proliferation following stimulation with IL-17 in vitro. However, the effects of keratinocytes on mast cells were significantly diminished in the presence of anti-CD117 (stem cell factor receptor) blocking antibodies. Taken together, our results revealed that the Th17-mediated inflammatory environment promotes mast cell accumulation through keratinocyte-derived SCF.

OX40, OX40L and Autoimmunity: a Comprehensive Review

The tumour necrosis factor receptor OX40 (CD134) is activated by its cognate ligand OX40L (CD134L, CD252) and functions as a T cell co-stimulatory molecule. OX40-OX40L interactions have been proposed as a potential therapeutic target for treating autoimmunity. OX40 is expressed on activated T cells, and in the mouse at rest on regulatory T cells (Treg). OX40L is found on antigen-presenting cells, activated T cells and others including lymphoid tissue inducer cells, some endothelia and mast cells. Expression of both molecules is increased after antigen presentation occurs and also in response to multiple other pro-inflammatory factors including CD28 ligation, CD40L ligation and interferon-gamma signaling. Their interactions promote T cell survival, promote an effector T cell phenotype, promote T cell memory, tend to reduce regulatory function, increase effector cytokine production and enhance cell mobility. In some circumstances, OX40 agonism may be associated with increased tolerance, although timing with respect to antigenic stimulus is important. Further, recent work has suggested that OX40L blockade may be more effective than OX40 blockade in reducing autoimmunity. This article reviews the expression of OX40 and OX40L in health, the effects of their interactions and insights from their under- or over-expression. We then review OX40 and OX40L expression in human autoimmune disease, identified associations of variations in their genes (TNFRSF4 and TNFSF4, respectively) with autoimmunity, and data from animal models of human diseases. A rationale for blocking OX40-OX40L interaction in human autoimmunity is then presented along with commentary on the one trial of OX40L blockade in human disease conducted to date. Finally, we discuss potential problems with clinical use of OX40-OX40L directed pharmacotherapy.

Expansion of Th17 Cells by Human Mast Cells Is Driven by Inflammasome-Independent IL-1β

Mast cells (MC) are most well known for their role in innate immune responses. However, MC are increasingly recognized as important regulators of adaptive immune responses, especially in setting the outcome of T cell responses. In this study we determined the effect of MC on cytokine production by naive and memory human Th cells. CD4⁺ T cells were cultured with MC supernatant or control medium, after which cytokine production by T cells was determined. Supernatant of activated MC specifically increased the number of IL-17-producing T cells. This enhancement of Th17 cell number was specifically observed for the memory CD4⁺ T cell population and not for the naive CD4⁺ T cell population. The effect of MC was inhibited for ∼80% by blocking Abs to IL-1β and the rIL-1R antagonist anakinra. Importantly, secretion of active IL-1β by MC was independent of caspase activity, indicating that Th17 cell expansion by MC occurred through inflammasome-independent IL-1β. Together, these studies reveal a role for human MC in setting the outcome of T cell responses through release of caspase-independent IL-1β, and provide evidence for a novel contribution of MC in boosting the Th17 axis in mucosal immune responses.

Vam3, a Compound Derived from Vitis amurensis Rupr., Attenuated Colitis-Related Tumorigenesis by Inhibiting NF-κB Signaling Pathway

Background: Chronic inflammation is one of the important mediators of colitis-related colon cancer (CRC). Abundant mast cells (MCs) were observed in the tumor microenvironment and mediators released upon MC activation play an important role in the process of chronic inflammation. Previously, we found that activation of intestine mucosal MCs recruited and modulated the inflammatory CD11b⁺Gr1⁺ cells to promote the CRC development. In the current study we investigated the effects of Vam3, a resveratrol dimer with potent anti-inflammatory effects, on CRC development.

Methods: RBL-2H3 cells, a basophilic leukemia cell line, were pretreated with 2.5 or 5 µM Vam3 and then stimulated with dinitrophenol-conjugated bovine serum albumin (DNP-BSA) plus lipopolysaccharide (LPS). The MC degranulation was determined by measuring β-hexosaminidase release. Generation of TNF-α and IL-6 in RBL-2H3 cells or in peritoneal macrophages was determined by ELISA and real-time qPCR. NF-κB p65 and phospho-NF-κB p65 expression was determined by Western blotting. NF-κB activity in RAW264.7 cells was determined by luciferase reporter assay. CRC was induced in C57BL/6 mice by intraperitoneal injection of azoxymethane (AOM), followed by oral exposure to dextran sodium sulfate (DSS). Vam3 at 50 mg/kg, or disodium cromoglycate (DSCG, MC stabilizer) at 100 mg/kg, or vehicle were administrated to the mice 4 weeks after DSS withdrawal. Levels of TNF-α, IL-6, and mouse MC protease-1 were determined by ELISA. Infiltration of CD11b⁺Gr1⁺ cells was determined by flow cytometry analysis. One-way ANOVA was used to compare difference between groups.

Results: Pretreatment with Vam3 significantly inhibited RBL-2H3 cell degranulation and inflammatory cytokine production from RBL-2H3 cells and from peritoneal macrophages. After Vam3 treatment, NF-κB activity in RAW264.7 cells, and expressions of phospho-NF-κB p65 in RBL-2H3 cells and in peritoneal macrophages were significantly down-regulated. In the AOM plus DSS-induced CRC murine model, the Vam3 and DSCG-treated mice had less tumor numbers than those treated with vehicle. Expression of phospho-NF-κB p65, production of inflammatory cytokines, and infiltration of MCs and CD11b⁺Gr1⁺ cells were attenuated in the Vam3-treated mice.

Conclusion: Vam3 treatment could attenuate the CRC development. This effect may be due to its inhibition on NF-κB signaling pathway in MCs and macrophages of the inflamed intestines.

Purinergic regulation of the immune system

Cellular stress or apoptosis triggers the release of ATP, ADP and other nucleotides into the extracellular space. Extracellular nucleotides function as autocrine and paracrine signalling molecules by activating cell-surface P2 purinergic receptors that elicit pro-inflammatory immune responses. Over time, extracellular nucleotides are metabolized to adenosine, leading to reduced P2 signalling and increased signalling through anti-inflammatory adenosine (P1 purinergic) receptors. Here, we review how local purinergic signalling changes over time during tissue responses to injury or disease, and we discuss the potential of targeting purinergic signalling pathways for the immunotherapeutic treatment of ischaemia, organ transplantation, autoimmunity or cancer.

Meningeal mast cell-T cell crosstalk regulates T cell encephalitogenicity

GM-CSF is a cytokine produced by T helper (Th) cells that plays an essential role in orchestrating neuroinflammation in experimental autoimmune encephalomyelitis, a rodent model of multiple sclerosis. Yet where and how Th cells acquire GM-CSF expression is unknown. In this study we identify mast cells in the meninges, tripartite tissues surrounding the brain and spinal cord, as important contributors to antigen-specific Th cell accumulation and GM-CSF expression. In the absence of mast cells, Th cells do not accumulate in the meninges nor produce GM-CSF. Mast cell-T cell co-culture experiments and selective mast cell reconstitution of the meninges of mast cell-deficient mice reveal that resident meningeal mast cells are an early source of caspase-1-dependent IL-1β that licenses Th cells to produce GM-CSF and become encephalitogenic. We also provide evidence of mast cell-T cell co-localization in the meninges and CNS of recently diagnosed acute MS patients indicating similar interactions may occur in human demyelinating disease.

Challenges and opportunities in treating inflammation associated with pulmonary hypertension

INTRODUCTION

Inflammatory cells are present in the lungs from patients with many, if not all, forms of severe pulmonary hypertension.

AREAS COVERED

Historically the first inflammatory cell identified in the pulmonary vascular lesions was the mast cell. T and B lymphocytes, as well as macrophages, are present in and around the pulmonary arterioles and many patients have elevated blood levels of interleukin 1 and 6; some patients show elevated levels of leukotriene B4. An overlap between collagen-vascular disease-associated pulmonary arterial hypertension (PAH) and idiopathic PAH exists, yet only a few studies have been designed that evaluate the effect of anti-inflammatory treatments. Here we review the pertinent data that connect PAH and inflammation/autoimmune dysregulation and evaluate experimental models of severe PAH with an emphasis on the Sugen/athymic rat model of severe PAH. Expert commentary: We postulate that there are several inflammatory phenotypes and predict that there will be several anti-inflammatory treatment strategies for severe PAH.

Mast cells contribute to autoimmune diabetes by releasing interleukin-6 and failing to acquire a tolerogenic IL-10+ phenotype

Mast cells (MCs) are innate immune cells that exert positive and negative immune modulatory functions capable to enhance or limit the intensity and/or duration of adaptive immune responses. Although MCs are crucial to regulate T cell immunity, their action in the pathogenesis of autoimmune diseases is still debated. Here we demonstrate that MCs play a crucial role in T1D pathogenesis so that their selective depletion in conditional MC knockout NOD mice protects them from the disease. MCs of diabetic NOD mice are overly inflammatory and secrete large amounts of IL-6 that favors differentiation of IL-17-secreting T cells at the site of autoimmunity. Moreover, while MCs of control mice acquire an IL-10+ phenotype upon interaction with FoxP3+ Treg cells, MCs of NOD mice do not undergo this tolerogenic differentiation. Our data indicate that overly inflammatory MCs unable to acquire a tolerogenic IL-10+ phenotype contribute to the pathogenesis of autoimmune T1D.

Regulatory T cells that co-express RORγt and FOXP3 are pro-inflammatory and immunosuppressive and expand in human pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is highly infiltrated by CD4⁺T cells that express RORγt and IL-17 (T_H17). Compelling evidence from the tumor microenvironment suggest that regulatory T cells (T_reg) contribute to T_H17 mediated inflammation. Concurrently, PDAC patients have elevated levels of pro-inflammatory cytokines that may lead to T_H17 associated functional plasticity in T_reg. In this study, we investigated the phenotype and functional properties of T_reg in patients with PDAC. We report that PDAC patients have elevated frequency of FOXP3⁺T_reg, which exclusively occurred within the FOXP3⁺RORγt⁺T_reg compartment. The FOXP3⁺RORγt⁺T_reg retained FOXP3⁺T_reg markers and represented an activated subset. The expression of RORγt in T_reg may indicate a phenotypic switch toward T_H17 cells. However, the FOXP3⁺RORγt⁺T_reg produced both T_H17 and T_H2 associated pro-inflammatory cytokines, which corresponded with elevated T_H17 and T_H2 immune responses in PDAC patients. Both the FOXP3⁺T_reg and FOXP3⁺RORγt⁺T_reg from PDAC patients strongly suppressed T cell immune responses, but they had impaired anti-inflammatory properties. We conclude that FOXP3⁺RORγt⁺T_reg have a dual phenotype with combined pro-inflammatory and immunosuppressive activity, which may be involved in the pathogenesis of PDAC.

An Interleukin-33-Mast Cell-Interleukin-2 Axis Suppresses Papain-Induced Allergic Inflammation by Promoting Regulatory T Cell Numbers

House dust mite-derived proteases contribute to allergic disorders in part by disrupting epithelial barrier function. Interleukin-33 (IL-33), produced by lung cells after exposure to protease allergens, can induce innate-type airway eosinophilia by activating natural helper (NH) cells, a member of group 2 innate lymphoid cells (ILC2), to secrete Th2 type-cytokines. Because IL-33 also can induce mast cells (MCs) to secrete Th2 type-cytokines, MCs are thought to cooperate with NH cells in enhancing protease or IL-33-mediated innate-type airway eosinophilia. However, we found that MC-deficient Kit(W-sh/W-sh) mice exhibited exacerbated protease-induced lung inflammation associated with reduced numbers of regulatory T (Treg) cells. Moreover, IL-2 produced by IL-33-stimulated MCs promoted expansion of numbers of Treg cells, thereby suppressing development of papain- or IL-33-induced airway eosinophilia. We have thus identified a unique anti-inflammatory pathway that can limit induction of innate-type allergic airway inflammation mediated by NH cells.

Mast Cells as Regulators of T Cell Responses

Mast cells (MCs) are recognized to participate in the regulation of innate and adaptive immune responses. Owing to their strategic location at the host–environment interface, they control tissue homeostasis and are key cells for starting early host defense against intruders. Upon degranulation induced, e.g., by immunoglobulin E (IgE) and allergen-mediated engagement of the high-affinity IgE receptor, complement or certain neuropeptide receptors, MCs release a wide variety of preformed and newly synthesized products including proteases, lipid mediators, and many cytokines, chemokines, and growth factors. Interestingly, increasing evidence suggests a regulatory role for MCs in inflammatory diseases via the regulation of T cell activities. Furthermore, rather than only serving as effector cells, MCs are now recognized to induce T cell activation, recruitment, proliferation, and cytokine secretion in an antigen-dependent manner and to impact on regulatory T cells. This review synthesizes recent developments in MC–T cell interactions, discusses their biological and clinical relevance, and explores recent controversies in this field of MC research.

Methods for the study of mast cells in cancer

Tumor growth requires interactions of tumor cells with a receptive and inductive microenvironment. Two major populations of tumor-infiltrating cells are considered to be essential for producing such a microenvironment: (1) proinflammatory cells that nurture the tumor with growth factors and facilitate invasion and metastasis by secreting proteases and (2) immune suppressive leukocytes including T-regulatory cells (Treg) that hinder tumor-specific CD8 T-cell responses, which otherwise could potentially reject the tumor. Among the proinflammatory cells, accumulation of mast cells (MCs) in human tumors is frequently recorded and was recently linked with poor prognosis. Causative links between mast cell infiltration and tumor progression can be deduced from animal studies. There is an interesting link between mast cells and Treg. The adoptive transfer of Treg from healthy syngeneic mice to mice susceptible to colon cancer suppresses focal mastocytosis and hinders tumor progression. Furthermore, T-cell-deficient mice susceptible to colon cancer show enhanced focal mastocytosis and tumor invasion. Here, we describe methods to assess MCs in mouse models of cancer and to investigate how MCs affect tumor epithelium. Additionally, we will detail methods used to investigate how T cells influence MCs and how MCs influence T cells.

Pathogenesis of Systemic Sclerosis

Systemic scleroderma (SSc) is one of the most complex systemic autoimmune diseases. It targets the vasculature, connective tissue-producing cells (namely fibroblasts/myofibroblasts), and components of the innate and adaptive immune systems. Clinical and pathologic manifestations of SSc are the result of: (1) innate/adaptive immune system abnormalities leading to production of autoantibodies and cell-mediated autoimmunity, (2) microvascular endothelial cell/small vessel fibroproliferative vasculopathy, and (3) fibroblast dysfunction generating excessive accumulation of collagen and other matrix components in skin and internal organs. All three of these processes interact and affect each other. The disease is heterogeneous in its clinical presentation that likely reflects different genetic or triggering factor (i.e., infection or environmental toxin) influences on the immune system, vasculature, and connective tissue cells. The roles played by other ubiquitous molecular entities (such as lysophospholipids, endocannabinoids, and their diverse receptors and vitamin D) in influencing the immune system, vasculature, and connective tissue cells are just beginning to be realized and studied and may provide insights into new therapeutic approaches to treat SSc.

IL17 Mediates Pelvic Pain in Experimental Autoimmune Prostatitis (EAP)

Chronic pelvic pain syndrome (CPPS) is the most common form of prostatitis, accounting for 90-95% of all diagnoses. It is a complex multi-symptom syndrome with unknown etiology and limited effective treatments. Previous investigations highlight roles for inflammatory mediators in disease progression by correlating levels of cytokines and chemokines with patient reported symptom scores. It is hypothesized that alteration of adaptive immune mechanisms results in autoimmunity and subsequent development of pain. Mouse models of CPPS have been developed to delineate these immune mechanisms driving pain in humans. Using the experimental autoimmune prostatitis (EAP) in C57BL/6 mice model of CPPS we examined the role of CD4+T-cell subsets in the development and maintenance of prostate pain, by tactile allodynia behavioral testing and flow cytometry. In tandem with increased CD4+IL17A+ T-cells upon EAP induction, prophylactic treatment with an anti-IL17 antibody one-day prior to EAP induction prevented the onset of pelvic pain. Therapeutic blockade of IL17 did not reverse pain symptoms indicating that IL17 is essential for development but not maintenance of chronic pain in EAP. Furthermore we identified a cytokine, IL7, to be associated with increased symptom severity in CPPS patients and is increased in patient prostatic secretions and the prostates of EAP mice. IL7 is fundamental to development of IL17 producing cells and plays a role in maturation of auto-reactive T-cells, it is also associated with autoimmune disorders including multiple sclerosis and type-1 diabetes. More recently a growing body of research has pointed to IL17's role in development of neuropathic and chronic pain. This report presents novel data on the role of CD4+IL17+ T-cells in development and maintenance of pain in EAP and CPPS.

Paradigm shifts in mast cell and basophil biology and function: an emerging view of immune regulation in health and disease

The physiological role of the mast cell and basophil has for many years remained enigmatic. In this chapter we briefly summarize some of the more recent studies that shed new light on the role of mast cells and basophils in health and disease. What we gain from these studies is a new appreciation for mast cells and basophils as sentinels in host defense and a further understanding that dysregulation of mast cell and basophil function can be a component of various diseases other than allergies. Perhaps, the most important insight reaped from this work is the increasing awareness that mast cells and basophils can function as immunoregulatory cells that modulate the immune response in health and disease. Collectively, the recent knowledge provides new challenges and opportunities towards the development of novel therapeutic strategies to augment host protection and modify disease through manipulation of mast cell and basophil function.

Mast cell and autoimmune diseases

Mast cells are important in innate immune system. They have been appreciated as potent contributors to allergic reaction. However, increasing evidence implicates the important role of mast cells in autoimmune disease like rheumatoid arthritis and multiple sclerosis. Here we review the current stage of knowledge about mast cells in autoimmune diseases.

The Killer Cell Ig-like Receptor 2DL4 Expression in Human Mast Cells and Its Potential Role in Breast Cancer Invasion

The killer-cell Ig-like receptor (KIR) 2DL4 (CD158d) acts as a receptor for human leukocyte antigen (HLA)-G and is expressed on almost all human natural killer (NK) cells. The expression and function of KIR2DL4 in other hematopoietic cells is poorly understood. Here, we focused on human mast cells, which exhibit cytotoxic activity similar to that of NK cells. KIR2DL4 was detected in all examined human cultured mast cells established from peripheral blood derived from healthy volunteers (PB-mast), the human mast cell line LAD2, and human nonneoplastic mast cells, including those on pathologic specimens. An agonistic antibody against KIR2DL4 decreased KIT-mediated and IgE-triggered responses, and enhanced the granzyme B production by PB-mast and LAD2 cells, by activating Src homology 2-containing protein tyrosine phosphatase (SHP-2). Next, we performed a coculture assay between LAD2 cells and the HLA-G(+) cancer cells, MCF-7 and JEG-3, and showed that KIR2DL4 on LAD2 cells enhanced MMP-9 production and the invasive activity of both cell lines via HLA-G. Immunohistochemical analysis revealed that the direct interaction between HLA-G(+) breast cancer cells and KIR2DL4(+) tissue mast cells (observed in 12 of 36 cases; 33.3%) was statistically correlated with the presence of lymph node metastasis or lymph-vascular invasion (observed in 11 of 12 cases; 91.7%; χ(2) = 7.439; P < 0.01; degrees of freedom, 1) in the clinical samples. These findings suggest that the KIR2DL4 on human mast cells facilitates HLA-G-expressing cancer invasion and the subsequent metastasis.

Mast cell plasticity and sphingosine-1-phosphate in immunity, inflammation and cancer

Mast cells (MC) are found in all vascularized tissues at homeostasis and, until recently, were viewed only as effector cells of allergic reactions via degranulation, the canonical process through which MC release mediators, including histamine and pre-formed proteases and cytokines such as TNF. Cross-linking of IgE bound to surface high affinity receptors for IgE (FcɛRI) by a specific antigen (Ag) triggers signaling events leading to degranulation. We and others have reported the concomitant production and export of an influential multifaceted sphingolipid mediator, sphingosine-1-phosphate (S1P) transported outside of MC by ATP-binding cassettes (ABC) transporters, i.e., independently of degranulation. Indeed, the MC horizon expanded by the discovery of their unique ability to selectively release mediators depending upon the stimulus and receptors involved. Aside from degranulation and transporter usage, MC are also endowed with piecemeal degranulation, a slower process during which mediator release occurs with minor morphological changes. The broad spectrum of pro- and anti-inflammatory bioactive substances MC produce and release, their amounts and delivery pace render these cells bona fide fine-tuners of the immune response. In this viewpoint article, MC developmental, phenotypic and functional plasticity, its modulation by microRNAs and its relevance to immunity, inflammation and cancer will be discussed.

Mast cell function: a new vision of an old cell

Since first described by Paul Ehrlich in 1878, mast cells have been mostly viewed as effectors of allergy. It has been only in the past two decades that mast cells have gained recognition for their involvement in other physiological and pathological processes. Mast cells have a widespread distribution and are found predominantly at the interface between the host and the external environment. Mast cell maturation, phenotype and function are a direct consequence of the local microenvironment and have a marked influence on their ability to specifically recognize and respond to various stimuli through the release of an array of biologically active mediators. These features enable mast cells to act as both first responders in harmful situations as well as to respond to changes in their environment by communicating with a variety of other cells implicated in physiological and immunological responses. Therefore, the critical role of mast cells in both innate and adaptive immunity, including immune tolerance, has gained increased prominence. Conversely, mast cell dysfunction has pointed to these cells as the main offenders in several chronic allergic/inflammatory disorders, cancer and autoimmune diseases. This review summarizes the current knowledge of mast cell function in both normal and pathological conditions with regards to their regulation, phenotype and role.

The Role of Mast Cells in Molding the Tumor Microenvironment

Mast cells (MCs) are granulocytic immune cells that reside in tissues exposed to the external environment. MCs are best known for their activity in allergic reactions, but they have been involved in different physiological and pathological conditions. In particular, MC infiltration has been shown in several types of human tumors and in animal cancer models. Nevertheless, the role of MCs in the tumor microenvironment is still debated because they have been associated either to good or poor prognosis depending on tumor type and tissue localization. This dichotomous role relies on MC capacity to secrete a broad spectrum of molecules with modulatory functions, which may condition the final tumor outcome also promoting angiogenesis and tissue remodeling. In this review, we analyze the multifaceted role of mast cell in tumor progression and inhibition considering their ability to interact with: i) immune cells, ii) tumor cells and iii) the extracellular matrix. Eventually, the current MC targeting strategies to treat cancer patients are discussed. Deciphering the actual role of MCs in tumor onset and progression is crucial to identify MC-targeted treatments aimed at killing cancer cells or at making the tumor vulnerable to selected anti-cancer drugs.

TL1A increases expression of CD25, LFA-1, CD134 and CD154, and induces IL-22 and GM-CSF production from effector CD4 T-cells

Elevated levels of the cytokine TL1A is associated with several autoimmune diseases e.g. rheumatoid arthritis and inflammatory bowel disease. However, the exact role of TL1A remains elusive. In this study, we investigated the function of TL1A in a pro-inflammatory setting. We show that TL1A together with IL-12, IL-15 and IL-18 increases expression of the co-stimulatory molecules CD154 (CD40 ligand) and CD134 (OX40) on previously activated CD4+ T cells. This indicates that TL1A functions as a co-stimulatory molecule, decreasing the activation threshold of T-cells. We have previously shown that TL1A co-stimulation strongly induces IL-6 in human healthy leukocytes. Interestingly, the cytokine-activated effector T-cells did not produce IL-6 in response to TL1A, indicating distinct effects of TL1A on different cell populations. We further show that this co-stimulation increases the expression of CD25 (IL-2Rα) and CD11a (α-chain of LFA-1) on CD4 T-cells, likely governing increased IL-2/IL-15 sensitivity and cell-cell contact. Along with this, TL1A co-stimulation caused a specific induction of IL-22 and GM-CSF from the activated T-cells. These results substantially contribute to the explanation of TL1A's role in inflammation. Our results suggest that TL1A should be considered as a target for immunotherapeutic treatment of rheumatoid arthritis and inflammatory bowel disease.

MS4A Cluster in Alzheimer's Disease

Several variants within membrane-spanning 4-domains subfamily A (MS4A) gene cluster have recently been implicated the association of Alzheimer's disease (AD) by serial recent genome-wide association studies (GWAS). As cell membrane proteins, MS4A family members are found to participate in the regulation of calcium signaling which have been widely discussed in neurodegeneration and AD. Besides, although the MS4A family members are poorly characterized, an important role in immunity has already been identified for several members of this cluster (such as MS4A1, MS4A2, and MS4A4B), indicating the possible involvement of MS4A gene cluster in AD pathogenesis. In this article, we briefly summarize the structure, localization, and function of MS4A gene cluster, review recent genetic and expression findings concerning the association of MS4A gene cluster with AD pathogenesis, and also speculate the possible roles of MS4A gene cluster in this disease. Based on the contributing effects of MS4A gene cluster in AD pathogenesis, targeting MS4A gene cluster might provide new opportunities for AD treatment.

Rituximab modulates IL-17 expression in the salivary glands of patients with primary Sjögren's syndrome

OBJECTIVE

The aim of this study was to evaluate the role of rituximab (RTX) in modulating the expression of the IL-17/IL-23 pathway in the salivary glands (SGs) of patients with primary SS (pSS).

METHODS

Consecutive SG biopsies were obtained from 15 patients with pSS before and after 1 year of RTX therapy. The SG expression of IL-17, IL-23p19 and p-STAT3 was evaluated by immunohistochemistry at baseline and after RTX therapy. The role of mast cells in pSS patients in modulating the Th17 response and the immunologic effect of RTX on mast cells were also studied in in vitro experiments.

RESULTS

IL-17 was overexpressed in the SGs of patients with pSS mainly by infiltrating T cells and mast cells. After RTX therapy, the SG expression of IL-17, but not of IL-23p19 and p-STAT3, was significantly reduced and was accompanied by the depletion of tissue mast cells. In in vitro experiments with heterologous peripheral lymphocytes RTX significantly induced the apoptosis of isolated mast cells. Finally, mast cells isolated from peripheral blood mononuclear cells of pSS patients in vitro significantly increased Th17 lymphocytes.

CONCLUSION

RTX acts on pSS patients by globally reducing the expression of IL-17 and specifically inducing a pronounced apoptotic depletion of mast cells.

Current status of interleukin-10 and regulatory T-cells in cancer

PURPOSE OF REVIEW

Tumor growth elicits antigen-specific cytotoxic as well as immune suppressive responses. Interleukin-10 (IL-10) is a key immune-suppressive cytokine produced by regulatory T-cells and by helper T-cells. Here, we review pleiotropic functions of IL-10 that impact the immune pathology of cancer.

RECENT FINDINGS

The role of IL-10 in cancer has become less certain with the knowledge of its immune stimulatory functions. IL-10 is needed for T-helper cell functions, T-cell immune surveillance, and suppression of cancer-associated inflammation. By promoting tumor-specific immune surveillance and hindering pathogenic inflammation, IL-10 is emerging as a key cytokine in the battle of the host against cancer.

SUMMARY

IL-10 functions at the cross-roads of immune stimulation and immune suppression in cancer. Immunological mechanisms of action of IL-10 can be ultimately exploited to develop novel and effective cancer therapies.

Myeloid-derived cells are key targets of tumor immunotherapy

Tumors are composed of heterogeneous cell populations recruited by cancer cells to promote growth and metastasis. Among cells comprising the tumor stroma, myeloid-derived cells play pleiotropic roles in supporting tumorigenesis at distinct stages of tumor development. The tumor-infiltrating myeloid cell contingent is composed of mast cells, neutrophils, dendritic cells, macrophages, and myeloid-derived suppressor cells. Such cells are capable of evading the hostile tumor environment typically prone to immune cell destruction and can even promote angiogenesis, chronic inflammation, and invasion. This paper briefly summarizes the different myeloid-derived subsets that promote tumor development and the strategies that have been used to counteract the protumorigenic activity of these cells. These strategies include myeloid cell depletion, reduction of recruitment, and inactivation or remodeling of cell phenotype. Combining drugs designed to target tumor myeloid cells with immunotherapies that effectively trigger antitumor adaptive immune responses holds great promise in the development of novel cancer treatments.

Immune mediators of chronic pelvic pain syndrome

The cause of chronic pelvic pain syndrome (CPPS) has yet to be established. Since the late 1980s, cytokine, chemokine, and immunological classification studies using human samples have focused on identifying biomarkers for CPPS, but no diagnostically beneficial biomarkers have been identified, and these studies have done little to deepen our understanding of the mechanisms underlying chronic prostatic pain. Given the large number of men thought to be affected by this condition and the ineffective nature of current treatments, there is a pressing need to elucidate these mechanisms. Prostatitis types IIIa and IIIb are classified according to the presence of pain without concurrent presence of bacteria; however, it is becoming more evident that, although levels of bacteria are not directly associated with levels of pain, the presence of bacteria might act as the initiating factor that drives primary activation of mast-cell-mediated inflammation in the prostate. Mast cell activation is also known to suppress regulatory T cell (Treg) control of self-tolerance and also activate neural sensitization. This combination of established autoimmunity coupled with peripheral and central neural sensitization can result in the development of multiple symptoms, including pelvic pain and bladder irritation. Identifying these mechanisms as central mediators in CPPS offers new insight into the prospective treatment of the disease.

Mast cells as targets for immunotherapy of solid tumors

Mast cells have historically been studied mainly in the context of allergic disease. In recent years, we have come to understand the critical importance of mast cells in tissue remodeling events and their role as sentinel cells in the induction and development of effective immune responses to infection. Studies of the role of mast cells in tumor immunity are more limited. The pro-tumorigenic role of mast cells has been widely reported. However, mast cell infiltration predicts improved prognosis in some cancers, suggesting that their prognostic value may be dependent on other variables. Such factors may include the nature of local mast cell subsets and the various activation stimuli present within the tumor microenvironment. Experimental models have highlighted the importance of mast cells in orchestrating the anti-tumor events that follow immunotherapies that target innate immunity. Mast cells are long-lived tissue resident cells that are abundant around many solid tumors and are radiation resistant making them unique candidates for combined treatment modalities. This review will examine some of the key roles of mast cells in tumor immunity, with a focus on potential immunotherapeutic interventions that harness the sentinel role of mast cells.

Mast cells, basophils and B cell connection network

It has been proven that both resting and activated mast cells (MCs) and basophils are able to induce a significant increase in proliferation and survival of naïve and activated B cells, and their differentiation into antibody-producing cells. The immunological context in which this regulation occurs is of particular interest and the idea that these innate cells induce antibody class switching and production is increasingly gaining ground. This direct role of MCs and basophils in acquired immunity requires cell to cell contact as well as soluble factors and exosomes. Here, we review our current understanding of the interaction between B cells and MCs or basophils as well as the evidence supporting B lymphocyte-MC/basophil crosstalk in pathological settings. Furthermore, we underline the obscure aspects of this interaction that could serve as important starting points for future research in the field of MC and basophil biology in the peculiar context of the connection between innate and adaptive immunity.

Bone marrow stroma CD40 expression correlates with inflammatory mast cell infiltration and disease progression in splenic marginal zone lymphoma

Splenic marginal zone lymphoma (SMZL) is a mature B-cell neoplasm characterized by rather indolent clinical course. However, nearly one third of patients experience a rapidly progressive disease with a dismal outcome. Despite the characterization of clone genetics and the recognition of deregulated immunologic stimulation in the pathogenesis of SMZL, little is known about microenvironment dynamics and their potential biological influence on disease outcome. Here we investigate the effect of stroma-intrinsic features on SMZL disease progression by focusing on the microenvironment of the bone marrow (BM), which represents an elective disease localization endorsing diagnostic and prognostic relevance. We show that the quality of the BM stromal meshwork of SMZL infiltrates correlates with time to progression. In particular, we describe the unfavorable prognostic influence of dense CD40 expression by BM stromal cells, which involves the contribution of CD40 ligand (CD40L)-expressing bystander mast cells infiltrating SMZL BM aggregates. The CD40/CD40L-assisted crosstalk between mesenchymal stromal cells and mast cells populating the SMZL microenvironment finds correlation in p53(-/-) mice developing SMZL and contributes to the engendering of detrimental proinflammatory conditions. Our study highlights a dynamic interaction, playing between nonneoplastic elements within the SMZL niche, toward disease progression.

Inhibiting mast cell degranulation by HO-1 affects dendritic cell maturation in vitro

OBJECTIVE AND DESIGN

Mast cell (MC) degranulation can break peripheral immune tolerance. However, its mechanism remains unclear. Our goal was to study the stabilization of MC membranes by heme oxygenase-1 (HO-1) in order to influence dendritic cell (DC) function.

MATERIAL

Mast cells and dendritic cells were prepared from 8-week-old to 10-week-old C57BL/6 mice; spleen mononuclear cells (SMCs) were prepared from 8-week-old to 10-week-old C57BL/6 and Balb/c mice.

TREATMENT

Mast cells were pretreated with PBS, DMSO, Hemin (50 μl/ml), and Znpp (50 μl/ml) for 8 h.

METHOD

Real-time PCR and western-blot tested the HO-1 of MC mRNA and protein. The co-stimulatory molecules of DCs (CD80, CD86, CD40) were measured by flow cytometry, and levels of TNF-α, IL-6, and IFN-γ were measured by ELISA. We set up a one-way mixed lymphocyte reaction (MLR) model to test the proliferation of SMCs after MC/DC interaction. *P < 0.05 (t test) was taken as the level of statistical significance.

RESULT

MCs pretreated with hemin induced HO-1 mRNA and protein expression, then interacted with DCs; expression of the co-stimulatory molecules was attenuated. The TNF-α, IL-6, and IFN-γ levels in the co-culture system were decreased. These DCs couldn't stimulate the proliferation of SMCs.

CONCLUSION

Inhibiting MC degranulation by HO-1 restrained DC maturation and attenuated the proliferation of SMCs.

Modulation of FcεRI-dependent mast cell response by OX40L

OX40L is expressed by many cell types, including antigen presenting cells (APCs), T cells, vascular endothelial cells, mast cells (MCs), and natural killer cells. The importance of OX40L:OX40 interactions and the OX40L signaling is crucial for the homeostasis and for the modulation of the effector functions of the immune system. However, the lack of non-murine/non-IgG commercially available OX40L-triggering antibodies and the potential signal cross-contamination caused by the binding to the FcγRs co-expressed by several immune cells have limited the study of the OX40L-signaling cascade. We recently characterized the functions and described the molecular events, which follow the engagement of OX40L in MCs, by the use of the soluble OX40 molecule, able to mimic the regulatory T cell-driven engagement of MC-OX40L. This molecule enables signaling studies in MCs with any requirement for OX40-expressing cells. Using this unique reagent, we determined the modality and the extent by which the engagement of OX40L in MCs influences the IgE-dependent MC degranulation. This tool may find a potential application for signaling studies of other OX40L-expressing populations other than MCs, mainly APCs, with similar approaches we reported for the study of OX40L cascade.

Expression of RORγt marks a pathogenic regulatory T cell subset in human colon cancer

The role of regulatory T cells (T(regs)) in human colon cancer (CC) remains controversial: high densities of tumor-infiltrating T(regs) can correlate with better or worse clinical outcomes depending on the study. In mouse models of cancer, T(regs) have been reported to suppress inflammation and protect the host, suppress T cells and protect the tumor, or even have direct cancer-promoting attributes. These different effects may result from the presence of different T(reg) subsets. We report the preferential expansion of a T(reg) subset in human CC with potent T cell-suppressive, but compromised anti-inflammatory, properties; these cells are distinguished from T(regs) present in healthy donors by their coexpression of Foxp3 and RORγt. T(regs) with similar attributes were found to be expanded in mouse models of hereditary polyposis. Indeed, ablation of the RORγt gene in Foxp3(+) cells in polyp-prone mice stabilized T(reg) anti-inflammatory functions, suppressed inflammation, improved polyp-specific immune surveillance, and severely attenuated polyposis. Ablation of interleukin-6 (IL-6), IL-23, IL-17, or tumor necrosis factor-α in polyp-prone mice reduced polyp number but not to the same extent as loss of RORγt. Surprisingly, loss of IL-17A had a dual effect: IL-17A-deficient mice had fewer polyps but continued to have RORγt(+) T(regs) and developed invasive cancer. Thus, we conclude that RORγt has a central role in determining the balance between protective and pathogenic T(regs) in CC and that T(reg) subtype regulates inflammation, potency of immune surveillance, and severity of disease outcome.

The "missing link" in autoimmunity and autism: extracellular mitochondrial components secreted from activated live mast cells

Autoimmune diseases continue to increase, but the reason(s) remain obscure and infections have not proven to be major contributors. Mast cells are tissue immune cells responsible for allergies, but have been increasingly shown to be involved in innate and acquired immunity, as well as inflammation. This involvement is possible because of their ability to release multiple mediators in response to a great variety of triggers. We recently published that activation of mast cells is accompanied by mitochondrial fission and translocation to the cell surface from where they secrete at least ATP and DNA outside the cell without cell damage. These extracellular mitochondrial components are misconstrued by the body as "innate pathogens" leading to powerful autocrine and paracrine auto-immune/auto-inflammatory responses. We also showed that mitochondrial DNA is increased in the serum of young children with autism spectrum disorders (ASD), a condition that could involve "focal brain allergy/encephalitits". Blocking the secretion of extracellular mitochondrial components could present unique possibilities for the therapy of ASD and other autoimmune diseases. Unique formulation of the flavonoid luteolin offers unique advantages.

Direct effects of IL-4 on mast cells drive their intestinal expansion and increase susceptibility to anaphylaxis in a murine model of food allergy

Interleukin (IL)-4 has critical roles in allergic disorders, including food hypersensitivity. The direct effects of the cytokine on the survival and function of mast cells, the key effectors of food anaphylaxis, have not been established. In this study, we demonstrate that IL-4 induces a marked intestinal mastocytosis in mice. This phenotype is reproduced in animals expressing Il4rαF709, an activating variant of the IL-4 receptor α-chain (IL-4Rα). Il4rαF709 mice exhibit enhanced anaphylactic reactions but unaltered physiological responses to vasoactive mediators. IL-4 induces Bcl-2 and Bcl-X(L) and enhances survival and stimulates proliferation in cultured bone marrow-derived mast cells (BMMC). These effects are STAT6 (signal transducer and activator of transcription factor 6)-dependent and are amplified in Il4rαF709 BMMC. In competitive bone marrow chimeras, Il4rαF709 mast cells display a substantial competitive advantage over wild-type mast cells, which, in turn, prevail over IL-4Rα⁻/⁻ mast cells in populating the intestine, establishing a cell-intrinsic effect of IL-4 in intestinal mast cell homeostasis. Our results demonstrate that IL-4-signaling is a key determinant of mast cell expansion in food allergy.