Anti-CD40 Ab- or 8-oxo-dG-enhanced Treg cells reduce development of experimental autoimmune encephalomyelitis via down-regulating migration and activation of mast cells

Novel gene signatures predicting and immune infiltration analysis in Parkinson's disease: based on combining random forest with artificial neural network

BACKGROUND

Parkinson's disease (PD) ranks as the second most prevalent neurodegenerative disorder globally, and its incidence is rapidly rising. The diagnosis of PD relies on clinical characteristics. Although current treatments aim to alleviate symptoms, they do not effectively halt the disease's progression. Early detection and intervention hold immense importance. This study aimed to establish a new PD diagnostic model.

METHODS

Data from a public database were adopted for the construction and validation of a PD diagnostic model with random forest and artificial neural network models. The CIBERSORT platform was applied for the evaluation of immune cell infiltration in PD. Quantitative real-time PCR was performed to verify the accuracy and reliability of the bioinformatics analysis results.

RESULTS

Leveraging existing gene expression data from the Gene Expression Omnibus (GEO) database, we sifted through differentially expressed genes (DEGs) in PD and identified 30 crucial genes through a random forest classifier. Furthermore, we successfully designed a novel PD diagnostic model using an artificial neural network and verified its diagnostic efficacy using publicly available datasets. Our research also suggests that mast cells may play a significant role in the onset and progression of PD.

CONCLUSION

This work developed a new PD diagnostic model with machine learning techniques and suggested the immune cells as a potential target for PD therapy.

The Plasticity of Immune Cell Response Complicates Dissecting the Underlying Pathology of Multiple Sclerosis

Multiple sclerosis (MS) is a neurodegenerative autoimmune disease characterized by the destruction of the myelin sheath of the neuronal axon in the central nervous system. Many risk factors, including environmental, epigenetic, genetic, and lifestyle factors, are responsible for the development of MS. It has long been thought that only adaptive immune cells, especially autoreactive T cells, are responsible for the pathophysiology; however, recent evidence has indicated that innate immune cells are also highly involved in disease initiation and progression. Here, we compile the available data regarding the role immune cells play in MS, drawn from both human and animal research. While T and B lymphocytes, chiefly enhance MS pathology, regulatory T cells (Tregs) may serve a more protective role, as can B cells, depending on context and location. Cells chiefly involved in innate immunity, including macrophages, microglia, astrocytes, dendritic cells, natural killer (NK) cells, eosinophils, and mast cells, play varied roles. In addition, there is evidence regarding the involvement of innate-like immune cells, such as γδ T cells, NKT cells, MAIT cells, and innate-like B cells as crucial contributors to MS pathophysiology. It is unclear which of these cell subsets are involved in the onset or progression of disease or in protective mechanisms due to their plastic nature, which can change their properties and functions depending on microenvironmental exposure and the response of neural networks in damage control. This highlights the need for a multipronged approach, combining stringently designed clinical data with carefully controlled in vitro and in vivo research findings, to identify the underlying mechanisms so that more effective therapeutics can be developed.

Advances in immune checkpoint-based immunotherapies for multiple sclerosis: rationale and practice

Beyond the encouraging results and broad clinical applicability of immune checkpoint (ICP) inhibitors in cancer therapy, ICP-based immunotherapies in the context of autoimmune disease, particularly multiple sclerosis (MS), have garnered considerable attention and hold great potential for developing effective therapeutic strategies. Given the well-established immunoregulatory role of ICPs in maintaining a balance between stimulatory and inhibitory signaling pathways to promote immune tolerance to self-antigens, a dysregulated expression pattern of ICPs has been observed in a significant proportion of patients with MS and its animal model called experimental autoimmune encephalomyelitis (EAE), which is associated with autoreactivity towards myelin and neurodegeneration. Consequently, there is a rationale for developing immunotherapeutic strategies to induce inhibitory ICPs while suppressing stimulatory ICPs, including engineering immune cells to overexpress ligands for inhibitory ICP receptors, such as program death-1 (PD-1), or designing fusion proteins, namely abatacept, to bind and inhibit the co-stimulatory pathways involved in overactivated T-cell mediated autoimmunity, and other strategies that will be discussed in-depth in the current review. Video Abstract.

Regulatory T cell therapy for multiple sclerosis: Breaching (blood-brain) barriers

Multiple sclerosis (MS) is an autoimmune disorder causing demyelination and neurodegeneration in the central nervous system. MS is characterized by disturbed motor performance and cognitive impairment. Current MS treatments delay disease progression and reduce relapse rates with general immunomodulation, yet curative therapies are still lacking. Regulatory T cells (Tregs) are able to suppress autoreactive immune cells, which drive MS pathology. However, Tregs are functionally impaired in people with MS. Interestingly, Tregs were recently reported to also have regenerative capacity. Therefore, experts agree that Treg cell therapy has the potential to ameliorate the disease. However, to perform their local anti-inflammatory and regenerative functions in the brain, they must first migrate across the blood-brain barrier (BBB). This review summarizes the reported results concerning the migration of Tregs across the BBB and the influence of Tregs on migration of other immune subsets. Finally, their therapeutic potential is discussed in the context of MS.

Cladribine Alters Immune Cell Surface Molecules for Adhesion and Costimulation: Further Insights to the Mode of Action in Multiple Sclerosis

Cladribine (CLAD) is a deoxyadenosine analogue prodrug which is given in multiple sclerosis (MS) as two short oral treatment courses 12 months apart. Reconstitution of adaptive immune function following selective immune cell depletion is the presumed mode of action. In this exploratory study, we investigated the impact of CLAD tablets on immune cell surface molecules for adhesion (CAMs) and costimulation (CoSs) in people with MS (pwMS). We studied 18 pwMS who started treatment with CLAD and 10 healthy controls (HCs). Peripheral blood mononuclear cells were collected at baseline and every 3 months throughout a 24-month period. We analysed ICAM-1, LFA-1, CD28, HLADR, CD154, CD44, VLA-4 (CD49d/CD29), PSGL-1 and PD-1 with regard to their expression on B and T cells (T helper (Th) and cytotoxic T cells (cT)) and surface density (mean fluorescence intensity, MFI) by flow cytometry. The targeted analysis of CAM and CoS on the surface of immune cells in pwMS revealed a higher percentage of ICAM-1 (B cells, Th, cT), LFA-1 (B cells, cT), HLADR (B cells, cT), CD28 (cT) and CD154 (Th). In pwMS, we found lower frequencies of Th and cT cells expressing PSGL-1 and B cells for the inhibitory signal PD-1, whereas the surface expression of LFA-1 on cT and of HLADR on B cells was denser. Twenty-four months after the first CLAD cycle, the frequencies of B cells expressing CD44, CD29 and CD49d were lower compared with the baseline, together with decreased densities of ICAM-1, CD44 and HLADR. The rate of CD154 expressing Th cells dropped at 12 months. For cT, no changes were seen for frequency or density. Immune reconstitution by oral CLAD was associated with modification of the pro-migratory and -inflammatory surface patterns of CAMs and CoSs in immune cell subsets. This observation pertains primarily to B cells, which are key cells underlying MS pathogenesis.

An Update of Palmitoylethanolamide and Luteolin Effects in Preclinical and Clinical Studies of Neuroinflammatory Events

The inflammation process represents of a dynamic series of phenomena that manifest themselves with an intense vascular reaction. Neuroinflammation is a reply from the central nervous system (CNS) and the peripheral nervous system (PNS) to a changed homeostasis. There are two cell systems that mediate this process: the glia of the CNS and the lymphocites, monocytes, and macrophages of the hematopoietic system. In both the peripheral and central nervous systems, neuroinflammation plays an important role in the pathogenesis of neurodegenerative diseases, such as Parkinson’s and Alzheimer’s diseases, and in neuropsychiatric illnesses, such as depression and autism spectrum disorders. The resolution of neuroinflammation is a process that allows for inflamed tissues to return to homeostasis. In this process the important players are represented by lipid mediators. Among the naturally occurring lipid signaling molecules, a prominent role is played by the N-acylethanolamines, namely N-arachidonoylethanolamine and its congener N-palmitoylethanolamine, which is also named palmitoylethanolamide or PEA. PEA possesses a powerful neuroprotective and anti-inflammatory power but has no antioxidant effects per se. For this reason, its co-ultramicronization with the flavonoid luteolin is more efficacious than either molecule alone. Inhibiting or modulating the enzymatic breakdown of PEA represents a complementary therapeutic approach to treating neuroinflammation. The aim of this review is to discuss the role of ultramicronized PEA and co-ultramicronized PEA with luteolin in several neurological diseases using preclinical and clinical approaches.

Calming Down Mast Cells with Ketotifen: A Potential Strategy for Multiple Sclerosis Therapy?

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) characterized by extensive inflammation, demyelination, axonal loss and gliosis. Evidence indicates that mast cells contribute to immunopathogenesis of both MS and experimental autoimmune encephalomyelitis (EAE), which is the most employed animal model to study this disease. Considering the inflammatory potential of mast cells, their presence at the CNS and their stabilization by certain drugs, we investigated the effect of ketotifen fumarate (Ket) on EAE development. EAE was induced in C57BL/6 mice by immunization with MOG35-55 and the animals were injected daily with Ket from the seventh to the 17th day after disease induction. This early intervention with Ket significantly reduced disease prevalence and severity. The protective effect was concomitant with less NLRP3 inflammasome activation, rebalanced oxidative stress and also reduced T cell infiltration at the CNS. Even though Ket administration did not alter mast cell percentage at the CNS, it decreased the local CPA3 and CMA1 mRNA expression that are enzymes typically produced by these cells. Evaluation of the CNS-barrier permeability indicated that Ket clearly restored the permeability levels of this barrier. Ket also triggered an evident lymphadenomegaly due to accumulation of T cells that produced higher levels of encephalitogenic cytokines in response to in vitro stimulation with MOG. Altogether these findings reinforce the concept that mast cells are particularly relevant in MS immunopathogenesis and that Ket, a known stabilizer of their activity, has the potential to be used in MS control.

Protective effect of exogenous 8-oxo-2'-deoxyguanosine on Drosophila melanogaster larval stages under heat shock

The influence of exogenous 8-oxo-2'-deoxyguanosine on the development of Drosophila melanogaster under normal conditions, and under the influence of short-term heat shock was studied. It was shown that 8-oxo-2'-deoxyguanosine was not toxic at concentrations of up to 1 μM. A tendency to accelerate larval development and fly emergence was observed under the influence of this compound in our experiments. Short-term heat shock causes a 50-80% decrease in the number of larvae that complete development. The addition of exogenous 8-oxo-2'-deoxyguanosine to the food before thermal influence negates this effect and brings the levels of the imago emergence indicators back to the basal level. The obtained results are further evidence of the possible bioregulatory and adaptogen functions of 8-oxo-2'-deoxyguanosine.

A CD40 targeting peptide prevents severe symptoms in experimental autoimmune encephalomyelitis

CD40/CD154-interaction is critical in the development of Experimental Autoimmune Encephalomyelitis (EAE; mouse model of Multiple Sclerosis). Culprit CD4⁺CD40⁺ T cells drive a more severe form of EAE than conventional CD4 T cells. Blocking CD40/CD154-interaction with CD154-antibody prevents or ameliorates disease but had thrombotic complications in clinical trials. We targeted CD40 using a CD154-sequence based peptide. Peptides in human therapeutics demonstrate good safety. A small peptide, KGYY₆, ameliorates EAE when given as pretreatment or at first symptoms. KGYY₆ binds Th40 and memory T cells, affecting expression of CD69 and IL-10 in the CD4 T cell compartment, ultimately hampering disease development.

Oxidized Cell-Free DNA Role in the Antioxidant Defense Mechanisms under Stress

The present study focuses on the investigation of the oxidized cell-free DNA (cfDNA) properties in several experimental models, including cultured cerebellum cells, peripheral blood lymphocytes (PBL), plasma, and hippocampus under an acute and chronic unpredictable stress model in rats. Firstly, our study shows that Spectrum Green fluorescence-labeled oxidized cfDNA fragments were transferred into the cytoplasm of 80% of the cerebellum culture cells; meanwhile, the nonoxidized cfDNA fragments do not pass into the cells. Oxidized cfDNA stimulates the antioxidant mechanisms and induction of transcription factor NRF2 expression, followed by an activation of NRF2 signaling pathway genes-rise of Nrf2 and Hmox1 gene expression and consequently NRF2 protein synthesis. Secondly, we showed that stress increases plasma cfDNA concentration in rats corresponding with the duration of the stress exposure. At the same time, our study did not reveal any significant changes of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) level in PBL of rats under acute or chronic stress, probably due to the significantly increased Nrf2 expression, that we found in such conditions. 8-oxodG is one of the most reliable markers of DNA oxidation. We also found an increased level of 8-oxodG in the hippocampal homogenates and hippocampal dentate gyrus in rats subjected to acute and chronic stress. Taken together, our data shows that oxidized cfDNA may play a significant role in systemic and neuronal physiological mechanisms of stress and adaptation.

Identification of a Novel OX40L+ Dendritic Cell Subset That Selectively Expands Regulatory T cells

We have previously shown GM-CSF derived bone-marrow dendritic cells (G-BMDCs) can induce the selective expansion of Tregs through the surface-bound molecule OX40L; however, the physiological role of this ex vivo derived DC subset remained to be elucidated. We determined GM-CSF administration to mice induced the generation of in vivo derived OX40L⁺ DCs, phenotypically similar to ex vivo OX40L⁺G-BMDCs, in the spleen, brachial lymph nodes and liver. The generation of OX40L⁺ DCs correlated with increased percentages of functionally suppressive Tregs in the spleen, brachial lymph nodes, and liver of GM-CSF treated mice. DCs from GM-CSF treated mice expanded Tregs in CD4⁺ T-cell co-cultures in an OX40L dependent manner, suggesting OX40L⁺ DCs may play a role in peripheral Treg homeostasis. Furthermore, comparing the transcriptome data of OX40L⁺ DCs to that of all immune cell types revealed OX40L⁺ DCs to be distinct from steady-state immune cells and, microarray analysis of OX40L⁺G-BMDCs and OX40L⁻G-BMDCs revealed higher expression of molecules that are associated with tolerogenic phenotype and could play important roles in the function of OX40L⁺ DCs. These findings suggest that OX40L⁺ DCs may represent a unique DC subset induced under inflammatory conditions that may play an essential role in maintaining Treg homeostasis.

Inflammatory mediators resulting from transglutaminase 2 expressed in mast cells contribute to the development of Parkinson's disease in a mouse model

This study aimed to investigate the role of transglutaminase 2 (TG2) expressed in mast cells in substantia nigra (SN) in Parkinson's disease (PD) model or human PD patients. C57BL/6 mice received 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) by ip injection to induce PD. Bone marrow-derived mast cells (BMMCs) were adoptively transferred to TG2 knockout (KO or TG2^-/-) mice by iv injection 1 day before MPTP injection or stimulated by 1 methyl-4-phenylpyridinium (MMP⁺). KO-MPTP mice showed reduced expression of tyrosine hydroxylase (TH) and dopamine (DA) transporter (DAT) and loss of TH⁺ DA neurons, and expression of markers (c-kit, tryptase, FcεRI), mediators' release (histamine, leukotrienes, cytokines), and TG2 related to mast cells, and co-localization of DA neuronal cells and mast cells in SN tissues or release of mediators and TG2 activity in SN tissues and sera versus those in WT (wild type)-MPTP or BM + KO-MPTP mice. KO-MPTP mice reversed the alterations of behavior. KO-BMMCs-transferred KO-MPTP (BM + KO-MPTP) mice had restoration of all the responses versus the KO-MPTP mice. MPP⁺-stimulated BMMCs had increased mediators' release, which were inhibited by TG2 inhibitor (R2 peptide). All the mediators and TG2 activity were also increased in the sera of human PD patients. The data suggest that TG2 expressed in mast cells recruited into SN tissues might contribute to neuroinflammation, which is known as one of the important features in pathogenesis of PD, via up-regulating the release of various mediators.

Co-Stimulation-Impaired Bone Marrow-Derived Dendritic Cells Prevent Dextran Sodium Sulfate-Induced Colitis in Mice

Dendritic cells (DC) are important in the onset and severity of inflammatory bowel disease (IBD). Tolerogenic DC induce T-cells to become therapeutic Foxp3+ regulatory T-cells (Tregs). We therefore asked if experimental IBD could be prevented by administration of bone marrow-derived DC generated under conventional GM-CSF/IL-4 conditions but in the presence of a mixture of antisense DNA oligonucleotides targeting the primary transcripts of CD40, CD80, and CD86. These cell products (which we call AS-ODN BM-DC) have demonstrated tolerogenic activity in preventing type 1 diabetes and preserving beta cell mass in new-onset type 1 diabetes in the NOD mouse strain, in earlier studies. In addition to measuring efficacy in prevention of experimental IBD, we also sought to identify possible mechanism(s) of action. Weight, behavior, stool frequency, and character were observed daily for 7–10 days in experimental colitis in mice exposed to dextran sodium sulfate (DSS) following injection of the AS-ODN BM-DC. After euthanasia, the colons were processed for histology while spleen and mesenteric lymph nodes (MLNs) were made into single cells to measure Foxp3+ Treg as well as IL-10+ regulatory B-cell (Breg) population frequency by flow cytometry. AS-ODN BM-DC prevented DSS-induced colitis development. Recipients of these cells exhibited significant increases in Foxp3+ Treg and IL-10+ Breg in MLN and spleen. Histological examination of colon sections of colitis-free mice remained largely architecturally physiologic and mostly free of leukocyte infiltration when compared with DSS-treated animals. Although DSS colitis is mainly an innate immunity-driven condition, our study adds to the growing body of evidence showing that Foxp3+ Treg and IL-10 Bregs can suppress a mainly innate-driven inflammation. The already-established safety of human DC generated from monocytic progenitors in the presence of the mixture of antisense DNA targeting the primary transcripts of CD40, CD80, and CD86 in humans offers the potential to adapt them for clinical IBD therapy.

The CD40-CD40L Dyad in Experimental Autoimmune Encephalomyelitis and Multiple Sclerosis

The CD40-CD40L dyad is an immune checkpoint regulator that promotes both innate and adaptive immune responses and has therefore an essential role in the development of inflammatory diseases, including multiple sclerosis (MS). In MS, CD40 and CD40L are expressed on immune cells present in blood and lymphoid organs, affected resident central nervous system (CNS) cells, and inflammatory cells that have infiltrated the CNS. CD40-CD40L interactions fuel the inflammatory response underlying MS, and both genetic deficiency and antibody-mediated inhibition of the CD40-CD40L dyad reduce disease severity in experimental autoimmune encephalomyelitis (EAE). Both proteins are therefore attractive therapeutic candidates to modulate aberrant inflammatory responses in MS. Here, we discuss the genetic, experimental and clinical studies on the role of CD40 and CD40L interactions in EAE and MS and we explore novel approaches to therapeutically target this dyad to combat neuroinflammatory diseases.

Th40 cells (CD4+CD40+ Tcells) drive a more severe form of Experimental Autoimmune Encephalomyelitis than conventional CD4 T cells

CD40-CD154 interaction is critically involved in autoimmune diseases, and CD4 T cells play a dominant role in the Experimental Autoimmune Encephalomyelitis (EAE) model of Multiple Sclerosis (MS). CD4 T cells expressing CD40 (Th40) are pathogenic in type I diabetes but have not been evaluated in EAE. We demonstrate here that Th40 cells drive a rapid, more severe EAE disease course than conventional CD4 T cells. Adoptively transferred Th40 cells are present in lesions in the CNS and are associated with wide spread demyelination. Primary Th40 cells from EAE-induced donors adoptively transfer EAE without further in-vitro expansion and without requiring the administration of the EAE induction regimen to the recipient animals. This has not been accomplished with primary, non-TCR-transgenic donor cells previously. If co-injection of Th40 donor cells with Freund's adjuvant (CFA) in the recipient animals is done, the disease course is more severe. The CFA component of the EAE induction regimen causes generalized inflammation, promoting expansion of Th40 cells and infiltration of the CNS, while MOG-antigen shapes the antigen-specific TCR repertoire. Those events are both necessary to precipitate disease. In MS, viral infections or trauma may induce generalized inflammation in susceptible individuals with subsequent disease onset. It will be important to further understand the events leading up to disease onset and to elucidate the contributions of the Th40 T cell subset. Also, evaluating Th40 levels as predictors of disease onset would be highly useful because if either the generalized inflammation event or the TCR-honing can be interrupted, disease onset may be prevented.

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.

OX40 regulates pressure overload-induced cardiac hypertrophy and remodelling via CD4+ T-cells

OX40, which belongs to the tumour necrosis factor (TNF)-receptor family, is a costimulatory receptor that can potentiate T-cell receptor signalling on the surface of T-lymphocytes. The role of OX40 in non-immune systems, particularly the cardiovascular system, has not been defined. In the present study, we observed a noticeable increase in OX40 expression during cardiac remodelling in rodent heart. In the present study, cardiac hypertrophy was induced by aortic banding (AB) in OX40 knockout (KO) mice and wild-type (WT) mice. After 8 weeks, the OX40 KO mice showed significantly attenuated cardiac hypertrophy, fibrosis and inflammation as well as preserved cardiac function compared with the WT mice. Follow-up in vitro studies suggested that CD4⁺ T-lymphocyte proliferation and pro-inflammatory cytokine release were significantly decreased, whereas anti-inflammatory cytokine release was considerably increased in OX40 KO mice compared with WT mice as assessed by Cell Counting Kit-8 (CCK-8) assay and ELISA. Co-culturing neonatal rat cardiomyocytes with the activated supernatant of CD4⁺ T-lymphocytes from OX40 KO mice reduced the hypertrophy response. Interestingly, OX40 KO mice with reconstituted CD4⁺ T-lymphocytes presented deteriorated cardiac remodelling. Collectively, our data indicate that OX40 regulates cardiac remodelling via the modulation of CD4⁺ T-lymphocytes.

Translational utility of experimental autoimmune encephalomyelitis: recent developments

Multiple sclerosis (MS) is a complex autoimmune condition with firmly established genetic and environmental components. Genome-wide association studies (GWAS) have revealed a large number of genetic polymorphisms in the vicinity of, and within, genes that associate to disease. However, the significance of these single-nucleotide polymorphisms in disease and possible mechanisms of action remain, with a few exceptions, to be established. While the animal model for MS, experimental autoimmune encephalomyelitis (EAE), has been instrumental in understanding immunity in general and mechanisms of MS disease in particular, much of the translational information gathered from the model in terms of treatment development (glatiramer acetate and natalizumab) has been extensively summarized. In this review, we would thus like to cover the work done in EAE from a GWAS perspective, highlighting the research that has addressed the role of different GWAS genes and their pathways in EAE pathogenesis. Understanding the contribution of these pathways to disease might allow for the stratification of disease subphenotypes in patients and in turn open the possibility for new and individualized treatment approaches in the future.

Transglutaminase 2 expressed in mast cells recruited into skin or bone marrow induces the development of pediatric mastocytosis

BACKGROUND

Mastocytosis is characterized by a pathological increase in mast cells in organs such as skin and bone marrow. Transglutaminase 2 (TG2) expressed in mast cells contributes to allergic diseases, but its role in mastocytosis has not been investigated. This study aimed to investigate whether TG2 contributes to pediatric mastocytosis.

METHODS

Serum, various skin tissues or bone marrow (BM) biopsy and aspirates were obtained from pediatric normal control or patients with indolent systemic mastocytosis (SM), mastocytoma, and urticaria pigmentosa (UP). Tryptase, individual cytokines, leukotriene C4 (LTC4 ), and TG2 activity in the serum were determined by enzyme-linked immunosorbent assay, mast cell population by May-Grünwald-Giemsa, CD 117 by immunofluorescence, cell surface molecules by Western blot, and colocalization of c-kit and TG2 or IL-10-expressing cells, CD25, and FOXP3 by immunohistochemistry.

RESULTS

Infiltration of CD25(+) CD117(+) CD2(-) mast cells into BM and scalp/trunk/ear dermis; expression of FcεRI, tryptase, c-kit, FOXP3, CCL2/CCR2, and vascular cell adhesion molecule-1; and colocalization of c-kit and TG2 were enhanced in patient's skin tissues or BM, particularly SM, but colocalization of c-kit and IL-10-expressing cells was decreased vs. normal tissues. Amounts of LTC4 and inflammatory cytokines, expression of tryptase or TG2 activity were increased in patient's serum, BM aspirates, or ear/scalp skin tissues, respectively, vs. normal persons, but IL-10 level was decreased.

CONCLUSION

The data suggest that mast cells, recruited in the skin and BM by CCL2/CCR, may induce the development of pediatric mastocytosis through reducing IL-10 due to upregulating TG2 activity via transcription factor nuclear factor-κB. Thus, TG2 may be used in diagnosis of pediatric mastocytosis, particularly SM.

Mast cells promote blood brain barrier breakdown and neutrophil infiltration in a mouse model of focal cerebral ischemia

Blood brain barrier (BBB) breakdown and neuroinflammation are key events in ischemic stroke morbidity and mortality. The present study investigated the effects of mast cell deficiency and stabilization on BBB breakdown and neutrophil infiltration in mice after transient middle cerebral artery occlusion (tMCAo). Adult male C57BL6/J wild type (WT) and mast cell-deficient (C57BL6/J Kit(Wsh/Wsh) (Wsh)) mice underwent tMCAo and BBB breakdown, brain edema and neutrophil infiltration were examined after 4 hours of reperfusion. Blood brain barrier breakdown, brain edema, and neutrophil infiltration were significantly reduced in Wsh versus WT mice (P<0.05). These results were reproduced pharmacologically using mast cell stabilizer, cromoglycate. Wild-type mice administered cromoglycate intraventricularly exhibited reduced BBB breakdown, brain edema, and neutrophil infiltration versus vehicle (P<0.05). There was no effect of cromoglycate versus vehicle in Wsh mice, validating specificity of cromoglycate on brain mast cells. Proteomic analysis in Wsh versus WT indicated that effects may be via expression of endoglin, endothelin-1, and matrix metalloproteinase-9. Using an in vivo model of mast cell deficiency, this is the first study showing that mast cells promote BBB breakdown in focal ischemia in mice, and opens up future opportunities for using mice to identify specific mechanisms of mast cell-related BBB injury.

IgE and IgA produced by OX40-OX40L or CD40-CD40L interaction in B cells-mast cells re-activate FcεRI or FcαRI on mast cells in mouse allergic asthma

Mast cells are major effector cells of allergic diseases related to IgE. This study was undertaken to determine whether IgE or IgA, produced by CD40-CD40L or OX40-OX40L interactions between B cells and mast cells, re-activate FcεRI or FcαRI on mast cell surface. C57BL mice were sensitized and subjected to OVA challenge to induce asthma. Bone marrow-derived mast cells (BMMCs) and primary B cells were co-cultured. Mast cell recruitment into airways was stained by May-Grünwald Giemsa, the expression of markers or signaling molecules were determined by immunohistochemistry or Western blotting, and co-localization of B cells and mast cells by immunofluorescence. Anti-CD40 plus anti-OX40L Abs synergistically reduced IgE and IgA production, and mediators (histamine, LTs and cytokines) released in mast cells, and additively reduced other responses, such as, numbers of mast cells, the expression of markers (tryptase, mMCP5, B220 and CD19), surface molecules (CD40, CD40L, OX40 and OX40L), FcεRI or FcαRI and the co-localization of BMMCs and B cells, and IgE- or IgA-producing cells, as compared with individual blocking Ab treatment which reducedresponses in BAL cells or lung tissues of OVA-challenged mice or in co-culture of B and mast cells. The data suggest that IgE and IgA, produced by OX40-OX40L or CD40-CD40L interaction between B cells and mast cells, may re-activate receptors of FCεRI and FcαRI on mast cell surfaces, followed by more mediator release, and furthermore, that treatment with anti-CD40 plus anti-OX40L Abs offers a potential treatment for allergic asthma.

CD4(+)Foxp3(+) Tregs protect against innate immune cell-mediated fulminant hepatitis in mice

Foxp3(+) Tregs play important roles in maintaining homeostasis by suppressing excessive immune responses that result in serious tissue damage; yet, it is largely unknown about the impact of Tregs on innate immune cells in hepatitis models in vivo. In this study, we examined the effect of hepatic Tregs on innate immune-mediated liver injury by using the murine model of polyI:C and d-galactosamine (d-GalN)-induced hepatitis. Administration of polyI:C/d-GalN increased the number of CD4(+)Foxp3(+) Tregs in the liver. Depletion of Tregs leaded to higher levels of proinflammatory cytokine expression and severer liver injury, whereas adoptive transfer of Foxp3(+) Tregs attenuated liver injury in polyI:C/d-GalN-treated mice. In addition, depletion of Tregs leaded to a reduction in TGF-β and IL-10 expression in polyI:C/d-GalN-treated mice. Both of these cytokines were important for suppression of polyI:C/d-GalN-induced liver injury. TGF-β was derived from Tregs. IL-10 was derived from active Kupffer cells, and coincubation of Kupffer cells with Tregs increased IL-10 secretion. Furthermore, TGF-β blockade abrogated Treg-mediated suppression of proinflammatory cytokine production by innate immune cell in vitro.

CONCLUSION

CD4(+)Foxp3(+) Tregs modify innate immune responses in polyI:C/d-GalN-induced fulminant hepatitis via producing TGF-β and enhancing IL-10 secretion by Kupffer cells.

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.

CD1d expressed in mast cell surface enhances IgE production in B cells by up-regulating CD40L expression and mediator release in allergic asthma in mice

Mast cells play important roles via FcεRI-mediated activation in allergic asthma. A nonpolymorphic MHC I-like molecule CD1d, which is mainly expressed in APCs, presents glycolipid Ag to iTCR on iNKT cells and modulates allergic responses. This study aimed to investigate the role of CD1d on IgE production and mast cell activation related to allergic asthma. Bone marrow-derived mast cells (BMMCs) from C57BL/6 Wild type (WT) or KO (CD1d(-/-)) mice were activated with Ag/Ab (refer to WT-act-BMMCs and KO-act-BMMCs, respectively) or α-Galactosylceramide (WT-αGal-BMMCs, KO-αGal-BMMCs) in the presence of iNKT cells. WT, KO or BMMC-transferred KO mice were sensitized and/or challenged by OVA or α-Gal to induce asthma. KO-act-BMMCs reduced intracellular Ca(2+) levels, expression of signaling molecules (Ras, Rac1/2, PLA2, COX-2, NF-κB/AP-1), mediator release (histamines, leukotrienes and cytokines/chemokines), and total IgE levels versus the corresponding WT-BMMCs. KO mice reduced total and OVA-specific serum IgE levels, number of mast cells, recruiting molecules (CCR2/CCL2, VCAM-1, PECAM-1), expression of tryptase, c-kit, CD40L and cytokine mRNA, co-localization of c-kit and CD1d or iNKT cells in BAL cells or lung tissues, and PCA responses, compared with the corresponding WT mice. BMMC-transferred KO-both mice showed the restoration of all allergic responses versus KO-both mice (Ag/Ab reaction plus α-Gal). KO-αGal-BMMCs or KO-αGal mice did not show any responses. Our data suggest that CD1d-expressed mast cells may function as APC cells for iNKT cells and exacerbate airway inflammation and remodeling through up-regulating IgE production via B cell Ig class switching and mediator release in mast cells of OVA-challenged mice.

IgE Generation and Mast Cell Activation

IgE is an important marker for allergy and plays a central role in the induction of allergic diseases through its binding of the high affinity receptor on mast cells. Mast cells can influence B cell survival, proliferation and differentiation into CD138+cells. Among TH2 cytokines, interleukin (IL)-4 and IL-13 are responsible for class-switching in B cells which resolves in production of allergen-specific IgE antibodies that bind to specific receptor on mast cells. IgE synthesis by B cells is regulated by CD40 ligand, IL-4 and interferon-gamma, therefore inhibition of B cell antigen-specific IgE may prevent the cleavage of CD23 from B cells, having a therapeutic impact which also includes the removal of circulating free IgE, omalizumab, corticosteroids, mast cell stabilizers, leukotriene receptor antagonist, and others. B cell differentiation into IgE-producing cells requires two signals provided by TH2 cells and IL-4, however IL-4, IL-1 and IL-10 as well as several hormones are critical for the development of TH2 cells, while cytokines, such as interferon (IFN)-alpha, IFN-gamma, IL-12 and transforming growth factor (TGF)-beta play a negative role. However, the exact mechanism of this process has not yet been defined.