Interleukin (IL)-10 inhibits long-term IL-6 production but not preformed mediator release from rat peritoneal mast cells

IL-10 Modulates the Expression and Activation of Pattern Recognition Receptors in Mast Cells

Mast cells (MCs) are involved in several immune-related responses, including those in bacterial infections, autoimmune diseases, inflammatory bowel diseases, and cancer, among others. MCs identify microorganisms by pattern recognition receptors (PRRs), activating a secretory response. Interleukin (IL)-10 has been described as an important modulator of MC responses; however, its role in PRR-mediated activation of MC is not fully understood. We analyzed the activation of TLR2, TLR4, TLR7 and Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) in mucosal-like MCs (MLMCs) and peritoneum-derived cultured MCs (PCMCs) from IL-10^-/- and wild-type (WT) mice. IL-10^-/- mice showed a reduced expression of TLR4 and NOD2 at week 6 and TLR7 at week 20 in MLMC. In MLMC and PCMC, TLR2 activation induced a reduced secretion of IL-6 and TNFα in IL-10^-/- MCs. TLR4- and TLR7-mediated secretion of IL-6 and TNFα was not detected in PCMCs. Finally, no cytokine release was induced by NOD2 ligand, and responses to TLR2 and TLR4 were lower in MCs at 20 weeks. These findings indicate that PRR activation in MCs depends on the phenotype, ligand, age, and IL-10.

Cadmium exposure caused cardiotoxicity in common carps (Cyprinus carpio L.): miR-9-5p, oxidative stress, energetic impairment, mitochondrial division/fusion imbalance, inflammation, and autophagy

Cadmium (Cd), a toxic heavy metal pollutant, is a threat to human and eatable fish health. Common carps are widely cultivated and eaten by humans. However, there are no reports about Cd-damaged common carp hearts. Our experiment attempted to investigate the cardiotoxicity of Cd to common carps by establishing a common carp Cd exposure model. Our results showed that Cd injured hearts. Moreover, Cd treatment induced autophagy via miR-9-5p/Sirt1/mTOR/ULK1 pathway. Cd exposure caused oxidant/antioxidant imbalance and oxidative stress; and led to energetic impairment. Energetic impairment partook in oxidative stress-mediated autophagy through AMPK/mTOR/ULK1 pathway. Furthermore, Cd caused mitochondrial division/fusion imbalance and resulted in inflammatory injury via NF-κB-COX-2-PTGEs and NF-κB-COX-2-TNF-α pathways. Oxidative stress mediated mitochondrial division/fusion imbalance, further induced inflammation and autophagy via OPA1/NF-κB-COX-2-TNF-α-Beclin1 and OPA1/NF-κB-COX-2-TNF-α/P62 pathways under Cd treatment. Taken together, miR-9-5p, oxidative stress, energetic impairment, mitochondrial division/fusion imbalance, inflammation, and autophagy participated in the mechanism of Cd-cardiotoxicity to common carps. Our study revealed harmful effect of Cd on hearts, and provided new information for researches of environmental pollutant toxicity.

Hepatic enzymes and immunoinflammatory response to Bio-C Temp bioceramic intracanal medication implanted into the subcutaneous tissue of rats

Our purpose was to evaluate the biocompatibility and hepatotoxicity of a new bioceramic intracanal medicament, Bio-C Temp (BIO). The biological properties of BIO were compared with calcium hydroxide-based intracanal medicament (Calen; CAL), used as gold pattern. Polyethylene tubes filled with BIO or CAL, and empty tubes (control group, CG) were implanted into subcutaneous tissue of rats. After 7, 15, 30 and 60 days, the samples were embedded in paraffin for morphological, quantitative and immunohistochemistry analyses. At 7 and 60 days, blood samples were collected for analysis of serum glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) levels. The data were submitted to two-way ANOVA and Tukey’s test (p ≤ 0.05). No significant difference was detected in serum GOT and GPT levels among BIO, CAL and CG specimens. In all periods, BIO specimens exhibited lower number of inflammatory cells and immunoexpression of IL-6, a pro-inflammatory cytokine, than CAL specimens. The reduction of these parameters was accompanied by significant increase in the collagen content and in the immunoexpression of IL-10, a cytokine involved in the tissue repair, over time. Our findings indicate that Bio-C Temp is biocompatible and had no hepatotoxicity effect.

Suppression function against environmental dust exposure after Dermatophagoides pteronyssinus immunotherapy is associated with production of specific and cross-reactive immunoglobulin G4

BACKGROUND

Whether Dermatophagoides pteronyssinus (Der-p) allergen immunotherapy (AIT) can induce Dermatophagoides farina (Der-f) specific immunoglobulin (sIg) G4 production and tolerance to environmental allergens has not been fully investigated.

OBJECTIVE

We aimed to determine serum Der-p-sIgG4 and Der-f-sIgG4 levels in asthma and/or rhinitis patients undergoing Der-p AIT and their ability to reduce immune responses triggered by indoor-dust extracts.

METHODS

We performed a real-world prospective trial and enrolled patients with allergic rhinitis and/or asthma in Guangzhou, China. These patients received either Der-p AIT (SCIT group) or routine medications (non-SCIT group) for 156 weeks. Clinical outcomes were assessed by the combined symptom medication score (SMS) and FEV₁ % changes. House dust samples were collected to analyze allergen levels. Serum levels of Der-p-sIgG4 and Der-f-sIgG4, serum inhibitory capacity against Der-p, Der-f, and indoor dust extract by sIgE-facilitated allergen binding to B cells (IgE-FAB), and serum blocking indoor dust extract-induced basophil activation inhibition assays (BATI) in peripheral blood monocytes were carried out at weeks 0, 4, 12, 16, 52, 104, and 156 after the initiations of the treatments.

RESULTS

Our study enrolled a total of 60 participants, with 30 patients in each group. Patients in the SCIT group had significantly improved SMS when compared with the baseline and the patients in the non-SCIT group. Median levels of Der-p 1 and Der-f 1 in indoor dust extract were 1.86 μg/g and 4.74 μg/g, respectively. Serum Der-p-sIgG4 and Der-f-IgG4 levels in SCIT patients showed a significant increase from week 12 to week 156. Serum in these SCIT patients could significantly block Der-p, Der-f, and indoor dust extract formation of allergen-sIgE complex and reduced the threshold of IgE-FAB from 16 weeks after the initiation of the treatment. The capacity to inhibit Der-p, Der-f, and indoor dust extract BATI was observed in SCIT serum after 12 weeks. Der-p-sIgG4 and Der-f-sIgG4 had a significant correlation with IgE-FAB and BATI in SCIT patients at all time points.

CONCLUSION

Single Der-p immunotherapy induced both Der-p-sIgG4 and Der-f-sIgG4 production, which might cross-reactively induce tolerance against environmental allergen exposure in patients with asthma and/or rhinitis.

Alternative Splicing of Human Telomerase Reverse Transcriptase (hTERT) and Its Implications in Physiological and Pathological Processes

Alternative splicing (AS) of human telomerase catalytic subunit (hTERT, human telomerase reverse transcriptase) pre-mRNA strongly regulates telomerase activity. Several proteins can regulate AS in a cell type-specific manner and determine the functions of cells. In addition to being involved in telomerase activity regulation, AS provides cells with different splice variants that may have alternative biological activities. The modulation of telomerase activity through the induction of hTERT AS is involved in the development of different cancer types and embryos, and the differentiation of stem cells. Regulatory T cells may suppress the proliferation of target human and murine T and B lymphocytes and NK cells in a contact-independent manner involving activation of TERT AS. This review focuses on the mechanism of regulation of hTERT pre-mRNA AS and the involvement of splice variants in physiological and pathological processes.

IL-10 in Mast Cell-Mediated Immune Responses: Anti-Inflammatory and Proinflammatory Roles

Mast cells (MCs) play critical roles in Th2 immune responses, including the defense against parasitic infections and the initiation of type I allergic reactions. In addition, MCs are involved in several immune-related responses, including those in bacterial infections, autoimmune diseases, inflammatory bowel diseases, cancers, allograft rejections, and lifestyle diseases. Whereas antigen-specific IgE is a well-known activator of MCs, which express FcεRI on the cell surface, other receptors for cytokines, growth factors, pathogen-associated molecular patterns, and damage-associated molecular patterns also function as triggers of MC stimulation, resulting in the release of chemical mediators, eicosanoids, and various cytokines. In this review, we focus on the role of interleukin (IL)-10, an anti-inflammatory cytokine, in MC-mediated immune responses, in which MCs play roles not only as initiators of the immune response but also as suppressors of excessive inflammation. IL-10 exhibits diverse effects on the proliferation, differentiation, survival, and activation of MCs in vivo and in vitro. Furthermore, IL-10 derived from MCs exerts beneficial and detrimental effects on the maintenance of tissue homeostasis and in several immune-related diseases including contact hypersensitivity, auto-immune diseases, and infections. This review introduces the effects of IL-10 on various events in MCs, and the roles of MCs in IL-10-related immune responses and as a source of IL-10.

Synergistic inflammatory signaling by cGAS may be involved in the development of atherosclerosis

Inappropriate activation or overactivation of cyclic GMP-AMP synthase (cGAS) by double-stranded deoxyribonucleic acid (dsDNA) initiates a regulatory signaling cascade triggering a variety of inflammatory responses, which are a great threat to human health. This study focused on identifying the role of cGAS in atherosclerosis and its potential mechanisms. The relationship between cGAS and atherosclerosis was identified in an ApoE ^-/- mouse model. Meanwhile, RNA sequencing (RNA-seq) analysis of the underlying mechanisms of atherosclerosis in RAW264.7 macrophages treated with cGAS inhibition was conducted. Results showed that cGAS was positively correlated with atherosclerotic plaque area, and was mainly distributed in macrophages. RNA-seq analysis revealed that inflammatory response, immune response and cytokine–cytokine receptor interaction may play important roles in the development of atherosclerosis. Real-time quantitative polymerase chain reaction (RT-qPCR) results showed that the expression of the pro-inflammatory factors, signal transducer and activator of transcription (Stat), interferon regulatory factor (Irf), toll-like receptors (Tlrs), and type I interferons (Ifns) were synergistically reduced when cGAS was inhibited. Furthermore, cGAS inhibition significantly inhibited RAW264.7 macrophage M1 polarization. These results demonstrate that cGAS may contribute to the development of atherosclerosis through synergistic inflammatory signaling of TLRs, STAT/IRF as well as IFNs, leading to macrophage M1 polarization.

Intraperitoneal Phototherapy Suppresses Inflammatory Reactions in a Surgical Model of Peritonitis

BACKGROUND

Standard treatment for diffuse peritonitis due to colorectal perforation may be insufficient to suppress inflammatory reaction in sepsis. Thus, developing new treatments is important. This study aimed to examine whether intraperitoneal irradiation by artificial sunlight suppresses inflammatory reaction in a lipopolysaccharide (LPS)-induced peritonitis model after surgical treatments.

MATERIALS AND METHODS

Mice were divided into naive, nontreatment (NT), and phototherapy (PT) groups. In the latter two groups, LPS was intraperitoneally administered to induce peritonitis and removed by intraperitoneal lavage after laparotomy. The PT group was irradiated with artificial sunlight intraperitoneally. We evaluated the local and systemic inflammatory reactions. Murine macrophages were irradiated with artificial sunlight after stimulation by LPS, and cell viability and expression of tumor necrotizing factor-α (TNF-α) were evaluated.

RESULTS

As a local inflammatory reaction, the whole cell count, the expression of interleukin-6 and TNF-α in the intra-abdominal fluid, and the peritoneal thickness were significantly lower in the PT group than in the NT group. As a systematic inflammatory reaction, the expression of serum TNF-α, granulocyte macrophage colony-stimulating factor, monocyte chemotactic protein-1, macrophage inflammatory protein (MIP)-1α, and MIP-1β were significantly lower in the PT group than in the NT group. Irradiation by artificial sunlight suppressed the expression of TNF-α in murine macrophages without affecting cell viability.

CONCLUSIONS

Intraperitoneal irradiation by artificial sunlight could suppress local and systemic inflammatory reactions in the LPS-induced peritonitis murine model. These effects may be associated with macrophage immune responses.

Imidacloprid exposure suppresses cytokine production and neutrophil infiltration in TLR2-dependent activation of RBL-2H3 cells and skin inflammation of BALB/c mice

Imidacloprid suppressed TNF-α and IL-6 production and neutrophil infiltration, without altering mast cell degranulation.

Progesterone decreases gut permeability through upregulating occludin expression in primary human gut tissues and Caco-2 cells

Progesterone plays a protective role in preventing inflammation and preterm delivery during pregnancy. However, the mechanism involved is unknown. Microbial product translocation from a permeable mucosa is demonstrated as a driver of inflammation. To study the mechanism of the protective role of progesterone during pregnancy, we investigated the effect of physiologic concentrations of progesterone on tight junction protein occludin expression and human gut permeability in vitro and systemic microbial translocation in pregnant women in vivo. Plasma bacterial lipopolysaccharide (LPS), a representative marker of in vivo systemic microbial translocation was measured. We found that plasma LPS levels were significantly decreased during 24 to 28 weeks of gestation compared to 8 to 12 weeks of gestation. Moreover, plasma LPS levels were negatively correlated with plasma progesterone levels but positively correlated with plasma tumor necrosis factor-alpha (TNF-α) levels at 8 to 12 weeks of gestation but not at 24 to 28 weeks of gestation. Progesterone treatment increased intestinal trans-epithelial electrical resistance (TEER) in primary human colon tissues and Caco-2 cells in vitro through upregulating tight junction protein occludin expression. Furthermore, progesterone exhibited an inhibitory effect on nuclear factor kappa B (NF-κB) activation following LPS stimulation in Caco-2 cells. These results reveal a novel mechanism that progesterone may play an important role in decreasing mucosal permeability, systemic microbial translocation, and inflammation during pregnancy.

Mast cells as sources of cytokines, chemokines, and growth factors

Mast cells are hematopoietic cells that reside in virtually all vascularized tissues and that represent potential sources of a wide variety of biologically active secreted products, including diverse cytokines and growth factors. There is strong evidence for important non-redundant roles of mast cells in many types of innate or adaptive immune responses, including making important contributions to immediate and chronic IgE-associated allergic disorders and enhancing host resistance to certain venoms and parasites. However, mast cells have been proposed to influence many other biological processes, including responses to bacteria and virus, angiogenesis, wound healing, fibrosis, autoimmune and metabolic disorders, and cancer. The potential functions of mast cells in many of these settings is thought to reflect their ability to secrete, upon appropriate activation by a range of immune or non-immune stimuli, a broad spectrum of cytokines (including many chemokines) and growth factors, with potential autocrine, paracrine, local, and systemic effects. In this review, we summarize the evidence indicating which cytokines and growth factors can be produced by various populations of rodent and human mast cells in response to particular immune or non-immune stimuli, and comment on the proven or potential roles of such mast cell products in health and disease.

IL-10 Receptor or TGF-β Neutralization Abrogates the Protective Effect of a Specific Nondigestible Oligosaccharide Mixture in Cow-Milk-Allergic Mice

Background

Dietary nondigestible, short-chain galacto-, long-chain fructo-, and pectin-derived acidic oligosaccharides (GFAs) lower the effector response in cow-milk-allergic (CMA) mice; and forkhead box P3 (Foxp3)-positive regulatory T cells (Tregs) were shown to contribute to this.

Objective

The aim of this study was to assess the contribution of interleukin 10 (IL-10) and transforming growth factor β (TGF-β) to the protective effect of the GFA diet in CMA mice.

Methods

Female C3H/HeOuJ mice, 3-4 wk old, were orally sensitized with cholera toxin (Sham) or whey and cholera toxin (Whey) 1 time/wk for 5 consecutive weeks and challenged with whey 1 wk later. The mice were fed a control or 1% GFA (9:2:1) (Whey+GFA) diet starting 2 wk before the first sensitization. In a second experiment, the mice were also injected with αIL-10 receptor (αIL-10r), αTGF-β, or isotype control antibodies 24 h before each sensitization. The acute allergic skin response, anaphylaxis score, whey-specific IgE, mucosal mast cell protease 1 (mMCP-1), and Treg frequency in the mesenteric lymph nodes (MLNs) and intestinal Foxp3, Il10, and Tgfb mRNA expression were determined.

Results

In Whey+GFA mice, intestinal Il10, Tgfb, or Foxp3 mRNA expression was 2-10 times higher (P < 0.05) and the MLN Treg frequency was 25% higher compared with Whey mice (P < 0.05). The acute allergic skin response was 50% lower in Whey+GFA mice compared with Whey mice (P < 0.01), and IL-10 receptor (IL-10r) or TGF-β neutralizing antibodies prevented this protective effect (P < 0.001). The Whey mice had higher serum mMCP-1 concentrations and whey-immunoglobulin E (-IgE) levels than Sham mice (P < 0.01), whereas these were not higher in Whey+GFA mice, and neutralizing antibodies partially interfered with these responses.

Conclusions

Dietary GFAs enhance the Treg frequency in the MLNs and mucosal IL-10 and TGF-β transcription while suppressing the allergic effector response. Neutralizing antibodies showed that the allergy-protective effect of the GFA diet was mediated by IL-10 and TGF-β in CMA mice.

Contact-independent suppressive activity of regulatory T cells is associated with telomerase inhibition, telomere shortening and target lymphocyte apoptosis

Regulatory T cells (Tregs) play a fundamental role in the maintenance of immunological tolerance by suppressing effector target T, B and NK lymphocytes. Contact-dependent suppression mechanisms have been well-studied, though contact-independent Treg activity is not fully understood. In the present study, we showed that human native Tregs, as well as induced ex vivo Tregs, can cause in vitro telomere-dependent senescence in target T, B and NK cells in a contact-independent manner. The co-cultivation of target cells with Tregs separated through porous membranes induced alternative splicing of the telomerase catalytic subunit hTERT (human Telomerase Reverse Transcriptase), which suppressed telomerase activity. Induction of the hTERT splicing variant was associated with increased expression of the apoptotic endonuclease EndoG, a splicing regulator. Inhibited telomerase in target cells co-cultivated with Tregs for a long period of time led to a decrease in their telomere lengths, cell cycle arrest, conversion of the target cells to replicative senescence and apoptotic death. Induced Tregs showed the ability to up-regulate EndoG expression, TERT alternative splicing and telomerase inhibition in mouse T, B and NK cells after in vivo administration. The results of the present study describe a novel mechanism of contact-independent Treg cell suppression that induces telomerase inhibition through the EndoG-provoked alternative splicing of hTERT and converts cells to senescence and apoptosis phenotypes.

Murine regulatory T cells induce death of effector T, B, and NK lymphocytes through a contact-independent mechanism involving telomerase suppression and telomere-associated senescence

Regulatory T cells (Tregs) suppress the activity of effector T, B and NK lymphocytes and sustain immunological tolerance, but the proliferative activity of suppressed cells remains unexplored. In the present study, we report that mouse Tregs can induce replicative senescence and the death of responder mouse CD4⁺CD25^- T cells, CD8⁺ T cells, B cells and NK cells in vitro and in vivo. Contact-independent in vitro co-cultivation with Tregs up-regulated endonuclease G (EndoG) expression and its translocation to the nucleus in responder cells. EndoG localization in the nucleus induced alternative mRNA splicing of the telomerase catalytic subunit Tert and telomerase inhibition. The lack of telomerase activity in proliferating cells led to telomere loss followed by the development of senescence and cell death. Injection of Tregs into mice resulted in EndoG-associated alternative splicing of Tert, telomerase inhibition, telomere loss, senescence development and increased cell death in vivo. The present study describes a novel contact-independent mechanism by which Tregs specify effector cell fate and provides new insights into cellular crosstalk related to immune suppression.

Controlling Mast Cell Activation and Homeostasis: Work Influenced by Bill Paul That Continues Today

Mast cells are tissue resident, innate immune cells with heterogenous phenotypes tuned by cytokines and other microenvironmental stimuli. Playing a protective role in parasitic, bacterial, and viral infections, mast cells are also known for their role in the pathogenesis of allergy, asthma, and autoimmune diseases. Here, we review factors controlling mast cell activation, with a focus on receptor signaling and potential therapies for allergic disease. Specifically, we will discuss our work with FcεRI and FγR signaling, IL-4, IL-10, and TGF-β1 treatment, and Stat5. We conclude with potential therapeutics for allergic disease. Much of these efforts have been influenced by the work of Bill Paul. With many mechanistic targets for mast cell activation and different classes of therapeutics being studied, there is reason to be hopeful for continued clinical progress in this area.

Immunoglobulin G; structure and functional implications of different subclass modifications in initiation and resolution of allergy

IgE and not IgG is usually associated with allergy. IgE lodged on mast cells in skin or gut and basophils in the blood allows for the prolonged duration of allergy through the persistent expression of high affinity IgE receptors. However, many allergic reactions are not dependent on IgE and are generated in the absence of allergen specific and even total IgE. Instead, IgG plasma cells are involved in induction of, and for much of the pathogenesis of, allergic diseases. The pattern of IgG producing plasma cells in atopic children and the tendency for direct or further class switching to IgE are the principle factors responsible for long-lasting sensitization of mast cells in allergic children. Indirect class switching from IgG producing plasma cells has been shown to be the predominant pathway for production of IgE while a Th2 microenvironment, genetic predisposition, and the concentration and nature of allergens together act on IgG plasma cells in the atopic tendency to undergo further immunoglobulin gene recombination. The seminal involvement of IgG in allergy is further indicated by the principal role of IgG4 in the natural resolution of allergy and as the favourable immunological response to immunotherapy. This paper will look at allergy through the role of different antibodies than IgE and give current knowledge of the nature and role of IgG antibodies in the start, maintenance and resolution of allergy.

Inflammation in Respiratory Allergy Treated by Sublingual Immunotherapy

The most common allergic diseases, such as rhinitis, asthma and atopic dermatitis, are sustained by allergic inflammation, the treatment of which requires anti-inflammatory activity. Among the available treatments, allergen immunotherapy (IT) has a documented impact on allergic inflammation which persists after its discontinuation and modifies the natural course of allergy. The anti-inflammatory effects of IT, and particularly of sublingual IT (SLIT), are based on the ability to modify the phenotype of T cells which, in allergic subjects, are characterized by a prevalence of the Th2 type, with production of IL-4, IL-5, IL-13, IL-17, and IL-32 cytokines. IT-induced changes result in a Th1-type response (immune deviation) related to an increased IFN-gamma and IL-2 production or in a Th2 reduced activity, through a mechanism of anergy or tolerance. It is now known that T cell tolerance is characterized by the generation of allergen-specific Treg cells, which produce cytokines such as IL-10 and TGF-beta with immunosuppressant and/or immunoregulatory activity. Recent studies suggest that the anti-inflammatory mechanism of SLIT is similar to classical, subcutaneous IT, with a prominent role in SLIT for mucosal dendritic cells. The tolerance pattern induced by Treg accounts for the suppressed or reduced activity of inflammatory cells and for the isotypic switch of antibody synthesis from IgE to IgG, and especially to IgG4. Data obtained from biopsies clearly indicate that the pathophysiology of the oral mucosa plays a pivotal role in inducing tolerance to the sublingually administered allergen.

Munc13 proteins control regulated exocytosis in mast cells

Mast cells (MCs) are involved in host defenses against pathogens and inflammation. Stimulated MCs release substances stored in their granules via regulated exocytosis. In other cell types, Munc13 (mammalian homolog of Caenorhabditis elegans uncoordinated gene 13) proteins play essential roles in regulated exocytosis. Here, we found that MCs express Munc13-2 and -4, and we studied their roles using global and conditional knock-out (KO) mice. In a model of systemic anaphylaxis, we found no difference between WT and Munc13-2 KO mice, but global and MC-specific Munc13-4 KO mice developed less hypothermia. This protection correlated with lower plasma histamine levels and with histological evidence of defective MC degranulation but not with changes in MC development, distribution, numbers, or morphology. In vitro assays revealed that the defective response in Munc13-4-deficient MCs was limited to regulated exocytosis, leaving other MC secretory effector responses intact. Single cell capacitance measurements in MCs from mouse mutants differing in Munc13-4 expression levels in their MCs revealed that as levels of Munc13-4 decrease, the rate of exocytosis declines first, and then the total amount of exocytosis decreases. A requirement for Munc13-2 in MC exocytosis was revealed only in the absence of Munc13-4. Electrophysiology and EM studies uncovered that the number of multigranular compound events (i.e. granule-to-granule homotypic fusion) was severely reduced in the absence of Munc13-4. We conclude that although Munc13-2 plays a minor role, Munc13-4 is essential for regulated exocytosis in MCs, and that this MC effector response is required for a full anaphylactic response.

Virus-Infected Human Mast Cells Enhance Natural Killer Cell Functions

Mucosal surfaces are protected from infection by both structural and sentinel cells, such as mast cells. The mast cell's role in antiviral responses is poorly understood; however, they selectively recruit natural killer (NK) cells following infection. Here, the ability of virus-infected mast cells to enhance NK cell functions was examined. Cord blood-derived human mast cells infected with reovirus (Reo-CBMC) and subsequent mast cell products were used for the stimulation of human NK cells. NK cells upregulated the CD69 molecule and cytotoxicity-related genes, and demonstrated increased cytotoxic activity in response to Reo-CBMC soluble products. NK cell interferon (IFN)-γ production was also promoted in the presence of interleukin (IL)-18. In vivo, SCID mice injected with Reo-CBMC in a subcutaneous Matrigel model, could recruit and activate murine NK cells, a property not shared by normal human fibroblasts. Soluble products of Reo-CBMC included IL-10, TNF, type I and type III IFNs. Blockade of the type I IFN receptor abrogated NK cell activation. Furthermore, reovirus-infected mast cells expressed multiple IFN-α subtypes not observed in reovirus-infected fibroblasts or epithelial cells. Our data define an important mast cell IFN response, not shared by structural cells, and a subsequent novel mast cell-NK cell immune axis in human antiviral host defense.

Post-sensitization administration of non-digestible oligosaccharides and Bifidobacterium breve M-16V reduces allergic symptoms in mice

To support dietary management of severe cow's milk allergic infants, a synbiotic mixture of non-digestible oligosaccharides and Bifidobacterium breve M-16V (B. breve) was designed from source materials that are completely cow's milk-free. It was investigated whether this specific synbiotic concept can reduce an established food allergic response in a research model for hen's egg allergy. Mice were orally sensitized once a week for 5 weeks to ovalbumin (OVA) using cholera toxin (CT) as an adjuvant. Non-sensitized mice received CT in PBS only. Sensitized mice were fed a control diet or a diet enriched with short-chain- (scFOS) and long-chain fructo-oligosaccharides (lcFOS), B. breve or scFOSlcFOS + B. breve for 3 weeks starting after the last sensitization. Non-sensitized mice received the control diet. Anaphylactic shock symptoms, acute allergic skin responses and serum specific IgE, mMCP-1 and galectin-9 were measured upon OVA challenge. Activated Th2-, Th1-cells and regulatory T-cells were quantified in spleen and mesenteric lymph nodes (MLN) and cytokine profiles were analyzed. Short chain fatty acids (SCFA) were measured in ceacal samples. The acute allergic skin response was reduced in mice fed the scFOSlcFOS + B. breve diet compared to mice fed any of the other diets. A reduction in mast cell degranulation (mMCP-1) and anaphylactic shock symptoms was also observed in these mice. Unstimulated splenocyte cultures produced increased levels of IL10 and IFNg in mice fed the scFOSlcFOS + B. breve diet. Correspondingly, increased percentages of activated Th1 cells were observed in the spleen. Allergen-specific re-stimulation of splenocytes showed a decrease in IL5 production. In summary; post-sensitization administration of scFOSlcFOS + B. breve was effective in reducing allergic symptoms after allergen challenge. These effects coincided with changes in regulatory and effector T-cell subsets and increases in the SCFA propionic acid. These results suggest immune modulatory benefits of dietary intervention with a unique combination of scFOSlcFOS + B. breve in established food allergy. Whether these effects translate to human applications is subject for ongoing clinical studies.

IL-10 Enhances IgE-Mediated Mast Cell Responses and Is Essential for the Development of Experimental Food Allergy in IL-10-Deficient Mice

IL-10 is a key pleiotropic cytokine that can both promote and curb Th2-dependent allergic responses. In this study, we demonstrate a novel role for IL-10 in promoting mast cell expansion and the development of IgE-mediated food allergy. Oral OVA challenge in sensitized BALB/c mice resulted in a robust intestinal mast cell response accompanied by allergic diarrhea, mast cell activation, and a predominance of Th2 cytokines, including enhanced IL-10 expression. In contrast, the development of intestinal anaphylaxis, including diarrhea, mast cell activation, and Th2 cytokine production, was significantly attenuated in IL-10(-/-) mice compared with wild-type (WT) controls. IL-10 also directly promoted the expansion, survival, and activation of mast cells; increased FcεRI expression on mast cells; and enhanced the production of mast cell cytokines. IL-10(-/-) mast cells had reduced functional capacity, which could be restored by exogenous IL-10. Similarly, attenuated passive anaphylaxis in IL-10(-/-) mice could be restored by IL-10 administration. The adoptive transfer of WT mast cells restored allergic symptoms in IL-10(-/-) mice, suggesting that the attenuated phenotype observed in these animals is due to a deficiency in IL-10-responding mast cells. Lastly, transfer of WT CD4 T cells also restored allergic diarrhea and intestinal mast cell numbers in IL-10(-/-) mice, suggesting that the regulation of IL-10-mediated intestinal mast cell expansion is T cell dependent. Our observations demonstrate a critical role for IL-10 in driving mucosal mast cell expansion and activation, suggesting that, in its absence, mast cell function is impaired, leading to attenuated food allergy symptoms.

IL-10-Induced miR-155 Targets SOCS1 To Enhance IgE-Mediated Mast Cell Function

IL-10 is an important regulatory cytokine that modulates a wide range of immune cells. Whereas it is best known for its ability to suppress immune responses, IL-10 has been found to be pathogenic in several human and animal studies of immune-mediated diseases. There is a considerable gap in our understanding of the molecular mechanisms behind the stimulatory effects of IL-10 during allergic inflammation. IL-10 treatment has been shown to suppress mast cell TNF production. In this study, we report that whereas TNF secretion was reduced, IL-10 surprisingly enhanced IgE-mediated protease and cytokine production both in vitro and in vivo. This stimulatory effect was consistent in mouse and human skin mast cells. IL-10 enhanced activation of the key FcεRI signaling proteins Stat5, JNK, and ERK. We demonstrate that IL-10 effects are dependent on Stat3 activation, eliciting miR-155 expression, with a resulting loss of suppressor of cytokine signaling-1. The importance of miR-155 was demonstrated by the inability of IL-10 to enhance anaphylaxis in miR-155-deficient mice. Taken together, our results reveal an IL-10-induced, Stat3-miR-155 signaling pathway that can promote mast cell responses.

Regular exercise modulates cardiac mast cell activation in ovariectomized rats

It is well accepted that regular exercise is a significant factor in the prevention of cardiac dysfunction; however, the cardioprotective mechanism is as yet not well defined. We have examined whether regular exercise can modulate the activity of cardiac mast cells (CMC) after deprivation of female sex hormones, as well as the density and percentage degranulation of mast cells, in ventricular tissue of ovariectomized (OVX) rats after an 11-week running program. A significant increase in CMC density with a greater percentage degranulation was induced after ovarian sex hormone deprivation. Increased CMC density was prevented by estrogen supplements, but not by regular training. To the contrary, increased CMC degranulation in the OVX rat heart was attenuated by exercise training, but not by estrogen supplement. These findings indicate a significant correlation between the degree of CMC degranulation and myocyte cross-section area. However, no change in the expression of inflammatory mediators, including chymase, interleukin-6, and interleukin-10, was detected. Taken together, these results clearly indicate one of the cardioprotective mechanisms of regular aerobic exercise is the modulation of CMC activation.

Attenuation of food allergy symptoms following treatment with human milk oligosaccharides in a mouse model

BACKGROUND

The prebiotic nature of human milk oligosaccharides (HMOs) and increasing evidence of direct immunomodulatory effects of these sugars suggest that they may have some therapeutic potential in allergy. Here, we assess the effect of two HMOs, 2'-fucosyllactose and 6'-sialyllactose, on symptomatology and immune responses in an ovalbumin-sensitized mouse model of food allergy.

METHODS

The effects of oral treatment with 2'-fucosyllactose and 6'-sialyllactose on anaphylactic symptoms induced by oral ovalbumin (OVA) challenge in sensitized mice were investigated. Mast cell functions in response to oral HMO treatment were also measured in the passive cutaneous anaphylaxis model, and direct effects on IgE-mediated degranulation of mast cells were assessed.

RESULTS

Daily oral treatment with 2'-fucosyllactose or 6'-sialyllactose attenuated food allergy symptoms including diarrhea and hypothermia. Treatment with HMOs also suppressed antigen-induced increases in mouse mast cell protease-1 in serum and mast cell numbers in the intestine. These effects were associated with increases in the CD4(+) CD25(+) IL-10(+) cell populations in the Peyer's patches and mesenteric lymph nodes, while 6'-sialyllactose also induced increased IL-10 and decreased TNF production in antigen-stimulated splenocytes. Both 2'-fucosyllactose and 6'-sialyllactose reduced the passive cutaneous anaphylaxis response, but only 6'-sialyllactose directly inhibited mast cell degranulation in vitro, at high concentrations.

CONCLUSIONS

Our results suggest that 2'-fucosyllactose and 6'-sialyllactose reduce the symptoms of food allergy through induction of IL-10(+) T regulatory cells and indirect stabilization of mast cells. Thus, human milk oligosaccharides may have therapeutic potential in allergic disease.

IL-10 enhances CTL-mediated tumor rejection by inhibiting highly suppressive CD4+ T cells and promoting CTL persistence in a murine model of plasmacytoma

Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine that regulates immune responses. IL-10 has also been shown to enhance antitumor CD8⁺ T-cell responses in tumor models although the underlying mechanisms are not fully understood. In this study, we used a series of genetic mouse models and the mouse plasmacytoma J558 model to investigate this issue. J558 tumors grew significantly faster in IL-10^-/- mice than in wild type (WT) mice, but similarly in IL-10 ^-/- Rag2 ^-/- and Rag2 ^-/- mice. Tumors from IL-10 ^-/- mice contained fewer IFN-γ-producing CD8⁺ and CD4⁺ T cells than tumors from WT mice. Strikingly, depletion of total CD4⁺ T cells, but not CD25⁺ cells, resulted in tumor eradication in IL-10 ^-/- mice. Adoptive transfer studies revealed that CD4⁺ T cells from IL-10 ^-/- mice exhibited more potent suppression of cytotoxic T lymphocyte (CTL)-mediated tumor rejection than their WT counterparts, and IL-10-deficient tumor-infiltrating CD4⁺ T cells expressed higher levels of PD-L1 and CTLA-4 inhibitory molecules. Although IL-10-deficient CD8⁺ T cells are not defective in activation and initial rejection of tumors, adoptive transfer studies using IL-10-deficient P1CTL transgenic T cells that recognize the tumor rejection antigen P1A reveal that IL-10 is required for long-term persistence of CTLs and control of tumor growth. Thus, we have found that IL-10 enhances antitumor CTL responses by inhibiting highly suppressive CD4⁺ T cells and promoting CTL persistence. These data have important implications for the design of immunotherapy for human cancer.

Genomic analysis of LPS-stimulated myeloid cells identifies a common pro-inflammatory response but divergent IL-10 anti-inflammatory responses

Inflammation is an essential physiological response to infection and injury that must be kept within strict bounds. The IL-10/STAT3 anti-inflammatory response (AIR) is indispensable for controlling the extent of inflammation, although the complete mechanisms downstream of STAT3 have not yet been elucidated. The AIR is widely known to extend to other myeloid cells, but it has best been characterized in macrophages. Here we set out to characterize the LPS-mediated pro-inflammatory response and the AIR across a range of myeloid cells. We found that whereas the LPS-induced pro-inflammatory response is broadly similar among macrophages, dendritic cells, neutrophils, mast cells and eosinophils, the AIR is drastically different across all myeloid cell types that respond to IL-10 (all bar eosinophils). We propose a model whereby the IL-10/STAT3 AIR works by selectively inhibiting specific pathways in distinct cell types: in macrophages the AIR most likely works through the inhibition of NF-κB target genes; in DCs and mast cells through indirect IRF disruption; and in neutrophils through IRF disruption and possibly also indirect NF-κB inhibition. In summary, no conserved IL-10/STAT3 AIR effectors were identified; instead a cell type-specific model of the AIR is proposed.

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.

Role of cellular immunity in cow's milk allergy: pathogenesis, tolerance induction, and beyond

Food allergy is an aberrant immune-mediated reaction against harmless food substances, such as cow's milk proteins. Due to its very early introduction, cow's milk allergy is one of the earliest and most common food allergies. For this reason cow's milk allergy can be recognized as one of the first indications of an aberrant inflammatory response in early life. Classically, cow's milk allergy, as is true for most other allergies as well, is primarily associated with abnormal humoral immune responses, that is, elevation of specific immunoglobulin E levels. There is growing evidence indicating that cellular components of both innate and adaptive immunity play significant roles during the pathogenesis of cow's milk allergy. This is true for the initiation of the allergic phenotype (stimulation and skewing towards sensitization), development and outgrowth of the allergic disease. This review discusses findings pertaining to roles of cellular immunity in allergic inflammation, and tolerance induction against cow's milk proteins. In addition, a possible interaction between immune mechanisms underlying cow's milk allergy and other types of inflammation (infections and noncommunicable diseases) is discussed.

ADAM10 is required for SCF-induced mast cell migration

A Disintegrin and Metalloproteinase (ADAM)-10 plays critical roles in neuronal migration and distribution. Recently, ADAM10 deletion was shown to disrupt myelopoiesis. We found that inducible deletion of ADAM10 using Mx1-driven Cre recombinase for a period of three weeks resulted in mast cell hyperplasia in the skin, intestine and spleen. Mast cells express surface ADAM10 in vitro and in vivo, at high levels compared to other immune cells tested. ADAM10 is important for mast cell migration, since ADAM10-deficiency reduced c-Kit-mediated migration. As with some mast cell proteases, ADAM10 expression could be altered by the cytokine microenvironment, being inhibited by IL-10 or TGFβ1, but not by several other T cell-derived cytokines. Collectively these data show that the ADAM10 protease is an important factor in mast cell migration and tissue distribution, and can be manipulated by environmental cues.

Mechanisms of allergen-specific immunotherapy: multiple suppressor factors at work in immune tolerance to allergens

Allergen-specific immunotherapy (AIT) has been used for more than 100 years as a desensitizing therapy for IgE-mediated allergic diseases and represents a potentially curative way of treatment. The mechanisms of action of AIT include the induction of very early desensitization of mast cells and basophils; generation of regulatory T and regulatory B (Breg) cell responses; regulation of IgE and IgG4; decreases in numbers and activity of eosinophils and mast cells in mucosal allergic tissues; and decreases in the activity of basophils in circulation. Skewing of allergen-specific effector T and effector B cells to a regulatory phenotype appears as a key event in the course of AIT and normal immune response to allergens. Recently, inducible IL-10-secreting Breg cells were also demonstrated to contribute to allergen tolerance through suppression of effector T cells and selective induction of IgG4 isotype antibodies. Allergen-specific regulatory T and Breg cells orchestrate a general immunoregulatory activity, which can be summarized as suppression of cytokines from inflammatory dendritic cells; suppression of effector TH1, TH2, and TH17 cells; suppression of allergen-specific IgE and induction of IgG4; and suppression of migration of mast cells, basophils, eosinophils, and effector T cells to tissues. A detailed knowledge of the mechanisms of AIT is not only important in designing the prevention and treatment of allergic diseases but might also find applications in the treatment of autoimmune diseases, organ transplantation, chronic infection, and cancer.

Stress triggers coronary mast cells leading to cardiac events

OBJECTIVE

Stress precipitates and worsens not only asthma and atopic dermatitis but also acute coronary syndromes (ACSs), which are associated with coronary inflammation. Evidence linking stress to ACS was reviewed and indicated that activation of coronary mast cells (MCs) by stress, through corticotropin-releasing hormone (CRH) and other neuropeptides, contributes to coronary inflammation and coronary artery disease.

DATA SOURCES

PubMed was searched (2005-2013) for articles using the following keywords: allergies, anaphylaxis, anxiety, coronary arteries, coronary artery disease, C-reactive protein, cytokines, chymase, histamine, hypersensitivity, interleukin-6 (IL-6), inflammation, mast cells, myocardial ischemia, niacin, platelet-activating factor, rupture, spasm, statins, stress, treatment, tryptase, and uroctortin.

STUDY SELECTIONS

Articles were selected based on their relevance to how stress affects ACS and how it activates coronary MCs, leading to coronary hypersensitivity, inflammation, and coronary artery disease.

RESULTS

Stress can precipitate allergies and ACS. Stress stimulates MCs through the activation of high-affinity surface receptors for CRH, leading to a CRH-dependent increase in serum IL-6. Moreover, neurotensin secreted with CRH from peripheral nerves augments the effect of CRH and stimulates cardiac MCs to release IL-6, which is elevated in ACS and is an independent risk factor for myocardial ischemia. MCs also secrete CRH and uroctortin, which induces IL-6 release from cardiomyocytes. The presence of atherosclerosis increases the risk of cardiac MC activation owing to the stimulatory effect of lipoproteins and adipocytokines. Conditions such as Kounis syndrome, mastocytosis, and myalgic encephalopathy/chronic fatigue syndrome are particularly prone to coronary hypersensitivity reactions.

CONCLUSION

Inhibition of cardiac MCs may be a novel treatment approach.

Phototherapy with artificial light suppresses dextran sulfate sodium-induced colitis in a mouse model

BACKGROUND AND AIM

Medical treatment for inflammatory bowel disease (IBD) requires chronic administration and causes side effects. Recently, anti-inflammatory effects of phototherapy were reported in animal models. The present study evaluated whether phototherapy improves dextran sulfate sodium (DSS)-induced colitis in a mouse model of IBD.

METHODS

Mice were divided into four equal groups: Control, DSS, DSS + light low (LL), and DSS + light high (LH) groups. Normal fluorescent light intensity in the Control and DSS groups was 200 lux. Artificial light intensities were as follows: DSS + LL group, 1000 lux; DSS + LH group, 2500 lux. After administering phototherapy for 7 days, we evaluated disease activity index (DAI), histological score, colon length/weight, serum 1,25-dihydroxyvitamin D(3) level, and serum and colonic cytokines in the mice.

RESULTS

DAI and histological scores were significantly lower in the DSS + LL group than in the DSS group (both, P < 0.05). Colon length and weight were significantly higher in the DSS + LL group than in the DSS group (both, P < 0.05). Serum interleukin (IL)-6, TNF-α, and IL-17 in the DSS + LL group were significantly lower, and serum and colonic IL-10 were significantly higher in the DSS + LL group than in the DSS group (all, P < 0.05). Serum 1,25-dihydroxyvitamin D(3) levels in the DSS + LH group were significantly increased compared with those in the DSS + LL and DSS groups.

CONCLUSION

Artificial light phototherapy suppressed DSS-induced colitis in mice by suppression of pro-inflammatory cytokines and promotion of anti-inflammatory cytokines.

Mechanisms of allergen-specific immunotherapy and novel ways for vaccine development

Allergen-specific immunotherapy (SIT) is the only available curative treatment of allergic diseases. Recent evidence provided a plausible explanation to its multiple mechanisms inducing both rapid desensitization and long-term allergen-specific immune tolerance, and suppression of allergic inflammation in the affected tissues. During SIT, peripheral tolerance is induced by the generation of allergen-specific regulatory T cells, which suppress proliferative and cytokine responses against the allergen of interest. Regulatory T cells are characterized by IL-10 and TGF-beta secretion and expression of important cell surface suppressive molecules such as cytotoxic T lymphocyte antigen-4 and programmed death-1 that directly or indirectly influence effector cells of allergic inflammation, such as mast cells, basophils and eosinophils. Regulatory T cells and particularly IL-10 also have an influence on B cells, suppressing IgE production and inducing the production of blocking type IgG4 antibodies. In addition, development of allergen-specific B regulatory cells that produce IL-10 and develop into IgG4 producing plasma cells represent essential players in peripheral tolerance. These findings together with the new biotechnological approaches create a platform for development of the advanced vaccines. Moreover, reliable biomarkers could be selected and validated with the intention to select the patients who will benefit most from this immune-modifying treatment. Thus, allergen-SIT could provide a complete cure for a larger number of allergic patients and novel preventive approaches need to be elaborated.

CD25+ regulatory T cells transfer n-3 long chain polyunsaturated fatty acids-induced tolerance in mice allergic to cow's milk protein

BACKGROUND

Recently, we have shown that dietary long-chain n-3 polyunsaturated fatty acids (n-3 LCPUFA) largely prevent allergic sensitization in a murine model for cow's milk allergy. The aim of this study was to assess the contribution of regulatory T cells (Treg) in the prevention of food allergy by n-3 LCPUFA.

METHODS

C3H/HeOuJ female donor mice were fed a control or fish oil diet before and during oral sensitization with cow's milk protein whey. Acute allergic skin response (ASR), anaphylaxis, body temperature, serum immunoglobulins, and mouse mast cell protease-1 (mmcp-1) were assessed. Splenocytes of sham- or whey-sensitized donor mice fed either control or fish oil diet were adoptively transferred to naïve recipient mice. Recipient mice received a whole splenocyte suspension, splenocytes ex vivo depleted of CD25+ cells, or MACS-isolated CD4+ CD25+ Treg. Recipient mice were sham- or whey-sensitized and fed control diet.

RESULTS

The ASR as well as whey-specific IgE and whey-specific IgG1 levels were reduced in whey-sensitized donor mice fed the fish oil diet as compared to the control diet. Splenocytes of control-diet-fed whey-sensitized donors transferred immunologic memory. By contrast, splenocytes of fish-oil-fed whey-sensitized - but not sham-sensitized - donors transferred tolerance to recipients as shown by a reduction in ASR and serum mmcp-1, and depletion of CD25+ Treg abrogated this. Transfer of CD25+ Treg confirmed the involvement of Treg in the suppression of allergic sensitization.

CONCLUSIONS

CD25+ Treg are crucial in whey allergy prevention by n-3 LCPUFA.

Peritoneal mast cell degranulation differently affected thioglycollate-induced macrophage phenotype and activity in Dark Agouti and Albino Oxford rats

AIMS

Macrophages are heterogeneous population of inflammatory cells and, in response to the microenvironment, become differentially activated. The objective of the study was to explore macrophage effector functions during different inflammatory conditions in two rat strains.

MAIN METHODS

We have investigated the effects of in vivo treatment with mast cell-degranulating compound 48/80 and/or thioglycollate on peritoneal macrophage phagocytosis and capacity to secrete hydrogen peroxide (H2O2), tumor necrosis factor-α (TNF-α) and nitric oxide (NO) in Dark Agouti (DA) and Albino Oxford (AO) rat strains. Besides, fresh peritoneal cells were examined for the expression of ED1, ED2 and CD86 molecules.

KEY FINDINGS

In thioglycollate-elicited macrophages, increased proportion of ED1+ cells was accompanied with elevated phagocytosis of zymosan (DA strain), whereas increased expression level of CD86 molecule on ED2+ macrophages matched elevated secretory capacity for H2O2, TNF-α and NO (AO rats). Although mast cell degranulation induced by compound 48/80 increased the percentages of ED2+ macrophages in both rat strains, the proportion of ED2+ cells expressing CD86 molecule was decreased and increased in DA and AO rats, respectively. Furthermore, in DA strain compound 48/80 diminished macrophage secretion of NO, but stimulated all macrophage functions tested in AO strain. If applied concomitantly, the compound 48/80 additively increased macrophage activity induced by thioglycollate in AO rats.

SIGNIFICANCE

Macrophages from DA and AO rat strains show different susceptibility to mediators released from mast cells, suggesting that strain-dependant predisposition(s) toward particular activation pattern is decisive for the macrophage efficacy in response to inflammatory agents.

Myocardial remodeling in diabetic cardiomyopathy associated with cardiac mast cell activation

Diabetic cardiomyopathy is a specific disease process distinct from coronary artery disease and hypertension. The disease features cardiac remodeling stimulated by hyperglycemia of the left ventricle wall and disrupts contractile functions. Cardiac mast cells may be activated by metabolic byproducts resulted from hyperglycermia and then participate in the remodeling process by releasing a multitude of cytokines and bioactive enzymes. Nedocromil, a pharmacologic stabilizer of mast cells, has been shown to normalize cytokine levels and attenuate cardiac remodeling. In this study, we describe the activation of cardiac mast cells by inducing diabetes in normal mice using streptozotocin (STZ). Next, we treated the diabetic mice with nedocromil for 12 weeks and then examined their hearts for signs of cardiac remodeling and quantified contractile function. We observed significantly impaired heart function in diabetic mice, as well as increased cardiac mast cell density and elevated mast cell secretions that correlated with gene expression and aberrant cytokine levels associated with cardiac remodeling. Nedocromil treatment halted contractile dysfunction in diabetic mice and reduced cardiac mast cell density, which correlated with reduced bioactive enzyme secretions, reduced expression of extracellular matrix remodeling factors and collagen synthesis, and normalized cytokine levels. However, the results showed nedocromil treatments did not return diabetic mice to a normal state. We concluded that manipulation of cardiac mast cell function is sufficient to attenuate cardiomyopathy stimulated by diabetes, but other cellular pathways also contribute to the disease process.

Different potency of bacterial antigens TLR2 and TLR4 ligands in stimulating mature mast cells to cysteinyl leukotriene synthesis

The aim of study was to compare the potency of different bacterial antigens to induce rat mature mast cell to cysteinyl leukotriene (cysLT) generation. We examined Toll-like receptor (TLR)2 agonists, i.e. lipoteichoic acid (LTA) Staphylococcus faecalis, Streptococcus pyogenes, Bacillus subtilis and Staphylococcus aureus, lipoarabinomannan (LAM) Mycobacterium smegmatis, peptydoglican (PGN) Staphylococcus aureus, as well as TLR4 agonists, i.e. lipopolysaccharide (LPS) Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella enteritidis, Pophyromonas gingivalis and Escherichia coli. We also estimated the effect of tumor necrosis factor (TNF)-, interleukin (IL)-6-, CCL5-, and IL-10-priming on mast cell cysLT synthesis following bacterial antigen activation. We found that all bacterial antigens activated mast cells to cysLT generation; however, the extent of cysLT release in response to stimulation varied. Out of the examined antigens LPS P. gingivalis exhibited the highest potency, as it induced cysLT generation acting at a very low concentration (10(-4) ng/mL). Other LPSs affected mast cells at higher (up to 10(5) -fold) concentrations. LTAs were the most effective at concentrations of 5 × 10(2) ng/mL, while LAM and PGN stimulated mast cells to maximal cysLT generation at concentrations as high as 10(5) ng/mL. Anti-TLR2 and anti-TLR4 antibodies, as well as nuclear factor κB (NF-κB) inhibitor significantly diminished cysLT generation in response to bacterial antigen stimulation. Priming with TNF, IL-6 and CCL5 did not affect bacterial antigen-induced cysLT generation, while IL-10-pretreatment caused significant decrease in cysLT synthesis by mast cells. These observations might have a great pathophysiological importance; inasmuch cysLTs strongly influence the development and intensity of inflammation during bacterial infection.

Immunological mechanisms for desensitization and tolerance in food allergy

Food allergy is a major public health concern in westernized countries, estimated to affect 5 % of children and 3-4 % of adults. Allergen-specific immunotherapy for food allergy is currently being actively evaluated, but is still experimental. The optimal protocol, in terms of the route of administration of the food, target maintenance dose, and duration of maintenance therapy, and the optimal patient for these procedures are still being worked out. The mechanisms underlying successful food desensitization are also unclear, in part, because there is no standard immunotherapy protocol. The mechanisms involved, however, may include mast cell and basophil suppression, development of food-specific IgG4 antibodies, reduction in the food-specific IgE/IgG4 ratio, up-regulation and expansion of natural or inducible regulatory T cells, a skewing from a Th2 to a Th1 profile, and the development of anergy and/or deletion in antigen-specific cells. Additional studies are required to elucidate and understand these mechanisms by which desensitization and tolerance are achieved, which may reveal valuable biomarkers for evaluating and following food allergic patients on immunotherapy.

The Fyn-STAT5 Pathway: A New Frontier in IgE- and IgG-Mediated Mast Cell Signaling

Mast cells are central players in immune surveillance and activation, positioned at the host–environment interface. Understanding the signaling events controlling mast cell function, especially those that maintain host homeostasis, is an important and still less understood area of mast cell-mediated disease. With respect to allergic disease, it is well established that IgE and its high affinity receptor FcεRI are major mediators of mast cell activation. However, IgG-mediated signals can also modulate mast cell activities. Signals elicited by IgG binding to its cognate receptors (FcγR) are the basis for autoimmune disorders such as lupus and rheumatoid arthritis. Using knowledge of IgE-mediated mast cell signaling, recent work has begun to illuminate potential overlap between FcεRI and FcγR signal transduction. Herein we review the importance of Src family kinases in FcεRI and FcγR signaling, the role of the transcription factor STAT5, and impingement of the regulatory cytokines IL-4, IL-10, and TGFβ1 upon this network.

Therapies for allergic inflammation: refining strategies to induce tolerance

Current therapies for asthma and allergy are relatively safe and effective at controlling symptoms but do not change the chronic course of disease. There is no established method to prevent asthma and allergy, and major unmet needs in this area include the better control of the severe forms of these diseases and the developments of curative therapies. Two major therapeutic strategies for asthma and allergy are currently being developed, and I here discuss the advances and challenges for future therapeutic development in these two areas. The first approach, allergen-specific immunotherapy, aims to induce specific immune tolerance and has a long-term disease-modifying effect. The second approach is the use of biological immune response modifiers to decrease pathological immune responses. Combination strategies using both of these approaches may also provide a route for addressing the unmet clinical needs in allergic diseases.

Environment and T regulatory cells in allergy

The central role of T regulatory cells in the responses against harmless environmental antigens has been confirmed by many studies. Impaired T regulatory cell function is implicated in many pathological conditions, particularly allergic diseases. The "hygiene hypothesis" suggests that infections and infestations may play a protective role for allergy, whereas environmental pollutants favor the development of allergic diseases. Developing countries suffer from a variety of infections and are also facing an increasing diffusion of environmental pollutants. In these countries allergies increase in relation to the spreading use of xenobiotics (pesticides, herbicides, pollution, etc.) with a rate similar to those of developed countries, overcoming the protective effects of infections. We review here the main mechanisms of non-self tolerance, with particular regard to relations between T regulatory cell activity, infections and infestations such as helminthiasis, and exposure to environmental xenobiotics with relevant diffusion in developing countries.

The influence of monogalactosyldiacylglycerols from different marine macrophytes on immunogenicity and conformation of protein antigen of tubular immunostimulating complex

The tubular immunostimulating complex (TI-complex) is a novel nanoparticulate antigen delivery system consisting of cholesterol, triterpene glycoside cucumarioside A(2)-2, and glycolipid monogalactosyldiacylglycerol (MGDG) isolated from marine macrophytes. MGDG is crucial for the formation of a lipid matrix for the protein antigen incorporated in TI-complexes. Fatty acid composition and the physical state of this glycolipid depend on the taxonomic position of marine macrophytes. Therefore, the aim of the present work was to study the capacity of MGDGs, isolated from five species of marine macrophytes, to influence conformation and to enhance immunogenicity of porin from Yersinia pseudotuberculosis (YOmpF) as a model antigen of subunit vaccine based on TI-complexes. The trimeric porin was chosen for these experiments, because it was approximately two times more immunogenic than monomeric porin incorporated in TI-complexes. Immunization of mice with YOmpF within TI-complexes, comprised of different MGDGs, revealed a dependence of the immunostimulating effect of TI-complexes on the microvicosity of this glycolipid. TI-complexes comprising MGDGs from Sargassum pallidum and Ulva fenestrata with medium microviscosity induced maximal levels of anti-porin antibodies (four times higher when compared with those induced by pure porin). The adjuvant effect of TI-complexes based on other MGDGs varied by 2.8, 2.3 and 1.3 times for TI-complexes comprised of MGDGs from Zostera marina, Ahnfeltia tobuchiensis, and Laminaria japonica, respectively. MGDGs are also able to influence cytokine mechanisms of immunological regulation. DSC and spectroscopic studies showed that maximal immunostimulating effect of TI-complexes correlated with a moderate stabilizing influence of MGDGs from S. pallidum and U. fenestrata on the conformation of porin. The results obtained suggest lipid "nanofluidics" as a novel strategy for optimizing the immune response to protein antigens within lipid particulate systems.

Regulatory T cells enhance mast cell production of IL-6 via surface-bound TGF-β

Mast cell degranulation is a hallmark of allergic reactions, but mast cells can also produce many cytokines that modulate immunity. Recently, CD25(+) regulatory T cells (Tregs) have been shown to inhibit mast cell degranulation and anaphylaxis, but their influence on cytokine production remained unknown. In this study, we show that, rather than inhibit, Tregs actually enhance mast cell production of IL-6. We demonstrate that, whereas inhibition of degranulation was OX40/OX40 ligand dependent, enhancement of IL-6 was due to TGF-β. Interestingly, our data demonstrate that the Treg-derived TGF-β was surface-bound, because the interaction was contact dependent, and no TGF-β was detectable in the supernatant. Soluble TGF-β1 alone was sufficient to enhance mast cell IL-6 production, and these supernatants were sufficient to promote Th17 skewing, but those from Treg-mast cell cultures were not, supporting this being surface-bound TGF-β from the Tregs. Interestingly, the augmentation of IL-6 production occurred basally or in response to innate stimuli (LPS or peptidoglycan), adaptive stimuli (IgE cross-linking by specific Ag), and cytokine activation (IL-33). We demonstrate that TGF-β led to enhanced transcription and de novo synthesis of IL-6 upon activation without affecting IL-6 storage or mRNA stability. In vivo, the adoptive transfer of Tregs inhibited mast cell-dependent anaphylaxis in a model of food allergy but promoted intestinal IL-6 and IL-17 production. Consequently, our findings establish that Tregs can exert divergent influences upon mast cells, inhibiting degranulation via OX40/OX40 ligand interactions while promoting IL-6 via TGF-β.

Novel insights on the role of the innate immune system in systemic sclerosis

Over the last several years the involvement of the innate immune system in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus (SLE) has become well established. As systemic sclerosis (SSc; scleroderma) shares clinical features and autoantibodies with SLE, investigation has recently focused on the role of innate immunity in SSc. This has been supported by recent genetic studies. However, unlike SLE and other related autoimmune diseases, SSc patients suffer from pathologic fibrosis of skin and internal organs. The fibrotic component of SSc shares several features with syndromes following environmental exposures to agents such as organic solvents, silica dust and bleomycin. Recent work in SSc and these related fibrotic diseases have identified several areas in which innate immunity can stimulate inflammation as well as fibrosis. This article will focus on the recent discoveries identifying a prominent role of cells of the innate immune system, pattern recognition receptors, and activation of dendritic cells in the pathogenesis of SSc.

T-cell subset regulation in atopy

Presentation of processed allergen by antigen-presenting cells to T-helper (Th) lymphocytes, which is influenced costimulatory signals, cytokines, chemokines, and regulatory T cells (Tregs), determines the development of different types of T-cell immunity. The discovery of Tregs revolutionized the primary concepts of immune regulation interpreted within the framework of a binary Th1/Th2 paradigm. Tregs play a central role in the maintenance of peripheral homeostasis, the establishment of controlled immune responses, and the inhibition of allergen-specific effector cells. Recently, some other T-cell subsets appeared, including Th17 and Th9 cells, which control local tissue inflammation through upregulation of proinflammatory cytokines and chemokines. This review aims to discuss our understanding of the T-cell subset reciprocal interaction in atopy.