Mast Cell Responses Research Articles

MrgprD-expressing nonpeptidergic neurons suppress mast cell responsiveness via glutamate release

Abstract Cutaneous mast cells underly numerous skin inflammatory processes. Our study reveals that the ablation of a subset of sensory nonpeptidergic neurons expressing MrgprD increases the expression of a mast cell gene module, including the activating receptor, Mrgprb2, leading to increased mast cell reactivity to MrgprB2 ligands, and cutaneous inflammation in several disease models, such as irritant dermatitis and rosacea. MrgprD-expressing neurons releases glutamate to inhibit mast cell responsiveness. Reducing glutamate release from MrgprD-expressing neurons in the periphery resulted in a hyperresponsive state of mast cells. The antagonism of glutamate receptors on cultured peritoneal cavity mast cells (PCMCs) enhances MC degranulation and phenocopied the genetic state in the absence of MrgprD-expressing neurons. We subsequently identifies the kainate receptor GluR6/KA2 as the glutamate receptor subtype expressed on dermal MCs. Two non-specific agonists of GluR6, and the highly selective GluR6 agonist SYM2081 suppress the degranulation of PCMC in response to MrgprB2 activation but not FcɛRI crosslinking in a dose-dependent manner. In vivo, intradermal delivery of SYM2081 suppresses compound 48/80 induced-dermal MC activation, and attenuates croton oil-induced irritant dermatitis, but not IgE-dependent passive cutaneous anaphylaxis. Together, these data demonstrate that glutamate acting via the GluR6/KA2 receptor promotes mast cell hypo-responsiveness during homeostasis and suggests that selective agonism of this pathway has the potential to reduce mast cell activation in vivo, which would be of significant utility in the treatment of diseases where mast cells represent a key component of the pathogenic pathway.

Age and sex influence cultured rodent mast cell and basophil responses to antigen

Abstract Mast cells initiate allergic inflammatory immune responses and play a role in disease by releasing various inflammatory and immunomodulatory mediators. Several mast cell-lines and primary cultured cells have been used as mast cell models with inconsistent results among research groups. Bone marrow-derived mast cells (BMMC) cultured from mouse bone marrow progenitor cells are often used as a representative model of mucosal mast cell behaviour, however their reported phenotype is variable due to inconsistent culture protocols. RBL-2H3 is a rat basophilic histamine-releasing cell line that has some characteristics of both mast cells and basophils but is not a true representation of either cell type. The murine mast cell line MC/9 is an IL-3-dependent mucosal mast cell model but has limited mast cell characteristics. In this study, we have compared the response of BMMC (derived from C57BL/6 male or female mice), two sources of RBL-2H3 (purchased directly from ATCC and a lab curated culture), and MC/9 (ATCC) at several critical stages to some common stimuli (IgE/Ag, A23187) and analyzed mast cell morphology, expression level of common mast cell surface markers (CD117 and FcɛRI), protease expression, and function (growth kinetics, viability, ROS production, degranulation, cytokine release and FcɛRI signaling). The objective of this study was to provide insight into the effects of culture conditions, biological sex, and age of the cells on variability among reported phenotypes and, to determine optimal conditions for activation of these cells. Factors that are often overlooked such as source, age and biological sex of mast cells play an integral role in phenotypic outcomes and may account for the reported variability in their function. National Research Council Canada

Comparison of intrinsic allergenicity potentials of gliadins from durum and soft white wheats in an adjuvant-free mouse model

Abstract Wheat is one of the major allergenic foods capable of eliciting life-threatening anaphylaxis. Discovering potential hypo/hyper-allergenic wheat classes is imperative to advance our knowledge and manage wheat allergy. Durum wheat (genome AABB) and soft white wheat (genome AABBDD) are two commonly consumed wheats. However, whether there are differences in the intrinsic allergenicity potential between them is unknown. Here, we tested the hypothesis that gliadins extracted from durum and soft white wheats will differ in their intrinsic allergenicity in an adjuvant-free mouse model that uses skin sensitization followed by intraperitoneal (IP) allergen challenge. Balb/c female mice were produced and maintained on a plant protein-free diet during this study. Groups of mice (n=5–10/group) were exposed to gliadins or vehicle via the skin once a week for 9 weeks. IgE responses were analyzed by ELISA to determine sensitization. Systemic anaphylaxis upon IP challenge was quantified by hypothermic shock response (HSR); mucosal mast cell response (MMCR) was quantified by measuring MMCP-1 in the blood. Our results suggest that mice exhibited robust, but comparable levels of specific IgE antibody responses after skin exposures to both wheat gliadins elicited. HSRs induced upon IP challenges with gliadins from the two wheats displayed strikingly similar kinetics. Interestingly, soft white wheat gliadin was significantly more potent in eliciting MMCR compared to the durum wheat gliadin. We demonstrate for the first-time the similarities and differences in intrinsic allergenicity potentials of gliadins obtained from the two wheats. Supported by grants from USDA/NIFA Hatch Project MICL02486 (Accession Number: 1012322)

Evaluation of salt-soluble protein extract from an ancient wheat progenitor (Aegilops tauschii) for intrinsic allergenicity in an adjuvant-free mouse model of wheat allergy

Abstract Wheat allergies are a growing significant health concern around the globe. The ancient diploid wheat progenitor, Aegilops tauschii (genome DD), contributed to the genetic diversity of the common soft white wheat (Triticum aestivum, genomes AABBDD). The allergenic potential of Ae. tauschii is largely unknown. Here we tested the hypothesis that the the salt-soluble protein extract (SSPE) from Ae. tauschii will be intrinsically allergenic in an adjuvant-free mouse model of wheat allergy. The ancient wheat progenitor was grown at the Michigan State University greenhouse using the seeds stored at our wheat breeding program. The SSPE was prepared, characterized for quality, and then tested in the mouse model that uses skin sensitization followed by oral allergen challenge. Balb/c mice were produced and maintained on a plant protein-free diet. Groups of adult mice (n=10/group) were repeatedly exposed to SSPE or vehicle via the skin. Allergic sensitization was assessed by specific IgE (sIgE) response. Oral anaphylaxis was quantified by hypothermic shock response (HSR). The mucosal mast cell response (MMCR) was quantified by measuring MMCP-1 in the blood. Repeated skin exposure to SSPE but not the vehicle elicited robust sIgE response. Oral SSPE challenge but not vehicle challenge elicited significant, but a modest HSR as well as MMCR. In summary, we report the characterization of intrinsic allergenicity potential of the SSPE obtained from the Ae. tauschii wheat progenitor for the first time. Funding: USDA/NIFA. The United States Department of Agriculture (USDA)/National Institute of Food and Agriculture (NIFA); Hatch project MICL02486 (Accession Number: 1012322); Hatch project MICL01699; Agricultural and Food Research Initiative Competitive Program, grant number: 2018-67017-27876

Construction of an interferon regulatory factors-related risk model for predicting prognosis, immune microenvironment and immunotherapy in clear cell renal cell carcinoma.

Interferon regulatory factors (IRFs) played complex and essential roles in progression, prognosis, and immune microenvironment in clear cell renal cell carcinoma (ccRCC). The purpose of this study was to construct a novel IRFs-related risk model to predict prognosis, tumor microenvironment (TME) and immunotherapy response in ccRCC. Multi-omics analysis of IRFs in ccRCC was performed based on bulk RNA sequencing and single cell RNA sequencing data. According to the expression profiles of IRFs, the ccRCC samples were clustered by non-negative matrix factorization (NMF) algorithm. Then, least absolute shrinkage and selection operator (LASSO) and Cox regression analyses were applied to construct a risk model to predict prognosis, immune cells infiltration, immunotherapy response and targeted drug sensitivity in ccRCC. Furthermore, a nomogram comprising the risk model and clinical characteristics was established. Two molecular subtypes with different prognosis, clinical characteristics and infiltration levels of immune cells were identified in ccRCC. The IRFs-related risk model was developed as an independent prognostic indicator in the TCGA-KIRC cohort and validated in the E-MTAB-1980 cohort. The overall survival of patients in the low-risk group was better than that in the high-risk group. The risk model was superior to clinical characteristics and the ClearCode34 model in predicting the prognosis. In addition, a nomogram was developed to improve the clinical utility of the risk model. Moreover, the high-risk group had higher infiltration levels of CD8+ T cell, macrophages, T follicular helper cells and T helper (Th1) cells and activity score of type I IFN response but lower infiltration levels of mast cells and activity score of type II IFN response. Cancer immunity cycle showed that the immune activity score of most steps was remarkably higher in the high-risk group. TIDE scores indicated that patients in the low-risk group were more likely responsive to immunotherapy. Patients in different risk groups showed diverse drug sensitivity to axitinib, sorafenib, gefitinib, erlotinib, dasatinib and rapamycin. In brief, a robust and effective risk model was developed to predict prognosis, TME characteristics and responses to immunotherapy and targeted drugs in ccRCC, which might provide new insights into personalized and precise therapeutic strategies.

Mast Cells as a Target-A Comprehensive Review of Recent Therapeutic Approaches.

Mast cells (MCs) are the immune cells distributed throughout nearly all tissues, mainly in the skin, near blood vessels and lymph vessels, nerves, lungs, and the intestines. Although MCs are essential to the healthy immune response, their overactivity and pathological states can lead to numerous health hazards. The side effect of mast cell activity is usually caused by degranulation. It can be triggered by immunological factors, such as immunoglobulins, lymphocytes, or antigen-antibody complexes, and non-immune factors, such as radiation and pathogens. An intensive reaction of mast cells can even lead to anaphylaxis, one of the most life-threatening allergic reactions. What is more, mast cells play a role in the tumor microenvironment by modulating various events of tumor biology, such as cell proliferation and survival, angiogenesis, invasiveness, and metastasis. The mechanisms of the mast cell actions are still poorly understood, making it difficult to develop therapies for their pathological condition. This review focuses on the possible therapies targeting mast cell degranulation, anaphylaxis, and MC-derived tumors.

Mast cells selectively produce inflammatory mediators and impact the early response to Chlamydia reproductive tract infection.

Chlamydia trachomatis (C. trachomatis) is a Gram-negative obligate intracellular bacterium that causes reproductive tract complications in women, including ectopic pregnancies and tubal factor infertility. We hypothesized that mast cells, which are common at mucosal barriers, may contribute to responses to Chlamydia infection and aimed to define human mast cell responses to C. trachomatis. Human cord blood-derived mast cells (CBMCs) were exposed to C. trachomatis to assess bacterial uptake, mast cell degranulation, gene expression, and production of inflammatory mediators. The role of formyl peptide receptors and Toll-like receptor 2 (TLR2) were investigated using pharmacological inhibitors and soluble TLR2. Mast cell-deficient mice and littermate controls were used to examine the in vivo role of mast cells in influencing the immune response to Chlamydia infection in the female reproductive tract. C. trachomatis bacteria were taken up by human mast cells but did not replicate efficiently inside CBMCs. C. trachomatis-activated mast cells did not degranulate but maintained viability and exhibited cellular activation with homotypic aggregation and upregulation of ICAM-1. However, they significantly enhanced the gene expression of IL1B, CCL3, NFKB1, CXCL8, and IL6. Inflammatory mediators were produced, including TNF, IL-1β, IL-1RA, IL-6, GM-CSF, IL-23, CCL3, CCL5, and CXCL8. Endocytic blockade resulted in reduced gene expression of IL6, IL1B, and CCL3, suggesting C. trachomatis induced mast cell activation in both extracellular and intracellular locations. The IL-6 response to C. trachomatis was reduced when CBMCs were treated with C. trachomatis coated with soluble TLR2. Mast cells derived from TLR2-deficient mice also demonstrated a reduced IL-6 response to C. muridarum. Five days following C. muridarum infection, mast cell-deficient mice showed attenuated CXCL2 production and significantly reduced numbers of neutrophils, eosinophils, and B cells in the reproductive tract when compared with mast cell-containing littermates. Taken together, these data demonstrate that mast cells are reactive to Chlamydia spp. through multiple mechanisms that include TLR2-dependent pathways. Mast cells also play an important role in shaping in vivo immune responses in Chlamydia reproductive tract infection through both effector cell recruitment and modification of the chemokine microenvironment.

IgG:FcγRIIb signals block effector programs of IgE:FcεRI-activated mast cells but spare survival pathways

IgE-induced mast cell (MC) degranulation can be inhibited by IgG antibodies, signaling via FcγRIIb, but the effects of IgG on IgE-induced MC transcription are unknown. We sought to assess inhibitory IgG:FcγRIIb effects on MC responses to IgE using complementary transcriptomic and functional approaches. RNA sequencing was performed on bone marrow-derived MCs from wild-type and FcγRIIb-deficient mice to identify genes activated following IgE receptor crosslinking that were further modulated in the presence of antigen-specific IgG in an FcγRIIb-dependent fashion. Parallel analyses of signaling pathways and allergic responses invivo were performed to assess the impact of these changes in gene expression. Rapid changes in the transcription of 879 genes occurred in MCs activated by IgE, peaking at 1 hour. Surprisingly, only 12% of these were altered by IgG signaling via FcγRIIb, including numerous transcripts involved in orchestrating type 2 responses linked to spleen tyrosine kinase signaling. Consistent with this finding, IgG suppressed IgE-induced phospho-intermediates in the spleen tyrosine kinase signaling pathway. Invivo studies confirmed that the IgG-mediated suppression of both systemic anaphylaxis and MC-driven tissue recruitment of inflammatory cells following allergen challenge was dependent on FcγRIIb. In contrast, genes in the STAT5a cell survival pathway were unaltered by IgG, and STAT5a phosphorylation increased after IgE-induced MC activation but was unaffected by IgG. Our findings indicate that inhibitory IgG:FcγRIIb signals block an IgE-induced proallergic program but spare a prosurvival program.

THE ROLE OF MAST CELLS IN CARCINOGENESIS (LITERATURE REVIEW)

Mast cells are an important link in the immune system. They are involved in many pathological processes such as stress, inflammation, autoimmune processes and carcinogenesis. The purpose of the review is to summarize the data on the role of mast cells in carcinogenesis. Materials and methods. Review of available literature sources published in Elibrary and PubMed. Results. Tumor growth in the body is accompanied by immune system dysfunction and mast cell response. Mast cells are able to stimulate tumour growth through the secretion of proteases, angiogenic and growth factors, and at the same time have a tumour suppressive effect. The response of the mast cell population depends on the type of tissue from which the tumor is developing, the speed and stage of the process, the localization of the mast cells, and the combination of pro- and anti-tumor factors. During tumour development and growth, total degranulation of mast cells occurs. In addition, mast cells in normal and tumor tissue differ in structure. This article provides information on the role of mast cells in carcinogenesis. Conclusion. Thus, mast cells on the one hand positively affect tumor growth through the synthesis of proteases, growth and angiogenic factors, and on the other hand, act as inhibitors of malignant growth. The response of mastocytes directly depends on the tissue in which tumour develops, on its type and degree of malignancy, the stage of pathological process, localization of mast cells and the degree of their activation, as well as the total balance of pro- and antitumour effects.

GRK2 differentially regulates FcεRI and MRGPRB2-mediated responses in mast cells.

In addition to high-affinity IgE receptor (FcεRI), a subtype of mouse mast cells (MCs) expresses a G protein-coupled receptor known as Mas-related G protein-coupled receptor (GPCR)-B2 (MRGPRB2; human ortholog MRGPRX2). GPCR kinase 2 (GRK2) is a Serine/Threonine kinase that phosphorylates GPCRs to promote their desensitization and internalization. We previously showed that silencing GRK2 expression in mouse bone marrow-derived MCs (BMMCs) blocks IgE-mediated degranulation. Compound 48/80 (C48/80), substance P (SP) and LL-37 cause degranulation in human and mouse MCs via MRGPRX2 and MRGPRB2, respectively. We also reported that C48/80 and SP cause desensitization and internalization of MRGPRX2, but LL-37 does not. Here, we generated mice with MC-specific deletion of Grk2 (Cpa3Cre+/Grk2fl/fl ) to determine its role on IgE-mediated responses and to assess whether it differentially regulates degranulation in response to LL-37, C48/80 and SP. Absence of GRK2 substantially inhibited IgE-mediated tyrosine phosphorylation of STAT5, calcium mobilization, and degranulation in mouse primary lung-derived MCs (PLMCs). By contrast, peritoneal MCs (PMCs) from Cpa3Cre+/Grk2fl/fl mice demonstrated significant enhancement of degranulation in response to C48/80 and SP, but not LL-37. Deletion of Grk2 in MCs attenuated IgE-mediated passive cutaneous anaphylaxis (PCA) and itch but not passive systemic anaphylaxis (PSA). Surprisingly, PSA was significantly reduced in Mrgprb2-/- mice. These findings suggest that GRK2 contributes to PCA and itch but not PSA. By contrast, GRK2 desensitizes MRGPRX2/B2-mediated responses to C48/80 and SP but not LL-37. However, IgE-mediated PSA likely involves the activation of MRGPRB2 by LL-37 or a similar agonist, whose function is resistant to modulation by GRK2.

Hapten-Decorated DNA Nanostructures Decipher the Antigen-Mediated Spatial Organization of Antibodies Involved in Mast Cell Activation.

The immunological response of mast cells is controlled by the multivalent binding of antigens to immunoglobulin E (IgE) antibodies bound to the high-affinity receptor FcεRI on the cell membrane surface. However, the spatial organization of antigen-antibody-receptor complexes at the nanometer scale and the structural constraints involved in the initial events at the cell surface are not yet fully understood. For example, it is unclear what influence the affinity and nanoscale distance between the binding partners involved have on the activation of mast cells to degranulate inflammatory mediators from storage granules. We report the use of DNA origami nanostructures (DON) functionalized with different arrangements of the haptenic 2,4-dinitrophenyl (DNP) ligand to generate multivalent artificial antigens with full control over valency and nanoscale ligand architecture. To investigate the spatial requirements for mast cell activation, the DNP-DON complexes were initially used in surface plasmon resonance (SPR) analysis to study the binding kinetics of isolated IgE under physiological conditions. The most stable binding was observed in a narrow window of approximately 16 nm spacing between haptens. In contrast, affinity studies with FcεRI-linked IgE antibodies on the surface of rat basophilic leukemia cells (RBL-2H3) indicated virtually no distance-dependent variations in the binding of the differently structured DNP-DON complexes but suggested a supramolecular oligovalent nature of the interaction. Finally, the use of DNP-DON complexes for mast cell activation revealed that antigen-directed tight assembly of antibody-receptor complexes is the critical factor for triggering degranulation, even more critical than ligand valence. Our study emphasizes the significance of DNA nanostructures for the study of fundamental biological processes.

Age-related morphofunctional changes of thyroid mast cells under low-intensity laser irradiation (an experimental study)

Purpose: to study the dynamics of morphofunctional parameters of thyroid mast cells under low-intensity laser irradiation depending on age. Material and methods. The experiment was conducted on 96 white male laboratory rats of the Wistar breed. Animals were divided into four groups: 1 – control young, 2 – control old, 3 – young, low-intensity laser irradiation, 4 – old, low-intensity laser irradiation. A single laser irradiation session in continuous mode (wavelength – 970 nm, power – 1 W, exposure – 60 s) was made in the projection of thyroid gland. The animals were removed from the experiment 1 hour and 1, 3 and 7 days after exposure to laser light. Thyroid preparations were fixed in the formalin; histological sections were prepared and stained with toluidine blue; the morphometric analysis was performed to determine the number of thyroid mast cells and their varieties depending on the granular saturation level and degranulation degree.Results. The reaction of thyroid mast cells of experimental animals to laser exposure had some specific features: in young animals there was the increase in the number of cells and in their synthetic activity with the increase in granular saturation level and with the decrease in degranulation level which indicates an increased migration of cells into the thyroid gland and a pronounced adaptive reaction of the entire population of mast cells of the body. In old animals, exposure to laser light caused degranulation activity of thyroid mast cells with decrease in the level of granular saturation. No changes in the number of cells indicates that the reaction is limited within the organ contours.Conclusion. The results obtained expand our understanding of specific reactions of mast cells to laser exposure and confirm the need for individual correction of low-level laser therapy depending on age.

Intrinsic Allergenicity Potential of Salt-Soluble Protein Extracts from the Diploid, Tetraploid and Hexaploid Wheats: Validation Using an Adjuvant-Free Mouse Model

Wheat allergies are potentially life-threatening and, therefore, have become a major health concern at the global level. It is largely unknown at present whether genetic variation in allergenicity potential exists among hexaploid, tetraploid and diploid wheat species. Such information is critical in establishing a baseline allergenicity map to inform breeding efforts to identify hyper-, hypo- and non-allergenic varieties. We recently reported a novel mouse model of intrinsic allergenicity using the salt-soluble protein extract (SSPE) from durum, a tetraploid wheat (Triticum durum). Here, we validated the model for three other wheat species [hexaploid common wheat (Triticum aestivum), diploid einkorn wheat (Triticum monococcum), and the ancient diploid wheat progenitor, Aegilops tauschii], and then tested the hypothesis that the SSPEs from wheat species will exhibit differences in relative allergenicities. Balb/c mice were repeatedly exposed to SSPEs via the skin. Allergic sensitization potential was assessed by specific (s) IgE antibody responses. Oral anaphylaxis was quantified by the hypothermic shock response (HSR). The mucosal mast cell response (MMCR) was determined by measuring mast cell protease in the blood. While T. monococcum elicited the least, but significant, sensitization, others were comparable. Whereas Ae. taushcii elicited the least HSR, the other three elicited much higher HSRs. Similarly, while Ae. tauschii elicited the least MMCR, the other wheats elicited much higher MMCR as well. In conclusion, this pre-clinical comparative mapping strategy may be used to identify potentially hyper-, hypo- and non-allergenic wheat varieties via crossbreeding and genetic engineering methods.

Remibrutinib inhibits hives effector cells stimulated by serum from chronic urticaria patients independently of FcεR1 expression level and omalizumab clinical response.

Despite advances in the treatment of chronic urticaria, in a significant percentage of the patients symptoms are not fully controlled with conventional approaches. New strategies under development include blocking intracellular mediators of mast cell and basophil activation. We aim to investigate the effects of the Bruton's tyrosine kinase (BTK) inhibitor remibrutinib on human blood basophils and CD34+ -derived mast cells activation induced by serum obtained from chronic urticaria patients. Twenty-two patients with chronic spontaneous urticaria (mean age 52years, 27% women) and 22 patients with chronic inducible urticaria (46years, 27% women) were included in the study together with a sex-matched control group. Patients were classified as responders or non-responders to anti-IgE therapy on the basis of their clinical data, FcεR1a expression on blood basophils and total IgE levels. Changes on CD63 expression-as an activation marker-, were used to evaluate in vitro the response of basophils and mast cells to serum exposure and the inhibitory effects of remibrutinib. Remibrutinib inhibits degranulation induced by IgE cross-linking in mast cells and basophils and also the activation triggered by factors present in the sera of spontaneous and inducible chronic urticaria patients. Patient's serum induces a greater degranulation of effector cells than controls. Activation of mast cells and basophils by patient sera and remibrutinib effects were not related to omalizumab responsiveness. Remibrutinib inhibits activation of human basophils and mast cells induced in vitro by exposure to the serum of chronic urticaria patients independently of their response to omalizumab.

House Dust Mite and Cat Dander Extract Induce Asthma-Like Histopathology with an Increase of Mucosal Mast Cells in a Guinea Pig Model.

Asthma is a chronic inflammatory disease with structural changes in the lungs defined as airway remodelling. Mast cell responses are important in asthma as they, upon activation, release mediators inducing bronchoconstriction, inflammatory cell recruitment, and often remodelling of the airways. As guinea pigs exhibit anatomical, physiological, and pharmacological features resembling human airways, including mast cell distribution and mediator release, we evaluated the effect of extracts from two common allergens, house dust mite (HDM) and cat dander (CDE), on histopathological changes and the composition of tryptase- and chymase-positive mast cells in the guinea pig lungs. Guinea pigs were exposed intranasally to HDM or CDE for 4, 8, and 12 weeks, and airway histology was examined at each time point. Hematoxylin and eosin, Picro-Sirius Red, and Periodic Acid-Schiff staining were performed to evaluate airway inflammation, collagen deposition, and mucus-producing cells. In addition, Astra blue and immunostaining against tryptase and chymase were used to visualize mast cells. Repetitive administration of HDM or CDE led to the accumulation of inflammatory cells into the proximal and distal airways as well as increased airway smooth muscle mass. HDM exposure caused subepithelial collagen deposition and mucus cell hyperplasia at all three time points, whereas CDE exposure only caused these effects at 8 and 12 weeks. Both HDM and CDE induced a substantial increase in mast cells after 8 and 12 weeks of challenges. This increase was primarily due to mast cells expressing tryptase, but not chymase, thus indicating mucosal mast cells. We here show that exposure to HDM and CDE elicits asthma-like histopathology in guinea pigs with infiltration of inflammatory cells, airway remodelling, and accumulation of primarily mucosal mast cells. The results together encourage the use of HDM and CDE allergens for the stimulation of a clinically relevant asthma model in guinea pigs.

The exon-skipping oligonucleotide, KitStop, depletes tissue-resident mast cells in vivo to ameliorate anaphylaxis.

Anaphylaxis represents the most extreme and life-threatening form of allergic disease and is considered a medical emergency requiring immediate intervention. Additionally, some people with mastocytosis experience recurrent episodes of anaphylaxis during normal daily activities without exposure to known triggers. While acute therapy consists primarily of epinephrine and supportive care, chronic therapy relies mostly on desensitization and immunotherapy against the offending allergen, which is a time-consuming and sometimes unsuccessful process. These treatments also necessitate identification of the triggering allergen which is not always possible, and thus highlighting a need for alternative treatments for mast cell-mediated diseases. The exon-skipping oligonucleotide KitStop was administered to mice intradermally, intraperitoneally, or systemically at a dose of 12.5 mg/kg. Local mast cell numbers were enumerated via peritoneal lavage or skin histology, and passive systemic anaphylaxis was induced to evaluate KitStop's global systemic effect. A complete blood count and biochemistry panel were performed to assess the risk of acute toxicity following KitStop administration. Here, we report the use of an exon-skipping oligonucleotide, which we have previously termed KitStop, to safely reduce the severity and duration of the anaphylactic response via mast cell depopulation in tissues. KitStop administration results in the integration of a premature stop codon within the mRNA transcript of the KIT receptor-a receptor tyrosine kinase found primarily on mast cells and whose gain-of-function mutation can lead to systemic mastocytosis. Following either local or systemic KitStop treatment, mice had significantly reduced mast cell numbers in the skin and peritoneum. In addition, KitStop-treated mice experienced a significantly diminished anaphylactic response using a model of passive systemic anaphylaxis when compared with control mice. KitStop treatment results in a significant reduction in systemic mast cell responses, thus offering the potential to serve as a powerful additional treatment modality for patients that suffer from anaphylaxis.

Brucella abortus induces mast cell activation through TLR-2 and TLR-4

The Gram-negative bacteria Brucella abortus is a major cause of brucellosis in animals and humans. The host innate immune response to B. abortus is mainly associated with phagocytic cells such as dendritic cells, neutrophils, and macrophages. However, as mast cells naturally reside in the main bacterial entry sites they may be involved in bacterial recognition. At present, little is known about the role of mast cells during B. abortus infection. The role of the innate immune receptors TLR2 and TLR4 in activation of mast cells by B. abortus (strain RB51) infection was analyzed in this study. The results showed that B. abortus did not induce mast cell degranulation, but did induce the synthesis of the cytokines IL-1β, IL-6, TNF-α, CCL3, CCL4, and CCL5. Furthermore, B. abortus stimulated key cell signaling molecules involved in mast cell activation such as p38 and NF-κB. Blockade of the receptors TLR2 and TLR4 decreased TNF-α and IL-6 release by mast cells in response to B. abortus. Taken together, our results demonstrate that mast cells are activated by B. abortus and may play a role in inducing an inflammatory response during the initial phase of the infection.

Changes of local microenvironment and systemic immunity after acupuncture stimulation during inflammation: A literature review of animal studies.

An increasing number of studies have demonstrated the underlying mechanisms by which acupuncture therapy mediates both local and systemic immunomodulation. However, the connection between alterations in the local microenvironment and the resulting change in systemic immunity remains unclear. In this review, we focus on cell-specific changes in local immune responses following acupuncture stimulation and their link to systemic immune modulation. We have gathered the most recent evidence for chemo- and mechano-reactive changes in endothelial cells, neutrophils, macrophages, and mast cells in response to acupuncture. Local signaling is then related to the activation of systemic neuro-immunity including the cholinergic, adrenal, and splenic nervous systems and pain-related neuromodulation. This review aims to serve as a reference for further research in this field.

Acute activation of SERCA with CDN1163 attenuates IgE-mediated mast cell activation through selective impairment of ROS and p38 signaling.

Mast cells are granulocytic immune sentinels present in vascularized tissues that drive chronic inflammatory mechanisms characteristic of allergic pathologies. IgE-mediated mast cell activation leads to a rapid mobilization of Ca2+ from intracellular stores, which is essential for the release of preformed mediators via degranulation and de novo synthesized proinflammatory cytokines and chemokines. Given its potent signaling capacity, the dynamics of Ca2+ localization are highly regulated by various pumps and channels controlling cytosolic Ca2+ concentrations. Among these is sarco/endoplasmic reticulum Ca2+ -ATPase (SERCA), which functions to maintain low cytosolic Ca2+ concentrations by actively transporting cytosolic Ca2+ ions into the endoplasmic reticulum. In this study, we characterized the role of SERCA in allergen-activated mast cells using IgE-sensitized bone marrow-derived mast cells (BMMCs) treated with the SERCA activating compound, CDN1163, and simultaneously stimulated with allergen through FcεRI under stem cell factor (SCF) potentiation. Acute treatment with CDN1163 was found to attenuate early phase mast cell degranulation along with reactive oxygen species (ROS) production. Additionally, treatment with CDN1163 significantly reduced secretion of IL-6, IL-13, and CCL3, suggesting a role for SERCA in the late phase mast cell response. The protective effects of SERCA activation via CDN1163 treatment on the early and late phase mast cell response may be driven by the selective suppression of p38 MAPK signaling. Together, these findings implicate SERCA as an important regulator of the mast cell response to allergen and suggest SERCA activity may offer therapeutic potential targeting allergic pathologies, warranting further investigation.

The impact of physical exertion and man-made environmental factors on lymphoid organs

The athletes' body is exposed not only to intense physical exertion, but also to man–made environmental factors - transport and industrial noise, of which infrasound is an integral part. Infrasound affects the structure of the vascular wall, causing disorders of lymph flow. Intense physical activity is accompanied by adaptive reactions of the body, including the organs of the immune system. The effect of infrasound on the structure of lymph nodes during the recovery period after intense physical exertion was studied. An experimental study was conducted on mesenteric lymph nodes of white rats in the recovery period after intense physical exertion (swimming); the first group of experimental animals underwent a recovery period under normal conditions of detention, the second was exposed to infrasound for 2 weeks after the end of physical exertion. Compensatory reactions are manifested by an increase in the content of tissue basophils in the lymph nodes, markedly pronounced in the second week of the recovery period. The impact of infrasound leads to a violation of lymph flow, which is accompanied by a violation of migration processes in the lymph nodes. Against the background of a decrease in lymphocyte migration, the suppression of lymphopoiesis is sharply pronounced, which is determined throughout the entire observation period. The mast cell reaction in this group of experimental animals is observed only in the fourth week of the recovery period, when the phenomena of oedema begin to subside, and is much less pronounced.