Mast Cell Activation Research Articles

On the pathogenesis of COVID-19: the role of transforming growth factor beta

Proteins of the transforming growth factor beta (TGF-β) family regulate numerous cellular processes that are essential in the pathogenesis of acute respiratory distress syndrome (ARDS), contributing to increased alveolar epithelial permeability, activation of fibroblasts, and extracellular matrix remodeling. TGF-β is involved in the pathogenesis of inflammatory respiratory diseases during the development of COVID-19. SARS-CoV-2 leads to complex immune responses that include the release of inflammatory cytokines, increased activity of mast cells, and the release of mast cell secretome, in particular profibrotic enzymes and cytokines, including TGF-β.Tryptaseand chymase-positive mast cells play a major role in pulmonary fibrosis and embolism in COVID-19. Mast cell chymase is angiotensin-converting enzyme 2-independent due to extracellular formation of angiotensin II in the interstitium; it also activates TGF-β and other molecules, thereby playing a role in tissue remodeling. Mast cell β-tryptase increases the secretion of TGF-β1 by airway smooth muscle tissue and the expression of α-smooth muscle actin (α-SMA). TGF-β also induces the generation of mitochondrial reactive oxygen species (ROS), which enhances the production of ROS in lung fibroblasts. TGF-β is crucial for induing the synthesis of extracellular matrix components by fibroblasts.The review is devoted to the structure of TGF-β, the sources of its secretion and functions, the mechanism of its involvement in the pathogenesis of COVID-19, and the possibility of its use as a prognostic marker of COVID-19 severity.

Ursolic acid attenuates pseudo-allergic reactions via reducing MRGPRX2-mediated mast cell degranulation

Mas-related G protein–coupled receptor X2 (MRGPRX2) is a newly identified receptor on mast cells that contribute to IgE-independent pseudo-allergy. Ursolic acid (UA), a pentacyclic triterpenoid, has been reported for its anti-allergy effects. However, the protective mechanism against pseudo-allergic reactions remains unclear. This study aims to investigate the effects of UA on pseudo-allergic reactions both in vivo and in vitro, focusing on the therapeutical mechanism underlying its effect on mast cells. In present study, UA reduced degranulation and chemokines production induced by MRGPRX2 agonists, including compound 48/80 (C48/80) and substance P (SP), in LAD2 cells in vitro. UA also alleviated C48/80 and SP-induced systemic anaphylaxis and passive cutaneous anaphylaxis (PCA) in vivo. Furthermore, UA demonstrated strong binding affinity to the MRGPRX2 protein, leading to a decrease in calcium influx in both LAD2 cells and MRGPRX2-HEK293 cells stimulated with C48/80 and SP. Moreover, UA effectively suppressed phosphorylation levels within phospholipase C-γ (PLCγ) pathway and nuclear factor kappa-B (NF-κB) pathway of MRGPRX2 downstream proteins. Our findings indicated that UA exerts an attenuating effect in pseudo-allergic reactions by suppressing MRGPRX2-mediated mast cell activation, targeting PLCγ pathway and NF-κB pathway. These results suggest that UA may serve as a promising therapeutic agent for MRGPRX2-dependent pseudo-allergic reactions.

Differential MRGPRX2-dependent activation of human mast cells by polymyxins and octapeptins

The emergence of multi-drug resistant Gram-negative bacteria has led to renewed interest in the antimicrobial activity of polymyxins and novel polymyxin analogues (e.g. nonapeptides and octapeptin). In some individuals, clinically used polymyxins can cause acute hypersensitivity reactions through mast cell activation, with a recent study attributing this effect to activation of the MAS-related G protein-coupled receptor X2 (MRGPRX2). In the present study, HEK293 cells expressing human MRGPRX2 and the human mast cell line LAD2 were used to characterize the activity of the broader family of polymyxins. Octapeptin C4, polymyxin B and colistin produced concentration-dependent calcium mobilization, degranulation, and CCL-2 (MCP-1) release in LAD2 mast cells, with the former being highly potent. CRISPR-Cas9 knockdown of MRGPRX2 in LAD2 cells and a MRGPRX2 inverse agonist caused a significant reduction in calcium mobilization, degranulation, and CCL-2 release, demonstrating dependency on MRGPRX2 expression. In contrast, polymyxin nonapeptides were far less potent calcium mobilisers and failed to induce functional degranulation in LAD2 cells. Our results confirm that activation of mast cells induced by polymyxin-related antibiotics is MRGPRX2-dependent and reveal that octapeptin C4 might be more liable, whilst nonapeptides are less liable, to trigger immediate hypersensitivity reactions clinically. The mechanism underpinning the difference in MRGPRX2 activation between polymyxin-related antibiotics is important to better understand as it may help design new, safer polymyxins and guide the optimal clinical use of existing polymyxin drugs.

Mast Cells Mediate Acute Inflammatory Responses After Glenoid Labral Tears and Can Be Inhibited With Cromolyn in a Rat Model

Background: Injuries to the glenoid labrum have been recognized as a source of joint pain and discomfort, which may be associated with the inflammatory responses that lead to the deterioration of labral tissue. However, it is unclear whether the torn labrum prompts mast cell (MC) activation, resulting in synovial inflammatory responses that lead to labral tissue degeneration. Purpose: To determine the potential influence of activated MC on synovial inflammatory responses and subsequent labral tissue degeneration and shoulder function deterioration in a rat model by monitoring MC behavior and sequential inflammatory responses within the synovial tissue and labral tissue after injury, suture repair, and MC stabilizer administration. Study Design: Controlled laboratory study. Methods: Anteroinferior glenoid labral tears were generated in the right shoulder of rats (n = 20) and repaired using a tunneled suture technique. Synovial tissue inflammatory responses were modulated in some rats with intraperitoneal administration of an MC stabilizer—cromolyn (n = 10). At weeks 1 and 3, MC activation, synovial inflammatory responses, and labral degeneration were histologically evaluated. Simultaneously, gait analysis was performed before and after surgical repair to assess the worsening of the shoulder function after the injury and treatment. Results: Resident MC degranulation after labral injury (50.48% ± 8.23% activated at week 1) contributed to the initiation of synovial tissue inflammatory cell recruitment, inflammatory product release, matrix metalloproteinase-13, and subsequent labral tissue extracellular matrix degeneration. The administration of cromolyn, an MC stabilizer, was found to significantly diminish injury-mediated inflammatory responses (inflammatory cell infiltration and subsequent proinflammatory product secretion) and improve shoulder functional recovery. Conclusion: MC activation is responsible for labral tear–associated synovial inflammation and labral degeneration. The administration of cromolyn can significantly diminish the cascade of inflammatory reactions after labral injury. Clinical Relevance: Our findings support the concept that MC stabilizers may be used as a complementary therapeutic option in the treatment and repair of labral tears.

Characterization of the cellular components of mouse collecting lymphatic vessels reveals that lymphatic muscle cells are the innate pacemaker cells regulating lymphatic contractions.

Collecting lymphatic vessels (cLVs) exhibit spontaneous contractions with a pressure-dependent frequency, but the identity of the lymphatic pacemaker cell is still debated. By analogy to pacemakers in the GI and lower urinary tracts, proposed cLV pacemaker cells include interstitial cells of Cajal like cells (ICLC) or the lymphatic muscle (LMCs) cells themselves. Here we combined immunofluorescence and scRNAseq analyses with electrophysiological methods to examine the cellular constituents of the mouse cLV wall and assess whether any cell type exhibited morphological and functional processes characteristic of pacemaker cells: a continuous if not contiguous network integrated into the electrical syncytium; spontaneous Ca2+ transients; and depolarization-induced propagated contractions. We employed inducible Cre (iCre) mouse models routinely used to target these specific cell populations including: c-kitCreER T2 to target ICLC; PdgfrβCreER T2 to target pericyte-like cells; PdgfrαCreER ™ to target CD34+ adventitial cells and ICLC; and Myh11CreER T2 to target LMCs directly. These specific inducible Cre lines were crossed to the fluorescent reporter ROSA26mT/mG, the genetically encoded Ca2+ sensor GCaMP6f, and the light-activated cation channel rhodopsin2 (ChR2). c-KitCreER T2 labeled both a sparse population of LECs and round adventitial cells that responded to the mast cell activator compound 48-80. PdgfrβCreER T2 drove recombination in both adventitial cells and LMCs, limiting its power to discriminate a pericyte-specific population. PdgfrαCreER ™ labeled a large population of interconnected, oak leaf-shaped cells primarily along the adventitial surface of the vessel. Of these cells, only LMCs consistently, but heterogeneously, displayed spontaneous Ca2+ events during the diastolic period of the contraction cycle, and whose frequency was modulated in a pressure-dependent manner. Optogenetic depolarization through the expression of ChR2 under control of Myh11CreER T2 , but not PdgfrαCreER ™ or c-KitCreER T2 , resulted in propagated contractions upon photo-stimulation. Membrane potential recordings in LMCs demonstrated that the rate of diastolic depolarization significantly correlated with contraction frequency. These findings support the conclusion that LMCs, or a subset of LMCs, are responsible for mouse cLV pacemaking.

Mast cells promote choroidal neovascularization in a model of age-related macular degeneration

‘Wet’ age-related macular degeneration (AMD) is characterized by pathologic choroidal neovascularization (CNV) that destroys central vision. Abundant evidence points to inflammation and immune cell dysfunction in the progression of CNV in AMD. Mast cells are resident immune cells that control the inflammatory response. Mast cells accumulate and degranulate in the choroid of patients with AMD, suggesting they play a role in CNV. Activated mast cells secrete various biologically active mediators, including inflammatory cytokines and proteolytic enzymes such as tryptase. We investigated the role of mast cells in AMD using a model of CNV. Conditioned media from activated mast cells exerts proangiogenic effects on choroidal endothelial cells and choroidal explants. Laser-induced CNV in vivo was markedly attenuated in mice genetically depleted of mast cells (KitW−sh/W−sh) and in wild-type mice treated with mast cell stabilizer, ketotifen fumarate. Tryptase was found to elicit pronounced choroidal endothelial cell sprouting, migration and tubulogenesis; while tryptase inhibition diminished CNV. Transcriptomic analysis of laser-treated RPE/choroid complex revealed collagen catabolism and extracellular matrix (ECM) reorganization as significant events correlated in clusters of mast cell activation. Consistent with these analyses, compared to wildtype mice choroids of laser-treated mast cell-deficient mice displayed less ECM remodelling evaluated using collagen hybridizing peptide tissue binding. Findings herein provide strong support for mast cells as key players in the progression of pathologic choroidal angiogenesis and as potential therapeutic targets to prevent pathological neovascularization in ‘wet’ AMD.

Altered B-cell, plasma cell and antibody immune profiles in blood of systemic mastocytosis

Systemic mastocytosis (SM) is a heterogeneous disease characterized by an expansion of KIT-mutated constitutively activated mast cells (MCs) that release MC mediators, which might act on the tumor microenvironment including other immune cells. To investigate the blood distribution of B-cell, plasma cell (PC), and antibody isotype compartments in patients with SM. We used spectral flow cytometry and the EuroFlow Immunomonitoring panel and Lymphocyte Screening Tube to quantify B cells, PCs, and their subsets in blood of 108 patients with SM (35 bone marrow mastocytosis [BMM] cases, 64 indolent SM [ISM] cases, 9 aggressive SM [ASM] cases) versus 117 age-matched healthy donors and paired bone marrow samples of 31 patients with SM versus 17 controls, respectively. In parallel, IgM, IgD, IgG, IgA, and IgE plasma levels were measured. Compared with healthy donors, patients with SM showed increased immature B-cell production in bone marrow (P= .003) associated with greater release of pre-germinal center immature (P< .001) and naive CD5+ B lymphocytes (P< .001) to blood, but a pronounced decrease in PC counts of all different IgH isotypes and subclasses (P≤ .001) together with overall increased IgM (P= .001) and IgD (P< .001) plasma levels. Different immune profiles were found per diagnostic subtype of disease with progressively greater counts in blood of immature B lymphocytes together with decreased IgMD+, IgG2+, IgA1+, and IgA2+ memory B cells (P≤ .032) and elevated IgM (P= .017) plasma levels in cases of ASM, increased IgM (P= .001) and IgD (P= .001) plasma levels in ISM cases, and exacerbated IgE (P< .001) with decreased IgG (P= .008) plasma levels in BMM cases. Our results reveal a significant dysregulation of the B-cell and PC compartments in blood of patients with SM, consistent with distinctly altered antibody isotype profiles in plasma of patients with BMM versus ISM versus ASM.

Involvement of interferon γ-producing mast cells in immune responses against melanocytes in vitiligo requires MrgX2 activation.

Increasing evidence indicates that oxidative stress and interferon γ (IFNγ)-driven cellular immune responses are responsible for the pathogenesis of vitiligo. However, the connection between oxidative stress and the local production of IFNγ in early vitiligo remains unexplored. The aim of this study was to identify the mechanism underlying the production of IFNγ by mast cells and its impact on vitiligo pathogenesis. Skin specimens from the central, marginal, and perilesional skin areas of active vitiligo lesions were collected to characterize changes of mast cells, CD8+ T cells, and IFNγ-producing cells. Cell supernatants from hydrogen peroxide (H2O2)-treated keratinocytes (KCs) were harvested to measure levels of soluble stem cell factor (sSCF) and matrix metalloproteinase (MMP)-9. A murine vitiligo model was established using Mas-related G protein-coupled receptor-B2 (MrgB2, mouse ortholog of human MrgX2) conditional knockout (MrgB2-/-) mice to investigate IFNγ production and inflammatory cell infiltrations in tail skin following the challenge with tyrosinase-related protein (Tyrp)-2 180 peptide. Potential interactions between the Tyrp-2 180 peptide and MrgX2 were predicted using molecular docking. The siRNAs targeting MrgX2 and the calcineurin inhibitor FK506 were also used to examine the signaling pathways involved in mast cell activation. IFNγ-producing mast cells were closely aligned with the recruitment of CD8+ T cells in the early phase of vitiligo skin. sSCF released by KCs through stress-enhanced MMP9-dependent proteolytic cleavage recruited mast cells into sites of inflamed skin (Perilesion vs. lesion, 13.00 ± 4.00/HPF vs. 26.60 ± 5.72/HPF, P <0.05). Moreover, IFNγ-producing mast cells were also observed in mouse tail skin following challenge with Tyrp-2 180 (0 h vs. 48 h post-recall, 0.00 ± 0.00/HPF vs. 3.80 ± 1.92/HPF, P <0.05). The IFNγ+ mast cell and CD8+ T cell counts were lower in the skin of MrgB2-/-mice than in those of wild-type mice (WT vs. KO 48 h post-recall, 4.20 ± 0.84/HPF vs. 0.80 ± 0.84/HPF, P <0.05). Mast cells activated by MrgX2 serve as a local IFNγ producer that bridges between innate and adaptive immune responses against MCs in early vitiligo. Targeting MrgX2-mediated mast cell activation may represent a new strategy for treating vitiligo.

Neoadjuvant chemotherapy induces phenotypic mast cell changes in high grade serous ovarian cancer

BackgroundHigh grade serous ovarian cancer (HGSOC) is the most lethal gynecologic malignancy in which patients have still yet to respond meaningfully to clinically available immunotherapies. Hence, novel immune targets are urgently needed. Our past work has identified that mast cells are significantly upregulated at the mRNA level in HGSOC patient tumors following neoadjuvant chemotherapy (NACT) exposure. Therefore, in this current investigation we sought to characterize intratumoral mast cell phenotypic changes as a result of NACT exposure and determine how these adaptations are associated with patient clinical outcomes.MethodsHematologic immunohistochemistry was employed to determine mast cell levels in 36 matched pre- and post-NACT HGSOC patient tumors. Fluorescent Immunohistochemistry was utilized to identify Tryptase+(carboxypeptidase A3 (CPA3) + mast cells as well as histamine levels in 29 and 20, respectively, matched pre- and post-NACT HGSOC patient tumors. Finally, human immortalized mast cells, LUVA were stimulated with carboplatin and paclitaxel and genomic changes were analyzed by quantitative PCR.ResultsHematologic labeled intratumoral mast cells were significantly upregulated in the intraepithelial and stromal regions of the tumor, post-NACT. Lower levels of pre-NACT mast cells were significantly associated with an improved progression-free survival (PFS). Histamine, a marker of mast cell degranulation was similarly upregulated in post-NACT exposed tumors. Through the characterization of mast cell specific proteases Tryptase and CPA3, it was found that Tryptase+/ CPA3 + mast cells were significantly upregulated both in the intraepithelial and stromal compartments of the tumor, while Tryptase + cells were significantly upregulated in the stromal regions of the tumor. Lower post-NACT treated levels with Tryptase+/ CPA3 + cells were significantly associated with improved overall survival (OS) and PFS while higher Tryptase + mast cells were associated with improved OS. Finally, following chemotherapy exposure mast cell activating factors AREG and CCL2 were significantly upregulated while TGFB1, an inhibitor of mast cell activation was downregulated in LUVA cells.ConclusionsEnhanced mast cell numbers, as well as activation and degranulation are a consequence of NACT exposure. Post-NACT mast cells displayed differing associations with survival outcomes that was dependent upon granule classification. Ultimately, mast cells represent a clinically relevant putative HGSOC immune target.

Clinical utility analysis of the Hoxb8 mast cell activation test for the diagnosis of peanut allergy.

Peanut allergy is among the most severe and common food allergies. The diagnosis has a significant impact on the quality of life for patients and their families. An effective management approach depends on accurate, safe, and easily implementable diagnostic methods. We previously developed a cell-based assay using Hoxb8 mast cells (Hoxb8 MCs) aimed at improving clinical allergy diagnosis. In this study, we assessed its diagnostic performance by measuring blinded sera from a prospectively enrolled and pre-validated peanut allergy cohort. Hoxb8 MCs were passively sensitized with sera from peanut-allergic and peanut tolerant children and adolescents (n = 112). Degranulation of Hoxb8 MCs was quantified upon stimulation with dose-titrated peanut extract by means of flow cytometry, using CD107a as activation marker. The results from the Hoxb8 mast cell activation test (Hoxb8 MAT) were compared to established diagnostic assays such as the skin prick test (SPT), specific IgE (sIgE) levels, and the basophil activation test (BAT). Additionally, serum samples from BAT nonresponders were assessed with the Hoxb8 MAT. Hoxb8 MAT displayed a robust dose-dependent activation to peanut extract, with a cutoff value of ≤5.2% CD107a positive cells. The diagnostic accuracy was highest at allergen concentrations ≥100 ng/mL, with an area under the receiver operating characteristic curve (AUROC) of 0.97, 93% sensitivity, and 96% specificity, outperforming traditional SPT and sIgE tests. When compared to BAT, Hoxb8 MAT exhibited comparable diagnostic efficacy. Moreover, sera from BAT nonresponders were accurately classified into allergics and nonallergics by the Hoxb8 MAT. The Hoxb8 MAT demonstrated a very good diagnostic precision in patients prospectively assessed for peanut allergy comparable to the fresh whole blood-based BAT. Additionally, it demonstrated its value for accurate classification of BAT nonresponders into allergic and nonallergic individuals. Further investigations into its utility in the routine clinical setting are warranted.

Transactivation DNA-binding protein-related genes were associated with salivary gland injury in primary Sjögren syndrome.

The purpose was to identify transactivation DNA-binding protein-related genes in salivary gland injury in primary Sjögren syndrome (pSS) in southwest China. We downloaded the datasets of GSE7451, GSE23117, and GSE40611. In order to screen the candidate genes, 2 kinds of machine learning algorithms were used. We collected blood from 28 patients and 20 controls to verify the expression of candidate genes using quantitative real-time polymerase chain reaction. The receiver operating characteristic curve was used to evaluate the diagnostic efficiency. Correlations between candidate genes and immune cells were examined. A total of 31 differentially expressed genes were obtained. Through different algorithms, 6 genes including IFIT1, CSF2RB, TRIM22, PPM1H, VAMP7, and C21orf2 were getted. Validation results suggested that the expression of CSF2RB, VAMP7, IFIT1, C21orf2, and TRIM22 was significantly increased in pSS. The area under the curve of CSF2RB was 0.937 and that of TRIM22 was 0.915. Immune infiltration analysis showed that the percentage of activated mast cells was lower than the controls (P = .025). Correlation analysis suggested that CSF2RB was associated with immune cell infiltration. The expression of CSF2RB was significantly upregulated, which could be related to the increase of γδ T cells. We revealed that CSF2RB could be the candidate gene of pSS. CSF2RB was involved by regulating various immune cells. The expression of CSF2RB was significantly upregulated, which was related to the increase of γδ T cells.

Tryptase levels in children with cutaneous mastocytosis: a prospective study

BACKGROUND: Serum tryptase levels are used as a diagnostic marker in mastocytosis and are considered an indicator of clonal mast cell (MC) load. AIMS: To analyze tryptase levels in children with different clinical types of cutaneous mastocytosis. MATERIALS AND METHODS:A single-center prospective study was conducted for the period 2022-2024. The results of examination of 202 children aged from 6 months to 17 years with a diagnosis of cutaneous mastocytosis, who were undergoing outpatient treatment at the Moscow scientific and practical Center of dermatovenereology and cosmetology, were analyzed. Serum tryptase levels were determined by enzyme immunoassay. RESULTS:The median basal tryptase level for the entire group (n=202) was 5.09 μg/L (range 1.3–57.0 μg/L). Serum tryptase values exceeding 11.0 μg/L were detected in 17.3% of patients, and 20.0 μg/L in 7.4%. The mean enzyme level in the control group was 2.55 μg/L. There were significant differences in tryptase concentrations between the maculopapular cutaneous mastocytosis (MPCM) and control groups (p=0.05). The median tryptase level in children with MPCM was 8.7 μg/L. The most pronounced differences were observed between the enzyme levels in children with the monomorphic type of MPCM and in the control group (p=0.01). Analysis of tryptase levels depending on gender and clinical type of MPCM showed that children and adolescents with the monomorphic type of MPCM had higher enzyme levels. CONCLUSIONS: Further studies are needed to determine which tryptase levels in children are indicative of MC activation and primary MC diseases. A detailed understanding of tryptase levels in children may facilitate the development of new specific therapeutic approaches to the management of various clinical forms of cutaneous mastocytosis.

Targeting mast cell activation alleviates anti-MHC I antibody and LPS-induced TRALI in mice by pharmacologically blocking the TLR3 and MAPK pathway

Transfusion-related lung injury (TRALI) poses a significant risk following blood transfusion and remains the primary cause of transfusion-related morbidity and mortality, primarily driven by the activation of immune cells through anti-major histocompatibility complex class I (anti-MHC I) antibody. However, it remains to be defined how immune microenvironmental cue contributes to TRALI. Here, we uncover that activated mast cells within the immune microenvironment promote lung inflammation and injury in antibody-mediated TRALI, both in vitro and in vivo. This was demonstrated by co-culturing lipopolysaccharide (LPS)-pretreated mast cell line with anti-MHC I antibody and establishing a “two-hit” TRALI mouse model through intratracheal injection of LPS followed by tail-vein injection of anti-MHC I antibody. Importantly, mast cell-deficient KitW-sh/W-sh mice exhibited markedly reduced lung inflammation and injury responses in antibody-mediated TRALI compared with wild-type mice. Mechanistically, activation of toll-like receptor 3 (TLR3)/mitogen-activated protein kinase (MAPK) signaling pathway in mast cells contributes to the enhanced production of proinflammatory factors. These excessive proinflammatory factors produced by activated mast cells contribute to lung inflammation and injury in antibody-mediated TRALI. Pharmacologically targeting the TLR3/MAPK pathway to inhibit mast cell activation normalizes the proinflammatory microenvironment and alleviates lung inflammation and injury in the preclinical TRALI mouse model. Overall, we find that activation of mast cells via the TLR3/MAPK pathway contributes to lung inflammation and injury in antibody-mediated TRALI, providing novel insights into its underlying mechanisms. Furthermore, targeting activated mast cells and the associated pathway offers potential therapeutic strategies for antibody-mediated TRALI.

Clinical factors as predictors of the development of severe recurrence of chronic spontaneous urticaria after completion of omalizumab therapy

Chronic spontaneous urticaria (CSU) affects about 1% of population, and its prevalence is increasing. The disease occurs in both children and adults, with predominance among women. At least two possible causes of CSU have been identified, two autoimmune endotypes, with different types of autoantibodies associated with activation of skin mast cells. In clinical practice, patients with CSU receive therapy accordance the clinical recommendations of the Ministry of Health of Russia for treatment of urticaria, according to the doctor’s algorithm of actions. In patients with CSU, symptoms are difficult to relieve due to special mechanisms of development this variant of disease. In recent years, specific markers, including clinical and laboratory parameters, have been described that can predict response to treatment patients with CSU. In clinical practice, we encounter difficulties in managing these patients. One of these is recurrence of urticaria symptoms after cessation of omalizumab treatment, which negatively affects compliance of patients and its psycho-emotional background. A retrospective analysis of 14 patients with CSU with resumption symptoms after completion of omalizumab treatment was carried out. Patients were divided into two groups: 1 group – 10 patients that symptoms began controlled with antihistamines (go to 1st therapy stage); and 2 group – 4 patients who need re-prescription of omalizumab (stay on 3rd treatment stage). The duration of CSU, activity according to UAS7, combination with development of angioedema, presence of concomitant allergic and autoimmune pathologies, level of CRP, total IgE, and presence of TPO antibodies were analyzed. There was no tendency relapses severity CSU after omalizumab discontinuation with age, gender, duration of the disease, presence of concomitant allergic diseases and drug hypersensitivity. In patients with high disease activity was tendency toward more severe relapses of CSU. The search and study of predictors response to treatment of CSC remains actual task. Further research to identify predictors of response to treatment and relapses severity help identify groups of patients for early transition to more effective treatment methods, which optimize and personalize management of patients with CSU.

Mast cells as indicators of foreign particle biocompatibility

The key problem of introducing nanoparticles into clinical practice for diagnostic and therapeutic purposes is their safety. Connective tissue, an important component of which are mast cells, reacts actively in response to foreign particles. The reaction of mast cells can be an indicator of the biocompatibility of foreign particles. The study was conducted on male Wistar rats. Iron-carbon nanoparticles in the FeC modification stabilized in an aqueous medium using an auxiliary substance were used. Tissue examination (liver, lungs, heart, thymus, kidneys) was performed 1, 7 and 30 days after injection. After the injection of nanoparticles, the largest quantity of them is found in the liver and lungs, a smaller quantity is found in the heart, kidneys and thymus. The liver and lungs are the main organs of excretion of nanoparticles due to phagocytes. The accumulation of nanoparticles in the liver leads to the development of destructive processes and to the activation of compensatory and adaptive mechanisms in the form of cellular and intracellular regeneration of hepatocytes. In organs with a low content of nanoparticles, structural changes are poorly expressed. The mast cells of the studied organs react differently to the introduction of nanoparticles. The first to react are the mast cells of the liver by reducing the quantity and increasing degranulation. The population of lung mast cells reacts unidirectionally by sharply activating degranulation without changing the amount. An increase in the secretory activity of mast cells in the lungs and liver indicates the participation of mast cells in the regulation of particle elimination through intercellular signaling pathways of interaction with the system of phagocytic mononuclear cells. Heart mast cells are involved in maintaining the inflammatory process in the early period of the experiment, contribute to the return of myocardial parameters to homeostatic norm in the late period of the experiment. Mast cells can be considered as indicators of biocompatibility nanoparticles. The absence of an inflammatory process and the preservation of the structural and functional characteristics of the tissues where nanoparticles accumulate, as well as the reaction of mast cells in them, indicate the relative safety of the particles under study.

No signs of mast cell involvement in long-COVID: Acase-control study.

Long-COVID caused by SARS-CoV-2 infection has significant and increasing effects on human health worldwide. Although a unifying molecular or biological explanation is lacking, several pathophysiological mechanisms have been proposed. Involvement of mast cells-evolutionary old "multipurpose" innate immune cells-was reported recently in studies of acute infection and post-acute-COVID-19 syndrome. Mast cell activity has been suggested in long-COVID. In this case-control study, we compared data from 24 individuals with long-COVID (according to the NICE criteria) and 24 age- and sex-matched healthy individuals with a history of SARS-CoV-2 infection without developing sequelae. Serum levels of the proteases beta-tryptase (TPSB2) and carboxypeptidase (CPA3), which are mast cell specific, were measured using immunoassays. The values were compared between the two groups and correlated to measures of physical exertional intolerance. TPSB2 and CPA3 levels were median (range) 26.9 (2.0-1000) and 5.8 (1.5-14.0) ng/mL, respectively, in the long-COVID group. The corresponding values in the control group were 10.9 (2.0-1000) (p = 0.93) and 5.3 (3.5-12.9) ng/mL (p = 0.82). No significant correlations between TPSB2 or CPA3 levels and scores on the ten physical subscales of SF-36, 3.1-3.10 were revealed. We found no significant differences in the levels of mast cell activation markers TPSB2 and CPA3 between the long-COVID and control groups and no correlations with proxy markers of exercise intolerance. Mast cell activation does not appear to be part of long-term pathogenesis of long-COVID, at least in the majority of patients.

Nebivolol hydrochloride and its impurities induce pseudo-allergic reactions via mast cell activation.

Nebivolol hydrochloride is a third-generation β-blocker commonly used to treat cardiovascular diseases. However, it has been reported to induce allergic reactions in clinical use which deserves much attention. Therefore, this study focused on the ability of two isomers of nebivolol and chiral isomer impurities to induce allergic reactions. Our findings demonstrate that both nebivolol and two isomeric impurities can activate mast cell degranulation in vitro and show significant retention on Mas-related G-protein-coupled receptor X2 (MRGPRX2)-HEK293 cell membrane chromatography. These effects were further validated in vivo, where nebivolol and impurity IP-3 were observed to cause toe swelling and mast cell degranulation in mice. Molecular docking studies revealed interactions between these compounds and key amino acids of MRGPRX2, suggesting a mechanism for the induced allergic reactions. This work lays the foundation for improving the clinical safety of nebivolol.

Identification and validation of endoplasmic reticulum stress-related genes in patients with steroid-induced osteonecrosis of the femoral head

Steroid-induced osteonecrosis of the femoral head (SONFH) is a debilitating condition caused by long-term corticosteroid use, leading to impaired blood flow and bone cell death. The disruption of cellular processes and promotion of apoptosis by endoplasmic reticulum stress (ERS) is implicated in the pathogenesis of SONFH. We identified ERS-associated genes in SONFH and investigated their potential as therapeutic targets. We analysed the GSE123568 GEO dataset to identify differentially expressed genes (DEGs) related to ERS in SONFH. We conducted Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, identified hub genes by protein-protein interaction (PPI) analyses, and evaluated their functions by gene set enrichment analysis (GSEA). We constructed mRNA–miRNA networks, identified potential therapeutics, and assessed immune cell infiltration. We performed cross-validation using the GEO dataset GSE74089, qRT-PCR on clinical samples from patients with SONFH and controls, and a receiver operating characteristic (ROC) curve analysis to assess the diagnostic performance of the hub genes. We identified 195 ERS-related genes in SONFH, which were primarily involved in oxidative stress, immune responses, and metabolic pathways. The PPI network suggested CXCL8, STAT3, IL1B, TLR4, PTGS2, TLR2, CASP1, CYBB, CAT, and HOMX1 to be key hub genes, which were shown by GSEA to be involved in biological pathways related to metabolism, immune modulation, and cellular integrity. We also identified 261 microRNAs (miRNAs) as well as drugs such as dibenziodolium and N-acetyl-L-cysteine that modulated inflammatory responses in SONFH. Twenty-two immune cell subtypes showed significant correlations, such as a positive correlation between activated mast cells and Tregs, and patients with SONFH had fewer dendritic cells than controls. The hub genes CYBB and TLR4 showed significant correlations with M1 macrophages and CD8 T cells, respectively. Cross-validation and qRT-PCR confirmed the upregulation of STAT3, IL1B, TLR2, and CASP1 in patients with SONFH, validating the bioinformatics findings. An ROC curve analysis confirmed the diagnostic potential of the hub genes. The top 10 hub genes show promise as ERS-related diagnostic biomarkers for SONFH. We discovered that 261 miRNAs, including hsa-miR-23, influence these genes and identified potential therapeutics such as dibenziodolium and simvastatin. Immune profiling indicated altered immune functions in SONFH, with significant correlations among immune cell types. Validation confirmed the upregulation of STAT3, IL1B, TLR2 and CASP1, which had diagnostic potential. The findings suggest potential diagnostic markers and therapeutic targets for SONFH.

Mastocytoma and juvenile xanthogranuloma in children

The growing number of children with rare diseases such as cutaneous mastocytoma and juvenile xanthogranuloma turning to dermatologists, as well as their clinical similarity, dictate the need for specialists to pay careful attention to these diseases. cutaneous mastocytoma is a clinical form of cutaneous mastocytosis. According to the WHO classification (2022), isolated (one focus) and multiple cutaneous mastocytoma (no more than three foci) are distinguished. juvenile xanthogranuloma belongs to the group of non-Langerhans cell histiocytosis, a broad group of related diseases characterized by the proliferation of histiocytes other than Langerhans cells. We describe a case of an unusual clinical course of solitary juvenile xanthogranuloma in a 3-year-old boy referred to Moscow Scientific and Practical Center of Dermatovenereology and Cosmetology with suspected cutaneous mastocytoma. The size, unusual shape, localization of the lesion and elevated levels of serum tryptase exceeding the age norm (&lt;5 μg/l) determined the atypicality of this case. Dermoscopic examination revealed a central deep yellow coloration of the lesion in the center (the setting sun symptom), a vascular pattern and a clouds symptom. Pathological examination confirmed the diagnosis of juvenile xanthogranuloma. The article also reflects the results of a dynamic observation of a child with an isolated large-sized cutaneous mastocytoma. During the examination, an increase in tryptase levels (&gt;20 μg/l), and AST values, as well as ultrasound signs of hepatomegaly were revealed. Features of the dermoscopic and pathomorphological picture demonstrated patterns characteristic of infiltration and increased activity of mast cells. Cutaneous mastocytoma and juvenile xanthogranuloma are rare and benign skin diseases that usually begin in childhood. Diagnosis of rare diseases often requires complex differential diagnosis. Features of the modern course of cutaneous mastocytoma and juvenile xanthogranuloma are an atypical clinical picture and a high risk of developing extracutaneous symptoms. The presented clinical cases demonstrate the need for interdisciplinary monitoring of patients with these diseases and change the stereotypes of treating them as independent and regressive processes without a trace.

Energy metabolism-related GLUD1 contributes to favorable clinical outcomes of IDH-mutant glioma

BackgroundGlioma is the most common brain tumor. IDH mutations occur frequently in glioma, indicating a more favorable prognosis. We aimed to explore energy metabolism-related genes in glioma to promote the research and treatment.MethodsDatasets were obtained from TCGA and GEO databases. Candidate genes were screened by differential gene expression analysis, then functional enrichment analysis was conducted on the candidate genes. PPI was also carried out to help determine the target gene. GSEA and DO analysis were conducted in the different expression level groups of the target gene. Survival analysis and immune cell infiltrating analysis were performed as well.ResultsWe screened 34 candidate genes and selected GLUD1 as the target gene. All candidate genes were significantly enriched in 10 KEGG pathways and 330 GO terms. GLUD1 expression was higher in IDH-mutant samples than IDH-wildtype samples, and higher in normal samples than tumor samples. Low GLUD1 expression was related to poor prognosis according to survival analysis. Most types of immune cells were negatively related to GLUD1 expression, but monocytes and activated mast cells exhibited significantly positive correlation with GLUD1 expression. GLUD1 expression was significantly related to 119 drugs and 6 immune checkpoint genes. GLUD1 was able to serve as an independent prognostic indicator of IDH-mutant glioma.ConclusionIn this study, we identified an energy metabolism-related gene GLUD1 potentially contributing to favorable clinical outcomes of IDH-mutant glioma. In glioma, GLUD1 related clinical outcomes and immune landscape were clearer, and more valuable information was provided for immunotherapy.