Human Mast Cells Research Articles

The importance of mast cell histamine secretion in IgG-mediated systemic anaphylaxis.

IgG can mediate murine and human systemic anaphylaxis (SA). The roles of mast cells (MCs) and histamine in IgG-mediated anaphylaxis are controversial for mice and have not been studied in vivo for humans. We now investigate these issues. Actively or passively sensitized wild-type and immune-deficient mice were induced to develop anaphylaxis by i.v. antigen challenge. Anaphylaxis was characterized by evaluating hypothermia, hypomobility, histamine, and mast cell protease responses. In contrast to our previous results with protein-immunized mice from a conventional colony, IgG-mediated passive SA in our SPF colony mice depended considerably on histamine produced by connective tissue MCs (CTMCs) in response to FcγRIII crosslinking. This was found for C57BL/6 and young male and female BALB/c mice, including BALB/c mice freshly arrived from 3 vendors. IgG-mediated anaphylaxis was less histamine-dependent in old than young mice. Although both mucosal MC (MMC) and CTMC responses were severely depleted in c-kit-deficient mice, MMC responses depended considerably more than CTMC responses on c-kit for maintenance. In immunologically naïve mice, FcγRIII crosslinking strongly activated a subset of CTMCs, but had little ability to activate MMCs. In vivo LPS + poly I.C treatment decreased histamine-dependence of IgG-mediated anaphylaxis while a strong Th2 immune response increased FcγRIII crosslinking-induced MMC activation. IgG-mediated activation of human MCs in reconstituted immunodeficient mice induced histamine-dependent anaphylaxis. IgG-dependent SA can be mediated largely by histamine released by mouse CTMCs and human MCs; histamine dependence is influenced by mouse age, sex, immune and infectious history, and the anaphylaxis model studied.

Targeting of the IL-5 pathway in severe asthma reduces mast cell progenitors

BackgroundTherapies targeting interleukin-5 (IL-5) or its receptor (IL-5Rα) are currently used to treat patients with severe eosinophilic asthma. ObjectiveTo investigate the impact of anti-IL-5 and anti-IL-5Rα biological therapies on mast cells (MCs) and their progenitors. MethodsSurface IL-5Rα expression was investigated on MCs and their progenitors in mouse lungs and bone marrow, and in human lungs and blood. Isolated human MC progenitors cultured in the presence or absence of IL-5 were analyzed in vitro. Circulating MC progenitors were quantified in patients with severe asthma, before and after anti-IL-5 (mepolizumab) or anti-IL-5Rα (benralizumab) therapy. Gene expression analysis of MC progenitors was performed before and after anti-IL-5Rα therapy. ResultsApproximately 50% of the human primary lung MCs, and 30% of the human MC progenitors from individuals with allergic asthma expressed IL-5Rα. In patients with mild-to-moderate allergic asthma and mice with acute allergic airway inflammation, the fraction of IL-5Rα + MC progenitors was elevated. Additionally, IL-5 promoted the proliferation and/or survival of isolated human MC progenitors. Further, patients with severe asthma from two independent cohorts demonstrated a reduction of blood MC progenitors after anti-IL-5 or anti-IL-5Rα treatment. This was associated with improved asthma control, as well as a decline in both blood eosinophils and Th2 cells. Finally, the blood MC progenitors remaining after anti-IL-5Rα (benralizumab) treatment exhibited a downregulated expression of genes involved in growth and proliferation. ConclusionThis study introduces the possibility that the clinical effects of targeting IL-5/IL-5Rα in severe asthma also may involve reduction of MC populations.

Neuroplasticity and neuroimmune interactions in fatal asthma.

Alteration of airway neuronal function and density and bidirectional interaction between immune cells and sensory peripheral nerves have been proposed to trigger and perpetuate inflammation that contribute to asthma severity. To date, few studies analysed neuroplasticity and neuroinflammation in tissue of asthmatic individuals. We hypothesized that the presence of these phenomena would be a pathological feature in fatal asthma. We have quantified the expression of the pan-neuronal marker PGP9.5 and the neuronal sensory-derived neuropeptide calcitonin gene-related peptide (CGRP) in the large airways of 12 individuals deceased due to an asthma attack and compared to 10 control lung samples. The proximity between nerve bundles to eosinophils, mast cells and CADM1+ cells was also quantified. We have additionally developed a hPSC-derived sensory neuron/mast cell co-culture model, from where mast cells were purified and differences in gene expression profile assessed. Fatal asthma patients presented a higher PGP9.5 and CGRP positive area in the airways, indicating sensory neuroplasticity. Eosinophils, mast cells and CADM1+ cells were observed in close contact or touching the airway nerve bundles, and this was found to be statistically higher in fatal asthma samples. Invitro co-culture model showed that human mast cells adhere to sensory neurons and develop a distinct gene expression profile characterized by upregulated expression of genes related to heterophilic adhesion, activation and differentiation markers, such as CADM4, PTGS2, C-KIT, GATA2, HDC, CPA3, ATXN1 and VCAM1. Our results support a significant role for neuroplasticity and neuroimmune interactions in fatal asthma, that could be implicated in the severity of the fatal attack. Accordingly, the presence of physical neuron and mast cell interaction leads to differential gene expression profile in the later cell type.

Synthesis and Docking Studies of Novel Spiro[5,8-methanoquinazoline-2,3'-indoline]-2',4-dione Derivatives.

In this study, a set of spiro[5,8-methanoquinazoline-2,3'-indoline]-2',4-dione derivatives 3a-p were synthesized starting from unsubstituted and N-methyl-substituted diendo- and diexo-2-aminonorbornene carboxamides, as well as various substituted isatins. The typical method involves a condensation reaction of alicyclic aminocarboxamide and isatin in the presence of a catalyst, using a solvent and an acceptable temperature. We developed a cost-effective and ecologically benign high-speed ball milling (HSBM), microwave irradiation (MW), and continuous flow (CF) technique to synthesize spiroquinazolinone molecule 3a. The structures of the synthesized compounds 3a-p were determined using 1D and 2D NMR spectroscopies. Furthermore, docking studies and absorption, distribution, metabolism, and toxicity (ADMET) predictions were used in this work. In agreement with the corresponding features found in the case of both the SARS-CoV-2 main protease (RCSB Protein Data Bank: 6LU7) and human mast cell tryptase (RCSB Protein Data Bank: 2ZA5) based on the estimated total energy and binding affinity, H bonds, and hydrophobicity in silico, compound 3d among our 3a-g, 3i-k, and 3m derivatives was found to be our top-rated compound.

Molecular mechanism of IgE-mediated FcεRI activation.

Allergic diseases, affecting over a quarter of individuals in industrialized countries, have become significant public health concerns1,2. The high-affinity Fc receptor for IgE (FcεRI), mainly present on mast cells and basophils, plays a crucial role in allergic diseases3-5. Monomeric IgE binding to FcεRI regulates mast cell survival, differentiation, and maturation6-8. However, the underlying molecular mechanism remains unclear. Here we demonstrate that, prior to IgE binding, FcεRI mostly exists as a homo-dimer on human mast cell membrane. The structure of human FcεRI confirms the dimeric organization, with each promoter comprising one α subunit, one β subunit, and two γ subunits. The transmembrane helices of the α subunits form a layered arrangement with those of the γ and β subunits. The dimeric interface is mediated by a four-helix bundle of the α and γ subunits at the intracellular juxtamembrane region. Cholesterol-like molecules embedded within the transmembrane domain may stabilize the dimeric assembly. Upon IgE binding, the dimeric FcεRI dissociates into two protomers, each binding to an IgE molecule. Importantly, this process elicits transcriptional activation of Egr1/3 and Ccl2 in rat basophils, which can be attenuated by inhibiting the FcεRI dimer-to-monomer transition. Collectively, our study unveils the mechanism of antigen-independent, IgE-mediated FcεRI activation.

Acute and chronic impact of interleukin-33 stimulation on chemokines and growth factors in human cord blood-derived mast cells.

Mast cells (MCs) are multifaceted immune cells that are capable of recognizing and responding to various stimuli by releasing an array of cytokines. We aimed to use human cord blood-derived mast cells (hCBMCs) as a model to evaluate different conditions under which chemokines and growth factors are expressed and secreted as mediators upon stimulation with the alarmin interleukin-33 (IL-33). hCBMCs were stimulated with 10 ng/mL or 20 ng/mL of recombinant human IL-33 (rhIL-33) for 6 h (acute) or 24 h (chronic). The mRNA expression of chemokines and growth factors was analyzed using microarrays, and the mediators released in the supernatant were evaluated using a multiplex assay. The mRNA expression levels of C-C chemokine ligands (CCL) CCL1, CCL5, granulocyte macrophage colony-stimulating factor (GM-CSF), and macrophage inflammatory protein (MIP)-4/CCL18 were upregulated under all conditions. In contrast, C-X-C motif chemokine ligand (CXCL) CXCL8 and CCL24 levels increased only under acute (6 h) and prolonged (24 h) conditions, respectively. Moreover, high levels of CXCL8, MIP-1α, and MIP-1β were secreted during acute inflammation, whereas the release of GM-CSF and CXCL9 proteins increased under all four conditions. This study highlights the sentinel role of MCs in mounting a specific immune response against a pathogenic-like stimulus in a timely and dose-dependent manner and is relevant for improving inflammatory treatment options.

Pharmacological blockade of the mast cell MRGPRX2 receptor supports investigation of its relevance in skin disorders.

Because MRGPRX2 is now recognized as the mast cell receptor for basic secretagogues, there is currently a tremendous interest in whether MRGRPX2 could play an important role in various pruritic dermatoses such as chronic spontaneous urticaria. Therefore, we sought to identify new potent and selective antagonists to pharmacologically characterize the biological role of MRGPRX2. Various relevant in vitro, ex vivo, and in vivo model systems were used to investigate the role of MRGPRX2. This included the study of freshly isolated human skin mast cells and human basophils as well as an ex vivo human skin microdialysis preparation. The additivity of MRGPRX2 and FcεR1-mediated degranulation was also investigated. Human MRGPRX2 knock-in mice were generated to interrogate pharmacokinetic/pharmacodynamic relationships because both antagonists studied were shown to be human specific. Two novel and structurally distinct MRGPRX2 antagonists were identified with one, Compound B, being orally active and demonstrating high potency in blocking Substance P-mediated degranulation using freshly isolated human skin mast cells with half maximal inhibitory concentration (IC50) at 0.42 nM. Compound B also potently blocked Substance P-stimulated histamine release from resident mast cells in a human skin explant setup as well as blocking itch in an established behavioral scratching model using MRGPRX2 knock-in mice. Unlike human mast cells, Substance P failed to elicit a functional response in human basophils. These data fully support the investigation of MRGPRX2 receptor antagonists in mast cell-driven allergic skin disorders such as chronic spontaneous urticaria.

Regulation of BCR-dependent germinal center B-cell formation by HGAL and insight into its emerging myeloid ortholog, C1ORF150.

The specificity of cytokine and immunoreceptor signaling frequently depends upon receptor recruitment of select adaptor proteins and specifically engaged effectors. This review focuses on the orthologous adaptor proteins, HGAL and C1ORF150, and aims to provide insight into their respective modulation of lymphoid and myeloid cell signaling, formation, and function. HGAL acts predominantly within germinal center B cells as an important BCR signal transducer. Effects on BCR signalosome assembly involve HGAL's localization to the plasma membrane via its lipidation, initial interactions with SYK, the pY-phosphorylation of HGAL including its recruitment of GRB2, and HGAL engagement of PDZ-RhoGEF and RhoA signaling. At ligated BCRs, this includes HGAL(-GRB2) stimulation of SYK kinase, attenuation of calcium flux-dependent and NF-κB expression, promotion of cSMAC formation, and cytoskeletal remodeling associated with HGAL-attenuated cell migration. HGAL and partnered effectors also impact on DLBCL pathogenesis, and studies are summarized on HGAL's actions (using DLBCL and Burkitt lymphoma B cells) including cell migration effects, HGAL modulation of cytoskeletal components, and insightful HGAL transgenic mouse and xenograft models. For C1ORF150, its HGAL-homologous subdomains are considered, together with studies that demonstrate C1OR150's FcϵRI- and KIT-mediated expression and phosphorylation in primary human mast cells. Intriguingly, recent GWAS studies have identified a C1ORF150 in-frame splice variant that is strongly associated with urticaria. Candidate mechanisms via which the encoded "C1ORF150-Δexon2" isoform affects mast cell degranulation are considered, including FcϵR1 and/or KIT receptor connections, and candidate "myristoylation switch" mechanisms.

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.

IL-33-primed human mast cells drive IL-9 production by CD4+ effector T cells in an OX40L-dependent manner.

Interleukin-33 (IL-33) is an alarmin released by epithelial cells in response to tissue damage. It activates resident immune sentinel cells, which then produce signals commonly associated with type 2 immune responses, particularly affecting infiltrating antigen-specific T cells. Given that mast cells (MCs) are a primary target of IL-33 and can shape T helper (Th) cell responses, we investigated the effect of IL-33 priming on the ability of MCs to influence Th cell cytokine production. To examine the Th cell/MC interaction, we developed human primary MC/memory CD4+ T-cell coculture systems involving both cognate and non-cognate interactions. Our results demonstrated that IL-33-primed MCs, whether as bystander cells cocultured with activated effector T cells or functioning as antigen-presenting cells, promoted IL-9 and increased IL-13 production in Th cells via an OX40L-dependent mechanism. This indicates that MCs sense IL-33-associated danger, prompting them to direct Th cells to produce the key type 2 effector cytokines IL-9 and IL-13.

Intrinsic regulatory mechanisms protect human skin mast cells from excessive MRGPRX2 activation – paucity in LAD2 cells contributes to hyperresponsiveness of the mast cell line

Intrinsic regulatory mechanisms protect human skin mast cells from excessive MRGPRX2 activation – paucity in LAD2 cells contributes to hyperresponsiveness of the mast cell line

Co-cultivation of mastocytes and cumulus cells in polycystic ovary syndrome

The purpose of the study was to study the cytokine-producing function of cumulus cells of the ovaries in PCOS during co-cultivation of cumulus cells with mast cells to identify their mutual influence in the immunopathogenesis of PCOS. The study was approved by the Interdisciplinary Ethics Committee of the FSBEI of HE of the Ministry of Health of the Russian Federation. A permanent human mast cell line HMC-1 (Human mast cell, ATCC, USA) and a primary culture of cumulus cells were used. The condition of cumulus cells and mastocytes was determined using fluorescent dyes followed by flow cytometry before co-cultivation and after 7 days co-cultivation. The levels of IL-6, IL-10, and IFNã were studied on days 1, 3, and 7 of the experiment. In monoculture and during co-culture of cells, the synthesis of cytokines IL-6, IL-10, and IFNã continues, but to varying degrees of severity. In the permanent mast cell line, an increase in IL-6, IL-10, and IFNã is observed on the 1st, 3rd, and 7th days of cultivation. On the first day, cytokine levels of donor cumulus cells and mastocytes did not differ significantly (p 0.05). In the culture of donor cumulus cells, the synthesis of IL-6, IL-10, and IFNã progressively increases by the 7th day of the experiment (p 0.05). On the first day of the experiment, the balance of Th1/Th2 cytokines in PCOS was twice as high as in healthy women. The ratio increased, and on the 7th day reached 3.83 times higher than the ratio of Th1/Th2 cytokines in the control group. Hyperproduction of IFNã by mastocytes was most significant when they were co-cultured with cumulus cells, in monoculture mast cells synthesized excessively cytokine twice from the initial values of IFNã, and the monoculture cumulus cells in PCOS it practically did not contain. The studied cytokines are regulators of the function of ovarian cumulus cells and factors that increase the competence of the oocyte, indicating the need for their correction, which will allow a real influence on the links of pathogenesis in PCOS in the future.later on.

Rocuronium-specific antibodies drive perioperative anaphylaxis but can also function as reversal agents in preclinical models.

Neuromuscular blocking agents (NMBAs) relax skeletal muscles to facilitate surgeries and ease intubation but can lead to adverse reactions, including complications because of postoperative residual neuromuscular blockade (rNMB) and, in rare cases, anaphylaxis. Both adverse reactions vary between types of NMBAs, with rocuronium, a widely used nondepolarizing NMBA, inducing one of the longest rNMB durations and highest anaphylaxis incidences. rNMB induced by rocuronium can be reversed by the synthetic γ-cyclodextrin sugammadex. However, in rare cases, sugammadex can provoke anaphylaxis. Thus, additional therapeutic options are needed. Rocuronium-induced anaphylaxis is proposed to rely on preexisting rocuronium-binding antibodies. To understand the pathogenesis of rocuronium-induced anaphylaxis and to identify potential therapeutics, we investigated the memory B cell antibody repertoire of patients with suspected hypersensitivity to rocuronium. We identified polyclonal antibody repertoires with a high diversity among V(D)J genes without evidence of clonal groups. When recombinantly expressed, these antibodies demonstrated specificity and low affinity for rocuronium without cross-reactivity for other NMBAs. Moreover, when these antibodies were expressed as human immunoglobulin E (IgE), they triggered human mast cell activation and passive systemic anaphylaxis in transgenic mice, although their affinities were insufficient to serve as reversal agents. Rocuronium-specific, high-affinity antibodies were thus isolated from rocuronium-immunized mice. The highest-affinity antibody was able to reverse rocuronium-induced neuromuscular blockade in nonhuman primates with kinetics comparable to that of sugammadex. Together, these data support the hypothesis that antibodies cause anaphylactic reactions to rocuronium and pave the way for improved diagnostics and neuromuscular blockade reversal agents.

Amphotericin B for injection triggers degranulation of human LAD2 mast cells by MRGPRX2 and pseudo-allergic reactions in mice via MRGPRB2 activation.

Amphotericin B, a polyene macrolide antifungal agent, still plays an important role in the management of serious systemic fungal infections. Amphotericin B deoxycholate (AmBd) has been used to treat invasive fungal infections for over 60years and remains the primary clinical formulation currently available. Anaphylactoid reactions triggered by AmBd in the clinic have been documented. However, the molecular and cellular events contributing to these reactions have not been clearly elucidated to date. This study demonstrates that the human Mas-related G protein-coupled receptor X2 (MRGPRX2) is the receptor that mediates these anaphylactoid responses. Molecular docking and cellular thermal shift assay (CETSA) indicate that AmBd exhibits potential affinity with MRGPRX2. In vitro, exposure to AmBd results in significant release of LAD2 mast cell granules and induces intracellular Ca2+ mobilization as well as activation of PLC-γ/IP3R and PI3K/AKT signaling pathways. However, these phenomena are reduced in MRGPRX2-knockdown LAD2 cells. In vivo, AmBd triggers paw swelling and a rapid drop in core body temperature in wild-type (WT) mice. However, these reactions are almost absent in MRGPRB2 (the mouse homolog of MRGPRX2) knockout mice (MRGPRB2MUT, MUT). The above results suggest that AmBd activates PLC-γ/IP3R and PI3K/AKT signaling via MRGPRX2 (in human LAD2 mast cells) or MRGPRB2 (in mice), leading to the release of mast cell granules and subsequent triggering of pseudo-allergic reactions. Taken together, this study clarifies the role of MRGPRX2 in triggering pseudo-allergic reactions to AmBd and suggests that MRGPRX2 could be a potential therapeutic target for controlling these reactions.

Nutraceutical formulation based on a synergic combination of melatonin and palmitoylethanolamide for the management of allergic events.

The management of allergic events is a growing global health issue, especially in industrialized countries. This disease is an immune-mediated process, regulated by the interaction of IgE with an allergen, resulting in mast cell activation, which concerns the release of several immune-inflammatory modulators, i.e., histamine, β-hexosaminidase, COX-2, IL-6, and TNF-α, responsible for the main allergic-reaction associated symptoms. The aim of the present study was the efficacy evaluation of an alternative remedy, an innovative nutraceutical formulation (NF) based on the synergic combination of melatonin (MEL) and palmitoylethanolamide (PEA) for the prevention and treatment of immune disease. At first, the intestinal bioaccessibility of PEA and MEL in NF was assessed at 1.6 and 36%, respectively. Then the MEL and PEA ability to modulate the release of immune-inflammatory modulators in the human mast cell line (HMC-1.2) at their bioaccessible concentration was investigated. Our results underline that NF treatment was able to reduce COX-2 mRNA transcription levels (-30% vs. STIM, p < 0.0001) in stimulated HMC-1.2 and to contract COX-2 enzymatic activity directly (IC50: 152 μg/mL). Additionally, NF showed valuable ability in reducing histamine and β-hexosaminidase release in stimulated HMC-1.2, as well as in decreasing TNF-α and IL-6 mRNA transcription levels and protein production.

Mast cell-derived BH4 and serotonin are critical mediators of postoperative pain.

Postoperative pain affects most patients after major surgery and can transition to chronic pain. The considerable side effects and limited efficacy of current treatments underline the need for new therapeutic options. We observed increased amounts of the metabolites BH4 and serotonin after skin injury. Mast cells were primary postoperative sources of Gch1, the rate-limiting enzyme in BH4 synthesis, itself an obligate cofactor in serotonin production by tryptophan hydroxylase (Tph1). Mice deficient in mast cells or in mast cell-specific Gch1 or Tph1 showed drastically decreased postoperative pain. We found that injury induced the nociceptive neuropeptide substance P, mast cell degranulation, and granule nerve colocalization. Substance P triggered serotonin release in mouse and human mast cells, and substance P receptor blockade substantially ameliorated pain hypersensitivity. Our findings highlight the importance of mast cells at the neuroimmune interface and substance P-driven mast cell BH4 and serotonin production as a therapeutic target for postoperative pain treatment.

Anti-Allergic and Anti-Inflammatory Signaling Mechanisms of Natural Compounds/Extracts in In Vitro System of RBL-2H3 Cell: A Systematic Review.

Various extracts are tested for anti-allergic or anti-inflammatory properties on in vitro models. RBL-2H3 cells are widely used in allergic or immunological studies. FCεRI and its downstream signaling cascades, such as MAPK, NF-κB, and JAK/STAT signaling pathways, are important allergic or inflammatory signaling mechanisms in mast and basophil cells. This systematic review aims to study common signaling pathways of the anti-allergic or anti-inflammatory compounds on RBL-2H3 cells. We selected the relevant research articles published after 2015 from the PubMed, Scopus, Science Direct and Web of Science databases. The risk of bias of the studies was assessed based on the modified CONSORT checklist for in vitro studies. The cell lines, treatments, assay, primary findings, and signaling pathways on RBL-2H3 cells were extracted to synthesize the results. Thirty-eight articles were included, and FCεRI and its downstream pathways, such as Lyn, Sky, PLCγ, and MAPK, were commonly studied. Moreover, the JAK/STAT pathway was a potential signaling mechanism in RBL-2H3 cells. However, the findings based on RBL-2H3 cells needed to be tested along with human mast cells to confirm its relevance to human health. In conclusion, a single plant extract may act as an anti-inflammatory reagent in RBL-2H3 cells via multiple signaling pathways besides the MAPK signaling pathway.

Acute and prolonged effects of interleukin-33 on cytokines in human cord blood-derived mast cells

Mast cells are multifaceted cells localized in tissues and possess various surface receptors that allow them to respond to inner and external threat signals. Interleukin-33 (IL-33) is a cytokine released by structural cells in response to parasitic infections, mechanical damage, and cell death. IL-33 can activate mast cells, causing them to release an array of mediators. This study aimed to identify the different cytokines released by human cord blood-derived mast cells (hCBMCs) in response to acute and prolonged stimulation with IL-33. For this purpose, a hCBMC model was established and stimulated with 10 ng and 20 ng of recombinant human IL-33 (rhIL-33) for 6 h and 24 h. Total RNA was hybridized using a high-density oligonucleotide microarray. A multiplex assay was performed to assess the released cytokines. Acute exposure to rhIL-33 increased the expression of IL-1α, IL-1β, IL-6, and IL-13, whereas prolonged exposure increased the expression of IL-5 and IL-10, and cytokines were detected in the culture supernatant. WebGestalt analysis revealed that rhIL-33 induces pathways and biological processes related to the immune system and the acute inflammatory response. This study demonstrates that rhIL-33 can activate hCBMCs to release pro- and anti-inflammatory cytokines, eliciting distinct acute and prolonged responses unique to hCBMCs.

The JAK1/JAK2 inhibitor ruxolitinib inhibits mediator release from human basophils and mast cells.

The Janus kinase (JAK) family includes four cytoplasmic tyrosine kinases (JAK1, JAK2, JAK3, and TYK2) constitutively bound to several cytokine receptors. JAKs phosphorylate downstream signal transducers and activators of transcription (STAT). JAK-STAT5 pathways play a critical role in basophil and mast cell activation. Previous studies have demonstrated that inhibitors of JAK-STAT pathway blocked the activation of mast cells and basophils. In this study, we investigated the in vitro effects of ruxolitinib, a JAK1/2 inhibitor, on IgE- and IL-3-mediated release of mediators from human basophils, as well as substance P-induced mediator release from skin mast cells (HSMCs). Ruxolitinib concentration-dependently inhibited IgE-mediated release of preformed (histamine) and de novo synthesized mediators (leukotriene C4) from human basophils. Ruxolitinib also inhibited anti-IgE- and IL-3-mediated cytokine (IL-4 and IL-13) release from basophils, as well as the secretion of preformed mediators (histamine, tryptase, and chymase) from substance P-activated HSMCs. These results indicate that ruxolitinib, inhibiting the release of several mediators from human basophils and mast cells, is a potential candidate for the treatment of inflammatory disorders.

On probiotic integration in the management of inflammation and the maintenance of the intestinal epithelial barrier’s integrity

Inflammatory bowel disease epidemiology has grown dramatically in recent years, particularly in developed and developing Western countries. Many factors, including stress, diet, and medications, cause and exacerbate inflammatory conditions. Inflammation is closely related to the concept of intestinal barrier integrity. When integrity is compromised, toxins and pathogens can enter the bloodstream. In recent years, there has been a growing interest in using probiotic bacteria to prevent or treat a variety of pathologies, including inflammatory bowel disease. Some studies have looked at the effectiveness of multi-strain probiotic supplements in preventing intestinal barrier dysfunction in in vitro models of lipopolysaccharide-induced inflammation. To mimic the intestinal barrier, human colon adenocarcinoma cell lines were established in Transwell co-culture models. The epithelium permeability was assessed by measuring the transepithelial electrical resistance. The expression of individual proteins involved in barrier function was assessed. The immunomodulatory effects of probiotic formulations were studied in both human macrophage cell lines and ex vivo human peripheral blood mononuclear cell-derived macrophages. The intestinal epithelial layer was also interfaced with a human mast cell line. Selected probiotics have demonstrated high potential for use in maintaining intestinal barrier integrity and possessing anti-inflammatory properties.