Search Results (298)

The IRE1α-XBP1 axis is the most conserved of the three major unfolded protein response (UPR) branches triggered by the endoplasmic reticulum (ER) stress. Although the transcription factor XBP1 is involved in the development and function of several hematopoietic lineages, its role in the activation of mast cells (MCs), which are critical in allergic responses, remains largely unknown. We identified salicylaldehyde, which suppresses IRE1α nuclease activity that is essential for XBP1 production, as an inhibitor of MC activation in our previous screening; therefore, we herein investigated the effects of additional IRE1α inhibitors, 3-methyl-6-bromo-salichylaldehyde (MBSA) and KIRA6, targeting the nuclease domain and kinase domain, respectively, on MC activation. MBSA and KIRA6 suppressed IgE-dependent degranulation of bone marrow-derived MCs (BMMCs) but did not inhibit Ca²⁺ ionophore- or compound48/80-induced degranulation. Treatments with inhibitors of two other branches of UPR, the PERK and ATF6 pathways, did not affect the IgE-induced activation of BMMCs. The intraperitoneal administration of MBSA or KIRA6 significantly suppressed IgE-induced passive anaphylaxis in mice. Furthermore, to examine the effects of XBP1, siRNA-mediated knockdown was performed. The results obtained confirmed that Xbp1 siRNA introduction reduced the IgE-dependent degranulation of BMMCs in parallel with the knockdown level of Xbp1 mRNA. Therefore, the IRE1α-XBP1 axis plays a significant role in IgE-dependent and MC-mediated allergic responses and is considered to be a therapeutic target of allergic diseases. Full article

Jacareubin (2), nujiangexanthone A, and α-mangostin display the highest anti-allergic effects among the active xantones through still not well-known mechanisms. This study investigates the SAR of jacareubin, its precursor xanthone V (1) and their peracetylated (1a and 2a), permethylated (1b and 2b) derivatives and their anti-allergic and anti-inflammatory effects. To characterize the inhibitory effect of jacareubin, 2a and 2b on the anaphylactic reaction, we first utilized in vitro models of bone marrow derived mast cells (BMMCs), determining their capacity of inhibiting the IgE/Antigen-induced degranulation, myeloperoxidase (MPO), and xanthine oxidase (XO) activation. Also, we utilized in vivo models of passive cutaneous anaphylaxis (PCA) and TPA-induced ear edema. In vitro tests showed that the compound 2b was more effective than jacareubin in the inhibition of BMMCs degranulation. Besides, in vivo models of PCA revealed that the fourth cyclized ring of jacareubin is the critical structural element for anti-allergic efficacy, as compound 1 was less effective. Additionally, hydroxyl groups were found to be essential for inhibiting MPO. Jacareubin was the only tested xanthone that directly inhibited XO, a result supported by molecular docking. Overall, jacareubin represents a promising multi-target scaffold that could be used for developing new treatments for inflammatory and allergic diseases. Full article

Background/Objectives: Cardiovascular disease (CVD), particularly coronary artery disease (CAD), is increasingly linked to microvascular inflammation driven by interactions between immune, vascular, and neuroendocrine systems. Mast cells (MCs), strategically positioned near blood vessels, play pivotal roles in this process through the release of inflammatory and vasoactive mediators, contributing to increased vascular permeability, endothelial dysfunction, and tissue inflammation in conditions including ischemia–reperfusion (I/R) and CVD. This comprehensive review examines the cellular and molecular mechanisms underlying MC-mediated microvascular inflammation, with emphasis on neuroimmune regulation through the heart–brain axis, and evaluates the therapeutic potential of flavonoids. Methods: A review of in vitro, animal, and clinical studies was conducted to assess MC-mediated cardiovascular pathology and the pharmacological effects of natural flavonoids on MC activation and microvascular inflammation. Results: Psychological and physical stress activates hypothalamic corticotropin-releasing hormone (CRH) signaling, directly triggering coronary MC degranulation via CRHR-1 and CRHR-2 receptors, while co-released neuropeptides, including neurotensin and urocortin, amplify this neuroimmune cascade. Traumatic brain injury, autonomic dysregulation, and atrial fibrillation further perpetuate this bidirectional heart–brain axis, linking neurological stress to microvascular injury and adverse cardiac remodeling. An autocrine–paracrine CRH amplification loop sustains chronic coronary microvascular inflammation, contributing to heart failure with preserved ejection fraction (HFpEF) and MC activation disease (MCAD)-related cardiovascular manifestations. Natural flavonoids were found to inhibit MC activation, suppress inflammatory mediator synthesis, and protect microvascular integrity through multiple molecular targets, including calcium signaling, transcription factors, oxidative stress pathways, and CRHR-1-mediated neuroimmune signaling. Conclusions: While challenges remain regarding bioavailability and standardization, multi-compound formulations targeting multiple risk factors hold promise for preventing CVD progression. Future research directions for advancing these natural compounds toward clinical implementation are identified. Full article

This study concurrently addressed the separation method for carbon dots derived from Glycyrrhizae Radix et Rhizoma Praeparata cum Melle (GRRPM) and the in vitro evaluation of their anti-allergic biological activity. Glycyrrhizae Radix et Rhizoma Praeparata cum Melle Carbon Dots (GRRPM-CDs) were prepared via decoction followed by dialysis, and their properties were characterized using High-Performance Liquid Chromatography (HPLC) and nanomaterial techniques. Anti-allergic activity was evaluated using a C48/80-induced RBL-2H3 mast cell degranulation model. Safety and efficacy were assessed using the CCK-8 assay, direct intervention, and drug-containing serum methods. The release of β-hexosaminidase (β-hex), histamine (HIS), interleukin-4 (IL-4), and tumor necrosis factor-α (TNF-α) was measured by ELISA, and key proteins in the MAPK signaling pathway were analyzed by Western blot. GRRPM-CDs inhibited mast cell degranulation and the release of allergic and inflammatory mediators in a dose-dependent manner. They also significantly downregulated the phosphorylation levels of the JNK, ERK, and p38 proteins in the MAPK signaling pathway. GRRPM-CDs exhibit significant anti-allergic activity, likely via suppression of the MAPK pathway. These findings provide new insights into the bioactive components of processed Glycyrrhiza and suggest potential avenues for developing novel therapies for allergic diseases. Full article

NLRP1 is an inflammasome sensor protein expressed in barrier tissues of humans. Its activation in response to microbes or cellular stress triggers a cascade of molecular events, leading up to IL1β-driven inflammation and pyroptosis. Rare germline mutations of NLRP1 cause its persistent activation, resulting in autoinflammatory syndromes. Multiple self-healing palmoplantar carcinoma (MSPC) is one such syndrome, characterized by the appearance of recurrent keratoacanthomas (KAs) on the palms and soles. Here, we aimed to compare the subcellular localization of mutant NLRP1 in lesions from an MSPC patient to wild-type NLRP1 in non-MSPC-KAs and in skin from healthy donors. Using mass spectrometry, immunohistochemistry and immunoelectron tomography, we found that NLRP1 localized to mast cell granules in all MSPC lesions but also in healthy skin, a novel finding which implicates these cells in NLRP1-associated responses in human skin. Moreover, we found that mast cells expressing the A66V pathogenic variant of NLRP1 overpopulated MSPC-KAs, infiltrated the epidermis and degranulated, a behavior not seen in other lesions from this study. The released granules had the highest NLRP1 protein content and also contained NLRP3 and IL1β, suggesting the coexistence of inflammasome pathways within mast cells. Taken together, our findings propose cutaneous mast cells as a previously unrecognized NLRP1 reservoir in health and disease. Full article

Background: Atopic dermatitis (AD) is a chronic inflammatory skin disease linked to epidermal barrier dysfunction, Th2-skewed immune polarization, and disrupted gut microbiota homeostasis. While probiotic interventions show promise in managing AD, the mechanisms governing strain-specific efficacy—particularly systemic modulation via the “gut–skin axis”—remaining to be fully elucidated. Methods: This study systematically compared the oral therapeutic effects of three Lacticaseibacillus rhamnosus strains (MG-A047, MG-A054, and LGG) in a 2,4-dinitrochlorobenzene (DNCB)-induced AD mouse model. Results: By integrating behavioral, histopathological, and serological assessments with 16S rRNA-based gut microbiota profiling and in vitro functional assays, this study offers a multidimensional evaluation of the strain-specific advantages and potential therapeutic mechanisms of three L. rhamnosus strains. The results demonstrate that MG-A054 most effectively alleviated cutaneous inflammation and pruritus, significantly reduced serum IgE and IL-4 levels, and attenuated epidermal hyperplasia and inflammatory cell infiltration (including mast cells and eosinophils). Mechanistically, this strain may directly inhibit hyaluronidase activity and mast cell degranulation, and specifically remodel the gut microbiota structure, thereby promoting a shift toward a healthier functional profile. Conclusions: These findings suggest that the superior efficacy of MG-A054 may be achieved through coordinated modulation of the gut–skin axis and related pathways. This study offers new mechanistic clues for understanding the strain-specific actions of probiotics and lays a preclinical foundation for the further development of MG-A054 as a potential targeted microecological therapy for AD. Full article

Mast cells can release different kinds of molecules as a response to different stimuli, particularly proinflammatory mediators that contribute to neuroinflammation. The enrichment of mast cells in specific areas of the nervous system and gastrointestinal tract, together with their degranulation, histamine and neuropeptide secretion, such as substance P, and mast cell–microglia interactions, may promote neuroinflammatory signaling in neurological and psychiatric disorders during childhood and adolescence. The aim of this review is to explore the mast cell-related molecular aspects of the main neuropsychiatric disorders of the developmental period, such as ADHD, autism spectrum disorder, and epilepsy, as well as anxiety and depression. The translational analysis of molecular pathways and the relationships involved may contribute to the development of innovative and targeted therapeutic approaches. Full article

Transient receptor potential vanilloid 4 (TRPV4) is a polymodal cation channel that is widely expressed in sensory neurons, immune cells, and structural tissues, where it integrates mechanical, osmotic, and chemical stimuli to regulate both physiological responses and disease-associated signaling. Mast cells (MCs), key immune effector cells capable of rapid mediator release through degranulation, also express TRPV4. Increasing evidence supports TRPV4-MC signaling as an important neuroimmune interface, linking mechanical and inflammatory stimuli to tissue hypersensitivity and pain. In this review, we synthesize current evidence supporting a role for TRPV4 in MC-associated neuroimmune signaling across multiple disease contexts while distinguishing settings in which TRPV4 directly regulates MC activation from those in which MC responses arise through multicellular tissue interactions. Direct TRPV4-dependent MC activation has been described in conditions such as LL-37–driven rosacea and mechanically induced inflammation, whereas in disorders including asthma, visceral hypersensitivity, bladder pain syndromes, and osteoarthritis, TRPV4 activity in epithelial, neuronal, or stromal compartments more often influences MC function indirectly through ATP–purinergic signaling, cytokine release, and neuropeptide-mediated crosstalk. Across systems, TRPV4 emerges not as a single pathogenic switch but as part of a context-dependent signaling network whose functional consequences depend on cell type, tissue microenvironment, and disease stage. Altogether, these findings identify TRPV4 as a therapeutically actionable node within neuroimmune signaling pathways and support the development of tissue-specific and combination strategies targeting both TRPV4 activity and MC-mediated signaling in chronic inflammatory and pain disorders. Full article

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by epidermal barrier dysfunction and dysregulated immune responses, particularly an imbalance between T helper type 1 (Th1) and type 2 (Th2) cytokines. Natural products with immunomodulatory activity have attracted increasing attention as potential strategies for regulating allergic inflammation. In this study, we investigated the immunomodulatory effects of bioprocessed black rice bran (BRB-F) and bioprocessed balloon flower root (BFR-F). In vitro assays using human B cells, mast cells, and keratinocytes were conducted to evaluate IgE production, mast cell degranulation, and epithelial inflammatory mediator release. The efficacy of the BRB-F:BFR-F mixture was further evaluated in BALB/c mice with 2,4-dinitrochlorobenzene (DNCB)/Dermatophagoides farinae extract (DFE)-induced AD-like dermatitis. BRB-F and BFR-F suppressed IgE production, attenuated mast cell degranulation and thymic stromal lymphopoietin (TSLP) release, and reduced keratinocyte-derived inflammatory mediators (thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC), and IL-6). In mice, dietary supplementation with the BRB-F:BFR-F mixture (10–80 mg/kg/day) dose-dependently improved clinical skin lesions and histopathological changes, with serum IgE reduced by up to 87.1% at the highest dose. The treatment significantly suppressed Th2 cytokine mRNA expression in ear tissue (IL-4, IL-5, and IL-13) by 37.2%, 32.7%, and 34.0%, respectively, compared with the positive control. In contrast, splenic Th1 cytokine mRNA expression (IL-2, IL-12, and IFN-γ) was partially restored by 37.1%, 22.5%, and 18.7%, respectively. These findings indicate that BRB-F and BFR-F modulate multiple immune pathways and help restore Th1/Th2 immune balance, suggesting their potential as functional materials for regulating immune dysregulation associated with AD. Full article

Type 2 diabetes (T2D) features insulin resistance that promotes cerebrovascular injury, yet the immune signals linking metabolic stress to vascular dysfunction remain unclear. We tested the hypothesis that insulin resistance and soluble vascular cell adhesion molecule-1 (sVCAM1) act through complementary pathways in mast cells (MCs) to raise circulating histamine levels and impair cerebral vascular function. In a high-fat diet (HFD) plus low-dose streptozotocin (STZ) model, plasma histamine rose sharply after the onset of insulin resistance and remained elevated. Plasma sVCAM1 levels also increased after insulin resistance. In vitro, recombinant sVCAM1 upregulated histidine decarboxylase (HDC) in native MCs in a dose-dependent manner, indicating a shift toward histamine synthesis, but did not enhance degranulation. In contrast, pharmacological inhibition of Akt with MK2206 activated Glycogen Synthase Kinase 3 beta (GSK3β) and increased MC degranulation without affecting HDC expression. Diabetic endothelial cell monolayers exhibited a ~twofold reduction in transendothelial electrical resistance consistent with impaired blood–brain barrier (BBB) integrity. Diabetic cerebral arteries showed receptor remodeling that favored constriction with histamine H1 receptor (H1R) expression increasing in vascular smooth muscle, while endothelial H1R and histamine H2 receptor (H2R) decreased. Functionally, insulin treatment lowered HOMA2-IR in T2D mice but did not restore cerebral artery myogenic tone or improve stroke outcomes after distal middle cerebral artery occlusion (dMCAO). Neutralizing VCAM1 with a monoclonal antibody reduced circulating sVCAM1 and histamine levels, and, together with the GSK3β inhibitor Tideglusib, stabilized MCs, normalized cerebral artery tone, and reduced post-MCAO infarct size and edema. These findings identify two distinct yet complementary mast cell pathways in T2D, highlight an immune-vascular interface that drives cerebrovascular dysfunction, and propose sVCAM1 blockade plus GSK3β inhibition as rational strategies to protect cerebral vascular function in the diabetic brain. Full article

Helminths infect a quarter of the human population and are controlled in the frame of a canonical type-2 immune response. Interleukin-9 is a cytokine with pleiotropic functions during type-2 immunity that can be produced by many different cells. Accumulating evidence suggest that IL-9 is of particular relevance in controlling intestinal helminth infections. Using mice infected with the parasitic nematode Strongyloides ratti, we showed previously that ejection from the intestine depends on IL-9 and IL-9-mediated activation of mucosal mast cells. Here we use IL-9 reporter mice to identify the relevant cellular sources of IL-9 in vivo. We report that predominantly CD4⁺ T cells and group 2 innate lymphoid cells (ILC2s) produced IL-9 in S. ratti-infected or IL-33-treated mice. Interestingly, the IL-33-mediated induction of IL-9 and subsequent mast cell degranulation was modulated by concurrent S. ratti infection. While the IL-33-mediated expansion of IL-9-producing ILC2s was supressed by S. ratti infection, IL-9-producing CD4⁺ T cells were proportionally increased. Finally, we show that S. ratti-derived E/S products interfered with IL-9 production by BM-derived ILC2 in vitro. In conclusion, we have identified that ILC2 and CD4⁺ T cells produce IL-9 during S. ratti infection, and that ILC2 responses are suppressed by S. ratti products. Full article

Mast cells (MCs) are innate immune cells that are derived from CD34⁺ hematopoietic stem/progenitor cells (HSPCs) and mature in peripheral tissues such as skin and mucosa. Mature human MCs can be generated from peripheral blood, but this process requires substantial blood volumes as HSPC frequencies are typically very low. The aim of this study was to validate a new in-house-developed protocol for the generation of MCs from less than 20 mL of peripheral blood. To this end, we used a magnetic bead-based procedure to isolate ‘untouched’ HSPCs from 14 to 16 mL peripheral blood (PB). In total, 12 cultures were set up with blood from seven healthy donors, wherein HSPCs were first expanded for 4 weeks, followed by another 8 weeks of culture in MC maturation-inducing medium. Flowcytometric analysis, histochemical staining, and degranulation assays were used to assess their phenotypic and functional features. Our data show comparable expression of cytoplasmic granules and cell-surface expression of MRGPRX2, FcεR1α, and CD117 in 8/12 blood-derived MCs (PB-MCs) and buffy coat-derived HSPCs (BC-MCs). PB-MCs responded to classic stimulating agents like IgE/anti-IgE and C48/80. Hence, our novel MC generation protocol yields functionally competent MCs with no compromise in their maturation or activation potential despite 12 weeks of in vitro culture. Full article

Food allergies (FA) are a major public health concern in both children and adults. Immunoglobulin E (IgE)-mediated FA is characterized by allergic reactions driven by allergen-specific IgE and the subsequent degranulation of mast cells and basophils. Current FA management primarily involves avoidance of allergen-containing food, and more recently, therapies such as oral immunotherapy (OIT), sublingual immunotherapy (SLIT), and the anti-IgE biologic omalizumab. However, these interventions are not curative. The gut microbiome has been implicated in the development and regulation of oral tolerance to food antigens. This narrative review explores the role of probiotics, fecal microbiota transplantation (FMT), dietary interventions, and the interaction between the microbiome and OIT as potential strategies to manage established FA. We also explore barriers to their proliferation as part of regular clinical care. We conclude that future research should (1) address how the microbiome interacts with immunotherapies other than OIT, (2) explore the role of novel microbiome-based treatments like FMT as potential adjuvants to existing food allergy therapeutics, and (3) focus on developing standardized protocols and endpoints for microbiome-based therapeutics. Full article

Natural compounds have experienced increasing clinical application, but their association with rapid-onset anaphylactoid reactions (ARs) present a significant challenge to their safe use. These ARs, clinically resembling Type I hypersensitivity, are non-IgE-mediated and involve direct mast cell activation, primarily through the human Mas-related G protein-coupled receptor X2 (MRGPRX2). We computationally screened a natural compound library for MRGPRX2 activation. A human MRGPRX2-expressing cell model was established. Cell viability assays (0–80 μM) were performed to determine appropriate drug concentrations. Compared to the controls, Baohuoside I (10 μM), along with Kaempferol-3-O-rutinoside, Epigallocatechin gallate (EGCG), Isochlorogenic Acid B, Baicalin, Andrographolide, Isorhamnetin, and Dehydroandrographolide (all at 20 μM), significantly increased intracellular calcium flux (p < 0.05) and boosted tryptase and β-hexosaminidase secretion (ELISA) (p < 0.05) in mast cells. Furthermore, the degranulation induced by these compounds was inhibited by the MRGPRX2 inhibitor Z3578 at 20 μM. Neutral red staining was employed to observe cellular morphological changes. Specific compounds capable of mediating ARs through MRGPRX2 activation on mast cells were identified. This contributes to safer and more effective drug use by elucidating the potential triggers of ARs. Full article

Background: Vasicine (Vas) is a quinazoline alkaloid derived from Adhatoda vasica Nees, which has good anti-allergic asthma and anti-inflammatory effects. However, its specific functional mechanism on allergic asthma is unclear. This study aims to investigate the protective effect of Vas on allergic asthma and its underlying mechanisms. Methods: Initially, the therapeutic effects of Vas were assessed in ovalbumin-sensitized BALB/c mice using airway hyperresponsiveness (AHR), histopathological examinations, immunohistochemistry, and enzyme-linked immunosorbent assays (ELISA). Subsequently, a non-targeted metabolomic analysis was performed to examine the influence of Vas on lung metabolites, while molecular docking was utilized to clarify the mechanisms by which Vas intervenes in allergic asthma. Lastly, RBL-2H3 cells were employed in vitro to validate the metabolomic findings by measuring intracellular Ca²⁺ concentrations, in addition to conducting ELISA and Western blot analyses. Results: In vivo, Vas alleviates AHR in mice with allergic asthma, enhances histopathological conditions, and reduces inflammatory factors. Non-targeted metabolomics analyses indicate that the primary pathway implicated in its intervention in allergic asthma may be the FcεRI pathway. Furthermore, molecular docking techniques were utilized to evaluate the binding affinity between Vas and proteins associated with this pathway. In vitro, Vas effectively inhibits degranulation in RBL-2H3 cells and diminishes the release of inflammatory factors by modulating the FcεRI/Lyn + Syk/MAPK pathway. Conclusions: These findings indicate that Vas may effectively alleviate allergic asthma by reducing inflammatory responses, decreasing AHR, and improving histopathological features. Furthermore, Vas seems to inhibit mast cell degranulation and modulate the FcεRI/Lyn + Syk/MAPK pathway. Full article