Mast cell stabilisers

A Neuron-Mast Cell Axis Regulates Skin Microcirculation in Diabetes

Changes in microcirculation lead to the progression of organ pathology in diabetes. Although neuroimmune interactions contribute to a variety of conditions, it is still unclear whether abnormal neural activities affect microcirculation related to diabetes. Using laser speckle contrast imaging, we examined the skin of patients with type 2 diabetes and found that their microvascular perfusion was significantly compromised. This phenomenon was replicated in a high-fat diet-driven murine model of type 2 diabetes-like disease. In this setting, although both macrophages and mast cells were enriched in the skin, only mast cells and associated degranulation were critically required for the microvascular impairment. Sensory neurons exhibited enhanced TRPV1 activities, which triggered mast cells to degranulate and compromise skin microcirculation. Chemical and genetic ablation of TRPV1+ nociceptors robustly improved skin microcirculation status. Substance P (SP) is a neuropeptide and was elevated in the skin and sensory neurons in the context of type 2 diabetes. Exogenous administration of SP resulted in impaired skin microcirculation, whereas neuronal knockdown of SP dramatically prevented mast cell degranulation and consequently improved skin microcirculation. Overall, our findings indicate a neuron-mast cell axis underlying skin microcirculation disturbance in diabetes and shed light on neuroimmune therapeutics for diabetes-related complications.

ARTICLE HIGHLIGHTS

Mast cells and the gut-liver Axis: Implications for liver disease progression and therapy

The role of mast cells, traditionally recognized for their involvement in immediate hypersensitivity reactions, has garnered significant attention in liver diseases. Studies have indicated a notable increase in mast cell counts following hepatic injury, underscoring their potential contribution to liver disorder pathogenesis. Predominantly situated in connective tissue that envelops the hepatic veins, bile ducts, and arteries, mast cells are central to both initiating and perpetuating liver disorders. Additionally, they are crucial for maintaining gastrointestinal barrier function. The gut-liver axis emphasizes the complex, two-way communication between the gut microbiome and the liver. Past research has implicated gut microbiota and their metabolites in the progression of hepatic disorders. This review sheds light on how mast cells are activated in various liver conditions such as alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD), viral hepatitis, hepatic fibrogenesis, and hepatocellular carcinoma. It also briefly explores the connection between the gut microbiome and mast cell activation in these hepatic conditions.

Dehydroleucodine and xanthatin, two natural anti-inflammatory lactones, inhibit mast cell degranulation by affecting the actin cytoskeleton

Actin remodeling is a critical regulator of mast cell secretion. In previous work, we have shown that dehydroleucodine and xanthatin, two natural α,β-unsaturated lactones, exhibit anti-inflammatory and mast cell stabilizing properties. Based on this background, this study aimed to determine whether the mast cell stabilizing action of these lactones is associated with changes in the actin cytoskeleton. Rat peritoneal mast cells were preincubated in the presence of dehydroleucodine or xanthatin before incubation with compound 48/80. Comparative studies with sodium cromoglycate and latrunculin B were also made. After treatments, different assays were performed on mast cell samples: β-hexosaminidase release, cell viability studies, quantification of mast cells and their state of degranulation by light microscopy, transmission electron microscopy, and actin staining for microscopy observation. Results showed that dehydroleucodine and xanthatin inhibited mast cell degranulation, evidenced by the inhibition of β-hexosaminidase release and decreased degranulated mast cell percentage. At the same time, both lactones altered the F-actin cytoskeleton in mast cells resulting, similarly to Latrunculin B, in a higher concentration of nuclear F-actin when activated by compound 48/80. For the first time, this study describes the biological properties of dehydroleucodine and xanthatin concerning to the rearrangement of actin filaments during stimulated exocytosis in mast cells. These data have important implications for developing new anti-inflammatory and mast cell stabilizing drugs and for designing new small molecules that may interact with the actin cytoskeleton.

Combined effect of trifluoperazine and sodium cromoglycate on reducing acute edema and limiting lasting functional impairments after spinal cord injury in rats

Edema formation is one of the very first events to occur after spinal cord injury (SCI) leading to an increase of the intrathecal pressure and consequently to serious spinal tissue and functional impairments. Current edema treatments are still symptomatic and/or non-specific. Since edema formation mechanisms are mainly described as vasogenic and cytotoxic, it becomes crucial to understand the interplay between these two subtypes. Acting on key targets to inhibit edema formation may reduce secondary damage and related functional impairments. In this study, we characterize the edema kinetic after T9-10 spinal contusion. We use trifluoperazine (TFP) to block the expression and the functional subcellular localization of aquaporin-4 supposed to be implicated in the cytotoxic edema formation. We also use sodium cromoglycate (SCG) to deactivate mast cell degranulation known to be implicated in the vasogenic edema formation. Our results show a significant reduction of edema after TFP treatment and after TFP-SCG combined treatment compared to control. This reduction is correlated with limited onset of initial sensorimotor impairments particularly after combined treatment. Our results highlight the importance of potential synergetic targets in early edema therapy after SCI as part of tissue sparing strategies.

A one-pot and eco-friendly synthesis of novel β-substituted-α-halomethyl acrylates and the bioactivity of these compounds in an in vitro model of mast cell degranulation induced by pro-inflammatory stimuli

The goal of the present work was to develop novel β-substituted-α-halomethyl acrylates from a methodology in an aqueous phase and to evaluate their bioactivity as potential inhibitors of mast cell activation. Eleven β-substituted-α-halomethyl acrylates were synthesized through a modified Horner-Wadsworth-Emmons reaction. Compound 48/80 and the calcium ionophore A23187 stimulated the release of β-hexosaminidase from mast cells. The effect induced by compound 48/80 was inhibited by compound 5 (320 µM) and compound 9 (160 and 320 µM) without causing cytotoxic effects. The effect induced by A23187 was inhibited by compound 5 (40, 80, 160, and 320 µM) without affecting cell viability. The inhibitory effects exhibited by compounds 5 and 9 were more potent than those of the reference compound sodium cromoglycate at the same concentrations. The biochemical results were consistent with the morphological findings obtained by light and transmission electron microscopy. This study reports, for the first time, that the new synthetic compounds methyl (Z)- 2-bromo-3-(furan-3-yl)acrylate (compound 5) and methyl (E)- 2-bromo-3-(3-bromophenyl)acrylate (compound 9) strongly inhibit mast cell degranulation, without affecting cell viability. The implications of these results are relevant as a basis for developing new anti-inflammatory and mast cell stabilizing drugs.

Antiallergic Activity of 3-O-Dodecyl-l-ascorbic Acid

2-O-Alkyl-l-ascorbic acids and 3-O-alkyl-l-ascorbic acids were synthesized, and their degranulation inhibitory activities were evaluated. Among ascorbic acid derivatives with butyl, octyl, dodecyl, hexadecyl, and octadecyl groups introduced at the C-2 or C-3 positions, an AA derivative with a dodecyl group introduced at the C-3 position, 3-O-dodecyl-l-ascorbic acid (compound 8), showed the strongest inhibitory activity against antigen-stimulated degranulation. Compound 8 also inhibited calcium ionophore-stimulated degranulation. Compound 11, in which the hydroxyl group at the C-6 position of compound 8 was substituted with an amino group, and compound 12, in which the dodecyloxy group at the C-3 position of compound 8 was exchanged with a dodecylamino group, were synthesized, and these derivatives showed weaker inhibitory activity against antigen-stimulated degranulation than that of compound 8. In addition, orally administered compound 8 inhibited passive cutaneous anaphylaxis reactions in mice with a potency equal to that of oxatomide, an antiallergic agent. These results suggest that compound 8 may be a candidate for antiallergic treatment.

Anti-inflammatory effect of dictamnine on allergic rhinitis via suppression of the LYN kinase-mediated molecular signaling pathway during mast cell activation

Mast cells (MCs) are important therapeutic targets for allergic diseases. High-affinity immunoglobulin E (IgE) Fc receptors (FcεRI) trigger abnormal activation of MCs. Allergic rhinitis (AR) is an IgE-mediated antigen inhalation reaction that occurs in the nasal mucosa. MC aggravation and dysfunction were observed during the early stages of AR pathogenesis. Herb-derived dictamnine exhibits anti-inflammatory effects. Here, we investigated the pharmacological effects of herb-derived dictamnine on IgE-induced activation of MCs and an ovalbumin (OVA)-induced murine AR model. The results indicated that dictamnine attenuated OVA-induced local allergic reactions and reduced body temperature in OVA-challenged mice with active systemic anaphylaxis. Additionally, dictamnine decreased the frequency of nasal rubbing and sneezing in an OVA-induced murine AR model. Moreover, dictamnine inhibited FcεRI-activated MC activation in a dose-dependent manner without causing cytotoxicity, reduced the activation of the tyrosine kinase LYN in LAD2 cells, and downregulated the phosphorylation of PLCγ1, IP3R, PKC, Erk1/2, and Akt, which are downstream of LYN. In conclusion, dictamnine suppressed the OVA-stimulated murine model of AR and activated IgE-induced MCs via the LYN kinase-mediated molecular signaling pathway, suggesting that dictamnine may be a promising treatment for AR.

Coronary "Microvascular Dysfunction": Evolving Understanding of Pathophysiology, Clinical Implications, and Potential Therapeutics

Until recently, it has been generally held that stable angina pectoris (SAP) primarily reflects the presence of epicardial coronary artery stenoses due to atheromatous plaque(s), while acute myocardial infarction (AMI) results from thrombus formation on ruptured plaques. This concept is now challenged, especially by results of the ORBITA and ISCHEMIA trials, which showed that angioplasty/stenting does not substantially relieve SAP symptoms or prevent AMI or death in such patients. These disappointing outcomes serve to redirect attention towards anomalies of small coronary physiology. Recent studies suggest that coronary microvasculature is often both structurally and physiologically abnormal irrespective of the presence or absence of large coronary artery stenoses. Structural remodelling of the coronary microvasculature appears to be induced primarily by inflammation initiated by mast cell, platelet, and neutrophil activation, leading to erosion of the endothelial glycocalyx. This leads to the disruption of laminar flow and the facilitation of endothelial platelet interaction. Glycocalyx shedding has been implicated in the pathophysiology of coronary artery spasm, cardiovascular ageing, AMI, and viral vasculitis. Physiological dysfunction is closely linked to structural remodelling and occurs in most patients with myocardial ischemia, irrespective of the presence or absence of large-vessel stenoses. Dysfunction includes the impairment of platelet and vascular responsiveness to autocidal coronary vasodilators, such as nitric oxide, prostacyclin, and hydrogen sulphide, and predisposes both to coronary vasoconstriction and to a propensity for microthrombus formation. These findings emphasise the need for new directions in medical therapeutics for patients with SAP, as well as a wide range of other cardiovascular disorders.

Endocannabinoid modulation of allergic responses: Focus on the control of FcεRI-mediated mast cell activation

Allergic reactions are highly prevalent pathologies initiated by the production of IgE antibodies against harmless antigens (allergens) and the activation of the high-affinity IgE receptor (FcεRI) expressed in the surface of basophils and mast cells (MCs). Research on the mechanisms of negative control of those exacerbated inflammatory reactions has been intense in recent years. Endocannabinoids (eCBs) show important regulatory effects on MC-mediated immune responses, mainly inhibiting the production of pro-inflammatory mediators. However, the description of the molecular mechanisms involved in eCB control of MC activation is far from complete. In this review, we aim to summarize the available information regarding the role of eCBs in the modulation of FcεRI-dependent activation of that cell type, emphasizing the description of the eCB system and the existence of some of its elements in MCs. Unique characteristics of the eCB system and cannabinoid receptors (CBRs) localization and signaling in MCs are mentioned. The described and putative points of cross-talk between CBRs and FcεRI signaling cascades are also presented. Finally, we discuss some important considerations in the study of the effects of eCBs in MCs and the perspectives in the field.

Discovery of anti-allergic components in Guomingkang Formula using sensitive HEMT biochips coupled with in vitro and in vivo validation

BACKGROUND

Allergic rhinitis (AR) is a prevalent allergic disease, which seriously affects the sufferers' life quality and increases the socioeconomic burden. Guominkang (GMK), a well-known prescription for AR treatment, showed satisfactory effects; while its anti-allergic components remain to be disclosed. AlGaN/GaN HEMT biochip is more sensitive and cost-effective than other binding equipments, indicating its great potential for screening of active ingredients from herbal medicines.

METHODS

AR mouse models were first established to test the anti-allergic effect of GMK and discover the ingredients absorbed into blood by ultra-high performance liquid chromatography-mass spectra (UHPLC-MS). Then, novel Syk/Lyn/Fyn-functionalized high electron mobility transistor (HEMT) biochips with high sensitivity and specificity were constructed and applied to screen the active components. Finally, the results from HEMT biochips screening were validated via in silico (molecular docking and molecular dynamics simulation), in vitro (RBL-2H3 cells), and in vivo (PCA mice model) assays.

RESULTS

GMK showed a potent therapeutic effect on AR mice, and fifteen components were identified from the medicated plasma. Furthermore, hamaudol was firstly found to selectively inhibit the Syk and Lyn, and emodin was to selectively inhibit Lyn, which were further confirmed by isothermal titration calorimetry, molecular docking, and molecular dynamics simulation analyses. Suppression of the activation of FcεRI-MAPK signals might be the possible mechanism of the anti-allergic effect of hamaudol.

CONCLUSIONS

The targets of emodin and hamaudol were discovered by HEMT biochips for the first time. This study provided a novel and effective strategy to discover active components in a complex herbal formula by using AlGaN/GaN HEMT biochips.

Immunotherapy: A promising novel endometriosis therapy

Endometriosis is a common disease of the female reproductive system and has malignant features. Although endometriosis by itself is a benign disease, its erosive growth characteristics lead to severe pelvic pain and female infertility. Unfortunately, several aspects of the pathogenesis of endometriosis are still unclear. Furthermore, the clinical therapeutic methods are unsatisfactory. The recurrence rate of endometriosis is high. Accumulating evidence suggests that the onset and development of endometriosis are closely related to the abnormal function of the female autoimmune system, especially the function of some immune cells such as the aggregation of neutrophils, abnormal differentiation of macrophages, decreased cytotoxicity of NK cells, and abnormal function of T- and B-cell lines. Therefore, immunotherapy is probably a novel therapeutic strategy for endometriosis besides surgery and hormone therapy. However, information regarding the clinical application of immunotherapy in the treatment of endometriosis is very limited. This article aimed to review the effects of existing immunomodulators on the development of endometriosis, including immune cell regulators and immune factor regulators. These immunomodulators clinically or experimentally inhibit the pathogenesis and development of endometriosis lesions by acting on the immune cells, immune factors, or immune-related signaling pathways. Thus, immunotherapy is probably a novel and effective clinical treatment choice for endometriosis. Experimental studies of the detailed mechanism of immunotherapy and large-scale clinical studies about the effectiveness and safety of this promising therapeutic method are required in the future.

GPR30-mediated non-classic estrogen pathway in mast cells participates in endometriosis pain via the production of FGF2

Pain is one of the main clinical symptoms of endometriosis, but its underlying mechanism is still not clear. Recent studies have shown that the secretory mediators of mast cells activated by estrogen are involved in the pathogenesis of endometriosis-related pain, but how estrogen-induced mast cell mediators are involved in endometriosis-related pain remains unclear. Here, mast cells were found to be increased in the ovarian endometriotic lesions of patients. They were also closely located closely to the nerve fibers in the ovarian endometriotic lesions from of patients with pain symptoms. Moreover, fibroblast growth factor 2 (FGF2)-positive mast cells were upregulated in endometriotic lesions. The concentration of FGF2 in ascites and the protein level of fibroblast growth factor receptor 1 (FGFR1) were higher in patients with endometriosis than in those without endometriosis, and they were correlated with pain symptoms. In vitro, estrogen could promote the secretion of FGF2 through G-protein-coupled estrogen receptor 30 (GPR30) via the MEK/ERK pathway in rodent mast cells. Estrogen-stimulated mast cells enhanced the concentration of FGF2 in endometriotic lesions and aggravated endometriosis-related pain in vivo. Targeted inhibition of the FGF2 receptor significantly restrained the neurite outgrowth and calcium influx in dorsal root ganglion (DRG) cells. Administration of FGFR1 inhibitor remarkably elevated the mechanical pain threshold (MPT) and prolonged the heat source latency (HSL) in a rat model of endometriosis. These results suggested that the up-regulated production of FGF2 by mast cells through non-classic estrogen receptor GPR30 plays a vital role in the pathogenesis of endometriosis-related pain.

Progress in research of low-grade inflammation in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common intestinal disease with a prevalence of 10%-15%. However, its pathophysiology is still not completely clear, and it has long been considered as a functional disease. In recent years, it has been found that low-grade inflammation plays a pathogenic role in IBS. Studies have confirmed that there is persistent mucosal inflammation at the microscopic and molecular levels. This review discusses the evidence, role, and clinical relevance of mucosal inflammation in IBS. In addition to mucosal inflammation, neuroinflammation may lead to changes in neuroendocrine pathways and glucocorticoid receptor genes through the "gut-brain" axis, and thus cause IBS through proinflammatory phenotype and hypothalamic pituitary adrenal axis and 5-hydroxytryptamine dysfunction. The observation that IBS patients can benefit from anti-inflammatory therapy also confirms that IBS is associated with inflammation.

Tanshinone IIA alleviates ovalbumin-induced allergic rhinitis symptoms by inhibiting Th2 cytokine production and mast cell histamine release in mice

CONTEXT

Studies have shown that tanshinone IIA (TIIA) has an anti-inflammatory effect, but the effect on allergic rhinitis (AR) is unclear.

OBJECTIVE

In this study, we explore the effect of TIIA on AR.

MATERIALS AND METHODS

AR mice model was established by the intraperitoneal (ip) injection of 50 μg ovalbumin (OVA). AR mice in the dose tested groups were treated with TIIA (10 mg/kg/d, ip) or dexamethasone (Dex) (2.5 mg/kg/d, oral). The number of nasal rubbing in mice was counted. Inflammatory, goblet and mast cells in nasal mucosal tissue were detected. The contents of histamine, OVA-immunoglobulin E (IgE), OVA-immunoglobulin G1 (IgG1), tumour necrosis factor-α (TNF-α), interleukin-4 (IL-4), IL-5, interferon-γ (IFN-γ) and IL-12 in nasal lavage fluid (NALF) or serum were measured. Human mast cells (HMC-1) were treated with C48/80 to release histamine or TIIA for therapeutic effect, and the cell viability, histamine content and mast cell degranulation were examined.

RESULTS

OVA promoted the number of nasal rubbings in mice (78 times/10 min, p< 0.001), increased the inflammatory, goblet and mast cells in nasal mucosal tissue, and significantly (p< 0.001) elevated the levels of histamine (120 ng/mL), OVA-IgE (2 pg/mL), OVA-IgG1 (90 ng/mL), TNF-α (2.3 pg/mL), IL-4 (150 pg/mL) and IL-5 (65 pg/mL) in serum or NALF of OVA-induced AR mice. However, both TIIA and Dex inhibited the effect of OVA on AR mice. Besides, TIIA reversed the promotion of histamine release (30%) and mast cell degranulation induced by C48/80.

DISCUSSION AND CONCLUSIONS

TIIA alleviates OVA-induced AR symptoms in AR mice, and may be applied as a therapeutic drug for patients with Th2-, or mast cell-allergic disorders.

Chemical composition-based characterization of the anti-allergic effect of Guominkang Formula on IgE-mediated mast cells activation and passive cutaneous anaphylaxis

Guominkang (GMK), a Chinese medicine formula, has been used to treat allergic diseases in clinical settings for many years. To evaluate the antiallergic effect and molecular mechanism of action of GMK extract, RBL-2H3 cell models and passive cutaneous anaphylaxis (PCA) mouse models were established. High performance liquid chromatography (HPLC) and ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) analyses were performed to characterize the chemical composition of GMK. A total of 94 compounds were identified or tentatively identified from GMK. Three of them, emodin, ursolic acid, and hamaudol, were identified for the first time as potential active compounds in GMK, since they inhibited the degranulation of mast cells. The anti-allergic effect of hamaudol was the first to be discovered. GMK could markedly mitigate the shade of Evans Blue extravasation and ear incrassation in PCA mouse models. Additionally, GMK significantly inhibited the degranulation of mast cells, suppressed mast cell degranulation by reducing Ca²⁺ influx and the levels of TNF-α, IL-4, and histamine, and markedly inhibited the phosphorylation of Lyn, Syk, PLCγ1, IκBα, and NF-κB p65. Molecular docking results indicated that hamaudol and emodin had strong interaction with FcɛRI and NF-κB related proteins, while ursolic acid only interacted with NF-κB associated proteins. These results suggest GMK suppresses the activation of MCs both in vivo and in vitro. The underlying mechanism of its anti-allergic activity is associated with the inhibition of FcɛRI and NF-κB activation.

Comparison of Cromolyn Sodium, Montelukast, and Zafirlukast Prophylaxis for Capsular Contracture

BACKGROUND

Capsular contracture is the most common complication following breast augmentation. Recently, prophylaxis studies aiming to inhibit the release of profibrotic substances to prevent capsular contracture have gained in importance. This study investigated the effects of cromolyn sodium, montelukast, and zafirlukast on capsular contracture in a rat model.

METHODS

Thirty female Wistar albino rats were randomly divided into five groups: control, sham, cromolyn sodium, montelukast, and zafirlukast. Intraperitoneal injections were administered daily to the sham (1 ml per day), cromolyn sodium (10 mg/kg per day), montelukast (10 mg/kg per day), and zafirlukast (1.25 mg/kg per day) groups 1 month before surgery. Miniature breast implants were then placed on the backs of the rats in each group. Injections were continued for the next 3 months. The rats were subsequently killed, and the capsules were harvested and assessed histopathologically. The histopathologic outcomes were acute inflammation status, inflammation severity, synovial metaplasia, foreign body reaction, mast cell count, and capsular thickness.

RESULTS

The cromolyn sodium, montelukast, and zafirlukast groups had less acute inflammation and lower mean inflammation severity scores, foreign body reaction occurrence, mast cell counts, and capsular thickness than the control and sham groups ( p < 0.05). These parameters were better in the cromolyn sodium group than in the montelukast and zafirlukast groups ( p < 0.05).

CONCLUSIONS

Cromolyn sodium appears to inhibit capsular contracture more efficiently than montelukast and zafirlukast. This report may be a pioneer study for the prophylactic use of cromolyn sodium in capsular contracture.

CLINICAL RELEVANCE STATEMENT

The prophylactic administration of cromolyn sodium appears to reduce capsular contracture more efficiently than that of montelukast and zafirlukast. This report might constitute a pioneer study for the prophylactic use of cromolyn sodium in capsular contracture.

Nutritional activities of luteolin in obesity and associated metabolic diseases: an eye on adipose tissues

Obesity is characterized by excessive body fat accumulation and is a high-risk factor for metabolic comorbidities, including type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular disease. In lean individuals, adipose tissue (AT) is not only an important regulatory organ for energy storage and metabolism, but also an indispensable immune and endocrine organ. The sustained energy imbalance induces adipocyte hypotrophy and hyperplasia as well as AT remodeling, accompanied by chronic low-grade inflammation and adipocytes dysfunction in AT, ultimately leading to systemic insulin resistance and ectopic lipid deposition. Luteolin is a natural flavonoid widely distributed in fruits and vegetables and possesses multifold biological activities, such as antioxidant, anticancer, and anti-inflammatory activities. Diet supplementation of this flavonoid has been reported to inhibit AT lipogenesis and inflammation as well as the ectopic lipid deposition, increase AT thermogenesis and systemic energy expenditure, and finally improve obesity and associated metabolic diseases. The purpose of this review is to reveal the nutritional activities of luteolin in obesity and its complications with emphasis on its action on AT energy metabolism, immunoregulation, and endocrine intervention.

Review of potential medical treatments for middle ear cholesteatoma

Middle ear cholesteatoma (MEC), is a destructive, and locally invasive lesion in the middle ear driven by inflammation with an annual incidence of 10 per 100,000. Surgical extraction/excision remains the only treatment strategy available and recurrence is high (up to 40%), therefore developing the first pharmaceutical treatments for MEC is desperately required. This review was targeted at connecting the dysregulated inflammatory network of MEC to pathogenesis and identification of pharmaceutical targets. We summarized the numerous basic research endeavors undertaken over the last 30+ years to identify the key targets in the dysregulated inflammatory pathways and judged the level of evidence for a given target if it was generated by in vitro, in vivo or clinical experiments. MEC pathogenesis was found to be connected to cytokines characteristic for Th1, Th17 and M1 cells. In addition, we found that the inflammation created damage associated molecular patterns (DAMPs), which further promoted inflammation. Similar positive feedback loops have already been described for other Th1/Th17 driven inflammatory diseases (arthritis, Crohn’s disease or multiple sclerosis). A wide-ranging search for molecular targeted therapies (MTT) led to the discovery of over a hundred clinically approved drugs already applied in precision medicine. Based on exclusion criteria designed to enable fast translation as well as efficacy, we condensed the numerous MTTs down to 13 top drugs. The review should serve as groundwork for the primary goal, which is to provide potential pharmaceutical therapies to MEC patients for the first time in history.

Experimental Search for New Means of Pathogenetic Therapy COVID-19: Inhibitor of H2-Receptors Famotidine Increases the Effect of Oseltamivir on Survival and Immune Status of Mice Infected by A/PR/8/34 (H1N1)

The development of drugs for the therapy of COVID-19 is one of the main problems of modern physiology, biochemistry and pharmacology. Taking into account the available information on the participation of mast cells and the role of histamine in the pathogenesis of COVID-19, as well as information on the positive role of famotidine in the prevention and treatment of coronavirus infection, an experiment was carried out using famotidine in a mouse model. We used a type A/PR/8/34 (H1N1) virus adapted to mice. The antiviral drug oseltamivir (Tamiflu), which belongs to the group of neuraminidase inhibitors, was used as a reference drug. The use of famotidine in combination with oseltamivir can increase survival, improve the dynamics of animal weight, reduce the level of NKT cells and increase the level of naive T-helpers. Further studies of famotidine in vivo should be aimed at optimizing the regimen of drug use at a higher viral load, as well as with a longer use of famotidine.

Mast Cell–Tumor Interactions: Molecular Mechanisms of Recruitment, Intratumoral Communication and Potential Therapeutic Targets for Tumor Growth

Mast cells (MCs) are tissue-resident immune cells that are important players in diseases associated with chronic inflammation such as cancer. Since MCs can infiltrate solid tumors and promote or limit tumor growth, a possible polarization of MCs to pro-tumoral or anti-tumoral phenotypes has been proposed and remains as a challenging research field. Here, we review the recent evidence regarding the complex relationship between MCs and tumor cells. In particular, we consider: (1) the multifaceted role of MCs on tumor growth suggested by histological analysis of tumor biopsies and studies performed in MC-deficient animal models; (2) the signaling pathways triggered by tumor-derived chemotactic mediators and bioactive lipids that promote MC migration and modulate their function inside tumors; (3) the possible phenotypic changes on MCs triggered by prevalent conditions in the tumor microenvironment (TME) such as hypoxia; (4) the signaling pathways that specifically lead to the production of angiogenic factors, mainly VEGF; and (5) the possible role of MCs on tumor fibrosis and metastasis. Finally, we discuss the novel literature on the molecular mechanisms potentially related to phenotypic changes that MCs undergo into the TME and some therapeutic strategies targeting MC activation to limit tumor growth.

Traumatic Brain Injury: An Age-Dependent View of Post-Traumatic Neuroinflammation and Its Treatment

Traumatic brain injury (TBI) is a leading cause of death and disability all over the world. TBI leads to (1) an inflammatory response, (2) white matter injuries and (3) neurodegenerative pathologies in the long term. In humans, TBI occurs most often in children and adolescents or in the elderly, and it is well known that immune responses and the neuroregenerative capacities of the brain, among other factors, vary over a lifetime. Thus, age-at-injury can influence the consequences of TBI. Furthermore, age-at-injury also influences the pharmacological effects of drugs. However, the post-TBI inflammatory, neuronal and functional consequences have been mostly studied in experimental young adult animal models. The specificity and the mechanisms underlying the consequences of TBI and pharmacological responses are poorly understood in extreme ages. In this review, we detail the variations of these age-dependent inflammatory responses and consequences after TBI, from an experimental point of view. We investigate the evolution of microglial, astrocyte and other immune cells responses, and the consequences in terms of neuronal death and functional deficits in neonates, juvenile, adolescent and aged male animals, following a single TBI. We also describe the pharmacological responses to anti-inflammatory or neuroprotective agents, highlighting the need for an age-specific approach to the development of therapies of TBI.

Antibiotic-induced disturbances of the gut microbiota result in accelerated breast tumor growth

The gut microbiota's function in regulating health has seen it linked to disease progression in several cancers. However, there is limited research detailing its influence in breast cancer (BrCa). This study found that antibiotic-induced perturbation of the gut microbiota significantly increases tumor progression in multiple BrCa mouse models. Metagenomics highlights the common loss of several bacterial species following antibiotic administration. One such bacteria, Faecalibaculum rodentium, rescued this increased tumor growth. Single-cell transcriptomics identified an increased number of cells with a stromal signature in tumors, and subsequent histology revealed an increased abundance of mast cells in the tumor stromal regions. We show that administration of a mast cell stabilizer, cromolyn, rescues increased tumor growth in antibiotic treated animals but has no influence on tumors from control cohorts. These findings highlight that BrCa-microbiota interactions are different from other cancers studied to date and suggest new research avenues for therapy development.

Evaluation of Fluorinated Cromolyn Derivatives as Potential Therapeutics for Alzheimer's Disease

BACKGROUND

Cromolyn is an anti-neuroinflammatory modulator with a multifactorial mechanism of action that has been shown to inhibit amyloid-β (Aβ) aggregation and enhance microglial uptake and clearance of Aβ.

OBJECTIVE

We report the effects of fluoro-cromolyn derivatives on microglial cell toxicity and microglial clearance of Aβ42.

METHODS

Microglial cell toxicity for cromolyn derivatives were determined in naive BV2 microglial cells. Microglial clearance assays were performed with Aβ42 in naive BV2 microglial cell line and single cell clone BV2 line expressing CD33WT. PET imaging was performed for three F-18 analogs in a rhesus macaque.

RESULTS

All compounds but derivative 8 exhibited low microglial cell toxicity. Cromolyn 1 and derivatives 2, 4, and 7 displayed an increased uptake on Aβ42 in naïve BV2 microglial cells. Derivative 4 increased Aβ42 uptake in a dose-dependent manner and at 75μM resulted in a one-fold increase in Aβ42 uptake in BV2-CD33WT. PET imaging for three [18F]cromolyn analogs revealed the order of brain tracer penetration to be 4a > 10 > 2a. Tracer 4a exhibited enhanced uptake in areas of high perfusion (putamen, grey matter, and cerebellum) and lower signal in areas of lower perfusion (caudate, thalamus, and white matter).

CONCLUSION

Substantial uptake of Aβ42 in both naïve BV2 and BV2-CD33WT cells observed with 4 indicate conversion of microglial cells from a pro-inflammatory to an activation state favoring Aβ phagocytosis/clearance. These findings suggest that a fluoro-cromolyn analog could reduce fibril-prone Aβ42in vivo and thereby serve as a therapeutic for the treatment and prevention of AD.

An integrated strategy for the identification and screening of anti-allergy components from natural products based on calcium fluctuations and cell extraction coupled with HPLC-Q-TOF-MS

Allergic diseases are a significant public health problem worldwide. Traditional Chinese medicines (TCMs) with reported anti-allergy effects may be important sources for the development of new anti-allergy drugs. Thus, establishing an analytical method that can simultaneously identify and screen anti-allergic compounds in TCMs is important. The increased concentrations of intracellular calcium ions resulting in mast cell degranulation releasing active mediators play a key role in allergic diseases, which can be used as a potential index to identify anti-allergic herbs and compounds. In this study, we provide a new strategy that was applied to screening natural anti-allergic compounds based on fluorescence calcium ion (Ca²⁺) fluctuation integrated with cell extract and high-performance liquid chromatography-mass spectrometry (HPLC-MS). A low-cost, convenient fluorescence detection Ca²⁺ signaling method was established and successfully applied to identify three herbs. Then, the method was integrated with biospecific cell fishing and HPLC-MS to screen potential active components that have the effect of stabilizing the cell membrane of rat basophilic leukemia granulocytes (RBL-2H3). Seven components, namely, albiflorin and paeoniflorin from Radix Paeoniae Alba, ononin and formononetin from Radix Astragali, cimifugin, 4'-O-β-D-glucosyl-5-O-methylvisamminol, and prim-O-glucosylcimifugin from Radix Saposhnikoviae were fished. These seven compounds have the effect of inhibiting cell Ca²⁺ influx. 4'-O-β-D-Glucosyl-5-O-methylvisamminol, prim-O-glucosylcimifugin, paeoniflorin, ononin, and formononetin significantly inhibit the release of β-hexosaminidase, which is equivalent to the positive drug. In conclusion, the integrated strategy of fluorescence detection calcium ion kinetic method binding with biospecific cell fishing was an effective mode to identify and screen natural anti-allergic compounds.

FAK inhibitor PF-431396 suppresses IgE-mediated mast cell activation and allergic inflammation in mice

Mast cells (MCs) initiate and maintain allergic inflammation. Upon being stimulated with immunoglobulin (Ig)E and antigen (Ag), MCs exhibit FcεRI (high-affinity IgE) receptor-mediated degranulation, cytokine secretion, and increased focal adhesion kinase (FAK) activity. The aims of this study were to examine mechanisms of FAK regulation in IgE-mediated MC activation and the effects of FAK inhibition on MC-mediated allergic responses. FAK activity was manipulated with short hairpin RNA (shRNA) knockdown, FAK overexpression, and the FAK inhibitor PF-431396 (PF). Gene expression and kinase activation were analyzed with quantitative molecular biology assays. PF effects were tested in the passive cutaneous anaphylaxis (PCA), active systemic anaphylaxis (ASA), and allergic conjunctivitis (AC) mouse models. Our results showed that FAK overexpression increased IgE-mediated degranulation and reduced the dexamethasone inhibitory effect on MCs activation. The FAK inhibitor PF diminished MC release of β-hexosaminidase (β-hex), histamine, and inflammatory cytokines, via a mechanism that involves MAPK and NF-κB signaling pathways. CaMKII was identified as a robust FAK-associating protein. Inhibition of CaMKII activation by KN-93 suppressed FAK activity and its downstream pathway. PF attenuated inflammatory responses in our PCA and ASA models, and relieved signs of allergic disease in AC model mice. In conclusions, MC degranulation and production of inflammatory mediators in allergic disease may be consequent to FcεRI crosslinking inducing CaMKII-mediated activation of FAK activity. FAK inhibition may represent a new MC-suppressing treatment strategy for the treatment of allergic diseases.

Cytokine Storm Syndrome in SARS-CoV-2 Infections: A Functional Role of Mast Cells

Cytokine storm syndrome is a cascade of escalated immune responses disposing the immune system to exhaustion, which might ultimately result in organ failure and fatal respiratory distress. Infection with severe acute respiratory syndrome-coronavirus-2 can result in uncontrolled production of cytokines and eventually the development of cytokine storm syndrome. Mast cells may react to viruses in collaboration with other cells and lung autopsy findings from patients that died from the coronavirus disease that emerged in 2019 (COVID-19) showed accumulation of mast cells in the lungs that was thought to be the cause of pulmonary edema, inflammation, and thrombosis. In this review, we present evidence that a cytokine response by mast cells may initiate inappropriate antiviral immune responses and cause the development of cytokine storm syndrome. We also explore the potential of mast cell activators as adjuvants for COVID-19 vaccines and discuss the medications that target the functions of mast cells and could be of value in the treatment of COVID-19. Recognition of the cytokine storm is crucial for proper treatment of patients and preventing the release of mast cell mediators, as impeding the impacts imposed by these mediators could reduce the severity of COVID-19.

Inflammation and tumor progression: signaling pathways and targeted intervention

Cancer development and its response to therapy are regulated by inflammation, which either promotes or suppresses tumor progression, potentially displaying opposing effects on therapeutic outcomes. Chronic inflammation facilitates tumor progression and treatment resistance, whereas induction of acute inflammatory reactions often stimulates the maturation of dendritic cells (DCs) and antigen presentation, leading to anti-tumor immune responses. In addition, multiple signaling pathways, such as nuclear factor kappa B (NF-kB), Janus kinase/signal transducers and activators of transcription (JAK-STAT), toll-like receptor (TLR) pathways, cGAS/STING, and mitogen-activated protein kinase (MAPK); inflammatory factors, including cytokines (e.g., interleukin (IL), interferon (IFN), and tumor necrosis factor (TNF)-α), chemokines (e.g., C-C motif chemokine ligands (CCLs) and C-X-C motif chemokine ligands (CXCLs)), growth factors (e.g., vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β), and inflammasome; as well as inflammatory metabolites including prostaglandins, leukotrienes, thromboxane, and specialized proresolving mediators (SPM), have been identified as pivotal regulators of the initiation and resolution of inflammation. Nowadays, local irradiation, recombinant cytokines, neutralizing antibodies, small-molecule inhibitors, DC vaccines, oncolytic viruses, TLR agonists, and SPM have been developed to specifically modulate inflammation in cancer therapy, with some of these factors already undergoing clinical trials. Herein, we discuss the initiation and resolution of inflammation, the crosstalk between tumor development and inflammatory processes. We also highlight potential targets for harnessing inflammation in the treatment of cancer.

Systemic mastocytosis: The roles of histamine and its receptors in the central nervous system disorders

Mastocytosis is a rare disease of clonal hematological disorders characterized by a pathological accumulation of Mast Cells (MCs) in different tissues, with variable symptomatology and prognosis. Signs and symptoms of Systemic Mastocytosis (SM) are due to pathological infiltration of MCs and to the release of chemical mediators, mainly histamine. Patients with SM may also present with neurological symptoms or complications. The pathophysiology of these neurological disorders remains uncertain to this day, but it can be associated with the infiltration of tissue mastocytes, release of mastocytes' mediators or both. Moreover, there is a lot to understand about the role of neurological symptoms in SM and knowing, for example, what is the real frequency of neurological disorders in SM and if is present a relation between other SM subtypes, because it has been noted that the alteration of the histamine expression may be an initiating factor for susceptibility, gravity and progression of the epigenetic disease. In this review we explain the possible pathophysiological mechanism about neurological symptomatology found in some patients affected by SM, describing the role of histamine and its receptors in the nervous system and, in light of the results, what the future prospects may be for a more specific course of treatment.

Potential of brain mast cells for therapeutic application in the immune response to bacterial and viral infections

A wide range of microorganisms can infect the central nervous system (CNS). The immune response of the CNS provides limited protection against microbes penetrating the blood-brain barrier. This results in a neurological deficit and sometimes leads to high morbidity and mortality rates despite advanced therapies. For the last two decades, different studies have expanded our understanding of the molecular basis of human neuroinfectious diseases, especially concerning the contributions of mast cell interactions with other central nervous system compartments. Brain mast cells are multifunctional cells derived from the bone marrow and reside in the brain. Their proximity to blood vessels, their role as "first responders" their unique receptors systems and their ability to rapidly release pathogen responsive mediators enable them to exert a crucial defensive role in the host-defense system. This review describes key biological and physiological functions of mast cells, concerning their ability to recognize pathogens via various receptor systems, followed by a coordinated and selective mediator release upon specific interactions with pathogenic stimulating factors. The goal of this review is to direct attention to the possibilities for therapeutic applications of mast cells against bacterial and viral related infections. We also focus on opportunities for future research activating mast cells via adjuvants.

COVID-19: Famotidine, Histamine, Mast Cells, and Mechanisms

SARS-CoV-2 infection is required for COVID-19, but many signs and symptoms of COVID-19 differ from common acute viral diseases. SARS-CoV-2 infection is necessary but not sufficient for development of clinical COVID-19 disease. Currently, there are no approved pre- or post-exposure prophylactic COVID-19 medical countermeasures. Clinical data suggest that famotidine may mitigate COVID-19 disease, but both mechanism of action and rationale for dose selection remain obscure. We have investigated several plausible hypotheses for famotidine activity including antiviral and host-mediated mechanisms of action. We propose that the principal mechanism of action of famotidine for relieving COVID-19 symptoms involves on-target histamine receptor H₂ activity, and that development of clinical COVID-19 involves dysfunctional mast cell activation and histamine release. Based on these findings and associated hypothesis, new COVID-19 multi-drug treatment strategies based on repurposing well-characterized drugs are being developed and clinically tested, and many of these drugs are available worldwide in inexpensive generic oral forms suitable for both outpatient and inpatient treatment of COVID-19 disease.

Harnessing the Power of Mast Cells in unconventional Immunotherapy Strategies and Vaccine Adjuvants

Mast cells are long-lived, granular, myeloid-derived leukocytes that have significant protective and repair functions in tissues. Mast cells sense disruptions in the local microenvironment and are first responders to physical, chemical and biological insults. When activated, mast cells release growth factors, proteases, chemotactic proteins and cytokines thereby mobilizing and amplifying the reactions of the innate and adaptive immune system. Mast cells are therefore significant regulators of homeostatic functions and may be essential in microenvironmental changes during pathogen invasion and disease. During infection by helminths, bacteria and viruses, mast cells release antimicrobial factors to facilitate pathogen expulsion and eradication. Mast cell-derived proteases and growth factors protect tissues from insect/snake bites and exposure to ultraviolet radiation. Finally, mast cells release mediators that promote wound healing in the inflammatory, proliferative and remodelling stages. Since mast cells have such a powerful repertoire of functions, targeting mast cells may be an effective new strategy for immunotherapy of disease and design of novel vaccine adjuvants. In this review, we will examine how certain strategies that specifically target and activate mast cells can be used to treat and resolve infections, augment vaccines and heal wounds. Although these strategies may be protective in certain circumstances, mast cells activation may be deleterious if not carefully controlled and any therapeutic strategy using mast cell activators must be carefully explored.

Should mast cells be considered therapeutic targets in multiple sclerosis?

Mast cells are immune cells of the myeloid lineage that are found throughout the body, including the central nervous system. They perform many functions associated with innate and specific immunity, angiogenesis, and vascular homeostasis. Moreover, they have been implicated in a series of pathologies (e.g., hypersensitivity reactions, tumors, and inflammatory disorders). In this review, we propose that this cell could be a relevant therapeutic target in multiple sclerosis, which is a central nervous system degenerative disease. To support this proposition, we describe the general biological properties of mast cells, their contribution to innate and specific immunity, and the participation of mast cells in the various stages of multiple sclerosis and experimental autoimmune encephalomyelitis development. The final part of this review is dedicated to an overview of the available mast cells immunomodulatory drugs and their activity on multiple sclerosis and experimental autoimmune encephalomyelitis, including our own experience related to the effect of ketotifen fumarate on experimental autoimmune encephalomyelitis evolution.

Emerging mechanisms contributing to mast cell-mediated pathophysiology with therapeutic implications

Mast cells are tissue-resident immune cells that play key roles in the initiation and perpetuation of allergic inflammation, usually through IgE-mediated mechanisms. Mast cells are, however, evolutionary ancient immune cells that can be traced back to urochordates and before the emergence of IgE antibodies, suggesting their involvement in antibody-independent biological functions, many of which are still being characterized. Herein, we summarize recent advances in understanding the roles of mast cells in health and disease, partly through the study of emerging non-IgE receptors such as the Mas-related G protein-coupled receptor X2, implicated in pseudo-allergic reactions as well as in innate defense and neuronal sensing; the mechano-sensing adhesion G protein-coupled receptor E2, variants of which are associated with familial vibratory urticaria; and purinergic receptors, which orchestrate tissue damage responses similarly to the IL-33 receptor. Recent evidence also points toward novel mechanisms that contribute to mast cell-mediated pathophysiology. Thus, in addition to releasing preformed mediators contained in granules and synthesizing mediators de novo, mast cells also secrete extracellular vesicles, which convey biological functions. Understanding their release, composition and uptake within a variety of clinical conditions will contribute to the understanding of disease specific pathology and likely lead the way to novel therapeutic approaches. We also discuss recent advances in the development of therapies targeting mast cell activity, including the ligation of inhibitory ITIM-containing receptors, and other strategies that suppress mast cells or responses to mediators for the management of mast cell-related diseases.

John AL, Ginhoux F. Fetal mast cells mediate postnatal allergic responses dependent on maternal IgE

Mast cells (MCs) are central effector cells in allergic reactions that are often mediated by immunoglobulin E (IgE). Allergies commonly start at an early age, and both MCs and IgE are detectable in fetuses. However, the origin of fetal IgE and whether fetal MCs can degranulate in response to IgE-dependent activation are presently unknown. Here, we show that human and mouse fetal MCs phenotypically mature through pregnancy and can be sensitized by maternal IgE. IgE crossed the placenta, dependent on the fetal neonatal Fc receptor (FcRN), and sensitized fetal MCs for allergen-specific degranulation. Both passive and active prenatal sensitization conferred allergen sensitivity, resulting in postnatal skin and airway inflammation after the first allergen encounter. We report a role for MCs within the developing fetus and demonstrate that fetal MCs may contribute to antigen-specific vertical transmission of allergic disease.

Endoglin is Highly Expressed in Human Mast Cells

Endoglin, known to be expressed in proliferating vessels, is of worth when evaluating microvessel density as a prognostic factor in many types of malignancies, including some subtypes of leukemia cells. In childhood acute lymphoblastic leukemia, endoglin is associated with adverse outcome. In bone marrow, endoglin identifies the repopulating hematopoietic stem cells. Mast cells are a component of normal tissue and play an important role in the regulation of several processes, including inflammation and neoplasia. The aim of this study was to evaluate the use of endoglin as a biological marker of mast cells compared with the gold standard stains. We studied 15 specimens of neurofibroma, 9 of mastocytosis, and 6 of fibrous scar tissue through immunohistochemistry (for endoglin and mast cell tryptase) and histochemical staining using toluidine blue. Quantitative analysis of the cells was performed by counting 5 hotspots. The validity of endoglin as a mast cell marker was assessed by intraclass correlation coefficient. The Kruskal-Wallis test was used to compare mast cell count for each marker. A strong endoglin expression was found in the cytoplasmic granules of mast cells within the 3 groups. Similar results were observed with mast cell tryptase as well as toluidine blue. The intraclass correlation coefficient revealed that endoglin is a highly reliable biomarker of mast cells when compared with mast cell tryptase and toluidine blue. In conclusion, endoglin may assist in the diagnosis and pathogenesis study of various processes associated with mast cells. An endoglin-neutralizing treatment for solid cancers and leukemia could also affect mastocytes and the immunologic system.

Rhinitis 2020: A practice parameter update

This comprehensive practice parameter for allergic rhinitis (AR) and nonallergic rhinitis (NAR) provides updated guidance on diagnosis, assessment, selection of monotherapy and combination pharmacologic options, and allergen immunotherapy for AR. Newer information about local AR is reviewed. Cough is emphasized as a common symptom in both AR and NAR. Food allergy testing is not recommended in the routine evaluation of rhinitis. Intranasal corticosteroids (INCS) remain the preferred monotherapy for persistent AR, but additional studies support the additive benefit of combination treatment with INCS and intranasal antihistamines in both AR and NAR. Either intranasal antihistamines or INCS may be offered as first-line monotherapy for NAR. Montelukast should only be used for AR if there has been an inadequate response or intolerance to alternative therapies. Depot parenteral corticosteroids are not recommended for treatment of AR due to potential risks. While intranasal decongestants generally should be limited to short-term use to prevent rebound congestion, in limited circumstances, patients receiving regimens that include an INCS may be offered, in addition, an intranasal decongestant for up to 4 weeks. Neither acupuncture nor herbal products have adequate studies to support their use for AR. Oral decongestants should be avoided during the first trimester of pregnancy. Recommendations for use of subcutaneous and sublingual tablet allergen immunotherapy in AR are provided. Algorithms based on a combination of evidence and expert opinion are provided to guide in the selection of pharmacologic options for intermittent and persistent AR and NAR.

IL33 and Mast Cells-The Key Regulators of Immune Responses in Gastrointestinal Cancers?

The Interleukin (IL-)1 family IL33 is best known for eliciting type 2 immune responses by stimulating mast cells (MCs), regulatory T-cells (Tregs), innate lymphoid cells (ILCs) and other immune cells. MCs and IL33 provide critical control of immunological and epithelial homeostasis in the gastrointestinal (GI) tract. Meanwhile, the role of MCs in solid malignancies appears tissue-specific with both pro and anti-tumorigenic activities. Likewise, IL33 signaling significantly shapes immune responses in the tumor microenvironment, but these effects remain often dichotomous when assessed in experimental models of cancer. Thus, the balance between tumor suppressing and tumor promoting activities of IL33 are highly context dependent, and most likely dictated by the mixture of cell types responding to IL33. Adding to this complexity is the promiscuous nature by which MCs respond to cytokines other than IL33 and release chemotactic factors that recruit immune cells into the tumor microenvironment. In this review, we integrate the outcomes of recent studies on the role of MCs and IL33 in cancer with our own observations in the GI tract. We propose a working model where the most abundant IL33 responsive immune cell type is likely to dictate an overall tumor-supporting or tumor suppressing outcome in vivo. We discuss how these opposing responses affect the therapeutic potential of targeting MC and IL33, and highlight the caveats and challenges facing our ability to effectively harness MCs and IL33 biology for anti-cancer immunotherapy.

Repositioning Chromones for Early Anti-inflammatory Treatment of COVID-19

The COVID-19 pandemic is posing an unprecedented sanitary threat. In the absence of specific vaccines and anti-SARS-CoV-2 drugs, medicines that may assist in tackling the emergency and limiting the high number of fatalities are urgently needed. The repositioning of available drugs to treat COVID-19 is the only and rapid option in the face of the lack of direct antiviral agents and vaccines available. In this light it is important to focus on available drugs, which, based on their pharmacodynamics, could plausibly attenuate viral growth as well as COVID-19’s worst complications. This is the case of chloroquine and tocilizumab which seem to limit virus replication and the severity of interstitial pneumonia, respectively. However, these treatments, particularly those aimed at containing inflammation, are still reserved for the most severe cases. This commentary elaborates on the pharmacological rationale of repositioning the mast cell stabilizer chromones as an adjunctive treatment for SARS‐CoV‐2 infection, and proposes their practical clinical testing as an early, safe, and cost-effective anti-inflammatory intervention in COVID-19 to limit the eventual secondary progression toward life-threatening respiratory complications.

Hydrophobic ion pair loaded self-emulsifying drug delivery system (SEDDS): A novel oral drug delivery approach of cromolyn sodium for management of bronchial asthma

The aim of the present study is to develop a self-emulsifying drug delivery system (SEDDS) for the hydrophobic ion pair (HIP) complex of cromolyn sodium (CS), in order to enhance its intestinal absorption and biological activity. Two ion pairing agents (IPAs) were investigated: hexadecyl pyridininum chloride (HPC) and myristyl trimethyl ammonium bromide (MTAB). The optimum binding efficiency for complexation between investigated IPAs and CS was observed at a molar ratio of 1.5:1, where CS binding efficiency was found to be 76.10 ± 2.12 and 91.37 ± 1.73% for MTAB and HPC, respectively. The two prepared complexes exhibited a significant increase in partition coefficient indicating increased lipophilicity. The optimized CS-HIP complex was incorporated into SEDDS formulations. SEDDS formulations F2 (40% oleic acid, 40% Brij^TM98, 20% propylene glycol) and F3 (25% oleic acid, 50% Brij^TM98, 25% propylene glycol) exhibited nanometric droplet diameters with monodisperse distribution and nearly neutral zeta potential values. Ex vivo intestinal permeation study, using the non-everted gut sac technique, revealed a significantly higher cumulative amount of permeated drug, after 2 h, for F2 and F3 (53.836 and 77.617 µg/cm², respectively) compared to 8.649 µg/cm² for plain CS solution. The in vivo evaluation of plain CS solution compared to F2 and F3 was conducted in an ovalbumin sensitization-induced bronchial asthma rat model. Lung function parameters (tidal volume and peak expiratory flow), biochemical parameters (interleukin-5, immunoglobulin-E, myeloperoxidase and airway remodelling parameters) were assessed in addition to histopathological examination. The results indicated the superiority of F3 followed by F2 compared to plain CS solution for prophylaxis of bronchial asthma in rats.

The Role of Natural Killer Cells and Mast Cells in Female Infertility and Associated Treatment Outcomes

Introduction:

One of the identified causes of infertility has been related to the inability to regulate immunological tolerance of the maternal immune system against the developing fetus, thereby inhibiting the process of implantation. Various immune cells have been identified to contribute to the concept of un-regulated immunological tolerance, such as mast cells (MCs) and natural killer cells (NK). There are available evidences that MC play a role in the pathogenesis of infertility diseases like endometriosis and NK in specific infertility disease.

Objective:

Presently, there are studies to formulate and develop immunosuppressive drugs in order to suppress or inhibit the process of immune rejection caused by maternal immune cells. In addition, there have been reports regarding the use of steroids for the treatment of miscarriage that can inhibit the activity of most immune cells.

Conclusion:

This review is to give a comprehensive mini-review on the role of immune cells, especially mast cells and NK cells in developing novel infertility treatment.

Cough-provocation tests with hypertonic aerosols

Recent advances in cough research suggest a more widespread use of cough-provocation tests to demonstrate the hypersensitivity of the cough reflex arc. Cough-provocation tests with capsaicin or acidic aerosols have been used for decades in scientific studies. Several factors have hindered their use in everyday clinical work: i.e. lack of standardisation, the need for special equipment and the limited clinical importance of the response. Cough-provocation tests with hypertonic aerosols (CPTHAs) involve provocations with hypertonic saline, hypertonic histamine, mannitol and hyperpnoea. They probably act via different mechanisms than capsaicin and acidic aerosols. They are safe and well tolerated and the response is repeatable. CPTHAs can assess not only the sensitivity of the cough reflex arc but also the tendency of the airway smooth muscles to constrict (airway hyper-responsiveness). They can differentiate between subjects with asthma or chronic cough and healthy subjects. The responsiveness to CPTHAs correlates with the cough-related quality of life among asthmatic subjects. Furthermore, the responsiveness to them decreases during treatment of chronic cough. A severe response to CPTHAs may indicate poor long-term prognosis in chronic cough. The mannitol test has been stringently standardised, is easy to administer with simple equipment, and has regulatory approval for the assessment of airway hyper-responsiveness. Manual counting of coughs during a mannitol challenge would allow the measurement of the function of the cough reflex arc as a part of clinical routine.

Cough-provocation tests with hypertonic aerosols offer the possibility to measure the function of the cough reflex arc even in everyday clinical workhttp://bit.ly/2RTOfMI

The antipsychotic drug pimozide inhibits IgE-mediated mast cell degranulation and migration

BACKGROUND

Mast cells (MCs) mediate a key role in allergic diseases. Detailed studies of how the neuroleptic drug pimozide affects MC activity are lacking. The aim of this study was to investigate pimozide inhibition of immunoglobulin E (IgE)-mediated MC activation and MC-mediated allergic responses.

METHOD

MCs were stimulated with anti-dinitrophenyl (DNP) IgE antibodies and DNP-horse serum albumin (HSA) antigen (Ag), and anti-allergic pimozide effects were detected by measuring β-hexosaminidase levels. Morphological changes were observed histologically. In vivo pimozide effects were assessed in passive cutaneous anaphylaxis (PCA) and ovalbumin (OVA)-sensitized active systemic anaphylaxis mouse (ASA) model experiments. Levels of phosphorylated (p-) SYK (spleen tyrosine kinase) and MAPKs (mitogen-activated protein kinases) were detected in western blots.

RESULTS

We found that pimozide inhibited MC degranulation, reduced MC release of β-hexosaminidase dose-dependently in activated RBL-2H3 (IC₅₀: 13.52 μM) and bone marrow derived MC (BMMC) (IC₅₀: 42.42 μM), and reduced MC morphological changes. The IgE/Ag-induced migration effect was suppressed by pimozide treatment dose-dependently. Pimozide down-regulated IgE/Ag-induced phosphorylation of SYK and MAPKs in activated MCs. Moreover, pimozide attenuated allergic reactions in PCA and ASA model mice, and decreased MC populations among splenic cells.

CONCLUSIONS

The antipsychotic drug pimozide can suppress IgE-mediated MC activation in vitro and in vivo and should be considered for repurposing to suppress MC-mediated diseases.

Histamine-mediated autocrine signaling in mesenteric perilymphatic mast cells

Lymphatic vessels play a critical role in mounting a proper immune response by trafficking peripheral immune cells to draining lymph nodes. Mast cells (MCs) are well known for their roles in type I hypersensitivity reactions, but little is known about their secretory regulation in the lymphatic niche. MCs, as innate sensor and effector cells, reside close to mesenteric lymphatic vessels (MLVs), and their activation and ability to release histamine influences the lymphatic microenvironment in a histamine-NF-κB-dependent manner. Using an established experimental protocol involving surgical isolation of rat mesenteric tissue segments, including MLVs and surrounding perilymphatic tissues, we tested the hypothesis that perilymphatic mesenteric MCs possess histamine receptors (HRs) that bind and respond to the histamine released from these same MCs. Under various experimental conditions, including inflammatory stimulation by LPS, we measured histamine in mesenteric perilymphatic tissues, evaluated expression of histidine decarboxylase in MCs along with the degree of MC degranulation, assessed the functional status of HRs in MCs, and evaluated the ability of histamine itself to induce MC activation. Finally, we evaluated the importance of MCs and HR1 and -2 for MLV-directed trafficking of CD11b/c-positive cells during acute tissue inflammation. Our data indicate the existence of a functionally potent MC-histamine autocrine regulatory loop, the elements of which are crucially important for acute inflammation-induced trafficking of the CD11b/c-positive cells toward MLVs. This MC-histamine loop serves as a first-line cellular servo control system, playing a key role in the innate and adaptive immune response as well as NF-κB-mediated maintenance of body homeostasis.

Acupoint application inhibits nerve growth factor and attenuates allergic inflammation in allergic rhinitis model rats

Background

Acupoint application therapy (AAT) has been widely used to treat allergic inflammation induced by allergic rhinitis (AR). The therapeutic effect of acupoint application is obvious. But the underlying therapeutic mechanism is still indistinct. Nerve growth factor (NGF) expression showed a dramatic rise in nasal mucosa tissue after AR, and allergic inflammation also increased significantly. To demonstrate how AAT can improve allergic inflammation by down-regulating the expression of NGF, AR rat models were established by intraperitoneal injection of ovalbumin (OVA) and nasal drops in SD rats. The number of nasal rubbing, sneezing and the degree of runny nose were observed and the symptoms were scored by behavioral symptom scoring method within 3 min. The expression levels of NGF and its downstream key proteins, such as IL-4, IL-5, IL-13, IgE and IFN-γ were determined by q-PCR, Western blot analysis, ELISA and immunofluorescence staining. Furthermore, H&E staining and toluidine blue staining were used to observe the pathological structure of nasal mucosa and mast cells in nasal mucosa, and the ultrastructure of nasal mucosa was observed by electron microscopy.

Results

Our data demonstrated that acupoint application significantly reduced the score of behavioral symptoms, and decreased the expression levels of NGF and its downstream key proteins, including IL-4, IL-5, IL-13, IgE, as well as promoting the expression level of IFN-γ in nasal mucosa tissue in AR rats. Thus, the activation of IgE and viability of mast cells was inhibited.

Conclusion

Our findings suggest that AAT can attenuate allergic inflammation by inhibiting the expression of NGF and its downstream pathway.

The Theranostics Role of Mast Cells in the Pathophysiology of Rosacea

Rosacea is a chronic inflammatory cutaneous disorder that adversely affects patient's health and quality of life due to the complex course and the need for repeated treatment. The exact molecular mechanisms of rosacea are unclear. Mast cells are innate immune cells that can be found in virtually all tissues. Recently, increasing evidence has indicated that mast cells have important effects on the pathogenesis of rosacea. In this review article, we describe recent advances of skin mast cells in the development of rosacea. These studies suggested that mast cells can be an important immune cell that connected innate immunity, nerves, and blood vessels in the development of rosacea. Moreover, we review the inhibition of mast cells for the potential treatment of rosacea.

Calming Down Mast Cells with Ketotifen: A Potential Strategy for Multiple Sclerosis Therapy?

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) characterized by extensive inflammation, demyelination, axonal loss and gliosis. Evidence indicates that mast cells contribute to immunopathogenesis of both MS and experimental autoimmune encephalomyelitis (EAE), which is the most employed animal model to study this disease. Considering the inflammatory potential of mast cells, their presence at the CNS and their stabilization by certain drugs, we investigated the effect of ketotifen fumarate (Ket) on EAE development. EAE was induced in C57BL/6 mice by immunization with MOG35-55 and the animals were injected daily with Ket from the seventh to the 17th day after disease induction. This early intervention with Ket significantly reduced disease prevalence and severity. The protective effect was concomitant with less NLRP3 inflammasome activation, rebalanced oxidative stress and also reduced T cell infiltration at the CNS. Even though Ket administration did not alter mast cell percentage at the CNS, it decreased the local CPA3 and CMA1 mRNA expression that are enzymes typically produced by these cells. Evaluation of the CNS-barrier permeability indicated that Ket clearly restored the permeability levels of this barrier. Ket also triggered an evident lymphadenomegaly due to accumulation of T cells that produced higher levels of encephalitogenic cytokines in response to in vitro stimulation with MOG. Altogether these findings reinforce the concept that mast cells are particularly relevant in MS immunopathogenesis and that Ket, a known stabilizer of their activity, has the potential to be used in MS control.