Mast cell chymase and tryptase as targets for cardiovascular and metabolic diseases

Identifying pyroptosis- and inflammation-related genes in intracranial aneurysms based on bioinformatics analysis

BACKGROUND

Intracranial aneurysm (IA) is the most common cerebrovascular disease, and subarachnoid hemorrhage caused by its rupture can seriously impede nerve function. Pyroptosis is an inflammatory mode of cell death whose underlying mechanisms involving the occurrence and rupture of IAs remain unclear. In this study, using bioinformatics analysis, we identified the potential pyroptosis-related genes (PRGs) and performed their inflammatory response mechanisms in IAs.

METHODS

The mRNA expression matrix of the IA tissue was obtained from the Gene Expression Omnibus database, and 51 PRGs were obtained from previous articles collected from PubMed. The differentially expressed PRGs (DEPRGs) were performed using R software. Subsequently, we performed enrichment analysis, constructed a protein-protein interaction network, performed weighted gene coexpression network analysis (WGCNA) and external validation using another dataset, and identified a correlation between hub genes and immune cell infiltration. Finally, the expression and tissue distribution of these hub genes in IA tissues were detected using Western blotting and immunohistochemical (IHC) staining.

RESULTS

In total, 12 DEPRGs associated with IA were identified in our analysis, which included 11 up-regulated and one down-regulated genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed that the DEPRGs were mostly enriched in the NOD-like receptor signaling pathway, interleukin-1 beta production, and the inflammasome complex. Three hub genes, NLRP3, IL1B and IL18, were identified using Cytoscape software and the WGCNA correlation module, and external validation revealed statistically significant differences between the expression of these hub genes in the ruptured and unruptured aneurysm groups (p < 0.05). Furthermore, all AUC values were > 0.75. Immune cell infiltration analysis suggested that the hub genes are related to CD8 T cell, macrophages and mast cells. Finally, IHC staining revealed that the protein levels of these hub genes were higher in ruptured and unruptured IA tissues than in normal tissues (p < 0.05).

CONCLUSION

The results of bioinformatics analysis showed that pyroptosis is closely related to the formation and rupture of IA, and identified three potential hub genes involved in the pyroptosis and infiltration ofcells. Our findings may improve the understanding of the mechanisms underlying pyroptosis in IA.

Renin-Angiotensin System: Updated Understanding and Role in Physiological and Pathophysiological States

The classical view of the renin-angiotensin system (RAS) is that of the circulating hormone pathway involved in salt and water homeostasis and blood pressure regulation. It is also involved in the pathogenesis of cardiac and renal disorders. This led to the creation of drugs blocking the actions of this classical pathway, which improved cardiac and renal outcomes. Our understanding of the RAS has significantly expanded with the discovery of new peptides involved in this complex pathway. Over the last two decades, a counter-regulatory or protective pathway has been discovered that opposes the effects of the classical pathway. Components of RAS are also implicated in the pathogenesis of obesity and its metabolic diseases. The continued discovery of newer molecules also provides novel therapeutic targets to improve disease outcomes. This article aims to provide an overview of an updated understanding of the RAS, its role in physiological and pathological processes, and potential novel therapeutic options from RAS for managing cardiorenal disorders, obesity, and related metabolic disorders.

Mast Cells as a Potential Target of Molecular Hydrogen in Regulating the Local Tissue Microenvironment

Knowledge of the biological effects of molecular hydrogen (H₂), hydrogen gas, is constantly advancing, giving a reason for the optimism in several healthcare practitioners regarding the management of multiple diseases, including socially significant ones (malignant neoplasms, diabetes mellitus, viral hepatitis, mental and behavioral disorders). However, mechanisms underlying the biological effects of H₂ are still being actively debated. In this review, we focus on mast cells as a potential target for H₂ at the specific tissue microenvironment level. H₂ regulates the processing of pro-inflammatory components of the mast cell secretome and their entry into the extracellular matrix; this can significantly affect the capacity of the integrated-buffer metabolism and the structure of the immune landscape of the local tissue microenvironment. The analysis performed highlights several potential mechanisms for developing the biological effects of H₂ and offers great opportunities for translating the obtained findings into clinical practice.

Host-Derived Cytotoxic Agents in Chronic Inflammation and Disease Progression

At inflammatory sites, cytotoxic agents are released and generated from invading immune cells and damaged tissue cells. The further fate of the inflammation highly depends on the presence of antagonizing principles that are able to inactivate these host-derived cytotoxic agents. As long as the affected tissues are well equipped with ready-to-use protective mechanisms, no damage by cytotoxic agents occurs and resolution of inflammation is initiated. However, long-lasting and severe immune responses can be associated with the decline, exhaustion, or inactivation of selected antagonizing principles. Hence, cytotoxic agents are only partially inactivated and contribute to damage of yet-unperturbed cells. Consequently, a chronic inflammatory process results. In this vicious circle of permanent cell destruction, not only novel cytotoxic elements but also novel alarmins and antigens are liberated from affected cells. In severe cases, very low protection leads to organ failure, sepsis, and septic shock. In this review, the major classes of host-derived cytotoxic agents (reactive species, oxidized heme proteins and free heme, transition metal ions, serine proteases, matrix metalloproteases, and pro-inflammatory peptides), their corresponding protective principles, and resulting implications on the pathogenesis of diseases are highlighted.

Protease Profile of Tumor-Associated Mast Cells in Melanoma

Mast cells (MCs) produce a variety of mediators, including proteases—tryptase, chymase, and carboxypeptidases—which are important for the immune response. However, a detailed assessment of the mechanisms of biogenesis and excretion of proteases in melanoma has yet to be carried out. In this study, we present data on phenotype and secretory pathways of proteases in MCs in the course of melanoma. The development of melanoma was found to be accompanied by the appearance in the tumor-associated MC population of several pools with a predominant content of one or two specific proteases with a low content or complete absence of others. Elucidation of the molecular and morphological features of the expression of MC proteases in melanoma allows us a fresh perspective of the pathogenesis of the disease, and can be used to clarify MCs classification, the disease prognosis, and evaluate the effectiveness of ongoing antitumor therapy.

Insights into Early-Pregnancy Mechanisms: Mast Cells and Chymase CMA1 Shape the Phenotype and Modulate the Functionality of Human Trophoblast Cells, Vascular Smooth-Muscle Cells and Endothelial Cells

Spiral-artery (SA) remodeling is a fundamental process during pregnancy that involves the action of cells of the initial vessel, such as vascular smooth-muscle cells (VSMCs) and endothelial cells, but also maternal immune cells and fetal extravillous trophoblast cells (EVTs). Mast cells (MCs), and specifically chymase-expressing cells, have been identified as key to a sufficient SA-remodeling process in vivo. However, the mechanisms are still unclear. The purpose of this study is to evaluate the effects of the MC line HMC-1 and recombinant human chymase (rhuCMA1) on human primary uterine vascular smooth-muscle cells (HUtSMCs), a human trophoblast cell line (HTR8/SV-neo), and human umbilical-vein endothelial cells (HUVEC) in vitro. Both HMC-1 and rhuCMA1 stimulated migration, proliferation, and changed protein expression in HUtSMCs. HMC-1 increased proliferation, migration, and changed gene expression of HTR8/SVneo cells, while rhuCMA treatment led to increased migration and decreased expression of tissue inhibitors of matrix metalloproteinases. Additionally, rhuCMA1 enhanced endothelial-cell-tube formation. Collectively, we identified possible mechanisms by which MCs/rhuCMA1 promote SA remodeling. Our findings are relevant to the understanding of this crucial step in pregnancy and thus of the dysregulated pathways that can lead to pregnancy complications such as fetal growth restriction and preeclampsia.

Histamine 2 receptors in cardiovascular biology: A friend for the heart

Undermining new mediators involved in the development and progression of cardiovascular diseases (CVDs) is vital for better disease management. Existing studies implicate a crucial role for inflammation and inflammatory cells, particularly mast cells, in cardiac diseases. Interestingly, the mast cell mediator, histamine, and its receptors profoundly impact the pathophysiology of the heart, resulting in hypertension-induced cardiac hypertrophy and other cardiac anomalies. In this review, we provide a detailed description of mast cell activation, mediators, and histamine receptors, with a particular focus on histamine 2 receptors (H2Rs). Preclinical and clinical studies using histamine receptor antagonists report improvement in cardiac function. Insights into the precise function of histamine receptors will aid in developing novel therapies and pave the way for repurposing antihistamines for cardiovascular diseases.

Chymase inhibition: A key factor in the anti-inflammatory activity of ethanolic extracts and spilanthol isolated from Acmella oleracea

ETHNOPHARMACOLOGICAL RELEVANCE

Acmella oleracea (L.) R. K. Jansen (Asteraceae), known as jambú in Brazil, is used in traditional medicine as analgesic and for inflammatory conditions, characterized by the presence of N-alkylamides, mainly spilanthol. This bioactive compound is responsible for the above-described pharmacological properties, including sialagogue and anesthetic.

AIM OF THE STUDY

This study aimed to characterize the anti-inflammatory effects of A. oleracea leaves (AOEE-L) and flowers (AOEE-F) extracts, including an isolated alkylamide (spilanthol), using in vitro and in vivo models. The mechanism underlying this effect was also investigated.

MATERIALS AND METHODS

Extracts were analyzed by HPLC-ESI-MS/MS in order to characterize the N-alkylamides content. AOEE-L, AOEE-F (25-100 μg/mL) and spilanthol (50-200 μM) were tested in vitro on VSMC after stimulation with hyperglycemic medium (25 mM glucose). Their effects over nitric oxide (NO) generation, chymase inhibition and expression, catalase (CAT), superoxide anion (SOD) radical activity were evaluated. After an acute administration of extracts (10-100 mg/mL) and spilanthol (6.2 mg/mL), the anti-inflammatory effects were evaluated by applying the formalin test in rats. Blood was collected to measure serum aminotransferases activities, NO activity, creatinine and urea.

RESULTS

A number of distinct N-alkylamides were detected and quantified in AOEE-L and AOEE-F. Spilanthol was identified in both extracts and selected for experimental tests. Hyperglycemic stimulation in VSMC promoted the expression of inflammatory parameters, including chymase, NO, CAT and SOD activity and chymase expression, all of them attenuated by the presence of the extracts and spilanthol. The administration of extracts or spilanthol significantly inhibited edema formation, NO production and cell tissue infiltration in the formalin test, without causing kidney and liver toxicity.

CONCLUSION

Taken together, these results provide evidence for the anti-inflammatory activity of leaves and flowers extracts of jambú associated distinctly with their chemical profile. The effects appear to be associated with the inhibition of chymase activity, suppression of the proinflammatory cytokine NO and antioxidant activities.

Co- localization of Flt1 and tryptase of mast cells in skin wound of rats with type I diabetes: Initial studies

Random skin flap (RSF) is commonly used in plastic and reconstructive surgery, but its distal part often occurs ischemia. Type 1 Diabetes mellitus (T1DM), may be detrimental for flap survival by provide sever ischemia. We sought to determine the influence of DM on the relation between mast cells and angiogenesis by examining tryptase and Fms-like tyrosine kinase 1 (Flt-1), a well-known vascular endothelial growth factor receptor (VEGFR-1), in the surviving areas of RSF in healthy and diabetic rats. 16 male rats divided into healthy and diabetic groups. T1DM was created in the diabetic rats, followed by generation of a RSF in both the control and diabetic rat. On day 7, the surviving areas of each RSF were recorded. Then animals were euthanized, and numbers of vessels, mast cells and co-localization of mast cell tryptase and Flt-1 were analyzed. T1DM decreased survival areas in the RSF compared to the healthy rats, with higher percentage of intact and degranulated mast cells. T1DM elevated the expression percentage of tryptase and VEGFR-1in the proximal and middle areas of the survival parts of the RSF in most diabetic rats. Generally, our results showed that mast cell degranulation might have a positive correlation with VEGFR-1 and in this current model of ischemic tissue in diabetic rats, this finding could lead to poor angiogenesis and weakened blood vessel function, which might result in decreased RSF survival. Additional molecular mechanisms that pertain to the effects of DM on ischemic tissues healing such as this RSF model should be determined by further investigations.

Emerging Roles of Mast Cells in the Regulation of Lymphatic Immuno-Physiology

Mast cells (MCs) are abundant in almost all vascularized tissues. Furthermore, their anatomical proximity to lymphatic vessels and their ability to synthesize, store and release a large array of inflammatory and vasoactive mediators emphasize their significance in the regulation of the lymphatic vascular functions. As a major secretory cell of the innate immune system, MCs maintain their steady-state granule release under normal physiological conditions; however, the inflammatory response potentiates their ability to synthesize and secrete these mediators. Activation of MCs in response to inflammatory signals can trigger adaptive immune responses by dendritic cell-directed T cell activation. In addition, through the secretion of various mediators, cytokines and growth factors, MCs not only facilitate interaction and migration of immune cells, but also influence lymphatic permeability, contractility, and vascular remodeling as well as immune cell trafficking through the lymphatic vessels. In summary, the consequences of these events directly affect the lymphatic niche, influencing inflammation at multiple levels. In this review, we have summarized the recent advancements in our understanding of the MC biology in the context of the lymphatic vascular system. We have further highlighted the MC-lymphatic interaction axis from the standpoint of the tumor microenvironment.

Liquid Chromatography Tandem Mass Spectrometry Based Label-Free Quantification Method for Assessment of Allergen-Induced Anaphylactoid Reactions

Mast cells are essential in mediating inflammatory processes. When activated, mast cells can rapidly release characteristic granules and various mediators into the interstitium. Tryptase (TPS) and β-hexosaminidase (HEXB) are typical protease mediators stored in granules and released upon activation. They have been recognized as important biomarkers of anaphylaxis, and the released level is associated with the severity of allergic reactions. In this study, a sensitive, accurate, and selective liquid chromatography tandem mass spectrometry (LC-MS/MS) method for simultaneously quantifying the two biomarkers was developed and validated in LAD2 cell culture supernatant, and P₁₄R was used as internal standard. Good linearity was observed in the range of 50-2500 ng/mL for TPS and 10-2000 ng/mL for HEXB both with R² > 0.99. The matrix effect and recovery were both within acceptable limits. We quantified TPS and HEXB released from Laboratory of Allergic Disease 2 (LAD2) mast cells treated with several potential allergens, and the results demonstrate that the method can be used to investigate TPS and HEXB levels in LAD2 mast cell model during allergy research. We anticipate our approach to be a robust and sensitive assessment method for more biomarkers with similar kinetics characteristics and to be a major tool of allergic drug assessment or antiallergic drug development in research.

Mast cell chymase: morphofunctional characteristics

During degranulation, mast cells secrete a specific set of mediators defined as "secretome" including the preformed mediators that have already been synthesized by a cell and contained in the cytoplasmic granules. This group includes serine proteases, in particular, chymase and tryptase. Biological significance of chymase depends on the mechanisms of degranulation and is characterized by selective effects on the cellular and non-cellular components of the specific tissue microenvironment. Chymase is known to be closely involved in the mechanisms of inflammation and allergy, angiogenesis, and oncogenesis, remodeling of the extracellular matrix of the connective tissue and changes in organ histoarchitectonics. Number of chymase-positive mast cells in the intra-organ population, and the mechanisms of biogenesis and secretome degranulation appear to be the informative criteria for interpreting the state of the internal organs, characterizing not only the diagnostic efficacy but also the properties of targets of pharmacotherapy. In this review, we discussed the current state of knowledge about mast cell chymase as one of the mast cell secretome proteases. Main issues of the reviewed publications are highlighted with our microscopic images of mast cell chymase visualized using immunohistochemical staining.

Multifunctional Role of Chymase in Acute and Chronic Tissue Injury and Remodeling

Chymase is the most efficient Ang II (angiotensin II)-forming enzyme in the human body and has been implicated in a wide variety of human diseases that also implicate its many other protease actions. Largely thought to be the product of mast cells, the identification of other cellular sources including cardiac fibroblasts and vascular endothelial cells demonstrates a more widely dispersed production and distribution system in various tissues. Furthermore, newly emerging evidence for its intracellular presence in cardiomyocytes and smooth muscle cells opens an entirely new compartment of chymase-mediated actions that were previously thought to be limited to the extracellular space. This review illustrates how these multiple chymase-mediated mechanisms of action can explain the residual risk in clinical trials of cardiovascular disease using conventional renin-angiotensin system blockade.

Increased mast cell number is associated with a decrease in beta-cell mass and regeneration in type 2 diabetic rats

The role of mast cells (MCs) in type 2 diabetes (T2D) is not thoroughly studied as much as in T1D. Therefore in the current study we investigated correlation between these cells and various parameters of islets of Langerhans (IOL) in rats which were equally divided (n = 40) into; control and diabetic groups. We detected a significantly increased (p < 0.05) MC count (MCC) in the diabetic IOL compared to the control, together with a noticeable intra-islet seeding of these cells which displayed a tryptase positive immunostaining. A significant positive correlation (p < 0.05) between MCC and the % of glucagon cells per islet was detected in DM, unlike mass of the islets, mass of β-cells, and % of β-cells per islet which were negatively correlated with MCC. Similarly, there was a negative correlation between MCC with β-cell proliferation and neogenesis frequency in DM. This highlights the potential association between the increased MC number and the diminished islet`s mass as well as regeneration which may fasten the progression of T2D.

Biomarkers for evaluation of mast cell and basophil activation

Mast cells and basophils play a pathogenetic role in allergic, inflammatory, and autoimmune disorders. These cells have different development, anatomical location and life span but share many similarities in mechanisms of activation and type of mediators. Mediators secreted by mast cells and basophils correlate with clinical severity in asthma, chronic urticaria, anaphylaxis, and other diseases. Therefore, effective biomarkers to measure mast cell and basophil activation in vivo could potentially have high diagnostic and prognostic values. An ideal biomarker should be specific for mast cells or basophils, easily and reproducibly detectable in blood or biological fluids and should be metabolically stable. Markers of mast cell and basophil include molecules secreted by stimulated cells and surface molecules expressed upon activation. Some markers, such as histamine and lipid mediators are common to mast cells and basophils whereas others, such as tryptase and other proteases, are relatively specific for mast cells. The best surface markers of activation expressed on mast cells and basophils are CD63 and CD203. While these mediators and surface molecules have been associated to a variety of diseases, none of them fulfills requirements for an optimal biomarker and search for better indicators of mast cell/basophil activation in vivo is ongoing.

Correlation between pancreatic mast cells and the low grade inflammation in adipose tissue of experimental prediabetes

The role of mast cells (MCs) in prediabetes (Pre-DM) is not clearly elucidated. In the current study rats (n = 22 each) were divided equally into; control and Pre-DM (received high fat diet, HFD) groups. Samples from pancreas as well as from visceral adipose tissue (VAT) were studied for the consequent changes. We detected a significantly increased mast cell count (MCC) in the pancreas of Pre-DM compared to that of control. Frequent degranulation of MC granules was observed in Pre-DM. VAT of the Pre-DM had significantly increased (p < 0.05) macrophages (CD68⁺) and mast cells (tryptase⁺) compared to that of the control. A significant increase (p < 0.05) in CD68 mRNA expression as well as in the level of IL-1 β, IL-6, TNF-α and TGF- β1 was detected in VAT of Pre-DM with a significant positive correlation (p < 0.05) with the MCC. All these findings may indicate a potential role of MC in the low grade inflammation of VAT in Pre-DM.

Proteases: Pivot Points in Functional Proteomics

Proteases drive the life cycle of all proteins, ensuring the transportation and activation of newly minted, would-be proteins into their functional form while recycling spent or unneeded proteins. Far from their image as engines of protein digestion, proteases play fundamental roles in basic physiology and regulation at multiple levels of systems biology. Proteases are intimately associated with disease and modulation of proteolytic activity is the presumed target for successful therapeutics. "Proteases: Pivot Points in Functional Proteomics" examines the crucial roles of proteolysis across a wide range of physiological processes and diseases. The existing and potential impacts of proteolysis-related activity on drug and biomarker development are presented in detail. All told the decisive roles of proteases in four major categories comprising 23 separate subcategories are addressed. Within this construct, 15 sets of subject-specific, tabulated data are presented that include identification of proteases, protease inhibitors, substrates, and their actions. Said data are derived from and confirmed by over 300 references. Cross comparison of datasets indicates that proteases, their inhibitors/promoters and substrates intersect over a range of physiological processes and diseases, both chronic and pathogenic. Indeed, "Proteases: Pivot Points …" closes by dramatizing this very point through association of (pro)Thrombin and Fibrin(ogen) with: hemostasis, innate immunity, cardiovascular and metabolic disease, cancer, neurodegeneration, and bacterial self-defense.

Markers of anaphylaxis - a systematic review

Anaphylaxis is defined as severe, life-threatening, systemic or general, immediate reaction of hypersensitivity, with repeatable symptoms caused by the dose of stimulus which is well tolerated by healthy persons. The proper diagnosis, immediate treatment and differential diagnosis are crucial for saving patient's life. However, anaphylaxis is relatively frequently misdiagnosed or confused with other clinical entities. Thus, there is a continuous need for identifying detectable markers improving the proper diagnosis of anaphylaxis. Here we presented currently known markers of anaphylaxis and discussed in more detail the most clinically valuable ones: tryptase, platelet activacting factor (PAF), PAF-acethylhydrolase, histamine and its metabolites.

Adenosine activates Gαs proteins and inhibits C3a-induced activation of human mast cells

Anaphylatoxin C3a and adenosine receptors (AR) are implicated in the inflammatory process associated with allergic rhinitis and asthma by modifying mast cell (MC) responses. Possible interactions between these G-protein coupled receptor (GPCR) pathways in MCs have not yet been demonstrated. LAD2 human MC were stimulated with C3a in the presence or absence of AR agonists and antagonists and their adhesion, chemotaxis and mediator release were measured. The pan-specific AR agonist, 5'-N-Ethylcarboxamidoadenosine (NECA) inhibited C3a-induced LAD2 cell migration, adhesion, degranulation, production of CCL2, and ERK1/2 phosphorylation. The selective A_2A receptor agonist CGS 21680 inhibited C3a-mediated degranulation, while the A_2B and A₃ receptor agonists BAY 60-6583 and IB-MECA, respectively, had no effect. Moreover, an A_2A receptor antagonist SCH 58261 blocked the inhibitory effect of NECA on C3a-induced degranulation, suggesting that inhibition of degranulation was mediated through the A_2A receptor. NECA increased intracellular cAMP in C3a-activated mast cells, suggesting that Gα_s protein signals are required for adenosine-induced inhibition of C3a-mediated human mast cell activation. The adenylyl cyclase inhibitor SQ 22536 attenuated the inhibitory effect of NECA on C3a-activated degranulation, and the A_2A agonist CSG 21680 potentiated the inhibition of mast cell activation mediated by the A_2A receptor. Our results suggest that adenosine inhibits C3a-mediated activation of human mast cells, possibly through a Gα_s protein-dependent pathway.

Elevated seminal plasma estradiol and epigenetic inactivation of ESR1 and ESR2 is associated with CP/CPPS

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is associated with urinary tract symptoms and hormonal imbalances amongst others. The heterogeneous clinical presentation, unexplored molecular background and lack of prostate biopsies complicate therapy. Here, using liquid biopsies, we performed a comprehensive translational study on men diagnosed with CP/CPPS type III (n= 50; median age 39.8, range 23-65) and age-matched controls (n= 61; median age 36.8, range 20-69), considering biochemical parameters of blood and ejaculates, and epigenetic regulation of the estrogen receptor genes (ESR1 and ESR2) in leukocytes isolated from blood (systemic regulation) and in somatic cells isolated from ejaculates (local regulation). We found elevated 17β-estradiol (E2) levels in seminal plasma, but not in blood plasma, that was significantly associated with CP/CPPS and impaired urinary tract symptoms. In ejaculated somatic cells of CP/CPPS patients we found that ESR1 and ESR2 were both significantly higher methylated in CpG-promoters and expressionally down-regulated in comparison to controls. Mast cells are reported to contribute to CP/CPPS and are estrogen responsive. Consistent with this, we found that E2 -treatment of human mast cell lines (HMC-1 and LAD2) resulted in altered cytokine and chemokine expression. Interestingly, in HMC-1 cells, possessing epigenetically inactivated ESR1 and ESR2, E2 -treatment led to a reduced transcription of a number of inflammatory genes. Overall, these data suggest that elevated local E2 levels associate with an epigenetic down-regulation of the estrogen receptors and have a prominent role in CP/CPPS. Investigating E2 levels in semen could therefore serve as a promising biomarker to select patients for estrogen targeted therapy.

Review of various molecular targets on mast cells and its relation to obesity: A future perspective

Mast cells are stimulatory factors in prognosis of various immunogenic and allergic diseases in human body. These cells play an important role in various immunological and metabolic diseases. The aim of present article is to explore the molecular targets to suppress the over expression of mast cells in obesity. The last 20 years literature were searched by various bibliographic data bases like Pubmed, google Scholar, Scopus and web of Science. The data were collected by keywords like "Mast Cell" "obesity" and "role of mast cell or role in obesity". Articles and their abstract were reviewed with a counting of 827 publications, in which 87 publications were considered for study and remaining was excluded because of its specificity to the subject. This review explains the characteristics, molecular targets and role of mast cells in obesity and existing research with mast cells to the area of metabolic diseases.

Mast cells regulate myofilament calcium sensitization and heart function after myocardial infarction

Ngkelo et al. use a mast cell–deficient mouse model to reveal a protective role of mast cells in myocardial infarction, through regulation of the cardiac contractile machinery.

Acute myocardial infarction (MI) is a severe ischemic disease responsible for heart failure and sudden death. Inflammatory cells orchestrate postischemic cardiac remodeling after MI. Studies using mice with defective mast/stem cell growth factor receptor c-Kit have suggested key roles for mast cells (MCs) in postischemic cardiac remodeling. Because c-Kit mutations affect multiple cell types of both immune and nonimmune origin, we addressed the impact of MCs on cardiac function after MI, using the c-Kit–independent MC-deficient (Cpa3^Cre/+) mice. In response to MI, MC progenitors originated primarily from white adipose tissue, infiltrated the heart, and differentiated into mature MCs. MC deficiency led to reduced postischemic cardiac function and depressed cardiomyocyte contractility caused by myofilament Ca²⁺ desensitization. This effect correlated with increased protein kinase A (PKA) activity and hyperphosphorylation of its targets, troponin I and myosin-binding protein C. MC-specific tryptase was identified to regulate PKA activity in cardiomyocytes via protease-activated receptor 2 proteolysis. This work reveals a novel function for cardiac MCs modulating cardiomyocyte contractility via alteration of PKA-regulated force–Ca²⁺ interactions in response to MI. Identification of this MC-cardiomyocyte cross-talk provides new insights on the cellular and molecular mechanisms regulating the cardiac contractile machinery and a novel platform for therapeutically addressable regulators.

Mast cell specific immunological biomarkers and metabolic syndrome among middle-aged and older Chinese adults

The main aim of this study is to explore whether these mast cell specific immunological biomarkers [immunoglobulin E (IgE), chymase and tryptase] is an independent risk factor of MetS and whether the combined action of these biomarkers increased the associations with MetS. Three mast cell-specific immunological biomarkers were measured using enzyme linked immunosorbent assay (ELISA). One-way analysis of covariance and logistic regression models were used for analyzing the associations between immunological biomarkers with MetS. A total of 340 participants, 82 (24.1%) individuals had diabetes mellitus, 31 (9.1%) had MetS (without diabetes mellitus) and 110 had MetS plus diabetes mellitus. After adjusting by multivariable (age, gender, smoking, and family history for hypertension), compared with no diabetes mellitus or MetS group (reference group), hs-CRP was associated with diabetes mellitus [OR (odds ratio): 2.29 (1.15-4.57, 95% CI (confidence interval), p=0.019] and MetS plus diabetes mellitus [OR: 2.20 (1.05-4.61, 95% CI), p=0.036], IgE was associated with MetS plus diabetes mellitus [OR: 2.38 (1.13-5.02, 95% CI), p=0.023]. After adjusting by multivariable, compared with reference group, most of combined elevated inflammatory or immunological biomarkers were significantly associated with diabetes mellitus or MetS with or without diabetes mellitus. Patients with established diabetes mellitus or MetS had different inflammatory or immunological cytokine profile (such as hs-CRP, IgE, chymase, tryptase), which indicated that there is an alteration in the function of the immune system in diabetes mellitus or MetS patient. But these results are requested to be further demonstrated for large sample population-based cohort study.

Increased Bone Mass in Female Mice Lacking Mast Cell Chymase

Here we addressed the potential impact of chymase, a mast-cell restricted protease, on mouse bone phenotype. We show that female mice lacking the chymase Mcpt4 acquired a persistent expansion of diaphyseal bone in comparison with wild type controls, reaching a 15% larger diaphyseal cross sectional area at 12 months of age. Mcpt4-/- mice also showed increased levels of a bone anabolic serum marker and higher periosteal bone formation rate. However, they were not protected from experimental osteoporosis, suggesting that chymase regulates normal bone homeostasis rather than the course of osteoporosis. Further, the absence of Mcpt4 resulted in age-dependent upregulation of numerous genes important for bone formation but no effects on osteoclast activity. In spite of the latter, Mcpt4-/- bones had increased cortical porosity and reduced endocortical mineralization. Mast cells were found periosteally and, notably, bone-proximal mast cells in Mcpt4-/- mice were degranulated to a larger extent than in wild type mice. Hence, chymase regulates degranulation of bone mast cells, which could affect the release of mast cell-derived factors influencing bone remodelling. Together, these findings reveal a functional impact of mast cell chymase on bone. Further studies exploring the possibility of using chymase inhibitors as a strategy to increase bone volume may be warranted.

Biomarkers of the involvement of mast cells, basophils and eosinophils in asthma and allergic diseases

Biomarkers of disease activity have come into wide use in the study of mechanisms of human disease and in clinical medicine to both diagnose and predict disease course; as well as to monitor response to therapeutic intervention. Here we review biomarkers of the involvement of mast cells, basophils, and eosinophils in human allergic inflammation. Included are surface markers of cell activation as well as specific products of these inflammatory cells that implicate specific cell types in the inflammatory process and are of possible value in clinical research as well as within decisions made in the practice of allergy-immunology.

Often seen, rarely recognized: mast cell activation disease--a guide to diagnosis and therapeutic options

Mast cell (MC) disease has long been thought to be just the rare disease of mastocytosis (in various forms, principally cutaneous and systemic), with aberrant MC mediator release at symptomatic levels due to neoplastic MC proliferation. Recent discoveries now show a new view is in order, with mastocytosis capping a metaphorical iceberg now called "MC activation disease" (MCAD, i.e. disease principally manifesting inappropriate MC activation), with the bulk of the iceberg being the recently recognized "MC activation syndrome" (MCAS), featuring inappropriate MC activation to symptomatic levels with little to no inappropriate MC proliferation. Given increasing appreciation of a great menagerie of mutations in MC regulatory elements in mastocytosis and MCAS, the great heterogeneity of MCAD's clinical presentation is unsurprising. Most MCAD patients present with decades of chronic multisystem polymorbidity generally of an inflammatory ± allergic theme. Preliminary epidemiologic investigation suggests MCAD, while often misrecognized, may be substantially prevalent, making it increasingly important that practitioners of all stripes learn how to recognize its more common forms such as MCAS. We review the diagnostically challenging presentation of MCAD (with an emphasis on MCAS) and current thoughts regarding its biology, epidemiology, natural history, diagnostic evaluation, and treatment.

Serum tryptase detected during acute coronary syndrome is significantly related to the development of major adverse cardiovascular events after 2 years

BACKGROUND

One of the greatest challenges in cardiovascular medicine is to define the best tools for performing an accurate risk stratification for the recurrence of ischemic events in acute coronary syndrome (ACS) patients.

METHODS

We followed 65 ACS patients enrolled in a previous pilot study for 2 years after being discharged, focusing on the occurrence of major adverse cardiovascular events (MACE). The relationship between serum tryptase levels on admission, SYNergy between percutaneous coronary intervention with the TAXUS drug-eluting stent and the cardiac surgery score (SX-score), cardiovascular complexity and MACE at 2 years follow-up were analyzed.

RESULTS

The ACS population was divided in two groups: patients with MACE (n = 23) and patients without MACE (n = 42). The tryptase measurement at admission (T0) and at discharge (T3) and SX-score were higher in patients who experienced MACE than in those without (p = 0.0001, p < 0.0001 and p = 0.006, respectively). Conversely, we found no significant association between MACE and C-reactive protein (CRP), and between MACE and maximum level of high-sensitivity troponin (hs-Tn) values. Among all patients with MACE, 96% belonged to the group that presented with cardiovascular complexity at the beginning of ACS index admission (p < 0.0001). The predictive accuracy of serum tryptase for MACE at follow up set at the cut-off point of 4.95 ng/ml at T0 and of 5.2 ng/ml at T3. Interestingly, patients with both the above cut-off tryptase values at T0 and at T3 presented a 1320% increase in the odds of developing MACE (p < 0.0001).

CONCLUSION

In ACS patients, serum tryptase measured during index admission is significantly correlated to the development of MACE up to 2 years, demonstrating a possible long-term prognostic role of this biomarker.

The renin-angiotensin system: a possible contributor to migraine pathogenesis and prophylaxis

The presence of a tissue-based renin-angiotensin system, independent of the systemic one, has been identified in several organs including the brain. Experimental models have suggested the involvement of the renin-angiotensin system in neurogenic inflammation, susceptibility to oxidative stress, endothelial dysfunction, and neuromodulation of nociceptive transmission, thus potentially contributing to the pathogenesis of migraine. Genetic factors that increase susceptibility to migraine may include angiotensin-converting enzyme polymorphism, although available data are controversial. Clinical studies have suggested that angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may be effective in migraine prophylaxis. However, further research should clarify whether the postulated preventive effect is attributable to a pharmacological action over and above the antihypertensive effect and should test their tolerability in subjects with normal blood pressure values. In patients with contraindications or not responding to conventional prophylactic drugs and in patients with comorbid arterial hypertension, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may be used for migraine prophylaxis.

Measurement of β-tryptase in postmortem serum, pericardial fluid, urine and vitreous humor in the forensic setting

In the realm of forensic pathology, β-tryptase measurement for diagnostic purposes is performed in postmortem serum obtained from femoral blood. This may be partially or completely unavailable in some specific cases, such as infant autopsies and severely damaged bodies. The aim of this study was to investigate the usefulness of determining β-tryptase levels for diagnostic purposes in alternative biological samples. Urine, vitreous humor and pericardial fluid were selected and measured in 94 subjects including: fatal anaphylaxis following contrast material administration (6 cases), hypothermia (10 cases), diabetic ketoacidosis (10 cases), gunshot suicide (10 cases), heroin injection-related deaths (18 cases), trauma (10 cases), sudden death with minimal coronary atherosclerosis (10 cases), severe coronary atherosclerosis without myocardial infarction (10 cases) and severe coronary atherosclerosis with myocardial infarction (10 cases). Postmortem serum and pericardial fluid β-tryptase levels higher than the clinical reference value (11.4ng/ml) were systematically identified in fatal anaphylaxis following contrast material administration and 6 cases unrelated to anaphylaxis. β-tryptase concentrations in urine and vitreous humor were lower than the clinical reference value in all cases included in this study. Determination of β-tryptase in pericardial fluid appears to be a possible alternative to postmortem serum in the early postmortem period when femoral blood cannot be collected during autopsy and biochemical investigations are required to objectify increased β-tryptase levels.

Generation of a new congenic mouse strain with enhanced chymase expression in mast cells

Mast cells are effector cells best known for their roles in IgE-associated allergy, but they also play a protective role in defense against pathogens. These cells express high levels of proteases including chymase, tryptase and carboxypeptidase. In the present study, we identified a congenic strain of C57BL/6 mice expressing an extraordinarily high level of chymases Mcp-2 and Mcp-4 in mast cells. The overexpression was associated with variant Mcp-2 and Mcp-4 genes originated from DBA/2 mice that also expressed high levels of the two enzymes. Real time PCR analysis revealed that Mcp-2 and Mcp-4 were selectively overexpressed as tryptases, Cpa3 and several other chymases were kept at normal levels. Reporter gene assays demonstrated that single-nucleotide polymorphisms (SNPs) in the promoter region of Mcp-2 gene may be partly responsible for the increased gene transcription. Our study provides a new model system to study the function of mast cell chymases. The data also suggest that expression of chymases differs considerably in different strains of mice and the increased chymase activity may be responsible for some unique phenotypes observed in DBA/2 mice.

Pharmaceutical stabilization of mast cells attenuates experimental atherogenesis in low-density lipoprotein receptor-deficient mice

Mast cells (MCs) contribute to atherogenesis by releasing pro-inflammatory mediators to activate vascular cells and other inflammatory cells. This study examined whether MC activation or stabilization affects diet-induced atherosclerosis in low-density lipoprotein receptor-deficient (Ldlr(-/-)) mice. When Ldlr(-/-) mice consumed an atherogenic diet for 3 or 6 months, MC activation with compound 48/80 (C48/80) increased aortic arch intima and total lesion areas, and plasma total cholesterol, LDL, and triglyceride levels, whereas MC stabilization with cromolyn reduced these parameters. There were significant differences in arch intima and total lesion areas, and plasma total cholesterol, LDL, and triglyceride levels between C48/80-treated and cromolyn-treated mice. To examine a therapeutic application of cromolyn in atherosclerosis, we fed Ldlr(-/-) mice an atherogenic diet for 3 months followed by giving mice cromolyn for additional 3 months. Cromolyn did not affect aortic arch intima area, but significantly reduced lipid deposition in the thoracic-abdominal aortas. In aortic arches, however, cromolyn treatment significantly reduced lesion contents of Mac-3(+) macrophages, CD4(+) T cells, activated MCs, and lesion cell proliferation. While plasma total cholesterol and LDL levels increased and high-density lipoprotein (HDL) levels decreased from 3 months to 6 months of an atherogenic diet, cromolyn treatment decreased significantly plasma total cholesterol, LDL, and triglyceride levels and increased HDL levels above those of 3-month time point. These observations demonstrate that MC stabilization reduces lesion inflammation, ameliorates plasma lipid profiles, and may serve as a potential therapy for this cardiovascular disease.