Mast cells in human health and disease

Diagnostic and prognostic significance of mast cell markers in HIV/AIDS: Current insights and future directions

Human immunodeficiency virus (HIV) infection continues to pose significant global health challenges, necessitating advancements in diagnostic and prognostic approaches to optimize disease management. While primarily recognized for their roles in allergic responses, mast cells have emerged as potential markers with diagnostic and prognostic significance in the context of HIV/AIDS. This paper aims to synthesize current insights and delineate future directions regarding the utility of mast cell markers in diagnosing HIV infection, predicting disease progression, and guiding therapeutic strategies. Mast cells, equipped with distinct markers such as tryptase, chymase, carboxypeptidase A3, and c-kit/CD117 receptors, exhibit tissue-specific expression patterns that offer potential as diagnostic indicators for HIV infection. Understanding the dynamics of these markers in different tissues and body fluids holds promise for accurate HIV diagnosis, disease staging, and monitoring treatment responses. Moreover, the prognostic significance of mast cell markers in HIV/AIDS lies in their potential to predict disease progression, immune dysregulation, and clinical outcomes. The integration of mast cell markers into clinical applications offers promising avenues for refining diagnostic assays, patient monitoring protocols, and therapeutic strategies in HIV/AIDS. Future research directions involve the development of novel diagnostic tools and targeted therapies based on mast cell-specific markers, potentially revolutionizing clinical practice and enhancing patient care in the management of HIV/AIDS. Continued investigations into mast cell markers' diagnostic and prognostic implications hold immense potential to advance our understanding and improve outcomes in HIV/AIDS management.

NET-related gene signature for predicting AML prognosis

Acute Myeloid Leukemia (AML) is a malignant blood cancer with a high mortality rate. Neutrophil extracellular traps (NETs) influence various tumor outcomes. However, NET-related genes (NRGs) in AML had not yet received much attention. This study focuses on the role of NRGs in AML and their interaction with the immunological microenvironment. The gene expression and clinical data of patients with AML were downloaded from the TCGA-LAML and GEO cohorts. We identified 148 NRGs through the published article. Univariate Cox regression was used to analyze the association of NRGs with overall survival (OS). The least absolute shrinkage and selection operator were utilized to assess the predictive efficacy of NRGs. Kaplan-Meier plots visualized survival estimates. ROC curves assessed the prognostic value of NRG-based features. A nomogram, integrating clinical information and prognostic scores of patients, was constructed using multivariate logistic regression and Cox proportional hazards regression models. Twenty-seven NRGs were found to significantly impact patient OS. Six NRGs-CFTR, ENO1, PARVB, DDIT4, MPO, LDLR-were notable for their strong predictive ability regarding patient survival. The ROC values for 1-, 3-, and 5-year survival rates were 0.794, 0.781, and 0.911, respectively. In the training set (TCGA-LAML), patients in the high NRG risk group showed a poorer prognosis (p < 0.001), which was validated in two external datasets (GSE71014 and GSE106291). The 6-NRG signature and corresponding nomograms exhibit superior predictive accuracy, offering insights for pre-immune response evaluation and guiding future immuno-oncology treatments and drug selection for AML patients.

Dopamine, Immunity, and Disease

The neurotransmitter dopamine is a key factor in central nervous system (CNS) function, regulating many processes including reward, movement, and cognition. Dopamine also regulates critical functions in peripheral organs, such as blood pressure, renal activity, and intestinal motility. Beyond these functions, a growing body of evidence indicates that dopamine is an important immunoregulatory factor. Most types of immune cells express dopamine receptors and other dopaminergic proteins, and many immune cells take up, produce, store, and/or release dopamine, suggesting that dopaminergic immunomodulation is important for immune function. Targeting these pathways could be a promising avenue for the treatment of inflammation and disease, but despite increasing research in this area, data on the specific effects of dopamine on many immune cells and disease processes remain inconsistent and poorly understood. Therefore, this review integrates the current knowledge of the role of dopamine in immune cell function and inflammatory signaling across systems. We also discuss the current understanding of dopaminergic regulation of immune signaling in the CNS and peripheral tissues, highlighting the role of dopaminergic immunomodulation in diseases such as Parkinson's disease, several neuropsychiatric conditions, neurologic human immunodeficiency virus, inflammatory bowel disease, rheumatoid arthritis, and others. Careful consideration is given to the influence of experimental design on results, and we note a number of areas in need of further research. Overall, this review integrates our knowledge of dopaminergic immunology at the cellular, tissue, and disease level and prompts the development of therapeutics and strategies targeted toward ameliorating disease through dopaminergic regulation of immunity. SIGNIFICANCE STATEMENT: Canonically, dopamine is recognized as a neurotransmitter involved in the regulation of movement, cognition, and reward. However, dopamine also acts as an immune modulator in the central nervous system and periphery. This review comprehensively assesses the current knowledge of dopaminergic immunomodulation and the role of dopamine in disease pathogenesis at the cellular and tissue level. This will provide broad access to this information across fields, identify areas in need of further investigation, and drive the development of dopaminergic therapeutic strategies.

Morphometric Analysis of Mast Cells in Tumor Predicts Recurrence of Hepatocellular Carcinoma After Liver Transplantation

Tumor-infiltrating immune cells are relevant prognostic and immunotherapeutic targets in hepatocellular carcinoma (HCC). Mast cells play a key role in allergic response but may also be involved in anticancer immunity. Digital morphometric analysis of patient tissue sections has become increasingly available for clinical routine and provides unbiased quantitative data. Here, we apply morphometric analysis of mast cells to retrospectively evaluate their relevance for HCC recurrence in patients after orthotopic liver transplantation (OLT). A total of 173 patients underwent OLT for HCC at the Medical University of Vienna (21 women, 152 men; 55.2 ± 7.9 years; 74 beyond Milan criteria, 49 beyond up-to-7 criteria for liver transplantation). Tissue arrays from tumors and corresponding surrounding tissues were immunohistochemically stained for mast cell tryptase. Mast cells were quantified by digital tissue morphometric analysis and correlated with HCC recurrence. Mast cells were detected in 93% of HCC tumors and in all available surrounding liver tissues. Tumor tissues revealed lower mast cell density than corresponding surrounding tissues (P < 0.0001). Patients lacking intratumoral mast cells (iMCs) displayed larger tumors and higher tumor recurrence rates both in the whole cohort (hazard ratio [HR], 2.74; 95% confidence interval [CI], 1.09-6.93; P = 0.029) and in patients beyond transplant criteria (Milan HR, 2.81; 95% CI, 1.04-7.62; P = 0.01; up-to-7 HR, 3.58; 95% CI, 1.17-10.92; P = 0.02). Notably, high iMC identified additional patients at low risk classified outside the Milan and up-to-7 criteria, whereas low iMC identified additional patients at high risk classified within the alpha-fetoprotein French and Metroticket criteria. iMCs independently predicted tumor recurrence in a multivariate Cox regression analysis (Milan HR, 2.38; 95% CI, 1.16-4.91; P = 0.019; up-to-7 HR, 2.21; 95% CI, 1.05-4.62; P = 0.035). Conclusion: Hepatic mast cells might be implicated in antitumor immunity in HCC. Morphometric analysis of iMCs refines prognosis of HCC recurrence after liver transplantation.

Mast Cells as a Double Edged Sword in Immunity: Disorders of Mast Cell Activation and Therapeutic Management. Second of Two Parts

Mast cells (MCs) bear many receptors that allow them to respond to a variety of exogenous and endogenous stimuli. However, MC function is dual since they can initiate pathological events or protect the host against infectious challenges. The role of MCs in disease will be analyzed in a broad sense, describing cellular and molecular mechanisms related to their involvement in auto-inflammatory diseases, asthma, autoimmune diseases and cancer. On the other hand, their protective role in the course of bacterial, fungal and parasitic infections will also be illustrated. As far as treatment of MC-derived diseases is concerned, allergen immunotherapy as well as other attempts to reduce MC-activation will be outlined according to the recent data. Finally, in agreement with current literature and our own data polyphenols have been demonstrated to attenuate type I allergic reactions and contact dermatitis in response to nickel. The use of polyphenols in these diseases will be discussed also in view of MC involvement.

Antibiotic Treatment in an Animal Model of Inflammatory Lung Disease

Allergic disease is on the rise and yet the underlying cause and risk factors are not fully understood. While lifesaving in many circumstances, the use of antibiotics and the subsequent disruption of the microbiome are positively correlated with the development of allergies. Here, we describe the use of the antibiotic vancomycin in combination with the papain-induced mouse model of allergic disease that allows for the assessment of microbiome perturbations and the impact on allergy development.

Butyrate Shapes Immune Cell Fate and Function in Allergic Asthma

The microbiome plays a fundamental role in how the immune system develops and how inflammatory responses are shaped and regulated. The “gut-lung axis” is a relatively new term that highlights a crucial biological crosstalk between the intestinal microbiome and lung. A growing body of literature suggests that dysbiosis, perturbation of the gut microbiome, is a driving force behind the development, and severity of allergic asthma. Animal models have given researchers new insights into how gut microbe-derived components and metabolites, such as short-chain fatty acids (SCFAs), influence the development of asthma. While the full understanding of how SCFAs influence allergic airway disease remains obscure, a recurring theme of epigenetic regulation of gene expression in several immune cell compartments is emerging. This review will address our current understanding of how SCFAs, and specifically butyrate, orchestrates cell behavior, and epigenetic changes and will provide a detailed overview of the effects of these modifications on immune cells in the context of allergic airway disease.

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.

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.

Leptin receptor is expressed by tissue mast cells

Leptin, the adipose tissue-derived product of the obese (ob) gene, is known to function as the hormone of energy expenditure. It has also been established that leptin regulates immune and inflammatory processes. All leptin-induced biological activities depend on binding to the membrane-spanning leptin receptor (Ob-R), belonging to the class I cytokine receptor family. The available data relating to the Ob-R on mature mast cells (MCs), and consequently leptin significance in the modulation of MC activity within the tissue, are limited. Immunohistochemistry was used to establish Ob-R expression by MCs in the mesenteric adipose tissue. Flow cytometry and confocal microscopy were used to evaluate both constitutive and leptin-induced expression of Ob-R on freshly isolated peritoneal MCs. MCs in the mesenteric adipose tissue and native peritoneal MCs express Ob-R constitutively. Additionally, leptin influences its receptor expression on these cells. Leptin at lower concentrations caused Ob-R expression increase both at the cell surface and in the cell interior. MC stimulation with higher concentrations of leptin results in a decline of Ob-R from the cell surface and significant enhancement of this receptor not only in the nuclear region but also in the endoplasmic reticulum. In conclusion, one can be assumed that leptin regulates MC activity within tissues. These findings might provide an additional link among the leptin, innate immune function, and inflammatory processes and diseases.

Preclinical human models and emerging therapeutics for advanced systemic mastocytosis

Mastocytosis is a term used to denote a group of rare diseases characterized by an abnormal accumulation of neoplastic mast cells in various tissues and organs. In most patients with systemic mastocytosis, the neoplastic cells carry activating mutations in KIT Progress in mastocytosis research has long been hindered by the lack of suitable in vitro models, such as permanent human mast cell lines. In fact, only a few human mast cell lines are available to date: HMC-1, LAD1/2, LUVA, ROSA and MCPV-1. The HMC-1 and LAD1/2 cell lines were derived from patients with mast cell leukemia. By contrast, the more recently established LUVA, ROSA and MCPV-1 cell lines were derived from CD34⁺ cells of non-mastocytosis donors. While some of these cell lines (LAD1/2, LUVA, ROSA^{KIT WT} and MCPV-1) do not harbor KIT mutations, HMC-1 and ROSA^{KIT D816V} cells exhibit activating KIT mutations found in mastocytosis and have thus been used to study disease pathogenesis. In addition, these cell lines are increasingly employed to validate new therapeutic targets and to screen for effects of new targeted drugs. Recently, the ROSA^{KIT D816V} subclone has been successfully used to generate a unique in vivo model of advanced mastocytosis by injection into immunocompromised mice. Such a model may allow in vivo validation of data obtained in vitro with targeted drugs directed against mastocytosis. In this review, we discuss the major characteristics of all available human mast cell lines, with particular emphasis on the use of HMC-1 and ROSA^{KIT D816V} cells in preclinical therapeutic research in mastocytosis.

Mast Cell Proteases Activate Astrocytes and Glia-Neurons and Release Interleukin-33 by Activating p38 and ERK1/2 MAPKs and NF-κB

Inflammatory mediators released from activated microglia, astrocytes, neurons, and mast cells mediate neuroinflammation. Parkinson's disease (PD) is characterized by inflammation-dependent dopaminergic neurodegeneration in substantia nigra. 1-Methyl-4-phenylpyridinium (MPP⁺), a metabolite of parkinsonian neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), induces inflammatory mediators' release from brain cells and mast cells. Brain cells' interaction with mast cells is implicated in neuroinflammation. However, the exact mechanisms involved are not yet clearly understood. Mouse fetal brain-derived cultured primary astrocytes and glia-neurons were incubated with mouse mast cell protease-6 (MMCP-6) and MMCP-7, and mouse bone marrow-derived mast cells (BMMCs) were incubated with MPP⁺ and brain protein glia maturation factor (GMF). Interleukin-33 (IL-33) released from these cells was quantitated by enzyme-linked immunosorbent assay. Both MMCP-6 and MMCP-7 induced IL-33 release from astrocytes and glia-neurons. MPP⁺ and GMF were used as a positive control-induced IL-33 and reactive oxygen species expression in mast cells. Mast cell proteases and MPP⁺ activate p38 and extracellular signal-regulated kinases 1/2 (ERK1/2), mitogen-activated protein kinases (MAPKs), and transcription factor nuclear factor-kappa B (NF-κB) in astrocytes, glia-neurons, or mast cells. Addition of BMMCs from wt mice and transduction with adeno-GMF show higher chemokine (C-C motif) ligand 2 (CCL2) release. MPP⁺ activated glial cells and reduced microtubule-associated protein 2 (MAP-2) expression indicating neurodegeneration. IL-33 expression increased in the midbrain and striatum of PD brains as compared with age- and sex-matched control subjects. Glial cells and neurons interact with mast cells and accelerate neuroinflammation and these interactions can be explored as a new therapeutic target to treat PD.

Microbiome-driven allergic lung inflammation is ameliorated by short-chain fatty acids

The mammalian gastrointestinal tract harbors a microbial community with metabolic activity critical for host health, including metabolites that can modulate effector functions of immune cells. Mice treated with vancomycin have an altered microbiome and metabolite profile, exhibit exacerbated T helper type 2 cell (Th2) responses, and are more susceptible to allergic lung inflammation. Here we show that dietary supplementation with short-chain fatty acids (SCFAs) ameliorates this enhanced asthma susceptibility by modulating the activity of T cells and dendritic cells (DCs). Dysbiotic mice treated with SCFAs have fewer interleukin-4 (IL4)-producing CD4⁺ T cells and decreased levels of circulating immunoglobulin E (IgE). In addition, DCs exposed to SCFAs activate T cells less robustly, are less motile in response to CCL19 in vitro, and exhibit a dampened ability to transport inhaled allergens to lung draining nodes. Our data thus demonstrate that gut dysbiosis can exacerbate allergic lung inflammation through both T cell- and DC-dependent mechanisms that are inhibited by SCFAs.

Mast cell activation disease and the modern epidemic of chronic inflammatory disease

A large and growing portion of the human population, especially in developed countries, suffers 1 or more chronic, often quite burdensome ailments which either are overtly inflammatory in nature or are suspected to be of inflammatory origin, but for which investigations to date have failed to identify specific causes, let alone unifying mechanisms underlying the multiple such ailments that often afflict such patients. Relatively recently described as a non-neoplastic cousin of the rare hematologic disease mastocytosis, mast cell (MC) activation syndrome-suspected to be of greatly heterogeneous, complex acquired clonality in many cases-is a potential underlying/unifying explanation for a diverse assortment of inflammatory ailments. A brief review of MC biology and how aberrant primary MC activation might lead to such a vast range of illness is presented.

Cardiovascular symptoms in patients with systemic mast cell activation disease

Traditionally, mast cell activation disease (MCAD) has been considered as just one rare (neoplastic) disease, mastocytosis, focused on the mast cell (MC) mediators tryptase and histamine and the suggestive, blatant symptoms of flushing and anaphylaxis. Recently another form of MCAD, the MC activation syndrome, has been recognized featuring inappropriate MC activation with little to no neoplasia and likely much more heterogeneously clonal and far more prevalent than mastocytosis. Increasing expertise and appreciation has been established for the truly very large menagerie of MC mediators and their complex patterns of release, engendering complex, nebulous presentations of chronic and acute illness best characterized as multisystem polymorbidity of generally inflammatory ± allergic theme. We describe the pathogenesis of MCAD with a particular focus on clinical cardiovascular symptoms and the therapeutic options for MC mediator-induced cardiovascular symptoms.

Role of capsaicin-sensitive nerves and tachykinins in mast cell tryptase-induced inflammation of murine knees

OBJECTIVE, DESIGN

Mast cell tryptase (MCT) is elevated in arthritic joints, but its direct effects are not known. Here, we investigated MCT-evoked acute inflammatory and nociceptive mechanisms with behavioural, in vivo imaging and immunological techniques.

MATERIAL AND SUBJECTS

Neurogenic inflammation involving capsaicin-sensitive afferents, transient receptor potential vanilloid 1 receptor (TRPV1), substance P (SP), neurokinin A (NKA) and their NK1 tachykinin receptor were studied using gene-deleted mice compared to C57Bl/6 wildtypes (n = 5-8/group).

TREATMENT

MCT was administered intraarticularly or topically (20 μl, 12 μg/ml). Capsaicin-sensitive afferents were defunctionalized with the TRPV1 agonist resiniferatoxin (RTX; 30-70-100 μg/kg s.c. pretreatment).

METHODS

Knee diameter was measured with a caliper, synovial perfusion with laser Doppler imaging, mechanonociception with aesthesiometry and weight distribution with incapacitance tester over 6 h. Cytokines and neuropeptides were determined with immunoassays.

RESULTS

MCT induced synovial vasodilatation, oedema, impaired weight distribution and mechanical hyperalgesia, but cytokine or neuropeptide levels were not altered at the 6-h timepoint. Hyperaemia was reduced in RTX-treated and TRPV1-deleted animals, and oedema was absent in NK1-deficient mice. Hyperalgesia was decreased in SP/NKA- and NK1-deficient mice, weight bearing impairment in RTX-pretreated, TRPV1- and NK1-deficient animals.

CONCLUSIONS

MCT evokes synovial hyperaemia, oedema, hyperalgesia and spontaneous pain. Capsaicin-sensitive afferents and TRPV1 receptors are essential for vasodilatation, while tachykinins mediate oedema and pain.

Malignant transformation of oral submucous fibrosis: overview of histopathological aspects

Oral submucous fibrosis (OSF), first described in 1952, is a potentially malignant disorder associated with betel quid and areca nut chewing, mostly prevalent in the population of the Indian subcontinent and South East Asia. Malignant transformation of OSF to squamous cell carcinoma (SCC) has been estimated to be between 2% and 8%. Our study aimed to review the histopathologic changes that contribute to the understanding of the malignant transformation of OSF. Changes in epithelial thickness and dysplasia characterized by micronuclei, altered AgNOR counts and distribution, keratin protein alteration, and alteration of P63 and E-cadherin characterize the epithelial changes during the transformation of OSF to SCC. Common mechanisms have been proposed to be involved in OSF and SCC, through collagen maturation and their interaction with myofibroblasts and mast cells. Fibrosis-driven vascular constriction that results in epithelial hypoxia has also been proposed as an important mechanism for the malignant transformation of OSF. However, reassessment of the classical view is required, because with demonstration of large blood vasculature in the connective tissue stroma of OSF, the hypothesis associated with tissue hypoxia-induced malignant transformation of OSF can be questioned.

Inhibition of MDM2 expression by rosmarinic acid in TSLP-stimulated mast cell

Rosmarinic acid (RA) has an anti-inflammatory property while thymic stromal lymphopoietin (TSLP) has an important role in mast cell-mediated inflammatory responses. Thus, the aim of this study was to determine the regulatory effect of RA in TSLP-stimulated human mast cell line, HMC-1 cells, and short ragweed pollen-induced allergic conjunctivitis mouse model. As a result, we found that RA significantly decreased the TSLP-induced mast cell proliferation and murine double minute (MDM) 2 expression. RA significantly decreased the levels of interleukin (IL)-13 and phosphorylated the signal transducer and activation of transcription 6 in the TSLP-stimulated HMC-1 cells. RA induced the increment of p53 levels, caspase-3 activation, and poly-ADP-ribose polymerase cleavage and the reduction of the procaspase-3 and Bcl2. RA significantly reduced the production of tumor necrosis factor-α, IL-1β, and IL-6 on the TSLP-stimulated HMC-1 cells. In addition, RA significantly reduced the levels of IgE, IL-4, and TSLP in the short ragweed pollen-induced allergic conjunctivitis mouse model. In conclusion, the results of the study suggest that RA has a significant anti-inflammatory effect on TSLP-induced inflammatory reactions. These effects of RA are likely to be mediated through inhibiting the MDM2 increased by TSLP.

Update on macrophages and innate immunity in scleroderma

PURPOSE OF REVIEW

In this review of the literature from 2014 through mid-2015, we examine new data that shed light on how macrophages and other innate immune cells and signals contribute to inflammation, vascular dysfunction, and fibrosis in scleroderma.

RECENT FINDINGS

Recent human studies have focused on changes early in scleroderma, and linked macrophages to inflammation in skin and progression of lung disease. Plasmacytoid dendritic cells have been implicated in vascular dysfunction. In mice, several factors have been identified that influence macrophage activation and experimental fibrosis. However, emerging data also suggest that myeloid cells can have differential effects in fibrosis. Sustained signaling through different toll-like receptors can lead to inflammation or fibrosis, and these signals can influence both immune and nonimmune cells.

SUMMARY

There are many types of innate immune cells that can potentially contribute to scleroderma and will be worth exploring in detail. Experimentally dissecting the roles of macrophages based on ontogeny and activation state, and the innate signaling pathways in the tissue microenvironment, may also lead to better understanding of scleroderma pathogenesis.

Nonclinical evaluation of the potential for mast cell activation by an erythropoietin analog

The erythropoietin analog peginesatide was withdrawn from marketing due to unexpected severe anaphylactic reactions associated with administration of the multi-use formulation. The adverse events occurred rapidly following the first ever administration of the drug with most affected patients becoming symptomatic in less than 30min. This is most consistent with an anaphylactoid reaction due to direct activation of mast cells. Laboratory evaluation was undertaken using rat peritoneal mast cells as the model system. Initial studies showed that high concentrations of the formulated drug as well as formulated vehicle alone could cause mast cell degranulation as measured by histamine release. The purified active drug was not able to cause histamine release whereas the vehicle filtrate and lab created drug vehicle were equally potent at causing histamine release. Individual formulations of vehicle leaving one component out showed that histamine release was due to phenol. Dose response studies with phenol showed a very sharp dose response curve that was similar in three buffer systems. Cellular analysis by flow cytometry showed that the histamine release was not due to cell death, and that changes in light scatter parameters consistent with degranulation were rapidly observed. Limited testing with primary human mast cells showed a similar dose response of histamine release with exposure to phenol. To provide in vivo confirmation, rats were injected with vehicle formulated with various concentrations of phenol via a jugular vein cannula. Significant release of histamine was detected in blood samples taken 2min after dosing at the highest concentrations tested.

Masitinib for the treatment of mild to moderate Alzheimer's disease

Alzheimer's disease (AD) is a degenerative neurological disorder that is the most common cause of dementia and disability in older patients. Available treatments are symptomatic in nature and are only sufficient to improve the quality of life of AD patients temporarily. A potential strategy, currently under investigation, is to target cell-signaling pathways associated with neurodegeneration, in order to decrease neuroinflammation, excitotoxicity, and to improve cognitive functions. Current review centers on the role of neuroinflammation and the specific contribution of mast cells to AD pathophysiology. The authors look at masitinib therapy and the evidence presented through preclinical and clinical trials. Dual actions of masitinib as an inhibitor of mast cell-glia axis and a Fyn kinase blocker are discussed in the context of AD pathology. Masitinib is in Phase III clinical trials for the treatment of malignant melanoma, mastocytosis, multiple myeloma, gastrointestinal cancer and pancreatic cancer. It is also in Phase II/III clinical trials for the treatment of multiple sclerosis, rheumatoid arthritis and AD. Additional research is warranted to better investigate the potential effects of masitinib in combination with other drugs employed in AD treatment.