Involvement Of Mast Cells Research Articles

Critical Role of Protease-activated Receptor 2 Activation by Mast Cell Tryptase in the Development of Postoperative Pain

Studies have indicated that nearly half of all surgical patients still have inadequate pain relief. Thus, it is crucial to understand the mechanisms involved in postoperative pain in order to better treat it. Thus, the aim of this study was to investigate the involvement of mast cell degranulation, tryptase and its substrate, the protease-activated receptor 2, in a model of postoperative pain in mice. We evaluated the effect of the compound 48/80 (to cause mast cell mediator depletion), cromoglycate or ketotifen (mast cell stabilizers), gabexate (tryptase inhibitor) or N3-methylbutyryl-N-6-aminohexanoyl-piperazine (protease-activated receptor 2 antagonist) in a postoperative pain model in mice (n = 5-10). Mast cell degranulation and tryptase activity were also evaluated in the operated tissue (n= 5-8). The pre-treatment with compound 48/80 or ketotifen was able to prevent nociception throughout the postoperative hyperalgesia course (until 5 days after surgery), whereas cromoglycate presented a shorter effect (until 1 day). Gabexate or N3-methylbutyryl-N-6-aminohexanoyl-piperazine also produced a short-lasting effect in preventing postoperative nociception. However, neither gabexate, N3-methylbutyryl-N-6-aminohexanoyl-piperazine nor cromoglycate was capable of reversing nociception when administered after incision. Surgery led to early mast cell degranulation on the incised tissue and increased tryptase activity in tissue perfusates. Cromoglycate fully prevented the tryptase release in the perfusate and the compound 48/80 substantially reduced tryptase activity in the incised tissue. Thus, the mast cell degranulation with the subsequent release of tryptase and protease-activated receptor 2 activation are potential targets for the development of novel therapies to prevent, but not reverse, postoperative pain.

Mast cells and the cyclooxygenase pathway mediate colonic afferent nerve sensitization in a murine colitis model

Intestinal inflammation alters colonic afferent nerve sensitivity which may contribute to patients' perception of abdominal discomfort. We aimed to explore whether mast cells and the cyclooxygenase pathway are involved in altered afferent nerve sensitivity during colitis. C57Bl6 mice received 3% dextran-sulfate sodium (DSS) in drinking water for 7 days to induce colitis. Control animals received regular water. On day 8 inflammation was assessed in the proximal colon by morphology and histology. Extracellular afferent nerve discharge was recorded from the mesenteric nerve of a 2 cm colonic segment. Subgroups were treated in vitro with the mast cell stabilizer doxantrazole (10⁻⁴M) or the cyclooxygenase inhibitor naproxen (10⁻⁵M). DSS colitis resulted in morphological and histological signs of inflammation. At baseline, peak firing was 11±2 imp s⁻¹ in colitis segments and 5±1 imp s⁻¹ in uninflamed control segments (p<0.05; mean ± SEM; each n=6). In colitis segments, afferent nerve discharge to bradykinin (0.5 μM) was increased to 47±7 compared to 23±6 imp s⁻¹ in recordings from non-inflamed control tissue (p<0.05). Mechanosensitivity during luminal ramp distension (0-80 cm H₂O) was increased reaching 24±5 imp s⁻¹ at 80 cm H₂O during colitis compared to 14±2 in non-inflamed controls (p<0.05). Doxantrazole or naproxen reduced afferent discharge to bradykinin and luminal ramp distension in colitis segments to control levels. Intestinal inflammation sensitizes mesenteric afferent nerve fibers to bradykinin and mechanical stimuli. The underlying mechanism responsible for this sensitization seems to involve mast cells and prostaglandins.

Physiological Relevance of LL-37 Induced Bladder Inflammation and Mast Cells

We established the physiological relevance of LL-37 induced bladder inflammation. We hypothesized that 1) human urinary LL-37 is increased in pediatric patients with spina bifida, 2) LL-37 induced inflammation occurs in our mouse model via urothelial binding and is dose dependent and 3) LL-37 induced inflammation involves mast cells. To test our first hypothesis, we obtained urine samples from 56 pediatric patients with spina bifida and 22 normal patients. LL-37 was measured by enzyme-linked immunosorbent assay. Our second hypothesis was tested in C57Bl/6 mice challenged with 7 LL-37 concentrations intravesically for 1 hour. At 24 hours tissues were examined histologically and myeloperoxidase assay was done to quantitate inflammation. In separate experiments fluorescent LL-37 was instilled and tissues were obtained immediately (time = 0) and at 24hours (time = 24). To test our final hypothesis, we performed immunohistochemistry for mast cell tryptase and evaluated 5 high power fields per bladder to determine the mean number of mast cells per mm(2). Urinary LL-37 was 89-fold higher in patients with spina bifida. Mouse LL-37 dose escalation experiments revealed increased inflammation at higher LL-37 concentrations. Fluorescent LL-37 demonstrated global urothelial binding at time = 0 but was not visible at time = 24. Immunohistochemistry for tryptase revealed mast cell infiltration in all tissue layers. At higher concentrations the LL-37 challenge led to significantly greater mast cell infiltration. Urinary LL-37 was significantly increased in pediatric patients with spina bifida. To our knowledge we report for the first time that LL-37 can elicit profound, dose dependent bladder inflammation involving the urothelium. Finally, inflammation propagation involves mast cells.

Molecular signaling and targets from itch: lessons for cough

Itch is described as an unpleasant sensation that elicits the desire to scratch, which results in the removal of the irritant from the skin. The cough reflex also results from irritation, with the purpose of removing said irritant from the airway. Could cough then be similar to itch? Anatomically, both pathways are mediated by small-diameter sensory fibers. These cough and itch sensory fibers release neuropeptides upon activation, which leads to inflammation of the nerves. Both cough and itch also involve mast cells and their mediators, which are released upon degranulation. This common inflammation and interaction with mast cells are involved in the development of chronic conditions of itch and cough. In this review, we examine the anatomy and molecular mechanisms of itch and compare them to known mechanisms for cough. Highlighting the common aspects of itch and cough could lead to new thoughts and perspectives in both fields.

CHANGES IN THE URINARY BLADDER MORPHOLOGY, MAST CELL POPULATION AND ESTROGEN RECEPTOR ALPHA EXPRESSION FOLLOWING OVARECTOMY AND CHRONIC ESTROGEN REPLACEMENT THERAPY IN ALBINO RATS

11 Acta Endocrinologica (Buc), vol. IX, no. 1, p. 11-22, 2013 *Correspondence to: Dr. Flaviu Alexandru Tabaran, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Department of Pathology, Manastur Street, Nr.3-5, Cluj-Napoca, Cluj, 400372, Romania, E-mail: flaviu_tabaran@yahoo.com Abstract Context. The inflammatory disorders of the urinary bladder represent one of the most frequent disorders associated with hormonal unbalances caused by menopause. The involvement of estrogens and mast cells in this complex mechanism mediated by neuro-hormonal pathway is well known, but the pathogenesis through which the hormonal deprivation is affecting the Estrogen Receptor expression and is predisposing to urinary bladder inflammatory changes is still argued. Objective. To determine the structural changes associated with surgically induced menopause, and the effect of estrogen replacement therapy (ERT) in the urinary bladder morphology, mast cell population and Estrogen Receptor (ERα) expression. Subjects and methods. The effect of ovariectomy and ERT was monitored by quantifying the number of mast cells and the structural changes that the urinary bladder suffers. By immunohistochemistry we assessed the changes of the Estrogen Receptor Alpha (ERα) expression in the urothelium and detrusor muscle. The study was carried out on ovariectomised female rats over a period of 42 days. Results. The main alterations associated with the hormonal deprivation were represented by the growth in number of the bladder mast cells, atrophy of the urothelium and amplification of the expression of ERα from the urothelium, but not from the detrusor muscle. ERT significantly decreased the tissue expression for ERα, reduced the severity of bladder atrophy and the number of mast cells. Conclusions. The estrogenic hormonal substitution can diminish the severity of the atrophic, inflammatory and ERα changes in bladder disorders associated with ovarectomy in rat.

Skin tags: a link between lesional mast cell count/tryptase expression and obesity and dyslipidemia.

Background:The etiology of skin tags (STs) is not fully understood. A relation to diabetes mellitus and obesity was suggested. Few studies of possible mast cells (MCs) involvement were reported. Tyrptase is a mast cell mediator and a potent fibroblast growth factor. It may provide a molecular link between mast cell activation and fibrosis.Aims:The aim was to assess clinical and laboratory findings in patients with STs, and the possible link between obesity, dyslipidemia, and lesional MC count/tryptase expression.Materials and Methods:A total of 20 patients with STs were subjected to clinical examination, estimation of body mass index (BMI), fasting blood glucose (FBG), postprandial blood glucose (PPBG), serum cholesterol and triglycerides, abdominal ultrasound for fatty liver assessment, in addition to study of MCs through staining for MC tryptase in two skin biopsies; lesional and nonlesional (control).Results:All patients showed abnormally high BMI and hypertriglyceridemia, with abnormal sonographic pattern in 15 patients (75%). STs number positively correlated with the age of patients. STs showed significantly higher MC counts and tryptase expression, compared with control skin (P < 0.001), with no correlation of the STs number or MC count with BMI, FBG, PPBG or serum cholesterol. Obese patients showed a significantly higher MC count than overweight and there was a positive correlation between MC count and serum triglycerides. Axilla and under breast STs showed a higher MC count compared with other sites.Conclusions:STs seem to be related to obesity and hypertriglyceridemia. MCs with their tryptase are possibly involved in pathogenesis of STs. MC count is related to the associated factors; obesity and serum triglycerides. MC tryptase expression is a reliable method for accurate tissue MC counting.

Prevalence of rhinitis symptoms among textile industry workers exposed to cotton dust.

Summary Introduction: The respiratory tract is one of the main points of entry of foreign substances into the body. Because of its location, the respiratory tract is heavily exposed to harmful agents, such as gases, vapors, or aerosols. Aim: Our objective was to evaluate the symptoms of occupational rhinitis in workers exposed to cotton dust. Method: The prospective study population consisted of workers from the “Nova Esperança” Cooperative of Nova Odessa (Sao Paulo), who were studied between September and December 2008. Data were collected through an individually and privately answered questionnaire designed by the author considering the clinical criteria for rhinitis. Results: Using the questionnaire, we evaluated a total of 124 workers. Among these patients, 63.7% complained of nasal obstruction, 57.2% of nasal itching, 46.7% of rhinorrhea, and 66.1% of sneezing. Of the patients considered to have very serious symptoms, 9% had nasal obstruction; 9%, itching; 4%, rhinorrhea; and 6.4%, sneezing. Discussion: Aerosol agents in the environment can clearly aggravate and even initiate rhinitis. From the standpoint of pathogenesis, the mechanisms of classical allergic airway inflammation involving mast cells, IgE, histamine, eosinophils, and lymphocytes may be responsible for the development of rhinitis after exposure to high molecular weight allergens such as proteins derived from animals and plants. This study showed a strong relationship between the occupational exposures associated with work in the cotton textile industry and the symptoms of rhinitis. Conclusion: Analysis of the data clearly showed the occurrence of rhinitis symptoms in these patients, demonstrating that the prevention and treatment of this condition in the workplace is extremely important.

Dermal mast cell density in fingers reflects severity of skin sclerosis in systemic sclerosis

Systemic sclerosis (SSc) is characterized by skin sclerosis, which develops from the distal extremities and spreads to the trunk. Although several reports have implied the involvement of mast cells in SSc based on examination of forearm skin specimens, there have been no studies that examined digital skin specimens. Skin biopsies were obtained from the distal one-third of the forearm and between distal and proximal interphalangeal joints from 46 SSc patients, as well as from 29 non-SSc patients and normal controls. Dermal mast cells were detected histologically using NanoZoomer digital pathology. Dermal mast cell density was significantly higher in both the forearms and fingers in SSc patients compared with non-SSc patients and normal controls. Digital dermal mast cell density was significantly higher in patients with diffuse cutaneous SSc than in local cutaneous SSc patients and also in the anti-topoisomerase I antibody-positive group than in the negative group, though such tendency was not noted in the forearm dermis. Interestingly, digital dermal mast cell density tended to correlate negatively but significantly with disease duration, suggesting the possible involvement of dermal mast cells in the early pathological process. Digital accumulation of toluidine blue- and/or c-Kit-positive dermal mast cells appears to be involved in the early stages of the pathological processes of SSc, especially in patients positive for anti-topoisomerase I antibody.

Mast cell–glia axis in neuroinflammation and therapeutic potential of the anandamide congener palmitoylethanolamide

Communication between the immune and nervous systems depends a great deal on pro-inflammatory cytokines. Both astroglia and microglia, in particular, constitute an important source of inflammatory mediators and may have fundamental roles in central nervous system (CNS) disorders from neuropathic pain and epilepsy to neurodegenerative diseases. Glial cells respond also to pro-inflammatory signals released from cells of immune origin. In this context, mast cells are of particular relevance. These immune-related cells, while resident in the CNS, are able to cross a compromised blood-spinal cord and blood-brain barrier in cases of CNS pathology. Emerging evidence suggests the possibility of mast cell-glia communication, and opens exciting new perspectives for designing therapies to target neuroinflammation by differentially modulating the activation of non-neuronal cells normally controlling neuronal sensitization-both peripherally and centrally. This review aims to provide an overview of recent progress relating to the pathobiology of neuroinflammation, the role of glia, neuro-immune interactions involving mast cells and the possibility that glia-mast cell interactions contribute to exacerbation of acute symptoms of chronic neurodegenerative disease and accelerated disease progression, as well as promotion of pain transmission pathways. Using this background as a starting point for discussion, we will consider the therapeutic potential of naturally occurring fatty acid ethanolamides, such as palmitoylethanolamide in treating systemic inflammation or blockade of signalling pathways from the periphery to the brain in such settings.

Alteration of cell responses to PrPSc in prolonged cell culture and its effect on transmission of PrPSc to neural cells

The mechanisms and processes of the uptake, intracellular trafficking and intercellular spread of PrP(Sc) and its transfer to neural cells are not clearly defined. The involvement of immune, intestinal, mast or peripheral neural cells in this process also remains unclear. The role of these cell types in the accumulation and transfer of PrP(Sc) to neural cells was investigated following short and prolonged exposure to the Chandler and Obihiro strains of scrapie PrP(Sc) for up to 28days. Eight cell lines of murine immune, neural, intestinal and fibroblast cell types were tested. After transient degradation phases, certain immune, intestinal and neural cells accumulated PrP(Sc) for up to 28days postinfection. When co-cultured with N2a-3/EGFP neuroblastoma cells for 4days followed by several passages, the immune, intestinal and the neural cell lines were able to transfer infection to neural cells. Our results suggest that some of these cell types may have a role in PrP(Sc) accumulation and intercellular spread of PrP(Sc) infection to neural cells in vivo.

Anti CD-30 Antibody-Drug Conjugate Brentuximab Vedotin (ADCETRIS®) May Be a Promising Treatment Option for Systemic Mastocytosis (SM).

Abstract 2857▪▪This icon denotes a clinically relevant abstractMastocytosis is a clonal proliferation of abnormal mast cells in single or multiple organs leading to clinical syndromes ranging from a benign self-resolving cutaneous disease to the highly aggressive malignancy, mast cell leukemia (MCL). Mastocytosis is categorized under myeloproliferative neoplasms in the 2008 World Health Organization (WHO) classification of hematopoietic and lymphoid diseases. In almost all cases of SM, the bone marrow (BM) is involved by atypical mast cells. The characteristic Asp816Val (D816V) mutation in the KIT gene present in most cases gives the atypical mast cells a survival advantage that leads to treatment resistance with tyrosine kinase inhibitor (TKIs) like imatinib. According to the 2008 WHO classification, 1 major and 1 minor or 3 minor criterion are required for the diagnosis of systemic mastocytosis (Fig. 1a). Systemic Mastocytosis (SM) is subcategorized into four distinct categories in order of indolent to highly aggressive disease: Indolent Systemic Mastocytosis (ISM), SM with an associated hematologic non-MC-lineage disease (SM-AHNMD), aggressive SM (ASM) and MCL. SM with C findings categorized as ASM (Fig. 1b) is treated with cytoreductive chemotherapy such as interferon 2α or 2-chlorodeoxyadenosine (2-CdA). The overall response rate (ORR) with these agents is 40–50% with significant chemotherapy-related toxicity and short durable responses. The majority of patients with ASM and MCL relapse within a year with a very poor prognosis.The CD30 (Ki-1) antigen is expressed in the majority of ASM cases. Thus, CD30 can serve as a potential therapeutic target as well as a reliable tumor marker to follow disease status. Brentuximab vedotin is an antibody-drug conjugate compound consisting of a chimeric monoclonal antibody against CD30 linked to the antimitotic agent monomethyl auristatin E (MMAE). Here we report evidence of anti-tumor activity in two patients with CD30-positive ASM treated with brentuximab vedotin. Case #1:A 62 year old white male with significant medical history of rheumatoid arthritis, diabetes mellitus and coronary artery disease was evaluated for pancytopenia and hepatomegaly. His initial BM aspiration and biopsy revealed multifocal dense mast cell infiltrate (30–40% involvement with tryptase and CD117 positivity). His initial serum tryptase level was 276 ng/ml. He was treated with 2-CdA continuous infusion for three cycles with no significant response and substantial toxicities. He was subsequently enrolled in a clinical trial with brentuximab vedotin given every 3 weeks at 1.8 mg/kg after confirmation of CD30 positivity on BM aspirate and biopsy (Fig. 2). His peripheral blood counts started to improve after the 5thcycle and he had a durable partial response as assessed by his peripheral blood counts and BM biopsies (Fig 2). Importantly, his sequential bone marrow biopsies showed a decrease in mast cell involvement and CD30 intensity with improved normal marrow cellularity (Fig 2). His only treatment-related toxicities were grade II neuropathy and neutropenia for which his dose was reduced to 1.2 mg/kg. He is currently asymptomatic with ECOG performance status of 0 and does not require any growth factor support at Cycle 12 of this regimen. Case #2:A 79 yr old white male with significant medical history of hypertension, obstructive sleep apnea, coronary artery disease s/p CABG was referred for new diagnosis of ASM on BM biopsy (60–70% marrow involvement with 3+ mast cell density). His initial tryptase level was 224ng/ml. He was enrolled on the same clinical protocol as described above. His sequential BM biopsies revealed significant reduction in mast cell density with mild improvement in overall normal cellularity after 3 cycles of treatment. (Fig 3). Conclusion:Brentuximab vedotin is a promising targeted therapy for SM and needs to be confirmed further by a prospective multicenter clinical trial. In two patients reported here treatment is well tolerated, targets the malignant mast cells and seems to prevent disease progression in a rare disorder with few treatment options and limited response rates. [Display omitted] [Display omitted] [Display omitted] Disclosures:Off Label Use: Brentuximab vedotin (ADCETRIS®) is an antibody-drug conjugate compound consisting of a chimeric monoclonal antibody against CD30 linked to the antimitotic agent monomethyl auristatin E (MMAE). It is not FDA approved for use in Mastocytosis.

Improvement by Phytotherapeutic Agent of Detrusor Overactivity, Down-Regulation of Pharmacological Receptors and Urinary Cytokines in Rats with Cyclophosphamide Induced Cystitis

We characterized pharmacological effects of the phytotherapeutic agent Eviprostat® on urodynamic parameters, bladder muscarinic and purinergic receptors, and urinary cytokines in rats with cyclophosphamide induced cystitis. Urodynamic parameters in cyclophosphamide (150 mg/kg intraperitoneally) treated rats were measured by a cystometric method. Muscarinic and purinergic receptors in the bladder and other tissues were measured by radioreceptor assays using [N-methyl-(3)H]scopolamine methyl chloride and [(3)H]αβ-MeATP, respectively. The urinary cytokines interleukin-1β, 6 and 17 were measured with enzyme-linked immunoassay kits. Eviprostat (36 mg/kg per day twice daily for 7 days) was orally administered. On cystometry the micturition interval and micturition volume were significantly decreased in cyclophosphamide vs sham treated rats, while micturition frequency, basal pressure and post-void residual urine volume were significantly increased. Repeat oral administration of Eviprostat in cyclophosphamide treated rats significantly increased the micturition interval and micturition volume, and decreased micturition frequency, basal pressure and post-void residual urine volume. The maximal number of binding sites for [N-methyl-(3)H]scopolamine methyl chloride and [(3)H]αβ-MeATP was significantly decreased in the bladder of cyclophosphamide vs sham treated rats. Such decreases were significantly attenuated by repeat Eviprostat treatment. Increased urinary cytokine levels in cyclophosphamide treated rats were also effectively attenuated by Eviprostat. Repeat Eviprostat treatment significantly improved detrusor overactivity, down-regulated the expression of bladder pharmacological receptors and increased urinary cytokine levels in rats with cyclophosphamide induced cystitis. Therefore, Eviprostat may be a pharmacologically useful phytotherapeutic agent for cystitis.

A carbon nanotube toxicity paradigm driven by mast cells and the IL-₃₃/ST₂ axis.

Concern about the use of nanomaterials has increased significantly in recent years due to potentially hazardous impacts on human health. Mast cells are critical for innate and adaptive immune responses, often modulating allergic and pathogenic conditions. Mast cells are well known to act in response to danger signals through a variety of receptors and pathways including IL-33 and the IL-1-like receptor ST2. Here, the involvement of mast cells and the IL-33/ST2 axis in pulmonary and cardiovascular responses to multi-walled carbon nanotube (MWCNT) exposure are examined. Toxicological effects of MWCNTs are observed only in mice with a sufficient population of mast cells and are not observed when mast cells are absent or incapable of responding to IL-33. Our findings establish for the first time that mast cells and the IL-33/ST2 axis orchestrates adverse pulmonary and cardiovascular responses to an engineered nanomaterial, giving insight into a previously unknown mechanism of toxicity. This novel mechanism of toxicity could be used for assessing the safety of engineered nanomaterials and provides a realistic therapeutic target for potential nanoparticle induced toxicities.

SH2 domain-containing phosphatase 2 is a critical regulator of connective tissue mast cell survival and homeostasis in mice.

Mast cells require KIT receptor tyrosine kinase signaling for development and survival. Here, we report that SH2 domain-containing phosphatase 2 (SHP2) signaling downstream of KIT is essential for mast cell survival and homeostasis in mice. Using a novel mouse model with shp2 deletion within mature mast cells (MC-shp2 knockout [KO]), we find that SHP2 is required for the homeostasis of connective tissue mast cells. Consistently with the loss of skin mast cells, MC-shp2 KO mice fail to mount a passive late-phase cutaneous anaphylaxis response. To better define the phenotype of shp2-deficient mast cells, we used an inducible shp2 knockout approach in bone marrow-derived mast cells (BMMCs) or cultured peritoneal mast cells and found that SHP2 promotes mast cell survival. We show that SHP2 promotes KIT signaling to extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase and downregulation of the proapoptotic protein Bim in BMMCs. Also, SHP2-deficient BMMCs failed to repopulate mast cells in mast cell-deficient mice. Silencing of Bim partially rescued survival defects in shp2-deficient BMMCs, consistent with the importance of a KIT → SHP2 → Ras/ERK pathway in suppressing Bim and promoting mast cell survival. Thus, SHP2 is a key node in a mast cell survival pathway and a new potential therapeutic target in diseases involving mast cells.

FES Kinase Promotes Mast Cell Recruitment to Mammary Tumors via the Stem Cell Factor/KIT Receptor Signaling Axis

KIT receptor is required for mast cell development, survival, and migration toward its ligand stem cell factor (SCF). Many solid tumors express SCF and this leads to mast cell recruitment to tumors and release of mediators linked to tumor angiogenesis, growth, and metastasis. Here, we investigate whether FES protein-tyrosine kinase, a downstream effector of KIT signaling in mast cells, is required for migration of mast cells toward SCF-expressing mammary tumors. Using a novel agarose drop assay for chemotaxis of bone marrow-derived mast cells (BMMC) toward SCF, we found that defects in chemotaxis of fes-null BMMCs correlated with disorganized microtubule networks in polarized cells. FES displayed partial colocalization with microtubules in polarized BMMCs and has at least two direct microtubule binding sites within its N-terminal F-BAR and SH2 domains. An oligomerization-disrupting mutation within the Fer/CIP4 homology-Bin/Amphiphysin/Rvs (F-BAR) domain had no effect on microtubule binding, whereas microtubule binding to the SH2 domain was dependent on the phosphotyrosine-binding pocket. FES involvement in mast cell recruitment to tumors was tested using the AC2M2 mouse mammary carcinoma model. These tumor cells expressed SCF and promoted BMMC recruitment in a KIT- and FES-dependent manner. Engraftment of AC2M2 orthotopic and subcutaneous tumors in control or fes-null mice, revealed a key role for FES in recruitment of mast cells to the tumor periphery. This may contribute to the reduced tumor growth and metastases observed in fes-null mice compared with control mice. Taken together, FES is a potential therapeutic target to limit the progression of tumors with stromal mast cell involvement.

Hypersensitivity to antineoplastic agents: mechanisms and treatment with rapid desensitization

Hypersensitivity reactions (HSRs) to chemotherapy drugs, such as taxanes and platins, and to monoclonal antibodies limit their therapeutic use due to the severity of some reactions and the fear of inducing a potentially lethal reaction in highly sensitized patients. Patients who experience hypersensitivity reactions face the prospect of abandoning first-line treatment and switching to a second-line, less effective therapy. Some of these reactions are mast cell-mediated hypersensitivity reactions, a subset of which occur through an immunoglobulin (IgE)-dependent mechanism, and are thus true allergies. Others involve mast cells without a demonstrable IgE mechanism. Whether basophils can participate in these reactions has not been demonstrated. Rapid drug desensitization (RDD) is a procedure that induces temporary tolerance to a drug, allowing a medication allergic patient to receive the optimal agent for his or her disease. Through RDD, patients with IgE and non-IgE HSRs can safely be administered important medications while minimizing or completely inhibiting adverse reactions. Due to the clinical expansion and success of RDD, the molecular mechanisms inducing the temporary tolerization have been investigated and are partially understood, allowing for safer and more effective protocols. This article reviews the current literature on molecular mechanisms of RDD with an emphasis in our recent contributions to this field as well as the indications, methods and outcomes of RDD for taxanes, platins, and monoclonal antibodies.

Neutrophils: key players in mast cell-mediated thermal pain in mice (67.4)

Abstract Mast cells are involved in a range of physiologies and pathologies including allergic disease, defense against pathogens, and neutralization of venoms. Recently, these cells have been shown to play significant roles in inflammatory pain. Acute inflammation is a beneficial mechanism designed to prevent further tissue damage; however, it can also lead to a decreased quality of life and, as such, is a pervasive health concern. The involvement of mast cells in this process has not been fully characterized. We show, in a mast cell-dependent model of thermal pain that degranulation of peripheral mast cells in the plantar tissue of mice is accompanied by neutrophil influx as well as edema and upregulation of pro-inflammatory cytokines. When mast cells are stabilized with sodium cromoglycate, pain, edema and neutrophil influx are abrogated. Additionally, when neutrophil influx is blocked with pre-administration of the selectin blocker fucoidan, pain and edema are also abrogated. This suggests neutrophil influx is a key event in the development of mast cell-initiated inflammatory pain.

Localization of heat shock protein 70 in rat mast cells

Heat shock proteins (Hsp) are intracellular chaperons, as well as extracellular molecules with immunomodulatory and signaling functions engaged in adaptation to stress on the cellular and organism levels. The presence of Hsp in secretory granules of mast cells (MCs) may be correlated with mast cells’ active participation in adaptation to stress. Using immunoelectron microscopy, we showed that Hsp70 was localized in secretory granules of rat pericardial and peritoneal mast cells. Localization of Hsp70 in rat peritoneal mast cells isolated by Percoll density gradient centrifugation was confirmed by immunoblotting. The possible involvement of mast cells in production of extracellular Hsp70, as well as Hsp70 functions inside the mast cells, is discussed.

Chapter 21: Urticaria and angioedema

Urticaria, also known as hives, may affect up to 20% of the population at some time in their lives. Urticaria is characterized by extreme pruritus and described as erythematous, raised, circumscribed lesions with central pallor that blanch with pressure. The pathogenesis of urticaria involves mast cell activation, with subsequent release of histamine and other vasoactive mediators, leading to increased vascular permeability of postcapillary venules and development of edema, erythema, and pruritus. Urticaria is closely associated with angioedema in 40% of individuals; ∼10% of patients experience angioedema without urticaria. Urticarial lesions often are generalized with multiple lesions in no specific distribution; angioedema tends to be localized, commonly affecting the face (periorbital and perioral regions), tongue, uvula, soft palate or larynx, extremities, and genitalia. Urticaria is subdivided into acute and chronic urticaria based on duration of symptoms. Acute urticaria lasts <6 weeks and an identifiable cause may be discovered such as food products, medications (aspirin, nonsteroidal anti-inflammatory drugs, and antibiotics), or insect stings. Urticaria lasting >6 weeks is designated as chronic urticaria, and an etiology is seldom identified and thus considered idiopathic. Chronic urticaria may have an autoimmune basis. There is a well-documented association between autoimmune hypothyroidism (Hashimoto's disease) and urticaria and angioedema with higher incidence of antithyroid (antithyroglobulin and antiperoxidase) antibodies in these usually euthyroid patients. Furthermore, studies have revealed a circulating IgG antibody directed against the IgE receptor (F(Cε)RIα) or IgE in 40-60% of patients with chronic urticaria. Histamine 1-receptor antagonists (antihistamines) are initial therapy.

Chapter 24: Anaphylaxis

Anaphylaxis is a sudden-onset, immediate reaction that implies a risk of death. Think of a "rule of 2's" for anaphylaxis implying that reactions usually begin within 2 minutes to 2 hours after injection, infusion, ingestion, contact, or inhalation. Fatalities can be from asphyxiation from laryngeal or oropharyngeal swelling, collapse from hypotensive shock, cardiac arrest, or acute severe bronchoconstriction causing respiratory failure and arrest. When there is activation of mast cells and basophils in anaphylaxis, chemical mediators are detectable. The preformed mediators from mast cells include histamine, tryptase, carboxypeptidase A, and proteoglycans (heparin and chondroitin sulfates). Newly synthesized mediators include prostaglandin D(2), leukotriene D(4), and platelet-activating factor. Crucial actions of the mediators include an abrupt increase in vascular permeability, vascular smooth muscle relaxation, and bronchial smooth muscle contraction. Anaphylaxis can be classified into immunologic, nonimmunologic, or idiopathic based on the associated mechanism. For example, immunologic causes of anaphylaxis are those mediated by IgE antibodies acting through the FcεR I (foods, insect venom, and beta-lactam antibiotics) whereas non-IgE immunologic anaphylaxis is mediated without presence of antiallergen IgE antibodies or via FcεRI activation (radiographic contrast material). Nonimmunologic anaphylaxis involves mast cell mediator release such as occurs with exercise, cold temperature exposure, or from medications such as opioids or vancomycin. Idiopathic anaphylaxis involves mast cell activation (acutely elevated urine histamine or serum tryptase) and activated lymphocytes. Because anaphylaxis is a medical emergency, the drug of choice is epinephrine, not H(1)-receptor antagonists.