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To the Editor, Immediate hypersensitivity reactions are related to mast cell and/or basophil activation. The mediators released such as tryptase and histamine are involved in clinical symptoms and are key parameters that contribute to diagnosis. Serum tryptase concentrations peak between 30 minutes and 4 hours following the reaction. Tryptase release is considered a robust marker of mast cell degranulation but is not informative in mild reactions.1 Histamine is released at the early beginning of the reaction but has a short half-life. The concentration value can be altered by pre-analytic conditions.2 Anaphylactic reactions can occur during night and week-end when laboratories can’t take charge of samples. To our knowledge, no thorough study of the stability in whole blood of these markers in anaphylaxis has been published. The aim of our study was to evaluate the impact of whole blood sample storage conditions (temperature and delay before centrifugation and plasma collection) on the reliability of tryptase and histamine measurements.Blood samples from 14 patients suspected of anaphylactic reactions (grade 2 to 4 of the Ring and Messmer scale)3 and from 10 volunteers were collected on EDTA after signed informed consent (CCPPRB Caen Basse-Normandie protocol 2004-32). The description of the patient anaphylactic episodes appears in Table 1.When received in the lab, an aliquot of whole blood was processed for diagnostic (reference measurement) and the remaining was divided in aliquots stored at room temperature (RT) or at +4°C for 24, 72 hours or 7 days (patients) or 2, 6, 24 or 72 hours for controls before centrifugation and plasma collection.Total tryptase concentrations were measured by an automated fluoroimmunoassay (ThermoFisher, Phadia SAS, ). Increased tryptase is defined as ≥ 1.2 x basal value + 2 µg.L-1.4 In our hands, tryptase uncertainties of measurement for low and high concentrations (9 µg.L-1 and 38.2 µg.L-1) are 17% and 16% respectively, in accordance with published results.5 Plasma histamine concentrations were measured by a radioimmunoassay (Beckman Coulter, Immunotech, France). Increased values defined by the manufacturer are >10 nmol.L-1, in accordance with published data.6 In our hands, histamine uncertainties of measurement for low and moderate concentrations (4.7 nmol.L-1 and 12.9 nmol.L-1) were 22% and 25%, respectively.The differences between the concentrations measured before and after storage were compared by paired two-tailed t-tests using SAS software. Results were considered significant for p < 0.05.As shown in Figure 1A, storage conditions did not modify tryptase concentrations (linear regression: slope=1.079, R²=0.9675). Tryptase concentrations appeared stable in whole blood left at +4°C for 7 days or 72 hours at RT.Histamine concentrations in patient samples were not modified during 72h at +4°C (Figure 1B) or at RT (Figure 1C). In the control group at RT, histamine concentrations were significantly increased at 6 hours (p=0.005) although moderately increased and staying within the limits of uncertainty measurement and never reaching the positivity threshold (Figure 1E). After 24 hours at RT a false positivity was observed for 8 of 10 samples (p

Background The protease chymase generates multiple factors involved in tissue remodelling including angiotensin II (Ang II) and has been implicated in the pathophysiology of diabetic kidney disease (DKD). This study investigated the effects of the chymase inhibitor fulacimstat on albuminuria in patients with Type II diabetes mellitus and a clinical diagnosis of DKD. Methods In this double-blind, randomized, placebo-controlled trial, patients were on the maximum tolerated dose of either an Ang II receptor blocker or an Ang-converting enzyme inhibitor since at least 3 months before the screening visit. Eligible patients were randomized in a 2:1 ratio to treatment with either 25 mg fulacimstat (n = 99) or placebo (n = 48) twice daily on top of standard of care. Results The randomized patients had a mean urine albumin–creatinine ratio (UACR) of 131 mg/g (range: 29–2429 mg) and a mean (standard deviation) estimated glomerular filtration rate of 60.8 ± 16.9 mL/min/1.73 m2 before treatment start. Fulacimstat was safe and well tolerated, and achieved mean total trough concentrations that were ∼9-fold higher than those predicted to be required for minimal therapeutic activity. UACR increased by 27.4% [coefficient of variation (CV) 86%] and 3% (CV 88.9%) after 24 weeks of treatment with placebo or fulacimstat, respectively. Analysis of covariance revealed a least square mean UACR ratio (fulacimstat/placebo) of 0.804 (90% CI 0.627–1.030, P = 0.1477), indicating a statistically non-significant UACR reduction of 19.6% after fulacimstat treatment compared with placebo. Conclusions Fulacimstat was safe and well tolerated but did not reduce albuminuria in patients with DKD. These findings do not support a therapeutic role for chymase inhibition in DKD.

A novel coronavirus [severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), or 2019 novel coronavirus] has been identified as the pathogen of coronavirus disease 2019. The main protease (Mpro, also called 3‐chymotrypsin‐like protease) of SARS‐CoV‐2 is a potential target for treatment of COVID‐19. A Mpro homodimer structure suitable for docking simulations was prepared using a crystal structure (PDB ID: https://doi.org/10.2210/pdb6Y2G/pdb; resolution 2.20 Å). Structural refinement was performed in the presence of peptidomimetic α‐ketoamide inhibitors, which were previously disconnected from each Cys145 of the Mpro homodimer, and energy calculations were performed. Structure‐based virtual screenings were performed using the ChEMBL database. Through a total of 1 485 144 screenings, 64 potential drugs (11 approved, 14 clinical, and 39 preclinical drugs) were predicted to show high binding affinity with Mpro. Additional docking simulations for predicted compounds with high binding affinity with Mpro suggested that 28 bioactive compounds may have potential as effective anti‐SARS‐CoV‐2 drug candidates. The procedure used in this study is a possible strategy for discovering anti‐SARS‐CoV‐2 drugs from drug libraries that may significantly shorten the clinical development period with regard to drug repositioning., Here, I describe virtual screenings for compounds targeting main protease of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) to predict potential anti‐SARS‐CoV‐2 drugs and lead compounds. The procedure described herein may be a suitable drug repositioning strategy for the discovery of anti‐SARS‐CoV‐2 drugs from drug libraries.

Rationale: Kidney homeostasis is critically determined by the coordinated activity of the renin-angiotensin system (RAS), including the balanced synthesis of its main effector peptides Ang (angiotensin) II and Ang (1–7). The condition of enzymatic overproduction of Ang II relative to Ang (1–7) is termed RAS dysregulation and leads to cellular signals, which promote hypertension and organ damage, and ultimately progressive kidney failure. ACE2 (angiotensin-converting enzyme 2) and NEP (neprilysin) induce the alternative, and potentially reno-protective axis by enhancing Ang (1–7) production. However, their individual contribution to baseline RAS balance and whether their activities change in chronic kidney disease (CKD) has not yet been elucidated. Objective: To examine whether NEP-mediated Ang (1–7) generation exceeds Ang II formation in the healthy kidney compared with diseased kidney. Methods and Results: In this exploratory study, we used liquid chromatography-tandem mass spectrometry to measure Ang II and Ang (1–7) synthesis rates of ACE, chymase and NEP, ACE2, PEP (prolyl-endopeptidase), PCP (prolyl-carboxypeptidase) in kidney biopsy homogenates in 11 healthy living kidney donors, and 12 patients with CKD. The spatial expression of RAS enzymes was determined by immunohistochemistry. Healthy kidneys showed higher NEP-mediated Ang (1–7) synthesis than Ang II formation, thus displaying a strong preference towards the reno-protective alternative RAS axis. In contrast, in CKD kidneys higher levels of Ang II were recorded, which originated from mast cell chymase activity. Conclusions: Ang (1–7) is the dominant RAS peptide in healthy human kidneys with NEP rather than ACE2 being essential for its generation. Severe RAS dysregulation is present in CKD dictated by high chymase-mediated Ang II formation. Kidney RAS enzyme analysis might lead to novel therapeutic approaches for CKD.

Recently, the world has witnessed outbreak of a novel Coronavirus (SARS-CoV-2), the virus which initially emerged in Wuhan, China has now made its way to a large part of the world, resulting in a public emergency of international concern. The functional importance of Chymotrypsin-like protease (3CL

Ticks inject serine protease inhibitors (serpins) into their feeding sites to evade serine protease-mediated host defenses against tick-feeding. This study describes two highly identitical (97%) but functionally different Amblyomma americanum tick saliva serpins (AAS41 and 46) that are secreted at the inception of tick-feeding. We show that AAS41, which encodes a leucine at the P1 site inhibits inflammation system proteases: chymase (SI = 3.23, Ka = 5.6 ± 3.7X103M−1 s−1) and α-chymotrypsin (SI = 3.18, Ka = 1.6 ± 4.1X104M−1 s−1), while AAS46, which encodes threonine has no inhibitory activity. Similary, rAAS41 inhibits rMCP-1 purified from rat peritonuem derived mast cells. Consistently, rAAS41 inhibits chymase-mediated inflammation induced by compound 48/80 in rat paw edema and vascular permeability models. Native AAS41/46 proteins are among tick saliva immunogens that provoke anti-tick immunity in repeatedly infested animals as revealed by specific reactivity with tick immune sera. Of significance, native AAS41/46 play critical tick-feeding functions in that RNAi-mediated silencing caused ticks to ingest significantly less blood. Importantly, monospecific antibodies to rAAS41 blocked inhibitory functions of rAAS41, suggesting potential for design of vaccine antigens that provokes immunity to neutralize functions of this protein at the tick-feeding site. We discuss our findings with reference to tick-feeding physiology and discovery of effective tick vaccine antigens.

A recent research has identified chymase, a mast cell-specific protease as an exclusive novel therapeutic target to prevent Japanese encephalitis virus (JEV) induced encephalitis. Interestingly, JEV activates mast cell specific chymase during its penetration through blood brain barrier (BBB) which eventually guide to viral encephalitis. Hence, in this study, natural chemical entities (NCE) from multiple databases (MPD3, TIPDB and MTDP) were virtually screened for their binding affinity as chymase inhibitors, a promising negotiator for prolong survival against JEV tempted encephalitis. Merged computational programs, Maestro software, QikProp, ProTox and Gromacs were applied to screen the NCEs against target receptor (PDB: 4KP0). Three hits (C00008437, C00014417 and 8141903) were identified after employing a series of sieves such as High Throughput Virtual Screening (HTVS), Standard precision (SP) and Xtra precision (XP) molecular docking simulations followed by desired pharmacokinetic-toxicity profile predictions and molecular dynamics (MD) examinations. Maestro simulations resulted in best three binding energy scores as -11.992 kcal/mol (first ranked; C00008437), -11.673 kcal/mol (second ranked; C00014417) and -11.456 kcal/mol (third ranked; 8141903), respectively. The top three hits revealed an ideal range of pharmacokinetic and toxicity descriptors values. In addition, MD simulations enabled us to confirm top hits higher selectivity toward chymase receptor. In conclusion, this might potentially represent remarkable novel classes with an effective chymase mediated treatment to combat JEV induced encephalitis, which need to justify with further detail studies.

Human lung fibroblasts (HLFs) treated with the viral mimetic polyinosine-polycytidylic acid (poly I:C) form an extracellular matrix (ECM) enriched in hyaluronan (HA) that avidly binds monocytes and lymphocytes. Mast cells are important innate immune cells in both asthma and acute respiratory infections including respiratory syncytial virus (RSV); however, the effect of RSV on HA dependent mast cell adhesion and/or function is unknown. To determine if RSV infection of HLFs leads to the formation of a HA-enriched ECM that binds and enhances mast cell activity primary HLFs were infected with RSV for 48 h prior to leukocyte binding studies using a fluorescently labeled human mast cell line (LUVA). Parallel HLFs were harvested for characterization of HA production by ELISA and size exclusion chromatography. In separate experiments, HLFs were infected as above for 48 h prior to adding LUVA cells to HLF wells. Co-cultures were incubated for 48 h at which point media and cell pellets were collected for analysis. The role of the hyaladherin tumor necrosis factor-stimulated gene 6 (TSG-6) was also assessed using siRNA knockdown. RSV infection of primary HLFs for 48 h enhanced HA-dependent LUVA binding assessed by quantitative fluorescent microscopy. This coincided with increased HLF HA synthase (HAS) 2 and HAS3 expression and decreased hyaluronidase (HYAL) 2 expression leading to increased HA accumulation in the HLF cell layer and the presence of larger HA fragments. Separately, LUVAs co-cultured with RSV-infected HLFs for 48 h displayed enhanced production of the mast cell proteases, chymase, and tryptase. Pre-treatment with the HA inhibitor 4-methylumbelliferone (4-MU) and neutralizing antibodies to CD44 (HA receptor) decreased mast cell protease expression in co-cultured LUVAs implicating a direct role for HA. TSG-6 expression was increased over the 48-h infection. Inhibition of HLF TSG-6 expression by siRNA knockdown led to decreased LUVA binding suggesting an important role for this hyaladherin for LUVA adhesion in the setting of RSV infection. In summary, RSV infection of HLFs contributes to inflammation via HA-dependent mechanisms that enhance mast cell binding as well as mast cell protease expression via direct interactions with the ECM.

Mast cells (MCs) are inflammatory cells primarily found in tissues in close contact with the external environment, such as the skin and the intestinal mucosa. They store large amounts of active components in cytoplasmic granules, ready for rapid release. The major protein content of these granules is proteases, which can account for up to 35 % of the total cellular protein. Depending on their primary cleavage specificity, they can generally be subdivided into chymases and tryptases. Here we present the extended cleavage specificities of two such proteases from the platypus. Both of them show an extended chymotrypsin-like specificity almost identical to other mammalian MC chymases. This suggests that MC chymotryptic enzymes have been conserved, both in structure and extended cleavage specificity, for more than 200 million years, indicating major functions in MC-dependent physiological processes. We have also studied a third closely related protease, originating from the same chymase locus whose cleavage specificity is closely related to the apoptosis-inducing protease from cytotoxic T cells, granzyme B. The presence of both a chymase and granzyme B in all studied mammals indicates that these two proteases bordering the locus are the founding members of this locus.

Background: Renin-angiotensin system (RAS) is a complex network of enzymes and peptides with the essential role in blood pressure control. The relationships between RAS components, RAS-related gene...

INTRODUCTION: Chymase is primarily found in mast cells (MCs), fibroblasts, and vascular endothelial cells. MC chymase is released into the extracellular interstitium in response to inflammatory signals, tissue injury, and cellular stress. Among many functions, chymase is a major extravascular source for angiotensin II (Ang II) generation. Several recent pre-clinical and a few clinical studies point to the relatively unrecognized fact that chymase inhibition may have significant therapeutic advantages over other treatments in halting progression of cardiac and vascular disease. AREA COVERED: The present review covers patent literature on chymase inhibitors for the treatment of cardiac diseases registered between 2010 and 2018. EXPERT OPINION: Increase in cardiac MC number in various cardiac diseases has been found in pathological tissues of human and experimental animals. Meta-analysis data from large clinical trials employing angiotensin converting enzyme (ACE) inhibitors show a relatively small risk reduction of clinical cardiovascular endpoints. The disconnect between the expected benefit associated with Ang II blockade of synthesis or activity underscore a greater participation of chymase compared to ACE in forming Ang II in humans. Emerging literature and a reconsideration of previous studies provide lucid arguments to reconsider chymase as a primary Ang II forming enzyme in human heart and vasculature.

Purpose of review The aim of the review is to describe the different clinical pictures of anaphylaxis (phenotypes), in relation to the underlying mechanisms and potential biomarkers, to describe anaphylaxis endotypes. This may aid in achieving a better understanding, management and outcomes of such severe reactions. Recent findings Different anaphylaxis phenotypes have been outlined, ranging from the classical type-I-like to those suggestive of cytokine-storm-like or complement-mediated reactions. Underlying mechanisms differ and biomarkers of cells and systems involved are being identified (tryptase, IL-6, bradykinin etc.) SUMMARY: Identifying specific phenotypes/endotypes will allow the application of precision medicine in patients with anaphylaxis, providing insights to the most appropriate approach in each case.

Tree nuts are among “Big Eight” and have been reported globally for causing allergy. Buchanania lanzan (Bl) is one of the major tree nuts consumed by Indian population. However, very little is known about B. lanzan's induced allergic manifestation. Therefore, evaluation of it's allergenic potential was undertaken. Bl-crude protein extract sensitized BALB/c mice sera were used to identify the allergic proteins by it's IgE binding capability. The major IgE binding proteins found with molecular weight of 11, 20, 23, 25, 48, 54, and 65 kDa. Specific IgE, specific IgG1, MCPT-1, PGD2 and histamine were assessed in mice sera. Enormous amount of mast cell infiltration was noted in different organs. The levels of Th1/Th2 transcription factors GATA-3, SOCS3 and STAT-6 were found upregulated, whereas T-bet was downregulated. Furthermore, elevated Th1/Th2 cytokine responses were observed in mice sera. All together, these reactions developed systemic anaphylaxis upon Bl-CPE challenge in sensitized BALB/c mice. In order to confirm the evidences obtained from the studies carried out in BALB/c, the investigation was extended to human subjects as well. Control subjects and allergic patients were subjected to skin prick test (SPT). Later sera collected from those positive to SPT along with controls were used for IgE immunoblotting. The study evaluated the allergic manifestation associated with Bl, and identified it's proteins attributing Bl-mediated allergy. This work may help in managing tree nuts mediated allergies especially due to Buchanania lanzan sensitization.

Chymase is a serine protease that is predominantly expressed by mast cells and has key roles in immune defense and the cardiovascular system. This enzyme has also emerged as a therapeutic target for cardiovascular disease due to its ability to remodel cardiac tissue and generate angiotensin II. Here, we used the nature-derived cyclic peptide sunflower trypsin inhibitor-1 (SFTI-1) as a template for designing novel chymase inhibitors. The key binding contacts of SFTI-1 were optimized by combining a peptide substrate library screen with structure-based design, which yielded several variants with potent activity. The lead variant was further modified by replacing the P1 Tyr residue with para-substituted Phe derivatives, generating new inhibitors with improved potency (Ki = 1.8 nM) and higher selectivity over closely related enzymes. Several variants were shown to block angiotensin I cleavage in vitro, highlighting their potential for further development and future evaluation as pharmaceutical leads.

Soybean products are limited in terms of safe consumption because of the sensitization of raw materials. In this study, the allergenicity of cross-linked tofu with microbial transglutaminase (MTG) was evaluated on the basis of a BALB/c mouse model. The mice were randomly divided into five groups. Cholera toxin was used as an adjuvant to sensitize the mice through intragastric administration, and tofu was given orally to investigate its sensitization effect on the mice. The allergy symptoms, body temperature, and weight of the mice were detected. The immunoglobulin E (IgE), immunoglobulin G (IgG), and spleen cytokines of the mice were determined through an enzyme-linked immunosorbent assay. The regulation of the differentiation balance of the different subsets of splenic T lymphocyte (Th1, Th2) and regulatory T cells (Tregs) in the mice was measured through flow cytometry. Results showed that the mice administered with MTG-cross-linked tofu had fewer allergic symptoms compared with those of the control group. The concentrations of serum-specific IgE and IgG, plasma histamine, and mast cell protease 1 (mMCP-1) significantly decreased. The Th2-related cytokine levels reduced, and the IFN-γ levels increased. The proportion of Th2 cells decreased, and the proportion of CD4+CD25+Foxp+ Tregs increased as the percentage of Th1 cells increased. Therefore, the sensitization of enzymatic cross-linked tofu decreased.

Accumulating evidence suggests that mast cells should play critical roles in disruption and maintenance of intestinal homeostasis, although it remains unknown how they affect local microenvironment. Interleukin-9 (IL-9) was found to play critical roles in intestinal mast cell accumulation induced in various pathological conditions, such as parasite infection and oral allergen-induced anaphylaxis. Newly recruited intestinal mast cells trigger inflammatory responses and damage epithelial integrity through release of a wide variety of mediators including mast cell proteases. We established a novel culture model (mucosal mast cell-like cultured mast cells, MMC-like MCs), in which murine IL-3-dependent bone marrow-derived cultured mast cells (BMMCs) were further cultured in the presence of stem cell factor and IL-9. In MMC-like MCs, drastic up-regulation of Mcpt1 and Mcpt2 was found. Although histamine storage and tryptase activity were significantly downregulated in the presence of SCF and IL-9, it was entirely reversed when mast cells were co-cultured with a murine fibroblastic cell line, Swiss 3T3. MMC-like MCs underwent degranulation upon IgE-mediated antigen stimulation, which was found to less sensitive to lower concentrations of IgE in comparison with BMMCs. This model might be useful for investigation of the spatiotemporal changes of newly recruited intestinal mast cells.

Background Chymase is the major angiotensin II (Ang II)-forming enzyme in cardiovascular tissue, with an important role in atrial remodeling. This study aimed to examine the association between chymase 1 gene (CMA1) polymorphisms and atrial fibrillation (AF) in a Chinese Han population. Methods This case-control study enrolled 126 patients with lone AF and 120 age- and sex-matched healthy controls, all from a Chinese Han population. Five CMA1 polymorphisms were genotyped. Results The CMA1 polymorphism rs1800875 (G-1903A) was associated with AF. The frequency of the GG genotype was significantly higher in AF patients compared with controls (p = 0.009). Haplotype analysis further demonstrated an increased risk of AF associated with the rs1800875-G haplotype (Hap8 TGTTG, odds ratio (OR) = 1.668, 95% CI 1.132–2.458, p = 0.009), and a decreased risk for the rs1800875-A haplotype (Hap5 TATTG, OR = 0.178, 95% CI 0.042–0.749, p = 0.008). Conclusions CMA1 polymorphisms may be associated with AF, and the rs1800875 GG genotype might be a susceptibility factor for AF in the Chinese Han population.

Chymase released from mast cells produces pro‐fibrotic, inflammatory, and vasoconstrictor agents. Studies were performed to test the hypothesis that chronic chymase inhibition provides a renal protective effect in type 2 diabetes. Diabetic (db/db) and control mice (db/m) were chronically infused with a chymase‐specific inhibitor or vehicle for 8 weeks. Baseline urinary albumin excretion (UalbV) averaged 42 ± 3 and 442 ± 32 microg/d in control (n = 22) and diabetic mice (n = 27), respectively (p, The most significant finding of the present study is the identification that chronic inhibition of chymase in the db/db type II diabetic mouse results in renoprotection as reflected by a significant attenuation of urinary albumin excretion and mesangial expansion/glomerular injury. These studies suggest that chymase inhibition may represent a novel therapeutic target in cardiovascular and renal disease.

Background Chemerin is a chemoattractant involved in immunity that also functions as an adipokine. Chemerin is secreted as an inactive precursor (chem163S), and its activation requires proteolytic cleavages at its C-terminus, involving proteases in coagulation, fibrinolysis, and inflammation. Previously, we found chem158K was the dominant chemerin form in synovial fluids from patients with arthritis. In this study, we aimed to characterize a distinct cleaved chemerin form, chem156F, in osteoarthritis (OA) and rheumatoid arthritis (RA). Methods Purified chem156F was produced in transfected CHO cells. To quantify chem156F in OA and RA samples, we developed a specific ELISA for chem156F using antibody raised against a peptide representing the C-terminus of chem156F. Results Ca2+ mobilization assays showed that the EC50 values for chem163S, chem156F, and chem157S were 252 ± 141 nM, 133 ± 41.5 nM, and 5.83 ± 2.48 nM, respectively. chem156F was more active than its precursor, chem163S, but very much less potent than chem157S, the most active chemerin form. Chymase was shown to be capable of cleaving chem163S at a relevant rate. Using the chem156F ELISA we found a substantial amount of chem156F present in synovial fluids from patients with OA and RA, 24.06 ± 5.51 ng/ml and 20.35 ± 5.19 ng/ml (mean ± SEM, n = 25) respectively, representing 20% of total chemerin in OA and 76.7% of chemerin in RA synovial fluids. Conclusions Our data show that chymase cleavage of chem163S to partially active chem156F can be found in synovial fluids where it can play a role in modulation of the inflammation in joints. Electronic supplementary material The online version of this article (10.1186/s13075-018-1615-y) contains supplementary material, which is available to authorized users.

There is no definitive predictor of dengue severity, and this has led to a very large number of unnecessary hospitalizations worldwide. Although mast cell mediators are believed to a play role in dengue severity, the lack of precise kinetic data demands further research on early predictors. We enrolled 111 patients with confirmed dengue and 85 with “other febrile illness” (OFI) in a hospital-based prospective study in Vietnam. Dengue patients were classified as level 1, 2, or 3 based on the clinical intervention received. Blood samples were collected from each patient every day (pre- and post-defervescence) and after discharge. Plasma chymase, total IgE, and dengue-specific IgE were measured. Dengue-specific IgE levels showed an increasing trend during the course of illness and remained high even at post-discharge, although no significant difference was observed among severity levels. Total IgE showed no such trend. The specific IgE/total IgE ratio (S/T ratio) remained constantly higher in level 3 patients compared to other levels, with a significant difference at some time points. The S/T ratio of acute phase samples (before defervescence) tended to increase with increasing severity (level 1 < 2 < 3), and was significantly higher in level 3 patients than in level 1 and OFI patients. As an early predictor of severity allowing level 3 patients to be distinguished from other dengue patients, the S/T ratio achieved a sensitivity of 75% and specificity of 68%. We describe the kinetic profiles of IgEs, their ratio, and chymase levels at different severity levels. The S/T ratio was found to be associated with dengue severity, suggesting that it could potentially be used as an early predictor of severity.

Chagas disease is an infection caused by the parasite Trypanosoma cruzi that affects millions of people worldwide and is endemic in Latin America. Megacolon is the most frequent complication of the digestive chronic form and happens due to lesions of the enteric nervous system. The neuronal lesions seem to initiate in the acute phase and persist during the chronic phase, albeit the mechanisms involved in this process are still debated. Among the cells of the immune system possibly involved in this pathological process is the mast cell (MC) due to its well-known role in the bi-directional communication between the immune and nervous systems. Using ultrastructural analysis, we found an increased number of degranulated MCs in close proximity to nerve fibers in infected patients when compared with uninfected controls. We also immunostained MCs for the two pro-inflammatory molecules tryptase and chymase, the first being also important in neuronal death. The number of MCs immunostained for tryptase or chymase was increased in patients with megacolon, whereas increased tryptase staining was additionally observed in patients without megacolon. Moreover, we detected the expression of the tryptase receptor PAR2 in neurons of the enteric nervous system, which correlated to the tryptase staining results. Altogether, the data presented herein point to the participation of MCs on the denervation process that occurs in the development of T. cruzi-induced megacolon.

Significance We show that distinct subsets of mast cells (MCs) expand with sequential oncogenic events in small bowel cancer. Mucosal mast cells (MMCs) previously detected early during Trichinella spiralis infection expand in adenomatous polyps in an IL-10–dependent manner. Connective tissue mast cells (CTMCs), earlier shown to expand during the resolution of inflammation following clearance of T. spiralis, are independent of IL-10 and associate with the transition of polyps to adenocarcinoma. IL-33 upregulates the CTMC lineage-specific protease murine mast cell protease 6 (mMCP6). Ablation of mMCP6 attenuates tumor growth. Thus, tissue sentinel cells respond to oncogenic events and cellular transformation in effect to help promote cancer. Delineating the types of MCs present at various stages of disease offers actionable cellular targets for therapeutic intervention in disease progression., Mast cells (MCs) are tissue resident sentinels that mature and orchestrate inflammation in response to infection and allergy. While they are also frequently observed in tumors, the contribution of MCs to carcinogenesis remains unclear. Here, we show that sequential oncogenic events in gut epithelia expand different types of MCs in a temporal-, spatial-, and cytokine-dependent manner. The first wave of MCs expands focally in benign adenomatous polyps, which have elevated levels of IL-10, IL-13, and IL-33, and are rich in type-2 innate lymphoid cells (ILC2s). These vanguard MCs adhere to the transformed epithelial cells and express murine mast cell protease 2 (mMCP2; a typical mucosal MC protease) and, to a lesser extent, the connective tissue mast cell (CTMC) protease mMCP6. Persistence of MCs is strictly dependent on T cell-derived IL-10, and their loss in the absence of IL-10–expressing T cells markedly delays small bowel (SB) polyposis. MCs expand profusely in polyposis-prone mice when T cells overexpress IL-10. The frequency of polyp-associated MCs is unaltered in response to broad-spectrum antibiotics, arguing against a microbial component driving their recruitment. Intriguingly, when polyps become invasive, a second wave of mMCP5+/mMCP6+ CTMCs expands in the tumor stroma and at invasive tumor borders. Ablation of mMCP6 expression attenuates polyposis, but invasive properties of the remaining lesions remain intact. Our findings argue for a multistep process in SB carcinogenesis in which distinct MC subsets, and their elaborated proteases, guide disease progression.

ApoA-I, the main structural and functional protein of HDL particles, is cardioprotective, but also highly sensitive to proteolytic cleavage. Here, we investigated the effect of cardiac mast cell activation and ensuing chymase secretion on apoA-I degradation using isolated rat hearts in the Langendorff perfusion system. Cardiac mast cells were activated by injection of compound 48/80 into the coronary circulation or by low-flow myocardial ischemia, after which lipid-free apoA-I was injected and collected in the coronary effluent for cleavage analysis. Mast cell activation by 48/80 resulted in apoA-I cleavage at sites Tyr(192) and Phe(229), but hypoxic activation at Tyr(192) only. In vitro, the proteolytic end-product of apoA-I with either rat or human chymase was the Tyr(192)-truncated fragment. This fragment, when compared with intact apoA-I, showed reduced ability to promote migration of cultured human coronary artery endothelial cells in a wound-healing assay. We propose that C-terminal truncation of apoA-I by chymase released from cardiac mast cells during ischemia impairs the ability of apoA-I to heal damaged endothelium in the ischemic myocardium.

Nonalcoholic steatohepatitis (NASH), in which there is steatosis and fibrosis in the liver, is linked to metabolic syndrome and progresses to hepatic cirrhosis. In this study, a novel hamster NASH model derived from metabolic syndrome was made using hamsters. Hamsters were fed a normal or a high-fat and high-cholesterol (HFC) diet for 12 weeks. Body weight and the ratio of liver weight to body weight were significantly greater in HFC diet-fed hamsters than in normal diet-fed hamsters. Triglyceride, low-density lipoprotein cholesterol, and glucose levels in blood were significantly increased in HFC diet-fed hamsters, and blood pressure also tended to be high, suggesting that the HFC diet-fed hamsters developed metabolic syndrome. Hepatic steatosis and fibrosis were observed in liver sections of HFC diet-fed hamsters, as in patients with NASH, but they were not seen in normal diet-fed hamsters. Chymase generates angiotensin II and transforming growth factor (TGF)-β, both of which are related to hepatic steatosis and fibrosis, and a significant augmentation of chymase activity was observed in livers from HFC diet-fed hamsters. Both angiotensin II and TGF-β were also significantly increased in livers of HFC diet-fed hamsters. Thus, HFC diet-fed hamsters might develop metabolic syndrome-derived NASH that clinically resembles that in NASH patients.

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.

Acute pancreatitis is still a life-threatening disease without an evidenced therapeutic agent. In this study, the effect of chymase in acute pancreatitis and the possible effect of a chymase inhibitor in acute pancreatitis were investigated. Hamsters were subcutaneously administered 3.0 g/kg of L-arginine to induce acute pancreatitis. Biological markers were measured 1, 2, and 8 h after L-arginine administration. To investigate the effect of a chymase inhibitor, a placebo (saline) or a chymase inhibitor TY-51469 (30 mg/kg) was given 1 h after L-arginine administration. The survival rates were evaluated for 24 h after L-arginine administration. Significant increases in serum lipase levels and pancreatic neutrophil numbers were observed at 1 and 2 h after L-arginine administration, respectively. Significant increases in pancreatic neutrophil numbers were observed in the placebo-treated group, but they were significantly reduced in the TY-51469-treated group. A significant increase in the pancreatic tumor necrosis factor-α mRNA level was observed in the placebo-treated group, but it disappeared in the TY-51469-treated group. Chymase activity significantly increased in the placebo-treated group, but it was significantly reduced by treatment with TY-51469. The survival rate significantly improved in the TY-51469-treated group. A chymase inhibitor may become a novel therapeutic agent for acute pancreatitis.

Background and Aims: Chymotrypsin-like-proteinase of Treponema denticola (Td-CTLP) can stimulate the protein expression and activation of matrix metalloproteinase (MMP)-8 (or collagenase-2), a potent tissue destructive enzyme from gingival cells in vitro. The aims of this study were 1) to demonstrate the proMMP-8 (or latent MMP-8) activation by Td-CTLP in vitro and 2) to detect Td-CTLP and MMP-8 protein levels in the tissue samples of peri-implantitis and periodontitis patients. Materials and Methods: proMMP-8 activation by Td-CTLP was analyzed by immunoblots. Tissue specimens were collected from 38 systemically healthy and non-smoking patients; 14 of whom had moderate to severe periodontitis, 10 of whom were suffering from peri-implantitis, and finally 14 of whom showed no sign of periodontal inflammation nor radiological bone decay (control group). The immune-expression levels of MMP-8 and Td-CTLP in the epithelium and the connective tissue were analyzed immunohistochemically. A pixel color-intensity analyze was performed with ImageJ software (version 1.46c; Rasband WS, National Institutes of Health, Bethesda, MD, USA) to obtain a comparable numeral score for each patient's epithelium and connective tissue MMP-8 and Td-CTLP enzyme level. Results: Td-CTLP activated proMMP-8 in vitro by converting the 70 75 kDa proMMP-8 to 65 kDa active MMP-8. Also, lower molecular size 25 50 kDa parts of MMP-8 were formed. There was no statistically significant difference between the study groups in terms of their MMP-8 and Td-CTLP levels in the epithelium or in the connective tissue. Conclusion: Regarding the limits of this study, it can thus be said that the Td-CTLP enzyme can activate the host proMMP-8 enzyme. Tissue protein levels of MMP-8 and Td-CTLP do not seem to be changed in peri-implantitis and in periodontitis. Turku University Foundation [12198]; Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [BIDEB 2219-1059B191600656] This study was supported by the Turku University Foundation (Grant no: 12198, UKG) and by the Scientific and Technological Research Council of Turkey (Grant no: BIDEB 2219-1059B191600656, GK).