Mast cells in human choroid and their role in age-related macular degeneration (AMD).

The role of mast cells in physiologic and pathological processes extends far beyond the allergy processes: they are involved in wound healing, chronic inflammation, and tumor growth. This short article emphasizes the role played by mast cells in age-related macular degeneration (AMD). Mast cells can induce angiogenesis and are present around Bruch's membrane during the early and late stages of choroidal neovascularization in AMD. Proteolytic enzymes released by mast cells lead to thinning of the choroid in AMD as well as degradation of vascular basement membranes and Bruch's membrane, which in turn could result in retinal pigment epithelial death and choriocapillaris degeneration in geographical atrophy and exudative AMD.

Therapeutic modulation of KIT ligand in melanocytic disorders with implications for mast cell diseases.

KIT ligand and its associated receptor KIT serve as a master regulatory system for both melanocytes and mast cells controlling survival, migration, proliferation and activation. Blockade of this pathway results in cell depletion, while overactivation leads to mastocytosis or melanoma. Expression defects are associated with pigmentary and mast cell disorders. KIT ligand regulation is complex but efficient targeting of this system would be of significant benefit to those suffering from melanocytic or mast cell disorders. Herein, we review the known associations of this pathway with cutaneous diseases and the regulators of this system both in skin and in the more well-studied germ cell system. Exogenous agents modulating this pathway will also be presented. Ultimately, we will review potential therapeutic opportunities to help our patients with melanocytic and mast cell disease processes potentially including vitiligo, hair greying, melasma, urticaria, mastocytosis and melanoma.

Validation of mitochondrial biomarkers and immune dynamics in polycystic ovary syndrome.

PROBLEM: Polycystic ovary syndrome (PCOS), a prevalent endocrine-metabolic disorder, presents considerable therapeutic challenges due to its complex and elusive pathophysiology. METHOD OF STUDY: We employed three machine learning algorithms to identify potential biomarkers within a training dataset, comprising GSE138518, GSE155489, and GSE193123. The diagnostic accuracy of these biomarkers was rigorously evaluated using a validation dataset using area under the curve (AUC) metrics. Further validation in clinical samples was conducted using PCR and immunofluorescence techniques. Additionally, we investigate the complex interplay among immune cells in PCOS using CIBERSORT to uncover the relationships between the identified biomarkers and various immune cell types. RESULTS: Our analysis identified ACSS2, LPIN1, and NR4A1 as key mitochondria-related biomarkers associated with PCOS. A notable difference was observed in the immune microenvironment between PCOS patients and healthy controls. In particular, LPIN1 exhibited a positive correlation with resting mast cells, whereas NR4A1 demonstrated a negative correlation with monocytes in PCOS patients. CONCLUSION: ACSS2, LPIN1, and NR4A1 emerge as PCOS-related diagnostic biomarkers and potential intervention targets, opening new avenues for the diagnosis and management of PCOS.

Mast Cells in the Microenvironment of Hepatocellular Carcinoma Confer Favorable Prognosis: A Retrospective Study using QuPath Image Analysis Software.

The insights provided by in-situ detection of immune cells within hepatocellular carcinoma (HCC) might present information on patient outcomes. Studies investigating the expression and localization of immune cells within tumor tissues are associated with several challenges, including a lack of precise annotation for tumor regions and random selection of microscopic fields of view. QuPath is an open-source, user-friendly software that could meet the growing need for digital pathology in whole-slide image (WSI) analysis. The infiltration of HCC and adjacent tissues by CD1a+ immature dendritic cells (iDCs), CD117+ mast cells, and NKp46+ natural killer cells (NKs) cells was assessed immunohistochemically in representative specimens of 67 patients with HCC who underwent curative resection. The area fraction (AF) of positively stained cells was assessed automatically in WSIs using QuPath in the tumor center (TC), inner margin (IM), outer margin (OM), and peritumor (PT) area. The prognostic significance of immune cells was evaluated for time to recurrence (TTR), disease-free survival (DFS), and overall survival (OS). The AF of mast cells was significantly greater than the AF of NKs, and the AF of iDCs was significantly lower compared to NKs in each region of interest. High AFs of mast cells in the IM and PT areas were associated with longer DFS. In addition, high AF of mast cells in IM was associated with longer OS. Computer-assisted analysis using this software is a suitable tool for obtaining prognostic information for tumor-infiltrating immune cells (iDCs, mast cells, and NKs) in different regions of HCC after resection. Mast cells displayed the greatest AF in all regions of interest (ROIs). Mast cells in the peritumor region and IM showed a positive prognostic significance.

Xin-Yi-Qing-Fei-Tang and its critical components reduce asthma symptoms by suppressing GM-CSF and COX-2 expression in RBL-2H3 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: The traditional Chinese medicine (TCM) XYQFT is composed of 10 herbs. According to the NHIRD, XYQFT is one of the top ten most commonly used TCM prescriptions for asthma treatment. AIM OF THE STUDY: The aim of this study was to explore whether XYQFT reduces asthma symptoms in a mouse model of chronic asthma and determine the immunomodulatory mechanism of mast cells. MATERIALS AND METHODS: BALB/c mice were intratracheally (it) stimulated with 40 µL (2.5 µg/µL) of Dermatophagoides pteronyssinus (Der p) once a week for 6 consecutive weeks and orally administered XYQFT at 1 g/kg 30 min before Der p stimulation. Airway hypersensitivity, inflammatory cells in the BALF and total IgE in the blood were assessed in mice. In addition, RBL-2H3 cells (mast cells) were stimulated with DNP-IgE, after which different concentrations of XYQFT were added for 30 min to evaluate the effect of XYQFT on the gene expression and degranulation of DNP-stimulated RBL-2H3 cells. After the compounds in XYQFT were identified using LC‒MS/MS, the PBD method was used to identify the chemical components that inhibited the expression of the GM-CSF and COX-2 genes in mast cells. RESULTS: The airway hypersensitivity assay demonstrated that XYQFT significantly alleviated Der p-induced airway hypersensitivity. Moreover, cell counting and typing of bronchoalveolar lavage fluid revealed a significant reduction in Der p-induced inflammatory cell infiltration with XYQFT treatment. ELISA examination further indicated a significant decrease in Der p-induced total IgE levels in serum following XYQFT administration. In addition, XYQFT inhibited the degranulation and expression of genes (IL-3, IL-4, ALOX-5, IL-13, GM-CSF, COX-2, TNF-α, and MCP-1) in RBL-2H3 cells after DNP stimulation. The compounds timosaponin AIII and genkwanin in XYQFT were found to be key factors in the inhibition of COX-2 and GM-CSF gene expression in mast cells. CONCLUSION: By regulating mast cells, XYQFT inhibited inflammatory cell infiltration, airway hypersensitivity and specific immunity in a mouse model of asthma. In addition, XYQFT synergistically inhibited the expression of the GM-CSF and COX-2 genes in mast cells through timosaponin AIII and genkwanin.

High Intraepithelial Mast Cell Density in Warthin's Tumor.

BACKGROUND/AIM: Warthin's tumor, the second most frequent neoplasia of the parotid gland, is characterized by a proliferation of both epithelial and lymphoid components. In addition to epithelial and lymphoid cells, various other cell types are implicated to varying degrees in the immune response. Notably, mast cells have long been recognized as a consistent cell population within this tumor. Despite the historical acknowledgment of mast cell presence, their true distribution and significance within Warthin's tumor remain unclear. In this study, we aimed to elucidate the distribution and significance of mast cells in Warthin's tumor. MATERIALS AND METHODS: Histochemical and immunohistochemical methods were employed for the evaluation of mast cells within tumor specimens. RESULTS: Our study revealed a notable concentration of mast cells in the epithelial component of Warthin's tumor. Microscopic examination showed predominant lymphoid and epithelial elements with occasional cystic formations. Immunohistochemical analysis identified mast cells in both components, emphasizing their role in the tumor microenvironment. Double immunostaining (mast cell tryptase and CD34) revealed no significant correlation between mast cells and blood vessels. Intraepithelial mast cells (IEMCs) had a significantly higher density in the epithelial component, suggesting a potential association with the tumor's benign nature. The relationship between IEMCs and epithelial cells, especially in the presence of cystic structures, offers valuable insights into the unique features of Warthin's tumor. CONCLUSION: Our study contributes to the understanding of mast cells in Warthin's tumor, highlighting a substantial concentration within the epithelial component. This knowledge may pave the way for further investigations into the roles of mast cells in the pathogenesis and treatment of Warthin's tumor.

Bienzyme-Locked Activatable Fluorescent Probes for Specific Imaging of Tumor-Associated Mast Cells.

Tumor-associated mast cells (TAMCs) have been recently revealed to play a multifaceted role in the tumor microenvironment. Noninvasive optical imaging of TAMCs is thus highly desired to gain insights into their functions in cancer immunotherapy. However, due to the lack of a single enzyme that is specific to mast cells, a common probe design approach based on single-enzyme activation is not applicable. Herein, we reported a bienzyme-locked molecular probe (THCMC) based on a photoinduced electron transfer-intramolecular charge-transfer hybrid strategy for in vivo imaging of TAMCs. The bienzyme-locked activation mechanism ensures that THCMC exclusively turns on near-infrared (NIR) fluorescence only in the presence of both tryptase and chymase specifically coexpressed by mast cells. Thus, THCMC effectively distinguishes mast cells from other leukocytes, including T cells, neutrophils, and macrophages, a capability lacking in single-locked probes. Such a high specificity of THCMC allows noninvasive tracking of the fluctuation of TAMCs in the tumor of living mice during cancer immunotherapy. The results reveal that the decreased intratumoral signal of THCMC after combination immunotherapy correlates well with the reduced population of TAMCs, accurately predicting the inhibition of tumor growth. Thus, this study not only presents the first NIR fluorescent probe specific for TAMCs but also proposes a generic bienzyme-locked probe design approach for in vivo cell imaging.

Mast cells in meningiomas.

Meningioma represents the most frequent tumor of the central nervous system (CNS). Correlations between the presence of mast cells (MCs) and grade or other histological features of meningioma are still debated. Our study aimed to better understand the relationship between mast cells and meningiomas and to compare our results based on specific histological subtypes and novel 2021 CNS WHO grading system. We observed some differences as regards the number of MCs and meningioma grade. In low-grade (grade 1) meningiomas, MCs were observed in 7/22 cases, while they were consistently present in all eight high-grade cases (grade 2 and grade  3). Among the grade 1 meningiomas, we observed two "low-positive", two "intermediate-positive", and three "high-positive" cases. Among the group of high-grade meningiomas, the six cases grade 2 were considered as "low-positive", while the two grade 3 cases showed a higher number of MCs and were included in the "intermediate-positive" group. Even though with no statistical significance, due to the low number of cases, our results seem to confirm a sort of relationship between meningioma grading and the number of MCs, as demonstrated by the higher percentage of high-grade meningiomas showing MCs infiltrates, compared to low-grade meningiomas.

Recruitment or activation of mast cells in the liver aggravates the accumulation of fibrosis in carbon tetrachloride-induced liver injury.

Liver diseases caused by viral infections, alcoholism, drugs, or chemical poisons are a significant health problem: Liver diseases are a leading contributor to mortality, with approximately 2 million deaths per year worldwide. Liver fibrosis, as a common liver disease characterized by excessive collagen deposition, is associated with high morbidity and mortality, and there is no effective treatment. Numerous studies have shown that the accumulation of mast cells (MCs) in the liver is closely associated with liver injury caused by a variety of factors. This study investigated the relationship between MCs and carbon tetrachloride (CCl4)-induced liver fibrosis in rats and the effects of the MC stabilizers sodium cromoglycate (SGC) and ketotifen (KET) on CCl4-induced liver fibrosis. The results showed that MCs were recruited or activated during CCl4-induced liver fibrosis. Coadministration of SCG or KET alleviated the liver fibrosis by decreasing SCF/c-kit expression, inhibiting the TGF-ß1/Smad2/3 pathway, depressing the HIF-1a/VEGF pathway, activating Nrf2/HO-1 pathway, and increasing the hepatic levels of GSH, GSH-Px, and GR, thereby reducing hepatic oxidative stress. Collectively, recruitment or activation of MCs is linked to liver fibrosis and the stabilization of MCs may provide a new approach to the prevention of liver fibrosis.

Immunohistochemical staining with CD117 and PGP9.5 of excised vestibular tissue from patients with neuroproliferative vestibulodynia.

BACKGROUND: Neuroproliferative vestibulodynia (NPV), a provoked genital pain characterized by severe allodynia and hyperalgesia, is confirmed in excised vestibular tissue by immunohistochemical staining (>8 CD117-positive immunostained cells/100× microscopic field) rather than by hematoxylin and eosin staining. AIM: In this study we sought to assess immunostaining of tissue samples obtained during vestibulectomy surgery and to correlate results with patient outcomes. METHODS: Patients (n = 65) meeting criteria for NPV who underwent vestibulectomy during the period from June 2019 through December 2022 formed the study cohort. We performed assessment of pathology of vestibular tissues by use of immunohistochemical staining, including quantitation of mast cells by CD117 (mast cell marker) and nerve fibers by protein gene product (PGP) 9.5 (neuronal marker). We analyzed 725 photomicrographs of immunostained tissue sections (100× and 200×) by manual counting and computer-assisted histometry and correlated these data to clinical assessments. OUTCOMES: Outcomes included density of CD117 and PGP9.5 immunostaining in the 1:00-11:00 o'clock and 12:00 o'clock vestibular regions, and patient-reported outcomes assessing sexual function, pain, distress, and symptom improvement. RESULTS: All 65 NPV patients (median age 26 years), 45 with lifelong and 20 with acquired NPV, had severe pain documented by PROs and vulvoscopy and had >8 CD117-immunopositive cells/100× microscopic field. Median cell count values were similar in the 1:00-11:00 o'clock and 12:00 vestibular regions (28.5 and 29.5/100× field, respectively). Likewise, the marker) and nerve fibers by protein gene product (PGP) 9.5 (neuronal marker). We analyzed 725 photomicrographs of immunostained tissue sections (100× and 200×) by manual counting and computer-assisted histometry and correlated these data to clinical assessments. OUTCOMES: Outcomes included density of CD117 and PGP9.5 immunostaining in the 1:00-11:00 o'clock and 12:00 o'clock vestibular regions, and patient-reported outcomes assessing sexual function, pain, distress, and symptom improvement. RESULTS: All 65 NPV patients (median age 26 years), 45 with lifelong and 20 with acquired NPV, had severe pain documented by PROs and vulvoscopy and had >8 CD117-immunopositive cells/100× microscopic field. Median cell count values were similar in the 1:00-11:00 o'clock and 12:00 vestibular regions (28.5 and 29.5/100× field, respectively). Likewise, the median area of CD117 immunostaining was similar in both regions (0.69% and 0.73%). The median area of PGP9.5 immunostaining was 0.47% and 0.31% in these same regions. Pain scores determined with cotton-tipped swab testing were nominally higher in lifelong vs acquired NPV patients, reaching statistical significance in the 1:00-11:00 o'clock region (P < .001). The median score for the McGill Pain Questionnaire affective subscale dimension was also significantly higher in lifelong vs acquired NPV patients (P = .011). No correlations were observed between hematoxylin and eosin results and density of mast cells or neuronal markers. Of note, 63% of the patient cohort reported having additional conditions associated with aberrant mast cell activity. CLINICAL IMPLICATIONS: The pathology of NPV is primarily localized to the vestibular epithelial basement membrane and subepithelial stroma with no visible vulvoscopic findings, making clinical diagnosis challenging. STRENGTHS AND LIMITATIONS: Strengths of this study include the large number of tissues examined with what is to our knowledge the first-ever assessment of the 12:00 vestibule. Major limitations are specimens from a single timepoint within the disease state and lack of control tissues. CONCLUSIONS: Performing immunohistochemical staining of excised vestibular tissue with CD117 and PGP9.5 led to histometric confirmation of NPV, indications that NPV is a field disease involving all vestibular regions, validation for patients whose pain had been ignored and who had experienced negative psychosocial impact, and appreciation that such staining can advance knowledge.

IL-10 Differentially Promotes Mast Cell Responsiveness to IL-33, Resulting in Enhancement of Type 2 Inflammation and Suppression of Neutrophilia.

Mast cells (MCs) play critical roles in the establishment of allergic diseases. We recently demonstrated an unexpected, proinflammatory role for IL-10 in regulating MC responses. IL-10 enhanced MC activation and promoted IgE-dependent responses during food allergy. However, whether these effects extend to IgE-independent stimuli is not clear. In this article, we demonstrate that IL-10 plays a critical role in driving IL-33-mediated MC responses. IL-10 stimulation enhanced MC expansion and degranulation, ST2 expression, IL-13 production, and phospho-relA upregulation in IL-33-treated cells while suppressing TNF-α. These effects were partly dependent on endogenous IL-10 and further amplified in MCs coactivated with both IL-33 and IgE/Ag. IL-10's divergent effects also extended in vivo. In a MC-dependent model of IL-33-induced neutrophilia, IL-10 treatment enhanced MC responsiveness, leading to suppression of neutrophils and decreased TNF-α. In contrast, during IL-33-induced type 2 inflammation, IL-10 priming exacerbated MC activity, resulting in MC recruitment to various tissues, enhanced ST2 expression, induction of hypothermia, recruitment of eosinophils, and increased MCPT-1 and IL-13 levels. Our data elucidate an important role for IL-10 as an augmenter of IL-33-mediated MC responses, with implications during both allergic diseases and other MC-dependent disorders. IL-10 induction is routinely used as a prognostic marker of disease improvement. Our data suggest instead that IL-10 can enhance ST2 responsiveness in IL-33-activated MCs, with the potential to both aggravate or suppress disease severity depending on the inflammatory context.

Expression of CD25, mast cell markers and T-cell markers in eosinophilic esophagitis.

While eosinophilic esophagitis (EOE) is defined by histologic presence of eosinophils, a few studies have established the presence of mast cells in EOE and even shown their correlation with symptom persistence despite resolution of eosinophils. Expression of aberrant mast cell markers CD25 and CD2 have not been studied in EOE. This study quantifies the number of hotspot cells per high power field expressing CKIT/CD117, tryptase, CD25, CD2 and CD3 by immunohistochemical stains in endoscopic esophageal biopsies of the following three cohorts: (1) established and histologically confirmed EOE, (2) suspected EOE with biopsies negative for eosinophils, and (3) no history of or suspicion for EOE with histologically unremarkable biopsies. In this study, mast cells were highlighted by CKIT and tryptase in EOE, and not seen in other clinically mimicking cases. There were also significantly higher densities of CD25 and pan-T-cell marker staining in EOE cases. These findings suggest an inflammatory cellular milieu in EOE, beyond just eosinophils, that can be demonstrated by immunohistochemistry, and that invite further study into the role that these cells may play in EOE.

Impact of TNF and IL-33 Cytokines on Mast Cells in Neuroinflammation.

Mast cells (MCs) are derived from hematopoietic progenitors, mature in vascularized tissues, and participate in innate and acquired immunity. Neuroinflammation is a highly debated topic in the biomedical literature; however, the impact of tumor necrosis factor (TNF) and IL-33 on MCs in the brain has not been widely addressed. MCs can be activated by IgE binding to FcεRI, as well as by different antigens. After activation, MCs mediate various immunological and inflammatory responses through TNF and IL-33. TNF has two receptors: TNFR1, a p55 molecule, and TNFR2, a p75 molecule. This cytokine is the only one of its kind to be stored in the granules of MCs and can also be generated by de novo synthesis via mRNA. In the central nervous system (CNS), TNF is produced almost exclusively by microglial cells, neurons, astrocytes, and, minimally, by endothelial cells. After its release into brain tissue, TNF rapidly induces the adhesion molecules endothelial leukocyte adhesion molecule 1 (ELAM-1), intercellular adhesion molecule 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1) in endothelial cells. TNF causes the chemoattraction of neutrophils by inducing several molecules, including CXC chemokines (IL-8). Both MCs and microglial cells act as a primary barrier against foreign molecules in the CNS, producing pro-inflammatory cytokines such as IL-33. IL-33 belongs to the IL-1 family, is activated through the ST2L/IL1-RAcP receptor complex, and mediates both the innate and adaptive immune response. IL-33 is a nuclear transcription factor expressed in the brain, where it induces pro-inflammatory cytokines (TNF and IL-1) and chemokines (CCL2, CCL3, CCL5, and CXCL10). Therefore, MCs and microglia in the CNS are a source of pro-inflammatory cytokines, including TNF and IL-33, that mediate many brain diseases. The inhibition of TNF and IL-33 may represent a new therapeutic approach that could complement existing neuroinflammatory therapies.

PGR-KITLG signaling drives a tumor-mast cell regulatory feedback to modulate apoptosis of breast cancer cells.

The immune microenvironment constructed by tumor-infiltrating immune cells and the molecular phenotype defined by hormone receptors (HRs) have been implicated as decisive factors in the regulation of breast cancer (BC) progression. Here, we found that the infiltration of mast cells (MCs) informed impaired prognoses in HR(+) BC but predicted improved prognoses in HR(-) BC. However, molecular features of MCs in different BC remain unclear. We next discovered that HR(-) BC cells were prone to apoptosis under the stimulation of MCs, whereas HR(+) BC cells exerted anti-apoptotic effects. Mechanistically, in HR(+) BC, the KIT ligand (KITLG), a major mast cell growth factor in recruiting and activating MCs, could be transcriptionally upregulated by the progesterone receptor (PGR), and elevate the production of MC-derived granulin (GRN). GRN attenuates TNFα-induced apoptosis in BC cells by competitively binding to TNFR1. Furthermore, disruption of PGR-KITLG signaling by knocking down PGR or using the specific KITLG-cKIT inhibitor iSCK03 potently enhanced the sensitivity of HR(+) BC cells to MC-induced apoptosis and exerted anti-tumor activity. Collectively, these results demonstrate that PGR-KITLG signaling in BC cells preferentially induces GRN expression in MCs to exert anti-apoptotic effects, with potential value in developing precision medicine approaches for diagnosis and treatment.

The effect of myeloablative radiation on urinary bladder mast cells.

Radiation-induced cystitis is an inflammatory condition affecting the urinary bladder, which can develop as a side effect of abdominopelvic radiotherapy, specifically external-beam radiation therapy or myeloablative radiotherapy. A possible involvement of mast cells in the pathophysiology of radiation-induced cystitis has been indicated in cases of external-beam radiation therapy; however, there is no evidence that these findings apply to the myeloablative aetiology. As such, this study investigated potential changes to urinary bladder mast cell prevalence when exposed to myeloablative radiation. Lethally irradiated C57BL/6J mice that received donor rescue bone marrow cells exhibited an increased mast cell frequency amongst host leukocytes 1 week following irradiation. By 4 weeks, no significant difference in either frequency or cell density was observed. However mast cell diameter was smaller, and a significant increase in mast cell number in the adventitia was observed. This study highlights that mast cells constitute a significant portion of the remaining host leukocyte population following radiation exposure, with changes to mast cell distribution and decreased cell diameter four weeks following radiation-induced injury.

Mast cell distribution and prevalence in the murine urinary bladder.

BACKGROUND: Mast cells have been implicated in the pathology of various urinary bladder disorders. However, the distribution of mast cells throughout urinary bladder tissue remains uncertain despite mast cell prevalence being relatively well-defined. Using a mouse tissue model, this study aims to characterise the prevalence and distribution of mast cells throughout the urinary bladder. METHODS: Bladder tissues were collected from six C57BL/6J female mice. Mast cell prevalence was quantified by flow cytometry, based on the expression of the following characteristic markers: CD45, CD117 and FcɛRIα. The toluidine blue stain assessed mast cell distribution, size, and proximity to vasculature. A repeated measures one-way ANOVA was used to evaluate the density of mast cells between the discrete layers of the urinary bladder, and an ordinary one-way ANOVA was used to assess potential differences between mast cell size across the urinary bladder wall. RESULTS: It was determined that mast cells compose less than 4% of all live leukocytes in the urinary bladder. They were also found to be more prominent in the lamina propria and detrusor muscle layers, compared to the urothelium and adventitia. In addition, 20.89% of mast cells were located near vasculature, which may be an important factor in consideration of their function and potential to contribute to various bladder pathologies, such as cystitis or overactive bladder. CONCLUSION: These findings provide a baseline understanding of mast cell prevalence and distribution throughout the urinary bladder.

Effective in vitro evaluation of the risk of histamine release related to valemetostat tosylate using MRGPRX2-expressing cells.

Mas-related G-protein-coupled receptor X2 (MRGPRX2), expressed on mast cells, is associated with drug-induced pseudo-allergic reactions. Although it is well known that there are differences of sensitivity between species in the pseudo-allergic reactions, no platform for evaluating a human risk of the pseudo-allergic reactions observed in nonclinical studies has been established. Valemetostat tosylate, developed as an anti-cancer drug, induced histamine release in a nonclinical study with dogs. The purpose of the current study was to identify the mechanism and assess the human risk of valemetostat-tosylate-induced histamine release using dog and human MRGPRX2-expressing cells. In an experiment with human or dog MRGPRX2-expressing cells, valemetostat tosylate caused activation of human and dog MRGPRX2. Importantly, the EC50 for dog MRGPRX2 was consistent with the Cmax value at which histamine release was observed in dogs. Furthermore, the EC50 for human MRGPRX2 was ca. 27-fold higher than that for dog MRGPRX2, indicating a species difference in histamine-releasing activity. In a clinical trial, histamine release was not observed in patients receiving valemetostat tosylate. In conclusion, an in vitro assay using human and animal MRGPRX2-expressing cells would be an effective platform to investigate the mechanism and predict the human risk of histamine release observed in nonclinical studies.

Intracranial invasion of a mast cell tumour in a dog: A case report and review of the literature.

An 11-year-old, female-neutered beagle was presented with a growing soft tissue mass arising within the deep tissues of the left cranial cervical region. At presentation, facial asymmetry was evident along with palpable lymphadenomegaly. Magnetic resonance imaging demonstrated a locally invasive cervical mass with intracranial invasion through focal osteolysis of the occipital bone. After antihistamine administration, cytology confirmed mast cell tumour (MCT) with metastasis to local lymph nodes and liver. The owner chose to pursue lomustine and prednisolone, which were dispensed, but, before home administration, prolonged seizures/status epilepticus occurred prompting euthanasia. Postmortem examination confirmed a high-grade MCT associated with, and infiltrating through, muscle, calvarium, dura mata, leptomeninges and the underlying brain. We present the clinical, imaging, and pathological findings of an unprecedented case of extracranial MCT tumour causing osteolysis of an imperforate flat bone (occipital bone) and intracranial invasion.

Effect of moxibustion on colonic low-grade inflammatory response in rats with diarrhea-predominant irritable bowel syndrome based on mast cell degranulation. / åŸºäºŽè‚¥å¤§ç»†èƒžè„±é¢—ç²’æŽ¢è®¨è‰¾ç¸å¯¹è ¹æ³»åž‹è‚ æ˜“æ¿€ç»¼åˆå¾å¤§é¼ ç»“è‚ ä½Žåº¦ç‚Žæ€§ååº”çš„å½±å“.

OBJECTIVES: To observe the effects of moxibustion on colonic mast cell degranulation and inflammatory factor expression in rats with diarrhea-predominant irritable bowel syndrome (IBS-D), and explore the potential mechanism of moxibustion in treating IBS-D. METHODS: Forty-five rat pups born from 5 healthy SPF-grade pregnant SD rats, with 8 rats were randomly selected as the normal group. The remaining 37 rats were intervened with maternal separation, acetic acid enema, and chronic restraint stress to establish the IBS-D model. The successfully modeled 32 rats were then randomly assigned to a model group, a ketotifen group, a moxibustion group, and a moxibustion-medication group, with 8 rats in each group. The rats in the ketotifen group were intervened with intragastric administration of ketotifen solution (10 mL/kg); the rats in the moxibustion group were intervened with suspended moxibustion on bilateral "Tianshu" (ST 25) and "Shangjuxu" (ST 37); the rats in the moxibustion-medication group were intervened with suspended moxibustion combined with intragastric administration of ketotifen solution. All interventions were administered once daily for 7 consecutive days. The diarrhea rate and minimum volume threshold of abdominal withdrawal reflex (AWR) were calculated before and after modeling, as well as after intervention. After intervention, colonic tissue morphology was observed using HE staining; colonic mucosal ultrastructure was examined by scanning electron microscopy; colonic mast cell ultrastructure was observed using transmission electron microscopy; mast cell degranulation was assessed by toluidine blue staining; serum and colonic levels of histamine, interleukin (IL)-1ß, IL-6, IL-1α, trypsin-like enzyme, and protease-activated receptor 2 (PAR-2) were measured by ELISA; the Western blot and real-time quantitative PCR were employed to evaluate the protein and mRNA expression of colonic IL-1ß, IL-6, IL-1α, trypsin-like enzyme, and PAR-2; the immunofluorescence was used to detect the positive expression of histamine, IL-1ß, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 in the colonic tissue. RESULTS: Compared to the normal group, the rats in the model group exhibited extensive infiltration of inflammatory cells in colonic tissue, severe damage to the colonic mucosa, disordered arrangement of villi, reduced electron density, and a significant decrease in granule quantity within mast cells. The diarrhea rate and mast cell degranulation rate were increased (P<0.01), AWR minimum volume threshold was decreased (P<0.01); the serum and colonic levels of histamine, IL-1ß, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 were elevated (P<0.01); the positive expression of histamine, as well as protein, mRNA and positive expression of IL-1ß, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 in the colon were all elevated (P<0.01). Compared to the model group, the rats in the ketotifen group, the moxibustion group, and the moxibustion-medication group exhibited significantly reduced infiltration of inflammatory cells in colonic tissue, relatively intact colonic mucosa, orderly arranged villi, increased electron density, and an augmented number of mast cell granules; the diarrhea rate and mast cell degranulation rate were decreased (P<0.01), and AWR minimum volume threshold was increased (P<0.01); the serum and colonic levels of histamine, IL-1ß, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 were reduced (P<0.01); the positive expression of histamine, as well as protein, mRNA and positive expression of IL-1ß, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 in the colon were all decreased (P<0.01). Compared to the ketotifen group, the moxibustion group showed decreased serum levels of histamine, IL-6, and trypsin-like enzyme (P<0.01, P<0.05), as well as reduced colonic levels of IL-1ß and IL-6 (P<0.01, P<0.05); the protein expression of colonic IL-1ß, IL-1α, and PAR-2 was reduced (P<0.05), and the positive expression of colonic IL-1ß and trypsin-like enzyme was reduced (P<0.01, P<0.05). Compared to both the ketotifen group and the moxibustion group, the moxibustion-medication group exhibited decreased diarrhea rate and mast cell degranulation rate (P<0.01), an increased AWR minimum volume threshold (P<0.01), reduced serum and colonic levels of histamine, IL-1ß, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 (P<0.01), decreased protein expression of colonic IL-1ß, trypsin-like enzyme, and PAR-2 (P<0.01, P<0.05), reduced mRNA and positive expression of colonic IL-1ß, IL-6, IL-1α, trypsin-like enzyme, and PAR-2 (P<0.01, P<0.05), and decreased positive expression of colonic histamine (P<0.01). CONCLUSIONS: Moxibustion on "Tianshu" (ST 25) and "Shangjuxu" (ST 37) might inhibit low-grade inflammatory reactions in the colon of IBS-D model rats. The mechanism may be related to the inhibition of histamine and trypsin-like enzyme secreted by mast cell, thereby reducing the expression of related inflammatory factors.