Mast Cell Granules Research Articles

Tryptase in all its states: From allergy to mastocytosis

In normal humans, tryptase, a serine protease with multiple biological activities, is synthesized nearly exclusively by mast cells (MCs). While immature forms of tryptase (α- and β- monomers) are constantly released by MCs and can be measured in the serum of normal individuals as the basal serum tryptase (BST) level, mature tryptases (mostly tetramers of β-tryptase) are retained in the secretory granules of MCs and are released only upon cell activation. Such MC activation occurs during IgE-mediated allergic reactions and increased levels of tryptase, which can be measured immediately after degranulation, are involved in the pathophysiology of immediate hypersensitivity. Interestingly, recent studies have reported that around 5% of the general population present with a genetic trait called hereditary alpha-tryptasemia (HαT). In HαT+ patients, the BST level is increased. Mastocytosis are a group of hematologic neoplasms characterized by an accumulation of atypical MCs in one or several organs/tissues, often accompanied by MC activation. Increased BST level is a hallmark of systemic mastocytosis (SM) and a diagnostic, prognostic and follow-up marker. Interestingly, the incidence of the HαT trait has been found increased in SM patients (up to 18% of the cases) and HαT+ SM patients are more prone to develop anaphylaxis, making HαT a disease penetrance and phenotype modifier.

Internalization of benzylisoquinoline alkaloids by resting and activated bone marrow-derived mast cells utilizes energy-dependent mechanisms

Objective and designDrug delivery to inflammatory cells is dependent upon poorly understood, complex endocytic processes. Berberine (BBR), a benzylisoquinoline alkaloid, binds to heparin and targets glycosaminoglycan-rich granules in mast cells (MC), but the mechanism of BBR internalization is unknown.MethodsBMMC were treated with various concentrations of BBR for different amounts of time and BBR internalization was assessed by flow cytometry and fluorescence microscopy. BMMC were pretreated with endocytic inhibitors or a growth factor (IL-3) prior to BBR exposure to access mechanisms of its internalization.ResultsAfter 24 h, 48 ± 0.8% of BMMC internalized BBR and this process was dependent upon temperature and the presence of glucose in the medium. Methanol fixation reduced BBR internalization, suggesting the involvement of an energy-dependent active transport mechanism. To determine mode of internalization, BBR was encapsulated into Lipofectamine TM lipoplexes since these are known to circumvent classical endocytic pathways. Incorporating BBR into lipoplexes decreased BBR internalization by 26% and 10% (10 μg/ml and 100 μg/ml Lipo-BBR respectively) by BMMC. BBR endocytosis was significantly reduced by Latrunculin B (88%), Cytochalasin B (87%), Chloroquine (86.5%) and 3-methyladenine (91%), indicating that actin polymerization, lysosomal pH and lysosomal self-degradation via the autophagy pathway was involved. In contrast, IL-3 treatment significantly enhanced BBR endocytosis (54% by 40 ng/ml IL-3) suggesting that IL-3 signaling pathways play a role in internalization.ConclusionsOur data suggests that internalization of BBR by resting and IL-3-activated BMMC utilizes an energy-dependent pathway that is dependent upon glucose metabolism and temperature. Furthermore, this process requires actin polymerization and lysosomal trafficking. These data suggest internalization of benzylisoquinoline compounds is an active and complex process.

Comparative Analysis of Orthologous Mast Cell Chymases Active Sites Using Bioinformatics Tools

Mast cells, neutrophils, basophils, natural killer cells, and cytotoxic T cells are among the hematopoietic cell lines originating from immune cells. The importance of mammalian mast cells in innate immunity has piqued the scientific community's interest. cytoplasmic granules of mast cells. Histamine, proteoglycans, proteins, and cytokines are examples of compounds (mediators) that produce mast cell cytoplasmic granules. When external stimuli are received, these granules are released, causing degranulation. Mast cells generate a lot of proteases including chymase, tryptase, and type A carboxypeptidase, among other things. The structure of chymase cma1 was unknown in mice, but it shares 74 percent of its human sequence with chymase CMA1, which was used as a reference. The human CMA1 structure was used to establish and interpret the mouse cma1 structure. Significant residues from the active site, such as catalytic triads and binding residues, were examined. The position of a catalytic triad in human CMA1 chymase and mouse cma1 chymase has been discovered to be similar. Val 175 and Val 197, respectively, replaced two Ala 192 and Gly 214 residues in active site binding residues in target, according to active site residue analysis. We may deduce from this substitution that the cleavage specificity of mouse cma1 chymase varies from that of human CMA1 chymase.

Interplay of collagen and mast cells in periapical granulomas and periapical cysts: a comparative polarizing microscopic and immunohistochemical study.

ObjectivesThis pilot study aimed to establish the interrelationship between collagen and mast cells in periapical granulomas and periapical cysts.Materials and MethodsAn observational cross-sectional study was conducted on the paraffin-embedded tissue sections of 68 specimens (34 periapical granulomas and 34 periapical cysts). The specimens were stained with picrosirius to observe collagen fiber birefringence and anti-tryptase antibody to evaluate the mast cell count immunohistochemically. The mean number and birefringence of collagen fibers, as well as the mean number of mast cells (total, granulated, and degranulated), and the mean inflammatory cell density were calculated. The data obtained were analyzed using the Kruskal Wallis test, Mann Whitney U test, and Spearman correlation test (p < 0.05).ResultsThe mean number of thick collagen fibers was higher in periapical cysts, while that of thin fibers was higher in granulomas (p = 0.00). Cysts emitted orange-yellow to red birefringence, whereas periapical granulomas had predominantly green fibers (p = 0.00). The mean inflammatory cell density was comparable in all groups (p = 0.129). The number of total, degranulated, and granulated mast cells exhibited significant results (p = 0.00) in both groups. Thick cyst fibers showed significant inverse correlations with inflammation and degranulated mast cells (p = 0.041, 0.04 respectively).ConclusionsMast cells and inflammatory cells influenced the nature of collagen fiber formation and its birefringence. This finding may assist in the prediction of the nature, pathogenesis, and biological behavior of periapical lesions.

Granule Leakage Induces Cell-Intrinsic, Granzyme B-Mediated Apoptosis in Mast Cells.

Mast cells are multifunctional immune cells scattered in tissues near blood vessels and mucosal surfaces where they mediate important reactions against parasites and contribute to the pathogenesis of allergic reactions. Serine proteases released from secretory granules upon mast cell activation contribute to these functions by modulating cytokine activity, platelet activation and proteolytic neutralization of toxins. The forced release of granule proteases into the cytosol of mast cells to induce cell suicide has recently been proposed as a therapeutic approach to reduce mast cell numbers in allergic diseases, but the molecular pathways involved in granule-mediated mast cell suicide are incompletely defined. To identify intrinsic granule proteases that can cause mast cell death, we used mice deficient in cytosolic serine protease inhibitors and their respective target proteases. We found that deficiency in Serpinb1a, Serpinb6a, and Serpinb9a or in their target proteases did not alter the kinetics of apoptosis induced by growth factor deprivation in vitro or the number of peritoneal mast cells in vivo. The serine protease cathepsin G induced marginal cell death upon mast cell granule permeabilization only when its inhibitors Serpinb1a or Serpinb6a were deleted. In contrast, the serine protease granzyme B was essential for driving apoptosis in mast cells. On granule permeabilization, granzyme B was required for caspase-3 processing and cell death. Moreover, cytosolic granzyme B inhibitor Serpinb9a prevented caspase-3 processing and mast cell death in a granzyme B-dependent manner. Together, our findings demonstrate that cytosolic serpins provide an inhibitory shield preventing granule protease-induced mast cell apoptosis, and that the granzyme B-Serpinb9a-caspase-3 axis is critical in mast cell survival and could be targeted in the context of allergic diseases.

Impact of preconditioned diabetic stem cells and photobiomodulation on quantity and degranulation of mast cells in a delayed healing wound simulation in type one diabetic rats.

Herein, we report the influence of administering different protocols of preconditioned diabetic adipose-derived mesenchymal stem cells (ADSs) with photobiomodulation in vitro, and photobiomodulation in vivo on the number of mast cells (MCs), their degranulation, and wound strength in the maturation step of a Methicillin-resistant Staphylococcus aureus (MRSA)-infectious wound model in rats with type one diabetes. An MRSA-infectious wound model was generated on diabetic animals, and they were arbitrarily assigned into five groups (G). G1 were control rats. In G2, diabetic ADS were engrafted into the wounds. In G3, diabetic ADS were engrafted into the wound, and the wound was exposed to photobiomodulation (890nm, 890 ± 10nm, 80Hz, 0.2J/cm2) in vivo. In G4, preconditioned diabetic ADS with photobiomodulation (630 and 810nm; each 3 times with 1.2J/cm2) in vitro were engrafted into the wound. In G5, preconditioned diabetic ADS with photobiomodulation were engrafted into the wound, and the wound was exposed to photobiomodulation in vivo. The results showed that, the maximum force in all treatment groups was remarkably greater compared to the control group (all, p = 0.000). Maximum force in G4 and G5 were superior than that other treated groups (both p = 0.000). Moreover, G3, G4, and G5 showed remarkable decreases in completely released MC granules and total numbers of MC compared to G1 and G2 (all, p = 0.000). We concluded that diabetic rats in group 5 showed significantly better results in terms of accelerated wound healing and MC count of an ischemic infected delayed healing wound model.

Solitary cutaneous hemorrhagic bullous mastocytoma: A rare entity

Solitary cutaneous mastocytoma, a clinical type of cutaneous mastocytosis, may present from birth itself as a macule, plaque, nodule, or bulla. It may be associated with pruritus, flushing attacks, or convulsions. The diagnosis of a solitary mastocytoma is made by the presence of a characteristic skin lesion and confirmed by typical histopathological features of mast cell clusters in dermis and subcutaneous tissues, metachromatic staining of mast cell granules with toluidine blue or giemsa staining, and immunohistochemical mast cell marker c-kit/ CD-117 staining. We report a 4-month-old child who presented with a hemorrhagic bulla of left knee. Skin biopsy and immunohistochemistry confirmed the clinical diagnosis of solitary cutaneous mastocytoma. We did not come across any previous report of solitary cutaneous mastocytoma presenting as hemorrhagic bulla.

Racial/Ethnic Variations in Skin Barrier: Implications for Skin Care Recommendations in Skin of Color.

Genetic and environmental factors influence stratum corneum (SC) barrier properties and function. Researchers increasingly focus on biophysical studies that may help clinicians provide their patients with an informed choice on tailormade skincare. This literature review on skin barrier properties comparing different ethnic populations aims to offer insights into the information's clinical relevance. A literature review followed by panel discussions and an online review process aimed to answer the questions: Are there racial/ethnic differences in the SC barrier structure and healthy skin barrier function? Is there a need for specific cleansers and moisturizers? Ethnic categories based on race and ethnicity are often not well defined and inconsistent across different studies. Studies comparing ethnic groups' physical and biochemical skin barrier properties have reported differences in transepidermal water loss (TEWL), skin lipid levels, pH, and mast cell granule size. However, these studies frequently had methodological flaws, mainly were small, and demonstrated conflicting results. The literature suggests racial/ethnic variations in ceramide content, SC structure, and filaggrin mutations. Furthermore, studies have shown a greater burden of pruritus and atopic dermatitis among Black populations. Data on barrier properties in Hispanic/LatinX and South Asian populations are lacking. Robust comparative studies are needed to understand these basic concepts to help tailor skincare and skin of color patients' education. J Drugs Dermatol. 2021;20(9):932-938. doi:10.36849/JDD.6312.

Evaluation of mast cell count in oral and cutaneous lichen planus lesions

Introduction: Lichen planus (LP) is a relatively common chronic mucocutaneous disorder diagnosed based on clinical manifestations and histopathological findings. Mast cells (MCs) are multifunctional immune cells that are involved in the pathogenesis of LP by releasing certain chemical mediators. Objectives: The purpose of this comparative study was to estimate the number of intact (granulated), degranulated and total MCs in oral lichen planus (OLP) and cutaneous lichen planus (CLP) lesions. Patients and Methods: The present descriptive-analytical and cross-sectional study was conducted on 125 LP blocks, including 40 OLP samples and 85 CLP samples. The mean number of granulated, degranulated and total MCs were counted under light microscope (×100 and ×400). Data were analyzed by SPSS version 24 software using Mann-Whitney U and Pearson’s chi-square tests. Results: The mean total MC count was 14.92 ± 3.90 in OLP samples and 14.04 ± 5.60 in CLP samples respectively which was not statistically significant. The mean granulated MC count in CLP (10.53 ± 5.70) was higher than in OLP (4.34 ± 3.46) (P&lt;0.001). The mean degranulated MC count in OLP (10.57 ± 2.99) was higher than in CLP (3.51 ± 2.72) (P&lt;0.001). Conclusion: No statistically significant difference was observed in the total MC count between OLP and CLP; however the difference in the degranulated MC count was detected between OLP and CLP. Despite the homogeneity in the total MC count, the MCs appear to play different pathological roles in OLP and CLP.

Internalization of benzylisoquinoline alkaloids by resting and activated bone marrow-derived mast cells utilizes energy-dependent mechanisms

Abstract Berberine (BBR), a benzylisoquinoline alkaloid, binds to heparin and targets glycosaminoglycan-rich granules of myeloid-derived mast cells, but, the mechanism of berberine’s internalization is poorly understood. Our data showed that 84±3.3% of highly granulated bone marrow-derived mast cells (BMMC) internalized BBR (10 ug/mL) after 45 hr. Methanol fixation completely blocked this process, suggesting an energy-dependent active transport mechanism, and 3-mtheyladenine (600 uM) inhibited internalization by ~43%, indicating that lysosomal self-degradation via the autophagy pathway was involved. BBR incorporation into lipoplexes did not improve BBR internalization, but, rather decreased it by ~30% (1 ug/mL Lipo/BBR; n=3, p&amp;lt;0.05), suggesting that BBR internalization may utilize clathrin-dependent endosomal endocytosis. Interleukin-3 (IL-3)-mediated activation of BMMC augmented BBR internalization (~54% by 40 ng/mL IL-3) in a concentration-dependent manner, further suggesting that clathrin-mediated endocytosis as well as active cell division, have a profound role in BBR internalization. Altogether, our data suggest that internalization of BBR in resting and IL-3 activated BMMC, utilizes clathrin-dependent pathway. Our findings provide important new mechanistic insights into the internalization of benzylsoquinoline compounds by resting and activated mast cells and open new avenues for designing organelle-targeted nanotherapeutics.

Mast cell tryptases in allergic inflammation and immediate hypersensitivity.

Dysregulated mast cell-mediated inflammation and/or activation have been linked to a number of human diseases, including asthma, anaphylaxis, chronic spontaneous urticaria, and mast cell activation syndromes. As a major mast cell granule protein, tryptase is a biomarker commonly used in clinical practice to diagnose mast cell-associated disorders and -mediated reactions, but its mechanistic roles in disease pathogenesis remains incompletely understood. Here, we summarize recent advances in the understanding of human tryptase genetics and the effects that different genetic composition may have on the quaternary structure of tetrameric mature tryptases. We also discuss how these differences may impact clinical phenotypes including allergic inflammation, immediate hypersensitivity, and others seen in patients with mast cell-associated disorders. With the increased application of next-generation sequencing, we foresee that human genetic approaches will be a major focus of understanding human tryptase functions in various human mast cell disorders and in new therapeutic development.

COMPARATIVE STUDY OF HISTOLOGICAL AND HISTOCHEMICAL PROPERTIES OF PERITONEAL MAST CELLS OF ALBINO RAT USING TWO TYPES OF FIXATIVES

Objectives: To make a comparative study of histological and histochemical properties of peritoneal mast cells in albino rat using neutral buffered formalin and formal alcohol as fixatives.&#x0D; Methods: The stretch preparation from Albino rat peritoneum was made on chemically clean glass slides and immediately placed into the fixatives.&#x0D; Results: With toluidine blue (pH 4.4), the mast cells stained deep purple and similar reaction was obtained with toluidine blue at pH 2. These staining reactions indicate the presence of substantial amount of heparin trisulfate, small amount of heparin monosulfate, and neutral mucopolysaccharide.&#x0D; Conclusion: Heparin trisulfate is an active form of heparin and is the main constituent of the mast cell granules of the albino rat.

Mast Cell and Astrocyte Hemichannels and Their Role in Alzheimer's Disease, ALS, and Harmful Stress Conditions.

Considered relevant during allergy responses, numerous observations have also identified mast cells (MCs) as critical effectors during the progression and modulation of several neuroinflammatory conditions, including Alzheimer’s disease (AD) and amyotrophic lateral sclerosis (ALS). MC granules contain a plethora of constituents, including growth factors, cytokines, chemokines, and mitogen factors. The release of these bioactive substances from MCs occurs through distinct pathways that are initiated by the activation of specific plasma membrane receptors/channels. Here, we focus on hemichannels (HCs) formed by connexins (Cxs) and pannexins (Panxs) proteins, and we described their contribution to MC degranulation in AD, ALS, and harmful stress conditions. Cx/Panx HCs are also expressed by astrocytes and are likely involved in the release of critical toxic amounts of soluble factors—such as glutamate, adenosine triphosphate (ATP), complement component 3 derivate C3a, tumor necrosis factor (TNFα), apoliprotein E (ApoE), and certain miRNAs—known to play a role in the pathogenesis of AD, ALS, and other neurodegenerative disorders. We propose that blocking HCs on MCs and glial cells offers a promising novel strategy for ameliorating the progression of neurodegenerative diseases by reducing the release of cytokines and other pro-inflammatory compounds.

Lung Mast Cells Have a High Constitutive Expression of Carboxypeptidase A3 mRNA That Is Independent from Granule-Stored CPA3.

The mast cell granule metalloprotease CPA3 is proposed to have important tissue homeostatic functions. However, the basal CPA3 mRNA and protein expression among mast cell populations has remained poorly investigated. Using a novel histology-based methodology that yields quantitative data on mRNA and protein expression at a single-cell level, the present study maps CPA3 mRNA and protein throughout the MCT and MCTC populations in healthy skin, gut and lung tissues. MCTC cells had both a higher frequency of CPA3 protein-containing cells and a higher protein-staining intensity than the MCT population. Among the tissues, skin MCs had highest CPA3 protein intensity. The expression pattern at the mRNA level was reversed. Lung mast cells had the highest mean CPA3 mRNA staining. Intriguingly, the large alveolar MCT population, that lack CPA3 protein, had uniquely high CPA3 mRNA intensity. A broader multi-tissue RNA analysis confirmed the uniquely high CPA3 mRNA quantities in the lung and corroborated the dissociation between chymase and CPA3 at the mRNA level. Taken together, our novel data suggest a hitherto underestimated contribution of mucosal-like MCT to baseline CPA3 mRNA production. The functional consequence of this high constitutive expression now reveals an important area for further research.

Directional mast cell degranulation of tumor necrosis factor into blood vessels primes neutrophil extravasation

Tissue resident mast cells (MCs) rapidly initiate neutrophil infiltration upon inflammatory insult, yet the molecular mechanism is still unknown. Here, we demonstrated that MC-derived tumor necrosis factor (TNF) was crucial for neutrophil extravasation to sites of contact hypersensitivity-induced skin inflammation by promoting intraluminal crawling. MC-derived TNF directly primed circulating neutrophils via TNF receptor-1 (TNFR1) while being dispensable for endothelial cell activation. The MC-derived TNF was infused into the bloodstream by directional degranulation of perivascular MCs that were part of the vascular unit with access to the vessel lumen. Consistently, intravenous administration of MC granules boosted neutrophil extravasation. Pronounced and rapid intravascular MC degranulation was also observed upon IgE crosslinking or LPs challenge indicating a universal MC potential. Consequently, the directional MC degranulation of pro-inflammatory mediators into the bloodstream may represent an important target for therapeutic approaches aimed at dampening cytokine storm syndromes or shock symptoms, or intentionally pushing immune defense.

Carboxypeptidase inhibition by NvCI suppresses airway hyperreactivity in a mouse asthma model

Carboxypeptidase inhibition by NvCI suppresses airway hyperreactivity in a mouse asthma model

Immunity in Medically Important Parasitic Infections

Immunity is the rule. It is often incomplete and takes many years to develop and fade away quickly. Human life is a battlefield in which we are like soldiers attacked from all sides by bacteria, viruses, fungi and parasites. Our body is bestowed with a defense mechanism in the form of an immune system It has long been recognized that infections with parasites, such as intestinal worms, are often accompanied by blood eosinophilia, and this is due to an immunological process. Conditions in which blood eosinophilia is common include intestinal infections with Ancylostoma duodenale, Ascaris lumbricoides, Trichuristrichiura, various forms of Wuchereria bancroft, Brugiamalayi, loaloa, Dracunculus medinensis, mite infection of the lungs (including at least some cases of tropical eosinophilia);and hydrated disease is due to Echinococcus granulosus. Eosinophilia, in large numbers invades tissues in which antigen-antibody reaction has taken place. They appear to be attracted by some product of the antigen-antibody reaction and it has been shown that if tissues from sensitized guinea -pigs mixed with antigen in vitro, or tissues from guinea-pigs which have died from anaphylaxis, are transferred to the peritoneal cavity of normal guinea-pigs, the recipient develops very marked eosinophilia within 24 hours. The active agent has not been infected, but it is probably not histamine. The eosinophils of rodents are very actively phagocytic, and ingest cellular debris, mast cell granules, etc, but it is not certain whether this is true of eosinophils from other species, nor it is known what functions the eosinophils serve in these reactions. A multitude of defensive mechanisms are involved in parasitic infection. A humoral response develops when parasites invade blood stream (Malaria, Trypanosoma), whereas cell-mediated immunity is elicited by parasites that grow within the tissues (Eg: Cutaneous leishmaniasis). In protozoal infections, IgG, and IgM are produced. In Addition, IgA also produced in intestinal infection. With helminthic infections, IgG, IgM and IgE antibodies are produced.

On the Regulatory Capabilities of Thyroid Mast Cells in Thiamazole Model of Hypothyroidism and Infrared Laser Exposure

The regulatory effect of mast cells on the state of thyroid gland in hypothyroidism and laser therapy remains unclear. Aim: to study the secretory processes of mast cells in relationship with the indicators of functional activity of thyroid gland. Materials and methods. Experimental groups: (55 rats) 1) intact rats, 2) hypothyroidism (thiamazole 25mg/kg) 3) hypothyroidism and 0.5W laser exposure, 4) hypothyroidism and 2.0W laser exposure. Histological samples of the thyroid gland were removed on the 1, 7, and 30 days. Histological sections were stained with toluidine blue. Morphometric data analysis included descriptive statistics and non-parametric tests (Mann Whitney, Spearman correlation coefficient). Results. The increase in the granular saturation of mast cells and the average histochemical coefficient was observed in the hypothyroidism group, the degranulation index increased by day 30. After 0.5 W laser exposure, there was a decrease in the granular content in mast cells and an increase in the degranulation index; the granular saturation increased by day 30. After 2.0 W laser exposure, the content of granules in mast cells decreased on day 1, and on days 7 and 30 it was higher than in the hypothyroidism group; the degranulation index decreased by day 30. The correlation was revealed between the indicators of granule accumulation in a mast cell, the index of mast cell degranulation, the thyroid epithelium height, and relative vascular area. Conclusions. The synthesis processes prevailed over secretion for mastocytes in thiamazole hypothyroidism. 0.5 W laser exposure was more effective for stimulation of the secretory processes in mast cells compared to 2.0 W exposure. The secretory activity of mast cells was associated with the functional activity of thyroid gland, which confirms their regulatory role in tissue repair after thiamazole induced hypothyroidism modeling.

Feline Eosinophilic Keratoconjunctivitis: Nonsteroidal vs Corticosteroid Topical Treatment

Background: Feline eosinophilic keratoconjunctivitis is a proliferative eye lesion of chronic aspect with usually unilateral presentation that may initiate as a superficial vascularization that evolves to a proliferative, granular, irregular lesion of whitish-pink aspect. With its association with an immune-mediated response, nonsteroidal anti-inflammatories do not appear to be efficient, although few studies describe its use. This case report describes a case of a feline eosinophilic keratoconjunctivitis with its clinical evolution since the use of nonsteroidal topical anti-inflammatory drug in an undiagnosed patient and the transition to a topical corticosteroid and cure after 14 days since diagnosis.Case: An 8-year-old female cat was attended at the Veterinary Hospital of the Dom Bosco Catholic University (UCDB), with main complaint being an eye injury with at least 36 days of evolution andunresponsive to treatment (topical tobramycin 0.3% every 12 h / ketorolac trometamol 0.5%/ every 12 h and ophthalmic lubricant/every 4 h). Since the patient had free access to the street, the owners suspected of trauma-induced lesion. At physical examination, it was observed a proliferative lesion at the peri-limbal superotemporal quadrant of the right cornea with approximately 0.4 cm diameter, with color varying of pale to pink, with irregular surface and low vascularity, the adjacent conjunctiva was also affected with similar multiple nodular lesions (0.1 cm). Fluorescein test was negative as well as FIV/FeLV immunochromatography testing. Feline herpesvirus investigation was not possible. The patient was anesthetized and a lesion specimen was acquired with a cotton swab scraping and a fine needle aspiration. Cytology showed predominance of eosinophils and mast cells, with rare corneal epithelial cells, with smear background containing mast cell granules and free eosinophils. Presumptive diagnosis was eosinophilic keratoconjunctivits. After 14 days of topical corticosteroid (prednisolone acetate 1% every 8 h) the patient showed complete remission of the lesions with no relapse in 48 days.Discussion: Misdiagnosis and consequently mistreatment seems a greater prejudice than the risks associated with sample collection of keratoconjunctival proliferative lesions. Due to the lack of cytobrush or cotton swab, apparently, the reported patient was not submitted to ophthalmic cytology due to reluctance of the staff regarding fine needle aspiration of the cornea lesion. Despite a greater risk of iatrogenic trauma with needle aspiration, with eye anatomy well defined, level size and movement amplitude respected, it is unlikely that severe complications could occur. In this case, the undiagnosed patient was submitted to unnecessary 15 days of topical antibiotic and nonsteroidal anti-inflammatory, and no improvement of the clinical signs was observed. Despite non-recommended, few clinical trials as well as case descriptions are available comparing nonsteroidal and corticosteroid treatment of the disease. Once with diagnosis and beginning of topical prednisolone acetate 1% exclusively, the patient showed continuous improvement until complete remission of clinical signs after 14 days. This report reinforces the recommendation of corticosteroid therapy for feline eosinophilic keratoconjunctivitis and the absence of efficacy of nonsteroidal drugs. It also highlights the importance of diagnosis before any medical treatment is considered.

ТУЧНЫЕ КЛЕТКИ В ГОЛОВНОМ МОЗГЕ ПОЗВОНОЧНЫХ – ЛОКАЛИЗАЦИЯ И ФУНКЦИИ

This review focuses on mast cells as resident cells in the central nervous system (CNS) of mammals, birds, reptiles, amphibians, and fish. Mast cell distribution in the brain of different vertebrate species is surveyed in detail. In mammals, they are located most often in the choroid plexus, meninges, thalamus, medial nucleus of habenula, hypothalamus and circumventricular organs, usually in the immediate vicinity of blood vessels and cerebrospinal fluid (CSF)-containing spaces. Their number in brain is unstable, changing during postnatal ontogeny and under the influence of hormonal and immune factors. There are different ways of mediator release from cytoplasmic granules of mast cells, which provide targeted or diffuse effects on surrounding cells. Mast cells express a large number of receptors for immunoglobulins, neurotransmitters and hormones, which makes them highly sensitive to changes in external and internal environments of the body. At the same time, numerous mediators contained in mast cells allow them to induce inflammatory, anti-inflammatory, immuno-, vasculo-, gliocyto- and/or neuromodulating effects, the intensity and direction of which relies on the composition and amount of excreted mediators and the ways of their release, which, in turn, depends on which receptors on mast cells are activated. Mast cells control the permeability of the blood-brain and blood-CSF barriers, contribute to angiogenesis and, along with glial cells, regulate neuroinflammation (which is a leading pathogenetic factor of some nervous system and mental diseases) and protect the CNS from other pathogenic factors. Mast cells in the brain play the role of neuroimmune centers with afferent and efferent functions that link peripheral organs to specialized CNS cells and are actively involved in maintaining CNS homeostasis under both physiological conditions and the influence of pathological factors.