Mast cells promote choroidal neovascularization in a model of age-related macular degeneration.

'Wet' age-related macular degeneration (AMD) is characterized by pathologic choroidal neovascularization (CNV) that destroys central vision. Abundant evidence points to inflammation and immune cell dysfunction in the progression of CNV in AMD. Mast cells are resident immune cells that control the inflammatory response. Mast cells accumulate and degranulate in the choroid of patients with AMD, suggesting they play a role in CNV. Activated mast cells secrete various biologically active mediators, including inflammatory cytokines and proteolytic enzymes such as tryptase. We investigated the role of mast cells in AMD using a model of CNV. Conditioned media from activated mast cells exerts proangiogenic effects on choroidal endothelial cells and choroidal explants. Laser-induced CNV in vivo was markedly attenuated in mice genetically depleted of mast cells (KitW-sh/W-sh) and in wild-type mice treated with mast cell stabilizer, ketotifen fumarate. Tryptase was found to elicit pronounced choroidal endothelial cell sprouting, migration and tubulogenesis; while tryptase inhibition diminished CNV. Transcriptomic analysis of laser-treated RPE/choroid complex revealed collagen catabolism and extracellular matrix (ECM) reorganization as significant events correlated in clusters of mast cell activation. Consistent with these analyses, compared to wildtype mice choroids of laser-treated mast cell-deficient mice displayed less ECM remodelling evaluated using collagen hybridizing peptide tissue binding. Findings herein provide strong support for mast cells as key players in the progression of pathologic choroidal angiogenesis and as potential therapeutic targets to prevent pathological neovascularization in 'wet' AMD.

Sensory neuroimmune interactions at the barrier.

Epithelial barriers such as the skin, lung, and gut, in addition to having unique physiologic functions, are designed to preserve tissue homeostasis upon challenge with a variety of allergens, irritants, or pathogens. Both the innate and adaptive immune systems play a critical role in responding to epithelial cues triggered by environmental stimuli. However, the mechanisms by which organs sense and coordinate complex epithelial, stromal, and immune responses have remained a mystery. Our increasing understanding of the anatomic and functional characteristics of the sensory nervous system is greatly advancing a new field of peripheral neuroimmunology and subsequently changing our understanding of mucosal immunology. Herein, we detail how sensory biology is informing mucosal neuroimmunology, even beyond neuroimmune interactions seen within the central and autonomic nervous systems.

Innate players in Th2 and non-Th2 asthma - emerging roles for the epithelial cell, mast cell and monocyte/macrophage network.

Asthma is one of the most common chronic respiratory diseases and is characterized by airway inflammation, increased mucus production and structural changes in the airways. Recently, there is increasing evidence that the disease is much more heterogeneous than expected, with several distinct asthma endotypes. Based on the specificity of T cells as the best-known driving force in airway inflammation, bronchial asthma is categorized into T helper cell (Th)2 and non-Th2 asthma. The most studied effector cells in Th2 asthma include T cells and eosinophils. In contrast to Th2 asthma, much less is known about the pathophysiology of non-Th2 asthma, which is often associated with treatment resistance. Besides T cells, the interaction of myeloid cells such as monocytes/macrophages and mast cells with the airway epithelium significantly contributes to the pathogenesis of asthma. However, the underlying molecular regulation and particularly the specific relevance of this cellular network in certain asthma endotypes remains to be understood. In this review, we summarize recent findings on the regulation of and complex interplay between epithelial cells and the "non-classical" innate effector cells, mast cells and monocytes/macrophages, in Th2 and non-Th2 asthma with the ultimate goal to provide the rationale for future research into targeted therapy regimens.

Mast Cells Mediate Acute Inflammatory Responses After Glenoid Labral Tears and Can Be Inhibited With Cromolyn in a Rat Model.

BACKGROUND: Injuries to the glenoid labrum have been recognized as a source of joint pain and discomfort, which may be associated with the inflammatory responses that lead to the deterioration of labral tissue. However, it is unclear whether the torn labrum prompts mast cell (MC) activation, resulting in synovial inflammatory responses that lead to labral tissue degeneration. PURPOSE: To determine the potential influence of activated MC on synovial inflammatory responses and subsequent labral tissue degeneration and shoulder function deterioration in a rat model by monitoring MC behavior and sequential inflammatory responses within the synovial tissue and labral tissue after injury, suture repair, and MC stabilizer administration. STUDY DESIGN: Controlled laboratory study. METHODS: Anteroinferior glenoid labral tears were generated in the right shoulder of rats (n = 20) and repaired using a tunneled suture technique. Synovial tissue inflammatory responses were modulated in some rats with intraperitoneal administration of an MC stabilizer-cromolyn (n = 10). At weeks 1 and 3, MC activation, synovial inflammatory responses, and labral degeneration were histologically evaluated. Simultaneously, gait analysis was performed before and after surgical repair to assess the worsening of the shoulder function after the injury and treatment. RESULTS: Resident MC degranulation after labral injury (50.48% ± 8.23% activated at week 1) contributed to the initiation of synovial tissue inflammatory cell recruitment, inflammatory product release, matrix metalloproteinase-13, and subsequent labral tissue extracellular matrix degeneration. The administration of cromolyn, an MC stabilizer, was found to significantly diminish injury-mediated inflammatory responses (inflammatory cell infiltration and subsequent proinflammatory product secretion) and improve shoulder functional recovery. CONCLUSION: MC activation is responsible for labral tear-associated synovial inflammation and labral degeneration. The administration of cromolyn can significantly diminish the cascade of inflammatory reactions after labral injury. CLINICAL RELEVANCE: Our findings support the concept that MC stabilizers may be used as a complementary therapeutic option in the treatment and repair of labral tears.

Long COVID elevated MMP-9 and release from microglia by SARS-CoV-2 Spike protein.

Objective: Long COVID is a major health concern because many patients develop chronic neuropsychiatric symptoms, but the precise pathogenesis is unknown. Matrix metalloproteinase-9 (MMP-9) can disrupt neuronal connectivity and be elevated in patients with long COVID. Methods: In this study, MMP-9 was measured in the serum of long COVID patients and healthy controls, as well as in the supernatant fluid of cultured human microglia cell line stimulated by recombinant severe acute respiratory syndrome coronavirus 2 Spike protein, as well as lipopolysaccharide (LPS) and neurotensin (NT) used as positive controls. MMP-9 was measured by commercial enzyme-linked immunosorbent assay. Results: MMP-9 was significantly elevated in the serum of long COVID patients compared to healthy controls. Moreover, there was significant release of MMP-9 from a cultured human microglia cell line stimulated by LPS, NT, or Spike protein. We further show that pretreatment with the flavonoids luteolin and tetramethoxyluteolin (methlut) significantly inhibited the release of MMP-9 stimulated by the Spike protein. Conclusion: MMP-9 from Spike protein-stimulated microglia could contribute to the development of long COVID and may serve as a target for treatment including the use of luteolin.

DNA Methylation Negatively Regulates Gene Expression of Key Cytokines Secreted by BMMCs Recognizing FMDV-VLPs.

Virus-like particles (VLPs) have been studied and used as vaccines to control foot-and-mouth disease (FMD). Mast cells (MCs) express various pattern recognition receptors that recognize pathogens and secrete numerous cytokines to initiate and modulate immune responses. Our previous study showed that bone marrow-derived mast cells (BMMCs) can recognize foot-and-mouth disease virus-like particles (FMDV-VLPs) to differentially express various cytokines and that histone acetylation can regulate the cytokines secreted during BMMC recognition of FMDV-VLPs. To demonstrate the role of DNA methylation in this response process, BMMCs that recognize FMDV-VLPs were treated with azacytidine (5-AZA), an inhibitor of DNA methylation transferase. We prepared FMDV-VLPs as described previously and cultured the BMMCs. The transcription and expression of key cytokines and transcription factors were determined using real-time quantitative PCR (RT-qPCR) and Western blotting. Results showed that pre-treatment with AZA resulted in the increased transcription and expression of tumor necrosis factor α (TNF-α), interleukin (IL)-6, IL-13, and IL-10, while the changes in IL-13 transcription and IL-6 expression were irrelevant to mannose receptors (MRs). Furthermore, analysis of the transcription factors indicated that both the transcription and expression of nuclear factor-kappa B (NF-κB) increased significantly in the AZA pre-treated group, indicating that DNA methylation may also regulate NF-κB expression to modulate TNF-α, IL-13, and IL-6. However, pre-treatment with AZA did not alter the expression of microphthalmia-associated transcription factor (MITF) or GATA-2. All the data demonstrate that DNA methylation negatively regulates the transcription and expression of TNF-α, IL-13, IL-10, and IL-6 secreted by recognizing FMDV-VLPs. These results provide new ideas for the mast cell-based design of more effective vaccine adjuvants and targeted therapies in the future.

Differential MRGPRX2-dependent activation of human mast cells by polymyxins and octapeptins.

The emergence of multi-drug resistant Gram-negative bacteria has led to renewed interest in the antimicrobial activity of polymyxins and novel polymyxin analogues (e.g. nonapeptides and octapeptin). In some individuals, clinically used polymyxins can cause acute hypersensitivity reactions through mast cell activation, with a recent study attributing this effect to activation of the MAS-related G protein-coupled receptor X2 (MRGPRX2). In the present study, HEK293 cells expressing human MRGPRX2 and the human mast cell line LAD2 were used to characterize the activity of the broader family of polymyxins. Octapeptin C4, polymyxin B and colistin produced concentration-dependent calcium mobilization, degranulation, and CCL-2 (MCP-1) release in LAD2 mast cells, with the former being highly potent. CRISPR-Cas9 knockdown of MRGPRX2 in LAD2 cells and a MRGPRX2 inverse agonist caused a significant reduction in calcium mobilization, degranulation, and CCL-2 release, demonstrating dependency on MRGPRX2 expression. In contrast, polymyxin nonapeptides were far less potent calcium mobilisers and failed to induce functional degranulation in LAD2 cells. Our results confirm that activation of mast cells induced by polymyxin-related antibiotics is MRGPRX2-dependent and reveal that octapeptin C4 might be more liable, whilst nonapeptides are less liable, to trigger immediate hypersensitivity reactions clinically. The mechanism underpinning the difference in MRGPRX2 activation between polymyxin-related antibiotics is important to better understand as it may help design new, safer polymyxins and guide the optimal clinical use of existing polymyxin drugs.

Significance of Immune and Non-Immune Cell Stroma as a Microenvironment of Hepatocellular Carcinoma-From Inflammation to Hepatocellular Carcinoma Progression.

Hepatocellular carcinoma (HCC) is the most common liver cancer as well as the most prevalent cause of death in the adult patient population with cirrhosis. The occurrence of HCC is primarily caused by chronic liver inflammation that might occur because of a viral infection, non-alcoholic fatty liver disease (NAFLD), or various lifestyle-associated factors. The objective of this review was to summarize the current knowledge regarding the microenvironment of HCC, indicating how immune- and non-immune-cell stroma might affect the onset and progression of HCC. Therefore, in the following narrative review, we described the role of tumor-infiltrating neutrophils, bone-marrow-derived cells, tumor-associated mast cells, cancer-associated fibroblasts, tumor-associated macrophages, liver-sinusoidal endothelial cells, lymphocytes, and certain cytokines in liver inflammation and the further progression to HCC. A better understanding of the HCC microenvironment might be crucial to introducing novel treatment strategies or combined therapies that could lead to more effective clinical outcomes.

TRESK channel activation ameliorates migraine-like pain via modulation of CGRP release from the trigeminovascular system and meningeal mast cells in experimental migraine models.

AIMS: Accumulating evidence indicates the involvement of TRESK potassium channels in migraine, however, effects of TRESK activation on migraine-related mechanisms remain unclear. We explored effects of TRESK channel modulation on migraine-related behavioral and molecular markers in in-vivo and ex-vivo rat models of migraine. MAIN METHODS: The selective TRESK activator cloxyquin at different doses, the TRESK inhibitor A2764, and the migraine drug sumatriptan were tested alone or in different combinations in nitroglycerin (NTG)-induced in-vivo model, and in ex-vivo meningeal, trigeminal ganglion and brainstem preparations in which CGRP release was induced by capsaicin. Mechanical allodynia, CGRP and c-fos levels in trigeminovascular structures and meningeal mast cells were evaluated. KEY FINDINGS: Cloxyquin attenuated NTG-induced mechanical allodynia, brainstem c-fos and CGRP levels, trigeminal ganglion CGRP levels and meningeal mast cell degranulation and number, in-vivo. It also diminished capsaicin-induced CGRP release from ex-vivo meningeal, trigeminal ganglion and brainstem preparations. Specific TRESK inhibitor A2764 abolished all effects of cloxyquin in in-vivo and ex-vivo. Combining cloxyquin and sumatriptan exerted a synergistic effect ex-vivo, but not in-vivo. SIGNIFICANCE: Our findings provide the experimental evidence for the anti-migraine effect of TRESK activation in migraine-like conditions. The modulation of TRESK channels may therefore be an attractive alternative strategy to relieve migraine pain.

Rapidly Trading Down Depression's 3 Pillars to 5HT3-Receptors Through ECT or Psilocybin?

Depression astonishingly can be stopped instantly by electrotherapies or through some psychedelics like psilocybin. In explaining this, the traditional approaches to their antidepressant effects via "reset" models and orthosteric serotonin receptors has neglected the only serotonin channel 5HT3, which e.g. has emerged as being helpful for the neurotrophic translation for all anti-depressants and final synaptic effects. Psychedelics here are confronted with a panorama of also anti-depressant 5HT3-channels and a search for their part e.g. in the "3 pillars" reigning depression. Of these M1) mitochondria, parasitic organelles from a fusion between some proto-bacteria and archae, founding eukaryotes, also through 5HT3 in depression determine much of its somatic crises. Two further pillars, "pushback" and "shame-link", are clarified by the parasympathetic (PS-) conspiciously 5HT3-rich "nasal" pterygo-palatine ganglion (PPG): PPG-1.) Intramural "pushbacks" intoxicating brain's tissues, show up on MRI e.g. along branches of the peri-/subcallosal artery. The brain-draining circular chambers, by CIMURAF, are plausibly driven by the PPG (and other PS-ganglia) through their dense nitrergic grid, causing loose wrung areas creating hyperboloid stenoses where they delimit contracted sliding segments PPG-2.) Existential conflicts trigger last-resort attacks, whereby the subduing are stopped into submissive shame. This plausibly occurs via the antidromic "Suzuki-link" from preparatory attack-biting (V3) via the trigeminal ggl. V3-V2-crosstalk onto the PPG, which, blushing via PACAP, maybe via MCs opens the BBB causing foggy confusion. Mushrooms may have acquired psilocybin to similarly stop feeding moves of worms (C. elegans) via the >100 5HT3-like ion channels. While on MOD-1 serotonin elicits "dwelling", collective feeding on just one fungus, psilocin could on promote audacious "roaming" (protecting fungi) - channel LGC-50 learning from this. The biphasic and pervasive H2S, being a dipole, might be flushed by ECT and on the 5HT3-receptors might get worms (and us) to move.

Amphotericin B for injection triggers degranulation of human LAD2 mast cells by MRGPRX2 and pseudo-allergic reactions in mice via MRGPRB2 activation.

Amphotericin B, a polyene macrolide antifungal agent, still plays an important role in the management of serious systemic fungal infections. Amphotericin B deoxycholate (AmBd) has been used to treat invasive fungal infections for over 60 years and remains the primary clinical formulation currently available. Anaphylactoid reactions triggered by AmBd in the clinic have been documented. However, the molecular and cellular events contributing to these reactions have not been clearly elucidated to date. This study demonstrates that the human Mas-related G protein-coupled receptor X2 (MRGPRX2) is the receptor that mediates these anaphylactoid responses. Molecular docking and cellular thermal shift assay (CETSA) indicate that AmBd exhibits potential affinity with MRGPRX2. In vitro, exposure to AmBd results in significant release of LAD2 mast cell granules and induces intracellular Ca2+ mobilization as well as activation of PLC-γ/IP3R and PI3K/AKT signaling pathways. However, these phenomena are reduced in MRGPRX2-knockdown LAD2 cells. In vivo, AmBd triggers paw swelling and a rapid drop in core body temperature in wild-type (WT) mice. However, these reactions are almost absent in MRGPRB2 (the mouse homolog of MRGPRX2) knockout mice (MRGPRB2MUT, MUT). The above results suggest that AmBd activates PLC-γ/IP3R and PI3K/AKT signaling via MRGPRX2 (in human LAD2 mast cells) or MRGPRB2 (in mice), leading to the release of mast cell granules and subsequent triggering of pseudo-allergic reactions. Taken together, this study clarifies the role of MRGPRX2 in triggering pseudo-allergic reactions to AmBd and suggests that MRGPRX2 could be a potential therapeutic target for controlling these reactions.

Dynamin 2-mediated endocytosis of BLT1 is required for IL-8 production in HMC-1 cells induced by Trichomonas vaginalis-derived secretory products.

We previously reported that leukotriene B4 (LTB4) contained in Trichomonas vaginalis-derived secretory products (TvSP) play an essential role in interleukin-8 (IL-8) production in human mast cell line (HMC-1 cells) via LTB4 receptor (BLT)-mediated Nuclear Factor-kappa B (NF-кB) activation. Dynamin, a GTPase, has been known to be involved in endocytosis of receptors for signaling of production of cytokine or chemokines. In the present study, we investigated the role of dynamin-mediated BLT1 endocytosis in TvSP-induced IL-8 production. When HMC-1 cells were transfected with BLT1 or BLT2 siRNA, TvSP-induced IL-8 production was significantly inhibited compared with that in cells transfected with control siRNA. In addition, pretreatment of HMC-1 cells with a dynamin inhibitor (Dynasore) reduced IL-8 production induced by TvSP or LTB4. TvSP- or LTB4- induced phosphorylation of NF-кB was also attenuated by pretreatment with Dynasore. After exposing HMC-1 cells to TvSP or LTB4, BLT1 was translocated from the intracellular compartments to the plasma membrane within 30 min. At 60 min after stimulation with TvSP or LTB4, BLT1 remigrated from the cell surface to intracellular areas. Pretreatment of HMC-1 cells with dynamin-2 siRNA blocked internalization of BLT1 induced by TvSP or LTB4. Co-immunoprecipitation experiments revealed that dynamin-2 strongly interacted with BLT1 60 min after stimulation with TvSP or LTB4. These results suggest that T. vaginalis-secreted LTB4 induces IL-8 production in HMC-1 cells via dynamin 2-mediated endocytosis of BLT1 and phosphorylation of NF-кB.

Emerging trends and research hotspots in the relationship between mast cells and atopic dermatitis based on the literature from 2001 to 2024: A bibliometric and visualized analysis.

BACKGROUND: Atopic dermatitis (AD) is a prevalent chronic inflammatory and highly pruritic skin condition characterized by the infiltration of immune cells, notably eosinophils and mast cells. Mast cells (MCs) critically participate in the complex pathogenesis of AD through multiple pathways and have recently garnered growing attention in research. Despite the abundance of related studies published over the years, a comprehensive bibliometric analysis on this topic remains lacking. OBJECTIVE: Our objective was to perform an up-to-date bibliometric analysis of the literature focusing on the relationship between MCs and AD. This analysis would provide valuable insights through a thorough bibliometric review, enabling a clearer understanding of the current research landscape, pinpointing key studies, and detecting emerging trends within this field. METHODS: We searched the Web of Science Core Collection (WoSCC) database on 15 July 2024. The data retrieval strategy was structured as follows: #1: TS = ("mast cells") OR TS = ("mast cell") OR TS = ("mastocyte"); #2: TS = ("atopic dermatitis") OR TS = ("atopic eczema") Final data: (#1 AND #2). A total of 2272 items published between 2001 and 2024 were included. Several scientometric visualization tools, including VOSviewer, R-bibliometrix, CiteSpace and an online analytical platform, were utilized to conduct text mining and to visualize the bibliometric data, facilitating a comprehensive analysis of research trends and patterns. RESULTS: Out of the initial 2272 articles retrieved, 2168 were selected for analysis after applying inclusion and exclusion criteria based on publication type. The findings indicate a steady and substantial exponential growth in the annual number of publications focused on the relationship between over the years. The South Korea (547/2168), USA (465/2168) and Japan (436/2168) were the major contributors within this field, collectively constituting more than half of the total publications. To clarify the underlying mechanisms and role of MCs in the pathogenesis of AD and to make MCs prime targets for therapeutic intervention have garnered the most attention in this field. According to references analysis, the research emphasis has shifted to developing MC-related therapeutics and intervention and regulating the immune system of AD patients through modulating the activity of various immune cells. On the basis of keywords analysis, we outlined the following research frontiers and hotpots in the future: the role of oxidative stress in the pathogenesis; imbalance in the different types of T helper (Th) cells during immune response; skin barrier and barrier dysfunction; improving quality of life; sensory neurons; biological agents and small-molecule drugs. Furthermore, IL-13, IL-4, NFKB1, BCGF-1 and CD4 ranked as the top five genes that have received the most investigative attention in the intersection of MCs and AD. CONCLUSION: In a word, this analysis would greatly benefit from a thorough bibliometric review to gain a deeper understanding of the current research landscape, identify pivotal studies and pinpoint emerging trends in the field of MCs and AD. Meanwhile, our findings offered researchers a holistic perspective of ongoing developments, serving as a valuable resource for guiding future research and informing decision-making for both researchers and policymakers in this area.

Airway tryptase levels inform the lack of clinical efficacy of the tryptase inhibitor MTPS9579A in asthma.

BACKGROUND: Tryptase, a mast cell protease, has been identified as a potential therapeutic target in managing patients with refractory asthma. We assessed the efficacy, safety, pharmacokinetics, and pharmacodynamics of MTPS9579A, an anti-tryptase antibody, in a phase 2a randomized trial for patients with uncontrolled asthma and a phase 1c trial to understand activity within the lower respiratory tract. METHODS: Phase 2a patients (n = 134) received 1800 mg MTPS9579A or placebo intravenously every 4 weeks for 48 weeks. The primary endpoint was time to the first composite exacerbation event. Phase 1c patients (n = 27) received one intravenous dose of 300 or 1800 mg MTPS9579A or placebo. Both trials measured MTPS9579A concentrations and effects on tryptase in serum and nasal lining fluid; phase 1c also analyzed bronchial lining fluid. RESULTS: MTPS9579A did not meet the primary endpoint (hazard ratio = 0.90; 95% CI: 0.55-1.47; p = 0.6835); exacerbation rates in the placebo group were low. Serum and nasal MTPS9579A pharmacokinetics and tryptase levels were consistent with data from healthy volunteers. However, in phase 1c patients, compared to nasal levels, MTPS9579A bronchial concentrations were 6.8-fold lower, and bronchial active and total tryptase levels were higher (119-fold and 30-fold, respectively). Pharmacokinetic/pharmacodynamic modeling predicted intravenous doses of 3800 mg every 4 weeks would be necessary to achieve 95% active tryptase inhibition from baseline. CONCLUSIONS: The MTPS9579A dose tested in the phase 2a study was insufficient to inhibit tryptase in bronchial lining fluid, likely contributing to the observed lack of efficacy.

Solitary Cutaneous Mastocytoma in an Adult Diagnosed on Cytology: A Rare Case Report.

Mastocytosis is characterized by the proliferation of neoplastic mast cells in various organs, which can have either cutaneous or systemic presentation. Solitary cutaneous mastocytomas are most commonly seen in the pediatric age group but rarely present in adults. Histopathology of cutaneous mastocytoma is well described in the literature but only a few studies are available describing the cytomorphological features. We present a case of a 19-year-old female who presented with a 6-month history of a right supraclavicular single, 0.5 × 0.5 cm, well-defined, reddish-brown round nodule. The fine needle aspiration cytology (FNAC) smears were highly cellular showing monomorphic cells, predominantly dispersed singly and occasionally in small clusters. The cells were round to oval, with moderate cytoplasm containing coarse metachromatic granules. Toluidine blue stain and CD117 immunocytochemical stain confirmed the presence of mast cell granules. Based on the cytomorphology, staining, clinical history, and examination, a diagnosis of solitary cutaneous mastocytoma was rendered. FNAC plays a pivotal role in diagnosing mast cell tumors and even obviates the need for tissue biopsy in selected cases.

The Complement System Is Essential for Arteriogenesis by Enhancing Sterile Inflammation as a Relevant Step in Collateral Artery Growth.

Arteriogenesis is an inflammatory driven mechanism, describing the growth of a natural bypass from pre-existing collateral arteries to compensate for an occluded artery. The complement system component C3 is a potent natural inflammatory activator. Here, we investigated its impact on the process of collateral artery growth using C3-deficient (C3 -/-) and wildtype control mice in a murine hindlimb model of arteriogenesis. Induction of arteriogenesis by unilateral femoral artery ligation resulted in decreased perfusion recovery in C3 -/- mice on day 7 as shown by Laser Doppler imaging. Immunofluorescence staining revealed a reduced vascular cell proliferation in C3 -/- mice. Gene expression analysis displayed a significant reduction in monocyte chemoattractant protein-1 (MCP-1) expression in C3 -/- mice. Interestingly, 3 days after induction of arteriogenesis, the number of macrophages (CD68+) recruited to growing collaterals was not affected by C3 deficiency. However, a significant reduction in inflammatory M1-like polarized macrophages (CD68+/MRC1-) was noted. Forced mast cell activation by Compound 48/80 as well as exogenous MCP-1 application rescued the number of M1-like polarized macrophages along with perfusion recovery in C3 -/- mice. In summary, this study demonstrates that complement C3 influences arteriogenesis by mediating MCP-1 expression, which is essential for the induction and enhancement of sterile inflammation.

The Contribution of Mast Cells to the Regulation of Elastic Fiber Tensometry in the Skin Dermis of Children with Marfan Syndrome.

Marfan syndrome (MFS) is a hereditary condition accompanied by disorders in the structural and regulatory properties of connective tissue, including elastic fibers, due to a mutation in the gene encodes for fibrillin-1 protein (FBN1 gene) and the synthesis of abnormal fibrillin-1 glycoprotein. Despite the high potential of mast cells (MCs) to remodel the extracellular matrix (ECM), their pathogenetic significance in MFS has not been considered yet. The group of patients with Marfan syndrome included two mothers and five children (three girls aged 4, 11, and 11 and two boys aged 12 and 13). Normal skin was examined in two children aged 11 and 12. Histochemical, monoplex, and multiplex immunohistochemical techniques; combined protocols of simultaneous histochemical and immunohistochemical staining (the results of staining were assessed using light, epifluorescence, and confocal microscopy); and bioinformatics algorithms for the quantitative analysis of detected targets were used to evaluate mast cells and their relationship with other cells from extracellular structures in the skin dermis. Analysis of the skin MC population in children with Marfan syndrome revealed a considerably increased number of intra-organic populations with the preservation of the specific Tryptase+Chymase+CPA3+ protease profile typical of the skin. The features of the MC histotopography phenotype in MFS consisted of closer colocalization with elastic fibers, smooth muscle cells, and fibroblasts. MCs formed many intradermal clusters that synchronized the activity of cell functions in the stromal landscape of the tissue microenvironment with the help of spatial architectonics, including the formation of cell chains and the creation of fibrous niches. In MCs, the expression of specific proteases, TGF-ß, and heparin increased, with targeted secretion of biologically active substances relative to the dermal elastic fibers, which had specific structural features in MFS, including abnormal variability in thickness along their entire length, alternating thickened and thinned areas, and uneven surface topography. This paper discusses the potential role of MCs in strain analysis (tensometry) of the tissue microenvironment in MFS. Thus, the quantitative and qualitative rearrangements of the skin MC population in MFS are aimed at altering the stromal landscape of the connective tissue. The results obtained should be taken into account when managing clinical signs of MFS manifested in other pathogenetically critical structures of internal organs, including the aorta, tendons, cartilage, and parenchymal organs.

Immunohistochemical Analysis of CD117 in the Mast Cells of Odontogenic Keratocysts.

BACKGROUND: Odontogenic lesions contain mast cells (MCs), particularly those with a cystic appearance. Because of their high recurrence rates and aggressive clinical behaviour, odontogenic keratocysts (OKCs) require special treatment. A particular kind of protein called cluster of differentiation (CD) 117/ receptor tyrosine kinase (c-KIT) is present on the surface of many cells. Most hematopoietic cells lose their expression of KIT during the differentiation process, with the exception of MCs, which continue to express KIT throughout their lifetime. AIM: Using the CD117 immunomarker, this immunohistochemical investigation sought to assess the presence and location of MCs in OKCs and examine the relationship between MC numbers in sporadic, syndromic, and recurrent OKCs. METHODS: The study comprised 30 paraffin-embedded tissue specimens, and a histopathological diagnosis was made from hematoxylin and eosin-stained sections with a thickness of 4-5 µ. Out of 30 specimens, 21 were sporadic, six were recurrent OKCs, and three were syndrome-associated OKCs. CD-117/c-kit rabbit polyclonal primary antibody was used to stain the sections for observing MCs, which were then viewed under a light microscope with a digital camera and a desktop computer with MICAPS software for viewing images. RESULT: To compare the number of MCs among OKCs, a one-way ANOVA test was used. Our study revealed that a statistically significant increase in MCs has been observed in the subepithelial and deep connective tissue of recurrent OKC (p < 0.05). However, a comparison of the mean MC value among three OKC subtypes did not reveal any statistically significant differences. An increased mast count was observed in the deep connective tissue layer of syndromic OKC under multiple comparisons. CONCLUSION: Our study concluded that MCs were present in increased numbers both in the superficial and deep connective tissue of recurrent OKCs, indicative of their aggressive clinical behaviour. Increased mean MC counts observed in some of the sporadic cases may be an indicator of their chances of recurrence in the future.

Photobiological response of mast cells to green and red light-emitting diodes (LEDs) in cutaneous burns.

This study assessed the effects of red and green LEDs on mast cells (MCs) in third-degree burns in 75 Wistar rats, divided into control, red LED (RED), and green LED (GREEN) groups. Animals were irradiated daily with RED (630 nm, 300 mW, 0.779 W/cm2, 9 J/cm2, 30 s) and GREEN (520 nm, 180 mW, 0.467 W/cm2, 60 J/cm2, 30 s). Histological sections stained with toluidine blue were analyzed for total and subtype MCs. Standardized MC counting was performed across the viable lesion area, considering lesion margins, through intact connective tissue and the integrity of skin appendages. No statistically significant differences in MCs 2 (with released granules and intact cell border) were found between groups. Irradiated groups showed increased total MCs at 7, 14, and 21 days (p < 0.05), with a decrease in MCs 1 (intact MCs) at all time points compared to control (p < 0.05). Significant changes in MCs 3 (with massive degranulation and partial or complete disintegration of the cell border) degranulation were noted in RED at 7, 14, and 21 days (p < 0.009) and in GREEN at 14 (p < 0.009) and 32 days (p < 0.028). Results suggest red and green LEDs modulate MC recruitment and degranulation in third-degree burns.