Thrombopoietin inhibits murine mast cell differentiation

MRGPRX2 signaling involves the Lysyl-tRNA synthetase and MITF pathway

MRGPRX2, a G-protein-coupled-seven transmembrane domain receptor, is mainly expressed in mast cells and neurons and is involved in skin immunity and pain. It is implicated in the pathophysiology of non-IgE-mediated immediate hypersensitivity and has been related to adverse drug reactions. Moreover, a role has been proposed in asthma, atopic dermatitis, contact dermatitis, and chronic spontaneous urticaria. Although it has a prominent role in disease, its signaling transduction is poorly understood. This study shows that MRGPRX2 activation with substance P increased Lysyl t-RNA synthetase (LysRS) translocation to the nucleus. LysRS is a moonlighting protein with a dual role in protein translation and IgE signaling in mast cells. Upon allergen- IgE-FcεRI crosslinking, LysRS is translocated to the nucleus and activates microphthalmia-associated transcription factor (MITF) activity. In this study, we found that MRGPRX2 triggering led to MITF phosphorylation and increased MITF activity. Therefore, overexpression of LysRS increased MITF activity after MRGPRX2 activation. MITF silencing reduced MRGPRX2-dependent calcium influx and mast cell degranulation. Furthermore, a MITF pathway inhibitor, ML329, impaired MITF expression, calcium influx, and mast cell degranulation. Moreover, drugs such as atracurium, vancomycin, and morphine, reported to induce MRGPRX2-dependent degranulation, increased MITF activity. Altogether, our data show that MRGPRX2 signaling enhances MITF activity, and its abrogation by silencing or inhibition resulted in defective MRGPRX2 degranulation. We conclude that MRGPRX2 signaling involves the LysRS and MITF pathway. Thus, MITF and MITF-dependent targets may be considered therapeutic approaches to treat pathologies where MRGPRX2 is implicated.

Biomolecules and Cardiovascular Diseases in Women

Although cardiovascular diseases (CVD) are the leading cause of non-communicable diseases-dependent death worldwide, their effects are still largely underestimated in women [...].

Prognostic Value of High-Sensitivity Cardiac Troponin in Women

High-sensitivity cardiac troponin assays have become the gold standard for diagnosing acute and chronic myocardial injury. The detection of troponin levels beyond the 99th percentile is included in the fourth universal definition of myocardial infarction, specifically recommending the use of sex-specific thresholds. Measurable concentrations below the proposed diagnostic thresholds have been shown to inform prognosis in different categories of inpatients and outpatients. However, clinical investigations from the last twenty years have yielded conflicting results regarding the incremental value of using different cut-offs for men and women. While advocates of a sex-specific approach claim it may help reduce gender bias in cardiovascular medicine, particularly in acute coronary syndromes, other groups question the alleged incremental diagnostic and prognostic value of sex-specific thresholds, ultimately asserting that less is more. In the present review, we aimed to synthesize our current understanding of sex-based differences in cardiac troponin levels and to reappraise the available evidence with regard to (i) the prognostic significance of sex-specific diagnostic thresholds of high-sensitivity cardiac troponin assays compared to common cut-offs in both men and women undergoing cardiovascular disease risk assessment, and (ii) the clinical utility of high-sensitivity cardiac troponin assays for cardiovascular disease prevention in women.

CD244 expression represents functional decline of murine hematopoietic stem cells after in vitro culture

Isolation of long-term hematopoietic stem cell (HSC) is possible by utilizing flow cytometry with multiple cell surface markers. However, those cell surface phenotypes do not represent functional HSCs after in vitro culture. Here we show that cultured HSCs express mast cell-related genes including Cd244. After in vitro culture, phenotypic HSCs were divided into CD244^- and CD244⁺ subpopulations, and only CD244^- cells that have low mast cell gene expression and maintain HSC-related genes sustain reconstitution potential. The result was same when HSCs were cultured in an efficient expansion medium containing polyvinyl alcohol. Chemically induced endoplasmic reticulum (ER) stress signal increased the CD244⁺ subpopulation, whereas ER stress suppression using a molecular chaperone, TUDCA, decreased CD244⁺ population, which was correlated to improved reconstitution output. These data suggest CD244 is a potent marker to exclude non-functional HSCs after in vitro culture thereby useful to elucidate mechanism of functional decline of HSCs during ex vivo treatment.

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Murine HSCs up-regulate mast cell-related genes including Cd244 during in vitro culture

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Long-term HSCs after in vitro culture are enriched in CD244⁻CD48⁻KSL population

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Induction of unfolded protein response is involved in the increase of CD244⁺HSC

Resveratrol Enhances the Cytotoxic Activity of Lymphocytes from Menopausal Women

Nutraceuticals and functional foods are the main sources of antioxidants and have positive effects on health through regulation of the redox balance. Accordingly, they represent a useful nutritional source for the prevention of noncommunicable diseases (NCDs). Menopausal women have an increased risk of developing NCDs due to hormonal dysregulation and the ongoing aging process. Accordingly, a healthy lifestyle and good nutritional habits are of utmost importance in this population. Resveratrol (RSV) is a natural polyphenol, and it is used as a nutraceutical given its estrogenic, anti-inflammatory, and antioxidant properties. The aim of this study was to analyze the effects of RSV on the lymphocyte cytotoxicity in menopausal women. Lymphocytes from 13 healthy menopausal women (56.18 ± 4.24 years) were isolated, and then cocultured with hTERT-HME1, a breast cell line with a precancerous phenotype. The results showed that, when treated with RSV, lymphocytes significantly increased the TNF-α production (p < 0.001), the formation of immune synapses (p = 0.009), and the target cell lysis (p = 0.002). No effects were detected in the lymphocyte total antioxidant capacity. In conclusion, RSV might enhance the immune surveillance in menopausal women by increasing the cytotoxic activity of lymphocytes.

The underestimated role of the microphthalmia-associated transcription factor (MiTF) in normal and pathological haematopoiesis

Haematopoiesis, the process by which a restrained population of stem cells terminally differentiates into specific types of blood cells, depends on the tightly regulated temporospatial activity of several transcription factors (TFs). The deregulation of their activity or expression is a main cause of pathological haematopoiesis, leading to bone marrow failure (BMF), anaemia and leukaemia. TFs can be induced and/or activated by different stimuli, to which they respond by regulating the expression of genes and gene networks. Most TFs are highly pleiotropic; i.e., they are capable of influencing two or more apparently unrelated phenotypic traits, and the action of a single TF in a specific setting often depends on its interaction with other TFs and signalling pathway components. The microphthalmia-associated TF (MiTF) is a prototype TF in multiple situations. MiTF has been described extensively as a key regulator of melanocyte and melanoma development because it acts mainly as an oncogene. Mitf-mutated mice show a plethora of pleiotropic phenotypes, such as microphthalmia, deafness, abnormal pigmentation, retinal degeneration, reduced mast cell numbers and osteopetrosis, revealing a greater requirement for MiTF activity in cells and tissue. A growing amount of evidence has led to the delineation of key roles for MiTF in haematopoiesis and/or in cells of haematopoietic origin, including haematopoietic stem cells, mast cells, NK cells, basophiles, B cells and osteoclasts. This review summarizes several roles of MiTF in cells of the haematopoietic system and how MiTFs can impact BM development.

Decellularized Extracellular Matrices and Cardiac Differentiation: Study on Human Amniotic Fluid-Stem Cells

Cell therapy with a variety of stem populations is increasingly being investigated as a promising regenerative strategy for cardiovascular (CV) diseases. Their combination with adequate scaffolds represents an improved therapeutic approach. Recently, several biomaterials were investigated as scaffolds for CV tissue repair, with decellularized extracellular matrices (dECMs) arousing increasing interest for cardiac tissue engineering applications. The aim of this study was to analyze whether dECMs support the cardiac differentiation of CardiopoieticAF stem cells. These perinatal stem cells, which can be easily isolated without ethical or safety limitations, display a high cardiac differentiative potential. Differentiation was previously achieved by culturing them on Matrigel, but this 3D scaffold is not transplantable. The identification of a new transplantable scaffold able to support CardiopoieticAF stem cell cardiac differentiation is pivotal prior to encouraging translation of in vitro studies in animal model preclinical investigations. Our data demonstrated that decellularized extracellular matrices already used in cardiac surgery (the porcine CorTMPATCH and the equine MatrixPatchTM) can efficiently support the proliferation and cardiac differentiation of CardiopoieticAF stem cells and represent a useful cellular scaffold to be transplanted with stem cells in animal hosts.

Gingival Response to Dental Implant: Comparison Study on the Effects of New Nanopored Laser-Treated vs. Traditional Healing Abutments

The health of peri-implant soft tissues is important for the long-term success rate of dental implants and the surface topography is pivotal in influencing it. Thus, the aim of this study was to evaluate, in human patients, the inflammatory mucosal microenvironment in the tissue surrounding a new, nanoscale, laser-treated healing abutment characterized by engineered nanopores versus a standard machined-surface. Analyses of anti- and pro-inflammatory markers, cytokeratins, desmosomal proteins and scanning electron microscopy were performed in 30 soft-tissue biopsies retrieved during second-stage surgery. The results demonstrate that the soft tissue surrounding the laser-treated surface was characterized by a lower grade of inflammation than the one facing the machined-surface, which, in turn, showed a disrupted epithelium and altered desmosomes. Moreover, higher adhesion of the epithelial cells on the laser-treated surface was detected compared to the machined one. In conclusion, the laser-treated surface topography seems to play an important role not only in cell adhesion, but also on the inflammatory makers’ expression of the soft tissue microenvironment. Thus, from a clinical point of view, the use of this kind of topography may be of crucial importance not only on healing abutments but also on prosthetic ones.

Effect of Physical Exercise on the Release of Microparticles with Angiogenic Potential

Cellular communication has a fundamental role in both human physiological and pathological states and various mechanisms are involved in the crosstalk between organs. Among these, microparticles (MPs) have an important involvement. MPs are a subtype of extracellular vesicles produced by a variety of cells following activation or apoptosis. They are normally present in physiological conditions, but their concentration varies in pathological states such as cardiovascular disease, diabetes mellitus, or cancer. Acute and chronic physical exercise are able to modify MPs amounts as well. Among various actions, exercise-responsive MPs affect angiogenesis, the process through which new blood vessels grow from pre-existing vessels. Usually, the neo vascular growth has functional role; but an aberrant neovascularization accompanies several oncogenic, ischemic, or inflammatory diseases. In addition, angiogenesis is one of the key adaptations to physical exercise and training. In the present review, we report evidence regarding the effect of various typologies of exercise on circulating MPs that are able to affect angiogenesis.

Epigenetic Features of Human Perinatal Stem Cells Redefine Their Stemness Potential

Human perinatal stem cells (SCs) can be isolated from fetal annexes without ethical or safety limitations. They are generally considered multipotent; nevertheless, their biological characteristics are still not fully understood. The aim of this study was to investigate the pluripotency potential of human perinatal SCs as compared to human induced pluripotent stem cells (hiPSCs). Despite the low expression of the pluripotent factors NANOG, OCT4, SOX2, and C-KIT in perinatal SC, we observed minor differences in the promoters DNA-methylation profile of these genes with respect to hiPSCs; we also demonstrated that in perinatal SCs miR-145-5p had an inverse trend in comparison to these stemness markers, suggesting that NANOG, OCT4, and SOX2 were regulated at the post-transcriptional level. The reduced expression of stemness markers was also associated with shorter telomere lengths and shift of the oxidative metabolism between hiPSCs and fetal annex-derived cells. Our findings indicate the differentiation ability of perinatal SCs might not be restricted to the mesenchymal lineage due to an epigenetic barrier, but other regulatory mechanisms such as telomere shortening or metabolic changes might impair their differentiation potential and challenge their clinical application.

Immunohistochemical Results of Soft tissues Around a New Implant Healing-Abutment Surface: A Human Study

Although, the high success rate of implant rehabilitation treatment, the biological complications such as bone loss and peri-implantitis are still present. The creation of a coronal biological seal between the implant and the oral tissues seems to be a crucial point on preserving dental implants. The objective of this study was to immunohistochemically analyze the behavior of peri-implant soft tissues around a new implant healing-abutment surface on humans. A total of 30 soft tissue biopsies were collected after a healing period of 30 (±7) days, to analyze the expression of inflammatory (cluster of differentiation 63 (CD63), human neutrophil peptides 1-3 (HPN1-3)) and junctional (E-cadherin, occludin, and β-catenin) markers, on soft tissues around laser treated and machined alternated healing abutments. The evaluation demonstrated the whole area of the soft tissues adherent to the laser treated surface with a regular morphology. While several stress hallmarks in correspondence of machined surfaces were shown such as: a) An irregular, disrupted, and discontinued basal membrane with an increased inflammation evident both the epithelial and connective tissues; b) the absence or defective proper keratinization process of the external layer, and c) damages in the cell to cell interaction. In conclusion, the laser treated surface is preferable to maintain the integrity and functionality of the gingiva epithelium.

Cardiomyocytes Derived from Human CardiopoieticAmniotic Fluids

Human amniotic fluid (hAF) cells share characteristics of both embryonic and adult stem cells. They proliferate rapidly and can differentiate into cells of all embryonic germ layers but do not form teratomas. Embryoid-bodies obtained from hAF have cardiac differentiation potential, but terminal differentiation to cardiomyocytes (CMs) has not yet been described. Our purpose was to promote cardiac differentiation in hAFcells. Cells were exposed to inducing factors for up to 15 days. Only the subset of hAF cells expressing the multipotency markers SSEA4, OCT4 and CD90 (^{Cardiopoietic}AF cells) responded to the differentiation process by increasing the expression of the cardiac transcription factors Nkx2.5 and GATA4, sarcomeric proteins (cTnT, α-MHC, α-SA), Connexin43 and atrial and ventricular markers. Furthermore, differentiated cells were positive for the calcium pumps CACNA1C and SERCA2a, with approximately 30% of ^{Cardiopoietic}AF-derived CM-like cells responding to caffeine or adrenergic stimulation. Some spontaneous rare beating foci were also observed. In conclusion, we demonstrated that ^{Cardiopoietic}AF cells might differentiate toward the cardiac lineage giving rise to CM-like cells characterized by several cardiac-specific molecular, structural, and functional properties.

The thrombopoietin/MPL axis is activated in the Gata1low mouse model of myelofibrosis and is associated with a defective RPS14 signature

Myelofibrosis (MF) is characterized by hyperactivation of thrombopoietin (TPO) signaling, which induces a RPS14 deficiency that de-regulates GATA1 in megakaryocytes by hampering its mRNA translation. As mice carrying the hypomorphic Gata1^low mutation, which reduces the levels of Gata1 mRNA in megakaryocytes, develop MF, we investigated whether the TPO axis is hyperactive in this model. Gata1^low mice contained two times more Tpo mRNA in liver and TPO in plasma than wild-type littermates. Furthermore, Gata1^low LSKs expressed levels of Mpl mRNA (five times greater than normal) and protein (two times lower than normal) similar to those expressed by LSKs from TPO-treated wild-type mice. Gata1^low marrow and spleen contained more JAK2/STAT5 than wild-type tissues, an indication that these organs were reach of TPO-responsive cells. Moreover, treatment of Gata1^low mice with the JAK inhibitor ruxolitinib reduced their splenomegaly. Also in Gata1^low mice activation of the TPO/MPL axis was associated with a RSP14 deficiency and a discordant microarray ribosome signature (reduced RPS24, RPS26 and SBDS expression). Finally, electron microscopy revealed that Gata1^low megakaryocytes contained poorly developed endoplasmic reticulum with rare polysomes. In summary, Gata1^low mice are a bona fide model of MF, which recapitulates the hyperactivation of the TPO/MPL/JAK2 axis observed in megakaryocytes from myelofibrotic patients.

Porcine intestinal mast cells. Evaluation of different fixatives for histochemical staining techniques considering tissue shrinkage

Staining of mast cells (MCs), including porcine ones, is critically dependent upon the fixation and staining technique. In the pig, mucosal and submucosal MCs do not stain or stain only faintly after formalin fixation. Some fixation methods are particularly recommended for MC staining, for example the fixation with Carnoy or lead salts. Zinc salt fixation (ZSF) has been reported to work excellently for the preservation of fixation-sensitive antigens. The aim of this study was to establish a reliable histological method for counting of MCs in the porcine intestinum. For this purpose, different tissue fixation and staining methods that also allow potential subsequent immunohistochemical investigations were evaluated in the porcine mucosa, as well as submucosa of small and large intestine. Tissues were fixed in Carnoy, lead acetate, lead nitrate, Zamboni and ZSF and stained subsequently with either polychromatic methylene blue, alcian blue or toluidine blue. For the first time our study reveals that ZSF, a heavy metal fixative, preserves metachromatic staining of porcine MCs. Zamboni fixation was not suitable for histochemical visualization of MCs in the pig intestine. All other tested fixatives were suitable. Alcian blue and toluidine blue co-stained intestinal goblet cells which made a prima facie identification of MCs difficult. The polychromatic methylene blue proved to be the optimal staining. In order to compare MC counting results of the different fixation methods, tissue shrinkage was taken into account. As even the same fixation caused shrinkagedifferences between tissue from small and large intestine, different factors for each single fixation and intestinal localization had to be calculated. Tissue shrinkage varied between 19% and 57%, the highest tissue shrinkage was found after fixation with ZSF in the large intestine, the lowest one in the small intestine after lead acetate fixation. Our study emphasizes that MC counting results from data using different fixation techniques can only be compared if the respective studyimmanent shrinkage factor has been determined and quantification results are adjusted accordingly.

Mast cell progenitor trafficking and maturation

Mast cells are derived from the hematopoietic progenitors found in bone marrow and spleen. Committed mast cell progenitors are rare in bone marrow suggesting they are rapidly released into the blood where they circulate and move out into the peripheral tissues. This migration is controlled in a tissue specific manner. Basal trafficking to the intestine requires expression of α4β7 integrin and the chemokine receptor CXCR2 by the mast cell progenitors and expression of MAdCAM-1 and VCAM-1 in the intestinal endothelium; and is also controlled by dendritic cells expressing the transcriptional regulatory protein T-bet. None of these play a role in basal trafficking to the lung. With the induction of allergic inflammation in the lung, there is marked recruitment of committed mast cell progenitors to lung and these cells must express α4β7 and α4β1 integrins. Within the lung there is a requirement for expression of VCAM-1 on the endothelium that is regulated by CXCR2, also expressed on the endothelium. There is a further requirement for expression of the CCR2/CCL2 pathways for full recruitment of the mast cell progenitors to the antigen-inflamed lung.

Increased differentiation of dermal mast cells in mice lacking the Mpl gene

Thrombopoietin interactions with its receptor, Mpl, play an important role in the regulation of hematopoietic stem/progenitor cell proliferation and differentiation. In this study, we report that the mast cell restricted progenitor cells (MCP) and the mast cell precursors in the bone marrow of wild-type mice express Mpl on their surface. Furthermore, targeted deletion of the Mpl gene in mice decreases the number of MCP while increasing the number of mast cell precursors present in the marrow and spleen. It also increases the number of mast cells present in the dermis, in the peritoneal cavity, and in the gut of the mice. In addition, serosal mast cells from Mpl(null) mice have a distinctive differentiation profile similar to that expressed by wild-type dermal mast cells. These results suggest that not only does ligation of thrombopoietin with the Mpl receptor exert an effect at the mast cell restricted progenitor cell level, but also plays an unexpected yet important role in mast cell maturation.

Molecular regulation of mast cell development and maturation

Mast cells play a crucial role in the pathogenesis of allergic diseases. In recent years, tremendous progresses have been made in studies of mast cell origination, migration, proliferation, maturation and survival, and the cytokines regulating these activities. These advances have significantly improved our understandings to mast cell biology and to the molecular mechanisms of mast cells in the pathogenesis of allergic diseases.

Advances in the understanding of congenital amegakaryocytic thrombocytopenia

Congenital amegakaryocytic thrombocytopenia (MIM #604498) is an extremely rare inherited bone marrow failure syndrome, usually presenting as a severe thrombocytopenia at birth due to ineffective megakaryocytopoiesis and no characteristic physical anomalies. Usually the isolated thrombocytopenia progresses to pancytopenia during the first years of life. The only curative therapy to date is haematopoietic stem cell transplantation. Most of the cases of congenital amegakaryocytic thrombocytopenia are caused by defective expression or function of the thrombopoietin receptor due to homozygous or compound heterozygous mutations in the gene MPL. The essential roles of thrombopoietin as a lineage specific regulator of platelet production and as a regulator of haematopoietic stem cell function are reflected in the haematological defects seen in affected individuals.