Guide Cells Support Muscle Regeneration and Affect Neuro-Muscular Junction Organization.

Muscular regeneration is a complex biological process that occurs during acute injury and chronic degeneration, implicating several cell types. One of the earliest events of muscle regeneration is the inflammatory response, followed by the activation and differentiation of muscle progenitor cells. However, the process of novel neuromuscular junction formation during muscle regeneration is still largely unexplored. Here, we identify by single-cell RNA sequencing and isolate a subset of vessel-associated cells able to improve myogenic differentiation. We termed them 'guide' cells because of their remarkable ability to improve myogenesis without fusing with the newly formed fibers. In vitro, these cells showed a marked mobility and ability to contact the forming myotubes. We found that these cells are characterized by CD44 and CD34 surface markers and the expression of Ng2 and Ncam2. In addition, in a murine model of acute muscle injury and regeneration, injection of guide cells correlated with increased numbers of newly formed neuromuscular junctions. Thus, we propose that guide cells modulate de novo generation of neuromuscular junctions in regenerating myofibers. Further studies are necessary to investigate the origin of those cells and the extent to which they are required for terminal specification of regenerating myofibers.

ROS in Platelet Biology: Functional Aspects and Methodological Insights.

Reactive oxygen species (ROS) and mitochondria play a pivotal role in regulating platelet functions. Platelet activation determines a drastic change in redox balance and in platelet metabolism. Indeed, several signaling pathways have been demonstrated to induce ROS production by NAPDH oxidase (NOX) and mitochondria, upon platelet activation. Platelet-derived ROS, in turn, boost further ROS production and consequent platelet activation, adhesion and recruitment in an auto-amplifying loop. This vicious circle results in a platelet procoagulant phenotype and apoptosis, both accounting for the high thrombotic risk in oxidative stress-related diseases. This review sought to elucidate molecular mechanisms underlying ROS production upon platelet activation and the effects of an altered redox balance on platelet function, focusing on the main advances that have been made in platelet redox biology. Furthermore, given the increasing interest in this field, we also describe the up-to-date methods for detecting platelets, ROS and the platelet bioenergetic profile, which have been proposed as potential disease biomarkers.

PKCε promotes human Th17 differentiation: Implications in the pathophysiology of psoriasis.

PKCε is implicated in T cell activation and proliferation and is overexpressed in CD4+ -T cells from patients with autoimmune Hashimoto's thyroiditis. Although this might induce the suspicion that PKCε takes part in autoimmunity, its role in the molecular pathophysiology of immune-mediated disorders is still largely unknown. We studied PKCε expression in circulating CD4+ -T cells from patients with psoriasis, a skin disorder characterized by an increased amount of Th17 cells, a CD4+ subset that is critical in the development of autoimmunity. Although the mechanisms that underlie Th17 differentiation in humans are still unclear, we here show that: (i) PKCε is overexpressed in CD4+ -T cells from psoriatic patients, and its expression positively correlates with the severity of the disease, being reduced by effective phototherapy; (ii) PKCε interacts with Stat3 during Th17 differentiation and its overexpression results in an enhanced expression of Stat3 and pStat3(Ser727); iii) conversely, when PKCε is forcibly downregulated, CD4+ -T cells show lower levels of pStat3(Ser727) expression and defective in vitro expansion into the Th17-lineage. These data provide a novel insight into the molecular mechanisms of Th17 cell polarization that is known to play a crucial role in autoimmunity, pinpointing PKCε as a potential target in Th17-mediated diseases.

Claimed effects, outcome variables and methods of measurement for health claims on foods proposed under European Community Regulation 1924/2006 in the area of appetite ratings and weight management.

All the requests for authorisation to bear health claims under Articles 13(5) and 14 in the context of appetite ratings and weight management have received a negative opinion by the European Food Safety Authority (EFSA), mainly because of the insufficient substantiation of the claimed effects (CEs). This manuscript results from an investigation aimed to collect, collate and critically analyse the information related to outcome variables (OVs) and methods of measurement (MMs) in the context of appetite ratings and weight management compliant with Regulation 1924/2006. Based on the literature review, the appropriateness of OVs and MMs was evaluated for specific CEs. This work might help EFSA in the development of updated guidance addressed to stakeholders interested in bearing health claims in the area of weight management. Moreover, it could drive the applicants during the design of randomised controlled trials aimed to substantiate such claims.

Claimed effects, outcome variables and methods of measurement for health claims on foods related to the gastrointestinal tract proposed under regulation (EC) 1924/2006.

Most of the requests of authorisation to the use of health claims pursuant to Regulation EC 1924/2006 related to the gastrointestinal (GI) tract have received a negative opinion by the European Food Safety Authority (EFSA), mainly because of an insufficient substantiation of the claimed effect (CE). The present manuscript refers to the collection, collation and critical analysis of outcome variables (OVs) and methods of measurement (MMs) related to the GI tract compliant with Regulation 1924/2006. The critical evaluation of OVs and MMs was based on the literature review, with the final aim of defining their appropriateness in the context of a specific CE. The results obtained are relevant for the choice of the best OVs and MMs to be used in randomised controlled trials aimed to substantiate the claims on the GI tract. Moreover, the results can be used by EFSA for updating the guidance for the scientific requirements of such health claims.

Human thrombopoiesis depends on Protein kinase Cδ/protein kinase Cε functional couple.

A deeper understanding of the molecular events driving megakaryocytopoiesis and thrombopoiesis is essential to regulate in vitro and in vivo platelet production for clinical applications. We previously documented the crucial role of PKCε in the regulation of human and mouse megakaryocyte maturation and platelet release. However, since several data show that different PKC isoforms fulfill complementary functions, we targeted PKCε and PKCδ, which show functional and phenotypical reciprocity, at the same time as boosting platelet production in vitro. Results show that PKCδ, contrary to PKCε, is persistently expressed during megakaryocytic differentiation, and a forced PKCδ down-modulation impairs megakaryocyte maturation and platelet production. PKCδ and PKCε work as a functional couple with opposite roles on thrombopoiesis, and the modulation of their balance strongly impacts platelet production. Indeed, we show an imbalance of PKCδ/PKCε ratio both in primary myelofibrosis and essential thrombocythemia, featured by impaired megakaryocyte differentiation and increased platelet production, respectively. Finally, we demonstrate that concurrent molecular targeting of both PKCδ and PKCε represents a strategy for in vitro platelet factories.

Cytofluorimetric platelet analysis.

Blood platelets are highly specialized cells that drive hemostatic events and tissue repair mechanisms at the site of vascular injury. Their peculiar morphology and certain functional characteristics can be analyzed by flow cytometry (FCM). Specifically, platelet activation, a hallmark of prothrombotic states and inflammatory conditions, is associated with changes in expression of both surface and intracellular antigens that are recognized by specific monoclonal antibodies. Assessment of platelet activation status as ex vivo or in vitro reactivity to specific agonists has become relevant in particular conditions (namely, cardiovascular diseases, hematological malignancies, monitoring of pharmacological antiaggregation). In addition, aberrant surface marker expression that characterizes inherited and acquired platelet function disorders is also detected by FCM. This review discusses the main applications of FCM in platelet analyses, which are relevant for both research and clinical settings.

Laboratory diagnostics of inherited platelet disorders.

Abstract Inherited platelet disorders (IPDs) are the general and common denomination of a broad number of different rare and congenital pathologies affecting platelets. Even if these disorders are characterized by widely heterogeneous clinical presentations, all of them are commonly present as defects in hemostasis. Platelet number and/or function are affected by a wide spectrum of severity. IPDs might be associated with defects in bone marrow megakaryocytopoiesis and, rarely, with somatic defects. Although in the last few years new insights in the genetic bases and pathophysiology of IPDs have greatly improved our knowledge of these disorders, much effort still needs to be made in the field of laboratory diagnosis. This review discusses the laboratory approach for the differential diagnosis of the most common IPDs, suggesting a common multistep flowchart model which starts from the simpler test (platelet count) ending with the more selective and sophisticated analyses.

Protein kinase C ε in hematopoiesis: conductor or selector?

Mainly known for its cardioprotective properties, protein kinase C isoform ε (PKCε) is also progressively coming of age in terms of its role in hematopoiesis regulation, particularly that is related to erythropoiesis, megakaryocytopoiesis, and platelet production. Data available to date show that PKCε is differentially regulated in erythrocyte and megakaryocyte progenitors, strongly suggesting an addressing role toward maturation of either lineage. This function appears to be played by either selecting progenitors or conducting maturation toward a specific fate. Inappropriate expression of PKCε in human mature platelets is discussed as a recently described example of functional modification that may acquire pathophysiologic relevance in major thrombotic diseases. Preliminary evidence suggests that PKCε expression may be used as a surrogate marker for thrombotic risk stratification and as a possible target for antiplatelet therapy in patients with thrombotic disorders.

TRAIL up-regulation must be accompanied by a reciprocal PKCε down-regulation during differentiation of colonic epithelial cell: implications for colorectal cancer cell differentiation.

PKC isoenzymes play central roles in various cellular signalling pathways, participating in a variety of protein phosphorylation cascades that regulate/modulate cellular structure and gene expression. It has been firmly established that several isoforms of PKC have a role in the regulation of tumor necrosis factor-related apoptosis inducing ligand (TRAIL) activity. Our interest in probing the role of the epsilon isoform of PKC in the colonic cell differentiation stems from the discovery that PKCε and TRAIL are involved in the differentiation of other cell types like hematopoietic stem cells. Although the role of PKCε and TRAIL in the gastrointestinal system is unclear, it has been observed that PKCε has oncogenic activity in colon epithelial cells (CEC), while TRAIL increases the death of intestinal epithelial cells during inflammation. Here we demonstrate a reciprocal expression of PKCε and TRAIL in human colon mucosa: CECs at the bottom of the colonic crypts show high levels of PKCε, being negative for TRAIL expression. On the contrary, luminal CECs are positive for TRAIL, while negative for PKCε. Indeed, TRAIL- and butyrate-induced differentiation of the human colorectal cancer cell line HT29 requires the decrease of PKCε expression, whose absence in turn increases cell sensitivity to TRAIL-induced apoptosis. Moreover, TRAIL preferentially promotes HT29 differentiation into goblet cells. Taken together, this data demonstrate that TRAIL and PKCε must be reciprocally regulated to ensure physiological CEC differentiation starting from the stem cell pool, and that the down-regulation of PKCε is however critical for the differentiation and apoptosis of cancer cells.

Interlink Between Physiological and Biomechanical Changes in the Swim-to-Cycle Transition in Triathlon Events: A Narrative Review.

Triathlon is a multisport composed of swim, cycle, and run segments and two transition periods. The swim-to-cycle transition is considered a critical period for the change in body position and the modifications in physiological (heart rate, VO2, lactate) and biomechanical parameters (cycling power and cadence, swimming stroke rate). Therefore, the aim of this review was to summarize the current evidence regarding the physiological and biomechanical changes and their interlink during the swim-to-cycle transition hinting at practical recommendations for coaches and athletes. The influence of the swim segment on cycle one is more evident for short-distance events. Greater modifications occur in athletes of lower level. The modulation of intensity during the swim segment affects the changes in the physiological parameters (heart rate, blood lactate, core temperature), with a concomitant influence on cycling gross efficiency. However, gross efficiency could be preserved by wearing a wetsuit or by swimming in a drafting position. A higher swim leg frequency during the last meters of the segment induces a higher cadence during the cycle segment. Training should be directed to the maintenance of a swimming intensity around 80-90% of a previous maximal swim test and with the use of a positive pacing strategy. When athletes are intended to train consecutively only swim and cycle segments, for an optimal muscle activation during cycling, triathletes could adopt a lower cadence (about 60-70% of their typical cadence), although an optimal pedaling cadence depends on the level and type of athlete. Future research should be focused on the combined measurements of physiological and biomechanical parameters using an intervention study design to evaluate training adaptations on swim kick rate and their effects on cycling performance. Coaches and athletes could benefit from the understanding of the physiological and biomechanical changes occurring during the swim-to-cycle transition to optimize the overall triathlon performance.

Mesoangioblasts at 20: From the embryonic aorta to the patient bed.

In 2002 we published an article describing a population of vessel-associated progenitors that we termed mesoangioblasts (MABs). During the past decade evidence had accumulated that during muscle development and regeneration things may be more complex than a simple sequence of binary choices (e.g., dorsal vs. ventral somite). LacZ expressing fibroblasts could fuse with unlabelled myoblasts but not among themselves or with other cell types. Bone marrow derived, circulating progenitors were able to participate in muscle regeneration, though in very small percentage. Searching for the embryonic origin of these progenitors, we identified them as originating at least in part from the embryonic aorta and, at later stages, from the microvasculature of skeletal muscle. While continuing to investigate origin and fate of MABs, the fact that they could be expanded in vitro (also from human muscle) and cross the vessel wall, suggested a protocol for the cell therapy of muscular dystrophies. We tested this protocol in mice and dogs before proceeding to the first clinical trial on Duchenne Muscular Dystrophy patients that showed safety but minimal efficacy. In the last years, we have worked to overcome the problem of low engraftment and tried to understand their role as auxiliary myogenic progenitors during development and regeneration.

In vitro calcified matrix deposition by human osteoblasts onto a zinc-containing bioactive glass.

Bioactive glasses synthesized by the sol-gel technique possess many of the qualities associated with an ideal scaffold material for a bone graft substitute. In view of the potential clinical applications, we performed a detailed in vitro study of the biological reactivity of synthesized 58S bioactive glass containing-zinc, in terms of osteoblast morphology, proliferation, and deposition of a mineralized extracellular matrix (ECM). Human Sarcoma Osteoblast (SAOS-2) cells were used to i) assess cytotoxicity by lactate dehydrogenase (LDH) release and ii) evaluate the deposition of a calcified extracellular matrix by ELISA assay and quantitative RT-PCR (qRT-PCR). In comparison with pure silica and 58S, the 58S-Zn0.4 bioglass showed a significant increase in cellular proliferation and deposition of ECM components such as decorin, fibronectin, osteocalcin, osteonectin, osteopontin, type-I and -III collagens. Calcium deposition was significantly higher than on pure silica and 58S samples. Also Alkaline phosphatase (ALP) activity and its protein content was higher with respect to pure silica and 58S. qRT-PCR analysis revealed the up-regulation of type-I collagen, bone sialoprotein and osteopontin genes. All together these results demonstrate the cytocompatibility of 58S-Zn0.4 bioglass and its capability to promote osteoblast differentiation.

Localization of Magic-F1 transgene, involved in muscular hypertrophy, during early myogenesis.

We recently showed that Magic-F1 (Met-activating genetically improved chimeric factor 1), a human recombinant protein derived from hepatocyte growth factor/scatter factor (HGF/SF) induces muscle cell hypertrophy but not progenitor cell proliferation, both in vitro and in vivo. Here, we examined the temporal and spatial expression pattern of Magic-F1 in comparison with Pax3 (paired box gene 3) transcription factor during embryogenesis. Ranging from 9.5 to 17.5 dpc (days post coitum) mouse embryos were analyzed by in situ hybridization using whole mounts during early stages of development (9.5-10.5-11.5 dpc) and cryostat sections for later stages (11.5-13.5-15.5-17.5 dpc). We found that Magic-F1 is expressed in developing organs and tissues of mesenchymal origin, where Pax3 signal appears to be downregulated respect to the wt embryos. These data suggest that Magic-F1 could be responsible of muscular hypertrophy, cooperating with Pax3 signal pathway in skeletal muscle precursor cells.

Posture and gait in the early course of schizophrenia.

While correlations between postural stability deficits and schizophrenia are well documented, information on dynamic motor alterations in schizophrenia are still scarce, and no data on their onset are available yet. Therefore, the aim of this study was i) to measure gait pattern(s) in patients with schizophrenia; ii) to identify posture and gait alterations which could potentially be used as a predictive clinical tool of the onset of the disorder. Body composition, posture and gait parameters were assessed in a group of 30 patients with schizophrenia and compared to 25 healthy subjects. Sway area was significantly higher in the schizophrenia group compared to controls regardless of whether the participants were in eyes open or eyes closed condition. Gait cadence and speed were significantly lower in patients with schizophrenia, while stride length was similar. We concluded that the combination of an increased sway area (independent from eye closure) and a gait cadence reduction-in the presence of normal gait speed and stride length-might be considered peculiar postural and gait profile characteristic of early schizophrenia.

Hydrogen Sulfide Inhibits TMPRSS2 in Human Airway Epithelial Cells: Implications for SARS-CoV-2 Infection.

The COVID-19 pandemic has now affected around 190 million people worldwide, accounting for more than 4 million confirmed deaths. Besides ongoing global vaccination, finding protective and therapeutic strategies is an urgent clinical need. SARS-CoV-2 mostly infects the host organism via the respiratory system, requiring angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) to enter target cells. Therefore, these surface proteins are considered potential druggable targets. Hydrogen sulfide (H2S) is a gasotransmitter produced by several cell types and is also part of natural compounds, such as sulfurous waters that are often inhaled as low-intensity therapy and prevention in different respiratory conditions. H2S is a potent biological mediator, with anti-oxidant, anti-inflammatory, and, as more recently shown, also anti-viral activities. Considering that respiratory epithelial cells can be directly exposed to H2S by inhalation, here we tested the in vitro effects of H2S-donors on TMPRSS2 and ACE2 expression in human upper and lower airway epithelial cells. We showed that H2S significantly reduces the expression of TMPRSS2 without modifying ACE2 expression both in respiratory cell lines and primary human upper and lower airway epithelial cells. Results suggest that inhalational exposure of respiratory epithelial cells to natural H2S sources may hinder SARS-CoV-2 entry into airway epithelial cells and, consequently, potentially prevent the virus from spreading into the lower respiratory tract and the lung.

One-shoulder carrying school backpack strongly affects gait swing phase and pelvic tilt: a case study.

The use of backpacks is common to both adults and children and often leads to the onset of musculoskeletal discomforts. Although a large number of studies have focused on the optimal load for children schoolbags, there is no general consensus. Here we report a 13-yr old girl case study, showing the impact of weight and wearing the school backpack on gait parameters. The variation of gait parameters and pelvis angles in different conditions were studied: without backpack (CTRL), or with backpack at 10% Body Weight (10BW), 15% BW (15BW) and 20% BW (20BW), carried "on both shoulders" (2S), "on one shoulder" (1S), or "with one hand" (1H). Swing phase was comparably modified by 2S/20BW and 1S/10BW conditions, suggesting that a lower backpack weight was sufficient to induce gait alterations when carried in asymmetrical conditions. Pelvic tilt, which was preserved by a two-shoulders distributed 10% BW load (2S/10BW), was strongly  reduced in asymmetrical condition (1S/10BW), suggesting that a low weight carried on a single shoulder generates postural modifications including reduction of pelvic tilting, which is known to be associated to low back pain.

Muscle Activation in Traditional and Experimental Barbell Bench Press Exercise: A Potential New Tool for Fitness Maintenance.

BACKGROUND: The bench press exercise (BP) is commonly practiced in both recreational and professional training. The weight is lowered from a position where the elbows are at a 90° angle at the start and <90° at the end of eccentric phase, and then returned to the elbows extended position. In order to focus the exercise more on the triceps brachii (TB) rather than the pectoralis major (PM), the inter-handle distance (IHD) is decreased diminishing the involvement of the PM in favor of the TB. PURPOSE: To improve performance of the exercise by reducing force dissociation and transmitting 100% of the external load to the muscle tissue we propose a prototype of the barbell with a bar on which two sleeves are capable of sliding. The dynamic modifications of the IHD keep the elbow flexion angle constant at 90°. RESULTS: Analysis of the inter-handle distance (IHD) signals of the upper body muscles showed a marked increase in muscle activity using the experimental barbell for the PM (19.5%) and for the biceps brachii (173%). CONCLUSIONS: The experimental barbell increased the muscle activity typical of the bench press exercise, obtaining the same training induction with a lower load and consequently preventing articular stress.

Sighting acute myocardial infarction through platelet gene expression.

Acute myocardial infarction is primarily due to coronary atherosclerotic plaque rupture and subsequent thrombus formation. Platelets play a key role in the genesis and progression of both atherosclerosis and thrombosis. Since platelets are anuclear cells that inherit their mRNA from megakaryocyte precursors and maintain it unchanged during their life span, gene expression profiling at the time of an acute myocardial infarction provides information concerning the platelet gene expression preceding the coronary event. In ST-segment elevation myocardial infarction (STEMI), a gene-by-gene analysis of the platelet gene expression identified five differentially expressed genes: FKBP5, S100P, SAMSN1, CLEC4E and S100A12. The logistic regression model used to combine the gene expression in a STEMI vs healthy donors score showed an AUC of 0.95. The same five differentially expressed genes were externally validated using platelet gene expression data from patients with coronary atherosclerosis but without thrombosis. Platelet gene expression profile highlights five genes able to identify STEMI patients and to discriminate them in the background of atherosclerosis. Consequently, early signals of an imminent acute myocardial infarction are likely to be found by platelet gene expression profiling before the infarction occurs.

Claimed effects, outcome variables and methods of measurement for health claims proposed under European Community Regulation 1924/2006 in the area of blood glucose and insulin concentrations.

Most requests for authorization to bear health claims under Articles 13(5) and 14 related to blood glucose and insulin concentration/regulation presented to the European Food Safety Authority (EFSA) receive a negative opinion. Reasons for such decisions are mainly ascribable to poor substantiation of the claimed effects. In this scenario, a project was carried out aiming at critically analysing the outcome variables (OVs) and methods of measurement (MMs) to be used to substantiate health claims, with the final purpose to improve the quality of applications provided by stakeholders to EFSA. This manuscript provides a position statement of the experts involved in the project, reporting the results of an investigation aimed to collect, collate and critically analyse the information relevant to claimed effects (CEs), OVs and MMs related to blood glucose and insulin levels and homoeostasis compliant with Regulation 1924/2006. The critical analysis of OVs and MMs was performed with the aid of the pertinent scientific literature and was aimed at defining their appropriateness (alone or in combination with others) to support a specific CE. The results can be used to properly select OVs and MMs in a randomized controlled trial, for an effective substantiation of the claims, using the reference method(s) whenever available. Moreover, results can help EFSA in updating the guidance for the scientific requirements of health claims.