Impacts of radiation exposure, hindlimb unloading, and recovery on murine skeletal muscle cell telomere length.

Astronauts are exposed to harsh conditions, including cosmic radiation and microgravity. Spaceflight elongates human telomeres in peripheral blood, which shorten upon return to Earth and approach baseline levels during postflight recovery. Astronauts also encounter muscle atrophy, losing up to 20% loss of muscle mass on spaceflights. Telomere length changes in muscle cells of astronauts remain unexplored. This study investigates telomere alterations in grounded mice experiencing radiation exposure and muscle atrophy, via a hindlimb unloading spaceflight mimicking model. We find telomere lengthening is present in muscle stem cells and in myofiber nuclei, but not in muscle-resident endothelial cells. We further assessed telomere length in the model following hindlimb unloading recovery. We find that telomere length failed to return to baseline values. Our results suggest a role for telomeres in muscle acclimatization, which is relevant for the well-being of astronauts in space, and upon their return to Earth.

Unlocking the Potential of Colloidal Quantum Dot/Organic Hybrid Solar Cells: Band Tunable Interfacial Layer Approach.

Hybrid colloidal quantum dot (CQD)/organic architectures are promising candidates for emerging optoelectronic devices having high performance and inexpensive fabrication. For unlocking the potential of CQD/organic hybrid devices, enhancing charge extraction properties at electron transport layer (ETL)/CQD interfaces is crucial. Hence, we carefully adjust the interface properties between the ETL and CQD layer by incorporating an interfacial layer for the ETL (EIL) using several types of cinnamic acid ligands. The EIL having a cascading band offset (ΔEC) between the ETL and CQD layer suppresses the potential barrier and the local charge accumulation at ETL/CQD interfaces, thereby reducing the bimolecular recombination. An optimal EIL effectively expands the depletion region that facilitates charge extraction between the ETL and CQD layer while preventing the formation of shallow traps. Representative devices with an EIL exhibit a maximum power conversion efficiency of 14.01% and retain over 80% of initial performances after 300 h under continuous maximum power point operation.

Quantum Dot-Siloxane Anchoring on Colloidal Quantum Dot Film for Flexible Photovoltaic Cell.

Lead sulfide (PbS) colloidal quantum dots (CQDs) are promising materials for next-generation flexible solar cells because of near-infrared absorption, facile bandgap tunability, and superior air stability. However, CQD devices still lack enough flexibility to be applied to wearable devices owing to the poor mechanical properties of CQD films. In this study, a facile approach is proposed to improve the mechanical stability of CQDs solar cells without compromising the high power conversion efficiency (PCE) of the devices. (3-aminopropyl)triethoxysilane (APTS) is introduced on CQD films to strengthen the dot-to-dot bonding via QD-siloxane anchoring, and as a result, crack pattern analysis reveals that the treated devices become robust to mechanical stress. The device maintains 88% of the initial PCE under 12 000 cycles at a bending radius of 8.3 mm. In addition, APTS forms a dipole layer on CQD films, which improves the open circuit voltage (VOC ) of the device, achieving a PCE of 11.04%, one of the highest PCEs in flexible PbS CQD solar cells.

Candida albicans-specific Th17 cell-mediated response contributes to alcohol-associated liver disease.

Alcohol-associated liver disease is accompanied by intestinal mycobiome dysbiosis, yet the impacts on liver disease are unclear. We demonstrate that Candida albicans-specific T helper 17 (Th17) cells are increased in circulation and present in the liver of patients with alcohol-associated liver disease. Chronic ethanol administration in mice causes migration of Candida albicans (C. albicans)-reactive Th17 cells from the intestine to the liver. The antifungal agent nystatin decreased C. albicans-specific Th17 cells in the liver and reduced ethanol-induced liver disease in mice. Transgenic mice expressing T cell receptors (TCRs) reactive to Candida antigens developed more severe ethanol-induced liver disease than transgene-negative littermates. Adoptively transferring Candida-specific TCR transgenic T cells or polyclonal C. albicans-primed T cells exacerbated ethanol-induced liver disease in wild-type mice. Interleukin-17 (IL-17) receptor A signaling in Kupffer cells was required for the effects of polyclonal C. albicans-primed T cells. Our findings indicate that ethanol increases C. albicans-specific Th17 cells, which contribute to alcohol-associated liver disease.

Fission impossible: Mitochondrial dynamics direct muscle stem cell fates.

Muscle stem cells (MuSCs) exhibit different metabolic profiles depending on their activity, however the mechanisms by which mitochondria affect MuSC fate has been understudied. In this issue of Cell Stem Cell, Hong et al. (2022) and Baker et al. (2022) demonstrate that defects in mitochondrial dynamics hinder proper MuSC activation and impair muscle regeneration.

PDE4B Is a Homeostatic Regulator of Cyclic AMP in Dendritic Cells.

Chronic decreases in the second messenger cyclic AMP (cAMP) occur in numerous settings, but how cells compensate for such decreases is unknown. We have used a unique system-murine dendritic cells (DCs) with a DC-selective depletion of the heterotrimeric GTP binding protein Gαs-to address this issue. These mice spontaneously develop Th2-allergic asthma and their DCs have persistently lower cAMP levels. We found that phosphodiesterase 4B (PDE4B) is the primary phosphodiesterase expressed in DCs and that its expression is preferentially decreased in Gαs-depleted DCs. PDE4B expression is dynamic, falling and rising in a protein kinase A-dependent manner with decreased and increased cAMP concentrations, respectively. Treatment of DCs that drive enhanced Th2 immunity with a PDE4B inhibitor ameliorated DC-induced helper T cell response. We conclude that PDE4B is a homeostatic regulator of cellular cAMP concentrations in DCs and may be a target for treating Th2-allergic asthma and other settings with low cellular cAMP concentrations.

Piezo1 regulates the regenerative capacity of skeletal muscles via orchestration of stem cell morphological states.

Muscle stem cells (MuSCs) are essential for tissue homeostasis and regeneration, but the potential contribution of MuSC morphology to in vivo function remains unknown. Here, we demonstrate that quiescent MuSCs are morphologically heterogeneous and exhibit different patterns of cellular protrusions. We classified quiescent MuSCs into three functionally distinct stem cell states: responsive, intermediate, and sensory. We demonstrate that the shift between different stem cell states promotes regeneration and is regulated by the sensing protein Piezo1. Pharmacological activation of Piezo1 is sufficient to prime MuSCs toward more responsive cells. Piezo1 deletion in MuSCs shifts the distribution toward less responsive cells, mimicking the disease phenotype we find in dystrophic muscles. We further demonstrate that Piezo1 reactivation ameliorates the MuSC morphological and regenerative defects of dystrophic muscles. These findings advance our fundamental understanding of how stem cells respond to injury and identify Piezo1 as a key regulator for adjusting stem cell states essential for regeneration.

ANT2 drives proinflammatory macrophage activation in obesity.

Macrophage proinflammatory activation is an important etiologic component of the development of insulin resistance and metabolic dysfunction in obesity. However, the underlying mechanisms are not clearly understood. Here, we demonstrate that a mitochondrial inner membrane protein, adenine nucleotide translocase 2 (ANT2), mediates proinflammatory activation of adipose tissue macrophages (ATMs) in obesity. Ant2 expression was increased in ATMs of obese mice compared with lean mice. Myeloid-specific ANT2-knockout (ANT2-MKO) mice showed decreased adipose tissue inflammation and improved insulin sensitivity and glucose tolerance in HFD/obesity. At the molecular level, we found that ANT2 mediates free fatty acid-induced mitochondrial permeability transition, leading to increased mitochondrial reactive oxygen species production and damage. In turn, this increased HIF-1α expression and NF-κB activation, leading to proinflammatory macrophage activation. Our results provide a previously unknown mechanism for how obesity induces proinflammatory activation of macrophages with propagation of low-grade chronic inflammation (metaflammation).

Metastasis Risk Assessment Using BAG2 Expression by Cancer-Associated Fibroblast and Tumor Cells in Patients with Breast Cancer.

Few studies have examined the role of BAG2 in malignancies. We investigated the prognostic value of BAG2-expression in cancer-associated fibroblasts (CAFs) and tumor cells in predicting metastasis-free survival in patients with breast cancer. Tissue-microarray was constructed using human breast cancer tissues obtained by surgical resection between 1992 and 2015. BAG2 expression was evaluated by immunohistochemistry in CAFs or the tumor cells. BAG2 expression in the CAFs and cytoplasm of tumor cells was classified as positive and negative, and low and high, respectively. BAG2-CAF was evaluated in 310 patients and was positive in 67 (21.6%) patients. Kaplan-Meier plots showed that distant metastasis-free survival (DMFS) was lesser in patients with BAG2(+) CAF than in patients with BAG2(-) CAF (p = 0.039). Additionally, we classified the 310 patients into two groups: 109 in either BAG2-high or BAG2(+) CAF and 201 in BAG2-low and BAG2(-) CAF. DMFS was significantly reduced in patients with either BAG2-high or BAG2(+) CAF than in the patients of the other group (p = 0.005). Multivariable analysis demonstrated that DMFS was prolonged in patients with BAG2(-) CAF or BAG2-low. Evaluation of BAG2 expression on both CAFs and tumor cells could help in determining the risk of metastasis in breast cancer.

Investigation of niclosamide as a repurposing agent for skeletal muscle atrophy.

Skeletal muscle atrophy is a feature of aging (termed sarcopenia) and various diseases, such as cancer and kidney failure. Effective drug treatment options for muscle atrophy are lacking. The tapeworm medication, niclosamide is being assessed for repurposing to treat numerous diseases, including end-stage cancer metastasis and hepatic steatosis. In this study, we investigated the potential of niclosamide as a repurposing drug for muscle atrophy. In a myotube atrophy model using the glucocorticoid, dexamethasone, niclosamide did not prevent the reduction in myotube diameter or the decreased expression of phosphorylated FOXO3a, which upregulates the ubiquitin-proteasome pathway of muscle catabolism. Treatment of normal myotubes with niclosamide did not activate mTOR, a major regulator of muscle protein synthesis, and increased the expression of atrogin-1, which is induced in catabolic states. Niclosamide treatment also inhibited myogenesis in muscle precursor cells, enhanced the expression of myoblast markers Pax7 and Myf5, and downregulated the expression of differentiation markers MyoD, MyoG and Myh2. In an animal model of muscle atrophy, niclosamide did not improve muscle mass, grip strength or muscle fiber cross-sectional area. Muscle atrophy is also feature of cancer cachexia. IC50 analyses indicated that niclosamide was more cytotoxic for myoblasts than cancer cells. In addition, niclosamide did not suppress the induction of iNOS, a key mediator of atrophy, in an in vitro model of cancer cachexia and did not rescue myotube diameter. Overall, these results suggest that niclosamide may not be a suitable repurposing drug for glucocorticoid-induced skeletal muscle atrophy or cancer cachexia. Nevertheless, niclosamide may be employed as a compound to study mechanisms regulating myogenesis and catabolic pathways in skeletal muscle.

Lithium Chloride Protects against Sepsis-Induced Skeletal Muscle Atrophy and Cancer Cachexia.

Inflammation-mediated skeletal muscle wasting occurs in patients with sepsis and cancer cachexia. Both conditions severely affect patient morbidity and mortality. Lithium chloride has previously been shown to enhance myogenesis and prevent certain forms of muscular dystrophy. However, to our knowledge, the effect of lithium chloride treatment on sepsis-induced muscle atrophy and cancer cachexia has not yet been investigated. In this study, we aimed to examine the effects of lithium chloride using in vitro and in vivo models of cancer cachexia and sepsis. Lithium chloride prevented wasting in myotubes cultured with cancer cell-conditioned media, maintained the expression of the muscle fiber contractile protein, myosin heavy chain 2, and inhibited the upregulation of the E3 ubiquitin ligase, Atrogin-1. In addition, it inhibited the upregulation of inflammation-associated cytokines in macrophages treated with lipopolysaccharide. In the animal model of sepsis, lithium chloride treatment improved body weight, increased muscle mass, preserved the survival of larger fibers, and decreased the expression of muscle-wasting effector genes. In a model of cancer cachexia, lithium chloride increased muscle mass, enhanced muscle strength, and increased fiber cross-sectional area, with no significant effect on tumor mass. These results indicate that lithium chloride exerts therapeutic effects on inflammation-mediated skeletal muscle wasting, such as sepsis-induced muscle atrophy and cancer cachexia.

Screening ginseng saponins in progenitor cells identifies 20(R)-ginsenoside Rh2 as an enhancer of skeletal and cardiac muscle regeneration.

Aging is associated with increased prevalence of skeletal and cardiac muscle disorders, such as sarcopenia and cardiac infarction. In this study, we constructed a compendium of purified ginsenoside compounds from Panax ginseng C.A. Meyer, which is a traditional Korean medicinal plant used to treat for muscle weakness. Skeletal muscle progenitor cell-based screening identified three compounds that enhance cell viability, of which 20(R)-ginsenoside Rh2 showed the most robust response. 20(R)-ginsenoside Rh2 increased viability in myoblasts and cardiomyocytes, but not fibroblasts or disease-related cells. The cellular mechanism was identified as downregulation of cyclin-dependent kinase inhibitor 1B (p27Kip1) via upregulation of Akt1/PKB phosphorylation at serine 473, with the orientation of the 20 carbon epimer being crucially important for biological activity. In zebrafish and mammalian models, 20(R)-ginsenoside Rh2 enhanced muscle cell proliferation and accelerated recovery from degeneration. Thus, we have identified 20(R)-ginsenoside Rh2 as a p27Kip1 inhibitor that may be developed as a natural therapeutic for muscle degeneration.

Inhibition of IRF4 in dendritic cells by PRR-independent and -dependent signals inhibit Th2 and promote Th17 responses.

Cyclic AMP (cAMP) is involved in many biological processes but little is known regarding its role in shaping immunity. Here we show that cAMP-PKA-CREB signaling (a pattern recognition receptor [PRR]-independent mechanism) regulates conventional type-2 Dendritic Cells (cDC2s) in mice and reprograms their Th17-inducing properties via repression of IRF4 and KLF4, transcription factors essential for cDC2-mediated Th2 induction. In mice, genetic loss of IRF4 phenocopies the effects of cAMP on Th17 induction and restoration of IRF4 prevents the cAMP effect. Moreover, curdlan, a PRR-dependent microbial product, activates CREB and represses IRF4 and KLF4, resulting in a pro-Th17 phenotype of cDC2s. These in vitro and in vivo results define a novel signaling pathway by which cDC2s display plasticity and provide a new molecular basis for the classification of novel cDC2 and cDC17 subsets. The findings also reveal that repressing IRF4 and KLF4 pathway can be harnessed for immuno-regulation.

High A20 expression negatively impacts survival in patients with breast cancer.

BACKGROUND: A20 protein has ubiquitin-editing activities and acts as a key regulator of inflammation and immunity. Previously, our group showed that A20 promotes tumor metastasis through multi-monoubiquitylation of SNAIL1 in basal-like breast cancer. Here, we investigated survival outcomes in patients with breast cancer according to A20 expression. PATIENTS AND METHODS: We retrospectively collected tumor samples from patients with breast cancer. Immunohistochemistry (IHC) with an A20-specific antibody was performed, and survival outcomes were analyzed. RESULTS: A20 expression was evaluated in 442 patients. High A20 expression was associated with advanced anatomical stage and young age. High A20 expression showed significantly inferior recurrence-free-survival and overall-survival (P<0.001 and P<0.001, respectively). Multivariate analysis showed that A20 was an independent prognostic marker for RFS (HRs: 2.324, 95% CIs: 1.446-3.736) and OS (HRs: 2.629, 95% CIs: 1.585-4.361). In human epidermal growth factor receptor 2 (HER2)-positive and triple negative breast cancer (TNBC) subtypes, high A20 levels were associated with poor OS. CONCLUSION: We found that A20 expression is a poor prognostic marker in breast cancer. The prognostic impact of A20 was pronounced in aggressive tumors, such as HER2-positive and TNBC subtypes. Our findings suggested that A20 may be a valuable target in patients with aggressive breast cancer.

TiCaPCON-Supported Pt- and Fe-Based Nanoparticles and Related Antibacterial Activity.

A rapid increase in the number of antibiotic-resistant bacteria urgently requires the development of new more effective yet safe materials to fight infection. Herein, we uncovered the contribution of different metal nanoparticles (NPs) (Pt, Fe, and their combination) homogeneously distributed over the surface of nanostructured TiCaPCON films in the total antibacterial activity toward eight types of clinically isolated bacterial strains (Escherichia coli K261, Klebsiella pneumoniae B1079k/17-3, Acinetobacter baumannii B1280A/17, Staphylococcus aureus no. 839, Staphylococcus epidermidis i5189-1, Enterococcus faecium Ya-235: VanA, E. faecium I-237: VanA, and E. coli U20) taking into account various factors that can affect bacterial mechanisms: surface chemistry and phase composition, wettability, ion release, generation of reactive oxygen species (ROS), potential difference and polarity change between NPs and the surrounding matrix, formation of microgalvanic couples on the sample surfaces, and contribution of a passive oxide layer, formed on the surface of films, to general kinetics of the NP dissolution. The results indicated that metal ion implantation and subsequent annealing significantly changed the chemistry of the TiCaPCON film surface. This, in turn, greatly affected the shedding of ions, ROS formation, potential difference between film components, and antibacterial activity. The presence of NPs was critical for ROS generation under UV or daylight irradiation. By eliminating the potential contribution of ions and ROS, we have shown that bacteria can be killed using direct microgalvanic interactions. The possibility of charge redistribution at the interfaces between Pt NPs and TiO2 (anatase and rutile), TiC, TiN, and TiCN components was demonstrated using density functional theory calculations. The TiCaPCON-supported Pt and Fe NPs were not toxic for lymphocytes and had no effect on the ability of lymphocytes to activate in response to a mitogen. This study provides new insights into understanding and designing of antibacterial yet biologically safe surfaces.

Block-Co-polymer-Assisted Synthesis of All Inorganic Highly Porous Heterostructures with Highly Accessible Thermally Stable Functional Centers.

Here, we propose a simple approach for the design of highly porous multicomponent heterostructures by infiltration of block-co-polymer templates with inorganic precursors in swelling solvents followed by gas-phase sequential infiltration synthesis and thermal annealing. This approach can prepare conformal coatings, free-standing membranes, and powders consisting of uniformly sized metal or metal oxide nanoparticles (NPs) well dispersed in a porous oxide matrix. We employed this new, versatile synthetic concept to synthesize catalytically active heterostructures of uniformly dispersed ∼4.3 nm PdO nanoparticles accessible through three-dimensional pore networks of the alumina support. Importantly, such materials reveal high resistance against sintering at 800 °C, even at relatively high loadings of NPs (∼10 wt %). At the same time, such heterostructures enable high mass transport due to highly interconnected nature of the pores. The surface of synthesized nanoparticles in the porous matrix is highly accessible, which enables their good catalytic performance in methane and carbon monoxide oxidation. In addition, we demonstrate that this approach can be utilized to synthesize heterostructures consisting of different types of NPs on a highly porous support. Our results show that swelling-based infiltration provides a promising route toward the robust and scalable synthesis of multicomponent structures.

Machine learning models based on the dimensionality reduction of standard automated perimetry data for glaucoma diagnosis.

INTRODUCTION: Visual field testing via standard automated perimetry (SAP) is a commonly used glaucoma diagnosis method. Applying machine learning techniques to the visual field test results, a valid clinical diagnosis of glaucoma solely based on the SAP data is provided. In order to reflect structural-functional patterns of glaucoma on the automated diagnostic models, we propose composite variables derived from anatomically grouped visual field clusters to improve the prediction performance. A set of machine learning-based diagnostic models are designed that implement different input data manipulation, dimensionality reduction, and classification methods. METHODS: Visual field testing data of 375 healthy and 257 glaucomatous eyes were used to build the diagnostic models. Three kinds of composite variables derived from the Garway-Heath map and the glaucoma hemifield test (GHT) sector map were included in the input variables in addition to the 52 SAP visual filed locations. Dimensionality reduction was conducted to select important variables so as to alleviate high-dimensionality problems. To validate the proposed methods, we applied four classifiers-linear discriminant analysis, naïve Bayes classifier, support vector machines, and artificial neural networks-and four dimensionality reduction methods-Pearson correlation coefficient-based variable selection, Markov blanket variable selection, the minimum redundancy maximum relevance algorithm, and principal component analysis- and compared their classification performances. RESULTS: For all tested combinations, the classification performance improved when the proposed composite variables and dimensionality reduction techniques were implemented. The combination of total deviation values, the GHT sector map, support vector machines, and Markov blanket variable selection obtains the best performance: an area under the receiver operating characteristic curve (AUC) of 0.912. CONCLUSION: A glaucoma diagnosis model giving an AUC of 0.912 was constructed by applying machine learning techniques to SAP data. The results show that dimensionality reduction not only reduces dimensions of the input space but also enhances the classification performance. The variable selection results show that the proposed composite variables from visual field clustering play a key role in the diagnosis model.

ENOblock inhibits the pathology of diet-induced obesity.

Obesity is a medical condition that impacts on all levels of society and causes numerous comorbidities, such as diabetes, cardiovascular disease, and cancer. We assessed the suitability of targeting enolase, a glycolysis pathway enzyme with multiple, secondary functions in cells, to treat obesity. Treating adipocytes with ENOblock, a novel modulator of these secondary 'moonlighting' functions of enolase, suppressed the adipogenic program and induced mitochondrial uncoupling. Obese animals treated with ENOblock showed a reduction in body weight and increased core body temperature. Metabolic and inflammatory parameters were improved in the liver, adipose tissue and hippocampus. The mechanism of ENOblock was identified as transcriptional repression of master regulators of lipid homeostasis (Srebp-1a and Srebp-1c), gluconeogenesis (Pck-1) and inflammation (Tnf-α and Il-6). ENOblock treatment also reduced body weight gain, lowered cumulative food intake and increased fecal lipid content in mice fed a high fat diet. Our results support the further drug development of ENOblock as a therapeutic for obesity and suggest enolase as a new target for this disorder.

Effect of the Micelle Opening in Self-assembled Amphiphilic Block Co-polymer Films on the Infiltration of Inorganic Precursors.

Infiltration of the polymer templates with inorganic precursors using the selective vapor-phase infiltration approach, or sequential infiltration synthesis (SIS), allows the design of materials with advanced properties. Swelling of the block co-polymer (BCP) templates enables the additional control of the structure, porosity, and thickness of the composite or inorganic materials. Here, we use the highly precise quartz crystal microbalance (QCM) technique to investigate quantitatively the effect of the micelle opening by swelling and inorganic precursor infiltrating on the evolution of porosity in amphiphilic BCPs. We show that swelling of the polystyrene- block-poly-4-vinyl pyridine (PS- b-P4VP) BCP in ethanol at 75 °C occurs rapidly and results in a stable polymer structure in 30 min. By using an alumina model system, we found that swelling enables access to all available polar domains of the PS- b-P4VP film leading to an increase in the SIS-infiltrated alumina mass as compared to the nonswelled BCP layer. Our results demonstrate that swelling of the 110 nm thick BCP template results in the formation of 192 nm thick alumina films with 2 times larger alumina mass and 4 times larger effective pore volume than in case of the nonswelled sample. In the case of the thicker polymer template, the difference due to swelling becomes even more substantial because the fraction of accessible polymer is increased much more than in thin films. Our findings provide important insights into the mechanism of the infiltration of the inorganic precursors into swelled and nonswelled, spin-coated BCP templates enabling the design of highly porous thick ceramic films by SIS.