Synergistic short-term and long-term effects of TGF-β1 and 3 on collagen production in differentiating myoblasts

C2C12 myoblasts differentiate into myofibroblasts via the TGF-β1 signaling pathway mediated by Fibulin2

Myoblasts play a critical role in the regeneration of skeletal muscle following injury. It has been reported that local elevation of transforming growth factor-β1 (TGF-β1) after skeletal muscle injury induces differentiation of myoblasts into myofibroblasts. However, the mechanisms underlying this differentiation process remain incompletely understood. In this study, we found that Fibulin2 expression significantly increases in myoblasts in response to TGF-β1 stimulation. Elevated Fibulin2 levels enhance the expression of fibrotic markers. Conversely, downregulation of Fibulin2 in myoblasts inhibits the upregulation of fibrotic markers induced by TGF-β1 stimulation. Extracellular secretion of Fibulin2 activates the TGF-β1-Smad2 pathway, thereby promoting the upregulation of fibrotic markers. Hence, Fibulin2 and TGF-β1 form a positive feedback loop that facilitates differentiation of myoblasts into myofibroblasts.

The effect of pre-existing sarcopenia on outcomes of critically ill patients treated for COVID-19

Background

Sarcopenia, defined by a loss of skeletal muscle mass and function, has been identified as a prevalent condition associated with poor clinical outcome among critically ill patients. This study aims to evaluate the impact of pre-existing sarcopenia on outcomes in critically ill patients with acute respiratory failure (ARF) due to COVID-19.

Material and Methods

A retrospective study was carried out on COVID-19 patients admitted to intensive care. Pre-existing sarcopenia was assessed using early CT scans. Clinical outcomes, including duration of high-flow oxygenation (HFO), mechanical ventilation (MV), length of hospital stay (LOS) and ICU mortality, were evaluated according to sarcopenia status.

Results

Among the studied population, we found a high prevalence (75 patients, 50%) of pre-existing sarcopenia, predominantly in older male patients. Pre-existing sarcopenia significantly impacted HFO duration (6.8 (+/-4.4) vs. 5 (+/-2.9) days; p=0.005) but did not significantly affect MV requirement (21 (28%) vs. 23 (37.3%); p=185), MV duration (7 vs. 10 days; p=0.233), ICU mortality (12 (16%) vs. 10 (13.3 %); p=0.644) or hospital LOS (27 vs. 25 days; p=0.509). No differences in outcomes were observed between sarcopenic and non-sarcopenic obese patients.

Conclusions

Pre-existing sarcopenia in critically ill COVID-19 patients is associated with longer HFO duration but not with other adverse outcomes. Further research is needed to elucidate the mechanisms and broader impact of sarcopenia on septic critically ill patient outcomes.

Reduced myotube diameter induced by combined inhibition of transforming growth factor-β type I receptors Acvr1b and Tgfbr1 is associated with enhanced β1-syntrophin expression

Simultaneous inhibition of transforming growth factor-β (TGF-β) type I receptors Acvr1b and Tgfbr1 signalling has been associated with excessive skeletal muscle hypertrophy in vivo. However, it remains unclear whether the increased muscle mass in vivo is a direct result of inhibition of intracellular TGF-β signalling or whether this is an indirect effect of an altered extracellular anabolic environment. Here, we tested whether individual or simultaneous knockdown of TGF-β type I receptors in C2C12 myotubes was sufficient to induce muscle hypertrophy. The expression levels of TGF-β type I receptors Acvr1b and Tgfbr1 in myotubes were knocked down individually or in combination in the absence or presence of TGF-β1 and myostatin. Knocking down either Acvr1b or Tgfbr1 did not significantly change cell phenotype. Unexpectedly, simultaneous knockdown of both receptors reduced C2C12 myotube diameter, mRNA expression levels of Hgf, Ccn2 and Mymx with or without TGF-β1 and myostatin administration. In spite of decreased phosphorylation of Smad2/3, phosphorylation of P70S6K was reduced. In addition, the gene expression level of β1-syntrophin (Sntb1), which encodes a protein associated with the dystrophin-glycoprotein complex, was increased. Parallel experiments where Sntb1 gene expression was reduced showed an increase in myotube diameter and fusion of C2C12 myoblasts. Together, these results indicate that the knockdown of both TGF-β type I receptors reduced myotube diameter. This atrophic effect was attributed to reduced protein synthesis signalling and an increased expression of β1-syntrophin. These results have implications for our fundamental understanding of how TGF-β signalling regulates skeletal muscle size.

Protective role of transforming growth factor-Β3 (TGF-Β3) in the formation of radiation-induced capsular contracture around a breast implant: In vivo experimental study

Postmastectomy radiotherapy causes capsular contracture due to fibroproliferation of the capsular tissue around the implant. In fibrosis, unlike normal wound healing, structural and functional disorders are observed in the tissues caused by excessive/irregular accumulation of extracellular matrix proteins. It has been reported that transforming growth factor-β3 (TGF-β3) prevents and reverses fibrosis in various tissues or provides scarless healing with its antifibrotic effect. Additionally, TGF-β3 has been shown to reduce fibrosis in radiotherapy-induced fibrosis syndrome. However, no study in the literature investigates the effects of exogenously applied TGF-β3 on capsular contracture in aesthetic or reconstructive breast implant application. TGF-β3, which has a very short half-life, has low bioavailability with parenteral administration. Within the scope of this study, free TGF-β3 was loaded into the nanoparticles to increase its low bioavailability and extend its duration of action by providing controlled release. The aim of this study is to investigate the preventive/improving effects of radiation induced capsular contracture using chitosan film formulations containing TGF-β3 loaded poly(lactic-co-glycolic acid)-b-poly(ethylene glycol) (PLGA-b-PEG) nanoparticles in implant-based breast reconstruction. In the characterization studies of nanoparticles, the particle size and zeta potential of the TGF-β3-loaded PLGA-b-PEG nanoparticle formulation selected to be used in the treatment group were found to be 123.60 ± 2.09 nm and -34.87 ± 1.42 mV, respectively. The encapsulation efficiency of the formulation was calculated as 99.91 %. A controlled release profile was obtained in in vitro release studies. Chitosan film formulations containing free TGF-β3 or TGF-β3-loaded PLGA-b-PEG nanoparticles were used in in vivo studies. In animal studies, rats were randomly distributed into 6 groups (n = 8) as sham, implant, implant + radiotherapy, implant + radiotherapy + chitosan film containing unloaded nanoparticles, implant + radiotherapy + chitosan film containing free TGF-β3, implant + radiotherapy + chitosan film containing TGF-β3 loaded nanoparticle. In all study groups, a 2 cm incision was made along the posterior axillary line at the thoracic vertebral level in rats to reach the lateral edge of the latissimus dorsi. The fascial attachment to the chest wall was then bluntly dissected to create a pocket for the implants. In the treatment groups, the wound was closed after films were placed on the outer surface of the implants. After administering prophylactic antibiotics, rats were subjected to irradiation with 10 Gy photon beams targeted to each implant site. Each implant and the surrounding excised tissue were subjected to the necessary procedures for histological (capsule thickness, cell density), immunohistochemical, and biochemical (α-SMA, vimentin, collagen type I and type III, TGF-β1 and TGF-β3: expression level/protein level) examinations. It was determined that the levels of TGF-β1 and TGF-β3 collagen type III, which decreased as a result of radiotherapy, were brought to the control level with free TGF-β3 film and TGF-β3 nanoparticle film formulations. Histological analyses, consistent with biochemical analyses, showed that thick collagen and fibrosis, which increased with radiotherapy, were brought to the control level with free TGF-β3 film and TGF-β3 nanoparticle film treatments. In biochemical analyses, the decrease in thick collagen was compatible with the decrease in the collagen type I/type III ratio in the free TGF-β3 film and TGF-β3 nanoparticle film groups. Changes in protein expression show that TGF-β3 loaded nanoparticles are more successful than free TGF-β3 in wound healing. In line with these results and the literature, it is thought that the balance of TGF-β1 and TGF-β3 should be maintained to ensure scarless wound healing with no capsule contracture.

Smoking cessation only partially reverses cardiac metabolic and structural remodeling in mice

AIMS

Active cigarette smoking is a major risk factor for chronic obstructive pulmonary disease that remains elevated after cessation. Skeletal muscle dysfunction has been well documented after smoking, but little is known about cardiac adaptations to cigarette smoking. The underlying cellular and molecular cardiac adaptations, independent of confounding lifestyle factors, and time course of reversibility by smoking cessation remain unclear. We hypothesized that smoking negatively affects cardiac metabolism and induces local inflammation in mice, which do not readily reverse upon 2-week smoking cessation.

METHODS

Mice were exposed to air or cigarette smoke for 14 weeks with or without 1- or 2-week smoke cessation. We measured cardiac mitochondrial respiration by high-resolution respirometry, cardiac mitochondrial density, abundance of mitochondrial supercomplexes by electrophoresis, and capillarization, fibrosis, and macrophage infiltration by immunohistology, and performed cardiac metabolome and lipidome analysis by mass spectrometry.

RESULTS

Mitochondrial protein, supercomplex content, and respiration (all p < 0.03) were lower after smoking, which were largely reversed within 2-week smoking cessation. Metabolome and lipidome analyses revealed alterations in mitochondrial metabolism, a shift from fatty acid to glucose metabolism, which did not revert to control upon smoking cessation. Capillary density was not different after smoking but increased after smoking cessation (p = 0.02). Macrophage infiltration and fibrosis (p < 0.04) were higher after smoking but did not revert to control upon smoking cessation.

CONCLUSIONS

While cigarette-impaired smoking-induced cardiac mitochondrial function was reversed by smoking cessation, the remaining fibrosis and macrophage infiltration may contribute to the increased risk of cardiovascular events after smoking cessation.

PROTAC-biomacromolecule conjugates for precise protein degradation in cancer therapy: A review

Proteolysis targeting chimera (PROTAC) technology is a promising new mode of targeted protein degradation with significant transformative implications for the clinical treatment of different diseases. Nevertheless, while this technology offers numerous advantages, on-target off-tumour toxicity in healthy cells remains a major challenge for clinical application in cancer therapy. Strategies are presently being explored to optimize degradation activity with cellular selectivity to minimize undesirable side effects. PROTAC-antibody conjugates and PROTAC-aptamer conjugates are unique innovations that combine PROTACs and biomacromolecules. These novel PROTAC-biomacromolecule conjugates (PBCs) can enhance the targetability of PROTACs and reduce their off-target side-effects. The combination of potent PROTACs and highly safe biomacromolecules will pioneer an emerging trend in targeted protein degradation. In our review, we have summarized recent advances in PBCs, discussed current challenges, and outlooked opportunities for future research in the field.

A review: analysis of technical challenges in cultured meat production and its commercialization

The cultured meat technology has developed rapidly in recent years, but there are still many technical challenges that hinder the large-scale production and commercialization of cultured meat. Firstly, it is necessary to lay the foundation for cultured meat production by obtaining seed cells and maintaining stable cell functions. Next, technologies such as bioreactors are used to expand the scale of cell culture, and three-dimensional culture technologies such as scaffold culture or 3D printing are used to construct the three-dimensional structure of cultured meat. At the same time, it can reduce production costs by developing serum-free medium suitable for cultured meat. Finally, the edible quality of cultured meat is improved by evaluating food safety and sensory flavor, and combining ethical and consumer acceptability issues. Therefore, this review fully demonstrates the current development status and existing technical challenges of the cultured meat production technology with regard to the key points described above, in order to provide research ideas for the industrial production of cultured meat.

Chitin-based hydrogel loaded with bFGF and SDF-1 for inducing endogenous mesenchymal stem cells homing to improve stress urinary incontinence

Nonoperative treatments for Stress Urinary Incontinence (SUI) represent an ideal treatment method. Mesenchymal stem cell (MSCs) treatment is a new modality, but there is a lack of research in the field of gynecological pelvic floor and no good method to induce internal MSC homing to improve SUI. Herein, we develop an injectable and self-healing hydrogel derived from β-chitin which consists of an amino group of quaternized β-chitin (QC) and an aldehyde group of oxidized dextran (OD) between the dynamic Schiff base linkage.it can carry bFGF and SDF-1a and be injected into the vaginal forearm of mice in a non-invasive manner. It provides sling-like physical support to the anterior vaginal wall in the early stages. In the later stage, it slowly releasing factors and promoting the homing of MSCs in vivo, which can improve the local microenvironment, increase collagen deposition, repair the tissue around urethra and finally improve SUI (Scheme 1). This is the first bold attempt in the field of pelvic floor using hydrogel mechanical support combined with MSCs homing and the first application of chitin hydrogel in gynecology. We think the regenerative medicine approach based on bFGF/SDF-1/chitin hydrogel may be an effective non-surgical approach to combat clinical SUI.

Molecular characterization and expression of TGFβRI and TGFβRII and its association with litter size in Tibetan sheep

BACKGROUNDS

Transforming growth factor-β (TGF-β) type I receptor (TGFβRI) and type II receptor (TGFβRII) are the members of the TGFβ superfamily, which are potent regulators of cell proliferation and differentiation in many organ systems, and they play key roles in multiple aspects of follicle development.

OBJECTIVES

We aimed to explore the characterization, expression analysis of TGFβRI and TGFβRII genes, and the association with litter size in Tibetan sheep.

METHODS

In this study, we cloned the complete coding sequences of TGFβRI and TGFβRII genes in Tibetan sheep and analyzed their genomic structures.

RESULTS

The results showed that percentages of sequences homology of the two proteins in Tibetan sheep were the most similar to Ovis aries (100%), followed by Bos mutus (99%). The RT-qPCR showed that two genes were expressed widely in the different tissues of Tibetan sheep. The TGFβRI expression was the highest in the lung (p < 0.05), followed by the spleen and ovary (p < 0.05). The TGFβRII expression was significantly higher in uterus than that in lung and ovary (p < 0.05). In addition, the χ² test indicated that all ewes in the population were in Hardy-Weinberg equilibrium, and the population was in medium or low polymorphic information content status. We also found four Single Nucleotide Polymorphism (SNPs), g.9414A > G, g.28881A > G, g.28809T > C, g.10429G > A in sheep TGFβRI gene and g.63940C > T, g.63976C > T, g.64538C > T, g.64504T > A in TGFβRII gene. Three genotypes, except for g.64504T > A, and three haplotypes were identified in each gene. linkage disequilibrium analysis indicated that there was strong linkage disequilibrium in each gene. The association analysis showed that the four SNPs of TGFβRI were associated with litter size (p < 0.05), and g.63940C > T of TGFβRII was confirmed to be associated with litter size (p < 0.05).

CONCLUSIONS

Based on these preliminary results, we can assume that TGFβ receptors (TGFβRI and TGFβRII) may play an important role in sheep reproduction.

Hydralazine plays an immunomodulation role of pro-regeneration in a mouse model of spinal cord injury

Spinal cord injury (SCI) results in severe motor and sensory dysfunction with no effective therapy. Spinal cord debris (sp) from injured spinal cord evokes secondary SCI continuously. We and other researchers have previously clarified that it is mainly bone marrow derived macrophages (BMDMs) infiltrating in the lesion epicenter to clear sp, rather than local microglia. Unfortunately, the pro-inflammatory phenotype of these infiltrating BMDMs is predominant which impairs wound healing. Hydralazine, as a potent vasodilator and scavenger of acrolein, has protective effects in many diseases. Hydralazine is also confirmed to promote motor function and hypersensitivity in SCI rats through scavenging acrolein. However, few studies have explored the effects of hydralazine on immunomodulation, as well as spontaneous pain and emotional response, the important syndromes in clinical patients. It remains unclear whether hydralazine affects infiltrating BMDMs after SCI. In this study, we targeted BMDMs to explore the influence of hydralazine on immune cells in a mouse model of SCI, and also investigated the contribution of polarized BMDMs to hydralazine-induced neurological function recovery after SCI in male mice. The adult male mice underwent T10 spinal cord compression. The results showed that in addition to improving motor function and hypersensitivity, hydralazine relieved SCI-induced spontaneous pain and emotional response, which is a newly discovered function of hydralazine. Hydralazine inhibited the recruitments of pro-inflammatory BMDMs and educated infiltrated BMDMs to a more reparative phenotype involving in multiple biological processes associated with SCI pathology, including immune/inflammation response, neurogenesis, lipid metabolism, oxidative stress, fibrosis formation, and angiogenesis, etc. As an overall effect, hydralazine-treated BMDMs loaden with sp partially rescued neurological function after SCI. It is concluded that hydralazine plays an immunomodulation role of educating pro-inflammatory BMDMs to a more reparative phenotype; and hydralazine-educated BMDMs contribute to hydralazine-induced improvement of neurological function in SCI mice, which provides support for drug and cell treatment options for SCI therapy.

The NLRP3 inflammasome contributes to inflammation-induced morphological and metabolic alterations in skeletal muscle

BACKGROUND

Systemic inflammation is associated with skeletal muscle atrophy and metabolic dysfunction. Although the nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome contributes to cytokine production in immune cells, its role in skeletal muscle is poorly understood. Here, we studied the link between inflammation, NLRP3, muscle morphology, and metabolism in in vitro cultured C2C12 myotubes, independent of immune cell involvement.

METHODS

Differentiated C2C12 myotubes were treated with lipopolysaccharide (LPS; 0, 10, and 100-200 ng/mL) to induce activation of the NLRP3 inflammasome with and without MCC950, a pharmacological inhibitor of NLRP3-induced IL-1β production. We assessed markers of the NLRP3 inflammasome, cell diameter, reactive oxygen species, and mitochondrial function.

RESULTS

NLRP3 gene expression and protein concentrations increased in a time-dependent and dose-dependent manner. Intracellular IL-1β concentration significantly increased (P < 0.0001), but significantly less with MCC950 (P = 0.03), suggestive of moderate activation of the NLRP3 inflammasome in cultured myotubes upon LPS stimulation. LPS suppressed myotube growth after 24 h (P = 0.03), and myotubes remained smaller up to 72 h (P = 0.0009). Exposure of myotubes to IL-1β caused similar alterations in cell morphology, and MCC950 mitigated these LPS-induced differences in cell diameter. NLRP3 appeared to co-localize with mitochondria, more so upon exposure to LPS. Mitochondrial reactive oxygen species were higher after LPS (P = 0.03), but not after addition of MCC950. Myotubes had higher glycolytic rates, and mitochondria were more fragmented upon LPS exposure, which was not altered by MCC950 supplementation.

CONCLUSIONS

LPS-induced activation of the NLRP3 inflammasome in cultured myotubes contributes to morphological and metabolic alterations, likely due to its mitochondrial association.

Production of scaffold-free cell-based meat using cell sheet technology

In the production of cell-based meat, it is desirable to reduce animal-derived materials as much as possible to meet the challenges of sustainability. Here, we demonstrate the “cell sheet-based meat”: scaffold-free cell-based meat using cell sheet technology and characterize its texture and nutrients. Bovine myoblast cell sheets were prepared using temperature-responsive culture dishes (TRCDs) and 10 stacked cell sheets to fabricate three-dimensional tissue of 1.3–2.7 mm thickness. Hardness was increased by incubation on the TRCD and was further increased by boiling as is characteristic of natural meat. The wet weight percentage of total protein in the cell sheet was about half that of beef. In this method, large-sized items of cell sheet-based meat were also created by simply scaling up the TRCD. This method promises an environment-friendly food product.

Skeletal muscle alterations in patients with acute Covid-19 and post-acute sequelae of Covid-19

Skeletal muscle-related symptoms are common in both acute coronavirus disease (Covid)-19 and post-acute sequelae of Covid-19 (PASC). In this narrative review, we discuss cellular and molecular pathways that are affected and consider these in regard to skeletal muscle involvement in other conditions, such as acute respiratory distress syndrome, critical illness myopathy, and post-viral fatigue syndrome. Patients with severe Covid-19 and PASC suffer from skeletal muscle weakness and exercise intolerance. Histological sections present muscle fibre atrophy, metabolic alterations, and immune cell infiltration. Contributing factors to weakness and fatigue in patients with severe Covid-19 include systemic inflammation, disuse, hypoxaemia, and malnutrition. These factors also contribute to post-intensive care unit (ICU) syndrome and ICU-acquired weakness and likely explain a substantial part of Covid-19-acquired weakness. The skeletal muscle weakness and exercise intolerance associated with PASC are more obscure. Direct severe acute respiratory syndrome coronavirus (SARS-CoV)-2 viral infiltration into skeletal muscle or an aberrant immune system likely contribute. Similarities between skeletal muscle alterations in PASC and chronic fatigue syndrome deserve further study. Both SARS-CoV-2-specific factors and generic consequences of acute disease likely underlie the observed skeletal muscle alterations in both acute Covid-19 and PASC.

Developments of CRBN-based PROTACs as potential therapeutic agents

Protease-targeted chimeras (PROTACs) are a new technology that is receiving much attention in the treatment of diseases. The mechanism is to inhibit protein function by hijacking the ubiquitin E3 ligase for protein degradation. Heterogeneous bifunctional PROTACs contain a ligand for recruiting E3 ligase, a linker, and another ligand to bind to the target protein for degradation. A variety of small-molecule PROTACs (CRBN, VHL, IAPs, MDM2, DCAF15, DCAF16, and RNF114-based PROTACs) have been identified so far. In particular, CRBN-based PROTACs (e.g., ARV-110 and ARV-471) have received more attention for their promising therapeutic intervention. To date, CRBN-based PRTOACs have been extensively explored worldwide and have excelled not only in cancer diseases but also in cardiovascular diseases, immune diseases, neurodegenerative diseases, and viral infections. In this review, we will provide a comprehensive update on the latest research progress in CRBN-based PRTOACs area. Following the criteria, such as disease area and drug target class, we will present the degradants in alphabetical order by target. We also provide our own perspective on the future prospects and potential challenges facing PROTACs.

From the Matrix to the Nucleus and Back: Mechanobiology in the Light of Health, Pathologies, and Regeneration of Oral Periodontal Tissues

Among oral tissues, the periodontium is permanently subjected to mechanical forces resulting from chewing, mastication, or orthodontic appliances. Molecularly, these movements induce a series of subsequent signaling processes, which are embedded in the biological concept of cellular mechanotransduction (MT). Cell and tissue structures, ranging from the extracellular matrix (ECM) to the plasma membrane, the cytosol and the nucleus, are involved in MT. Dysregulation of the diverse, fine-tuned interaction of molecular players responsible for transmitting biophysical environmental information into the cell's inner milieu can lead to and promote serious diseases, such as periodontitis or oral squamous cell carcinoma (OSCC). Therefore, periodontal integrity and regeneration is highly dependent on the proper integration and regulation of mechanobiological signals in the context of cell behavior. Recent experimental findings have increased the understanding of classical cellular mechanosensing mechanisms by both integrating exogenic factors such as bacterial gingipain proteases and newly discovered cell-inherent functions of mechanoresponsive co-transcriptional regulators such as the Yes-associated protein 1 (YAP1) or the nuclear cytoskeleton. Regarding periodontal MT research, this review offers insights into the current trends and open aspects. Concerning oral regenerative medicine or weakening of periodontal tissue diseases, perspectives on future applications of mechanobiological principles are discussed.