Two Types of Mouse Models for Sarcopenia Research: Senescence Acceleration and Genetic Modification Models

Sarcopenia leads to loss of skeletal muscle mass, quality, and strength due to aging; it was recently given a disease code (International Classification of Diseases, Tenth Revision, Clinical Modification, M62.84). As a result, in recent years, sarcopenia-related research has increased. In addition, various studies seeking to prevent and treat sarcopenia by identifying the various mechanisms related to the reduction of skeletal muscle properties have been conducted. Previous studies have identified muscle synthesis and breakdown; investigating them has generated evidence for preventing and treating sarcopenia. Mouse models are still the most useful ones for determining mechanisms underlying sarcopenia through correlations and interventions involving specific genes and their phenotypes. Mouse models used to study sarcopenia often induce muscle atrophy by hindlimb unloading, denervation, or immobilization. Though it is less frequently used, the senescence-accelerated mouse can also be useful for sarcopenia research. Herein, we discuss cases where senescence-accelerated and genetically engineered mouse models were used in sarcopenia research and different perspectives to use them.

Two Types of Mouse Models for Sarcopenia Research: Senescence Acceleration and Genetic Modification Models

Sarcopenia leads to loss of skeletal muscle mass, quality, and strength due to aging; it was recently given a disease code (International Classification of Diseases, Tenth Revision, Clinical Modification, M62.84). As a result, in recent years, sarcopenia-related research has increased. In addition, various studies seeking to prevent and treat sarcopenia by identifying the various mechanisms related to the reduction of skeletal muscle properties have been conducted. Previous studies have identified muscle synthesis and breakdown; investigating them has generated evidence for preventing and treating sarcopenia. Mouse models are still the most useful ones for determining mechanisms underlying sarcopenia through correlations and interventions involving specific genes and their phenotypes. Mouse models used to study sarcopenia often induce muscle atrophy by hindlimb unloading, denervation, or immobilization. Though it is less frequently used, the senescence-accelerated mouse can also be useful for sarcopenia research. Herein, we discuss cases where senescence-accelerated and genetically engineered mouse models were used in sarcopenia research and different perspectives to use them.

Draft genome of Semisulcospira libertina, a species of freshwater snail

Semisulcospira libertina, a species of freshwater snail, is widespread in East Asia. It is important as a food source. Additionally, it is a vector of clonorchiasis, paragonimiasis, metagonimiasis, and other parasites. Although S. libertina has ecological, commercial, and clinical importance, its whole-genome has not been reported yet. Here, we revealed the genome of S. libertina through de novo assembly. We assembled the whole-genome of S. libertina and determined its transcriptome for the first time using Illumina NovaSeq 6000 platform. According to the k-mer analysis, the genome size of S. libertina was estimated to be 3.04 Gb. Using RepeatMasker, a total of 53.68% of repeats were identified in the genome assembly. Genome data of S. libertina reported in this study will be useful for identification and conservation of S. libertina in East Asia.

Rodent Model of Muscular Atrophy for Sarcopenia Study

The hallmark symptom of sarcopenia is the loss of muscle mass and strength without the loss of overall body weight. Sarcopenia patients are likely to have worse clinical outcomes and higher mortality than do healthy individuals. The sarcopenia population shows an annual increase of ~0.8% in the population after age 50, and the prevalence rate is rapidly increasing with the recent worldwide aging trend. Based on International Classification of Diseases, Tenth Revision, a global classification of disease published by the World Health Organization, issued the disease code (M62.84) given to sarcopenia in 2016. Therefore, it is expected that the study of sarcopenia will be further activated based on the classification of disease codes in the aging society. Several epidemiological studies and meta-analyses have looked at the correlation between the prevalence of sarcopenia and several environmental factors. In addition, studies using cell lines and rodents have been done to understand the biological mechanism of sarcopenia. Laboratory rodent models are widely applicable in sarcopenia studies because of the advantages of time savings, cost saving, and various analytical applications that could not be used for human subjects. The rodent models that can be applied to the sarcopenia research are diverse, but a simple and fast method that can cause atrophy or aging is preferred. Therefore, we will introduce various methods of inducing muscular atrophy in rodent models to be applied to the study of sarcopenia.

Genes Expressed in Steroid-exposed Lens Epithelial Cells as Revealed by Polymerase Chain Reaction

Purpose@#We investigated the expression levels of 84 genes in dexamethasone-exposed human lens epithelial cells using polymerase chain reaction (PCR) array analysis. @*Methods@#The viability and motility of lens epithelial cells were examined after treatment with dexamethasone at 0.01, 0.1, and 1 mg/mL; Western blot was used to evaluate the expression levels of fibronectin, α-smooth muscle actin (α-SMA), and E-cadherin. After 24, 48, and 72 hours of dexamethasone treatment at 0.1 mg/mL, the expression levels of 84 growth factors were analyzed using PCR array. @*Results@#Cell viability did not change significantly at dexamethasone levels of 0.01 or 0.1 mg/mL, but decreased markedly at 1 mg/mL; motility increased in a concentration-dependent manner at 0.01 and 0.1 mg/mL. Western blot showed that fibronectin levels increased significantly at all dexamethasone concentrations tested; the α-SMA level increased only at 0.01 mg/mL, and E-cadherin levels decreased significantly at all tested concentrations. PCR showed that the levels of FGF1, FGF2, IL-11, regulators of apoptosis (GDNF, IL-1β, and NRG2), and regulators of cell differentiation (BMP5, FGF1, FGF2, and FGF5) decreased more than twofold, whereas the levels of FGF9 and FGF19 increased more than twofold. @*Conclusions@#PCR performed after exposure of lens epithelial cells to dexamethasone may identify the genes involved in the development of steroid-induced cataracts.

Overexpression of Neuron-Specific Enolase as a Prognostic Factor in Patients with Gastric Cancer

PURPOSE: Enolase is a cytoplasmic enzyme that catalyzes the conversion of 2-phosphoglycerate to phosphoenolpyruvate in the glycolytic pathway. The aim of this study was to investigate whether the overexpression of neuron-specific enolase (NSE) can serve as a prognostic factor in patients with gastric cancer (GC). MATERIALS AND METHODS: To assess its prognostic value in GC, NSE expression was measured by immunohistochemistry in a clinically annotated tissue microarray comprising of 327 human GC specimens. Cytoplasmic NSE expression was scored from 0 to 4, reflecting the percentage of NSE-positive cells. RESULTS: In terms of histology as per the World Health Organization criteria (P=0.340), there were no differences between the NSE overexpression (NSE-OE) and NSE underexpression (NSE-UE) groups. The NSE-OE group showed a significantly lower rate of advanced GC (P<0.010), lymph node metastasis (P=0.010), advanced stage group (P<0.010), cancer-related death (P<0.010), and cancer recurrence (P<0.010). Additionally, a Kaplan-Meier survival analysis revealed that the NSE-OE group had longer cumulative survival times than the NSE-UE group (log-rank test, P<0.010). However, there were no significant differences in the serum levels of NSE expression in patients with GC and healthy volunteers (P=0.280). CONCLUSIONS: Patients with NSE overexpressing GC tissues showed better prognostic results, implying that NSE could be a candidate biomarker of GC.

Myeloid deletion of SIRT1 suppresses collagen-induced arthritis in mice by modulating dendritic cell maturation

The type III histone deacetylase silent information regulator 1 (SIRT1) is an enzyme that is critical for the modulation of immune and inflammatory responses. However, the data on its role in rheumatoid arthritis (RA) are limited and controversial. To better understand how SIRT1 regulates adaptive immune responses in RA, we evaluated collagen-induced arthritis (CIA) in myeloid cell-specific SIRT1 knockout (mSIRT1 KO) and wild-type (WT) mice. Arthritis severity was gauged on the basis of clinical, radiographic and pathologic scores. Compared with their WT counterparts, the mSIRT1 KO mice exhibited less severe arthritis, which was less destructive to the joints. The expression levels of inflammatory cytokines, matrix metalloproteinases and ROR-γT were also reduced in the mSIRT1 KO mice compared with the WT mice and were paralleled by reductions in the numbers of Th1 and Th17 cells and CD80- or CD86-positive dendritic cells (DCs). In addition, impaired DC maturation and decreases in the Th1/Th17 immune response were observed in the mSIRT1 KO mice. T-cell proliferation was also investigated in co-cultures with antigen-pulsed DCs. In the co-cultures, the DCs from the mSIRT1 KO mice showed decreases in T-cell proliferation and the Th1/Th17 immune response. In this study, myeloid cell-specific deletion of SIRT1 appeared to suppress CIA by modulating DC maturation. Thus, a careful investigation of DC-specific SIRT1 downregulation is needed to gauge the therapeutic utility of agents targeting SIRT1 in RA.

Cytoprotective Mechanism of Cyanidin and Delphinidin against Oxidative Stress-Induced Tenofibroblast Death

Age-related rotator cuff tendon degeneration is related to tenofibroblast apoptosis. Anthocyanins reduce oxidative stress-induced apoptotic cell death in tenofibroblasts. The current study investigated the presence of cell protective effects in cyanidin and delphinidin, the most common aglycon forms of anthocyanins. We determined whether these anthocyanidins have antiapoptotic and antinecrotic effects in tenofibroblasts exposed to H₂O₂, and evaluated their biomolecular mechanisms. Both cyanidin and delphinidin inhibited H₂O₂-induced apoptosis in a dose-dependent manner. However, at concentrations of 100 μg/ml or greater, delphinidin showed cytotoxicity against tenofibroblasts and a decreased antinecrotic effect. Cyanidin and delphinidin both showed inhibitory effects on the H₂O₂-induced increase in intracellular ROS formation and the activation of ERK1/2 and JNK. In conclusion, both cyanidin and delphinidin have cytoprotective effects on cultured tenofibroblasts exposed to H₂O₂. These results suggest that cyanidin and delphinidin are both beneficial for the treatment of oxidative stress-mediated tenofibroblast cell death, but their working concentrations are different.

Inhibitory Effects for Rheumatoid Arthritis of Dietary Supplementation with Resveratrol in Collagen-induced Arthritis

OBJECTIVE: Resveratrol is well-known for its anti-inflammatory, anti-oxidant effects on several diseases. We investigated whether dietary supplementation with resveratrol may suppress joint inflammation and destruction in a mouse model of collagen-induced arthritis (CIA). METHODS: Mice were randomly divided into two groups; CIA mice with normal diet-fed and CIA mice fed a 0.05% resveratrol diet. The effect of resveratrol on arthritis was assessed by clinical scoring system. The plain radiographs of paws were obtained to evaluate the effects on preventing bone destruction. Joint inflammation, cartilage damage, and osteoclastic bone resorption were checked by staining with H&E, Safranin-O, and tartrate resistant acid phosphatase (TRAP). Levels of pro-inflammatory cytokines were checked by enzyme-linked immunosorbent assay. The level of expression of nuclear factor (NF)-kappaB was measured by electrophoretic mobility shift assay (EMSA). RESULTS: Dietary supplementation with resveratrol led to mitigated severity of arthritis compared to the normal diet group (6.7+/-0.8 vs. 2.7+/-0.6, p<0.01). Resveratrol-fed mice showed decreased bone destruction on radiograph (3.4+/-0.3 vs. 2.0+/-0.2, p<0.01), and showed significantly inhibited pathological changes (inflammation 2.0+/-0.3 vs.3.2+/-0.2, p<0.01; cartilage damage 1.5+/-0.3 vs. 3.2+/-0.2, p<0.01; pannus formation 1.4+/-0.3 vs. 3.0+/-0.3, p<0.01; erosion; 1.4+/-0.2 vs. 3.3+/-0.3, p<0.01). Generation of TRAP-positive osteoclasts was inhibited in the resveratrol-fed mice (55.3+/-12.7 vs. 3.27+/-0.8, p<0.01). Resveratrol-fed mice showed decreased levels of tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6,monocyte chemoattractant protein 1, and the soluble receptor activator of NF-kappaB ligand in joint tissues and sera. Expression of NF-kappaB, measured by EMSA, was decreased in resveratrol-fed mice. CONCLUSION: Dietary supplementation with resveratrol mitigates inflammation and bone destruction in CIA mice.

Induction of Melanogenesis by Rapamycin in Human MNT-1 Melanoma Cells

BACKGROUND: Melanogenesis is one of the characteristic parameters of differentiation in melanocytes and melanoma cells. Specific inhibitors of phosphatidylinositol 3-kinase (PI3K), such as wortmannin and LY294002, stimulate melanin production in mouse and in human melanoma cells, suggesting that PI3K and mammalian target of rapamycin (mTOR) might be involved in the regulation of melanogenesis. OBJECTIVE: The involvement of the mTOR pathway in regulating melanogenesis was examined using human MNT-1 melanoma cells, and the effects of the potent inhibitor of mTOR, rapamycin, in the presence or absence of alpha-melanocyte-stimulating hormone (alpha-MSH) were evaluated. METHODS: In cells treated with rapamycin, cell viability, melanin content, and tyrosinase (TYR) activity were measured and compared with untreated controls. Protein levels of TYR, tyrosinase-related protein (TYRP)-1, TYRP-2, and microphthalmia-associated transcription factor (MITF) were also analyzed by Western blot. RESULTS: In rapamycin-treated cells, the melanin content increased concomitantly with an elevation in TYR activity, which plays a major role in melanogenesis. There was also an up-regulation of TYR, TYRP-1, and MITF proteins. Combined treatment with rapamycin or wortmannin and alpha-MSH increased melanogenesis more strongly than alpha-MSH alone. CONCLUSION: Rapamycin-induced melanin formation may be mediated through the up-regulation of TYR protein and activity. Furthermore, rapamycin and wortmannin, inhibitors of mTOR and PI3K, respectively, have co-stimulatory effects with alpha-MSH in enhancing melanogenesis in melanocyte cells.

COMP-Angiopoietin-1 Stimulates Synovial Proliferation but Suppresses Osteoclast by Enhancing Angiogenesis and Osteoblast Maturation in Collagen-Induced Arthritis

OBJECTIVE: Angiopoietin-1 (Ang1) is a potent angiogenic factor that can increase synovial angiogenesis and also enhance osteoblast maturation and bone formation. However, its role in rheumatoid arthritis (RA) has not been well documented. Thus, we investigated roles of Ang1 in collagen-induced arthritis (CIA). METHODS: A recombinant adenovirus carrying the gene that encodes either cartilage oligomeric matrix protein (AdCOMP)-Ang1 (a modified form of Ang1) or LacZ (AdLacZ) was injected intravenously into CIA mice. Clinical, radiological, histopathological, and immunofluorescent analyses were performed. Serum levels of receptor activators of nuclear factor kappaB ligand (RANKL) and osteoprotegerin (OPG) and expression of osteoblast maturation genes were analyzed. RESULTS: AdCOMP-Ang1-injected mice developed more severe inflammation than the AdLacZ-injected mice. However, there were no significant differences in cartilage damage and bone erosion. More PECAM-1-positive blood vessels were seen in the synovium of the AdCOMP-Ang1-injected mice than in those injected with AdLacZ. Interestingly, a lower number of TRAP-positive osteoclasts were observed in AdCOMP-Ang1-injected CIA mice than in the AdLacZ group when comparing sections obtained from joints showing similar synovial proliferation. The serum OPG/RANKL ratio and expression of osteoblast maturation genes, such as runt-related transcription factor 2, bone sialoprotein, type 1 collagen, osteopontin, and osterix, were significantly upregulated in the AdCOMP-Ang1 group. CONCLUSION: COMP-Ang1 facilitates arthritis onset and increases synovial inflammation, but enhances osteoblast maturation, which in turn inhibits osteoclastogenesis by increasing the OPG/RANKL ratio in CIA. Our results suggest that careful investigation is necessary to delineate the possible therapeutic use of COMP-Ang1 as an adjunctive agent, in combination with anti-inflammatory therapies, for the prevention of bone destruction in RA.

Role of IL-15 in Sepsis-Induced Skeletal Muscle Atrophy and Proteolysis / 결핵및호흡기질환

BACKGROUND: Muscle wasting in sepsis is associated with increased proteolysis. Interleukin-15 (IL-15) has been characterized as an anabolic factor for skeletal muscles. Our study aims to investigate the role of IL-15 in sepsis-induced muscle atrophy and proteolysis. METHODS: Mice were rendered septic either by cecal ligation and puncture or by intraperitoneal injection of lipopolysaccharide (LPS, 10 mg/kg i.p.). Expression of IL-15 mRNA and protein was determined by reverse transcriptase polymerase chain reaction and Western blot analysis in the control and septic limb muscles. C2C12 skeletal muscle cells were stimulated in vitro with either LPS or dexamethasone in the presence and absence of IL-15 and sampled at different time intervals (24, 48, or 72 hours). IL-15 (10microg/kg) was intraperitoneally administered 6 hours before sepsis induction and limb muscles were sampled after 24 hours of sepsis. Cathepsin L activity was determined to measure muscle proteolysis. Atrogin-1 and muscle-specific ring finger protein 1 (MuRF1) expressions in limb muscle protein lysates was analyzed. RESULTS: IL-15 mRNA expression was significantly lower in the limb muscles of septic mice compared to that of controls. Cathepsin L activity in C2C12 cells was significantly lower in presence of IL-15, when compared to that observed with individual treatments of LPS or dexamethasone or tumor necrosis factor alpha. Further, the limb muscles of mice pre-treated with IL-15 prior to sepsis induction showed a lower expression of atrogin-1 and MuRF1 than those not pre-treated. CONCLUSION: IL-15 may play a role in protection against sepsis-induced muscle wasting; thereby, serving as a potential therapeutic target for sepsis-induced skeletal muscle wasting and proteolysis.

In vivo Osteogenesis of Cultured Human Periosteal-derived Cells and Polydioxanone/Pluronic F127 Scaffold

Use of Peristeum as a Source of Endothelial-like Cells

Evaluation of osteogenic activity of periosteal-derived cells treated with inflammatory cytokines

INTRODUCTION: Skeletal homeostasis is normally maintained by the stability between bone formation by osteoblasts and bone resorption by osteoclasts. However, the correlation between the inflammatory reaction and osteoblastic differentiation of cultured osteoprogenitor cells has not been fully investigated. This study examined the effects of inflammatory cytokines on the osteoblastic differentiation of cultured human periosteal-derived cells. MATERIALS AND METHODS: Periosteal-derived cells were obtained from the mandibular periosteum and introduced into the cell culture. After passage 3, the periosteal-derived cells were further cultured in an osteogenic induction Dulbecco's modified Eagle's medium (DMEM) medium containing dexamethasone, ascorbic acid, and beta-glycerophosphate. In this culture medium, tumor necrosis factor (TNF)-alpha with different concentrations (0.1, 1, and 10 ng/mL) or interleukin (IL)-1beta with different concentrations (0.01, 0.1, and 1 ng/mL) were added. RESULTS: Both TNF-alpha and IL-1beta stimulated alkaline phosphatase (ALP) expression in the periosteal-derived cells. TNF-alpha and IL-1beta increased the level of ALP expression in a dose-dependent manner. Both TNF-alpha and IL-1beta also increased the level of alizarin red S staining in a dose-dependent manner during osteoblastic differentiation of cultured human periosteal-derived cells. CONCLUSION: These results suggest that inflammatory cytokines TNF-alpha and IL-1beta can stimulate the osteoblastic activity of cultured human periosteal-derived cells.

Proliferation and Functional Activity of Human Adipose Tissue-Derived CD146 Positive Endothelial Cells According to Culture Mediums

Use of Human Adipose Tissue as a Source of Endothelial Cells

STIMULATION OF OSTEOBLASTIC PHENOTYPES BY STRONTIUM IN PERIOSTEAL-DERIVED CELLS

VEGF-related Autocrine Growth in Periosteal-Derived Cells

PURPOSE: The development of a microvascularization is important for the homeostasis of normal bone. Vascular endothelial growth factor (VEGF) is one of the most important factors in vessel formation. The purpose of this study was to examine VEGF-related autocrine growth in periostealderived cells. MATERIALS AND METHODS: Periosteal-derived cells were obtained from mandibular periosteums and introduced into the cell culture. After passage 3, the periosteal-derived cells were further cultured for 21 days in an osteogenic inductive culture medium containing dexamethasone, ascorbic acid, and beta-glycerophosphate. RESULTS: The expression of four VEGF isoforms and VEGFRs was observed in periosteal-derived cells. Treatment with cultures with VEGFR-1 and VEGFR-2 Kinase Inhibitor inhibited osteoblastic differentiation and alkaline phosphatase (ALP) activity of periosteal-derived cells. In addition, exogenous VEGF treatment increased calcium content in the periosteal-derived cells. CONCLUSION: These results suggest that VEGF might act as an autocrine growth molecule during osteoblastic differentiation of cultured human periosteal-derived cells.

VEGF-related Autocrine Growth in Periosteal-Derived Cells

PURPOSE: The development of a microvascularization is important for the homeostasis of normal bone. Vascular endothelial growth factor (VEGF) is one of the most important factors in vessel formation. The purpose of this study was to examine VEGF-related autocrine growth in periostealderived cells. MATERIALS AND METHODS: Periosteal-derived cells were obtained from mandibular periosteums and introduced into the cell culture. After passage 3, the periosteal-derived cells were further cultured for 21 days in an osteogenic inductive culture medium containing dexamethasone, ascorbic acid, and beta-glycerophosphate. RESULTS: The expression of four VEGF isoforms and VEGFRs was observed in periosteal-derived cells. Treatment with cultures with VEGFR-1 and VEGFR-2 Kinase Inhibitor inhibited osteoblastic differentiation and alkaline phosphatase (ALP) activity of periosteal-derived cells. In addition, exogenous VEGF treatment increased calcium content in the periosteal-derived cells. CONCLUSION: These results suggest that VEGF might act as an autocrine growth molecule during osteoblastic differentiation of cultured human periosteal-derived cells.