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Specialized connective tissues, including bone and adipose tissues, control various physiological activities, including mineral and energy homeostasis. However, the identity of stem cells maintaining these tissues throughout adulthood remains elusive. By conducting genetic lineage tracing and cell depletion experiments in newly generated knock-in Cre/CreER

A new Ni-HY zeolite with lamellar-crystals was prepared as a catalyst for phenanthrene hydrocracking. It showed significantly improved reactivity and BTX (benzene, toluene and xylene) selectivity (up to 99.1% and 75.6%, respectively), depending on a reasonable synergistic effect between its excellent internal-diffusion and the high-efficiency concerted catalysis of surface metal-Ni active sites and acid sites. In particular, compared with a conventional Ni-HY with diamond-shaped crystals, its significantly shortened diffusion-reaction path of the micropore system in the lamellar crystals greatly enhanced the diffusion-reaction efficiency of large-molecule phenanthrene and polycyclic intermediates and remarkably improved the utilization of both pores and internal reactive sites, powerfully promoting phenanthrene into benzene series conversion. The much decreased diffusion-residence time of benzene-series products in shortened channels also effectively weakened the further cracking loss of the benzene-ring, leading to enhanced BTX selectivity. Moreover, this shorter-channel Ni-HY catalyst with a higher external surface area and mesoporous volume also exhibited greatly improved catalytic stability attributed to its stronger capabilities of accommodating coke and resisting coke-deposition. The phenanthrene conversion of76.3% and the BTX yield of46.3% were obtained during a 60 h on-stream reaction.

ObjectiveTo explore the prevalence and patterns of multimorbidity in population with different genders and age ranges.DesignA cross-sectional study.SettingNational Health and Nutrition Examination Surveys database.Participants12 576 patients.Primary and secondary outcome measuresThe prevalence and patterns of multimorbidity.ResultsHigh cholesterol had the highest prevalence in all population (33.4 (95% CI: 32.0 to 34.9)) and males. In females ConclusionHypertension and high cholesterol were prevalent in all population, regardless of females and males. Hypertension and high cholesterol, arthritis and hypertension, and diabetes and hypertension were more likely to coexist. The findings of this study might help make plans for the management and primary care of people with one or more diseases.

Osteoarthritis (OA) is the most common joint disease. The surface of joint cartilage is a defensive and first affected structure of articular cartilage (AC) during the pathogenesis of OA. Alk5 signaling is critical for maintaining AC homeostasis, however, the role and underlying mechanism for the involvement of Alk5 signaling in the phenotypes of articular cartilage stem cells (ACSCs) at the surface of AC is still unclear. The role of Alk5 in OA development was explored using an ACSCs-specific Alk5-deficient (cKO) mouse model. Alterations in cartilage structure were evaluated histologically. Senescence was detected by SA-β-gal, while reactive oxygen species (ROS), MitoTracker, and LysoTracker staining were used to detect changes related to senescence. In addition, mice were injected intra-articularly with ganciclovir to limit the detrimental roles of senescent cells (SnCs). Alk5 cKO mice showed a decreased number of the slow-cell cycle cells and less lubricant secretion at the surface accompanied with drastically accelerated cartilage degeneration under ageing and surgically induced OA conditions. Further studies showed that Alk5 deficient ACSCs exhibited senescence-like manifestations including decreased proliferation and differentiation, more SA-β-gal-positive cells and ROS production, as well as significantly swollen mitochondria and lysosome breakdown. We further found that local limitation of the detrimental roles of SnCs can attenuate the development of posttraumatic OA. Taken together, our findings suggest that Alk5 signaling acts as an important regulator of the SnCs in the superficial layer during AC maintenance and OA initiation.

Systemic application of glucocorticoids is an essential anti-inflammatory and immune-modulating therapy for severe inflammatory or autoimmunity conditions. However, its long-term effects on articular cartilage of patients' health need to be further investigated. In this study, we studied the effects of dexamethasone (Dex) on the homeostasis of articular cartilage and the progress of destabilization of medial meniscus (DMM)-induced osteoarthritis (OA) in adult mice. Long-term administration of Dex aggravates the proteoglycan loss of articular cartilage and drastically accelerates cartilage degeneration under surgically induced OA conditions. In addition, Dex increases calcium content in calcified cartilage layer of mice and the samples from OA patients with a history of long-term Dex treatment. Moreover, long term usage of Dex results in decrease subchondral bone mass and bone density. Further studies showed that Dex leads to calcification of extracellular matrix of chondrocytes partially through activation of AKT, as well as promotes apoptosis of chondrocytes in calcified cartilage layer. Besides, Dex weakens the stress-response autophagy with the passage of time. Taken together, our data indicate that long-term application of Dex may predispose patients to OA and or even accelerate the OA disease progression development of OA patients.

Growing evidences suggest that the fibroblast growth factor/FGF receptor (FGF/FGFR) signaling has crucial roles in a multitude of processes during embryonic development and adult homeostasis by regulating cellular lineage commitment, differentiation, proliferation, and apoptosis of various types of cells. In this review, we provide a comprehensive overview of the current understanding of FGF signaling and its roles in organ development, injury repair, and the pathophysiology of spectrum of diseases, which is a consequence of FGF signaling dysregulation, including cancers and chronic kidney disease (CKD). In this context, the agonists and antagonists for FGF-FGFRs might have therapeutic benefits in multiple systems.

Regulated fibroblast growth factor (FGF) signalling is a prerequisite for the correct development and homeostasis of articular cartilage, as evidenced by the fact that aberrant FGF signalling contributes to the maldevelopment of joints and to the onset and progression of osteoarthritis. Of the four FGF receptors (FGFRs 1-4), FGFR1 and FGFR3 are strongly implicated in osteoarthritis, and FGFR1 antagonists, as well as agonists of FGFR3, have shown therapeutic efficacy in mouse models of spontaneous and surgically induced osteoarthritis. FGF18, a high affinity ligand for FGFR3, is the only FGF-based drug currently in clinical trials for osteoarthritis. This Review covers the latest advances in our understanding of the molecular mechanisms that regulate FGF signalling during normal joint development and in the pathogenesis of osteoarthritis. Strategies for FGF signalling-based treatment of osteoarthritis and for cartilage repair in animal models and clinical trials are also introduced. An improved understanding of FGF signalling from a structural biology perspective, and of its roles in skeletal development and diseases, could unlock new avenues for discovery of modulators of FGF signalling that can slow or stop the progression of osteoarthritis.

CATSHL syndrome, characterized by camptodactyly, tall stature and hearing loss, is caused by loss-of-function mutations of fibroblast growth factor receptors 3 (FGFR3) gene. Most manifestations of patients with CATSHL syndrome start to develop in the embryonic stage, such as skeletal overgrowth, craniofacial abnormalities, however, the pathogenesis of these phenotypes especially the early maldevelopment remains incompletely understood. Furthermore, there are no effective therapeutic targets for this skeleton dysplasia. Methods: We generated fgfr3 knockout zebrafish by CRISPR/Cas9 technology to study the developmental mechanisms and therapeutic targets of CATSHL syndrome. Several zebrafish transgenic lines labeling osteoblasts and chondrocytes, and live Alizarin red staining were used to analyze the dynamical skeleton development in fgfr3 mutants. Western blotting, whole mount in situ hybridization, Edu labeling based cell proliferation assay and Wnt/β-catenin signaling antagonist were used to explore the potential mechanisms and therapeutic targets. Results: We found that fgfr3 mutant zebrafish, staring from early development stage, showed craniofacial bone malformation with microcephaly and delayed closure of cranial sutures, chondroma-like lesion and abnormal development of auditory sensory organs, partially resembling the clinical manifestations of patients with CATSHL syndrome. Further studies showed that fgfr3 regulates the patterning and shaping of pharyngeal arches and the timely ossification of craniofacial skeleton. The abnormal development of pharyngeal arch cartilage is related to the augmented hypertrophy and disordered arrangement of chondrocytes, while decreased proliferation, differentiation and mineralization of osteoblasts may be involved in the delayed maturation of skull bones. Furthermore, we revealed that deficiency of fgfr3 leads to enhanced IHH signaling and up-regulated canonical Wnt/β-catenin signaling, and pharmacological inhibition of Wnt/β-catenin could partially alleviate the phenotypes of fgfr3 mutants. Conclusions: Our study further reveals some novel phenotypes and underlying developmental mechanism of CATSHL syndrome, which deepens our understanding of the pathogenesis of CATSHL and the role of fgfr3 in skeleton development. Our findings provide evidence that modulation of Wnt/β-catenin activity could be a potential therapy for CATSHL syndrome and related skeleton diseases.

Osteoporosis, fractures, and other bone diseases or injuries represent serious health problems in modern society. A variety of treatments including drugs, surgeries, physical therapies, etc. have been used to prevent or delay the progression of these diseases/injuries with limited effects. Electromagnetic field (EMF) has been used to non-invasively treat bone diseases, such as fracture and osteoporosis, for many years. However, because a variety of cellular and molecular events can be affected by EMF with various parameters, the precise bioeffects and underlying mechanisms of specific EMF on bone cells are still obscure. Here, we summarize the common therapeutic parameters (frequency and intensity) of major types of EMF used to treat bone cells taken from 32 papers we selected from the PubMed database published in English from 1991 to 2018. Briefly, pulse EMF promotes the proliferation of osteoblasts when its frequency is 7.5-15 Hz or 50-75 Hz and the intensity is 0.40-1.55 mT or 3.8-4 mT. Sinusoidal EMF, with 0.9-4.8 mT and 45-60 Hz, and static magnetic field with 0.1-0.4 mT or 400 mT, can promote osteoblast differentiation and maturation. Finally, we summarize the latest advances on the molecular signaling pathways influenced by EMF in osteoblasts and osteoclasts. A variety of molecules such as adenosine receptors, calcium channels, BMP2, Notch, Wnt1, etc., can be influenced by EMF in osteoblasts. For osteoclasts, EMF affects RANK, NF-κB, MAPK, etc. We speculate that EMF with different frequencies and intensities exert distinct bioeffects on specific bone cells. More high-quality work is required to explore the detailed effects and underlying mechanisms of EMF on bone cells/skeleton to optimize the application of EMF on bone diseases/injuries. Bioelectromagnetics. 2020;41:263-278 © 2020 Bioelectromagnetics Society.

A comprehensive understanding of the cellular heterogeneity and molecular mechanisms underlying the development, homeostasis, and disease of human intervertebral disks (IVDs) remains challenging. Here, the transcriptomic landscape of 108 108 IVD cells was mapped using single-cell RNA sequencing of three main compartments from young and adult healthy IVDs, including the nucleus pulposus (NP), annulus fibrosus, and cartilage endplate (CEP). The chondrocyte subclusters were classified based on their potential regulatory, homeostatic, and effector functions in extracellular matrix (ECM) homeostasis. Notably, in the NP, a PROCR+ resident progenitor population showed enriched colony-forming unit-fibroblast (CFU-F) activity and trilineage differentiation capacity. Finally, intercellular crosstalk based on signaling network analysis uncovered that the PDGF and TGF-β cascades are important cues in the NP microenvironment. In conclusion, a single-cell transcriptomic atlas that resolves spatially regulated cellular heterogeneity together with the critical signaling that underlies homeostasis will help to establish new therapeutic strategies for IVD degeneration in the clinic.

Background Intervertebral disc degeneration (IVDD) can cause low back pain, a major public health concern. IVDD is characterized with loss of cells especially those in nucleus pulposus (NP), due to the limited proliferative potential and regenerative ability. Few studies, however, have been carried out to investigate the in vivo proliferation events of NP cells and the cellular contribution of a specific subpopulation of NP during postnatal growth or regeneration. Methods We generated FGFR3-3*Flag-IRES-GFP mice and crossed FGFR3-CreERT2 mice with Rosa26-mTmG, Rosa26-DTA and Rosa26-Confetti mice, respectively, to perform inducible genetic tracing studies. Results Expression of FGFR3 was found in the outer region of NP with co-localized expressions of proliferating markers. By fate mapping studies, FGFR3-positive (FGFR3+) NP cells were found proliferate from outer region to inner region of NP during postnatal growth. Clonal lineage tracing by Confetti mice and ablation of FGFR3·+ NP cells by DTA mice further revealed that the expansion of the FGFR3+ cells was required for the morphogenesis and homeostasis of postnatal NP. Moreover, in degeneration and regeneration model of mouse intervertebral disc, FGFR3+ NP cells underwent extensive expansion during the recovery stage. Conclusion Our present work demonstrates that FGFR3+ NP cells are novel subpopulation of postnatal NP with long-existing proliferative capacity shaping the adult NP structure and participating in the homeostasis maintenance and intrinsic repair of NP. These findings may facilitate the development of new therapeutic approaches for IVD regeneration.

Congenital scoliosis (CS) is a complex genetic disorder characterized by vertebral malformations. The precise etiology of CS is not fully defined. Here, we identify that mutation in dual serine/threonine and tyrosine protein kinase (dstyk) lead to CS-like vertebral malformations in zebrafish. We demonstrate that the scoliosis in dstyk mutants is related to the wavy and malformed notochord sheath formation and abnormal axial skeleton segmentation due to dysregulated biogenesis of notochord vacuoles and notochord function. Further studies show that DSTYK is located in late endosomal/lysosomal compartments and is involved in the lysosome biogenesis in mammalian cells. Dstyk knockdown inhibits notochord vacuole and lysosome biogenesis through mTORC1-dependent repression of TFEB nuclear translocation. Inhibition of mTORC1 activity can rescue the defect in notochord vacuole biogenesis and scoliosis in dstyk mutants. Together, our findings reveal a key role of DSTYK in notochord vacuole biogenesis, notochord morphogenesis and spine development through mTORC1/TFEB pathway., Congenital scoliosis is a complex genetic disorder characterized by vertebral malformation. Here, the authors demonstrate that loss of dstyk leads to scoliosis in zebrafish due to dysregulated biogenesis of notochord vacuoles and that DSTYK is required for lysosome biogenesis through mTORC1 regulation.

ObjectivesThis study aims to investigate the role and mechanism of FGFR3 in macrophages and their biological effects on the pathology of arthritis.MethodsMice with conditional knockout of FGFR3 in myeloid cells (R3cKO) were generated. Gait behaviours of the mice were monitored at different ages. Spontaneous synovial joint destruction was evaluated by digital radiographic imaging and μCT analysis; changes of articular cartilage and synovitis were determined by histological analysis. The recruitment of macrophages in the synovium was examined by immunostaining and monocyte trafficking assay. RNA-seq analysis, Western blotting and chemotaxis experiment were performed on control and FGFR3-deficient macrophages. The peripheral blood from non-osteoarthritis (OA) donors and patients with OA were analysed. Mice were treated with neutralising antibody against CXCR7 to investigate the role of CXCR7 in arthritis.ResultsR3cKO mice but not control mice developed spontaneous cartilage destruction in multiple synovial joints at the age of 13 months. Moreover, the synovitis and macrophage accumulation were observed in the joints of 9-month-old R3cKO mice when the articular cartilage was not grossly destructed. FGFR3 deficiency in myeloid cells also aggravated joint destruction in DMM mouse model. Mechanically, FGFR3 deficiency promoted macrophage chemotaxis partly through activation of NF-κB/CXCR7 pathway. Inhibition of CXCR7 could significantly reverse FGFR3-deficiency-enhanced macrophage chemotaxis and the arthritic phenotype in R3cKO mice.ConclusionsOur study identifies the role of FGFR3 in synovial macrophage recruitment and synovitis, which provides a new insight into the pathological mechanisms of inflammation-related arthritis.

Cartilage-hair hypoplasia (CHH) is an autosomal recessive metaphyseal chondrodysplasia characterized by bone dysplasia and many other highly variable features. The gene responsible for CHH is the RNA component of the mitochondrial RNA-processing endoribonuclease (RMRP) gene. Currently, the pathogenesis of osteochondrodysplasia and extraskeletal manifestations in CHH patients remains incompletely understood; in addition, there are no viable animal models for CHH. We generated an rmrp KO zebrafish model to study the developmental mechanisms of CHH. We found that rmrp is required for the patterning and shaping of pharyngeal arches. Rmrp mutation inhibits the intramembranous ossification of skull bones and promotes vertebrae ossification. The abnormalities of endochondral bone ossification are variable, depending on the degree of dysregulated chondrogenesis. Moreover, rmrp mutation inhibits cell proliferation and promotes apoptosis through dysregulating the expressions of cell-cycle- and apoptosis-related genes. We also demonstrate that rmrp mutation upregulates canonical Wnt/β-catenin signaling; the pharmacological inhibition of Wnt/β-catenin could partially alleviate the chondrodysplasia and increased vertebrae mineralization in rmrp mutants. Our study, by establishing a novel zebrafish model for CHH, partially reveals the underlying mechanism of CHH, hence deepening our understanding of the role of rmrp in skeleton development.

Objective: Scoliosis is a common disease characterized by spinal curvature with variable severities. There is no generally accepted theory about the physical origin of the spinal deformation of scoliosis. The aim of this study was to explore a new hypothesis suggesting that the curvatures in scoliosis may be associated with the imbalance growth between thoracic vertebral column and sternum. Methods: We undertook a comparative computed tomography (CT) based morphology study of thoracic vertebrae and sternum of patients with adolescent idiopathic scoliosis (AIS) and age-gender matched normal subjects. We further measured the ratios between the lengths of the sternum and thoracic vertebra of mice with deficiency of fibroblast growth factor receptor 3 (FGFR3), which exhibit scoliosis. Three-week-old C57BL/6J mice were used to generate bipedal and sternal growth plate injury model. Radiographs and histological images were obtained to observe the presence of sternal and spinal deformity. Results: There was a significant correlation between the severities of scoliosis and the ratios of the sternum to thoracic vertebral lengths. We also found that FGFR3 deficient mice showed smaller ratio of the sternum to thoracic vertebra lengths than that of the wild-type mice, which were similar with that of the AIS patients. Surgery-induced injuries of sternal growth plates can accelerate and aggravate the scoliosis in bipedal mice and imbalanced development of anterior and posterior thoracic occurred before the appearance of scoliosis. Conclusions: Our findings suggest that the imbalanced growth between the thoracic vertebral column and the sternum is an important causative factor for the pathogenesis of scoliosis including AIS. The translational potential of this article: Imbalanced growth between the thoracic vertebral column and the sternum is associated with scoliosis. Surgical or rehabilitation intervention for scoliosis should focus on all components involved in the pathogenesis of curvature to obtain better outcome. Keywords: Growth plate, Imbalanced growth, Scoliosis, Sternum, Vertebrae

Acquired heterotopic ossification (HO) is the extraskeletal bone formation after trauma. Various mesenchymal progenitors are reported to participate in ectopic bone formation. Here we induce acquired HO in mice by Achilles tenotomy and observe that conditional knockout (cKO) of fibroblast growth factor receptor 3 (FGFR3) in Col2+ cells promote acquired HO development. Lineage tracing studies reveal that Col2+ cells adopt fate of lymphatic endothelial cells (LECs) instead of chondrocytes or osteoblasts during HO development. FGFR3 cKO in Prox1+ LECs causes even more aggravated HO formation. We further demonstrate that FGFR3 deficiency in LECs leads to decreased local lymphatic formation in a BMPR1a-pSmad1/5-dependent manner, which exacerbates inflammatory levels in the repaired tendon. Local administration of FGF9 in Matrigel inhibits heterotopic bone formation, which is dependent on FGFR3 expression in LECs. Here we uncover Col2+ lineage cells as an origin of lymphatic endothelium, which regulates local inflammatory microenvironment after trauma and thus influences HO development via FGFR3-BMPR1a pathway. Activation of FGFR3 in LECs may be a therapeutic strategy to inhibit acquired HO formation via increasing local lymphangiogenesis., Different types of mesenchymal progenitors participate in ectopic bone formation. Here, the authors show Col2+ lineage cells adopt a lymphatic endothelium cell fate, which regulates local inflammatory microenvironment after trauma, thus influencing heterotopic ossification (HO) development via a FGFR3-BMPR1a pathway.

Systemic application of glucocorticoids is an essential anti-inflammatory and immune-modulating therapy for severe inflammatory or autoimmunity conditions. However, its long-term effects on articular cartilage of patients' health need to be further investigated. In this study, we studied the effects of dexamethasone (Dex) on the homeostasis of articular cartilage and the progress of destabilization of medial meniscus (DMM)-induced osteoarthritis (OA) in adult mice. Long-term administration of Dex aggravates the proteoglycan loss of articular cartilage and drastically accelerates cartilage degeneration under surgically induced OA conditions. In addition, Dex increases calcium content in calcified cartilage layer of mice and the samples from OA patients with a history of long-term Dex treatment. Moreover, long term usage of Dex results in decrease subchondral bone mass and bone density. Further studies showed that Dex leads to calcification of extracellular matrix of chondrocytes partially through activation of AKT, as well as promotes apoptosis of chondrocytes in calcified cartilage layer. Besides, Dex weakens the stress-response autophagy with the passage of time. Taken together, our data indicate that long-term application of Dex may predispose patients to OA and or even accelerate the OA disease progression development of OA patients.

Objective To explore the effect of dexamethasone (Dex) infusion on articular cartilage and the underlying mechanisms in vitro and in vivo. Methods Destabilization of medial meniscus (DMM)-induced OA mouse model was used in this study. The mice with Dex treatment were sacrificed and then the knee joint samples were obtained for pathological analysis. Mouse primary chondrocytes were isolated and cultured in the presence or absence of Dex, which were used for calcification analysis and western blot assay. Results Dex accelerated the loss of articular cartilage matrix in mice, while it aggravated the damage of cartilage in DMM-induced OA model at the late stage. The calcium content in calcified cartilage layer in the joints from Dex treated OA mice was significantly higher than that from control mice. Dex treatment enhanced mineralization of articular cartilage matrix and leaded to massive apoptosis of chondrocytes in OA model. In addition, Dex caused autophagy of chondrocytes in the early stage, which was decreased at the late stage of Dex treatment. Moreover, we found that the effect of Dex on the mineralization of articular cartilage matrix in mice was related to AKT activation. Conclusions Continuous infusion of Dex can enhance the calcification of cartilage via AKT activation and increase chondrocyte apoptosis through inhibiting autophagy, which aggravates the damage of articular cartilage and accelerates the progression of OA in vivo.

Apert syndrome (AS), the most severe form of craniosynostosis, is caused by missense mutations including Pro253Arg(P253R) of fibroblast growth factor receptor 2 (FGFR2), which leads to enhanced FGF/FGFR2-signaling activity. Surgical correction of the deformed skull is the typical treatment for AS. Because of constant maldevelopment of sutures, the corrective surgery is often executed several times, resulting in increased patient challenge and complications. Biological therapies targeting the signaling of mutant FGFR2 allele, in combination with surgery, may bring better outcome. Here we screened and found a small interfering RNA (siRNA) specifically targeting the Fgfr2-P253R allele, and we revealed that it inhibited osteoblastic differentiation and matrix mineralization by reducing the signaling of ERK1/2 and P38 in cultured primary calvarial cells and calvarial explants from Apert mice (Fgfr2+/P253R). Furthermore, AAV9 carrying short hairpin RNA (shRNA) (AAV9-Fgfr2-shRNA) against mutant Fgfr2 was delivered to the skulls of AS mice. Results demonstrate that AAV9-Fgfr2-shRNA attenuated the premature closure of coronal suture and the decreased calvarial bone volume of AS mice. Our study provides a novel practical biological approach, which will, in combination with other therapies, including surgeries, help treat patients with AS while providing experimental clues for the biological therapies of other genetic skeletal diseases. Keywords: craniosynostosis, Apert syndrome, Fgfr2, adeno-associated virus, RNAi, molecular therapy

Faulty bony repair causes dysrepair of injured growth plate cartilage and bone growth defects in children; however, the underlying mechanisms are unclear. Recently, we observed the prominent induction of neurotrophin‑3 (NT-3) and its important roles as an osteogenic and angiogenic factor promoting the bony repair. The current study investigated its roles in regulating injury site remodelling. In a rat tibial growth plate drill-hole injury repair model, NT-3 was expressed prominently in osteoblasts at the injury site. Recombinant NT-3 (rhNT-3) systemic treatment enhanced, but NT-3 immunoneutralization attenuated, expression of cartilage-removal proteases (MMP-9 and MMP-13), presence of bone-resorbing osteoclasts and expression of osteoclast protease cathepsin K, and remodelling at the injury site. NT-3 was also highly induced in cultured mineralizing rat bone marrow stromal cells, and the conditioned medium augmented osteoclast formation and resorptive activity, an ability that was blocked by presence of anti-NT-3 antibody. Moreover, NT-3 and receptor TrkC were induced during osteoclastogenesis, and rhNT-3 treatment activated TrkC downstream kinase Erk1/2 in differentiating osteoclasts although rhNT-3 alone did not affect activation of osteoclastogenic transcription factors NF-κB or NFAT in RAW264.7 osteoclast precursor cells. Furthermore, rhNT-3 treatment increased, but NT-3 neutralization reduced, expression of osteoclastogenic cytokines (RANKL, TNF-α and IL-1) in mineralizing osteoblasts and in growth plate injury site, and rhNT-3 augmented the induction of these cytokines caused by RANKL treatment in RAW264.7 cells. Thus, injury site osteoblast-derived NT-3 is important in promoting growth plate injury site remodelling, as it induces cartilage proteases for cartilage removal and augments osteoclastogenesis and resorption both directly (involving activing Erk1/2 and substantiating RANKL-induced increased expression of osteoclastogenic signals in differentiating osteoclasts) and indirectly (inducing osteoclastogenic signals in osteoblasts). Refereed/Peer-reviewed

Activation of transforming growth factor-β (TGF-β) signaling has been used to enhance healing of meniscal degeneration in several models. However, the exact role and molecular mechanism of TGF-β signaling in meniscus maintenance and degeneration are still not understood due to the absence of in vivo evidence. In this study, we found that the expression of activin receptor-like kinases 5 (ALK5) in the meniscus was decreased with the progression of age and/or osteoarthritis induced meniscal degeneration. Col2α1 positive cells were found to be specifically distributed in the superficial and inner zones of the anterior horn, as well as the inner zone of the posterior horn in mice, indicating that Col2α1-CreER(T2) mice can be a used for studying gene function in menisci. Furthermore, we deleted Alk5 in Col2α1 positive cells in meniscus by administering tamoxifen. Alterations in the menisci structure were evaluated histologically. The expression levels of genes and proteins associated with meniscus homeostasis and TGF-β signaling were analyzed by quantitative real-time PCR analysis (qRT-PCR) and immunohistochemistry (IHC). Our results revealed severe and progressive meniscal degeneration phenotype in 3- and 6-month-old Alk5 cKO mice compared with Cre-negative control, including aberrantly increased hypertrophic meniscal cells, severe fibrillation, and structure disruption of meniscus. qRT-PCR and IHC results showed that disruption of anabolic and catabolic homeostasis of chondrocytes may contribute to the meniscal degeneration phenotype observed in Alk5 cKO mice. Thus, TGF-β/ALK5 signaling plays a chondro-protective role in menisci homeostasis, in part, by inhibiting matrix degradation and maintaining extracellular matrix proteins levels in meniscal tissues.

It has been reported that overactivation of fibroblast growth factor receptor 1 (FGFR1) is an important characteristic found in most non-small cell lung cancer (NSCLC) samples. Here, we identified a FGFR1 inhibitory peptide R1-P2 and investigated its effects on the lung cancer cells growth and angiogenesis in vitro and in vivo. Our results demonstrate that R1-P2 bound to human FGFR1 protein, and efficiently blocked the binding of FGF2 to FGFR1 in A549 and NCI-H460 cells. Moreover, this peptide significantly decreased the proliferation, migration and invasion, but promoted the apoptosis in both cell lines. In addition, R1-P2 treatment effectively inhibited the tumor growth and neovascularization in nude mice with xenografted A549 cells, and R1-P2 also significantly inhibited the FGF2-induced angiogenesis in tube formation experiment and CAM model. We further demonstrated that R1-P2 suppressed lung tumor growth through anti-angiogenic and anti-proliferative activity. Our data may provide a novle leading molecule with potential application in the treatment of FGFR1 activation related lung cancers.

Temporomandibular joint osteoarthritis (TMJ OA) is a common degenerative disease with few effective disease-modifying treatments in the clinic. Fibroblast growth factor (FGF) signaling is implicated in articular cartilage homeostasis, but the functional roles of FGFR1 in TMJ OA remain largely unknown. In this study, we report that deletion of Fgfr1 in TMJ chondrocytes delayed TMJ OA progression in the age-associated spontaneous OA model and the abnormal dental occlusion OA model. Immunohistochemical staining revealed that Fgfr1 deficiency decreased the expressions of MMP13 (matrix metalloproteinase-13), ADAMTS5 (a disintegrin and metalloproteinase with thrombospondin motifs 5), and COL10A1 but increased aggrecan expression level in two TMJ OA models. Furthermore, our data show that inactivation of FGFR1 signaling may promote autophagic activity in TMJ. FGFR1 inhibitor decreased the expressions of Mmp13, Adamts5, and Runx2 in IL-1β-stimulated condylar chondrocytes, whereas autophagy inhibitors abrogated the protective effects of the FGFR1 inhibitor. Thus, our study indicates inactivated FGFR1 signaling ameliorates TMJ OA progression partially by promoting autophagic activity. Manipulation of this signaling may be a potential therapeutic approach to modify TMJ OA.

Apert syndrome is one of the most severe craniosynostoses, resulting from gain-of-function mutations in fibroblast growth factor receptor 2 (FGFR2). Previous studies have shown that gain-of-function mutations of FGFR2 (S252W or P253R) cause skull malformation of human Apert syndrome by affecting both chondrogenesis and osteogenesis, underscoring the key role of FGFR2 in bone development. However, the effects of FGFR2 on bone formation at the adult stage have not been fully investigated. To investigate the role of FGFR2 in bone formation, we generated mice with tamoxifen-inducible expression of mutant FGFR2 (P253R) at the adult stage. Mechanical bone marrow ablation (BMX) was performed in both wild-type and Fgfr2 mutant (MT) mice. Changes in newly formed trabecular bone were assessed by micro-computed tomography and bone histomorphometry. We found that MT mice exhibited increased trabecular bone formation and decreased bone resorption after BMX accompanied with a remarkable increase in bone marrow stromal cell recruitment and proliferation, osteoblast proliferation and differentiation, and enhanced Wnt/β-catenin activity. Furthermore, pharmacologically inhibiting Wnt/β-catenin signaling can partially reverse the increased trabecular bone formation and decreased bone resorption in MT mice after BMX. Our data demonstrate that gain-of-function mutation in FGFR2 exerts a Wnt/β-catenin-dependent anabolic effect on trabecular bone by promoting bone formation and inhibiting bone resorption at the adult stage. © 2017 American Society for Bone and Mineral Research.

The osteoarthritis (OA) progression is now considered to be related to inflammation. Anemonin (ANE) is a small natural molecule extracted from various kinds of Chinese traditional herbs and has been shown to inhibiting inflammation response. In this study, we examined whether ANE could attenuate the progression of OA via suppression of IL‐1β/NF‐κB pathway activation. Destabilization of the medial meniscus (DMM) was performed in 10‐week‐old male C57BL/6J mice. ANE was then intra‐articularly injected into joint capsule for 8 and 12 weeks. Human articular chondrocytes and cartilage explants challenged with interleukin‐1β (IL‐1β) were treated with ANE. We found that ANE delayed articular cartilage degeneration in vitro and in vivo. In particular, proteoglycan loss and chondrocyte hypertrophy were significantly decreased in ANE ‐treated mice compared with vehicle‐treated mice. ANE decreased the expressions of matrix metalloproteinase‐13 (MMP13), A disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5), collagen X (Col X) while increasing Aggrecan level in murine with DMM surgery. ANE treatment also attenuated proteoglycan loss in human cartilage explants treated with IL‐1β ex vivo. ANE is a potent protective molecule for OA; it delays OA progression by suppressing ECM loss and chondrocyte hypertrophy partially by suppressing IL‐1β/NF‐κB pathway activation.

Caution is necessary when using symptom or physical examination findings to localize the osteoporotic vertebral fractures (VFs) attributable to the discrepant colocalized relationship. Whether the location of symptoms or physical examination findings delineates the appropriate spinal range for imaging has not been thoroughly investigated for VFs. The present study aims to analyze the consistency between the fractural vertebrae location and the location suggested by patient-reported pain or physical examination findings. This observational study, following a prospective design, enrolled 358 patients with VFs. The locations of two symptoms (patient-reported back pain [P-RBP], radiating pain [RP]) and findings from two physical examinations (spinal palpation tenderness [SPT], axial spinal percussion pain [ASPP]) were used to locate the VF segments identified using whole-spine magnetic resonance imaging (MRI). The percentage of agreements and kappa coefficient were calculated. In 20.7% (74/358), the P-RBP site and VF segments were in the same location (kappa = 0.153); 21.2% (76/358) presented with concomitant RP in 93.4% (71/76) of whom the RP dermatome was colocalized with the VF segments (kappa = 0.924); 55.0% (197/358) and 23.2% (83/358) of patients presented with positive SPT and ASPP, respectively; and in 49.2% (97/197) and 96.4% (80/83) of patients with positive SPT (kappa = 0.435) and ASPP (kappa = 0.963), the positive finding and the VF segments were consistently colocalized. The positive finding of RP or ASPP is useful in determining the spinal range for imaging tests, while an MRI scan covering the whole thoracic and lumbar spine is necessary in VF-suspected patients with P-RBP or positive SPT, indicating that caution is necessary when using symptoms or physical examination findings to localize VFs.

Synovitis plays an important role in the pathogenesis of arthritis, which is closely related to the joint swell and pain of patients. The purpose of this study was to investigate the anti-inflammatory effects of pulsed electromagnetic fields (PEMF) on synovitis and its underlying mechanisms. Destabilization of the medial meniscus (DMM) model and air pouch inflammation model were established to induce synovitis in C57BL/6 mice. The mice were then treated by PEMF (pulse waveform, 1.5 mT, 75 Hz, 10% duty cycle). The synovitis scores as well as the levels of IL-1β and TNF-α suggested that PEMF reduced the severity of synovitis in vivo. Moreover, the proportion of neutrophils in the synovial-like layer was decreased, while the proportion of macrophages increased after PEMF treatment. In addition, the phagocytosis of apoptotic neutrophils by macrophages (efferocytosis) was enhanced by PEMF. Furthermore, the data from western blot assay showed that the phosphorylation of P38 was inhibited by PEMF. In conclusion, our current data show that PEMF noninvasively exhibits the anti-inflammatory effect on synovitis via upregulation of the efferocytosis in macrophages, which may be involved in the phosphorylation of P38.

Cartilage is an essential part of skeleton. It is a structural component of multiple tissues such as ears, nose and bronchial tubes, acting as template for bone growth and covering the ends of long bones at the joints. Fibroblast growth factor (FGF)/FGF receptor (FGFR) signaling is proved to play a vital role in the cartilage development, growth, maintenance and repair. Findings from patients and animal studies reveal that FGF signaling tightly regulates skeleton development mainly through its regulation of both endochondral and intramembranous ossification. FGF signaling plays an essential role in the endochondral ossification by regulating the growth plate chondrocytes. Manipulation of individual FGF signaling molecule causes or ameliorate articular cartilage degeneration in mouse osteoarthritis models, indicating its critical role in cartilage maintenance, and FGF signaling is a therapeutic target for osteoarthritis.