In this study,Tremella fuciformis residues as raw material,dietary fibers from tremella were prepared by multiple enzymes.The structure of dietary fibers from tremella was studied by Fourier transform infrared(FTIR),X...In this study,Tremella fuciformis residues as raw material,dietary fibers from tremella were prepared by multiple enzymes.The structure of dietary fibers from tremella was studied by Fourier transform infrared(FTIR),X-ray diffraction analysis(XRD)and scanning electron microscopy(SEM).We analyzed their lipidlowering properties in vitro(water holding,oil holding swelling cholesterol and sodium cholate binding capacitises)and the hypolipidemic effects in mice.The results showed that tremella dietary fibers presented the infrared absorption spectrum characteristics of polysaccharides and the characteristic diffraction peaks of cellulose type I.SEM results indicated that the surface of insoluble dietary fiber(IDF)was porous,while the soluble dietary fiber(SDF)was relatively compact and spongy.IDF exhibited significantly higher water holding,oil holding,and swelling binding capacities than the corresponding SDF.However,SDF exhibited significantly higher viscosity than IDF.The results showed tremella dietary fibers were significant in swelling,water holding and oil holding,cholesterol and bile acids.In vivo experiment results in mice indicated that SDF has the best effect on hyperlipidemia mice than IDF and total dietary fiber(TDF).SDF showed that the total cholesterol(TC),triglyceride(TG)and low density lipoprotein cholesterol(LDL-C)contents dropped by 28.33%,18.65%,and 48.97%,respectively,while high density lipoprotein cholesterol(HDL-C)content increased by 43.80%.Compared with the high-fat control(HCM)group,the arteriosclerosis index(AI)and liver index(LI)of the SDF group mice showed significant differences,indicating that SDF has a good auxiliary effect of lowering blood lipids.The administration of tremella fibers improved the lipid metabolism disorderly situation of hyperlipidemia mice.These results provide a reference for further research and rational development of T.fuciformis.展开更多
Natural rubber(NR)is an irreplaceable biopolymer of economic and strategic importance owing to its unique physical and chemical properties.The Parárubber tree(Hevea brasiliensis(Willd.ex A.Juss.)Müll.Arg.)is...Natural rubber(NR)is an irreplaceable biopolymer of economic and strategic importance owing to its unique physical and chemical properties.The Parárubber tree(Hevea brasiliensis(Willd.ex A.Juss.)Müll.Arg.)is currently the exclusive commercial source of NR,and it is primarily grown in plantations restricted to the tropical and subtropical areas of Southeast Asia.However,current Parárubber production barely meets the sharply increasing global industrial demand for rubber.Petroleum-based synthetic rubber(SR)has been used to supplement the shortage of NR but its industrial performance is not comparable to that of NR.Thus,there is an urgent need to develop new productive rubber crops with broader environmental adaptability.This review summarizes the current research progress on alternative rubberproducing plants,including horticultural plants(Taraxacum kok-saghyz Rodin and Lactuca L.species),woody plants(Parthenium argentatum A.Gray and Eucommia ulmoides Oliv.),and other plant species with potential for NR production.With an emphasis on the molecular basis of NR biosynthesis revealed by a multi-omics approach,we highlight new integrative strategies and biotechnologies for exploring the mechanism of NR biosynthesis with a broader scope,which may accelerate the breeding and improvement of new rubber crops.展开更多
PPeritendinous adhesion formation(PAF)can substantially limit the range of motion of digits.However,the origin of myofibroblasts in PAF tissues is still unclear.In this study,we found that the concentration of active ...PPeritendinous adhesion formation(PAF)can substantially limit the range of motion of digits.However,the origin of myofibroblasts in PAF tissues is still unclear.In this study,we found that the concentration of active TGF-β1 and the numbers of macrophages,mesenchymal stromal cells(MSCs),and myofibroblasts in human and mouse adhesion tissues were increased.Furthermore,knockout of TGF-β1 in macrophages or TGF-β1R2 in MSCs inhibited PAF by reducing MSC and myofibroblast infiltration and collagenⅠandⅢdeposition,respectively.Moreover,we found that MSCs differentiated into myofibroblasts to form adhesion tissues.Systemic injection of the TGF-β–neutralizing antibody 1D11 during the granulation formation stage of PAF significantly reduced the infiltration of MSCs and myofibroblasts and,subsequently,PAF.These results suggest that macrophage-derived TGF-β1 recruits MSCs to form myofibroblasts in peritendinous adhesions.An improved understanding of PAF mechanisms could help identify a potential therapeutic strategy.展开更多
AIM:To investigate the prevalence of fatty liver discovered upon physical examination of Chinese patients and determine the associated clinical characteristics.METHODS:A total of 3433 consecutive patients who received...AIM:To investigate the prevalence of fatty liver discovered upon physical examination of Chinese patients and determine the associated clinical characteristics.METHODS:A total of 3433 consecutive patients who received physical examinations at the Huangpu Division of the First Affiliated Hospital at Sun Yat-sen University in Guangzhou,China from June 2010 to December2010 were retrospectively enrolled in the study.Results of biochemical tests,abdominal ultrasound,electrocardiography,and chest X-ray were collected.The diagnosis of fatty liver was made if a patient met any two of the three following ultrasonic criteria:(1)liver and kidney echo discrepancy and presence of an increased liver echogenicity(bright);(2)unclear intrahepatic duct structure;and(3)liver far field echo decay.RESULTS:The study population consisted of 2201males and 1232 females,with a mean age of 37.4±12.8 years.When all 3433 patients were considered,the overall prevalence of hyperlipidemia was 38.1%,of fatty liver was 26.0%,of increased alanine aminotransferase(ALT)and/or aspartate aminotransferase(AST)levels was 11.9%,of gallstone was 11.4%,of hyperglycemia was 7.3%,of hypertension was 7.1%,and of hyperuricemia was 6.2%.Of the 2605 patients who completed the abdominal ultrasonography exam,677(26.0%)were diagnosed with fatty liver and the prevalence was higher in males(32.5%vs females:15.3%,P<0.001).The overall prevalence of fatty liver increased with age,with the peak prevalence(39.5%)found in the 60 to 70-year-old age group.Among patients between the ages of 18 to 50-year-old,the prevalence of fatty liver was significantly higher in males(20.2%vs females:8.7%,P<0.001);the difference in prevalence between the two sexes in patients>50-year-old did not reach statistical significance.Only 430 of the patients diagnosed with fatty liver had complete information;among those,increased ALT and/or AST levels were detected in only 30%,with all disturbances being mild or moderate.In these 430 patients,the overall prevalence of hypertriglyceridemia was 31.4%,of mixed type hyperlipidemia was 20.9%,of hypercholesterolemia was 12.3%,of hyperglycemia was 17.6%,of hypertension was 16.0%,of hyperuricemia was 15.3%,and of gallstone was 14.4%.Again,the prevalences of hypertriglyceridemia and hyperuricemia were higher in males(hypertriglyceridemia,36.0%vs females:12.0%,P<0.05;hyperuricemia,17.3%vs females:7.2%,P<0.05);in contrast,however,the prevalences of mixed type hyperlipidemia and hypercholesterolemia was higher in females(mixed type hyperlipidemia,18.7% vs females:30.1%,P<0.05,hypercholesterolemia,9.5%vs females:24.1%,P<0.05).Finally,comparison of the fatty liver group to the non-fatty liver group showed that prevalences of hyperlipidemia,hyperglycemia,hypertension,and hyperuricemia were higher in the former(all P<0.01).CONCLUSION:A high prevalence of fatty liver is detected upon physical examination in Guangzhou,and the primary associated clinical findings are hyperlipidemia,hyperglycemia,hypertension,and hyperuricemia.展开更多
Ankylosing spondylitis(AS), a common type of spondyloarthropathy, is a chronic inflammatory autoimmune disease that mainly affects spine joints, causing severe, chronic pain;additionally, in more advanced cases, it ca...Ankylosing spondylitis(AS), a common type of spondyloarthropathy, is a chronic inflammatory autoimmune disease that mainly affects spine joints, causing severe, chronic pain;additionally, in more advanced cases, it can cause spine fusion. Significant progress in its pathophysiology and treatment has been achieved in the last decade. Immune cells and innate cytokines have been suggested to be crucial in the pathogenesis of AS, especially human leukocyte antigen(HLA)?B27 and the interleukin?23/17 axis.However, the pathogenesis of AS remains unclear. The current study reviewed the etiology and pathogenesis of AS, including genome-wide association studies and cytokine pathways. This study also summarized the current pharmaceutical and surgical treatment with a discussion of future potential therapies.展开更多
TGF-β 1–3 are unique multi-functional growth factors that are only expressed in mammals, and mainly secreted and stored as a latent complex in the extracellular matrix(ECM). The biological functions of TGF-β in adu...TGF-β 1–3 are unique multi-functional growth factors that are only expressed in mammals, and mainly secreted and stored as a latent complex in the extracellular matrix(ECM). The biological functions of TGF-β in adults can only be delivered after ligand activation, mostly in response to environmental perturbations. Although involved in multiple biological and pathological processes of the human body, the exact roles of TGF-β in maintaining stem cells and tissue homeostasis have not been well-documented until recent advances, which delineate their functions in a given context. Our recent findings, along with data reported by others, have clearly shown that temporal and spatial activation of TGF-β is involved in the recruitment of stem/progenitor cell participation in tissue regeneration/remodeling process, whereas sustained abnormalities in TGF-β ligand activation, regardless of genetic or environmental origin, will inevitably disrupt the normal physiology and lead to pathobiology of major diseases. Modulation of TGF-β signaling with different approaches has proven effective pre-clinically in the treatment of multiple pathologies such as sclerosis/fibrosis, tumor metastasis, osteoarthritis, and immune disorders. Thus, further elucidation of the mechanisms by which TGF-β is activated in different tissues/organs and how targeted cells respond in a context-dependent way can likely be translated with clinical benefits in the management of a broad range of diseases with the involvement of TGF-β.展开更多
Low back pain(LBP),as a leading cause of disability,is a common musculoskeletal disorder that results in major social and economic burdens.Recent research has identified inflammation and related signaling pathways as ...Low back pain(LBP),as a leading cause of disability,is a common musculoskeletal disorder that results in major social and economic burdens.Recent research has identified inflammation and related signaling pathways as important factors in the onset and progression of disc degeneration,a significant contributor to LBP.Inflammatory mediators also play an indispensable role in discogenic LBP.The suppression of LBP is a primary goal of clinical practice but has not received enough attention in disc research studies.Here,an overview of the advances in inflammation-related pain in disc degeneration is provided,with a discussion on the role of inflammation in IVD degeneration and pain induction.Puncture models,mechanical models,and spontaneous models as the main animal models to study painful disc degeneration are discussed,and the underlying signaling pathways are summarized.Furthermore,potential drug candidates,either under laboratory investigation or undergoing clinical trials,to suppress discogenic LBP by eliminating inflammation are explored.We hope to attract more research interest to address inflammation and pain in IDD and contribute to promoting more translational research.展开更多
There is currently no effective medical treatment for temporomandibular joint osteoarthritis(TMJ-OA) due to a limited understanding of its pathogenesis. This study was undertaken to investigate the key role of transfo...There is currently no effective medical treatment for temporomandibular joint osteoarthritis(TMJ-OA) due to a limited understanding of its pathogenesis. This study was undertaken to investigate the key role of transforming growth factor-β(TGF-β)signalling in the cartilage and subchondral bone of the TMJ using a temporomandibular joint disorder(TMD) rat model, an ageing mouse model and a Camurati–Engelmann disease(CED) mouse model. In the three animal models, the subchondral bone phenotypes in the mandibular condyles were evaluated by μCT, and changes in TMJ condyles were examined by TRAP staining and immunohistochemical analysis of Osterix and p-Smad2/3. Condyle degradation was confirmed by Safranin O staining, the Mankin and OARSI scoring systems and type X collagen(Col X), p-Smad2/3 a and Osterix immunohistochemical analyses. We found apparent histological phenotypes of TMJ-OA in the TMD, ageing and CED animal models, with abnormal activation of TGF-βsignalling in the condylar cartilage and subchondral bone. Moreover, inhibition of TGF-β receptor I attenuated TMJ-OA progression in the TMD models. Therefore, aberrant activation of TGF-β signalling could be a key player in TMJ-OA development.展开更多
Degenerative disc disease(DDD) is associated with intervertebral disc degeneration of spinal instability. Here, we report that the cilia of nucleus pulposus(NP) cells mediate mechanotransduction to maintain anabolic a...Degenerative disc disease(DDD) is associated with intervertebral disc degeneration of spinal instability. Here, we report that the cilia of nucleus pulposus(NP) cells mediate mechanotransduction to maintain anabolic activity in the discs. We found that mechanical stress promotes transport of parathyroid hormone 1 receptor(PTH1 R) to the cilia and enhances parathyroid hormone(PTH) signaling in NP cells. PTH induces transcription of integrin α_vβ_6 to activate the transforming growth factor(TGF)-β-connective tissue growth factor(CCN2)-matrix proteins signaling cascade. Intermittent injection of PTH(iPTH) effectively attenuates disc degeneration of aged mice by direct signaling through NP cells, specifically improving intervertebral disc height and volume by increasing levels of TGF-β activity, CCN2, and aggrecan. PTH1 R is expressed in both mouse and human NP cells. Importantly,knockout PTH1 R or cilia in the NP cells results in significant disc degeneration and blunts the effect of PTH on attenuation of aged discs. Thus, mechanical stress-induced transport of PTH1 R to the cilia enhances PTH signaling, which helps maintain intervertebral disc homeostasis, particularly during aging, indicating therapeutic potential of iPTH for DDD.展开更多
The vast osteocytic network is believed to orchestrate bone metabolic activity in response to mechanical stimuli through production of sclerostin, RANKL, and osteoprotegerin(OPG). However, the mechanisms of osteocyte ...The vast osteocytic network is believed to orchestrate bone metabolic activity in response to mechanical stimuli through production of sclerostin, RANKL, and osteoprotegerin(OPG). However, the mechanisms of osteocyte mechanotransduction remain poorly understood. We've previously shown that osteocyte mechanosensitivity is encoded through unique intracellular calcium (Ca^(2+) ) dynamics. Here, by simultaneously monitoring Ca^(2+) and actin dynamics in single cells exposed to fluid shear flow, we detected actin network contractions immediately upon onset of flow-induced Ca^(2+) transients, which were facilitated by smooth muscle myosin and further confirmed in native osteocytes ex vivo. Actomyosin contractions have been linked to the secretion of extracellular vesicles(EVs), and our studies demonstrate that mechanical stimulation upregulates EV production in osteocytes through immunostaining for the secretory vesicle marker Lysosomal-associated membrane protein 1(LAMP1) and quantifying EV release in conditioned medium, both of which are blunted when Ca^(2+) signaling was inhibited by neomycin. Axial tibia compression was used to induce anabolic bone formation responses in mice, revealing upregulated LAMP1 and expected downregulation of sclerostin in vivo. This load-related increase in LAMP1 expression was inhibited in neomycin-injected mice compared to vehicle.Micro-computed tomography revealed significant load-related increases in both trabecular bone volume fraction and cortical thickness after two weeks of loading, which were blunted by neomycin treatment. In summary, we found mechanical stimulation of osteocytes activates Ca^(2+) -dependent contractions and enhances the production and release of EVs containing bone regulatory proteins. Further, blocking Ca^(2+) signaling significantly attenuates adaptation to mechanical loading in vivo, suggesting a critical role for Ca^(2+) -mediated signaling in bone adaptation.展开更多
Survival of children with chronic medical illnesses is leading to an increase in secondary osteoporosis due to impaired peak bone mass(PBM).Insulin-like growth factor type 1(IGF-1) levels correlate with the pattern of...Survival of children with chronic medical illnesses is leading to an increase in secondary osteoporosis due to impaired peak bone mass(PBM).Insulin-like growth factor type 1(IGF-1) levels correlate with the pattern of bone mass accrual and many chronic illnesses are associated with low IGF-1 levels.Reduced serum levels of IGF-1 minimally affect the integrity of the skeleton,whereas recent studies suggest that skeletal IGF-I regulates PBM.To determine the role of IGF-1 in postnatal bone mass accrual regardless of source,we established an inducible type 1 Igf receptor Cre/lox knockout mouse model,in which the type 1 Igf receptor was deleted inducibely in the mesenchymal stem cells(MSCs) from 3-7 weeks of age.The size of the mouse was not affected as knockout and wild type mice had similar body weights and nasoanal and femoral lengths.However,bone volume and trabecular bone thickness were decreased in the secondary spongiosa of female knockout mice relative to wild type controls,indicating that IGF-1 is critical for bone mass.IGF-1 signaling in MSCs in vitro has been implicated to be involved in both migration to the bone surface and differentiation into bone forming osteoblasts.To clarify the exact role of IGF-1 in bone,we found by immunohistochemical analysis that a similar number of Osterix-positive osteoprogenitors were on the bone perimeter,indicating migration of MSCs was not affected.Most importantly,56% fewer osteocalcin-positive mature osteoblasts were present on the bone perimeter in the secondary spongiosa in knockout mice versus wild type littermates.These in vivo data demonstrate that the primary role of skeletal IGF-1 is for the terminal differentiation of osteoprogenitors,but refute the role of IGF-1 in MSC migration in vivo.Additionally,these findings confirm that impaired IGF-1 signaling in bone MSCs is sufficient to impair bone mass acquisition.展开更多
Parathyroid hormone(PTH) regulates bone remodeling by activating PTH type 1 receptor(PTH1R) in osteoblasts/osteocytes. Insulinlike growth factor type 1(IGF-1) stimulates mesenchymal stem cell differentiation to osteob...Parathyroid hormone(PTH) regulates bone remodeling by activating PTH type 1 receptor(PTH1R) in osteoblasts/osteocytes. Insulinlike growth factor type 1(IGF-1) stimulates mesenchymal stem cell differentiation to osteoblasts. However, little is known about the signaling mechanisms that regulates the osteoblast-to-osteocyte transition. Here we report that PTH and IGF-I synergistically enhance osteoblast-to-osteocyte differentiation. We identified that a specific tyrosine residue, Y494, on the cytoplasmic domain of PTH1R can be phosphorylated by insulin-like growth factor type I receptor(IGF1R) in vitro. Phosphorylated PTH1R localized to the barbed ends of actin filaments and increased actin polymerization during morphological change of osteoblasts into osteocytes.Disruption of the phosphorylation site reduced actin polymerization and dendrite length. Mouse models with conditional ablation of PTH1R in osteoblasts demonstrated a reduction in the number of osteoctyes and dendrites per osteocyte, with complete overlap of PTH1R with phosphorylated-PTH1R positioning in osteocyte dendrites in wild-type mice. Thus, our findings reveal a novel signaling mechanism that enhances osteoblast-to-osteocyte transition by direct phosphorylation of PTH1R by IGF1R.展开更多
Lipoprotein receptor-related protein 6(LRP6) plays a critical role in skeletal development and homeostasis in adults. However, the role of LRP6 in mesenchymal stem cells(MSCs), skeletal stem cells that give rise to os...Lipoprotein receptor-related protein 6(LRP6) plays a critical role in skeletal development and homeostasis in adults. However, the role of LRP6 in mesenchymal stem cells(MSCs), skeletal stem cells that give rise to osteoblastic lineage, is unknown. In this study, we generated mice lacking LRP6 expression specifically in nestin1MSCs by crossing nestin-Cre mice with LRP6floxmice and investigated the functional changes of bone marrow MSCs and skeletal alterations. Mice with LRP6 deletion in nestin1cells demonstrated reductions in body weight and body length at 1 and 3 months of age. Bone architecture measured by microCT(mCT) showed a significant reduction in bone mass in both trabecular and cortical bone of homozygous and heterozygous LRP6mutant mice. A dramatic reduction in the numbers of osteoblasts but much less significant reduction in the numbers of osteoclasts was observed in the mutant mice. Osterix1osteoprogenitors and osteocalcin1osteoblasts significantly reduced at the secondary spongiosa area, but only moderately decreased at the primary spongiosa area in mutant mice. Bone marrow MSCs from the mutant mice showed decreased colony forming, cell viability and cell proliferation. Thus, LRP6 in bone marrow MSCs is essential for their survival and proliferation, and therefore, is a key positive regulator for bone formation during skeletal growth and remodeling.展开更多
Intervertebral disc(IVD) degeneration is the leading cause of disability with no disease-modifying treatment.IVD degeneration is associated with instable mechanical loading in the spine, but little is known about how ...Intervertebral disc(IVD) degeneration is the leading cause of disability with no disease-modifying treatment.IVD degeneration is associated with instable mechanical loading in the spine, but little is known about how mechanical stress regulates nucleus notochordal(NC) cells to maintain IVD homeostasis. Here we report that mechanical stress can result in excessive integrin α_vβ_6-mediated activation of transforming growth factor beta(TGFβ), decreased NC cell vacuoles, and increased matrix proteoglycan production, and results in degenerative disc disease(DDD). Knockout of TGFβ type II receptor(TβRII) or integrin α_v in the NC cells inhibited functional activity of postnatal NC cells and also resulted in DDD under mechanical loading.Administration of RGD peptide, TGFβ, and α_vβ_6-neutralizing antibodies attenuated IVD degeneration. Thus,integrin-mediated activation of TGFβ plays a critical role in mechanical signaling transduction to regulate IVD cell function and homeostasis. Manipulation of this signaling pathway may be a potential therapeutic target to modify DDD.展开更多
In the recent two decades, it has been well elucidated that receptor activator of nuclear factor-κB ligand (RANKL;also known as TNFSF11) binding to its receptor RANK (also known as TNFRSF11A) drives osteoclast develo...In the recent two decades, it has been well elucidated that receptor activator of nuclear factor-κB ligand (RANKL;also known as TNFSF11) binding to its receptor RANK (also known as TNFRSF11A) drives osteoclast development as the crucial signaling pathway.1-3 However, accumulating evidence also implies that osteoblastic RANKL regulates osteoblastogenesis.4-6 The studies “RANKL signaling in bone marrow mesenchymal stem cells negatively regulates osteoblastic bone formation” by Chen et al.展开更多
Prostaglandin E2(PGE2), a major cyclooxygenase-2(COX-2) product, is highly secreted by the osteoblast lineage in the subchondral bone tissue of osteoarthritis(OA) patients. However, NSAIDs, including COX-2 inhibitors,...Prostaglandin E2(PGE2), a major cyclooxygenase-2(COX-2) product, is highly secreted by the osteoblast lineage in the subchondral bone tissue of osteoarthritis(OA) patients. However, NSAIDs, including COX-2 inhibitors, have severe side effects during OA treatment. Therefore, the identification of novel drug targets of PGE2 signaling in OA progression is urgently needed. Osteoclasts play a critical role in subchondral bone homeostasis and OA-related pain. However, the mechanisms by which PGE2 regulates osteoclast function and subsequently subchondral bone homeostasis are largely unknown. Here, we show that PGE2 acts via EP4 receptors on osteoclasts during the progression of OA and OA-related pain. Our data show that while PGE2 mediates migration and osteoclastogenesis via its EP2 and EP4 receptors, tissue-specific knockout of only the EP4 receptor in osteoclasts(EP4 Lys M) reduced disease progression and osteophyte formation in a murine model of OA. Furthermore, OA-related pain was alleviated in the EP4 Lys M mice, with reduced Netrin-1 secretion and CGRP-positive sensory innervation of the subchondral bone. The expression of plateletderived growth factor-BB(PDGF-BB) was also lower in the EP4 Lys Mmice, which resulted in reduced type H blood vessel formation in subchondral bone. Importantly, we identified a novel potent EP4 antagonist, HL-43, which showed in vitro and in vivo effects consistent with those observed in the EP4 Lys Mmice. Finally, we showed that the Gαs/PI3 K/AKT/MAPK signaling pathway is downstream of EP4 activation via PGE2 in osteoclasts. Together, our data demonstrate that PGE2/EP4 signaling in osteoclasts mediates angiogenesis and sensory neuron innervation in subchondral bone, promoting OA progression and pain, and that inhibition of EP4 with HL-43 has therapeutic potential in OA.展开更多
Ankylosing spondylitis(AS)is chronic inflammatory arthritis with a progressive fusion of axial joints.Anti-inflammatory treatments such as anti-TNF-αantibody therapy suppress inflammation but do not effectively halt ...Ankylosing spondylitis(AS)is chronic inflammatory arthritis with a progressive fusion of axial joints.Anti-inflammatory treatments such as anti-TNF-αantibody therapy suppress inflammation but do not effectively halt the progression of spine fusion in AS patients.Here we report that the autoimmune inflammation of AS generates a microenvironment that promotes chondrogenesis in spine ligaments as the process of spine fusion.Chondrocyte differentiation was observed in the ligaments of patients with earlystage AS,and cartilage formation was followed by calcification.Moreover,a large number of giant osteoclasts were found in the inflammatory environment of ligaments and on bony surfaces of calcified cartilage.Resorption activity by these giant osteoclasts generated marrow with high levels of active TGF-β,which induced new bone formation in the ligaments.Notably,no Osterix+osteoprogenitors were found in osteoclast resorption areas,indicating uncoupled bone resorption and formation.Even at the late and maturation stages,the uncoupled osteoclast resorption in bony interspinous ligament activates TGF-βto induce the progression of ossification in AS patients.Osteoclast resorption of calcified cartilage-initiated ossification in the progression of AS is a similar pathologic process of acquired heterotopic ossification(HO).Our finding of cartilage formation in the ligaments of AS patients revealed that the pathogenesis of spinal fusion is a process of HO and explained why anti-inflammatory treatments do not slow ankylosing once there is new bone formation in spinal soft tissues.Thus,inhibition of HO formation,such as osteoclast activity,cartilage formation,or TGF-βactivity could be a potential therapy for AS.展开更多
基金financially supported by the Key Projects of the National Research and Development Program of China(2018YFD0400204)。
文摘In this study,Tremella fuciformis residues as raw material,dietary fibers from tremella were prepared by multiple enzymes.The structure of dietary fibers from tremella was studied by Fourier transform infrared(FTIR),X-ray diffraction analysis(XRD)and scanning electron microscopy(SEM).We analyzed their lipidlowering properties in vitro(water holding,oil holding swelling cholesterol and sodium cholate binding capacitises)and the hypolipidemic effects in mice.The results showed that tremella dietary fibers presented the infrared absorption spectrum characteristics of polysaccharides and the characteristic diffraction peaks of cellulose type I.SEM results indicated that the surface of insoluble dietary fiber(IDF)was porous,while the soluble dietary fiber(SDF)was relatively compact and spongy.IDF exhibited significantly higher water holding,oil holding,and swelling binding capacities than the corresponding SDF.However,SDF exhibited significantly higher viscosity than IDF.The results showed tremella dietary fibers were significant in swelling,water holding and oil holding,cholesterol and bile acids.In vivo experiment results in mice indicated that SDF has the best effect on hyperlipidemia mice than IDF and total dietary fiber(TDF).SDF showed that the total cholesterol(TC),triglyceride(TG)and low density lipoprotein cholesterol(LDL-C)contents dropped by 28.33%,18.65%,and 48.97%,respectively,while high density lipoprotein cholesterol(HDL-C)content increased by 43.80%.Compared with the high-fat control(HCM)group,the arteriosclerosis index(AI)and liver index(LI)of the SDF group mice showed significant differences,indicating that SDF has a good auxiliary effect of lowering blood lipids.The administration of tremella fibers improved the lipid metabolism disorderly situation of hyperlipidemia mice.These results provide a reference for further research and rational development of T.fuciformis.
基金This work was supported by the National Key Research and Development Program of China(2019YFD1002701-02)the National Natural Science Foundation of China(32170371)the Strategic Priority Research Program of Chinese Academy of Sciences(XDA24030503).
文摘Natural rubber(NR)is an irreplaceable biopolymer of economic and strategic importance owing to its unique physical and chemical properties.The Parárubber tree(Hevea brasiliensis(Willd.ex A.Juss.)Müll.Arg.)is currently the exclusive commercial source of NR,and it is primarily grown in plantations restricted to the tropical and subtropical areas of Southeast Asia.However,current Parárubber production barely meets the sharply increasing global industrial demand for rubber.Petroleum-based synthetic rubber(SR)has been used to supplement the shortage of NR but its industrial performance is not comparable to that of NR.Thus,there is an urgent need to develop new productive rubber crops with broader environmental adaptability.This review summarizes the current research progress on alternative rubberproducing plants,including horticultural plants(Taraxacum kok-saghyz Rodin and Lactuca L.species),woody plants(Parthenium argentatum A.Gray and Eucommia ulmoides Oliv.),and other plant species with potential for NR production.With an emphasis on the molecular basis of NR biosynthesis revealed by a multi-omics approach,we highlight new integrative strategies and biotechnologies for exploring the mechanism of NR biosynthesis with a broader scope,which may accelerate the breeding and improvement of new rubber crops.
基金supported in part by Fox and Necrosis funds from the Department of Orthopedic Surgery。
文摘PPeritendinous adhesion formation(PAF)can substantially limit the range of motion of digits.However,the origin of myofibroblasts in PAF tissues is still unclear.In this study,we found that the concentration of active TGF-β1 and the numbers of macrophages,mesenchymal stromal cells(MSCs),and myofibroblasts in human and mouse adhesion tissues were increased.Furthermore,knockout of TGF-β1 in macrophages or TGF-β1R2 in MSCs inhibited PAF by reducing MSC and myofibroblast infiltration and collagenⅠandⅢdeposition,respectively.Moreover,we found that MSCs differentiated into myofibroblasts to form adhesion tissues.Systemic injection of the TGF-β–neutralizing antibody 1D11 during the granulation formation stage of PAF significantly reduced the infiltration of MSCs and myofibroblasts and,subsequently,PAF.These results suggest that macrophage-derived TGF-β1 recruits MSCs to form myofibroblasts in peritendinous adhesions.An improved understanding of PAF mechanisms could help identify a potential therapeutic strategy.
基金Supported by The Science and Technology Project of Guangdong ProvinceChina+3 种基金No.2010B031600047Shenzhen Jian An Pharmaceutical Company Limited for their support
文摘AIM:To investigate the prevalence of fatty liver discovered upon physical examination of Chinese patients and determine the associated clinical characteristics.METHODS:A total of 3433 consecutive patients who received physical examinations at the Huangpu Division of the First Affiliated Hospital at Sun Yat-sen University in Guangzhou,China from June 2010 to December2010 were retrospectively enrolled in the study.Results of biochemical tests,abdominal ultrasound,electrocardiography,and chest X-ray were collected.The diagnosis of fatty liver was made if a patient met any two of the three following ultrasonic criteria:(1)liver and kidney echo discrepancy and presence of an increased liver echogenicity(bright);(2)unclear intrahepatic duct structure;and(3)liver far field echo decay.RESULTS:The study population consisted of 2201males and 1232 females,with a mean age of 37.4±12.8 years.When all 3433 patients were considered,the overall prevalence of hyperlipidemia was 38.1%,of fatty liver was 26.0%,of increased alanine aminotransferase(ALT)and/or aspartate aminotransferase(AST)levels was 11.9%,of gallstone was 11.4%,of hyperglycemia was 7.3%,of hypertension was 7.1%,and of hyperuricemia was 6.2%.Of the 2605 patients who completed the abdominal ultrasonography exam,677(26.0%)were diagnosed with fatty liver and the prevalence was higher in males(32.5%vs females:15.3%,P<0.001).The overall prevalence of fatty liver increased with age,with the peak prevalence(39.5%)found in the 60 to 70-year-old age group.Among patients between the ages of 18 to 50-year-old,the prevalence of fatty liver was significantly higher in males(20.2%vs females:8.7%,P<0.001);the difference in prevalence between the two sexes in patients>50-year-old did not reach statistical significance.Only 430 of the patients diagnosed with fatty liver had complete information;among those,increased ALT and/or AST levels were detected in only 30%,with all disturbances being mild or moderate.In these 430 patients,the overall prevalence of hypertriglyceridemia was 31.4%,of mixed type hyperlipidemia was 20.9%,of hypercholesterolemia was 12.3%,of hyperglycemia was 17.6%,of hypertension was 16.0%,of hyperuricemia was 15.3%,and of gallstone was 14.4%.Again,the prevalences of hypertriglyceridemia and hyperuricemia were higher in males(hypertriglyceridemia,36.0%vs females:12.0%,P<0.05;hyperuricemia,17.3%vs females:7.2%,P<0.05);in contrast,however,the prevalences of mixed type hyperlipidemia and hypercholesterolemia was higher in females(mixed type hyperlipidemia,18.7% vs females:30.1%,P<0.05,hypercholesterolemia,9.5%vs females:24.1%,P<0.05).Finally,comparison of the fatty liver group to the non-fatty liver group showed that prevalences of hyperlipidemia,hyperglycemia,hypertension,and hyperuricemia were higher in the former(all P<0.01).CONCLUSION:A high prevalence of fatty liver is detected upon physical examination in Guangzhou,and the primary associated clinical findings are hyperlipidemia,hyperglycemia,hypertension,and hyperuricemia.
基金supported by the Beijing Natural Science Foundation youth project (7184325)the China Postdoctoral Foundation NO.62 general program
文摘Ankylosing spondylitis(AS), a common type of spondyloarthropathy, is a chronic inflammatory autoimmune disease that mainly affects spine joints, causing severe, chronic pain;additionally, in more advanced cases, it can cause spine fusion. Significant progress in its pathophysiology and treatment has been achieved in the last decade. Immune cells and innate cytokines have been suggested to be crucial in the pathogenesis of AS, especially human leukocyte antigen(HLA)?B27 and the interleukin?23/17 axis.However, the pathogenesis of AS remains unclear. The current study reviewed the etiology and pathogenesis of AS, including genome-wide association studies and cytokine pathways. This study also summarized the current pharmaceutical and surgical treatment with a discussion of future potential therapies.
基金supported by U.S. National Institutes of Health grants (AR063943 and DK057501 to X.C. AR064833 to J.L.C.)+3 种基金the National Natural Science Foundation of China (81771099 to X.X.)the Key Project for Frontier Research of Science and Technology Department of Sichuan Province (2016JY0006 to X.Z.)Sichuan Province Science and Technology Innovation Team Program (2017TD0016 to Q.Y.).X.X.supported by the visiting scholar fellowship from West China Hospital of Stomatology, Sichuan University
文摘TGF-β 1–3 are unique multi-functional growth factors that are only expressed in mammals, and mainly secreted and stored as a latent complex in the extracellular matrix(ECM). The biological functions of TGF-β in adults can only be delivered after ligand activation, mostly in response to environmental perturbations. Although involved in multiple biological and pathological processes of the human body, the exact roles of TGF-β in maintaining stem cells and tissue homeostasis have not been well-documented until recent advances, which delineate their functions in a given context. Our recent findings, along with data reported by others, have clearly shown that temporal and spatial activation of TGF-β is involved in the recruitment of stem/progenitor cell participation in tissue regeneration/remodeling process, whereas sustained abnormalities in TGF-β ligand activation, regardless of genetic or environmental origin, will inevitably disrupt the normal physiology and lead to pathobiology of major diseases. Modulation of TGF-β signaling with different approaches has proven effective pre-clinically in the treatment of multiple pathologies such as sclerosis/fibrosis, tumor metastasis, osteoarthritis, and immune disorders. Thus, further elucidation of the mechanisms by which TGF-β is activated in different tissues/organs and how targeted cells respond in a context-dependent way can likely be translated with clinical benefits in the management of a broad range of diseases with the involvement of TGF-β.
基金the National Natural Science Foundation of China(81772386,81702191,81572175,81371984,and 81071511)the Guangdong-Hong Kong Joint Innovation Project of Guangdong Province(2017A050506019)the Natural Science Foundation of Guangdong Province,China(2020A1515011031).
文摘Low back pain(LBP),as a leading cause of disability,is a common musculoskeletal disorder that results in major social and economic burdens.Recent research has identified inflammation and related signaling pathways as important factors in the onset and progression of disc degeneration,a significant contributor to LBP.Inflammatory mediators also play an indispensable role in discogenic LBP.The suppression of LBP is a primary goal of clinical practice but has not received enough attention in disc research studies.Here,an overview of the advances in inflammation-related pain in disc degeneration is provided,with a discussion on the role of inflammation in IVD degeneration and pain induction.Puncture models,mechanical models,and spontaneous models as the main animal models to study painful disc degeneration are discussed,and the underlying signaling pathways are summarized.Furthermore,potential drug candidates,either under laboratory investigation or undergoing clinical trials,to suppress discogenic LBP by eliminating inflammation are explored.We hope to attract more research interest to address inflammation and pain in IDD and contribute to promoting more translational research.
基金supported by 2016JQ0054 and NSFC grants 81470711 to L.Z.National Key Research and Development Program of China 2016YFC1102700 to X.Z.
文摘There is currently no effective medical treatment for temporomandibular joint osteoarthritis(TMJ-OA) due to a limited understanding of its pathogenesis. This study was undertaken to investigate the key role of transforming growth factor-β(TGF-β)signalling in the cartilage and subchondral bone of the TMJ using a temporomandibular joint disorder(TMD) rat model, an ageing mouse model and a Camurati–Engelmann disease(CED) mouse model. In the three animal models, the subchondral bone phenotypes in the mandibular condyles were evaluated by μCT, and changes in TMJ condyles were examined by TRAP staining and immunohistochemical analysis of Osterix and p-Smad2/3. Condyle degradation was confirmed by Safranin O staining, the Mankin and OARSI scoring systems and type X collagen(Col X), p-Smad2/3 a and Osterix immunohistochemical analyses. We found apparent histological phenotypes of TMJ-OA in the TMD, ageing and CED animal models, with abnormal activation of TGF-βsignalling in the condylar cartilage and subchondral bone. Moreover, inhibition of TGF-β receptor I attenuated TMJ-OA progression in the TMD models. Therefore, aberrant activation of TGF-β signalling could be a key player in TMJ-OA development.
基金supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health under Award Numbers AR071432 and AR063943
文摘Degenerative disc disease(DDD) is associated with intervertebral disc degeneration of spinal instability. Here, we report that the cilia of nucleus pulposus(NP) cells mediate mechanotransduction to maintain anabolic activity in the discs. We found that mechanical stress promotes transport of parathyroid hormone 1 receptor(PTH1 R) to the cilia and enhances parathyroid hormone(PTH) signaling in NP cells. PTH induces transcription of integrin α_vβ_6 to activate the transforming growth factor(TGF)-β-connective tissue growth factor(CCN2)-matrix proteins signaling cascade. Intermittent injection of PTH(iPTH) effectively attenuates disc degeneration of aged mice by direct signaling through NP cells, specifically improving intervertebral disc height and volume by increasing levels of TGF-β activity, CCN2, and aggrecan. PTH1 R is expressed in both mouse and human NP cells. Importantly,knockout PTH1 R or cilia in the NP cells results in significant disc degeneration and blunts the effect of PTH on attenuation of aged discs. Thus, mechanical stress-induced transport of PTH1 R to the cilia enhances PTH signaling, which helps maintain intervertebral disc homeostasis, particularly during aging, indicating therapeutic potential of iPTH for DDD.
基金supported by NIH R01 AR052461 and NIH R01 AR069148supported by a NSF Graduate Research Fellowship. A. E. M.supported by training grant T32 AR059038
文摘The vast osteocytic network is believed to orchestrate bone metabolic activity in response to mechanical stimuli through production of sclerostin, RANKL, and osteoprotegerin(OPG). However, the mechanisms of osteocyte mechanotransduction remain poorly understood. We've previously shown that osteocyte mechanosensitivity is encoded through unique intracellular calcium (Ca^(2+) ) dynamics. Here, by simultaneously monitoring Ca^(2+) and actin dynamics in single cells exposed to fluid shear flow, we detected actin network contractions immediately upon onset of flow-induced Ca^(2+) transients, which were facilitated by smooth muscle myosin and further confirmed in native osteocytes ex vivo. Actomyosin contractions have been linked to the secretion of extracellular vesicles(EVs), and our studies demonstrate that mechanical stimulation upregulates EV production in osteocytes through immunostaining for the secretory vesicle marker Lysosomal-associated membrane protein 1(LAMP1) and quantifying EV release in conditioned medium, both of which are blunted when Ca^(2+) signaling was inhibited by neomycin. Axial tibia compression was used to induce anabolic bone formation responses in mice, revealing upregulated LAMP1 and expected downregulation of sclerostin in vivo. This load-related increase in LAMP1 expression was inhibited in neomycin-injected mice compared to vehicle.Micro-computed tomography revealed significant load-related increases in both trabecular bone volume fraction and cortical thickness after two weeks of loading, which were blunted by neomycin treatment. In summary, we found mechanical stimulation of osteocytes activates Ca^(2+) -dependent contractions and enhances the production and release of EVs containing bone regulatory proteins. Further, blocking Ca^(2+) signaling significantly attenuates adaptation to mechanical loading in vivo, suggesting a critical role for Ca^(2+) -mediated signaling in bone adaptation.
基金supported in part by the grants from the United States National Institute of Health NIDDK including T32DK07751 (JLC)the Diabetes Research and Training Center grant P60DK079637(JSF),and DK057501 and DK08098 (XC)
文摘Survival of children with chronic medical illnesses is leading to an increase in secondary osteoporosis due to impaired peak bone mass(PBM).Insulin-like growth factor type 1(IGF-1) levels correlate with the pattern of bone mass accrual and many chronic illnesses are associated with low IGF-1 levels.Reduced serum levels of IGF-1 minimally affect the integrity of the skeleton,whereas recent studies suggest that skeletal IGF-I regulates PBM.To determine the role of IGF-1 in postnatal bone mass accrual regardless of source,we established an inducible type 1 Igf receptor Cre/lox knockout mouse model,in which the type 1 Igf receptor was deleted inducibely in the mesenchymal stem cells(MSCs) from 3-7 weeks of age.The size of the mouse was not affected as knockout and wild type mice had similar body weights and nasoanal and femoral lengths.However,bone volume and trabecular bone thickness were decreased in the secondary spongiosa of female knockout mice relative to wild type controls,indicating that IGF-1 is critical for bone mass.IGF-1 signaling in MSCs in vitro has been implicated to be involved in both migration to the bone surface and differentiation into bone forming osteoblasts.To clarify the exact role of IGF-1 in bone,we found by immunohistochemical analysis that a similar number of Osterix-positive osteoprogenitors were on the bone perimeter,indicating migration of MSCs was not affected.Most importantly,56% fewer osteocalcin-positive mature osteoblasts were present on the bone perimeter in the secondary spongiosa in knockout mice versus wild type littermates.These in vivo data demonstrate that the primary role of skeletal IGF-1 is for the terminal differentiation of osteoprogenitors,but refute the role of IGF-1 in MSC migration in vivo.Additionally,these findings confirm that impaired IGF-1 signaling in bone MSCs is sufficient to impair bone mass acquisition.
基金provided by K01-AR060433 (T.Q.)K08-AR064833 (J.C)R01-AR063943 (X.C)
文摘Parathyroid hormone(PTH) regulates bone remodeling by activating PTH type 1 receptor(PTH1R) in osteoblasts/osteocytes. Insulinlike growth factor type 1(IGF-1) stimulates mesenchymal stem cell differentiation to osteoblasts. However, little is known about the signaling mechanisms that regulates the osteoblast-to-osteocyte transition. Here we report that PTH and IGF-I synergistically enhance osteoblast-to-osteocyte differentiation. We identified that a specific tyrosine residue, Y494, on the cytoplasmic domain of PTH1R can be phosphorylated by insulin-like growth factor type I receptor(IGF1R) in vitro. Phosphorylated PTH1R localized to the barbed ends of actin filaments and increased actin polymerization during morphological change of osteoblasts into osteocytes.Disruption of the phosphorylation site reduced actin polymerization and dendrite length. Mouse models with conditional ablation of PTH1R in osteoblasts demonstrated a reduction in the number of osteoctyes and dendrites per osteocyte, with complete overlap of PTH1R with phosphorylated-PTH1R positioning in osteocyte dendrites in wild-type mice. Thus, our findings reveal a novel signaling mechanism that enhances osteoblast-to-osteocyte transition by direct phosphorylation of PTH1R by IGF1R.
基金supported by National Institutes of Health Grant DK083350 to M. W
文摘Lipoprotein receptor-related protein 6(LRP6) plays a critical role in skeletal development and homeostasis in adults. However, the role of LRP6 in mesenchymal stem cells(MSCs), skeletal stem cells that give rise to osteoblastic lineage, is unknown. In this study, we generated mice lacking LRP6 expression specifically in nestin1MSCs by crossing nestin-Cre mice with LRP6floxmice and investigated the functional changes of bone marrow MSCs and skeletal alterations. Mice with LRP6 deletion in nestin1cells demonstrated reductions in body weight and body length at 1 and 3 months of age. Bone architecture measured by microCT(mCT) showed a significant reduction in bone mass in both trabecular and cortical bone of homozygous and heterozygous LRP6mutant mice. A dramatic reduction in the numbers of osteoblasts but much less significant reduction in the numbers of osteoclasts was observed in the mutant mice. Osterix1osteoprogenitors and osteocalcin1osteoblasts significantly reduced at the secondary spongiosa area, but only moderately decreased at the primary spongiosa area in mutant mice. Bone marrow MSCs from the mutant mice showed decreased colony forming, cell viability and cell proliferation. Thus, LRP6 in bone marrow MSCs is essential for their survival and proliferation, and therefore, is a key positive regulator for bone formation during skeletal growth and remodeling.
文摘Intervertebral disc(IVD) degeneration is the leading cause of disability with no disease-modifying treatment.IVD degeneration is associated with instable mechanical loading in the spine, but little is known about how mechanical stress regulates nucleus notochordal(NC) cells to maintain IVD homeostasis. Here we report that mechanical stress can result in excessive integrin α_vβ_6-mediated activation of transforming growth factor beta(TGFβ), decreased NC cell vacuoles, and increased matrix proteoglycan production, and results in degenerative disc disease(DDD). Knockout of TGFβ type II receptor(TβRII) or integrin α_v in the NC cells inhibited functional activity of postnatal NC cells and also resulted in DDD under mechanical loading.Administration of RGD peptide, TGFβ, and α_vβ_6-neutralizing antibodies attenuated IVD degeneration. Thus,integrin-mediated activation of TGFβ plays a critical role in mechanical signaling transduction to regulate IVD cell function and homeostasis. Manipulation of this signaling pathway may be a potential therapeutic target to modify DDD.
文摘In the recent two decades, it has been well elucidated that receptor activator of nuclear factor-κB ligand (RANKL;also known as TNFSF11) binding to its receptor RANK (also known as TNFRSF11A) drives osteoclast development as the crucial signaling pathway.1-3 However, accumulating evidence also implies that osteoblastic RANKL regulates osteoblastogenesis.4-6 The studies “RANKL signaling in bone marrow mesenchymal stem cells negatively regulates osteoblastic bone formation” by Chen et al.
基金supported by grants from the National Key Research and Development Program of China (2020YFC2002800 to J.L. and 2018YFC1105102 to J.L.)the National Natural Science Foundation of China (91949127, 92168204 to J.L.)the Fundamental Research Funds for the Central Universities (22120210586)
文摘Prostaglandin E2(PGE2), a major cyclooxygenase-2(COX-2) product, is highly secreted by the osteoblast lineage in the subchondral bone tissue of osteoarthritis(OA) patients. However, NSAIDs, including COX-2 inhibitors, have severe side effects during OA treatment. Therefore, the identification of novel drug targets of PGE2 signaling in OA progression is urgently needed. Osteoclasts play a critical role in subchondral bone homeostasis and OA-related pain. However, the mechanisms by which PGE2 regulates osteoclast function and subsequently subchondral bone homeostasis are largely unknown. Here, we show that PGE2 acts via EP4 receptors on osteoclasts during the progression of OA and OA-related pain. Our data show that while PGE2 mediates migration and osteoclastogenesis via its EP2 and EP4 receptors, tissue-specific knockout of only the EP4 receptor in osteoclasts(EP4 Lys M) reduced disease progression and osteophyte formation in a murine model of OA. Furthermore, OA-related pain was alleviated in the EP4 Lys M mice, with reduced Netrin-1 secretion and CGRP-positive sensory innervation of the subchondral bone. The expression of plateletderived growth factor-BB(PDGF-BB) was also lower in the EP4 Lys Mmice, which resulted in reduced type H blood vessel formation in subchondral bone. Importantly, we identified a novel potent EP4 antagonist, HL-43, which showed in vitro and in vivo effects consistent with those observed in the EP4 Lys Mmice. Finally, we showed that the Gαs/PI3 K/AKT/MAPK signaling pathway is downstream of EP4 activation via PGE2 in osteoclasts. Together, our data demonstrate that PGE2/EP4 signaling in osteoclasts mediates angiogenesis and sensory neuron innervation in subchondral bone, promoting OA progression and pain, and that inhibition of EP4 with HL-43 has therapeutic potential in OA.
文摘Ankylosing spondylitis(AS)is chronic inflammatory arthritis with a progressive fusion of axial joints.Anti-inflammatory treatments such as anti-TNF-αantibody therapy suppress inflammation but do not effectively halt the progression of spine fusion in AS patients.Here we report that the autoimmune inflammation of AS generates a microenvironment that promotes chondrogenesis in spine ligaments as the process of spine fusion.Chondrocyte differentiation was observed in the ligaments of patients with earlystage AS,and cartilage formation was followed by calcification.Moreover,a large number of giant osteoclasts were found in the inflammatory environment of ligaments and on bony surfaces of calcified cartilage.Resorption activity by these giant osteoclasts generated marrow with high levels of active TGF-β,which induced new bone formation in the ligaments.Notably,no Osterix+osteoprogenitors were found in osteoclast resorption areas,indicating uncoupled bone resorption and formation.Even at the late and maturation stages,the uncoupled osteoclast resorption in bony interspinous ligament activates TGF-βto induce the progression of ossification in AS patients.Osteoclast resorption of calcified cartilage-initiated ossification in the progression of AS is a similar pathologic process of acquired heterotopic ossification(HO).Our finding of cartilage formation in the ligaments of AS patients revealed that the pathogenesis of spinal fusion is a process of HO and explained why anti-inflammatory treatments do not slow ankylosing once there is new bone formation in spinal soft tissues.Thus,inhibition of HO formation,such as osteoclast activity,cartilage formation,or TGF-βactivity could be a potential therapy for AS.
