The role of ADAMTS-7 and ADAMTS-12 in the pathogenesis of arthritis

Ion channels in osteoarthritis: emerging roles and potential targets

Osteoarthritis (OA) is a highly prevalent joint disease that causes substantial disability, yet effective approaches to disease prevention or to the delay of OA progression are lacking. Emerging evidence has pinpointed ion channels as pivotal mediators in OA pathogenesis and as promising targets for disease-modifying treatments. Preclinical studies have assessed the potential of a variety of ion channel modulators to modify disease pathways involved in cartilage degeneration, synovial inflammation, bone hyperplasia and pain, and to provide symptomatic relief in models of OA. Some of these modulators are currently being evaluated in clinical trials. This review explores the structures and functions of ion channels, including transient receptor potential channels, Piezo channels, voltage-gated sodium channels, voltage-dependent calcium channels, potassium channels, acid-sensing ion channels, chloride channels and the ATP-dependent P2XR channels in the osteoarthritic joint. The discussion spans channel-targeting drug discovery and potential clinical applications, emphasizing opportunities for further research, and underscoring the growing clinical impact of ion channel biology in OA.

Progranulinopathy: A diverse realm of disorders linked to progranulin imbalances

Progranulin (PGRN), encoded by the GRN gene in humans, was originally isolated as a secreted growth factor that implicates in a multitude of processes ranging from regulation of tumorigenesis, inflammation to neural proliferation. Compelling evidence indicating that GRN mutation can lead to various common neuronal degenerative diseases and rare lysosomal storage diseases. These findings have unveiled a critical role for PGRN as a lysosomal protein in maintaining lysosomal function. The phenotypic spectrum of PGRN imbalance has expanded to encompass a broad spectrum of diseases, including autoimmune diseases, metabolic, musculoskeletal and cardiovascular diseases. These diseases collectively referred to as Progranulinopathy- a term encompasses the wide spectrum of disorders influenced by PGRN imbalance. Unlike its known extracellular function as a growth factor-like molecule associated with multiple membrane receptors, PGRN also serves as an intracellular co-chaperone engaged in the folding and traffic of its associated proteins, particularly the lysosomal hydrolases. This chaperone activity is required for PGRN to exert its diverse functions across a broad range of diseases, encompassing both the central nervous system and peripheral systems. In this comprehensive review, we present an update of the emerging role of PGRN in Progranulinopathy, with special focus on elucidating the intricate interplay between PGRN and a diverse array of proteins at various levels, ranging from extracellular fluids and intracellular components, as well as various pathophysiological processes involved. This review seeks to offer a comprehensive grasp of PGRN's diverse functions, aiming to unveil intricate mechanisms behind Progranulinopathy and open doors for future research endeavors.

Progressive Keratoconus in a Patient With Severe Pectus Excavatum and a Cartilage Oligomeric Matrix Protein Gene Mutation: A Case Report

INTRODUCTION

Keratoconus is a progressive ocular disorder associated with numerous systemic diseases, many of which affect the musculoskeletal system. Although the etiology and pathophysiology of the disorder remain elusive, recent studies suggest a significant role of genetic predisposition in the pathogenesis of keratoconus. This case report aims to elucidate a potential genetic association in a patient presenting with keratoconus, severe pectus excavatum, generalized muscular weakness, and skeletal deformities.

CASE DESCRIPTION

A 31-year-old Iranian man presented with progressively diminishing vision in both eyes over the years, eventually diagnosed with keratoconus. The patient's history and further examination indicated generalized muscular weakness, skeletal deformities, and severe pectus excavatum with cardiac and large vessel displacement. Whole-exome sequencing identified two heterozygous gene variants: one in the Cartilage Oligomeric Matrix Protein (COMP) gene and another in the Regulating Synaptic Membrane Exocytosis 1 gene. The patient's systemic and ocular symptoms, combined with the gene variants identified, suggested a connective tissue systemic disorder, potentially within the clinical spectrum of COMPopathies.

CONCLUSION

This is the first documented case of bilateral progressive keratoconus associated with severe pectus excavatum, generalized musculoskeletal dystrophy, and a COMP gene mutation. It highlights the necessity of continued search into the pathogenic genes of keratoconus, particularly in cases with coexisting systemic manifestations, to further our understanding of the etiology and pathogenesis of this complex disease.

Effects of metalloprotease ADAMTS12 on cervical cancer cell phenotype and its potential mechanism

ADAMTS12 is a gene widely expressed in human tissues. We studied the expression level of ADAMTS12 in cervical cancer tissue and its relationship with clinicopathological features. We also explored the function of ADAMTS12 in cervical cancer cells and its underlying mechanisms. We found the higher expression level of ADAMTS12 in cancer tissues, which was associated with the worse overall survival rate. The immunofluorescence assay showed that the cytoplasm of cervical cancer cells is the main expression site of ADAMTS12. Overexpression of ADAMTS12 in HeLa and CaSki cells prominently promoted the cell proliferation, migration and invasion. We found that 2032 genes were correlated with ADAMTS12, which was mainly related to extracellular matrix, TGF-β signaling pathway. The phosphorylation levels of mTOR and 4E-BP1 were upregulated in ADAMTS12-overexpressing cells. Co-Immunoprecipitation combined with protein mass spectrometry showed that TGF-β signaling pathway-related proteins interacting with ADAMTS12 were screened from HeLa cells with ADAMTS12 overexpression. Therefore, we concluded that ADAMTS12 may affect the mTOR signaling pathway through the interacting with TGF-β1, and then affect the biological function of cervical cancer cells.

Phylogenetic inference of the emergence of sequence modules and protein-protein interactions in the ADAMTS-TSL family

Numerous computational methods based on sequences or structures have been developed for the characterization of protein function, but they are still unsatisfactory to deal with the multiple functions of multi-domain protein families. Here we propose an original approach based on 1) the detection of conserved sequence modules using partial local multiple alignment, 2) the phylogenetic inference of species/genes/modules/functions evolutionary histories, and 3) the identification of co-appearances of modules and functions. Applying our framework to the multidomain ADAMTS-TSL family including ADAMTS (A Disintegrin-like and Metalloproteinase with ThromboSpondin motif) and ADAMTS-like proteins over nine species including human, we identify 45 sequence module signatures that are associated with the occurrence of 278 Protein-Protein Interactions in ancestral genes. Some of these signatures are supported by published experimental data and the others provide new insights (e.g. ADAMTS-5). The module signatures of ADAMTS ancestors notably highlight the dual variability of the propeptide and ancillary regions suggesting the importance of these two regions in the specialization of ADAMTS during evolution. Our analyses further indicate convergent interactions of ADAMTS with COMP and CCN2 proteins. Overall, our study provides 186 sequence module signatures that discriminate distinct subgroups of ADAMTS and ADAMTSL and that may result from selective pressures on novel functions and phenotypes.

The Biochemistry and Physiology of A Disintegrin and Metalloproteinases (ADAMs and ADAM-TSs) in Human Pathologies

Metalloproteinases are a group of proteinases that plays a substantial role in extracellular matrix remodeling and its molecular signaling. Among these metalloproteinases, ADAMs (a disintegrin and metalloproteinases) and ADAM-TSs (ADAMs with thrombospondin domains) have emerged as highly efficient contributors mediating proteolytic processing of various signaling molecules. ADAMs are transmembrane metalloenzymes that facilitate the extracellular domain shedding of membrane-anchored proteins, cytokines, growth factors, ligands, and their receptors and therefore modulate their biological functions. ADAM-TSs are secretory, and soluble extracellular proteinases that mediate the cleavage of non-fibrillar extracellular matrix proteins. ADAMs and ADAM-TSs possess pro-domain, metalloproteinase, disintegrin, and cysteine-rich domains in common, but ADAM-TSs have characteristic thrombospondin motifs instead of the transmembrane domain. Most ADAMs and ADAM-TSs are activated by cleavage of pro-domain via pro-protein convertases at their N-terminus, hence directing them to various signaling pathways. In this article, we are discussing not only the structure and regulation of ADAMs and ADAM-TSs, but also the importance of these metalloproteinases in various human pathophysiological conditions like cardiovascular diseases, colorectal cancer, autoinflammatory diseases (sepsis/rheumatoid arthritis), Alzheimer's disease, proliferative retinopathies, and infectious diseases. Therefore, based on the emerging role of ADAMs and ADAM-TSs in various human pathologies, as summarized in this review, these metalloproteases can be considered as critical therapeutic targets and diagnostic biomarkers.

GAAGs, COMP, and YKL-40 as Potential Markers of Cartilage Turnover in Blood of Children with Juvenile Idiopathic Arthritis Treated with Etanercept—Relationship with ADAMTS4, ADAMTS5, and PDGF-BB

We quantified galactosaminoglycans (GAAGs), oligomeric cartilage matrix protein (COMP), and human cartilage glycoprotein 39 (YKL-40) in blood obtained from juvenile idiopathic arthritis (JIA) before and during 2-year treatment with etanercept (ETA), as potential biomarkers of cartilage extracellular matrix (ECM) dysfunction and indicators of efficacy of biologic therapy. We also evaluated the relationship of the mentioned markers with the factors that regulate their metabolism, disintegrin and thrombospondin motif metalloproteinases 4 (ADAMTS4), ADAMTS5, and platelet-derived growth factor BB (PDGF-BB). Methods: We studied 38 children diagnosed with JIA and 45 healthy children. We quantified GAAGs by assessing the concentration of unsaturated disaccharide units formed by digestion of isolated glycosaminoglycans with chondroitinase ABC, while COMP, YKL-40, and PDGF-BB were quantified using immunoenzymatic methods. Results: Compared to the control group, GAAGs and COMP levels were significantly lower, while YKL-40 levels were higher in the blood of patients with aggressive JIA, qualified for ETA treatment. ETA therapy leading to clinical improvement simultaneously promoted normalization of COMP and YKL-40 levels, but not GAAGs. After 24 months of taking ETA, glycan levels were still significantly lower, relative to controls. GAAGs, COMP, and YKL-40 levels were significantly influenced by ADAMTS4, ADAMTS5, and PDGF-BB levels both before and during ETA treatment. Conclusions: The dynamics of changes in marker concentrations during treatment seem to indicate that measurement of COMP and YKL-40 levels can be used to assess the chondroprotective biological efficacy of therapy. In contrast, changes in GAAGs concentrations reflect systemic extracellular matrix transformations in the course of JIA.

Cryo-EM structures show the mechanistic basis of pan-peptidase inhibition by human α2-macroglobulin

Human α₂-macroglobulin (hα₂M) is an ∼720-kDa homotetrameric particle with pan-peptidase inhibitory functions that transits between an open native conformation and a closed induced state, in which endopeptidases are trapped upon cleavage of an accessible bait region. We determined the molecular mechanism of this function through eight cryo–electron microscopy (cryo-EM) structures, which revealed that the hα₂M subunits are organized in two flexible modules that undergo independent expanded-to-compact transitions. In the induced state, a reactive thioester bond triggers covalent linking of the proteinase, and a receptor-binding domain is exposed on the tetramer surface for binding to its specific cellular receptor for internalization and clearance from circulation. These results elucidate the long-awaited molecular mechanism of a historical suicidal inhibitory trap.

Human α₂-macroglobulin (hα₂M) is a multidomain protein with a plethora of essential functions, including transport of signaling molecules and endopeptidase inhibition in innate immunity. Here, we dissected the molecular mechanism of the inhibitory function of the ∼720-kDa hα₂M tetramer through eight cryo–electron microscopy (cryo-EM) structures of complexes from human plasma. In the native complex, the hα₂M subunits are organized in two flexible modules in expanded conformation, which enclose a highly porous cavity in which the proteolytic activity of circulating plasma proteins is tested. Cleavage of bait regions exposed inside the cavity triggers rearrangement to a compact conformation, which closes openings and entraps the prey proteinase. After the expanded-to-compact transition, which occurs independently in the four subunits, the reactive thioester bond triggers covalent linking of the proteinase, and the receptor-binding domain is exposed on the tetramer surface for receptor-mediated clearance from circulation. These results depict the molecular mechanism of a unique suicidal inhibitory trap.

Induced forms of α2-macroglobulin neutralize heparin and direct oral anticoagulant effects

Alpha₂-macroglobulin (α₂M) is a physiological macromolecule that facilitates the clearance of many proteinases, cytokines and growth factors in human. Here, we explored the effect of induced forms of α₂M on anticoagulant drugs. Gla-domainless factor Xa (GDFXa) and methylamine (MA)-induced α₂M were prepared and characterized by electrophoresis, immunonephelometry, chromogenic, clot waveform and rotational thromboelastometry assays. Samples from healthy volunteers and anticoagulated patients were included. In vivo neutralization of anticoagulants was evaluated in C57Bl/6JRj mouse bleeding-model. Anticoagulant binding sites on induced α₂M were depicted by computer-aided energy minimization modeling. GDFXa-induced α₂M neutralized dabigatran and heparins in plasma and whole blood. In mice, a single IV dose of GDFXa-induced α₂M following anticoagulant administration significantly reduced blood loss and bleeding time. Being far easier to prepare, we investigated the efficacy of MA-induced α₂M. It neutralized rivaroxaban, apixaban, dabigatran and heparins in spiked samples in a concentration-dependent manner and in samples from treated patients. Molecular docking analysis evidenced the ability of MA-induced α₂M to bind non-covalently these compounds via some deeply buried binding sites. Induced forms of α₂M have the potential to neutralize direct oral anticoagulants and heparins, and might be developed as a universal antidote in case of major bleeding or urgent surgery.

Omics Profiling of S2P Mutant Fibroblasts as a Mean to Unravel the Pathomechanism and Molecular Signatures of X-Linked MBTPS2 Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is an inherited skeletal dysplasia characterized by low bone density, bone fragility and recurrent fractures. The characterization of its heterogeneous genetic basis has allowed the identification of novel players in bone development. In 2016, we described the first X-linked recessive form of OI caused by hemizygous MBTPS2 missense variants resulting in moderate to severe phenotypes. MBTPS2 encodes site-2 protease (S2P), which activates transcription factors involved in bone (OASIS) and cartilage development (BBF2H7), ER stress response (ATF6) and lipid metabolism (SREBP) via regulated intramembrane proteolysis. In times of ER stress or sterol deficiency, the aforementioned transcription factors are sequentially cleaved by site-1 protease (S1P) and S2P. Their N-terminal fragments shuttle to the nucleus to activate gene transcription. Intriguingly, missense mutations at other positions of MBTPS2 cause the dermatological spectrum condition Ichthyosis Follicularis, Atrichia and Photophobia (IFAP) and Keratosis Follicularis Spinulosa Decalvans (KFSD) without clinical overlap with OI despite the proximity of some of the pathogenic variants. To understand how single amino acid substitutions in S2P can lead to non-overlapping phenotypes, we aimed to compare the molecular features of MBTPS2-OI and MBTPS2-IFAP/KFSD, with the ultimate goal to unravel the pathomechanisms underlying MBTPS2-OI. RNA-sequencing-based transcriptome profiling of primary skin fibroblasts from healthy controls (n = 4), MBTPS2-OI (n = 3), and MBTPS2-IFAP/KFSD (n = 2) patients was performed to identify genes that are differentially expressed in MBTPS2-OI and MBTPS2-IFAP/KFSD individuals compared to controls. We observed that SREBP-dependent genes are more downregulated in OI than in IFAP/KFSD. This is coupled to alterations in the relative abundance of fatty acids in MBTPS2-OI fibroblasts in vitro, while no consistent alterations in the sterol profile were observed. Few OASIS-dependent genes are suppressed in MBTPS2-OI, while BBF2H7- and ATF6-dependent genes are comparable between OI and IFAP/KFSD patients and control fibroblasts. Importantly, we identified genes involved in cartilage physiology that are differentially expressed in MBTPS2-OI but not in MBTPS2-IFAP/KFSD fibroblasts. In conclusion, our data provide clues to how pathogenic MBTPS2 mutations cause skeletal deformities via altered fatty acid metabolism or cartilage development that may affect bone development, mineralization and endochondral ossification.

ADAMTS-12: Functions and Challenges for a Complex Metalloprotease

Nineteen members of the ADAMTS family of secreted zinc metalloproteinases are present in the human degradome. A wide range of different functions are being attributed to these enzymes and the number of their known substrates is considerably increasing in recent years. ADAMTSs can participate in processes such as fertility, inflammation, arthritis, neuronal and behavioral disorders, as well as cancer. Since its first annotation in 2001, ADAMTS-12 has been described to participate in different processes displayed by members of this family of proteinases. In this sense, ADAMTS-12 performs essential roles in modulation and recovery from inflammatory processes such as colitis, endotoxic sepsis and pancreatitis. ADAMTS-12 has also been involved in cancer development acting either as a tumor suppressor or as a pro-tumoral agent. Furthermore, participation of ADAMTS-12 in arthritis or in neuronal disorders has also been suggested through degradation of components of the extracellular matrix. In addition, ADAMTS-12 proteinase activity can also be modified by interaction with other proteins and thus, can be an alternative way of modulating ADAMTS-12 functions. In this review we revised the most relevant findings about ADAMTS-12 function on the 20th anniversary of its identification.

Molecular and Cellular Pathways Contributing to Joint Damage in Rheumatoid Arthritis

Rheumatoid arthritis is a chronic autoimmune syndrome associated with several genetic, epigenetic, and environmental factors affecting the articular joints contributing to cartilage and bone damage. Although etiology of this disease is not clear, several immune pathways, involving immune (T cells, B cells, dendritic cells, macrophages, and neutrophils) and nonimmune (fibroblasts and chondrocytes) cells, participate in the secretion of many proinflammatory cytokines, chemokines, proteases (MMPs, ADAMTS), and other matrix lysing enzymes that could disturb the immune balance leading to cartilage and bone damage. The presence of autoantibodies preceding the clinical onset of arthritis and the induction of bone erosion early in the disease course clearly suggest that initiation events damaging the cartilage and bone start very early during the autoimmune phase of the arthritis development. During this process, several signaling molecules (RANKL-RANK, NF-κB, MAPK, NFATc1, and Src kinase) are activated in the osteoclasts, cells responsible for bone resorption. Hence, comprehensive knowledge on pathogenesis is a prerequisite for prevention and development of targeted clinical treatment for RA patients that can restore the immune balance improving clinical therapy.

Quantification of Extracellular Matrix Fiber Systems Related to ADAMTS Proteins

ADAMTS (a disintegrin-like and metalloprotease domain with thrombospondin type 1 motifs) proteins regulate tissue homeostasis and extracellular matrix (ECM)-related pathogenesis. Some ADAMTS proteins interact with or process multiple ECM proteins, including fibrillins, fibronectin, and collagens. Therefore, characterization and quantification of these ECM fiber systems is essential to understand their functional relationship with ADAMTS proteins. Here we describe unbiased methods to quantify various aspects of ADAMTS-related ECM fiber systems in cell culture and in tissues. We focus on cell counting, overall fiber intensity, fiber length, and focal adhesion analysis in cell culture, and on the quantification of immunohistochemical and immunofluorescent tissue sections. We use ImageJ/Fiji, a widely used Java-based open source software which provides efficient and customizable quantification methods for microscopy images.

lncRNA/mRNA profiling of endometriosis rat uterine tissues during the implantation window

Endometriosis is associated with changes in long non-coding RNA (lncRNA) and mRNA expression, but the exact changes during the implantation window are unknown. Therefore, this study aimed to explore the lncRNA and mRNA expression profiles in the uterus of rats with endometriosis during the implantation window. A total of 35 non-pregnant female rats were randomized to the endometriosis (n=13), adipose tissue control (n=8) and blank control (n=14) groups. On the 5th day of pregnancy, the rats were sacrificed to obtain uterine tissues. lncRNA and mRNA were analyzed using gene chips. A total of five differentially expressed lncRNA and four mRNA were validated by reverse transcription-quantitative (RT-q)PCR. Immunohistochemistry and western blotting were used to determine the expression of the ADAM metal-lopeptidase with thrombospondin type 1 motif 7 (Adamts7), tumor protein p53 (Tp53), distal-less homeobox 3 (Dlx3) and pyrimidinergic receptor P2Y6 (P2ry6) proteins. There were 115 upregulated lncRNAs, 51 downregulated lncRNAs, 97 upregulated mRNAs and 85 downregulated mRNAs in the endometriosis group. RT-qPCR confirmed the trends for five lncRNAs and four mRNAs (Adamts7, Tp53, Dlx3 and P2ry6). The relative protein expression levels of Adamts7, P2ry6, Dlx3 and TP53 were significantly different in the endometriosis group (P<0.05 vs. controls). Bioinformatics predicted the co-expression relationship of the selected five lncRNA and four mRNA. Gene ontology and the Kyoto Encyclopedia of Genes and Genomes predicted that Adamts7, P2ry6, Dlx3 and TP53 were involved in endometriosis-related inflammation and reproductive pathways. In conclusion, the changes in the expression of lncRNAs, mRNAs and proteins (Adamts7, P2ry6, Dlx3 and TP53) may possibly affect endometrial receptivity in rats with endometriosis during the implantation window, probably resulting in implantation failure of the embryo.

Progranulin: A conductor of receptors orchestra, a chaperone of lysosomal enzymes and a therapeutic target for multiple diseases

Progranulin (PGRN), a widely expressed glycoprotein with pleiotropic function, has been linked to a host of physiological processes and diverse pathological states. A series of contemporary preclinical disease models and clinical trials have evaluated various therapeutic strategies targeting PGRN, highlighting PGRN as a promising therapeutic target. Herein we summarize available knowledge of PGRN targeting in various kinds of diseases, including common neurological diseases, inflammatory autoimmune diseases, cancer, tissue repair, and rare lysosomal storage diseases, with a focus on the functional domain-oriented drug development strategies. In particular, we emphasize the role of extracellular PGRN as a non-conventional, extracellular matrix bound, growth factor-like conductor orchestrating multiple membrane receptors and intracellular PGRN as a chaperone/co-chaperone that mediates the folding and traffic of its various binding partners.

Upregulation of ADAMTS‑7 and downregulation of COMP are associated with spontaneous abortion

A disintegrin and metalloproteinase with thrombospondin motifs 7 (ADAMTS-7) has been revealed to serve an important role in inflammation-associated diseases. However, the role of ADAMTS-7 in spontaneous abortion (SA) remains unclear. In the present study, human and mouse decidual tissues were used to detect the expression of ADAMTS-7 and cartilage oligomeric matrix protein (COMP) in mice with lipopolysaccharide (LPS)-induced abortion (10 mice/group), and in SA humans and the corresponding control group (21 participants in the SA group and 15 participants in the control group). The results revealed that ADAMTS-7 expression was upregulated and that COMP expression was downregulated in the mouse decidual tissue of the LPS-induced abortion group, when compared with that of the normal control group. The results were further confirmed by western blot analysis and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis, which revealed increased ADAMTS-7 and decreased COMP expression at the protein and mRNA levels in mice treated with LPS. Additionally, the expression of ADAMTS-7 was negatively correlated with the expression of COMP in mice, with a correlation coefficient of −0.936 (P<0.001). In addition, the expression of ADAMTS-7 and COMP exhibited was similar in the decidual tissue of SA patients when compared with the levels observed in the tissues of the normal control participants, as demonstrated by increased ADAMTS-7 expression and decreased COMP expression. Western blotting and RT-qPCR analysis revealed that ADAMTS-7 was increased and COMP was decreased in the decidual tissue of SA subjects. The correlation analysis of ADAMTS-7 and COMP in human decidual tissue also revealed a similar result, with a correlation coefficient of −0.836 (P<0.001). The results of the present study demonstrated that ADAMTS-7 was upregulated and COMP was downregulated in the decidual tissues of humans and mice with SA, and a negative correlation was identified between the expression levels of ADAMTS-7 and COMP, thereby providing novel evidence for a better understanding of the pathogenesis of SA, which may lead to improvements in the clinical pregnancy outcomes of these individuals.

The Expression of Thrombospondin-4 Correlates with Disease Severity in Osteoarthritic Knee Cartilage

Osteoarthritis (OA) is a progressive joint disease characterized by a continuous degradation of the cartilage extracellular matrix (ECM). The expression of the extracellular glycoprotein thrombospondin-4 (TSP-4) is known to be increased in injured tissues and involved in matrix remodeling, but its role in articular cartilage and, in particular, in OA remains elusive. In the present study, we analyzed the expression and localization of TSP-4 in healthy and OA knee cartilage by reverse transcription polymerase chain reaction (RT-PCR), immunohistochemistry, and immunoblot. We found that TSP-4 protein expression is increased in OA and that expression levels correlate with OA severity. TSP-4 was not regulated at the transcriptional level but we detected changes in the anchorage of TSP-4 in the altered ECM using sequential protein extraction. We were also able to detect pentameric and fragmented TSP-4 in the serum of both healthy controls and OA patients. Here, the total protein amount was not significantly different but we identified specific degradation products that were more abundant in sera of OA patients. Future studies will reveal if these fragments have the potential to serve as OA-specific biomarkers.

The extracellular protease AdamTS-B inhibits vein formation in the Drosophila wing

Vein patterning in the Drosophila wing provides a powerful tool to study regulation of various signaling pathways. Here we show that the ADAMTS extracellular protease AdamTS-B (CG4096) is expressed in the embryonic wing imaginal disc precursor cells and the wing imaginal disc, and functions to inhibit wing vein formation. Knock-down of AdamTS-B displayed posterior crossveins (PCVs) with either extra branches or deltas, or wider PCVs, and a wandering distal tip of the L5 longitudinal vein. Conversely, over-expression of AdamTS-B resulted in a complete absence of the PCV, an incomplete anterior crossvein, and missing distal end of the L5 longitudinal vein. We conclude that AdamTS-B inhibits wing vein formation through negative regulation of signaling pathways, possibly BMP as well as Egfr, displaying the complexity of roles for this family of extracellular proteases.

Role of ADAMTS-12 in Protecting Against Inflammatory Arthritis in Mice By Interacting With and Inactivating Proinflammatory Connective Tissue Growth Factor

OBJECTIVE

It has been reported that ADAMTS-12 is a susceptibility gene for rheumatoid arthritis (RA) development, and its level is significantly increased in RA patients. In addition, ADAMTS-12 is reported to be required for inflammation in otherwise healthy subjects. This study was undertaken to determine the role of ADAMTS-12 and the underlying mechanisms in the pathogenesis of inflammatory arthritis.

METHODS

The collagen-induced arthritis (CIA) model was established in ADAMTS-12-deficient mice and their control littermates to determine the role of ADAMTS-12 in vivo. Micro-computed tomography scanning was used to demonstrate the destruction of the ankle joint; histologic analysis illustrated synovitis, pannus formation, and bone and cartilage destruction; enzyme-linked immunosorbent assay was performed to measure serum levels of inflammatory cytokines; and protein-protein interaction assays were performed to detect the interactions of ADAMTS-12 and its various deletion mutants with connective tissue growth factor (CTGF).

RESULTS

Deficiency of ADAMTS-12 led to accelerated inflammatory arthritis in the CIA mouse model. Loss of ADAMTS-12 caused enhanced osteoclastogenesis. In vitro and in vivo protein-protein interaction assays demonstrated that ADAMTS-12 bound and processed CTGF, a previously unrecognized substrate of ADAMTS-12. In addition, deletion of ADAMTS-12 enhanced, while overexpression of ADMATS-12 reduced, CTGF-mediated inflammation. Furthermore, ADAMTS-12 regulation of inflammation was largely lost in CTGF-deficient macrophages. Importantly, blocking of CTGF attenuated elevated inflammatory arthritis seen in the ADAMTS-12-deficient CIA mouse model.

CONCLUSION

This study provides evidence that ADAMTS-12 is a critical regulator of inflammatory arthritis and that this is mediated, at least in part, through control of CTGF turnover.

Association of serum ADAMTS7 levels and genetic variant rs1994016 with acute coronary syndrome in a Chinese population: A case control study

BACKGROUND AND AIMS

Acute coronary syndrome (ACS) is commonly caused by rupture or erosion of coronary atherosclerotic plaques and secondary thrombus formation. Metalloproteinase ADAMTS7 was found to play an important role in atherogenesis. This study aimed to explore the association of serum ADAMTS7 levels and rs1994016 polymorphism at ADAMTS7 locus with ACS in a Chinese population.

METHODS

1881 patients who underwent coronary angiography were consecutively recruited. Among them, 426 patients were matched for case-controlled analysis. Serum ADAMTS7 levels were determined through enzyme-linked immunosorbent assay (ELISA) and rs1994016 polymorphism was detected by polymerase chain reaction (PCR).

RESULTS

Serum ADAMTS7 levels in patients with unstable angina pectoris were much higher than in non-atherosclerotic patients, however, no difference was found among non-atherosclerotic patients, the coronary atherosclerosis subgroup and stable angina pectoris subgroup. A higher serum ADAMTS7 level was found in the ACS group than in the non-ACS group (0.61 ± 0.04 vs. 0.47 ± 0.02 ng/mL, p = 0.002) and serum ADAMTS7 level was found to be an independent risk factor for ACS after adjusting for major confounding factors (OR:2.81, 95% CI:1.33-5.93, p = 0.007). ADAMTS7 rs1994016 CT/TT polymorphism was negatively associated with the risk of ACS (OR:0.40, 95% CI:0.22-0.71, p = 0.002). Meanwhile, crossover analysis revealed that in CT/TT homozygotes, ACS risk was reduced nearly 80% in patients with serum ADAMTS7 levels <0.594 ng/mL (Interaction p = 0.002).

CONCLUSIONS

Serum level of ADAMTS7 was positively associated and rs1994016 CT/TT genotype was negatively associated with the risk of ACS. Patients with lower serum ADAMTS7 level and rs1994016 CT/TT genotype are less likely to suffer from ACS in a Chinese population.

The metalloproteinase-proteoglycans ADAMTS7 and ADAMTS12 provide an innate, tendon-specific protective mechanism against heterotopic ossification

Heterotopic ossification (HO) is a significant clinical problem with incompletely resolved mechanisms. Here, the secreted metalloproteinases ADAMTS7 and ADAMTS12 are shown to comprise a unique proteoglycan class that protects against a tendency toward HO in mouse hindlimb tendons, menisci, and ligaments. Adamts7 and Adamts12 mRNAs were sparsely expressed in murine forelimbs but strongly coexpressed in hindlimb tendons, skeletal muscle, ligaments, and meniscal fibrocartilage. Adamts7-/- Adamts12-/- mice, but not corresponding single-gene mutants, which demonstrated compensatory upregulation of the intact homolog mRNA, developed progressive HO in these tissues after 4 months of age. Adamts7-/- Adamts12-/- tendons had abnormal collagen fibrils, accompanied by reduced levels of the small leucine-rich proteoglycans (SLRPs) biglycan, fibromodulin, and decorin, which regulate collagen fibrillogenesis. Bgn-/0 Fmod-/- mice are known to have a strikingly similar hindlimb HO to that of Adamts7-/- Adamts12-/- mice, implicating fibromodulin and biglycan reduction as a likely mechanism underlying HO in Adamts7-/- Adamts12-/- mice. Interestingly, degenerated human biceps tendons had reduced ADAMTS7 mRNA compared with healthy biceps tendons, which expressed both ADAMTS7 and ADAMTS12. These results suggest that ADAMTS7 and ADAMTS12 drive an innate pathway protective against hindlimb HO in mice and may be essential for human tendon health.

Progranulin derivative Atsttrin protects against early osteoarthritis in mouse and rat models

BACKGROUND

Atsttrin, an engineered protein composed of three tumor necrosis factor receptor (TNFR)-binding fragments of progranulin (PGRN), shows therapeutic effect in multiple murine models of inflammatory arthritis . Additionally, intra-articular delivery of PGRN protects against osteoarthritis (OA) progression. The purpose of this study is to determine whether Atsttrin also has therapeutic effects in OA and the molecular mechanisms involved.

METHODS

Surgically induced and noninvasive rupture OA models were established in mouse and rat, respectively. Cartilage degradation and OA were evaluated using Safranin O staining, immunohistochemistry, and ELISA. Additionally, expressions of pain-related markers, degenerative factors, and anabolic and catabolic markers known to be involved in OA were analyzed. Furthermore, the anabolic and anti-catabolic effects and underlying mechanisms of Atsttrin were determined using in-vitro assays with primary chondrocytes.

RESULTS

Herein, we found Atsttrin effectively prevented the accelerated OA phenotype associated with PGRN deficiency. Additionally, Atsttrin exhibited a preventative effect in OA by protecting articular cartilage and reducing OA-associated pain in both nonsurgically induced rat and surgically induced murine OA models. Mechanistic studies revealed that Atsttrin stimulated TNFR2-Akt-Erk1/2-dependent chondrocyte anabolism, while inhibiting TNFα/TNFR1-mediated inflammatory catabolism.

CONCLUSIONS

These findings not only provide new insights into the role of PGRN and its derived engineered protein Atsttrin in cartilage homeostasis as well as OA in vivo, but may also lead to new therapeutic alternatives for OA as well as other relative degenerative joint diseases.

Alterations in ADAMTS12 gene expression in salivary glands of radioiodine-131-administered rats

PURPOSE

The aim of this study was to evaluate the alterations in ADAMTS12 expression after radioiodine-131 (RAI)-induced salivary gland damage.

MATERIALS AND METHODS

A total of 30 Wistar male albino rats (260±45 g, 6 months old) were studied for ADAMTS12 gene expression levels and histological changes in the parotid and submandibular salivary glands of rats after the administration of RAI. A series of healthy rats were used as controls. A 3 mCi (111 MBq) dose of RAI was administered to rats in group 1 (n=6), group 2 (n=6), group 3 (n=6), and group 4 (n=6) to induce salivary gland damage. Evaluations were performed at 24 h in controls and at 4, 24 h, 7, and 30 days after the administration of RAI. Quantitative and statistical analyses were carried out.

RESULTS

In RAI-administered groups, the mean values of ADAMTS12 gene expression showed a distinct suppression over time for the parotid gland (groups 1-4: 0.38, 0.11, 0.10, and 0.18, respectively; P<0.05), but the values remained similar over time for the submandibular gland (groups 1-4: 1.59, 1.57, 1.03, and 1.00, respectively; P>0.05) compared with the controls. Histological evaluation indicated that RAI-administered groups had significant common nuclear coarsening and focal subnuclear vacuolization, but not in the control samples. Histological changes were more prominent in the parotid gland samples.

CONCLUSION

Alterations in ADAMTS12 gene expression may play a role in RAI-induced salivary gland damage in rats.

Evaluation of the relationship and genetic overlap between Kashin-Beck disease and body mass index

OBJECTIVES

Body mass index (BMI) is one of the major factors affecting the development of osteoarthritis (OA) but there is currently no information available regarding the relationship between BMI and Kashin-Beck disease (KBD). Our aim in this study was to investigate the relationship and genetic overlap between BMI and KBD.

METHOD

A total of 2050 Han Chinese subjects participated in this study. Using a cohort of 333 grade I KBD patients, logistic regression analysis was conducted to evaluate the correlation between BMI and KBD. Another independent sample of 1717 subjects was genotyped for a genome-wide association study (GWAS) using Affymetrix Human SNP 6.0 Arrays. Single nucleotide polymorphism (SNP) effect concordance analysis (SECA) was applied to the GWAS summaries of KBD and BMI for pleiotropy analysis. Genome-wide bivariate association analysis (GWBAA) of KBD and BMI was carried out to identify the genes with pleiotropic effects on KBD and BMI. The relevance of identified genes with KBD was validated by gene expression profiling and immunohistochemistry.

RESULTS

BMI correlated positively with knee movement disorder in KBD (coefficient β = 0.068, p = 0.045). SECA identified a significant pleiotropic effect (empirical p = 0.021) between KBD and BMI. In the GWBAA, the rs1893577 of the ADAMTS1 gene achieved the most significant association signal (p = 7.38 × 10^-9). ADAMTS1 was also up-regulated in KBD vs. normal (ratio = 2.64 ± 2.80) and KBD vs. OA (ratio = 2.31 ± 2.01). The rate of ADAMTS1-positive chondrocytes in KBD was significantly higher than that in OA (p < 0.05) and healthy controls (p < 0.05).

CONCLUSIONS

Our results suggest that ADAMTS1 is a novel susceptibility gene for KBD.

Sol narae (Sona) is a Drosophila ADAMTS involved in Wg signaling

ADAMTS (a disintegrin and metalloproteases with thrombospondin motif) family consists of secreted proteases, and is shown to cleave extracellular matrix proteins. Their malfunctions result in cancers and disorders in connective tissues. We report here that a Drosophila ADAMTS named Sol narae (Sona) promotes Wnt/Wingless (Wg) signaling. sona loss-of-function mutants are lethal and rare escapers had malformed appendages, indicating that sona is essential for fly development and survival. sona exhibited positive genetic interaction with wntless (wls) that encodes a cargo protein for Wg. Loss of sona decreased the level of extracellular Wg, and also reduced the expression level of Wg effector proteins such as Senseless (Sens), Distalless (Dll) and Vestigial (Vg). Sona and Wg colocalized in Golgi and endosomal vesicles, and were in the same protein complex. Furthermore, co-expression of Wg and Sona generated ectopic wing margin bristles. This study suggests that Sona is involved in Wg signaling by regulating the level of extracellular Wg.

Regulation of a disintegrins and metalloproteinase with thrombospondin motifs 7 during inflammation in nucleus pulposus (NP) cells: role of AP-1, Sp1 and NF-κB signaling

AIM

The objective of this study is to explore the effect of inflammatory cytokines on a disintegrins and metalloproteinase with thrombospondin motifs 7 (ADAMTS7) and to demonstrate the role of Sp1, AP-1 and NF-κB signaling on the ADAMTS7 regulation during inflammation in NP cells.

METHODS

Real-time PCR was to detect the effect of ADAMTS7 knockdown on the expression of catabolic enzymes during inflammatory condition in NP cells. Real-time PCR, western blot, immunofluorescence and transfection experiments were used to observe the effect of tumor necrosis factor-α (TNF-α) or interleukin-1β on the expression and the activity of ADAMTS7, and demonstrated the role to Sp1, AP-1 and NF-κB in the regulation of ADAMTS7 during inflammation.

RESULTS

As other cells, ADAMTS7 knockdown suppressed the mRNA expression of catabolic factors during inflammation in human NP cells. However, the expression of ADAMTS7 mRNA and protein and the activity of ADAMTS7 promoter were refractory to inflammatory cytokines. In addition, Sp1, AP-1, not NF-κB signaling sustained the expression of ADAMTS7 mRNA, protein, as well as promoter activity during inflammation in NP cells.

CONCLUSION

ADAMTS7 played a crucial role in the expression of catabolic genes in the presence of TNF-α and AP-1, Sp1, not NF-κB signaling were critical for the maintenance of ADAMTS7 expression during inflammation in NP cells.

The role of progranulin in arthritis

Progranulin (PGRN) is a growth factor with a unique beads-on-a-string structure that is involved in multiple pathophysiological processes, including anti-inflammation, tissue repair, wound healing, neurodegenerative diseases, and tumorigenesis. This review presents up-to-date information concerning recent studies on the role of PGRN in inflammatory arthritis and osteoarthritis, with a special focus on the involvement of the interactions and interplay between PGRN and tumor necrosis factor receptor (TNFR) family members in regulating such musculoskeletal diseases. In addition, this paper highlights the applications of atsttrin, an engineered protein comprising three TNFR-binding fragments of PGRN, as a promising intervention in treating arthritis.

Pathophysiological Function of ADAMTS Enzymes on Molecular Mechanism of Alzheimer's Disease

The extracellular matrix (ECM) is an environment that has various enzymes attended in regeneration and restoration processes which is very important to sustain physiological and biological functions of central nervous system (CNS). One of the participating enzyme systems in ECM turnover is matrix metalloproteinases. A disintegrin-like and metalloproteinase with thrombospondin type 1 motifs (ADAMTS) is a unique family of ECM proteases found in mammals. Components of this family may be distinguished from the ADAM (A Disintegrin and Metalloproteinase) family based on the multiple copies of thrombospondin 1-like repeats. The considerable role of the ADAMTS in the CNS continues to develop. Evidences indicate that ADAMTS play an important role in neuroplasticity as well as nervous system pathologies such as Alzheimer's disease (AD). It is hopeful and possible that ADAMTS family members may be utilized to develop therapies for CNS pathologies, ischemic injuries, neurodegenerative and neurological diseases. To understand and provide definitive data on ADAMTS to improve structural and functional recovery in CNS injury and diseases, this review aimed to enlighten the subject extensively to reach certain information on metalloproteinases and related molecules/enzymes. It will be interesting to examine how ADAMTS expression and action would affect the initiation/progression of above-mentioned clinical situations, especially AD.

Classification of ADAMTS binding sites: The first step toward selective ADAMTS7 inhibitors

Genome-wide association studies identified ADAMTS7 as a risk locus for coronary artery disease. In carotid arteries of rats, neointima formation after balloon-mediated injury goes along with enhanced Adamts7 expression. Vice versa, Adamts7-deficient mice display reduced neointima formation following vascular injury. Although a causal link between ADAMTS7 and coronary artery disease remains to be proven, inhibition of ADAMTS7 represents a potential new target for intervention in this disease. ADAMTS7, a member of the 'a disintegrin and metalloproteinase with thrombospondin motifs' (ADAMTS) family of proteins, contains a catalytic zinc ion in the binding site of its metalloproteinase domain. The structure of ADAMTS7 and its inhibitors are unknown. In this study, we used in silico methods, including homology modeling and pharmacophore modeling, to analyze the ADAMTS7 metalloproteinase domain, particularly its binding site. The results revealed structural and sequence differences relative to the binding sites of the other ADAMTS proteins; these non-conserved regions represent potential binding regions for selective ADAMTS7 inhibitors. The main contribution of this study is the proposal of a pharmacophore for ADAMTS7. The characterization of the ADAMTS7 binding site and definition of a pharmacophore are the first step toward developing a new therapeutic target for coronary artery disease.

miR-105/Runx2 axis mediates FGF2-induced ADAMTS expression in osteoarthritis cartilage

Fibroblast growth factor 2 (FGF2) plays an important role in the development of osteoarthritis (OA) through the regulation of cartilage degradation. However, the molecular mechanism underlying FGF2-induced OA is poorly characterized. MicroRNAs (miRNAs) maintain cartilage homeostasis. To examine whether FGF2 regulates OA through the modulation of miRNA, we screened potential miRNA molecules that could be regulated through FGF2 using microarray analysis. The results showed that microRNA-105 (miR-105) was significantly downregulated in chondrocytes stimulated with FGF2. Runt-related transcription factor 2 (Runx2), a key transcription factor involved in OA, has been identified as a novel potential target of miR-105. FGF2 suppressed miR-105 expression through the recruitment of the subunit of the nuclear factor kappa B transcription complex p65 to the miR-105 promoter. The knockdown of Runx2 mimicked the effect of miR-105 and abolished the ability of miR-105 to regulate the expression of a disintegrin-like and metalloproteinase with thrombospondin 4 (ADAMTS4), ADAMTS5, ADAMTS7 and ADAMTS12, both of which are responsible for the degradation of collagen 2A1 (COL2A1) and aggrecan (ACAN). miR-105 is also required for FGF2/p65-induced Runx2 activation and ADAMTS expression. Moreover, miR-105 expression was downregulated in OA patients and inversely correlated with the expression of Runx2, ADAMTS7 and ADAMTS12, which were upregulated in OA patients. These data highlight that the FGF2/p65/miR-105/Runx2/ADAMTS axis might play an important role in OA pathogenesis and that miR-105 might be a potential diagnostic target and useful strategy for OA treatment.

KEY MESSAGE

Runx2 was identified as a novel direct target of miR-105. FGF2 inhibits miR-105 transcription through recruitment of p65 to miR-105 promoter. p65/miR-105 is essential for FGF2-mediated Runx2 and ADAMTS upregulation. miR-105 is downregulated in OA and inversely correlated with Runx2 expression.

The Function and Roles of ADAMTS-7 in Inflammatory Diseases

The ADAMTS proteinases are a group of multidomain and secreted metalloproteinases containing the thrombospondin motifs. ADAMTS-7 is a member of ADAMTS family and plays a crucial role in the pathogenesis of arthritis. Overexpression of ADAMTS-7 gene promotes the breakdown of cartilage oligomeric matrix protein (COMP) matrix and accelerates the progression of both surgically induced osteoarthritis and collagen-induced arthritis. Moreover, ADAMTS-7 and tumor necrosis factor-α (TNF-α) form a positive feedback loop in osteoarthritis. More significantly, granulin-epithelin precursor, a growth factor has important roles in bone development and bone-associated diseases, disturbs the interaction between ADAMTS-7 and COMP, and prevents COMP degradation. This review is based on our results and provides an overview of current knowledge of ADAMTS-7, including its structure, function, gene regulation, and inflammatory diseases involvement.

IL-17A enhances ADAMTS-7 expression through regulation of TNF-α in human nucleus pulposus cells

ADMATS-7 is known to play an important role in the pathogenesis of various diseases, including cartilaginous diseases. IL-17A is an inflammatory cytokine detected in degenerative disc tissues. However, the interplay between IL-17A and ADMATS-7 in human disc degeneration is still unknown. Samples collected from 50 patients were divided into three groups according to MRI degeneration grading system score. Immunohistochemistry, RT-PCR and western Blotting were used to investigate the expression of ADAMTS-7 in NP tissues. Furthermore, a rat disc degeneration model was established, and the expression level of ADAMTS-7 was assayed using immunohistochemistry, RT-PCR and western Blotting. The human NP cells were cultured in the presence and absence of IL-17A stimulation. RNA extracts were collected, and real-time PCR was performed to determine the expression of ADAMTS-7. Moreover, ADAMTS-7 concentrations were detected in human NP cell culture supernatants by ELISA. After culturing NP cells with IL-17A (with or without Etanercept), ADAMTS-7 levels were detected in each group. ADAMTS-7 expression was dramatically elevated in both human and rat degenerative NP tissues compared with normal controls. The RT-PCR and ELISA results revealed that IL-17A could enhance the production of ADAMTS-7, while ADAMTS-7 expression dramatically decreased in the IL-17A + Etanercept group in comparison to the IL-17A alone group. Our results indicate the presence of ADAMTS-7 in human NP cells and imply its potential role in disc degeneration. Additionally, our results indicate that IL-17A induced ADAMTS-7 expression via TNF-α, which may form a molecular axis in human NP cells.

Apelin attenuates postburn sepsis via a phosphatidylinositol 3-kinase/protein kinase B dependent mechanism: A randomized animal study

INTRODUCTION

This study aims to investigate whether apelin would regulate inflammatory response and promote survival in an experimental burn sepsis model through a phosphatidylinositol 3-kinase/protein kinase B dependent pathway.

METHODS

Male BALB/c mice were divided into the following groups: sham, burn, burn sepsis, burn sepsis treated with apelin, burn sepsis treated with apelin plus LY294002, and burn sepsis treated with LY294002 alone. Apelin level and inflammatory cytokines in serum were detected by enzyme-linked immuno sorbent assay. Apelin/APJ (apelin receptor, gene symbol APLNR) mRNA expression in spleen and adhesion molecules levels in lung was detected by real-time polymerase chain reaction. Neutrophil infiltration in lung was determined by myeloperoxidase assay. Phosphorylation of protein kinase B in lung was determined by western blot. Mortality rate was monitored.

RESULTS

Burn sepsis induced decreased apelin/APJ mRNA expression in spleen and reduced apelin level in plasma, which were both restored by exogenous apelin treatment. Burn sepsis treated with apelin resulted in decreased interleukin-6, tumor-necrosis factor-alpha, interleukin -1β and monocyte chemotactic protein-1 levels in plasma. Mice with apelin treatment also showed decreased neutrophil infiltration and adhesion molecules expression, accompanied by a remarkable increased protein kinase B phosphorylation in lung tissue. The mortality rate in apelin treated animals was also significantly reduced. Importantly, the above effects of apelin were abolished by LY294002 treatment.

CONCLUSION

Apelin regulates inflammatory response, diminishes inflammatory remote organ damage and improves survival in an experimental model of burn sepsis, which is at least partly mediated by a phosphatidylinositol 3-kinase/protein kinase B dependent pathway.

Overexpression of ADAMTS-7 leads to accelerated initiation and progression of collagen-induced arthritis in mice

The aim of the present study is to determine whether ADAMTS-7 contributes to the onset and severity of joint inflammation in the pathogenesis of inflammatory arthritis. ADAMTS-7 was found to be elevated in the course of collagen-induced arthritis (CIA). ADAMTS-7 transgenic (TG) mice were more susceptible to the induction of CIA. The onset of CIA was accelerated and the arthritic severity was increased in TG mice compared to wild-type mice. The overall incidence was also significantly higher in TG mice. In addition, arthritic TG mice displayed significantly higher clinical and histological arthritis scores. The COMP degradative fragments were significantly elevated in articular cartilage and sera in CIA models of TG mice. Furthermore, the production of tumor necrosis factor-alpha and interleukin-17 was also increased in serum and draining lymph nodes of arthritic TG mice. Therefore, these data provided the in vivo evidence, suggesting that ADAMTS-7 may play an important role in the pathogenesis of inflammatory arthritis, and that inhibition of ADAMTS-7 may be a potential target to ameliorate the severity of inflammatory arthritis.

ADAMTS-7 exhibits elevated expression in cartilage of osteonecrosis of femoral head and has a positive correlation with TNF- α and NF- κ B P65

ADAMTS-7 has been reported to exaggerate cartilage degeneration and to be associated with TNF-α and NF-κB signaling pathway. In this study we compared the expression of ADAMTS-7, TNF-α, and Phospho-NF-κB in patients with femoral neck fracture (FNF) and osteonecrosis of femoral head (ONFH) at different stages. We found that expression of ADAMTS-7, TNF-α, and Phospho-NF-κB was significantly upregulated in ONFH patients' articular cartilage and related to the pathogenesis of ONFH. Thus we conclude that ADAMTS-7 level appears to be positively associated with expression of TNF-α and Phospho-NF-κB P65 in cartilage, which may imply its association with cartilage destruction of ONFH.

A new biological marker candidate in female reproductive system diseases: Matrix metalloproteinase with thrombospondin motifs (ADAMTS)

Playing a key role in the pathophysiology of many diseases, A Disintegrin-like and Metalloproteinase with Thrombospondin type-1 motif (ADAMTS) proteinases have been attracted more attention in obstetrics and gynecology. First discovered in 1997, this zinc-dependent proteinase family has 19 members today. These enzymes, which are located in the extracellular matrix (ECM), have a lot of very important functions, like matrix formation and resorption, angiogenesis, ovulation, and coagulation. In addition, in the pathogenesis of cancer, inflammation, arthritis, and connective tissue diseases, ADAMTS proteinases have crucial roles. The purpose of this review is to collect previous studies about obstetrics and gynecology that are related to ADAMTS enzymes and discuss the subject in many aspects to give an idea to the investigators who are interested in the subject.

Progranulin protects against osteoarthritis through interacting with TNF-α and β-Catenin signalling

OBJECTIVE

Progranulin (PGRN) was previously isolated as an osteoarthritis (OA)-associated growth factor. Additionally, PGRN was found to play a therapeutic role in inflammatory arthritis mice models through antagonising tumour necrosis factor α (TNF-α). This study was aimed at investigating the role of PGRN in degradation of cartilage and progression of OA.

METHODS

Progression of OA was analysed in both spontaneous and surgically induced OA models in wild type and PGRN-deficient mice. Cartilage degradation and OA were evaluated using Safranin O staining, immunohistochemistry and ELISA. Additionally, mRNA expression of degenerative factors and catabolic markers known to be involved in cartilage degeneration in OA were analysed. Furthermore, the anabolic effects and underlying mechanisms of PGRN were investigated by in vitro experiments with primary chondrocytes.

RESULTS

Here, we found that deficiency of PGRN led to spontaneous OA-like phenotype in 'aged' mice. Additionally, PGRN-deficient mice exhibited exaggerated breakdown of cartilage structure and OA progression, while local delivery of recombinant PGRN protein attenuated degradation of cartilage matrix and protected against OA development in surgically induced OA models. Furthermore, PGRN activated extracellular signal-regulated kinases (ERK) 1/2 signalling and elevated the levels of anabolic biomarkers in human chondrocyte, and the protective function of PGRN was mediated mainly through TNF receptor 2. Additionally, PGRN suppressed inflammatory action of TNF-α and inhibited the activation of β-Catenin signalling in cartilage and chondrocytes.

CONCLUSIONS

Collectively, this study provides new insight into the pathogenesis of OA, and also presents PGRN as a potential target for the treatment of joint degenerative diseases, including OA.

ADAMTS-12: a multifaced metalloproteinase in arthritis and inflammation

ADAMTS-12 is a member of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) family of proteases, which were known to play important roles in various biological and pathological processes, such as development, angiogenesis, inflammation, cancer, arthritis, and atherosclerosis. In this review, we briefly summarize the structural organization of ADAMTS-12; concentrate on the emerging role of ADAMTS-12 in several pathophysiological conditions, including intervertebral disc degeneration, tumorigenesis and angioinhibitory effects, pediatric stroke, gonad differentiation, trophoblast invasion, and genetic linkage to schizophrenia and asthma, with special focus on its role in arthritis and inflammation; and end with the perspective research of ADAMTS-12 and its potential as a promising diagnostic and therapeutic target in various kinds of diseases and conditions.

The role of PGRN in musculoskeletal development and disease

Progranulin (PGRN) is a growth factor that has been implicated in wound healing, inflammation, infection, tumorigenesis, and is most known for its neuroprotective and proliferative properties in neurodegenerative disease. This pleiotropic growth factor has been found to be a key player and regulator of a diverse spectrum of multi-systemic functions. Its critical anti-inflammatory role in rheumatoid arthritis and other inflammatory disease models has allowed for the propulsion of research to establish its significance in musculoskeletal diseases, including inflammatory conditions involving bone and cartilage pathology. In this review, we aim to elaborate on the emerging role of PGRN in the musculoskeletal system, reviewing its particular mechanisms described in various musculoskeletal diseases, with special focus on osteoarthritis and inflammatory joint disease patho-mechanisms and potential therapeutic applications of PGRN and its derivatives in these and other musculoskeletal diseases.

Genetics of coronary artery disease and myocardial infarction--2013

Coronary artery disease is a complex disease influenced by modifiable risk factors as well as genetic susceptibility. The genetics of coronary artery disease and myocardial infarction have long been enigmatic. Recent advances in molecular genetics and biology, bioinformatics, and statistics have allowed us to study the interaction of exogenous and endogenous factors. Recent genome-wide association studies and their meta-analyses have included thousands of patients and healthy individuals and provided the statistical power to identify genetic variants, each associated with a rather small increase in risk. Thus far, more than 45 risk loci have been identified. Nevertheless, the search for genetics-based improvements in therapy and prevention has just begun. Hitherto unrecognized mechanisms may provide promising drug targets and early interventional strategies. Furthermore, the sum of risk alleles may facilitate risk assessment as they provide complementary information to traditional risk scores.

ADAMTS-7 forms a positive feedback loop with TNF-α in the pathogenesis of osteoarthritis

OBJECTIVE

To examine the expression of ADAMTS-7 during the progression of osteoarthritis (OA), defining its role in the pathogenesis of OA, and elucidating the molecular events involved.

METHODS

ADAMTS-7 expression in cartilage of a rat OA model was assayed using immunohistochemistry. Cartilage-specific ADAMTS-7 transgenic mice and ADAMTS-7 small interfering (si)RNA knockdown mice were generated and used to analyse OA progression in both spontaneous and surgically induced OA models. Cartilage degradation and OA was evaluated using Safranin-O staining, immunohistochemistry, ELISA and western blotting. In addition, mRNA expression of tumour necrosis factor (TNF)-α and metalloproteinases known to be involved in cartilage degeneration in OA was analysed. Furthermore, the transactivation of ADAMTS-7 by TNF-α and its downstream NF-κB signalling was measured using reporter gene assay.

RESULTS

ADAMTS-7 expression was elevated during disease progression in the surgically induced rat OA model. Targeted overexpression of ADAMTS-7 in chondrocytes led to chondrodysplasia characterised by short-limbed dwarfism and a delay in endochondral ossification in 'young mice' and a spontaneous OA-like phenotype in 'aged' mice. In addition, overexpression of ADAMTS-7 led to exaggerated breakdown of cartilage and accelerated OA progression, while knockdown of ADAMTS-7 attenuated degradation of cartilage matrix and protected against OA development, in surgically induced OA models. ADAMTS-7 upregulated TNF-α and metalloproteinases associated with OA; in addition, TNF-α induced ADAMTS-7 through NF-κB signalling.

CONCLUSIONS

ADAMTS-7 and TNF-α form a positive feedback loop in the regulation of cartilage degradation and OA progression, making them potential molecular targets for prevention and treatment of joint degenerative diseases, including OA.

c-Maf Transcription Factor Regulates ADAMTS-12 Expression in Human Chondrogenic Cells

OBJECTIVE

ADAMTS (a disintegrin and metalloproteinase with thrombospondin type-1 motif) zinc metalloproteinases are important during the synthesis and breakdown of cartilage extracellular matrix. ADAMTS-12 is up-regulated during in vitro chondrogenesis and embryonic limb development; however, the regulation of ADAMTS-12 expression in cartilage remains unknown. The transcription factor c-Maf is a member of Maf family of basic ZIP (bZIP) transcription factors. Expression of c-Maf is highest in hypertrophic chondrocytes during embryonic development and postnatal growth. We hypothesize that c-Maf and ADAMTS-12 are co-expressed during chondrocyte differentiation and that c-Maf regulates ADAMTS-12 expression during chondrogenesis.

DESIGN

Promoter analysis and species alignments identified potential c-Maf binding sites in the ADAMTS-12 promoter. c-Maf and ADAMTS-12 co-expression was monitored during chondrogenesis of stem cell pellet cultures. Luciferase expression driven by ADAMTS-12 promoter segments was measured in the presence and absence of c-Maf, and synthetic oligonucleotides were used to confirm specific binding of c-Maf to ADAMTS-12 promoter sequences.

RESULTS

In vitro chondrogenesis from human mesenchymal stem cells revealed co-expression of ADAMTS-12 and c-Maf during differentiation. Truncation and point mutations of the ADAMTS-12 promoter evaluated in reporter assays localized the response to the proximal 315 bp of the ADAMTS-12 promoter, which contained a predicted c-Maf recognition element (MARE) at position -61. Electorphoretic mobility shift assay confirmed that c-Maf directly interacted with the MARE at position -61.

CONCLUSIONS

These data suggest that c-Maf is involved in chondrocyte differentiation and hypertrophy, at least in part, through the regulation of ADAMTS-12 expression at a newly identified MARE in its proximal promoter.

Biochemistry and physiological functions of ADAMTS7 metalloprotease

Here, we provide a comprehensive review of current findings concerning the biochemistry and physiological functions of ADAMTS7, a metalloprotease that is known to interact with cartilage oligomeric matrix protein, progranulin, and alpha2-macroglobulin. Such broad substrate specificity and potentially diverse physiological functions make ADAMTS7 an interesting enzyme to study. ADAMTS7 has been shown to play a role in the pathogenesis of arthritis and disc disorders. More recently, the ADAMTS7 locus is identified to have a strong association with coronary atherosclerotic disease. However, the role of ADAMTS7 in the development of atherosclerosis is yet to be determined. The development of an easy and high throughput assay for ADAMTS7 activity and appropriate animal models will allow us to uncover the novel mechanisms of coronary arterial disease.

Negative effects of ADAMTS-7 and ADAMTS-12 on endplate cartilage differentiation

The roles of ADAMTS-7 and ADAMTS-12 in disc degeneration have not been previously examined. The purpose of this study was to examine the expression of ADAMTS-7 and ADAMTS-12 in the endplate cells isolated from patients with degenerative disc disease and to see whether they are associated with the pathological change of endplate. Sixty-four degenerated lumbar endplate specimens were obtained from the patients with degenerative disc disease categorized as type Modic I or II in magnetic resonance imaging (MRI) and 12 nondegenerative specimens as control (vertebra burst fracture patients without degenerative change in MRI) during surgical procedures. The expression of ADAMTS-7 and ADAMTS-12 was examined by real-time PCR and Western blotting. A statistically significant increase in mRNA expression of ADAMTS-7 and ADAMTS-12 was observed in the endplate cells in degenerative discs compared with nondegenerative discs. The corresponding protein levels of ADAMTS-7 and ADAMTS-12 had the same expression patterns. Moreover, ADAMTS-7 and ADAMTS-12 down-regulated the expression of Col II, Sox9, and Col X the marker genes for chondrogenesis. Our results indicate that ADAMTS-7 and ADAMTS-12 appear to be potent negative regulators of endplate cartilage development.

Strategies beyond genome-wide association studies for atherosclerosis

Atherosclerotic diseases, including coronary artery disease (CAD) and myocardial infarction (MI), are the leading causes of death in the world. The genetic basis of CAD and MI, which are caused by multiple interacting endogenous and exogenous factors, has gained considerable interest in the last years as genome-wide association studies (GWASs) have identified many new susceptibility loci for CAD and MI, and the underlying genes provide new insights into the genetic architecture of these diseases. Here we summarize the recent findings from GWASs of atherosclerosis and discuss their functional and biological implications. We also discuss the different post-GWAS strategies that are currently used for refining the location of causal variants, understanding their role, and shedding light on molecular mechanisms explaining their association to CAD. We finally discuss potential clinical translations of GWAS findings for individual risk prediction, advanced clinical strategies, and personalized treatments.

Association of serum a disintegrin and metalloproteinase with thrombospodin motif 4 levels with the presence and severity of coronary artery disease

OBJECTIVE

A disintegrin and metalloproteinase with thrombospodin motif 4 (ADAMTS4) has been shown to be an important player in atherosclerosis. However, the clinical significance of measuring serum ADAMTS4 levels has not been fully elucidated. We therefore investigate whether serum ADAMTS4 levels are associated with the presence and severity of coronary artery disease (CAD).

METHODS

Serum levels of ADAMTS4 were measured in 192 patients undergoing elective coronary angiography for suspected CAD, the severity of CAD was determined by the number of diseased vessels and the severity score of coronary stenosis.

RESULTS

Patients with CAD showed significantly higher levels of ADAMTS4 than did patients with normal coronary arteries [57.82 (48.96-70.32) vs. 46.55 (41.16-51.72) ng/ml, P<0.001]. ADAMTS4 levels increased with the number of diseased vessels (P<0.05) and significantly associated with severity score of stenosis (rs=0.601, P<0.001). In the multivariate analysis, ADAMTS4 levels were found to be independently correlated with the presence and severity of CAD. Receiver-operating characteristic analysis revealed that a cut-off of serum ADAMTS4 levels of 51.63 ng/ml could predict CAD with a 76% sensitivity and a 69% specificity. ADAMTS4 levels were significantly lower in patients with statin treatment than in those without it [47.49 (42.30, 57.09) vs. 56.39 (47.05, 68.94) ng/ml, P<0.05].

CONCLUSION

In conclusion, serum ADAMTS4 levels are associated with the presence and the severity of CAD, ADAMTS4 might serve as an independent factor for predicting CAD. Statin therapy reduces the serum levels of ADAMTS4.