The characteristics of thrombin in osteoarthritic pathogenesis and treatment

In Vivo and In Vitro Investigation of a Novel Gelatin/Sodium Polyacrylate Composite Hemostatic Sponge for Topical Bleeding

Designing a functional and efficient blood-clotting agent is a major challenge. In this research, hemostatic scaffolds (GSp) were prepared from the superabsorbent, inter-crosslinked polymer sodium polyacrylate (Sp) bound to a natural protein gelatin (G) loaded with thrombin (Th) by a cost-effective freeze-drying method. Five compositions were grafted (GSp0.0, Gsp0.1, GSp0.2, GSp0.3, GSp0.3-Th) where the concentration of Sp varied but the ratios of G remained the same. The fundamental physical characteristics that increased the amounts of Sp with G gave synergistic effects after interacting with thrombin. Due to the presence of superabsorbent polymer (SAP) swelling capacities in GSp0.3 and GSp0.3-Th surge forward 6265% and 6948%, respectively. Pore sizes became uniform and larger (ranging ≤ 300 μm) and well-interconnected. The water-contact angle declined in GSp0.3 and GSp0.3-Th to 75.73 ± 1.097 and 75.33 ± 0.8342 degrees, respectively, thus increasing hydrophilicity. The pH difference was found to be insignificant as well. In addition, an evaluation of the scaffold in in vitro biocompatibility with the L929 cell line showed cell viability >80%, so the samples were nontoxic and produced a favorable environment for cell proliferation. The composite GSp0.3-Th revealed the lowest HR (%) (2.601%), and the in vivo blood-clotting time (s) and blood loss (gm) supported hemostasis. Overall, the results showed that a novel GSp0.3-Th scaffold can be a potential candidate as a hemostatic agent.

A "best-in-class" systemic biomarker predictor of clinically relevant knee osteoarthritis structural and pain progression

We aimed to identify markers in blood (serum) to predict clinically relevant knee osteoarthritis (OA) progression defined as the combination of both joint structure and pain worsening over 48 months. A set of 15 serum proteomic markers corresponding to 13 total proteins reached an area under the receiver operating characteristic curve (AUC) of 73% for distinguishing progressors from nonprogressors in a cohort of 596 individuals with knee OA. Prediction based on these blood markers was far better than traditional prediction based on baseline structural OA and pain severity (59%) or the current "best-in-class" biomarker for predicting OA progression, urinary carboxyl-terminal cross-linked telopeptide of type II collagen (58%). The generalizability of the marker set was confirmed in a second cohort of 86 individuals that yielded an AUC of 70% for distinguishing joint structural progressors. Blood is a readily accessible biospecimen whose analysis for these biomarkers could facilitate identification of individuals for clinical trial enrollment and those most in need of treatment.

Inhibition of fibroblast activation protein ameliorates cartilage matrix degradation and osteoarthritis progression

Fibroblast activation protein (Fap) is a serine protease that degrades denatured type I collagen, α2-antiplasmin and FGF21. Fap is highly expressed in bone marrow stromal cells and functions as an osteogenic suppressor and can be inhibited by the bone growth factor Osteolectin (Oln). Fap is also expressed in synovial fibroblasts and positively correlated with the severity of rheumatoid arthritis (RA). However, whether Fap plays a critical role in osteoarthritis (OA) remains poorly understood. Here, we found that Fap is significantly elevated in osteoarthritic synovium, while the genetic deletion or pharmacological inhibition of Fap significantly ameliorated posttraumatic OA in mice. Mechanistically, we found that Fap degrades denatured type II collagen (Col II) and Mmp13-cleaved native Col II. Intra-articular injection of rFap significantly accelerated Col II degradation and OA progression. In contrast, Oln is expressed in the superficial layer of articular cartilage and is significantly downregulated in OA. Genetic deletion of Oln significantly exacerbated OA progression, which was partially rescued by Fap deletion or inhibition. Intra-articular injection of rOln significantly ameliorated OA progression. Taken together, these findings identify Fap as a critical pathogenic factor in OA that could be targeted by both synthetic and endogenous inhibitors to ameliorate articular cartilage degradation.

Thrombin generation potential is increased in patients with autoimmune inflammatory myopathies

PURPOSE

Dermatomyositis and polymyositis (DM/PM) are rare autoimmune inflammatory myopathies, characterized by an increased risk of cardiovascular and thromboembolic events, likely related to the prothrombotic plasma properties. The aim of this study was to assess the in vitro thrombin generation profile as a biomarker of plasma procoagulant properties in DM/PM patients.

METHODS

In 58 clinically stable DM/PM patients and 67 controls matched for sex, age, body mass index, we measured plasma thrombin generation potential using the Calibrated Automated Thrombinography (CAT) and analyzed its relationship with clinical disease characteristics, including autoantibodies profile.

RESULTS

Patients with DM/PM had a 21% increase in endogenous thrombin potential (ETP), 36% higher peak thrombin concentration, and 11% faster thrombin generation, compared to controls (p ​< ​0.001, all, also after adjustment for potential confounders). Interestingly, although both diseases did not differ in thrombin generation potential, heterogenous variables predicted elevated ETPs in both of them. In DM, that was higher fibrinogen, C-reactive protein, and total cholesterol, whereas in PM, presence of arthritis and increased blood platelet count. Surprisingly, thrombin formation capacity remained in a robust inverse relationship with serum troponin (r ​= ​-0.67, p ​< ​0.001) in the patient group.

CONCLUSIONS

DM/PM patients are characterized by an increased thrombin generation potential, suggesting prothrombotic plasma properties in both diseases. However, more studies are needed to verify its rationale and role in DM/PM clinical course and unfavorable clinical outcomes.

A Simple Evolutionary Model of Genetic Robustness After Gene Duplication

When a dispensable gene is duplicated (referred to the ancestral dispensability denoted by O⁺), genetic buffering and duplicate compensation together maintain the duplicate redundancy, whereas duplicate compensation is the only mechanism when an essential gene is duplicated (referred to the ancestral essentiality denoted by O^-). To investigate these evolutionary scenarios of genetic robustness, I formulated a simple mixture model for analyzing duplicate pairs with one of the following states: double dispensable (DD), semi-dispensable (one dispensable one essential, DE), or double essential (EE). This model was applied to the yeast duplicate pairs from a whole-genome duplication (WGD) occurred about 100 million years ago (mya), and the mouse duplicate pairs from a WGD occurred about more than 500 mya. Both case studies revealed that the proportion of essentiality for those duplicates with ancestral essentiality [P_E(O^-)] was much higher than that for those with ancestral dispensability [P_E(O⁺)]. While it was negligible in the yeast duplicate pairs, P_E(O⁺) (about 20%) was shown statistically significant in the mouse duplicate pairs. These findings, together, support the hypothesis that both sub-functionalization and neo-functionalization may play some roles after gene duplication, though the former may be much faster than the later.

Fibrin deposition associates with cartilage degeneration in arthritis

Background

Cartilage damage in inflammatory arthritis is attributed to inflammatory cytokines and pannus infiltration. Activation of the coagulation system is a well known feature of arthritis, especially in rheumatoid arthritis (RA). Here we describe mechanisms by which fibrin directly mediates cartilage degeneration.

Methods

Fibrin deposits were stained on cartilage and synovial tissue of RA and osteoarthritis (OA) patients and in murine adjuvant-induced arthritis (AIA) in wild-type or fibrinogen deficient mice. Fibrinogen expression and procoagulant activity in chondrocytes were evaluated using qRT-PCR analysis and turbidimetry. Chondro-synovial adhesion was studied in co-cultures of human RA cartilage and synoviocytes, and in the AIA model. Calcific deposits were stained in human RA and OA cartilage and in vitro in fibrinogen-stimulated chondrocytes.

Findings

Fibrin deposits on cartilage correlated with the severity of cartilage damage in human RA explants and in AIA in wild-type mice, whilst fibrinogen deficient mice were protected. Fibrin upregulated Adamts5 and Mmp13 in chondrocytes. Chondro-synovial adhesion only occurred in fibrin-rich cartilage areas and correlated with cartilage damage. In vitro, autologous human synoviocytes, cultured on RA cartilage explants, adhered exclusively to fibrin-rich areas. Fibrin co-localized with calcification in human RA cartilage and triggered chondrocyte mineralization by inducing pro-calcification genes (Anx5, Pit1, Pc1) and the IL-6 cytokine. Similar fibrin-mediated mechanisms were observed in OA models, but to a lesser extent and without pseudo-membranes formation.

Interpretation

In arthritis, fibrin plaques directly impair cartilage integrity via a triad of catabolism, adhesion, and calcification.

Funding

None.

Preparation and characterisation of ecdysterone/hydroxypropyl-Β-cyclodextrin inclusion complex with enhanced oral and transdermal bioavailability

To prepare ecdysterone (ES)/hydroxypropyl-β-cyclodextrin (HP-β-CD) inclusion complex, thus improving the water solubility and bioavailability of ES. Phase-solubility study was performed to study the mass ratio of ES and HP-β-CD. Then, the ES/HP-β-CD inclusion complex was prepared by the solvent evaporation method, and its physicochemical properties were characterised using the SEM, DSC, XRD, ¹HNMR and FT-IR. In addition, in vitro dissolution and bioavailability (oral and transdermal) experiments were also conducted. The inclusion complex was formed with ES and HP-β-CD at the mass ratio of 1:1. ES existed in an amorphous form in the inclusion complex. The equilibrium solubility of ES/HP-β-CD inclusion complex in SGF (simulated gastric fluid) and SIF (simulated intestinal fluid) was 50.6 ± 0.11 mg/mL and 75.9 ± 0.38 mg/mL in SGF and SIF, which was 5.93 and 9.96 times higher than that of free ES, respectively. The ES/HP-β-CD inclusion complex had better dissolution ability and transdermal permeability than the free ES. The oral bioavailability and the transdermal bioavailability were respectively increased by 2.97 times and 1.92 times compared with the free ES. These data suggest that the ES/HP-β-CD inclusion complex can be developed as potential pharmaceutical product for future clinical applications.

Interrelationship of Osteopontin, MMP-9 and ADAMTS4 in Patients With Osteoarthritis Undergoing Total Joint Arthroplasty

Osteoarthritis (OA) is a degenerative joint disease characterized by loss of articular cartilage, inflammation and pain, which sometimes necessitates total joint arthroplasty (TJA). Profiling biomarkers of cartilage degradation and inflammation is a promising area of research to understand the pathogenesis of OA. This study aims to report the post-operative fluctuations of 3 biomarkers of OA, osteopontin (OPN), matrix metalloproteinase-9 (MMP-9), and ADAMTS4 (a disintegrin and metalloproteinase with thrombospondin motifs 4), in patients undergoing TJA to further define the interaction among these biomarkers and delineate their role in OA pathogenesis. OPN is an extracellular matrix (ECM) glycoprotein with increased activity in OA and joint damage and is upregulated by either inflammation or cleavage by MMPs and thrombin. MMP-9 is known to cleave OPN and is upregulated by inflammatory markers, such as IL-1, IL-6 and CRP. ADAMTS4 is an enzyme that degrades aggrecan, a major component of cartilage. These biomarkers were measured in deidentified blood samples collected on the day of surgery, 1 day post-operatively, and day 5-7 post-operatively. MMP-9 and OPN levels were significantly elevated at all times, and ADAMTS4 was significantly decreased at baseline versus controls. OPN and ADAMTS4 inversely fluctuated post-operatively, indicating an interrelation between these 2 biomarkers. This study suggests that the upregulation of MMP-9 and therefore OPN then results in the downregulation of ADAMTS4. The relationship between OPN and thrombin also highlights the importance of monitoring for thrombotic complications. These biomarkers, along with thrombin-mediated cleavage products, may be helpful in the prognostic management of OA patients.

Interrelationship of MMP-9, Proteoglycan-4, and Inflammation in Osteoarthritis Patients Undergoing Total Hip Arthroplasty

Osteoarthritis (OA) is a chronic condition marked by joint pain, inflammation and loss of articular cartilage, that can be treated with total joint arthroplasty (TJA) at end stages. TJA is marked by post-operative inflammation, which directly effects levels of cartilage degradation biomarkers, proteoglycan-4 (PRG4) and matrix metalloproteinase-9 (MMP-9). PRG4 is a protective glycoprotein that is decreased in individuals with OA. MMP-9 is a matrix metalloproteinase that contributes to articular cartilage loss and is elevated in OA patients. It is upregulated by pro-inflammatory markers, such as IL-1, IL-6 and CRP. This study aims to elucidate the immediate post-operative changes in levels of PRG4, MMP-9, IL-6, CRP, and WBC in patients undergoing TJA to clarify the role of inflammation in recovery after surgery and in the overall pathogenesis of OA. Blood was collected at 3 time points (day 0, day 1 post-operatively, and days 5-7 post-operatively), from 63 patients undergoing TJA due to OA, and levels of these biomarkers were quantified. IL-6, CRP, WBC and MMP-9 were lowest at day 0, highest at day 1, and stabilized at an intermediate level at days 5-7. Meanwhile, PRG4 followed the opposite trend. These studies suggest that IL-6, CRP and WBC showed predictable fluctuations, with pro-inflammatory biomarkers upregulating MMP-9 and downregulating PRG4. Measuring these biomarkers may help expose the role of inflammation in the post-surgical recovery of TJA patients and in long-term pathogenesis of OA. These levels may help risk stratify patients pre-operatively and help develop individualized post-surgical plans.

Glucose suppresses IL-1β-induced MMP-1 expression through the FAK, MEK, ERK, and AP-1 signaling pathways

Osteoarthritis (OA) commonly affects the synovial joint and is characterized by degradation of articular cartilage. Increased matrix metalloproteinase (MMP) activity plays a major role in this degradation. Dextrose (D-glucose) prolotherapy has shown promising activity in the treatment of different musculoskeletal disorders, including OA. However, little is known about the role of glucose on MMP inhibition in OA therapy. We found that stimulating chondrocytes with the proinflammatory cytokine interleukin-1β (IL-1β) increased the expression of MMP-1, MMP-3, and MMP-13. Glucose reduced this increase in MMP-1 expression, but had no effect upon MMP-3 or MMP-13 expression. Analyses using a focal adhesion kinase (FAK) inhibitor, MEK inhibitors (U0126 and PD98059), an ERK inhibitor, AP-1 inhibitors (curcumin and tanshinone), or siRNAs demonstrated that the FAK, MEK, ERK, and AP-1 pathways mediate IL-1β-induced increases in MMP-1 expression. Glucose antagonized IL-1β-promoted phosphorylation of FAK, MEK, ERK, and c-Jun. Thus, glucose decreased IL-1β-induced MMP-1 expression through the FAK, MEK, ERK, and AP-1 signaling cascades. These findings may provide a better understanding of the mechanisms of prolotherapy on inhibiting MMP expression.

Chemokine C-C Motif Ligand 4 Gene Polymorphisms Associated with Susceptibility to Rheumatoid Arthritis

Chemokine C-C motif ligand 4 (CCL4) gene is a chemokine-encoding gene, and the polymorphism of CCL4 gene has been shown to predict risk of various diseases. We want to investigate whether the single nucleotide polymorphisms (SNPs) of the CCL4 gene can predict the risk of rheumatoid arthritis (RA). Between 2007 and 2015, we recruited 217 patients diagnosed with RA and 371 control participants. Comparative genotyping of the rs1634507, rs10491121, and rs1719153 SNPs was performed. When compared with participants with the A/A genotype of rs1719153, those with the A/T genotype were less likely to develop RA, as were those with the A/T+T/T genotype. The protective effect of the T-containing genotype was even more prominent among females. Those with A/T in rs1719153 were 56% less likely to develop RA compared with females with A/A; a similar protective effect was seen for females with the A/T+T/T genotype compared with those with A/A. The GTEx database revealed that patients carrying the T/T genotype had lower levels of CCL4 gene expression than those carrying the A/A genotype. These results indicate that the nucleotide T over the rs1719153 is associated with decreased CCL4 gene expression and decreased risk for RA.

Proteinases and their receptors in inflammatory arthritis: an overview

Proteinases are enzymes with established roles in physiological and pathological processes such as digestion and the homeostasis, destruction and repair of tissues. Over the past few years, the hormone-like properties of circulating proteinases have become increasingly appreciated. Some proteolytic enzymes trigger cell signalling via proteinase-activated receptors, a family of G protein-coupled receptors that have been implicated in inflammation and pain in inflammatory arthritis. Proteinases can also regulate ion flux owing to the cross-sensitization of transient receptor potential cation channel subfamily V members 1 and 4, which are associated with mechanosensing and pain. In this Review, the idea that proteinases have the potential to orchestrate inflammatory signals by interacting with receptors on cells within the synovial microenvironment of an inflamed joint is revisited in three arthritic diseases: osteoarthritis, spondyloarthritis and rheumatoid arthritis. Unanswered questions are highlighted and the therapeutic potential of modulating this proteinase-receptor axis for the management of disease in patients with these types of arthritis is also discussed.

Prognostic significance of high-mobility group box protein 1 genetic polymorphisms in rheumatoid arthritis disease outcome

Rheumatoid arthritis (RA) is a systemic inflammatory disease that causes chronic inflammation of the joints. Analysis of genetic variants offers promise for guiding treatment and improving outcomes in RA. High-mobility group box protein 1 (HMGB1) is a ubiquitous nuclear protein found in all mammal eukaryotic cells that participates in several biological functions including immune response, cell survival and apoptosis. We investigated the effects of HMGB1 gene polymorphisms on the risk of RA disease progression in a cohort of Chinese Han individuals. Four single nucleotide polymorphisms (SNPs) from the HMGB1 gene were selected and genotyped in 232 patients with RA and 353 healthy controls. We found that having one C allele in rs1360485 and one G allele in rs2249825 polymorphisms lowered the risk of RA in females. Moreover, among healthy controls, those who bore the C/G/T haplotype at SNPs rs1360485, rs2249825 and rs1412125 were at reduced risk of developing RA by 0.13-fold (p <0.05). This is the first report to examine the risk factors associated with HMGB1 SNPs in the development of RA disease in the Chinese Han population.