Liraglutide, a glucagon-like peptide 1 receptor agonist, exerts analgesic, anti-inflammatory and anti-degradative actions in osteoarthritis.

Osteoarthritis (OA) is a common disabling disease worldwide, with no effective and safe disease-modifying drugs (DMOAD) in the market. However, studies suggest that drugs, such as liraglutide, which possess strong potential in decreasing low-grade systemic inflammation may be effective in treating OA. Therefore, the aim of this study was to examine the anti-inflammatory, analgesic, and anti-degradative effects in OA using in vitro and in vivo experiments. The results showed that intra-articular injection of liraglutide alleviated pain-related behavior in in vivo sodium monoiodoacetate OA mouse model, which was probably driven by the GLP-1R-mediated anti-inflammatory activity of liraglutide. Moreover, liraglutide treatment significantly decreased IL-6, PGE2 and nitric oxide secretion, and the expression of inflammatory genes in vitro in chondrocytes and macrophages in a dose-dependent manner. Additionally, liraglutide shifted polarized macrophage phenotype in vitro from the pro-inflammatory M1 phenotype to the M2 anti-inflammatory phenotype. Furthermore, liraglutide exerted anti-catabolic activity by significantly decreasing the activities of metalloproteinases and aggrecanases, a family of catabolic enzymes involved in cartilage breakdown in vitro. Overall, the findings of this study showed that liraglutide ameliorated OA-associated pain, possess anti-inflammatory and analgesic properties, and could constitute a novel therapeutic candidate for OA treatment.

Pyrocarbon versus cobalt-chromium in the context of spherical interposition implants: an in vitro study on cultured chondrocytes.

In the context of shoulder surgical replacement, a new generation of spherical interposition implants has been developed, with the implant being a mobile spacer rubbing against the glenoid cartilage and humeral bone cavity. The aim of the present study was to compare pyrocarbon (PyC) versus cobalt-chromium (CoCr) implants, regarding preservation and regeneration of the surrounding tissues. The effect of the biomaterials on chondrocytes was analysed in vitro. Murine primary chondrocytes were grown on discs made of PyC or CoCr using two culture media to mimic either cartilage-like or bone-like conditions (CLC or BLC). Chondrocytes did grow on PyC and CoCr without alteration in cell viability or manifestation of cytotoxicity. The tissue-like cell membranes grown under BLC were examined for the chondrocyte's ability to mineralise (by alizarin red matrix staining, calcium deposit and alkaline phosphatase activity) and for their mechanical properties (by rheological tests). For the chondrocytes grown under CLC and BLC, extracellular matrix components were analysed by histological staining and immunolabelling. Under CLC, PyC promoted type II collagen expression in chondrocytes, suggesting that they may generate a more cartilage-like matrix than samples grown on both CoCr and plastic control. In BLC, the tissue-like cell membranes grown on PyC were more mineralised and homogenous. The mechanical results corroborated the biological data, since the elastic modulus of the tissue-like cell membranes developed on the PyC surface was higher, indicating more stiffness. Overall, the results suggested that PyC might be a suitable biomaterial for spherical interposition implants.

Differential expression of interleukin-17 and interleukin-22 in inflamed and non-inflamed synovium from osteoarthritis patients.

OBJECTIVE: Synovitis associated with osteoarthritis (OA) is directly responsible for several clinical symptoms and reflects OA's structural progression. This study sought to analyze the expression of proinflammatory mediations, including Interleukin (IL)-17 and IL-22, which play key roles in regulating inflammatory processes, in inflamed and non-inflamed areas of osteoarthritic synovium. METHODS: Synovium from knees of 32 OA patients were collected at surgery. Macroscopic evaluation of inflammation enabled inflamed and non-inflamed areas to be separated. Samples were incubated to obtain tissue-conditioned media. Quantitative mRNA expression of proinflammatory mediators was analyzed by RT-PCR and protein levels by ELISA and gelatin zymography. Immunohistochemistry and histology were performed. RESULTS: Inflamed synovium were characterized by increased leukocyte infiltration and a higher vessel-to-tissue area ratio than non-inflamed tissues. Macrophages, T and B lymphocytes, and some neutrophils were found only in the inflamed tissue, and only in the subintimal layer. Levels of proinflammatory cytokines and MMP-9 were significantly higher in tissue-conditioned media from inflamed than non-inflamed tissues. Inflamed areas were associated with higher expression of IL-17 and IL-22, both correlated with the combined release of IL-6, IL-23, and TGFß1. CONCLUSION: Our results showed that inflammatory cytokines, including IL-17 and IL-22, are expressed at higher levels by inflamed OA synovium and suggest IL-22 involvement in OA pathophysiology. This study will help identify new therapeutic strategies for OA, especially the targeting of IL-22 to decrease inflammation.

What understanding tendon cell differentiation can teach us about pathological tendon ossification.

Tendons are the structures that attach muscles to bones and transmit mechanical forces. Tendon cells are composed of mature tenocytes and a rare population of tendon stem cells. Both cell types ensure homeostasis and repair of tendon extracellular matrix to guarantee its specific mechanical properties. Moreover, tendon cells seem to present a marked potential for trans-differentiation, predominantly into the chondrocyte and osteoblast lineages. In this review article, we first present chronic tendon pathologies associated with abnormal ossification, such as spondyloarthritis and calcifying tendinopathy, and discuss how tendon cell differentiation and trans-differentiation may participate in these diseases. We moreover present the factors known to influence tendon cell differentiation and trans-differentiation, with a particular emphasis on extracellular environment, mechanical stimulation and several soluble factors that can tip the balance toward one or another lineage. A better understanding of the neglected tendon cell biology may be extremely useful to understand the pathological mechanisms of spondyloarthritis and calcifying tendinopathy.

Backbone and side-chain 1H, 15N and 13C assignment of apo- and imipenem-acylated L,D-transpeptidase from Bacillus subtilis.

The D,D-transpeptidase activity of Penicillin Binding Proteins (PBPs) is essential to maintain cell wall integrity. PBPs catalyze the final step of the peptidoglycan synthesis by forming 4 → 3 cross-links between two peptide stems. Recently, a novel ß-lactam resistance mechanism involving L,D-transpeptidases has been identified in Enterococcus faecium and Mycobacterium tuberculosis. In this resistance pathway, the classical 4 → 3 cross-links are replaced by 3 → 3 cross-links, whose formation are catalyzed by the L,D-transpeptidases. To date, only one class of the entire ß-lactam family, the carbapenems, is able to inhibit the L,D-transpeptidase activity. Nevertheless, the specificity of this inactivation is still not understood. Hence, the study of this new transpeptidase family is of considerable interest in order to understand the mechanism of the L,D-transpeptidases inhibition by carbapenems. In this context, we present herein the backbone and side-chain (1)H, (15)N and (13)C NMR assignment of the L,D-transpeptidase from Bacillus subtilis (Ldt(Bs)) in the apo and in the acylated form with a carbapenem, the imipenem.

[Human chondrocyte responsiveness to bone morphogenetic protein-2 after their in vitro dedifferentiation: potential use of bone morphogenetic protein-2 for cartilage cell therapy]. / Réponse des chondrocytes humains à la bone morphogenetic protein-2 après leur dédifférenciation in vitro : utilisation potentielle de la bone morphogenetic protein-2 pour la thérapie cellulaire du cartilage.

AIM OF THE STUDY: Cartilage has a limited capacity for healing after trauma. Autologous chondrocyte implantation is widely used for the treatment of patients with focal damage to articular cartilage. Chondrocytes are isolated from biopsy specimen, cultured in monolayers on plastic then transplanted over the cartilage defect. However, chondrocyte amplification on plastic triggers their dedifferentiation. This phenomenon is characterized by loss of expression of type II collagen, the most abundant cartilage protein. The challenge for autologous chondrocyte implantation is to provide patients with well-differentiated cells. The aim of the present study was to test the capability of bone morphogenetic protein (BMP)-2 to promote redifferentiation of human chondrocytes after their expansion on plastic. MATERIALS AND METHODS: Chondrocytes extracted from nasal cartilage obtained after septoplasty were serially cultured in monolayers. After one, two or three passages, BMP-2 was added to the culture medium. The cellular phenotype was characterized at the gene level by using RT-PCR. The expression of genes coding for type II procollagen with the ratio of IIB/IIA forms, aggrecan, Sox9, osteocalcin and type I procollagen was monitored. RESULTS: Our results show that BMP-2 can stimulate chondrogenic expression of the chondrocytes amplified on plastic, without inducing osteogenic expression. However, this stimulatory effect decreases with the number of passages. CONCLUSION: The efficiency of autologous chondrocyte implantation could be improved by using chondrocytes treated with BMP-2 during their in vitro preparation.

Backbone solution structures of proteins using residual dipolar couplings: application to a novel structural genomics target.

Structural genomics (or proteomics) activities are critically dependent on the availability of high-throughput structure determination methodology. Development of such methodology has been a particular challenge for NMR based structure determination because of the demands for isotopic labeling of proteins and the requirements for very long data acquisition times. We present here a methodology that gains efficiency from a focus on determination of backbone structures of proteins as opposed to full structures with all sidechains in place. This focus is appropriate given the presumption that many protein structures in the future will be built using computational methods that start from representative fold family structures and replace as many as 70% of the sidechains in the course of structure determination. The methodology we present is based primarily on residual dipolar couplings (RDCs), readily accessible NMR observables that constrain the orientation of backbone fragments irrespective of separation in space. A new software tool is described for the assembly of backbone fragments under RDC constraints and an application to a structural genomics target is presented. The target is an 8.7 kDa protein from Pyrococcus furiosus, PF1061, that was previously not well annotated, and had a nearest structurally characterized neighbor with only 33% sequence identity. The structure produced shows structural similarity to this sequence homologue, but also shows similarity to other proteins, which suggests a functional role in sulfur transfer. Given the backbone structure and a possible functional link this should be an ideal target for development of modeling methods.

Paramagnetic NMR investigations of high-spin nickel(II) complexes. Controlled synthesis, structural, electronic, and magnetic properties of dinuclear vs. mononuclear species.

New dissymmetric tertiary amines (N(3)SR) with varying N/S donor sets have been synthesized to provide mono- and dinuclear complexes. Acetate ions are used to complete the octahedral coordination sphere around nickel(II) atom(s). The facile conversion of mononuclear to dinuclear systems can be controlled to produce either mono- or dinuclear complexes from the same ligand. The dinuclear complex a(BPh(4))(2) ([Ni(2)(N(3)SSN(3))(OAc)(2)](BPh(4))(2)) has been characterized in the solid state by X-ray diffraction techniques as solvate: a(BPh(4))(2).(1/2)[5(CH(3)OH).(CH(3)CN).(CH(3)CH(2)OH)]. The two Ni atoms are six-coordinated and bridged by a disulfide group and two bidentate acetates. Magnetic susceptibility reveals a weak ferromagnetic exchange interaction between the two Ni atoms with J = 2.5(7) cm(-1). UV-vis studies suggest that the six-coordinated structure persists in solution. The (1)H NMR spectrum of a(BPh(4))(2) exhibits sharp significantly hyperfine shifted ligand signals. A complete assignment of resonances is accomplished by a combination of methods: 2D-COSY experiments, selective chemical substitution, and analysis of proton relaxation data. Proton isotropic hyperfine shifts are shown to originate mainly from contact interactions and to intrinsically contain a small J-magnetic coupling and/or zero-field splitting contribution. A temperature dependence study of longitudinal relaxation times indicates that a very unusual paramagnetic Curie dipolar mechanism is the dominant relaxation pathway in these weakly ferromagnetically spin-coupled dinickel(II) centers. The mononuclear nickel(II) analogue exhibits extremely broader (1)H NMR signals and only partial analysis could be performed. These data are consistent with a shortening of electronic relaxation times in homodinuclear compounds with respect to the corresponding mononuclear species.