Several clinical studies demonstrated that glucosamine sulfate (GS) is effective in controlling osteoarthritis (OA), showing a structure-modifying action. However, little is known about the molecular mechanism(s) by which GS exerts such action and about the effects of GS at a tissue level on osteoarthritic cartilage and other joint structures. Here we provide mechanistic evidence suggesting that in vitro GS attenuates NF-κB activation at concentrations in the range of those observed after GS administration to volunteers and patients, thus strengthening previous findings. Furthermore, we describe the effects of GS at a tissue level on the progression of the disease in a relevant model of spontaneous OA, the STR/ort mouse. In this model, the administration of GS at human corresponding doses was associated with a significant decrease of OA scores. Histomorphometry showed that the lesion surface was also significantly decreased, while the number of viable chondrocytes within the matrix was significantly increased. GS improved the course of OA in the STR/Ort mouse, by delaying cartilage breakdown as assessed histologically and histomorphometrically.

BackgroundProstaglandin E2 (PGE2) acts via its EP4 receptor as a cytokine amplifier (e.g., interleukin [IL]-6) and induces the differentiation and expansion of inflammatory T-helper (Th) lymphocytes. These mechanisms play a key role in the onset and progression of rheumatoid arthritis (RA). We present the pharmacological characterisation of CR6086, a novel EP4 receptor antagonist, and provide evidence for its potential as a disease-modifying anti-rheumatic drug (DMARD).MethodsCR6086 affinity and pharmacodynamics were studied in EP4-expressing HEK293 cells by radioligand binding and cyclic adenosine monophosphate (cAMP) production, respectively. In immune cells, IL-6 and vascular endothelial growth factor (VEGF) expression were analysed by RT-PCR, and IL-23 and IL-17 release were measured by enzyme-linked immunosorbent assay (ELISA). In collagen-induced arthritis (CIA) models, rats or mice were immunised with bovine collagen type II. Drugs were administered orally (etanercept and methotrexate intraperitoneally) starting at disease onset. Arthritis progression was evaluated by oedema, clinical score and histopathology. Anti-collagen II immunoglobulin G antibodies were measured by ELISA.ResultsCR6086 showed selectivity and high affinity for the human EP4 receptor (Ki = 16.6 nM) and functioned as a pure antagonist (half-maximal inhibitory concentration, 22 nM) on PGE2-stimulated cAMP production. In models of human immune cells in culture, CR6086 reduced key cytokine players of RA (IL-6 and VEGF expression in macrophages, IL-23 release from dendritic cells, IL-17 release from Th17 cells). In the CIA model of RA in rats and mice, CR6086 significantly improved all features of arthritis: severity, histology, inflammation and pain. In rats, CR6086 was better than the selective cyclooxygenase-2 inhibitor rofecoxib and at least as effective as the Janus kinase inhibitor tofacitinib. In mice, CR6086 and the biologic DMARD etanercept were highly effective, whereas the non-steroidal anti-inflammatory drug naproxen was ineffective. Importantly, in a study of CR6086/methotrexate, combined treatment greatly improved the effect of a fully immunosuppressive dose of methotrexate.ConclusionsCR6086 is a novel, potent EP4 antagonist showing favourable immunomodulatory properties, striking DMARD effects in rodents, and anti-inflammatory activity targeted to immune-mediated inflammatory diseases and distinct from the general effects of cyclooxygenase inhibitors. These results support the clinical development of CR6086, both as a stand-alone DMARD and as a combination therapy with methotrexate. The proof-of-concept trial in patients with RA is ongoing.Electronic supplementary materialThe online version of this article (10.1186/s13075-018-1537-8) contains supplementary material, which is available to authorized users.

No abstract

Endothelium is an early target of pro-atherosclerotic events, which may result in functional and morphological perturbations. Oxidized low density lipoproteins, an atherogenic factor with strong cytotoxicity, may potentially contribute to altered endothelial function through the activation of a stress response, which would rescue cells to full vitality, or, conversely, by leading to cell death. Evidence is presented here for the ability of chemically oxidized low density lipoproteins to induce the synthesis of the inducible form of heat shock protein 70 in cultured human endothelial cells, and for the association of epitopes of these modified lipoproteins with apoptotic endothelial cells in aortic sections from hypercholesterolemic rabbits.

Abstract-Oxidized low density lipoproteins (OxLDLs) are believed to play a central role in atherogenesis and to possess a wide variety of biological properties; among them, OxLDLs are cytotoxic to cultured vascular cells in that they induce necrosis and apoptosis. Moreover, OxLDLs are known to induce the expression of heat shock protein 70 (Hsp70), a protein that protects cells from several cytotoxic stimuli. To determine whether Hsp70 can protect cells against OxLDL-induced cytotoxicity, COS-1 cells were transfected with a construct containing human Hsp70. A number of cell lines permanently expressing Hsp70 were obtained, 1 of which (cos-Hsp70/10, with high Hsp70 expression) was selected for further studies. Hsp70 overexpression protected cells from toxic stimuli, such as H 2 O 2 , UV irradiation, and heat shock, suggesting that the overexpressed protein was functional. When incubated with OxLDLs, however, the clone overexpressing Hsp70 showed a significant decrease in viability, as determined by the [ 3 H]adenine release assay (319.8Ϯ3.16% of control for transfected cells versus 217.6Ϯ6.08% for control cells exposed to 100 g protein/mL of OxLDL), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (12.5Ϯ0.9% versus 28.9Ϯ1.99% of control, respectively), and LDH release (48.4Ϯ0.04% versus 15.2Ϯ0.06% of control cells). The increased expression of Bax and the decreased expression of Bcl-2 (a proapoptotic and an antiapoptotic protein, respectively) in cos-Hsp70/10 cells and in control cells on incubation with OxLDLs suggested that overexpression of Hsp70 did not confer protection against apoptosis induced by OxLDLs. The analysis of nucleosome content and the nuclear staining with Hoechst 33258 confirmed this finding. These data suggest that overexpression of Hsp70 not only fails to protect COS-1 cells against OxLDL-induced apoptosis but rather confers a higher sensitivity to the cytotoxic action of these lipoproteins. Thus, the Hsp70 response, although induced by OxLDLs, cannot protect cells from lipoprotein toxicity. Key Words: low density lipoproteins Ⅲ apoptosis Ⅲ necrosis Ⅲ Bcl-2 Ⅲ Bax W hen exposed to stresses, such as high temperature or other toxic stimuli, cells react by synthesizing stress proteins, also named heat shock proteins (Hsps). [1][2][3][4][5][6] Hsps include constitutive and inducible forms. Constitutive Hsps play important biological roles, including facilitation of the correct folding of newly synthesized polypeptides 7 and their transport across cellular membranes 8 -10 ; inducible forms, expressed by cells under stress conditions, are believed to protect cellular proteins from denaturation. 11 Hsps show a very high degree of homology among different organisms 12 ; Hsp70, the major Hsp, is the most conserved throughout evolution 13 and plays a key role in protecting cells from environmental stresses. 14 In fact, overexpression of Hsp70 confers thermotolerance and increases cell survival in the presence of noxious stimuli. [15][16][17][18][19] Interestingly, the cellular conten...