Human C-reactive protein aggravates osteoarthritis development in mice on a high-fat diet

Objective: C-reactive protein (CRP) levels can be elevated in osteoarthritis (OA) patients. In addition to indicating systemic inflammation, it is suggested that CRP itself can play a role in OA development. Obesity and metabolic syndrome are important risk factors for OA and also induce elevated CRP levels. Here we evaluated in a human CRP (hCRP)-transgenic mouse model whether CRP itself contributes to the development of ‘metabolic’ OA.Design: Metabolic OA was induced by feeding 12-week-old hCRP-transgenic males (hCRP-tg, n = 30) and wild-type littermates (n = 15) a 45 kcal% high-fat diet (HFD) for 38 weeks. Cartilage degradation, osteophytes and synovitis were graded on Safranin O-stained histological knee joint sections. Inflammatory status was assessed by plasma lipid profiling, flow cytometric analyses of blood immune cell populations and immunohistochemical staining of synovial macrophage subsets.Results: Male hCRP-tg mice showed aggravated OA severity and increased osteophytosis compared with their wild-type littermates. Both classical and non-classical monocytes showed increased expression of CCR2 and CD86 in hCRP-tg males. HFD-induced effects were evident for nearly all lipids measured and indicated a similar low-grade systemic inflammation for both genotypes. Synovitis scores and synovial macrophage subsets were similar in the two groups.Conclusions: Human CRP expression in a background of HFD-induced metabolic dysfunction resulted in the aggravation of OA through increased cartilage degeneration and osteophytosis. Increased recruitment of classical and non-classical monocytes might be a mechanism of action through which CRP is involved in aggravating this process. These findings suggest interventions selectively directed against CRP activity could ameliorate metabolic OA development

The catabolic-to-anabolic shift seen in the canine osteoarthritic cartilage treated with knee joint distraction occurs after the distraction period

Background Cartilage regenerative mechanisms initiated by knee joint distraction (KJD) remain elusive. Animal experiments that are representative for the human osteoarthritic situation and investigate the effects of KJD at consecutive time points could be helpful in this respect but are lacking. This study investigated the effects of KJD on the osteoarthritic joint of dogs on two consecutive timepoints. Methods Osteoarthritis was bilaterally induced for 10 weeks in 12 dogs using the groove model. Subsequently, KJD was applied to the right hindlimb for 8 weeks. The cartilage, subchondral bone and synovial membrane were investigated directly after KJD treatment, and after 10 weeks of follow-up after KJD treatment. Macroscopic and microscopic joint tissue alterations were investigated using the OARSI grading system. Additionally, proteoglycan content and synthesis of the cartilage were assessed biochemically. RT-qPCR analysis was used to explore involved signaling pathways. Results Directly after KJD proteoglycan and collagen type II content were reduced accompanied by decreased proteoglycan synthesis. After 10 weeks of follow-up, proteoglycan and collagen type II content were partly restored and proteoglycan synthesis increased. RT-qPCR analysis of the cartilage suggests involvement of the TGF-β and Notch signalling pathways. Additionally, increased subchondral bone remodelling was found at 10 weeks of follow-up. Conclusion While the catabolic environment in the cartilage is still present directly after KJD, at 10 weeks of follow-up a switch towards a more anabolic joint environment was observed. Further investigation of this timepoint and the pathways involved might elucidate the regenerative mechanisms behind KJD. The Translational Potential of this Article Further elucidation of the regenerative mechanisms behind KJD could improve the existing KJD treatment. Furthermore, these findings could provide input for the discovery or improvement of other joint regenerative treatment strategies

Selective COX-2 inhibition is favorable to human early and late-stage osteoarthritic cartilage: a human in vitro study

SummaryObjectiveNonsteroidal anti-inflammatory drugs (NSAIDs) are widely used in the treatment of osteoarthritis (OA). For the outcome of treatment the direct effects of NSAIDs on cartilage may be more important than indirect effects on inflammation, considered being secondary in OA. For clinical practice, it is relevant to study effects of NSAIDs on early stages of OA. Therefore we studied the direct effects of celecoxib on human degenerated OA cartilage and compared the effects with those on human healthy cartilage and human end-stage OA cartilage.MethodsDegenerated, late-stage OA, and healthy human articular cartilage were exposed (7 days of culture) to celecoxib (0.1–10μM). Changes in cartilage proteoglycan turnover (synthesis, retention, and release), proteoglycan content, prostaglandin E2 (PGE2) and nitric oxide (NO) production were determined.ResultsBoth degenerated and established OA cartilage showed its characteristic changes in proteoglycan turnover (all P<0.05). Celecoxib at 1μM was able to increase synthesis of degenerated cartilage and normalize both releases of newly formed and resident proteoglycans. Importantly, 1μM celecoxib influenced matrix integrity by enhancing proteoglycan content. Similar results were found for end-stage OA cartilage. Enhanced PGE2 production in degenerative and OA cartilage could be decreased by celecoxib, whereas no effect on enhanced NO production was found. No significant effects of celecoxib on normal cartilage were found.DiscussionCelecoxib, in a clinical relevant concentration, showed in vitro a significant beneficial effect, not only on late-stage OA but also on more early stages of OA, whereas healthy cartilage remained unaffected, suggesting chondroprotective properties of celecoxib in the treatment of degenerative joint disorders

Cytotoxicity and neurocytotoxicity of new marine anticancer agents evaluated using in vitro assays

Purpose: New classes of anticancer drugs, isolated from marine organisms, have been shown to possess cytotoxic activity against multiple tumor types. Aplidine, didemnin B, and isohomohalichondrin B (IHB), among the more promising antitumor candidates, have been evaluated in the present study on a comparative basis in terms of their antiproliferative activity and neurotoxic effects in vitro. Methods: Using a panel of different human, prostatic cancer cell lines (DU 145, PC-3 and LNCaP-FGC) the effects of Aplidine, didemnin B, and IHB on tumor cell proliferation were tested in a colorimetric (XTT) assay and compared with the effects of vincristine, vinorelbine, and Taxol. Under analogous in vitro conditions these drugs were also monitored for neurocytotoxic effects using a PC 12 cell line based model. Results: Didemnin B and - especially Aplidine were more effective in the inhibition of prostate cancer cell proliferation than vincristine, vinorelbine or Taxol at concentration levels between 5 and 50 pmol/ml. At these same concentrations, however, Didemnin B and Aplidine were also most potent in the in vitro neurotoxicity assays. IHB was found to exert even more potent antiproliferative activity (at concentration levels between 0.05 and 0.1 pmol/ml). However, neurotoxic effects were also found to be present at these levels. After drug withdrawal, the neurotoxic damage, inflicted by aplidine or IHB appeared to be more long lasting than after vincristine or vinorelbine exposure. Conclusions: These results point to high antiproliferative activity of aplidine and IHB in prostate cancer. At the same time, the data urge some caution in the clinical use of these agents because of potential neurotoxic side-effects. The use of a newly formulated Aplidine may involve a more favorable therapeutic profile