An assessment of the chondroprotective effects of intra-articular application of statin and tetracycline on early-stage experimental osteoarthritis

Cholesterol metabolism related genes in osteoarthritis

Cholesterol homeostasis plays a significant role in skeletal development and the dysregulation of cholesterol-related mechanism has been shown to be involved in the development of cartilage diseases including osteoarthritis (OA). Epidemiological studies have shown an association between elevated serum cholesterol levels and OA. Furthermore, abnormal lipid accumulation in chondrocytes as a result of abnormal regulation of cholesterol homeostasis has been demonstrated to be involved in the development of OA. Although, many in vivo and in vitro studies support the connection between cholesterol and cartilage degradation, the mechanisms underlying the complex interactions between lipid metabolism, especially HDL cholesterol metabolism, and OA remain unclear. The current review aims to address this problem and focuses on key molecular players of the HDL metabolism pathway and their role in ΟΑ pathogenesis. Understanding the complexity of biological processes implicated in OA pathogenesis, such as cholesterol metabolism, may lead to new targets for drug therapy of OA patients.

Ultrasound-targeted simvastatin-loaded microbubble destruction promotes OA cartilage repair by modulating the cholesterol efflux pathway mediated by PPARγ in rabbits

Aims

To evaluate the effect of ultrasound-targeted simvastatin-loaded microbubble destruction (UTMD_SV) for alleviation of the progression of osteoarthritis (OA) in rabbits through modulation of the peroxisome proliferator-activated receptor (PPARγ).

Methods

In vitro, OA chondrocytes were treated with ultrasound (US), US-targeted microbubble destruction (UTMD), simvastatin (SV), and UTMD_SV on alternate days for four weeks. Chondrocytes were also treated with PPARγ inhibitor, PPARγ inhibitor+ UTMD_SV, and UTMD_SV. The cholesterol efflux rate and triglyceride levels were measured using an assay kit and oil red O staining, respectively. In vivo, the OA rabbits were treated with a single intra-articular injection of UTMD, SV, and UTMD_SV every seven days for four weeks. Cartilage histopathology was assessed by safranin-O staining and the Mankin score. Total cholesterol (TC) and high-density lipoprotein-cholesterol (HDL-C) in rabbit knee synovial fluid were detected by enzyme-marker assay. Aggrecan, collagen II, and PPARγ expression levels were analyzed by Western blotting (WB).

Results

In vitro, UTMD_SV significantly increased the cholesterol efflux rate and aggrecan, collagen II, and PPARγ levels in OA chondrocytes; these effects were blocked by the PPARγ inhibitor. In vivo, UTMD_SV significantly increased aggrecan, collagen II, PPARγ, and HDL-C levels, while TC levels and Mankin scores were decreased compared with the UTMD, SV, OA, and control groups.

Conclusion

UTMD_SV promotes cartilage extracellular matrix synthesis by modulating the PPARγ-mediated cholesterol efflux pathway in OA rabbits.

Cite this article: Bone Joint Res 2021;10(10):693–703.

Tetracycline use in treating osteoarthritis: a systematic review

BACKGROUND AND AIMS

The purpose of the review was to synthesize the current literature regarding tetracyclines in the treatment of osteoarthritis.

METHODS

Using multiple databases, a systematic review was performed with customized search terms crafted to identify studies examining doxycycline or minocycline in the treatment of osteoarthritis. Results were classified into basic science mechanistic studies, in vivo animal studies, and human clinical trials. A total of 1446 potentially relevant studies were reviewed, and after exclusion criteria were applied, 23 investigations were included in the final analysis.

RESULTS

From 12 basic science mechanistic studies, we report on three main mechanisms by which tetracyclines may exert benefit in osteoarthritis progression: matrix metalloproteinase inhibition, immunomodulation, and nitric oxide synthase inhibition. Seven animal studies showed generally encouraging results. Four articles reported human clinical studies, showing mixed results in the treatment of osteoarthritis, potentially related to the choice of patient population, primary outcomes, and timing of treatment.

CONCLUSION

Tetracyclines have the potential to benefit osteoarthritis patients via multiple mechanisms. Further study is warranted to examine the optimal dose and timing of tetracycline treatment in osteoarthritis.

Modulation of the Inflammatory Process by Hypercholesterolemia in Osteoarthritis

Objective: Several studies have linked metabolic syndrome to the development of osteoarthritis (OA) through hypercholesterolemia, one of its components. However, epidemiological studies showed contradictory results, and it is not clear how hypercholesterolemia itself, or oxidized LDL (oxLDL)-a pathological molecule potentially involved in this relationship-could be affecting OA. The objectives of this study were to investigate the effect of hypercholesterolemia induced by high-fat diet (HFD) in cartilage from OA rabbits, and how oxLDL affect human chondrocyte inflammatory and catabolic responses. Design: New Zealand rabbits were fed with HFD for 18 weeks. On week 6, OA was surgically induced. At the end of the study, cartilage damage and IL-1β, IL-6, MCP-1, MMP-13, and COX-2 expression in articular cartilage were evaluated. In addition, cultured human OA articular chondrocytes were treated with oxLDL at concentrations equivalent to those expected in synovial fluid from HFD rabbits, in the presence of IL-1β and TNFα. The effect of oxLDL on cell viability, nitric oxide production and catabolic and pro-inflammatory gene expression was evaluated. Results: HFD intake did not modify cartilage structure or pro-inflammatory and catabolic gene expression and protein presence, both in healthy and OA animals. OxLDL did not affect human chondrocyte viability, ADAMTS5 and liver X receptor (LXR) α gene expression, but decreased the induction of IL-1β, IL-6, MCP-1, MMP-13, iNOS, and COX-2 gene expression and MMP-13 and COX-2 protein presence, evoked by cytokines. Conclusions: Our data suggest that cholesterol intake per se may not be deleterious for articular cartilage. Instead, cholesterol de novo synthesis and altered cholesterol metabolism could be involved in the associations observed in human disease.

Statin use and knee osteoarthritis progression: Results from a post-hoc analysis of the SEKOIA trial

OBJECTIVE

Epidemiological and experimental studies have suggested that lipid disorders might be involved in the pathophysiology of knee osteoarthritis (OA). Studies assessing the effect of statins on knee OA progression have shown conflicting results. We investigated the impact of statin use on radiological progression in patients with radiological and symptomatic knee OA.

METHODS

In total, 336 patients from the placebo arm of SEKOIA trial completed the 3-year follow-up and were included in this post-hoc analysis. Statin use was recorded at baseline interview. Minimal medial tibiofemoral joint space was measured on plain radiographs by an automated method at baseline and then annually. Radiologic progression was defined as joint space narrowing≥0.5mm over 3 years.

RESULTS

Overall, 71 patients were statin users (21.1%). They had a higher BMI (31.1±5.3 vs. 29.3±5.2kg/m², P=0.008), a higher sum of metabolic factors (≥3 factors: 43.7% vs 7.2%; P for trend<0.001) and a higher rate of radiological progression (49.3% vs. 32.1%, P=0.007) as compared to statin non-users. The significant association between radiological progression and statin use was independent of age, gender, WOMAC global score, disease duration, baseline joint space width, hypertension, type 2 diabetes, obesity (BMI>30kg/m²) and cardiovascular diseases [relative risk 1.49 (95% CI: 1.10-2.02), P=0.010].

CONCLUSION

Among patients with knee OA, statin use was associated with radiological worsening over 3 years, regardless of other potential confounding factors (obesity, type 2 diabetes, hypertension, disease duration, symptom intensity and radiological severity).

Does statin use have a disease modifying effect in symptomatic knee osteoarthritis? Study protocol for a randomised controlled trial

Background

Osteoarthritis (OA) is a major clinical and public health problem, with no current medications approved as having disease modifying effects. HMG-CoA reductase inhibitors, or “statins”, a drug class widely used to prevent cardiovascular events, could potentially affect OA progression via a number of mechanisms including their effects on lipid metabolism and inflammation. The aim of this multicentre, randomised, double-blind, placebo-controlled trial is to determine whether atorvastatin reduces the progression of knee structural changes and symptoms over 2 years in patients with symptomatic knee OA.

Methods/design

350 patients with symptomatic knee OA will be recruited through the OA Clinical Trial Network (in Melbourne, Hobart and Adelaide). They will be randomly allocated to the two arms of the study, receiving either 40 mg of atorvastatin or identical placebo once daily for 2 years. Magnetic resonance imaging of the knee will be performed at baseline and 2 years later. Knee structure, symptoms and function will be assessed using validated methods. The primary outcome is annual percentage change in knee cartilage volume. Secondary outcomes include progression of cartilage defects, bone marrow lesions, knee pain and function. The primary analysis will be by intention to treat, but per protocol analyses will also be performed.

Discussion

The study will provide high-quality evidence to address whether atorvastatin has a novel disease modifying effect in OA by delaying the structural and symptomatic progression of knee OA. Thus, the trial has major public health and clinical importance, as if found to be beneficial, atorvastatin could produce substantial cost savings by delaying and possibly reducing the need for joint replacement surgery, and provide marked improvements in quality of life for people with OA.

Trial registration

Australian New Zealand Clinical Trials Registry: ACTRN12613000190707, registered on 18 February 2013.