Effect of fatty acids on bone marrow lesions and knee cartilage in healthy, middle-aged subjects without clinical knee osteoarthritis

5,7,3',4'-tetramethoxyflavone ameliorates cholesterol dysregulation by mediating SIRT1/FOXO3a/ABCA1 signaling in osteoarthritis chondrocytes

Dyslipidemia has been associated with the development of osteoarthritis. Our previous study found that 5,7,3',4'-tetramethoxyflavone (TMF) exhibited protective activities against the pathological changes of osteoarthritis. Aim: To investigate the roles of TMF in regulating ABCA1-mediated cholesterol metabolism. Methods: Knockdown and overexpression were employed to study gene functions. Protein-protein interaction was investigated by co-immunoprecipitation, and the subcellular locations of proteins were studied by immunofluorescence. Results: IL-1β decreased ABCA1 expression and induced apoptosis. Therapeutically, TMF ameliorated the effects of IL-1β. FOXO3a knockdown expression abrogated the effects of TMF, and FOXO3a overexpression increased ABCA1 expression by interacting with LXRα. TMF promoted FOXO3a nuclear translocation by activating SIRT1 expression. Conclusions: TMF ameliorates cholesterol dysregulation by increasing the expression of FOXO3a/LXRα/ABCA1 signaling through SIRT1 in C28/I2 cells.

Metabolic syndrome and subchondral bone alterations: The rise of osteoarthritis - A review

Metabolic syndrome (MS) has become one of the top major health burdens for over three decades not only due to its effects on cardiovascular health but also its implications in orthopedics. Extensive research has shown that MS is tightly linked to osteoarthritis and inflammation, a process which appears to primarily occur in the subchondral bone via the incidence of bone-marrow lesions (BMLs). Numerous studies identify obesity, dyslipidemia, insulin resistance and hypertension as the top metabolic risk factors, the so-called "deadly quartet". These factors are responsible for the disruptive physiological processes that culminate in detrimental alterations within the subchondral bone, cartilage damage and, overall, the predominant pro-inflammatory joint microenvironment. Although it has long been thought that osteoarthritis was limited to the cartilage component of the joint, other studies indicate that the disease may originate from the harmful alterations that occur primarily in the subchondral bone, especially via means of vascular pathology. Since metabolic risk factors are manageable to a certain extent, it is therefore possible to decelerate the progression of OA and mitigate its devastating effects on the subchondral bone and subsequent articular cartilage damage.

METHODS

Literature was reviewed using PubMed and Google Scholar in order to find a correlation between metabolic syndrome and osteoarthritic progression. The investigation included a combination of nomenclature such as: "metabolic syndrome", "obesity", "insulin resistance", "hypertension", "dyslipidemia", "low-grade systemic inflammation", "osteoarthritis", "subchondral bone", "cartilage" and "inflammatory biomarkers".

CONCLUSION

Based on several studies, there seems to be a significant association between The Deadly Quartet (metabolic syndrome), dysregulation of both pro- and anti-inflammatory biomarkers, and osteoarthritic progression arising from unbridled systemic inflammation.

Osteoarthritis Is a Low-Grade Inflammatory Disease: Obesity's Involvement and Herbal Treatment

Osteoarthritis (OA) is considered a major cause of disability around the globe. This handicapping disease causes important cartilage and bone alteration that is associated with serious pains and loss of joint function. Despite its frequent association with obesity, the aetiology of OA is not fully understood. In this review, the different aspects of OA and its correlation with obesity were analysed. Through examining different mechanisms by which obesity may trigger and/or exacerbate OA, we point out some relevant signalling pathways that may evolve as candidates for pharmacological drug development. As such, we also suggest a review of different herbal medicines (HMs) and their main compounds, which specifically interfere with the identified pathways. We have shown that obesity's involvement in OA is not only limited to the mechanical weight exerted on the joints (mechanical hypothesis), but also induces an inflammatory state by different mechanisms, including increased leptin expression, compromised gut mucosa, and/or gut microbiota disruption. The main signalling pathways involved in OA inflammation, which are associated with obesity, are protein tyrosine phosphatase 1B (PTP1B) and TLR4 or DAP12. Moreover, we also underline the contamination of plant extracts with LPS as an important factor to consider when studying HM's effects on articular cells. By summarizing recent publications, this review aims at highlighting newly established aspects of obesity involvement in OA other than the mechanical one.

Type 2 diabetes mellitus and osteoarthritis

OBJECTIVES

Type 2 diabetes mellitus (T2DM) and osteoarthritis (OA) are common diseases that frequently co-exist, along with overweight/obesity. While the mechanical impact of excess body weight on joints may explain lower limb OA, we sought to explore whether T2DM is linked to OA outside of excess weight and whether T2DM may play a role in OA pathophysiology. The consequence of T2DM on OA outcomes is a question of research interest.

METHODS

We conducted a critical review of the literature to explore the association between T2DM and OA, whether any association is site-specific for OA, and whether the presence of T2DM impacts on OA outcomes. We also reviewed the literature to assess the safety of anti-OA treatments in patients with T2DM.

RESULTS

T2DM has a pathogenic effect on OA through 2 major pathways involving oxidative stress and low-grade chronic inflammation resulting from chronic hyperglycemia and insulin resistance. T2DM is a risk factor for OA progression and has a negative impact on arthroplasty outcomes. Evidence is mounting for safety concerns with some of the most frequently prescribed anti-OA medications, including paracetamol, non-steroidal anti-inflammatory drugs, and corticosteroid injections, while other anti-OA medications may be safely prescribed in OA patients with T2DM, such as glucosamine and intra-articular hyaluronic acid.

CONCLUSIONS

Future research is needed to better understand whether diabetes control and prevention can modulate OA occurrence and progression. The selection of therapy to treat OA symptoms in patients with T2DM may require careful consideration of the evidence based to avoid untoward safety issues.

Nutrition, osteoarthritis and cartilage metabolism

BACKGROUND

Osteoarthritis (OA) is a degenerative joint disease and a leading cause of adult disability. There is no cure for OA and there is no effective treatment to stop its progression. Current pharmacologic treatments such as analgesics and non-steroidal anti-inflammatory drugs may improve the pain and offer some relief but they do not affect the progression of the disease. The chronic intake of these drugs may result in severe adverse events. The aim of this review is to revise the effects of nutrition on cartilage metabolism and OA progression.

METHODS

A systematic literature search was performed including those related to macro- and micro-nutrients' actions on cartilage and OA outcome. We selected peer-reviewed articles reporting the results of human clinical trials.

RESULTS

Glucosamine and chondroitin sulfate have shown to delay OA knee progression in several clinical trials. The effectiveness of some products considered nutraceuticals has been widely reviewed in the literature. This article presents a general description of the effectiveness and mechanism of action of nutrients, vitamins, antioxidants and other natural components considered as part of the normal diet. Many in vitro studies indicate the efficacy of specific nutrients in cartilage metabolism and its involvement in OA. However, rigorous clinical studies needed to evaluate the efficacy of these compounds in humans are still missing. The influence of nutrients and diet on the metabolism of cartilage and OA could represent a long-term coadjuvant alternative in the management of patients with OA. Effects of diet modifications on lipid and cholesterol profiles, adequate vitamin levels and weight reduction in obese patients could influence the course of the disease.

CONCLUSION

This review demonstrates that nutrition can improve the symptoms of OA. Glucosamine and chondroitin sulfate have shown robustly to delay the progression of knee OA in several well-designed studies, however more controlled clinical trials are needed to conclude that nutritional changes slow down the progression of the disease.

What is the evidence for a role for diet and nutrition in osteoarthritis?

As current treatment options in OA are very limited, OA patients would benefit greatly from some ability to self-manage their condition. Since diet may potentially affect OA, we reviewed the literature on the relationship between nutrition and OA risk or progression, aiming to provide guidance for clinicians. For overweight/obese patients, weight reduction, ideally incorporating exercise, is paramount. The association between metabolic syndrome, type-2 diabetes and OA risk or progression may partly explain the apparent benefit of dietary-lipid modification resulting from increased consumption of long-chain omega-3 fatty-acids from oily fish/fish oil supplements. A strong association between OA and raised serum cholesterol together with clinical effects in statin users suggests a potential benefit of reduction of cholesterol by dietary means. Patients should ensure that they meet the recommended intakes for micronutrients such as vitamin K, which has a role in bone/cartilage mineralization. Evidence for a role of vitamin D supplementation in OA is unconvincing.

Association between Dietary Glycemic Index and Knee Osteoarthritis: The Korean National Health and Nutrition Examination Survey 2010-2012

BACKGROUND

Obesity and metabolic abnormalities are important risk factors for knee osteoarthritis (KOA). Recent epidemiologic studies have found that a high glycemic index (GI) and glycemic load (GL) diet are associated with a higher risk for metabolic complications and cardiovascular mortality.

OBJECTIVE

We aimed to examine the association between dietary GI, dietary GL, and KOA among Korean adults.

DESIGN

This was a cross-sectional study that analyzed data obtained from the Korean National Health and Nutrition Examination Survey 2010-2012.

PARTICIPANTS/SETTING

A total of 9,203 participants (5,275 women) aged ≥50 years were included.

MAIN OUTCOME MEASURES

KOA was defined as the presence of radiographic features of Kellgren-Lawrence grade ≥2. Chronic knee pain was defined as the presence of knee pain for more than 30 days during the past 3 months. Dietary information was collected using a single 24-hour recall method.

STATISTICAL ANALYSES PERFORMED

The association between the quintiles of dietary GI and dietary GL and knee conditions was analyzed using a multinomial logistic regression analysis adjusting for age, physical activity, obesity, hypertension and diabetes, serum low-density lipoprotein, and total energy intake.

RESULTS

Among the women, the association between dietary GI and symptomatic KOA was: quintile 1: 1.00 (reference); quintile 2: 1.29 (95% CI 0.87 to 1.92); quintile 3: 1.59 (95% CI 1.11 to 2.28); quintile 4: 1.74 (95% CI 1.21 to 2.51); and quintile 5: 1.77 (95% CI 1.20 to 2.60) (P=0.001). Chronic knee pain without KOA was associated with dietary GI; however, this association was not linear across quintiles. There was no significant association between dietary GI and asymptomatic KOA. Among the men, no significant association was found between dietary GI and any knee conditions. There was no significant association between dietary GL and KOA in both men and women.

CONCLUSIONS

There was a significant positive association between dietary GI and symptomatic KOA in women.

Diclofenac - induced hepatotoxicity: Low dose of omega-3 fatty acids have more protective effects

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Diclofenac sodium instigates pro-oxidative and pro-inflammatory responses.

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Dietary supplementation with omega-3 fatty acids (N-3) boost the antioxidant system.

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Low dose of N-3 has more hepatoprotective effects than the high.

The global embrace of the Western dietary style has necessitated the need for supplementation with omega-3 fatty acids (N-3) to redress the imbalance in omega-6/omega-3 fatty acids ratio. Therefore, the study investigated the effects of pre-treatment with N-3 in adult male Wistar rats exposed to diclofenac sodium (DF). Twenty adult male Wistar rats were used for this study. They were divided into 4 groups of 5 rats each, which included: Group 1 - Normal control; Group 2 - DF control; Group 3 - Low N-3 + DF; and, Group 4 - High N-3 + DF. The rats in group 2 were administered DF (10 mg/kg b.w./day, im) during the last 7 days of the experiment, while the rats in groups 3 and 4 were pre-treated with N-3 at 100 and 300 mg/kg b.w./day, po respectively for 21 days, afterwards, they received DF at 10 mg/kg b.w./day (im) for 7 days. The result showed that DF significantly increased malondialdehyde, lactate dehydrogenase, and pro-inflammatory markers (total white blood cell count, uric acid, platelet/lymphocyte and neutrophil/lymphocyte ratios). Moreover, DF significantly elevated the activities of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase, but, significant reduced the total antioxidant capacity and the activities of superoxide dismutase, catalase, and glutathione peroxidase. The histological results were parallel to the biochemical and haematological findings. Pre-treatment with N-3 significantly prevented the manifestation of the abnormalities brought about by DF. Although there were indications of the dose-dependent effects of N-3, the low dose was found to be more effective. In conclusion, the pre-administration of N-3, preferably at a low dose, could reduce hepatotoxicity that could result from subsequent exposure to DF.

Saturated fatty acids induce development of both metabolic syndrome and osteoarthritis in rats

The predominant saturated fatty acids (SFA) in human diets are lauric acid (LA, C12:0), myristic acid (MA, C14:0), palmitic acid (PA, C16:0) and stearic acid (SA, C18:0). The aim of this study was to investigate whether diets containing individual SFA together with excess simple carbohydrates induce osteoarthritis (OA)-like changes in knee joints and signs of metabolic syndrome in rats. Rats were given either a corn starch diet or a diet composed of simple carbohydrates together with 20% LA, MA, PA, SA or beef tallow for 16 weeks. Rats fed beef tallow, SA, MA or PA diets developed signs of metabolic syndrome, and also exhibited cartilage degradation and subchondral bone changes similar to OA. In contrast, replacement of beef tallow with LA decreased signs of metabolic syndrome together with decreased cartilage degradation. Furthermore, PA and SA but not LA increased release of matrix sulphated proteoglycans in cultures of bovine cartilage explants or human chondrocytes. In conclusion, we have shown that longer-chain dietary SFA in rats induce both metabolic syndrome and OA-like knee changes. Thus, diets containing SFA are strongly relevant to the development or prevention of both OA and metabolic syndrome.

Osteoarthritis and type 2 diabetes mellitus: What are the links?

Osteoarthritis (OA) is the most frequent joint disorder and one of the leading cause of disability. During a long time, it was considered as the consequence of aging and mechanical stress on cartilage. Recent advances in the knowledge of OA have highlighted that it is a whole joint disease with early modifications of synovium and subchondral bone but also that it is associated with obesity and metabolic syndrome through systemic mechanisms. In the past year, type 2 diabetes has been described in two meta-analyzes as an independent risk factor for OA. In vivo models of diabetes corroborated epidemiological studies. Indeed, diabetic rodents display a spontaneous and a more severe experimental OA than their non-diabetic counterparts, which can be partially prevented by diabetes treatment (insulin, pioglitazone). The negative impact of diabetes on joints could be explain by the induction of oxidative stress and pro-inflammatory cytokines but also by advanced age products accumulation in joint tissues exposed to chronic high glucose concentration. Insulin resistance might also impair joint tissue because of a local insulin resistance of diabetic synovial membrane but also by the systemic low grade inflammation state related to obesity and insulin resistant state.

Fish oil in knee osteoarthritis: a randomised clinical trial of low dose versus high dose

OBJECTIVES

To determine whether high-dose fish oil is superior to low-dose supplementation for symptomatic and structural outcomes in knee osteoarthritis (OA).

METHODS

A randomised, double-blind, multicentre trial enrolled 202 patients with knee OA and regular knee pain. They were randomised 1:1 to high-dose fish oil (4.5 g omega-3 fatty acids) 15 mL/day or (2) low-dose fish oil (blend of fish oil and sunola oil; ratio of 1:9, 0.45 g omega-3 fatty acids) 15 mL/day. The primary endpoints were Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain score at 3, 6, 12 and 24 months, and change in cartilage volume at 24 months. Secondary outcomes included WOMAC function, quality of life, analgesic and non-steroidal anti-inflammatory drug use and bone marrow lesion score.

RESULTS

Although there was improvement in both groups, the low-dose fish oil group had greater improvement in WOMAC pain and function scores at 2 years compared with the high-dose group, whereas between-group differences at 1 year did not reach statistical significance. There was no difference between the two groups in cartilage volume loss at 2 years. For other secondary endpoints, there was no difference between the two groups at 2 years.

CONCLUSIONS

In people with symptomatic knee OA, there was no additional benefit of a high-dose fish oil compared with low-dose fish oil. The combination comparator oil appeared to have better efficacy in reducing pain at 2 years, suggesting that this requires further investigation.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry (ACTRN 12607000415404).

Links between osteoarthritis and diabetes: implications for management from a physical activity perspective

Osteoarthritis (OA) and type 2 diabetes mellitus (T2DM) often coexist in older adults. Those with T2DM are more susceptible to developing arthritis, which has been traditionally attributed to common risk factors, namely, age and obesity. Alterations in lipid metabolism and hyperglycemia might directly impact cartilage health and subchondral bone, contributing to the development/progression of OA. Adequate management of older persons with both conditions benefits from a comprehensive understanding of the associated risk factors. We discuss common risk factors and emerging links between OA and T2DM, emphasizing the importance of physical activity and the implications of safe and effective physical activity.

Metabolic enrichment of omega-3 polyunsaturated fatty acids does not reduce the onset of idiopathic knee osteoarthritis in mice

OBJECTIVE

We evaluated the effect of a reduction in the systemic ratio of n-6:n-3 polyunsaturated fatty acids (PUFAs) on changes in inflammation, glucose metabolism, and the idiopathic development of knee osteoarthritis (OA) in mice. We hypothesized that a lower ratio of n-6:n-3 PUFAs would protect against OA markers in cartilage and synovium, but not bone.

DESIGN

Male and female fat-1 transgenic mice (Fat-1), which convert dietary n-6 to n-3 PUFAs endogenously, and their wild-type (WT) littermates were fed an n-6 PUFA enriched diet for 9-14 months. The effect of gender and genotype on serum PUFAs, interleukin (IL)-6, tumor necrosis factor (TNF)-α, and glucose tolerance was tested by 2-factor analysis of variance (ANOVA). Cortical and trabecular subchondral bone changes were documented by micro-focal computed tomography (CT), and knee OA was assessed by semi-quantitative histomorphometry grading.

RESULTS

The n-6:n-3 ratio was reduced 12-fold and 7-fold in male and female Fat-1 mice, respectively, compared to WT littermates. IL-6 and TNF-α levels were reduced modestly in Fat-1 mice. However, these systemic changes did not reduce osteophyte development, synovial hyperplasia, or cartilage degeneration. Also the fat-1 transgene did not alter subchondral cortical or trabecular bone morphology or bone mineral density.

CONCLUSIONS

Reducing the systemic n-6:n-3 ratio does not slow idiopathic changes in cartilage, synovium, or bone associated with early-stage knee OA in mice. The anti-inflammatory and anti-catabolic effects of n-3 PUFAs previously reported for cartilage may be more evident at later stages of disease or in post-traumatic and other inflammatory models of OA.

The potential for dietary factors to prevent or treat osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease for which there are no disease-modifying drugs. It is a leading cause of disability in the UK. Increasing age and obesity are both major risk factors for OA and the health and economic burden of this disease will increase in the future. Focusing on compounds from the habitual diet that may prevent the onset or slow the progression of OA is a strategy that has been under-investigated to date. An approach that relies on dietary modification is clearly attractive in terms of risk/benefit and more likely to be implementable at the population level. However, before undertaking a full clinical trial to examine potential efficacy, detailed molecular studies are required in order to optimise the design. This review focuses on potential dietary factors that may reduce the risk or progression of OA, including micronutrients, fatty acids, flavonoids and other phytochemicals. It therefore ignores data coming from classical inflammatory arthritides and nutraceuticals such as glucosamine and chondroitin. In conclusion, diet offers a route by which the health of the joint can be protected and OA incidence or progression decreased. In a chronic disease, with risk factors increasing in the population and with no pharmaceutical cure, an understanding of this will be crucial.

Lipid transport and metabolism in healthy and osteoarthritic cartilage

Cartilage is an avascular tissue and cartilage metabolism depends on molecule diffusion from synovial fluid and subchondral bone. Thus, nutrient availability is limited by matrix permeability according to the size and charge of the molecules. Matrix composition limits the access of molecules to chondrocytes, determining cell metabolism and cartilage maintenance. Lipids are important nutrients in chondrocyte metabolism and are available for these cells through de novo synthesis but also through diffusion from surrounding tissues. Cartilage status and osteoarthritis development depend on lipid availability. This paper reviews lipid transport and metabolism in cartilage. We also analyze signalling pathways directly mediated by lipids and those that involve mTOR pathways, both in normal and osteoarthritic cartilage.

Fibrates as therapy for osteoarthritis and rheumatoid arthritis? A systematic review

Fibrates are used as lipid-lowering drugs to prevent cardiovascular pathology. Fibrates are ligands of peroxisome proliferator-activated receptor α (PPARα). Besides altering lipid metabolism, PPARα ligands exert anti-inflammatory effects on various cell types. In this study, we hypothesized that PPARα agonists exert beneficial effects on osteoarthritis (OA) and rheumatoid arthritis (RA) by their local anti-inflammatory effects, but also by their systemic influences. A systematic literature search of Medline and EMBASE databases was performed up to August 2011. The main search items were osteoarthritis, rheumatoid arthritis, peroxisome proliferator-activated receptor alpha and fibrates. Inclusion criteria were in vivo or in vitro studies regarding humans or animals in which the effects of PPARα ligands were studied. Six in vivo human studies, four in vivo animal studies and seven in vitro studies were included. The in vivo human studies showed all beneficial clinical effects of PPARα ligands, but studies were small and only four were randomized. Ligands for PPARα significantly reduced pain, swelling of the joints and decreased systemic inflammatory markers. In vitro and in vivo animal studies indicate that PPARα agonists inhibit bone resorption, and reduce inflammatory and destructive responses in cartilage and synovium. PPARα agonists such as fibrates should be considered as potential therapeutic strategy for RA. There is no clinical evidence for their use in OA, although in vitro studies indicate that PPARα agonists demonstrate different joint-protective effects locally, and systemic effects on inflammation, serum lipid levels and vascular pathology. Animal studies should be performed and after confirmation of the protective effects of PPARα, large randomized controlled trials could investigate fibrates in OA and RA.

Intra-articular lentivirus-mediated insertion of the fat-1 gene ameliorates osteoarthritis

Osteoarthritis (OA) is a gradually progressive degenerative disease characterized by gradual inflammatory loss of articular cartilage caused by increased proteolytic catabolism, mediated by interleukin-1 (IL-1), tumor necrosis factor α (TNF-α), matrix metalloproteinase (MMPs), aggrecanases and other proteinases, and reduced anabolism of cartilage components, contributed by interleukin-4 (IL-4), interleukin-10 (IL-10), insulin-like growth factor 1 (IGF-1), transforming growth factor β (TGF-β), and bone morphogenetic proteins (BMPs). Substantial studies showed n-3 polyunsaturated fatty acids (n-3 PUFAs) exhibit a powerful anti-inflammatory effects in and ex vivo through reducing the production of IL-1 and TNF-α and increasing the expression of IL-4, IL-10, TGF-β and IGF-1 in OA. Meanwhile, more convincing results are observed in the fat-1 transgenic mice, which are exogenously inserted in a fat-1 gene from Caenorhabditis elegans, which can endogenously convert n-6 polyunsaturated fatty acids (n-6 PUFAs) to n-3 PUFAs. Taken together, it has long been realized that dietary supplementation with fish oils that are plentiful of n-3 PUFAs can bring benefits in the treatment of osteoarthritis. Previously two phase I human studies based on in vitro transfer of the cDNA via lentivirus to arthritic joints have confirmed its feasibility and safety in human subjects. Consequently, we hypothesis that directly infect the chondrocytes and synoviocytes with lentivirus carrying the fat-1 gene could be a well therapeutic strategy for OA in humans.

A longitudinal study of the association between dietary factors, serum lipids, and bone marrow lesions of the knee

Introduction

Bone marrow lesions (BMLs) play an important role in knee osteoarthritis, but their etiology is not well understood. The aim of this longitudinal study was to describe the association between dietary factors, serum lipids, and BMLs.

Methods

In total, 394 older men and women (mean age, 63 years; range, 52 to 79) were measured at baseline and approximately 2.7 years later. BMLs were determined by using T₂-weighted fat-saturation magnetic resonance imaging (MRI) by measuring the maximal area of the lesion. Nutrient intake (total energy, fat, carbohydrate, protein, and sugar) and serum lipids were assessed at baseline.

Results

Cross-sectionally, dietary factors and lipids were not significantly associated with BMLs. Energy, carbohydrate, and sugar intake (but not fat) were positively associated with a change in BML size (β = 15.44 to 19.27 mm² per 1 SD increase; all P < 0.05). High-density lipoprotein (HDL) cholesterol tended to be negatively associated with BML change (β = -11.66 mm² per 1 SD increase; P = 0.088).

Conclusions

Energy, carbohydrate, and sugar intake may be risk factors for BML development and progression. HDL cholesterol seems protective against BMLs. These results suggest that macronutrients and lipids may be important in BML etiology and that dietary modification may alter BML natural history.

Regulation of osteoarthritis by omega-3 (n-3) polyunsaturated fatty acids in a naturally occurring model of disease

OBJECTIVE

To examine effects of high omega-3 (n-3) polyunsaturated fatty acid (PUFA) diets on development of osteoarthritis (OA) in a spontaneous guinea pig model, and to further characterise pathogenesis in this model. Modern diets low in n-3 PUFAs have been linked with increases in inflammatory disorders, possibly including OA. However, n-3 is also thought to increases bone density, which is a possible contributing factor in OA. Therefore we aim to determine the net influence of n-3 in disease development.

METHOD

OA-prone Dunkin-Hartley (DH) Guinea pigs were compared with OA-resistant Bristol Strain-2s (BS2) each fed a standard or an n-3 diet from 10 to 30 weeks (10/group). We examined cartilage and subchondral bone pathology by histology, and biochemistry, including collagen cross-links, matrix metalloproteinases (MMPs), alkaline phosphatase, glycosaminoglycan (GAG), and denatured type II collagen.

RESULTS

Dietary n-3 reduced disease in OA-prone animals. Most cartilage parameters were modified by n-3 diet towards those seen in the non-pathological BS2 strain - significantly active MMP-2, lysyl-pyridinoline and total collagen cross-links - the only exception being pro MMP-9 which was lower in the BS2, yet increased with n-3. GAG content was higher and denatured type II lower in the n-3 group. Subchondral bone parameters in the DH n-3 group also changed towards those seen in the non-pathological strain, significantly calcium:phosphate ratios and epiphyseal bone density.

CONCLUSION

Dietary n-3 PUFA reduced OA in the prone strain, and most disease markers were modified towards those of the non-OA strain, though not all significantly so. Omega-3 did not increase markers of pathology in either strain.

Nutraceuticals: do they represent a new era in the management of osteoarthritis? - a narrative review from the lessons taken with five products

OBJECTIVES

The aim of this first global systematic review on selected nutraceuticals was to synthesize and evaluate scientific relevant data available in the literature. Evidences that can support health, physiological or functional benefit on osteoarthritis (OA) were gathered and the level of evidence relative to each of these ingredients was highlighted.

METHODOLOGY

Relevant scientific data (positive or not) regarding OA were searched for five groups of compounds (avocado/soybean unsaponifiables (ASU), n-3 polyunsaturated fatty acids, collagen hydrosylates (CHs), vitamin D, polyphenols) within preclinical (in vitro and in vivo), epidemiological, and clinical studies. The following criteria were evaluated to assess the methodology quality of each study: (1) study question; (2) study population; (3) primary endpoint; (4) study design (randomization, control, blinding, duration of follow up); (5) data analysis and interpretation. A scientific consensus was determined for all studied nutraceuticals to evaluate their efficacy in OA.

RESULTS

The studied compounds demonstrated different potencies in preclinical studies. Most of them have demonstrated anti-catabolic and anti-inflammatory effects by various inhibitory activities on different mediators. Vitamin D showed a pro-catabolic effect in vitro and the polyphenol, Genistein, had only anti-inflammatory potency. The evaluation of the clinical data showed that ASU was the only one of the studied ingredients to present a good evidence of efficacy, but the efficient formulation was considered as a drug in some countries. Pycnogenol showed moderate evidence of efficacy, and vitamin D and collagen hydrolysate demonstrated a suggestive evidence of efficacy, whereas curcumin, epigallocatechin-3-gallate (EGCG) and resveratrol had only preclinical evidence of efficacy due to the lack of clinical data. The literature gathered for n-3 PUFA, nobiletin and genistein was insufficient to conclude for their efficacy in OA.

CONCLUSION

Additional data are needed for most of the studied nutraceuticals. Studies of good quality are needed to draw solid conclusions regarding their efficacy but nutraceuticals could represent good alternates for OA management. Their use should be driven by any recommendations.

Osteoarthritis: another component of metabolic syndrome?

Osteoarthritis (OA) has become a major public health problem not only because of its increasing prevalence worldwide but also because of its frequent association with cardiovascular disease, the leading cause of death in industrialized countries. There is growing evidence that OA is not simply a disease related to aging or mechanical stress of joints but rather a "metabolic disorder" in which various interrelated lipid, metabolic, and humoral mediators contribute to the initiation and progression of the disease process. Indeed, OA has been linked not only to obesity but also to other cardiovascular risk factors, namely, diabetes, dyslipidemia, hypertension, and insulin resistance.

Development of bone marrow lesions is associated with adverse effects on knee cartilage while resolution is associated with improvement--a potential target for prevention of knee osteoarthritis: a longitudinal study

INTRODUCTION

To examine the relationship between development or resolution of bone marrow lesions (BMLs) and knee cartilage properties in a 2 year prospective study of asymptomatic middle-aged adults.

METHODS

271 adults recruited from the Melbourne Collaborative Cohort Study, underwent a magnetic resonance imaging scan (MRI) of their dominant knee at baseline and again approximately 2 years later. Cartilage volume, cartilage defects and BMLs were determined at both time points.

RESULTS

Among 234 subjects free of BMLs at baseline, 33 developed BMLs over 2 years. The incidence of BMLs was associated with progression of tibiofemoral cartilage defects (OR 2.63 (95% CI 0.93, 7.44), P = 0.07 for medial compartment; OR 3.13 (95% CI 1.01, 9.68), P = 0.048 for lateral compartment). Among 37 subjects with BMLs at baseline, 17 resolved. Resolution of BMLs was associated with reduced annual loss of medial tibial cartilage volume (regression coefficient -35.9 (95%CI -65, -6.82), P = 0.02) and a trend for reduced progression of medial tibiofemoral cartilage defects (OR 0.2 (95% CI 0.04, 1.09), P = 0.06).

CONCLUSIONS

In this cohort study of asymptomatic middle-aged adults the development of new BMLs was associated with progressive knee cartilage pathology while resolution of BMLs prevalent at baseline was associated with reduced progression of cartilage pathology. Further work examining the relationship between changes and BML and cartilage may provide another important target for the prevention of knee osteoarthritis.

Total cholesterol and triglycerides are associated with the development of new bone marrow lesions in asymptomatic middle-aged women - a prospective cohort study

Introduction

Given the emerging evidence that osteoarthritis (OA) may have a vascular basis, the aim of this study was to determine whether serum lipids were associated with change in knee cartilage, presence of bone marrow lesions (BMLs) at baseline and the development of new BMLs over a 2-year period in a population of pain-free women in mid-life.

Methods

One hundred forty-eight women 40 to 67 years old underwent magnetic resonance imaging (MRI) of their dominant knee at baseline and 2.2 (standard deviation 0.12) years later. Cartilage volume and BMLs were determined for both time points. Serum lipids were measured from a single-morning fasting blood test approximately 1.5 years prior to the MRI.

Results

The incidence of BML at follow-up was associated with higher levels of total cholesterol (odds ratio [OR] 1.84, 95% confidence interval [CI] 1.01, 3.36; P = 0.048) and triglycerides (OR 8.4, 95% CI 1.63, 43.43; P = 0.01), but not high-density lipoprotein (HDL) (P = 0.93), low-density lipoprotein (LDL) (P = 0.20) or total cholesterol/HDL ratio (P = 0.17). No association between total cholesterol, triglycerides, HDL, LDL or total cholesterol/HDL ratio and presence of BMLs at baseline or annual change in total tibial cartilage volume was observed.

Conclusions

In this study of asymptomatic middle-aged women with no clinical knee OA, serum cholesterol and triglyceride levels were associated with the incidence of BMLs over 2 years. This provides support for the hypothesis that vascular pathology may have a role in the pathogenesis of knee OA. Further work is warranted to clarify this and whether treatments aimed at reducing serum lipids may have a role in reducing the burden of knee OA.

Effect of glucosamine sulfate with or without omega-3 fatty acids in patients with osteoarthritis

INTRODUCTION

A total of 177 patients with moderate-to-severe hip or knee osteoarthritis (OA) were tested over a period of 26 weeks in a two-center, two-armed, randomized, double-blind, comparison study. The aim was to see if a combination of glucosamine sulfate (1500 mg/day) and the omega-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (group A), showed equivalence (noninferiority) or superiority as opposed to glucosamine sulfate alone (group B).

METHODS

The primary therapy evaluation was performed using the Western Ontario and McMaster Universities Arthrosis index (WOMAC) score. At the end of the study, a reduction in the pain score of > or =20% was required (primary target criterion) and the quantitative difference in the WOMAC subscores pain, stiffness, and function were analyzed (secondary target criteria).

RESULTS AND CONCLUSION

When a minimal pain reduction of > or =20% was chosen, there was no statistically significant difference in the number of responders between the two groups (92.2% group A, 94.3% group B). A higher responder criterion (> or =80% reduction in the WOMAC pain score) was chosen. Therefore, the frequency of responders showed a therapeutic and statistical superiority for the combination product of glucosamine sulfate and the omega-3 polyunsaturated fatty acids in patients who complied with the study protocol (group A 44%, group B 32%; P=0.044). OA symptoms (morning stiffness, pain in hips and knees) were reduced at the end of the study: by 48.5%-55.6% in group A and by 41.7%-55.3% in group B. The reduction was greater in group A than in group B. There was a tendency toward superiority shown in the secondary target criteria and concurrent variables. In the global safety evaluation, both products have been demonstrated to be very safe in long-term treatment over 26 weeks. To our knowledge, this is the first clinical trial in which glucosamine was given in combination with omega-3 fatty acids to patients with OA.

Reduced rates of primary joint replacement for osteoarthritis in Italian and Greek migrants to Australia: the Melbourne Collaborative Cohort Study

Introduction

Racial and ethnic disparities in rates of total joint replacement have been described, but little work has been done in well-established migrant groups. The aim of this study was to compare the rates of primary joint replacement for osteoarthritis for Italian and Greek migrants to Australia and Australian-born individuals.

Methods

Eligible participants (n = 39,023) aged 27 to 75 years, born in Italy, Greece, Australia and the United Kingdom, were recruited for the Melbourne Collaborative Cohort Study between 1990 and 1994. Primary hip and knee replacement for osteoarthritis between 2001 and 2005 was determined by data linkage to the Australian Orthopaedic Association National Joint Replacement Registry.

Results

Participants born in Italy and Greece had a lower rate of primary joint replacement compared with those born in Australia (hazard ratio [HR] 0.32, 95% confidence interval [CI] 0.26 to 0.39, P < 0.001), independent of age, gender, body mass index, education level, and physical functioning. This lower rate was observed for joint replacements performed in private hospitals (HR 0.17, 95% CI 0.13 to 0.23), but not for joint replacements performed in public hospitals (HR 0.96, 95% CI 0.72 to 1.29).

Conclusions

People born in Italy and Greece had a lower rate of primary joint replacement for osteoarthritis in this cohort study compared with Australian-born people, which could not simply be explained by factors such as education level, physical functioning, and weight. Although differential access to health care found in the population may explain the different rates of joint replacement, it may be that social factors and preferences regarding treatment or different rates of progression to end-stage osteoarthritis in this population are important to ethnic disparity.

Dietary fatty acid intake affects the risk of developing bone marrow lesions in healthy middle-aged adults without clinical knee osteoarthritis: a prospective cohort study

Introduction

Fatty acids have been implicated in osteoarthritis (OA), yet the mechanism by which fatty acids affect knee structure and consequently the risk of knee OA has not been fully elucidated. Higher intakes of fatty acids have been shown to be associated with the risk of bone marrow lesions (BMLs) in a healthy population. The aim of this study was to examine the association between fatty acid consumption and the incidence of BMLs in healthy middle-aged adults without clinical knee OA.

Methods

Two hundred ninety-seven middle-aged adults without clinical knee OA underwent magnetic resonance imaging (MRI) of their dominant knee at baseline. BMLs were assessed. Of the 251 participants with no BMLs in their knee at baseline, 230 underwent MRI of the same knee approximately 2 years later. Intakes of fatty acids were estimated from a food frequency questionnaire.

Results

Increased consumption of saturated fatty acids was associated with an increased incidence of BMLs over 2 years after adjusting for energy intake, age, gender, and body mass index (odds ratio of 2.56 for each standard deviation increase in dietary intake, 95% confidence interval 1.03 to 6.37, P = 0.04). Intake of monounsaturated or polyunsaturated fatty acids was not significantly associated with the incidence of BMLs.

Conclusions

Increased fatty acid consumption may increase the risk of developing BMLs. As subchondral bone is important in maintaining joint integrity and the development of OA, this study suggests that dietary modification of fatty acid intake may be one strategy in the prevention of knee OA which warrants further investigation.