Nutrition: risk factors for osteoarthritis

ASA VI controls osteoarthritis in mice by maintaining mitochondrial homeostasis through Sirtuin 3

OBJECTIVE

The aim of this study was to investigate whether ASA VI controls osteoarthritis (OA) by regulating mitochondrial function.

METHODS

Primary chondrocytes were isolated and cultured from rat knee joints. The chondrocytes were treated with ASA VI and interleukin-1β (IL-1β) to simulate the inflammatory environment of OA. Cell viability, apoptosis, inflammatory cytokine levels, and extracellular matrix (ECM) component levels were assessed. Mitochondrial function, including ATP levels, mitochondrial membrane potential, reactive oxygen species (ROS) levels, and mitochondrial DNA content, was evaluated. The expression of Sirtuin 3 (Sirt3), a key regulator of mitochondrial homeostasis, was examined. Additionally, a rat OA model was established by destabilizing the medial meniscus, and the effects of ASA VI on cartilage degeneration were assessed.

RESULTS

ASA VI treatment improved cell viability, reduced apoptosis, and decreased IL-6 and TNF-α levels in IL-1β-induced chondrocytes. ASA VI also upregulated Collagen II and Aggrecan expression, while downregulating ADAMTS5 and MMP-13 expression. Furthermore, ASA VI mitigated IL-1β-induced mitochondrial dysfunction by increasing ATP levels, restoring mitochondrial membrane potential, reducing ROS production, and preserving mitochondrial DNA content. These effects were accompanied by the activation of Sirt3. In the rat OA model, ASA VI treatment increased Sirt3 expression and alleviated cartilage degeneration.

CONCLUSION

ASA VI exerts chondroprotective and anti-inflammatory effects on IL-1β-induced chondrocytes by improving mitochondrial function through Sirt3 activation. ASA VI also attenuates cartilage degeneration in a rat OA model. These findings suggest that ASA VI may be a potential therapeutic agent for the treatment of osteoarthritis by targeting mitochondrial dysfunction.

Current therapies for osteoarthritis and prospects of CRISPR-based genome, epigenome, and RNA editing in osteoarthritis treatment

Osteoarthritis (OA) is one of the most common degenerative joint diseases worldwide, causing pain, disability, and decreased quality of life. The balance between regeneration and inflammation-induced degradation results in multiple etiologies and complex pathogenesis of OA. Currently, there is a lack of effective therapeutic strategies for OA treatment. With the development of CRISPR-based genome, epigenome, and RNA editing tools, OA treatment has been improved by targeting genetic risk factors, activating chondrogenic elements, and modulating inflammatory regulators. Supported by cell therapy and in vivo delivery vectors, genome, epigenome, and RNA editing tools may provide a promising approach for personalized OA therapy. This review summarizes CRISPR-based genome, epigenome, and RNA editing tools that can be applied to the treatment of OA and provides insights into the development of CRISPR-based therapeutics for OA treatment. Moreover, in-depth evaluations of the efficacy and safety of these tools in human OA treatment are needed.

Sports Participation and Osteoarthritis in Females: A Systematic Review

Sports participation and the risk of osteoarthritis (OA) have been a concern for decades. Few research efforts have been dedicated to clarify this issue for females, although they are considered at greater risk of developing OA than males. In contrast, several reviews have established an association between sports participation and OA for males. The aim of the systematic review was to assess the association between OA and participation in popular sports for females. PubMed, Embase, and Google Scholar were searched and yielded 578 articles. Nine eligible studies were included and covered ballet (age range: 19-54 years), running or tennis (age range: 40-65 years), Olympic sports (age range: not specified), volleyball (age range: 16.0 ± 0.8 to 46.8 ± 5.1 years), and cross-country skiing (age range: 15 to ≥60 years). For females, participating in sports at an elite level was associated with a higher risk of OA and an increased need for surgical treatment. At non-elite level, it was associated with a higher risk of OA, but it did not materialize to an increased risk for surgical treatment. Few studies compared females and males, and these studies suggested that sex did not affect the risk of developing OA from participating in sports. Nevertheless, to isolate the precise effect of sports participation on the development of OA remains difficult as injuries are common among athletes and are independently associated with an increased risk of OA.

α-Chaconine Facilitates Chondrocyte Pyroptosis and Nerve Ingrowth to Aggravate Osteoarthritis Progression by Activating NF-κB Signaling

BACKGROUND

With the rapid growth of the elderly population, the incidence of osteoarthritis (OA) increases annually, which has attracted extensive attention in public health. The roles of dietary intake in controlling joint disorders are perhaps one of the most frequently posed questions by OA patients, while the information about the interaction between dietary intake and OA based on scientific research is limited. α-Chaconine is the richest glycoalkaloid in eggplants such as potatoes. Previous evidence suggests that α-Chaconine is a toxic compound to nervous and digestive systems with potentially severe and fatal consequences for humans and farm animals, but its effect on OA development remains obscure.

OBJECTIVE

To determine whether α-Chaconine deteriorates OA progression through sensory innervation and chondrocyte pyroptosis via regulating nuclear factor-κB (NF-κB) signaling, providing evidence for a possible linkage between α-Chaconine and OA progression.

METHODS

We established a mouse OA model by destabilization of medial meniscus (DMM) surgery and then intra-articular injection of 20 or 100 μM α-Chaconine into the OA mice for 8 and 12 weeks. The severity of OA progression was evaluated by histological staining and radiographic analyses. The expressions of matrix metabolic indicators, Col2, Mmp3, and Mmp13, as well as pyroptosis-related proteins, Nlrp3, Caspase-1, Gsdmd, IL-1β, IL-18, were determined by immunohistochemistry. And the changes in sensory nerve ingrowth and activity of NF-κB signaling were determined by immunofluorescence.

RESULTS

We found that α-Chaconine could exacerbate mouse OA progression, resulting in subchondral sclerosis, osteophyte formation, and higher OARSI scores. Specifically, α-Chaconine could augment cartilage matrix degradation and induce chondrocyte pyroptosis and nerve ingrowth. Mechanistical analysis revealed that α-Chaconine stimulated NF-κB signaling by promoting I-κB α phosphorylation and p65 nuclear translocation.

CONCLUSION

Collectively, our findings raise the possibility that α-Chaconine intake can boost chondrocyte pyroptosis and nerve ingrowth to potentiate OA progression by activating NF-κB signaling.

Safranal Treatment Induces Sirt1 Expression and Inhibits Endoplasmic Reticulum Stress in Mouse Chondrocytes and Alleviates Osteoarthritis Progression in a Mouse Model

Osteoarthritis (OA) is an age-related degenerative disease. Oxidative stress (OS) modulates OA pathogenesis by enhancing chondrocyte apoptosis and extracellular matrix (ECM) degeneration via activation of the endoplasmic reticulum (ER) stress. Prior studies revealed that safranal plays a critical role in multiple diseases treatments, but there are no reports on its effect on OA. Therefore, investigating the effect of safranal on OA is needed. As a compound that can lead excessive reactive oxygen species (ROS) accumulation, tert-butyl hydroperoxide (TBHP) was used to induce OS and OS-mediated endoplasmic reticulum (ER) stress for imitating OA in vitro. Besides, the bilateral medial meniscus was removed to induce joint instability and excessive friction of the joint surface to establish destabilization of medial meniscus for imitating the initiation and progression of OA in vivo. We, next, conducted Western blot and RT-PCR analyses to identify biomarkers of the underlying signaling pathway. Our results demonstrated that 30 μM safranal strongly upregulated Sirt1 expression, suppressed TBHP-mediated ER stress, and, in turn, prevented chondrocyte apoptosis and ECM degeneration. Furthermore, compared with the other two classic signaling pathways of ER stress, safranal can inhibit the PERK-eIF2α-CHOP axis at the lower concentration (5 and 15 μM). In vivo, using Safranin O staining, X-ray, immunofluorescence (IF), and immunohistochemical (IHC) staining, we demonstrated that OA progression can be postponed with intraperitoneal injection of 90 and 180 mg/kg safranal in an OA mouse model. Taken together, our analyses revealed that safranal can potentially prevent OA development.

Mind the Gap: Exploring Nutritional Health Compared With Weight Management Interests of Individuals with Osteoarthritis

Background

For persons with osteoarthritis (OA), nutrition education may facilitate weight and OA symptom management.

Objectives

The primary aim of this study was to determine preferred OA-related nutritional and weight management topics and their preferred delivery modality. The secondary aim was to determine whether there is a disconnect between what patients want to know about nutrition and OA management and what information health-care professionals (HCPs) are providing to patients.

Methods

The Osteoarthritis Action Alliance surveyed individuals with OA to identify their preferences, categorized in 4 domains: 1) strategies for weight management and a healthy lifestyle; 2) vitamins, minerals, and other supplements; 3) foods or nutrients that may reduce inflammation; and 4) diets for weight loss. HCPs were provided these domains and asked which topics they discussed with patients with OA. Both groups were asked to select currently utilized or preferred formats of nutritional resources.

Results

Survey responses from 338 individuals with OA and 104 HCPs were included. The highest preference rankings in each domain were: 1) foods that make OA symptoms worse (65%), foods and nutrients to reduce inflammation (57%), and healthy weight loss (42%); 2) glucosamine (53%), vitamin D (49%), and omega-3 fatty acids (45%); 3) spices and herbs (65%), fruits and vegetables (58%), and nuts (40%); and 4) Mediterranean diet (21%), low-carbohydrate diet (18%), and fasting or intermittent fasting (15%). There was greater than 20% discrepancy between interests reported by individuals with OA and discussions reported by HCPs on: weight loss strategies, general information on vitamins and minerals, special dietary considerations for other conditions, mindful eating, controlling caloric intake or portion sizes, and what foods worsen OA symptoms. Most respondents preferred to receive nutrition information in a passive format and did not want information from social media messaging.

Conclusions

There is disparity between the nutrition education content preferred by individuals with OA (which often lacks empirical support) and evidence-based topics being discussed by HCPs. HCPs must communicate evidence-based management of joint health and OA symptoms in patient-preferred formats. This study explored the information gap between what individuals with OA want to know and what HCPs believe they need to know.

Low-Grade Inflammation in the Pathogenesis of Osteoarthritis: Cellular and Molecular Mechanisms and Strategies for Future Therapeutic Intervention

Osteoarthritis (OA) is a musculoskeletal disease characterized by cartilage degeneration and stiffness, with chronic pain in the affected joint. It has been proposed that OA progression is associated with the development of low-grade inflammation (LGI) in the joint. In support of this principle, LGI is now recognized as the major contributor to the pathogenesis of obesity, aging, and metabolic syndromes, which have been documented as among the most significant risk factors for developing OA. These discoveries have led to a new definition of the disease, and OA has recently been recognized as a low-grade inflammatory disease of the joint. Damage-associated molecular patterns (DAMPs)/alarmin molecules, the major cellular components that facilitate the interplay between cells in the cartilage and synovium, activate various molecular pathways involved in the initiation and maintenance of LGI in the joint, which, in turn, drives OA progression. A better understanding of the pathological mechanisms initiated by LGI in the joint represents a decisive step toward discovering therapeutic strategies for the treatment of OA. Recent findings and discoveries regarding the involvement of LGI mediated by DAMPs in OA pathogenesis are discussed. Modulating communication between cells in the joint to decrease inflammation represents an attractive approach for the treatment of OA.

Echinacoside Upregulates Sirt1 to Suppress Endoplasmic Reticulum Stress and Inhibit Extracellular Matrix Degradation In Vitro and Ameliorates Osteoarthritis In Vivo

Background

Osteoarthritis (OA) is a progressive illness that destroys cartilage. Oxidative stress is a major contributor of OA, while endoplasmic reticulum (ER) stress is the key cellular damage under oxidative stress in chondrocytes. Echinacoside (ECH) is the main extract and active substance of Cistanche, with potent antioxidative stress (OS) properties, and currently under clinical trials in China. However, its function in OA is yet to be determined.

Purpose

We aimed to explore the specific role of ECH in the occurrence and development of OA and its underlying mechanism in vivo and in vitro.

Methods

After the mice were anesthetized, the bilateral medial knee joint meniscus resection was performed to establish the DMM model. TBHP was used to induce oxidative stress to establish the OA model in chondrocytes in vitro. Western blot and RT-PCR were used to evaluate the level of ER stress-related biomarkers such as p-PERK/PERK, GRP78, ATF4, p-eIF2α/eIF2α, and CHOP and apoptosis-related proteins such as BAX, Bcl-2, and cleaved caspase-3. Meanwhile, we used SO staining, immunofluorescence, and immunohistochemical staining to evaluate the pharmacological effects of ECH in mice in vivo.

Results

We demonstrated the effectiveness of ECH in suppressing ER stress and restoring ECM metabolism in vitro. In particular, ECH was shown to suppress tert-Butyl hydroperoxide- (TBHP-) induced OS and subsequently lower the levels of p-PERK/PERK, GRP78, ATF4, p-eIF2α/eIF2α, and CHOP in vitro. Simultaneously, ECH reduced MMP13 and ADAMTS5 levels and promoted Aggrecan and Collagen II levels, suggesting ECM degradation suppression. Moreover, we showed that ECH mediates its cellular effects via upregulation of Sirt1. Lastly, we confirmed that ECH can protect against OA in mouse OA models.

Conclusion

In summary, our findings indicate that ECH can inhibit ER stress and ECM degradation by upregulating Sirt1 in mouse chondrocytes treated with TBHP. It can also prevent OA development in vivo.

Cell cycle-related lncRNAs and mRNAs in osteoarthritis chondrocytes in a Northwest Chinese Han Population

BACKGROUND

A group of differentially expressed long non-coding RNAs (lncRNAs) have been shown to play key roles in osteoarthritis (OA), although they represented only a small proportion of lncRNAs that may be biologically and physiologically relevant. Since our knowledge of regulatory functions of non-coding RNAs is still limited, it is important to gain better understanding of their relation to the pathogenesis of OA.

METHODS

We performed mRNA and lncRNA microarray analysis to detect differentially expressed RNAs in chondrocytes from three OA patients compared with four healthy controls. Then, enrichment analysis of the differentially expressed mRNAs was carried out to define disease molecular networks, pathways and gene ontology (GO) function. Furthermore, target gene prediction based on the co-expression network was performed to reveal the potential relationships between lncRNAs and mRNAs, contributing an exploration of a role of lncRNAs in OA mechanism. Quantitative RT-PCR analyses were used to demonstrate the reliability of the experimental results.

FINDINGS

Altogether 990 lncRNAs (666 up-regulated and 324 down-regulated) and 546 mRNAs (419 up-regulated and 127 down-regulated) were differentially expressed in OA samples compared with the normal ones. The enrichment analysis revealed a set of genes involved in cell cycle. In total, 854 pairs of mRNA and lncRNA were highly linked, and further target prediction appointed 12 genes specifically for their corresponding lncRNAs. The lncRNAs lncRNA-CTD-2184D3.4, ENST00000564198.1, and ENST00000520562.1 were predicted to regulate SPC24, GALM, and ZNF345 mRNA expressions in OA.

INTERPRETATION

This study uncovered several novel genes potentially important in pathogenesis of OA, and forecast the potential function of lnc-CTD-2184D3.4, especially for the cell cycle in the chondrocytes. These findings may promote additional aspects in studies of OA.

Consumption of dairy products in relation to the presence of clinical knee osteoarthritis: The Maastricht Study

PURPOSE

Observational studies showed inverse associations between milk consumption and knee osteoarthritis (knee OA). There is lack of information on the role of specific dairy product categories. We explored the association between dairy consumption and the presence of knee osteoarthritis in 3010 individuals aged 40-75 years participating in The Maastricht Study.

METHODS

The presence of knee OA was defined according to a slightly modified version of the American College of Rheumatology (ACR) clinical classification criteria. Data on dairy consumption were appraised by a 253-item FFQ covering 47 dairy products with categorization on fat content, fermentation or dairy type. Multivariable logistic regression analyses were performed to estimate odd ratios (ORs) and 95% confidence intervals (95%CI), while correcting for relevant factors.

RESULTS

427 (14%) participants were classified as having knee OA. Significant inverse associations were observed between the presence of knee OA and intake of full-fat dairy and Dutch, primarily semi-hard, cheese, with OR for the highest compared to the lowest tertile of intake of 0.68 (95%CI 0.50-0.92) for full-fat dairy, and 0.75 (95%CI 0.56-0.99) for Dutch cheese. No significant associations were found for other dairy product categories.

CONCLUSION

In this Dutch population, higher intake of full-fat dairy and Dutch cheese, but not milk, was cross-sectionally associated with the lower presence of knee OA. Prospective studies need to assess the relationship between dairy consumption, and in particular semi-hard cheeses, with incident knee OA.

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.

Modifiable lifestyle factors are associated with lower pain levels in adults with knee osteoarthritis

Pain is the most important osteoarthritis (OA) symptom; however, it is poorly understood and markers of disease severity cannot explain pain variability. With no cure for OA, the authors recognized the need to identify modifiable factors to decrease pain and increase physical function. This study examined factors that characterize OA patients experiencing different levels of pain and investigated the relationships among these factors and OA pain.

BACKGROUND:

With no cure or effective treatments for osteoarthritis (OA), the need to identify modifiable factors to decrease pain and increase physical function is well recognized.

OBJECTIVE:

To examine factors that characterize OA patients at different levels of pain, and to investigate the relationships among these factors and pain.

METHODS:

Details of OA characteristics and lifestyle factors were collected from interviews with healthy adults with knee OA (n=197). The Western Ontario and McMaster Universities Osteoarthritis Index was used to assess pain. Factors were summarized across three pain score categories, and χ² and Kruskal-Wallis tests were used to examine differences. Multiple linear regression analysis using a stepwise selection procedure was used to examine associations between lifestyle factors and pain.

RESULTS:

Multiple linear regression analysis indicated that pain was significantly higher with the use of OA medications and higher body mass index category, and significantly lower with the use of supplements and meeting physical activity guidelines (≥150 min/week). Stiffness and physical function scores, bilateral knee OA, body mass index category and OA medication use were significantly higher with increasing pain, whereas self-reported health, servings of fruit, supplement use and meeting physical activity guidelines significantly lower. No significant differences across pain categories were found for sex, age, number of diseases, duration of OA, ever smoked, alcoholic drinks/week, over-the-counter pain medication use, OA supplement use, physical therapy use, servings of vegetables or minutes walked/week.

CONCLUSIONS:

Healthy weight maintenance, exercise for at least 150 min/week and appropriate use of medications and supplements represent important modifiable factors related to lower knee OA pain.

Beer and wine consumption and risk of knee or hip osteoarthritis: a case control study

Introduction

The aim of this study was to investigate the association between alcoholic and non-alcoholic beverages and knee or hip osteoarthritis (OA).

Methods

We conducted a case–control study of Caucasian men and women aged 45 to 86 years of age from Nottingham, UK. Cases had clinically severe symptoms and radiographic knee or hip OA; controls had no symptoms and no radiographic knee or hip OA. Exposure information was sought using interview-based questionnaires and a semi-quantitative food frequency questionnaire to assess beverage consumption at ages 21 to 50 years. Odds ratios (ORs), adjusted ORs (aORs), 95% confidence intervals (CI) and P values were estimated using logistic regression models.

Results

A total of 1,001 knee OA, 993 hip OA and 933 control participants were included in the study. Increasing beer consumption was associated with an increasing risk of OA (P for trend ≤0.001). Compared to those who did not consume beer, aORs for people who consumed 20 or more servings of beer were 1.93 (95% CI 1.26 to 2.94) and 2.15 (95% CI 1.45 to 3.19) for knee OA and hip OA, respectively. In contrast, increasing levels of wine consumption were associated with decreased likelihood of knee OA (P for trend <0.001). Compared to those who did not consume wine, aOR for knee OA among those who consumed 4 to 6 glasses of wine per week and ≥7 glasses of wine per week was 0.55 (95% CI 0.34 to 0.87) and 0.48 (95% CI 0.29 to 0.80), respectively. No association was identified between non-alcoholic beverages and knee or hip OA.

Conclusions

Beer consumption appears to be a risk factor for knee and hip OA whereas consumption of wine has a negative association with knee OA. The mechanism behind these findings is speculative but warrants further study.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0534-4) contains supplementary material, which is available to authorized users.

Vitamin D deficiency is associated with progression of knee osteoarthritis

BACKGROUND

Knee osteoarthritis causes functional limitation and disability in the elderly. Vitamin D has biological functions on multiple knee joint structures and can play important roles in the progression of knee osteoarthritis. The metabolism of vitamin D is regulated by parathyroid hormone (PTH).

OBJECTIVE

The objective was to investigate whether serum concentrations of 25-hydroxyvitamin D [25(OH)D] and PTH, individually and jointly, predict the progression of knee osteoarthritis.

METHODS

Serum 25(OH)D and PTH were measured at the 30- or 36-mo visit in 418 participants enrolled in the Osteoarthritis Initiative (OAI) who had ≥1 knee with both symptomatic and radiographic osteoarthritis. Progression of knee osteoarthritis was defined as any increase in the radiographic joint space narrowing (JSN) score between the 24- and 48-mo OAI visits.

RESULTS

The mean concentrations of serum 25(OH)D and PTH were 26.2 μg/L and 54.5 pg/mL, respectively. Approximately 16% of the population had serum 25(OH)D < 15 μg/L. Between the baseline and follow-up visits, 14% progressed in JSN score. Participants with low vitamin D [25(OH)D < 15 μg/L] had >2-fold elevated risk of knee osteoarthritis progression compared with those with greater vitamin D concentrations (≥15 μg/L; OR: 2.3; 95% CI: 1.1, 4.5). High serum PTH (≥73 pg/mL) was not associated with a significant increase in JSN score. However, participants with both low vitamin D and high PTH had >3-fold increased risk of progression (OR: 3.2; 95%CI: 1.2, 8.4).

CONCLUSION

Our results suggest that individuals deficient in vitamin D have an increased risk of knee osteoarthritis progression.

Milk consumption and progression of medial tibiofemoral knee osteoarthritis: data from the Osteoarthritis Initiative

OBJECTIVE

Milk consumption has long been recognized for its important role in bone health, but its role in the progression of knee osteoarthritis (OA) is unclear. We examined the prospective association of milk consumption with radiographic progression of knee OA.

METHODS

In the Osteoarthritis Initiative, 2,148 participants (3,064 knees) with radiographic knee OA and dietary data at baseline were followed up to 12, 24, 36, and 48 months. Milk consumption was assessed with a Block Brief Food Frequency Questionnaire completed at baseline. To evaluate progression of OA, we used quantitative joint space width (JSW) between the medial femur and tibia of the knee based on plain radiographs. The multivariate linear models for repeated measures were used to test the independent association between milk intake and the decrease in JSW over time, while adjusting for baseline disease severity, body mass index, dietary factors, and other potential confounders.

RESULTS

We observed a significant dose-response relationship between baseline milk intake and adjusted mean decrease of JSW in women (P = 0.014 for trend). With increasing levels of milk intake (none, ≤3, 4-6, and ≥7 glasses/week), the mean decreases of JSW were 0.38 mm, 0.29 mm, 0.29 mm, and 0.26 mm, respectively. In men, we observed no significant association between milk consumption and the decreases of JSW.

CONCLUSION

Our results suggest that frequent milk consumption may be associated with reduced OA progression in women. Replication of these novel findings in other prospective studies demonstrating the increase in milk consumption leads to delay in knee OA progression are needed.

Epidemiology of osteoarthritis

Osteoarthritis (OA) is the most common form of arthritis in the United States and is a leading cause of disability. It is typically defined in epidemiologic studies by radiographic findings and consideration of symptoms. Its incidence and prevalence are rising, likely related to the aging of the population and increasing obesity. Risk factors for OA include numerous person-level factors, such as age, sex, obesity, and genetics, as well as joint-specific factors that are likely reflective of abnormal loading of the joints. In studying OA, several methodologic challenges exist that can hamper our ability to identify pertinent relationships.

Association of suboptimal 25-hydroxyvitamin D levels with knee osteoarthritis incidence in post-menopausal Egyptian women

The main aim of this study was to assess the vitamin D status of newly diagnosed knee osteoarthritis (OA) patients. Thirty-six post-menopausal Egyptian females of mean age 54.7 years with knee OA were recruited alongside ten healthy males of mean age 25.8 years. The body mass index of all knee OA patients was calculated, and full patient history was gathered to screen for vitamin D status altering conditions or medication. Total 25-hydroxyvitamin D [25(OH)D] was assessed using HPLC which permitted an individualized assessment of both forms of the vitamin's metabolite, 25(OH)D2 and 25(OH)D3. Results showed that mean 25(OH)D ± SEM concentrations were 25.0 ± 1.6 ng/mL and 35.4 ± 2.1 ng/mL for female patients and healthy male participants, respectively. Student's t test statistical comparison yielded a significant result (P = 0.001) when comparing healthy and osteoarthritic participants, and insignificant results when comparing patients of different BMI class, and the different forms of the vitamin's metabolite (P = 0.184 and 0.335, respectively). The 95 % confidence interval associated with knee OA incidence is 21.9-28.1 ng/mL, which is in the vitamin D insufficiency zone. In Conclusion, suboptimal 25(OH)D levels are associated with knee OA incidence in post-menopausal Egyptian females which further fortifies accumulating evidence.

High dietary fat and the development of osteoarthritis in a rabbit model

OBJECTIVE

Osteoarthritis (OA) is associated with obesity, although this relationship remains unclear. Proposed etiologies of OA in obesity include mechanical loading of malaligned joints and possible toxicity of dietary fat. The hypothesis tested in the present study was that increased dietary fat worsens OA in both malaligned and normal joints, detected by biochemical and histological cartilage markers.

METHOD

83 New Zealand white rabbits were divided among two conditions related to OA: bowing of the knee and a 14%kcal vs 47.8%kcal fat diet. Rabbit weights and knee angles were compared throughout the experiment. At 28 and 38 weeks, intra-articular forces were measured, animals sacrificed, and knee cartilage examined for histological changes, glycosaminoglycan content, 35S uptake, and aggrecanase-1 expression.

RESULTS

There were no differences in animal weights or intra-articular forces between the two diets. Despite increased fat content in their diet, animals on the 47.8%kcal fat diet did not gain excess weight. Representative histology showed atypical shearing of articular cartilage among animals on the high fat diet. Animals on the 47.8%kcal fat diet had suppression of protein synthesis compared to the 14%kcal fat diet: lower glycosaminoglycan content and aggrecanase-1 expression in all knee compartments at both times, and lower 35S uptake at 38 weeks.

CONCLUSION

These results suggest dietary fat, independent of animal weight, results in altered chondrocyte function. Increased dietary fat was associated with changes in rabbit cartilage in vivo and appears to be a risk factor for the development of OA.

Osteoarthritis prevention

PURPOSE OF REVIEW

We discuss recent published epidemiologic data regarding risk factors for incident and progressive knee osteoarthritis and related knee pain to identify targets for primary and secondary prevention. We also discuss recently identified methodologic challenges to the study of knee osteoarthritis, particularly osteoarthritis progression.

RECENT FINDINGS

Recent epidemiologic studies and systematic reviews of knee osteoarthritis have confirmed that being overweight and obese, and knee injuries increase the risk for incident knee osteoarthritis. Biomechanical risk factors such as leg-length inequalities and malalignment require further study. Obesity also appears to play a role in accelerating osteoarthritis worsening. However, with the exception of malalignment, no risk factors for knee osteoarthritis progression have been identified. Novel approaches to the study of knee pain have demonstrated a strong association between structural abnormalities and knee pain, contrary to the 'so-called' structure-symptom discordance, as well as between fluctuations of knee pain with changes in specific structural lesions. A number of methodologic issues, including conditioning on an intermediate stage of disease and depletion of susceptibles may explain, in part, the difficulty in identifying risk factors for knee osteoarthritis.

SUMMARY

There is strong epidemiologic evidence that being overweight or obese and knee injury are associated with increased risk of developing knee osteoarthritis. Further study is required to confirm associations of leg-length inequality and malalignment with incident knee osteoarthritis. Few new risk factors for progression of knee osteoarthritis have been identified in the past few years. Without such knowledge, secondary prevention of osteoarthritis remains challenging.

The effects of vitamin C supplementation on incident and progressive knee osteoarthritis: a longitudinal study

OBJECTIVE

To evaluate the association between vitamin C supplementation and the incidence and progression of radiographic knee osteoarthritis (OA).

DESIGN

Prospective cohort study.

SETTING

Clearwater Osteoarthritis Study (COS): (1988 to the present) a longitudinal study.

SUBJECTS

Male and female COS participants aged 40 years and above (n 1023). The study exposure was the participants' self-reported history of vitamin C supplementation. The participants underwent biennial, sequential knee radiographs, which were assessed using the Kellgren-Lawrence ordinal scale to determine evidence of the study 2 outcomes: incident radiographic knee OA (RKOA) and progression of RKOA.

RESULTS

Individuals without baseline knee OA who self-reported vitamin C supplement usage were 11% less likely to develop knee OA than were those individuals who self-reported no vitamin C supplement usage (risk ratio (RR)=0.89, 95% CI 0.85, 0.93). Among those participants with RKOA at baseline, vitamin C supplement usage did not demonstrate an association with RKOA progression (RR=0.94, 95% CI 0.79, 1.22).

CONCLUSIONS

In the present prospective cohort study, we found no evidence to support a protective role of vitamin C in the progression of knee OA. However, after controlling for confounding variables, these data suggest that vitamin C supplementation may indeed be beneficial in preventing incident knee OA. Given the massive public health burden of OA, the use of a simple, widely available and inexpensive supplement to potentially reduce the impact of this disease merits further consideration.

Integrative medicine approach to chronic pain

Chronic pain can be a frustrating condition for patient and clinician. The integrative medicine approach to pain can offer hope, adding safe complementary and alternative medical (CAM) therapies to mitigate pain and suffering. Such CAM therapies include nutrition, supplements and herbs, manual medicine, acupuncture, yoga, and mind-body approaches. The evidence is heterogeneous regarding these approaches, but some evidence suggests efficacy and confirms safety. The integrative medicine approach can be beneficial in a patient with chronic pain.

The role of analgesics and intra-articular injections in disease management

The most important goals of therapy in patients with osteoarthritis are pain management, improvement in function and disability, and, ultimately, disease modification. This review discusses the current pharmacologic regimen available to address these goals. Specific attention is paid to current trends and controversies related to pharmacologic management, including the use of oral, topical, and injectable agents.

Osteoarthritis and nutrition. From nutraceuticals to functional foods: a systematic review of the scientific evidence

The scientific and medical community remains skeptical regarding the efficacy of nutrition for osteoarthritis despite their broad acceptation by patients. In this context, this paper systematically reviews human clinical trials evaluating the effects of nutritional compounds on osteoarthritis. We searched the Medline, Embase, and Biosis databases from their inception to September 2005 using the terms random, double-blind method, trial, study, placebo, and osteoarthritis. We selected all peer-reviewed articles reporting the results of randomised human clinical trials (RCTs) in osteoarthritis that investigated the effects of oral interventions based on natural molecules. Studies on glucosamine and chondroitin sulfate were excluded. The quality of the RCTs was assessed with an osteoarthritic-specific standardised set of 12 criteria and a validated instrument. A best-evidence synthesis was used to categorise the scientific evidence behind each nutritional compound as good, moderate, or limited. A summary of the most relevant in vitro and animal studies is used to shed light on the potential mechanisms of action. Inclusion criteria were met by 53 RCTs out of the 2,026 identified studies. Good evidence was found for avocado soybean unsaponifiables. Moderate evidence was found for methylsulfonylmethane and SKI306X, a cocktail of plant extracts. Limited evidence was found for the Chinese plant extract duhuo jisheng Wan, cetyl myristoleate, lipids from green-lipped mussels, and plant extracts from Harpagophytum procumbens. Overall, scientific evidence exists for some specific nutritional interventions to provide symptom relief to osteoarthritic patients. It remains to be investigated whether nutritional compounds can have structure-modifying effects.

Transforming growth factor Beta1 induction of tissue inhibitor of metalloproteinases 3 in articular chondrocytes is mediated by reactive oxygen species

Transforming growth factor beta1 (TGF-beta1) stimulates cartilage extracellular matrix synthesis but, in excess, evokes synovial inflammation, hyperplasia, and osteophyte formation in arthritic joints. TGF-beta1 induces tissue inhibitor of metalloproteinases 3 (TIMP-3), an inhibitor of cartilage-damaging matrix metalloproteianases and aggrecanases. We investigated the role of reactive oxygen species (ROS) in TIMP-3 induction by TGF-beta1. In primary human and bovine chondrocytes, ROS scavenger and antioxidant N-acetylcysteine (NAC) inhibited TGF-beta1-induced TIMP-3 mRNA and protein increases. Ebselen and ascorbate also reduced this induction. TGF-beta1 time-dependently induced ROS production that was suppressed by NAC. Hydrogen peroxide, a ROS, induced TIMP-3 RNA. The TIMP-3 increase induced by TGF-beta1 was partly Smad2-dependent. TGF-beta1-stimulated Smad2 phosphorylation was inhibited by NAC. Reduced glutathione and L-cysteine also blocked Smad2 and TIMP-3 induction by TGF-beta1, whereas a nonthiol, N-acetylalanine, did not. Smad2 was not activated by H2O2. Smad2 phosphorylation was independent, and TIMP-3 expression was dependent, on new protein synthesis. TGF-beta-stimulated ERK and JNK phosphorylation was also inhibited by NAC. However, inhibitory actions of NAC were not mediated by ERK activation. Thus, ROS mediate TGF-beta1-induced TIMP-3 gene expression. Blocking TGF-beta1-induced gene expression by modulating cellular redox status with thiols can be potentially beneficial for treating arthritic and other disorders caused by excessive TGF-beta1.

Can we identify a 'high risk' patient profile to determine who will experience rapid progression of osteoarthritis?

Disease modifying drugs for osteoarthritis (OA) that may halt or retard joint destruction and at the same time possibly improve symptoms are being developed and tested at various stages in clinical trials. This has, for at least two reasons, focused attention on the need for identification of patient groups at high risk for incident or progressive OA. First, well characterized such groups may be useful in clinical trials. Second, assuming that disease modifying OA drugs become available in the future, primary target groups in need of such therapy have to be identified. Risk factors for incident OA may differ from those for OA progression. Interactions between risk factors for OA is little understood. Factors that have consistently been reported as associated with radiographic OA progression are obesity, generalized OA, alignment and synovitis. Other factors such as bone scintigraphic lesions, joint injury nad biomarkers (such as type II collagen fragments, COMP and HA) show promise. Further evaluation of these variables and their individual and combined influence will be useful to design a risk profile for OA incidence and progression.

Advanced glycation endproducts and osteoarthritis

Non-enzymatic glycation of proteins, such as collagen, results in the formation of advanced glycation endproducts (AGE). Advanced glycation endproducts result in pathologic stiffening of cartilage and extracellular matrix and accumulate with age. Pentosidine, an AGE, is present in serum, synovial fluid, and articular cartilage from patients with osteoarthritis (OA). However, AGE levels are not always increased, and may be decreased locally, in association with osteoarthritic pathology. The finding of pentosidine in articular cartilage of individuals with OA may not be specific for that disease, independent of chronologic age. Advanced glycation endproduct modification of normal articular cartilage increases its stiffness, increases chondrocyte-mediated proteoglycan degradation, reduces its susceptibility to matrix metalloproteinase-mediated degradation, and decreases proteoglycan synthesis by chondrocytes. These observations parallel findings in osteoarthritic cartilage, which suggests that AGE modification could contribute to the pathogenesis of OA. However, a causative link between AGEs and OA has not yet been established.

Crosslinking by advanced glycation end products increases the stiffness of the collagen network in human articular cartilage: a possible mechanism through which age is a risk factor for osteoarthritis

OBJECTIVE

Age is an important risk factor for osteoarthritis (OA). During aging, nonenzymatic glycation results in the accumulation of advanced glycation end products (AGEs) in cartilage collagen. We studied the effect of AGE crosslinking on the stiffness of the collagen network in human articular cartilage.

METHODS

To increase AGE levels, human adult articular cartilage was incubated with threose. The stiffness of the collagen network was measured as the instantaneous deformation (ID) of the cartilage and as the change in tensile stress in the collagen network as a function of hydration (osmotic stress technique). AGE levels in the collagen network were determined as: Nepsilon-(carboxy[m]ethyl)lysine, pentosidine, amino acid modification (loss of arginine and [hydroxy-]lysine), AGE fluorescence (360/460 nm), and digestibility by bacterial collagenase.

RESULTS

Incubation of cartilage with threose resulted in a dose-dependent increase in AGEs and a concomitant decrease in ID (r = -0.81, P < 0.001; up to a 40% decrease at 200 mM threose), i.e., increased stiffness, which was confirmed by results from the osmotic stress technique. The decreased ID strongly correlated with AGE levels (e.g., AGE fluorescence r = -0.81, P < 0.0001). Coincubation with arginine or lysine (glycation inhibitors) attenuated the threose-induced decrease in ID (P < 0.05).

CONCLUSION

Increasing cartilage AGE crosslinking by in vitro incubation with threose resulted in increased stiffness of the collagen network. Increased stiffness by AGE crosslinking may contribute to the age-related failure of the collagen network in human articular cartilage to resist damage. Thus, the age-related accumulation of AGE crosslinks presents a putative molecular mechanism whereby age is a predisposing factor for the development of OA.

Antioxidants and fatty acids in the amelioration of rheumatoid arthritis and related disorders

The generation of reactive oxygen species (free radicals) is an important factor in the development and maintenance of rheumatoid arthritis in humans and animal models. One source of free radicals is nitric oxide produced within the synoviocytes and chondrocytes and giving rise to the highly toxic radical peroxynitrite. Several cytokines, including tumour necrosis factor-alpha (TNFalpha) are involved in the formation of free radicals, partly by increasing the activity of nitric oxide synthase. Indeed, nitric oxide may mediate some of the deleterious effects of cytokines on bone resorption. Aspirin, tetracyclines, steroids and methotrexate can suppress nitric oxide synthase. Dietary antioxidants include ascorbate and the tocopherols and beneficial effects of high doses have been reported especially in osteoarthritis. There is also evidence for beneficial effects of beta-carotene and selenium, the latter being a component of the antioxidant enzyme glutathione peroxidase. The polyunsaturated fatty acids (PUFA) include the n-3 compounds, some of which are precursors of eicosanoid synthesis, and the n-6 group which can increase formation of the pro-inflammatory cytokines TNFalpha and interleukin-6, and of reactive oxygen species. Some prostaglandins, however, suppress cytokine formation, so that n-3 PUFA often oppose the inflammatory effects of some n-6-PUFA. gamma-linolenic acid (GLA) is a precursor of prostaglandin E1, a fact which may account for its reported ability to ameliorate arthritic symptoms. Fish oil supplements, rich in n-3 PUFA such as eicosapentaenoic acid have been claimed as beneficial in rheumatoid arthritis, possibly by suppression of the immune system and its cytokine repertoire. Some other oils of marine origin (e.g. from the green-lipped mussel) and a range of vegetable oils (e.g. olive oil and evening primrose oil) have indirect anti-inflammatory actions, probably mediated via prostaglandin E1. Overall, there is a growing scientific rationale for the use of dietary supplements as adjuncts in the treatment of inflammatory disorders such as rheumatoid arthritis and osteoarthritis.

Thiol antioxidant, N-acetylcysteine, activates extracellular signal-regulated kinase signaling pathway in articular chondrocytes

Reactive oxygen species (ROS) generated during inflammation and aging contribute to the resorption of articular cartilage. Low antioxidant levels are a risk factor for arthritis because they protect cartilage from ROS. N-Acetylcysteine (NAC) is a ROS scavenger and, depending upon the concentration, an anti-inflammatory or prooxidant agent. Mechanisms of action for NAC were studied in primary human and bovine chondrocytes. NAC dose-dependently activated phosphorylation of extracellular signal-regulated kinases-mitogen-acivated protein kinases (ERK-MAPK). ERK activation peaked within 15 min and declined afterward up to 180 min. This activation was inhibited by the MAPKK inhibitor, PD098059. The induction was mimicked by other thiols, l-cysteine, reduced glutathione, and pyrrolidine dithiocarbamate (PDTC) but not by a nonthiol, N-acetylalanine. The total nonphosphorylated ERKs levels remained unaffected by these treatments. Activation of the ERK-MAPK pathway provides a mechanism for the reported promotion of chondrocyte survival by thiol antioxidants.

Aging and the etiopathogenesis and treatment of osteoarthritis

Knee OA in the older adult is often the result of multiple factors, some of which are intrinsic to the joint tissues and related to aging and others, such as obesity, which are extrinsic and influence the rate of development and severity of the disease. Obesity and quadricep weakness are factors that may be modifiable. The focus in managing patients with knee OA should not only be centered on the improvement of pain but also improvement in function. A combination of simple analgesics and nonpharmacologic measures, including exercises to strengthen the knee extensors, should be employed. Patients also can benefit from aerobic exercises, such as a walking or swimming program and strategies for joint protection. When medications are needed, the least toxic drugs possible should be used given the increased susceptibility of older adults to unwanted side effects.

Modeling impairment: using the disablement process as a framework to evaluate determinants of hip and knee flexion

Elders often present to health care providers with multiple inter-related conditions that determine an individual's ability to function. The disablement process provides a generalized sociomedical framework for investigating the complex pathways from chronic disease to disability. At each stage of the main pathway, associations may exist among primary physical factors and modifying variables that ultimately have downstream effects on the progression toward disability. The purpose of the present analysis is to examine the inter-relationships between a cohesive set of variables primarily at the level of impairment that may affect hip and knee flexion range of motion (ROM). The San Antonio Longitudinal Study of Aging enrolled 833 community dwelling Mexican (MA) and European American (EA) elders aged 64-78 years between 1992 and 1996. Of these, 647 had complete data from both a home-based and performance-based battery of assessments for these analyses. Concerning impairments, hip ROM was measured using an inclinometer, and knee ROM using a goniometer. Pain location and intensity were assessed using the McGill Pain Questionnaire. Peripheral vascular disease was assessed using doppler brachial and ankle systolic blood pressures. Ankle and knee reflexes, and vibratory sensation were assessed by a standardized neurological examination. As to diseases, diabetes was assessed using a combination of blood glucose levels and self-report, and arthritis by self-report. Concerning modifying variables, height and weight were directly measured and used to calculate BMI. Activity level was assessed with the Minnesota Leisure Time Questionnaire. Analgesic use was assessed by direct observation of medications taken within the past two weeks. We used structural equation modeling to test associations between the variables that were specified a priori. These analyses demonstrate the central role of BMI as a determinant of hip and knee flexion ROM. For an increase in level of BMI, the coefficients [SEM] for changes in levels of hip and knee ROM were -0.38 [0.05] and -0.26 [0.05], respectively. A higher BMI resulted in lower hip and knee ROM. BMI was also directly associated with prevalent diabetes (0.10 [0.05]) and arthritis (0.17 [0.05]). However, after adjustment for BMI, diabetes and arthritis did not have direct independent associations with either hip or knee ROM. BMI was also indirectly associated with knee, but not hip, ROM through paths including lower-leg pain, pain intensity, and neurosensory impairments. Diabetes had an indirect association with hip, but not knee ROM, through a path including peripheral vascular disease. In conclusion, BMI is a primary direct determinant of hip and knee ROM. The paths by which diabetes and arthritis lead to physical disability may be mediated, in part, at the level of impairment by BMI's association with joint range of motion. Interventions designed to decrease the impact of diabetes and arthritis on disability should track changes in BMI and joint ROM to measure the paths that account for the intervention's success. The observed associations suggest that interventions targeted to decrease BMI itself may lead to improved function in part through improved joint ROM.

Osteoarthritis of the hand: a modifiable disease

Osteoarthritis remains an exciting challenge in terms of an understanding of its pathophysiology, the development of disease-modifying drugs, and the search for more effective treatment for pain. With the aging of the general population, the impetus for research will increase, making the treatment of osteoarthritis, once considered an unalterable disease, an area of dynamic interest.

Vitamins and arthritis. The roles of vitamins A, C, D, and E

There are at least four mechanisms whereby the nutrient vitamins A, C, D, and E may be related to the processes that impede or give rise to OA. These nutrient vitamins have major roles in modulating oxidative stress, participating in immune responses, and contributing to cell differentiation. There is a substantial need to understand the contribution of these nutrients to OA, because they may provide important insight into ameliorating the initiation and progression of the disease. Simultaneously, greater understanding will add rationality to an area of potential intervention that is often based on anecdote. Investigation will be complex; there is the need to select appropriate systems. Typical animal model systems used in the study of OA are inappropriate because most animals can synthesize ascorbic acid. There is the need to disaggregate, as much as possible, the numerous subsets of OA and the plethora of processes that contribute to that heterogeneity. Certainly, there is the need to recognize the interdependency of the actions of each of these nutrients at the cellular level. Furthermore, humans rarely consume these nutrients as independent products. For example, watermelon is a primary source of both ascorbic acid and beta-carotene. Failure to address these complexities denies the scientist the opportunity to advance our understanding of health and disease processes. More importantly, failure to address these complexities denies the person with OA the opportunity to address his or her own health.