Osteoarthritis year in review 2015: clinical

Microarray study of gene expression profile to identify new candidate genes involved in the molecular mechanism of leptin-induced knee joint osteoarthritis in rat

BACKGROUND

Osteoarthritis (OA) is one of the most prevalent chronic joint diseases while the precise genetic mechanism remains elusive. In this study, we investigated the gene expression profile in OA by microarray analysis.

RESULTS

Histopathological characteristics of OA cartilage were examined using a rat model of leptin-induced OA. Gene expression profile of leptin-induced articular cartilage and healthy rat cartilage were compared using genome-wide microarray hybridization. A total of 1857 genes differentially expressed genes (1197 upregulated and 660 downregulated) were identified, some of which are known to be associated with leptin-induced OA phenotype. These included genes related to MMPs, inflammatory factors, growth factors, apoptotic genes and osteogenic genes. In addition, upregulated expressions of some new candidate genes, which have hitherto fore not been linked to OA (such as BCL2L11) were detected in leptin-induced OA cartilage, which suggests that these genes might be important for OA molecular mechanism.

CONCLUSION

Our findings suggest that pathogenesis of leptin-induced OA involves modulation of expression of multiple genes, although the underlying molecular mechanisms need to be studied further. Further investigation of leptin-induced gene expression changes is needed to gain new insights into the molecular mechanism of OA pathogenesis.

Mesenchymal Stem Cell-Based Cartilage Regeneration Approach and Cell Senescence: Can We Manipulate Cell Aging and Function?

Aging is the most prominent risk factor triggering several degenerative diseases, such as osteoarthritis (OA). Due to its poor self-healing capacity, once injured cartilage needs to be reestablished. This process might be approached through resorting to cell-based therapies and/or tissue engineering. Human mesenchymal stem cells (MSCs) represent a promising approach due to their chondrogenic differentiation potential. Presently, in vitro chondrogenic differentiation of MSCs is limited by two main reasons as follows: aging of MSCs, which determines the loss of cell proliferative and differentiation capacity and MSC-derived chondrocyte hypertrophic differentiation, which limits the use of these cells in cartilage tissue regeneration approach. The effect of aging on MSCs is fundamental for stem cell-based therapy development, especially in older subjects. In the present review we focus on homeostasis alterations occurring in MSC-derived chondrocytes during in vitro aging. Moreover, we deal with potential cell aging regulation approaches, such as cell stimulation through telomerase activators, mechanical strain, and epigenetic regulation. Future investigations in this field might provide new insights into innovative strategies for cartilage regeneration and potentially inspire novel therapeutic approaches for OA treatment.

Nonoperative Options for Management of Articular Cartilage Disease

Nonoperative options for articular cartilage injury are pervasive but have not shown to be curative. Recommendations for low-impact exercise and weight loss provide benefit and are a foundation for the treatment of osteoarthritis. Judicious use of NSAIDs and acetaminophen can be appropriate for pain management. Topical NSAIDs may be a treatment option with fewer side effects than its oral counterpart. Additionally, viscosupplementation injections are useful for mild to moderate knee osteoarthritis, whereas short-term pain relief is provided by intra-articular corticosteroid injections. Future studies to individualize treatment options based on patient phenotype and genotype may hold promise.

T140 blocks the SDF-1/CXCR4 signaling pathway and prevents cartilage degeneration in an osteoarthritis disease model

Osteoarthritis (OA) is one of the most common diseases affecting older people; however, there remains no effective targeted drug to combat OA. The aims of this study were (1) to explore the effect of T140 in regulating degeneration of articular cartilage in vivo by targeted blocking of the SDF-1/CXCR4 signaling pathway, and (2) to provide experimental evidence for the development of a novel OA-targeted pharmacotherapy. Thirty-six healthy Hartley guinea pigs were randomly divided into three groups: a T140-treated group (n = 12), a phosphate buffer saline control group (n = 12) and an untreated control group (n = 12). At 2, 4, 6, 8, 10 and 12 weeks of treatment, SDF-1 in serum was quantified by enzyme-linked immunosorbent assay. At 12 weeks of treatment, the cartilage from knee tibial plateau in the knee joint was collected for H&E, Safranin-O staining and Mankin grading; measurement for mRNA levels of matrix metalloproteinases (MMP-3, MMP-9 and MMP-13), aggrecan (ACAN) and collagen II (Col II) using RT-PCR; and measurement for Col II protein levels by western blot. Results showed that SDF-1 in serum increased in the T140 group and increased in the control groups. H&E and Safranin-O staining revealed less cartilage loss in T140-treated animals compared to controls. The mRNA levels of MMP-3, MMP-9 and MMP-13 in cartilage were much lower in the T140 group than other groups, but mRNA levels of ACAN and Col II in cartilage were higher in the T140-treated group. Col II protein levels in the T140 group and control groups were different. T140 can downregulate the expression of matrix-degrading enzyme and lessen the degeneration of cartilage by blocking the SDF-1/CRCR4 signaling pathway in vivo. This mechanism may present a pharmacological target for the treatment of OA.

Measuring the musculoskeletal aging phenotype

The world is aging. The population aged over sixty years worldwide is predicted to rise from 841 million in 2013 to more than 2 billion by 2050. Musculoskeletal (MSK) disease is a significant burden on the aging population, contributing 7.5% of the disease burden in those aged over 60 years. MSK diseases have a pronounced effect on disability level and independence in old age, with a consequent significant public health burden and impact on quality of later life. As numbers of older individuals and their disease burden increase, it is important to examine MSK disease in older life in detail. The musculoskeletal aging phenotype comprises four often interwoven key elements - osteoporosis, osteoarthritis, sarcopenia and frailty - and this review will focus on these four themes. It is crucial that we are able to accurately measure each phenotype in order that we might identify those individuals at greatest risk of developing these conditions, and design trials of therapeutic agents that might impact their development. Accurate measurement of the musculoskeletal aging phenotype is necessary firstly to document the burden of each condition, and then to enable factors to be identified which may accelerate or retard their development or progression. In some areas of MSK disease, this work is more advanced (osteoporosis); in other areas (sarcopenia) the field is currently very rapidly evolving. We will explore the tools currently used to measure the musculoskeletal aging phenotype and how they compare, as well as highlight areas where more work is needed.

Autoimmune enteropathy

Autoimmune enteropathy (AIE) is a very rare clinical entity primarily reported in infancy. In recent years, adult involvement has also been documented. Intractable diarrhea is the main manifestation, which is associated with small bowel villous atrophy. Corticosteroids are considered the first-choice therapy for AIE. In some patients, immunosuppressive therapies are necessary.

Effects of a tailor-made exercise program on exercise adherence and health outcomes in patients with knee osteoarthritis: a mixed-methods pilot study

Introduction

Previous studies showed that exercise intervention was effective in symptoms control of knee osteoarthritis (OA) but poor intervention adherence reduced the exercise effect. It has been suspected that the design of exercise intervention mainly from the health care professionals’ perspective could not address the patients’ barriers to exercise. Therefore, a tailor-made exercise program which incorporated the patient’s perspective in the design was developed and ready for evaluation.

Objectives

This pilot study estimated the effects of a tailor-made exercise program on exercise adherence and health outcomes, and explored the participants’ perception and experience of the program.

Methods

The intervention of this study was a 4-week community-based group exercise program, which required the participants to attend a 1-hour session each week. Thirty-four older people with knee OA were recruited to the program. Mixed-methods study design was used to estimate the effects of this program and explore the participants’ perception and experience of the program. Exercise adherence and performance in return-demonstration of the exercise were assessed at 12 weeks after the program. Disease-specific health status (Western Ontario and McMaster Universities Osteoarthritis Index), general health status (12-item Short Form of the Medical Outcome Study Questionnaire), knee range of motion, muscle strength, and endurance of the lower extremities (Timed-Stands Test) were measured at the beginning of the program and 12 weeks after. Six participants were interviewed individually on the 12th week.

Results

Thirty-three participants (75.0±7.3 years) completed the one-group pretest and post-test study. The participants’ exercise adherence was 91.4%±14.54%, and their correct performance in return-demonstration was 76.7%±21.75%. Most of the participants’ health outcomes significantly improved at posttests except the 12-item Short Form of the Medical Outcome Study Questionnaire physical health summary score. The qualitative findings provided rich information to explain and support the quantitative results.

Conclusion

The results of this study showed that a tailor-made exercise program could improve exercise adherence and health outcomes in older people with knee OA.

Discoidin Domain Receptor 2 as a Potential Therapeutic Target for Development of Disease-Modifying Osteoarthritis Drugs

Osteoarthritis (OA) is the most common form of arthritis disorders, but the identification of therapeutic targets to effectively prevent OA has been increasingly difficult. The goal of this investigation is to provide experimental evidence that discoidin domain receptor 2 (DDR2) may be an ideal target for the development of disease-modifying OA drugs. Ddr2 was conditionally deleted from articular cartilage of adult mouse knee joints. Aggrecan-CreERT2;floxed Ddr2 mice, which were generated by crossing Aggrecan-CreERT2 mice with floxed Ddr2 mice, then received tamoxifen injections at the age of 8 weeks. The mice were then subjected to destabilization of the medial meniscus (DMM) surgery. At 8 and 16 weeks after DMM, mice were euthanized for the collection of knee joints. In a separate experiment, Aggrecan-CreERT2;floxed Ddr2 mice were subjected to DMM at the age of 10 weeks. The mice then received tamoxifen injections at 8 weeks after DMM. The mice were euthanized for the collection of knee joints at 16 weeks after DMM. The progressive process of articular cartilage degeneration was significantly delayed in the knee joints of Ddr2-deficient mice in comparison to their control littermates. Articular cartilage damage in the knee joints of the mice was associated with increased expression profiles of both Ddr2 and matrix metalloproteinase 13. These findings suggest that DDR2 may be an ideal target for the development of disease-modifying OA drugs.