How Important Is Collagen Destruction In Arthritis? A Study With Collagenase-resistant Knockin Mice
Funder
National Health and Medical Research Council
Funding Amount
$529,723.00
Summary
Aggecan and collagen are important structural molecules in cartilage. Together they allow cartilage to bear weight and resist compression. In arthritis, collagen is degraded by collagenases and aggrecan is degraded by aggrecanases. Aggrecan loss is a feature of cartilage disease. Early aggrecan loss is well documented and usually precedes clinical symptoms, suggesting that it is the initiating step in cartilage pathology. Aggrecan loss precedes collagen damage in explant culture, however it is n ....Aggecan and collagen are important structural molecules in cartilage. Together they allow cartilage to bear weight and resist compression. In arthritis, collagen is degraded by collagenases and aggrecan is degraded by aggrecanases. Aggrecan loss is a feature of cartilage disease. Early aggrecan loss is well documented and usually precedes clinical symptoms, suggesting that it is the initiating step in cartilage pathology. Aggrecan loss precedes collagen damage in explant culture, however it is not known whether inhibiting aggrecanases is sufficient to block cartilage damage long-term. In contrast, other studies suggest that aggrecan is only lost after damage to the collagen scaffold. These studies propose that clipping of the collagen scaffold may initiate aggrecan release; with progressive degeneration and collagen clipping, more aggrecan is lost, until ultimately the scaffold is severely damaged and aggrecan is severely depleted. Cartilage can only withstand a limited degree of collagen degradation and any significant damage to the network is widely considered to be irreparable. It is unclear what role aggrecanases and collagenases have in initiating and perpetuating cartilage damage. We have mice with aggrecan resistant to aggrecanases and mice with inactive aggrecanase. We will also create mice with collagen resistant to collagenase. We will use these mice to determine the contribution of collagenases and aggrecanases to the initiation and progression of cartilage damage, in three models of joint disease. We will identify differences in time of disease onset, rate of disease progression and disease severity. The results will show whether one or both activities is important for the initiation and progression of joint disease. This will reveal whether single or combination therapies are required for the management of arthritis. The research will inform the pharmaceutical industry on directions for the development of new drugs to prevent joint disease.Read moreRead less
Functional Variants Of RUNX2 Related To Bone Density
Funder
National Health and Medical Research Council
Funding Amount
$451,938.00
Summary
Bone density and osteoporosis have a genetic component. Identifying genes that are involved in determining bone density may permit advances in controlling osteoporosis. We have identified a variant in a gene called RUNX2 that is related to bone density high enough to protect individuals four fold against Colle's fracture, the common wrist fracture seen in women. This variant is highly correlated with changes in the second promoter of RUNX2, such that the high bone density form appears to be the ....Bone density and osteoporosis have a genetic component. Identifying genes that are involved in determining bone density may permit advances in controlling osteoporosis. We have identified a variant in a gene called RUNX2 that is related to bone density high enough to protect individuals four fold against Colle's fracture, the common wrist fracture seen in women. This variant is highly correlated with changes in the second promoter of RUNX2, such that the high bone density form appears to be the ancestral form of this gene. We now need to know how this change in this promoter alters bone density and we are following up on observations that other important transcription factors bind to the variable site in the promoter. Furthermore, we have assembled a large collection of samples from people who have had extensive measures of bone density and arthritis in order to accurately measure the impact of this gene on bone density, osteoarthritis and bone fracture. In addition, some people with bone fracture at the hip, or low bone density, have mutations in this gene. Such mutations in a region called the Q-repeat are rather common, 1-200 people are carriers. Our data show that these mutant proteins are not as efficient at their task of regulating other genes. We now want to know how this occurs in a molecular sense, since it is known that the Runx2 protein resides in the nucleus of the cell and interacts with many other regulators. This part of the project is being done with one of the world experts on gene regulation in bone cells. Since RUNX2 is a master regulator of the cells that make bone, this gives hope that it may be possible to alter bone formation through this master regulator.Read moreRead less
Ankylosing spondylitis (AS) is a chronic arthritis which causes severe back and joint pain in young men and women. It can be difficult to diagnose as it takes years to show up on x-ray, and by then the joints are already damaged. This study looks at new ways to diagnose people with AS much earlier, which will allow earlier treatment and better outcomes. The study will also look at the role of lifestyle factors such as diet and physical activity which might impact on AS.
The Therapeutic Value Of Targeting Wnt Signalling For The Treatment Of Osteoarthritis
Funder
National Health and Medical Research Council
Funding Amount
$561,535.00
Summary
Osteoarthritis (OA) affects 1.62 million Australians and imposes a significant burden on healthcare. It is characterised by damage to joint cartilage, and increased bone formation with formation of bone spurs. Our studies will determine the importance of the Wnt signalling pathway in mediating OA joint degeneration and identify mechanisms that regulate the activation of this pathway in OA. This will inform the development of novel therapeutic strategies which could halt joint damage in OA.
Regulation Of ADAMTS-5 Activity By Keratan Sulphate-binding Exosites
Funder
National Health and Medical Research Council
Funding Amount
$213,342.00
Summary
Arthritis and musculoskeletal conditions are the predominant cause of disability in Australia. The burden of arthritis is felt not only by patients, their families and carers, but also the labour market and the national economy. There is a pressing need to identify new targets for design of inexpensive arthritis therapies. The TNF antagonists have proved effective in managing rheumatoid arthritis (RA), but they are expensive, administered by injection, and in general, only prescribed in Australi ....Arthritis and musculoskeletal conditions are the predominant cause of disability in Australia. The burden of arthritis is felt not only by patients, their families and carers, but also the labour market and the national economy. There is a pressing need to identify new targets for design of inexpensive arthritis therapies. The TNF antagonists have proved effective in managing rheumatoid arthritis (RA), but they are expensive, administered by injection, and in general, only prescribed in Australia for patients who respond poorly to DMARDs. Their long-term efficacy and safety is not yet determined. There are no treatments for osteoarthritis (OA), the disease that occurs more frequently with age and is characterised by destruction of cartilage and aggrecan. New drugs that protect against aggrecan breakdown are urgently needed for OA and they would also be valuable adjunct therapies to the DMARDs for treatment of RA. We have discovered that the major aggrecan-degrading enzyme is ADAMTS-5. ADAMTS-5 is, therefore, a potential target for arthritis therapies. Unfortunately, drugs targeting the active site of ADAMTS-5 are predicted to fail, given the wide tissue distribution of ADAMTS-5, the high level of homology between the active site of ADAMTS enzymes and matrix metalloproteinases (MMPs), and the notorious failure of MMP active site inhibitors in clinical trials. The aim of this project is to determine whether ancillary domains of ADAMTS-5 are a viable alternative target to the active site. We have evidence to suggest that keratan sulphate, which is covalently attached to the aggrecan core protein, can modulate aggrecan cleavage by ADAMTS enzymes. We aim to identify opportunities for developing antagonists that block keratan sulphate binding, or keratan sulphate analogues that block enzyme binding to its substrate. The data will inform the pharmaceutical industry on new directions for modulating aggrecanolysis by ADAMTS-5.Read moreRead less
Knee osteoarthritis (OA) affects about 30% of Australians over the age of 65, but also at younger ages. It causes joint pain and stiffness, especially on exercise. The cause is unknown but it results in loss of joint cartilage. There are few treatments available to stop the progression, which can finally result in need for an artificial joint. Most treatments such as paracetamol and non-steroid anti-inflammatory drugs (NSAIDs) reduce pain but have no effect on cartilage. NSAIDs can have serious ....Knee osteoarthritis (OA) affects about 30% of Australians over the age of 65, but also at younger ages. It causes joint pain and stiffness, especially on exercise. The cause is unknown but it results in loss of joint cartilage. There are few treatments available to stop the progression, which can finally result in need for an artificial joint. Most treatments such as paracetamol and non-steroid anti-inflammatory drugs (NSAIDs) reduce pain but have no effect on cartilage. NSAIDs can have serious side effects such as stomach ulcers and increased cardiovascular events (such as heart attacks). Fish oil has possible benefits in OA as it decreases pain and inflammation in rheumatoid arthritis (RA, another type of arthritis with joint inflammation and swelling), less use of NSAID in patients with RA, and in laboratory experiments may reduce cartilage breakdown in OA. It is likely that fish oil will have few side effects and decrease blood cholesterol. Many people with OA are already taking fish oil, however, there is no studies to know if it is effective in OA. The aim of this proposal is to study the effect of fish oil on pain and progression of knee OA, by doing a randomised clinical trial. Participants with knee OA will be given either high dose fish oil or similar oil with low levels of fish oil. The study will run for 2 years and during that time, we will measure pain and blood levels of fatty acids (part of the fish oil) and cholesterol. At the beginning and end of the study, magnetic resonance imaging (MRI) of the knee, a knee xray, and bone density testing will be done. The outcomes of the study will be to determine if fish oil affects pain and function (measured by questionnaires) and progression of OA (measured by cartilage changes on MRI). If fish oil is shown to reduce pain and disability and cartilage loss in OA, it will provide Australians with OA an alternative treatment that is low in side effects with positive effects on cardiovascular disease.Read moreRead less
REGULATION OF GLUCOCORTICOID SENSITIVITY BY ANNEXIN-1
Funder
National Health and Medical Research Council
Funding Amount
$533,828.00
Summary
Steroids like prednisolone or cortisone are very effective at reducing inflammation in diseases like rheumatoid arthritis and are particularly known to decrease substances involved in inflammation. Almost 70% of patients with rheumatoid arthritis are treated more or less continuously with steroids. Steroid resistance (need for higher doses) or changes in steroid-sensitivity has been widely recognized in asthma, inflammatory bowel disease, and rheumatoid arthritis. Many new drug therapies however ....Steroids like prednisolone or cortisone are very effective at reducing inflammation in diseases like rheumatoid arthritis and are particularly known to decrease substances involved in inflammation. Almost 70% of patients with rheumatoid arthritis are treated more or less continuously with steroids. Steroid resistance (need for higher doses) or changes in steroid-sensitivity has been widely recognized in asthma, inflammatory bowel disease, and rheumatoid arthritis. Many new drug therapies however have the aim of keeping cortisone use to a minimum because of undesirable side effects like osteoporosis. Annexin-1 is an anti-inflammatory substance important in arthritis development which is also known to mediate many of the actions of steroids. However, the possible contribution of annexin-1 to mediate the effect of steroids in the regulation of these substances has not been examined. Moreover, how annexin-1 turns genes on is not known. Our studies will therefore reveal whether the absence of annexin-1 will increase inflammatory substances turn genes, and secondly, by determining the possible substances regulated by annexin-1 if the treatment with steroids are less effective in the absence of annexin-1. If annexin-1 is found either to increase anti-inflammatory substances or to mediate the effect of therapeutic steroids, its capacity to be involved in the beneficial effect of steroids may have an important impact in treatment of arthritis and other inflammatory diseases. If annexin-1 functionally acts as steroids, the reduction or discontinuation of steroid use will be possible.Read moreRead less
Defining The Role Of GILZ In Inflammatory Arthritis
Funder
National Health and Medical Research Council
Funding Amount
$675,030.00
Summary
Corticosteroids are commonly used to treat inflammatory diseases such as arthritis. Their action is based on effects on natural inflammation control pathways. One such pathway is that mediated by the protein known as GILZ (glucocorticoid induced leucine zipper). The function of this protein in disease is not well understood, and the research proposed here will increase understanding of its role. This knowledge could yield new treatments for arthritis and other inflammatory diseases.
Chondrocyte Hypertrophy In Development And Disease
Funder
National Health and Medical Research Council
Funding Amount
$360,018.00
Summary
Whereas chondrocyte hypertrophy is a normal feature of skeletal growth, in adult chondrocytes it is associated with osteoarthritis (OA). We propose that collagen II fragments provide signals for hypertrophy in cartilage. The lack of collagen II fragments in our collagenase-resistant mouse provides a unique opportunity to address the role of collagen II fragments in driving cellular hypertrophy. We will identify bioactive collagen II fragments that represent novel targets for OA therapies
Factors That Affect Knee Structure In Healthy Women
Funder
National Health and Medical Research Council
Funding Amount
$199,176.00
Summary
Osteoarthritis (OA) has the largest impact of any chronic disease on burden of disease borne in later life, affecting women more often than men. The importance of OA has been acknowledged by its listing within musculoskeletal disease, the 7th health priority in Australia. It is 4 times as common in women as in men.Treatments which slow or prevent OA progressing are limited, so prevention must play a key role. With increasing disease severity, joint cartilage is lost. We have recently developed a ....Osteoarthritis (OA) has the largest impact of any chronic disease on burden of disease borne in later life, affecting women more often than men. The importance of OA has been acknowledged by its listing within musculoskeletal disease, the 7th health priority in Australia. It is 4 times as common in women as in men.Treatments which slow or prevent OA progressing are limited, so prevention must play a key role. With increasing disease severity, joint cartilage is lost. We have recently developed a method to measure joint cartilage from magnetic resonance imaging (MRI) scans which is able to assess the severity of structural changes in the knee. Using this method will allow us to assess 2 issues: 1) Obesity is the only identified modifiable risk factor for knee OA. However, the mechanism is poorly understood. Weight loss programs may be more effective at reducing the risk of OA if they are combined with programs aimed at maintaining muscle mass. 2) Bone is important in development of Knee OA, but its role is poorly understood. Understanding how bone metabolism relates to risk of knee OA may allow us to prevent disease. Bone is more likely to respond to pharmacological manipulation than cartilage. Thus it may prove a more effective target for intervention than cartilage. The Geelong Osteoporosis Study was begun in 1994 to study bone health in Australian women (urban and rural). Much information relevant to the risk of OA has been collected over the past decade. By performing MRI of the knee now and in 2 years time, we will determine the effect of different measures of obesity and bone metabolism on structural change at the knee which predisposes to OA. Since both of these factors (obesity and bone metabolism) are potentially modifiable, this study may offer new avenues of prevention and therapy in knee OA. This has the potential to promote a better quality of life as people age and to reduce the economic burden of knee OA in the community.Read moreRead less