Research Summary Research topics:
1. Identifying and sequencing proteins found in the synovial fluid of patients with healthy and arthritic knees to determine the pathways involved in the development of osteoarthritis and rheumatoid arthritis
2. Studying the role that phospholipase A2 (sPLA2-IIA) plays in contributing to the progression of osteoarthritis
1. Determining that synovial tissue influences the progression of osteoarthritis and rheumatoid arthritis more than disordered cartilage cells
2. The possibility of slowing or stopping the progression of osteoarthritis through pharmacologic therapies that target phospholipase A2 (sPLA2-IIA)
Patient care applications of results:
1. Expanded understanding of how osteoarthritis and rheumatoid arthritis develop and progress toward identifying possible pharmacologic interventions
2. Sufficient scientific evidence to inform clinical trials of existing drugs that target a protein that is key in the inflammation and compromised joint function caused by osteoarthritis
Simplified patient care applications:
1. A scientific basis for future research designed to slow or stop the progress of rheumatoid arthritis and osteoarthritis
2. Increased joint function and reduced pain from osteoarthritis, allowing patients to enjoy a more active life
Saying “No” to Arthritis
OREF grant recipient isolates a key protein
Orthopaedic surgeon Reuben Gobezie, MD, two-time Orthopaedic Research and Education Foundation (OREF) grant recipient, knows arthritis is the most common disorder in musculoskeletal medicine. “Not a day goes by in my office that I don’t see somebody with arthritis,” he said.
More than 40 million Americans suffer from reduced joint function and pain due to arthritis, the most common cause of disability and a leading cause of work limitations.1
“That’s a big deal,” stated Dr. Gobezie, assistant professor in the Department of Orthopaedics at Case Western Reserve University and director of the Center for Musculoskeletal Proteomics in Cleveland. “What’s even bigger is that we don’t understand how it happens. We don’t have a single therapeutic that can address the mechanism of the disorder.”
With the help of two OREF grants, however, Dr. Gobezie is conducting research that will add to the understanding of the pathogenesis of arthritis and hopefully lead to some effective therapeutics. Assisted by an OREF Young Investigator Grant in 2005, Dr. Gobezie succeeded in identifying new biomarkers for osteoarthritis (OA) using proteomic technology. He is continuing this research with support from a 2011 OREF/Goldberg Research Grant in Arthritis.
Proteomics at the forefront
“Our first study compared the knee joint fluid of healthy patients and patients with arthritis,” said Dr. Gobezie. “This had never been done before.” Using mass-spectrometer-based proteomics, the goal was to identify new biomarkers specific to OA and rheumatoid arthritis, as well as identify possible target proteins that could be used to develop new pharmacologic therapeutics. One of the more promising proteins they identified was phospholipase A2 (sPLA2-IIA), which showed substantial elevations in both early and late OA synovial fluid.
“We also found that, contrary to what many people believe about arthritis being a cartilage-based disease, the synovial tissue seems to be influencing the progression of this disorder at least as much as, if not more than, the cartilage,” explained Dr. Gobezie. “This is a new concept.”
Building on these results, Dr. Gobezie is using his second OREF grant to validate in a controlled environment the findings from the prior clinical study.
The current project emerged from a collaboration between Dr. Gobezie and rheumatologist David M. Lee, MD, associate professor in medicine, Harvard Medical School. Again using mass spectrometry, this study is exploring the in vivo role of sPLA2-IIA in the pathogenesis of OA using destabilization of the medial meniscus (DMM) in a mouse model. DMM leads to cartilage damage (proteoglycan depletion, fibrillation, and erosions) in weight-bearing sections of the joint within 4 to 8 weeks with progressive damage noted through 26 weeks.
“Our rationale for these experiments is several-fold,” indicated Dr. Gobezie. “We observed a strong sPLA2-IIA upregulation in our human subjects with meniscal damage and early cartilage changes of OA. And we chose the DMM model because it may provide insight into post-meniscal damage pathophsyiology in early OA. Additonally, human sPLA2-IIA transgenic mice allow us to closely model the activity of this human sPLA2 isoform.”
As with all non-clinical studies, the DMM methodology does not fully replicate arthritis as it’s seen in humans. For example, subchondral sclerosis evident in humans with later stage arthritis does not occur. Nevertheless, when applied appropriately, the DMM model produces findings useful in understanding the pathophysiology of OA.
Phospholipase A2 in the model
The experiment starts with researchers cutting the ligament that holds the meniscus in place within the knee of the model, which results in a progression of arthritis that goes from healthy knee all the way through late arthritis within 30 days.
“We then take different time points along that spectrum from healthy to time zero to 30 days, homogenize those joints, then sequence the proteins within them,” said Dr. Gozebie, who expects to see a strong correlation between phospholipase A2 and the progression of arthritis.
Based on results to date, the team hypothesizes that arthritis is the result of a chronic wound signal that starts in the meniscus. When the chronic wound doesn’t heal, it spreads to the synovial tissue and drives a clinic wound pattern that eventually deteriorates and erodes the joint. Importantly, there are strong indications that a therapeutic based on sPLA2-IIA may stop the progression of arthritis.
In addition to achieving promising results in the lab, the team is encouraged that their work is gaining significant attention through publication in major orthopaedic and basic science journals.
“The 2005 OREF grant allowed us to compare synovial fluid of patients with healthy knees to the fluid of those who had different stages of arthritis. No one had ever done that. A lot of the studies being done now spun off that research. It was thanks to the OREF grant that I could leverage that and it made a tremendous impact on my career,” Dr. Gobezie said.
Still, Dr. Gobezie is deeply concerned that financial pressures might slow or halt their research. “Clinician scientists are becoming an endangered species. The scarcity of funding threatens our work and is driving away new scientists,” he explained. “Until National Institutes of Health funding levels are increased substantially—or additional large-scale funding sources are developed—all our work is at risk.”
From a patient perspective, Dr. Gobezie explained that arthritis strikes at the heart of what most Americans value highly—activity and motion. “Our work represents a significant contribution toward developing novel therapeutics that can prevent the progression of arthritis and relieve the pain many of our patients struggle with every day,” said Dr. Gobezie. “The ultimate objective is to eliminate arthritis altogether and put ourselves out of business. That would be a big deal.”
1United States Bone and Joint Initiative: The Burden of Musculoskeletal Diseases in the United States, Second Edition. Rosemont, IL: American Academy of Orthopaedic Surgeons; 2011.