Obesity, aging genes may play role in arthritis
The frayed, white substance is a torn meniscus being removed during surgery. Each year in the United States, at least half a million people have surgery for meniscus tears. All of them are at increased risk for developing arthritis in the knee later in life. Credit: ROBERT H. BROPHY, MD
(Medical Xpress)—Studying gene activity in tissue removed from injured knees, researchers at Washington University School of Medicine in St. Louis have found that genes related to obesity and aging may contribute to the development of osteoarthritis.
Osteoarthritis is the most common knee disorder. The problem involves the breakdown of cartilage, causing pain, swelling and stiffness that make it difficult, over time, to move the joint or put weight on it.
The new study involved 68 people who had surgery to repair or remove a torn meniscus, the cartilage in the knee that acts as a cushion between the shinbone and the thighbone. The findings are available online in the International Journal of Obesity.
"Having a tear in the meniscus is associated with an increased risk of developing osteoarthritis later in life," says principal investigator Robert H. Brophy, MD. "Some studies have suggested that more than 50 percent of people with a meniscus tear will go on to develop arthritis 10 to 20 years later, but we don't precisely understand how one leads to the other."
This video is not supported by your browser at this time.For the study, Brophy, a sports medicine specialist and associate professor of orthopaedic surgery, and M. Farrooq Rai, PhD, postdoctoral research scholar in orthopaedic surgery, analyzed the activity of 28 genes related to obesity, aging and the secretion of inflammatory substances in meniscus tissue to learn how genes related to age and body mass might influence the development of arthritis.
"We know there's a mechanical relationship," he says. "People who are obese have increased pressure and force on the knee joint. And older people have more wear and tear on the joints. But we wanted to see whether something else is going on that may accelerate the risk for osteoarthritis."
Brophy and his colleagues found four aging-related genes and one obesity-related gene behaving abnormally in torn meniscus tissue. Heavy patients had low activity levels in the obesity gene, and older patients had low activity in aging-related genes. Low activity in the genes may contribute to disease by leaving the tissue without enough of the proteins necessary for the meniscus to function normally.
The researchers also noticed differences in the activity of genes involved in degrading tissue and increasing inflammation levels.
"In general, I think we can say that the inflammatory molecules we see in the tissue are not good," says co-investigator Linda J. Sandell, PhD. "The meniscus is a stable, slowly changing tissue. But if it's overstimulated, that usually means it's being irritated in some way. What we don't know at this point is whether the meniscus is irritated because it was torn by injury or whether it's responding to something else. It's even possible that the tissue tore because it already was in a pre-osteoarthritis condition."
Sandell, the Mildred B. Simon Research Professor of Orthopaedic Surgery, leads the Center for Musculoskeletal Research and also serves as president of the Osteoarthritis Research Society. This project, like much of her research, is directed at finding markers for osteoarthritis before patients actually develop symptoms. The meniscus is a key focus of those studies, and she's particularly excited that these genetic and molecular studies are being conducted in human tissue.
"These findings are directly applicable to human disease," she says. "We're beginning to learn that the meniscus itself is manufacturing things that could degrade tissue in the knee, so it may be an active player in osteoarthritis. Unfortunately, many drug companies aren't excited about developing drugs to inhibit osteoarthritis until we can show that it's possible to detect it early."
The current study looked primarily at the activity of genes already suspected of being involved in the development of osteoarthritis. But Sandell and Brophy say their next step involves analyzing every gene that's active in meniscus tissue. They'll also continue to follow patients to see whether it's possible to connect the dots that link genetic and molecular markers in the meniscus to clinical outcomes in patients.
More information: International Journal of Obesity, advance online publication. doi:10,1038/ijo.2012.221
Journal reference: International Journal of Obesity
- FDA approves knee-injury device for humans Oct 02, 2007 | not rated yet | 0
- Loss of motion after knee surgery may increase osteoarthritis risk, research suggests Jul 09, 2011 | not rated yet | 0
- Genes that promote cartilage healing protect against arthritis Apr 27, 2012 | not rated yet | 0
- Surgical repair of knee injuries does not decrease risk of osteoarthritis Jun 29, 2010 | not rated yet | 0
- Repair of torn knee meniscus at the time of ACL reconstruction is safe and effective for children Mar 15, 2010 | not rated yet | 0
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Change in momentum when a body is thrown up and falls back down.
1 hour ago Say, a body of mass 'm' is thrown at a certain angle with the vertical with certain initial velocity 'u'. The initial momentum of this object is mu....
change in speed and wavelength of light while travelling from one med
1 hour ago what is the mechanism by which light changes its speed and wavelength while travelling from one medium to other. I know it is c/n or lamda/n and know...
Calculus of Variation - Classical Mechanics
4 hours ago I'm reading Classical Mechanics (Taylor), and the 6th chapter is a basic introduction to calculus of variations. I'm super confused :confused: ...
Frictional Force Equation Doesn't Make Sense
4 hours ago Frictional Force is mathematically defined as: Ff = μ*m*g*cos(θ) , where μ is the coefficient of friction, m is the mass of the object, g is...
Calculating Steam Pressure in Closed Container
10 hours ago I am trying to calculate the volume of liquid water i need to place in a sealed container in order to obtain 10 psi of steam pressure in that closed...
Learning curve of Electromagnetism?
15 hours ago I'm taking a first year physics course and have been having a little trouble with the basics of newtons laws and forces and whatnot, though nothing...
- More from Physics Forums - Classical Physics
More news stories
(HealthDay)—Compared to clinical diagnosis of synovitis, ultrasound-detected synovitis provides either improved sensitivity or specificity when used with the American College of Rheumatology/European League ...
Arthritis & Rheumatism May 15, 2013 | not rated yet | 0
(HealthDay)—A genome-wide linkage scan has identified the chromosome 17p11.2-q11.2 region as the susceptibility locus for fibromyalgia, according to research published in the April issue of Arthritis & ...
Arthritis & Rheumatism May 11, 2013 | not rated yet | 0
Scientists have discovered that fat cells in the knee secrete a protein linked to arthritis, a finding that paves the way for new gene therapies that could offer relief and mobility to millions worldwide.
Arthritis & Rheumatism May 08, 2013 | 5 / 5 (5) | 0 |
Researchers from the Royal College of Surgeons in Ireland (RCSI) have discovered that a new treatment for the inflammatory condition, Systemic Lupus Erythmstosus (SLE) could potentially benefit Irish patients who suffer from ...
Arthritis & Rheumatism May 07, 2013 | not rated yet | 0
A team of researchers led by a Boston University Biomedical Engineer has developed a new joint lubricant that could bring longer lasting relief to millions of osteoarthritis sufferers. The new synthetic polymer supplements ...
Arthritis & Rheumatism May 02, 2013 | 4 / 5 (1) | 0
4 hours ago | not rated yet | 0
4 hours ago | 4.5 / 5 (2) | 0 |
4 hours ago | not rated yet | 0 |
The neural machinery underlying our olfactory sense continues to be an enigma for neuroscience. A recent review in Neuron seeks to expand traditional ideas about how neurons in the olfactory bulb might encode information about ...
May 17, 2013 | not rated yet | 0 |
3 hours ago | not rated yet | 0
4 hours ago | not rated yet | 0