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  • A new study finds a drug compound was able to help reduce inflammation in joints affected by osteoarthritis.
  • The study was conducted in animals, but researchers expect to include humans in trials in the next year.
  • About 32 million people in the U.S. have osteoarthritis.

Millions of Americans are living with osteoarthritis, a common and painful form of arthritis that affects the many tissues of the joints, most often those in the hands, hips, knees, lower back, and neck.

While the severity of this condition varies among people, it can lead to a decreased range of motion or instability in the joint, and weakness in the surrounding muscles.

These symptoms can impact a person’s quality of life and their ability to carry out daily activities.

While there are effective therapies — many of which focus on relieving symptoms — so far no treatments can repair the damage to the joint.

New research by a team led by scientists at the Keck School of Medicine of USC in Los Angeles aims to change that.

In an animal study, researchers found that a drug compound, R805/CX-011, reduced inflammation in the affected joint, while still managing pain and stiffness.

“We saw a profound effect on joint pain, structure, and function,” study author Dr. Denis Evseenko, an associate professor of orthopedic surgery, stem cell research, and regenerative medicine at the Keck School of Medicine, said in a statement.

It’s too soon to know if this drug will help people with osteoarthritis, because not all drugs that show positive results in animals end up working well in people.

However, researchers plan to test the drug in initial clinical trials later this year, in collaboration with the start-up Carthronix, according to the release. They currently have funding to test knee injections of the drug in up to 70 patients.

The results of the study, published March 22 in the journal Science Translational Medicine, suggest that R805/CX-011 modulates a key cell receptor in the body’s immune system, known as glycoprotein 130, or gp130.

In addition to regulating the immune response and inflammation, this cell receptor is involved in regulating other biological processes such as cardiovascular function and the survival of neurons.

While gp130 plays several important roles in the body — including responding to damaged cartilage due to a joint injury — it can also contribute to hyper-inflammation in the joint.

This excess inflammation can lead to further destruction of the joint cartilage, a key feature of osteoarthritis.

“In trying to fix the problem, the immune system causes even more damage,” Evseenko said in the release. “But gp130 is a vital receptor. You cannot inhibit it, because it’s needed for healthy stem cells, as well as cardiovascular and immune function.”

To understand what role gp130 plays in joint hyper-inflammation in osteoarthritis, researchers genetically engineered mice in order to block the activation of a specific gp130 signaling pathway.

These mice showed signs of increased resistance to degenerative joint disease, including to surgically induced osteoarthritis.

“No white blood cells rushed to the scene and no hyper-inflammation occurred,” Evseenko said in the release.

In addition, the mice showed enhanced wound healing capabilities, including regenerating new skin, along with hair follicles, glands and other skin structures.

Researchers also carried out tests of R805/CX-011 in small and large animal models of osteoarthritis — rats and dog. These animals underwent a surgical procedure to mimic the joint degeneration of osteoarthritis.

This part of the study mirrored a human clinical trial, with animals receiving joint injections of one of three doses of the drug or a salt solution (inactive saline).

Rats that received the drug injections showed signs of less joint cartilage damage. In dogs that received the drug, there were signs of less damage to the joint, as well as lower levels of pain and lameness.

Dr. Rupak Thapa, an assistant professor of rheumatology and immunology at Wake Forest University School of Medicine in Winston-Salem, North Carolina, said despite osteoarthritis being so common — affecting around 32 million American adults — we still don’t have a cure for this condition.

“The current available treatments for knee osteoarthritis are geared toward controlling the symptoms,” he said, “It’s like if you had a fever from an infection, and you were just treating the fever but not the infection.”

Treatments for knee osteoarthritis include lifestyle modifications such as weight loss, physical therapy, and changing your activities to reduce symptoms.

Doctors may also recommend medications to control the pain, including over-the-counter drugs and prescription opioids, as well as anti-inflammatory drugs, topicals like capsaicin, and antidepressants.

Steroid injections into the joint are another option to reduce inflammation. But Thapa said the effects of these drugs are short-lasting and their use may lead to faster progression of osteoarthritis.

Dr. Michael Baria, an associate professor of physical medicine and rehabilitation at The Ohio State Wexner Medical Center in Columbus, Ohio, said steroid injections can also have a negative effect on people with other medical problems, such as diabetes or low bone density, so they aren’t the best option for these patients.

Instead, he said viscosupplementation — in which a gel-like fluid is injected into the knee joint — is a good alternative. “It can be effective and tends to work a bit longer than steroids,” he said.

Another treatment that may show some benefit is platelet-rich plasma injections. However, Baria cautions that this is not yet approved by the U.S. Food and Drug Administration.

While current treatment options provide some relief from osteoarthritis symptoms, they don’t address the underlying damage to the joint.

“The biggest thing that we don’t have right now is something that clearly modifies the disease,” said Baria. “We don’t have anything that slows down the arthritic progression.”

Thapa said having a drug that not only controls the inflammation that occurs with osteoarthritis, but also helps regenerate the damaged cartilage would be a big step forward.

“It could help millions of people who have the disabling symptoms of osteoarthritis,” he said, “but it would also save a lot in healthcare costs.”