Potential disease-modifying drug for osteoarthritis identified
From left, Anna Spagnoli, M.D., and Tieshi Li, Ph.D.
The research is detailed in the May 8 issue of "Science Translational Medicine."
The collaborative research project involved scientists at four U.S. institutions -- UNMC, Rush University Medical Center, University of North Carolina at Chapel Hill and Duke University -- as well as Tongji Medical College in China and Gulhane Military Medical School in Turkey.
The lead author on the study is Tieshi Li, Ph.D., assistant professor, pediatrics, at UNMC. The senior author on the study is Anna Spagnoli, M.D., chair of the UNMC Department of Pediatrics and director of the Child Health Research Institute, pediatrician-in-chief and senior vice president for Children's Hospital & Medical Center.
Dr. Spagnoli joined UNMC and Children's earlier this year after working previously at Rush University Medical Center and the University of North Carolina at Chapel Hill. Dr. Li worked with Dr. Spagnoli at Rush University Medical Center and joined her team in Omaha.
Using several animal models and human samples from people with osteoarthritic joints, the researchers determined that the TGF-beta type II signaling receptor (TGFBR2) regulates joint development during fetal life as well as joint maintenance through the lifespan. It does this by modulating key components of a family of inflammatory cytokines called the IL-36 system.
Researchers discovered that if subjects lacked TGFBR2 that it led to OA and impaired movements. In aging mice that naturally develop OA and in mice with post-traumatic OA, researchers found a profound decrease in TGFBR2.
In human joints, the study found that the decrease in TGFBR2 correlated with the severity of the OA. They also found that the decrease in TGFBR2 was associated with an increase of IL-36-alpha and a decrease in its antagonist (IL-36 receptor antagonist) in humans and all four animal models studied.
These findings indicated that TGFBR2 is a potential target for treating OA. Researchers then focused on the IL-36 system as a novel and critical downstream mediator of TGFBR2 and a potential target to treat OA.
With most of the experiments performed by Dr. Li, the IL-36 receptor antagonist was injected in knee joints affected by OA -- and in the key finding of the study -- it was found that the injection improved the OA in mice and in human cartilage cells from people with OA and decreased metalloproteinases, enzymes that destroy joint cartilage.
"This is truly a significant breakthrough," Dr. Spagnoli said. "Currently, we are lacking any drugs that are capable of preventing, treating or halting the progression of OA, and the ultimate treatment is surgical joint replacement. Further studies need to be done, but we are excited by the positive response seen with the injection of the IL-36 receptor antagonist. It should provide hope to OA sufferers."