Bacteria in the gut, known as the gut microbiome, may be linked to osteoarthritis and joint pain in people who are obese, according to new research.
The findings, published in biomedicine journal JCI Insight, suggest that a prebiotic supplement may alter the obese microbiome and protect against osteoarthritis.
Scientists at the University of Rochester Medical Center (URMC) found that obese mice had more harmful bacteria in their guts compared to lean mice, and this caused inflammation throughout their bodies, leading to very rapid joint deterioration.
As part of the study, the researchers induced osteoarthritis with a meniscal tear, a common athletic injury known to cause osteoarthritis. Compared to lean mice, osteoarthritis progressed much more quickly in the obese mice, with nearly all of their cartilage disappearing within 12 weeks of the tear.
While a common prebiotic supplement did not help the mice to lose weight, it completely reversed the other symptoms and their joints were healthier.
According to the researchers, the effects of obesity on gut bacteria, inflammation and osteoarthritis were prevented when the high-fat diet of obese mice was supplemented with a prebiotic known as oligofructose. The knee cartilage of obese mice who ate the oligofructose supplement was indistinguishable from that of the lean mice.
“Prebiotics like oligofructose cannot be digested by rodents or humans, but they are welcome treats for certain types of beneficial gut bacteria, like Bifidobacteria,” URMC explained. “Colonies of those bacteria chowed down and grew, taking over the guts of obese mice and crowding out bad actors, like pro-inflammatory bacteria. This, in turn, decreased systemic inflammation and slowed cartilage breakdown in the mice’s osteoarthritic knees.”
Just reducing inflammation was enough to protect the joint cartilage from degeneration, supporting the idea that inflammation — rather than biomechanical forces — drives osteoarthritis and joint degeneration.
However, the scientists cautioned that although there are parallels between mouse and human microbiomes, the bacteria that protects mice from obesity-related osteoarthritis may differ from the bacteria that could help humans.
They hope to conduct further research comparing people who have obesity-related osteoarthritis to those who don’t, in order to further identify the connections between gut microbes and joint health. They also hope to test whether prebiotic or probiotic supplements that shape the gut microbiome can have similar effects in humans suffering from osteoarthritis as they did in mice.
“There are no treatments that can slow progression of osteoarthritis — and definitely nothing reverses it,” noted first author Eric Schott, postdoctoral fellow at URMC. “But this study sets the stage to develop therapies that target the microbiome and actually treat the disease.”