Can a Junk Food Diet Cause Osteoarthritis?

By Steve Weakley

Does what’s in your gut influence the pain in your knees? New research on mice at the University of Rochester Medical School suggests that it might, but the results are far from conclusive.

Researchers fed one group of laboratory mice a high fat diet that included red meat and milkshakes, and another group of mice a healthier low-fat diet. Both groups of mice had their knees surgically damaged to mimic the effects of osteoarthritis -- “wear and tear” arthritis that is often associated with age, obesity or injury.

Twelve weeks of the high fat diet made the mice obese and diabetic and led to more seriously damaged joints. It also created an imbalance of harmful bacteria in their digestive tracts. 

One group of the fat mice were then given a supplement containing the prebiotic fiber oligofructose (also available as an over-the-counter probiotic).  The researchers said the supplement did not cause the mice to lose weight, but it did greatly improve their blood sugar levels and the balance of healthy bacteria in their gut.  More importantly, the study concludes, the mice that were given the supplement also had healthier joints than the control group.

The University of Rochester study concluded that prebiotics and the correction of gut bacteria might help protect against osteoarthritis caused by obesity. And one of the researchers, Dr. Robert Mooney, told Forbes that the study suggests osteoarthritis may be accelerated or even caused by inflammation.

"That reinforces the idea that osteoarthritis is another secondary complication of obesity--just like diabetes, heart disease, and stroke, which all have inflammation as part of their cause," said Mooney. "Perhaps, they all share a similar root, and the microbiome (digestive bacteria) might be that common root."

However a critique by Britain’s National Health Service (NHS) said that conclusion might be premature.

“It's presumptuous to conclude that an imbalance of gut bacteria could be directly linked to risk of osteoarthritis in humans from the results of a study in mice with artificially induced knee damage. As such, there's no compelling evidence that prebiotics would prevent or reverse osteoarthritis,” the NHS said.

“Aiming for a healthy weight through a good diet combined with physical activity is a better strategy for reducing the risk of osteoarthritis (as well as many other long-term conditions) than taking prebiotics to try to combat the effects of a poor diet. “

Osteoarthritis is a joint disorder that leads to progressive joint damage. It can affect any joint in the body but is most commonly felt in weight bearing joints such as the knees and hips. Nearly 40 percent of Americans over the age of 45 have some degree of knee osteoarthritis.

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Previous studies have also found a link between a high fat diet and osteoarthritis.  Australian researchers reported last year that a diet rich in animal fats, butter and palm oil weakens cartilage and produces osteoarthritis-like changes in the knee.

"We also found changes in the bone under the cartilage on a diet rich in saturated fat," said Professor Yin Xiao of Queensland University of Technology’s Institute of Health and Biomedical Innovation. "Our findings suggest that it's not wear and tear but diet that has a lot to do with the onset of osteoarthritis.”

The University of Rochester researchers hope to include humans in future studies on the effects of diet on osteoarthritis.

Bacteria Studies Give New Hope to IBD Patients

By Pat Anson, Editor

A new study is adding to the growing body of evidence linking gut bacteria to autoimmune and gastrointestinal diseases – research that could lead to new and more effective treatments.

Researchers at the University of Utah used animal studies to show that a certain type of yeast can aggravate symptoms of Inflammatory Bowel Disease (IBD). Their findings, published in the journal Science Translational Medicine, also suggest that allopurinol, a generic drug already on the market, could offer some relief.

IBD is an autoimmune disease characterized by chronic inflammation of the gastrointestinal tract, causing diarrhea, pain, fatigue and weight loss.

For years doctors have used the presence of yeast antibodies, specifically antibodies in the yeast Saccharomyces cerevisiae, to differentiate between Crohn’s disease and ulcerative colitis, two variations of IBD. But it was unclear the role that yeast played in relation to IBD.

“To me this was a huge hole in our understanding of the role of yeast in IBD and our health,” said June Round, PhD, an associate professor in pathology at the University of Utah School of Medicine.

Round and her research team studied two types of yeast that are common in healthy people and IBD patients. Saccharomyces cerevisiae, also called Baker’s yeast, is a prominent organism in the environment and in our food. Rhodotorula aurantiaca is also commonly found in the environment, as well as milk and fruit juice.

Scientists gave each type of yeast to laboratory mice that had been treated with chemicals to induce IBD-like symptoms. The symptoms worsened in mice fed S. cerevisiae, but not in those fed R aurantiaca.

“The mice fed S. cerevisiae experienced significant weight loss, diarrhea, bloody stool, just like a person with IBD,” said Tyson Chiaro, graduate student in Round’s lab.

Further study revealed that the mice fed S. cerevisiae had a higher concentration of nitrogen-rich compounds, called purines, than the mice fed R. aurantiaca. Unlike other yeasts, S. cerevisiae cannot break down purines that accumulate in the intestinal tract and produce uric acid. Uric acid exacerbates inflammation, which may worsen IBD symptoms.

When the mice were treated with allopurinol, a medication used to block the production of uric acid in gout patients, the drug significantly reduced their intestinal inflammation.

“Our work suggests that if we can block the mechanism leading to the production of uric acid, perhaps with allopurinol, IBD patients with a high concentration of S. cerevisiae antibodies may have a new treatment option to reduce inflammation, which could allow the intestine time to heal,” said Round.

E. Coli linked to IBD and spondyloarthritis

Another recent study has helped researchers identify E. coli bacteria found in people with Crohn's disease that can trigger inflammation associated with spondyloarthritis, a painful arthritic condition that affects the spine and joints.

Researchers used fecal samples from IBD patients to identify bacteria in the gut that were coated with antibodies called immunoglobulin-A (IgA) that fight infection. Using flow cytometry, in which fluorescent probes are used to detect IgA-coated bacteria, the researchers found the E. coli bacteria were abundant in fecal samples from patients with both Crohn's disease and spondyloarthritis.

"Our findings may allow us to develop diagnostic tools to stratify Crohn's patients with spondyloarthritis symptoms as well as patients at risk," said senior author Dr. Randy Longman, an assistant professor of medicine and director of the Jill Roberts Institute Longman Lab at Weill Cornell Medicine.

Longman and his research team found that patients with Crohn's disease and spondyloarthritis had high levels of Th17 cells, which help fight inflammation. The finding may help physicians select therapies that target inflammation in both the bowels and the joints.

"We knew there was smoke but we didn't know where the fire was," said Dr. Kenneth Simpson, a professor of small animal medicine at Cornell's College of Veterinary Medicine. "If we can block the ability of bacteria to induce inflammation, we may be able to kick Crohn's disease and spondyloarthritis into remission."

The study findings are also published in Science Translational Medicine

Can Gum Disease Cause Rheumatoid Arthritis?

By Pat Anson, Editor

Scientists have long suspected that pathogens and bacterial infections may play a role in the development of autoimmune diseases such as rheumatoid arthritis (RA). Now there is evidence that a bacterium associated with chronic gum infections may trigger an inflammatory response characteristic of RA, a discovery that could lead to new ways to treat and prevent the disease.

"This research may be the closest we've come to uncovering the root cause of RA," said Maximilian Konig, MD, a former Johns Hopkins University School of Medicine fellow now at Massachusetts General Hospital.

Rheumatoid arthritis is a chronic autoimmune disease in which the body’s own defenses attack joint tissues, causing pain, inflammation and bone erosion. About 1.5 million Americans and one percent of adults worldwide suffer from RA. There is no cure for the disease and treatments only focus on slowing its progression.

In a study of nearly 200 RA patients, Konig and his colleagues found that nearly half had antibodies against Aggregatibacter actinomycetemcomitans in their blood.  

The level of infection with the bacteria was similar in patients with periodontal (gum) disease, but quite different in healthy patients, only 11 percent of whom tested positive for A. actinomycetemcomitans.

An infection with A. actinomycetemcomitans appears to induce the production of citrullinated proteins, which are suspected of activating the immune system and driving the cascade of events leading to RA.

"This is like putting together the last few pieces of a complicated jigsaw puzzle that has been worked on for many years," says Felipe Andrade, MD, a senior study investigator and associate professor of Medicine at the Johns Hopkins University School of Medicine.

Andrade cautions that over half of the study participants with RA had no evidence of an infection with A. actinomycetemcomitans, which may indicate that other bacteria in the gut, lung or elsewhere could be involved. He says more research is needed to determine if there is a cause and effect relationship between bacteria and RA.

"If we know more about the evolution of both combined, perhaps we could prevent rather than just intervene," he said.

The Johns Hopkins study is published in the journal Science Translational Medicine.

Scientists have observed an association between periodontal disease and RA since the early 1900s, and have suspected that both diseases may be triggered by a common factor. In the last decade, studies have focused on a bacterium known as Porphyromonas gingivalis, which is found in patients with gum disease. However, research has so far failed to corroborate such a link.

Researchers in the current study found inflammation in the joints of RA patients that was similar to the inflamed gums of patients with periodontal disease, an inflammatory process known as hyper-citrullination.

Citrullination occurs naturally in everyone as a way to regulate the function of proteins. But in people with RA, the process becomes hyperactive, resulting in the abnormal accumulation of citrullinated proteins. This drives the production of antibodies against proteins that create inflammation and attack a person's own tissues, the hallmark of RA.