Yale Study Suggests Cause of Lyme -Related Arthritis
Excerpted from the courant.com ( Posted: 06/25/2012)
In a study that could that explain some long-term symptoms in Lyme disease patients, Yale researchers say they have found the cause of Lyme-related arthritis in mice.
The study found that dying parts of the spirochete — a corkscrew-shaped bacterium that enters the bloodstream by tick bite – find their way into the cartilage of joints. The researchers believe that the body’s immune system’s response to these protein – not the bacteria – is what causes some Lyme disease sufferers experience arthritis symptoms long after completing a course of antibiotics treatment.
The question of whether chronic symptoms of Lyme disease that last after antibiotics has long been a contentious one.
The study, led by Linda Bockenstedt, who teaches rheumatology at the Yale School of Medicine, appears today in the online Journal of Clinical Investigation.
“We’ve always speculated about the reasons patients might have persistent symptoms, where antibiotics make no difference,” she said. It’s a controversy, she said, that’s “centered between people in academia and patients and layperson’s organizations.”
“It is a controversy and we’re trying to come to a medium ground,” she said. “This provides one explanation.”
For the study, the researchers infected mice with Borrelia burgdorferi, the bacteria that causes Lyme disease. Bockenstedt said the bacteria was killed in the vast majority of the mice after a couple days of antibiotic treatment. But they also found traces of proteins from the spirochete in the joints and cartilage of the mice. And in some of the mice, she said, they found a substance commonly produced in large-scale immune system attacks. The arthritis that some human Lyme patients suffer, she said, “could potentially be caused by continued inflammation after the spirochete was killed.”
Bockenstedt said Lyme-associated arthritis occurs in about 10 percent of people who contract the disease. And of those people, only about 10 percent have it for longer than a few months.
Dr. Eugene Shapiro, a professor of pediatrics and epidemiology at the Yale School of Medicine, said the study makes a good case for the cause of one very specific and very rare symptom of the disease, but doesn’t get at the heart of the debate.
“We’ve known that a very small number of patients go on to have objective findings of arthritis,” he said. “We’re talking about painful, inflamed joints — it’s extraordinarily rare. This is not what the controversy is about.”