Mast cells

Stanford University School of Medicine scientists have definitively linked mast cells; a class of cells belonging to the immune system, to the development of osteoarthritis, one of the world’s most common causes of pain and immobility. Osteoarthritis, by far the most frequently occurring variety of arthritis; is by cartilage breakdown and inflammation in joints, which can further aggravated by excess bone growths called osteophytes.

Some 30 million Americans have symptomatic osteoarthritis. By the time you are 60, your chances of exhibiting osteoarthritis symptoms exceed 30 %. By age 80 or 90, your risk has risen to nearly 100 percent. Osteoarthritis has traditionally thought to an inevitable result of wear and tear: the breakdown of cartilage over many years; ultimately resulting in grinding, bone-on-bone contact, and degeneration in the affected joints.

The immune system

But the new study shows the essential involvement of the immune system in the genesis of osteoarthritis; while prying open a window through which researchers can see a way to designing drugs to prevent it. At present, there are no drugs that can prevent, slow or cure it. Even though the vast majority of us will develop osteoarthritis at some point in our lives, they do not have any disease-slowing therapies.

The chances of actually reversing damage to joints are slim. Today’s treatments for the osteoarthritis-induced pain and mobility consist of painkillers like ibuprofen; naproxen and acetaminophen; walkers and canes; and knee or hip replacements. Mast cells are best as the culprits that produce the histamines and other molecules responsible for allergic symptoms; ranging from the itch of eczema to the mucous explosions of hay fever to the throat constriction of asthma or food-triggered anaphylaxis.

But mast cells also produce a degradative protein, tryptase, that can rip up collagens and other molecules that form the cartilage in joints. Mast cells usually reside quietly within tissues throughout the body. But when they become activated, they secrete granules containing histamines; tryptase, and other inflammatory substances. The classic trigger for that activation is the binding of a form of circulating antibody, or immunoglobin, called IgE to receptors abounding on mast cells.

The mast cells and histamines

The evolutionary purpose of IgE, mast cells and histamines is believed to be to fight off parasites; which have plagued humans and other animals throughout most of the evolution but have become relatively rare in humans in recent decades; at least in industrialized countries. While mast cells have been found lurking in joints of people with and without symptomatic arthritis; until now neither mast cells nor IgE has definitively identified as risk factors for osteoarthritis.

In the study, Robinson’s group used electron microscopy to show that mast cells in injured joints of humans who didn’t yet have arthritic symptoms not releasing their histamine and tryptase-laden granules; whereas mast cells residing in the joints of humans with arthritic symptoms.

Several types of genetically altered lab mice whose mast cells deficient or absent highly resistant to the development of osteoarthritic features including joint inflammation, osteophyte development; joint breakdown after undergoing an experimental procedure to induce these symptoms, the researchers found. A major goal in my career is to find a way to stop people from getting osteoarthritis. adding that he wants to identify drugs with excellent safety profiles and the ability to prevent; rather than treat, osteoarthritis. “These drugs will have to be safe enough for large numbers of people to take for decades without problems.”