What Causes Rheumatoid Arthritis?
With contributions from Lana.
Rheumatoid arthritis (or RA), is like any autoimmune disease, in that your body mistakes healthy tissue for invader cells, treats it like something it needs to fight off, and attacks it. With RA, this healthy tissue is your synovium, or fluid and membranes around your joint.
The inflammation that occurs from the RA will make the synovium thicker, which causes RA joint deformities and other problems in which the joint is deformed or destroyed. When you have RA, the thickening of the synovium can also damage the support system around your joints, such as the tendons and ligaments, further weakening the joints.
At this point in time, while there is research going on to try and identify the cause of the disease, there is nothing concrete. There are many theories that abound about what causes RA, but there is nothing that scientists can be absolutely sure of.
The Role of Genetics
One theory is that genes and genetics are a factor. It can be difficult to say if this means RA specifically is passed down, or an umbrella of autoimmune diseases are passed from one generation to another, as very often autoimmune diseases in general run in families.
There is also some evidence that RA itself runs in families, but this hasn’t been easy to pinpoint for a variety of reasons. Namely, because RA can be difficult to diagnose, there may be people who don’t know they have the disease or have a propensity for it. Likewise, because diagnosis is difficult, it isn’t a disease that was widely diagnosed or treated prior to the last 20 to 30 years or so, making it even more difficult to observe genetic patterns.
There are also some theories to suggest that while genes do play a part, they are not the be all and end all of having the disease. Instead, some doctors believe that genes make a person susceptible to the disease, but that they can only get it due to outside factors. These factors can mean being exposed to a certain infectious disease, or even smoking cigarettes.
The National Rheumatoid Arthritis Society in the UK says there’s no one gene that causes RA, but “more than 10 genes have now been identified and work is currently in progress to establish exactly what these genes do and how they interact with one another and environmental factors.”
The society also states that there isn’t one specific environmental factor that causes RA on its own.
“We can think of RA as being like a plant. Firstly it needs the soil in which to grow. The soil is equivalent to the genetic factors. Then there are the seeds which have to be planted in the soil. The seeds are equivalent to the non-genetic risk factors. The richer the soil (i.e. the more genes associated with RA a person has), the fewer the quantity of seeds needed for a plant to grow.”
Microbiome is the name for bacteria that lives in the intestinal tract. Some microbiomes are good bacteria while others are not.
Researchers have identified gut bacteria that may trigger RA. A type of intestinal bacteria called Prevotella copri has been linked to the onset of RA, this according to researchers from NYU Langone Medical Center and New York University School of Medicine.
Researchers suspect periodontal disease can trigger RA. Periodontal disease is a chronic inflammation of the gums and bones that support teeth.
A 2016 study from Johns Hopkins suggests the bacteria that causes gum inflammation can start a chain of events leading to the development of RA.
Next page: six more possible contributing factors to the development of RA.