Rheumatoid arthritis is a chronic arthritic condition of the joints. Like osteoarthritis, rheumatoid arthritis causes joint pain, swelling and stiffness, but these conditions are very different. While osteoarthritis is considered a disease of wear and tear, rheumatoid arthritis is an autoimmune disease. Which means that instead of protecting the body against an invader, the immune system turns on it’s own body tissues, in this case the joints, especially of the hands, feet and wrists.
In developed countries such as the UK, around 1% of the population may have rheumatoid arthritis. It is a condition that tends to run in families, and it affects around three times as many women as men.
Understanding the underlying causes and triggers for a condition like rheumatoid arthritis can help us understand how we might be able to prevent its occurrence or progression. So this is an important part of the research into rheumatoid arthritis and other autoimmune diseases. Scientists searching for the cause of rheumatoid arthritis believe that bacteria play an important part. In particular, at least for rheumatoid arthritis, certain types of Proteus bacteria that can cause urinary tract infections have been implicated.
The majority of urinary tract infections are caused by the bacteria Escherichia coli (E. coli). These bacteria tend to colonise the bladder and cause cystitis. In contrast, Proteus bacteria such as Proteus mirabilis invade the upper parts of the urinary tract, such as the ureters, the tubes leading from the kidney to the bladder, as well as the kidney itself. Proteus bacteria cause around 10 to 15% of urinary tract infections, which may be chronic, low grade infections without obvious symptoms.
Proteus and some other disease causing bacteria, but not E. coli, produce an enzyme called urease that helps them invade, colonise and spread. Proteus urease is toxic to the body’s tissues and is believed to have a role in the development of rheumatoid arthritis. It also encourages formation of urinary stones, and helps the Proteus bacteria to hide from the immune system and from antibiotic medication.
When the immune system detects an infection it creates antibodies to destroy foreign material such as bacteria. Similarly, in long lasting, chronic conditions such as urinary tract infections caused by Proteus bacteria, the immune system will produce antibodies to urease. What scientists now know is that in some people, antibodies that destroy Proteus urease also destroy cartilage.
In a process called molecular mimicry, antibodies that should be destroying bacteria or in this case Proteus urease, will also attack the lining membranes and cartilage of the joints. To these antibodies, the protein sequences of the membranes and collagen look a lot like those of their target. And, the immune system instead of protecting the body starts an inflammatory process that can eventually destroy the joints. Especially if the Proteus infections are recurrent or chronic, leading to chronic inflammation of the joints, with joint damage and deformity.
We know that women are more at risk for urinary tract infections than men. The researchers suggest that this along with their findings also explains why more women than men suffer from rheumatoid arthritis.
Interestingly, many herbs that were used traditionally for symptoms of urinary tract infections are also traditional remedies for arthritis or rheumatic conditions. Take juniper (Juniperus communis) for example, with a reputation for notable anti-inflammatory and anti-rheumatic effects, as well as antibacterial and antimicrobial activity. In fact, in studies Juniper has been found effective against Proteus mirabilis in vitro. This could perhaps explain why complementary and alternative medicine therapies are popular in people with rheumatoid arthritis worldwide.