Juvenile Arthritis: The Hidden Battle in Growing Bodies

Imagine you’re a kid with pain in your fingers and toes. But it’s different from the usual scrapes and bruises from horseplay—it’s an aching, dull pain, rather than a sharp, throbbing pain. You tell your parents, and they take you to a doctor. Eventually, you get an X-ray and a blood test, but these don’t reveal anything out of the ordinary. So, your doctor orders an MRI, and it turns out you have juvenile arthritis.

Juvenile idiopathic arthritis (JIA) is classified as arthritis within anyone 16 years of age or younger. This is a different kind of arthritis than our grandparents might have. JIA spreads from joint to joint, and if it isn’t treated quickly, mobility issues quickly arise. When caught, exercise and physical therapy will never be enough to treat JIA. Medicine will always be necessary until the patient is in remission. Out of 72.5 million children in America, 300,000 have JIA, according to the Arthritis National Research Foundation. 

Now, those are the basic facts and statistics, but how does JIA affect a child’s body? Juvenile arthritis is an autoimmune disease. A common belief is that the disease is caused by a very strong immune system. And while this may be true for other autoimmune diseases, it’s only partially true for JIA.

The immune system is made up of white blood cells, an example of which are macrophages. There are two types of macrophages: M1 and M2. M1 macrophages are pro-inflammatory and fight against viral infections and pathogens; M2 macrophages are anti-inflammatory and are involved in healing.

M1 macrophages produce excess proteins called cytokines. Cytokines do have a job–they are signaling proteins, chemical messengers that allow cells to interact with each other, that help control inflammation. One cytokine that M1 macrophages produce is TNF-alpha, which plays a crucial role in inflammation and immune responses.

Cytokines trigger inflammation in the body. TNF-alpha, specifically, is a chemical that helps protect us when we are sick or injured, and is one of the signals that tells our immune system to fight off infections. But, with all this immune response comes inflammation. Inflammation causes swelling and pain and it’s our body’s way of healing. While TNF-alpha is helpful, too much of it can be harmful and can hurt healthy tissue and organs.

In children with juvenile arthritis, TNF-alpha mistakenly signals a threat in the joints. It activates the immune system, which ends up attacking the joints despite there being no real danger. The resulting inflammation makes the joints stiff and swollen. 

When JIA is caught early, doctors may recommend an increase in exercise or physical therapy as treatment. Doctors might also prescribe nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce swelling and pain. Although NSAIDs are one of the most common forms of medication to treat JIA, many doctors now reach for disease-modifying antirheumatic drugs (DMARDs), such as Methotrexate or the biologic Humira. These drugs slow down the disease so it doesn’t damage joints as much. Methotrexate, which can be administered orally or by injection, inhibits TNF-alpha; Humira, which is administered by injection, blocks TNF-alpha. These treatments, however, have various side effects including weakening the immune system so illnesses may be caught more easily, injuries can take longer to heal, and viruses may last longer than usual. 

Dr. Karen Onel, a pediatric rheumatologist at Weill Cornell Medicine in New York, notes a time when DMARDs and other medications weren’t a thing. Only steroids were available for children. Steroid drops were not always effective and could cause horrible side effects, including blindness. Many rheumatologists were relieved when DMARDs like Methotrexate and Humira were introduced. While these medications are effective at stopping the progression of the disease, they are not a lifelong fix. Children with JIA  might be taken off the medication further down the line, or maybe put back on. 

Although treatments can help to manage symptoms and prevent long-term damage to joints, and remission is even possible, there is no permanent cure for JIA. It is hard to study due to how few people have it. Every day, rheumatologists are working to advance the treatments for juvenile arthritis, and hope to find a more permanent cure.