Researchers discovered that two painful inflammatory conditions affecting older adults—polymyalgia rheumatica and giant cell arteritis—have nearly identical immune system problems in the affected tissues. By examining tissue samples from patients with each disease, scientists found that the same type of immune cells (called macrophages) and their chemical signals were present in both conditions. This discovery suggests doctors might be able to use the same treatments for both diseases, which could help millions of people suffering from these painful conditions. The findings support the idea that these two diseases are actually different versions of the same underlying problem.

The Quick Take

  • What they studied: Whether two painful inflammatory diseases affecting older adults have the same immune system problems in their affected tissues
  • Who participated: 11 patients with polymyalgia rheumatica (muscle pain and stiffness) and 14 patients with giant cell arteritis (inflammation of blood vessels), all with active disease
  • Key finding: Both diseases showed nearly identical patterns of immune cells and chemical signals in their affected tissues, with only one minor difference in a specific marker called folate receptor beta
  • What it means for you: If you have either of these conditions, treatments designed for one disease may work for the other, potentially giving doctors more options. However, this is early-stage research, so talk with your doctor before expecting treatment changes

The Research Details

Scientists collected tiny tissue samples from patients with each disease. From polymyalgia rheumatica patients, they took samples from the shoulder area (subacromial bursa). From giant cell arteritis patients, they took samples from blood vessels in the temple. They then used special staining techniques to identify and count specific immune cells and chemical signals in these tissues. This allowed them to compare what was happening in each disease side-by-side.

The researchers looked for six different immune cell markers and six different chemical signals that immune cells produce. They counted how many cells showed each marker and measured how much of each chemical signal was present. This gave them a detailed picture of the immune system activity in each disease.

This approach is valuable because it looks directly at what’s happening in the actual diseased tissue, rather than just looking at blood samples. This gives a more accurate picture of what’s really going on in the body where the disease is causing damage.

Understanding that two diseases have the same root cause is important because it opens the door to shared treatments. If doctors know the same immune system problem drives both diseases, they can develop medicines that target that shared problem. This could mean fewer different medications to develop and test, and faster access to treatments for patients.

This study is a direct tissue comparison, which is stronger than just looking at blood tests. However, the sample size is relatively small (25 patients total), so the findings need to be confirmed in larger studies. The study was well-designed with clear methods for identifying and counting immune cells. The main limitation is that this is a snapshot in time—it doesn’t show how these patterns change over time or with treatment.

What the Results Show

The researchers found that both diseases had the same immune cells present in their affected tissues. Specifically, they found six different types of immune cell markers and six different chemical signals in both polymyalgia rheumatica and giant cell arteritis tissues. The amounts of these markers and signals were remarkably similar between the two diseases.

This means that at the microscopic level, the immune system is behaving almost identically in both conditions. The same types of immune cells are being activated, and they’re producing the same chemical messages. This is strong evidence that these two diseases are fundamentally the same problem, just affecting different parts of the body.

There was one exception: a marker called folate receptor beta was slightly more abundant in giant cell arteritis samples than in polymyalgia rheumatica samples. This small difference might explain why the diseases affect different tissues, but it doesn’t change the overall picture that they’re very similar.

The study confirmed that all the immune markers they looked for were present in both diseases, with no markers completely absent from either condition. This consistency strengthens the conclusion that these are related diseases. The chemical signals the researchers measured (GM-CSF, IL-6, IL-23, IFN-γ, M-CSF, and TNF-α) are all known to cause inflammation and tissue damage, which explains why both diseases cause pain and swelling.

Previous research suggested these two diseases might be related, but this is one of the first studies to directly compare the immune profiles in actual tissue samples from both conditions. Earlier studies looked at blood samples or focused on only one disease at a time. This research provides stronger evidence for what scientists have suspected—that polymyalgia rheumatica and giant cell arteritis are different expressions of the same underlying immune problem.

The study included only 25 patients total, which is a small number. Larger studies with more patients would make the findings more reliable. The study only looked at tissue samples at one point in time, so it doesn’t show how the immune patterns change as the disease progresses or responds to treatment. The study didn’t include healthy control samples for comparison, though the researchers knew what normal tissue looks like from previous research. Finally, this is a descriptive study that identifies similarities but doesn’t prove that treating one disease will definitely work for the other.

The Bottom Line

If you have polymyalgia rheumatica or giant cell arteritis, this research suggests that treatments being developed for one disease may eventually help the other. However, this is early-stage research, so don’t expect immediate changes to your treatment plan. Continue following your doctor’s current recommendations. This research may influence future treatment options over the next few years as pharmaceutical companies develop new medicines targeting the shared immune pathways. Confidence level: Moderate—the findings are solid but need confirmation in larger studies.

This research is most relevant to people over 50 with polymyalgia rheumatica or giant cell arteritis, as these are diseases of older adults. It’s also important for rheumatologists and other doctors treating these conditions. People with family histories of these diseases may find this information helpful for understanding their risk. This research is less immediately relevant to younger people or those without these specific conditions.

Don’t expect changes to your treatment immediately. This research needs to be followed by larger studies and then clinical trials testing new treatments. Realistically, it may take 3-5 years before new treatment options based on these findings become available to patients. In the meantime, current treatments remain the best option.

Want to Apply This Research?

  • Track your daily pain levels (0-10 scale) and which joints or areas hurt most. Note any new symptoms like fever, vision changes, or severe headaches. Record this weekly to show your doctor how your condition is changing over time.
  • Set a reminder to take your prescribed medications at the same time each day. Use the app to log when you take them and note any side effects. This helps you and your doctor see if your current treatment is working well.
  • Create a monthly summary of your symptoms to discuss with your doctor. Track patterns like whether certain activities make pain worse, how your energy levels change, and whether your symptoms are improving, staying the same, or getting worse. This information helps your doctor decide if your current treatment is effective.

This research is preliminary and describes similarities between two diseases at the cellular level. It does not establish that treatments for one disease will definitely work for the other. Do not change your current treatment plan based on this information. Always consult with your rheumatologist or primary care doctor before making any changes to your medications or treatment approach. This article is for educational purposes only and should not be considered medical advice. If you have polymyalgia rheumatica or giant cell arteritis, continue following your doctor’s recommendations while staying informed about emerging research.