When Stress Triggers Inflammation: How Arthritis Can Flare Up Again

Arthritis may seem under control, but stress can reignite inflammation. How? A study published in Science Advances has identified a potential link, in mice, between the nervous system, brown fat, and joint cells. This discovery helps explain how stress can trigger a new inflammatory response and points toward future treatment strategies for rheumatoid arthritis.

Psychological stress can affect much more than just emotional well-being. In individuals with rheumatoid arthritis, an autoimmune disease in which the immune system attacks the body’s own joint tissues, periods of stress are often associated with a worsening of symptoms. But how does this happen, especially when the disease appears to be under control?

A study published in the journal Science Advances investigated the biological mechanisms that may link stress to the reactivation of inflammation.

To explore this relationship, researchers studied mice with arthritis whose inflammation was in remission, meaning it was temporarily under control. The animals were subjected to "restraint stress," a situation in which their movement was restricted inside a tube.

The scientists then observed whether joint inflammation increased and identified the biological signals involved in this process. The results showed that stress exacerbated the inflammation, providing insight into how the body’s response to a stressful situation can reactivate existing inflammatory mechanisms.

The team identified a potential link between the nervous system and the immune system: brown fat, a type of adipose tissue known primarily for generating heat and helping to regulate body temperature.

Under stress, the sympathetic nervous system, which prepares the body to react to challenging situations, stimulated this tissue to release a substance called interleukin-6. This molecule plays a role in cell-to-cell communication and can promote inflammation under certain circumstances.

In this experimental model, it activated cells found in the lining of the joints, known as synovial fibroblasts, which then began producing another substance: CXCL1. This substance acts as a chemical signal that attracts neutrophils, immune defense cells capable of contributing to inflammation.

The researchers also investigated whether it might be possible to interrupt this sequence. To do so, they blocked the activity of a receptor called the beta-3 adrenergic receptor, which is involved in the brown fat’s response to signals from the sympathetic nervous system. This blockade significantly reduced the stress-induced worsening of arthritis in the animals.

Furthermore, the scientists analyzed data from individuals with rheumatoid arthritis and observed that the relationship between psychological stress and disease activity varied according to a genetic variant linked to this receptor. In participants carrying a version that reduces the receptor's function, the same positive association between stress and disease activity was not observed. While this finding in humans reinforces the relevance of the hypothesis, it does not, by itself, prove that the receptor is responsible for this difference.

The discovery reveals a potential pathway through which stress can reactivate inflammation during arthritis remission. However, experiments in animals do not necessarily mean that the same mechanism accounts for every episode of the disease in humans.

These findings pave the way for investigating treatments that could disrupt this communication between the nervous system, brown fat, and joint cells, without broadly compromising the body’s defenses. In the future, understanding this connection could help in developing complementary strategies for managing rheumatoid arthritis, though further studies are still required to evaluate their safety and clinical efficacy.

READ MORE:

Fibroblast-like synoviocytes exacerbate autoimmune arthritis upon psychological stress in an IL-6-dependent manner 

Jun Tamura, Shigeru Tanaka, Keishi Etori, Daisuke Hashiba, Shuhei Kameda, Atsuko Tomikawa, Ryo Kikuchi, Tatsuro Takahashi, Aiko Saku, Hirotoshi Kawashima, Junichi Nakamura, Seiji Ohtori, Shin-Ichiro Kagami, Koichi Hirose, and Hiroshi Nakajima

Science Advances, VOL. 12, NO. 42. Oct 16, 2026

DOI: 10.1126/sciadv.aec9257

Abstract: 

Psychological stress affects the immune system and exacerbates autoimmune diseases such as rheumatoid arthritis (RA), but the mechanisms underlying tissue inflammation during remission remain unclear. Here, we show that tube restraint stress exacerbates joint inflammation in a murine arthritis model during remission. This exacerbation required interleukin-6 (IL-6) produced by brown adipose tissue (BAT) following sympathetic activation. Fibroblast-like synoviocytes expressing the IL-6 receptor subunit gp130 were critical mediators, as IL-6 stimulated these cells to produce the neutrophil chemoattractant CXCL1. Pharmacological blockade of the β3-adrenergic receptor significantly attenuated stress-induced arthritis flares. In patients with RA, carriers of the hypofunctional Trp64Arg variant of ADRB3 showed no positive correlation between psychological stress and disease activity, whereas noncarriers did. These findings identify a BAT–IL-6–fibroblast axis that reactivates inflammatory memory in arthritis and suggest that targeting stress-responsive pathways may provide a complementary therapeutic strategy alongside current RA treatments without broadly suppressing systemic immunity.