A disease that dries out everything
Imagine your eyes feeling like sandpaper every time you blink. Your mouth too dry to swallow food. Not for a day — but for the rest of your life.
That's the daily reality for people with primary Sjögren's disease (SjD), a chronic autoimmune condition that affects an estimated 3 to 4 million people in the United States alone — the vast majority of them women.
What's going wrong inside the body
In Sjögren's disease, the immune system turns against the glands that produce saliva and tears. Immune cells flood in, multiply, and slowly destroy the glandular tissue. Over time, the glands stop working.
But the immune system is not a single thing. It's more like a complex government with many agencies — some pushing for more action, some calling for restraint. In Sjögren's, one of the "restraint" agencies is badly outnumbered.
The calming cells that go missing
Regulatory T cells — often called Tregs — are the peacekeepers of the immune system. Their job is to quiet overactive immune responses before they cause collateral damage.
In people with Sjögren's disease, Tregs are not doing their job effectively. Meanwhile, another group called Th17 cells push inflammation. The balance tips toward destruction, and the glands pay the price.
Think of it like a thermostat stuck on high, with the cooling mechanism broken. The immune response never gets the signal to dial back down.
Three drugs that could fix the thermostat
A review published in Frontiers in Medicine looked at recent research identifying ways to restore Treg function in Sjögren's patients. Three interventions stood out.
Mesenchymal stem cells (MSCs) — a type of stem cell found in bone marrow and other tissues — appear to promote Treg growth and improve their ability to suppress the overactive immune response. Fenofibrate, a drug already used to lower cholesterol, and metformin, the widely prescribed diabetes medication, both showed similar effects in early studies.
All three approaches nudged the immune system back toward balance — increasing Tregs, reducing Th17 activity, and as a result, allowing the saliva and tear glands to function better.
What the research actually covered
This was a review article — a synthesis of existing studies on Treg biology in Sjögren's disease. Researchers examined how Tregs regulate the immune environment inside the affected glands, why they fail in SjD, and which interventions have shown the most promise in restoring their function.
The evidence suggests that restoring the Th17/Treg ratio — bringing the two immune forces back into balance — leads to measurable improvements. In studies where Treg function was restored, inflammatory markers dropped. More strikingly, researchers found significantly increased saliva and tear secretion in treated subjects, suggesting that some gland function can be partially recovered if the immune environment improves.
These findings come from lab studies and early-phase research — they have not yet been confirmed in large human clinical trials.
Why familiar drugs matter
The fact that fenofibrate and metformin are already approved, widely used, and well-understood drugs is significant. Repurposing existing medications skips many of the early safety hurdles that entirely new drugs face. If these effects hold up in clinical trials, patients with Sjögren's disease could potentially benefit from treatments that are already accessible and relatively affordable.
If you have Sjögren's disease, talk to your rheumatologist before trying any of these medications for this purpose. Neither fenofibrate nor metformin is currently approved to treat Sjögren's, and taking them without medical supervision carries risks.
Watch for clinical trial announcements related to Treg-targeted therapy in autoimmune conditions — this is an active and growing area of research.
The limits of this research
Because this is a review rather than a new clinical trial, the conclusions are only as strong as the individual studies behind them. Many of those studies were conducted in animal models or small human cohorts. Real-world outcomes in diverse patient populations may vary.
What comes next
The researchers hope this review will serve as a foundation for designing new clinical trials that specifically target Treg pathways in Sjögren's disease. If trials using MSC therapy, fenofibrate, or metformin show consistent results in larger human studies, regulatory approval for a Treg-focused treatment strategy could move significantly closer within the next decade.