Researchers at Scripps Research have created a breakthrough class of drugs that could transform how doctors treat autoimmune diseases by reducing dangerous inflammation while keeping your immune system strong enough to fight real infections. The compounds, called ENDOtollins, work by blocking a specific molecular interaction inside immune cells, offering a far more precise approach than current medications that broadly suppress the entire immune system .

What Makes This Approach Different From Current Autoimmune Treatments?

Today's autoimmune disease medications like hydroxychloroquine work by broadly blocking endosomes, which are compartments inside cells where immune responses get triggered. While these drugs are effective, they come with significant side effects. Many patients experience gastrointestinal problems, and some develop vision damage serious enough to stop taking the medication altogether .

The new ENDOtollin approach targets a very specific problem: two proteins called Munc13-4 and syntaxin 7 that must bind together for immune sensors called Toll-like receptors (TLRs) to activate inside endosomes. In autoimmune diseases, these TLRs become overactive and start detecting the body's own DNA and RNA, triggering chronic inflammation even when there's no real threat .

"A key component of our approach is to begin by understanding the biological mechanisms at play. By accomplishing this first, we can more easily target the pathway driving inflammation without affecting other important processes," said Sergio D. Catz.

Sergio D. Catz, Professor at Scripps Research

Because the protein Munc13-4 is found mainly in immune cells, ENDOtollins can calm inflammation in a highly targeted way without broadly suppressing the immune system. This selectivity is crucial: in animal studies, the most potent compound, ENDO12, reduced inflammatory markers like IL-6 and interferon-gamma while preserving the animals' ability to mount a normal antiviral immune response when exposed to a virus .

How Did Researchers Develop These New Compounds?

The discovery process was rigorous and methodical. Scripps Research scientists screened approximately 32,000 compounds with support from the institute's Molecular Screening Center, looking for molecules that could specifically block the Munc13-4 and syntaxin 7 interaction without disrupting other cellular functions .

A key innovation was keeping the proteins in their natural cellular environment during screening, rather than extracting them into a test tube. This approach, developed by the research team, significantly increases the likelihood that compounds will actually work in living cells and tissues .

Steps to Understanding How ENDOtollins Work in Your Body

• Protein Binding Block: ENDOtollins interrupt the "molecular handshake" between Munc13-4 and syntaxin 7 proteins inside immune cells, preventing them from working together.
• TLR Deactivation: By blocking this interaction, the drugs prevent Toll-like receptors from becoming overactive and triggering false alarms that attack the body's own cells.
• Selective Inflammation Reduction: The compounds reduce harmful inflammatory markers like IL-6 and myeloperoxidase while leaving the immune system's ability to fight real infections intact.

The research, published in Nature Chemical Biology on April 6, 2026, showed that ENDO12 significantly reduced blood levels of inflammatory markers in animal models that received a TLR-activating molecule. Crucially, these same animals maintained a normal antiviral immune response when exposed to a virus, demonstrating that the drug doesn't leave patients vulnerable to infections .

Which Autoimmune Diseases Could Benefit From This Discovery?

The initial focus is on conditions that affect more than 15 million Americans. These include lupus, rheumatoid arthritis, and juvenile arthritis, all of which involve the overactive TLR responses that ENDOtollins are designed to target .

"Most treatments for autoimmune diseases manage symptoms; they don't change the underlying course of the disease. What's exciting about this approach is its potential to be disease-modifying: targeting the specific molecular machinery that drives inflammation, rather than broadly suppressing the immune system," explained Hugh Rosen.

Hugh Rosen, Professor at Scripps Research and the Pearson Family Chair

Beyond autoimmune conditions, researchers suggest ENDOtollins might help treat cytokine storms, the dangerous immune overreactions seen in patients with severe COVID-19 and as a side effect of CAR-T cancer therapy. Both conditions involve excessive IL-6 and runaway inflammation that could potentially be controlled by these new compounds .

The team's next steps include testing ENDOtollins in animal models that more closely mimic human autoimmune diseases and further optimizing the compounds' chemistry for potential clinical use. While translating these findings into treatments for patients remains a long-term goal, the mechanistic insights are already valuable for understanding how cellular compartments become stressed or dysfunctional in conditions ranging from autoimmune diseases to neurodegeneration .

This research represents a significant shift in thinking about autoimmune disease treatment. Rather than asking the immune system to stand down entirely, ENDOtollins ask it to stop attacking the wrong targets while remaining vigilant against genuine threats. For the millions of Americans struggling with autoimmune diseases and their side effects, that distinction could mean the difference between managing a chronic condition and achieving real disease control.