How a Chemical Reaction Triggers Brain Inflammation in Alzheimer’s Disease

Scientists at Scripps Research have identified a specific chemical reaction that triggers chronic brain inflammation in Alzheimer’s disease, offering a potential new target for treatment. The discovery centers on a protein called STING, which normally acts as an early-warning system for infections but becomes pathologically overactivated in Alzheimer’s brains through a process known as S-nitrosylation.

In the brains of people with Alzheimer’s disease, STING undergoes a chemical modification called S-nitrosylation (SNO), where nitric oxide binds to the protein to form “SNO-STING.” This modification causes STING to cluster into inflammatory complexes, driving the chronic activation of the brain’s immune cells that damages connections between nerve cells.

The research, published in Cell Chemical Biology on April 23, 2026, used human Alzheimer’s brain cells in a preclinical study to identify this molecular switch. By blocking the S-nitrosylation of STING at a specific building block—cysteine 148—scientists were able to quiet the brain’s “immune storm” in mouse models of the disease.

This precision targeting approach differs from many anti-inflammatory drugs that shut down the entire immune system. Instead, blocking the SNO modification at cysteine 148 only prevents the overactivation caused by Alzheimer’s pathology, preserving the body’s ability to fight infections through other immune pathways.

In preclinical models, preventing S-nitrosylation of STING did more than reduce inflammation—it actively stopped the degradation of synapses, the connections between brain cells required for memory and learning. The study showed that stopping the formation of SNO-STING protected these vital nerve cell connections in Alzheimer’s mouse models.

The findings build on existing evidence that in Alzheimer’s disease, the brain’s immune cells are chronically overactivated, causing inflammation that damages synaptic connections. Researchers note that the SNO modification is triggered by factors associated with aging and Alzheimer’s pathology, including toxins and protein clumps like amyloid-beta.

While the research represents a promising direction for Alzheimer’s treatment, scientists emphasize that the findings come from preclinical studies using mouse models and human brain cells. Further research will be needed to determine whether targeting this specific chemical modification could be safe and effective in human patients.