Beyond Nitric Oxide: Scientists Uncover iNOS "Structural Switch" That Directly Disables the Body’s Natural Inflammatory Brake

Researchers at Surrey and Oxford discover iNOS "handcuffs" the body's natural anti-inflammatory brake, opening new paths for treating arthritis and heart disease.

By: AXL Media

Published: Apr 24, 2026, 12:25 PM EDT

Source: Information for this report was sourced from the University of Surrey and the journal Nature Metabolism.

A Paradigm Shift in Immunology

For decades, inducible nitric oxide synthase (iNOS) has been a primary suspect in the study of chronic inflammation. Scientists long believed its role was limited to producing nitric oxide, a signaling molecule that, in excess, causes tissue damage. However, new research led by the University of Surrey and the University of Oxford has revealed that iNOS has a "second job." It acts as a physical regulator within the cell, directly binding to another protein called IRG1. This physical union effectively sequesters IRG1, stopping it from performing its vital role: producing itaconate, a metabolite that acts as the body’s natural emergency brake on the inflammatory response.

The "Handcuff" Mechanism Inside Mitochondria

The study utilized advanced mass spectrometry and computational modeling to map exactly how these proteins interact within the mitochondria of immune cells. The results showed that when iNOS adopts a specific shape—stabilized by its cofactor, tetrahydrobiopterin (BH4)—it physically docks with IRG1. This binding is remarkably high-affinity and stable in both human and mouse models. Critically, the researchers discovered that in cells lacking iNOS, IRG1 produced 15 times more itaconate, allowing the immune system to self-regulate and dampen inflammation much more effectively.

Precision Targeting vs. Broad Suppression

This discovery is particularly significant for drug development because it moves away from broad-spectrum immune suppression. Current anti-inflammatory treatments often dampen the entire immune system, leaving patients vulnerable to infections. Dr. Mark Crabtree of the University of Surrey explains that by focusing on the physical interface between iNOS and IRG1, scientists can design "precision strikes." By disrupting only this specific protein-to-protein interaction, they could potentially free the body’s natural itaconate "brake" without interfering with the immune system's ability to fight off external pathogens.