Inside the mitochondria of every immune cell lies a molecule that could hold the key to treating inflammatory bowel disease: cardiolipin, a lipid that researchers at the University of Cologne have just discovered plays a critical role in controlling gut inflammation.
For years, scientists have puzzled over what causes inflammatory bowel diseases—whether the primary culprit is harmful microbes or defects in the body's own immune cells. A research group led by Dr. Mauro Corrado at CECAD Cluster of Excellence for Aging Research and the Center for Molecular Medicine Cologne has now identified a crucial piece of that puzzle. They found that cardiolipin, a mitochondrial lipid, is essential for keeping regulatory T cells functioning properly. These are the immune cells whose job is to suppress excessive inflammatory responses and maintain balance in the gut.
The discovery emerged from experiments in mouse models where researchers stripped T cells of the enzyme needed to produce cardiolipin. The results were striking: without cardiolipin, the mice developed gut inflammation regardless of changes in their microbiota. When exposed to harmless gut bacteria, the inflammation progressed more rapidly and became more severe. The mechanism is metabolic—without cardiolipin, regulatory T cells lose what researchers call their "metabolic fitness" and trigger a stress response that leads to disease.
What makes this finding particularly promising is that the effect proved reversible. Once the researchers corrected the stress response in the mice, gut balance was restored and the animals lived longer. This suggests that therapies targeting the metabolism of immune cells could open an entirely new avenue for treating inflammatory bowel diseases.
"These findings offer a new perspective on inflammation," Dr. Corrado said. "We believe that targeting the metabolism of immune cells specifically could be a fundamentally new approach to treating inflammatory bowel diseases." The research, published in Nature Metabolism, combined cutting-edge immunology with state-of-the-art lipidomics and metabolic analysis to reveal this connection.
The implications extend beyond inflammatory bowel disease. The study offers insights into why infections and diseases progress so differently from person to person. Experiences with COVID-19 and other pathogens have shown that the same illness can cause mild symptoms in one person and severe or fatal outcomes in another. Individual differences in how efficiently immune cells metabolize energy may partially explain this variation. Though this study examined a single metabolic defect, researchers plan to expand their work to investigate other mitochondrial abnormalities.
The findings also illuminate a rare genetic condition called Barth syndrome, caused by cardiolipin deficiency. Patients with Barth syndrome suffer not only from life-threatening heart conditions but also from immune system disorders, including susceptibility to recurring infections and gastrointestinal problems. The new research suggests that T-cell deficiencies linked to cardiolipin loss could explain at least some of these immune complications—offering hope that understanding this lipid's role might one day help patients with this devastating condition.