Researchers at Weill Cornell Medicine have made a significant discovery linking two critical pathways that control the immune system in mammals. This discovery sheds new light on chronic inflammatory bowel diseases (IBD), which affect over 2 million people in the US and significantly impact their health and quality of life.
Our immune system uses various pathways to protect us from infections, but sometimes, these pathways can become overactive, leading to autoimmune diseases like IBD. One crucial immune factor involved in these diseases is Interleukin-23 (IL-23). It plays a role in fighting infections but can also contribute to inflammatory conditions like IBD, psoriasis, and rheumatoid arthritis. Until now, scientists didn’t fully understand why IL-23 could be beneficial in some situations and harmful in others.
In their study in Nature, researchers found that IL-23 influences a specific type of immune cell called group 3 innate lymphoid cells (ILC3s), which are crucial in protecting mucosal tissues such as the intestines and lungs. When IL-23 interacts with ILC3s, it increases the activity of a regulatory factor called CTLA-4. This factor helps prevent the immune system from attacking the body’s tissues and maintains a healthy balance with beneficial gut bacteria. This mechanism is essential for controlling inflammation in the gut, but it’s disrupted in IBD.
The research highlights ILC3s as a critical link between IL-23-driven inflammation and regulatory mechanisms that maintain gut health. Understanding this link could have broader implications, particularly in cancer treatment. It appears that manipulating these pathways could help to enhance cancer therapies. However, caution is needed because blocking CTLA-4 on ILC3s could worsen gut inflammation, a known side effect of some immunotherapy treatments.
Dr Gregory Sonnenberg, one of the study’s senior authors, emphasised the unexpected nature of their findings and the potential for developing more targeted therapies. By focusing on ILC3s and their response to IL-23, researchers hope to develop treatments to alleviate inflammation associated with IBD and possibly improve cancer therapies by fine-tuning how these pathways are manipulated.
The study used advanced techniques like single-cell RNA sequencing to confirm their findings across different types of immune cells in healthy intestines and in samples from IBD patients. This meticulous approach validated that the IL-23–CTLA-4 pathway is active in healthy intestines but impaired in inflamed intestines of IBD patients, suggesting a potential target for future therapies and instilling confidence in the research’s validity.
Overall, this research deepens our understanding of immune system regulation and opens doors for developing more effective treatments for chronic inflammatory diseases and enhancing cancer therapies. It underscores our immune system’s intricate balance and the potential benefits of precisely targeting specific pathways in disease treatment.
More information: Anees Ahmed et al, CTLA-4-expressing ILC3s restrain interleukin-23-mediated inflammation, Nature. DOI: 10.1038/s41586-024-07537-3
Journal information: Nature Provided by Weill Cornell Medicine
