The immune system provides protection against diverse infectious agents such as viruses, bacteria, fungi, and parasites. However, an excessive immune reaction towards these foreign invaders can cause collateral damage to the surrounding tissue and organs. Our laboratory investigates how a balanced immune response is generated, and what happens when this balance is disrupted. We are particularly interested in understanding why some infectious agents cause disease while others are harmless or beneficial, such as the trillions of commensal bacteria that colonize our intestine, also referred to as the 'microbiome'. By learning the difference between helpful immune responses versus those that cause harm, we will be able to design better treatments for inflammatory bowel disease, cancer, and other chronic inflammatory conditions.