Food allergies are slowly increasing within first world countries. According to the National Institute of Allergy and Infectious Diseases (NIAID), 8% of children and 11% of adults are affected by food allergies in America. Allergic reactions to food occur when the body’s immune system recognizes specific foods as foreign. As a result, the immune system builds a response and reacts. Reactions can range from mild to severe and include symptoms such as skin rashes, gastrointestinal issues, respiratory problems, headaches, and others. Besides avoiding potential foods that would cause a reaction, antihistamines and immunotherapies can help reduce symptoms.
The immune system works to target foreign pathogens to maintain healthy homeostatic levels throughout the body. In a healthy functioning body, various immune cells work to elicit a strong immune response. Immune cells communicate with one another to respond to molecules and foreign bodies that are deleterious invaders. However, allergies in general are a result of the immune system becoming hypersensitive to stimuli, such as pollen, dust, rag weed, and foods. Specific cells known as dendritic cells work to activate immune cells, such as T cells which are responsible for targeting and eliminating invaders. The dysregulation of this activation pathway results in overactivity of T cells. Scientists believe that dendritic cells are more involved in allergic reactions than previously thought. As a result, scientists have begun investigating dendritic cells as a possible target population for allergy medication.
A recent article in Nature, by Dr. Dan Littman and others, discovered that specific dendritic cells are critical for the regulation of food allergy response. Littman is the Helen L. and Martin S. Kimmel Professor of Molecular Immunology in the Department of Pathology at the New York University Langone Health Center. He is a world-renowned T cell biologist and a member of the National Academy of Sciences. His work had driven the field of T helper cells, which support robust immunity against pathogens.
Littman and his team found that dendritic cells present in the intestine allows food to pass by without reacting to cause an allergy. These cells were observed to have high expressions of PR domain-containing 16 (Prdm16) and Retinoic Acid-Related Orphan Receptor-gamma-t (RORyt), which protect foods from being targeted by the immune system. Consequently, mouse models that did not have dendritic cells that expressed RORyt and the PR domain were more susceptible to allergies.
Researchers used various laboratory techniques including the use of mouse models to demonstrate the role of RORyt and Prdm16 on dendritic cells. Interestingly, it was discovered that these dendritic cells not only help digest food, but also control the function of organ systems throughout the body. Further investigation outlines that these cells are involved in the regulation of the microbiome or vast array of microorganisms that prevent chronic autoimmunity, such as Crohn’s disease.
Littman and others also looked at patient samples and found similar dendritic cells in tissues. This applicability to humans is incredibly powerful and provides scientists with a potential target for food allergy and autoimmune treatment. Overall, the discovery of RORyt and Prdm16 expressing dendritic cells offers valuable insights into the underlying mechanisms of allergies and how physicians could treat them. Littman and his colleagues hope to learn more about these cells in the human body and how they are directly involved in allergy and autoimmune disorders.
Article, Nature, Dan Littman, New York University Langone Health Center.