The invention provides surface-layer protein coated microspheres for delivery of a therapeutic agent to the intestine. These surface-layer protein coated microspheres generally include a core encapsulated by a microsphere which is coated by surface layer protein. The core includes a therapeutic agent, such as a defensin. The invention also includes methods of making and using the surface-layer protein coated microspheres of the invention for administering therapeutic agents to a subject in need thereof. The invention also includes pharmaceutical dosage units that include the surface-layer protein coated microspheres of the invention. The invention further includes various labeled defensins for use in the study of the properties and actions of defensins, and further includes the use of defensins, particularly HD5α in the treatment of inflammatory conditions of the bowel, such as Crohn's disease.
