Mucosal Immunity and the Gut–Immune Axis: Health, Disease, and Therapeutic Modulation

This chapter reviews the unique immunological architecture of mucosal surfaces, with a focus on the gastrointestinal tract as the primary site of immune education, tolerance induction, and barrier defense. It examines recent advances in understanding the bidirectional interactions between the intestinal microbiome and mucosal immune cell populations, including IgA-secreting plasma cells, intraepithelial lymphocytes, and innate lymphoid cells, and their collective regulation of local and systemic immune homeostasis. The chapter discusses implications of mucosal immune dysregulation in inflammatory bowel disease, food allergy, systemic autoimmunity, and the emerging potential of microbiome-directed and mucosal vaccine strategies.