Abstract

Mucosal surfaces serve as the primary points of contact between the host and the external environment, constantly exposed to a myriad of pathogens and antigens. To ensure effective protection against invading microorganisms while maintaining tolerance to harmless commensals, the mucosal immune system has evolved a sophisticated surveillance mechanism. This abstract provides an overview of mucosal immune surveillance, highlighting its key components, cellular players, and mechanisms involved in maintaining immune homeostasis. Mucosal immune surveillance involves a complex interplay of innate and adaptive immune cells residing in mucosal tissues, including the respiratory, gastrointestinal, and genitourinary tracts. Epithelial cells lining these surfaces act as sentinels, capable of recognizing and responding to microbial and non-microbial insults through pattern recognition receptors (PRRs). Upon detection of potential threats, epithelial cells initiate immune responses by releasing chemokines and cytokines, recruiting immune cells to the site of infection or inflammation. Dendritic cells (DCs) play a pivotal role in mucosal immune surveillance by capturing antigens at mucosal surfaces and transporting them to secondary lymphoid organs. Here, DCs interact with T cells, promoting the differentiation of antigen-specific effector T cell subsets, such as Th1, Th2, Th17, and regulatory T cells, tailored to combat specific pathogens or maintain immune tolerance. B cells, residing in mucosalassociated lymphoid tissues, generate secretory immunoglobulin A (IgA) antibodies that provide a first line of defense against pathogens by neutralizing and preventing their attachment to epithelial surfaces. Importantly, mucosal immune surveillance encompasses mechanisms to maintain immune homeostasis and prevent excessive immune responses. Regulatory T cells and immunoregulatory cytokines, such as transforming growth factor-beta (TGF-β) and interleukin-10 (IL-10), actively suppress inflammatory reactions, ensuring appropriate immune responses without tissue damage. Furthermore, mucosal-associated lymphoid tissues possess specialized immune compartments, such as Peyer’s patches and isolated lymphoid follicles, facilitating immune induction and tolerance. Understanding the intricacies of mucosal immune surveillance is crucial for developing strategies to prevent and treat mucosal infections, autoimmune diseases, and allergies. Targeting specific components of the mucosal immune system could lead to the development of novel vaccines, immunotherapies, and mucosal adjuvants that enhance protective immune responses or restore immune balance.