Resident microbes shape host immunity and protect against pathogen infection and inflammatory disease

B cells. We discuss how resident microorganisms shape these immune components to form a protective barrier system that not only confers resistance to pathogenic and opportunistic microbial infections but also maintains local and systemic immune homeostasis. Furthermore, we address how disruption of these microbiota-driven regulatory networks can contribute to the development of inflammatory diseases, highlighting the importance of host-microbiota interactions in health and disease.