Bacillus subtilis spore induces efficient generation of memory T cells via ICAM-1 expression on dendritic cells

The intestinal mucosa is the primary exposure and entry site of infectious organisms. Tissue-resident memory T cells (Trms) is an important first line of defense against infection in mucosal tissues, their function in intestinal immunization remains to be investigated. Here, we reported that the levels of local mucosal and systemic immune responses were enhanced through oral immunization with H9N2 whole inactivated virus (H9N2 WIV) plus spore. Subsequently, H9N2 WIV plus spore led to the generation of CD103 + CD69 + Trms, which was independent of circulating T cells during the immune period. Meanwhile, we also found that Bacillus subtilis spore can stimulate Acrp30 expression in 3T3-L1 adipocytes. Moreover, adipocyte supernatant or spore also upregulated intercellular adhesion molecule-1 (ICAM-1) expression on dendritic cells (DCs) ( P