Exosome in intestinal mucosal immunity

Abstract

Intercellular communication of immune cells is critical to elicit efficient inflammatory responses. In intestinal mucosa, imbalance in pro-inflammatory and anti-inflammatory mediators, especially cytokines and chemokines, characterizes the underlying immune mechanisms of inflammatory bowel disease. Exosomes, small membrane vesicles secreted into the extracellular environment, are emerging as another important intercellular messenger in immune responses. A major recent breakthrough in this field unveils the capacity of exosomes to mediate the functional transfer of genetic materials (mRNAs and miRNAs) between immune cells. RAB27A and RAB27B are two small GTPases involved in exosome secretion. With respect to intestinal mucosal immunity, increased number of RAB27A-positive immune cells and RAB27B-positive immune cells are demonstrated in the colonic mucosa of patients with active ulcerative colitis as compared with that of healthy controls. This indicates the important role of exosome-mediated immune responses in the pathogenesis of inflammatory bowel disease. Here, we will discuss the immune properties of exosomes and recent advances in their function with a special focus on intestinal mucosal immunity.

Circulating exosomes regulate T‐cell–mediated inflammatory response in oral lichen planus

“…Their regulatory roles and potentially modulating mechanisms have been extensively investigated. The obtained evidence indicates that exosomes are able to promote the intercellular signaling transmission of immune cells . Exosomes are naturally nanosized extracellular vesicles with size distribution from 30 to 150 nm .…”

Crosstalk between intestinal epithelial cell and adaptive immune cell in intestinal mucosal immunity

“…As first‐line sentinel, IECs are capable of collecting luminal antigen, and exosome‐dependent antigen presentation of IECs greatly contributes to maintenance of local mucosal homeostasis. Both the number of IEC‐derived exosomes and quantity of MHC II molecules loaded in exosomes are elevated in infection, partly induced by interferon (IFN)‐γ, which means antigen presentation by IECs would be enhanced in inflammatory conditions …”

“…Both the number of IEC-derived exosomes and quantity of MHC II molecules loaded in exosomes are elevated in infection, partly induced by interferon (IFN)-γ, which means antigen presentation by IECs would be enhanced in inflammatory conditions. 16,17 IEC-mediated tolerance maintenance. Effective activation of T reg cells contributes to the maintenance of tolerance and suppression of over-activation of immune response.…”

Inhibition of lncRNA NEAT1 suppresses the inflammatory response in IBD by modulating the intestinal epithelial barrier and by exosome-mediated polarization of macrophages

“…Exosomes belong to a group of naturally secreted extracellular vesicles, which mediate short-and long-distance intercellular communication and deliver different types of biologically active cargo to recipient cells (23,24). In addition, exosomes are involved in other biological processes, including material transportation, cell division and apoptosis, and circulating exosomes have been demonstrated to be involved in regulation of the immune response (25). Exosomes have also been confirmed to be involved in the pathogenesis of IBD through the modulation of p38 and extracellular signal-regulated kinase (ERK) phosphorylation and the production of tumor necrosis factor-α to regulate macrophage activity (26).…”