Extracellular Vesicles (Exosomes) as Immunosuppressive Mediating Variables in Tumor and Chronic Inflammatory Microenvironments

Exosomes are extracellular vesicles released by most of the eukaryotic cells. Exosomes’ components include proteins, lipids, microRNA, circular RNA, long noncoding RNA, DNA, etc. Exosomes may carry both pro and anti-inflammatory cargos; however, exosomes are predominantly filled with immunosuppressive cargos such as enzymes and microRNAs in chronic inflammation. Exosomes have surfaced as essential participants in physiological and pathological intercellular communication. Exosomes may prevent or promote the formation of an aggressive tumor and chronic inflammatory microenvironments, thus influencing tumor and chronic inflammatory progression as well as clinical prognosis. Exosomes, which transmit many signals that may either enhance or constrain immunosuppression of lymphoid and myeloid cell populations in tumors, are increasingly becoming recognized as significant mediators of immune regulation in cancer. In this review, we outline the function of exosomes as mediators of immunosuppression in tumor and chronic inflammatory microenvironments, with the aim to improve cancer therapy.