Lucia Vojtech, PhD
Senior Fellow, Obstetrics & Gynecology
University of Washington
Exposure to infected semen is the primary route of transmission for many microbes. It has been established that factors in semen directly influence early events in viral transmission in the genital mucosa, but which components are responsible is not well understood. Each ejaculate contains trillions of exosomes, microvesicles secreted by cells of the male genital tract. Evidence that exosomes in general are important mediators of intercellular communication is rapidly accumulating, and in cells that take up exosomes, immunoregulatory effects have been described. We have established a protocol to isolate exosomes from semen which consistently results in 1012 or more vesicles per ejaculate. We observe that seminal exosomes rapidly enter antigen-presenting cells, altering cytokine production in response to pathogenic stimulus. Sequencing the small RNA content of seminal exosomes revealed small non-coding RNAs with regulatory potential as well as approximately 125 different miRNAs. Many of the most abundant miRNAs found in exosomes from all tested donors are potentially immunomodulatory. Understanding how seminal exosomes transfer immunoregulatory messages between people may help to improve vaccination and other strategies against viral disease.