Mitochondrial DNA in Exosomes Is Warning That Initiates Antiviral Response

Researchers at the Carlos III National Center for Cardiovascular Research (CNIC) in Madrid, Spain have provided valuable information about the defense mechanisms of the immune system in early learning to respond to pathogens such as viruses or bacteria. The data from this research, published online on July 9, 2018 in Nature Communications, contribute to the understanding of cellular processes that begin in the first moments and explain how the different cellular components of the immune system communicate to give an effective response to pathogens. The CNIC researchers have determined that the mitochondrial DNA contained in certain nanovesicles causes a state of alert in the receptor cells that allows the activation of the antiviral genetic program. These nanovesicles, known as exosomes, are produced by T lymphocytes and captured by dendritic cells via intercellular contacts. The immune response against pathogens requires the specific interaction between T lymphocytes and antigen-presenting cells, especially dendritic cells, a process known as immune synapses. During this process, the researchers explain, intercellular information is exchanged both by receptor connections and their ligands, which exist on the cell surface, and by the transfer of exosomes. Until now, the activation routes in the T cells after the immune synapse had been studied; however, both the identity of the signals received and their functional effects on the dendritic cells had received less attention. The laboratory of Professor Francisco Sánchez-Madrid, principal investigator of the Intercellular Communication Group of the CNIC, Head of the Hospital la Princesa, and Professor of Immunology of the Autonomous University of Madrid, had previously described the ability of T cells to transfer exosomes to the dendritic cells during the immune synapse.
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