Augmentation of DNA exonuclease TREX1 in macrophages as a therapy for cardiac ischemic injury.

Abstract

Noncoding RNAs (ncRNAs) are increasingly recognized as promising therapeutic candidates. Here, we report the development of therapeutic Y RNA 1 (TY1), a synthetic ncRNA bioinspired by a naturally occurring human small Y RNA with immunomodulatory properties. TY1 up-regulates three-prime DNA exonuclease 1 (TREX1), an exonuclease that rapidly degrades cytosolic DNA. In preclinical models of myocardial infarction (MI) induced by ischemia-reperfusion, TY1 reduced scar size. The cardioprotective effect of TY1 was abrogated by prior depletion of macrophages and mimicked by adoptive transfer of macrophages exposed to either TY1 or <i>Trex1</i> overexpression. Inhibition of <i>Trex1</i> in macrophages blocked TY1 cardioprotection. Consistent with a central role for <i>Trex1</i>, TY1 attenuated DNA damage in the post-MI heart. The key beneficial effects appear to be mediated by extracellular vesicles secreted by TY1-conditioned macrophages. This previously undescribed mechanism-pharmacological up-regulation of <i>Trex1</i> in macrophages-establishes TY1 as the prototype for a new class of ncRNA drugs with disease-modifying bioactivity. We refer to this potential new class of ncRNA drugs as exomers because of the identification of their parent molecules in extracellular vesicles.