Abstract P3160: Myocarditis Treatments Within Our Sights: Targeting Inflammatory Conversations In The Heart Using Extracellular Vesicles

Abstract

Viral myocarditis is an inflammatory cardiomyopathy with no pharmacologic agent currently able to quell the immune mechanisms that damage the heart in their inflammatory crossfire to quell infections, without risk of immunocompromise. Sex differences are well known in inflammatory and/or infectious diseases. Females display more efficient, anti-inflammatory responses to external threats like viruses, while males launch a pro-inflammatory defensive response. Myocarditis is a classic case of an infectious, inflammatory disease being more frequent and more severe in men, while pre-menopausal women are most protected. Extracellular vesicles are biocompatible, highly abundant, stable messaging carriers with no transformative risk, and hold great promise as therapeutics due to their functional cargo. As EVs are soluble mediators of the conversations between cells, we seek to redirect protective anti-inflammatory messaging from pre-menopausal women to male mice, using a highly translational model of murine myocarditis. We derive EVs from omental fat, repurposing this source to derive a purified, therapeutic component. Our results show robust immune system control, with EV treatments effectively attenuating pro-inflammatory inflammasome and complement markers, while leaving regulatory components like M2b macrophages and complement component CR1 unchanged. Treated mice are healthier during acute disease and demonstrate better heart function than control mice, despite being a strain susceptible to myocarditis and subsequent dilated cardiomyopathy. Tests using EVs from similarly aged men do not demonstrate this anti-inflammatory capacity. Proteomic and RNA-sequencing content comparisons of these EVs from these two donor groups reveal important proteins and regulatory micro RNAs. Our data suggest that EVs from fat may be a novel anti-inflammatory treatment for viral myocarditis, however individual donors show varying therapeutic capacity, with EV content heavily influenced by sex and age. This study not only addresses a major therapeutic gap in the myocarditis field, but also provides functional and -omic based comparisons of EVs from donors differing only by sex, to test if female cardioprotection from myocarditis is transferrable.