Non-coding RNA-based therapeutics and biomarkers for treatment and detection of vascular disease

Abstract

Cardiovascular disease (CVD), with atherosclerosis as its main underlying pathology, is the most prominent cause of death worldwide. Progression and rupture of atherosclerotic plaques lead to potential adverse pathological events such as myocardial infarction and stroke. Although largely successful, primary and secondary prevention strategies have thus far been insufficient in minimizing the vast consequences of atherosclerotic disease progression on global health. Abdominal aortic aneurysm (AAA) disease shares a similar risk profile with atherosclerosis. A consequence of undiagnosed AAAs can be their subsequent rupture, which up to 90% of patients will not survive.

In both atherosclerosis and AAA, treatment and prevention are complicated by the fact that they progress silently and rarely lead to significant health impacts in their early stages. In addition, different pathological processes are known to be of importance as the diseases progress. These are also affected by patient-specific genetic and environmental risk factors. It would therefore be of benefit to find better ways of stratifying patient-specific disease risk and develop novel treatments. In the past decades, non-coding RNAs have emerged as powerful disease regulators in CVD and have been implicated as disease biomarkers in several research fields. In this thesis, we have sought to: (1) identify novel long non-coding RNAs (lncRNAs) involved in late-stage atherosclerotic disease and AAA, (2) establish techniques of their targeted delivery to affected vasculature, and (3) identify novel microRNA biomarkers of AAA with direct roles in disease development and progression.

In study I, we have identified lncRNA MIAT as a novel regulator of vascular smooth muscle cell (VSMC) dynamics in carotid atherosclerotic disease, with positive effects on their survival – a beneficial trait in late-stage disease. Its effects on earlier disease stages were however detrimental through regulation of VSMC phenotypic switching into macrophage-like phenotypes and through regulation of macrophage-specific processes. In study II, we identified the lncRNA NUDT6, the natural antisense transcript of FGF2, to be up-regulated in fibrous caps of vulnerable vs stable plaques. NUDT6 was also up-regulated in AAA vs control aortic tissues. In experimental animal models of atherosclerosis and AAA, FGF2 de-repression by the way of NUDT6 inhibition had a beneficial effect on disease phenotypes and was successful in limiting the progression of these diseases. In studies II and III, we successfully used drug-eluting balloons to deliver therapeutics to the abdominal aorta of the translational mini-pig model of AAA. In addition, in study III, we observed beneficial effects of lenvatinib (VEGF-signaling inhibitor) on experimental AAA disease phenotype through positive effects on VSMC contractility and decreased diameter growth. Finally, in study IV, we identified miR-15a-5p as a novel disease biomarker of AAA. We showed miR-15a-5p to be relevant in AAA pathogenesis through its ability to modulate VSMCs into more inflammatory phenotypes, and its inhibition was able to limit experimental murine AAA diameter growth. In conclusion, our studies not only confirm that non-coding RNAs are promising targets for treatment of CVD, but also underline the translational feasibility of their use.