Attenuation of Hypertension and Heart Hypertrophy by Adeno-Associated Virus Delivering Angiotensinogen Antisense

Abstract

Abstract-Angiotensinogen (AGT), one of the major components in the renin-angiotensin system, has been linked to hypertension in humans and animals. We have previously systemically administered antisense oligonucleotides and plasmid vectors with DNA that targeted AGT and attenuated hypertension in spontaneously hypertensive rats. The aim of the present study was to prolong the effect of antisense treatment by the use of a recombinant adeno-associated viral (rAAV) vector targeted to AGT. Using a model of lifelong hypertension in which 5-day-old spontaneously hypertensive rats are treated, a single intracardiac injection of rAAV-AGT-antisense (rAAV-AGT-AS) delayed the onset of hypertension for 91 days and significantly attenuated hypertension in adulthood for up to 6 months. Key Words: adeno-associated virus Ⅲ hypertrophy, cardiac Ⅲ antisense Ⅲ gene therapy Ⅲ angiotensinogen A ntisense inhibition for gene therapy of hypertension is a novel approach to provide long-term control of hypertension. 1 Because the antisense strategy can target genes precisely, inhibition of specific proteins can be achieved. Although the genes involved in hypertension are largely unknown, currently used drugs control high blood pressure by inhibiting a few proteins such as angiotensin-converting enzyme (ACE), ␤ 1 -adrenoceptors (␤ 1 -AR), and angiotensin type 1 receptor (AT 1 -R). Therefore, specific gene targeting of these proteins has been our strategy with antisense oligodeoxynucleotides (AS-ODNs). Compared with current drugs, AS-ODNs are more specific and longer lasting and therefore may have certain advantages over current drug therapy. The longer duration of action could provide more consistently effective blood pressure control and thereby increase patient compliance. Despite all the drugs available, only Ϸ29% of all hypertensives have their high blood pressures controlled. Therefore, there is a need to explore a new generation of methods of treatment. Gene therapy, while oversold, still offers an approach that could produce prolonged benefits if based on scientific research. Whereas AS-ODN can reduce high blood pressure in rat models for weeks with a single dose, 1,2 even longer-lasting effects can be achieved with viral vectors. 1 Studies with the retrovirus used to deliver antisense to AT 1 -R or ACE have been shown to produce long-lasting effects in reducing high blood pressure when given in the first 5 days after birth. 3,4 Retroviruses, however, have disadvantages as a vector for therapeutic use. These include the possibility of tumorigenic activity, the vector entering the germ line, and the limitation that retroviruses only infect dividing cells. Adeno-associated virus (AAV) has the potential to provide stable, effective, and very long-lasting delivery of antisense, 5 even in nondividing cells. Because the previous studies have targeted the AT 1 -R for inhibition of the reninangiotensin system (RAS), the purpose of this study was to target angiotensinogen (AGT) mRNA with antisense and deliver it with AAV as a vector. AGT ha...

The effects of repeated delivery of angiotensin II AT1 receptor antisense on distinct vasoactive systems in Ren-2 transgenic rats: young vs. adult animals

“…Our previous study revealed that single dose of AS against ANG II receptor type 1 (AT 1 R) applied intravenously to young heterozygous TGR had transient antihypertensive effects. 15 Other studies have also shown that the long-term effect of AS therapy against angiotensinogen or AT 1 R persisted for 3 months in young spontaneously hypertensive rats (SHRs), 16,17 whereas the effect lasted only 1 month in adult SHRs. 18 Interestingly, AS therapy had an antihypertensive effect (B20 mm Hg) in young TGRs, which was associated with attenuated cardiac hypertrophy.…”

Gene Therapy for Hypertension

“…Therefore, injecting in 5-day-old SHR allowed us to observe if the development of hypertension would be reduced. A single injection of AAV-AGT-AS in 5-day-old SHR significantly attenuated the full development 34 and level of hypertension for up to 6 months. In 3-week-old SHR, rAAV-AT 1 R-AS significantly reduced hypertension by Ϸ30 mm Hg for at least 5 weeks (the length of the study).…”

“…However, unlike the reports of the effect of retrovirus delivery of an AT 1 R-AS in 5-day-old SHR "curing" hypertension, 32 we did not find a complete inhibition of the rise in blood pressure. 31,34 In rAAV-AGT-AS-treated SHR, measures of plasma AGT levels showed a corresponding lack of increase in AGT in the antisense-treated groups compared with the significant increase of AGT in the control animals. 34 Correlation of AGT versus blood pressure was significant (PϽ0.05) in the control-treated animals and not significant in the antisensetreated animals.…”

“…31,34 In rAAV-AGT-AS-treated SHR, measures of plasma AGT levels showed a corresponding lack of increase in AGT in the antisense-treated groups compared with the significant increase of AGT in the control animals. 34 Correlation of AGT versus blood pressure was significant (PϽ0.05) in the control-treated animals and not significant in the antisensetreated animals. This shows that AGT in the SHR is correlated with an increase in blood pressure.…”

AAV vectors for RNA-based modulation of gene expression

“…This led to a delayed onset of hypertension and an attenuated disease. 51 Cold-induced hypertension was attenuated when a U6-driven shRNA against the mineralocorticoid receptor was systemically delivered by an AAV2 vector in rats 52 and mice. 53 A 50% reduction in expression of the receptor was documented in the kidney where hypertrophy was attenuated, but not in the heart or aorta.…”