Inhibition of Hypertension by Peripheral Administration of Antisense Oligodeoxynucleotides

Abstract

We administered liposome-encapsulated antisense oligodeoxynucleotide targeted to angiotensinogen mRNA peripherally to spontaneously hypertensive rats to test whether peripheral angiotensinogen reduction would lower their hypertensive blood pressures and to determine the role of peripheral angiotensinogen in the modulation of hypertension. Using in vitro translation techniques, we tested the sequence specificity of the antisense sequence. The selected antisense sequence decreased angiotensinogen production in vitro, enabling us to distinguish between specific and nonspecific effects. To increase the efficiency of peripheral and hepatic antisense delivery, oligonucleotides were liposome encapsulated and intra-arterial administration. Confocal microscopy was used for determination of the hepatic distribution of fluorescently labeled antisense. Encapsulated antisense molecules were seen to be distributed within liver tissue 1 hour after injection; however, little or no uptake was observed with the unencapsulated oligonucleotides. We also determined the physiological effects of antisense oligodeoxynucleotide targeted to liver angiotensinogen mRNA. Administration of liposome-encapsulated antisense significantly decreased hypertensive blood pressures to normotensive levels compared with scrambled control oligonucleotides, unencapsulated antisense, and empty liposomes (P = .013). These data were supported by biochemical changes elicited by the antisense treatment. Rats receiving liposome-encapsulated antisense had significantly lowered peripheral angiotensinogen and angiotensin II levels compared with control groups (P < .05). No significant heart rate changes were observed in the antisense or control groups. These results suggest that peripheral angiotensinogen plays a role in the maintenance of hypertensive blood pressure in this model of hypertension and that peripheral administration of antisense molecules is possible with organ-targeted delivery mechanisms.

Somatic gene therapy for hypertension

“…However, there is no currently available drug to inhibit AGT. We have designed antisense, targeted to AGT mRNA and tested it in vivo and in vitro (5). When given iv the AGT-AS-ODN would reduce blood pressure significantly when delivered with a liposome.…”

Kidney Aminopeptidase A and Hypertension, Part I

“…Angiotensin-converting enzyme (ACE) inhibitors and angiotensin type 1 (AT 1 ) antagonists or, more recently, delivery of antisense oligonucleotides or complementary RNA against angiotensinogen or AT 1 receptors reduce or prevent hypertension in SHR. 1,2 On the other hand, plasma renin activity and plasma angiotensin II (Ang II) levels are not consistently elevated during any given stage of development in SHR. [3][4][5][6][7] Likewise, although plasma Ang II is elevated in stroke-prone SHR, plasma renin, angiotensinogen, and Ang II do not cosegregate with elevated blood pressure.…”

Is Gene Therapy for Hypertension Possible?

“…Effective AS ODN have been targeted to mRNA for renin, angiotensinogen, ACE, and AT 1 -R. They have been tested in 3 different models of hypertension, including the genetic model (SHR), [21][22][23][24] a surgical model (2-kidney, 1 clip hypertension [2K1C]), 25 and an environmental stress model (coldinduced hypertension) 26 (Table 1). In every case in which we have tested the selected AS oligomers, there have been consistent biological signs of gene knockdown.…”

“…Beneficial effects on the heart and kidneys still need to be tested. The naked AS oligonucleotide is effective, but cationic liposome carriers 22,23 or asialoglycoprotein 24 increases the effectiveness of the AS injected intravenously. The oligonucleotides we used do not appear to be toxic even after repeated injections over months.…”