CRISPR/Cas9 Mediated Deletion of the Angiotensinogen Gene Reduces Hypertension: A Potential for Cure?

Abstract

Hypertension is a major contributor to the global burden of disease. Unfortunately, hypertension is controlled in less than one-fifth of patients worldwide due to either failure to treat or lack of compliance to medication. An ideal therapy would be administered one time only and yield lifelong blood pressure control. We investigated our hypothesis that CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeat–associated 9)-mediated disruption of a key gene in the renin-angiotensin system, AGT (angiotensinogen), specifically in the liver, would result in sustained and possibly lifelong reduction in blood pressure. We demonstrated in vitro that the CRISPR/Cas9 system led to a significant reduction in AGT expression in hepatocytes. Delivery of the CRISPR/Cas9 system into the liver via the hepatocyte-targeting adeno-associated virus 8 reduced both AGT expression (40% decrease) and circulating AGT levels (30% decrease). In the SHR (spontaneously hypertensive rat) model of hypertension, CRISPR/Cas9-mediated loss of AGT expression reduced blood pressure in adult animals with established hypertension and prevented the spontaneous development of hypertension in young SHR. Moreover, reductions in blood pressure were prolonged and sustained up to 1 year of follow-up. In addition, the partial disruption of the hepatic AGT gene was sufficient to control hypertension but did not affect the homeostatic response to cardiovascular stress such as sodium depletion and furosemide. In summary, we have demonstrated that targeting the CRISPR/Cas9 system to hepatic AGT results in sustained reduction of blood pressure and is a potential therapy to achieve sustained and possibly lifelong control of human hypertension.

Basic Principles and Clinical Applications of CRISPR-Based Genome Editing

“…Additionally, another exciting possibility is on the horizon: treating common, non-Mendelian disorders, such as osteoarthritis, 70 hypertension, 71 inflammatory skin disorders, 72 and Alzheimer’s disease, 73 74 with CRISPR-based genome editing. These studies attempt to prevent the development or progression of multifactorial diseases by targeting genes with critical roles in disease pathophysiology.…”

“… 70 Angiotensinogen, a key player in the renin-angiotensin system that regulates blood pressure, was deleted to prevent the development of hypertension in spontaneous hypertensive rats. 71 The NLRP3 inflammasome, which is responsible for the activation of inflammatory responses, was disrupted in order to alleviate common inflammatory skin disorders, such as psoriasis or atopic dermatitis, in mouse models. 72 Finally, beta-secretase 1, which is required for the production of amyloid beta proteins, was targeted to suppress cognitive deficits in mouse models of Alzheimer’s disease.…”

Angiotensinogen Suppression: A New Tool to Treat Cardiovascular and Renal Disease

“…Currently, the GalNAc-conjugated ASO (IONIS-AGT-L Rx , Ionis Pharmaceuticals) phase I/II clinical trials have been completed, 26 and GalNAc-conjugated siRNA (Zilebesiran [ALN-AGT], Alnylam Pharmaceuticals) phase I/II clinical trials will be completed soon. The third approach to inhibit the formation of liver-derived AGT is to utilize gene editing technology, such as the clustered regularly interspaced short palindromic repeats/ clustered regularly interspaced short palindromic repeat-associated protein 9 (CRISPR/Cas9) gene editing system recently proposed by Sun et al 27 In contrast to the RNA-based therapeutics which inhibit the formation of liver-derived AGT for weeks to months, this approach results in the permanent disruption of the target gene, that is, it is irreversible. Although this approach is still in its infancy, initial studies in SHR suggest that partial deletion (40%) of the hepatic AGT gene is sufficient to prevent the development of hypertension in this model.…”

“…Although this approach is still in its infancy, initial studies in SHR suggest that partial deletion (40%) of the hepatic AGT gene is sufficient to prevent the development of hypertension in this model. 27 …”

Can Gene Targeting Be Used to Cure Hypertension?

“…Such a prospect is advanced by Dzau and colleagues in an article appearing in this issue of the Journal. 3 There they assert that "An ideal therapy would be administered one time only and yield life-long blood pressure control" and suggest gene targeting as a logical approach to such a therapy. After acknowledging that antisense, siRNA and shRNA gene targeting strategies already have been shown to be effective in lowering blood pressure, they point out that these methods still require repeated treatments to maintain a hypotensive effect, so are not a cure in the usual sense of the word.…”