Characterization of ACE Inhibitors and AT1R Antagonists with Regard to Their Effect on ACE2 Expression and Infection with SARS-CoV-2 Using a Caco-2 Cell Model

Blood-pressure-lowering drugs are proposed to foster SARS-CoV-2 infection by pharmacological upregulation of angiotensin-converting enzyme 2 (ACE2), the binding partner of the virus spike (S) protein, located on the surface of the host cells. Conversely, it is postulated that angiotensin–renin system antagonists may prevent lung damage caused by SARS-CoV-2 infection, by reducing angiotensin II levels, which can induce permeability of lung endothelial barrier via its interaction with the AT1 receptor (AT1R). Methods: We have investigated the influence of the ACE inhibitors (lisinopril, captopril) and the AT1 antagonists (telmisartan, olmesartan) on the level of ACE2 mRNA and protein expression as well as their influence on the cytopathic effect of SARS-CoV-2 and on the cell barrier integrity in a Caco-2 cell model. Results: The drugs revealed no effect on ACE2 mRNA and protein expression. ACE inhibitors and AT1R antagonist olmesartan did not influence the infection rate of SARS-CoV-2 and were unable to prevent the SARS-CoV-2-induced cell barrier disturbance. A concentration of 25 µg/mL telmisartan significantly reduced the virus replication rate. Conclusion: ACE inhibitors and AT1R antagonist showed neither beneficial nor detrimental effects on SARS-CoV-2-infection and cell barrier integrity in vitro at pharmacologically relevant concentrations.

Exploiting Knowledge on Structure–Activity Relationships for Designing Peptidomimetics of Endogenous Peptides

Endogenous peptides are important mediators in cell communication, being consequently involved in many physiological processes. Their use as therapeutic agents is limited due to their poor pharmacokinetic profile. To circumvent this drawback, alternative diverse molecules based on the stereochemical features that confer their activity can be synthesized, using them as guidance; from peptide surrogates provided with a better pharmacokinetic profile, to small molecule peptidomimetics, through cyclic peptides. The design process requires a competent use of the structure-activity results available on individual peptides. Specifically, it requires synthesis and analysis of the activity of diverse analogs, biophysical information and computational work. In the present work, we show a general framework of the process and show its application to two specific examples: the design of selective AT1 antagonists of angiotensin and the design of selective B2 antagonists of bradykinin.

5894The biased angiotensin receptor 1-ligand TRV023 attenuates atherosclerosis through selective inhibition of Gq-mediated signaling

Introduction Antagonists of the angiotensin II receptor type 1 (AT1) belong to the most successful treatments of cardiovascular disease. Besides G-protein-independent β-arrestin-mediated signaling, AT1 preferencially signals via G-proteins of the families Gq and G13. Conventional AT1-antagonists equally inhibit all of these pathways, even though the beneficial effects are generally attributed to the inhibition of Gq only. While data on β-arrestin signaling in the vascular disease context are conflicting, we found an excessive pathological remodeling and dramatic exacerbation of atherosclerosis upon interference with G13-mediated signaling. Against this background, selective inhibition of the Gq-pathway seems desirable. Thus, based on the novel concept of ligand-biased signaling, we aimed to identify biased AT1-antagonists that selectively inhibit the Gq-pathway, while allowing for continued signaling through G13. Methods and results We systematically profiled known AT1-ligands and identified the angiotensin analogue Sar-Arg-Val-Tyr-Lys-His-Pro-Ala-OH (TRV023) as a Gq-selective AT1-antagonist: TRV023 has recently been described as a β-arrestin-biased ligand; however its signaling properties regarding distinct G-protein isoforms have never been defined. Indeed, using bioluminescence reporter assays, we found that TRV023 inhibits Gq-signaling at least as potently as losartan and telmisartan, but unlike the conventional antagonists, it does not impair β-arrestin-signaling (Fig. 1A). Intriguingly, while the conventional antagonists effectively inhibited induction of a G13 luciferase reporter, TRV023 did not significantly interfere with G13-mediated signaling, indicating Gq-selective antagonistic effects. According to our hypothesis, these G-protein-biased signaling properties could render TRV023 superior to conventional antagonists in the treatment of vascular disease. In order to test this hypothesis, we exposed ApoE-deficient mice to one of two different atherosclerosis models: A novel model for accelerated atherosclosis based on partial carotid ligation and western diet, or a conventional atherosclerosis model based on 12 weeks of western diet. Using osmotic pumps, mice were continuously treated with vehicle control, TRV023 or losartan in doses that proved equipotent with respect to blood pressure lowering effects. In line with our hypothesis, TRV023 but not losartan significantly attenuated plaque development in both atherosclerosis models (Fig. 1B). Figure 1 Conclusion Our studies have identified TRV023 as a Gq-biased AT1-antagonist and indicate that selective inhibition of AT1-dependent Gq-mediated signaling by biased ligands may be a promising approach for the treatment of atherosclerosis. Hence, TRV023 qualifies as a drug candidate, particularly since it has already proven to be safe and well-tolerable in clinical phase I and II trials in the context of acute heart failure. Acknowledgement/Funding Else Kröner-Fresenius-Foundation