ACE2: A Dilemma in Regulating SARS-CoV-2 Infection and its Metabolic Complications

Summary The emergence of SARS-CoV-2 has resulted in >90,000 infections and >3,000 deaths. Coronavirus spike (S) glycoproteins promote entry into cells and are the main target of antibodies. We show that SARS-CoV-2 S uses ACE2 to enter cells and that the receptor-binding domains of SARS-CoV-2 S and SARS-CoV S bind with similar affinities to human ACE2, correlating with the efficient spread of SARS-CoV-2 among humans. We found that the SARS-CoV-2 S glycoprotein harbors a furin cleavage site at the boundary between the S1/S2 subunits, which is processed during biogenesis and sets this virus apart from SARS-CoV and SARS-related CoVs. We determined cryo-EM structures of the SARS-CoV-2 S ectodomain trimer, providing a blueprint for the design of vaccines and inhibitors of viral entry. Finally, we demonstrate that SARS-CoV S murine polyclonal antibodies potently inhibited SARS-CoV-2 S mediated entry into cells, indicating that cross-neutralizing antibodies targeting conserved S epitopes can be elicited upon vaccination.

The COVID-19 pandemic is a major threat to global health 1 for which there are limited medical countermeasures 2,3 . Moreover, we currently lack a thorough understanding of mechanisms of humoral immunity 4 . From a larger panel of human monoclonal antibodies (mAbs) targeting the spike (S) glycoprotein 5 , we identified several that exhibited potent neutralizing activity and fully blocked the receptor-binding domain of S (SRBD) from interacting with human ACE2 (hACE2). Competition-binding, structural, and functional studies allowed clustering of the mAbs into classes recognizing distinct epitopes on the SRBD as well as distinct conformational states of the S trimer. Potent neutralizing mAbs recognizing non-overlapping sites, COV2-2196 and COV2-2130, bound simultaneously to S and synergistically neutralized authentic SARS-CoV-2 virus. In two mouse models of SARS-CoV-2 infection, passive transfer of either COV2-2196 or COV2-2130 alone or a combination of both mAbs protected mice from weight loss and reduced viral burden and inflammation in the lung. In addition, passive transfer of each of two of the most potently ACE2 blocking mAbs (COV2-2196 or COV2-2381) as monotherapy protected rhesus macaques from SARS-CoV-2 infection. These results identify protective epitopes on SRBD and provide a structure-based framework for rational vaccine design and the selection of robust immunotherapeutics.

Microalbuminuria and hypertension are risk factors for diabetic nephropathy. Blockade of the renin-angiotensin system slows the progression to diabetic nephropathy in patients with type 1 diabetes, but similar data are lacking for hypertensive patients with type 2 diabetes. We evaluated the renoprotective effect of the angiotensin-II-receptor antagonist irbesartan in hypertensive patients with type 2 diabetes and microalbuminuria. A total of 590 hypertensive patients with type 2 diabetes and microalbuminuria were enrolled in this multinational, randomized, double-blind, placebo-controlled study of irbesartan, at a dose of either 150 mg daily or 300 mg daily, and were followed for two years. The primary outcome was the time to the onset of diabetic nephropathy, defined by persistent albuminuria in overnight specimens, with a urinary albumin excretion rate that was greater than 200 microg per minute and at least 30 percent higher than the base-line level. The base-line characteristics in the three groups were similar. Ten of the 194 patients in the 300-mg group (5.2 percent) and 19 of the 195 patients in the 150-mg group (9.7 percent) reached the primary end point, as compared with 30 of the 201 patients in the placebo group (14.9 percent) (hazard ratios, 0.30 [95 percent confidence interval, 0.14 to 0.61; P< 0.001] and 0.61 [95 percent confidence interval, 0.34 to 1.08; P=0.081 for the two irbesartan groups, respectively). The average blood pressure during the course of the study was 144/83 mm Hg in the placebo group, 143/83 mm Hg in the 150-mg group, and 141/83 mm Hg in the 300-mg group (P=0.004 for the comparison of systolic blood pressure between the placebo group and the combined irbesartan groups). Serious adverse events were less frequent among the patients treated with irbesartan (P=0.02). Irbesartan is renoprotective independently of its blood-pressure-lowering effect in patients with type 2 diabetes and microalbuminuria.