An ADAM17-Neutralizing Antibody Reduces Inflammation and Mortality While Increasing Viral Burden in a COVID-19 Mouse Model

Abstract

Angiotensin Converting Enzyme 2 (ACE2) is the primary cell entry receptor for SARS-CoV and SARS-CoV-2 viruses. A disintegrin and metalloproteinase 17 (ADAM17) is a protease that cleaves ectodomains of transmembrane proteins, including that of ACE2 and the proinflammatory cytokine TNF-α, from cell surfaces upon cellular activation. We hypothesized that blockade of ADAM17 activity would alter COVID-19 pathogenesis. To assess this pathway, we blocked the function of ADAM17 using the monoclonal antibody MEDI3622 in the K18-hACE2 transgenic mouse model of COVID-19. Antibody-treated mice were healthier, less moribund, and had significantly lower lung pathology than saline-treated mice. However, the viral burden in the lungs of MEDI3622-treated mice was significantly increased. Thus, ADAM17 appears to have a critical anti-viral role, but also may promote inflammatory damage. Since the inflammatory cascade is ultimately the reason for adverse outcomes in COVID-19 patients, there may be a therapeutic application for the MEDI3622 antibody.

Keywords: ADAM19; COVID-19; SARS-CoV-2; inflammation; lung; mouse model; virus.

Figure 1

Treatment of SARS-CoV-2 infected mice with MEDI3622 mAb ameliorates morbidity, but increases viral titers. (A) MEDI3622 mAb treated mice have diminished morbidity compared to saline-treated mice. (B) MEDI3622-treated mice lose significantly less weight than saline-treated controls (represented as the percentage of starting weight at time of infection for each mouse) (2-way ANOVA, *p<0.05). MEDI3622-treated mice have greater relative viral burdens than saline-treated mice as measured by (C) qPCR and (D) plaque assay Mann-Whitney test *p<0.05, **p<0.01, ***p<0.001. This experiment was performed similarly 2 independent times with 10 mice per group.

Figure 2

Damage to lungs in MEDI3622-treated SARS-CoV-2 infected mice is significantly reduced compared to those treated with saline. (A) Histological scores from parameters shown on right were assessed on a 0-3 scale for each parameter for each mouse. (B) Histological scores for each parameter listed in (A) are shown. Mann-Whitney test *p<0.05, **p<0.01, ***p<0.001. (C) Representative sections from each treatment group show differences in lung damage. (D) More mice in the saline-treated group (7 out of 8) had collapsed and fluid filled large bronchi (arrowheads point to examples) than in the MEDI3622-treated group (3 out of 10). This experiment was performed similarly 2 independent times with 10 mice per group. The lung section from the most severely inflamed MEDI3622-treated mouse has fewer collapsed bronchi compared to a representative example from the saline-treated group.

Figure 3

Cytokine transcript levels of MEDI3622-treated mice are higher than or similar to those of control (saline-treated) mice during SARS-CoV-2 infection. RNA was extracted from lungs of mice infected with SARS-CoV-2, described in Figure 1 . (A–F) Transcript levels of genes were measured with quantitative RT-qPCR and normalized against the housekeeping gene β−actin. *p<0.05. This experiment was performed similarly 2 independent times with 10 mice per group.

Figure 4

MEDI3622 blocks soluble TNF-α production in the lung. (A) Mice were treated 48 hours prior to euthanasia with either saline or MEDI3622 by the i.p. route, then 24 hours later injected with either saline (2 mice per route) or 1ug/mouse E. coli LPS (3 mice per route) by either the i.p. or i.t. routes. Only those mice treated i.t. with LPS had TNF-α in BALF 24 hours after injection, and treatment with MEDI3622 blocked this detection. This experiment was performed one time with 2 or 3 mice per group. (B) BALFs were collected on day 4 post-infection from SARS-CoV-2 infected, saline or MEDI3622-treated mice. Infectious viral burden in MEDI3622-treated mice was slightly increased at this interval. (C) BALF from mice treated with MEDI3622 had significantly less TNF-α compared to control mice. *p<0.05. This experiment was performed one time with 7 or 8 mice per group.