# Project 1: Mechanisms of innate sensing and pathogenesis of SARS-CoV-2

> **NIH NIH U54** · JOHNS HOPKINS UNIVERSITY · 2020 · $815,251

## Abstract

Understanding immune responses that contribute to severe COVID-19 is essential to identify patients likely to
become critically ill and to discern which pathways to target for therapeutic intervention. The inflammasome is
an antiviral and proinflammatory pathway activated by many viruses, but its role in COVID-19 has not been
defined fully. Inflammasome activation results in an inflammatory type of cell death called pyroptosis as well as
the release of proinflammatory cytokines that include interleukin (IL)-18. Inflammasome cytokines are central to
viral control, but excessive or prolonged activation enhances pathogenesis of numerous respiratory virus
infections, including avian influenza and SARS-CoV-1. Having extensively studied the role of inflammasome
cytokines in the pathogenesis of multiple other viral infections, we measured IL-18 and 36 other cytokines and
chemokines in plasma from patients with COVID-19. While most were not significantly different in COVID-19,
IL-18 and IL-1 receptor antagonist (RA) levels are elevated in intubated patients with COVID-19 versus non-
intubated COVID-19 and hospitalized influenza patients. Incubation of human macrophages with SARS-CoV-2
in vitro produced IL-18, IL-1, IL-RA, IL-6, and IL-8. We used a human macrophage cell-line with various
inflammasome genes disrupted to show that caspase-1 and NLRP3 are required for SARS-CoV-2 activation of
the inflammasome. We will establish the mechanism by which SARS-CoV-2 activates the inflammasome and
determine how inhibition of this pathway alters innate immune signaling using a panel of endocytosis inhibitors,
macrophage cell lines with specific inflammasome and other innate sensing genes disrupted, and specific
inhibitors of innate sensing in primary human macrophages. Early investigations suggest that antibodies (Abs)
modulate innate sensing of SARS-CoV-2. To test whether Abs produced during COVID-19 alter innate
signaling, we will incubate SARS-CoV-2 with monoclonal Abs or patient sera, inoculate primary or immortalized
macrophages, and measure supernatant cytokines. To investigate cellular function, we developed a flow
cytometry-based platform that enables single cell analysis of traditional cell surface markers combined with
intracellular staining for proteins involved in metabolic programming. Using this platform, we identified myeloid
derived suppressor cells (MDSCs) with distinct metabolic profiles that correlated with severe COVID-19.
Prolonged inflammation induces MDSCs in cancer, obesity, and chronic infections. We will use single cell RNA
sequencing to characterize these novel MDSCs and assess how cytokines produced in COVID-19 regulate
MDSC metabolic programming. The overall goal is to define the mechanism by which SARS-CoV-2 activates
inflammatory pathways, Ab modulation, the role of MDSCs, and how they intersect to mediate SARS-CoV-2
immune control and pathology. This will identify targets for therapeutic intervention that minimize inflammatory
patho...

## Key facts

- **NIH application ID:** 10221908
- **Project number:** 1U54CA260492-01
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** ANDREA L COX
- **Activity code:** U54 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $815,251
- **Award type:** 1
- **Project period:** 2020-09-30 → 2022-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10221908

## Citation

> US National Institutes of Health, RePORTER application 10221908, Project 1: Mechanisms of innate sensing and pathogenesis of SARS-CoV-2 (1U54CA260492-01). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10221908. Licensed CC0.

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