Defining the Immune Responses for SARS-CoV-2-Human Macrophage Interactions

Area of Science:

• Immunology
• Virology
• Cell Biology

Background:

• Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection triggers host innate immune responses, contributing to severe COVID-19 and acute respiratory distress syndrome (ARDS).
• Mononuclear phagocytes (MPs), including monocytes, macrophages, and dendritic cells, are activated by SARS-CoV-2, playing key roles in systemic inflammation and end-organ damage.

Approach:

• Investigated SARS-CoV-2 interactions with human monocyte-derived macrophages using transcriptomic and proteomic profiling.
• Examined the expression of the SARS-CoV-2 receptor, angiotensin-converting enzyme 2 (ACE2), during monocyte-macrophage differentiation.
• Assessed the impact of viral exposure on macrophage pro-inflammatory cytokine, chemokine, and type I interferon (IFN) activity.

Key Points:

• Angiotensin-converting enzyme 2 expression increased with macrophage differentiation but did not support productive SARS-CoV-2 infection.
• Macrophage exposure to SARS-CoV-2 induced significant pro-inflammatory cytokine and chemokine release.
• Type I interferon (IFN) activity was attenuated following SARS-CoV-2 exposure, alongside dysregulated IFN-related innate immune signaling pathways.

Conclusions:

• SARS-CoV-2 infection elicits a potent innate immune response characterized by a pro-inflammatory cytokine storm.
• This inflammatory response in macrophages contributes to end-organ damage observed in severe COVID-19.
• Understanding SARS-CoV-2-MP interactions is crucial for addressing COVID-19 pathogenesis and developing therapeutic strategies.