Macrophage Polarization in Viral Infectious Diseases: Confrontation with the Reality

The role of macrophages in viral infections is well documented. Their activation status also called macrophage polarization categorized by the dichotomy of M1 and M2 phenotype remained poorly investigated. Recent studies have shown the complexity of macrophage polarization in response to viral infection and the limits of its use in infected individuals. The aim of this chapter is to reappraise the concept of macrophage polarization in viral infectious diseases, which are more complicated than the models of macrophage-virus interaction. If this concept has been largely used to describe activation status of myeloid cells in experimental conditions, it has to be assessed in light of high-throughput technologies at molecular and phenotypic levels. We update knowledge on macrophage polarization in viral infectious diseases with a special attention for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection leading to coronavirus disease (COVID-19). Hence, we propose an overview of the concept of macrophages as targets for therapeutic intervention in viral infectious disease. Finally, we tempted to focus our approach on patient investigation restricting the use of in vitro experiments and animal models to mechanistic questions