CTSL and viral infectious disease: In addition, Dex has been shown to polarize macrophages toward the M2 phenotype,135 and higher CTSL expression in M1 macrophages than in M2 macrophages has been observed.134 Overall, upon airway administration, Dex and ALN locally regulate endosomes of AMs and prevent release of SARS-CoV-2 RNA from endosomes, thus achieving the goal of preventing or controlling viral infection at a very early stage (Fig. 4b).