CCL2 and COVID-19: In this study, we revealed that cytokine storms released by macrophages promoted TEX via CCL2-CCR2, CCL3-CCR1, CCL3-CCR5, CCL4-CCR5, CCL4L2-VSIR, and CCL3L1-CCR1 axes, that are associatied with poor prognosis of COVID-19.