MMP9 and COVID-19: In conclusion, through pathway and network analyses, our current study demonstrates an aberrant activation of endocrine (e.g., IGF1 and HGF) signaling pathways in the severe cases, as well as their connection to a upregulation of MMP9, a gene that has been implicated in the aberrant activation of neutrophil in severe COVID-19 [7] and mitochondrial dysfunction in diabetic retinopathy and cardiac disease [49,50,51,52].