CTSL and pyelonephritis: In fact, Puelles et al. [44] found in kidneys from patients who died from COVID-19, SARS-CoV-2 viral load in all kidney compartments examined, especially in glomerular cells, and high levels of RNA for angiotensin-converting enzyme 2 (ACE2), transmembrane serine protease 2 (TMPRSS2), and cathepsin L (CTSL), proteins known to facilitate SARS-CoV-2 kidney infection.