PGD and COVID-19: However, we found that CD16+ monocytes in patients with severe COVID-19 expressed higher levels of a PPP-related gene (PGD) and an arginine, alanine, aspartate and glutamate metabolism-related gene (GLUL), as well as lower levels of glycolysis-related genes (HK1, PFKL, PGK1, and ENO1), a fatty acid-related gene (CPT1A) and lysine metabolism-related genes (ASH1L and NSD1), an arginine and proline metabolism-related gene (CKB), and a tyrosine and phenylalanine metabolism-related gene (COMT) (Figure 2B).