PXDN and COVID-19: Tissue skeleton-associated proteins including proteins involved in collagen fibril organization (CRTAP, TNXB, COL1A2, COL5A1, LUM, COL14A1, PXDN, DPT, and FMOD) and elastic fiber assembly (MFAP4, TNXB, LTBP4, and FBLN5) were found to be downregulated in the COVID-19 patient heart tissues.