S1pr2

5 micron sections were stained with hematoxylin and eosin (H&E) to evaluate tissue morphology and air space and Masson’s trichrome stain to evaluate degree of collagen deposition. Immunohistochemistry was performed to detect SK1 (1:200, LS Bio, Seattle, WA, USA), CERS2 (1:1200, OTI3D9, OriGene, Rockville, MD, USA), S1PR1 (1:250, 8B7.1, MilliporeSigma, Burlington, MA, USA), or S1PR2 (1:200, Proteintech, Rosemont, IL, USA) using the Dako Envision + Dual Link secondary detection kit (Agilent Technologies, Santa Clara, CA) and chromogens 3,3’-Diaminobenzidine (DAB; brown; SK1, CERS2, and S1PR1 staining) or AEC (3-amino-9-ethylcarbazole) HRP Substrate (red; S1PR2 staining) following antigen retrieval (SK1, S1PR1 & S1PR2:10 mM citrate buffer (pH 6, Biogenex, San Ramon, CA, USA), and CERS2: Tris/EDTA buffer (pH9, Agilent, Santa Clara, CA, USA)). Representative no antibody staining controls shown in Supplemental Figure 2. Additionally, SK1 (secondary: anti-rabbit AlexaFluor594, Invitrogen,Waltham, MA, USA) and SARS-CoV-2 Nucleocapsid protein (1:1000, clone 05, Sino Biological, Wayne, PA, USA; secondary: anti-mouse AlexaFluor647, Invitrogen) were evaluated via immunofluoresent staining following citrate buffer antigen retrieval.