As detailed in Section 3, S1PR1 and S1PR3 are major barrier-regulatory G protein–coupled receptors highly expressed in lung ECs (121).The genes encoding the S1P1 receptor or S1P1,the critical barrier-promoting receptor (122), and the inflammation-promoting S1P3 receptor, S1P3, a potential ARDS biomarker (77), exhibit several SNPs overrepresented in Blacks with severe asthma and ARDS (123). Here, S1PR1 is linked to acute respiratory distress syndrome.