IL6 and acute respiratory distress syndrome: In our previous studies, we have demonstrated that [D-Ala2]-dynorphin 1-6 (leytragin), a potent peptide agonist of DOR [32], significantly improves survival rates and inhibits the expression of proinflammatory cytokines (predominantly IL-6) in the lungs of mice with LPS-induced ARDS/ALI [28, 33] (Fig. S1; Supplementary materials).