HMGB1 and acute respiratory distress syndrome: At 6 h PI, HMGB1 levels in swine that developed ARDS significantly increased (p < 0.05) compared with those swine that did not develop ARDS (Figure 2A); overall, serum HMGB1 significantly increased in swine with ARDS compared with those swine that did not develop ARDS (Figure 2A).