This unremitting inflammation was accompanied by a continued rise in lung HA content with marked intrapulmonary HA accumulation and respiratory failure in CD44 deficient mice.20 The results of Noble et al are of particular interest given our prior observations of HA accumulation in the BALF, blood, and tissue in lung recipients with CLAD.10 In this prior work, we found recipients with CLAD have a far greater mean BALF HA content (107.91 ng/mL) than that observed with AR (24.89 ng/mL) in the current study. Here, CD44 is linked to respiratory failure.