Interestingly, PDE5A, a critical metabolizing enzyme of cGMP that can influence cGMP concentration in vivo [32], was down-expressed in the lungs of IL10B-KO mice and could affect the cGMP–PKG signaling pathway in the LPS-induced ALI model, suggesting that B-cell derived IL-10 may regulate macrophage activation through Pde5a–cGMP–PKG axis. Here, IL10 is linked to acute respiratory distress syndrome.