PLA2G15 and pulmonary alveolar proteinosis: Mechanistically, Rituximab therapy ameliorates the lipid metabolism of AM in patients with PAP, as demonstrated by the upregulation of key lipid metabolism molecules, including PPAR-γ, ABCG1, and lysosomal phospholipase A2 (LPLA2), a critical enzyme for surfactant degradation (132).