SMPD1 and immune system disorder: ASM bioactivity in macrophage is responsible for induction or/and augmentation of inflammatory signals and cytokine production, which are likely triggered by bacterial components, e.g., lipopolysaccharide (LPS),20, 21, 22 saturated fatty acid such as palmitic acid,20 or oxidized lipids including LDL.23 Consequently, ASM activity determines macrophage functionalities and participates in inflammatory responses of immune diseases.