Neutral sphingomyelinase 2 (nSMase2) catalyzes the formation and release of extracellular vesicles (EVs) . Human nSMase2 catalyzes the hydrolysis of sphingomyelin to phosphorylcholine and ceramide. DPTIP, a potent brain penetrant neutral sphingomyelinase 2 (nSMase2; IC50=30 nM) inhibitor, regulates astrocyte-peripheral immune communication following brain inflammation. DPTIP is an inhibitor of extracellular vesicle release in primary glial cells and in vivo. Moreover, DPTIP dose-dependently inhibits extracellular vesicle release in primary astrocyte cultures.
DPTIP exhibits non-competitive mode of inhibition and shows selectivity for nSMase2 versus related enzymes. This inhibition leads to a reduction of cytokine upregulation in liver and attenuation of the infiltration of immune cells into the brain. Moreover, in a mouse model of brain inflammation, DPTIP potently inhibits IL-1β-induced astrocyte-derived extracellular vesicle release, peripheral cytokine upregulation and neutrophil migration into the brain.
DPTIP inhibits extracellular vesicle release from primary astrocytes. Treatment with DPTIP prevented astrocyte activation in response to serum starvation, while the inactive analog failed to prevent astrocyte activation. DPTIP shows metabolic stability in mouse and human liver microsomes and inhibits biomarkers of brain inflammation in vivo. In a mouse model of brain injury conducted in GFAP-GFP mice, DPTIP potently (10 mg/kg; i.p.) inhibits IL-1β-induced astrocyte-derived extracellular vesicle release. In addition, DPTIP exhibits plasma exposure and brain penetration after systemic dosing in mice.
In summary, DPTIP is a potent nSMase2 inhibitor. DPTIP is an inhibitor of extracellular vesicle release in primary glial cells and in vivo. Furthermore, DPTIP acts as a probe in animal models of disease associated with extracellular vesicle dysregulation.