Nalp3 inflammasome is activated and required for vascular smooth muscle cell calcification

The calcification of blood vessels correlates with increased morbidity and mortality in patients with atherosclerosis, diabetes, and end-stage kidney disease. Increased inflammasome activation has been shown to play an important role in the pathogenesis of atherosclerosis. However, the contribution of inflammasome activation on the development of vascular calcification has not been investigated.

β-Glycerophosphate (β-GP) was used as a procedure to induce extensive artery calcification in primary vascular smooth muscle cells (VSMCs). Analysis of the levels of Nalp3 inflammasome complex was performed by quantitative real-time PCR and western blotting. The effect of Nalp3 deficiency on VSMC calcification was examined after transfecting Nalp3 siRNA into cultured VSMCs.

We demonstrated for the first time that the mRNA levels of Nalp3 inflammasome complex including Nalp3, ASC and caspase1 were upregulated in calcifying VSMCs, resulting in increased IL-1β secretion. Inhibition of inflammasome activation by Nalp3 RNA interference reduced IL-1β secretion and inhibited VSMC calcification. Further analysis of clinical popliteal artery specimens showed an upregulation of inflammasome complex mRNA levels (4/5) and caspase1 activity (5/5) compared with their non-calcified adjacent tissues, indicating that Nalp3 inflammasome was tightly correlated with arterial calcification disease.

Our findings indicate that activation of the Nalp3-mediated inflammatory response pathway is an important venue associated with host response and pathogenesis of VSMC calcification.