Long-term exposure to silica nanoparticles induces cardiac hypertrophy through the pyroptosis pathway

Although acute cardiovascular effects of silicon nanoparticles (SiNPs) have been reported, the long-term impact of human-relevant exposure on cardiac hypertrophy remains unclear. The rats were randomly assigned to 2 groups: The SiNPs exposure group and the control group, receiving intratracheal instillations of SiNPs suspension or saline, respectively, once a week for 6 mo (24 doses total). Both groups then underwent a 6-mo recovery period without further intervention to assess postexposure effects. The results revealed significant hypertrophic remodeling, as evidenced by increased left ventricular anterior wall thickness, systolic dysfunction (reduced FS%), and diastolic impairment (prolonged IVRT and IVCT). Ultrastructural analysis indicated mitochondrial disorganization and swelling in myocardial tissue. At the molecular level, SiNPs exposure upregulated hypertrophic markers (β-MHC, ANP), inflammatory cytokines (IL-18, IL-1β), and oxidative stress markers MDA, while reducing SOD levels. Both classical (Caspase-1) and nonclassical (Caspase-4, Caspase-5) pyroptosis pathways were activated, with elevated levels of Cleaved-Caspase-1, ASC, and N-GSDMD. This study is the first to identify nonclassical pyroptosis as a contributor to SiNPs-induced cardiac hypertrophy. Importantly, cardiac hypertrophy was significantly reduced after exposure cessation, with no further pyroptosis-mediated inflammatory damage observed. These findings underscore the importance of stricter public health regulations to limit SiNPs exposure, given its long-term cardiovascular risks.