Cadmium Toxicity Induces Pyroptosis In Macrophages

Cadmium (Cd) toxicity contributes to chronic obstructive pulmonary disease (COPD) and other smoking-related lung disease. Caspase-1, gasdermin D (GSDMD), and gasdermin E (GSDME) are key proteins responsible for the initiation of pyroptosis. We hypothesize Cd induces host immune and inflammatory cell death in a macrophage model (RAW 264.7). RAW 264.7 macrophages (derived from Abelson leukemia virus) were cultured and plated in 4 groups of triplicates. Each triplicate received 0,5,10, or 15μM of CdCl2. After 24h cells were collected and lysed. Western blot analysis was then run for gasdermin D (GSDMD) and gasdermin E (GSDME). A Caspase-1 Activity Kit (ImmunoChemistry Technologies) was used with fluorescent inhibitor of caspase (FLICA) staining to assess caspase-1 activity in live cells. A dose curve shows increasing cytotoxicity as Cd concentration increases with 0% cell viability at 100μM Cd. The doses that hover around 50% cell viability were the experimental 5,10. And 15 μM. Western Blot data show significant cleavage of GSDMD at 5 μM Cd and significant cleavage of GSDME at 15uM Cd. Fluorescence microscopy revealed increased caspase-1 activity in treated macrophages. Cd toxicity induces pyroptosis in macrophages via upregulation of canonical inflammasomes and caspase-1, suggesting mechanistic targets to reduce the adverse effects of Cd toxicity on the immune system. Future studies will aim to characterize the mechanisms of Cd toxicity in other programmed cell death pathways.