Gamma Radiation Induce Inflammasome Signaling and Pyroptosis in Microvascular Endothelial Cells

The extend to the clinical benefit of radiation therapy is the inability to eliminate only cancer cells and destroy normal cells such as microvascular endothelial in the vascular niche and turn induced-inflammasome signaling and cell death. These unfortunate injuries generated by ionizing radiation alter the therapeutic window and result in the re-occurrence of the malignancy. Therefore, we engaged in vitro studies by demonstrating radiation-induced inflammasome and cell death in endothelial cells.

The microvascular endothelial cells were cultured in a sterile dish, then kept in a humidifier of 5% at 37°C for 12 hours/more to attain confluence, and exposed at a dose of 1.8Gy/min achieve the coveted amounts except for the control. The cells were harvested 24 hours post-irradiation.

Our findings indicate that gamma radiation activates the NOD-like receptor (NLR) family of NLRP1 and NLRP3 complex in microvascular endothelial cells. These complexes activate the inactive precursor of caspase-1, which cleaved to bioactive caspase -1 and enhances the production of pro-inflammatory cytokines of interleukin-1β and interleukin-18 that induce the dependent pyroptotic, which results in the production of chemokines, tumor necrosis factor-alpha (TNF-α), and high-mobility group protein-1 (HMGB-1). We also discovered the radiation could directly prompt caspase -1, which auto-cleaved to activate gasdermin D to potentiate pyroptosis independently.

Overall, these findings suggested that reducing the unfavorable effect of radiation injuries could be challenging since gamma radiation induces the microvascular endothelial cells to cell death and activates the inflammasome signaling via different pathways.