Nf-Kappa B/I Kappa B Alpha Signaling Pathways Are Essential For Resistance To Heat Stress-Induced Ros Production In Pulmonary Microvascular Endothelial Cells

The results of a previous study demonstrated that heat stress (HS) triggered oxidative stress, which in turn induced the apoptosis of epithelial cells. These results uncovered a novel mechanism underlying the activation of NF-kappa B in primary human umbilical vein endothelial cells. The present study aimed to further investigate the role of NF-kappa B/I kappa B alpha signaling pathways in the inhibition of HS-induced reactive oxygen species (ROS) generation and cytotoxicity in endothelial cells. The results of the present study demonstrated that HS triggered a significant amount of NF-kappa B and I kappa B alpha nuclear translocation without I kappa B alpha degradation in a time-dependent manner. Mutant constructs of I kappa B alpha phosphorylation sites (Ser32, Ser36) were employed in rat pulmonary microvascular endothelial cells (PMVECs). Cell Counting Kit-8 assays demonstrated that both the small interfering (si)RNA-mediated knockdown of p65 and I kappa B alpha mutant constructs significantly decreased cell viability and aggravated ROS accumulation in HS-induced rat PMVECs compared with the control. Additionally, western blot analysis revealed that p65 siRNA attenuated the protein expression of I kappa B alpha. However, I kappa B alpha mutant constructs failed to attenuate NF-kappa B activation and nuclear translocation, indicating that I kappa B alpha-independent pathways contributed to NF-kappa B activity and nucleus translocation in a time-dependent manner following HS. Collectively, the results of the present study suggested that the NF-kappa B/I kappa B alpha pathway was essential for resistance to HS-induced ROS production and cytotoxicity in rat PMVECs, and that it could be a potential therapeutic target to reduce the mortality and morbidity of heat stroke.