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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‑κB in primary human umbilical vein endothelial cells. The present study aimed to further investigate the role of NF‑κB/IκBα 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‑κB and IκBα nuclear translocation without IκBα degradation in a time‑dependent manner. Mutant constructs of IκBα 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 IκBα 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 IκBα. However, IκBα mutant constructs failed to attenuate NF‑κB activation and nuclear translocation, indicating that IκBα‑independent pathways contributed to NF‑κB activity and nucleus translocation in a time‑dependent manner following HS. Collectively, the results of the present study suggested that the NF‑κB/IκBα 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.

Necroptosis represents a newly defined form of regulated necrosis and participates in various human inflammatory diseases. It remains unclear whether necroptosis is presented in heatstroke-induced lung injury. We show that heat stress(HS) triggered an significant upregulation of receptor-interacting protein 1 (RIP1) and mixed lineage kinase domain-like protein (MLKL) expression in a time-dependent manner, without a significant change of receptor-interacting protein 3 (RIP3). Furthermore, co-immunoprecipitation assays showed that RIP1 binds to RIP3 to form the necrosome in heat stress-induced PMVECs. In vitro, necrostatin-1 (Nec-1) pre-treatment reduced heat stress-induced PMVECs necroptosis, which also inhibited HMGB1 translocation from the nucleus into the cytoplasm. Similarly, inhibition for ERK (PD98059), NF-κB (BAY11-7082) and c-Jun (c-Jun peptide), respectively, also suppressed the HMGB1 cytoplasm translocation. Furthermore, siRNA-mediated RIP1/RIP3 knockdown negatively regulated the release of HMGB1 in HS-induced necroptosis through the ERK, NF-κB, and c-Jun signaling pathways. Our study reveals that HS induces RIP1/RIP3-dependent necroptosis through the MAPK, NF-κB, and c-Jun signaling pathways in PMVECs., Competing Interests: Declaration of competing interest The authors declare no competing financial interests., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The vascular endothelium is a layer of cells lining the inner surface of vessels, serving as a barrier that mediates microenvironment homeostasis. Deterioration of either the structure or function of endothelial cells (ECs) results in a variety of cardiovascular diseases. Previous studies have shown that reactive oxygen species (ROS) is a key factor that contributes to the impairment of ECs and the subsequent endothelial dysfunction. The longevity regulator Sirt1 is a NAD + -dependent deacetylase that has a potential antioxidative stress activity in vascular ECs. The mechanisms underlying the protective effects involve Sirt1/FOXOs, Sirt1/NF- κ B, Sirt1/NOX, Sirt1/SOD, and Sirt1/eNOs pathways. In this review, we summarize the most recent reports in this field to recapitulate the potent mechanisms involving the protective role of Sirt1 in oxidative stress and to highlight the beneficial effects of Sirt1 on cardiovascular functions.