NF‐κB affected the serum levels of TNF‐α and IL‐1β via activation of the MAPK/NF‐κB signaling pathway in rat model of acute pulmonary microthromboembolism

Abstract Pulmonary thromboembolism caused by thrombi blocking major pulmonary artery and its branches, is a frequently encountered phenomenon and an important cause of high morbidity and mortality in lung diseases and may develop into persistent pulmonary hypertension (PH). Nuclear factor‐κB (NF‐κB) signaling pathway had been reported participated in the formation and development of PH by promoting inflammatory response. The aim of this study was to investigate the effects of NF‐κB activation on the serum levels of tumor necrosis factor α (TNF‐α) and interleukin‐1β (IL‐1β) in acute pulmonary microthromboembolism (APMTE) rats. Rats were randomized into five groups. APMTE group received jugular vein injection of autologous thrombus, while control group rats received normal saline injection. Pulmonary hemodynamic parameters were measured through ECHO‐guided transthoracic puncture. Pulmonary vascular morphological changes were analyzed by HE. The expression changes of NF‐κB and serum TNF‐α、IL‐1β levels were detected by enzyme‐linked immunosorbent assay. Protein expression of the MAPK/NF‐κB signaling pathway including p‐IκBα, p‐p38 MAPK, p‐NF‐κB p65, IκBα, p38 MAPK, and NF‐κB p65 was determined using western blot analysis. Compared with control group, the expression of NF‐κB in lung tissue and the levels of serum TNF‐α and IL‐1β rats were higher, a significant reduction in IκBα and elevation in the phosphorylation of IκBα, p38 MAPK, and NF‐κB p65 were found in APMTE group rats. And UK administration reversed the APMTE‐induced increase in TNF‐α, IL‐1β, p‐IκBα, p‐MAPK, and p‐NF‐κB protein. Furthermore, the levels of NF‐κB, TNF‐α, and IL‐1β were positively correlated with mean pulmonary artery. And the levels of TNF‐α and IL‐1β were positively correlated with NF‐κB. These findings suggest that the activation of MAPK/NF‐κB pathway as a critical driver of increasing TNF‐α and IL‐1β level in APMTE rats and UK exerted protective effects against APMTE‐induced PH may be related to the downregulation of the MAPK/NF‐κB signaling pathway.