TLR2 promotes traumatic deep venous thrombosis of the lower extremity following femoral fracture by activating the NF‑κB/COX‑2 signaling pathway in rats

Abstract

Endothelial cells (ECs) are crucial for maintaining the integrity of blood vessel walls and reducing thrombosis. Deep venous thrombosis (DVT) is a common thrombotic disease and its diagnosis and treatment remain at the stage of coagulation function examination and post-onset treatment. Thus, identifying the pathogenesis of DVT is important. The present study investigated the significance of the Toll-like receptor 2 (TLR2)/nuclear factor kappa B (NF-κB)/cyclooxygenase-2 (COX-2) signaling pathway in a human umbilical vein EC (HUVECs) oxygen glucose deprivation (OGD) model and femoral fractures were induced in anesthetized rats using a quantifiable impact device delivering 5 J of energy to each side of the proximal outer thigh, followed by external fixation with a hip spica cast to create a traumatic deep venous thrombosis (TDVT) animal model. Rats were subjected to quantitative impact fixation to establish a TDVT model. The rats were treated with a TLR2 agonist (Pam3CSK4) and a TLR2 inhibitor (C29) via intraperitoneal injection and thrombus formation was examined. HUVECs were subjected to OGD and treated with Pam3CSK4 or C29 and cell viability and apoptosis were assessed. Western blotting, immunofluorescence and reverse transcription-quantitative PCR were used to examine the inflammatory responses and signaling pathways. In vivo experiments showed that Pam3CSK4 promoted thrombus formation and increased the mRNA and protein expression of NF-κB, COX-2, Tissue factor (TF), IL-6 and P-selectin compared with the model and C29 groups. In vitro experiments showed that Pam3CSK4 treatment resulted in a higher number of apoptotic cells than C29 treatment and that it increased the levels of NF-κB, COX-2, IL-6 and P-selectin, whereas C29 decreased them. Thus, TLR2 promotes the inflammatory response in EC through the NF-κB/COX-2 signaling pathway, which may lead to EC apoptosis and the occurrence of TDVT.