Heparin-Binding Protein Aggravates Acute Lung Injury in Septic Rats by Promoting Macrophage M1 Polarization and NF-κB Signaling Pathway Activation

OBJECTIVE: Heparin-binding protein (HBP) plays an important role in sepsis and is a prognostic biomarker in patients with sepsis, but the role of HBP in the pathogenesis of sepsis-associated acute lung injury (ALI) remains unclear. This study aimed to investigate the role of HBP in sepsis-induced ALI and its underlying molecular mechanisms. METHODS: The cecal ligation and puncture (CLP) model was used to induce ALI in mice and randomly divided into 4 groups: control group, CLP (rats treated with cecal ligation and puncture), HBP (rats treated with CLP and HBP injection), and HBP + UFH (rats treated with CLP and injection of HBP and unfractionated heparin). Subsequently, HBP expression in rat serum and lung tissues was detected by qRT-PCR, edema and pathological changes in lung tissue by lung wet-to-dry weight ratio (W/D) and HE staining, myeloperoxidase (MPO) and superoxide dismutase (SOD) activities in lung tissues by detection kits. Additionally, ELISA and western blot were applied for the determination of IL-6, TNF-α, and IL-1β expression in rat bronchoalveolar lavage fluid, and iNOS, Arg-1, Mrc1, NF-κBp65, IKKα, IκBα, and p-IκBα expression in lung tissues. RESULTS: The expression levels of HBP in serum and lung tissues of rats in the HBP group were significantly increased, the lung tissues were severely injured, accompanied by a significant increase in MPO activity but a significant decrease in SOD activity, and the levels of IL-6, TNF-α, and IL-1β in bronchoalveolar lavage fluid were significantly increased. In addition, the expression levels of iNOS, NF-κB p65, IKKα, and p-IκBα in the lung tissues of rats in the HBP group were significantly increased, while the addition of unfractionated heparin reversed the above results. CONCLUSION: HBP aggravates ALI in septic rats, and its mechanism may be related to the promotion of macrophage M1 polarization and activation of the NF-κB signaling pathway.