Ulinastatin post-treatment attenuates lipopolysaccharide-induced acute lung injury in rats and human alveolar epithelial cells

Abstract

Ulinastatin (UTI), a serine protease inhibitor, possesses anti-inflammatory properties and has been suggested to modulate lipopolysaccharide (LPS)-induced acute lung injury (ALI). High-mobility group box 1 (HMGB1), a nuclear DNA-binding protein, plays a key role in the development of ALI. The aim of this study was to investigate whether UTI attenuates ALI through the inhibition of HMGB1 expression and to elucidate the underlying molecular mechanisms. ALI was induced in male rats by the intratracheal instillation of LPS (5 mg/kg). UTI was administered intraperitoneally 30 min following exposure to LPS. A549 alveolar epithelial cells were incubated with LPS in the presence or absence of UTI. An enzyme-linked immunosorbent assay was used to detect the levels of inflammatory cytokines. Western blot analysis was performed to detect the changes in the expression levels of Toll-like receptor 2/4 (TLR2/4) and the activation of nuclear factor-κB (NF-κB). The results revealed that UTI significantly protected the animals from LPS-induced ALI, as evidenced by the decrease in the lung wet to dry weight ratio, total cells, neutrophils, macrophages and myeloperoxidase activity, associated with reduced lung histological damage. We also found that UTI post-treatment markedly inhibited the release of HMGB1 and other pro-inflammatory cytokines. Furthermore, UTI significantly inhibited the LPS-induced increase in TLR2/4 protein expression and NF-κB activation in lung tissues. In vitro, UTI markedly inhibited the expression of TLR2/4 and the activation of NF-κB in LPS-stimulated A549 alveolar epithelial cells. The findings of our study indicate that UTI attenuates LPS-induced ALI through the inhibition of HMGB1 expression in rats. These benefits are associated with the inhibition of the activation of the TLR2/4-NF-κB pathway by UTI.

Ulinastatin Ameliorates Pulmonary Capillary Endothelial Permeability Induced by Sepsis Through Protection of Tight Junctions via Inhibition of TNF-α and Related Pathways

“…There is strong evidence indicating that UTI inhibits oxidant-induced hyperpermeability in cultured human endothelial cells, in which apoptosis and JNK/c-Jun signaling pathway were involved ( Li et al, 2014 , 2016 ). Furthermore, post-treatment with UTI markedly decreased cytokines (TNF-α and IL-6) in the bronchoalveolar lavage fluid (BALF) and attenuated LPS-induced ALI in LPS-induced rat model ( Luo et al, 2017 ). However, the protective effect of UTI on the tight junctional integrity of endothelia during sepsis-related lung injury and the underlying mechanisms have not been fully elucidated.…”

Lipoxin A4 ameliorates renal ischaemia–reperfusion‐induced acute lung injury in rats

“…At 1 hour after bilateral ischaemia, the rats were treated with LA4 (2 μg/kg, intravenously), BOC‐2 (50 μg/kg, intraperitoneally), or normal saline (NS, intravenously) . Lactated Ringer's solution (intraperitoneally) was subsequently used to resuscitate the rats in each group; at 1 hour after bilateral ischaemia, to illustrate the function of TLR4 in the release of inflammatory mediators, SD rats were administered an anti‐TLR4 Ab (10 mg/kg, intraperitoneally) and LA4 (2 μg/kg, intravenously) . At 24 hours following RIR, SD rats were killed.…”

“…Lung samples were collected, and liquid nitrogen was used to store lung samples for subsequent analysis. The dosages of LA4, anti‐TLR4 Ab and BOC‐2 were chosen according to those reported in previous studies and our preliminary experiments …”

Ulinastatin is effective in reducing mortality for critically ill patients with sepsis: a causal mediation analysis

“…Uncontrolled inflammatory response is the core to the pathophysiology of severe sepsis, which is also a potential target for its treatment 8 . Ulinastatin is one of such agents that have been shown to be promising in improving clinical outcomes for critically ill patients with sepsis 9 , 10 . However, clinical studies are conflicting.…”