leupeptins and Acute-Lung-Injury

Sepsis is a potentially fatal systemic inflammatory response syndrome caused by infection. In this study, we evaluated the effects of MCP-induced protein 1 (MCPIP1), a recently discovered inflammation-related ribonuclease, on sepsis-induced acute lung injury (ALI) and investigated the underlying mechanisms. Cecal ligation puncture and lipopolysaccharide induction were performed on Sprague-Dawley rats and RAW264.7 cells, respectively, to establish sepsis-induced ALI models. The proteasome inhibitor MG132 used as an activator of MCPIP1 overexpression, and we showed that MG132 can indeed increase the expression of MCPIP1. MCPIP1 overexpression induced by MG132 alleviated sepsis-induced pathologic changes, water content and protein leakage in the lungs, and induction of systemic inflammatory mediators, and improved the 7-day mortality rate in the model rats. We also showed that MCPIP1 p showed romoted macrophage polarization from the M1 to the M2 type in sepsis-induced ALI. Furthermore, MCPIP1-enhanced M2 polarization was inhibited by an MCPIP1-targeting small interfering RNA (siMCPIP1) in RAW264.7 cells. Further mechanistic studies showed that the promotive effect of MCPIP1 on M2 polarization was related to the inhibition of c-Jun N-terminal kinase (JNK) and its downstream transcription factor c-Myc in the in vitro model. Conversely, siMCPIP1 transfection resulted in the recovery of JNK and c-Myc expression in LPS-treated cells. Taken together, these findings indicate that MCPIP1 plays a protective role in sepsis-induced ALI by modulating macrophage polarization through inhibition of the JNK/c-Myc signaling pathway. Our study presents a potentially novel therapeutic strategy for the treatment of lung injury involving the inflammatory cascade.

Topics: Acute Lung Injury; Animals; JNK Mitogen-Activated Protein Kinases; Leupeptins; Male; Mice; Proto-Oncogene Proteins c-myc; Rats, Sprague-Dawley; RAW 264.7 Cells; Ribonucleases; Sepsis; Signal Transduction

BACKGROUND The aim of the present study was to investigate the protective effects of protease inhibitor MG-132 on sepsis-induced acute lung injury rats. MATERIAL AND METHODS Sprague Dawley rats were employed to induce sepsis by cecal ligation and puncture (CLP) method. Rats were divided into 4 groups: control, sham, model (CLP), and MG-132. Histopathology observation was detected by hematoxylin and eosin staining. The ratio of wet lung to dry lung (W/D) was calculated. In addition, the levels of inflammatory factors in bronchoalveolar lavage fluid (BALF) were measured by enzyme-linked immunosorbent assay (ELISA). Also, superoxide dismutase (SOD) and malondialdehyde (MDA) levels were evaluated. Western blotting was performed to measure the expression of hypoxia-inducible factor-1 alpha (HIF-1alpha). In order to assess the role of HIF-1alpha, YC-1, the inhibitor of HIF-1alpha, was used to treat the rats. The expression of phosphor-mTOR (p-mTOR), p-4EBP1, and p-EIF4E were evaluated by western blotting. RESULTS Obvious pathological injury and increasing ratio of W/D in the model group were observed. Both pathological injury and W/D were improved in the MG-132 group, and the greatest improvement could be seen in the YC-1+MG-132 group. Furthermore, the MDA levels in the MG-132 group was decreased, accompanied by an increase in SOD levels. The level of HIF-1alpha was increased in the model group while a decreased was detected in the MG-132 group. The levels of inflammatory factors were high in the model group, whereas the opposite result was found in the MG-132 group, and the lowest in were in the YC-1+MG-132 group. Furthermore, the expression levels of p-mTOR, p-4EBP1, and p-EIF4E proteins were downregulated in the MG-132 group compared to the model group, and the lowest was in the YC-1+MG-132 group. CONCLUSIONS Our study suggested that MG-132 was able to protect against acute lung injury via inhibition of HIF-1alpha mediated mTOR/4EBP1/EIF4E pathway.

Topics: Acute Lung Injury; Animals; Bronchoalveolar Lavage Fluid; China; Eukaryotic Initiation Factor-4E; Hypoxia-Inducible Factor 1, alpha Subunit; Intracellular Signaling Peptides and Proteins; Leupeptins; Lung; Malondialdehyde; Pulmonary Edema; Rats; Rats, Sprague-Dawley; Sepsis; Superoxide Dismutase; TOR Serine-Threonine Kinases