Knockdown of circ_0001679 alleviates lipopolysaccharide-induced MLE-12 lung cell injury by regulating the miR-338-3p/ mitogen-activated protein kinase 1 axis

The upregulation of circ_0001679 was reported in lipopolysaccharide (LPS)-induced lung injury mouse model, but its functional roles and mechanisms in LPS-induced lung injury remain to be investigated. In this study, we aimed to explore the potential role of circ_0001679 in septic acute lung injury. We initially established an in vitro lung cell injury model using LPS-treated MLE-12 cells. siRNAs targeting circRNA_0001679 were employed to stably knock down circRNA_0001679, followed by functional assays to investigate the effect of circRNA_0001679 silencing. The levels of inflammatory cytokines such as IL-6, IL-β and TNF-α (Tumor necrosis factor-α) were detected by ELISA (Enzyme-linked immunosorbent assay). Meanwhile, protein levels of Bcl-2, cleaved-caspase 3, Bax, and MAPK1 (Mitogen-Activated Protein Kinase 1) proteins expression level were measured by Western blot. We found that Circ_0001679 was upregulated in LPS-induced MLE-12 cells, and silencing circ_0001679 attenuated the growth inhibition and suppressed apoptosis induced by LPS. Circ_0001679 knockdown also lowered levels of IL-6, IL-β and TNF-α, and prevent the activation of cleaved-caspase 3 protein. We further revealed that circ_0001679 functioned as a sponge of miR-338-3p to negatively regulate miR-338-3p activity. miR-338-3p downregulated its downstream target MAPK1, while the upregulation of circ_0001679 maintained a high-level expression of MAPK1 by suppressing miR-338-3p. Collectively, our study indicates that circ_0001679/miR-338-3p/MAPK1 axis may play an important role in the pathogenesis of acute lung injury (ALI).

Pravastatin attenuates sepsis-induced acute lung injury through decreasing pulmonary microvascular permeability via inhibition of Cav-1/eNOS pathway

BACKGROUND

Disruption of alveolar endothelial barrier caused by inflammation drives the progression of septic acute lung injury (ALI). Pravastatin, an inhibitor of HMG Co-A reductase, has potent anti-inflammatory effects. In the present study, we aim to explore the beneficial role of pravastatin in sepsis-induced ALI and its related mechanisms.

METHODS

A septic ALI model was established by cecal ligation and puncture (CLP) in mice. The pulmonary microvascular endothelial cells (PMVECs) were challenged with lipopolysaccharide (LPS). The pathological changes in lung tissues were examined by HE staining. The pulmonary microvascular permeability was determined by lung wet-to-dry (W/D) weight ratio and Evans blue staining. The total protein concentration in bronchoalveolar lavage fluid (BALF) was detected by BCA assay. The levels of TNF-α, IL-1β, and IL-6 were assessed by qRT-PCR and ELISA. Apoptosis was determined by flow cytometry and TUNEL. Western blotting was performed for detection of target protein levels. The expression of VE-Cadherin in lung tissues was evaluated by immunohistochemical staining.

RESULTS

Pravastatin improved survival rate, attenuated lung pathological changes and reduced pulmonary microvascular permeability in septic mice. In addition, pravastatin restrained sepsis-induced inflammatory response and apoptosis in the lung tissues and PMVECs. Moreover, pravastatin up-regulated the levels of junction proteins ZO-1, JAM-C, and VE-Cadherin. Finally, pravastatin suppressed inflammation, apoptosis and enhanced the expression of junction proteins via regulating Cav-1/eNOS signaling pathway in LPS-exposed PMVECs.

CONCLUSION

Pravastatin ameliorates sepsis-induced ALI through improving alveolar endothelial barrier disruption via modulating Cav-1/eNOS pathway, which may be an effective candidate for treating septic ALI.

MicroRNA-144-3p enhances LPS induced septic acute lung injury in mice through downregulating Caveolin-2

OBJECTIVE

The emphasis of this study focused on the possible implication and the mechanism of miR-144-3p in septic acute lung injury (ALI) condition.

METHODS

Mice were pre-injected with miR-144-3p agomir, miR-144-3p antagomir, sh-Caveolin-2 or PBS before 10 mg/kg LPS induced sepsis model establishment. The ratio of wet weight of lung tissues and body weight (W/W) was calculated. The pathological changes on lung tissues were observed by H&E staining. Secretions of inflammatory cytokines (TNF-α, IL-1β and IL-6) in both mouse serum and lung tissues were determined by ELISA. Cell apoptosis and cell morphology were measured by TUNEL staining and H&E staining. The expressions of miR-144-3p, Caveolin-2, apoptotic related proteins and JAK/STAT pathway related proteins were measured by qRT-PCR or/and Western blot. Dual luciferase reporter assay was applied to detect the binding of miR-144-3p with Caveolin-2.

RESULTS

LPS resulted in increased W/W, disrupted lung tissue, enhanced inflammatory response and cell apoptosis. miR-144-3p was upregulated while Caveolin-2 was downregulated in response to LPS treatment. Inflammation and cell apoptosis induced by LPS can be alleviated by miR-144-3p antagomir injection, but enhanced by miR-144-3p agomir or sh-Caveolin-2 treatment. miR-144-3p can negatively target Caveolin-2. miR-144-3p can activate the JAK/STAT signal pathway through Caveolin-2 in septic ALI mouse.

CONCLUSION

miR-144-3 can promote LPS induced septic ALI through downregulating Caveolin-2 to activate the JAK/STAT signal pathway.