Inhibition of MRP4 alleviates sepsis-induced acute lung injury in rats

The ATP-Binding Cassette Transporter-Mediated Efflux Transport of Ganciclovir at the Blood-Brain Barrier

BACKGROUND AND OBJECTIVE

Recent studies have highlighted the key role of the ATP-binding cassette (ABC) transporters, including the P-glycoprotein (P-gp), the breast cancer resistance protein (BCRP), and the multi-drug resistance protein 4 (MRP4) in limiting the brain distribution of several antiviral agents. In this study, we investigated whether the inhibition of these transporters increases the permeability of the blood-brain barrier (BBB) to ganciclovir.

METHODS

A microdialysis and high-performance liquid chromatographic method was developed to monitor the concentrations of unbound ganciclovir in the brain interstitial fluid and plasma, with and without the administration of ABC transporter inhibitors. Pharmacokinetic parameters, including the area under the plasma concentration-time curve from time 0 to time of the last measurable analyte concentration (AUC0-t,plasma), the area under the brain interstitial fluid concentration-time curve from time 0 to time of the last measurable analyte concentration (AUC0-t,brain), and the unbound brain-to-plasma concentration ratio (Kp,uu,brain) were calculated.

RESULTS

The mean AUC0-t,plasma, AUC0-t,brain, and Kp,uu,brain in rats who received ganciclovir (30 mg/kg, intraperitoneal) alone were 1090 min·µg/mL, 150 min·µg/mL, and 14%, respectively. After the administration of tariquidar (inhibitor of P-gp), Ko143 (inhibitor of BCRP), or MK-571 (inhibitor of MRP4), the Kp,uu,brain of ganciclovir increased to 31 ± 2.1%, 26 ± 1.3%, and 32 ± 2.0%, respectively.

CONCLUSIONS

The findings of this study suggest that ABC transporters P-gp, BCRP, and MRP4 mediate the efflux of ganciclovir at the BBB and that the inhibition of these transporters facilitates the penetration of the BBB by ganciclovir.

Anthrahydroquinone‑2,6‑disulfonate attenuates PQ‑induced acute lung injury through decreasing pulmonary microvascular permeability via inhibition of the PI3K/AKT/eNOS pathway

In paraquat (PQ)‑induced acute lung injury (ALI)/ acute respiratory distress syndrome, PQ disrupts endothelial cell function and vascular integrity, which leads to increased pulmonary leakage. Anthrahydroquinone‑2,6‑disulfonate (AH2QDS) is a reducing agent that attenuates the extent of renal injury and improves survival in PQ‑intoxicated Sprague‑Dawley (SD) rats. The present study aimed to explore the beneficial role of AH2QDS in PQ‑induced ALI and its related mechanisms. A PQ‑intoxicated ALI model was established using PQ gavage in SD rats. Human pulmonary microvascular endothelial cells (HPMECs) were challenged with PQ. Superoxide dismutase, malondialdehyde, reactive oxygen species and nitric oxide (NO) fluorescence were examined to detect the level of oxidative stress in HPMECs. The levels of TNF‑α, IL‑1β and IL‑6 were assessed using an ELISA. Transwell and Cell Counting Kit‑8 assays were performed to detect the migration and proliferation of the cells. The pathological changes in lung tissues and blood vessels were examined by haematoxylin and eosin staining. Evans blue staining was used to detect pulmonary microvascular permeability. Western blotting was performed to detect target protein levels. Immunofluorescence and immunohistochemical staining were used to detect the expression levels of target proteins in HPMECs and lung tissues. AH2QDS inhibited inflammatory responses in lung tissues and HPMECs, and promoted the proliferation and migration of HPMECs. In addition, AH2QDS reduced pulmonary microvascular permeability by upregulating the levels of vascular endothelial‑cadherin, zonula occludens‑1 and CD31, thereby attenuating pathological changes in the lungs in rats. Finally, these effects may be related to the suppression of the phosphatidylinositol‑3‑kinase (PI3K)/protein kinase B (AKT)/endothelial‑type NO synthase (eNOS) signalling pathway in endothelial cells. In conclusion, AH2QDS ameliorated PQ‑induced ALI by improving alveolar endothelial barrier disruption via modulation of the PI3K/AKT/eNOS signalling pathway, which may be an effective candidate for the treatment of PQ‑induced ALI.

Cellular and molecular mechanisms of Notch signal in pulmonary microvascular endothelial cells after acute lung injury

This study focused on the effect and mechanism of Notch signal on pulmonary microvascular endothelial cells (PMVECs) following acute lung injury. PMVECs were cultured in vitro and randomly divided into eight groups. Grouping was based on whether cells were co-cultured with T cells (splenic CD4+T cells were isolated using MACS microbeads) and the level of Notch expression: Normal group and Normal+T cells group, Model group and Model+T cells group, Notch low-expression group and Notch low-expression+T cells group, and Notch overexpression group and Notch overexpression+T cells group. Except for the Normal group and Normal+T cells group, all other groups were treated with 500 μL lipopolysaccharide (1 μg/mL). The expression of VE-cadherin and Zo-1 protein in the Model group (with or without T cells) was lower than that in the normal group (with or without T cells), their expression in the Notch low-expression group (with or without T cells) was significantly increased, and their expression in the Notch overexpression group (with or without T cells) was significantly decreased. Compared with the normal+T cells group, the number of Treg cells in the Notch low-expression+T cells group decreased significantly (P<0.01). The number of Th17 cells in the Notch overexpression+T cells group was higher than that in the Model+T cells group (P<0.01), while the number of Treg cells decreased (P<0.01). Our results demonstrated that activated Notch signal can down-regulate the expression of the tight junction proteins VE-Cadherin and Zo-1 in PMVECs and affect Th17/Treg immune imbalance. Autophagy was discovered to be involved in this process.

Saikosaponin D attenuates inflammatory response and cell apoptosis of lipopolysaccharide-induced lung epithelial cells

BACKGROUND

Acute lung injury (ALI) is a prevalent complication of sepsis with high mortality rate. Saikosaponin D (SSD) is a triterpenoid saponin that has been reported to alleviate sepsis-triggered renal injury in mice. Nonetheless, the therapeutic effect of SSD on sepsis-evoked ALI is unclarified.

METHODS

Lipopolysaccharide (LPS) from Escherichia coli 055:B5 was utilized to stimulate lung epithelial cell line MLE-12. A mouse model of sepsis was established. CCK-8 assay was employed for determining cytotoxicity. ELISA was utilized for determining proinflammatory cytokine production. Flow cytometry and western blotting were implemented for evaluating cell apoptosis. Hematoxylin-eosin staining was conducted for histologic analysis of murine lung tissues.

RESULTS

SSD alleviated LPS-triggered inflammation and cell apoptosis of MLE-12 cells. SSD treatment ameliorated the pathological damages, inflammatory response, and cell apoptosis in the lungs of septic mice.

CONCLUSION

SSD protects against sepsis-triggered ALI by inhibiting inflammation and cell apoptosis in MLE-12 cells and septic mouse mice.

ERRα protects against sepsis-induced acute lung injury in rats

BACKGROUND

Sepsis-induced acute lung injury (ALI) is associated with poor survival rates. The identification of potential therapeutic targets for preventing sepsis-induced ALI has clinical importance. This study aims to investigate the role of estrogen-related receptor alpha (ERRα) in sepsis-induced ALI.

METHODS

Lipopolysaccharide (LPS) was used to simulate sepsis-induced ALI model in rat pulmonary microvascular endothelial cells (PMVECs). The effects of ERRα overexpression and knockdown on LPS-induced endothelial permeability, apoptosis and autophagy were determined by horseradish peroxidase permeability assay, TdT-mediated dUTP Nick End Labeling (TUNEL) assay, flow cytometry, immunofluorescence staining, RT-PCR and Western Blotting. The rat model with sepsis-induced ALI was established by cecal ligation and puncture in anesthetized rats to verify the results of in vitro experiments. Animals were randomly assigned to receive intraperitoneal injection of vehicle or ERRα agonist. Lung vascular permeability, pathological injury, apoptosis and autophagy were examined.

RESULTS

Overexpression of ERRα ameliorated LPS-induced endothelial hyperpermeability, degradation of adherens junctional molecules, upregulation of bax, cleaved caspase 3 and cleaved caspase 9 levels, downregulation of anti-apoptotic protein Bcl-2 level, and promoted the formation of autophagic flux, while the knockdown of ERRα exacerbated LPS-induced apoptosis and inhibited the activation of autophagy. Administration of ERRα agonist alleviated the pathological damage of lung tissue, increased the levels of tight junction proteins and adherens junction proteins, and decreased the expression of apoptosis-related proteins. Promoting the expression of ERRα significantly enhanced the process of autophagy and reduced CLP-induced ALI. Mechanistically, ERRα is essential to regulate the balance between autophagy and apoptosis to maintain the adherens junctional integrity.

CONCLUSION

ERRα protects against sepsis-induced ALI through ERRα-mediated apoptosis and autophagy. Activation of ERRα provides a new therapeutic opportunity to prevent sepsis-induced ALI.

ABC transporters affects tumor immune microenvironment to regulate cancer immunotherapy and multidrug resistance

Multidrug resistance (MDR) is the phenomenon in which cancer cells simultaneously develop resistance to a broad spectrum of structurally and mechanistically unrelated drugs. MDR severely hinders the effective treatment of cancer and is the major cause of chemotherapy failure. ATP-binding cassette (ABC) transporters are extensively expressed in various body tissues, and actively transport endogenous and exogenous substrates through biological membranes. Overexpression of ABC transporters is frequently observed in MDR cancer cells, which promotes efflux of chemotherapeutic drugs and reduces their intracellular accumulation. Increasing evidence suggests that ABC transporters regulate tumor immune microenvironment (TIME) by transporting various cytokines, thus controlling anti-tumor immunity and sensitivity to anticancer drugs. On the other hand, the expression of various ABC transporters is regulated by cytokines and other immune signaling molecules. Targeted inhibition of ABC transporter expression or function can enhance the efficacy of immune checkpoint inhibitors by promoting anticancer immune microenvironment. This review provides an update on the recent research progress in this field.

NRIP1 aggravates lung injury caused by Pseudomonas aeruginosa in mice by increasing PIAS1 ubiquitination

Recently, evidence has shown that nuclear receptor interacting protein 1 (NRIP1) is involved in acute lung injury (ALI) progression, but the specific mechanism remains unclear. Pseudomonas aeruginosa (PA)-treated TC-1 cells were transfected with pcDNA-NRIP1 or si-NRIP1, and we found that overexpression of NRIP1 inhibited cell viability and promoted cell apoptosis and secretion of inflammatory factors, and transfection of si-NRIP1 reversed these effects. Furthermore, online bioinformatics analysis and co-immunoprecipitation assay results indicated that NRIP1 could bind to Ubiquitin Conjugating Enzyme E2I (UBE2I), and promoted UBE2I expression. Next, the PA-treated TC-1 cells were transfected with si-NRIP1 alone or together with pcDNA-UBE2I, and we observed that transfection with si-NRIP1 inhibited UBE2I expression, promoted cell viability, and reduced cell apoptosis and inflammatory factor secretion, which could be reversed by UBE2I overexpression. Moreover, UBE2I could bind to protein inhibitor of activated signal transducer and activators of transcription 1 (PIAS1). Overexpression of NRIP1 promoted UBE2I expression and inhibited PIAS1 expression, and NRIP1 promoted PIAS1 ubiquitination and degradation by UBE2I. The PA-treated TC-1 cells were transfected with si-UBE2I alone or together with si-PIAS1, and the results indicated that transfection of si-UBE2I had the same effect as transfection of si-NRIP1. Finally, our in vivo findings indicated that the expression of NRIP1 and UBE2I was decreased, and PIAS1 expression was increased, in the lung tissues of mice with NRIP1 knocked-down, and the inflammatory infiltration in the lung tissue was reduced. In conclusion, our study demonstrates that NRIP1 aggravates PA-induced lung injury in mice by promoting PIAS1 ubiquitination.

Pulmonary perfusion imaging and delayed imaging to measure pulmonary capillary permeability in pulmonary contusion

PURPOSE

Explore the application value of pulmonary perfusion imaging and delayed imaging for evaluating pulmonary capillary permeability.

MATERIALS AND METHODS

After establishing a rat model of pulmonary contusion, changes in the metabolic index of technetium-99m macroaggregated albumin (99mTC-MAA) in the lungs of model rats were evaluated for two consecutive days. 99mTC-MAA metabolic indices of rat lungs with pulmonary contusion of varying severity (mild, moderate, and severe) were correlated with lung wet/dry weight ratio (W/D) and Evans blue extravasation. Finally, the method was validated in patients with pulmonary contusion and one healthy volunteer.

RESULTS

The 99mTC-MAA metabolic index was 23.56% ± 2.44% in healthy control (HC) rat lung, 8.56% ± 3.42% immediately after lung contusion (d0), 8.35% ± 3.20% after 1 day (d1), and 17.45% ± 6.44% after 2 days (d2); indices at d0 and d1 were significantly higher than those at HC (P < 0.05). The metabolic index of 99mTC-MAA in lung had significant negative correlations with W/D (r = -0.8025; P = 0.0092) and Evans blue extravasation (r = -0.9356; P = 0.0002). Metabolic and oxygenation indices of 99mTC-MAA exhibited a significant positive linear correlation in patients with pulmonary contusion (r = 0.8925; P = 0.0416).

CONCLUSION

Pulmonary perfusion and delayed imaging of 99mTC-MAA have potential value for evaluating pulmonary capillary permeability.

circRNA_0001679/miR-338-3p/DUSP16 axis aggravates acute lung injury

Acute lung injury (ALI) is a respiratory disorder characterized by acute respiratory failure. circRNA mus musculus (mmu)-circ_0001679 was reported overexpressed in septic mouse models of ALI. Here the function of circ_0001679 in sepsis-induced ALI was investigated. In vitro models and animal models with ALI were, respectively, established in mouse lung epithelial (MLE)-12 cells and C57BL/6 mice. Pulmonary specimens were harvested for examination of the pathological changes. The pulmonary permeability was examined by wet-dry weight (W/D) ratio and lung permeability index. The levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β in the bronchoalveolar lavage fluid (BALF), the lung tissues, and the supernatant of MLE-12 cells were measured by enzyme linked immunosorbent assay . Apoptosis was determined by flow cytometry. Bioinformatics analysis and luciferase reporter assay were used to assess the interactions between genes. We found that circ_0001679 was overexpressed in lipopolysaccharide (LPS)-stimulated MLE-12 cells. circ_0001679 knockdown suppressed apoptosis and proinflammatory cytokine production induced by LPS. Moreover, circ_0001679 bound to mmu-miR-338-3p and miR-338-3p targeted dual-specificity phosphatases 16 (DUSP16). DUSP16 overexpression reversed the effect of circ_0001679 knockdown in LPS-stimulated MLE-12 cells. Furthermore, circ_0001679 knockdown attenuated lung pathological changes, reduced pulmonary microvascular permeability, and suppressed inflammation in ALI mice. Overall, circ_0001679 knockdown inhibits sepsis-induced ALI progression through the miR-338-3p/DUSP16 axis.

Extracellular metabolism of 3',5'-cyclic AMP as a source of interstitial adenosine in the rat airways

In the respiratory tract, intracellular 3',5'-cAMP mediates smooth muscle relaxation triggered by the β₂-adrenoceptor/Gs protein/adenylyl cyclase axis. More recently, we have shown that β₂-adrenoceptor agonists also increase extracellular 3',5'-cAMP levels in isolated rat trachea, which leads to contraction of airway smooth muscle. In many other tissues, extracellular 3',5'-cAMP is metabolized by ectoenzymes to extracellular adenosine, a catabolic pathway that has never been addressed in airways. In order to evaluate the possible extracellular degradation of 3',5'-cAMP into 5'-AMP and adenosine in the airways, isolated rat tracheas were incubated with exogenous 3',5'-cAMP and the amount of 5'-AMP, adenosine and inosine (adenosine metabolite) produced was evaluated using ultraperformance liquid chromatography-tandem mass spectrometry. Incubation of tracheal tissue with 3',5'-cAMP induced a time- and concentration-dependent increase in 5'-AMP, adenosine and inosine in the medium. Importantly, IBMX (non-selective phosphodiesterase (PDE) inhibitor) and DPSPX (selective ecto-PDE inhibitor) reduced the extracellular conversion of 3',5'-cAMP to 5'-AMP. In addition, incubation of 3',5'-cAMP in the presence of AMPCP (inhibitor of ecto-5'-nucleotidase) increased extracellular levels of 5'-AMP while drastically reducing extracellular levels of adenosine and inosine. These results indicate that airways express an extracellular enzymatic system (ecto-phosphodiesterase, ecto-5'-nucleotidase and adenosine deaminase) that sequentially converts 3',5'-cAMP into 5'-AMP, adenosine and inosine. The observation that extracellular 3',5'-cAMP is a source of interstitial adenosine supports the idea that the extrusion and extracellular metabolism of 3',5'-cAMP has a role in respiratory physiology and pathophysiology.

Cangrelor ameliorates CLP-induced pulmonary injury in sepsis by inhibiting GPR17

BACKGROUND

Sepsis is a common complication of severe wound injury and infection, with a very high mortality rate. The P2Y12 receptor inhibitor, cangrelor, is an antagonist anti-platelet drug.

METHODS

In our study, we investigated the protective mechanisms of cangrelor in CLP-induced pulmonary injury in sepsis, using C57BL/6 mouse models.

RESULTS

TdT-mediated dUTP Nick-End Labeling (TUNEL) and Masson staining showed that apoptosis and fibrosis in lungs were alleviated by cangrelor treatment. Cangrelor significantly promoted surface expression of CD40L on platelets and inhibited CLP-induced neutrophils in Bronchoalveolar lavage fluid (BALF) (p < 0.001). We also found that cangrelor decreased the inflammatory response in the CLP mouse model and inhibited the expression of inflammatory cytokines, IL-1β (p  < 0.01), IL-6 (p < 0.05), and TNF-α (p < 0.001). Western blotting and RT-PCR showed that cangrelor inhibited the increased levels of G-protein-coupled receptor 17 (GPR17) induced by CLP (p < 0.001).

CONCLUSION

Our study indicated that cangrelor repressed the levels of GPR17, followed by a decrease in the inflammatory response and a rise of neutrophils in BALF, potentially reversing CLP-mediated pulmonary injury during sepsis.

Ruscogenin attenuates sepsis-induced acute lung injury and pulmonary endothelial barrier dysfunction via TLR4/Src/p120-catenin/VE-cadherin signalling pathway

OBJECTIVES

Sepsis-associated acute lung injury (ALI) occurs with the highest morbidity and carries the highest mortality rates among the pathogenies of ALI. Ruscogenin (RUS) has been found to exhibit anti-inflammation property and rescue lipopolysaccharide-induced ALI, but little is known about its role in sepsis-triggered ALI. The aim of this study was to investigate the potential role of RUS in sepsis-induced ALI and the probable mechanism.

METHODS

Mice model of cecal ligation and puncture (CLP) was replicated, and three doses of RUS (0.01, 0.03 and 0.1 mg/kg) were administrated 1 h before CLP surgeries.

KEY FINDINGS

RUS significantly extended the survival time and attenuated the lung pathological injury, oedema and vascular leakage in sepsis-induced ALI mice. RUS efficiently decreased the level of MPO in lung tissue and the WBC, NEU counts in BALF. In addition, RUS rescued the expression of VE-cadherin and p120-catenin and suppressed the TLR4/Src signalling in lung tissue.

CONCLUSIONS

RUS attenuated sepsis-induced ALI via protecting pulmonary endothelial barrier and regulating TLR4/Src/p120-catenin/VE-cadherin signalling pathway.

Restoring microRNA-499-5p Protects Sepsis-Induced Lung Injury Mice Via Targeting Sox6

BACKGROUND

MicroRNAs (miRs) are known to participate in sepsis; hence, we aim to discuss the protective effect of miR-499-5p targeting sex-determining region Y-related high-mobility-group box 6 (Sox6) on sepsis-induced lung injury in mice.

METHODS

The sepsis-induced lung injury model was established by cecal ligation and puncture. The wet/dry weight (W/D) ratio, miR-499-5p, Sox6, Caspase-3 and Caspase-9 expression in lung tissues of mice were tested. Lung injury score, collagen fibers and the degree of pulmonary fibrosis in lung tissues were determined. Further, the cell apoptosis in lung tissues was measured. The inflammatory factors contents and oxidative stress indices in bronchoalveolar lavage fluid (BALF) and lung tissues were detected via loss- and gain-of-function assays. The targeting relation between miR-499-5p and Sox6 was verified.

RESULTS

W/D ratio and Sox6 were increased while miR-499-5p was decreased in lung tissues of sepsis-induced lung injury mice. Restored miR-499-5p or depleted Sox6 alleviated lung tissues pathology, reduced lung injury score, collagen fibers, the degree of pulmonary fibrosis, TUNEL positive cells, Caspase-3 and Caspase-9 protein expression and inflammatory factors contents in BALF and lung tissues as well as oxidative stress response in lung tissues of sepsis-induced lung injury mice. miR-499-5p targeted Sox6.

CONCLUSION

High expression of miR-499-5p can attenuate cell apoptosis in lung tissues and inhibit inflammation of sepsis-induced lung injury mice via depleting Sox6, and it is a potential candidate marker and therapeutic target for sepsis-induced lung injury.

Anti-Inflammatory Effect Fraction of Bletilla striata and Its Protective Effect on LPS-Induced Acute Lung Injury

Bletilla striata is a well-known traditional Chinese herb with anti-inflammatory properties that is widely used in the treatment of lung conditions such as silicosis, tuberculosis, and pneumogastric hemorrhage. However, little information on the anti-inflammatory ingredients and their activities is available. In this study, an effect fraction of Bletilla striata (EFBS) was enriched, and its anti-inflammatory activities and underlying mechanisms were investigated. EFBS was enriched by polyamide column chromatography and characterized by HPLC; an LPS-induced acute lung injury model was used to evaluate the anti-inflammatory activities of EFBS. Meanwhile, the main anti-inflammation-contributing ingredients and possible molecular mechanism of anti-inflammatory activity in EFBS were verified by component-knockout method combined with LPS-induced RAW264.7 cell model. The EFBS mainly consisted of coelonin (15.88%), batatasin III (32.49%), 3′-O-methylbatatasin III (6.96%), and 3-hydroxy-5-methoxy bibenzyl (2.51%). Pretreatment with the EFBS (20 mg/kg and 60 mg/kg) for five days prior to the administration of LPS resulted in decreases in wet-to-dry lung weight ratio, neutrophil number, MPO activity, total protein concentration, NO level, and MDA level, as well as IL-1β, IL-6, MCP-1, and TNF-α concentrations in the bronchoalveolar lavage fluid. Western blot analysis demonstrated the increased expressions of iNOS, COX-2, and NF-κB p65 in the LPS treatment group, all of which were ameliorated by EFBS pretreatment. Histological examination confirmed the protective effect of the EFBS. Additionally, component-knockout assay confirmed that these four quantitative components contributed significantly to the anti-inflammatory effect of EFBS. Coelonin, batatasin III, 3′-O-methylbatatasin III and 3-hydroxy-5-methoxy bibenzyl were the main anti-inflammatory components of EFBS and could regulate the expression of downstream inflammatory cytokines by inhibiting p65 nuclear translocation. These findings uncover, in part, the molecular basis underlying the anti-inflammatory activity of Bletilla striata.

LncRNA NEAT1 acts as a key regulator of cell apoptosis and inflammatory response by the miR-944/TRIM37 axis in acute lung injury

Acute lung injury (ALI), a common complication of sepsis, is characterized by the impairment and injury of pulmonary function. The nuclear factor kappa-B (NF-κB) pathway is activated in ALI. Tripartite motif-containing 37 (TRIM37) can activate the NF-κB pathway and is closely associated with inflammation. The purpose of our study is to reveal the role of TRIM37 in ALI. The present study revealed that TRIM37 presented high levels in lung tissues of ALI mice, and knockdown of TRIM37 alleviated lipopolysaccharide (LPS)-induced lung injury, inflammatory response, and cell apoptosis in vivo. In addition, knockdown of TRIM37 inhibited the inflammatory response, and cell apoptosis of LPS-treated WI-38 cells. Mechanistically, miR-944 was identified to bind with and negatively regulate TRIM37. Furthermore, NEAT1 was indicated to act as a competitive endogenous RNA to promote TRIM37 expression by sequestering miR-944. Detailly, NEAT1 bound with miR-944, negatively modulated miR-944 expression, and positively modulated TRIM37 expression. The rescue assays suggested that overexpression of TRIM37 rescued the influence of NEAT1 knockdown on cell apoptosis and inflammatory response. Overall, NEAT1 facilitated cell apoptosis and inflammatory response of WI-38 cells by the miR-944/TRIM37 axis in sepsis-induced ALI, implying that NEAT1 may provide a novel insight for the treatment of sepsis-induced ALI.

Puerarin Inhibits Ferroptosis and Inflammation of Lung Injury Caused by Sepsis in LPS Induced Lung Epithelial Cells

Background: Ferroptosis is a new type of programmed cell death, which plays an important role in lung injury caused by sepsis. Studies have reported that Puerarin (Pue) can treat lung injury caused by sepsis in children, but whether it plays a role by regulating iron death has not been reported. Methods: LPS induced human alveolar epithelial cell A549 to form a model of lung injury caused by sepsis. MTT detected the effect of Pue on A549 cell viability and the effect of Pue on LPS-induced A549 cell viability. The effects of Pue on LPS-induced inflammatory cytokines TNF-α, IL-8, IL-1β in A549 cells were determined by ELISA assay. The expression level of MDA was detected by TBARS colorimetric quantitative detection kit. GSH kit was used to detect the expression of GSH in cells. The iron kit detected the total iron level and the expression level of ferric divalent ions in the cells. DCFH-DA fluorescent probe was used to detect ROS levels. Western blot was used to detect the expression of ferroptosis-related proteins in cells. Results: Pue alleviated LPS-induced injury and inflammatory response in A549 cells, and Pue reduced the expression of ROS, MDA and GSH in LPS-induced A549 cells. In addition, Pue reduced total iron levels and ferrous ion levels in LPS-induced A549 cells, and decreased the expression of iron ferroptosis-related proteins. Conclusion: Puerarin inhibited ferroptosis and inflammation of lung injury caused by sepsis in children in LPS induced lung epithelial cells.

Promotion of Bronchopulmonary Dysplasia Progression Using Circular RNA circabcc4 via Facilitating PLA2G6 Expression by Sequestering miR-663a

Circular RNA (circRNA) has been increasingly proven as a new type of promising therapeutic RNA molecule in a variety of human diseases. However, the role of circRNA in bronchopulmonary dysplasia (BPD) has not yet been elucidated. Here, a new circRNA circABCC4 was identified from the Agilent circRNA chip as a differentially expressed circRNA in BPD. The relationship between circABCC4 level and BPD clinicopathological characteristics was analyzed. The function of circABCC4 was evaluated by performing CCK-8 and apoptosis analysis in vitro and BPD model analysis in vivo. RNA immunoprecipitation (RIP), luciferase reporter and rescue experiments were used to elucidate the interaction between circABCC4 and miR-663a. Luciferase reporter assay and rescue experiments were used to elucidate the interaction between PLA2G6 and miR-663a. CircABCC4 and PLA2G6 levels were increased, while miR-663a levels were decreased in the BPD group, compared to the control group. MiR-663a inhibited apoptosis by repressing PLA2G6 expression, while circABCC4 enhanced the apoptosis and inhibited the proliferation of A549 cells by sponging miR-663a and increasing PLA2G6 expression. In conclusion, circABCC4 promotes the evolving of BPD by spongening miR-663a and up-regulating PLA2G6 expression, which makes circABCC4 an ideal molecular target for early diagnosis and intervention of BPD.

Protective effects of P2X7R antagonist in sepsis-induced acute lung injury in mice via regulation of circ_0001679 and circ_0001212 and downstream Pln, Cdh2, and Nprl3 expression

BACKGROUND

Sepsis induces pulmonary P2X₇ receptor (P2X₇ R) expression and P2X₇ R-knockout reduced lung inflammation in mice. The present study investigated the expression of circular RNA (circRNA) and mRNA in sepsis-induced acute lung injury (ALI) treated with a P2X₇ R antagonist.

METHODS

Sepsis was induced by tracheal administration of lipopolysaccharide (LPS), and the mice were then divided into two groups: without [sepsis + dimethyl sulfoxide (DMSO)] or with P2X₇ R antagonist treatment (sepsis + P2X₇ A). Sham mice were administrated sterile normal saline. Serum levels of interleukin (IL)-1β and tumor necrosis factor (TNF)-α, pathological changes, cell apoptosis and P2X₇ R expression in lung were assessed, followed by RNA sequencing (RNA-seq) and bioinformatics analyses. A quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) was used to validate circRNAs and mRNAs.

RESULTS

Compared to the sham group, LPS-induced sepsis produced obvious pathological changes in lung tissue, as well as increased apoptotic lung cells, serum TNF-α and IL-1β levels, and P2X₇ R expression; P2X₇ R antagonism significantly ameliorated these changes. RNA-seq identified many dysregulated circRNAs and mRNAs during sepsis, whereas this changed with P2X₇ R antagonism. RT-qPCR confirmed that Mus musculus (mmu)_circ_0001679, mmu_circ_0001212, phospholamban (Pln), cadherin-2 (Cdh2) and nitrogen permease regulator 3-like (Nprl3) expression were significantly increased in the sepsis + DMSO group compared to that in the sham group but were decreased in the sepsis + P2X₇ A group compared to that in the sepsis + DMSO group. The circRNA-microRNA-mRNA coexpression network indicated that mmu_circ_0001679 may regulate Nprl3 and that mmu_circ_0001212 may similarly regulate Pln, Cdh2 and Nprl3 as a competing endogenous RNA.

CONCLUSIONS

P2X₇ R antagonism attenuates sepsis-induced ALI by inhibiting dysregulated expression of circRNA (circ_0001679, circ_0001212) and mRNA (Pln, Cdh2 and Nprl3).

Inhibition of ERRα Aggravates Sepsis-Induced Acute Lung Injury in Rats via Provoking Inflammation and Oxidative Stress

Inflammation and oxidative stress are critical pathologies that contribute to sepsis-induced acute lung injury (ALI). This study investigated the regulatory role of estrogen-related receptor alpha (ERRα) in an experimental model of sepsis-induced ALI. In vivo, a cecal ligation and puncture- (CLP-) induced ALI model was established in anesthetized rats. Animals were then randomly assigned to receive an intraperitoneal injection of vehicle or ERRα inverse agonist (XCT-790, 2.5 mg/kg). Administration of XCT-790 significantly aggravated a sepsis-induced increase in pathological damage of lung tissues, lung endothelial permeability, myeloperoxidase (MPO) activity in lung tissues, production of serum inflammatory factors, and inflammatory cell accumulation in bronchoalveolar lavage fluid. In addition, XCT-790 treatment exacerbated a CLP-induced decrease in lung superoxide dismutase and an increase in lung malondialdehyde levels. In vitro, the exposure of rat pulmonary microvascular endothelial cells (PMVECs) to lipopolysaccharide (LPS) resulted in increased endothelial permeability and reduced expression of tight junction protein ZO-1, Occludin, JAM-A, and adherens junction protein VE-cadherin, which were further deteriorated by knockdown of ERRα. In addition, LPS-triggered inflammatory factor production and increase in the expression of phosphorylated IκBα and NF-κB p65 were also exacerbated by silencing ERRα gene. Meanwhile, knockdown of ERRα dramatically promoted LPS-activated mitochondrial reactive oxygen species production and LPS-induced downregulation of Sirt3 protein levels in rat PMVECs. Taken together, our present study provides evidences that ERRα functions as a novel negative modulator of sepsis-induced ALI in rats. The underlying mechanisms responsible for ERRα-elicited effects are largely dependent on the regulation of inflammatory response and oxidative stress.

Identification of circRNA and mRNA expression profiles and functional networks of vascular tissue in lipopolysaccharide-induced sepsis

Sepsis is the most common cause of death in intensive care units. This study investigated the circular RNA (circRNA) and mRNA expression profiles and functional networks of the aortic tissue in sepsis. We established a lipopolysaccharide (LPS)‐induced rat sepsis model. High‐throughput sequencing was performed on the aorta tissue to identify differentially expressed (DE) circRNAs and mRNAs, which were validated by real‐time quantitative polymerase chain reaction (RT‐qPCR). Bioinformatic analysis was carried out and coding and non‐coding co‐expression (CNC) and competing endogenous RNA (ceRNA) regulatory networks were constructed to investigate the mechanisms. In total, 373 up‐regulated and 428 down‐regulated circRNAs and 2063 up‐regulated and 2903 down‐regulated mRNAs were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of mRNAs showed that the down‐regulated genes were mainly enriched in the process of energy generation. CNC and ceRNA regulatory networks were constructed with seven DE circRNAs. The results of functional enrichment analysis of CNC target genes revealed the important role of circRNAs in inflammatory response. The ceRNA network also highlighted the significant enrichment in calcium signalling pathway. Significant alterations in circRNAs and mRNAs were observed in the aortic tissue of septic rats. In addition, CNC and ceRNA networks were established.

Integration Analysis of m6A-SNPs and eQTLs Associated With Sepsis Reveals Platelet Degranulation and Staphylococcus aureus Infection are Mediated by m6A mRNA Methylation

Sepsis is a major threat with high mortality rate for critically ill patients. Response to pathogen infection by the host immune system is a key biological process involved in the onset and development of sepsis. Heterogeneous host genome variation, especially single nucleotide polymorphisms (SNPs), has long been suggested to contribute to differences in disease progression. However, the function of SNPs located in non-coding regions remains to be elucidated. Recently, m⁶A mRNA modification levels were revealed to differ at SNPs. As m⁶A is a crucial regulator of gene expression, these SNPs might control genes by changing the m⁶A level on mRNA. To investigate the potential role of m⁶A SNPs in sepsis, we integrated m⁶A-SNP and expression quantitative trait loci (eQTLs) data. Analysis revealed 15,720 m⁶A-cis-eQTLs and 381 m⁶A-trans-eQTLs associated with sepsis. We identified 1321 genes as locations of m⁶A-cis-eQTLs. These were enriched in platelet degranulation and Staphylococcus aureus infection pathways, which are vital for the pathophysiological process of sepsis. We conclude that m⁶A modification of mRNA plays a very important role in sepsis, with m⁶A-cis-eQTLs potentially having the most effect on individual variation in sepsis progression.