Nrf2/PHB2 alleviates mitochondrial damage and protects against Staphylococcus aureus-induced acute lung injury.

Staphylococcus aureus (SA) is a major cause of sepsis, leading to acute lung injury (ALI) characterized by inflammation and oxidative stress. However, the role of the Nrf2/PHB2 pathway in SA-induced ALI (SA-ALI) remains unclear. In this study, serum samples were collected from SA-sepsis patients, and a SA-ALI mouse model was established by grouping WT and Nrf2-/- mice after 6 h of intraperitoneal injection. A cell model simulating SA-ALI was developed using lipoteichoic acid (LTA) treatment. The results showed reduced serum Nrf2 levels in SA-sepsis patients, negatively correlated with the severity of ALI. In SA-ALI mice, downregulation of Nrf2 impaired mitochondrial function and exacerbated inflammation-induced ALI. Moreover, PHB2 translocation from mitochondria to the cytoplasm was observed in SA-ALI. The p-Nrf2/total-Nrf2 ratio increased in A549 cells with LTA concentration and treatment duration. Nrf2 overexpression in LTA-treated A549 cells elevated PHB2 content on the inner mitochondrial membrane, preserving genomic integrity, reducing oxidative stress, and inhibiting excessive mitochondrial division. Bioinformatic analysis and dual-luciferase reporter assay confirmed direct binding of Nrf2 to the PHB2 promoter, resulting in increased PHB2 expression. In conclusion, Nrf2 plays a role in alleviating SA-ALI by directly regulating PHB2 transcription and maintaining mitochondrial function in lung cells.

Dehydrocostus Lactone Attenuates Methicillin-Resistant Staphylococcus aureus-Induced Inflammation and Acute Lung Injury via Modulating Macrophage Polarization.

Dehydrocostus lactone (DHL), a natural sesquiterpene lactone isolated from the traditional Chinese herbs Saussurea lappa and Inula helenium L., has important anti-inflammatory properties used for treating colitis, fibrosis, and Gram-negative bacteria-induced acute lung injury (ALI). However, the effects of DHL on Gram-positive bacteria-induced macrophage activation and ALI remains unclear. In this study, we found that DHL inhibited the phosphorylation of p38 MAPK, the degradation of IκBα, and the activation and nuclear translocation of NF-κB p65, but enhanced the phosphorylation of AMP-activated protein kinase (AMPK) and the expression of Nrf2 and HO-1 in lipoteichoic acid (LTA)-stimulated RAW264.7 cells and primary bone-marrow-derived macrophages (BMDMs). Given the critical role of the p38 MAPK/NF-κB and AMPK/Nrf2 signaling pathways in the balance of M1/M2 macrophage polarization and inflammation, we speculated that DHL would also have an effect on macrophage polarization. Further studies verified that DHL promoted M2 macrophage polarization and reduced M1 polarization, then resulted in a decreased inflammatory response. An in vivo study also revealed that DHL exhibited anti-inflammatory effects and ameliorated methicillin-resistant Staphylococcus aureus (MRSA)-induced ALI. In addition, DHL treatment significantly inhibited the p38 MAPK/NF-κB pathway and activated AMPK/Nrf2 signaling, leading to accelerated switching of macrophages from M1 to M2 in the MRSA-induced murine ALI model. Collectively, these data demonstrated that DHL can promote macrophage polarization to an anti-inflammatory M2 phenotype via interfering in p38 MAPK/NF-κB signaling, as well as activating the AMPK/Nrf2 pathway in vitro and in vivo. Our results suggested that DHL might be a novel candidate for treating inflammatory diseases caused by Gram-positive bacteria.

Ethyl ferulate protects against lipopolysaccharide-induced acute lung injury by activating AMPK/Nrf2 signaling pathway.

Ethyl ferulate (EF) is abundant in Rhizoma Chuanxiong and grains (e.g., rice and maize) and possesses antioxidative, antiapoptotic, antirheumatic, and anti-inflammatory properties. However, its effect on lipopolysaccharide (LPS)-induced acute lung injury (ALI) is still unknown. In the present study, we found that EF significantly alleviated LPS-induced pathological damage and neutrophil infiltration and inhibited the gene expression of proinflammatory cytokines (TNF-α, IL-1ß, and IL-6) in murine lung tissues. Moreover, EF reduced the gene expression of TNF-α, IL-1ß, IL-6, and iNOS and decreased the production of NO in LPS-stimulated RAW264.7 cells and BMDMs. Mechanistic experiments revealed that EF prominently activated the AMPK/Nrf2 pathway and promoted Nrf2 nuclear translocation. AMPK inhibition (Compound C) and Nrf2 inhibition (ML385) abolished the beneficial effect of EF on the inflammatory response. Furthermore, the protective effect of EF on LPS-induced ALI was not observed in Nrf2 knockout mice. Taken together, the results of our study suggest that EF ameliorates LPS-induced ALI in an AMPK/Nrf2-dependent manner. These findings provide a foundation for developing EF as a new anti-inflammatory agent for LPS-induced ALI/ARDS therapy.

Itaconate ameliorates methicillin-resistant Staphylococcus aureus-induced acute lung injury through the Nrf2/ARE pathway.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) are a critical predisposing factor of sepsis in the clinic. As a product of human energy metabolism and immune response, itaconate can effectively reduce inflammation in the body. This research employed 4-octyl itaconate (4-OI) to illustrate that itaconate exerted anti-inflammatory effects to protect the body from acute lung injury (ALI) induced by MRSA. METHODS: HE staining and immunohistochemistry are used to evaluate the MRSA-induced ALI in mice. WB and qPCR were used to verify the effect of 4-OI on inflammation and oxidative stress caused by MRSA. Molecular docking was used to verify the binding sites of 4-OI and Keap1. RESULTS: We demonstrated that 4-OI treatment increased the survival ratio, attenuated the pathological damage, inhibited neutrophil infiltration, and reduced lung bacterial burden in the mouse MRSA pneumonia model. 4-OI decreased the expression of inflammatory factors by stimulating the Nrf2 in vivo and in vitro. Furthermore, 4-OI exerted its effect by promoting nuclear transport of Nrf2 in vitro. The results of molecular docking indicated that 4-OI bound to the pocket of Keap1 and exerted a stable interaction. Both Nrf2 inhibitors (ML385) and Nrf2-/- mice abolished the protective effect of 4-OI on MRSA-induced inflammation both in vitro and in vivo. CONCLUSIONS: 4-OI prevents lung damage caused by MRSA bacteremia via activating Nrf2/ARE pathway.

Sodium Propionate Enhances Nrf2-Mediated Protective Defense Against Oxidative Stress and Inflammation in Lipopolysaccharide-Induced Neonatal Mice.

BACKGROUND: Alveolar arrest and the impaired angiogenesis caused by chronic inflammation and oxidative stress are two main factors in bronchopulmonary dysplasia (BPD). Short-chain fatty acids (SCFAs), especially propionate, possess anti-oxidant and anti-inflammatory effects. The present study was designed to examine the roles of sodium propionate (SP) on lipopolysaccharide (LPS)-challenged BPD and its potential mechanisms. METHODS: WT, Nrf2-/- mice and pulmonary microvascular endothelial cells (HPMECs) were used in this study. LPS was performed to mimic BPD model both in vivo and vitro. Lung histopathology, inflammation and oxidative stress-related mRNA expressions in lungs involved in BPD pathogenesis were investigated. In addition, cell viability and angiogenesis were also tested. RESULTS: The increased nuclear factor erythroid 2-related factor (Nrf2) and decreased Kelch-like ECH-associated protein-1 (Keap-1) expressions were observed after SP treatment in the LPS-induced neonatal mouse model of BPD. In LPS-induced wild-type but not Nrf2-/- neonatal mice, SP reduced pulmonary inflammation and oxidative stress and exhibited obvious pathological alterations of the alveoli. Moreover, in LPS-evoked HPMECs, SP accelerated Nrf2 nuclear translocation presented and exhibited cytoprotective and pro-angiogenesis effects. In addition, SP diminished the LPS-induced inflammatory response by blocking the activation of nuclear factor-kappa B pathway. Moreover, pretreatment with ML385, an Nrf2 specific inhibitor, offsets the beneficial effects of SP on inflammation, oxidative stress and angiogenesis in LPS-evoked HPMECs. CONCLUSION: SP protects against LPS-induced lung alveolar simplification and abnormal angiogenesis in neonatal mice and HPMECs in an Nrf2-dependent manner.

Sophoricoside attenuates lipopolysaccharide-induced acute lung injury by activating the AMPK/Nrf2 signaling axis.

Sophoricoside (SOP), an isoflavone glycoside isolated from seed of Sophora japonica L., has been reported to have various pharmacological activities, including anti-cancer, anti-allergy and anti-inflammation. However, the effect of SOP on lipopolysaccharides (LPS)-acute lung injury (ALI) is completely unclear. Here, we found that SOP pretreatment significantly ameliorated LPS-induced pathological damage, tissue permeability, neutrophil infiltration and the production of pro-inflammatory cytokines (TNF-α, IL-1ß and IL-6) in a murine model of ALI. Besides, SOP reduced the production of pro-inflammatory mediators such as iNOS, NO and inflammatory cytokines including TNF-α, IL-1ß and IL-6 in LPS-stimulated RAW264.7 cells and bone marrow derived macrophages. Interestingly, treatment with SOP exhibited no effect on the activation of NF-κB and MAPKs in macrophages but prominently accelerated the expression and nuclear translocation of Nrf2. By using ML385, a specific Nrf2 inhibitor, we found that inhibition of Nrf2 abolished the inhibitory effect of SOP on LPS-induced iNOS expression, NO production as well as pro-inflammatory cytokine generation. SOP also activated AMPK, an upstream protein of Nrf2, under LPS stimuli. Furthermore, we demonstrated that the accelerated expression of Nrf2 induced by SOP was reversed by interference with the AMPK inhibitor Compound C. Taken together, our results suggested that SOP attenuated LPS-induced ALI in AMPK/Nrf2 dependent manner and indicated that SOP might be a potential therapeutic candidate for treating ALI/ARDS.

Salvinorin A protects against methicillin resistant staphylococcus aureus-induced acute lung injury via Nrf2 pathway.

Salvinorin A (SA), a neoclerodane diterpene, is isolated from the dried leaves ofSalvia divinorum. SA has traditionally been used treatments for chronic pain diseases. Recent research has demonstrated that SA possesses the anti-inflammatory property. The present study aim to explore the effects and potentialmechanisms ofSA in protection against Methicillin Resistant Staphylococcus aureus (MRSA)-induced acute lung injury (ALI). Here, we firstly found that verylowdosesof SA (50 µg/kg) could markedly decrease the infiltration of pulmonary neutrophils, mRNA expression of pro-inflammatory cytokines (TNF-α, IL-1ß and IL-6) and then attenuated ALI cause by MRSA infection in mice. In vitro findings revealed that SA attenuated lipoteichoicacid-induced apoptosis, inflammation and oxidative stress in RAW264.7 cells. Mechanism research revealed that SA increased both mRNA levels and protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and up-regulated mRNA expression of its downstream genes (HO-1, Gclm, Trx-1, SOD1 and SOD2). Additionally, Nrf2 knockout mice abolished the inhibitory effect of SA on neutrophil accumulation and oxidative stress in MRSA-induced ALI. In conclusion, SA attenuates MRSA-induced ALI via Nrf2 signaling pathways.

Sodium Propionate Attenuates the Lipopolysaccharide-Induced Epithelial-Mesenchymal Transition via the PI3K/Akt/mTOR Signaling Pathway.

Short-chain fatty acids (SCFAs), especially propionate, originate from the fermentation of dietary fiber in the gut and play a key role in inhibiting pulmonary inflammation. Chronic inflammation may induce an epithelial-mesenchymal transition (EMT) in alveolar epithelial cells and result in fibrotic disorders. This study was designed to investigate the beneficial effect of sodium propionate (SP) on lipopolysaccharide (LPS)-induced EMT. In cultured BEAS-2B cells, the protein expression levels of E-cadherin, α-smooth muscle actin (SMA), and vimentin were 0.66 ± 0.20, 1.44 ± 0.23, and 1.32 ± 0.21 in the LPS group vs 1.11 ± 0.36 (P < 0.05), 1.04 ± 0.30 (P < 0.05), and 0.96 ± 0.13 (P < 0.01) in the LPS + SP group (mean ± standard deviation), respectively. Meanwhile, LPS-triggered inflammatory cytokines and extracellular proteins were also reduced by SP administration in BEAS-2B cells. Moreover, SP treatment attenuated inflammation, EMT, extracellular matrix (ECM) deposition, and even fibrosis in a mouse EMT model. In terms of mechanism, LPS-treated BEAS-2B cells exhibited a higher level of phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) phosphorylation, which was interrupted by SP treatment. It is worth noting that the blockade of the PI3K/Akt/mTOR signaling cascade reduced the LPS-evoked EMT process in BEAS-2B cells. These results suggest that SP can block LPS-induced EMT via inhibition of the PI3K/Akt/mTOR signaling cascade, which provides a basis for possible clinical use of SP in airway and lung diseases.

Elevation of autophagy rescues spermatogenesis by inhibiting apoptosis of mouse spermatocytes.

Autophagy and apoptosis are interlocked in an extensive crosstalk. Our previous study demonstrated that hypotonic hypoxia-induced marked apoptosis of a spermatocyte-derived cell line (GC-2). However, whether hypoxia-induced apoptosis is mediated by inhibition of autophagy under hypoxic conditions remains unclear. In this study, GC-2 cells were cultured in 1% O2 and harvested at different time points. Autophagy was determined by acridine orange staining, cyto-ID staining, mCherry-GFP-LC3B adenovirus transfection and Western blotting for various autophagy markers. Apoptosis was detected by TUNEL staining, flow cytometry, JC-1 staining and Western blotting of apoptosis-related proteins. We found that hypoxia-induced apoptosis of GC-2 cells through mitochondrial and death receptor pathways and inhibited autophagic flux in GC-2 cells in a time-dependent manner. However, while marked autolysosome formation was observed in GC-2 cells before 24-h culture in hypoxic conditions, apparent apoptosis was observed only after 24-h culture in hypoxic conditions. Caspase-8 siRNA treatment induced cell survival, accompanied by induction of the mature autophagosome, acidic vesicular organelle formation and autophagic flux. Furthermore, Beclin-1 overexpression markedly attenuated the impairment of spermatogenesis in mice by inhibiting apoptosis of spermatocytes. The results of this study demonstrate that hypoxia inhibits autophagy, which further enhances hypoxia-induced apoptosis of mouse spermatocytes by promoting caspase-8 activation in a time-dependent manner, suggesting that combined application of apoptosis inhibition and autophagy activation might be a therapeutic strategy for treating hypoxia-induced male infertility.

Improvement in the Quality of HbA1c Determination by Using Commutable Specimens With IFCC-Assigned Values.

BACKGROUND: To assess the usefulness of commutable secondary reference materials with International Federation of Clinical Chemistry (IFCC)-assigned values, for improving the quality of hemoglobin A1c (HbA 1c ) determination. METHODS: We recalibrated and evaluated 3 point-of-care-test (POCT) devices via 3 different method-specific central laboratory analyzers that were calibrated using commutable specimens with IFCC-assigned values. The staff members who performed POCT were also evaluated before and after training. RESULTS: HbA 1c levels measured with POCT devices showed significantly lesser bias after external mathematical calibration. The interlaboratory CVs for HbA 1c measurements decreased from 12% to 4% after training of POCT-device-operating personnel in the NycoCard group. The CVs in the DCA Vantage and Afinion groups also improved after training. CONCLUSION: Calibration of laboratory devices by specimens with IFCC-assigned values and by external mathematical calibration could improve the accuracy of POCT HbA 1c measurements. Also, standardized training could improve precision in POCT HbA 1c measurements, especially for semiautomated HbA 1c POCT devices.

The function of PlcR in Bacillus anthracis vaccine strain A16R.

Bacillus anthracis, B. thuringiensis and B. cereus are members of the B. cereus group. They share high genetic similarity. Whereas plcR (Phospholipase C regulator) usually encodes a functional pleiotropic activator protein in B. cereus and B. thuringiensis isolates, a characteristic nonsense mutation is found in all B. anthracis strains investigated, making the gene dysfunctional. To study the function of PlcR in B. anthracis, we used the B. cereus CMCC63301 genome as a template and constructed a recombinant expression plasmid pBE2A-plcR, and introduced it into the B. anthracis vaccine strain A16R, and then analyzed the activity of the hemolysin and sphingomyelinase. The results showed that transformation of B. anthracis with plasmid pBE2A-plcR carrying the native B. cereus plcR gene active the expression of sphingomyelinase gene, but did not activate expression of hemolysin genes of B. anthracis A16R.