NEMO-Binding Domain Peptide Attenuates Lipopolysaccharide-Induced Acute Lung Injury by Inhibiting the NF-κB Signaling Pathway

Echinatin attenuates acute lung injury and inflammatory responses via TAK1-MAPK/NF-κB and Keap1-Nrf2-HO-1 signaling pathways in macrophages

Echinatin is an active ingredient in licorice, a traditional Chinese medicine used in the treatment of inflammatory disorders. However, the protective effect and underlying mechanism of echinatin against acute lung injury (ALI) is still unclear. Herein, we aimed to explore echinatin-mediated anti-inflammatory effects on lipopolysaccharide (LPS)-stimulated ALI and its molecular mechanisms in macrophages. In vitro, echinatin markedly decreased the levels of nitric oxide (NO) and prostaglandin E2 (PGE2) in LPS-stimulated murine MH-S alveolar macrophages and RAW264.7 macrophages by suppressing inducible nitric oxide synthase and cyclooxygenase-2 (COX-2) expression. Furthermore, echinatin reduced LPS-induced mRNA expression and release of interleukin-1β (IL-1β) and IL-6 in RAW264.7 cells. Western blotting and CETSA showed that echinatin repressed LPS-induced activation of mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) pathways through targeting transforming growth factor-beta-activated kinase 1 (TAK1). Furthermore, echinatin directly interacted with Kelch-like ECH-associated protein 1 (Keap1) and activated the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway to enhance heme oxygenase-1 (HO-1) expression. In vivo, echinatin ameliorated LPS-induced lung inflammatory injury, and reduced production of IL-1β and IL-6. These findings demonstrated that echinatin exerted anti-inflammatory effects in vitro and in vivo, via blocking the TAK1-MAPK/NF-κB pathway and activating the Keap1-Nrf2-HO-1 pathway.

Fecal microbiota transplantation from HUC-MSC-treated mice alleviates acute lung injury in mice through anti-inflammation and gut microbiota modulation

Introduction

Acute lung injury (ALI) is a severe respiratory tract disorder facilitated by dysregulated inflammation, oxidative stress and intestinal ecosystem. Fecal microbiota transplantation (FMT) is a rapid method for gut microbiota (GM) reconstruction. Furthermore, our previous studies have confirmed that human umbilical cord mesenchymal stromal cells (HUC-MSCs) can alleviate ALI by improving GM composition. Therefore, we aimed to explore the efficacy and mechanism of FMT from HUC-MSCs-treated mice on ALI.

Methods

In brief, fresh feces from HUC-MSCs-treated mice were collected for FMT, and the mice were randomly assigned into NC, FMT, LPS, ABX-LPS, and ABX-LPS-FMT groups (n = 12/group). Subsequently, the mice were administrated with antibiotic mixtures to deplete GM, and given lipopolysaccharide and FMT to induce ALI and rebuild GM. Next, the therapeutic effect was evaluated by bronchoalveolar lavage fluid (BALF) and histopathology. Immune cells in peripheral blood and apoptosis in lung tissues were measured. Furthermore, oxidative stress- and inflammation-related parameter levels were tested in BALF, serum, lung and ileal tissues. The expressions of apoptosis-associated, TLR4/NF-κB pathway-associated, Nrf2/HO-1 pathway related and tightly linked proteins in the lung and ileal tissues were assessed. Moreover, 16S rRNA was conducted to assess GM composition and distribution.

Results

Our results revealed that FMT obviously improved the pathological damage of lung and ileum, recovered the immune system of peripheral blood, decreased the cell apoptosis of lung, and inhibited inflammation and oxidative stress in BALF, serum, lung and ileum tissues. Moreover, FMT also elevated ZO-1, claudin-1, and occludin protein expressions, activating the Nrf2/HO-1 pathway but hindering the TLR4/NF-κB pathway. Of note, the relative abundances of Bacteroides, Christensenella, Coprococcus, and Roseburia were decreased, while the relative abundances of Xenorhabdus, Sutterella, and Acinetobacter were increased in the ABX-LPS-FMT group.

Conclusion

FMT from HUC-MSCs-treated mice may alleviate ALI by inhibiting inflammation and reconstructing GM, additionally, we also found that the TLR4/NF-κB and Nrf2/HO-1 pathways may involve in the improvement of FMT on ALI, which offers novel insights for the functions and mechanisms of FMT from HUC-MSCs-treated mice on ALI.

Therapeutic Peptides for Treatment of Lung Diseases: Infection, Fibrosis, and Cancer

Various lung diseases endanger people's health. Side effects and pharmaceutical resistance complicate the treatment of acute lung injury, pulmonary fibrosis, and lung cancer, necessitating the development of novel treatments. Antimicrobial peptides (AMPs) are considered to serve as a viable alternative to conventional antibiotics. These peptides exhibit a broad antibacterial activity spectrum as well as immunomodulatory properties. Previous studies have shown that therapeutic peptides including AMPs had remarkable impacts on animal and cell models of acute lung injury, pulmonary fibrosis, and lung cancer. The purpose of this paper is to outline the potential curative effects and mechanisms of peptides in the three types of lung diseases mentioned above, which may be used as a therapeutic strategy in the future.

Glycyrrhizin mitigates acute lung injury by inhibiting the NLRP3 inflammasome in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Glycyrrhiza glabra L. is a widely used traditional Chinese medicine with antipyretic, detoxification, antibacterial and therapeutic effects against various diseases, including liver diseases. Glycyrrhizin (GL), the most significant active ingredient of Glycyrrhiza glabra L., exerts anti-inflammatory activity. However, the anti-inflammatory effect of GL remains to be determined.

AIM OF THIS STUDY

Consequently, this research was carried out to discover the effects and mechanism of action of GL on ALI.

MATERIALS AND METHODS

Cell experiments established an in vitro model of LPS-induced RAW 264.7 macrophages to verify the mechanism. The levels of NO, PEG₂, and inflammatory cytokines were estimated by ELISA. The expression levels of proteins related to the NF-κB signalling pathway and NLRP3 inflammasome were determined by Western blotting. The nuclear translocation of NF-κB p65 and ASC was tested through immunofluorescence analysis. The inhibitory effect of NLRP3 inhibitor MCC950 on macrophage was evaluated. Male BALB/C mice were selected to establish the ALI model. The experiment was randomly divided into five groups: control, ALI, GLL, GLH, and DEX. Pathological alterations were explored by H&E staining. The weight ratios of lung W/D, MPO, and inflammatory cytokines were evaluated by ELISA. The expression levels of proteins related to the NF-κB signalling pathway or NLRP3 inflammasome were analysed by Western blotting.

RESULTS

Here, we demonstrate that GL attenuates inflammation, nitric oxide, IL-18, IL-1β, TNF-α, IL-6, and PGE₂ levels and alveolar epithelial barrier permeability in macrophages and mice challenged with LPS. In addition, GL inhibits NLRP3 inflammasome initiation and activation and NF-κB signalling pathway activation.

CONCLUSION

This research demonstrates that GL may alleviate ALI inflammation by interfering with the NF-κB/NLRP3 inflammasome signalling pathway.

Binding domain peptide ameliorates alveolar hypercoagulation and fibrinolytic inhibition in mice with lipopolysaccharide-induced acute respiratory distress syndrome Via NF-κB signaling pathway

BACKGROUND

Alveolar hypercoagulation and fibrinolytic inhibition are shown to be associated with refractory hypoxemia in acute respiratory distress syndrome (ARDS), and the NF-κB pathway is involved in this process. The purpose of this study is to explore the role of NEMO-binding domain peptide (NBDP) in alleviating alveolar hypercoagulation and fibrinolytic inhibition induced by lipopolysaccharide (LPS) in ARDS mice and its related mechanisms.

MATERIALS AND METHODS

ARDS was induced by inhalation of LPS (mg/L) in adult male BALB/c mice. Mice were treated with intratracheal inhalation of NBDP or saline aerosol at increased concentrations 30 minutes before LPS administration. Six hours after LPS treatment, bronchoalveolar lavage fluids (BALF) were collected and then all mice were euthanized. In addition, coagulation and fibrinolysis associated factors in lung tissues and BALF were detected, and the activation of NF-κB signaling pathway was observed.

RESULTS

NBDP pretreatment dose-dependently inhibited the expression of tissue factor (TF) and plasminogen activator inhibitor (PAI) 1 in lung tissues, reduced the secretions of TF, PAI-1, thrombin-antithrombin (TAT) complex, and promoted activated protein C (APC) secretion in BALF induced by LPS. LPS-induced high expression of pulmonary procollagen peptide type lll (PIIIP) was also reduced in a dose-dependent manner under NBDP pretreatment. Western blotting showed that NBDP pretreatment significantly attenuated LPS-induced activation of IKKα/β, Iκα and NF-κB p65. NBDP pretreatment also inhibited the DNA binding activity of p65 induced by LPS. We also noticed that NBDP protected mice against LPS-induced lung injury in a dose-dependent manner.

CONCLUSIONS

The experimental findings demonstrate that through inhibiting the NF-κB signaling pathway, NBDP dose-dependently ameliorates LPS-induced alveolar hypercoagulation and fibrinolytic inhibition, which is expected to be a new therapeutic target to correct the abnormalities of alveolar coagulation and fibrinolytic pathways in ARDS.

Pharmacological Activation Of Aldehyde Dehydrogenase 2 Protects Against Heatstroke-Induced Acute Lung Injury by Modulating Oxidative Stress and Endothelial Dysfunction

Heatstroke (HS) can cause acute lung injury (ALI). Heat stress induces inflammation and apoptosis via reactive oxygen species (ROS) and endogenous reactive aldehydes. Endothelial dysfunction also plays a crucial role in HS-induced ALI. Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme that detoxifies aldehydes such as 4-hydroxy-2-nonenal (4-HNE) protein adducts. A single point mutation in ALDH2 at E487K (ALDH2*2) intrinsically lowers the activity of ALDH2. Alda-1, an ALDH2 activator, attenuates the formation of 4-HNE protein adducts and ROS in several disease models. We hypothesized that ALDH2 can protect against heat stress-induced vascular inflammation and the accumulation of ROS and toxic aldehydes. Homozygous ALDH2*2 knock-in (KI) mice on a C57BL/6J background and C57BL/6J mice were used for the animal experiments. Human umbilical vein endothelial cells (HUVECs) were used for the in vitro experiment. The mice were directly subjected to whole-body heating (WBH, 42°C) for 1 h at 80% relative humidity. Alda-1 (16 mg/kg) was administered intraperitoneally prior to WBH. The severity of ALI was assessed by analyzing the protein levels and cell counts in the bronchoalveolar lavage fluid, the wet/dry ratio and histology. ALDH2*2 KI mice were susceptible to HS-induced ALI in vivo. Silencing ALDH2 induced 4-HNE and ROS accumulation in HUVECs subjected to heat stress. Alda-1 attenuated the heat stress-induced activation of inflammatory pathways, senescence and apoptosis in HUVECs. The lung homogenates of mice pretreated with Alda-1 exhibited significantly elevated ALDH2 activity and decreased ROS accumulation after WBH. Alda-1 significantly decreased the WBH-induced accumulation of 4-HNE and p65 and p38 activation. Here, we demonstrated the crucial roles of ALDH2 in protecting against heat stress-induced ROS production and vascular inflammation and preserving the viability of ECs. The activation of ALDH2 by Alda-1 attenuates WBH-induced ALI in vivo.

Syndecan-1 Shedding by Matrix Metalloproteinase-9 Signaling Regulates Alveolar Epithelial Tight Junction in Lipopolysaccharide-Induced Early Acute Lung Injury

INTRODUCTION

Alveolar epithelial tight junction damage and glycocalyx syndecan-1 (SDC-1) degrading are key factors to pulmonary edema of acute lung injury (ALI). Matrix metalloproteinase-9 (MMP-9) was involved in glycocalyx shedding, which was vital in SDC-1 degrading. This study aimed to investigate the effects of MMP-9-mediated SDC-1 shedding on tight junction in LPS-induced ALI.

METHODS

Mice were intratracheally atomized with 5 mg/kg LPS to stimulate different periods and LPS stimulation for 6 hours for further studies. A549 cells was stimulated for 6 hours by active MMP-9 protein to assess the effects of active MMP-9 protein on SDC-1 and tight junction. Afterward, the mice treated with MMP-9 shRNA or A549 cells were treated with MMP-9 siRNA before LPS stimulation for 6 hours to explore the effects on glycocalyx SDC-1 and tight junction. Moreover, the mice were treated with recombinant SDC-1 protein or A549 cells were over-expressed by pc-SDC-1 before LPS stimulation for 6 hours to explore the effects of SDC-1 on tight junction.

RESULTS

The mice persistent exposure to LPS showed that MMP-9 expression, glycocalyx SDC-1 shedding (SDC-1 decreased in alveolar epithelium and increased in the BALF), tight junction impairment, FITC-albumin infiltration, and other phenomena began to appear after 6 hours of LPS treatment in this study. The levels of SDC-1 and tight junction significantly decreased by active MMP-9 protein stimulation for 6 hours in the A549 cells. Therefore, LPS stimulation for six hours was selected for investigating the underlying effects of MMP-9-mediated SDC-1 shedding on the alveolar epithelial tight junction and pulmonary edema. Further vivo analysis showed that down regulation MMP-9 expression by MMP-9 shRNA significantly alleviated glycocalyx SDC-1 shedding (SDC-1 increased in alveolar epithelium and decreased in the BALF), tight junction (occludin and ZO-1) damage, and FITC-albumin infiltration in LPS-induced early ALI mice. The vitro results also showed that MMP-9 siRNA alleviated glycocalyx SDC-1 shedding (SDC-1 increased in cell culture medium and decreased in cell surface) and tight junction damage by downregulating MMP-9 expression in LPS-stimulated A549 cells. In addition, pretreatment with recombinant mouse SDC-1 protein significantly alleviated glycocalyx (SDC-1 increased in alveolar epithelium) and tight junction damage, and FITC-albumin infiltration in LPS-induced early ALI mice. Overexpression SDC-1 by pc-SDC-1 also significantly decreased tight junction damage in LPS-stimulated A549 cells.

CONCLUSION

Glycocalyx SDC-1 shedding mediated by MMP-9 significantly aggravated tight junction damage, which further increased the pulmonary edema.

Ginsenoside Rb1 protects from Staphylococcus aureus-induced oxidative damage and apoptosis through endoplasmic reticulum-stress and death receptor-mediated pathways

Acute lung injury (ALI) is acute uncontrolled inflammation of lung tissue that leads to high fatality both in human and animals. Staphylococcus aureus (S. aureus) could be an opportunistic, versatile bacterial etiology of ALI. Ginsenoside Rb1 (Rb1) is extracted from the Panax ginseng, which displays a wide range of biological and pharmacological effects. However, protective effects of Rb1 in S. aureus-induced ALI though endoplasmic reticulum (ER) stress and death receptor-mediated pathways have not yet been reported. Therefore, present study was planned with the aims to investigate the antioxidant and anti-apoptotic properties of Rb1 through regulation of ER stress as well as death receptor-mediated pathways in ALI induced by S. aureus in mice. In this study, four groups of healthy Kunming mice (n = 48) were used. The S. aureus (80 µl; 1 ×10⁷ CFU/10 µl) was administered intranasally to establish mice model of ALI. After 24 h of onset of S. aureus-induced ALI, the mice were injected thrice with Rb1 (40 mg/kg) intraperitoneally six hours apart. Histopathology, enzyme linked immunosorbent assay (ELISA), real time quantitative polymerase chain reaction (RT-qPCR), Immunohistochemistry and western blotting assay were employed in the current study. Our results suggested that Rb1 administration save lungs from pulmonary injury by reducing wet to dry (W/D) ratio, protein levels, total cells, neutrophilic count, reactive oxygen species (ROS), myeloperoxidase (MPO), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (Gpx)1 depletion. Meanwhile, Rb1 therapy ameliorated histopathology alteration of lung tissue and pro-inflammatory cytokines secretion. The gene expression of ER stress marker (PERK, AFT-6, IRE1 and CHOP) were upregulated markedly (P < .05) in S. aureus-instilled groups, which was reduced by Rb1 administration that is reveled from the result findings of the RT-qPCR and immunoblot assay. The results of immunohistochemistry for CHOP indicated the increased expression in S. aureus groups which in turn ameliorated by Rb1 treatment. The mRNA expression demonstrated that death receptor-associated genes (FasL, Fas, FADD and caspase-8) showed up-regulation in S. aureus group. The similar findings were observed for the protein expression of caspase-8, FADD and Fas. Rb1 treatment markedly (P < .05) reversed protein and mRNA expression levels of these death receptor-associated genes when compared to the S. aureus group. Taken together, Rb1 attenuated S. aureus-induced oxidative damage via the ER stress-mediated pathway and apoptosis through death receptor-mediated pathway. Conclusively, our findings provide an insight into preventive mechanism of Rb1 in ALI caused by S. aureus and hence proven a scientific baseline for the therapeutic application of Rb1.

Vitamin D Inhibits Lipopolysaccharide (LPS)-Induced Inflammation in A549 Cells by Downregulating Inflammatory Cytokines

BACKGROUND Studies have shown that lung inflammation affects lung function, with life-threatening results. Vitamin D may play an important role in inhibiting inflammatory cytokines. Vitamin D deficiency is related to several lung problems, including respiratory distress syndrome, alveolar inflammation, epithelial damage, and hypoxia. Few studies have evaluated the benefits of vitamin D in preventing inflammation in alveolar cells. MATERIAL AND METHODS We developed a cell inflammation model induced by lipopolysaccharide (LPS) treatment. The effects of vitamin D on LPS-induced inflammation in A549 cells were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the anti-inflammatory mechanism of vitamin D was evaluated using western blot analysis. RESULTS Our results indicated that vitamin D promoted A549 cell survival following LPS-induced inflammation by downregulating nuclear factor nuclear factor kappa light chain enhancer of activated B cells, tumor necrosis factor-alpha, interleukin (IL)-1ß, IL-6, and IL-12. CONCLUSIONS Our results indicated that vitamin D has the potential to manage lung inflammation, although further studies are needed.

Triptolide dose-dependently improves LPS-induced alveolar hypercoagulation and fibrinolysis inhibition through NF-κB inactivation in ARDS mice

BACKGROUND

Alveolar hypercoagulation and fibrinolysis inhibition were associated with the refractory hypoxemia and the high mortality in patient with acute respiratory distress syndrome (ARDS), and NF-κB pathway was confirmed to contribute to the process. Triptolide (TP) significantly inhibited NF-κB pathway and thus depressed accessive inflammatory response in ARDS. We speculate that TP could improve alveolar hypercoagulation and fibrinolytic inhibition in LPS-induced ARDS via NF-κB inactivation.

PURPOSE

The aim of this experiment was to explore the efficacy and potential mechanism of TP on alveolar hypercoagulation and fibrinolysis inhibition in LPS-induced ARDS in mice.

METHODS

50 μl of LPS (5 mg/ml) was inhalationally given to C57BL/6 mice to set up ARDS model. Male mice were randomly accepted with LPS, LPS + TP (1 μg/kg, 10 μg/kg, 50 μg/kg respectively), or with NEMO Binding domain peptide (NBD), an inhibitor of NF-κB. TP (1 μg/kg, 10 μg/kg, 50 μg/kg) were intraperitoneally injected or 10 μg/50 μl of NBD solution were inhaled 30 min before LPS inhalation. A same volume of normal saline (NS) substituted for TP in mice in control. The endpoint of experiment was at 8 hours after LPS stimulation. Pulmonary tissues were taken for hematoxylin-eosin (HE) staining, wet / dry ratio and for lung injury scores (LIS). Tissue factor (TF) and plasminogen activator inhibitor (PAI)-1 in lung tissue were detected by Western-blotting and by quantitative Real-time PCR(qPCR) respectively. Concentrations of TF, PAI-1, thrombin-antithrombin complex (TAT), procollagen peptide type Ⅲ (PⅢP) and activated protein C (APC) in bronchoalveolar lavage fluid (BALF) were measured by ELISA. NF-κB activation and p65-DNA binding activity in pulmonary tissue were simultaneously determined.

RESULTS

LPS stimulation resulted in pulmonary edema, neutrophils infiltration, obvious alveolar collapse, interstitial congestion, with high LIS, which were all dose-dependently ameliorated by Triptolide. LPS also dramatically promoted the expressions of TF and PAI-1 either in mRNA or in protein in lung tissue, and significantly stimulated the secretions of TF, PAI-1, TAT, PⅢP but inhibited APC production in BALF, which were all reversed by triptolide treatment in dose-dependent manner. TP dose-dependently inhibited the activation of NF-κB pathway induced by LPS, indicated by the changes of phosphorylations of p65 (p-p65), p-IKKα/β and p-IκBα, and weakened p65-DNA binding activity. TP and NBD had same efficacies either on alveolar hypercoagulation and fibrinolysis inhibition or on NF-κB signalling pathway in ARDS mice.

CONCLUSIONS

TP dose-dependently improves alveolar hypercoagulation and fibrinolysis inhibition in ARDS mice through inhibiting NF-κB signaling pathway. Our data demonstrate that TP is expected to be an effective selection in ARDS.

Nuclear factor-kappaB regulates the transcription of NADPH oxidase 1 in human alveolar epithelial cells

Objective

Acute lung injury (ALI) is characterized by inflammation and oxidative stress. Nuclear factor-kappaB (NF-κB) mediates the expression of various inflammation-related genes, including the NADPH oxidase family. This study aimed to identify the potential regulatory role of NF-κB on NADPH oxidases in tumor necrosis factor-α (TNF-α)-induced oxidative stress in human alveolar epithelial cells.

Methods

A549 cells were treated with TNF-α for 24 h to establish ALI cell models. RT-PCR, western blot, assessment of oxidative stress, Alibaba 2.1 online analysis, electrophoretic mobility shift assays and luciferase reporter analysis were employed to identify the potential regulatory role of NF-κB on NADPH oxidases in TNF-α-induced oxidative stress in human alveolar epithelial cells.

Results

The expression of NF-κB/p65 was notably upregulated in TNF-α-stimulated A549 cells. NF-κB knockdown by siRNA significantly inhibited the TNF-α-induced oxidative stress. Moreover, NF-κB/p65 siRNA could inhibit the activation of NOX1, NOX2 and NOX4 mRNA and protein expression in TNF-α-stimulated A549 cells. The next study demonstrated that NF-κB activated the transcription of NOX1 by binding to the -261 to -252 bp (NOX1/κB2, TAAAAATCCC) region of NOX1 promoter in TNF-α-stimulated A549 cells.

Conclusion

Our data demonstrated that NF-κB can aggravate TNF-α-induced ALI by regulating the oxidative stress response and the expression of NOX1, NOX2 and NOX4. Moreover, NF-κB could promote the NOX1 transcriptional activity via binding its promoter in TNF-α-stimulated A549 cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01464-z.

Targeting NF-κB by the Cell-Permeable NEMO-Binding Domain Peptide Improves Albuminuria and Renal Lesions in an Experimental Model of Type 2 Diabetic Nephropathy

Diabetic nephropathy (DN) is a multifactorial disease characterized by hyperglycemia and close interaction of hemodynamic, metabolic and inflammatory factors. Nuclear factor-κB (NF-κB) is a principal matchmaker linking hyperglycemia and inflammation. The present work investigates the cell-permeable peptide containing the inhibitor of kappa B kinase γ (IKKγ)/NF-κB essential modulator (NEMO)-binding domain (NBD) as therapeutic option to modulate inflammation in a preclinical model of type 2 diabetes (T2D) with DN. Black and tan, brachyuric obese/obese mice were randomized into 4 interventions groups: Active NBD peptide (10 and 6 µg/g body weight); Inactive mutant peptide (10 µg/g); and vehicle control. In vivo/ex vivo fluorescence imaging revealed efficient delivery of NBD peptide, systemic biodistribution and selective renal metabolization. In vivo administration of active NBD peptide improved albuminuria (>40% reduction on average) and kidney damage, decreased podocyte loss and basement membrane thickness, and modulated the expression of proinflammatory and oxidative stress markers. In vitro, NBD blocked IKK-mediated NF-κB induction and target gene expression in mesangial cells exposed to diabetic-like milieu. These results constitute the first nephroprotective effect of NBD peptide in a T2D mouse model that recapitulates the kidney lesions observed in DN patients. Targeting IKK-dependent NF-κB activation could be a therapeutic strategy to combat kidney inflammation in DN.

NEMO-binding domain peptides alleviate perihematomal inflammation injury after experimental intracerebral hemorrhage

Inflammation aggravates the lethal consequences of intracerebral hemorrhage. Recently, many studies have found that nuclear factor-κB (NF-κB) is a crucial transcription factor that initiates inflammation in the perihematomal region of ICH. NF-κB essential modulator (NEMO)-binding domain (NBD) peptide, a cell-permeable peptide spanning the NBD of IKKα or IKKβ, functions as a highly specific inhibitor of NF-κB. This peptide can negatively regulate the NF-κB pathway. The present study aimed to explore the effects and underlying pathomechanisms of NBD peptides after ICH. Striatum infusion of whole blood or saline was performed on C57BL/6 mice (n = 198). Experimental animals were administered NBD or control (mutated) peptides 2 h before or after ICH by intracerebroventricular injection (icv.). NBD peptides significantly inhibited edema formation, ameliorated the neurological deficits, markedly reduced IκBα and p65 phosphorylation, blocked nuclear translocation of p65, and upregulated IκBα expression by NF-κB after ICH induction. Using an in vitro hemin toxicity model, we investigated the effects of NBD peptides on microglial inflammation. We found that NBD peptides suppressed microglia inflammation and lowered the expression of TNF-α and IL-1β in both in vivo and in vitro experiments. Further experiments were performed in mice and cultured microglia, which treated with NBD peptides in the presence of p65 siRNA confirmed that the specificity of NBD peptides inhibit ICH-induced NF-κB activation. This study demonstrated that NBD peptides exert a neuroprotective role after ICH and might be a potential candidate for a novel therapeutic strategy for ICH.

NF-κB p65 Knock-down inhibits TF, PAI-1 and promotes activated protein C production in lipopolysaccharide-stimulated alveolar epithelial cells type II

Purpose/aim: Activated coagulation and reduced fibrinolysis in alveolar compartment are an important characteristics in acute respiratory distress syndrome (ARDS). Alveolar epithelial cell type II (AECII) participates in regulating the intra-alveolar abnormalities of coagulation and fibrinolysis mainly through adjusting the productions of tissue factor (TF), plasminogen activator inhibitor (PAI)-1 and activated protein C (APC) in ARDS. NF-κB signal pathway may be involved in coagulation regulation in sepsis-induced ALI. The purpose of this study was to testify the hypothesis that NF-κB p65 (p65) knock-down would improve the abnormalities of coagulation and fibrinolysis mediated by lipopolysaccharide (LPS) stimulation in AECII.

MATERIALS AND METHODS

p65 gene knock-down in AECII was achieved by small interfering RNA (siRNA) transfection. Rat AECII (RLE-6TN) with or without p65 gene knock-down were stimulated by LPS for 24 hours. And then cytolysate was used for TF, PAI-1 expression examination, and supernatant was collected for TF, PAI-1 and PC concentrations determination. Activation of NF-κB canonical pathway was simultaneously checked by western-blotting, RT-PCR and immunofluorescence respectively.

RESULTS

TF, PAI-1 expressions in normal cells obviously increased under LPS stimulation with NF-κB canonical pathway activation represented by high levels of p65, p-p65, p-IκB with increased nuclear translocation of p-p65. Cells with NF-κB p65 knock-down, however, showed significant decreases in TF, PAI-1, p65, p-p65, p-IκB expressions following LPS stimulation with significant reduction in p-p65 nuclear translocation as compared to normal and siRNA control cells. The high concentrations of TF, PAI-1 and low level of APC in supernatant induced by LPS in normal cells were significantly reversed through p65 knock-down.

CONCLUSIONS

The experimental findings demonstrate that NF-kB signaling pathway is involved in regulating the expressions of coagulation and fibrinolysis factors in LPS-stimulated AECII, which suggest that NF-kB signaling pathway may be a new target to correct intra-alveolar coagulation and fibrinolytic abnormalities in ARDS.

Cell-Permeable Bicyclic Peptidyl Inhibitors against NEMO-IκB Kinase Interaction Directly from a Combinatorial Library

Macrocyclic peptides are capable of binding to flat protein surfaces such as the interfaces of protein-protein interactions with antibody-like affinity and specificity, but generally lack cell permeability in order to access intracellular targets. In this work, we designed and synthesized a large combinatorial library of cell-permeable bicyclic peptides, in which the first ring consisted of randomized peptide sequences for potential binding to a target of interest, while the second ring featured a family of different cell-penetrating motifs, for both cell penetration and target binding. The library was screened against the IκB kinase α/β (IKKα/β)-binding domain of NF-κB essential modulator (NEMO), resulting in the discovery of several cell-permeable bicyclic peptides, which inhibited the NEMO-IKKβ interaction with low μM IC50 values. Further optimization of one of the hits led to a relatively potent and cell-permeable NEMO inhibitor (IC50 = 1.0 μM), which selectively inhibited canonical NF-κB signaling in mammalian cells and the proliferation of cisplatin-resistant ovarian cancer cells. The inhibitor provides a useful tool for investigating the biological functions of NEMO/NF-κB and a potential lead for further development of a novel class of anti-inflammatory and anticancer drugs.

Nuciferine Ameliorates Inflammatory Responses by Inhibiting the TLR4-Mediated Pathway in Lipopolysaccharide-Induced Acute Lung Injury

Acute lung injury (ALI) is a complex syndrome with sepsis occurring in critical patients, who usually lack effective therapy. Nuciferine is a primary bioactive component extracted from the lotus leaf, and it displays extensive pharmacological functions, including anti-cancer, anti-inflammatory, and antioxidant properties. Nevertheless, the effects of nuciferine on lipopolysaccharide (LPS)-stimulated ALI in mice has not been investigated. ALI of mice stimulated by LPS was used to determine the anti-inflammatory function of nuciferine. The molecular mechanism of nuciferine was performed on RAW264.7 macrophage cells. The results of pathological section, myeloperoxidase activity and lung wet/dry ratio showed that nuciferine alleviated LPS-induced lung injury (p < 0.05). qRT-PCR and ELISA experiments suggested that nuciferine inhibited TNF-α, IL-6, and IL-1β secretion in tissues and RAW264.7 cells but increased IL-10 secretion (p < 0.05). Molecular studies showed that TLR4 expression and nuclear factor (NF)-κB activation were both inhibited by nuciferine treatment (p < 0.05). To further investigate the anti-inflammatory mechanism of nuciferine, TLR4 was knocked down. When TLR4 was silenced, LPS induced the production of IL-1β, and TNF-α was markedly decreased by TLR4-siRNA and nuciferine treatment in LPS-induced RAW264.7 cells (p < 0.05). These results suggested that nuciferine had the ability to protect against LPS-stimulated ALI. Thus, nuciferine may be a potential drug for treating LPS-induced pulmonary inflammation.

Necrostatin-1 attenuates lipopolysaccharide-induced acute lung injury in mice

AIM OF THE STUDY

Receptor-interacting protein (RIP) kinase family members are involved in several biological processes. However, their role in acute lung injury (ALI) is still unclear. In the present study, we aim to determine the expression and function of RIP kinase family in ALI.

MATERIALS AND METHODS

In the present study, ALI was induced in BALB/c male mice by intravenously injecting lipopolysaccharide (LPS). The expression levels of the RIP kinase family in ALI mice were determined using western blotting and immunohistochemical staining. The specific RIP-1 inhibitor, necrostatin-1, was used to treat LPS-induced ALI mice, followed by survival time recording, as well as histopathological and immunohistochemical staining of lung tissues, western blotting, myeloperoxidase (MPO) assay and enzyme-linked immunosorbent assay (ELISA) of related cytokines and downstream target expression.

RESULTS

We found that RIP-1 expression was upregulated in the lung of ALI mice and inhibition of RIP-1 by necrostatin-1 significantly prolonged the survival time of mice, which was accompanied by less serve lung injury. Furthermore, lower expression of pro-inflammatory cytokines (interleukin [IL]-6, tumor necrosis factor [TNF]-α, IL-8, cyclooxygenase [COX]-2, monocyte chemoattractant protein [MCP]-1, and IL-1β), MPO and nuclear factor (NF)-κB activation were found in bronchoalveolar lavage fluid (BALF) and lung tissues of necrostatin-1-treated ALI mice. Necrostatin-1 also attenuated LPS-induced pro-inflammatory cytokine expression and NF-κB activation in RAW 264.7 cells.

CONCLUSIONS

In summary, necrostatin-1 protected against LPS-induced ALI in mice by inhibiting inflammation and pulmonary NF-κB activation. Thus, necrostatin-1 could be a novel therapeutic strategy for ALI.