Monoclonal antibody against Toll-like receptor 4 attenuates ventilator-induced lung injury in rats by inhibiting MyD88- and NF-κB-dependent signaling

Retracted article: Protective effects of ulinastatin on rats with acute lung injury induced by lipopolysaccharide

Qitong Lu, Zhiyong Liu, Wei He and Xin Chu. Protective effects of ulinastatin on rats with acute lung injury induced by lipopolysaccharide. Bioengineered. 2021 Oct. doi: 10.1080/21655979.2021.1987083.Since publication, significant concerns have been raised about the compliance with ethical policies for human research and the integrity of the data reported in the article.When approached for an explanation, the authors provided some original data but were not able to provide all the necessary supporting information. As verifying the validity of published work is core to the scholarly record's integrity, we are retracting the article. All authors listed in this publication have been informed.We have been informed in our decision-making by our editorial policies and the COPE guidelines. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as 'Retracted.'

Optimization of a Lethal, Combat-Relevant Model of Sterile Inflammation in Mice for Drug Candidate Screening

INTRODUCTION

Extensive trauma, commonly seen in wounded military Service Members, often leads to a severe sterile inflammation termed systemic inflammatory response syndrome (SIRS), which can progress to multiple organ dysfunction syndrome (MODS) and death. MODS is a serious threat to wounded Service Members, historically causing 10% of all deaths in trauma admissions at a forward deployed combat hospital. The importance of this problem will be exacerbated in large-scale combat operations, in which evacuation will be delayed and care of complex injuries at lower echelons of care may be prolonged. The main goal of this study was to optimize an existing mouse model of lethal SIRS/MODS as a therapeutic screening platform for the evaluation of immunomodulatory drugs.

MATERIALS AND METHODS

Male C57BL/6 mice were euthanized, and the bones and muscles were collected and blended into a paste termed tissue-bone matrix (TBX). The TBX at 12.5%-20% relative to body weight of each recipient mouse was implanted into subcutaneous pouches created on the dorsum of anesthetized animals. Mice were observed for clinical scores for up to 48 hours postimplantation and euthanized at the preset point of moribundity. To test effects of anesthetics on TBX-induced mortality, animals received isoflurane or ketamine/xylazine (K/X). In a separate set of studies, mice received TBX followed by intraperitoneal injection with 20 mg/kg or 40 mg/kg Eritoran or a placebo carrier. All Eritoran studies were performed in a blinded fashion.

RESULTS

We observed that K/X anesthesia significantly increased the lethality of the implanted TBX in comparison to inhaled anesthetics. Although all the mice anesthetized with isoflurane and implanted with 12.5% TBX survived for 24 hours, 60% of mice anesthetized with K/X were moribund by 24 hours postimplantation. To mimic more closely the timing of lethal SIRS/MODS following polytrauma in human patients, we extended observation to 48 hours. We performed TBX dose-response studies and found that as low as 15%, 17.5%, and 20% TBX caused moribundity/mortality in 50%, 80%, and 100% mice, respectively, over a 48-hour time period. With 17.5% TBX, we tested if moribundity/mortality could be rescued by anti-inflammatory drug Eritoran, a toll-like receptor 4 antagonist. Neither 20 mg/kg nor 40 mg/kg doses of Eritoran were found to be effective in this model.

CONCLUSIONS

We optimized a TBX mouse model of SIRS/MODS for the purpose of evaluating novel therapeutic interventions to prevent trauma-related pathophysiologies in wounded Service Members. Negative effects of K/X on lethality of TBX should be further evaluated, particularly in the light of widespread use of ketamine in treatment of pain. By mimicking muscle crush, bone fracture, and necrosis, the TBX model has pleiotropic effects on physiology and immunology that make it uniquely valuable as a screening tool for the evaluation of novel therapeutics against trauma-induced SIRS/MODS.

Effects of butyrate on intestinal ischemia-reperfusion injury via the HMGB1-TLR4-MyD88 signaling pathway

BACKGROUND

This study combined bioinformatics and experimental verification in a mouse model of intestinal ischemia-reperfusion injury (IRI) to explore the protection mechanism exerted by butyrate against IRI.

METHODS

GeneCards, Bioinformatics Analysis Tool for Molecular Mechanisms of Traditional Chinese Medicine and GSE190581 were used to explore the relationship between butyrate and IRI and aging. Protein-protein interaction networks involving butyrate and IRI were constructed via the STRING database, with hub gene analysis performed through Cytoscape. Functional enrichment analysis was conducted on intersection genes. A mouse model of IRI was established, followed by direct arterial injection of butyrate. The experiment comprised five groups: normal, sham, model, vehicle, low-dose butyrate, and high-dose butyrate. Intestinal tissue observation was done via transmission electron microscopy (TEM), histological examination via hematoxylin and eosin (H&E) staining, tight junction proteins detection via immunohistochemistry, and Western blot analysis of hub genes. Drug-target interactions were evaluated through molecular docking.

RESULTS

Butyrate protected against IRI by targeting 458 genes, including HMGB1 and TLR4. Toll-like receptor pathway was implicated. Butyrate improved intestinal IRI by reducing mucosal damage, increasing tight junction proteins, and lowering levels of HMGB1, TLR4, and MyD88. Molecular docking showed strong binding energies between butyrate and HMGB1 (-3.7 kcal/mol) and TLR4 (-3.8 kcal/mol).

CONCLUSIONS

According to bioinformatics predictions, butyrate mitigates IRI via multiple-target and multiple-channel mechanisms. The extent of IRI can be reduced by butyrate through the inhibition of the HMGB1-TLR4-MyD88 signaling pathway, which is related to senescence.

Selenium Antagonizes Cadmium-Induced Inflammation and Oxidative Stress via Suppressing the Interplay between NLRP3 Inflammasome and HMGB1/NF-κB Pathway in Duck Hepatocytes

Cadmium (Cd) is a toxic heavy metal that can accumulate in the liver of animals, damaging liver function. Inflammation and oxidative stress are considered primary causes of Cd-induced liver damage. Selenium (Se) is an antioxidant and can resist the detrimental impacts of Cd on the liver. To elucidate the antagonism of Se on Cd against hepatocyte injury and its mechanism, duck embryo hepatocytes were treated with Cd (4 μM) and/or Se (0.4 μM) for 24 h. Then, the hepatocyte viability, oxidative stress and inflammatory status were assessed. The findings manifested that the accumulation of reactive oxygen species (ROS) and the levels of pro-inflammatory factors were elevated in the Cd group. Simultaneously, immunofluorescence staining revealed that the interaction between NOD-like receptor pyran domain containing 3 (NLRP3) and apoptosis-associated speck-like protein (ASC) was enhanced, the movement of high-mobility group box 1 (HMGB1) from nucleus to cytoplasm was increased and the inflammatory response was further amplified. Nevertheless, the addition of Se relieved the above-mentioned effects, thereby alleviating cellular oxidative stress and inflammation. Collectively, the results suggested that Se could mitigate Cd-stimulated oxidative stress and inflammation in hepatocytes, which might be correlated with the NLRP3 inflammasome and HMGB1/nuclear factor-κB (NF-κB) signaling pathway.

Myd88 knockdown with RNA interference induces in vitro immune hyporesponsiveness in dendritic cells from rhesus monkeys

Immature dendritic cells (imDCs) are activated and mature to initiate an adaptive immune response, resulting in allograft rejection and transplantation failure. Myeloid differentiation factor 88 (Myd88) is a key factor in the Toll-like receptor (TLR) signaling pathway. Here, we investigated the effect of Myd88 silencing on DC function and immune response. CD34 + cells were isolated from the bone marrow of rhesus monkeys by the immunomagnetic bead method and then infected with an adenovirus expressing Myd88-specific short hairpin RNA (sh-Myd88). sh-NC (nontargeting negative control)- or sh-Myd88-infected DCs were treated with lipopolysaccharide (LPS) for another 48 h to induce DCS maturation. The maturation of DCs was identified by immunofluorescence staining for MHCII, CD80, and CD86. DC apoptosis was examined using Annexin V/PI staining. DC-related cytokine levels (IFN-γ and IL-12) were assessed by ELISA. A mixed lymphocyte reaction (MLR) was performed to test the effect of Myd88-silenced DCs on T lymphocytes in vitro. The results showed that compared with control or sh-NC-infected DCs, Myd88-silenced DCs had lower MHCII, CD80, CD86, and DC-related cytokine (IFN-γ and IL-12) levels. Myd88 did not affect the apoptosis of DCs. MLR demonstrated that Myd88 silencing could effectively block LPS-activated T cell proliferation in vitro. These data were consistent with the characteristics of tolerogenic DCs. In conclusion, our data indicated that Myd88 silencing could inhibit the maturation of imDCs and alleviate immune rejection, which provides a reference for immune tolerance in clinical liver transplantation.

Neutrophil-Derived IL-17 Promotes Ventilator-Induced Lung Injury via p38 MAPK/MCP-1 Pathway Activation

Ventilator-induced lung injury (VILI) is one of the most common complications of mechanical ventilation and can severely affect health. VILI appears to involve excessive inflammatory responses, but its pathogenesis has not yet been clarified. Since interleukin-17 (IL-17) plays a critical role in the immune system and the development of infectious and inflammatory diseases, we investigated here whether it plays a role in VILI. In a mouse model of VILI, mechanical ventilation with high tidal volume promoted the accumulation of lung neutrophils, leading to increased IL-17 levels in the lung, which in turn upregulated macrophage chemoattractant protein-1 via p38 mitogen-activated protein kinase. Depletion of neutrophils decreases the production IL-17 in mice and inhibition of IL-17 significantly reduced HTV-induced lung injury and inflammatory response. These results were confirmed in vitro using RAW264.7 macrophage cultures. Our results suggest that IL-17 plays a pro-inflammatory role in VILI and could serve as a new target for its treatment.

First case of low-dose umbilical cord blood therapy for pediatric acute respiratory distress syndrome induced by Pneumocystis carinii pneumonia

Objective

This study aimed to present the case of a boy with acute distress syndrome (ARDS) treated with low-dose umbilical cord blood (UCB) therapy and explore the underlying possible mechanism.

Methods

A 7-year-old boy with severe Pneumocystis carinii pneumonia and severe ARDS was treated with allogeneic UCB as salvage therapy.

Results

The patient did not improve after being treated with lung protective ventilation, pulmonary surfactant replacement, and extracorporeal membrane oxygenation (ECMO) for 30 days. However, his disease reversed 5 days after allogeneic UCB infusion, and he weaned from ECMO after 7 days of infusion. Bioinformatics confirmed that his Toll-like receptor (TLR) was abnormal before UCB infusion. However, after the infusion, his immune system was activated and repaired, and the TLR4/MyD88/NF-κB signaling pathway was recovered.

Conclusion

Allogenic UCB could treat ARDS by repairing the TLR4/MyD88/NF-κB signaling pathway, thereby achieving stability of the immune system.

Obesity Attenuates Ventilator-Induced Lung Injury by Modulating the STAT3-SOCS3 Pathway

Background

Ventilator-induced lung injury (VILI) is characterized by vascular barrier dysfunction and suppression of alveolar fluid clearance (AFC). Obesity itself leads to chronic inflammation, which may initiate an injurious cascade to the lungs and simultaneously induce a protective feedback. In this study, we investigated the protective mechanism of obesity on VILI in a mouse model.

Methods

The VILI model was set up via 6-h mechanical ventilation with a high tidal volume. Parameters including lung injury score, STAT3/NFκB pathway, and AFC were assessed. Mice with diet-induced obesity were obtained by allowing free access to a high-fat diet since the age of 3 weeks. After a 9-week diet intervention, these mice were sacrificed at the age of 12 weeks. The manipulation of SOCS3 protein was achieved by siRNA knockdown and pharmaceutical stimulation using hesperetin. WNK4 knockin and knockout obese mice were used to clarify the pathway of AFC modulation.

Results

Obesity itself attenuated VILI. Knockdown of SOCS3 in obese mice offset the protection against VILI afforded by obesity. Hesperetin stimulated SOCS3 upregulation in nonobese mice and provided protection against VILI. In obese mice, the WNK4 axis was upregulated at the baseline, but was significantly attenuated after VILI compared with nonobese mice. At the baseline, the manipulation of SOCS3 by siRNA and hesperetin also led to the corresponding alteration of WNK4, albeit to a lesser extent. After VILI, WNK4 expression correlated with STAT3/NFκB activation, regardless of SOCS3 status. Obese mice carrying WNK4 knockout had VILI with a severity similar to that of wild-type obese mice. The severity of VILI in WNK4-knockin obese mice was counteracted by obesity, similar to that of wild-type nonobese mice only.

Conclusions

Obesity protects lungs from VILI by upregulating SOCS3, thus suppressing the STAT3/NFκB inflammatory pathway and enhancing WNK4-related AFC. However, WNK4 activation is mainly from direct NFκB downstreaming, and less from SOCS3 upregulation. Moreover, JAK2-STAT3/NFκB signaling predominates the pathogenesis of VILI. Nevertheless, the interaction between SOCS3 and WNK4 in modulating VILI in obesity warrants further investigation.

Baicalin relieves Mycoplasma pneumoniae infection‑induced lung injury through regulating microRNA‑221 to inhibit the TLR4/NF‑κB signaling pathway

Mycoplasma pneumoniae (MP) is a common pathogen that can cause respiratory infections. MP pneumonia (MPP) leads to numerous complications, including lung injury and even death. The present study aimed to investigate the protective effects of Baicalin treatment on MP infection‑induced lung injury and the molecular mechanism underlying these effects. Briefly, after mice were infected intranasally by MP and treated with Baicalin (80 mg/kg), serum levels of MP‑immunoglobulin M (IgM) were detected by ELISA. The expression levels of C‑reactive protein (CRP) in lung tissue were detected by immunohistochemistry and the bronchoalveolar lavage fluid (BALF) was examined by ELISA. Inflammatory factors and inflammatory cells in the BALF were assessed. The expression levels of microRNA (miR)‑221 in lung tissue were examined by reverse transcription‑quantitative PCR and pathological changes in lung tissue were detected by H&E staining. Cell apoptosis was evaluated by TUNEL assay and the protein expression levels of TLR4, MyD88 and NF‑κB were detected by western blotting. Baicalin treatment significantly reduced serum levels of MP‑IgM and CRP expression in lung tissue during MP infection. In addition, Baicalin decreased the levels of IL‑1β, IL‑6, IL‑18 and TNF‑α in the BALF, and the number of inflammatory cells. Baicalin also reduced the inflammatory infiltration in lung tissue induced by MP infection, improved the pathological changes detected in lung tissue, reduced apoptosis, and downregulated the protein expression levels of TLR4, MyD88 and NF‑κB. Furthermore, Baicalin treatment downregulated the expression of miR‑221 and the protective effects of Baicalin were attenuated by miR‑221 overexpression. In conclusion, Baicalin has a therapeutic effect on mice with MP infection‑induced lung injury, which may be related to inhibition of miR‑221 expression and regulation of the TLR4/NF‑κB signaling pathway.

Distinct effects of different doses of kaempferol on D‑GalN/LPS‑induced ALF depend on the autophagy pathway

Kaempferol, a flavonoid compound, has various biological functions, such as anti-inflammatory and antitumor activities. Acute liver failure (ALF) is a lethal clinical syndrome that occurs due to severe damage of the liver function. In the present study, the mechanisms underlying the therapeutic effects of kaempferol in ALF were evaluated. An ALF mouse model was established using D-galactosamine (D-GalN; 700 mg/kg)/lipopolysaccharide (LPS; 10 µg/kg). A total of 2 h before the administration of D-GalN/LPS, mice were pretreated with different doses of kaempferol (2.5, 5, 10, 20 and 40 mg/kg), and 6 h after injection of D-GalN/LPS, mice were euthanized. The survival rate, liver function and levels of inflammatory cytokines were assessed. The results demonstrated that kaempferol pretreatment protected hepatocytes from ALF induced by D-GalN/LPS via regulation of the autophagy pathway, both in vivo and in vitro. Pretreatment with a high dose of kaempferol significantly decreased the survival rates and increased severe liver damage; however, pretreatment with a low dose of kaempferol had the opposite effect. Furthermore, pretreatment with a high dose of kaempferol enhanced the levels of proinflammatory cytokines [TNF-α, IL-6, IL-12p40, IL-1β, C-X-C motif chemokine ligand (CXCL)-2, CXCL-10] and markers of the MAPK signaling pathway [phosphorylated (p)-JNK, p-ERK, p-p38], whereas pretreatment with a low dose of kaempferol had the opposite effect. Pretreatment with a high dose of kaempferol decreased autophagy, whereas pretreatment with a low dose of kaempferol increased autophagy in vivo and in vitro. It was also shown that pretreatment with 3-methyadenine or autophagy related 7 small interfering RNA, to inhibit autophagy, partially abrogated the hepatoprotective effects of pretreatment with 5 mg/kg kaempferol in the ALF mouse model. These results demonstrate that the effects of different doses of kaempferol on D-GalN/LPS-induced ALF varies based on the dose, and that kaempferol exerted its effects via regulation of the autophagy pathway.

TLR4/TRAF6/NOX2 signaling pathway is involved in ventilation-induced lung injury via endoplasmic reticulum stress in murine model

In ventilation-induced lung injury (VILI), prolonged nonpathogen-mediated inflammation is triggered as a result of alveolar hyperinflation. In our previous study, we suggested that endoplasmic reticulum (ER) stress-mediated inflammation was involved in VILI, but how ER stress is triggered remains unknown. Toll-like receptor 4 (TLR4) activation plays an important role in mechanical ventilation (MV)-induced lung inflammation, however, it is unknown whether ER stress is activated by TLR4 to participate in VILI. In this study, C57BL/6 mice were exposed to MV with high tidal volumes (HTV 20 ml/kg). Mice were pretreated with TAK-242 the TLR4 inhibitor, C25-140, the TRAF6 inhibitor, or GSK2795039, the NOX2 inhibitor. Lung tissue and bronchoalveolar lavage fluid (BALF) were collected to measure lung injury, inflammatory responses and mRNA/protein expression associated with ER stress and the TLR4/TRAF6/NOX2 signaling pathway. Our results indicate that MV with HTV caused the TLR4/TRAF6/NOX2 signaling pathway activation and production of large amounts of ROS, which led to ER stress and NF-κB mediated inflammation in VILI. Furthermore, TLR4/TRAF6/NOX2 signaling pathway inhibition attenuated ER stress response and alleviate lung injury in mice.

Identification of Genes with Altered Methylation and Its Role in Early Diagnosis of Sepsis-Induced Acute Respiratory Distress Syndrome

Purpose

Early diagnosis of sepsis-induced acute respiratory distress syndrome (ARDS) is critical for effective treatment. We aimed to identify early stage biomarkers.

Materials and Methods

Differentially expressed genes were identified in whole blood samples from patients with sepsis or ARDS based on the Gene Expression Omnibus (GEO) datasets GSE32707, GSE54514 and GSE10361. Functional enrichment analysis explored the biological characteristics of differentially expressed genes. Genes with high functional connectivity based on a protein-protein interaction network were marked as hub genes, which were validated using the GEO dataset GSE76293, and a gene set variation analysis index (GSVA) was assigned. Diagnostic and predictive ability of the hub genes were assessed by receiver operating characteristic (ROC) curve analysis. DNA methylation levels of hub genes were quantified using the GEO dataset GSE67530.

Results

Forty-one differentially expressed genes were shared between sepsis-specific and ARDS-specific datasets. MAP2K2 and IRF7 functional activity was highly connected in sepsis-induced ARDS. Hub genes included RETN, MVP, DEFA4, CTSG, AZU1, FMNL1, RBBP7, POLD4, RIN3, IRF7. ROC curve analysis of the hub gene GSVA index showed good diagnostic ability in sepsis or ARDS. Among genes related to sepsis-induced ARDS, 17 were differentially methylated. Principal component analysis and heatmaps indicated that gene methylation patterns differed significantly between ARDS patients and controls.

Conclusion

We identified a genetic profile specific to early-stage sepsis-induced ARDS. The abnormal expression of these genes may be caused by hypomethylation, which may serve as a biomarker for early diagnosis of ARDS.

Mitophagy-Mediated mtDNA Release Aggravates Stretching-Induced Inflammation and Lung Epithelial Cell Injury via the TLR9/MyD88/NF-κB Pathway

Background

In animal models of ventilation-induced lung injury, mitophagy triggers mitochondria damage and the release of mitochondrial (mt) DNA, which activates inflammation. However, the mechanism of this process is unclear.

Methods

A model of cyclic stretching (CS)-induced lung epithelial cell injury was established. The genetic intervention of phosphatase and tensin homolog-induced kinase 1 (PINK1) expression via lentivirus transfection was used to identify the relationship between PINK1-mediated mitophagy and mtDNA release in stretching-induced inflammatory response and injury. Pharmacological inhabitation of Toll-like receptor 9 (TLR9) and myeloid differentiation factor 88 (MyD88) expression was performed via their related inhibitors, while pre-treatment of exogenous mtDNA was used to verify the role of mtDNA in stretching-induced inflammatory response and injury.

Results

Using a cell culture model of CS, we found that knocking down PINK1 in lung epithelial cells reduced mitophagy activation and mtDNA release, leading to milder inflammatory response and injury; conversely, up-regulating PINK1 exacerbated stretching-induced inflammation and injury, and similar effects were observed by upregulating TLR9 to induce expression of MyD88 and nuclear factor-κB (NF-κB)/p65. Down-regulating MyD88 protected lung epithelial cells from stretching injury and decreased NF-κB/p65 expression.

Conclusion

These findings suggest that PINK1-dependent mitophagy and associated TLR9 activation is indeed a major factor in stretch-induced cell injury via a mechanism in which released mtDNA activates TLR9 and thereby the MyD88/NF-κB pathway. Inhibiting this process may be a therapeutic approach to prevent inflammation and cell injury in patients on mechanical ventilation.

Tryptophan decreases the intensity of lipopolysaccharide-induced acute lung injury in a rat model

Sepsis is a severe clinical condition that is a result of the cellular and biochemical response to infection. The present study evaluated the therapeutic potential of tryptophan against lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats. Rats were grouped into sham, control (ALI), and ALI + 1, 25, and 50 mg/kg body weight L-tryptophan. Supplementation with 1, 25, and 50 mg/kg L-tryptophan reduced the total protein content by 4.9%, 33.4%, and 64.5%; the levels of neutrophils (12.5%, 31.8%, and 65.1%), lymphocytes (15.1%, 41.7%, and 63.3%), total cells (12.6%, 42.4%, and 65.7%); lipid peroxidation (9.4%, 28.4%, and 68.7%); myeloperoxidase levels (12.1%, 33.4%, and 68.2%); migration inhibitory factor (12.7%, 39.5%, and 68.2%), interleukin (IL)-8 (5.5%, 46.8%, and 78.5%), tumor necrosis factor (TNF)-α (10.8%, 39.8%, and 72.2%), respectively. Supplementation with 1, 25, and 50 mg/kg L-tryptophan reduced mRNA expression of TNF-α (4.5%, 21.8%, and 41.8%), IL-1β (5.2%, 17.9%, and 46.2%); and the protein expression of TNF-α (2.8%, 15.2%, and 35.7%) and IL-1β (5.2%, 15.6%, and 28.6%), respectively. It also reduced glutathione (to near normal levels), neutrophilic infiltration and edema, and the wet/dry ratio of lung tissue. It significantly increased catalase, superoxide dismutase, glutathione peroxidase levels, as well as the partial pressure of oxygen (PaO₂) by 21.9%, 52.8%, and 87.4%, respectively. Altogether, our results suggest that supplementation with L-tryptophan has a strong protective effect against LPS-induced ALI.

miR-143-3p impacts on pulmonary inflammatory factors and cell apoptosis in mice with mycoplasmal pneumonia by regulating TLR4/MyD88/NF-κB pathway

miR-143-3p is correlated with inflammatory pain responses, such as hsa-miR-143-3p expression reduction in fibromyalgia. The present study aimed to explore the effects of miR-143-3p and Toll-like receptor (TLR) 4/myeloid differentiation factor 88 (MyD88)/NF-κB signaling pathway on pulmonary inflammatory factors levels and alveolar epithelial cell apoptosis in mycoplasmal pneumonia mice. Twenty mice were selected as normal group. The 120 successfully modeled Mycoplasma pneumoniae (MP) infection mice were randomly divided into model group (without any treatment), negative control (NC) group (injected with NC mimic), miR-143-3p mimic group (injected with miR-143-3p mimic), miR-143-3p inhibitor group (injected with miR-143-3p inhibitor), TAK-242 group (treatment with TAK-242), and miR-143-3p inhibitor + TAK-242 group (treatment with miR-143-3p inhibitor + TAK-242). Compared with model group, model mice had up-regulated miR-143-3p expression and decreased MyD88 and p-NF-κB p50 protein expressions (all P<0.05); Model mice treated with miR-143-3p mimic and TAK-242 had reduced interleukin (IL)-2 and tumor necrosis factor (TNF)-α contents and protein expressions of MyD88, p-NF-κB p50, increased IL-10 content, fewer alveolar epithelial cell apoptosis, lower Bax expression and higher Bcl-2 expression (all P<0.05); however, mice with miR-143-3p inhibitor treatment showed opposite trends in terms of above indicators. The exacerbation of mycoplasmal pneumonia caused by miR-143-3p inhibitor was partly improved by miR-143-3p inhibitor + TAK-242 combination treatment (all P<0.05). Therefore, up-regulation of miR-143-3p expression may ameliorate pulmonary inflammatory factors levels and reduce alveolar epithelial cell apoptosis in mycoplasmal pneumonia mice by inhibiting TLR4/MyD88/NF-κB signaling pathway.

Ly-6Chigh inflammatory-monocyte recruitment is regulated by p38 MAPK/MCP-1 activation and promotes ventilator-induced lung injury

Lymphocyte antigen 6Chigh (Ly-6C^high) inflammatory monocytes, as novel mononuclear cells in the innate immune system, participate in infectious diseases. In this study, we investigated the potential role of these monocytes in ventilator-induced lung injury (VILI) and the possible mechanism involved in their migration to lung tissue. Our results showed that mechanical ventilation with high tidal volume (HTV) increased the accumulation of Ly-6C^high inflammatory monocytes in lung tissues and that blocking C‑C chemokine receptor 2 (CCR2) could significantly reduce Ly-6C^high inflammatory-monocyte migration and attenuate the degree of inflammation of lung tissues. In addition, inhibition of p38 mitogen-activated protein kinase (p38 MAPK) activity could decrease the secretion of monocyte chemoattractant protein 1 (MCP-1), which in turn decreased the migration of Ly-6C^high inflammatory monocytes into lung tissue. We also demonstrated that high ventilation caused Ly-6C^high inflammatory monocytes in the bone marrow to migrate into and aggregate in the lungs, creating inflammation, and that the mechanism was quite different from that of infectious diseases. Ly-6C^high inflammatory monocytes might play a pro-inflammatory role in VILI, and blocking their infiltration into lung tissue might become a new target for the treatment of this injury.

Effect of bovine lactoferrin as a novel therapeutic agent in a rat model of sepsis-induced acute lung injury

Sepsis is a serious clinical condition resulting from severe infection. High rates of mortality and tissue damage have been reported in intensive care unit (ICU) patients with sepsis. Bovine lactoferrin (BLF) is a well-known 80-kDa glycoprotein in the transferrin family that inhibits sepsis in low-birth-weight neonates. The present study investigated the protective effects of BLF in a rat model of sepsis-induced acute lung injury (ALI). The wet/dry ratio, lipid peroxidation, antioxidant markers, total protein, total cell count, inflammatory markers and myeloperoxidase (MPO) levels were assessed. Histopathological analysis was also carried out. BLF treatment reduced the wet/dry ratio of lung tissue by 30.7% and 61.3%, and lipid peroxidation by 22.3% and 67%, at concentrations of 100 and 200 mg/kg, respectively. Superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (Gpx) and catalase were increased by more than 50% under treatment with 200 mg/kg BLF. Inflammatory markers, neutrophils, lymphocytes and total cell count were reduced by more than 50% under treatment with 200 mg/kg BLF. BLF treatment significantly reduced MPO activity, by 28.2% and 74.3%, at concentrations of 100 and 200 mg/kg, respectively. Neutrophilic infiltration and edema were observed in control rats. However, BLF treatment restored intestinal microvilli to the normal range and reduced inflammatory cell invasion. Collectively, these results suggest that BLF is an effective therapeutic agent against sepsis-induced ALI.

[Mechanism of ulinastatin in reducing lung inflammatory injury in rats with hemorrhagic shock]

OBJECTIVE

To investigate the effect of ulinastatin on the inflammatory mediators and their signaling pathways miR-146a/TLR4/NF-κB in rats with hemorrhagic shock.

METHODS

Seventy-two SD rats were randomly assigned into shock without resuscitation group (SR group, n=24), acetated Ringer's solution resuscitation group (AR group, n=24) and ulinastatin treatment group (n=24). In all the 3 groups hemorrhagic shock models were established by femoral artery bleeding (with the mean arterial pressure maintained at 30-40 mmHg) without resuscitation (in SR group) or with resuscitation (in AR and ulinastatin groups) using acetated Ringer's solution for 30 min at 60 min after the onset of shock. At 1, 4, and 6 h after the shock onset or immediately after shock if the rats died, the lung tissues were taken for measurement of mRNA expressions of miR-146a, tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), IL-4, IL-6 and IL-10 using real-time quantitative PCR and the protein expressions of TLR4, MyD88, IκB-α, p-IκB-α, NF-κB p65, IRAK4, p-IRAK4 (Thr345, Ser346), p-IRAK4 (Thr342) and TRAF6 using Western blotting. The lung histopathology of the rats was examined under optical microscope with HE staining.

RESULTS

Compared with the SR group, the rats in the AR group showed slightly alleviated inflammatory infiltration in the lung tissues with significantly increased mRNA levels of miR-146a, IL-4 and IL-10 (P < 0.05) and protein expressions of IκB-α, p-IRAK4 (Thr342) and p-IRAK4 (Thr345, ser346) (P < 0.05), and decreased mRNA levels of TNF-α, IL-1 and IL-6 (P < 0.05) and protein expressions of TLR4, MyD88, NF-κB p65, p-IκB-α, IRAK-4 and TRAF6 (P < 0.05). Compared with those in AR group, the rats in ulinastatin group showed further alleviation of inflammatory lung tissue injury, with increased mRNA levels of miR-146a, IL-4 and IL-10 (P < 0.01) and protein expressions of IκB-α, p-IRAK4 and p-IRAK4 (P < 0.01) and decreased mRNA levels of TNF-α, IL-1 and IL-6 (P < 0.01) and protein expressions of TLR4, MyD88, NF-κB p65, p-IκB-α, IRAK-4 and TRAF6 (P < 0.01).

CONCLUSIONS

Ulinastatin combined with acetated Ringer's solution resuscitation alleviates lung inflammations in rats with hemorrhagic shock possibly by enhancing miR-146a expression to regulate TLR4/NF-κB signaling pathway through a negative feedback mechanism and thus modulate the balance of pro-inflammatory and anti-inflammatory factors.

Ulinastatin Protects Against LPS-Induced Acute Lung Injury By Attenuating TLR4/NF-κB Pathway Activation and Reducing Inflammatory Mediators

Acute lung injury (ALI) and its severe form, acute respiratory distress syndrome, remain the leading causes of morbidity and mortality in intensive care units. Ulinastatin (UTI), a serine protease inhibitor, possesses anti-inflammatory properties and has been suggested to modulate lipopolysaccharide (LPS)-induced sepsis; thus, it is now widely used in the treatment of pancreatitis, sepsis, and septic shock. Toll-like receptor 4 (TLR4), an essential LPS signaling receptor, plays a critical role in the activation of innate immunity. The aim of this study was to investigate whether UTI alleviates ALI by attenuating TLR4 expression and to explore the underlying molecular mechanisms involved. Male C56BL/6 mice were administered UTI intravenously 1 h before and 6 h after exposure to LPS by intratracheal instillation. Human lung epithelial (BEAS-2B) cells were incubated with LPS in the presence or absence of UTI. An enzyme-linked immunosorbent assay was used to detect levels of inflammatory cytokines. Western blot analysis was performed to detect changes in TLR4 expression and nuclear factor-κB (NF-κB) activation. UTI significantly protected animals from LPS-induced ALI, decreasing the lung wet/dry weight ratio, ALI score, total cells, neutrophils, macrophages, myeloperoxidase activity, and malondialdehyde content, factors associated with lung histological damage. UTI treatment also markedly attenuated levels of TLR4 and other proinflammatory cytokines. Furthermore, UTI significantly attenuated LPS-induced increases in TLR4 protein expression and NF-κB activation in lung tissues. Similarly, UTI markedly attenuated TLR4 expression and NF-κB activation in LPS-stimulated BEAS-2B cells. These findings indicate that UTI ameliorates LPS-induced ALI by attenuating the TLR4/NF-κB pathway activation.

Biologically active 1,25-dihydroxyvitamin D3 protects against experimental sepsis by negatively regulating the Toll-like receptor 4/myeloid differentiation primary response gene 88/Toll-IL-1 resistance-domain-containing adapter-inducing interferon-β signaling pathway

The hormonally active form of vitamin D (VD), 1,25‑dihydroxyvitamin D3, has been reported to be a key immunoregulator in the reduction of inflammation. In this study, we investigated the effects of VD in an experimental sepsis cell model, and the underlying mechanisms. The sepsis cell model was first established in monocytes, isolated from newborns and healthy adults, which were stimulation with lipopolysaccharide (LPS). We observed that cell viability was significantly impaired in the monocytes after LPS stimulation, using a Cell Counting Kit‑8 and trypan blue assays. Additionally, ELISA revealed that LPS stimulation significantly elevated the expression of interleukin 6 (IL‑6), IL‑10 and tumor necrosis factor‑α (TNF‑α). The expression levels of Toll‑like receptor (TLR4), myeloid differentiation primary response gene 88 (MyD88), and Toll‑IL‑1 resistance‑domain‑containing adapter‑inducing interferon‑β (TRIF) mRNA were also significantly elevated under LPS stimulation using reverse transcription‑quantitative PCR and western blot analysis. VD treatment could significantly suppress the effects of LPS simulation on monocytes by negatively regulating inflammatory cytokines and TLR4/MyD88/TRIF signaling. Furthermore, a regulatory feedback mechanism was proposed to involve TLR4, MyD88 and TRIF in the sepsis cell model. In conclusion, VD may effectively decrease the release of inflammatory cytokines by inhibiting the TLR4/MyD88/TRIF signaling pathway, could be considered as a potential therapeutic agent for the treatment of sepsis.

Targeting Notch-activated M1 macrophages attenuate lung tissue damage in a rat model of ventilator induced lung injury

Ventilator induced lung injury (VILI) may be involved in the activation of alveolar macrophages. The purpose of this study was to investigate the relationship between the Notch signaling pathway and macrophage polarization in VILI. The VILI model was established using rats. Hematoxylineosin staining was used to test the lung tissue morphology. Bicinchoninic acid assay and ELISA were performed to detect protein and tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-10 levels in bronchoalveolar lavage fluids (BALF), respectively. The ratio of alveolar M1 and M2 macrophages was detected by flow cytometry. The mRNA and protein expression levels of Notch pathway-related proteins were determined using reverse transcription-quantitative PCR and western blotting. The present study found that high-frequency mechanical ventilation could cause pulmonary edema and increase the levels of protein, TNF-α and IL-6 in BALF while decreasing the level of IL-10 in BALF. High-frequency mechanical ventilation also induced polarization of alveolar macrophages to M1. The results also showed a significant increase in the levels of Notch pathway-related proteins including notch intracellular domain, Hes1, Hes5 and Hey1. Injection of N-[N-(3,5-difluorophenylacetyl)-1-alanyl] phenylglycine t-butyl ester could inhibit the Notch pathway and such an inhibition protected lung tissue and reduced lung inflammation caused by mechanical ventilation. After the Notch pathway was inhibited, the level of M1 polarization of macrophages caused by high-frequency mechanical ventilation was reduced. VILI caused pulmonary inflammation and macrophages to polarize to M1 and upregulated the expression levels of Notch pathway-related proteins. The inhibition of Notch pathway also reduced the proportion of M1 macrophages and inflammatory responses.

Activation of Nrf2 signaling by Icariin protects against 6-OHDA-induced neurotoxicity

Nerve damage is the main pathogenesis of neurodegenerative diseases. Recently, in search for a promising therapeutic target that could stop neurodegenerative diseases progression, the antioxidant signaling pathway regulated by transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) has attracted new hopes. Icariin (ICA) exhibited a battery of pharmacological properties, including antioxidation, anti-aging, and anti-inflammation activities. Recent studies indicate ICA conferred neuroprotection against brain ischemic injury and neurodegenerative diseases. However, the mechanisms underlying ICA-mediated neuroprotection remain unelucidated. This study aimed at analyzing whether ICA evoked neuroprotection against 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in PC12 cells and the mechanisms of action. ICA protected against 6-OHDA-induced neuronal damage, accompanied by the inhibition of cell apoptosis through the marked decreases in the Bax/Bcl-2 ratio, cytochrome c release, and caspase-3 cleavage. In addition, the activation of Nrf2 signaling pathway was responsible for ICA-mediated neuroprotection. First, ICA relieved reactive oxygen species accumulation and increased superoxide dismutase generation via the activation of Nrf2 signaling. Second, Nrf2 knockdown by siRNA reversed ICA-mediated neuroprotection. Together, these results suggested ICA-mediated neuroprotection might be attributable to the activation of Nrf2 pathway via antioxidative signaling pathways.

High Tidal Volume Induces Mitochondria Damage and Releases Mitochondrial DNA to Aggravate the Ventilator-Induced Lung Injury

Objective

This study aimed to determine whether high tidal volume (HTV) induce mitochondria damage and mitophagy, contributing to the release of mitochondrial DNA (mtDNA). Another aim of the present study was to investigate the role and mechanism of mtDNA in ventilator-induced lung injury (VILI) in rats.

Methods

Rats were tracheotomized and allowed to breathe spontaneously or mechanically ventilated for 4 h. After that, lung injury was assessed. Inhibition of toll-like receptor 9 (TLR9), named ODN2088, was used to determine the involvement of TLR9/myeloid differentiation factor 88 (MyD88)/nuclear factor-κB (NF-κB) signaling pathway in VILI. The mitochondrial damage and release of mtDNA were assessed. Pharmacological inhibition of mtDNA (chloroquine) was used to determine whether mtDNA trigger inflammation via TLR9 in VILI. EDU-labeled mtDNA deriving from mitophagy was assessed by immunofluorescence. The role of mitophagy in VILI was shown by administration of antimycin A and cyclosporine A.

Main results

Rats subjected to HTV showed more severe pulmonary edema and inflammation than the other rats. The decreased expression of TLR9, MyD88, and NF-κB were observed following the use of ODN2088. Mechanical ventilation (MV) with HTV damaged mitochondria which resulted in dysfunctional ATP synthesis, accumulation of reactive oxygen species, and loss of mitochondrial membrane potential. Moreover, the results of distribution of fluorescence in rats upon HTV stimulation indicated that mtDNA cleavage was associated with mitophagy. The expression levels of mitophagy related genes (LC3B-II/LC3B-I, PINK1, Parkin, and mitofusin 1) in animals ventilated with HTV were significantly upregulated. Administration of antimycin A aggregated the histological changes and inflammation after MV, but these effects were attenuated when administered in the presence of cyclosporine A.

Conclusion

MV with HTV induces mitochondrial damage and mitophagy, contributing to the release of mtDNA, which may be induced VILI in rat via TLR9/MyD88/NF-κB signaling pathway.

The triggering receptor expressed by myeloid cells-1 activates TLR4-MyD88-NF-κB-dependent signaling to aggravate ventilation-induced lung inflammation and injury in mice

The triggering receptor expressed by myeloid cells-1 (TREM-1) plays an important role in infectious and autoimmune diseases but how it contributes to ventilation-induced lung injury (VILI) and inflammation is unclear. Here, we examine the possibility that TREM-1 activates signaling dependent on Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (Myd88) and nuclear factor (NF)-κB, which leads in turn to VILI. In a mouse model of VILI, which we validated based on lung edema and histopathology as well as cytokine levels, we examine mRNA and protein levels of TREM-1, TLR4, MyD88, NF-κB and its inhibitory protein I-κB in animals subjected to ventilation at normal or high tidal volume. The extent of lung edema, injury and inflammation were higher in the high tidal volume animals, as were the expression levels of all proteins examined. Treatment with TREM-1 agonist aggravated these effects, whereas treatment with TREM-1 antagonist attenuated them. Our results suggest that aggravation of VILI by TREM-1 in mice may be associated with TLR4-MyD88-NF-κB-dependent signaling.

Transduced PEP-1-Heme Oxygenase-1 Fusion Protein Attenuates Lung Injury in Septic Shock Rats

Oxidative stress and inflammation have been identified to play a vital role in the pathogenesis of lung injury induced by septic shock. Heme oxygenase-1 (HO-1), an effective antioxidant and anti-inflammatory and antiapoptotic substance, has been used for the treatment of heart, lung, and liver diseases. Thus, we postulated that administration of exogenous HO-1 protein transduced by cell-penetrating peptide PEP-1 has a protective role against septic shock-induced lung injury. Septic shock produced by cecal ligation and puncture caused severe lung damage, manifested in the increase in the lung wet/dry ratio, oxidative stress, inflammation, and apoptosis. However, these changes were reversed by treatment with the PEP-1-HO-1 fusion protein, whereas lung injury in septic shock rats was alleviated. Furthermore, the septic shock upregulated the expression of Toll-like receptor 4 (TLR4) and transcription factor NF-κB, accompanied by the increase of lung injury. Administration of PEP-1-HO-1 fusion protein reversed septic shock-induced lung injury by downregulating the expression of TLR4 and NF-κB. Our study indicates that treatment with HO-1 protein transduced by PEP-1 confers protection against septic shock-induced lung injury by its antioxidant, anti-inflammatory, and antiapoptotic effects.

Tenascin‑C promotes the migration of bone marrow stem cells via toll‑like receptor 4‑mediated signaling pathways: MAPK, AKT and Wnt

There are currently limitations in stem cell therapy due to the low rate of homing and proliferation of cells following transplantation. The present study was designed to investigate the effects of Tenascin-C (TN-C) on bone marrow mesenchymal stem cells (BMSCs) and its underlying mechanisms. BMSCs were obtained from C57BL/6 mice. The survival and proliferation of BMSCs was analyzed by Cell Counting Kit-8 assay, migration was evaluated using the Transwell method, and differentiation was assessed by immunocytochemistry and immunofluorescence. In addition, the levels of proteins were detected by western blotting. High concentrations of TN-C promoted the migration of BMSCs. H₂O₂ at concentrations of 60–90 µmol/ml induced cell death in BMSCs, and thus, it was used to simulate oxidative stress in the microenvironment of acute myocardial infarction (AMI). High concentrations of TN-C were able to protect BMSCs from cell death, and promoted the migration of BMSCs (P<0.05). However, TAK-242 [the inhibitor of Toll-like receptor 4, (TLR4)] reduced the promoting effect of TN-C (P<0.05). By contrast, TN-C had no effect on the proliferation and differentiation of BMSCs. TN-C reduced the phosphorylation levels of p38 mitogen-activated protein kinase (MAPK), and increased the phosphorylation levels of Ser473 protein kinase B (AKT) and β-catenin, all of which were inhibited by TAK-242 (P<0.05). In the simulated AMI microenvironment, TN-C promoted the migration of BMSCs via TLR4-mediated signaling pathways, including MAPK, AKT and Wnt.

Effect of TLR4/MyD88 signaling pathway on sepsis-associated acute respiratory distress syndrome in rats, via regulation of macrophage activation and inflammatory response

The present study aimed to investigate the effects of the Toll-like receptor (TLR)4/myeloid differentiation primary response (MyD)88 signaling pathway on sepsis-associated acute respiratory distress syndrome (ARDS) in rats, and the involvement of macrophage activation and the inflammatory response. A total of 36 specific pathogen-free male Sprague-Dawley rats were selected to establish the rat model of sepsis-associated ARDS using cecal ligation and puncture (CLP). Rats were assigned into the Ab (anti-TLR4 monoclonal antibody)-CLP, CLP and Sham groups. Arterial partial pressure of oxygen (P_aO₂) was detected using blood gas analysis. Bronchoalveolar lavage fluid (BALF) and alveolar macrophages were collected. The pathological structure of lung tissue was observed following hematoxylin-eosin staining. The ultrastructural alterations of alveolar epithelial cells were observed under transmission electron microscope. The ratios of wet/dry weight of lung tissue and total protein content in BALF were measured. The concentration of tumor necrosis factor (TNF)-α and interleukin (IL)-1β in BALF and peripheral blood was determined by enzyme-linked immunosorbent assay. The TLR4, TLR9, MyD88 and nuclear factor (NF)-κΒ mRNA and protein expression levels in alveolar macrophages were measured by reverse transcription-quantitative polymerase chain reaction and western blotting. Compared with the Sham group, the rats in the CLP group demonstrated significantly increased respiratory frequency, lung permeability, lung edema, inflammatory infiltration, TNF-α and IL-1β expression levels in BALF and peripheral blood and TLR4, TLR9, MyD88 and NF-κΒ expression levels in macrophages, however decreased arterial P_aO₂. Following pretreatment with anti-TLR4 monoclonal antibody, rats exhibited decreased lung injury, inflammatory infiltration, lung edema, TNF-α and IL-1β expressions in BALF and peripheral blood, and TLR4, TLR9, MyD88 and NF-κΒ expression levels in macrophages, with increased arterial P_aO₂. These results suggested that the inhibition of TLR4/MyD88 signaling pathway may relieve sepsis-associated ARDS in rats through regulating macrophage activation and the inflammatory response.

Glycyrrhizin Ameliorate Ischemia Reperfusion Lung Injury through Downregulate TLR2 Signaling Cascade in Alveolar Macrophages

This experiment was conducted to study whether pretreatment with Glycyrrhizin (GL) could ameliorate ischemia-reperfusion (I/R) lung injury and investigate the mechanisms of its protective effects in a mice model. Six-eight weeks male BALB/C mice were randomly assigned to four groups (n = 6): Control, Glycyrrhizin, I/R and I/R+Glycyrrhizin. Lung I/R was achieved by clamping the left hilus pulmonis. GL (200 mg/kg) was injected intraperitoneally 30 min before anesthesia. Measurement of pathohistological lung injury score, pulmonary permeability, isolated alveolar macrophages, inflammatory mediators, TLR2 and its downstream factors (MyD88, NF-κB) were performed. The results were as anticipated. Pathohistological evaluation indicated that GL significantly ameliorated I/R-induced lung injury, pulmonary permeability and edema. Pretreatment with GL significantly inhibited I/R-induced inflammation in lung tissues and BALF. In addition, GL significantly decreased I/R-induced isolated alveolar macrophages and suppressed I/R-induced expression of TLR2 and its downstream factors in lung tissues and alveolar macrophages. Collectively, our data indicated that pretreatment with GL could ameliorate I/R lung injury. The mechanisms of its protective effects might be inhibit I/R-induced inflammatory response through downregulate TLR2 signaling cascade in alveolar macrophages.