Low concentration of oleic acid exacerbates LPS-induced cell death and inflammation in human alveolar epithelial cells

USP9X promotes lipopolysaccharide-stimulated acute lung injury by deubiquitination of NLRP3

Alveolar epithelial cells (AECs) function as a vital defense barrier avoiding the invasion of exogenous agents and preserving the functional and structural integrity of lung tissues, while damage/breakdown of this airway epithelial barrier is frequently associated with the pathogenesis of acute lung injury (ALI). NOD-like receptor family, pyrindomain-containing 3 (NLRP3) inflammasome activation-associated pyroptosis is involved in the development of ALI. Yet, how the activity of NLRP3 inflammasome is regulated in the context of ALI remains unknown. Herein we hypothesized that USP9X, an important deubiquitinase, participates in modulating the activation of NLRP3 inflammasome, thereby affecting the phenotypes in a lipopolysaccharide (LPS)-stimulated AEC model. Human pulmonary AECs were subjected to LPS/adenosine triphosphate (ATP) treatment to induce NLRP3 inflammasome activation and cell pyroptosis. Knockdown and overexpression of USP9X were applied to validate the function of USP9X. Inhibitors of proteinase and protein synthesis, as well as approach of co-immunoprecipitation coupled with Western blot, were utilized to explore the molecular mechanism. LPS/ATP challenge resulted in pronouncedly increased pyroptosis of AECs, activation of NLRP3 inflammasome and release of interleukin (IL)-1β and IL-18 cytokines, while downregulation of USP9X could reverse these alterations. USP9X was found to have marked impact on NLRP3 protein instead of mRNA level. Furthermore, increased ubiquitination of NLRP3 was observed upon downregulating USP9X. Additionally, the inhibitory effect of USP9X downregulation was reversed by NLRP3 overexpression, while the promoting impact of USP9X overexpression was dampened by NLRP3 inhibitor in terms of cell pyroptosis and cytokine secretion. USP9X modulated the activity of NLRP3 inflammasome and pyroptosis of AECs via its deubiquitination function.

Effect of Thiazolidin-4-one Against Lipopolysaccharide-Induced Oxidative Damage, and Alterations in Adenine Nucleotide Hydrolysis and Acetylcholinesterase Activity in Cultured Astrocytes

Astrocytes play multiple important roles in brain physiology. However, depending on the stimuli, astrocytes may exacerbate inflammatory reactions, contributing to the development and progression of neurological diseases. Therefore, therapies targeting astrocytes represent a promising area for the development of new brain drugs. Thiazolidinones are heterocyclic compounds that have a sulfur and nitrogen atom and a carbonyl group in the ring and represent a class of compounds of great scientific interest due to their pharmacological properties. The aim of this study was to investigate the effect of 3-(3-(diethylamino)propyl)-2-(4-(methylthio)phenyl)thiazolidin-4-one (DS27) on cell proliferation and morphology, oxidative stress parameters, activity of the enzymes ectonucleotidases and acetylcholinesterase (AChE) and interleukin 6 (IL-6) levels in primary astrocyte cultures treated with lipopolysaccharide (LPS), to model neuroinflammation. The astrocyte culture was exposed to LPS (10 μg/ml) for 3 h and subsequently treated with compound DS27 for 24 and 48 h (concentrations ranging to 10-100 μM). LPS induced an increase in astrocyte proliferation, AChE activity, IL-6 levels, oxidative damage, ATP and ADP and a reduction in AMP hydrolysis in rat primary astrocyte cultures. DS27 treatment was effective in reversing these alterations induced by LPS. Our findings demonstrated that DS27 is able to modulate cholinergic and purinergic signaling, redox status, and the levels of pro-inflammatory cytokines in LPS-induced astrocyte damage. These glioprotective effects of DS27 may be very important for improving neuroinflammation, which is associated with many brain diseases.

Clinical significance of lipid droplets formed in the peritoneal fluid after laparoscopic surgery for gastric cancer

BACKGROUND

Several studies have previously reported that laparoscopic surgery using an energy sealing device generates hazardous surgical smoke. However, the droplets appearing on the surface of peritoneal fluid irrigated with saline, after dissection phase of laparoscopic gastrectomy were ignored for a long time. This study aimed to investigate the composition and clinical significance of these droplet particles.

METHODS

This study prospectively enrolled 15 patients with early gastric cancer (cT1NanyM0) who were scheduled for laparoscopic gastrectomy. Floating phases of peritoneal irrigation fluid containing droplets in dissected area were retrieved before and after surgical dissection. Using gas chromatography analysis, the areas under the peak were compared between the samples retrieved before and after surgical dissection. We also analyzed if the area value with significant change was related to the inflammatory response.

RESULTS

In gas chromatography, the area values after laparoscopic surgical dissection were significantly increased in 10 out of 37 kinds of fatty acids, compared to those before surgical dissection. The significant increase in area value of α-linoleic and eicosadienoic acids were positively correlated with the elevated level of C-reactive protein at postoperative day 2 (Spearman's ρ = 0.843, P < 0.001; Spearman's ρ = 0.785, P = 0.001).

CONCLUSIONS

The lipid droplets, generated after laparoscopic lymphadenectomy during gastric cancer surgery, contained various types of fatty acids, and some of them have been found to be associated with inflammatory response.

Pseudomonas aeruginosa in bronchiectasis: infection, inflammation, and therapies

Introduction: Bronchiectasis is a chronic endobronchial suppurative disease characterized by irreversibly dilated bronchi damaged by repeated polymicrobial infections and predominantly, neutrophilic airway inflammation. Some consider bronchiectasis a syndromic consequence of several different causes whilst others view it as an individual disease entity. In most patients, identifying an underlying cause remains challenging. The acquisition and colonization of affected airways by Pseudomonas aeruginosa represent a critical and adverse clinical consequence for its progression and management.Areas covered: In this review, we outline clinical and pre-clinical peer-reviewed research published in the last 5 years, focusing on the pathogenesis of bronchiectasis and the role of P. aeruginosa and its virulence in shaping host inflammatory and immune responses in the airway. We further detail its role in airway infection, the lung microbiome, and address therapeutic options in bronchiectasis.Expert opinion: P. aeruginosa represents a key pulmonary pathogen in bronchiectasis that causes acute and/or chronic airway infection. Eradication can prevent adverse clinical consequence and/or disease progression. Novel therapeutic strategies are emerging and include combination-based approaches. Addressing airway infection caused by P. aeruginosa in bronchiectasis is necessary to prevent airway damage, loss of lung function and exacerbations, all of which contribute to adverse clinical outcome.

Multi-omics reveals the mechanisms of antidepressant-like effects of the low polarity fraction of Bupleuri Radix

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Bupleuri (Bupleurum chinense DC.) is a traditional Chinese medicine that has the effect of soothing the liver and relieving depression, and widely used in the field of antidepression.

AIM OF THE STUDY

The low polarity fraction of Bupleuri Radix (PBR) has proved to be effective for the treatment of depression based on the results of our previous study. However, mechanisms of definite antidepressant-like effects remained unclear. The purpose of this study is to reveal mechanisms of antidepressant-like effects of PBR with multi-dimensional omics.

MATERIALS AND METHODS

LC-MS metabolomics combined with 16S rRNA gene sequencing were used to investigate the effects of PBR on gut microbiota and metabolites in CUMS-induced depression, and Pearson correlation analysis was carried out on gut microbiota and metabolites.

RESULTS

PBR significantly improved depression-like behaviors in the CUMS model rats. Moreover, PBR significantly increased the levels of BDNF in the hippocampus. Cecum contents metabolomics revealed that 16 biomarkers associated with PBR antidepressant effect were screened, which were involved 3 metabolic pathways including primary bile acid biosynthesis, taurine and hypotaurine metabolism, glyoxylate and dicarboxylate metabolism. Gut microbiota further analysis demonstrated that PBR increased the diversity of gut microbiota, and significantly inhibited the growth of [Prevotella] and Ochrobactrum. Furthermore, Pearson analysis revealed there was a strong correlation between cecum contents of metabolites and gut microbiota.

CONCLUSIONS

PBR improved depression-like behavior by regulating metabolic profiles and gut microbiota, and contributing to further understand the entailed antidepressant-like mechanisms of PBR.

Short-Term versus Long-Term Culture of A549 Cells for Evaluating the Effects of Lipopolysaccharide on Oxidative Stress, Surfactant Proteins and Cathelicidin LL-37

Alveolar epithelial type II (ATII) cells and their proper function are essential for maintaining lung integrity and homeostasis. However, they can be damaged by lipopolysaccharide (LPS) during Gram-negative bacterial infection. Thus, this study evaluated and compared the effects of LPS on short and long-term cultures of A549 cells by determining the cell viability, levels of oxidative stress and antimicrobial peptide cathelicidin LL-37 and changes in the expression of surfactant proteins (SPs). Moreover, we compared A549 cell response to LPS in the presence of different serum concentrations. Additionally, the effect of N-acetylcysteine (NAC) on LPS-induced oxidative stress as a possible treatment was determined. Our results indicate that A549 cells are relatively resistant to LPS and able to maintain integrity even at high LPS concentrations. Their response to endotoxin is partially dependent on serum concentration. NAC failed to lower LPS-induced oxidative stress in A549 cells. Finally, LPS modulates SP gene expression in A549 cells in a time dependent manner and differences between short and long-term cultures were present. Our results support the idea that long-term cultivation of A549 cells could promote a more ATII-like phenotype and thus could be a more suitable model for ATII cells, especially for in vitro studies dealing with surfactant production.

Camellia japonica oil suppressed asthma occurrence via GATA-3 & IL-4 pathway and its effective and major component is oleic acid

BACKGROUND

In December 2016, WHO released a report stating that in 2015 there were 383,000 deaths caused by asthma and 235 million people suffering from asthma. As there are many adverse effects associated with the currently-used asthma drugs, new anti-asthmatic drugs need to be developed.

PURPOSE

In order to find new drug candidates with safe and low side effects, the anti-asthmatic function and mechanism of C. japonica oil were evaluated, and its active ingredients were analyzed for use in an ovalbumin asthma murine model.

STUDY DESIGN AND METHODS

The study consisted of six groups: control; ovalbumin group; and dexamethasone group as a positive control; and 10, 100, and 500 mg/kg C. japonica oil treatment groups. In order to measure the anti-asthmatic effect of C. japonica oil, WBC and differential cell count in BALF, IgE in serum, morphological changes in pulmonary system, and gene and protein levels such as IFN-γ, IL-12p40, IL-4, IL-5, IL-6, TNF-α, and IL-6 were all evaluated.

RESULTS

C. japonica oil had an anti-asthmatic effect and significantly controlled eosinophil in BALF, Th2-related factors such as GATA-3 that is Th2 cell transcription factor, IL-4, IL-5, and IL-13, and TNF-α in the lung. It also dose-dependently modulated inflammatory cells, T-bet, IL-12p40, and IL-6. Oleci acid was the major gradient (52.89%) in C. japonica oil and also had anti-asthmatic effects such as the downregulation of inflammatory cells, WBC, and eosinophil in BALF, IgE in serum, and morphological changes in the lung.

CONCLUSION

We concluded that C. japonica oil is a new anti-asthmatic drug candidate and that oleic acid is the major anti-asthmatic ingredient in C. japonica oil.

Alveolar-Capillary Membrane-Related Pulmonary Cells as a Target in Endotoxin-Induced Acute Lung Injury

The main function of the lungs is oxygen transport from the atmosphere into the blood circulation, while it is necessary to keep the pulmonary tissue relatively free of pathogens. This is a difficult task because the respiratory system is constantly exposed to harmful substances entering the lungs by inhalation or via the blood stream. Individual types of lung cells are equipped with the mechanisms that maintain pulmonary homeostasis. Because of the clinical significance of acute respiratory distress syndrome (ARDS) the article refers to the physiological role of alveolar epithelial cells type I and II, endothelial cells, alveolar macrophages, and fibroblasts. However, all these cells can be damaged by lipopolysaccharide (LPS) which can reach the airspaces as the major component of the outer membrane of Gram-negative bacteria, and lead to local and systemic inflammation and toxicity. We also highlight a negative effect of LPS on lung cells related to alveolar-capillary barrier and their response to LPS exposure. Additionally, we describe the molecular mechanism of LPS signal transduction pathway in lung cells.

Coculture with bone marrow‑derived mesenchymal stem cells attenuates inflammation and apoptosis in lipopolysaccharide‑stimulated alveolar epithelial cells via enhanced secretion of keratinocyte growth factor and angiopoietin‑1 modulating the Toll‑like receptor‑4 signal pathway

Acute lung injury (ALI) is a common, costly and potentially lethal disease with characteristics of alveolar‑capillary membrane disruption, pulmonary edema and impaired gas exchange due to increased apoptosis and pulmonary inflammation. There is no effective and specific therapy for ALI; however, mesenchymal stem cells (MSCs) have been demonstrated to be a potential option. Lipopolysaccharide (LPS) is a highly proinflammatory molecule that is used to mimic an in vivo inflammatory and damaged state in vitro. The present study investigated the effect of bone marrow‑derived MSCs on an LPS‑induced alveolar epithelial cell (A549 cell line) injury and its underlying mechanisms by a Transwell system. It was identified that a high LPS concentration caused a decrease in cell viability, increases in apoptosis, inflammatory cytokine release and NF‑κB activity, disruption of the caspase‑3/Bcl‑2 ratio, upregulation of Toll‑like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88) and toll‑interleukin‑1 receptor domain‑containing adaptor inducing interferon (TRIF) expression, and facilitation of TLR4/MyD88 and TLR4/TRIF complex formation in A549 cells. Coculture with MSCs attenuated all of these activities induced by LPS in A549 cells. In addition, an increased level of keratinocyte growth factor (KGF) and angiopoietin‑1 (ANGPT1) secretion from MSCs was observed under inflammatory stimulation. KGF and/or ANGPT1 neutralizing antibodies diminished the beneficial effect of MSC conditioned medium. These data suggest that MSCs alleviate inflammatory damage and cellular apoptosis induced by LPS in A549 cells by modulating TLR4 signals. These changes may be partly associated with an increased secretion of KGF and ANGPT1 from MSCs under inflammatory conditions. These data provide the basis for development of MSC‑based therapies for ALI.

Furanoid F-Acid F6 Uniquely Induces NETosis Compared to C16 and C18 Fatty Acids in Human Neutrophils

Various biomolecules induce neutrophil extracellular trap (NET) formation or NETosis. However, the effect of fatty acids on NETosis has not been clearly established. In this study, we focused on the NETosis-inducing ability of several lipid molecules. We extracted the lipid molecules present in Arabian Gulf catfish (Arius bilineatus, Val) skin gel, which has multiple therapeutic activities. Gas chromatography⁻mass spectrometry (GC-MS) analysis of the lipid fraction-3 from the gel with NETosis-inducing activity contained fatty acids including a furanoid F-acid (F6; 12,15-epoxy-13,14-dimethyleicosa-12,14-dienoic acid) and common long-chain fatty acids such as palmitic acid (PA; C16:0), palmitoleic acid (PO; C16:1), stearic acid (SA; C18:0), and oleic acid (OA; C18:1). Using pure molecules, we show that all of these fatty acids induce NETosis to different degrees in a dose-dependent fashion. Notably, F6 induces a unique form of NETosis that is rapid and induces reactive oxygen species (ROS) production by both NADPH oxidase (NOX) and mitochondria. F6 also induces citrullination of histone. By contrast, the common fatty acids (PA, PO, SA, and OA) only induce NOX-dependent NETosis. The activation of the kinases such as ERK (extracellular signal-regulated kinase) and JNK (c-Jun N-terminal kinase) is important for long-chain fatty acid-induced NETosis, whereas, in F-acid-induced NETosis, Akt is additionally needed. Nevertheless, NETosis induced by all of these compounds requires the final chromatin decondensation step of transcriptional firing. These findings are useful for understanding F-acid- and other fatty acid-induced NETosis and to establish the active ingredients with therapeutic potential for regulating diseases involving NET formation.

A2BAR activation attenuates acute lung injury by inhibiting alveolar epithelial cell apoptosis both in vivo and in vitro

The epithelial barrier of the lung is destroyed during acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) due to the apoptosis of alveolar epithelial cells (AECs). Therefore, treatments that block AEC apoptosis might be a therapeutic strategy to ameliorate ALI. Based on recent evidence, A2B adenosine receptor (A2BAR) plays an important role in ALI in several different animal models, but its exact function in AECs has not been clarified. We investigated the role of A2BAR in AEC apoptosis in a mouse model of oleic acid (OA)-induced ALI and in hydrogen peroxide (H2O2)-induced AEC (A549 cells and MLE-12 cells) injury. Mice treated with BAY60-6583, a selective A2BAR agonist, showed lower AEC apoptosis rates than mice treated with OA. However, the role of BAY60-6583 in OA-induced ALI was attenuated by a specific blocker of A2BAR, PSB1115. A2BAR activation decreased H2O2-induced cell apoptosis in vitro, as characterized by the translocation of apoptotic proteins, the release of cytochrome c, and the activation of caspase-3 and poly (ADP ribose) polymerase 1 (PARP-1). In addition, apoptosis was required for the phosphorylation of ERK1/2, p38, and JNK. Importantly, compared with cells transfected with the A2BAR-siRNA, an ERK inhibitor or p38 inhibitor exhibited decreased apoptotic ratios and cleaved caspase-9 and cleaved PARP-1 levels, whereas the JNK inhibitor displayed increases in these parameters. In conclusion, A2BAR activation effectively attenuated OA-induced ALI by inhibiting AEC apoptosis and mitigated H2O2-induced AEC injury by suppressing the p38 and ERK1/2-mediated mitochondrial apoptosis pathway.

The effects of hydrogen peroxide and lipopolysaccharide on rat alveolar L2 cells

PURPOSE

This study aimed to investigate differential cell responses of alveolar epithelial cells (AECs) after treatments with lipopolysaccharide (LPS) and hydrogen peroxide (H₂O₂) to mimic the exposure to inflammation and oxidative stress and the mechanisms of a double-hit model of apoptosis.

MATERIALS AND METHODS

AECs were cultured and treated with combinations of 1 μg/mL of LPS and 500 μM H₂O₂ as follows: LPS-only at 0 h, LPS at 0 h with H₂O₂ at 6 h (LPS + H₂O₂), H₂O₂-only at 0 h, H₂O₂ at 0 h with LPS at 6 h (H₂O₂ + LPS), and control. We investigated mRNA expression (TNF-α, Fas, Fas ligand, Bax, Bcl-2, Caspase-7), protein expression (Fas, Bax, Bcl-2, Caspase-7) and apoptosis (Caspase-3 activity, TUNEL assay) at 0, 3, 6, 9, 12, and 24 h.

RESULTS

In the H₂O₂ + LPS group, the Caspase-7, and Fas mRNA levels were significantly higher than the other groups at 9 h and 12 h, and Bax was higher at 12 h. The Bax/Bcl-2 protein expression ratio was significantly higher in the H₂O₂ + LPS group than that of the other groups at 12h and 24h. Apoptotic index was highest in the H₂O₂ + LPS group at 24 h.

CONCLUSIONS

The sequence of stimulation may modify the cell response in rat AECs. The results suggest that previous oxidative stress and subsequent LPS-induced inflammation primarily influence apoptosis of L2 cells by up-regulation of cell signaling.

Pulmonary Surfactant and Bacterial Lipopolysaccharide: The Interaction and its Functional Consequences

The respiratory system is constantly exposed to pathogens which enter the lungs by inhalation or via blood stream. Lipopolysaccharide (LPS), also named endotoxin, can reach the airspaces as the major component of the outer membrane of Gram-negative bacteria, and lead to local inflammation and systemic toxicity. LPS affects alveolar type II (ATII) cells and pulmonary surfactant and although surfactant molecule has the effective protective mechanisms, excessive amount of LPS interacts with surfactant film and leads to its inactivation. From immunological point of view, surfactant specific proteins (SPs) SP-A and SP-D are best characterized, however, there is increasing evidence on the involvement of SP-B and SP-C and certain phospholipids in immune reactions. In animal models, the instillation of LPS to the respiratory system induces acute lung injury (ALI). It is of clinical importance that endotoxin-induced lung injury can be favorably influenced by intratracheal instillation of exogenous surfactant. The beneficial effect of this treatment was confirmed for both natural porcine and synthetic surfactants. It is believed that the surfactant preparations have anti-inflammatory properties through regulating cytokine production by inflammatory cells. The mechanism by which LPS interferes with ATII cells and surfactant layer, and its consequences are discussed below.

Hydrostatin-SN1, a Sea Snake-Derived Bioactive Peptide, Reduces Inflammation in a Mouse Model of Acute Lung Injury

Snake venom has been used for centuries as a traditional Chinese medicine. Hydrostatin-SN1 (H-SN1), a bioactive peptide extracted from the Hydrophis cyanocinctus venom gland T7 phage display library, was reported to have the ability to reduce inflammation in a dextran sulfate sodium-induced murine colitis model. In this study, we sought to investigate the inhibitory potential of H-SN1 on inflammation in a murine model of lipopolysaccharide (LPS)-induced acute lung injury (ALI), and elucidate the anti-inflammatory mechanism in LPS-stimulated RAW 264.7 cells. In vivo, C57BL/6 male mice were intratracheally instilled with LPS or physiological saline with concurrent intraperitoneal injection of H-SN1 or saline alone. Lung histopathologic changes, lung wet-to-dry weight ratio, and myeloperoxidase activity in lung tissues were assessed. Total cell number, the protein concentration, and cytokine levels were determined in the bronchial alveolar lavage fluid. In vitro, RAW 264.7 cells were treated with various concentrations of H-SN1 for 2 h followed by incubation with or without 1 μg/ml LPS for 0.5 or 24 h. The mRNA expression of inflammatory cytokines was determined via RT-PCR and protein levels in the supernatants were measured via ELISA. Extracellular-signal related kinase 1/2 (ERK1/2) and nuclear factor-κB (NF-κB) pathways were analyzed via western blot. H-SN1 improved pulmonary edema status, decreased vascular permeability, suppressed pro-inflammatory cytokine production, and lessened lung morphological injury. H-SN1 also dose-dependently inhibited the mRNA expression and release of TNF-α, IL-6, and IL-1β in LPS-stimulated RAW 264.7 cells. Moreover, H-SN1 inhibited the LPS-induced phosphorylation of ERK1/2 and the nuclear translocation of NF-κB. Our results suggest that H-SN1 could attenuate LPS-induced ALI in mice, which is associated with the anti-inflammatory effect of H-SN1. The mechanism might involve inhibiting the production of inflammatory cytokines by, at least in part, interfering with the ERK1/2 and NF-κB signaling pathways.