Glycochenodeoxycholate induces rat alveolar epithelial type II cell death and inhibits surfactant secretion in vitro

Farnesoid X Receptor Protects Murine Lung against IL-6-promoted Ferroptosis Induced by Polyriboinosinic-Polyribocytidylic Acid

Various infections trigger a storm of proinflammatory cytokines in which IL-6 acts as a major contributor and leads to diffuse alveolar damage in patients. However, the metabolic regulatory mechanisms of IL-6 in lung injury remain unclear. Polyriboinosinic-polyribocytidylic acid [poly(I:C)] activates pattern recognition receptors involved in viral sensing and is widely used in alternative animal models of RNA virus-infected lung injury. In this study, intratracheal instillation of poly(I:C) with or without an IL-6-neutralizing antibody model was combined with metabonomics, transcriptomics, and so forth to explore the underlying molecular mechanisms of IL-6-exacerbated lung injury. We found that poly(I:C) increased the IL-6 concentration, and the upregulated IL-6 further induced lung ferroptosis, especially in alveolar epithelial type II cells. Meanwhile, lung regeneration was impaired. Mechanistically, metabolomic analysis showed that poly(I:C) significantly decreased glycolytic metabolites and increased bile acid intermediate metabolites that inhibited the bile acid nuclear receptor farnesoid X receptor (FXR), which could be reversed by IL-6-neutralizing antibody. In the ferroptosis microenvironment, IL-6 receptor monoclonal antibody tocilizumab increased FXR expression and subsequently increased the Yes-associated protein (YAP) concentration by enhancing PKM2 in A549 cells. FXR agonist GW4064 and liquiritin, a potential natural herbal ingredient as an FXR regulator, significantly attenuated lung tissue inflammation and ferroptosis while promoting pulmonary regeneration. Together, the findings of the present study provide the evidence that IL-6 promotes ferroptosis and impairs regeneration of alveolar epithelial type II cells during poly(I:C)-induced murine lung injury by regulating the FXR-PKM2-YAP axis. Targeting FXR represents a promising therapeutic strategy for IL-6-associated inflammatory lung injury.

Clinical characteristics and outcomes in neonates with perinatal acute respiratory distress syndrome in China: A national, multicentre, cross-sectional study

BACKGROUND

Neonatal acute respiratory distress syndrome (NARDS) was defined in 2017 and the epidemiological data remain unknown. Our objective was to explore aetiological factors, clinical characteristics and outcomes in patients with perinatal NARDS.

METHODS

A multicentre, prospective, cross-sectional study was performed in 58 tertiary neonatal intensive care units in China from Jan 1, 2018 to June 30, 2019. Neonates diagnosed with NARDS were included. Primary outcomes were aetiological factors, clinical characteristics and outcomes. Binary logistic regression and multivariate cox proportional regression were performed to identify independent predictors for bronchopulmonary dysplasia (BPD) and/or death or single death. This study was registered with ClinicalTrials.Gov, NCT03311165.

FINDINGS

Among 70,013 admitted neonates, the incidence of NARDS was 1.44% (1005). The cumulative incidences were 65.6%, 86.7%, 94.1% within one, two and three days after birth. The median gestational age and birth weight were 36.4 weeks and 2700 g. Three main aetiological triggers included pneumonia (58.1%), asphyxia (24.3%) and early-onset sepsis (EOS) (21.3%). BPD and/or death was observed in 213 (21.2%) infants, consisting 104 (10.3%) BPD and 126 (12.6%) deaths. The numbers of mild, moderate and severe NARDS were 537 (53.4%), 286 (28.4%) and 182 (18.2%). Two or more doses of surfactant was associated with increased mortality as compared with one or less doses of surfactant (odds ratio [OR] 1.93, 95% confidence interval [CI] 1.20-3.10, P = 0.006). Similarity also appeared in the comparison between EOS and non-EOS triggers (OR 1.57, 95% CI 1.06-2.33, P = 0.023).

INTERPRETATION

NARDS incidence was 1.44% and the three main aetiologies were pneumonia, asphyxia and EOS. The cumulative incidences were 65.6%, 86.7%, and 94.1% within one, two and three days after birth. Our results suggested that two or more doses of surfactant increased mortality compared with one or less doses of surfactant.

FUNDING

The National Clinical Research Center of China and Clinical Medical Study Program of Children's Hospital of Chongqing Medical University (NCRC-2019-GP-13) and Natural Science Foundation of Chongqing (cstc2020jcyj-msxmX0197).

Aspiration of conjugated bile acids predicts adverse lung transplant outcomes and correlates with airway lipid and cytokine dysregulation

INTRODUCTION

Duodeno-gastroesophageal reflux aspiration is associated with chronic lung allograft dysfunction (CLAD). Reflux aspirate can contain bile acids (BA), functional molecules in the gastro-intestinal tract with emulsifying properties. We sought to determine and quantify the various BA species in airways of the lung transplant recipients to better understand the various effects of aspirated BA that contribute to post-transplantation outcomes.

METHODS

Bronchial washings (BW) were prospectively collected from lung transplant recipients and subsequently assayed by liquid chromatography-mass spectrometry for 13 BA and 25 lipid families. Patients were monitored for CLAD, rejection, inflammation and airway infections.

RESULTS

Detectable BA were present in 45/50 patients (90%) at 3 months after transplant. Elevated BA and predominance of conjugated species were independent predictors of CLAD (hazard ratio 7.9; 95% confidence interval 2.7-23.6; p < 0.001 and 7.3; 2.4-22; p < 0.001, respectively) and mortality (hazard ratio 4.4; 1.5-12.7; p = 0.007 and 4.8; 1.4-15.8; p = 0.01, respectively). High BA associated with increased positive bacterial cultures (60% vs 25%, p = 0.02). Primary conjugated species independently correlated with the rate of bacterial cultures during the first-year post-transplant (Beta coefficient: 0.77; 0.28-1.26; p = 0.003) and changes in airway lipidome and cytokines.

CONCLUSIONS

Higher BA levels and predominance of conjugated BA are independent predictors of chronic lung allograft dysfunction, mortality and bacterial infections. Primary conjugated BA are related to distinct changes in airway lipidome and inflammatory cytokines. This elucidates novel evidence into the mechanism following BA aspiration and proposes novel markers for prediction of adverse post-transplant outcomes.

Deoxycholic acid as a molecular scaffold for tyrosyl-DNA phosphodiesterase 1 inhibition: A synthesis, structure-activity relationship and molecular modeling study

Para-Bromoanilides of deoxycholic acid with various functional groups on the steroid scaffold were designed as promising tyrosyl-DNA phosphodiesterase 1 (Tdp1) inhibitors. Tdp1 is a DNA repair enzyme, involved in removing DNA damage caused by topoisomerase I poisons; an important class of anticancer drugs. Thus, reducing the activity of Tdp1 can increase the efficacy of anticancer drugs in current use. Inhibitory activity in the low micromolar and submicromolar concentrations was observed with 3,12-dimethoxy para-bromoanilide 17 being the most active with an IC50 value of 0.27 μM. The activity of N-methyl para-bromoanilides was 3-4.8 times lower than of the corresponding para-bromoanilides. Increased potency of the ligands was seen with higher molecular weight and log P values. The ligands were evaluated for their cytotoxic potential in a panel of tumor cell lines; all were nontoxic to the A549 pulmonary adenocarcinoma cell line. However, derivatives containing a hydroxyl group at the 12th position were more toxic than their 12-hydroxyl group counterparts (acetoxy-, oxo- and methoxy- group) against HCT-116 human colon and HepG2 hepatocellular carcinomas. In addition, an N-methyl substitution led to an increase in toxicity for the HCT-116 and HepG2 cell lines. The excellent activity as well as low cytotoxicity, derivative 17 can be considered as a lead compound for further development.

Guts and Gall: Bile Acids in Regulation of Intestinal Epithelial Function in Health and Disease

Epithelial cells line the entire surface of the gastrointestinal tract and its accessory organs where they primarily function in transporting digestive enzymes, nutrients, electrolytes, and fluid to and from the luminal contents. At the same time, epithelial cells are responsible for forming a physical and biochemical barrier that prevents the entry into the body of harmful agents, such as bacteria and their toxins. Dysregulation of epithelial transport and barrier function is associated with the pathogenesis of a number of conditions throughout the intestine, such as inflammatory bowel disease, chronic diarrhea, pancreatitis, reflux esophagitis, and cancer. Driven by discovery of specific receptors on intestinal epithelial cells, new insights into mechanisms that control their synthesis and enterohepatic circulation, and a growing appreciation of their roles as bioactive bacterial metabolites, bile acids are currently receiving a great deal of interest as critical regulators of epithelial function in health and disease. This review aims to summarize recent advances in this field and to highlight how bile acids are now emerging as exciting new targets for disease intervention.

Vaginal lipidomics of women with vulvovaginal candidiasis and cytolytic vaginosis: A non-targeted LC-MS pilot study

Objective

To characterize the lipid profile in vaginal discharge of women with vulvovaginal candidiasis, cytolytic vaginosis, or no vaginal infection or dysbiosis.

Design

Cross-sectional study.

Setting

Genital Infections Ambulatory, Department of Tocogynecology, University of Campinas, Campinas, São Paulo–Brazil.

Sample

Twenty-four women were included in this study: eight with vulvovaginal candidiasis, eight with cytolytic vaginosis and eight with no vaginal infections or dysbiosis (control group).

Methods

The lipid profile in vaginal discharge of the different study groups was determined by liquid chromatography-mass spectrometry and further analyzed with MetaboAnalyst 3.0 platform.

Main outcome measures

Vaginal lipids concentration and its correlation with vulvovaginal candidiasis and cytolytic vaginosis.

Results

PCA, PLS-DA and hierarchical clustering analyses indicated 38 potential lipid biomarkers for the different groups, correlating with oxidative stress, inflammation, apoptosis and integrity of the vaginal epithelial tissue. Among these, greater concentrations were found for Glycochenodeoxycholic acid-7-sulfate, O-adipoylcarnitine, 1-eicosyl-2-heptadecanoyl-glycero-3-phosphoserine, undecanoic acid, formyl dodecanoate and lipoic acid in the vulvovaginal candidiasis group; N–(tetradecanoyl)-sphinganine, DL-PPMP, 1-oleoyl-cyclic phosphatidic, palmitic acid and 5-aminopentanoic acid in the cytolytic vaginosis group; and 1-nonadecanoyl-glycero-3-phosphate, eicosadienoic acid, 1-stearoyl-cyclic-phosphatidic acid, 1-(9Z,12Z-heptadecadienoyl)-glycero-3-phosphate, formyl 9Z-tetradecenoate and 7Z,10Z-hexadecadienoic acid in the control group.

Conclusions

Lipids related to oxidative stress and apoptosis were found in higher concentrations in women with vulvovaginal candidiasis and cytolytic vaginosis, while lipids related to epithelial tissue integrity were more pronounced in the control group. Furthermore, in women with cytolytic vaginosis, we observed higher concentrations of lipids related to bacterial overgrowth.

Autophagy May Protect Against Parenteral Nutrition-Associated Liver Disease by Suppressing Endoplasmic Reticulum Stress

BACKGROUND

The objectives of this study were to address the role of autophagy in the pathogenesis of parenteral nutrition (PN)-associated liver disease (PNALD) and its possible mechanism in vivo.

METHODS

Five-week-old male Sprague Dawley rats were fed Shoobree chow (Xietong Organism, Jiangsu, China) and administered intravenous 0.9% saline (sham group), PN (PN group), PN plus rapamycin (1 mg/kg; PN + Rapa group), or rapamycin (Rapa group) for 7 days. Before and after study, body weight, biochemical indicators, hepatic histology, level of autophagy, hepatocyte apoptosis, reactive oxygen species (ROS), and endoplasmic reticulum (ER) stress indicators including binding immunoglobulin protein (BIP), spliced X-box-binding protein-1 (sXBP1), and CCAAT-enhancer-binding protein homologous protein (CHOP) were measured.

RESULTS

Autophagy was suppressed in the PNALD model, which was demonstrated by less light chain 3 fluorescence (LC3) puncta and lower LC3II expression. Rapamycin effectively induced hepatic autophagy in PN rats. The PN + Rapa group presented improved hepatic function, decreased pathology scores, and less steatosis than the PN group. In addition, rapamycin treatment decreased terminal deoxynucleotidyl transferase dUTP nick end labeling and cleaved-caspase 3 expression, indicating a lower level of hepatocyte apoptosis. Compared with the PN group, the PN + Rapa group had lower levels of ROS and reduced expression of ER stress-related protein markers, such as BIP, sXBP1 and CHOP.

CONCLUSIONS

Autophagy was suppressed in the PNALD model. Rapamycin treatment induced autophagy and protected against PNALD, possibly by suppressing ROS-induced ER stress.

Apoptosis and surfactant protein-C expression inhibition induced by lipopolysaccharide in AEC II cell may associate with NF-κB pathway

Lipopolysaccharide (LPS), a Gram-negative bacterial outer membrane component, is one of the major causes of septic shock. Herein we investigate LPS-induced apoptosis of rat alveolar epithelial type II cells (AEC II) and the effects of LPS on surfactant protein-C (SP-C) expression in AEC II, along with the possible molecular mechanisms. LPS exposure impaired cell viability and increased apoptosis of AEC II significantly in concentration-dependent manner embodied in increased caspase-3 expression and the activity of caspase-3. Simultaneously, our results also indicated that LPS inhibited surfactant protein-C (SP-C) expression in AEC II. Mechanistic studies revealed that LPS treatment significantly increased the expression of NF-κB p50, NF-κB p65 and IKKβ proteins as well as induced IκB-α phosphorylation. Moreover, pretreatment with IKK inhibitor IKK-16 or NF-κB inhibitor PDTC ameliorated LPS-caused alterations in cleaved caspase-3 expression, the activity of caspase-3 and SP-C expression. Taken together, these results demonstrate that LPS can induce apoptosis of AEC II and decrease SP-C expression partly through activating the NF-κB pathway.

Morphologic Damage of Rat Alveolar Epithelial Type II Cells Induced by Bile Acids Could Be Ameliorated by Farnesoid X Receptor Inhibitor Z-Guggulsterone In Vitro

Objective. To determine whether bile acids (BAs) affect respiratory functions through the farnesoid X receptor (FXR) expressed in the lungs and to explore the possible mechanisms of BAs-induced respiratory disorder. Methods. Primary cultured alveolar epithelial type II cells (AECIIs) of rat were treated with different concentrations of chenodeoxycholic acid (CDCA) in the presence or absence of FXR inhibitor Z-guggulsterone (GS). Then, expression of FXR in nuclei of AECIIs was assessed by immunofluorescence microscopy. And ultrastructural changes of the cells were observed under transmission electron microscope and analyzed by Image-Pro Plus software. Results. Morphologic damage of AECIIs was exhibited in high BAs group in vitro, with high-level expression of FXR, while FXR inhibitor GS could attenuate the cytotoxicity of BAs to AECIIs. Conclusions. FXR expression was related to the morphologic damage of AECIIs induced by BAs, thus influencing respiratory functions.

Bile acids induce activation of alveolar epithelial cells and lung fibroblasts through farnesoid X receptor-dependent and independent pathways

BACKGROUND AND OBJECTIVE

The roles of bile acid microaspiration and bile acid-activated farnesoid X receptor (FXR) in the pathogenesis of idiopathic pulmonary fibrosis (IPF) remain unclear. We hypothesized that bile acids activate alveolar epithelial cells (AECs) and lung fibroblasts, which may be regulated by FXR activation.

METHODS

Human AECs and normal or IPF-derived lung fibroblast cells were incubated with the three major bile acids: lithocholic acid (LCA), deoxycholic acid (DCA) and chenodeoxycholic acid (CDCA). The AECs injury indices, epithelial-mesenchymal transition (EMT) and lung fibroblast activation were evaluated. FXR expression in IPF lungs and the roles of FXR and FXR-independent pathways in bile acid-induced profibrotic effects were also investigated.

RESULTS

LCA, DCA and CDCA reduced cell viability and increased intracellular reactive oxygen species (ROS) production in A549 cells. They all induced EMT, as shown by enhanced α-SMA and vimentin and decreased E-cadherin levels. LCA directly induced differentiation of lung fibroblasts to myofibroblasts. All three bile acids promoted cellular migration but not proliferation of lung fibroblasts. FXR expression was upregulated in IPF lungs, and inhibition of FXR restrained the bile acid-induced EMT and lung fibroblast activation. Differentiation and proliferation were enhanced in lung fibroblasts exposed to conditioned medium from bile acid-stimulated A549 cells, which contained increased levels of profibrotic factors. TGF-β/Smad3 signaling was also involved in the bile acid-induced EMT and lung fibroblast differentiation.

CONCLUSION

Bile acid microaspiration may promote the development of pulmonary fibrosis by inducing activation of AECs and lung fibroblasts via FXR-dependent and independent pathways.

Noninvasive Ventilation for Preterm Twin Neonates with Respiratory Distress Syndrome: A Randomized Controlled Trial

Noninvasive ventilation has been proven to be effective strategies for reducing the need for endotracheal ventilation in preterm infant with respiratory distress syndrome (RDS), however the best option needs to be further determined. A single center, paired design, randomized, controlled trial was conducted between Jan 2011 and July 2014. Preterm twins with RDS were included. One of a pair was randomized to NIPPV, while another to NCPAP. Surfactant was administrated as rescue treatment. The primary outcome was the need for endotracheal ventilation. The secondary outcomes were the complications. 143 pairs were randomized and 129 pairs finished the trial. The rates of endotracheal ventilation did not differ significantly between NIPPV and NCPAP groups (11.9% vs 19.6%, P = 0.080). This difference was not observed in the subgroup of infants who received surfactant therapy (11.1% vs 19.7%, P = 0.087). No secondary outcomes also differed significantly between the two groups. NIPPV did not result in a significantly lower incidence of intubation as compared with NCPAP in preterm twins with RDS.

Alveolar type II epithelial cell dysfunction in rat experimental hepatopulmonary syndrome (HPS)

The hepatopulmonary syndrome (HPS) develops when pulmonary vasodilatation leads to abnormal gas exchange. However, in human HPS, restrictive ventilatory defects are also observed supporting that the alveolar epithelial compartment may also be affected. Alveolar type II epithelial cells (AT2) play a critical role in maintaining the alveolar compartment by producing four surfactant proteins (SPs, SP-A, SP-B, SP-C and SP-D) which also facilitate alveolar repair following injury. However, no studies have evaluated the alveolar epithelial compartment in experimental HPS. In this study, we evaluated the alveolar epithelial compartment and particularly AT2 cells in experimental HPS induced by common bile duct ligation (CBDL). We found a significant reduction in pulmonary SP production associated with increased apoptosis in AT2 cells after CBDL relative to controls. Lung morphology showed decreased mean alveolar chord length and lung volumes in CBDL animals that were not seen in control models supporting a selective reduction of alveolar airspace. Furthermore, we found that administration of TNF-α, the bile acid, chenodeoxycholic acid, and FXR nuclear receptor activation (GW4064) induced apoptosis and impaired SP-B and SP-C production in alveolar epithelial cells in vitro. These results imply that AT2 cell dysfunction occurs in experimental HPS and is associated with alterations in the alveolar epithelial compartment. Our findings support a novel contributing mechanism in experimental HPS that may be relevant to humans and a potential therapeutic target.

Activation of autophagy protects against cholestasis-induced hepatic injury

Background

Cholestasis is characterized by an abnormal accumulation of bile acids and causes hepatocellular injury. Recent studies show that autophagy is involved in the pathophysiology of many liver diseases. The potential role of autophagy in preventing cholestatic hepatotoxicity, however, has rarely been investigated. The aim of this study was to examine whether autophagy is involved in the cholestatic hepatotoxicity.

Results

We found that bile duct ligation (BDL) led to cholestatic liver injury and hepatocytic autophagy activation in the mice. Suppression of autophagy with Chloroquine (CQ) increased liver injury and hepatocytes apoptosis; while activation of autophagy by rapamycin reduced cholestasis hepatotoxicity. In L02 normal liver cells, Glycochenodeoxycholate (GCDC) treatment would induce autophagy. Inhibition of autophagy by CQ could promote GCDC-induced cell apoptosis. In contrast, rapamycin treatment could protect against GCDC-induced cell death. Furthermore, autophagy contributed to the liver cells survival via modulation of reactive oxygen species (ROS).

Conclusions

These findings indicate that autophagy protects against cholestasis induced liver injury and hepatocyte apoptosis by eliminating ROS accumulation. Our data suggest that enhancement of autophagy may be a therapeutic strategy to mitigate cholestatic liver injury.