IL-1β and Inflammasome Activity Link Inflammation to Abnormal Fetal Airway Development

BCL6 attenuates hyperoxia-induced lung injury by inhibiting NLRP3-mediated inflammation in fetal mouse

BACKGROUND

The transcriptional repressor B-cell lymphoma 6 (BCL6) has been reported to inhibit inflammation. So far, experimental evidence for the role of BCL6 in bronchopulmonary dysplasia (BPD) is lacking. Our study investigated the roles of BCL6 in the progression of BPD and its downstream mechanisms.

METHODS

Hyperoxia or lipopolysaccharide (LPS) was used to mimic the BPD mouse model. To investigate the effects of BCL6 on BPD, recombination adeno-associated virus serotype 9 expressing BCL6 (rAAV9-BCL6) and BCL6 inhibitor FX1 were administered in mice. The pulmonary pathological changes, inflammatory chemokines and NLRP3-related protein were observed. Meanwhile, BCL6 overexpression plasmid was used in human pulmonary microvascular endothelial cells (HPMECs). Cell proliferation, apoptosis, and NLRP3-related protein were detected.

RESULTS

Either hyperoxia or LPS suppressed pulmonary BCL6 mRNA expression. rAAV9-BCL6 administration significantly inhibited hyperoxia-induced NLRP3 upregulation and inflammation, attenuated alveolar simplification and dysregulated angiogenesis in BPD mice, which were characterized by decreased mean linear intercept, increased radical alveolar count and alveoli numbers, and the upregulated CD31 expression. Meanwhile, BCL6 overexpression promoted proliferation and angiogenesis, inhibited apoptosis and inflammation in hyperoxia-stimulated HPMECs. Moreover, administration of BCL6 inhibitor FX1 arrested growth and development. FX1-treated BPD mice exhibited exacerbation of alveolar pathological changes and pulmonary vessel permeability, with upregulated mRNA levels of pro-inflammatory cytokines and pro-fibrogenic factors. Furthermore, both rAAV9-BCL6 and FX1 administration exerted a long-lasting effect on hyperoxia-induced lung injury (≥4 wk).

CONCLUSIONS

BCL6 inhibits NLRP3-mediated inflammation, attenuates alveolar simplification and dysregulated pulmonary vessel development in hyperoxia-induced BPD mice. Hence, BCL6 may be a target in treating BPD and neonatal diseases.

Mechanistic Approach on the Pulmonary Oxido-Inflammatory Stress Induced by Cobalt Ferrite Nanoparticles in Rats

Cobalt ferrite nanoparticles (CFN) are employed in data storage, imaging, medication administration, and catalysis due to their superparamagnetic characteristics. The widespread use of CFN led to significantly increased exposure to people and the environment to these nanoparticles. Until now, there is not any published paper describing the adverse effect of repeated oral intake of this nanoformulation on rats' lungs. So, the current research aims to elucidate the pulmonary toxicity prompted by different concentrations of CFN in rats as well as to explore the mechanistic way of such toxicity. We used 28 rats that were divided equally into 4 groups. The control group received normal saline, and the experimental groups received CFN at dosage levels 0.05, 0.5, and 5 mg/kg bwt. Our findings revealed that CFN enhanced dose-dependent oxidative stress manifested by raising in the MDA levels and declining in the GSH content. The histopathological examination revealed interstitial pulmonary inflammation along with bronchial and alveolar damage in both 0.5 and 5 mg CFN given groups. All these lesions were confirmed by the immunohistochemical staining that demonstrated strong iNOS and Cox-2 protein expression. There was also a significant upregulation of TNFα, Cox-2, and IL-1β genes with downregulation of IL-10 and TGF-β genes. Additionally, the group receiving 0.05 mg CFN did not exhibit any considerable toxicity in all measurable parameters. We concluded that the daily oral intake of either 0.5 or 5 mg CFN, but not 0.05 mg, could induce pulmonary toxicity via NPs and/or its leached components (cobalt and iron)-mediated oxido-inflammatory stress. Our findings may help to clarify the mechanisms of pulmonary toxicity generated by these nanoparticles through outlining the standards for risk assessment in rats as a human model.

Early human lung immune cell development and its role in epithelial cell fate

Studies of human lung development have focused on epithelial and mesenchymal cell types and function, but much less is known about the developing lung immune cells, even though the airways are a major site of mucosal immunity after birth. An unanswered question is whether tissue-resident immune cells play a role in shaping the tissue as it develops in utero. Here, we profiled human embryonic and fetal lung immune cells using scRNA-seq, smFISH, and immunohistochemistry. At the embryonic stage, we observed an early wave of innate immune cells, including innate lymphoid cells, natural killer cells, myeloid cells, and lineage progenitors. By the canalicular stage, we detected naive T lymphocytes expressing high levels of cytotoxicity genes and the presence of mature B lymphocytes, including B-1 cells. Our analysis suggests that fetal lungs provide a niche for full B cell maturation. Given the presence and diversity of immune cells during development, we also investigated their possible effect on epithelial maturation. We found that IL-1β drives epithelial progenitor exit from self-renewal and differentiation to basal cells in vitro. In vivo, IL-1β-producing myeloid cells were found throughout the lung and adjacent to epithelial tips, suggesting that immune cells may direct human lung epithelial development.

Overactivated Epithelial NF-κB Disrupts Lung Development in Congenital Diaphragmatic Hernia

Abnormal lung development is the main cause of morbidity and mortality in neonates with congenital diaphragmatic hernia (CDH), a common birth defect (1:2,500) of largely unknown pathobiology. Recent studies discovered that inflammatory processes, and specifically NF-κB-associated pathways, are enriched in human and experimental CDH. However, the molecular signaling of NF-κB in abnormal CDH lung development and its potential as a therapeutic target require further investigation. Using sections and hypoplastic lung explant cultures from the nitrofen rat model of CDH and human fetal CDH lungs, we demonstrate that NF-κB and its downstream transcriptional targets are hyperactive during abnormal lung formation in CDH. NF-κB activity was especially elevated in the airway epithelium of nitrofen and human CDH lungs at different developmental stages. Fetal rat lung explants had impaired pseudoglandular airway branching after exposure to nitrofen, together with increased phosphorylation and transcriptional activity of NF-κB. Dexamethasone, the broad and clinically applicable antiinflammatory NF-κB antagonist, rescued lung branching and normalized NF-κB signaling in hypoplastic lung explants. Moreover, specific NF-κB inhibition with curcumenol similarly rescued ex vivo lung hypoplasia and restored NF-κB signaling. Last, we showed that prenatal intraperitoneal dexamethasone administration to pregnant rat dams carrying fetuses with hypoplastic lungs significantly improves lung branching and normalizes NF-κB in vivo. Our results indicate that NF-κB is aberrantly activated in human and nitrofen CDH lungs. Antiinflammatory treatment with dexamethasone and/or specific NF-κB inhibition should be investigated further as a therapeutic avenue to target lung hypoplasia in CDH.

A key role for NLRP3 signaling in preterm labor and birth driven by the alarmin S100B

Preterm birth remains the leading cause of neonatal morbidity and mortality worldwide. A substantial number of spontaneous preterm births occur in the context of sterile intra-amniotic inflammation, a condition that has been mechanistically proven to be triggered by alarmins. However, sterile intra-amniotic inflammation still lacks treatment. The NLRP3 inflammasome has been implicated in sterile intra-amniotic inflammation; yet, its underlying mechanisms, as well as the maternal and fetal contributions to this signaling pathway, are unclear. Herein, by utilizing a translational and clinically relevant model of alarmin-induced preterm labor and birth in Nlrp3-/- mice, we investigated the role of NLRP3 signaling by using imaging and molecular biology approaches. Nlrp3 deficiency abrogated preterm birth and the resulting neonatal mortality induced by the alarmin S100B by impeding the premature activation of the common pathway of labor as well as by dampening intra-amniotic and fetal inflammation. Moreover, Nlrp3 deficiency altered leukocyte infiltration and functionality in the uterus and decidua. Last, embryo transfer revealed that maternal and fetal Nlrp3 signaling contribute to alarmin-induced preterm birth and neonatal mortality, further strengthening the concept that both individuals participate in the complex process of preterm parturition. These findings provide novel insights into sterile intra-amniotic inflammation, a common etiology of preterm labor and birth, suggesting that the adverse perinatal outcomes resulting from prematurity can be prevented by targeting NLRP3 signaling.

Sp3 is essential for normal lung morphogenesis and cell cycle progression during mouse embryonic development

Members of the Sp family of transcription factors regulate gene expression via binding GC boxes within promoter regions. Unlike Sp1, which stimulates transcription, the closely related Sp3 can either repress or activate gene expression and is required for perinatal survival in mice. Here, we use RNA-seq and cellular phenotyping to show how Sp3 regulates murine fetal cell differentiation and proliferation. Homozygous Sp3-/- mice were smaller than wild-type and Sp+/- littermates, died soon after birth and had abnormal lung morphogenesis. RNA-seq of Sp3-/- fetal lung mesenchymal cells identified alterations in extracellular matrix production, developmental signaling pathways and myofibroblast/lipofibroblast differentiation. The lungs of Sp3-/- mice contained multiple structural defects, with abnormal endothelial cell morphology, lack of elastic fiber formation, and accumulation of lipid droplets within mesenchymal lipofibroblasts. Sp3-/- cells and mice also displayed cell cycle arrest, with accumulation in G0/G1 and reduced expression of numerous cell cycle regulators including Ccne1. These data detail the global impact of Sp3 on in vivo mouse gene expression and development.

The Impact of Curcumin on Immune Response: An Immunomodulatory Strategy to Treat Sepsis

Primary and secondary immunodeficiencies cause an alteration in the immune response which can increase the rate of infectious diseases and worsened prognoses. They can also alter the immune response, thus, making the infection even worse. Curcumin is the most biologically active component of the turmeric root and appears to be an antimicrobial agent. Curcumin cooperates with various cells such as macrophages, dendritic cells, B, T, and natural killer cells to modify the body's defence capacity. Curcumin also inhibits inflammatory responses by suppressing different metabolic pathways, reduces the production of inflammatory cytokines, and increases the expression of anti-inflammatory cytokines. Curcumin may also affect oxidative stress and the non-coding genetic material. This review analyses the relationships between immunodeficiency and the onset of infectious diseases and discusses the effects of curcumin and its derivatives on the immune response. In addition, we analyse some of the preclinical and clinical studies that support its possible use in prophylaxis or in the treatment of infectious diseases. Lastly, we examine how nanotechnologies can enhance the clinical use of curcumin.

Quercetin alleviates ferroptosis accompanied by reducing M1 macrophage polarization during neutrophilic airway inflammation

Ferroptosis is a kind of regulated cell death, supporting the pathological process of lung inflammation, including asthma. Quercetin (QCT), a kind of natural dietary flavonoid, exerts anti-inflammatory and anti-ferroptosis effects in various diseases. However, the role of QCT in ferroptosis-associated airway inflammation of neutrophilic asthma remains to be described. Our study aimed to investigate the therapeutic effects of QCT on neutrophilic airway inflammation of asthma. Ferrostatin-1 (Fer-1), as a kind of ferroptosis inhibitor, was used to demonstrate whether neutrophilic airway inflammation of asthma relied on ferroptosis. In our study, the alleviation effect of QCT on neutrophilic airway inflammation was similar to Fer-1. Moreover, the significantly decreased levels of ferroptosis anti-oxidant protein (GPX4 and SLC7A11), increased malondialdehyde (MDA) levels, upregulated levels of 4-hydroxynonenal (4-HNE) expression by immunohistochemistry, and distorted mitochondria morphological changes in the lung tissues suggested lung ferroptosis in neutrophilic airway inflammation, which could be reversed by QCT treatment. In vitro experiments showed that QCT reduced LPS-induced ferroptosis through upregulating cell viability and levels of ferroptosis anti-oxidant protein (SLC7A11 and GPX4), reducing inflammatory cytokines, and decreasing the levels of MDA. Furthermore, ferroptosis was accompanied by enhancing M1 phenotype in neutrophilic airway inflammation, and QCT suppressed ferroptosis by inhibiting the pro-inflammatory M1 profile in vitro and in vivo, just as Fer-1 did. In conclusion, our study found that QCT ameliorated ferroptosis-associated neutrophilic airway inflammation accompanied by inhibiting M1 macrophage polarization. QCT may be a promising ferroptosis inhibitor for neutrophilic airway inflammation.

Insights into the Black Box of Intra-Amniotic Infection and Its Impact on the Premature Lung: From Clinical and Preclinical Perspectives

Intra-amniotic infection (IAI) is one major driver for preterm birth and has been demonstrated by clinical studies to exert both beneficial and injurious effects on the premature lung, possibly due to heterogeneity in the microbial type, timing, and severity of IAI. Due to the inaccessibility of the intra-amniotic cavity during pregnancies, preclinical animal models investigating pulmonary consequences of IAI are indispensable to elucidate the pathogenesis of bronchopulmonary dysplasia (BPD). It is postulated that on one hand imbalanced inflammation, orchestrated by lung immune cells such as macrophages, may impact on airway epithelium, vascular endothelium, and interstitial mesenchyme, resulting in abnormal lung development. On the other hand, excessive suppression of inflammation may as well cause pulmonary injury and a certain degree of inflammation is beneficial. So far, effective strategies to prevent and treat BPD are scarce. Therapeutic options targeting single mediators in signaling cascades and mesenchymal stromal cells (MSCs)-based therapies with global regulatory capacities have demonstrated efficacy in preclinical animal models and warrant further validation in patient populations. Ante-, peri- and postnatal exposome analysis and therapeutic investigations using multiple omics will fundamentally dissect the black box of IAI and its effect on the premature lung, contributing to precisely tailored and individualized therapies.

Hyperoxia Induced Bronchopulmonary Dysplasia-Like Inflammation via miR34a-TNIP2-IL-1β Pathway

Lung injury induced by oxygen is a key contributor to the pathogenesis of preterm infant bronchopulmonary dysplasia (BPD). To date, there are comprehensive therapeutic strategy for this disease, but the underlying mechanism is still in progress. By using lentivirus, we constructed microRNA34a (miR34a)-overexpressing or knockdown A549 cell lines, and exposure to hyperoxia to mimic oxygen induce lung injury. In this study, we investigated 4 proinflammatory cytokines, interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), angiopoietin-1 (Ang-1), and Cyclooxygenase-2 (COX-2) in the secreted sputum of infants who received mechanical ventilation, and found that IL-1β was substantially elevated in the first week after oxygen therapy and with no significant decrease until the fourth week, while TNF-α, Ang-1, and COX-2 were increased in the first week but decreased quickly in the following weeks. In addition, in vitro assay revealed that hyperoxia significantly increased the expression of miR-34a, which positively regulated the proinflammatory cytokine IL-1β in a time- and concentration-dependent manner in A549 cells. Overexpressing or knockdown miR34 would exacerbate or inhibit production of IL-1β and its upstream NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome signaling pathway. Mechanically, it's found that TNFAIP3 interacting protein 2 (TNIP2), an inhibitor of nuclear factor κB (NF-κB), is a direct target of miR34a, negatively regulated activation of NLRP3 inflammasome and the production of IL-1β. Overexpressing TNIP2 ameliorated hyperoxia-induced production of IL-1β and cell apoptosis. Our findings suggest that TNIP2 may be a potential clinical marker in the diagnosis of BPD.

Establishment of tissue-resident immune populations in the fetus

The immune system establishes during the prenatal period from distinct waves of stem and progenitor cells and continuously adapts to the needs and challenges of early postnatal and adult life. Fetal immune development not only lays the foundation for postnatal immunity but establishes functional populations of tissue-resident immune cells that are instrumental for fetal immune responses amidst organ growth and maturation. This review aims to discuss current knowledge about the development and function of tissue-resident immune populations during fetal life, focusing on the brain, lung, and gastrointestinal tract as sites with distinct developmental trajectories. While recent progress using system-level approaches has shed light on the fetal immune landscape, further work is required to describe precise roles of prenatal immune populations and their migration and adaptation to respective organ environments. Defining points of prenatal susceptibility to environmental challenges will support the search for potential therapeutic targets to positively impact postnatal health.

A single-cell atlas of mouse lung development

Lung organogenesis requires precise timing and coordination to effect spatial organization and function of the parenchymal cells. To provide a systematic broad-based view of the mechanisms governing the dynamic alterations in parenchymal cells over crucial periods of development, we performed a single-cell RNA-sequencing time-series yielding 102,571 epithelial, endothelial and mesenchymal cells across nine time points from embryonic day 12 to postnatal day 14 in mice. Combining computational fate-likelihood prediction with RNA in situ hybridization and immunofluorescence, we explore lineage relationships during the saccular to alveolar stage transition. The utility of this publicly searchable atlas resource (www.sucrelab.org/lungcells) is exemplified by discoveries of the complexity of type 1 pneumocyte function and characterization of mesenchymal Wnt expression patterns during the saccular and alveolar stages - wherein major expansion of the gas-exchange surface occurs. We provide an integrated view of cellular dynamics in epithelial, endothelial and mesenchymal cell populations during lung organogenesis.

Amniotic fluid-derived extracellular vesicles: characterization and therapeutic efficacy in an experimental model of bronchopulmonary dysplasia

BACKGROUND AIMS

Extracellular vesicles (EVs) are being tested for their use as novel therapeutics. However, the optimal source of EVs is currently under investigation. Amniotic fluid (AF) is a natural source of EVs that can be easily obtained for use in regenerative medicine, yet AF-EV characterization has not been fully explored.

METHODS

Here the authors demonstrate AF as a rich source of EVs and identify the microRNA and proteomic cargo. Bioinformatics analysis of this cargo revealed multiple pathway targets, including immunomodulatory, anti-inflammatory and free radical scavenging networks. The authors further demonstrated the therapeutic potential of this EV product as a novel preventative agent for bronchopulmonary dysplasia (BPD).

RESULTS

Intra-tracheal administration of AF-EVs preserved alveolar development, attenuated vascular remodeling and pulmonary hypertension, decreased lung pro-inflammatory cytokine expression and reduced macrophage infiltration in an experimental BPD model.

CONCLUSIONS

The authors' results suggest that AF is a viable biological fluid for EV harvest and that AF-EVs have strong therapeutic potential for pulmonary diseases, such as BPD, warranting further development to transition this novel EV product into the clinic.

Antenatal Mesenchymal Stromal Cell Extracellular Vesicle Therapy Prevents Preeclamptic Lung Injury in Mice

In preeclamptic pregnancies, a variety of intrauterine alterations lead to abnormal placentation, release of inflammatory/antiangiogenic factors, and subsequent fetal growth restriction with significant potential to cause a primary insult to the developing fetal lung. Thus, modulation of the maternal intrauterine environment may be a key therapeutic avenue to prevent preeclampsia-associated developmental lung injury. A biologic therapy of interest are mesenchymal stromal cell-derived extracellular vesicles (MEx), which we have previously shown to ameliorate preeclamptic physiology through intrauterine immunomodulation. To evaluate the therapeutic potential of MEx to improve developmental lung injury in experimental preeclampsia. Using the heme oxygenase-1 null mouse (Hmox1-/-) model, preeclamptic pregnant dams were administered intravenous antenatal MEx treatment during each week of pregnancy followed by analysis of fetal and postnatal lung tissues, amniotic fluid protein profiles and lung explant/amniotic fluid co-cultures in comparison with control and untreated preeclamptic pregnancies. We first identified that a preeclamptic intrauterine environment had a significant adverse impact on fetal lung development including alterations in fetal lung developmental gene profiles in addition to postnatal alveolar and bronchial changes. Amniotic fluid proteomic analysis and fetal lung explant/amniotic fluid co-cultures further demonstrated that maternally administered MEx altered the expression of multiple inflammatory mediators in the preeclamptic intrauterine compartment resulting in normalization of fetal lung branching morphogenesis and developmental gene expression. Our evaluation of fetal and postnatal parameters overall suggests that antenatal MEx treatment may provide a highly valuable preventative therapeutic modality for amelioration of lung development in preeclamptic disease.

The immunological link between neonatal lung and eye disease

Bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) are two neonatal diseases of major clinical importance, arising in large part as a consequence of supplemental oxygen therapy used to promote the survival of preterm infants. The presence of coincident inflammation in the lungs and eyes of neonates receiving oxygen therapy indicates that a dysregulated immune response serves as a potential common pathogenic factor for both diseases. This review examines the current state of knowledge of immunological dysregulation in BPD and ROP, identifying similarities in the cellular subsets and inflammatory cytokines that are found in the alveoli and retina during the active phase of these diseases, indicating possible mechanistic overlap. In addition, we highlight gaps in the understanding of whether these responses emerge independently in the lung and retina as a consequence of oxygen exposure or arise because of inflammatory spill‐over from the lung. As BPD and ROP are anatomically distinct, they are often considered discreet disease entities and are therefore treated separately. We propose that an improved understanding of the relationship between BPD and ROP is key to the identification of novel therapeutic targets to treat or prevent both conditions simultaneously.

NLRP3-Inflammasome Inhibition during Respiratory Virus Infection Abrogates Lung Immunopathology and Long-Term Airway Disease Development

Respiratory syncytial virus (RSV) infects most infants by two years of age. It can cause severe disease leading to an increased risk of developing asthma later in life. Previously, our group has shown that RSV infection in mice and infants promotes IL-1β production. Here, we characterized the role of NLRP3-Inflammasome activation during RSV infection in adult mice and neonates. We observed that the inhibition of NLRP3 activation using the small molecule inhibitor, MCC950, or in genetically modified NLRP3 knockout (Nlrp3−/−) mice during in vivo RSV infection led to decreased lung immunopathology along with a reduced expression of the mucus-associated genes and reduced production of innate cytokines (IL-1β, IL-33 and CCL2) linked to severe RSV disease while leading to significant increases in IFN-β. NLRP3-inflammasome inhibition or deletion diminished Th2 cytokines and inflammatory cell infiltration into the lungs. Furthermore, NLRP3 inhibition or deletion during early-life RSV infection led to reducing viral-exacerbated allergic response in a mouse model of RSV-induced allergy exacerbation. Here, we demonstrated the critical role of NLRP3-inflammasome activation in RSV immunopathology and the related long-term airway alteration. Moreover, these findings suggest the NLRP3-inflammasome as a potential therapeutic target to attenuate severe RSV disease and limit childhood asthma development.

New Pharmacologic Approaches to Bronchopulmonary Dysplasia

Bronchopulmonary Dysplasia is the most common long-term respiratory morbidity of preterm infants, with the risk of development proportional to the degree of prematurity. While its pathophysiologic and histologic features have changed over time as neonatal demographics and respiratory therapies have evolved, it is now thought to be characterized by impaired distal lung growth and abnormal pulmonary microvascular development. Though the exact sequence of events leading to the development of BPD has not been fully elucidated and likely varies among patients, it is thought to result from inflammatory and mechanical/oxidative injury from chronic ventilatory support in fragile, premature lungs susceptible to injury from surfactant deficiency, structural abnormalities, inadequate antioxidant defenses, and a chest wall that is more compliant than the lung. In addition, non-pulmonary issues may adversely affect lung development, including systemic infections and insufficient nutrition. Once BPD has developed, its management focuses on providing adequate gas exchange while promoting optimal lung growth. Pharmacologic strategies to ameliorate or prevent BPD continue to be investigated. A variety of agents, to be reviewed henceforth, have been developed or re-purposed to target different points in the pathways that lead to BPD, including anti-inflammatories, diuretics, steroids, pulmonary vasodilators, antioxidants, and a number of molecules involved in the cell signaling cascade thought to be involved in the pathogenesis of BPD.

Single cell transcriptomic analysis of murine lung development on hyperoxia-induced damage

During late lung development, alveolar and microvascular development is finalized to enable sufficient gas exchange. Impaired late lung development manifests as bronchopulmonary dysplasia (BPD) in preterm infants. Single-cell RNA sequencing (scRNA-seq) allows for assessment of complex cellular dynamics during biological processes, such as development. Here, we use MULTI-seq to generate scRNA-seq profiles of over 66,000 cells from 36 mice during normal or impaired lung development secondary to hyperoxia with validation of some of the findings in lungs from BPD patients. We observe dynamic populations of cells, including several rare cell types and putative progenitors. Hyperoxia exposure, which mimics the BPD phenotype, alters the composition of all cellular compartments, particularly alveolar epithelium, stromal fibroblasts, capillary endothelium and macrophage populations. Pathway analysis and predicted dynamic cellular crosstalk suggest inflammatory signaling as the main driver of hyperoxia-induced changes. Our data provides a single-cell view of cellular changes associated with late lung development in health and disease.

Transcriptional profiling of lung macrophages identifies a predictive signature for inflammatory lung disease in preterm infants

Lung macrophages mature after birth, placing newborn infants, particularly those born preterm, within a unique window of susceptibility to disease. We hypothesized that in preterm infants, lung macrophage immaturity contributes to the development of bronchopulmonary dysplasia (BPD), the most common serious complication of prematurity. By measuring changes in lung macrophage gene expression in preterm patients at risk of BPD, we show here that patients eventually developing BPD had higher inflammatory mediator expression even on the first day of life. Surprisingly, the ex vivo response to LPS was similar across all samples. Our analysis did however uncover macrophage signature genes whose expression increased in the first week of life specifically in patients resilient to disease. We propose that these changes describe the dynamics of human lung macrophage differentiation. Our study therefore provides new mechanistic insight into both neonatal lung disease and human developmental immunology.

Bioinformatic analysis of the molecular mechanism underlying bronchial pulmonary dysplasia using a text mining approach

Bronchopulmonary dysplasia (BPD) is a common disease of premature infants with very low birth weight. The mechanism is inconclusive. The aim of this study is to systematically explore BPD-related genes and characterize their functions.Natural language processing analysis was used to identify BPD-related genes. Gene data were extracted from PubMed database. Gene ontology, pathway, and network analysis were carried out, and the result was integrated with corresponding database.In this study, 216 genes were identified as BPD-related genes with P < .05, and 30 pathways were identified as significant. A network of BPD-related genes was also constructed with 17 hub genes identified. In particular, phosphatidyl inositol-3-enzyme-serine/threonine kinase signaling pathway involved the largest number of genes. Insulin was found to be a promising candidate gene related with BPD, suggesting that it may serve as an effective therapeutic target.Our data may help to better understand the molecular mechanisms underlying BPD. However, the mechanisms of BPD are elusive, and further studies are needed.

Sex-differences in LPS-induced neonatal lung injury

Being of the male sex has been identified as a risk factor for multiple morbidities associated with preterm birth, including bronchopulmonary dysplasia (BPD). Exposure to inflammatory stress is a well-recognized risk factor for developing BPD. Whether there is a sex difference in pulmonary innate immune TLR4 signaling, lung injury and subsequent abnormal lung development is unknown. Neonatal (P0) male and female mice (ICR) were exposed to systemic LPS (5 mg/kg, IP) and innate immune signaling, and the transcriptional response were assessed (1 and 5 hours), along with lung development (P7). Male and female mice demonstrated a similar degree of impaired lung development with decreased radial alveolar counts, increased surface area, increased airspace area and increased mean linear intercept. We found no differences between male and female mice in the baseline pulmonary expression of key components of TLR4-NFκB signaling, or in the LPS-induced pulmonary expression of key mediators of neonatal lung injury. Finally, we found no difference in the kinetics of LPS-induced pulmonary NFκB activation between male and female mice. Together, these data support the conclusion that the innate immune response to early postnatal LPS exposure and resulting pulmonary sequelae is similar in male and female mice.

Caffeine Inhibits NLRP3 Inflammasome Activation by Suppressing MAPK/NF-κB and A2aR Signaling in LPS-Induced THP-1 Macrophages

Excessive inflammation induced by various risk factors is associated with the development of bronchopulmonary dysplasia (BPD). Caffeine exerts potent anti-inflammatory effects as a clinical preventive medicine for BPD. Recently, NLRP3 inflammasome activation has been demonstrated to be essential for the pathogenesis of BPD. In the present study, we aimed to investigate the effects of caffeine on NLRP3 inflammasome activation in LPS-induced THP-1 macrophages and to explore the underlying the detailed mechanism. We found that caffeine significantly reduced NLRP3 expression, ASC speck formation, and caspase 1 cleavage and therefore decreased IL-1β and IL-18 secretion in THP-1 macrophages. Caffeine also markedly decreased the phosphorylation levels of MAPK and NF-κB pathway members, further suppressing the translocation of NF-κB in THP-1 macrophages. Moreover, silencing of the caffeine-antagonized adenosine A2a receptor (A2aR) significantly decreased cleaved caspase 1 expression in THP-1 macrophages by reducing ROS production. Given these findings, we conclude that caffeine inhibits NLRP3 inflammasome activation by suppressing MAPK/NF-κB signaling and A2aR-associated ROS production in LPS-induced THP-1 macrophages.

Differential Immune Activation in Fetal Macrophage Populations

Distinct macrophage subsets populate the developing embryo and fetus in distinct waves. However little is known about the functional differences between in utero macrophage populations or how they might contribute to fetal and neonatal immunity. Here we tested the innate immune response of mouse macrophages derived from the embryonic yolk sac and from fetal liver. When isolated from liver or lung, CD11bHI fetal liver derived macrophages responded to the TLR4 agonist LPS by expressing and releasing inflammatory cytokines. However F4/80HI macrophages from the yolk sac did not respond to LPS treatment. While differences in TLR4 expression did not appear to explain these data, F4/80HI macrophages had much lower NLRP3 inflammasome expression compared to CD11bHI macrophages. Gene expression profiling also demonstrated LPS-induced expression of inflammatory genes in CD11bHI macrophages, but not in F4/80HI cells. Genes expressed in LPS-treated CD11bHI macrophages were more likely to contain predicted NF-κB binding sites in their promoter regions. Our data show that CD11bHI macrophages derived from fetal liver are the major pro-inflammatory cells in the developing fetus. These findings could have important implications in better understanding the fetal inflammatory response and the unique features of neonatal immunity.

Bronchopulmonary dysplasia: Pathophysiology and potential anti-inflammatory therapies

Inflammation of the preterm lungs is key to the pathogenesis of bronchopulmonary dysplasia (BPD), whether it arises as a consequence of intrauterine inflammation or postnatal respiratory management. This review explores steroidal and non-steroidal therapies for reducing neonatal pulmonary inflammation, aimed at treating or preventing BPD.

IL-1 and TNFα Contribute to the Inflammatory Niche to Enhance Alveolar Regeneration

Inflammatory responses are known to facilitate tissue recovery following injury. However, the precise mechanisms that enhance lung alveolar regeneration remain unclear. Here, using an organoid-based screening assay, we find that interleukin-1 (IL-1) and tumor necrosis factor α (TNFα) enhance the proliferation of AEC2s while maintaining their differentiation capacity. Furthermore, we find that expression of IL-1β and TNFα are induced in the AEC2 niche following influenza-induced injury in vivo, and lineage tracing analysis revealed that surviving AEC2s around the damaged area contribute to alveolar regeneration. Through genetic and pharmacological modulation of multiple components of the IL-1-nuclear factor κB (NF-κB) signaling axis, we show that cell-intrinsic as well as stromal mediated IL-1 signaling are essential for AEC2 mediated lung regeneration. Taken together, we propose that the IL-1/TNFα-NF-κB signaling axis functions as a component of an inflammation-associated niche to regulate proliferation of surviving AEC2s and promote lung regeneration.

•

IL-1/TNFα enhance the growth of lung alveolar stem cells (AEC2s) in organoid culture

•

AEC2s treated with IL-1 or TNFα maintain differentiation ability

•

AEC2s proliferate and contribute to lung repair after influenza virus infection

•

NF-κB pathway is activated in AEC2s treated with IL-1 or TNFα

Inflammasomes: Pandora's box for sepsis

Sepsis was known to ancient Greeks since the time of great physician Hippocrates (460-377 BC) without exact information regarding its pathogenesis. With time and medical advances, it is now considered as a condition associated with organ dysfunction occurring in the presence of systemic infection as a result of dysregulation of the immune response. Still with this advancement, we are struggling for the development of target-based therapeutic approach for the management of sepsis. The advancement in understanding the immune system and its working has led to novel discoveries in the last 50 years, including different pattern recognition receptors. Inflammasomes are also part of these novel discoveries in the field of immunology which are <20 years old in terms of their first identification. They serve as important cytosolic pattern recognition receptors required for recognizing cytosolic pathogens, and their pathogen-associated molecular patterns play an important role in the pathogenesis of sepsis. The activation of both canonical and non-canonical inflammasome signaling pathways is involved in mounting a proinflammatory immune response via regulating the generation of IL-1β, IL-18, IL-33 cytokines and pyroptosis. In addition to pathogens and their pathogen-associated molecular patterns, death/damage-associated molecular patterns and other proinflammatory molecules involved in the pathogenesis of sepsis affect inflammasomes and vice versa. Thus, the present review is mainly focused on the inflammasomes, their role in the regulation of immune response associated with sepsis, and their targeting as a novel therapeutic approach.

TLR Activation Alters Bone Marrow-Derived Macrophage Differentiation

Early exposure to inflammatory signals may have a lasting impact on immune function. Present throughout embryogenesis, macrophages are key cells providing innate immune protection to the developing fetus and newborn. Here, we have used an established model of macrophage development to test how early inflammatory signals can impact cellular differentiation and function. Bone marrow-derived macrophages were treated with Escherichia coli lipopolysaccharide (LPS) 2 days after initial isolation and culture. LPS treatment during this early stage of differentiation decreased the expression of CSF1R and increased that of the mature macrophage marker F4/80. These early changes in macrophage differentiation were also measured in cells from mice lacking IKKβ, but the change in CSF1R expression after LPS treatment was blocked with MAPK inhibition. LPS-induced changes in macrophage marker expression persisted following LPS removal, suggesting that early inflammatory activation could induce a lasting developmental impact. Early LPS exposure inhibited macrophage phagocytosis of labeled E. coli while LPS had no effect on fully differentiated macrophages. Our data demonstrate that early inflammatory exposure to a microbial stimulus induce lasting phenotypic changes in macrophages.

FGF10 and Human Lung Disease Across the Life Spectrum

Lung diseases impact patients across the lifespan, from infants in the first minutes of life through the aged population. Congenital abnormalities of lung structure can cause lung disease at birth or make adults more susceptible to chronic disease. Continuous inhalation of atmospheric components also requires the lung to be resilient to cellular injury. Fibroblast growth factor 10 (FGF10) regulates multiple stages of structural lung morphogenesis, cellular differentiation, and the response to injury. As a driver of lung airway branching morphogenesis, FGF10 signaling defects during development lead to neonatal lung disease. Alternatively, congenital airway abnormalities attributed to FGF10 mutations increase the risk of chronic airway disease in adulthood. FGF10 also maintains progenitor cell populations in the airway and promotes alveolar type 2 cell expansion and differentiation following injury. Here we review the cellular and molecular mechanisms linking FGF10 to multiple lung diseases, from bronchopulmonary dysplasia in extremely preterm neonates, cystic fibrosis in children, and chronic adult lung disorders. Understanding the connections between FGF10 and lung diseases may lead to exciting new therapeutic strategies.

Nootkatone, a neuroprotective agent from Alpiniae Oxyphyllae Fructus, improves cognitive impairment in lipopolysaccharide-induced mouse model of Alzheimer's disease

Neuroinflammatory responses play a crucial role in the pathogenesis of Alzheimer's disease (AD). Our previous study demonstrated that petroleum ether extracts from Alpiniae Oxyphyllae Fructus(AOF) could attenuate lipopolysaccharide (LPS)-induced learning and memory impairment in mice, which could be associated with its inhibitory effect on neuroinflammation. Therefore, our present study is to investigate the potential therapeutic neuroprotective effects of nootkatone (NKT) on an AD mouse model induced by intracerebroventricular injection of LPS. We found that NKT (10 mg/kg) group showed good performance in behavior experiments including Y-maze test and Morris water maze test. The results of histopathological examination and immunohistochemical analysis showed that LPS induced degeneration of neurons and activation of microglia particularly in hippocampus and NKT (10 mg/kg) reversed these changes. Enzyme linked immunosorbent assay and western blot analysis also demonstrated that the model group had increased expression of IL-1β, IL-6, TNF-α, NLRP3 and NF-κB p65, especially in hippocampus relative to sham-operated group, and NKT (10 mg/kg) decreased the high expression of these inflammatory cytokines. Collectively, these data indicated that LPS-induced learning and memory impairments in mice could be improved by NKT, which was associated with attenuating neuroinflammatory responses. Our study indicated that NKT could act as a potential therapeutic agent for the treatment of neuroinflammation and AD.

Protective effects of Alpinae Oxyphyllae Fructus extracts on lipopolysaccharide-induced animal model of Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Alpinae Oxyphyllae Fructus (AOF) with warming and tonifying the kidney and spleen, anti-salivation, anti-polyuria and anti-diarrhea functions is the dried ripe fruits of Alpinia oxyphylla Miq. (Zingiberaceae). As a traditional Chinese medicine, its application history is very long.

AIMS OF THE STUDY

The purpose of our study is to investigate the effects of different solvent extracts from AOF on lipopolysaccharide (LPS)-induced animal model of Alzheimer's disease (AD) to elucidate the traditional medical theories with modern pharmacological methods and provide a reference for further clarifying its active components and mechanisms.

MATERIALS AND METHODS

The method of stepwise screening was adopted in this paper. The animals were divided into 9 groups, including control (CT) group, model (MD) group, donepezil (DPZ) group, total extract (TT) group, petroleum ether extract (PE) group, chloroform extract (CF) group, ethyl acetate extract (EA) group, n-butanol extract (NB) group and water extract (WT) group. The anti-amnesic effects of different solvent extracts from AOF were measured in LPS-induced memory deficits mice by Y maze test and Morris water maze (MWM) test. Hematoxylin eosin (HE) staining was applied to observe pathological changes in hippocampus and cerebral cortex tissue of different groups. Biochemical indicators including ionized calcium-binding adaptor molecule 1 (IBA-1), interleukin beta 1 (IL-1β), Aβ_1-42 and hyperphosphorylated tau proteins (p-tau) in hippocampus and cortex after treatment with LPS were measured according to the manufacturer's instructions of ELISA kits. HPLC was used to evaluate the major components of different extracts.

RESULTS

It was found that successive intragastric administration of AOF (360 mg/kg) extracts for 14 days showed different degrees of improvement on LPS-induced AD model as measured by Y-maze test, Morris water maze test, and Histopathological examination. Moreover, the results of ELISA suggested petroleum ether (PE) extracts were worth recommending for inhibiting the high level of IBA-1, IL-1β, Aβ_1-42 and p-tau in hippocampus and cortex after treatment with LPS.

CONCLUSIONS

The present study demonstrated for the first time that AOF attenuated LPS-induced learning and memory impairment, which may be associated with its inhibitory effect on neuroinflammation, amyloids-β (Aβ) deposition and p-tau. This research provided a theoretical basis for elucidating the traditional theory of AOF, and was also the stepping stone to the next step.

Postnatal steroids in extreme preterm infants: Intra-tracheal instillation using surfactant as a vehicle

Chronic Lung Disease (CLD) is a common respiratory morbidity in survivors following extreme preterm birth, and is associated with adverse neurodevelopment in the long term. Besides demographics, multiple risk factors are implicated in the pathogenesis of CLD. However, early lung inflammation appears to be the common pathway that leads to the pathological and clinical changes observed in CLD. Postnatal use of systemic steroids has been successful in reducing the incidence of CLD but resulted in unacceptable adverse neurodevelopmental outcomes. The efficacy of inhaled steroids is not yet established. We review the evidence of tracheal instillation of steroids using surfactant as a lipid vehicle, including published data on drug distribution, in vitro physical studies, and clinical trials in animals and human infants.

Inhibition of IκBβ/NFκB signaling prevents LPS-induced IL1β expression without increasing apoptosis in the developing mouse lung

BackgroundThe pro-inflammatory consequences of IL1β expression contribute to the pathogenesis of bronchopulmonary dysplasia. Selectively targeting Lipopolysaccharide (LPS)-induced IκBβ/NFκB signaling attenuates IL1β mRNA expression in macrophages. Whether targeting IκBβ/NFκB signaling affects the anti-apoptotic gene expression, a known consequence of global LPS-induced NFκB inhibition, is unknown.MethodsMacrophages (RAW 264.7, bone marrow-derived macrophage) were assessed for LPS-induced IL1β mRNA/protein expression, anti-apoptotic gene expression, cell viability (trypan blue exclusion), and activation of apoptosis (caspase-3 and PARP cleavage) following pharmacologic and genetic attenuation of IκBβ/NFκB signaling. Expressions of IL1β and anti-apoptotic genes were assessed in endotoxemic newborn mice (P0) with intact (WT), absent (IκBβ KO), and attenuated (IκBβ overexpressing) IκBβ/NFκB signaling.ResultsIn cultured macrophages, pharmacologic and genetic inhibition of LPS-induced IκBβ/NFκB signaling significantly attenuated IL1β mRNA and protein expression. Importantly, targeting IκBβ/NFκB signaling did not attenuate LPS-induced expression of anti-apoptotic genes or result in cell death. In endotoxemic neonatal mice, targeting LPS-induced IκBβ/NFκB signaling significantly attenuated pulmonary IL1β expression without affecting the anti-apoptotic gene expression.ConclusionTargeting IκBβ/NFκB signaling prevents LPS-induced IL1β expression without inducing apoptosis in cultured macrophages and in the lungs of endotoxemic newborn mice. Inhibiting this pathway may prevent inflammatory injury without affecting the protective role of NFκB activity in the developing lung.

Recent advances in our understanding of the mechanisms of late lung development and bronchopulmonary dysplasia

The objective of lung development is to generate an organ of gas exchange that provides both a thin gas diffusion barrier and a large gas diffusion surface area, which concomitantly generates a steep gas diffusion concentration gradient. As such, the lung is perfectly structured to undertake the function of gas exchange: a large number of small alveoli provide extensive surface area within the limited volume of the lung, and a delicate alveolo-capillary barrier brings circulating blood into close proximity to the inspired air. Efficient movement of inspired air and circulating blood through the conducting airways and conducting vessels, respectively, generates steep oxygen and carbon dioxide concentration gradients across the alveolo-capillary barrier, providing ideal conditions for effective diffusion of both gases during breathing. The development of the gas exchange apparatus of the lung occurs during the second phase of lung development-namely, late lung development-which includes the canalicular, saccular, and alveolar stages of lung development. It is during these stages of lung development that preterm-born infants are delivered, when the lung is not yet competent for effective gas exchange. These infants may develop bronchopulmonary dysplasia (BPD), a syndrome complicated by disturbances to the development of the alveoli and the pulmonary vasculature. It is the objective of this review to update the reader about recent developments that further our understanding of the mechanisms of lung alveolarization and vascularization and the pathogenesis of BPD and other neonatal lung diseases that feature lung hypoplasia.

IKKβ Activation in the Fetal Lung Mesenchyme Alters Lung Vascular Development but Not Airway Morphogenesis

In the immature lung, inflammation and injury disrupt the epithelial-mesenchymal interactions required for normal development. Innate immune signaling and NF-κB activation disrupt the normal expression of multiple mesenchymal genes that play a key role in airway branching and alveolar formation. To test the role of the NF-κB pathway specifically in lung mesenchyme, we utilized the mesenchymal Twist2-Cre to drive expression of a constitutively active inhibitor of NF-κB kinase subunit β (IKKβca) mutant in developing mice. Embryonic Twist2-IKKβca mice were generated in expected numbers and appeared grossly normal. Airway branching also appeared normal in Twist2-IKKβca embryos, with airway morphometry, elastin staining, and saccular branching similar to those in control littermates. While Twist2-IKKβca lungs did not contain increased levels of Il1b, we did measure an increased expression of the chemokine-encoding gene Ccl2. Twist2-IKKβca lungs had increased staining for the vascular marker platelet endothelial cell adhesion molecule 1. In addition, type I alveolar epithelial differentiation appeared to be diminished in Twist2-IKKβca lungs. The normal airway branching and lack of Il1b expression may have been due to the inability of the Twist2-IKKβca transgene to induce inflammasome activity. While Twist2-IKKβca lungs had an increased number of macrophages, inflammasome expression remained restricted to macrophages without evidence of spontaneous inflammasome activity. These results emphasize the importance of cellular niche in considering how inflammatory signaling influences fetal lung development.

Loss of TAB3 expression by shRNA exhibits suppressive bioactivity and increased chemical sensitivity of ovarian cancer cell lines via the NF-κB pathway

Ovarian cancer is a leading cause of death among gynaecologic malignancies. Despite many years of research, it still remains sparing in reliable diagnostic markers and methods for early detection and screening. Transforming growth factor β-activated protein kinase 1 (TAK1)-binding protein 3 (TAB3) was initially characterized as an adapter protein essential for TAK1 activation in response to IL-1β or TNFα, however, the physiological role of TAB3 in ovarian cancer tumorigenesis is still not fully understood. In this study, we evaluated the effects of TAB3 on ovarian cancer cell lines. Expressions of TAB3 and PCNA (proliferating cell nuclear antigen) were found to be gradually increased in EOC tissues and cell lines, by western blot analysis and qRT-PCR. Distribution of TAB3 was further analysed by immunohistochemistry. In vitro, knockdown of TAB3 expression in HO8910 or SKOV3 ovarian cancer cells significantly inhibited bioactivity of ovarian cancer cells, including proliferation and cell-cycle distribution, and promoted chemical sensitivity to cisplatin and paclitaxel treatment via inhibiting NF-κB pathways. In conclusion, our study strongly suggests a novel function of TAB3 as an oncogene that could be used as a biomarker for ovarian cancer. It provides a new insight into the potential mechanism for therapeutic targeting, in chemotherapy resistance, common in ovarian cancer.