Interleukin-1 Receptor Antagonist Protects Newborn Mice Against Pulmonary Hypertension

Precision cut lung slices: an integrated ex vivo model for studying lung physiology, pharmacology, disease pathogenesis and drug discovery

Precision Cut Lung Slices (PCLS) have emerged as a sophisticated and physiologically relevant ex vivo model for studying the intricacies of lung diseases, including fibrosis, injury, repair, and host defense mechanisms. This innovative methodology presents a unique opportunity to bridge the gap between traditional in vitro cell cultures and in vivo animal models, offering researchers a more accurate representation of the intricate microenvironment of the lung. PCLS require the precise sectioning of lung tissue to maintain its structural and functional integrity. These thin slices serve as invaluable tools for various research endeavors, particularly in the realm of airway diseases. By providing a controlled microenvironment, precision-cut lung slices empower researchers to dissect and comprehend the multifaceted interactions and responses within lung tissue, thereby advancing our understanding of pulmonary pathophysiology.

Recent progress in neonatal hyperoxic lung injury

With the progress in neonatal intensive care, there has been an increase in the survival rates of premature infants. However, this has also led to an increased incidence of neonatal hyperoxia lung injury and bronchopulmonary dysplasia (BPD), whose pathogenesis is believed to be influenced by various prenatal and postnatal factors, although the exact mechanisms remain unclear. Recent studies suggest that multiple mechanisms might be involved in neonatal hyperoxic lung injury and BPD, with sex also possibly playing an important role, and numerous drugs have been proposed and shown promise for improving the treatment outcomes of hyperoxic lung injury. Therefore, this paper aims to analyze and summarize sex differences in neonatal hyperoxic lung injury, potential pathogenesis and treatment progress to provide new ideas for basic and clinical research in this field.

Pathogenesis and Physiologic Mechanisms of Neonatal Pulmonary Hypertension: Preclinical Studies

Neonatal pulmonary hypertension (PH) is a devastating disorder of the pulmonary vasculature characterized by elevated pulmonary vascular resistance and mean pulmonary arterial pressure. Occurring predominantly because of maldevelopment or maladaptation of the pulmonary vasculature, PH in neonates is associated with suboptimal short-term and long-term outcomes because its pathobiology is unclear in most circumstances, and it responds poorly to conventional pulmonary vasodilators. Understanding the pathogenesis and pathophysiology of neonatal PH can lead to novel strategies and precise therapies. The review is designed to achieve this goal by summarizing pulmonary vascular development and the pathogenesis and pathophysiology of PH associated with maladaptation, bronchopulmonary dysplasia, and congenital diaphragmatic hernia based on evidence predominantly from preclinical studies. We also discuss the pros and cons of and provide future directions for preclinical studies in neonatal PH.

CC chemokines Modulate Immune responses in Pulmonary Hypertension

BACKGROUND

Pulmonary hypertension (PH) represents a progressive condition characterized by the remodeling of pulmonary arteries, ultimately culminating in right heart failure and increased mortality rates. Substantial evidence has elucidated the pivotal role of perivascular inflammatory factors and immune dysregulation in the pathogenesis of PH. Chemokines, a class of small secreted proteins, exert precise control over immune cell recruitment and functionality, particularly with respect to their migration to sites of inflammation. Consequently, chemokines emerge as critical drivers facilitating immune cell infiltration into the pulmonary tissue during inflammatory responses. This review comprehensively examines the significant contributions of CC chemokines in the maintenance of immune cell homeostasis and their pivotal role in regulating inflammatory responses. The central focus of this discussion is directed towards elucidating the precise immunoregulatory actions of CC chemokines concerning various immune cell types, including neutrophils, monocytes, macrophages, lymphocytes, dendritic cells, mast cells, eosinophils, and basophils, particularly in the context of pH processes. Furthermore, this paper delves into an exploration of the underlying pathogenic mechanisms that underpin the development of PH. Specifically, it investigates processes such as cellular pyroptosis, examines the intricate crosstalk between bone morphogenetic protein receptor type 2 (BMPR2) mutations and the immune response, and sheds light on key signaling pathways involved in the inflammatory response. These aspects are deemed critical in enhancing our understanding of the complex pathophysiology of PH. Moreover, this review provides a comprehensive synthesis of findings from experimental investigations targeting immune cells and CC chemokines.

AIM OF REVIEW

In summary, the inquiry into the inflammatory responses mediated by CC chemokines and their corresponding receptors, and their potential in modulating immune reactions, holds promise as a prospective avenue for addressing PH. The potential inhibition of CC chemokines and their receptors stands as a viable strategy to attenuate the inflammatory cascade and ameliorate the pathological manifestations of PH. Nonetheless, it is essential to acknowledge the current state of clinical trials and the ensuing progress, which regrettably appears to be less than encouraging. Substantial hurdles exist in the successful translation of research findings into clinical applications. The intention is that such emphasis could potentially foster the advancement of potent therapeutic agents presently in the process of clinical evaluation. This, in turn, may further bolster the potential for effective management of PH.

Bronchopulmonary dysplasia - associated pulmonary hypertension: An updated review

Bronchopulmonary dysplasia (BPD) is the leading cause of chronic lung disease in infants and the commonest complication of prematurity. Advances in respiratory and overall neonatal care have increased the survival of extremely low gestational age newborns, leading to the continued high incidence of BPD. Pulmonary hypertension (PH) represents the severe form of the pulmonary vascular disease associated with BPD, and affects almost one-third of infants with moderate to severe BPD. PH responds suboptimally to pulmonary vasodilators and increases morbidity and mortality in BPD infants. An up-to-date knowledge of the pathogenesis, pathophysiology, diagnosis, treatment, and outcomes of BPD-PH can be helpful to develop meaningful and novel strategies to improve the outcomes of infants with this disorder. Therefore, our multidisciplinary team has attempted to thoroughly review and summarize the latest advances in BPD-PH in preventing and managing this morbid lung disorder of preterm infants.

Perspectives on precision cut lung slices-powerful tools for investigation of mechanisms and therapeutic targets in lung diseases

Precision cut lung slices (PCLS) have emerged as powerful experimental tools for respiratory research. Pioneering studies using mouse PCLS to visualize intrapulmonary airway contractility have been extended to pulmonary arteries and for assessment of novel bronchodilators and vasodilators as therapeutics. Additional disease-relevant outcomes, including inflammatory, fibrotic, and regenerative responses, are now routinely measured in PCLS from multiple species, including humans. This review provides an overview of established and innovative uses of PCLS as an intermediary between cellular and organ-based studies and focuses on opportunities to increase their application to investigate mechanisms and therapeutic targets to oppose excessive airway contraction and fibrosis in lung diseases.

The Role of the Interleukin-1 Family in Complications of Prematurity

Preterm birth is a major contributor to neonatal morbidity and mortality. Complications of prematurity such as bronchopulmonary dysplasia (BPD, affecting the lung), pulmonary hypertension associated with BPD (BPD-PH, heart), white matter injury (WMI, brain), retinopathy of prematurity (ROP, eyes), necrotizing enterocolitis (NEC, gut) and sepsis are among the major causes of long-term morbidity in infants born prematurely. Though the origins are multifactorial, inflammation and in particular the imbalance of pro- and anti-inflammatory mediators is now recognized as a key driver of the pathophysiology underlying these illnesses. Here, we review the involvement of the interleukin (IL)-1 family in perinatal inflammation and its clinical implications, with a focus on the potential of these cytokines as therapeutic targets for the development of safe and effective treatments for early life inflammatory diseases.

Interleukin-1: an important target for perinatal neuroprotection?

Perinatal inflammation is a significant risk factor for lifelong neurodevelopmental impairments such as cerebral palsy. Extensive clinical and preclinical evidence links the severity and pattern of perinatal inflammation to impaired maturation of white and grey matters and reduced brain growth. Multiple pathways are involved in the pathogenesis of perinatal inflammation. However, studies of human and experimental perinatal encephalopathy have demonstrated a strong causative link between perinatal encephalopathy and excessive production of the pro-inflammatory effector cytokine interleukin-1. In this review, we summarize clinical and preclinical evidence that underpins interleukin-1 as a critical factor in initiating and perpatuating systemic and central nervous system inflammation and subsequent perinatal brain injury. We also highlight the important role of endogenous interleukin-1 receptor antagonist in mitigating interleukin-1-driven neuroinflammation and tissue damage, and summarize outcomes from clinical and mechanistic animal studies that establish the commercially available interleukin-1 receptor antagonist, anakinra, as a safe and effective therapeutic intervention. We reflect on the evidence supporting clinical translation of interleukin-1 receptor antagonist for infants at the greatest risk of perinatal inflammation and impaired neurodevelopment, and suggest a path to advance interleukin-1 receptor antagonist along the translational path for perinatal neuroprotection.

Application of Precision-Cut Lung Slices as an In Vitro Model for Research of Inflammatory Respiratory Diseases

The leading cause of many respiratory diseases is an ongoing and progressive inflammatory response. Traditionally, inflammatory lung diseases were studied primarily through animal models, cell cultures, and organoids. These technologies have certain limitations, despite their great contributions to the study of respiratory diseases. Precision-cut lung slices (PCLS) are thin, uniform tissue slices made from human or animal lung tissue and are widely used extensively both nationally and internationally as an in vitro organotypic model. Human lung slices bridge the gap between in vivo and in vitro models, and they can replicate the living lung environment well while preserving the lungs' basic structures, such as their primitive cells and trachea. However, there is no perfect model that can completely replace the structure of the human lung, and there is still a long way to go in the research of lung slice technology. This review details and analyzes the strengths and weaknesses of precision lung slices as an in vitro model for exploring respiratory diseases associated with inflammation, as well as recent advances in this field.

Fetal growth restriction and neonatal-pediatric lung diseases: Vascular mechanistic links and therapeutic directions

Bronchopulmonary dysplasia (BPD) is the most common respiratory sequela of prematurity, and infants born with fetal growth restriction (FGR) are disproportionately represented in BPD statistics, as factors which affect somatic growth may also affect pulmonary growth. Effects of in-utero hypoxia underlying FGR on lung parenchymal architecture predisposing to BPD are well documented, but the pulmonary vascular constructs are not well appreciated. Disruption of angiogenesis during critical periods of lung growth impairs alveolarization, contributing to BPD pathogenesis. Pulmonary artery thickness/stiffness has been noted in FGR in the initial postnatal weeks, and also in well-grown infants with established BPD. The lack of waveform cushioning by the major arteries exposes the pulmonary resistance vessels to higher pulsatile stress, thereby accelerating microvascular disease. Reactive oxygen species, increased sympathetic activity and endothelial dysfunction are common mediators in FGR and BPD; each putative targets for prevention and/or therapeutics using interleukin (IL)-1 receptor antagonist (IL-1Ra), melatonin or inhibition of renin-angiotensin-aldosterone system. While BPD is the archetypal respiratory disease of infancy, effects of FGR on pulmonary function are long-term, extending well into childhood. This narrative links FGR in very/extremely preterm infants with BPD through the vascular affliction as a mechanistic and potentially, therapeutic pathway. Our objectives were to depict the burden of disease for FGR and BPD amongst preterm infants, portray vascular involvement in the placenta in FGR and BPD cohorts, provide high resolution vascular ultrasound information in both cohorts with a view to address therapeutic relevance, and lastly, link this information with paediatric age-group lung diseases.

Novel hub genes associated with pulmonary artery remodeling in pulmonary hypertension

Pulmonary hypertension (PH) is a life-threatening disease with complex pathogenesis. According to etiology, PH is divided into five major groups in clinical classification. However, pulmonary artery (PA) remodeling is their common feature, in addition to bone morphogenetic protein receptor type 2; it is elusive whether there are other novel common genes and similar underlying mechanisms. To identify novel common hub genes involved in PA remodeling at different PH groups, we analyzed mRNA-Seq data located in the general gene expression profile GSE130391 utilizing bioinformatics technology. This database contains PA samples from different PH groups of hospitalized patients with chronic thromboembolic pulmonary hypertension (CTEPH), idiopathic pulmonary artery hypertension (IPAH), and PA samples from organ donors without known pulmonary vascular diseases as control. We screened 22 hub genes that affect PA remodeling, most of which have not been reported in PH. We verified the top 10 common hub genes in hypoxia with Sugen-induced PAH rat models by qRT-PCR. The three upregulated candidate genes are WASF1, ARHGEF1 and RB1 and the seven downregulated candidate genes are IL1R1, RHOB, DAPK1, TNFAIP6, PKN1, PLOD2, and MYOF. WASF1, ARHGEF1, and RB1 were upregulated significantly in hypoxia with Sugen-induced PAH, while IL1R1, DAPK1, and TNFA1P6 were upregulated significantly in hypoxia with Sugen-induced PAH. The DEGs detected by mRNA-Seq in hospitalized patients with PH are different from those in animal models. This study will provide some novel target genes to further study PH mechanisms and treatment.

Murine Double Hit Model for Neonatal Cardiopulmonary Diseases: Bronchopulmonary Dysplasia (BPD) and Pulmonary Hypertension Associated with BPD

Bronchopulmonary dysplasia (BPD) and pulmonary hypertension associated with BPD (BPD-PH) are of multifactorial origin and share common risk factors. Most murine models of BPD expose newborn pups to only one of these risk factors-more commonly postnatal hyperoxia-thereby mimicking the vital increased fraction of inspired oxygen (FiO2) that preterm infants in neonatal intensive care units often require. To improve representation of the multifactorial origins of BPD and BPD-PH, we established a double hit model, combining antenatal systemic inflammation followed by postnatal hyperoxia. On embryonic day 14, pups are exposed to systemic maternal inflammation via a single intraperitoneal injection of 150 µg/kg of lipopolysaccharide to the dam. Within 24 h after birth, pups and dams are randomized and exposed to gas with either an FiO2 of 0.21 (room air) or 0.65 (hyperoxia 65%). In our BPD and BPD-PH double hit model, we can obtain multiple readouts from individual pups that include echocardiography, lung histology and immunohistochemistry, ex vivo X-ray micro computed tomography, and pulmonary and plasmatic immunity by RNA, protein, or flow cytometry. This protocol was validated in: Sci Transl Med (2022), DOI: 10.1126/scitranslmed.aaz8454 Graphical abstract Figure 1. Murine double hit model of cardiopulmonary disease. On embryonic day (E)14, pups are exposed to systemic maternal inflammation via a single intraperitoneal injection of 150 µg/kg lipopolysaccharide to the dam. Within 24 h after birth, pups and dams are randomized to be exposed to gas with either a fraction of inspired oxygen (FiO ₂ ) of 0.21 (air; 21% O ₂ ) or 0.65 (hyperoxia; 65% O ₂ ) for a maximum of 28 days. According to the murine stage of lung development ( Schittny, 2017 ), experimental endpoints include postnatal day (D)3, D5, D14, D28, and D60.

Anakinra Pilot - a clinical trial to demonstrate safety, feasibility and pharmacokinetics of interleukin 1 receptor antagonist in preterm infants

BACKGROUND

Bronchopulmonary dysplasia (BPD), its complication pulmonary hypertension (BPD-PH) and preterm brain and gut injury lead to significant morbidity and mortality in infants born extremely prematurely. There is extensive evidence that the pro-inflammatory cytokine interleukin 1 (IL-1) plays a key role in the pathophysiology of these illnesses. Two decades of clinical use in paediatric and adult medicine have established an excellent safety and efficacy record for IL-1 blockade with IL-1 receptor antagonist (IL-1Ra, medication name anakinra). Building on robust pre-clinical evidence, the Anakinra Pilot trial aims to demonstrate safety and feasibility of administering anakinra to preterm infants, and to establish pharmacokinetics in this population. Its ultimate goal is to facilitate large studies that will test whether anakinra can ameliorate early-life inflammation, thus alleviating multiple complications of prematurity.

METHODS AND ANALYSIS

Anakinra Pilot is an investigator-initiated, single arm, safety and feasibility dose-escalation trial in extremely preterm infants born between 24 weeks 0 days (240) and 276 weeks of gestational age (GA). Enrolled infants will receive anakinra intravenously over the first 21 days after birth, starting in the first 24 h after birth. In the first phase, dosing is 1 mg/kg every 48 h, and dosage will increase to 1.5 mg/kg every 24 h in the second phase. Initial anakinra dosing was determined through population pharmacokinetic model simulations. During the study, there will be a interim analysis to confirm predictions before undertaking dose assessment. Anakinra therapy will be considered safe if the frequency of adverse outcomes/events does not exceed that expected in infants born at 240-276 weeks GA.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/, identifier NCT05280340.

Oxygen toxicity: cellular mechanisms in normobaric hyperoxia

In clinical settings, oxygen therapy is administered to preterm neonates and to adults with acute and chronic conditions such as COVID-19, pulmonary fibrosis, sepsis, cardiac arrest, carbon monoxide poisoning, and acute heart failure. In non-clinical settings, divers and astronauts may also receive supplemental oxygen. In addition, under current standard cell culture practices, cells are maintained in atmospheric oxygen, which is several times higher than what most cells experience in vivo. In all the above scenarios, the elevated oxygen levels (hyperoxia) can lead to increased production of reactive oxygen species from mitochondria, NADPH oxidases, and other sources. This can cause cell dysfunction or death. Acute hyperoxia injury impairs various cellular functions, manifesting ultimately as physiological deficits. Chronic hyperoxia, particularly in the neonate, can disrupt development, leading to permanent deficiencies. In this review, we discuss the cellular activities and pathways affected by hyperoxia, as well as strategies that have been developed to ameliorate injury.

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.

Interleukin-35 ameliorates cardiovascular disease by suppressing inflammatory responses and regulating immune homeostasis

The immune response is of great significance in the initiation and progression of a diversity of cardiovascular diseases involving pro-and anti-inflammatory cytokines. Interleukin-35 (IL-35), a cytokine of the interleukin-12 family, is a novel anti-inflammation and immunosuppressive cytokine, maintaining inflammatory suppression and regulating immune homeostasis. The role of IL-35 in cardiovascular diseases (CVDs) has aroused enthusiastic attention, a diversity of experimental or clinical evidence has indicated that IL-35 potentially has a pivot role in protecting against cardiovascular diseases, especially atherosclerosis and myocarditis. In this review, we initiate an overview of the relationship between Interleukin-35 and cardiovascular diseases, including atherosclerosis, acute coronary syndrome, pulmonary hypertension, abdominal aortic aneurysm, heart failure, myocardial ischemia-reperfusion, aortic dissection and myocarditis. Although the specific molecular mechanisms entailing the protective effects of IL-35 remain an unsolved issue, targeted therapies with IL-35 might provide a promising and effective solution to prevent and cure cardiovascular diseases.

Caspase-8 Promotes Pulmonary Hypertension by Activating Macrophage-Associated Inflammation and IL-1β (Interleukin 1β) Production

BACKGROUND

Macrophages are involved in the pathogenesis of pulmonary arterial hypertension (PAH). Caspase-8, an apical component of cell death pathways, is significantly upregulated in macrophages of PAH animal models. However, its role in PAH remains unclear. Caspase-8 plays a critical role in regulating inflammatory responses via inflammasome activation, cell death, and cytokine induction. This study investigated the mechanism of regulation of IL-1β (interleukin 1β) activation in macrophages by caspase-8.

METHODS

A hypoxia + SU5416-induced PAH mouse model and monocrotaline-induced rat model of PAH were constructed and the role of caspase-8 was analyzed.

RESULTS

Caspase-8 and cleaved-caspase-8 were significantly upregulated in the lung tissues of SU5416 and hypoxia-treated PAH mice and monocrotaline-treated rats. Pharmacological inhibition of caspase-8 alleviated PAH compared with wild-type mice, observed as a significant reduction in right ventricular systolic pressure, ratio of right ventricular wall to left ventricular wall plus ventricular septum, pulmonary vascular media thickness, and pulmonary vascular muscularization; caspase-8 ablated mice also showed significant remission. Mechanistically, increased proliferation of pulmonary arterial smooth muscle cellss is closely associated with activation of the NLRP3 (NOD [nucleotide oligomerization domain]-, LRR [leucine-rich repeat]-, and PYD [pyrin domain]-containing protein 3) inflammasome and the IL-1β signaling pathway. Although caspase-8 did not affect extracellular matrix synthesis, it promoted inflammatory cell infiltration and pulmonary arterial smooth muscle cell proliferation via NLRP3/IL-1β activation during the development stage of PAH.

CONCLUSIONS

Taken together, our study suggests that macrophage-derived IL-1β via caspase-8-dependent canonical inflammasome is required for macrophages to play a pathogenic role in pulmonary perivascular inflammation.

Moving Bronchopulmonary Dysplasia Research from the Bedside to the Bench

Although advances in the respiratory management of extremely preterm infants have led to improvements in survival, this progress has not yet extended to a reduction in the incidence of bronchopulmonary dysplasia (BPD). BPD is a complex multifactorial condition that primarily occurs due to disturbances in the regulation of normal pulmonary airspace and vascular development. Preterm birth and exposure to invasive mechanical ventilation also compromises large airway development, leading to significant morbidity and mortality. Although both predisposing and protective genetic and environmental factors have been frequently described in the clinical literature, these findings have had limited impact on the development of effective therapeutic strategies. This gap is likely because the molecular pathways that underlie these observations are yet not fully understood, limiting the ability of researchers to identify novel treatments that can preserve normal lung development and/or enhance cellular repair mechanisms. In this review article, we will outline various well-established clinical observations whilst identifying key knowledge gaps that need to be filled with carefully designed pre-clinical experiments. We will address these issues by discussing controversial topics in the pathophysiology, the pathology and the treatment of BPD, including an evaluation of existing animal models that have been used to answer important questions.

Stem-Cell Therapy for Bronchopulmonary Dysplasia (BPD) in Newborns

Premature newborns are at a higher risk for the development of respiratory distress syndrome (RDS), acute lung injury (ALI) associated with lung inflammation, disruption of alveolar structure, impaired alveolar growth, lung fibrosis, impaired lung angiogenesis, and development of bronchopulmonary dysplasia (BPD) with severe long-term developmental adverse effects. The current therapy for BPD is limited to supportive care including high-oxygen therapy and pharmacotherapy. Recognizing more feasible treatment options to improve lung health and reduce complications associated with BPD is essential for improving the overall quality of life of premature infants. There is a reduction in the resident stem cells in lungs of premature infants with BPD, which strongly suggests a critical role of stem cells in BPD pathogenesis; this warrants the exploration of the potential therapeutic use of stem-cell therapy. Stem-cell-based therapies have shown promise for the treatment of many pathological conditions including acute lung injury and BPD. Mesenchymal stem cells (MSCs) and MSC-derived extracellular vesicles (EVs) including exosomes are promising and effective therapeutic modalities for the treatment of BPD. Treatment with MSCs and EVs may help to reduce lung inflammation, improve pulmonary architecture, attenuate pulmonary fibrosis, and increase the survival rate.

Type 2 immune polarization is associated with cardiopulmonary disease in preterm infants

Postnatal maturation of the immune system is poorly understood, as is its impact on illnesses afflicting term or preterm infants, such as bronchopulmonary dysplasia (BPD) and BPD-associated pulmonary hypertension. These are both cardiopulmonary inflammatory diseases that cause substantial mortality and morbidity with high treatment costs. Here, we characterized blood samples collected from 51 preterm infants longitudinally at five time points, 20 healthy term infants at birth and age 3 to 16 weeks, and 5 healthy adults. We observed strong associations between type 2 immune polarization in circulating CD3⁺CD4⁺ T cells and cardiopulmonary illness, with odds ratios up to 24. Maternal magnesium sulfate therapy, delayed hepatitis B vaccination, and increasing fetal, but not maternal, chorioamnionitis severity were associated with attenuated type 2 polarization. Blocking type 2 mediators such as interleukin-4 (IL-4), IL-5, IL-13, or signal transducer and activator of transcription 6 (STAT6) in murine neonatal cardiopulmonary disease in vivo prevented changes in cell type composition, increases in IL-1β and IL-13, and losses of pulmonary capillaries, but not gains in larger vessels. Thereby, type 2 blockade ameliorated lung inflammation, protected alveolar and vascular integrity, and confirmed the pathological impact of type 2 cytokines and STAT6. In-depth flow cytometry and single-cell transcriptomics of mouse lungs further revealed complex associations between immune polarization and cardiopulmonary disease. Thus, this work advances knowledge on developmental immunology and its impact on early life disease and identifies multiple therapeutic approaches that may relieve inflammation-driven suffering in the youngest patients.

Postoperative Pulmonary Hemodynamics and Systemic Inflammatory Response in Pediatric Patients Undergoing Surgery for Congenital Heart Defects

There is scarce information about the relationships between postoperative pulmonary hemodynamics, inflammation, and outcomes in pediatric patients with congenital cardiac communications undergoing surgery. We prospectively studied 40 patients aged 11 (8–17) months (median with interquartile range) with a preoperative mean pulmonary arterial pressure of 48 (34–54) mmHg who were considered to be at risk for postoperative pulmonary hypertension. The immediate postoperative pulmonary/systemic mean arterial pressure ratio (PAP/SAP_IPO, mean of first 4 values obtained in the intensive care unit, readings at 2-hour intervals) was correlated directly with PAP/SAP registered in the surgical room just after cardiopulmonary bypass (r = 0.68, p < 0.001). For the entire cohort, circulating levels of 15 inflammatory markers changed after surgery. Compared with patients with PAP/SAP_IPO ≤ 0.40 (n = 22), those above this level (n = 18) had increased pre- and postoperative serum levels of granulocyte colony-stimulating factor (p = 0.040), interleukin-1 receptor antagonist (p = 0.020), interleukin-6 (p = 0.003), and interleukin-21 (p = 0.047) (panel for 36 human cytokines) and increased mean platelet volume (p = 0.018). Using logistic regression analysis, a PAP/SAP_IPO > 0.40 and a heightened immediate postoperative serum level of macrophage migration inhibitory factor (quartile analysis) were shown to be predictive of significant postoperative cardiopulmonary events (respective hazard ratios with 95% CIs, 5.07 (1.10–23.45), and 3.29 (1.38–7.88)). Thus, the early postoperative behavior of the pulmonary circulation and systemic inflammatory response are closely related and can be used to predict outcomes in this population.

Innovative Anti-Inflammatory and Pro-resolving Strategies for Pulmonary Hypertension: High Blood Pressure Research Council of Australia Award 2019

Pulmonary hypertension is a rare, ostensibly incurable, and etiologically diverse disease with an unacceptably high 5-year mortality rate (≈50%), worse than many cancers. Irrespective of pathogenic origin, dysregulated immune processes underlie pulmonary hypertension pathobiology, particularly pertaining to pulmonary vascular remodeling. As such, a variety of proinflammatory pathways have been mooted as novel therapeutic targets. One such pathway involves the family of innate immune regulators known as inflammasomes. In addition, a new and emerging concept is differentiating between anti-inflammatory approaches versus those that promote pro-resolving pathways. This review will briefly introduce inflammasomes and examine recent literature concerning their role in pulmonary hypertension. Moreover, it will explore the difference between inflammation-suppressing and pro-resolution approaches and how this links to inflammasomes. Finally, we will investigate new avenues for targeting inflammation in pulmonary hypertension via more targeted anti-inflammatory or inflammation resolving strategies.

miR-122-5p downregulation attenuates lipopolysaccharide-induced acute lung injury by targeting IL1RN

MicroRNAs (miRs) and inflammatory cytokines can induce acute lung injury (ALI), which can develop into acute respiratory distress syndrome in severe cases. Previous research has revealed that miR-122-5p participates in the development of ALI, and that its expression is positively associated with ALI. However, the mechanism by which miR-122-5p contributes to ALI remains to be determined. In the current study, TargetScan and dual luciferase reporter gene assays were used to confirm that IL-1 receptor antagonist (IL1RN) was a target of miR-122-5p. Subsequently, by referring to previous literature, a lipopolysaccharide (LPS)-induced ALI cell model was established. A549 cells were transfected with mimic control or miR-122-5p mimics for 24 h, and 10 µg LPS was used to treat the transfected cells for 12 h. The results revealed that miR-122-5p mimics decreased cell viability and promoted apoptosis. Lactate dehydrogenase (LDH) release assays indicated that miR-122-5p mimics increased LDH release. ELISA demonstrated that miR-122-5p mimics promoted TNF-α, IL-1β and IL-6 expression levels. A549 cells were transfected with inhibitor control, miR-122-5p inhibitor, miR-122-5p inhibitor + control-small interfering (si)RNA or miR-122-5p inhibitor + IL1RN-siRNA for 24 h, after which the cells were treated with 10 µg LPS for 12 h. The results revealed that the effects of the miR-122-5p inhibitor were the opposite of those of the miR-122-5p mimic. All the effects of miR-122-5p inhibitor on LPS-treated A549 cells were significantly reversed by IL1RN-siRNA. Overall, the results highlighted miR-122-5p as a potential novel target for the treatment of ALI.

Interleukin-1β in Multifactorial Hypertension: Inflammation, Vascular Smooth Muscle Cell and Extracellular Matrix Remodeling, and Non-Coding RNA Regulation

The biological activities of interleukins, a group of circulating cytokines, are linked to the immuno-pathways involved in many diseases. Mounting evidence suggests that interleukin-1β (IL-1β) plays a significant role in the pathogenesis of various types of hypertension. In this review, we summarized recent findings linking IL-1β to systemic arterial hypertension, pulmonary hypertension, and gestational hypertension. We also outlined the new progress in elucidating the potential mechanisms of IL-1β in hypertension, focusing on it's regulation in inflammation, vascular smooth muscle cell function, and extracellular remodeling. In addition, we reviewed recent studies that highlight novel findings examining the function of non-coding RNAs in regulating the activity of IL-1β and its associated proteins in the setting of hypertension. The information collected in this review provides new insights into understanding the pathogenesis of hypertension and could lead to the discovery of new anti-hypertensive therapies to combat this highly prevalent disease.

Bronchopulmonary Dysplasia and Pulmonary Hypertension. The Role of Smooth Muscle adh5

Bronchopulmonary dysplasia (BPD) is characterized by alveolar simplification, airway hyperreactivity, and pulmonary hypertension. In our BPD model, we have investigated the metabolism of the bronchodilator and pulmonary vasodilator GSNO (S-nitrosoglutathione). We have shown the GSNO catabolic enzyme encoded by adh5 (alcohol dehydrogenase-5), GSNO reductase, is epigenetically upregulated in hyperoxia. Here, we investigated the distribution of GSNO reductase expression in human BPD and created an animal model that recapitulates the human data. Blinded comparisons of GSNO reductase protein expression were performed in human lung tissues from infants and children with and without BPD. BPD phenotypes were evaluated in global (adh5^-/-) and conditional smooth muscle (smooth muscle/adh5^-/-) adh5 knockout mice. GSNO reductase was prominently expressed in the airways and vessels of human BPD subjects. Compared with controls, expression was greater in BPD smooth muscle, particularly in vascular smooth muscle (2.4-fold; P = 0.003). The BPD mouse model of neonatal hyperoxia caused significant alveolar simplification, airway hyperreactivity, and right ventricular and vessel hypertrophy. Global adh5^-/- mice were protected from all three aspects of BPD, whereas smooth muscle/adh5^-/- mice were only protected from pulmonary hypertensive changes. These data suggest adh5 is required for the development of BPD. Expression in the pulmonary vasculature is relevant to the pathophysiology of BPD-associated pulmonary hypertension. GSNO-mimetic agents or GSNO reductase inhibitors, both of which are currently in clinical trials for other conditions, could be considered for further study in BPD.

Prenatal Maternal Lipopolysaccharide and Mild Newborn Hyperoxia Increase Intrapulmonary Airway but Not Vessel Reactivity in a Mouse Model

Maternal infection is a risk for preterm delivery. Preterm newborns often require supplemental oxygen to treat neonatal respiratory distress. Newborn hyperoxia exposure is associated with airway and vascular hyperreactivity, while the complications of maternal infection are variable. In a mouse model of prenatal maternal intraperitoneal lipopolysaccharide (LPS, embryonic day 18) with subsequent newborn hyperoxia (40% oxygen × 7 days) precision-cut living lung slices were used to measure intrapulmonary airway and vascular reactivity at 21 days of age. Hyperoxia increased airway reactivity to methacholine compared to room air controls. Prenatal maternal LPS did not alter airway reactivity in room air. Combined maternal LPS and hyperoxia exposures increased airway reactivity vs. controls, although maximal responses were diminished compared to hyperoxia alone. Vessel reactivity to serotonin did not significantly differ in hyperoxia or room air; however, prenatal maternal LPS appeared to attenuate vessel reactivity in room air. Following room air recovery, LPS with hyperoxia lungs displayed upregulated inflammatory and fibrosis genes compared to room air saline controls (TNFαR1, iNOS, and TGFβ). In this model, mild newborn hyperoxia increases airway but not vessel reactivity. Prenatal maternal LPS did not further increase hyperoxic airway reactivity. However, inflammatory genes remain upregulated weeks after recovery from maternal LPS and newborn hyperoxia exposures.

Cytokines, Chemokines, and Inflammation in Pulmonary Arterial Hypertension

According to the World Symposium Pulmonary Hypertension (WSPH) classification, pulmonary hypertension (PH) is classified into five categories based on etiology. Among them, Group 1 pulmonary arterial hypertension (PAH) disorders are rare but progressive and often, fatal despite multiple approved treatments. Elevated pulmonary arterial pressure in patients with WSPH Group 1 PAH is mainly caused by increased pulmonary vascular resistance (PVR), due primarily to sustained pulmonary vasoconstriction and excessive obliterative pulmonary vascular remodeling. Growing evidence indicates that inflammation plays a critical role in the development of pulmonary vascular remodeling associated with PAH. While the role of auto-immunity is unclear, infiltration of inflammatory cells in and around vascular lesions, including T- and B-cells, dendritic cells, macrophages, and mast cells have been observed in PAH patients. Serum and plasma levels of chemokines, cytokines, and autoantibodies are also increased in PAH patients; some of these circulating molecules are correlated with disease severity and survival. Preclinical experiments have reported a key role of the inflammation in PAH pathophysiology in vivo. Importantly, anti-inflammatory and immunosuppressive agents have further exhibited therapeutic effects. The present chapter reviews published experimental and clinical evidence highlighting the canonical role of inflammation in the pathogenesis of PAH and as a major target for the development of anti-inflammatory therapies in patients with PAH.

T Lymphocytes, Multi-Omic Interactions and Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) remains a significant clinical challenge in neonatal medicine. BPD is clearly a multifactorial disease with numerous antenatal and postnatal components influencing lung development. Extremely immature infants are born in the late canalicular or early saccular stage and usually receive intensive care until the early alveolar stage of lung development, resulting in varying magnitudes of impairment of alveolar septation, lung fibrosis, and abnormal vascular development. The interactions between T lymphocytes, the genome and the epigenome, the microbiome and the metabolome, as well as nutrition and therapeutic interventions such as the exposure to oxygen, volutrauma, antibiotics, corticosteroids, caffeine and omeprazole, play an important role in pathogenesis and disease progression. While our general understanding of these interactions thanks to basic research is improving, this knowledge is yet to be translated into comprehensive prevention and clinical management strategies for the benefit of preterm infants developing BPD and later during infancy and childhood suffering from the disease itself and its sequelae. In this review, we summarise existing evidence on the interplay between T lymphocytes, lung multi-omics and currently used therapeutic interventions in BPD, and highlight avenues for potential future immunology related research in the field.

T. gondii infection induces IL-1R dependent chronic cachexia and perivascular fibrosis in the liver and skeletal muscle

Cachexia is a progressive muscle wasting disease that contributes to death in a wide range of chronic diseases. Currently, the cachexia field lacks animal models that recapitulate the long-term kinetics of clinical disease, which would provide insight into the pathophysiology of chronic cachexia and a tool to test therapeutics for disease reversal. Toxoplasma gondii (T. gondii) is a protozoan parasite that uses conserved mechanisms to infect rodents and human hosts. Infection is lifelong and has been associated with chronic weight loss and muscle atrophy in mice. We have recently shown that T. gondii-induced muscle atrophy meets the clinical definition of cachexia. Here, the longevity of the T. gondii-induced chronic cachexia model revealed that cachectic mice develop perivascular fibrosis in major metabolic organs, including the adipose tissue, skeletal muscle, and liver by 9 weeks post-infection. Development of cachexia, as well as liver and skeletal muscle fibrosis, is dependent on intact signaling through the type I IL-1R receptor. IL-1α is sufficient to activate cultured fibroblasts and primary hepatic stellate cells (myofibroblast precursors in the liver) in vitro, and IL-1α is elevated in the sera and liver of cachectic, suggesting a mechanism by which chronic IL-1R signaling could be leading to cachexia-associated fibrosis.

Interactive and independent effects of early lipopolysaccharide and hyperoxia exposure on developing murine lungs

Bronchopulmonary dysplasia (BPD)-associated pulmonary hypertension (PH) is a chronic infantile lung disease that lacks curative therapies. Infants with BPD-associated PH are often exposed to hyperoxia and additional insults such as sepsis that contribute to disease pathogenesis. Animal models that simulate these scenarios are necessary to develop effective therapies; therefore, we investigated whether lipopolysaccharide (LPS) and hyperoxia exposure during saccular lung development cooperatively induce experimental BPD-PH in mice. C57BL/6J mice were exposed to normoxia or 70% O₂ (hyperoxia) during postnatal days (PNDs) 1-5 and intraperitoneally injected with varying LPS doses or a vehicle on PNDs 3-5. On PND 14, we performed morphometry, echocardiography, and gene and protein expression studies to determine the effects of hyperoxia and LPS on lung development, vascular remodeling and function, inflammation, oxidative stress, cell proliferation, and apoptosis. LPS and hyperoxia independently and cooperatively affected lung development, inflammation, and apoptosis. Growth rate and antioxidant enzyme expression were predominantly affected by LPS and hyperoxia, respectively, while cell proliferation and vascular remodeling and function were mainly affected by combined exposure to LPS and hyperoxia. Mice treated with lower LPS doses developed adaptive responses and hyperoxia exposure did not worsen their BPD phenotype, whereas those mice treated with higher LPS doses displayed the most severe BPD phenotype when exposed to hyperoxia and were the only group that developed PH. Collectively, our data suggest that an additional insult such as LPS may be necessary for models utilizing short-term exposure to moderate hyperoxia to recapitulate human BPD-PH.

Novel Strategies to Reduce Pulmonary Hypertension in Infants With Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a developmental lung disorder of preterm infants primarily caused by the failure of host defense mechanisms to prevent tissue injury and facilitate repair. This disorder is the most common complication of premature birth, and its incidence remains unchanged over the past few decades. Additionally, BPD increases long-term cardiopulmonary and neurodevelopmental morbidities of preterm infants. Pulmonary hypertension (PH) is a common morbidity of BPD. Importantly, the presence of PH increases both the short- and long-term morbidities and mortality in BPD infants. Further, there are no curative therapies for this complex disease. Besides providing an overview of the pathogenesis and diagnosis of PH associated with BPD, we have attempted to comprehensively review and summarize the current literature on the interventions to prevent and/or mitigate BPD and PH in preclinical studies. Our goal was to provide insight into the therapies that have a high translational potential to meaningfully manage BPD patients with PH.

Emerging Role of the NLRP3 Inflammasome and Interleukin-1β in Neonates

Infection and persistent inflammation have a prominent role in the pathogenesis of brain injury and cerebral palsy, as well as other conditions associated with prematurity such as bronchopulmonary dysplasia. The NLRP3 inflammasome-interleukin (IL)-1β pathway has been extensively studied in adults and pre-clinical models, improving our understanding of innate immunity and offering an attractive therapeutic target that is already contributing to clinical management in many auto-inflammatory disorders. IL-1 blockade has transformed the course and outcome of conditions such as chronic infantile neurological, cutaneous, articular (CINCA/NOMID) syndrome. Inflammasome activation and upregulation has recently been implicated in neonatal brain and lung inflammatory disease and may be a novel therapeutic target.

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

Bronchopulmonary dysplasia (BPD) is the most common cause of morbidity and mortality in preterm infants. A key histopathological feature of BPD is stunted late lung development, where the process of alveolarization-the generation of alveolar gas exchange units-is impeded, through mechanisms that remain largely unclear. As such, there is interest in the clarification both of the pathomechanisms at play in affected lungs, and the mechanisms of de novo alveoli generation in healthy, developing lungs. A better understanding of normal and pathological alveolarization might reveal opportunities for improved medical management of affected infants. Furthermore, disturbances to the alveolar architecture are a key histopathological feature of several adult chronic lung diseases, including emphysema and fibrosis, and it is envisaged that knowledge about the mechanisms of alveologenesis might facilitate regeneration of healthy lung parenchyma in affected patients. To this end, recent efforts have interrogated clinical data, developed new-and refined existing-in vivo and in vitro models of BPD, have applied new microscopic and radiographic approaches, and have developed advanced cell-culture approaches, including organoid generation. Advances have also been made in the development of other methodologies, including single-cell analysis, metabolomics, lipidomics, and proteomics, as well as the generation and use of complex mouse genetics tools. The objective of this review is to present advances made in our understanding of the mechanisms of lung alveolarization and BPD over the period 1 January 2017-30 June 2019, a period that spans the 50th anniversary of the original clinical description of BPD in preterm infants.