Placenta-derived SOD3 deletion impairs maternal behavior via alterations in FGF/FGFR-prolactin signaling axis.

Offspring growth requires establishing maternal behavior associated with the maternal endocrine profile. Placentae support the adaptations of the mother, producing bioactive molecules that affect maternal organs. We recently reported that placentae produce superoxide dismutase 3 (SOD3) that exerts sustained effects on the offspring liver via epigenetic modifications. Here, we demonstrate that placenta-specific Sod3 knockout (Sod3-/-) dams exhibited impaired maternal behavior and decreased prolactin levels. Most fibroblast growth factor (FGF)-regulated pathways were downregulated in the pituitary tissues from Sod3-/- dams. FGF1-, FGF2-, and FGF4-induced prolactin expression and signaling via the phosphoinositide 3-kinase (PI3K)-phospholipase C-γ1 (PLCγ1)-protein kinase-Cδ (PKC)δ axis were reduced in primary pituitary cells from Sod3-/- dams. Mechanistically, FGF1/FGF receptor (FGFR)2 expressions were inhibited by the suppression of the ten-eleven translocation (TET)/isocitrate dehydrogenase (IDH)/α-ketoglutarate pathway and DNA demethylation levels at the zinc finger and BTB domain containing 18 (ZBTB18)-targeted promoters of Fgf1/Fgfr2. Importantly, offspring from Sod3-/- dams also showed impaired nurturing behavior to their grandoffspring. Collectively, placenta-derived SOD3 promotes maternal behavior via epigenetic programming of the FGF/FGFR-prolactin axis.

Relationship between Urine Serotonin and Persistent Pulmonary Hypertension of the Newborn.

Urine serotonin (5-HT)/creatinine was lower at day of life 3 in newborns with pulmonary hypertension compared with controls, while the percent change in the 5-HT metabolite, 5-hydroxyindoleacetic acid (5-HIAA)/creatinine increased. We speculate that the changes in 5-HT and 5-HIAA reflect enhanced pulmonary 5-HT uptake and/or metabolism.

Redistribution of SOD3 expression due to R213G polymorphism affects pulmonary interstitial macrophage reprogramming in response to hypoxia.

The extracellular isoform of superoxide dismutase (SOD3) is decreased in patients and animals with pulmonary hypertension (PH). The human R213G single nucleotide polymorphism (SNP) in SOD3 causes its release from tissue extracellular matrix (ECM) into extracellular fluids, without modulating enzyme activity, increasing cardiovascular disease risk in humans and exacerbating chronic hypoxic PH in mice. Given the importance of interstitial macrophages (IM) to PH pathogenesis, this study aimed to determine whether R213G SOD3 increases IM accumulation and alters IM reprogramming in response to hypoxia. R213G mice and wild-type (WT) controls were exposed to hypobaric hypoxia for 4 or 14 days compared to normoxia. Flow cytometry demonstrated a transient increase in IMs at day 4 in both strains. Contrary to our hypothesis, the R213G SNP did not augment IM accumulation. To determine strain differences in the IM reprogramming response to hypoxia, we performed RNAsequencing on IMs isolated at each time point. We found that IMs from R213G mice exposed to hypoxia activated ECM-related pathways and a combination of alternative macrophage and proinflammatory signaling. Furthermore, when compared to WT responses, IMs from R213G mice lacked metabolic remodeling and demonstrated a blunted anti-inflammatory response between the early (day 4) and later (day 14) time points. We confirmed metabolic responses using Agilent Seahorse assays whereby WT, but not R213G, IMs upregulated glycolysis at day 4 that returned to baseline at day 14. Finally, we identify differential regulation of several redox-sensitive upstream regulators that could be investigated in future studies.

Activation of Platelets and the Complement System in Mice with Schistosoma-Induced Pulmonary Hypertension.

Schistosomiasis-induced pulmonary hypertension (PH) presents a significant global health burden, yet the underlying mechanisms remain poorly understood. Here, we investigate the involvement of platelets and the complement system in the initiation events leading to Schistosoma-induced PH. We demonstrate that Schistosoma exposure leads to thrombocytopenia, platelet accumulation in the lung, and platelet activation. Additionally, we observed increased plasma complement anaphylatoxins C3a and C5a, indicative of complement system activation, and elevated platelet expression of C1q, C3, decay activating factor (DAF), and complement C3a and C5a receptors. Our findings suggest the active involvement of platelets in responding to complement system signals induced by Schistosoma exposure and form the basis for future mechanistic studies on how complement may regulate platelet activation and promote the development of Schistosoma-induced PH.

Lung EC-SOD Overexpression Prevents Hypoxia-Induced Platelet Activation and Lung Platelet Accumulation.

Pulmonary hypertension (PH) is a progressive disease marked by pulmonary vascular remodeling and right ventricular failure. Inflammation and oxidative stress are critical in PH pathogenesis, with early pulmonary vascular inflammation preceding vascular remodeling. Extracellular superoxide dismutase (EC-SOD), a key vascular antioxidant enzyme, mitigates oxidative stress and protects against inflammation and fibrosis in diverse lung and vascular disease models. This study utilizes a murine hypobaric hypoxia model to investigate the role of lung EC-SOD on hypoxia-induced platelet activation and platelet lung accumulation, a critical factor in PH-related inflammation. We found that lung EC-SOD overexpression blocked hypoxia-induced platelet activation and platelet accumulation in the lung. Though lung EC-SOD overexpression increased lung EC-SOD content, it did not impact plasma extracellular SOD activity. However, ex vivo, exogenous extracellular SOD treatment specifically blunted convulxin-induced platelet activation but did not blunt platelet activation with thrombin or ADP. Our data identify platelets as a novel target of EC-SOD in response to hypoxia, providing a foundation to advance the understanding of dysregulated redox signaling and platelet activation in PH and other chronic hypoxic lung diseases.

Disruption in glutathione metabolism and altered energy production in the liver and kidney after ischemic acute kidney injury in mice.

Acute kidney injury (AKI) is a systemic disease that affects energy metabolism in various remote organs in murine models of ischemic AKI. However, AKI-mediated effects in the liver have not been comprehensively assessed. After inducing ischemic AKI in 8-10-week-old, male C57BL/6 mice, mass spectrometry metabolomics revealed that the liver had the most distinct phenotype 24 h after AKI versus 4 h and 7 days. Follow up studies with in vivo [13C6]-glucose tracing on liver and kidney 24 h after AKI revealed 4 major findings: (1) increased flux through glycolysis and the tricarboxylic (TCA) cycle in both kidney and liver; (2) depleted hepatic glutathione levels and its intermediates despite unchanged level of reactive oxygen species, suggesting glutathione consumption exceeds production due to systemic oxidative stress after AKI; (3) hepatic ATP depletion despite unchanged rate of mitochondrial respiration, suggesting increased ATP consumption relative to production; (4) increased hepatic and renal urea cycle intermediates suggesting hypercatabolism and upregulation of the urea cycle independent of impaired renal clearance of nitrogenous waste. Taken together, this is the first study to describe the hepatic metabolome after ischemic AKI in a murine model and demonstrates that there is significant liver-kidney crosstalk after AKI.

Lactate produced by alveolar type II cells suppresses inflammatory alveolar macrophages in acute lung injury.

Alveolar inflammation is a hallmark of acute lung injury (ALI), and its clinical correlate is acute respiratory distress syndrome-and it is as a result of interactions between alveolar type II cells (ATII) and alveolar macrophages (AM). In the setting of acute injury, the microenvironment of the intra-alveolar space is determined in part by metabolites and cytokines and is known to shape the AM phenotype. In response to ALI, increased glycolysis is observed in AT II cells, mediated by the transcription factor hypoxia-inducible factor (HIF) 1α, which has been shown to decrease inflammation. We hypothesized that in acute lung injury, lactate, the end product of glycolysis, produced by ATII cells shifts AMs toward an anti-inflammatory phenotype, thus mitigating ALI. We found that local intratracheal delivery of lactate improved ALI in two different mouse models. Lactate shifted cytokine expression of murine AMs toward increased IL-10, while decreasing IL-1 and IL-6 expression. Mice with ATII-specific deletion of Hif1a and mice treated with an inhibitor of lactate dehydrogenase displayed exacerbated ALI and increased inflammation with decreased levels of lactate in the bronchoalveolar lavage fluid; however, all those parameters improved with intratracheal lactate. When exposed to LPS (to recapitulate an inflammatory stimulus as it occurs in ALI), human primary AMs co-cultured with alveolar epithelial cells had reduced inflammatory responses. Taken together, these studies reveal an innate protective pathway, in which lactate produced by ATII cells shifts AMs toward an anti-inflammatory phenotype and dampens excessive inflammation in ALI.

Imaging Reactive Oxygen Radicals in Excised Mouse Lung Trapped by Reaction with Hydroxylamine Probes Using 1 GHz Rapid Scan Electron Paramagnetic Resonance.

PURPOSE: Oxidative stress is proposed to be critical in acute lung disease, but methods to monitor radicals in lungs are lacking. Our goal is to develop low-frequency electron paramagnetic resonance (EPR) methods to monitor radicals that contribute to the disease. PROCEDURES: Free radicals generated in a lipopolysaccharide-induced mouse model of acute respiratory distress syndrome reacted with cyclic hydroxylamines CPH (1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine hydrochloride) and DCP-AM-H (4-acetoxymethoxycarbonyl-1-hydroxy-2,2,5,5-tetramethylpyrrolidine-3-carboxylic acid), which were converted into the corresponding nitroxide radicals, CP• and DCP•. The EPR signals of the nitroxide radicals in excised lungs were imaged with a 1 GHz EPR spectrometer/imager that employs rapid scan technology. RESULTS: The small numbers of nitroxides formed by reaction of the hydroxylamine with superoxide result in low signal-to-noise in the spectra and images. However, since the spectral properties of the nitroxides are known, we can use prior knowledge of the line shape and hyperfine splitting to fit the noisy data, yielding well-defined spectra and images. Two-dimensional spectral-spatial images are shown for lung samples containing (4.5 ± 0.5) ×1014 CP• and (9.9 ± 1.0) ×1014 DCP• nitroxide spins. These results suggest that a probe that accumulates in cells gives a stronger nitroxide signal than a probe that is more easily washed out of cells. CONCLUSION: The nitroxide radicals in excised mouse lungs formed by reaction with hydroxylamine probes CPH and DCP-AM-H can be imaged at 1 GHz.

CNP-miR146a Decreases Inflammation in Murine Acute Infectious Lung Injury.

Acute respiratory distress syndrome (ARDS) has approximately 40% in-hospital mortality, and treatment is limited to supportive care. Pneumonia is the underlying etiology in many cases with unrestrained inflammation central to the pathophysiology. We have previously shown that CNP-miR146a, a radical scavenging cerium oxide nanoparticle (CNP) conjugated to the anti-inflammatory microRNA(miR)-146a, reduces bleomycin- and endotoxin-induced acute lung injury (ALI) by decreasing inflammation. We therefore hypothesized that CNP-miR146a would decrease inflammation in murine infectious ALI. Mice were injured with intratracheal (IT) MRSA or saline followed by treatment with IT CNP-miR146a or saline control. Twenty-four hours post-infection, bronchoalveolar lavage fluid (BALF) and whole lungs were analyzed for various markers of inflammation. Compared to controls, MRSA infection significantly increased proinflammatory gene expression (IL-6, IL-8, TNFα, IL-1ß; p < 0.05), BALF proinflammatory cytokines (IL-6, IL-8, TNFα, IL-1ß; p < 0.01), and inflammatory cell infiltrate (p = 0.03). CNP-miR146a treatment significantly decreased proinflammatory gene expression (IL-6, IL-8, TNFα, IL-1ß; p < 0.05), bronchoalveolar proinflammatory protein leak (IL-6, IL-8, TNFα; p < 0.05), and inflammatory infiltrate (p = 0.01). CNP-miR146a decreases inflammation and improves alveolar-capillary barrier integrity in the MRSA-infected lung and has significant promise as a potential therapeutic for ARDS.

Use of Electron Paramagnetic Resonance (EPR) to Evaluate Redox Status in a Preclinical Model of Acute Lung Injury.

PURPOSE: Patients with hyper- vs. hypo-inflammatory subphenotypes of acute respiratory distress syndrome (ARDS) exhibit different clinical outcomes. Inflammation increases the production of reactive oxygen species (ROS) and increased ROS contributes to the severity of illness. Our long-term goal is to develop electron paramagnetic resonance (EPR) imaging of lungs in vivo to precisely measure superoxide production in ARDS in real time. As a first step, this requires the development of in vivo EPR methods for quantifying superoxide generation in the lung during injury, and testing if such superoxide measurements can differentiate between susceptible and protected mouse strains. PROCEDURES: In WT mice, mice lacking total body extracellular superoxide dismutase (EC-SOD) (KO), or mice overexpressing lung EC-SOD (Tg), lung injury was induced with intraperitoneal (IP) lipopolysaccharide (LPS) (10 mg/kg). At 24 h after LPS treatment, mice were injected with the cyclic hydroxylamines 1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine hydrochloride (CPH) or 4-acetoxymethoxycarbonyl-1-hydroxy-2,2,5,5-tetramethylpyrrolidine-3-carboxylic acid (DCP-AM-H) probes to detect, respectively, cellular and mitochondrial ROS - specifically superoxide. Several probe delivery strategies were tested. Lung tissue was collected up to one hour after probe administration and assayed by EPR. RESULTS: As measured by X-band EPR, cellular and mitochondrial superoxide increased in the lungs of LPS-treated mice compared to control. Lung cellular superoxide was increased in EC-SOD KO mice and decreased in EC-SOD Tg mice compared to WT. We also validated an intratracheal (IT) delivery method, which enhanced the lung signal for both spin probes compared to IP administration. CONCLUSIONS: We have developed protocols for delivering EPR spin probes in vivo, allowing detection of cellular and mitochondrial superoxide in lung injury by EPR. Superoxide measurements by EPR could differentiate mice with and without lung injury, as well as mouse strains with different disease susceptibilities. We expect these protocols to capture real-time superoxide production and enable evaluation of lung EPR imaging as a potential clinical tool for subphenotyping ARDS patients based on redox status.

CNP-miR146a improves outcomes in a two-hit acute- and ventilator-induced lung injury model.

Acute respiratory distress syndrome (ARDS) has high mortality (~40 %) and requires the lifesaving intervention of mechanical ventilation. A variety of systemic inflammatory insults can progress to ARDS, and the inflamed and injured lung is susceptible to ventilator-induced lung injury (VILI). Strategies to mitigate the inflammatory response while restoring pulmonary function are limited, thus we sought to determine if treatment with CNP-miR146a, a conjugate of novel free radical scavenging cerium oxide nanoparticles (CNP) to the anti-inflammatory microRNA (miR)-146a, would protect murine lungs from acute lung injury (ALI) induced with intratracheal endotoxin and subsequent VILI. Lung injury severity and treatment efficacy were evaluated via lung mechanical function, relative gene expression of inflammatory biomarkers, and lung morphometry (stereology). CNP-miR146a reduced the severity of ALI and slowed the progression of VILI, evidenced by improvements in inflammatory biomarkers, atelectasis, gas volumes in the parenchymal airspaces, and the stiffness of the pulmonary system.

Breath analysis by ultra-sensitive broadband laser spectroscopy detects SARS-CoV-2 infection.

Rapid testing is essential to fighting pandemics such as coronavirus disease 2019 (COVID-19), the disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Exhaled human breath contains multiple volatile molecules providing powerful potential for non-invasive diagnosis of diverse medical conditions. We investigated breath detection of SARS-CoV-2 infection using cavity-enhanced direct frequency comb spectroscopy (CE-DFCS), a state-of-the-art laser spectroscopic technique capable of a real-time massive collection of broadband molecular absorption features at ro-vibrational quantum state resolution and at parts-per-trillion volume detection sensitivity. Using a total of 170 individual breath samples (83 positive and 87 negative with SARS-CoV-2 based on reverse transcription polymerase chain reaction tests), we report excellent discrimination capability for SARS-CoV-2 infection with an area under the receiver-operating-characteristics curve of 0.849(4). Our results support the development of CE-DFCS as an alternative, rapid, non-invasive test for COVID-19 and highlight its remarkable potential for optical diagnoses of diverse biological conditions and disease states.

Release of extracellular superoxide dismutase into alveolar fluid protects against acute lung injury and inflammation in Staphylococcus aureus pneumonia.

Acute respiratory distress syndrome (ARDS) remains a significant cause of morbidity and mortality in critically ill patients. Oxidative stress and inflammation play a crucial role in the pathogenesis of ARDS. Extracellular superoxide dismutase (EC-SOD) is abundant in the lung and is an important enzymatic defense against superoxide. Human single-nucleotide polymorphism in matrix binding region of EC-SOD leads to the substitution of arginine to glycine at position 213 (R213G) and results in release of EC-SOD into alveolar fluid, without affecting enzyme activity. We hypothesized that R213G EC-SOD variant protects against lung injury and inflammation via the blockade of neutrophil recruitment in infectious model of methicillin-resistant S. aureus (MRSA) pneumonia. After inoculation with MRSA, wild-type (WT) mice had impaired integrity of alveolar-capillary barrier and increased levels of IL-1ß, IL-6, and TNF-α in the broncho-alveolar lavage fluid (BALF), while infected mice expressing R213G EC-SOD variant maintained the integrity of alveolar-capillary interface and had attenuated levels of proinflammatory cytokines. MRSA-infected mice expressing R213G EC-SOD variant also had attenuated neutrophil numbers in BALF and decreased expression of neutrophil chemoattractant CXCL1 by the alveolar epithelial ATII cells, compared with the infected WT group. The decreased neutrophil numbers in R213G mice were not due to increased rate of apoptosis. Mice expressing R213G variant had a differential effect on neutrophil functionality-the generation of neutrophil extracellular traps (NETs) but not myeloperoxidase (MPO) levels were attenuated in comparison with WT controls. Despite having the same bacterial load in the lung as WT controls, mice expressing R213G EC-SOD variant were protected from extrapulmonary dissemination of bacteria.

Neonatal Selenium Deficiency Decreases Selenoproteins in the Lung and Impairs Pulmonary Alveolar Development.

Decreased selenium (Se) levels during childhood and infancy are associated with worse respiratory health. Se is biologically active after incorporation into Se-containing antioxidant enzymes (AOE) and proteins. It is unknown how decreased maternal Se during pregnancy and lactation impacts neonatal pulmonary selenoproteins, growth, and lung development. Using a model of neonatal Se deficiency that limits Se intake to the dam during pregnancy and lactation, we evaluated which neonatal pulmonary selenoproteins are decreased in both the saccular (postnatal day 0, P0) and early alveolar (postnatal day 7, P7) stages of lung development. We found that Se deficient (SeD) pups weigh less and exhibit impaired alveolar development compared to Se sufficient (SeS) pups at P7. The activity levels of glutathione peroxidase (GPx) and thioredoxin reductase (Txnrd) were decreased at P0 and P7 in SeD lungs compared to SeS lungs. Protein content of GPx1, GPx3 and Txnrd1 were decreased in SeD lungs at P0 and P7, whereas Txnrd2 content was unaltered compared to SeS controls. The expression of NRF-2 dependent genes and several non-Se containing AOE were similar between SeS and SeD lungs. SeD lungs exhibited a decrease in selenoprotein N, an endoplasmic reticulum protein implicated in alveolar development, at both time points. We conclude that exposure to Se deficiency during pregnancy and lactation impairs weight gain and lung growth in offspring. Our data identify multiple selenoproteins in the neonatal lung that are vulnerable to decreased Se intake, which may impact oxidative stress and cell signaling under physiologic conditions as well as after oxidative stressors.

HIF1A-dependent induction of alveolar epithelial PFKFB3 dampens acute lung injury.

Acute lung injury (ALI) is a severe form of lung inflammation causing acute respiratory distress syndrome in patients. ALI pathogenesis is closely linked to uncontrolled alveolar inflammation. We hypothesize that specific enzymes of the glycolytic pathway could function as key regulators of alveolar inflammation. Therefore, we screened isolated alveolar epithelia from mice exposed to ALI induced by injurious ventilation to assess their metabolic responses. These studies pointed us toward a selective role for isoform 3 of the 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3). Pharmacologic inhibition or genetic deletion of Pfkfb3 in alveolar epithelia (Pfkfb3loxP/loxP SPC-ER-Cre+ mice) was associated with profound increases in ALI during injurious mechanical ventilation or acid instillation. Studies in genetic models linked Pfkfb3 expression and function to Hif1a. Not only did intratracheal pyruvate instillation reconstitute Pfkfb3loxP/loxP or Hif1aloxP/loxP SPC-ER-Cre+ mice, but pyruvate was also effective in ALI treatment of wild-type mice. Finally, proof-of-principle studies in human lung biopsies demonstrated increased PFKFB3 staining in injured lungs and colocalized PFKFB3 to alveolar epithelia. These studies reveal a specific role for PFKFB3 in counterbalancing alveolar inflammation and lay the groundwork for novel metabolic therapeutic approaches during ALI.

Serotonin-deficient neonatal mice are not protected against the development of experimental bronchopulmonary dysplasia or pulmonary hypertension.

Serotonin (5-hydroxytryptamine, 5-HT) is a potent pulmonary vasoconstrictor and contributes to high pulmonary vascular resistance in the developing ovine lung. In experimental pulmonary hypertension (PH), pulmonary expression of tryptophan hydroxylase-1 (TPH1), the rate limiting enzyme in 5-HT synthesis, and plasma 5-HT are increased. 5-HT blockade increases pulmonary blood flow and prevents pulmonary vascular remodeling and PH in neonatal models of PH with bronchopulmonary dysplasia (BPD). We hypothesized that neonatal tph1 knock-out (KO) mice would be protected from hypoxia-induced alveolar simplification, decreased vessel density, and PH. Newborn wild-type (WT) and tph1 KO mice were exposed to normoxia or hypoxia for 2 weeks. Normoxic WT and KO mice exhibited similar alveolar development, pulmonary vascular density, right ventricular systolic pressures (RVSPs), and right heart size. Circulating (plasma and platelet) 5-HT decreased in both hypoxia-exposed WT and KO mice. Tph1 KO mice were not protected from hypoxia-induced alveolar simplification, decreased pulmonary vascular density, or right ventricular hypertrophy, but displayed attenuation to hypoxia-induced RVSP elevation compared with WT mice. Tph1 KO neonatal mice are not protected against hypoxia-induced alveolar simplification, reduction in pulmonary vessel density, or RVH. While genetic and pharmacologic inhibition of tph1 has protective effects in adult models of PH, our results suggest that tph1 inhibition would not be beneficial in neonates with PH associated with BPD.

A Protocol for Fabrication and on-Chip Cell Culture to Recreate PAH-Afflicted Pulmonary Artery on a Microfluidic Device.

Pulmonary arterial hypertension (PAH) is a rare pulmonary vascular disease that affects people of all ethnic origins and age groups including newborns. In PAH, pulmonary arteries and arterioles undergo a series of pathological changes including remodeling of the entire pulmonary vasculatures and extracellular matrices, mis-localized growth of pulmonary arterial cells, and development of glomeruloid-like lesions called plexiform lesions. Traditionally, various animal and cellular models have been used to understand PAH pathophysiology, investigate sex-disparity in PAH and monitor therapeutic efficacy of PAH medications. However, traditional models can only partially capture various pathological features of PAH, and they are not adaptable to combinatorial study design for deciphering intricately intertwined complex cellular processes implicated in PAH pathogenesis. While many microfluidic chip-based models are currently available for major diseases, no such disease-on-a-device model is available for PAH, an under investigated disease. In the absence of any chip-based models of PAH, we recently proposed a five-channel polydimethylsiloxane (PDMS)-based microfluidic device that can emulate major pathological features of PAH. However, our proposed model can make a bigger impact on the PAH field only when the larger scientific community engaged in PAH research can fabricate the device and develop the model in their laboratory settings. With this goal in mind, in this study, we have described the detailed methodologies for fabrication and development of the PAH chip model including a thorough explanation of scientific principles for various steps for chip fabrication, a detailed list of reagents, tools and equipment along with their source and catalogue numbers, description of laboratory setup, and cautionary notes. Finally, we explained the methodologies for on-chip cell seeding and application of this model for studying PAH pathophysiology. We believe investigators with little or no training in microfluidic chip fabrication can fabricate this eminently novel PAH-on-a-chip model. As such, this study will have a far-reaching impact on understanding PAH pathophysiology, unravelling the biological mystery associated with sexual dimorphism in PAH, and developing PAH therapy based on patient sex and age.

Mitochondrial uncoupling protein-2 reprograms metabolism to induce oxidative stress and myofibroblast senescence in age-associated lung fibrosis.

Mitochondrial dysfunction has been associated with age-related diseases, including idiopathic pulmonary fibrosis (IPF). We provide evidence that implicates chronic elevation of the mitochondrial anion carrier protein, uncoupling protein-2 (UCP2), in increased generation of reactive oxygen species, altered redox state and cellular bioenergetics, impaired fatty acid oxidation, and induction of myofibroblast senescence. This pro-oxidant senescence reprogramming occurs in concert with conventional actions of UCP2 as an uncoupler of oxidative phosphorylation with dissipation of the mitochondrial membrane potential. UCP2 is highly expressed in human IPF lung myofibroblasts and in aged fibroblasts. In an aging murine model of lung fibrosis, the in vivo silencing of UCP2 induces fibrosis regression. These studies indicate a pro-fibrotic function of UCP2 in chronic lung disease and support its therapeutic targeting in age-related diseases associated with impaired tissue regeneration and organ fibrosis.

Plasma microRNA and metabolic changes associated with pediatric acute respiratory distress syndrome: a prospective cohort study.

Acute respiratory distress syndrome is a heterogeneous pathophysiological process responsible for significant morbidity and mortality in pediatric intensive care patients. Diagnosis is defined by clinical characteristics that identify the syndrome after development. Subphenotyping patients at risk of progression to ARDS could provide the opportunity for therapeutic intervention. microRNAs, non-coding RNAs stable in circulation, are a promising biomarker candidate. We conducted a single-center prospective cohort study to evaluate random forest classification of microarray-quantified circulating microRNAs in critically ill pediatric patients. We additionally selected a sub-cohort for parallel metabolomics profiling as a pilot study for concurrent use of miRNAs and metabolites as circulating biomarkers. In 35 patients (n = 21 acute respiratory distress, n = 14 control) 15 microRNAs were differentially expressed. Unsupervised random forest classification accurately grouped ARDS and control patients with an area under the curve of 0.762, which was improved to 0.839 when subset to only patients with bacterial infection. Nine metabolites were differentially abundant between acute respiratory distress and control patients (n = 4, both groups) and abundance was highly correlated with miRNA expression. Random forest classification of microRNAs differentiated critically ill pediatric patients who developed acute respiratory distress relative to those who do not. The differential expression of microRNAs and metabolites provides a strong foundation for further work to validate their use as a prognostic biomarker.