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Figure S1-13 and Table S1,3

Table S2

OBJECTIVE: To demonstrate sensitivity of diffusion-weighted MRI (DW-MRI) to pulmonary cellular-space changes during normal in-utero development using fetal rhesus macaques, compared to histological biomarkers. STUDY DESIGN: In-vivo/ex-vivo DW-MRI was acquired in 26 fetal rhesus lungs (early-canalicular through saccular stages). Apparent diffusion coefficients (ADC) from MRI and tissue area-density (H&E), alveolar type-II cells (ABCA3), and epithelial cells (TTF1) from histology were compared between gestational stages. RESULTS: In-vivo/ex-vivo ADC correlated with each other (Spearman ρ=0.47, P=0.038; Bland-Altman bias = 0.0835) and with area-density (in-vivo ρ=−0.56, P=0.011; ex-vivo ρ=−0.83, P

COVID-19 has different clinical stages, and effective therapy depends on the location and extent of the infection. The purpose of this review is to provide a background for understanding the progression of the disease throughout the pulmonary epithelium and discuss therapeutic options. The prime sites for infection that will be contrasted in this review are the conducting airways and the gas exchange portions of the lung. These two sites are characterised by distinct cellular composition and innate immune responses, which suggests the use of distinct therapeutic agents. In the nose, ciliated cells are the primary target cells for SARS-CoV-2 viral infection, replication and release. Infected cells shed their cilia, which disables mucociliary clearance. Evidence further points to a suppressed or incompletely activated innate immune response to SARS-CoV-2 infection in the upper airways. Asymptomatic individuals can still have a productive viral infection and infect others. In the gas exchange portion of the lung, the alveolar type II epithelial cell is the main target cell type. Cell death and marked innate immune response during infection likely contribute to alveolar damage and resultant acute respiratory distress syndrome. Alveolar infection can precipitate a hyperinflammatory state, which is the target of many therapies in severe COVID-19. Disease resolution in the lung is variable and may include scaring and long-term sequalae because the alveolar type II cells are also progenitor cells for the alveolar epithelium.

Lung epithelial regeneration after acute injury requires coordination of extensive cellular and molecular processes controlling proliferation and differentiation of specialized alveolar cells to pattern the morphologically complex alveolar gas exchange surface. During regeneration, specialized Wnt-responsive alveolar epithelial progenitor (AEP) cells, a subset of alveolar type 2 (AT2) cells, proliferate and transition to alveolar type 1 (AT1) cells, though the precise molecular and epigenetic determinants of these processes remain unclear. Here, we report a refined primary murine alveolar organoid assay which recapitulates critical aspects of in vivo regeneration, providing a tractable model to dissect these regenerative processes. Clonal expansion of single AEPs generate complex alveolar organoids with extensive structural maturation and organization. These organoids contain properly patterned AT1 and AT2 cells surrounding numerous alveolar-like cavities with minimal structural contribution from mesenchymal cells, implying extensive cell autonomous regenerative function encoded in adult AEPs. Leveraging a time series of paired scRNAseq and scATACseq, we identified the AEP state at single cell resolution and described two distinct AEP to AT1 intermediate states: a widely reported Krt8+ transitional state defined by cell stress markers and a second state defined by differential activation of signaling pathways mediating AT1 cell differentiation. Transcriptional regulatory network (TRN) analysis demonstrated that these AT1 transition states were driven by distinct regulatory networks controlled in part by differential activity of Nkx2-1. Genetic ablation of Nkx2-1 in AEP-derived organoids was sufficient to cause transition to a proliferative stressed Krt8+ state characterized by disorganized, uncontrolled growth. Finally, AEP-specific deletion of Nkx2-1 in adult mice led to rapid loss of AEP state, clonal expansion, and disorganization of alveolar structure, implying a continuous requirement for Nkx2-1 in maintenance and function of adult lung progenitors. Together, these data provide new insight into cellular hierarchies in lung regeneration and implicate dynamic epigenetic maintenance via lineage transcription factors as central to control of facultative progenitor activity in AEPs.

Pulmonary alveolar proteinosis (PAP) is a life-threatening rare lung syndrome characterized by the accumulation of surfactant and lipid-loaded macrophages within the alveoli for which there is no cure and no approved therapies. The clinical diagnosis of PAP, often made by invasive lung biopsies and/or cytology of bronchoalveolar lavage fluid does not identify the underlying cause of disease. In addition, no biomarkers exist to inform prognosis or therapeutic options in PAP. We now report on the use of comprehensive mass spectrometry to profile and define the lipid signature of alveolar macrophages obtained from PAP patients. In addition, we quantify how these macrophage-associated lipids change during clinical treatment. Our studies demonstrate that clinical improvement in treated PAP patients is associated with a decrease in total lipid content, indicating that levels of these macrophage-associated lipids correlate with the severity of the disease.

Antenatal steroid (ANS) therapy is the standard care for women at imminent risk of preterm labor. Despite extensive and long-standing use, 40%–50% of babies exposed antenatally to steroids do not derive benefit; remaining undelivered 7 days or more after ANS treatment is associated with a lack of treatment benefit and increased risk of harm. We used a pregnant sheep model to evaluate the impact of continuous versus pulsed ANS treatments on fetal lung maturation at an extended, 8-day treatment to delivery interval. Continuous low-dose ANS treatments for more than 72 h in duration improved fetal lung maturation at 8 days after treatment initiation. If fetal ANS exposure was interrupted, the beneficial ANS effect was lost. Truncated treatments, including that simulating the current clinical treatment regimen, did not improve lung function. Variable fetal lung maturation was correlated to the amount of saturated phosphatidylcholine present in the lung fluid. These data demonstrate that 1) the durability of ANS therapy may be enhanced by employing an extended, low-dose treatment regimen by reducing total dose and 2) interrupting the continuity of fetal exposure by allowing it to fall below a minimal threshold was associated with comparably poor functional maturation of the preterm ovine lung.

Naturally occurring adeno-associated virus (AAV) serotypes that bind to ligands such as AVB sepharose or heparin can be purified by affinity chromatography, which is a more efficient and scalable method than gradient ultracentrifugation. Wild-type AAV8 does not bind effectively to either of these molecules, which constitutes a barrier to using this vector when a high throughput design is required. Previously, AAV8 was engineered to contain a SPAKFA amino acid sequence to facilitate purification using AVB sepharose resin; however, in vivo studies were not conducted to examine whether these capsid mutations altered the transduction profile. To address this gap in knowledge, a mutant AAV8 capsid was engineered to bind to AVB sepharose and heparan sulfate (AAV8-AVB-HS), which efficiently bound to both affinity columns, resulting in elution yields of >80% of the total vector loaded compared to

Mutations in the gene SFTPC, encoding surfactant protein C (SP-C), are associated with interstitial lung disease in children and adults. To assess the natural history of disease, we knocked in a familial, disease-associated SFTPC mutation, L188Q (L184Q [LQ] in mice), into the mouse Sftpc locus. Translation of the mutant proprotein, proSP-CLQ, exceeded that of proSP-CWT in neonatal alveolar type 2 epithelial cells (AT2 cells) and was associated with transient activation of oxidative stress and apoptosis, leading to impaired expansion of AT2 cells during postnatal alveolarization. Differentiation of AT2 to AT1 cells was also inhibited in ex vivo organoid culture of AT2 cells isolated from LQ mice; importantly, treatment with antioxidant promoted alveolar differentiation. Upon completion of alveolarization, SftpcLQ expression was downregulated, leading to resolution of chronic stress responses; however, the failure to restore AT2 cell numbers resulted in a permanent loss of AT2 cells that was linked to decreased regenerative capacity in the adult lung. Collectively, these data support the hypothesis that susceptibility to disease in adult LQ mice is established during postnatal lung development, and they provide a potential explanation for the delayed onset of disease in patients with familial pulmonary fibrosis.

The use of antenatal corticosteroids (ACS) in low-resource environments is sporadic. Further, drug choice, dose, and route of ACS are not optimized. We report the pharmacokinetics and pharmacodynamics of oral dosing of ACS using a preterm sheep model. We measured pharmacokinetics of oral betamethasone-phosphate (Beta-P) and dexamethasone-phosphate (Dex-P) using catheterized pregnant sheep. We compared fetal lung maturation responses of oral Beta-P and Dex-P to the standard treatment with 2 doses of the i.m. mixture of Beta-P and betamethasone-acetate at 2, 5, and 7 days after initiation of ACS. Oral Dex-P had lower bioavailability than Beta-P, giving a lower maximum maternal and fetal concentration. A single oral dose of 0.33 mg/kg of Beta-P was equivalent to the standard clinical treatment assessed at 2 days; 2 doses of 0.16 mg/kg of oral Beta-P were equivalent to the standard clinical treatment at 7 days as assessed by lung mechanics and gas exchange after preterm delivery and ventilation. In contrast, oral Dex-P was ineffective because of its decreased bioavailability. Using a sheep model, we demonstrate the use of pharmacokinetics to develop oral dosing strategies for ACS. Oral dosing is feasible and may facilitate access to ACS in low-resource environments.

Respiratory complicˆations are the major cause of morbidity and mortality among preterm infants, which is partially prevented by the administration of antenatal corticosteroids (ACS). Most very preterm infants are exposed to chorioamnionitis, but short- and long-term effects of ACS treatment in this setting are not well defined. In low-resource settings, ACS increased neonatal mortality by perhaps increasing infection. We report that treatment with low-dose ACS in the setting of inflammation induced by intraamniotic lipopolysaccharide (LPS) in rhesus macaques improves lung compliance and increases surfactant production relative to either exposure alone. RNA sequencing shows that these changes are mediated by suppression of proliferation and induction of mesenchymal cellular death via TP53. The combined exposure results in a mature-like transcriptomic profile with inhibition of extracellular matrix development by suppression of collagen genes COL1A1, COL1A2, and COL3A1 and regulators of lung development FGF9 and FGF10. ACS and inflammation also suppressed signature genes associated with proliferative mesenchymal progenitors similar to the term gestation lung. Treatment with ACS in the setting of inflammation may result in early respiratory advantage to preterm infants, but this advantage may come at a risk of abnormal extracellular matrix development, which may be associated with increased risk of chronic lung disease.

While antenatal glucocorticoids are widely used to enhance lung function in preterm infants, cellular and molecular mechanisms by which glucocorticoid receptor (GR) signaling influences lung maturation remain poorly understood. Deletion of the glucocorticoid receptor gene ( Nr3c1) from fetal pulmonary mesenchymal cells phenocopied defects caused by global Nr3c1 deletion, while lung epithelial- or endothelial-specific Nr3c1 deletion did not impair lung function at birth. We integrated genome-wide gene expression profiling, ATAC-seq, and single cell RNA-seq data in mice in which GR was deleted or activated to identify the cellular and molecular mechanisms by which glucocorticoids control prenatal lung maturation. GR enhanced differentiation of a newly defined proliferative mesenchymal progenitor cell (PMP) into matrix fibroblasts (MFBs), in part by directly activating extracellular matrix-associated target genes, including Fn1, Col16a4, and Eln and by modulating VEGF, JAK-STAT, and WNT signaling. Loss of mesenchymal GR signaling blocked fibroblast progenitor differentiation into mature MFBs, which in turn increased proliferation of SOX9+ alveolar epithelial progenitor cells and inhibited differentiation of mature alveolar type II (AT2) and AT1cells. GR signaling controls genes required for differentiation of a subset of proliferative mesenchymal progenitors into matrix fibroblasts, in turn, regulating signals controlling AT2/AT1progenitor cell proliferation and differentiation and identifying cells and processes by which glucocorticoid signaling regulates fetal lung maturation.

Activated erythropoietin (EPO) receptor (EPOR) signaling causes erythrocytosis. The important role of macrophages for the erythroid expansion and differentiation process has been reported, both in baseline and stress erythropoiesis. However, the significance of EPOR signaling for regulation of macrophages contributing to erythropoiesis has not been fully understood. Here we show that EPOR signaling activation quickly expands both erythrocytes and macrophages in vivo in mouse models of primary and secondary erythrocytosis. To mimic the chimeric condition and expansion of the disease clone in the polycythemia vera patients, we combined Cre-inducible Jak2V617F/+ allele with LysM-Cre allele which expresses in mature myeloid cells and some of the HSC/Ps (LysM-Cre;Jak2V617F/+ mice). We also generated inducible EPO-mediated secondary erythrocytosis models using Alb-Cre, Rosa26-loxP-stop-loxP-rtTA, and doxycycline inducible EPAS1-double point mutant (DPM) alleles (Alb-Cre;DPM mice). Both models developed a similar degree of erythrocytosis. Macrophages were also increased in both models without increase of major inflammatory cytokines and chemokines. EPO administration also quickly induced these macrophages in wild-type mice before observable erythrocytosis. These findings suggest that EPOR signaling activation could induce not only erythroid cell expansion, but also macrophages. Surprisingly, an in vivo genetic approach indicated that most of those macrophages do not express EPOR, but erythroid cells and macrophages contacted tightly with each other. Given the importance of the central macrophages as a niche for erythropoiesis, further elucidation of the EPOR signaling mediated-regulatory mechanisms underlying macrophage induction might reveal a potential therapeutic target for erythrocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening syndrome characterized by overwhelming immune activation. A steroid and chemotherapy-based regimen remains as the first-line of therapy but it has substantial morbidity. Thus, novel, less toxic therapy for HLH is urgently needed. Although differences exist between familial HLH (FHL) and secondary HLH (sHLH), they have many common features. Using bioinformatic analysis with FHL and systemic juvenile idiopathic arthritis, which is associated with sHLH, we identified a common hypoxia-inducible factor 1A (HIF1A) signature. Furthermore, HIF1A protein levels were found to be elevated in the lymphocytic choriomeningitis virus infected Prf1−/− mouse FHL model and the CpG oligodeoxynucleotide-treated mouse sHLH model. To determine the role of HIF1A in HLH, a transgenic mouse with an inducible expression of HIF1A/ARNT proteins in hematopoietic cells was generated, which caused lethal HLH-like phenotypes: severe anemia, thrombocytopenia, splenomegaly, and multi-organ failure upon HIF1A induction. Mechanistically, these mice show type 1 polarized macrophages and dysregulated natural killler cells. The HLH-like phenotypes in this mouse model are independent of both adaptive immunity and interferon-γ, suggesting that HIF1A is downstream of immune activation in HLH. In conclusion, our data reveal that HIF1A signaling is a critical mediator for HLH and could be a novel therapeutic target for this syndrome.

‘LungGENS’, our previously developed web tool for mapping single-cell gene expression in the developing lung, has been well received by the pulmonary research community. With continued support from the ‘LungMAP’ consortium, we extended the scope of the LungGENS database to accommodate transcriptomics data from pulmonary tissues and cells from human and mouse at different stages of lung development. Lung Gene Expression Analysis (LGEA) web portal is an extended version of LungGENS useful for the analysis, display and interpretation of gene expression patterns obtained from single cells, sorted cell populations and whole lung tissues. The LGEA web portal is freely available at http://research.cchmc.org/pbge/lunggens/mainportal.html.

The adhesion class of G protein-coupled receptors (GPCRs) is the second largest family of GPCRs (33 members in humans). Adhesion GPCRs (aGPCRs) are defined by a large extracellular N-terminal region that is linked to a C-terminal seven transmembrane (7TM) domain via a GPCR-autoproteolysis inducing (GAIN) domain containing a GPCR proteolytic site (GPS). Most aGPCRs undergo autoproteolysis at the GPS motif, but the cleaved fragments stay closely associated, with the N-terminal fragment (NTF) bound to the 7TM of the C-terminal fragment (CTF). The NTFs of most aGPCRs contain domains known to be involved in cell-cell adhesion, while the CTFs are involved in classical G protein signaling, as well as other intracellular signaling. In this workshop report, we review the most recent findings on the biology, signaling mechanisms, and physiological functions of aGPCRs., info:eu-repo/semantics/published

Antenatal corticosteroids (ACS) are standard of care for women at risk of preterm delivery, although choice of drug, dose or route have not been systematically evaluated. Further, ACS are infrequently used in low resource environments where most of the mortality from prematurity occurs. We report proof of principle experiments to test betamethasone-phosphate (Beta-P) or dexamethasone-phosphate (Dex-P) given orally in comparison to the clinical treatment with the intramuscular combination drug beta-phosphate plus beta-acetate in a Rhesus Macaque model. First, we performed pharmacokinetic studies in non-pregnant monkeys to compare blood levels of the steroids using oral dosing with Beta-P, Dex-P and an effective maternal intramuscular dose of the beta-acetate component of the clinical treatment. We then evaluated maternal and fetal blood steroid levels with limited fetal sampling under ultrasound guidance in pregnant macaques. We found that oral Beta is more slowly cleared from plasma than oral Dex. The blood levels of both drugs were lower in maternal plasma of pregnant than in non-pregnant macaques. Using the pharmacokinetic data, we treated groups of 6-8 pregnant monkeys with oral Beta-P, oral Dex-P, or the maternal intramuscular clinical treatment and saline controls and measured pressure-volume curves to assess corticosteroid effects on lung maturation at 5d. Oral Beta-P improved the pressure-volume curves similarly to the clinical treatment. Oral Dex-P gave more variable and nonsignificant responses. We then compared gene expression in the fetal lung, liver and hippocampus between oral Beta-P and the clinical treatment by RNA-sequencing. The transcriptomes were largely similar with small gene expression differences in the lung and liver, and no differences in the hippocampus between the groups. As proof of principle, ACS therapy can be effective using inexpensive and widely available oral drugs. Clinical dosing strategies must carefully consider the pharmacokinetics of oral Beta-P or Dex-P to minimize fetal exposure while achieving the desired treatment responses.

Proteasomes are a critical component of quality control that regulate turnover of short-lived, unfolded, and misfolded proteins. Proteasome activity has been therapeutically targeted and considered as a treatment option for several chronic lung disorders including pulmonary fibrosis. Although pharmacologic inhibition of proteasome activity effectively prevents the transformation of fibroblasts to myofibroblasts, the effect on alveolar type 2 (AT2) epithelial cells is not clear. To address this knowledge gap, we generated a genetic model in which a proteasome subunit, RPT3, which promotes assembly of active 26S proteasome, was conditionally deleted in AT2 cells of mice. Partial deletion of RPT3 resulted in 26S proteasome dysfunction, leading to augmented cell stress and cell death. Acute loss of AT2 cells resulted in depletion of alveolar surfactant, disruption of the alveolar epithelial barrier and, ultimately, lethal acute respiratory distress syndrome (ARDS). This study underscores importance of proteasome function in maintenance of AT2 cell homeostasis and supports the need to further investigate the role of proteasome dysfunction in ARDS pathogenesis.

Antenatal corticosteroids (ANS) are the major intervention to decrease respiratory distress syndrome and mortality from premature birth and are standard of care. The use of ANS is expanding to include new indications and gestational ages, although the recommended dosing was never optimized. The most widely used treatment is two intramuscular doses of a 1:1 mixture of betamethasone-phosphate (Beta-P) and betamethasone-acetate (Beta-Ac) – the clinical drug. We tested in a primate model the efficacy of the slow release Beta-Ac alone for enhancing fetal lung maturation and to reduce fetal corticosteroid exposure and potential toxic effects. Pregnant rhesus macaques at 127 days of gestation (80% of term) were treated with either the clinical drug (0.25 mg/kg) or Beta-Ac (0.125 mg/kg). Beta-Ac alone increased lung compliance and surfactant concentration in the fetal lung equivalently to the clinical drug. By transcriptome analyses the early suppression of genes associated with immune responses and developmental pathways were less affected by Beta-Ac than the clinical drug. Promoter and regulatory analysis prediction identified differentially expressed genes targeted by the glucocorticoid receptor in the lung. At 5 days the clinical drug suppressed genes associated with neuronal development and differentiation in the fetal hippocampus compared to control, while low dose Beta-Ac alone did not. A low dose ANS treatment with Beta-Ac should be assessed for efficacy in human trials.

Patients with nosocomial pneumonia exhibit elevated levels of neurotoxic amyloid and tau proteins in the cerebrospinal fluid (CSF). In vitro studies indicate that pulmonary endothelium infected with clinical isolates of either Pseudomonas aeruginosa, Klebsiella pneumoniae, or Staphylococcus aureus produces and releases cytotoxic amyloid and tau proteins. However, the effects of the pulmonary endothelium-derived amyloid and tau proteins on brain function have not been elucidated. Here, we show that P. aeruginosa infection elicits accumulation of detergent insoluble tau protein in the mouse brain and inhibits synaptic plasticity. Mice receiving endothelium-derived amyloid and tau proteins via intracerebroventricular injection exhibit a learning and memory deficit in object recognition, fear conditioning, and Morris water maze studies. We compared endothelial supernatants obtained after the endothelia were infected with P. aeruginosa possessing an intact [P. aeruginosa isolated from patient 103 (PA103) supernatant] or defective [mutant strain of P. aeruginosa lacking a functional type 3 secretion system needle tip complex (ΔPcrV) supernatant] type 3 secretion system. Whereas the PA103 supernatant impaired working memory, the ΔPcrV supernatant had no effect. Immunodepleting amyloid or tau proteins from the PA103 supernatant with the A11 or T22 antibodies, respectively, overtly rescued working memory. Recordings from hippocampal slices treated with endothelial supernatants or CSF from patients with or without nosocomial pneumonia indicated that endothelium-derived neurotoxins disrupted the postsynaptic synaptic response. Taken together, these results establish a plausible mechanism for the neurologic sequelae consequent to nosocomial bacterial pneumonia.-Balczon, R., Pittet, J.-F., Wagener, B. M., Moser, S. A., Voth, S., Vorhees, C. V., Williams, M. T., Bridges, J. P., Alvarez, D. F., Koloteva, A., Xu, Y., Zha, X.-M., Audia, J. P., Stevens, T., Lin, M. T. Infection-induced endothelial amyloids impair memory.

The use of antenatal corticosteroids (ACS) in low-resource environments is sporadic. Further, drug choice, dose, and route of ACS are not optimized. We report the pharmacokinetics and pharmacodynamics of oral dosing of ACS using a preterm sheep model.We measured pharmacokinetics of oral betamethasone-phosphate (Beta-P) and dexamethasone-phosphate (Dex-P) using catheterized pregnant sheep. We compared fetal lung maturation responses of oral Beta-P and Dex-P to the standard treatment with 2 doses of the i.m. mixture of Beta-P and betamethasone-acetate at 2, 5, and 7 days after initiation of ACS.Oral Dex-P had lower bioavailability than Beta-P, giving a lower maximum maternal and fetal concentration. A single oral dose of 0.33 mg/kg of Beta-P was equivalent to the standard clinical treatment assessed at 2 days; 2 doses of 0.16 mg/kg of oral Beta-P were equivalent to the standard clinical treatment at 7 days as assessed by lung mechanics and gas exchange after preterm delivery and ventilation. In contrast, oral Dex-P was ineffective because of its decreased bioavailability.Using a sheep model, we demonstrate the use of pharmacokinetics to develop oral dosing strategies for ACS. Oral dosing is feasible and may facilitate access to ACS in low-resource environments.

Background Patients with coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) demonstrate high rates of co-infection with respiratory viruses, including influenza A (IAV), suggesting pathogenic interactions. Methods We investigated how IAV may increase the risk of COVID-19 lung disease, focusing on the receptor angiotensin-converting enzyme (ACE)2 and the protease TMPRSS2, which cooperate in the intracellular uptake of SARS-CoV-2. Results We found, using single-cell RNA sequencing of distal human nondiseased lung homogenates, that at baseline, ACE2 is minimally expressed in basal, goblet, ciliated and secretory epithelial cells populating small airways. We focused on human small airway epithelial cells (SAECs), central to the pathogenesis of lung injury following viral infections. Primary SAECs from nondiseased donor lungs apically infected (at the air-liquid interface) with IAV (up to 3×105 pfu; ~1 multiplicity of infection) markedly (eight-fold) boosted the expression of ACE2, paralleling that of STAT1, a transcription factor activated by viruses. IAV increased the apparent electrophoretic mobility of intracellular ACE2 and generated an ACE2 fragment (90 kDa) in apical secretions, suggesting cleavage of this receptor. In addition, IAV increased the expression of two proteases known to cleave ACE2, sheddase ADAM17 (TACE) and TMPRSS2 and increased the TMPRSS2 zymogen and its mature fragments, implicating proteolytic autoactivation. Conclusion These results indicate that IAV amplifies the expression of molecules necessary for SARS-CoV-2 infection of the distal lung. Furthermore, post-translational changes in ACE2 by IAV may increase vulnerability to lung injury such as acute respiratory distress syndrome during viral co-infections. These findings support efforts in the prevention and treatment of influenza infections during the COVID-19 pandemic., Shareable abstract (@ERSpublications) Influenza virus infection of cells lining the small airways increases the expression of molecules required for SARS-CoV-2 uptake in a manner that predicts increased severity of lung disease in those co-infected with influenza and coronaviruses https://bit.ly/3nu1WAo

Type 3 innate lymphoid cells (ILC3s) are critical for lung defense against bacterial pneumonia in the neonatal period, but the signals that guide pulmonary ILC3 development remain unclear. Here, we demonstrated that pulmonary ILC3s descended from ILC precursors that populated a niche defined by fibroblasts in the developing lung. Alveolar fibroblasts produced insulin-like growth factor 1 (IGF1), which instructed expansion and maturation of pulmonary ILC precursors. Conditional ablation of IGF1 in alveolar fibroblasts or deletion of the IGF-1 receptor from ILC precursors interrupted ILC3 biogenesis and rendered newborn mice susceptible to pneumonia. Premature infants with bronchopulmonary dysplasia, characterized by interrupted postnatal alveolar development and increased morbidity to respiratory infections, had reduced IGF1 concentrations and pulmonary ILC3 numbers. These findings indicate that the newborn period is a critical window in pulmonary immunity development, and disrupted lung development in prematurely born infants may have enduring effects on host resistance to respiratory infections.

Antenatal corticosteroids (ANS) are the major intervention to decrease respiratory distress syndrome and mortality from premature birth and are standard of care. The use of ANS is expanding to include new indications and gestational ages, although the recommended dosing was never optimized. The most widely used treatment is two intramuscular doses of a 1:1 mixture of betamethasone-phosphate (Beta-P) and betamethasone-acetate (Beta-Ac) – the clinical drug. We tested in a primate model the efficacy of the slow release Beta-Ac alone for enhancing fetal lung maturation and to reduce fetal corticosteroid exposure and potential toxic effects. Pregnant rhesus macaques at 127 days of gestation (80% of term) were treated with either the clinical drug (0.25 mg/kg) or Beta-Ac (0.125 mg/kg). Beta-Ac alone increased lung compliance and surfactant concentration in the fetal lung equivalently to the clinical drug. By transcriptome analyses the early suppression of genes associated with immune responses and developmental pathways were less affected by Beta-Ac than the clinical drug. Promoter and regulatory analysis prediction identified differentially expressed genes targeted by the glucocorticoid receptor in the lung. At 5 days the clinical drug suppressed genes associated with neuronal development and differentiation in the fetal hippocampus compared to control, while low dose Beta-Ac alone did not. A low dose ANS treatment with Beta-Ac should be assessed for efficacy in human trials.

Pulmonary alveolar proteinosis (PAP) is a syndrome of reduced GM-CSF-dependent, macrophage-mediated surfactant clearance, dysfunctional foamy alveolar macrophages, alveolar surfactant accumulation, and hypoxemic respiratory failure for which the pathogenetic mechanism is unknown. Here, we examine the lipids accumulating in alveolar macrophages and surfactant to define the pathogenesis of PAP and evaluate a novel pharmacotherapeutic approach. In PAP patients, alveolar macrophages have a marked increase in cholesterol but only a minor increase in phospholipids, and pulmonary surfactant has an increase in the ratio of cholesterol to phospholipids. Oral statin therapy is associated with clinical, physiological, and radiological improvement in autoimmune PAP patients, and ex vivo statin treatment reduces cholesterol levels in explanted alveolar macrophages. In Csf2rb−/− mice, statin therapy reduces cholesterol accumulation in alveolar macrophages and ameliorates PAP, and ex vivo statin treatment increases cholesterol efflux from macrophages. These results support the feasibility of statin as a novel pathogenesis-based pharmacotherapy of PAP., Pulmonary alveolar proteinosis (PAP) is associated with defective macrophage clearance of surfactant. Here, the authors show that patients with PAP have altered cholesterol-to-phospholipid ratio in their surfactant, and that more importantly, statin therapy and reduction of cholesterol accumulation in macrophages can ameliorate PAP in both humans and mice.

Gene therapy for the treatment of genetic disorders has demonstrated considerable therapeutic success in clinical trials. Among the most effective and commonly used gene delivery vectors are those based on adeno-associated virus (AAV). Despite these advances in clinical gene therapy, further improvements in AAV vector properties such as rapid intracellular processing and transgene expression, targeted transduction of therapeutically relevant cell types, and longevity of transgene expression, will render extension of such successes to many other human diseases. Engineering of AAV capsids continues to evolve the specificity and efficiency of AAV-mediated gene transfer. Here, we describe a triple AAV6 mutant, termed AAV6.2FF, containing F129L, Y445F, and Y731F mutations. AAV6.2FF yielded 10-fold greater transgene expression in lung than AAV6 after 21 days. Additionally, this novel capsid demonstrated 101-fold and 49-fold increased transgene expression in the muscle and lungs, respectively, 24 hr post vector delivery when compared with the parental AAV6. Furthermore, AAV6.2FF retains heparin sulfate binding capacity and displays a 10-fold increase in resistance to pooled immunoglobulin neutralization in vitro. The rapid and potent expression mediated by AAV6.2FF is ideally suited to applications such as vectored immunoprophylaxis, in which rapid transgene expression is vital for use during an outbreak response scenario. Keywords: AAV, AAV capsid, gene therapy, lung transduction, muscle transduction, vectored immunoprophylaxis

Nonalcoholic fatty liver disease (NAFLD), a metabolic predisposition for development of hepatocellular carcinoma (HCC), represents a disease spectrum ranging from steatosis to steatohepatitis to cirrhosis. Acox1, a rate-limiting enzyme in peroxisomal fatty acid β-oxidation, regulates metabolism, spontaneous hepatic steatosis, and hepatocellular damage over time. However, it is unknown whether Acox1 modulates inflammation relevant to NAFLD pathogenesis or if Acox1-associated metabolic and inflammatory derangements uncover and accelerate potential for NAFLD progression. Here, we show that mice with a point mutation in Acox1 (Acox1Lampe1) exhibited altered cellular metabolism, modified T cell polarization, and exacerbated immune cell inflammatory potential. Further, in context of a brief obesogenic diet stress, NAFLD progression associated with Acox1 mutation resulted in significantly accelerated and exacerbated hepatocellular damage via induction of profound histological changes in hepatocytes, hepatic inflammation, and robust upregulation of gene expression associated with HCC development. Collectively, these data demonstrate that β-oxidation links metabolism and immune responsiveness and that a better understanding of peroxisomal β-oxidation may allow for discovery of mechanisms central for NAFLD progression.

Myelodysplastic syndromes (MDS) are heterogeneous hematopoietic disorders that are incurable with conventional therapy. Their incidence is increasing with global population aging. Although many genetic, epigenetic, splicing, and metabolic aberrations have been identified in patients with MDS, their clinical features are quite similar. Here, we show that hypoxia-independent activation of hypoxia-inducible factor 1α (HIF1A) signaling is both necessary and sufficient to induce dysplastic and cytopenic MDS phenotypes. The HIF1A transcriptional signature is generally activated in MDS patient bone marrow stem/progenitors. Major MDS-associated mutations (Dnmt3a, Tet2, Asxl1, Runx1, and Mll1) activate the HIF1A signature. Although inducible activation of HIF1A signaling in hematopoietic cells is sufficient to induce MDS phenotypes, both genetic and chemical inhibition of HIF1A signaling rescues MDS phenotypes in a mouse model of MDS. These findings reveal HIF1A as a central pathobiologic mediator of MDS and as an effective therapeutic target for a broad spectrum of patients with MDS. Significance: We showed that dysregulation of HIF1A signaling could generate the clinically relevant diversity of MDS phenotypes by functioning as a signaling funnel for MDS driver mutations. This could resolve the disconnection between genotypes and phenotypes and provide a new clue as to how a variety of driver mutations cause common MDS phenotypes. Cancer Discov; 8(11); 1438–57. ©2018 AACR. See related commentary by Chen and Steidl, p. 1355. This article is highlighted in the In This Issue feature, p. 1333

Adaptation to air breathing after birth is dependent upon the synthesis and secretion of pulmonary surfactant by alveolar type 2 (AT2) cells. Surfactant, a complex mixture of phospholipids and proteins, is secreted into the alveolus, where it reduces collapsing forces at the air-liquid interface to maintain lung volumes during the ventilatory cycle. ABCA3, an ATP-dependent Walker domain containing transport protein, is required for surfactant synthesis and lung function at birth. Mutations in ABCA3 cause severe surfactant deficiency and respiratory failure in newborn infants. We conditionally deleted the Abca3 gene in AT2 cells in the mature mouse lung. Loss of ABCA3 caused alveolar cell injury and respiratory failure. ABCA3-related lung dysfunction was associated with surfactant deficiency, inflammation, and alveolar-capillary leak. Extensive but incomplete deletion of ABCA3 caused alveolar injury and inflammation, and it initiated proliferation of progenitor cells, restoring ABCA3 expression, lung structure, and function. M2-like macrophages were recruited to sites of AT2 cell proliferation during the regenerative process and were present in lung tissue from patients with severe lung disease caused by mutations in ABCA3. The remarkable and selective regeneration of ABCA3-sufficient AT2 progenitor cells provides plausible approaches for future correction of ABCA3 and other genetic disorders associated with surfactant deficiency and acute interstitial lung disease.

Pulmonary function is dependent upon the precise regulation of alveolar surfactant. Alterations in pulmonary surfactant concentrations or function impair ventilation and cause tissue injury. Identification of the molecular pathways that sense and regulate endogenous alveolar surfactant concentrations, coupled with the ability to pharmacologically modulate them both positively and negatively, would be a major therapeutic advance for patients with acute and chronic lung diseases caused by disruption of surfactant homeostasis. The orphan adhesion GPCR GPR116 (also known as Adgrf5) is a critical regulator of alveolar surfactant concentrations. Here, we show that human and mouse GPR116 control surfactant secretion and reuptake in alveolar type II (AT2) cells by regulating guanine nucleotide–binding domain α q and 11 (Gq/11) signaling. Synthetic peptides derived from the ectodomain of GPR116 activated Gq/11-dependent inositol phosphate conversion, calcium mobilization, and cortical F-actin stabilization to inhibit surfactant secretion. AT2 cell–specific deletion of Gnaq and Gna11 phenocopied the accumulation of surfactant observed in Gpr116–/– mice. These data provide proof of concept that GPR116 is a plausible therapeutic target to modulate endogenous alveolar surfactant pools to treat pulmonary diseases associated with surfactant dysfunction.

Macrophages are critical to organ structure and function in health and disease. To determine mechanisms by which granulocyte/macrophage-colony stimulating factor (GM-CSF) signaling normally maintains surfactant homeostasis and how its disruption causes pulmonary alveolar proteinosis (PAP), we evaluated lipid composition in alveolar macrophages and lung surfactant, macrophage-mediated surfactant clearance kinetics/dynamics, and cholesterol-targeted pharmacotherapy of PAP in vitro and in vivo. Without GM-CSF signaling, surfactant-exposed macrophages massively accumulated cholesterol ester-rich lipid-droplets and surfactant had an increased proportion of cholesterol. GM-CSF regulated cholesterol clearance in macrophages in constitutive, dose-dependent, and reversible fashion but did not affect phospholipid clearance. PPARγ-agonist therapy increased cholesterol clearance in macrophages and reduced disease severity in PAP mice. Results demonstrate that GM-CSF is required for cholesterol clearance in macrophages, identify reduced cholesterol clearance as the primary macrophage defect driving PAP pathogenesis, and support the feasibility of translating pioglitazone as a novel pharmacotherapy of PAP.