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Idiopathic pulmonary fibrosis is increasingly associated with nerve-driven processes and endogenous innate immune ligands such as mitochondrial DNA (mtDNA). Interestingly, a connection between these entities has not been explored. Here, we report that noradrenaline (NA) derived from the lung’s adrenergic nerve supply drives α-smooth muscle actin (αSMA)-expressing fibroblast accumulation via mechanisms involving α1 adrenoreceptors and mtDNA. Using the bleomycin model, we compared ablation of the lung’s adrenergic nerve supply with surgical adrenal resection and found that NA derived from local but not adrenal sources contributes to experimentally induced lung fibrosis and the emergence of an αSMA+ve fibroblast population expressing adrenoreceptor α-1D (ADRA1D). Therapeutic delivery of the α1 adrenoreceptor antagonist terazosin reversed these changes and suppressed extracellular mtDNA accumulation. Cultured normal human lung fibroblasts displayed α1 adrenoreceptors and in response to costimulation with TGFβ1 and NA adopted ACTA2 expression and extracellular mtDNA release. These findings were opposed by terazosin. Evaluation of a previously studied IPF cohort revealed that patients prescribed α1 adrenoreceptor antagonists for nonpulmonary indications demonstrated improved survival and reduced concentrations of plasma mtDNA. Our observations link nerve-derived NA, α1 adrenoreceptors, extracellular mtDNA, and lung fibrogenesis in mouse models, cultured cells, and humans with IPF. Further study of this neuroinnate connection may yield new avenues for investigation in the clinical and basic science realms.

RationaleChanges in peripheral blood cell populations have been observed but not detailed at single-cell resolution in idiopathic pulmonary fibrosis (IPF).ObjectivesTo provide an atlas of the changes in the peripheral immune system in stable and progressive IPF.MethodsPeripheral blood mononuclear cells (PBMCs) from IPF patients and controls were profiled using 10x Chromium 5’ single-cell RNA sequencing (scRNA-seq). Flow cytometry was used for validation. Protein concentrations of Regulatory T-cells (Tregs) and Monocytes chemoattractants were measured in plasma and lung homogenates from patients and controls.Measurements and Main ResultsThirty-eight PBMC samples from 25 patients with IPF and 13 matched controls yielded 149,564 cells that segregated into 23 subpopulations, corresponding to all expected peripheral blood cell populations. Classical monocytes were increased in progressive and stable IPF compared to controls (32.1%, 25.2%, 17.9%, respectively, pConclusionsThe single-cell atlas of the peripheral immune system in IPF, reveals an outcome-predictive increase in classical monocytes and Tregs, as well as evidence for a lung-blood immune recruitment axis involving CCL7 (for classical monocytes) and CCL18/CCL22 (for Tregs).

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease characterized by progressive scar tissue formation. An acute exacerbation of IPF (AE-IPF) is a clinically significant respiratory decompensation that accounts for a significant proportion of IPF-related morbidity and mortality. AE-IPF can be idiopathic or associated with pulmonary embolism, infection, aspiration, surgery, and drug toxicity. In this novel case report, we describe a potential association between AE-IPF and BNT162b2 mRNA COVID-19 vaccination that was successfully treated with a short course of glucocorticoids. While our aim is to raise awareness for this yet-to-be-described adverse event, immunization against vaccine-preventable disease remains widely recommended in vulnerable patients with chronic lung disease such as IPF.

The severe acute respiratory syndrome coronavirus 2 pandemic poses extraordinary challenges. The tremendous number of coronavirus disease 2019 (COVID-19) cases in the United States has resulted in a large population of survivors with prolonged postinfection symptoms. The creation of multidisciplinary post-COVID-19 clinics to address both persistent symptoms and potential long-term complications requires an understanding of the acute disease and the emerging data regarding COVID-19 outcomes. Experience with severe acute respiratory syndrome and Middle East respiratory syndrome, post-acute respiratory distress syndrome complications, and post-intensive care syndrome also informs anticipated sequelae and clinical program design. Post-COVID-19 clinical programs should be prepared to care for individuals previously hospitalized with COVID-19 (including those who required critical care support), nonhospitalized individuals with persistent respiratory symptoms following COVID-19, and individuals with preexisting lung disease complicated by COVID-19. Effective multidisciplinary collaboration models leverage lessons learned during the early phases of the pandemic to overcome the unique logistical challenges posed by pandemic circumstances. Collaboration between physicians and researchers across disciplines will provide insight into survivorship that may shape the treatment of both acute disease and chronic complications. In this review, we discuss the aims, general principles, elements of design, and challenges of a successful multidisciplinary model to address the needs of COVID-19 survivors.

Idiopathic Pulmonary Fibrosis is increasingly associated with adrenergic innervation and endogenous innate immune ligands such as mitochondrial DNA (mtDNA). Interestingly, a connection between these entities has not been explored. Here we report that noradrenaline (NA) derived from the lung’s adrenergic nerve supply drives the accumulation of αSMA-expressing fibroblasts via a mechanism involving α1 adrenoreceptors and mtDNA. Using the bleomycin model of lung fibrosis we compared the effect of lung specific adrenergic denervation achieved via the inhalational administration of the sympathetic neurotoxin 6-hydroxydopamine to surgically mediated adrenal ablation and found that NA derived from local but not adrenal sources drives lung fibrosis. Bleomycin induced the appearance of a αSMA+ fibroblast population co-expressing the adrenoreceptor alpha-1D (ADRA1D). Therapeutic delivery of the α1 adrenoreceptor antagonist terazosin reversed these changes and suppressed the accumulation of extracellular mtDNA. TGFβ1-stimulated normal human lung fibroblasts treated with TGFβ1 and Noradrenaline expressed ADRA1D and developed reduced αSMA expression and extracellular mtDNA concentrations when treated with terazosin. IPF patients prescribed α1 adrenoreceptor antagonists for non-pulmonary indications showed improved survival and reduced concentrations of plasma mtDNA. These findings link nerve-derived NA and α1 adrenoreceptor antagonism with mtDNA accumulation and lung fibrogenesis in mouse models, cultured cells, and humans with IPF. Further study of this neuro-innate connection may yield new avenues for investigation in the clinical and basic science realms.

Sarcoidosis is a chronic granulomatous disease of unknown etiology that primarily affects the lungs. The development of stage IV or fibrotic lung disease accounts for a significant proportion of the morbidity and mortality attributable to sarcoidosis. Further investigation into the active mechanisms of disease pathogenesis and fibrogenesis might illuminate fundamental mediators of injury and repair while providing new opportunities for clinical intervention. However, progress in sarcoidosis research has been hampered by the heterogeneity of clinical phenotypes and the lack of a consensus modeling system. Recently, reverse translational research, wherein observations made at the patient level catalyze hypothesis-driven research at the laboratory bench, has generated new discoveries regarding the immunopathogenic mechanisms of pulmonary granuloma formation, fibrogenesis, and disease model development. The purpose of this review is to highlight the promise and possibility of these novel investigative efforts.

Objective Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is characterized by variable clinical outcomes, activation of innate immune pattern-recognition receptors (PRRs), and accumulation of α-smooth muscle actin (α-SMA)-expressing myofibroblasts. The aim of this study was to identify an association between these entities and mitochondrial DNA (mtDNA), an endogenous ligand for the intracellular DNA-sensing PRRs Toll-like receptor 9 (TLR-9) and cyclic GMP-AMP synthase/stimulator of interferon genes (cGAS/STING), which has yet to be determined. Methods Human lung fibroblasts (HLFs) from normal donors and SSc-ILD explants were treated with synthetic CpG DNA and assayed for α-SMA expression and extracellular mtDNA using quantitative polymerase chain reaction for the human MT-ATP6 gene. Plasma MT-ATP6 concentrations were evaluated in 2 independent SSc-ILD cohorts and demographically matched controls. The ability of SSc-ILD and control plasma to induce TLR-9 and cGAS/STING activation was evaluated with commercially available HEK 293 reporter cells. Plasma concentrations of type I interferons (IFNs), interleukin-6 (IL-6), and oxidized DNA were measured using electrochemiluminescence and enzyme-linked immunosorbent assay-based methods. Extracellular vesicles (EVs) precipitated from plasma were evaluated for MT-ATP6 concentrations and proteomics via liquid chromatography mass spectrometry. Results Normal HLFs and SSc-ILD fibroblasts developed increased α-SMA expression and MT-ATP6 release following CpG stimulation. Plasma mtDNA concentrations were increased in the 2 SSc-ILD cohorts, reflective of ventilatory decline, and were positively associated with both TLR-9 and cGAS/STING activation as well as type I IFN and IL-6 expression. Plasma mtDNA was not oxidized and was conveyed by EVs displaying a proteomics profile consistent with a multicellular origin. Conclusion These findings demonstrate a previously unrecognized connection between EV-encapsulated mtDNA, clinical outcomes, and intracellular DNA-sensing PRR activation in SSc-ILD. Further study of these interactions could catalyze novel mechanistic and therapeutic insights into SSc-ILD and related disorders.

Early selection steps preventing autoreactive naive B cell production are often impaired in patients with autoimmune diseases, but central and peripheral B cell tolerance checkpoints have not been assessed in patients with systemic sclerosis (SSc). This study was undertaken to characterize early B cell tolerance checkpoints in patients with SSc.Using an in vitro polymerase chain reaction-based approach that allows the expression of recombinant antibodies cloned from single B cells, we tested the reactivity of antibodies expressed by 212 CD19+CD21Compared to serum from healthy donors, serum from patients with SSc displayed elevated proportions of polyreactive and antinuclear-reactive new emigrant/transitional B cells that recognize topoisomerase I, suggesting that defective central B cell tolerance contributes to the production of serum autoantibodies characteristic of the disease. Frequencies of autoreactive mature naive B cells were also significantly increased in SSc patients compared to healthy donors, thus indicating that a peripheral B cell tolerance checkpoint may be impaired in SSc.Defective counterselection of developing autoreactive naive B cells in SSc leads to the production of self antigen-specific B cells that may secrete autoantibodies and allow the formation of immune complexes, which promote fibrosis in SSc.

Sarcoidosis is a granulomatous disorder thought to be caused by exposures in genetically susceptible individuals. This study investigated whether specific exposures were associated with different sarcoidosis phenotypes.Extensive demographic, occupational and environmental exposure data was analyzed from subjects enrolled in the NHLBI Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis (GRADS) study.In patients with sarcoidosis, radiation exposure was significantly associated with an increased risk of cardiac sarcoidosis versus non-cardiac sarcoidosis. No exposures were significantly associated with pulmonary only disease versus extrapulmonary disease with or without pulmonary involvement, Scadding Stage II/III/IV versus Scadding Stage 0/I, acute or remitting disease versus non-acute or non-remitting disease, nor chronic versus non-chronic disease. Although not reaching statistically significance after adjustment for multiple comparisons, there were a number of exposures associated with specific disease phenotypes, including exposures where relationships to sarcoidosis have previously been described such as rural exposures and pesticide exposures.Radiation exposure may be a risk factor for cardiac sarcoidosis. Other exposures may also be associated with specific phenotypes and should be further explored. The study was limited by small groups of exposed subjects for individual exposures and multiple comparisons. The development of novel and innovative exposure assessment tools is needed.

Sarcoidosis is an idiopathic inflammatory disorder that is commonly treated with glucocorticoids and there are no approved steroid-sparing medications. There is emerging evidence that Janus kinase (JAK) inhibitors, which inhibit JAK-dependent cytokine activity, may hold promise in sarcoidosis. In this open-label trial, 10 patients with recalcitrant sarcoidosis with cutaneous involvement were treated with tofacitinib 5 mg twice daily. There was no washout period and patients were permitted to continue, taper, or discontinue other treatments. The primary outcome was the change in the Cutaneous Sarcoidosis Activity and Morphology Instrument (CSAMI) activity score after 6 months. Change in internal organ disease activity was also assessed using total lesion glycolysis (TLG) determined by full-body positron emission tomography. A mean reduction in the CSAMI activity score of 82.7% was observed, with 6 patients showing a complete response. Internal organ response data was available in 8 patients; a decrease in TLG of ≥50% was noted in 5 patients, with complete or near complete resolution in 3 (>98% reduction in TLG). Patients were generally able to significantly taper or discontinue their baseline immunosuppressive regimen, which included prednisone in 5 patients. Single cell RNA-sequencing, bulk RNA-sequencing, and high-throughput proteomic analyses were performed on skin and blood as a function of treatment in order to delineate changes in immunologic signals with therapy. We identified CD4+ T cell derived IFN-γ as a central cytokine driver of sarcoidosis and inhibition of its activity was achieved with tofacitinib and correlated closely with clinical improvement. Tofacitinib appears to have impressive activity in treatment of sarcoidosis and likely acts by inhibiting IFN-γ, larger, controlled studies are warranted.

Idiopathic pulmonary fibrosis (IPF) is the most common and devastating of the interstitial lung diseases. Epithelial dysfunction is thought to play a prominent role in disease pathology, and we sought to characterize secreted signals that may contribute to disease pathology. Transcriptional profiling of senescent type II alveolar epithelial cells from mice with epithelial-specific telomere dysfunction identified the transforming growth factor-β family member, growth and differentiation factor 15 ( Gdf15), as the most significantly upregulated secreted protein. Gdf15 expression is induced in response to telomere dysfunction and bleomycin challenge in mice. Gdf15 mRNA is expressed by lung epithelial cells, and protein can be detected in peripheral blood and bronchoalveolar lavage following bleomycin challenge in mice. In patients with IPF, GDF15 mRNA expression in lung tissue is significantly increased and correlates with pulmonary function. Single-cell RNA sequencing of human lungs identifies epithelial cells as the primary source of GDF15, and circulating concentrations of GDF15 are markedly elevated and correlate with disease severity and survival in multiple independent cohorts. Our findings suggest that GDF15 is an epithelial-derived secreted protein that may be a useful biomarker of epithelial stress and identifies IPF patients with poor outcomes.

Sarcoidosis is a systemic granulomatous disease predominantly affecting the lungs. The mechanisms promoting disease pathogenesis and progression are unknown, although interleukin-15 (IL-15) has been associated with the immune-mediated inflammation of sarcoidosis. Because the identification of a mechanistically based, clinically relevant biomarker for sarcoidosis remains elusive, we hypothesized this role for IL-15. Pulmonary sarcoidosis granuloma formation was modeled using trehalose 6,6′-dimicolate (TDM), which was administered into wild-type and three lineages of mice: those overexpressing IL-15, deficient in IL-15, and deficient in IL-15 receptor α. The number of granulomas per lung was counted and normalized to the wild type. IL-15 concentrations were measured in the bronchoalveolar lavage (BAL) from healthy controls and subjects with sarcoidosis in our cohort, where associations between IL-15 levels and clinical manifestations were sought. Findings were validated in another independent sarcoidosis cohort. TDM administration resulted in similar granuloma numbers across all lineages of mice. IL-15 concentrations were elevated in the BAL of both human cohorts, irrespective of disease phenotypes. In exploratory analysis, an association with obesity was observed, and various other soluble mediators were identified in the BAL of both cohorts. Although IL-15 is enriched in the sarcoidosis lung, it was independent of disease pathogenesis or clinical manifestations in our mouse model and human cohorts of sarcoidosis. An association with obesity perhaps reflects the ongoing inflammatory processes of these comorbid conditions. Our findings showed that IL-15 is redundant for disease pathogenesis and clinical progression of sarcoidosis.

Excess macrophages and smooth muscle cells (SMCs) characterize many cardiovascular diseases, but crosstalk between these cell types is poorly defined. Pulmonary hypertension (PH) is a lethal disease in which lung arteriole SMCs proliferate and migrate, coating the normally unmuscularized distal arteriole. We hypothesized that increased macrophage platelet-derived growth factor-B (PDGF-B) induces pathological SMC burden in PH. Our results indicate that clodronate attenuates hypoxia-induced macrophage accumulation, distal muscularization, PH, and right ventricle hypertrophy (RVH). With hypoxia exposure, macrophage Pdgfb mRNA was upregulated in mice, and LysM‑Cre mice carrying floxed alleles for hypoxia-inducible factor 1a, hypoxia-inducible factor 2a, or Pdgfb had reduced macrophage Pdgfb and were protected against distal muscularization and PH. Conversely, LysM‑Cre von-Hippel Lindaufl/fl mice had increased macrophage Hifa and Pdgfb and developed distal muscularization, PH, and RVH in normoxia. Similarly, Pdgfb was upregulated in macrophages from human idiopathic or systemic sclerosis-induced pulmonary arterial hypertension patients, and macrophage-conditioned medium from these patients increased SMC proliferation and migration via PDGF-B. Finally, in mice, orotracheal administration of nanoparticles loaded with Pdgfb siRNA specifically reduced lung macrophage Pdgfb and prevented hypoxia-induced distal muscularization, PH, and RVH. Thus, macrophage-derived PDGF-B is critical for pathological SMC expansion in PH, and nanoparticle-mediated inhibition of lung macrophage PDGF-B has profound implications as an interventional strategy for PH.

Fibrosis is a macrophage-driven process of uncontrolled extracellular matrix accumulation. Neuronal guidance proteins such as netrin-1 promote inflammatory scarring. We found that macrophage-derived netrin-1 stimulates fibrosis through its neuronal guidance functions. In mice, fibrosis due to inhaled bleomycin engendered netrin-1–expressing macrophages and fibroblasts, remodeled adrenergic nerves, and augmented noradrenaline. Cell-specific knockout mice showed that collagen accumulation, fibrotic histology, and nerve-associated endpoints required netrin-1 of macrophage but not fibroblast origin. Adrenergic denervation; haploinsufficiency of netrin-1’s receptor, deleted in colorectal carcinoma; and therapeutic α(1) adrenoreceptor antagonism improved collagen content and histology. An idiopathic pulmonary fibrosis (IPF) lung microarray data set showed increased netrin-1 expression. IPF lung tissues were enriched for netrin-1(+) macrophages and noradrenaline. A longitudinal IPF cohort showed improved survival in patients prescribed α(1) adrenoreceptor blockade. This work showed that macrophages stimulate lung fibrosis via netrin-1–driven adrenergic processes and introduced α(1) blockers as a potentially new fibrotic therapy.

BACKGROUND AND OBJECTIVE Molecular biomarkers are needed to refine prognostication and phenotyping of pulmonary hypertension (PH) patients. S100A12 is an emerging biomarker of various inflammatory diseases. This study aims to determine the prognostic value of S100A12 in PH. METHODS Exploratory microarray analysis performed on peripheral blood mononuclear cells (PBMC) collected from idiopathic pulmonary fibrosis (IPF) patients suggested an association between S100A12 and both PH and mortality. So the current study was designed to evaluate for an association between S100A12 in peripheral blood collected from two well-phenotyped PH cohorts in two other centres to derive and validate an association between S100A12 protein serum concentrations and mortality. RESULTS The majority of the patients in the discovery and validation cohorts were either World Health Organization (WHO) group 1 (pulmonary arterial hypertension (PAH)) or 3 (lung disease-associated) PH. In the discovery PH cohort, S100A12 was significantly increased in patients with PH (n = 51) compared to controls (n = 22) (29.8 vs 15.7 ng/mL, P < 0.001) and negatively correlated with cardiac output (r = -0.58, P < 0.001) in PH patients. When S100A12 data were pooled from both cohorts, PAH and non-PAH PH patients had higher S100A12 compared to healthy external controls (32.6, 30.9, 15.7 ng/mL; P < 0.001). S100A12 was associated with an increased risk in overall mortality in PH patients in both the discovery (n = 51; P = 0.008) and validation (n = 40; P < 0.001) cohorts. CONCLUSION S100A12 levels are increased in PH patients and are associated with increased mortality.

Background Sarcoidosis is a multisystem, chronic granulomatous disease of unknown etiology that predominantly affects the lungs. Pulmonary sarcoidosis classically presents with constitutional symptoms and computed tomographic scan findings of bilateral, symmetric micronodules in a peribronchovascular distribution with upper and middle lung zone predominance accompanied by bilateral, symmetric hilar lymphadenopathy. A solitary lung mass is a rare finding for pulmonary sarcoidosis, and with its associated constitutional symptoms, it strongly mimics a malignancy. We aimed to provide further insight into the broad differential diagnosis of a lung mass by describing our experiences in the care of a patient who presented with clinical and radiographic features of lung cancer who was ultimately found to have an atypical manifestation of stage II pulmonary sarcoidosis. Case presentation A 44-year-old African American woman with a history of childhood asthma and type 2 diabetes mellitus presented with shortness of breath. After being treated for a presumed asthma exacerbation with prednisone, she experienced worsening dyspnea, night sweats, and unintentional weight loss. Further evaluation revealed a large left lower lobe mass and hilar lymphadenopathy. A computed tomography-guided biopsy of the lung mass revealed a multifocal non-necrotizing granuloma with multinucleated giant cells. Although consistent with sarcoidosis, this finding could represent a sarcoid-like reaction secondary to an occult malignancy. A more extensive repeat biopsy via bronchoscopy and mediastinoscopy revealed granulomatous inflammation without evidence of malignancy or infection. These procedures confirmed the diagnosis of pulmonary sarcoidosis, and she was started on treatment with high-dose prednisone. Her treatment course was complicated by hyperglycemia necessitating insulin therapy, but after 3 months of therapy, she reported improvement in her dyspnea, and repeat imaging revealed a significant decrease in the size of the lung mass and lymphadenopathy. Given her clinical and radiographic response, she was continued on a prednisone taper. Conclusions Atypical manifestations of pulmonary sarcoidosis are diagnostically challenging because the clinical and radiographic features of the disease mimic those of a malignancy. We aimed to illustrate a unique etiology of a lung mass and the importance of maintaining a broad differential diagnosis. Nonetheless, with the possibility of a malignancy, a high index of suspicion is necessary for timely diagnosis and optimal management.

Fibrosis is a pathological result of a dysfunctional repair response to tissue injury and occurs in a number of organs, including the lungs1. Cellular metabolism regulates tissue repair and remodeling responses to injury2–4. AMPK is a critical sensor of cellular bioenergetics and controls the switch from anabolic to catabolic metabolism5. However, the role of AMPK in fibrosis is not well understood. In this report, we demonstrate that in the humans with idiopathic pulmonary fibrosis (IPF) and in an experimental mouse model of lung fibrosis, AMPK activity is lower in fibrotic regions associated with metabolically active and apoptosis-resistant myofibroblasts. Pharmacological activation of AMPK in myofibroblasts from lungs of humans with IPF display lower fibrotic activity, along with enhanced mitochondrial biogenesis and normalization of sensitivity to apoptosis. In a bleomycin model of lung fibrosis in mice, metformin therapeutically accelerates the resolution of well-established fibrosis in an AMPK-dependent manner. These studies implicate deficient AMPK activation in non-resolving, pathologic fibrotic processes, and support a role for metformin (or other AMPK activators) to reverse established fibrosis by facilitating deactivation and apoptosis of myofibroblasts.

Idiopathic pulmonary fibrosis (IPF) involves the accumulation of α-smooth muscle actin-expressing myofibroblasts arising from interactions with soluble mediators such as transforming growth factor-β1 (TGF-β1) and mechanical influences such as local tissue stiffness. Whereas IPF fibroblasts are enriched for aerobic glycolysis and innate immune receptor activation, innate immune ligands related to mitochondrial injury, such as extracellular mitochondrial DNA (mtDNA), have not been identified in IPF.We aimed to define an association between mtDNA and fibroblast responses in IPF.We evaluated the response of normal human lung fibroblasts (NHLFs) to stimulation with mtDNA and determined whether the glycolytic reprogramming that occurs in response to TGF-β1 stimulation and direct contact with stiff substrates, and spontaneously in IPF fibroblasts, is associated with excessive levels of mtDNA. We measured mtDNA concentrations in bronchoalveolar lavage (BAL) from subjects with and without IPF, as well as in plasma samples from two longitudinal IPF cohorts and demographically matched control subjects.Exposure to mtDNA augments α-smooth muscle actin expression in NHLFs. The metabolic changes in NHLFs that are induced by interactions with TGF-β1 or stiff hydrogels are accompanied by the accumulation of extracellular mtDNA. These findings replicate the spontaneous phenotype of IPF fibroblasts. mtDNA concentrations are increased in IPF BAL and plasma, and in the latter compartment, they display robust associations with disease progression and reduced event-free survival.These findings demonstrate a previously unrecognized and highly novel connection between metabolic reprogramming, mtDNA, fibroblast activation, and clinical outcomes that provides new insight into IPF.

TOPIC: Chest Infections TYPE: Medical Student/Resident Case Reports INTRODUCTION: The ongoing coronavirus disease 2019 (COVID-19) pandemic has resulted in persistent pulmonary complications among survivors. As our understanding of post infectious pulmonary phenomena continues to evolve, it is clear there are multiple difference manifestations of pulmonary lung disease associated with severe acute respiratory syndrome coronavirus 2 (SARS CoV-2). Here we describe a case of bullous lung disease as a complication of COVID-19. CASE PRESENTATION: A 61-year-old gentleman without significant past medical history presented with worsening shortness of breath of two days duration. Three months prior to presentation he was hospitalized for acute hypoxemic respiratory failure due to COVID-19 requiring Bi-level Positive Airway Pressure which was complicated by pneumomediastinum and right-sided pneumothorax that required chemical pleurodesis. On this presentation, he was hypoxemic and CT scan of the chest showed extensive bullous lung disease (BLD) throughout the right lung with mediastinal shift, not noted on prior imaging. He denied family history of lung disease or connective tissue disease. Prior to COVID-19 infection he was an avid marathon-runner, worked as a civil engineer with no occupational exposures, and never smoked tobacco products, vaped electronic cigarettes, or used illicit drugs. Admission vitals were unremarkable and physical exam revealed decreased breath sounds on the right side. His laboratory data including repeat SARS CoV-2 nasal polymerase chain reaction, alpha-1 antitrypsin and angiotensin-converting enzyme levels were unrevealing. Cardiothoracic surgery was consulted and he successfully underwent Video-Assisted Thoracoscopic surgery with wedge resection of the right lower lobe and chemical pleurodesis. Pathology ruled out a loculated pneumothorax and confirmed the presence of bullae localized within the lung parenchyma. DISCUSSION: Bullous lung disease has been described secondary to cocaine, cigarette or marijuana smoking as well as Emphysema, Sarcoidosis, alpha1-antitrypsin deficiency, Marfan's syndrome, Ehlers-Danlos syndrome and inhaled fiberglass exposure. However, our patient did not have any family history of lung disease, occupational exposures or smoking history, and physical exam was not suggestive of either Marfan's or Ehlers-Danlos syndrome. Since there was no underlying lung disease prior to hospitalization, common etiologies of bullous lung disease were ruled out, and given temporal association with COVID-19 infection, we hypothesized that his lung disease was related to his infection. Although the relationship between bullous lung disease and COVID-19 has yet-to-be defined, case reports have described this emerging association. CONCLUSIONS: Further investigation in the development of chronic lung disease following COVID-19 infection is sorely needed given the growing population of COVID-19 survivors. REFERENCE #1: Berhane S, Tabor A, Sahu A, Singh A. Development of bullous lung disease in a patient with severe COVID-19 pneumonitis. BMJ Case Reports. 2020;13(10):e237455. REFERENCE #2: Sun R, Liu H, Wang X. Mediastinal Emphysema, Giant Bulla, and Pneumothorax Developed during the Course of COVID-19 Pneumonia. Korean J Radiol. 2020;21(5):541-544. REFERENCE #3: Goldberg C, Carey KE. Bullous lung disease. West J Emerg Med. 2013;14(5):450-451. doi:10.5811/westjem.2013.3.16276. DISCLOSURES: No relevant relationships by Kwesi Amoah, source=Web Response No relevant relationships by robert homer, source=Web Response No relevant relationships by Denyse Lutchmansingh, source=Web Response No relevant relationships by Prachi Pednekar, source=Web Response No relevant relationships by Changwan Ryu, source=Web Response

Sarcoidosis is an unpredictable granulomatous disease in which African Americans disproportionately experience aggressive phenotypes. Mitochondrial DNA (mtDNA) released by cells in response to various stressors contributes to tissue remodelling and inflammation. While extracellular mtDNA has emerged as a biomarker in multiple diseases, its relevance to sarcoidosis remains unknown. We aimed to define an association between extracellular mtDNA and clinical features of sarcoidosis.Extracellular mtDNA concentrations were measured using quantitative PCR for the humanMT-ATP6gene in bronchoalveolar (BAL) and plasma samples from healthy controls and patients with sarcoidosis from The Yale Lung Repository; associations betweenMT-ATP6concentrations and Scadding stage, extrapulmonary disease and demographics were sought. Results were validated in the Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis cohort.Relative to controls,MT-ATP6concentrations in sarcoidosis subjects were robustly elevated in the BAL fluid and plasma, particularly in the plasma of patients with extrapulmonary disease. Relative to Caucasians, African Americans displayed excessiveMT-ATP6concentrations in the BAL fluid and plasma, for which the latter compartment correlated with significantly higher odds of extrapulmonary disease.Enrichments in extracellular mtDNA in sarcoidosis are associated with extrapulmonary disease and African American descent. Further study into the mechanistic basis of these clinical findings may lead to novel pathophysiologic and therapeutic insights.

Background: The pathogenesis of scleroderma associated interstitial lung disease (SSc-ILD) involves the uncontrolled differentiation of normal human lung fibroblasts (NHLFs) to alpha-smooth muscle actin (αSMA) expressing myofibroblasts mediated by transforming growth factor-β1 (TGF-β1). SSc-ILD has a highly variable clinical trajectory as some patients experience rapid deterioration in their ventilatory function while others remain stable. The association between the toll-like receptor 9 (TLR9) ligand mitochondrial DNA (mtDNA) and fibroblast activation and clinical outcomes in SSc-ILD has yet to be explored. Methods: NHLFs grown in the absence and presence of TGFβ1, CpG DNA, and chloroquine were assayed for αSMA expression and extracellular mtDNA release using qPCR for the human MT-ATP6 gene. This approach was then used to detect plasma mtDNA concentrations in two SSc-ILD cohorts, Boston and Yale, and demographically matched controls. TLR9 activation was quantified using commercially available human TLR9-expressing HEK 293 cells. Isolation of extracellular vesicles (EVs) were performed in the plasma from controls and Yale SSc-ILD subjects, and EVs were analyzed for mtDNA content and proteomics via mass spectrometry. Findings: TLR9 activity modulates αSMA expression and extracellular mtDNA release. Plasma mtDNA concentrations are increased in two independent SSc-ILD cohorts and activates TLR9. Longitudinal analysis reveals that plasma mtDNA predicts ventilatory decline and is cargoed by EVs. Proteomic analysis reveals a multicellular origin of EVs that involves cellular pathways that could act as mediators of the SSc-ILD state. Interpretation: These findings demonstrate an unrecognized connection with TLR9 activation mediated by extravesicular mtDNA and myofibroblast differentiation and clinical outcomes in SSc-ILD. Further study into the interactions between TLR9 and mtDNA could lead to novel mechanistic and therapeutic insights in this difficult to manage disease. Funding Statement: Parker B. Francis Foundation, Foundation for Sarcoidosis Research, Scleroderma Foundation, American Thoracic Society, National Institutes of Health, Gabriel and Alma Elias Research Fund, and Greenfield Foundation. Declaration of Interests: The authors have no relevant conflicts of interest to disclose. Ethical Approval Statement: All human studies were performed with informed consent on protocols approved by the Institutional Review Board at each institution.

Background: Vascular smooth muscle cells (SMCs) synthesize extracellular matrix (ECM) that contributes to tissue remodeling after revascularization interventions. The cytokine transforming growth factor β (TGF-β) is induced on tissue injury and regulates tissue remodeling and wound healing, but dysregulated signaling results in excess ECM deposition and fibrosis. The LIM (Lin11, Isl-1 & Mec-3) domain protein LIM domain only 7 (LMO7) is a TGF-β1 target gene in hepatoma cells, but its role in vascular physiology and fibrosis is unknown. Methods: We use carotid ligation and femoral artery denudation models in mice with global or inducible smooth muscle–specific deletion of LMO7, and knockout, knockdown, overexpression, and mutagenesis approaches in mouse and human SMC, and human arteriovenous fistula and cardiac allograft vasculopathy samples to assess the role of LMO7 in neointima and fibrosis. Results: We demonstrate that LMO7 is induced postinjury and by TGF-β in SMC in vitro. Global or SMC-specific LMO7 deletion enhanced neointimal formation, TGF-β signaling, ECM deposition, and proliferation in vascular injury models. LMO7 loss of function in human and mouse SMC enhanced ECM protein expression at baseline and after TGF-β treatment. TGF-β neutralization or receptor antagonism prevented the exacerbated neointimal formation and ECM synthesis conferred by loss of LMO7. Notably, loss of LMO7 coordinately amplified TGF-β signaling by inducing expression of Tgfb1 mRNA, TGF-β protein, αv and β3 integrins that promote activation of latent TGF-β, and downstream effectors SMAD3 phosphorylation and connective tissue growth factor. Mechanistically, the LMO7 LIM domain interacts with activator protein 1 transcription factor subunits c-FOS and c-JUN and promotes their ubiquitination and degradation, disrupting activator protein 1–dependent TGF-β autoinduction. Importantly, preliminary studies suggest that LMO7 is upregulated in human intimal hyperplastic arteriovenous fistula and cardiac allograft vasculopathy samples, and inversely correlates with SMAD3 phosphorylation in cardiac allograft vasculopathy. Conclusions: LMO7 is induced by TGF-β and serves to limit vascular fibrotic responses through negative feedback regulation of the TGF-β pathway. This mechanism has important implications for intimal hyperplasia, wound healing, and fibrotic diseases.

Background and objective Idiopathic pulmonary fibrosis (IPF) is a progressive disease with poor prognosis and variable clinical course. Although matrix metalloproteinase-7 (MMP-7) is emerging as an important IPF biomarker, reproducibility across studies is unclear. We aimed to determine whether a previously reported prognostic threshold for MMP-7 was predictive of mortality in an independent cohort of IPF patients. Methods MMP-7 concentrations obtained from heparinized plasma samples were determined by ELISA in 97 patients with IPF and 41 healthy controls. The association of the previously published heparin plasma MMP-7 threshold of 12.1 ng/mL with all-cause mortality or transplant-free survival (TFS) was determined, either as an independent biomarker or as part of the modified personal clinical and molecular mortality index (m-PCMI). Results MMP-7 plasma concentrations were significantly higher in IPF patients compared to healthy controls (14.40 ± 6.55 ng/mL vs 6.03 ± 2.51 ng/mL, P Conclusion This study confirms that MMP-7 concentrations could be used to accurately predict outcomes across cohorts and centres, when similar collection protocols are applied.

Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal interstitial lung disease with a median survival of 3–5 years [1]. Its disease course is highly variable, as some patients experience rapid deterioration in lung function while others experience more gradual decline [2]. The development of acute exacerbation of IPF (AE-IPF), a highly lethal complication of unknown etiology, has been shown to accelerate disease progression [3]. Presently, there are no accepted biomarkers that predict clinical deterioration [4], thus indicating an important, unmet need in the management of this devastating disease. Footnotes This manuscript has recently been accepted for publication in the European Respiratory Journal . It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online. Please open or download the PDF to view this article. Conflict of interest: Dr. Sakamoto reports grants from Japan Society for the Promotion of Science (JSPS), grants from the Satoshi Okamoto Memorial Foundation of Pulmonary Fibrosis, during the conduct of the study; grants from Pulmonary Fibrosis Foundation, grants from Eli Lilly Japan, grants from Boehringer Ingelheim, outside the submitted work. Conflict of interest: Dr. Furukawa has nothing to disclose. Conflict of interest: Dr. Yamano has nothing to disclose. Conflict of interest: Dr. Kataoka has nothing to disclose. Conflict of interest: Dr. Teramachi has nothing to disclose. Conflict of interest: Ms. Walia has nothing to disclose. Conflict of interest: Dr. Suzuki has nothing to disclose. Conflict of interest: Dr. Inoue has nothing to disclose. Conflict of interest: Dr. Nakahara has nothing to disclose. Conflict of interest: Dr. Ryu reports grants from the Boehringer Ingelheim Discovery Award., outside the submitted work. Dr. Ryu reports grants from the Boehringer Ingelheim Discovery Award, outside the submitted work. Conflict of interest: Dr. Hashimoto has nothing to disclose. Conflict of interest: Dr. Kondoh reports personal fees from Asahi Kasei Pharma Corp., personal fees from Boehringer Ingelheim Co., Ltd., personal fees from Janssen Pharmaceutical K.K., personal fees from Eisai inc., personal fees from KYORIN Pharmaceutical Co., Ltd., personal fees from Mitsubishi Tanabe Pharma, personal fees from Novartis Pharma K.K., personal fees from Shionogi & Co., outside the submitted work

Rationale: Airway stabilization for severe, symptomatic tracheobronchomalacia (TBM) may be accomplished by silicone Y-stent placement. Common complications of the Y-stent include mucus plugging and granulation tissue formation. Patient concerns: We describe a rare case of massive hemoptysis originating from a silicone Y-stent placed for TBM. Diagnoses: An emergent bronchoscopy showed an actively bleeding, pulsatile vessel at the distal end of the left bronchial limb of the Y-stent. It was felt that the bleeding was caused by, or at least impacted by, the distal left bronchial limb of the Y-stent eroding into the airway wall. Interventions: We hypothesized that placement of oxidized regenerated cellulose (ORC) would provide initial hemostasis, and the subsequent placement of a biocompatible surgical sealant would lead to definitive resolution. Outcomes: ORC provided sufficient hemostasis and the subsequent synthetic polymer reinforced the tissue for complete cessation of the bleed. Lessons: The combined use of ORC and a biocompatible surgical sealant provided long-term management for life-threatening hemoptysis, and potentially morbid procedures such as embolization or surgery were avoided by advanced endobronchial therapy.

Vascular rings are congenital malformations of the aortic arch. A double aortic arch (DAA), the most common type of vascular ring, results from the failure of the fourth embryonic branchial arch to regress, leading to an ascending aorta that divides into a left and right arch that fuse together to completely encircle the trachea and esophagus. The subsequent DAA causes compressive effects on the trachea and esophagus that typically manifests in infancy or early childhood. Adult presentations, particularly in the elderly, are exceedingly rare. Historically such patients have a long-standing history of dyspnea on exertion and dysphagia, with many assumed to have obstructive lung or intrinsic cardiac disease. We describe a case of an elderly woman who presented with respiratory failure due to DAA. In her case, surgery was not feasible and we describe our experience with airway stenting.