Regenerative Metaplastic Clones in COPD Lung Drive Inflammation and Fibrosis.

Chronic obstructive pulmonary disease (COPD) is a progressive condition of chronic bronchitis, small airway obstruction, and emphysema that represents a leading cause of death worldwide. While inflammation, fibrosis, mucus hypersecretion, and metaplastic epithelial lesions are hallmarks of this disease, their origins and dependent relationships remain unclear. Here we apply single-cell cloning technologies to lung tissue of patients with and without COPD. Unlike control lungs, which were dominated by normal distal airway progenitor cells, COPD lungs were inundated by three variant progenitors epigenetically committed to distinct metaplastic lesions. When transplanted to immunodeficient mice, these variant clones induced pathology akin to the mucous and squamous metaplasia, neutrophilic inflammation, and fibrosis seen in COPD. Remarkably, similar variants pre-exist as minor constituents of control and fetal lung and conceivably act in normal processes of immune surveillance. However, these same variants likely catalyze the pathologic and progressive features of COPD when expanded to high numbers.

High-resolution transcriptomic and epigenetic profiling identifies novel regulators of COPD.

Patients with chronic obstructive pulmonary disease (COPD) are still waiting for curative treatments. Considering its environmental cause, we hypothesized that COPD will be associated with altered epigenetic signaling in lung cells. We generated genome-wide DNA methylation maps at single CpG resolution of primary human lung fibroblasts (HLFs) across COPD stages. We show that the epigenetic landscape is changed early in COPD, with DNA methylation changes occurring predominantly in regulatory regions. RNA sequencing of matched fibroblasts demonstrated dysregulation of genes involved in proliferation, DNA repair, and extracellular matrix organization. Data integration identified 110 candidate regulators of disease phenotypes that were linked to fibroblast repair processes using phenotypic screens. Our study provides high-resolution multi-omic maps of HLFs across COPD stages. We reveal novel transcriptomic and epigenetic signatures associated with COPD onset and progression and identify new candidate regulators involved in the pathogenesis of chronic lung diseases. The presence of various epigenetic factors among the candidates demonstrates that epigenetic regulation in COPD is an exciting research field that holds promise for novel therapeutic avenues for patients.

1-Year Outcomes of Lung Transplantation for Coronavirus Disease 2019-Associated End-Stage Lung Disease in the United States.

BACKGROUND: Lung transplantation can provide quality of life and survival benefits for patients with coronavirus disease 2019 (COVID-19)-associated end-stage lung disease. Characteristics and outcomes of these lung transplant recipients are limited to mostly single-center experiences or provide a short-term follow-up. METHODS: Characteristics of deceased donors and adult lung transplant recipients for COVID-19-associated end-stage lung disease between August-2020 and June-2022 were analyzed using deidentified United Network for Organ Sharing database. Post-transplant patient survival of COVID-19 recipients was analyzed and compared with non-COVID-19 recipients. Secondary outcomes were length of hospitalization, post-transplant complications, and rates of organ rejection. RESULTS: During the study period, 400 lung transplants for COVID-associated end-stage lung disease comprised 8.7% of all lung transplants performed in United States. In the COVID-19 group, Hispanic males received lung transplants at significantly higher rates. The COVID-19 group was younger and had greater need for intensive care unit stay, mechanical ventilation, hemodialysis, extracorporeal membrane oxygenation support, and receipt of antibiotics pre-lung transplant. They had higher lung allocation score, with a shorter wait-list time and received more double lung transplants compared with non-COVID-19 recipients. Post-transplant, the COVID-19 cohort had longer hospital stays, with similar 1-year patient survival (COVID, 86.6% vs non-COVID, 86.3%). Post-transplant, COVID-19-associated deaths were 9.2% of all deaths among lung transplant recipients. CONCLUSIONS: Lung transplantation offers a effective option for carefully selected patients with end-stage lung disease from prior COVID-19, with short-term and long-term outcomes similar to those for lung transplant recipients of non-COVID-19 etiology.

Transcriptomic and Epigenetic Profiling of Fibroblasts in Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF), a devastating, fibroproliferative, chronic lung disorder, is associated with expansion of fibroblasts/myofibroblasts, which leads to excessive production and deposition of extracellular matrix. IPF is typically clinically identified as end-stage lung disease, after fibrotic processes are well-established and advanced. Fibroblasts have been shown to be critically important in the development and progression of IPF. We hypothesize that differential chromatin access can drive genetic differences in IPF fibroblasts relative to healthy fibroblasts. To this end, we performed assay of transposase-accessible chromatin sequencing to identify differentially accessible regions within the genomes of fibroblasts from healthy and IPF lungs. Multiple motifs were identified to be enriched in IPF fibroblasts compared with healthy fibroblasts, including binding motifs for TWIST1 and FOXA1. RNA sequencing identified 93 genes that could be annotated to differentially accessible regions. Pathway analysis of the annotated genes identified cellular adhesion, cytoskeletal anchoring, and cell differentiation as important biological processes. In addition, single nucleotide polymorphism analysis showed that linkage disequilibrium blocks of IPF risk single nucleotide polymorphisms with IPF-accessible regions that have been identified to be located in genes that are important in IPF, including MUC5B, TERT, and TOLLIP. Validation studies in isolated lung tissue confirmed increased expression for TWIST1 and FOXA1 in addition to revealing SHANK2 and CSPR2 as novel targets. Thus, modulation of differential chromatin access may be an important mechanism in the pathogenesis of lung fibrosis.

Characterization of pulmonary vascular remodeling and MicroRNA-126-targets in COPD-pulmonary hypertension.

BACKGROUND: Despite causing increased morbidity and mortality, pulmonary hypertension (PH) in chronic obstructive pulmonary disease (COPD) patients (COPD-PH) lacks treatment, due to incomplete understanding of its pathogenesis. Hypertrophy of pulmonary arterial walls and pruning of the microvasculature with loss of capillary beds are known features of pulmonary vascular remodeling in COPD. The remodeling features of pulmonary medium- and smaller vessels in COPD-PH lungs are less well described and may be linked to maladaptation of endothelial cells to chronic cigarette smoking (CS). MicroRNA-126 (miR126), a master regulator of endothelial cell fate, has divergent functions that are vessel-size specific, supporting the survival of large vessel endothelial cells and inhibiting the proliferation of microvascular endothelial cells. Since CS decreases miR126 in microvascular lung endothelial cells, we set out to characterize the remodeling by pulmonary vascular size in COPD-PH and its relationship with miR126 in COPD and COPD-PH lungs. METHODS: Deidentified lung tissue was obtained from individuals with COPD with and without PH and from non-diseased non-smokers and smokers. Pulmonary artery remodeling was assessed by ⍺-smooth muscle actin (SMA) abundance via immunohistochemistry and analyzed by pulmonary artery size. miR126 and miR126-target abundance were quantified by qPCR. The expression levels of ceramide, ADAM9, and endothelial cell marker CD31 were assessed by immunofluorescence. RESULTS: Pulmonary arteries from COPD and COPD-PH lungs had significantly increased SMA abundance compared to non-COPD lungs, especially in small pulmonary arteries and the lung microvasculature. This was accompanied by significantly fewer endothelial cell markers and increased pro-apoptotic ceramide abundance. miR126 expression was significantly decreased in lungs of COPD individuals. Of the targets tested (SPRED1, VEGF, LAT1, ADAM9), lung miR126 most significantly inversely correlated with ADAM9 expression. Compared to controls, ADAM9 was significantly increased in COPD and COPD-PH lungs, predominantly in small pulmonary arteries and lung microvasculature. CONCLUSION: Both COPD and COPD-PH lungs exhibited significant remodeling of the pulmonary vascular bed of small and microvascular size, suggesting these changes may occur before or independent of the clinical development of PH. Decreased miR126 expression with reciprocal increase in ADAM9 may regulate endothelial cell survival and vascular remodeling in small pulmonary arteries and lung microvasculature in COPD and COPD-PH.

Granulomatous fungal and non-tuberculous mycobacterial infestation complicating chronic lung disease: Outcomes in patients undergoing lung transplantation.

INTRODUCTION: Granulomatous infections are common in patients with chronic lung disease. We aim to study the incidence and clinicopathological features of granulomatous infections in a cohort of patients undergoing lung transplantation for end-stage chronic lung disease. METHODS: Pathology reports of 50 explanted native lungs of patients who underwent lung transplantation since 2015 at our institution were reviewed. Four cases with granulomatous lesions were identified. Correlation was made with clinical findings in the 4 cases. RESULTS: The granulomatous infections include non-necrotizing cryptococcal pneumonitis (case 1), necrotizing pneumonia due to Scedosporium sp. and Mycobacterium avium Complex (MAC) (Cases 2 and 3), and invasive Aspergillus pneumonia (Case 4). One patient received pre-transplant fungal prophylaxis (Case 4). Post-transplant infectious complications included invasive (Cases 2 and 4) and non-invasive (Case 1) fungal infections and bacterial pneumonia (Cases 1 and 2). Two patients (Cases 3 and 4) developed acute cellular rejection (ACR) in the first 30 days. The third patient (Case 1) was identified with ACR in the 9 months post-transplant and chronic lung allograft dysfunction at 29 months. In terms of mortality, 1 patient (Case 1) died at 30 months post-transplant from pseudomonal sepsis and chronic graft failure. Two patients with invasive fungal infections (Cases 2 and 4) are on secondary prophylaxis and doing well. One patient (Case 3) remains infection-free and on MAC prophylaxis. CONCLUSIONS: In our case series, patients with chronic lung diseases with superimposed granulomatous infestations frequently experienced post-transplant complications. These include invasive infections and repeat ACRs that predispose patients to chronic graft dysfunction. Pre- and post-transplant antifungal prophylaxis reduces fungal load and complication risk post-transplant.

Transforming growth factor ß1 alters the 3'-UTR of mRNA to promote lung fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic disease characterized by the pathological remodeling of air sacs as a result of excessive accumulation of extracellular matrix (ECM) proteins, but the mechanism governing the robust protein expression is poorly understood. Our recent findings demonstrate that alternative polyadenylation (APA) caused by NUDT21 reduction is important for the increased expression of fibrotic mediators and ECM proteins in lung fibroblasts by shortening the 3'-untranslated regions (3'-UTRs) of mRNAs and stabilizing their transcripts, therefore activating pathological signaling pathways. Despite the importance of NUDT21 reduction in the regulation of fibrosis, the underlying mechanisms for the depletion are unknown. We demonstrate here that NUDT21 is depleted by TGFß1. We found that miR203, which is increased in IPF, was induced by TGFß1 to target the NUDT21 3'-UTR, thus depleting NUDT21 in human and mouse lung fibroblasts. TGFß1-mediated NUDT21 reduction was attenuated by the miR203 inhibitor antagomiR203 in fibroblasts. TGFß1 transgenic mice revealed that TGFß1 down-regulates NUDT21 in fibroblasts in vivo Furthermore, TGFß1 promoted differential APA of fibrotic genes, including FGF14, RICTOR, TMOD2, and UCP5, in association with increased protein expression. This unique differential APA signature was also observed in IPF fibroblasts. Altogether, our results identified TGFß1 as an APA regulator through NUDT21 depletion amplifying pulmonary fibrosis.

Early clearance vs persistence of de novo donor-specific antibodies following lung transplantation.

BACKGROUND: The natural history of de novo donor-specific antibodies (dnDSA) after lung transplantation is not well-described. We sought to determine the incidence and risk factors associated with dnDSA and compare outcomes between recipients with transient (or isolated) vs persistent dnDSA after transplantation. METHODS: A single-center review of all lung transplants from 1/2009-7/2013. DSAs were tested eight times in the first year and every 4 months thereafter. Outcomes examined included acute rejection and graft failure. RESULTS: Median follow-up was 18 months (range: 1-61 months), and 24.6% of 333 first-time lung-only transplant recipients developed a dnDSA. Ethnicity, HLA-DQ mismatches, post-transplantation platelet transfusion and Lung Allocation Score >60 were associated with dnDSA (P<.05). Overall graft survival was worse for dnDSA-positive vs negative recipients (P=.025). Of 323 recipients with 1-year follow-up, 72 (22.2%) developed dnDSA, and in 25 (34.7%), the dnDSA was transient and cleared. Recipients with transient dnDSA were less likely to develop acute rejection than those with persistent dnDSA (P=.007). CONCLUSIONS: Early post-lung transplantation, dnDSA occurred in 1/4 of recipients, was associated with peri-transplant risk factors and resulted in decreased survival. Spontaneous clearance of dnDSA, seen in one-third of recipients, was associated with a lower risk of acute rejection.

Regulation of IL-4 receptor signaling by STUB1 in lung inflammation.

RATIONALE: IL-4Rα, the common receptor component for IL-4 and IL-13, plays a critical role in IL-4- and IL-13-mediated signaling pathways that regulate airway inflammation and remodeling. However, the regulatory mechanisms underlying IL-4Rα turnover and its signal termination remain elusive. OBJECTIVES: To evaluate the role of STUB1 (STIP1 homology and U-Box containing protein 1) in regulating IL-4R signaling in airway inflammation. METHODS: The roles of STUB1 in IL-4Rα degradation and its signaling were investigated by immunoblot, immunoprecipitation, and flow cytometry. The involvement of STUB1 in airway inflammation was determined in vivo by measuring lung inflammatory cells infiltration, mucus production, serum lgE levels, and alveolar macrophage M2 activation in STUB1(-/-) mice. STUB1 expression was evaluated in airway epithelium of patients with asthma and lung tissues of subjects with chronic obstructive pulmonary disease. MEASUREMENTS AND MAIN RESULTS: STUB1 interacted with IL-4Rα and targeted it for ubiquitination-mediated proteasomal degradation, terminating IL-4 or IL-13 signaling. STUB1 knockout cells showed increased levels of IL-4Rα and sustained STAT6 activation, whereas STUB1 overexpression reduced IL-4Rα levels. Mice deficient in STUB1 had spontaneous airway inflammation, alternative M2 activation of alveolar macrophage, and increased serum IgE. STUB1 levels were increased in airways of subjects with asthma or chronic obstructive pulmonary disease, suggesting that up-regulation of STUB1 might be an important feedback mechanism to dampen IL-4R signaling in airway inflammation. CONCLUSIONS: Our study identified a previously uncharacterized role for STUB1 in regulating IL-4R signaling, which might provide a new strategy for attenuating airway inflammation.

Combined lung and liver transplantation: analysis of a single-center experience.

Patients with end-stage lung disease complicated by cirrhosis are not expected to survive lung transplantation alone. Such patients are potential candidates for combined lung-liver transplantation (CLLT), however few reports document the indications and outcomes after CLLT. This is a review of a large single-center CLLT series. Eight consecutive CLLT performed during 2009-2012 were retrospectively reviewed. One patient received a third simultaneous heart transplant. Mean age was 42.5 ± 11.5 years. Pulmonary indications included cystic fibrosis (CF) (n = 3), idiopathic pulmonary fibrosis (n = 2), α1-antitrypsin deficiency (AATD) (n = 1) and pulmonary hypertension (n = 2). Liver indications were CF (n = 3), hepatitis C (n = 2), AATD (n = 1), cryptogenic (n = 1), and cardiac/congestive (n = 1). Urgency was reflected by median lung allocation score (LAS) of 41 (36.0-89.0) and median predicted FEV1 of 25.7%. Median donor age was 25 (20-58) years with median cold ischemia times of 147 minutes and 6.1 hours for lung and liver, respectively. Overall patient survival at 30 days, 90 days and 1 year was 87.5%, 75.0% and 71.4% respectively. One patient had evidence of acute lung rejection, and no patients had liver allograft rejection. Early postoperative mortalities (90 days) were caused by sepsis in 2 recipients who exhibited the highest LAS of 69.9 and 89.0. The remaining recipients had a median LAS of 39.5 and 100% survival at 1-year. Median length of stay was 25 days (7-181). Complications requiring operative intervention included bile duct ischemia (n = 1) and bile leak (n = 1), ischemia of the bronchial anastomosis (n = 1), and necrotizing pancreatitis with duodenal perforation (n = 1). This series reflects a large single-center CLLT experience. Sepsis is the most common cause of death. The procedure should be considered for candidates with LAS < 50.

Autophagy and role in asthma.

PURPOSE OF REVIEW: Asthma is a common worldwide respiratory illness with significant morbidity and mortality. The disease is characterized by airway inflammation with involvement of multiple biological pathways. Genetic predisposition and increased susceptibility to severe respiratory viral infections are well known clinical features of asthma. Autophagy is an evolutionarily conserved cellular degradation process with significant impact on immunity and antiviral response. In this review we have described the role of autophagy in immune cell survival, proliferation and function. Autophagy has complex effects on immune response involved in inflammation, specifically Th2 immune response. Common respiratory viruses are associated with increased morbidity and mortality in asthmatic patients. RECENT FINDINGS: We describe recent studies showing the effect of autophagy on replication and immune response to common respiratory viruses. The role of autophagy in asthma has recently been investigated. Two studies have been published describing the association of autophagy with asthma. Genetic polymorphism in specific autophagy genes is associated with asthma and influences gene expression in an experimental in-vivo model. SUMMARY: These studies provide us with a window into the possible role of autophagy in asthma and offer new clues to pathogenesis. Modulation of autophagy has the potential to develop into a new therapeutic avenue to treat this common respiratory ailment.

Pulmonary manifestations of amyloidosis.

Amyloidosis is caused by abnormal protein deposition in various tissues, including the lungs. Pulmonary manifestations of amyloidosis may be categorized by areas of involvement, such as parenchymal, large airway and pleural involvement. We describe four distinct manifestations of amyloidosis involving the lung and review their clinical, radiological and pathological features and summarize the evidence for treatment in each of these presentations. We describe alveolar-septal amyloidosis, cystic amyloid lung disease, endobronchial amyloidosis and pleural amyloidosis.

Seroprevalence of Measles, Mumps, Rubella, and Varicella-Zoster Virus and Seroresponse to the Vaccinations in Adult Solid Organ Transplant Candidates.

BACKGROUND: Updating live vaccines such as measles, mumps, rubella, and varicella (MMRV) is an important step in preparing patients for solid organ transplant (SOT) to prevent morbidity from these preventable diseases. However, data for this approach are scarce. Thus, we aimed to describe the seroprevalence of MMRV and the efficacy of the vaccines in our transplant center. METHODS: Pre-SOT candidates >18 y of age were retrospectively retrieved from SOT database in Memorial Hermann Hospital Texas Medical Center. MMRV serologies are routinely screened at the time of pretransplant evaluation. We divided patients into 2 groups: MMRV-positive group versus MMRV-negative group, patients with positive all MMRV serologies and with negative immunity to at least 1 dose of MMRV, respectively. RESULTS: A total of 1213 patients were identified. Three hundred ninety-four patients (32.4%) did not have immunity to at least 1 dose of MMRV. Multivariate analysis was conducted. Older age (odds ratio [OR]: 1.04) and liver transplant candidates (OR: 1.71) were associated with seropositivity. Previous history of SOT (OR: 0.54) and pancreas/kidney transplant candidates (OR: 0.24) were associated with seronegativity. Among 394 MMRV seronegative patients, 60 patients received 1 dose of MMR vaccine and 14 patients received 1 dose of varicella-zoster virus vaccine without severe adverse events. A total of 35% (13/37) of patients who had follow-up serologies did not have a serological response. CONCLUSIONS: A significant number of pre-SOT candidates were not immune to at least 1 dose of MMRV. This highlights the importance of MMRV screening and vaccinations pre-SOT. Postvaccination serological confirmation should be performed to evaluate the necessity for a second dose.

Cloning a profibrotic stem cell variant in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive, irreversible, and rapidly fatal interstitial lung disease marked by the replacement of lung alveoli with dense fibrotic matrices. Although the mechanisms initiating IPF remain unclear, rare and common alleles of genes expressed in lung epithelia, combined with aging, contribute to the risk for this condition. Consistently, single-cell RNA sequencing (scRNA-seq) studies have identified lung basal cell heterogeneity in IPF that might be pathogenic. We used single-cell cloning technologies to generate "libraries" of basal stem cells from the distal lungs of 16 patients with IPF and 10 controls. We identified a major stem cell variant that was distinguished from normal stem cells by its ability to transform normal lung fibroblasts into pathogenic myofibroblasts in vitro and to activate and recruit myofibroblasts in clonal xenografts. This profibrotic stem cell variant, which was shown to preexist in low quantities in normal and even fetal lungs, expressed a broad network of genes implicated in organ fibrosis and showed overlap in gene expression with abnormal epithelial signatures identified in previously published scRNA-seq studies of IPF. Drug screens highlighted specific vulnerabilities of this profibrotic variant to inhibitors of epidermal growth factor and mammalian target of rapamycin signaling as prospective therapeutic targets. This profibrotic stem cell variant in IPF was distinct from recently identified profibrotic stem cell variants in chronic obstructive pulmonary disease and may extend the notion that inappropriate accrual of minor and preexisting stem cell variants contributes to chronic lung conditions.

Post-Lung Transplantation Outcomes and Ex Vivo Histopathological Findings in Severe Post-Covid-19 Pulmonary Disease-A Single-Center Experience.

Background: A significant proportion of patients with severe and persistent coronavirus disease 2019 (COVID-19) require continuous ventilatory support and occasional extracorporeal membrane oxygenation (ECMO) for acute respiratory distress syndrome (ARDS). Lung transplantation is a treatment option for patients who develop severe ARDS. Methods: Our lung transplant database was retrospectively reviewed for patients who underwent lung transplantation for COVID-19 pulmonary disease at Memorial Hermann Hospital, Texas Medical Center, Houston, Texas, from January 2020 to March 2022. We evaluated outcomes of patients who were followed in our clinic at least 6 months post-transplant. Pretransplant patient characteristics, COVID-19-related treatment, histopathology results, and postdischarge course were evaluated. Results: Among a total of 13 lung transplant recipients, 6 consecutive patients were identified who had a minimum of 6 months of follow-up post-lung transplantation. The average age of patients was 55 years, with a male predominance. The median time to transplantation was 111 days. All 6 patients had significant postinfectious complications due to COVID-19 before transplant. Histopathological findings from explanted lungs showed a predominance of fibrotic change. There were no reported cases of rejection or graft dysfunction. 5 patients had minimal to no post-transplant infectious complications. One patient died 218 days post-transplant from infectious complications. Conclusions: Five out of six lung transplant recipients at our institution have demonstrated excellent long-term outcomes after index hospitalization, for a mean follow-up of 13 months post-lung transplantation. Lung transplantation for lung fibrosis due to COVID-19 is an acceptable salvage treatment option. Larger studies are warranted to confirm these findings.

Fulminant lung fibrosis in non-resolvable COVID-19 requiring transplantation.

BACKGROUND: Coronavirus Disease 2019 (COVID-19) can lead to the development of acute respiratory distress syndrome (ARDS). In some patients with non-resolvable (NR) COVID-19, lung injury can progress rapidly to the point that lung transplantation is the only viable option for survival. This fatal progression of lung injury involves a rapid fibroproliferative response and takes on average 15 weeks from initial symptom presentation. Little is known about the mechanisms that lead to this fulminant lung fibrosis (FLF) in NR-COVID-19. METHODS: Using a pre-designed unbiased PCR array for fibrotic markers, we analyzed the fibrotic signature in a subset of NR-COVID-19 lungs. We compared the expression profile against control lungs (donor lungs discarded for transplantation), and explanted tissue from patients with idiopathic pulmonary fibrosis (IPF). Subsequently, RT-qPCR, Western blots and immunohistochemistry were conducted to validate and localize selected pro-fibrotic targets. A total of 23 NR-COVID-19 lungs were used for RT-qPCR validation. FINDINGS: We revealed a unique fibrotic gene signature in NR-COVID-19 that is dominated by a hyper-expression of pro-fibrotic genes, including collagens and periostin. Our results also show a significantly increased expression of Collagen Triple Helix Repeat Containing 1(CTHRC1) which co-localized in areas rich in alpha smooth muscle expression, denoting myofibroblasts. We also show a significant increase in cytokeratin (KRT) 5 and 8 expressing cells adjacent to fibroblastic areas and in areas of apparent epithelial bronchiolization. INTERPRETATION: Our studies may provide insights into potential cellular mechanisms that lead to a fulminant presentation of lung fibrosis in NR-COVID-19. FUNDING: National Institute of Health (NIH) Grants R01HL154720, R01DK122796, R01DK109574, R01HL133900, and Department of Defense (DoD) Grant W81XWH2110032 to H.K.E. NIH Grants: R01HL138510 and R01HL157100, DoD Grant W81XWH-19-1-0007, and American Heart Association Grant: 18IPA34170220 to H.K.-Q. American Heart Association: 19CDA34660279, American Lung Association: CA-622265, Parker B. Francis Fellowship, 1UL1TR003167-01 and The Center for Clinical and Translational Sciences, McGovern Medical School to X.Y.

3'UTR shortening of HAS2 promotes hyaluronan hyper-synthesis and bioenergetic dysfunction in pulmonary hypertension.

Pulmonary hypertension (PH) comprises a diverse group of disorders that share a common pathway of pulmonary vascular remodeling leading to right ventricular failure. Development of anti-remodeling strategies is an emerging frontier in PH therapeutics that requires a greater understanding of the interactions between vascular wall cells and their extracellular matrices. The ubiquitous matrix glycan, hyaluronan (HA), is markedly elevated in lungs from patients and experimental models with PH. Herein, we identified HA synthase-2 (HAS2) in the pulmonary artery smooth muscle cell (PASMC) layer as a predominant locus of HA dysregulation. HA upregulation involves depletion of NUDT21, a master regulator of alternative polyadenylation, resulting in 3'UTR shortening and hyper-expression of HAS2. The ensuing increase of HAS2 and hyper-synthesis of HA promoted bioenergetic dysfunction of PASMC characterized by impaired mitochondrial oxidative capacity and a glycolytic shift. The resulting HA accumulation stimulated pro-remodeling phenotypes such as cell proliferation, migration, apoptosis-resistance, and stimulated pulmonary artery contractility. Transgenic mice, mimicking HAS2 hyper-synthesis in smooth muscle cells, developed spontaneous PH, whereas targeted deletion of HAS2 prevented experimental PH. Pharmacological blockade of HAS2 restored normal bioenergetics in PASMC, ameliorated cell remodeling phenotypes, and reversed experimental PH in vivo. In summary, our results uncover a novel mechanism of HA hyper-synthesis and downstream effects on pulmonary vascular cell metabolism and remodeling.

Sine oculis homeobox homolog 1 plays a critical role in pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal disease with limited treatment options. The role of the developmental transcription factor Sine oculis homeobox homolog 1 (SIX1) in the pathophysiology of lung fibrosis is not known. IPF lung tissue samples and IPF-derived alveolar type II cells (AT2) showed a significant increase in SIX1 mRNA and protein levels, and the SIX1 transcriptional coactivators EYA1 and EYA2 were elevated. Six1 was also upregulated in bleomycin-treated (BLM-treated) mice and in a model of spontaneous lung fibrosis driven by deletion of Telomeric Repeat Binding Factor 1 (Trf1) in AT2 cells. Conditional deletion of Six1 in AT2 cells prevented or halted BLM-induced lung fibrosis, as measured by a significant reduction in histological burden of fibrosis, reduced fibrotic mediator expression, and improved lung function. These effects were associated with increased macrophage migration inhibitory factor (MIF) in lung epithelial cells in vivo following SIX1 overexpression in BLM-induced fibrosis. A MIF promoter-driven luciferase assay demonstrated direct binding of Six1 to the 5'-TCAGG-3' consensus sequence of the MIF promoter, identifying a likely mechanism of SIX1-driven MIF expression in the pathogenesis of lung fibrosis and providing a potentially novel pathway for targeting in IPF therapy.

Clinical and functional recovery in a patient with pulmonary hypertension after bariatric surgery.

Severe pulmonary hypertension (PH) in obese patients pose a challenge to treat despite advances in medical therapeutics. Current treatment options are limited for patients who are not responding to maximal medical therapy. Here, we present a case of multifactorial PH, not responsive to ambrisentan, tadalafil, and treprostinil, even after optimization of cardiac and pulmonary function and had a poor prognosis. She demonstrated weight loss after bariatric surgery, improving her restrictive lung disease, obstructive sleep apnea and PH, and overall functionality. Bariatric surgery may offer a potential therapeutic option, in patients with morbid obesity and PH resistant to maximal medical therapy.