Endothelial Glycocalyx Degradation Patterns in Sepsis-Associated Pediatric Acute Respiratory Distress Syndrome: A Single Center Retrospective Observational Study

BACKGROUND

Sepsis-associated destruction of the pulmonary microvascular endothelial glycocalyx (EGCX) creates a vulnerable endothelial surface, contributing to the development of acute respiratory distress syndrome (ARDS). Constituents of the EGCX shed into circulation, glycosaminoglycans and proteoglycans, may serve as biomarkers of endothelial dysfunction. We sought to define the patterns of plasma EGCX degradation products in children with sepsis-associated pediatric ARDS (PARDS), and test their association with clinical outcomes.

METHODS

We retrospectively analyzed a prospective cohort (2018-2020) of children (≥1 month to <18 years of age) receiving invasive mechanical ventilation for acute respiratory failure for ≥72 h. Children with and without sepsis-associated PARDS were selected from the parent cohort and compared. Blood was collected at time of enrollment. Plasma glycosaminoglycan disaccharide class (heparan sulfate, chondroitin sulfate, and hyaluronan) and sulfation subtypes (heparan sulfate and chondroitin sulfate) were quantified using liquid chromatography tandem mass spectrometry. Plasma proteoglycans (syndecan-1) were measured through an immunoassay.

RESULTS

Among the 39 mechanically ventilated children (29 with and 10 without sepsis-associated PARDS), sepsis-associated PARDS patients demonstrated higher levels of heparan sulfate (median 639 ng/mL [interquartile range, IQR 421-902] vs 311 [IQR 228-461]) and syndecan-1 (median 146 ng/mL [IQR 32-315] vs 8 [IQR 8-50]), both p = 0.01. Heparan sulfate subtype analysis demonstrated greater proportions of N-sulfated disaccharide levels among children with sepsis-associated PARDS (p = 0.01). Increasing N-sulfated disaccharide levels by quartile were associated with severe PARDS (n = 9/29) with the highest quartile including >60% of the severe PARDS patients (test for trend, p = 0.04). Higher total heparan sulfate and N-sulfated disaccharide levels were independently associated with fewer 28-day ventilator-free days in children with sepsis-associated PARDS (all p < 0.05).

CONCLUSIONS

Children with sepsis-associated PARDS exhibited higher plasma levels of heparan sulfate disaccharides and syndecan-1, suggesting that EGCX degradation biomarkers may provide insights into endothelial dysfunction and PARDS pathobiology.

Efficacy and safety of an inhaled pan-Janus kinase inhibitor, nezulcitinib, in hospitalised patients with COVID-19: results from a phase 2 clinical trial

BACKGROUND

The inhaled lung-selective pan-Janus kinase inhibitor nezulcitinib had favourable safety and potential efficacy signals in part 1 of a phase 2 trial in patients with severe COVID-19, supporting progression to part 2.

METHODS

Part 2 was a randomised, double-blind phase 2 study (NCT04402866). Hospitalised patients aged 18-80 years with confirmed symptomatic COVID-19 requiring supplemental oxygen (excluding baseline invasive mechanical ventilation) were randomised 1:1 to nebulised nezulcitinib 3 mg or placebo for up to 7 days with background standard-of-care therapy (including corticosteroids). Efficacy endpoints included respiratory failure-free (RFF) days through day 28 as the primary endpoint. Secondary endpoints included safety and change from baseline oxygen saturation (SaO2)/fraction of inspired oxygen (FiO2) ratio on day 7, and 28-day mortality rate was a prespecified exploratory endpoint.

RESULTS

Between June 2020 and April 2021, 205 patients were treated (nezulcitinib, 103; placebo, 102). There was no statistically significant difference between nezulcitinib versus placebo in the primary endpoint (RFF days; median, 21.0 vs 21.0; p=0.6137) or secondary efficacy endpoints. Nezulcitinib was generally well tolerated with a favourable safety profile.

CONCLUSIONS

Although the prespecified primary, secondary and exploratory efficacy endpoints, including RFF through day 28, change from baseline SaO2/FiO2 ratio on day 7, and 28-day mortality rate, were not met, nezulcitinib was generally well tolerated and had a favourable safety profile. Further studies are required to determine if treatment with nezulcitinib confers clinical benefit in specific inflammatory biomarker-defined populations of patients with COVID-19.

Target organ expression and biomarker characterization of chemokine CCL21 in systemic sclerosis associated pulmonary arterial hypertension

Introduction

Systemic sclerosis (SSc) is a heterogenous disorder that appears to result from interplay between vascular pathologies, tissue fibrosis and immune processes, with evidence for deregulation of chemokines, which normally control immune trafficking. We recently identified altered levels of chemokine CCL21 in SSc associated pulmonary arterial hypertension (PAH). Here, we aimed to define target organ expression and biomarker characteristics of CCL21.

Materials and methods

To investigate target organ expression of CCL21, we performed immunohistochemistry (IHC) on explanted lung tissues from SSc-PAH patients. We assessed serum levels of CCL21 by ELISA and Luminex in two well-characterized SSc cohorts from Oslo (OUH, n=552) and Zurich (n=93) University hospitals and in 168 healthy controls. For detection of anti-CCl21 antibodies, we performed protein array analysis applying serum samples from SSc patients (n=300) and healthy controls. To characterize circulating CCL21 in SSc, we applied immunoprecipitation (IP) with antibodies detecting both full length and tailless and a custom-made antibody detecting only the C-terminal of CCL21. IP products were analyzed by SDS-PAGE/western blot and Mass spectrometry (MS).

Results

By IHC, we found that CCL21 was mainly expressed in the airway epithelial cells of SSc patients with PAH. In the analysis of serum levels of CCL21 we found weak correlation between Luminex and ELISA (r=0.515, p<0.001). Serum levels of anti-CCL21 antibodies were higher in SSc patients than in healthy controls (p<0.001), but only 5% of the SSc population were positive for anti-CCL21 antibodies in SSc, and we found no correlation between anti-CCl21 and serum levels of CCL21. By MS, we only identified peptides located within amino acid (aa) 23-102 of CCL21, indicating that CCL21 in SSc circulate as a truncated protein without the C-terminal tail.

Conclusion

This study demonstrates expression of CCL21 in epithelial lung tissue from SSc patients with PAH, and indicate that CCL21 in SSc circulates as a truncated protein. We extend previous observations indicating biomarker potential of CCL21, but find that Luminex is not suitable as platform for biomarker analyses. Finally, in vivo generated anti-CCL21 antibodies exist in SSc, but do not appear to modify serum CCL21 levels in patients with SSc-PAH.

POS0925 HIGH LEVELS OF BOTH CCL2 AND CCL17 WERE ASSOCIATED WITH MORE SEVERE SSc-ILD

Background

Systemic sclerosis (SSc) carries a high risk for progressive interstitial lung disease (ILD). Several anti-inflammatory therapies have been used to treat SSc-ILD and recently the first antifibrotic therapy has been approved. Personalized treatment strategies are largely missing to date. The two chemokines, CCL2 (MCP-1) and CCL17 (TARC), have been shown to be markers of inflammation and fibrosis, respectively.

Objectives

To examine associations between ILD severity and serum levels of CCL2 and CCL17 in two different but complementary sources of biomaterial.

Methods

Sera from the prospective Oslo University Hospital SSc cohort (n=371) and healthy blood donor controls (HC; n=100) and lung tissue at the time of lung transplantation from UCLA SSc-ILD patients (n = 12) and healthy donors (n = 12) were analyzed for CCL2 and CCL17 by multiplex assays. CCL2 and CCL17 levels were defined in serum as high or low using 95% CI in HC sera as cut-off values. Paired pulmonary function tests and HRCT images were obtained at baseline and follow-up. ILD was diagnosed on HRCT and categorized by the extent of lung fibrosis as limited (<10%) or extensive (>10%) ILD. Cellular sources of CCL-2 and CCL-17 in lung tissues were determined by immunohistochemistry. Descriptive statistics were applied.

Results

CCL2 and CCL17 were increased in SSc in sera and in lung tissue compared to HC (Figure 1). High levels of CCL17 (>700 pg/ml) and CCL2 (>1000pg/ml) in sera were identified in 43/254 (17%) and 84/471(18%) of the SSc patients (Table 1 and Figure 1). High levels of both CCL17 and CCL2 were associated with lower FVC at baseline and higher extent of lung fibrosis on HRCT (Table 1). Of those with high CCL2 and CCL17, 67% had extensive lung fibrosis. Categorization of ILD into no ILD, limited or extensive ILD showed an association between high CCL17 levels and the extent of fibrosis (Table 1). Reactive epithelium and macrophages and plasma cells expressed TARC, while more AM and infiltrating mononuclear cells expressed CCL-2.

Conclusion

High levels of both CCL17 and CCL2 were associated with more severe ILD and expressed in end-stage kung tissue and may reflect an ongoing inflammatory and fibrotic processes in SSc-ILD. This may have an implication on treatment choices for SSc-ILD.

Disclosure of Interests

Imon Barua: None declared, Vyacheslav Palchevskiy: None declared, Håvard Fretheim Shareholder of: non-financial support from GSK and

Actelion, outside the submitted work.,, Consultant of: Consultant of: Personal fees from Bayer and non-financial support from GSK and Actelion, outside the submitted work.,, Henriette Didriksen: None declared, Torhild Garen: None declared, Trond Mogens Aaløkken: None declared, Stephen Samuel Weigt: None declared, Øyvind Molberg: None declared, John Belperio: None declared, Anna-Maria Hoffmann-Vold Speakers bureau: Actelion, Boehringer Ingelheim, Jansen, Lilly, Medscape, Merck Sharp & Dohme, Roche,, Consultant of: Actelion, ARXX therapeutics, Bayer, Janssen,, MSD, Lilly, Roche, Boehringer-Ingelheim, Medscape.,,, Grant/research support from: Boehringer Ingelheim

The ZIP8/SIRT1 axis regulates alveolar progenitor cell renewal in aging and idiopathic pulmonary fibrosis

AbstractType 2 alveolar epithelial cells (AEC2s) function as progenitor cells in the lung. We have shown previously that failure of AEC2 regeneration results in progressive lung fibrosis in mice and is a cardinal feature of idiopathic pulmonary fibrosis (IPF). In this study, we identified a deficiency of a specific zinc transporter SLC39A8 (ZIP8) in AEC2s from both IPF lungs and lungs of old mice. Loss of ZIP8 expression was associated with impaired renewal capacity of AEC2s and enhanced lung fibrosis. ZIP8 regulation of AEC2 progenitor function was dependent on SIRT1. Replenishment with exogenous zinc and SIRT1 activation promoted self-renewal and differentiation of AEC2s from lung tissues of IPF patients and old mice. Deletion of Zip8 in AEC2s in mice impaired AEC2 renewal, increased susceptibility of the mice to bleomycin injury, and the mice developed spontaneous lung fibrosis. Therapeutic strategies to restore zinc metabolism and appropriate SIRT1 signaling could improve AEC2 progenitor function and mitigate ongoing fibrogenesis.

Predictive value of chart-based frailty evaluation for lung transplant candidates

Frailty, defined as a state of decreased physiologic reserve, has been correlated with poorer outcomes after hospitalization or surgery. Studies in lung transplant patients have associated frailty with an increased risk of post-transplant mortality; however, a unified approach is lacking. The identification of frail patients can help clinicians pre-emptively target modifiable risk factors and may facilitate risk stratification. The Frailty Risk Score (FRS) is a chart review-based approach based on eight symptoms and four laboratory biomarkers. We applied this method in a retrospective study to investigate its utility in predicting post-transplant lung outcomes. Eighty-four lung transplant recipients were evaluated, including 51 older (≥ 60) and 33 younger (< 60) patients. Median FRS score was 3.9, with 63 categorized as frail (75%) and 21 as non-frail (25%), using a previously published cut-off of ≥3 to define frailty. A high FRS was associated with readmission in the first year after transplantation and with the number of readmissions. There was also an association between FRS score and death (p = .047). FRS may be a viable tool in the assessment of lung transplant candidates. Frail patients may benefit from earlier referral and targeted therapy prior to transplant, as well as close post-transplant follow-up.

Categorization of lung mesenchymal cells in development and fibrosis

Pulmonary mesenchymal cells are critical players in both the mouse and human during lung development and disease states. They are increasingly recognized as highly heterogeneous, but there is no consensus on subpopulations or discriminative markers for each subtype. We completed scRNA-seq analysis of mesenchymal cells from the embryonic, postnatal, adult and aged fibrotic lungs of mice and humans. We consistently identified and delineated the transcriptome of lipofibroblasts, myofibroblasts, smooth muscle cells, pericytes, mesothelial cells, and a novel population characterized by Ebf1 expression. Subtype selective transcription factors and putative divergence of the clusters during development were described. Comparative analysis revealed orthologous subpopulations with conserved transcriptomic signatures in murine and human lung mesenchymal cells. All mesenchymal subpopulations contributed to matrix gene expression in fibrosis. This analysis would enhance our understanding of mesenchymal cell heterogeneity in lung development, homeostasis and fibrotic disease conditions.

Association of Lymphangiogenic Factors With Pulmonary Arterial Hypertension in Systemic Sclerosis

OBJECTIVE

Pulmonary arterial hypertension (PAH) is a major complication in systemic sclerosis (SSc), a disease marked by vascular and lymphatic vessel abnormalities. This study was undertaken to assess the role of the lymphangiogenic factors vascular endothelial growth factor C (VEGF-C) and angiopoietin 2 (Ang-2) and the soluble forms of their respective cognate receptors, soluble VEGF receptor 3 (sVEGFR-3) and soluble TIE-2, in patients with SSc, and to evaluate their predictive ability as markers for PAH development in SSc.

METHODS

In this cohort study, we used multiplex bead assays to assess serum levels of lymphangiogenic factors in 2 well-characterized SSc cohorts: an unselected identification cohort of SSc patients from Oslo University Hospital (n = 371), and a PAH-enriched validation cohort of SSc patients from Zurich University Hospital and Oslo University Hospital (n = 149). As controls for the identification and validation cohorts, we obtained serum samples from 100 healthy individuals and 68 healthy individuals, respectively. Patients in whom SSc-related PAH was identified by right-sided heart catheterization (RHC) in both cohorts were studied in prediction analyses. PAH was defined according to the European Society of Cardiology/European Respiratory Society 2015 guidelines for the diagnosis and treatment of PAH. Associations of serum levels of lymphangiogenic factors with the risk of PAH development were assessed in logistic regression and Cox regression analyses. Associations in Cox regression analyses were expressed as the hazard ratio (HR) with 95% confidence interval (95% CI).

RESULTS

In the identification cohort, SSc patients had lower mean serum levels of VEGF-C and higher mean serum levels of Ang-2 compared to healthy controls (for VEGF-C, mean ± SD 2.1 ± 0.5 ng/ml in patients versus 2.5 ± 0.4 ng/ml in controls; for Ang-2, mean ± SD 6.1 ± 7.6 ng/ml in patients versus 2.8 ± 1.8 ng/ml in controls; each P < 0.001); these same trends were observed in SSc patients with PAH compared to those without PAH. The association of serum VEGF-C levels with SSc-PAH was confirmed in the PAH-enriched RHC validation cohort. For prediction analyses, we assembled all 251 cases of SSc-PAH identified by RHC from the identification and validation cohorts. In multivariable Cox regression analyses adjusted for age and sex, the mean serum levels of VEGF-C and sVEGFR-3 were predictive of PAH development in patients with SSc (for VEGF-C, HR 0.53 [95% CI 0.29-0.97], P = 0.04; for sVEGFR-3, HR 1.21 [95% CI 1.01-1.45], P = 0.042).

CONCLUSION

These findings support the notion that lymphangiogenesis is deregulated during PAH development in SSc, and indicate that VEGF-C could be a promising marker for early PAH detection in patients with SSc.

THU0189 EFFICACY AND SAFETY OF NINTEDANIB IN PATIENTS WITH AUTOIMMUNE DISEASE-RELATED INTERSTITIAL LUNG DISEASE TREATED WITH DMARDS AND/OR GLUCOCORTICOIDS AT BASELINE

Background:

In the INBUILD trial in patients with progressive fibrosing ILDs, nintedanib reduced the rate of decline in forced vital capacity (FVC) vs placebo over 52 weeks in the overall population and in the subgroup with autoimmune disease-related ILDs. Patients taking stable doses of medications to treat RA or CTD were eligible, but the protocol excluded enrolment of patients treated with azathioprine, cyclosporine, mycophenolate, tacrolimus, rituximab, cyclophosphamide, or oral glucocorticoids >20 mg/day.

Objectives:

Assess the influence of DMARDs and/or glucocorticoids at baseline on the efficacy and safety of nintedanib in patients with progressive autoimmune disease-related ILDs.

Methods:

In patients with progressive autoimmune disease-related ILDs in the INBUILD trial, the rate of decline in FVC (mL/year) and adverse events (AEs) over 52 weeks of treatment (or until 28 days after last trial drug intake for patients who discontinued drug before week 52) were assessed in subgroups by use of DMARDs and/or glucocorticoids (any dose) at baseline (yes/no).

Results:

170 patients in the INBUILD trial (82 nintedanib, 88 placebo) had autoimmune disease-related ILDs (89 RA-ILD, 39 SSc-ILD, 19 MCTD-ILD, 23 other). The baseline characteristics of patients taking (n=131) and not taking (n=39) DMARDs and/or glucocorticoids are shown in the Table. All but 1 patient taking glucocorticoids at baseline was taking <20 mg/day. The mean (SE) annual rate of decline in FVC in the placebo group was numerically greater in patients taking vs not taking DMARDs and/or glucocorticoids at baseline (Figure). The effect of nintedanib vs placebo on reducing the rate of decline in FVC was numerically more pronounced in patients taking vs not taking DMARDs and/or glucocorticoids at baseline, but the treatment-by-subgroup-by-time interaction p-values did not indicate heterogeneity in the effect of nintedanib between subgroups (Figure). In patients taking vs not taking DMARDs and/or corticosteroids at baseline, respectively, diarrhoea was reported in 59.4% and 77.8% of patients treated with nintedanib and 28.4% and 23.8% of patients treated with placebo. Serious AEs were more frequent in patients taking vs not taking DMARDs and/or glucocorticoids at baseline in both the nintedanib (39.1% vs 16.7%) and placebo (35.8% vs 19.0%) groups.

Conclusion:

In the INBUILD trial, the rate of FVC decline was numerically greater in placebo-treated patients who were taking DMARDs and/or glucocorticoids at baseline than in those who were not. The rate of FVC decline was slower in patients treated with nintedanib than placebo both in patients who were and were not taking DMARDs and/or glucocorticoids at baseline. Nintedanib had an acceptable safety profile both in patients who were and were not using DMARDs and/or glucocorticoids at baseline.

DMARDs and/or glucocorticoids at baselineYes (n=131)No (n=39)Male, %51.930.8FVC, mL, mean (SD)2372 (718)2188 (619)ILD diagnosis, %RA-ILD60.325.6SSc-ILD15.348.7MCTD-ILD10.712.8Other13.712.8Biologic DMARDs, %15.3–Non-biologic DMARDs, %46.6–Glucocorticoids, %87.8–

Disclosure of Interests:

Martin Aringer Consultant of: Boehringer Ingelheim, Roche, Speakers bureau: Boehringer Ingelheim, Roche, Janet Pope Grant/research support from: AbbVie, Bristol-Myers Squibb, Eli Lilly & Company, Merck, Roche, Seattle Genetics, UCB, Consultant of: AbbVie, Actelion, Amgen, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Eicos Sciences, Eli Lilly & Company, Emerald, Gilead Sciences, Inc., Janssen, Merck, Novartis, Pfizer, Roche, Sandoz, Sanofi, UCB, Speakers bureau: UCB, Clive Kelly Consultant of: Boehringer Ingelheim, Speakers bureau: Boehringer Ingelheim, Anna-Maria Hoffmann-Vold Grant/research support from: Boehringer Ingelheim, Consultant of: Boehringer Ingelheim, Actelion, Bayer, GlaxoSmithKline, Speakers bureau: Boehringer Ingelheim, Actelion, Roche, John Belperio: None declared, Alexandra James Employee of: Employee of Boehringer Ingelheim, Carl Coeck Employee of: Employee of Boehringer Ingelheim, Manuel Quaresma Employee of: Employee of Boehringer Ingelheim, Eric Matteson Grant/research support from: Pfizer, Consultant of: Boehringer Ingelheim, Gilead, TympoBio, Arena Pharmaceuticals, Speakers bureau: Simply Speaking

Highlights from the clinical trials in organ transplantation (CTOT)-20 and CTOT-22 Consortium studies in lung transplant

Long-term survival after lung transplant lags behind that of other commonly transplanted organs, reflecting the current incomplete understanding of the mechanisms involved in the development of posttransplant lung injury, rejection, infection, and chronic allograft dysfunction. To address this unmet need, 2 ongoing National Institute of Allergy and Infectious Disease funded studies through the Clinical Trials in Organ Transplant Consortium (CTOT) CTOT-20 and CTOT-22 were dedicated to understanding the clinical factors and biological mechanisms that drive chronic lung allograft dysfunction and those that maintain cytomegalovirus polyfunctional protective immunity. The CTOT-20 and CTOT-22 studies enrolled 800 lung transplant recipients at 5 North American centers over 3 years. Given the number and complexity of subjects included, CTOT-20 and CTOT-22 utilized innovative data transfers and capitalized on patient-entered data collection to minimize site manual data entry. The data were coupled with an extensive biosample collection strategy that included DNA, RNA, plasma, serum, bronchoalveolar lavage fluid, and bronchoalveolar lavage cell pellet. This Special Article describes the CTOT-20 and CTOT-22 protocols, data and biosample strategy, initial results, and lessons learned through study execution.

The Effect of Monthly Anti-CD25+ Treatment with Basiliximab on the Progression of Chronic Renal Dysfunction after Lung Transplantation

BACKGROUND

Chronic renal dysfunction (CRD), as predominantly related to calcineurin-inhibitor (CNI) nephrotoxicity, is associated with increased morbidity and mortality after lung transplantation (LTx). Basiliximab (BSX), a recombinant chimeric monoclonal antibody against CD25⁺ on activated T-lymphocytes, although often employed as an "induction immunosuppression" after solid organ transplantation, may further allow for reduction in CNI exposure with monthly administration and amelioration of CRD.

OBJECTIVE

To determine the effect of monthly anti-CD25⁺ treatment with basiliximab on the progression of chronic renal dysfunction after lung transplantation.

METHODS

Post-LTx recipients with stages IIIB-V CRD were treated with monthly intravenous infusion of BSX 20 mg. They were analyzed for creatinine clearance at 1, 3, 6, and 12 months; rate of the change in the clearance (the slope of the regression line) and FEV₁/month; de novo HLA class I or II DSA; and infectious events (IE). Tacrolimus (TAC) trough levels were concurrently targeted at 2-4 ng/mL during BSX therapy. The criteria for BSX discontinuation included acute lung allograft rejection, acute respiratory infection, and progression to end-stage renal disease (ESRD).

RESULTS

9 LTx recipients were treated with BSX for ≥6 months. The median time past after their LTx was 1853 (range: 75-7212) days; the mean±SD age was 64.3±11.3 years; the male:female ratio was 7:2. The baseline mean±SD creatinine clearance 1-3 months prior to BSX initiation was 22.8±5.14 mL/min/1.73 m² (CI: 3.95) consistent with CRD stages-IIIB (2), IV (6), and V (1). Prior to BSX treatment, all 9 patients had established CLAD-obstructive-phenotype (BOS, n=4) and restrictive-phenotype (RAS, n=5). During the course of BSX treatment, the aggregate creatinine clearance mean slope increased by a mean±SD of 0.747±0.467 mL/min/1.72 m²/month (CI: 0.359), consistent with "stabilization" of renal function in 7 patients; deterioration occurred in 2 with transition to chronic hemodialysis. Spirometric stability in lung allograft function was observed in 5 patients with a mean±SD aggregate FEV₁ slope of -1.49±1.08 mL/month (CI: 2.50). 3 deaths occurred due to the following conditions during BSX treatment-HFpEF/Sepsis + CLAD/Parainfluenza type 2 bronchiolitis + CLAD. 2 recipients developed "weak MFI" HLA class II DSA; no HLA class I DSA was detected during the treatment.

CONCLUSION

Renal sparing therapy with monthly BSX infusion with concurrent reduction in CNI exposure (TAC = 2-4 ng/mL) for stages IIIB-V CRD was associated with stability in creatinine clearance in 78% of patients over a treatment course of 6-12 months. Pre-existing CLAD afflicting all patients and inherent variability in progression of chronic rejection, limits our assessment of BSX efficacy in this context. We detected an infrequent de novo HLA class II DSA during BSX therapy.

Multiscale light-sheet for rapid imaging of cardiopulmonary system

The ability to image tissue morphogenesis in real-time and in 3-dimensions (3-D) remains an optical challenge. The advent of light-sheet fluorescence microscopy (LSFM) has advanced developmental biology and tissue regeneration research. In this review, we introduce a LSFM system in which the illumination lens reshapes a thin light-sheet to rapidly scan across a sample of interest while the detection lens orthogonally collects the imaging data. This multiscale strategy provides deep-tissue penetration, high-spatiotemporal resolution, and minimal photobleaching and phototoxicity, allowing in vivo visualization of a variety of tissues and processes, ranging from developing hearts in live zebrafish embryos to ex vivo interrogation of the microarchitecture of optically cleared neonatal hearts. Here, we highlight multiple applications of LSFM and discuss several studies that have allowed better characterization of developmental and pathological processes in multiple models and tissues. These findings demonstrate the capacity of multiscale light-sheet imaging to uncover cardiovascular developmental and regenerative phenomena.

Bronchiolitis obliterans syndrome susceptibility and the pulmonary microbiome

BACKGROUND

Lung transplantation outcomes remain complicated by bronchiolitis obliterans syndrome (BOS), a major cause of mortality and retransplantation for patients. A variety of factors linking inflammation and BOS have emerged, meriting further exploration of the microbiome as a source of inflammation. In this analysis, we determined features of the pulmonary microbiome associated with BOS susceptibility.

METHODS

Bronchoalveolar lavage (BAL) samples were collected from 25 patients during standard of care bronchoscopies before BOS onset. Microbial DNA was isolated from BAL fluid and prepared for metagenomics shotgun sequencing. Patient microbiomes were phenotyped using k-means clustering and compared to determine effects on BOS-free survival.

RESULTS

Clustering identified 3 microbiome phenotypes: Actinobacteria dominant (AD), mixed, and Proteobacteria dominant. AD microbiomes, distinguished by enrichment with Gram-positive organisms, conferred reduced odds and risks for patients to develop acute rejection and BOS compared with non-AD microbiomes. These findings were independent of treatment models. Microbiome findings were correlated with BAL cell counts and polymorphonuclear cell percentages.

CONCLUSIONS

In some populations, features of the microbiome may be used to assess BOS susceptibility. Namely, a Gram-positive enriched pulmonary microbiome may predict resilience to BOS.

Chronic Lung Allograft Dysfunction: Evolving Concepts and Therapies

Lung transplantation has become an established therapeutic option for a variety of end-stage lung diseases. Technical advances in graft procurement, implantation, perioperative care, immunosuppression, and posttransplant medical management have led to significant improvements in 1-year survival, but outcomes after the first year have improved minimally over the last two decades. The main limitation to better long-term survival after lung transplantation is chronic lung allograft dysfunction (CLAD). CLAD also impairs quality of life and increases the costs of medical care. Our understanding of CLAD manifestations, risk factors, and mechanisms is rapidly evolving. Recognition of different CLAD phenotypes (e.g., bronchiolitis obliterans syndrome and restrictive allograft syndrome) and the unique pathogenic mechanisms will be important for developing novel therapies. In addition to alloimmune-mediated rejection, we now recognize the importance of alloimmune-independent mechanisms of injury to the allograft. CLAD is the consequence of dysregulated repair of allograft injury. Unfortunately, currently available therapies for CLAD are usually not effective. However, the advances in knowledge, reviewed in this manuscript, should lead to novel strategies for CLAD prevention and treatment, as well as improvement in long-term outcomes after lung transplantation. We provide an overview of the evolving terminology related to CLAD, its varying clinical phenotypes and their diagnosis, natural history, pathogenesis, and potential treatments.

Hyperoxia treatment of TREK-1/TREK-2/TRAAK-deficient mice is associated with a reduction in surfactant proteins

We previously proposed a role for the two-pore domain potassium (K2P) channel TREK-1 in hyperoxia (HO)-induced lung injury. To determine whether redundancy among the three TREK isoforms (TREK-1, TREK-2, and TRAAK) could protect from HO-induced injury, we now examined the effect of deletion of all three TREK isoforms in a clinically relevant scenario of prolonged HO exposure and mechanical ventilation (MV). We exposed WT and TREK-1/TREK-2/TRAAK-deficient [triple knockout (KO)] mice to either room air, 72-h HO, MV [high and low tidal volume (TV)], or a combination of HO + MV and measured quasistatic lung compliance, bronchoalveolar lavage (BAL) protein concentration, histologic lung injury scores (LIS), cellular apoptosis, and cytokine levels. We determined surfactant gene and protein expression and attempted to prevent HO-induced lung injury by prophylactically administering an exogenous surfactant (Curosurf). HO treatment increased lung injury in triple KO but not WT mice, including an elevated LIS, BAL protein concentration, and markers of apoptosis, decreased lung compliance, and a more proinflammatory cytokine phenotype. MV alone had no effect on lung injury markers. Exposure to HO + MV (low TV) further decreased lung compliance in triple KO but not WT mice, and HO + MV (high TV) was lethal for triple KO mice. In triple KO mice, the HO-induced lung injury was associated with decreased surfactant protein (SP) A and SPC but not SPB and SPD expression. However, these changes could not be explained by alterations in the transcription factors nuclear factor-1 (NF-1), NKX2.1/thyroid transcription factor-1 (TTF-1) or c-jun, or lamellar body levels. Prophylactic Curosurf administration did not improve lung injury scores or compliance in triple KO mice.

Cardiac Involvement in Sarcoidosis: Evolving Concepts in Diagnosis and Treatment

Clinically evident sarcoidosis involving the heart has been noted in at least 2 to 7% of patients with sarcoidosis, but occult involvement is much higher (> 20%). Cardiac sarcoidosis is often not recognized antemortem, as sudden death may be the presenting feature. Cardiac involvement may occur at any point during the course of sarcoidosis and may occur in the absence of pulmonary or systemic involvement. Sarcoidosis can involve any part of the heart, with protean manifestations. Prognosis of cardiac sarcoidosis is related to the extent and site(s) of involvement. Most deaths due to cardiac sarcoidosis are due to arrhythmias or conduction defects, but granulomatous infiltration of the myocardium may be lethal. The definitive diagnosis of isolated cardiac sarcoidosis is difficult. The yield of endomyocardial biopsies is low; treatment of cardiac sarcoidosis is often warranted even in the absence of histologic proof. Radionuclide scans are integral to the diagnosis. Currently, 18F-fluorodeoxyglucose–positron emission tomography/computed tomography and gadolinium-enhanced magnetic resonance imaging scans are the key imaging modalities to diagnose cardiac sarcoidosis. The prognosis of cardiac sarcoidosis is variable, but mortality rates of untreated cardiac sarcoidosis are high. Although randomized therapeutic trials have not been done, corticosteroids (alone or combined with additional immunosuppressive medications) remain the mainstay of treatment. Because of the potential for sudden cardiac death, implantable cardioverter defibrillators should be placed in any patient with cardiac sarcoidosis and serious ventricular arrhythmias or heart block, and should be considered for cardiomyopathy. Cardiac transplantation is a viable option for patients with end-stage cardiac sarcoidosis refractory to medical therapy.

Inflammatory Mediators and Clinical Outcome in Patients With Advanced Heart Failure Receiving Cardiac Resynchronization Therapy

Expression of different cytokines and growth factors after myocardial injury has been associated with fibroplasia and dilatation versus reverse remodeling and myocardial repair. Specifically, the proinflammatory/fibrotic mediators: interleukin (IL)-6, epidermal growth factor, and fibroblast growth factor (FGF)-2 cause fibroplasia, whereas reparative cytokines including: IL-1α, IL-1β, IL-4, and IL-13 can limit fibrosis. In appropriate patients, cardiac resynchronization therapy (CRT) reverses cardiomyopathy and improves outcome. However, a significant proportion will not respond to this therapy. We conducted this study to assess the association of proinflammatory/fibrotic and/or reparative immune response mediators at baseline with outcome after CRT. In the multicenter RISK study, plasma samples were collected prospectively before CRT implantation. Plasma IL-6, epidermal growth factor, FGF-2, IL-1α, IL-1β, IL-4, and IL-13 were evaluated by Luminex technology. The primary outcome was predefined as freedom from heart failure hospitalization or death and a decrease in echocardiographic end-systolic volume of >15% at 12 months. To determine associations with the outcome, multivariate logistic regression models including baseline clinical characteristics and the specific cytokines and growth factors were constructed. On multivariate analysis of 257 patients, detectable reparative cytokine IL-13 was significantly associated with the primary outcome (odds ratio 3.79; 95% CI 2.10 to 6.82, p <0.0001). In contrast, detectable proinflammatory/fibrotic growth factor FGF-2 was negatively associated (odds ratio 0.31; 95% CI, 0.14 to 0.68; p = 0.004). In conclusion, in CRT recipients, baseline levels of inflammatory mediators affecting cardiac fibrosis versus repair were associated with subsequent clinical outcome.

Antibody-mediated rejection of the lung: A consensus report of the International Society for Heart and Lung Transplantation

Antibody-mediated rejection (AMR) is a recognized cause of allograft dysfunction in lung transplant recipients. Unlike AMR in other solid-organ transplant recipients, there are no standardized diagnostic criteria or an agreed-upon definition. Hence, a working group was created by the International Society for Heart and Lung Transplantation with the aim of determining criteria for pulmonary AMR and establishing a definition. Diagnostic criteria and a working consensus definition were established. Key diagnostic criteria include the presence of antibodies directed toward donor human leukocyte antigens and characteristic lung histology with or without evidence of complement 4d within the graft. Exclusion of other causes of allograft dysfunction increases confidence in the diagnosis but is not essential. Pulmonary AMR may be clinical (allograft dysfunction which can be asymptomatic) or sub-clinical (normal allograft function). This consensus definition will have clinical, therapeutic and research implications.

Effects of maternal food restriction on offspring lung extracellular matrix deposition and long term pulmonary function in an experimental rat model

Intrauterine growth restriction (IUGR) increases the risk of respiratory compromise throughout postnatal life. However, the molecular mechanism(s) underlying the respiratory compromise in offspring following IUGR is not known. We hypothesized that IUGR following maternal food restriction (MFR) would affect extracellular matrix deposition in the lung, explaining the long-term impairment in pulmonary function in the IUGR offspring. Using a well-established rat model of MFR during gestation to produce IUGR pups, we found that at postnatal day 21, and at 9 months (9M) of age the expression and abundance of elastin and alpha smooth muscle actin (αSMA), two key extracellular matrix proteins, were increased in IUGR lungs when compared to controls (P < 0.05, n = 6), as determined by both Western and immunohistochemistry analyses. Compared to controls, the MFR group showed no significant change in pulmonary resistance at baseline, but did have significantly decreased pulmonary compliance at 9M (P < 0.05 vs. control, n = 5). In addition, MFR lungs exhibited increased responsiveness to methacholine challenge. Furthermore, exposing cultured fetal rat lung fibroblasts to serum deprivation increased the expression of elastin and elastin-related genes, which was blocked by serum albumin supplementation, suggesting protein deficiency as the predominant mechanism for increased pulmonary elastin deposition in IUGR lungs. We conclude that accompanying the changes in lung function, consistent with bronchial hyperresponsiveness, expression of the key alveolar extracellular matrix proteins elastin and αSMA increased in the IUGR lung, thus providing a potential explanation for the compromised lung function in IUGR offspring.

Lung transplantation and coronary artery disease

BACKGROUND

Coronary artery disease (CAD) remains a relative contraindication to lung transplantation. We have offered lung transplantation and coronary revascularization to selected patients with discrete CAD and preserved left ventricular function. The purpose of this report is the following: (1) to examine the short-term and medium-term outcome of patients after coronary revascularization and lung transplantation; and (2) to compare the short-term and medium-term outcome of this cohort to a matched group of lung transplant recipients without CAD.

METHODS

From January 2000 to March 2010, 27 patients with CAD underwent coronary revascularization and lung transplantation. The control group was matched based on age, diagnosis, lung allocation score, and type of procedure.

RESULTS

Lung transplant recipients with CAD and the control group had similar incidence of primary graft dysfunction (grade III). The duration of mechanical ventilation, intensive care unit stay, and hospital stay were the same. At a mean follow-up of 3 years, the incidence of composite adverse cardiac events was similar in the 2 groups.

CONCLUSIONS

Lung transplant recipients with CAD and the control group also had similar medium-term survival. Lung transplantation can be considered in patients with preexistent CAD with acceptable early and medium-term outcomes.

Combined CXCR3/CCR5 blockade attenuates acute and chronic rejection

Chemokine-chemokine receptor interactions orchestrate mononuclear cells recruitment to the allograft, leading to acute and chronic rejection. Despite biologic redundancy, several experimental studies have demonstrated the importance of CXCR3 and CCR5 in acute rejection of allografts. In these studies, deficiency or blockade of CXCR3 or CCR5 led to prolongation of allograft survival, yet allografts were ultimately lost to acute rejection. Given the above findings and the specificity of mononuclear cells bearing CXCR3 and CCR5, we hypothesized that combined blockade of CXCR3 and CCR5 will lead to indefinite (>100 days) graft survival in a full MHC-mismatched murine cardiac allograft model. The donor hearts in the control group were rejected in 6 +/- 1 days after transplantation. Combined blockade of CXCR3 and CCR5 prolonged allograft survival >15-fold vs the control group; all allografts survived for >100 days. More importantly, the donor hearts did not display any intimal lesions characteristic of chronic rejection. Further analysis of the donor hearts in the CXCR3/CCR5 blockade group demonstrated graft infiltration with CD4(+)CD25(+) T cells expressing the Foxp3 gene. Depletion of CD25(+) cells in the combined CXCR3 and CCR5 blockade group resulted in acute rejection of the allografts in 22 +/- 2 days. Combined CXCR3 and CCR5 blockade also reduced alloantigen-specific T lymphocyte proliferation. Combined CXCR3 and CCR5 blockade is effective in preventing acute and chronic rejection in a robust murine model. This effect is mediated, in part, by CD25(+) regulatory T cell recruitment and control of T lymphocyte proliferation.

Clarifying CB2 receptor-dependent and independent effects of THC on human lung epithelial cells

Marijuana smoking is associated with a number of abnormal findings in the lungs of habitual smokers. Previous studies revealed that Delta(9)-tetrahydrocannabinol (THC) caused mitochondrial injury in primary lung epithelial cells and in the cell line, A549 [Sarafian, T. A., Kouyoumjian, S., Khoshaghideh, F., Tashkin, D. P., and Roth, M. D. (2003). Delta 9-tetrahydrocannabinol disrupts mitochondrial function and cell energetics. Am J Physiol Lung Cell Mol Physiol 284, L298-306; Sarafian, T., Habib, N., Mao, J. T., Tsu, I. H., Yamamoto, M. L., Hsu, E., Tashkin, D. P., and Roth, M. D. (2005). Gene expression changes in human small airway epithelial cells exposed to Delta9-tetrahydrocannabinol. Toxicol Lett 158, 95-107]. The role of cannabinoid receptors in this injury was unclear, as was the potential impact on cell function. In order to investigate these questions, A549 cells were engineered to over-express the type 2 cannabinoid receptor (CB2R) using a self-inactivating lentiviral vector. This transduction resulted in a 60-fold increase in CB2R mRNA relative to cells transduced with a control vector. Transduced cell lines were used to study the effects of THC on chemotactic activity and mitochondrial function. Chemotaxis in response to a 10% serum gradient was suppressed in a concentration-dependent manner by exposure to THC. CB2R-transduced cells exhibited less intrinsic chemotactic activity (p<0.05) and were 80- to 100-fold more sensitive to the inhibitory effects of THC. Studies using SR144528, a selective CB2R antagonist, verified that these effects were mediated by the CB2R. Marijuana smoke extract, but not smoke extracts from tobacco or placebo marijuana cigarettes, reproduced these effects (p<0.05). THC decreased ATP level and mitochondrial membrane potential (Psi(m)) in both control and CB2R-transduced cells. However, these decreases did not play a significant role in chemotaxis inhibition since cyclosporine A, which protected against ATP loss, did not increase cell migration. Moreover, CB2R-transduced cells displayed higher Psi(m) than did control cells. Since both Psi(m) and chemotaxis are regulated by intracellular signaling, we investigated the effects of THC on the activation of multiple signaling pathways. Serum exposure activated several signaling events of which phosphorylation of IkappaB-alpha and JNK was regulated in a CB2R- and THC-dependent manner. We conclude that airway epithelial cells are sensitive to both CB2R-dependent and independent effects mediated by THC.

A chimeric human-cat Fcγ-Fel d1 fusion protein inhibits systemic, pulmonary, and cutaneous allergic reactivity to intratracheal challenge in mice sensitized to Fel d1, the major cat allergen

Co-aggregation of FcepsilonRI with FcgammaRIIb can block FcepsilonRI-mediated reactivity and Fc gamma:allergen chimeric proteins, by co-crosslinking FcgammaRIIb to allergen-specific IgE bound to the FcepsilonRI can block allergen-specific reactivity. We evaluated whether a human cat chimeric fusion protein (GFD) composed of part of the human Ig G1 Fc fused to the major cat allergen (Fel d1) would function as allergen immunotherapy while not inducing acute allergic reactivity in mice sensitized to Fel d1. Injection of GFD 6 h prior to Fel d1 challenge acutely blocked systemic and skin reactivity to Fel d1 challenge while mice given subcutaneous immunotherapy with GFD at days 37, 38, and 39 showed inhibition of systemic, lung, and cutaneous reactivity to Fel d1 2 weeks later. GFD immunotherapy did not induce systemic reactivity. Overall, the Fcgamma-Fel d1 chimeric fusion protein blocked Fel d1-induced IgE-mediated reactivity but did not induce in vivo mediator release on its own; suggesting that this approach using allergen combined with Fc gamma1 so as to achieve inhibitory signaling may provide an enhanced form of allergen immunotherapy.

Chemokine Monokine Induced by IFN-γ/CXC Chemokine Ligand 9 Stimulates T Lymphocyte Proliferation and Effector Cytokine Production

Monokine induced by IFN-gamma (MIG; CXC chemokine ligand (CXCL)9) is important in T lymphocyte recruitment in organ transplantation. However, it is not known whether this chemokine, in addition to its chemotactic properties, exerts any effect on T lymphocyte effector functions. For in vivo studies, we used a previously characterized murine model of chronic rejection. The recipient mice were treated with anti-MIG/CXCL9 Ab; graft-infiltrating cells were analyzed for IFN-gamma production. For in vitro studies, exogenous CXCR3 ligands were added to CD4 lymphocytes in MLRs, and the proliferative responses were measured. Separate experiments quantitated the number of IFN-gamma-producing cells in MLRs by ELISPOT. Neutralization of MIG/CXCL9, in the in vivo model, resulted in significant reduction in the percentage of IFN-gamma-producing graft-infiltrating T lymphocytes. In vitro experiments demonstrated that 1) exogenous MIG/CXCL9 stimulated CD4 lymphocyte proliferation in a MHC class II-mismatched MLR, 2) MIG/CXCL9 also increased the number of IFN-gamma-producing CD4 lymphocytes in ELISPOT, 3) neutralization of MIG/CXCL9 in MLR reduced T lymphocyte proliferation, 4) IFN-gamma-inducible protein 10/CXCL10 and IFN-inducible T cell alpha chemoattractant/CXCL11 had similar effects on T lymphocyte proliferation, 5) MIG/CXCL9 stimulated T lymphocyte proliferation in MHC class I- and total MHC-mismatched MLRs, 6) neutralization of CXCR3 reduced MIG/CXCL9-induced T lymphocyte proliferation and the number of IFN-gamma-positive spots on ELISPOT, and 7) the proliferative effects of MIG/CXCL9 were mediated via an IL-2-independent pathway and were controlled by IFN-gamma. This study demonstrates that MIG/CXCL9 stimulates T lymphocyte proliferation and effector cytokine production, in addition to its chemotactic effects. This novel observation expands our current understanding of MIG/CXCL9 biology beyond that of mediating T cell trafficking.