AGENDA

MORNING SESSION:  ASTHMA

7:30 Registration and Continental Breakfast

8:15-8:30 Introduction from Merck Research Laboratories

8:30-8:35 Introduction from Conference Co-Chairs

8:35-9:05  What has anti-IgE Therapy Taught us about Asthma?
Hans Oettgen Hans Oettgen, M.D., Ph.D., Associate Professor of Pediatrics, Harvard Medical School; Associate Chief, Division of Immunology, Children’s Hospital, Boston
Immunological sensitization to airborne allergens, resulting in production of IgE antibodies, is a hallmark of asthma. IgE has been recognized as a risk factor for developing asthma and IgE levels correlate with disease severity.  The introduction of the humanized monoclonal anti-IgE therapeutic, omalizumab, has provided both an effective therapy for poorly-controlled asthmatics and a useful probe for the investigation of mechanisms of action of IgE in asthma.  As had been predicted by animal models, omalizumab has identified roles for IgE in both acute and late-phase reactions to inhaled aeroallergens, regulation ofFcRI levels, modulation of the activation thresholds of effector cells and, in some subjects, recruitment eosinophils to the airway mucosa.  This session will review the lessons we have learned from anti-IgE.

9:05-9:35 Genetics of Allergic and Asthmatic Diseases
Benjamin Raby Benjamin Raby, M.D., M.P.H., Assistant Professor of Medicine, Channing Laboratory and the Division of Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School 
Allergy and asthma represent classic examples of complex genetic diseases in that they are caused by the interactive effects of numerous susceptibility genes and environmental cues. Over the past 5 years, the advent of genome-wide association studies have led to the discovery of more than 15 bona fide susceptibility genes for asthma, allergic rhinitis, and eczema, including many genes that had not been previously implicated in the pathobiology of atopy. This lecture will review these exciting findings and the prospects personalized medical treatment of atopy.

9:35-10:05 Lack of CFTR on T-cells Exacerbates Allergic IgE Responses
Christian Mueller Christian Mueller, Ph.D., Assistant Professor of Pediatrics, Gene Therapy Center, University of Massachusetts Medical School
Cystic fibrosis (CF) remains the most common fatal monogenic disease in the US, affecting 1 in 3,300 live births. CF is the result of mutations in CFTR, a chloride channel and regulator of other ion channels. We have shown that Cftr-/- mice mount an exaggerated IgE response towards Aspergillus fumigatus (Af) when compared to Cftr+/+ mice. The increased IgE levels are primarily due to the lack of Cftr expression in lymphocytes rather than with Cftr deficiency in the epithelium. Our results indicate that adoptive transfer experiments with Cf splenocytes confer higher IgE response to Af in host mice as compared to hosts receiving wild-type splenocytes. Conclusive data on this phenomenon were obtained with conditional Cftr knockout mice, where mice lacking Cftr in T-cell lineages developed the higher IgE titers as compared to their wild-type littermate controls. Further analysis of Cftr-deficient lymphocytes revealed an enhanced intracellular Ca2+ flux in response to T cell receptor activation as compared to normal lymphocytes. This was accompanied by a significant increase in nuclear localization of the calcium-sensitive transcription factor NFAT, which could contribute to the enhanced secretion of IL-13 and other cytokines.

10:05-10:30 Networking Coffee Break

10:30-11:00 Innate Signaling and Th2 Immunity to House Dust Mite via Dectin-2
Nora Barrett Nora A. Barrett, M.D., Instructor in Medicine, Brigham and Women’s Hospital
Allergic asthma is characterized by an exuberant Th2 immune response against innocuous environmental antigens, but the innate signaling pathways activated by inhaled antigens to trigger this response are not well defined. We have identified Dectin-2, a myeloid C-type lectin, as a dendritic cell (DC) receptor for glycans in allergen extracts from the house dust mites Dermatophagoides farinae (Df) and Dermatophagoides pteronyssinus (Dp), and from the mold Aspergillus fumigatus (Af). Activation of Dectin-2 in DCs stimulates the generation of both lipid mediators such as cysteinyl leukotrienes (cys-LTs) and pro-inflammatory cytokines such as TNF-α and IL-6, via an FcRγ and Syk-dependent signaling pathway. Lentiviral knockdown of Dectin-2 in bone marrow-derived dendritic cells (BMDCs) inhibits their ability to sensitize naïve recipients to Df and administration of an anti-Dectin-2 blocking antibody to mice dramatically reduces Df-elicited Th2 and Th17 pulmonary inflammation. Further studies using leukotriene C4 synthase (LTC4S)-deficient mice or type 1 cys-LT receptor (CysLT1R)-deficient mice identify DC cys-LTs as the germane Dectin-2-derived mediators of Th2 pulmonary inflammation to Df. Thus, the innate Dectin-2/cys-LT signaling pathway is a critical link between allergen recognition and Th2 immunity.

 

NOVEL TECHNOLOGIES & APPLICATIONS

11:00-11:30  Linking Airway Inflammatory Profiles in Allergic Asthma to Pulmonary Function

Benjamin Medoff Benjamin Medoff, M.D., Chief, Pulmonary and Critical Care Unit; Associate Director, CIID, Massachusetts General Hospital

In asthma, the relationship between airway inflammation and airway hyperresponsiveness is poorly understood.  We sought to determine whether PET-CT could be used to determine eosinophilic inflammation and local lung function following segmental allergen challenge in allergic asthmatics.  In this presentation, we report our experience using PET-CT to assess regional pulmonary perfusion (Q), specific ventilation (V ), fractional gas content (Fgas), airway wall thickness, and regional 18F-fluorodeoxyglucose (18FDG) uptake (Ki) 10 hours after segmental allergen challenge to the right middle lobe in subjects with demonstrated atopy with and without asthma.  Q, V, and Fgas in the allergen-challenged lobe were compared to the right upper lobe, where diluent was applied as a control.  Airway wall thickness aspect ratio of the allergen-challenged airway was compared to those of similarly-sized airways from unaffected areas of the lung.  Differences in Ki between allergen and diluent segments were compared to those in cell counts obtained 24 hours after the allergen challenge by a bronchoalveolar lavage of the respective segments.  We found systematic reductions in regional V , Q , and Fgas and increased airway wall thickness in asthmatic subjects.  In addition, in the asthmatic subjects the ratio of eosinophil count (allergen/diluent) was linearly related (R2=0.9916, p < 0.001) with the ratio in 18FDG Ki.  We conclude that  PET-CT can be used to assess eosinophilic airway inflammation and its functional effects following segmental allergen challenge.  Furthermore, our data demonstrate that segmental allergen challenge results in robust eosinophilic inflammation that is accompanied by systematic local alterations in lung function.

11:30-12:00 A Human Breathing Lung-on-a-Chip for Drug Screening and Nanotoxicology Applications

Dan Huh Dan Dongeun Huh, Ph.D., Wyss Technology Development Fellow, Wyss Institute for Biologically Inspired Engineering, Harvard University

Here we describe a biomimetic microsystem that reconstitutes the critical functional alveolar-capillary interface.  This microdevice reproduces complex integrated organ-level responses to bacteria and inflammatory cytokines introduced into the alveolar space.  Using this approach, we developed novel nanotoxicology models and revealed that physiological cyclic mechanical strain greatly accentuates toxic and inflammatory responses of the lung to silica nanoparticles.  Mechanical strain also enhances nanoparticle uptake by the epithelial cells and stimulates their transport into the underlying microvasculature. Importantly, similar effects of physiological breathing on nanoparticle absorption were observed in whole lung using a mouse lung ventilation-perfusion model.  We also explored the potential use of this microsystem for the development of microengineered models of human lung disease for applications in drug testing.  This mechanically active biomimetic microsystem represents valuable new model systems for in vitro analysis of various physiological functions and disease processes, in addition to providing low-cost alternatives to animal and clinical studies for drug screening and toxicology applications.

12:00pm-1:15  Networking Luncheon

AFTERNOON SESSION:  COPD & PULMONARY FIBROSIS

1:15-1:45 Regulation of Fibrosis by Lysophosphatidic Acid (LPA) and its Receptor LPA1 in the Lung and Other Organs
Andy Tager Andrew M. Tager, M.D., Pulmonary and Critical Care Unit and Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital and Harvard Medical School
Aberrant wound-healing responses to tissue injury have been implicated in the development of fibrosis in multiple organs, including the lungs in idiopathic pulmonary fibrosis (IPF), but the mediators directing these pathologic responses have yet to be fully identified.  We initially identified lysophosphatidic acid (LPA) as the chemoattractant responsible for recruiting fibroblasts to sites of lung injury in both the bleomycin mouse model of pulmonary fibrosis and IPF patients.  LPA signaling through LPA1, one of multiple LPA receptors identified, is specifically responsible for this fibroblast recruitment.  LPA-LPA1 signaling also contributes to lung fibrosis by promoting epithelial cell apoptosis and vascular leak, responses that, like fibroblast recruitment, appear excessive when tissue injury leads to fibrosis rather than repair.  We have found that LPA-LPA1 signaling is also required for the development of fibrosis in mouse models of scleroderma and of peritoneal fibrosis, a potentially fatal complication of peritoneal dialysis.  In the peritoneal fibrosis model, we have elucidated a novel molecular pathway through which LPA induces pro-fibrotic gene expression, involving LPA1 signaling, RhoA activation, actin polymerization, and the transcription factors myocardin-related transcription factor (MRTF)-A, MRTF-B and serum response factor (SRF).  LPA signaling through LPA1 therefore regulates multiple fibrotic responses to tissue injury in the lung and multiple other organs.  Targeting LPA and LPA1 consequently may be an effective therapeutic strategy for IPF and multiple other fibrotic diseases.

1:45-2:15 Sphingosine 1-phosphate Signaling in Lung Injury: Connecting the Dots between Vascular Leak and Fibrosis
Barry Shea Barry Shea, M.D., Pulmonary and Critical Care Unit , Massachusetts General Hospital
The lipid mediator sphingosine 1-phosphate (S1P), signaling through one of its receptors, S1P1, plays a key role in limiting the early exudative response to lung injury by limiting vascular leak.  Our laboratory has found that S1P-S1P1 signaling also appears to regulate the later fibrotic response to lung injury.  Manipulation of this pathway has therefore allowed us to gain insights into how early vascular responses to injury can influence subsequent fibrotic alveolar remodeling.  It appears that vascular leak promotes lung fibrosis through the extravasation of plasma clotting factors into the injured airspaces, resulting in increased intra-alveolar activation of the coagulation cascade, thrombin generation, and subsequent thrombin-mediated activation of proteinase-activated receptors (PARs).

2:15-2:45 Syndecan Interactions in Pneumonia
Pyong Park Pyong Woo Park, Ph.D., Associate Professor of Pediatrics, Division of Respiratory Diseases, Children’s Hospital, Harvard Medical School
Many pathogens bind to heparan sulfate proteoglycans (HSPGs) to infect host cells in vitro, but the significance of HSPG-pathogen interactions has yet to be established in vivo. We examined the role of syndecan-1, the major epithelial HSPG, in Staphylococcus aureus pneumonia. Syndecan-1 null mice significantly resisted intranasal S. aureus lung infection compared to Wt mice. S. aureus did not bind to syndecan-1, but it induced syndecan-1 shedding in lung epithelial cells. Administration of syndecan-1 ectodomains increased, whereas inhibition of syndecan-1 shedding decreased the bacterial burden. These data suggest that subversion of syndecan-1 shedding is an important virulence mechanism in S. aureus pneumonia.

2:45-3:10 Networking Refreshment Break

3:10- 3:40 Genetics of COPD
Edwin Silverman Edwin K. Silverman, M.D., Ph.D., Associate Professor of Medicine, Channing Laboratory and Pulmonary and Critical Care Division, Brigham and Women’s Hospital, Harvard Medical School
Recent genome-wide association studies (GWAS) of COPD have identified several genomic regions that contain COPD susceptibility genes, including a region on chromosome 15 which has previously been associated with smoking behavior and lung cancer, and two novel regions on chromosome 4.  However, the identification of the functional variants within these GWAS regions is challenging.  We have used chromosome conformation capture to localize regulatory regions within the COPD GWAS region on chromosome 4q31, which is located upstream from the HHIP gene.  Follow-up studies of this locus have identified an enhancer region with potentially functional genetic variants.  Following up the COPD GWAS discoveries will require high throughput functional assessments, as well as novel approaches to dissect COPD heterogeneity.

3:40-4:10 Spatial Heterogeneity of Lung Perfusion Assessed with Nitrogen-13 PET as a Vascular Biomarker in COPD
Scott Harris R. Scott Harris, M.D., Associate Physician, Massachusetts General Hospital, Assistant Professor, Harvard Medical School
Although it is known that structural and functional changes in the pulmonary vasculature and parenchyma occur in the progress of chronic obstructive pulmonary disease (COPD), information is limited on early regional perfusion (Qr) alterations. Methods: We studied 6 patients with mild or moderate COPD and 9 healthy subjects (6 young and 3 age-matched). The PET 13NN-labeled saline injection method was used to compute images of (Qr) and regional ventilation (Vr). Transmission scans were used to assess regional density. We used the squared coefficient of variation to quantify (Qr) heterogeneity and length-scale analysis to quantify the contribution to total perfusion heterogeneity of regions ranging from less than 12 to more than 108 mm. Results: Perfusion distribution in COPD subjects showed larger (Qr) heterogeneity, higher contribution from large length scales and lower contribution from small length scales, and larger heterogeneity of (Qr) normalized by tissue density than did healthy subjects. Dorsoventral gradients of (Vr) were present in healthy subjects, with larger ventilation in dependent regions, whereas no gradient was present in COPD. Heterogeneity of ventilation–perfusion ratios was larger in COPD. Conclusion: (Qr) is significantly redistributed in COPD. (Qr) heterogeneity in COPD patients is greater than in healthy subjects, mainly because of the contribution of large lung regions and not because of changes in tissue density or (Vr). The assessment of spatial heterogeneity of lung perfusion with 13NN-saline PET may serve as a vascular biomarker in COPD.

4:10-4:40 Activities for Proteinases in the Pathogenesis of COPD
Caroline Owen Caroline A. Owen, M.D., Ph.D., Assistant Professor of Medicine, Division of Pulmonary and Critical Care Medicine, Brigham and Women’s Hospital and Harvard Medical School
Cigarette smoke stimulates the recruitment of leukocytes and the release of proteinases into the lung (the  “proteinase-antiproteinase” hypothesis). Proteinases contribute to smoke-induced lung inflammation, emphysema development, mucus hypersecretion, and small airway fibrosis. The most compelling evidence linking proteinases and COPD comes from animal models of COPD which have implicated matrix metalloproteinase-12 (MMP-12) and neutrophil elastase (NE) in emphysema, serine and ADAM proteinases in mucus hypersecretion, and MMP-9 and -12 in small airway fibrosis.  Other studies have identified  mechanisms by which proteinases circumvent the lung’s proteinase inhibitor defense to promote COPD pathogenesis.  These mechanisms include: 1) inactivation of proteinase inhibitors; 2) binding of proteinases to leukocyte surfaces in inhibitor-resistant forms; and 3) leukocytes releasing very high concentrations of proteinases to overwhelm endogenous inhibitors in the pericellular environment. However, synthetic proteinase inhibitors effectively reduce lung pathologies in animal models of COPD.  Thus, developing novel therapeutics that more effectively inhibit the deleterious activities of proteinases than endogenous proteinase inhibitors and/or reduce the lung burden of proteinases should be a priority for human COPD.

4:40-5:00 Closing Remarks


Co-Chairs

Frank AustenK. Frank Austen, M.D., Astra Zeneca Professor of Respiratory and Inflammatory Diseases, Department of Medicine, Brigham and Women's Hospital

Andrew LusterAndrew D. Luster, M.D., Ph.D., Chief, Division of Rheumatology, Allergy and Immunology; Director, Center for Immunology and Inflammatory Diseases; Persis, Cyrus and Marlow B. Harrison Professor of Medicine, Harvard Medical School



Focused Sessions On

Asthma
COPD/Pulmonary Fibrosis