Honors & Awards

  • Member, Phi Beta Kappa Honor Society (2010)

Professional Education

  • Doctor of Philosophy, Stanford University, STMRM-PHD (2018)
  • BS, University of Denver, Molecular Biology (2010)

Current Research and Scholarly Interests

I am a postdoctoral fellow in the labs of Dr. Max Diehn (MD/PhD) and Dr. Ash Alizadeh (MD/PhD) at Stanford’s School of Medicine. I am broadly interested in translational cancer research and bioinformatics, with a focus on using cancer genomics to inform more personalized treatment strategies for cancer patients. My lab uses cell free DNA (cfDNA), which is accessible via the circulation, as a non-invasive biomarker to detect cancer (i.e. screening) and better monitor whether patients are responding to treatment over time (i.e. surveillance). To do this, my lab has developed Cancer Personalized Profiling by Deep Sequencing (CAPP-Seq), which enables the ultra-sensitive detection of circulating tumor DNA (ctDNA) that is broadly applicable to human cancers. The initial focus of my thesis research was on the mechanisms underlying acquired resistance to genotype-targeted therapies in patients with Non-Small Cell Lung Cancer (NSCLC). I am now focused on improving the sensitivity and specificity of our assay for cancer screening and monitoring applications.

Beyond these research focuses, I am also interested in business and entrepreneurship, specifically in the development of blood-based cancer diagnostics. I worked for two biotech companies while I was an undergraduate at the University of Denver and after completing my BS in 2010 I took graduate level coursework as a part of a certificate program in “Bioinnovation and Entrepreneurship” administered by the University of Colorado Medical School. This coursework exposed me to subject matter such as the fundamentals of entrepreneurship and entity formation, intellectual property law and technology transfer, FDA regulatory compliance, and reimbursement strategy. I have continued to pursue these interests outside the lab at Stanford.

All Publications

  • Combination approach for detecting different types of alterations in circulating tumor DNA in leiomyosarcoma. Clinical cancer research : an official journal of the American Association for Cancer Research Przybyl, J., Chabon, J. J., Spans, L., Ganjoo, K., Vennam, S., Newman, A. M., Forgó, E., Varma, S., Zhu, S., Debiec-Rychter, M., Alizadeh, A. A., Diehn, M., van de Rijn, M. 2018


    The clinical utility of circulating tumor DNA (ctDNA) monitoring has been shown in tumors that harbor highly recurrent mutations. Leiomyosarcoma (LMS) represents a type of tumor with a wide spectrum of heterogeneous genomic abnormalities; thus, targeting hotspot mutations or a narrow genomic region for ctDNA detection may not be practical. Here we demonstrate a combinatorial approach that integrates different sequencing protocols for the orthogonal detection of single nucleotide variants (SNVs), small indels and copy number alterations (CNAs) in ctDNA.We employed Cancer Personalized Profiling by deep Sequencing (CAPP-Seq) for the analysis of SNVs and indels, together with a genome-wide interrogation of CNAs by Genome Representation Profiling (GRP). We profiled 28 longitudinal plasma samples and 25 tumor specimens from 7 patients with LMS.We detected ctDNA in 6 of 7 of these patients with >98% specificity for mutant allele fractions down to a level of 0.01%. We show that results from CAPP-Seq and GRP are highly concordant, and the combination of these methods allows for more comprehensive monitoring of ctDNA by profiling a wide spectrum of tumor-specific markers. By analyzing multiple tumor specimens in individual patients obtained from different sites and at different times during treatment, we observed clonal evolution of these tumors that was reflected by ctDNA profiles.Our strategy allows for a comprehensive monitoring of a broad spectrum of tumor-specific markers in plasma. Our approach may be clinically useful not only in LMS but also in other tumor types that lack recurrent genomic alterations.

    View details for PubMedID 29463554

  • Early detection of molecular residual disease in localized lung cancer by circulating tumor DNA profiling. Cancer discovery Chaudhuri, A. A., Chabon, J. J., Lovejoy, A. F., Newman, A. M., Stehr, H., Azad, T. D., Khodadoust, M. S., Esfahani, M. S., Liu, C. L., Zhou, L., Scherer, F., Kurtz, D. M., Say, C., Carter, J. N., Merriott, D. J., Dudley, J. C., Binkley, M. S., Modlin, L., Padda, S. K., Gensheimer, M. F., West, R. B., Shrager, J. B., Neal, J. W., Wakelee, H. A., Loo, B. W., Alizadeh, A. A., Diehn, M. 2017


    Identifying molecular residual disease (MRD) after treatment of localized lung cancer could facilitate early intervention and personalization of adjuvant therapies. Here we apply Cancer Personalized Profiling by Deep Sequencing (CAPP-Seq) circulating tumor DNA (ctDNA) analysis to 255 samples from 40 patients treated with curative intent for stage I-III lung cancer and 54 healthy adults. In 94% of evaluable patients experiencing recurrence, ctDNA was detectable in the first post-treatment blood sample, indicating reliable identification of MRD. Post-treatment ctDNA detection preceded radiographic progression in 72% of patients by a median of 5.2 months and 53% of patients harbored ctDNA mutation profiles associated with favorable responses to tyrosine kinase inhibitors or immune checkpoint blockade. Collectively, these results indicate that ctDNA MRD in lung cancer patients can be accurately detected using CAPP-Seq and may allow personalized adjuvant treatment while disease burden is lowest.

    View details for PubMedID 28899864

  • Circulating tumour DNA profiling reveals heterogeneity of EGFR inhibitor resistance mechanisms in lung cancer patients NATURE COMMUNICATIONS Chabon, J. J., Simmons, A. D., Lovejoy, A. F., Esfahani, M. S., Newman, A. M., Haringsma, H. J., Kurtz, D. M., Stehr, H., Scherer, F., Karlovich, C. A., Harding, T. C., Durkin, K. A., Otterson, G. A., Purcell, W. T., Camidge, D. R., Goldman, J. W., Sequist, L. V., Piotrowska, Z., Wakelee, H. A., Neal, J. W., Alizadeh, A. A., Diehn, M. 2016; 7


    Circulating tumour DNA (ctDNA) analysis facilitates studies of tumour heterogeneity. Here we employ CAPP-Seq ctDNA analysis to study resistance mechanisms in 43 non-small cell lung cancer (NSCLC) patients treated with the third-generation epidermal growth factor receptor (EGFR) inhibitor rociletinib. We observe multiple resistance mechanisms in 46% of patients after treatment with first-line inhibitors, indicating frequent intra-patient heterogeneity. Rociletinib resistance recurrently involves MET, EGFR, PIK3CA, ERRB2, KRAS and RB1. We describe a novel EGFR L798I mutation and find that EGFR C797S, which arises in ∼33% of patients after osimertinib treatment, occurs in <3% after rociletinib. Increased MET copy number is the most frequent rociletinib resistance mechanism in this cohort and patients with multiple pre-existing mechanisms (T790M and MET) experience inferior responses. Similarly, rociletinib-resistant xenografts develop MET amplification that can be overcome with the MET inhibitor crizotinib. These results underscore the importance of tumour heterogeneity in NSCLC and the utility of ctDNA-based resistance mechanism assessment.

    View details for DOI 10.1038/ncomms11815

    View details for PubMedID 27283993

  • Detection and Surveillance of Bladder Cancer Using Urine Tumor DNA CANCER DISCOVERY Dudley, J. C., Schroers-Martin, J., Lazzareschi, D., Shi, W., Chen, S. B., Esfahani, M. S., Trivedi, D., Chabon, J. J., Chaudhuri, A. A., Stehr, H., Liu, C., Lim, H., Costa, H. A., Nabet, B. Y., Sin, M. Y., Liao, J. C., Alizadeh, A. A., Diehn, M. 2019; 9 (4): 500–509
  • Circulating Tumor DNA Measurements As Early Outcome Predictors in Diffuse Large B-Cell Lymphoma. Journal of clinical oncology : official journal of the American Society of Clinical Oncology Kurtz, D. M., Scherer, F., Jin, M. C., Soo, J., Craig, A. F., Esfahani, M. S., Chabon, J. J., Stehr, H., Liu, C. L., Tibshirani, R., Maeda, L. S., Gupta, N. K., Khodadoust, M. S., Advani, R. H., Levy, R., Newman, A. M., Duhrsen, U., Huttmann, A., Meignan, M., Casasnovas, R., Westin, J. R., Roschewski, M., Wilson, W. H., Gaidano, G., Rossi, D., Diehn, M., Alizadeh, A. A. 2018: JCO2018785246


    Purpose Outcomes for patients with diffuse large B-cell lymphoma remain heterogeneous, with existing methods failing to consistently predict treatment failure. We examined the additional prognostic value of circulating tumor DNA (ctDNA) before and during therapy for predicting patient outcomes. Patients and Methods We studied the dynamics of ctDNA from 217 patients treated at six centers, using a training and validation framework. We densely characterized early ctDNA dynamics during therapy using cancer personalized profiling by deep sequencing to define response-associated thresholds within a discovery set. These thresholds were assessed in two independent validation sets. Finally, we assessed the prognostic value of ctDNA in the context of established risk factors, including the International Prognostic Index and interim positron emission tomography/computed tomography scans. Results Before therapy, ctDNA was detectable in 98% of patients; pretreatment levels were prognostic in both front-line and salvage settings. In the discovery set, ctDNA levels changed rapidly, with a 2-log decrease after one cycle (early molecular response [EMR]) and a 2.5-log decrease after two cycles (major molecular response [MMR]) stratifying outcomes. In the first validation set, patients receiving front-line therapy achieving EMR or MMR had superior outcomes at 24 months (EMR: EFS, 83% v 50%; P = .0015; MMR: EFS, 82% v 46%; P < .001). EMR also predicted superior 24-month outcomes in patients receiving salvage therapy in the first validation set (EFS, 100% v 13%; P = .011). The prognostic value of EMR and MMR was further confirmed in the second validation set. In multivariable analyses including International Prognostic Index and interim positron emission tomography/computed tomography scans across both cohorts, molecular response was independently prognostic of outcomes, including event-free and overall survival. Conclusion Pretreatment ctDNA levels and molecular responses are independently prognostic of outcomes in aggressive lymphomas. These risk factors could potentially guide future personalized risk-directed approaches.

    View details for PubMedID 30125215

  • Capturing Genomic Evolution of Lung Cancers through Liquid Biopsy for Circulating Tumor DNA. Journal of oncology Offin, M., Chabon, J. J., Razavi, P., Isbell, J. M., Rudin, C. M., Diehn, M., Li, B. T. 2017; 2017: 4517834-?


    Genetic sequencing of malignancies has become increasingly important to uncover therapeutic targets and capture the tumor's dynamic changes to drug sensitivity and resistance through genomic evolution. In lung cancers, the current standard of tissue biopsy at the time of diagnosis and progression is not always feasible or practical and may underestimate intratumoral heterogeneity. Technological advances in genetic sequencing have enabled the use of circulating tumor DNA (ctDNA) analysis to obtain information on both targetable mutations and capturing real-time Darwinian evolution of tumor clones and drug resistance mechanisms under selective therapeutic pressure. The ability to analyze ctDNA from plasma, CSF, or urine enables a comprehensive view of cancers as systemic diseases and captures intratumoral heterogeneity. Here, we describe these recent advances in the setting of lung cancers and advocate for further research and the incorporation of ctDNA analysis in clinical trials of targeted therapies. By capturing genomic evolution in a noninvasive manner, liquid biopsy for ctDNA analysis could accelerate therapeutic discovery and deliver the next leap forward in precision medicine for patients with lung cancers and other solid tumors.

    View details for DOI 10.1155/2017/4517834

    View details for PubMedID 28392802

  • Evolution and clinical impact of co-occurring genetic alterations in advanced-stage EGFR-mutant lung cancers. Nature genetics Blakely, C. M., Watkins, T. B., Wu, W., Gini, B., Chabon, J. J., McCoach, C. E., McGranahan, N., Wilson, G. A., Birkbak, N. J., Olivas, V. R., Rotow, J., Maynard, A., Wang, V., Gubens, M. A., Banks, K. C., Lanman, R. B., Caulin, A. F., St John, J., Cordero, A. R., Giannikopoulos, P., Simmons, A. D., Mack, P. C., Gandara, D. R., Husain, H., Doebele, R. C., Riess, J. W., Diehn, M., Swanton, C., Bivona, T. G. 2017; 49 (12): 1693–1704


    A widespread approach to modern cancer therapy is to identify a single oncogenic driver gene and target its mutant-protein product (for example, EGFR-inhibitor treatment in EGFR-mutant lung cancers). However, genetically driven resistance to targeted therapy limits patient survival. Through genomic analysis of 1,122 EGFR-mutant lung cancer cell-free DNA samples and whole-exome analysis of seven longitudinally collected tumor samples from a patient with EGFR-mutant lung cancer, we identified critical co-occurring oncogenic events present in most advanced-stage EGFR-mutant lung cancers. We defined new pathways limiting EGFR-inhibitor response, including WNT/β-catenin alterations and cell-cycle-gene (CDK4 and CDK6) mutations. Tumor genomic complexity increases with EGFR-inhibitor treatment, and co-occurring alterations in CTNNB1 and PIK3CA exhibit nonredundant functions that cooperatively promote tumor metastasis or limit EGFR-inhibitor response. This study calls for revisiting the prevailing single-gene driver-oncogene view and links clinical outcomes to co-occurring genetic alterations in patients with advanced-stage EGFR-mutant lung cancer.

    View details for PubMedID 29106415

    View details for PubMedCentralID PMC5709185

  • Deactivated CRISPR Associated Protein 9 for Minor-Allele Enrichment in Cell-Free DNA. Clinical chemistry Aalipour, A., Dudley, J. C., Park, S. M., Murty, S., Chabon, J. J., Boyle, E. A., Diehn, M., Gambhir, S. S. 2017


    Cell-free DNA (cfDNA) diagnostics are emerging as a new paradigm of disease monitoring and therapy management. The clinical utility of these diagnostics is relatively limited by a low signal-to-noise ratio, such as with low allele frequency (AF) mutations in cancer. While enriching for rare alleles to increase their AF before sample analysis is one strategy that can greatly improve detection capability, current methods are limited in their generalizability, ease of use, and applicability to point mutations.Leveraging the robust single-base-pair specificity and generalizability of the CRISPR associated protein 9 (Cas9) system, we developed a deactivated Cas9 (dCas9)-based method of minor-allele enrichment capable of efficient single-target and multiplexed enrichment. The dCas9 protein was complexed with single guide RNAs targeted to mutations of interest and incubated with cfDNA samples containing mutant strands at low abundance. Mutation-bound dCas9 complexes were isolated, dissociated, and the captured DNA purified for downstream use.Targeting the 3 most common epidermal growth factor receptor mutations (exon 19 deletion, T790M, L858R) found in nonsmall-cell lung cancer (NSCLC), we achieved >20-fold increases in AF and detected mutations by use of qPCR at an AF of 0.1%. In a cohort of 18 NSCLC patient-derived cfDNA samples, our method enabled detection of 8 out of 13 mutations that were otherwise undetected by qPCR.The dCas9 method provides important application of the CRISPR/Cas9 system outside the realm of genome editing and can provide a step forward for the detection capability of cfDNA diagnostics.

    View details for PubMedID 29038154

  • Molecular profiling of single circulating tumor cells from lung cancer patients PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Park, S., Wong, D. J., Ooi, C. C., Kurtz, D. M., Vermesh, O., Aalipour, A., Suh, S., Pian, K. L., Chabon, J. J., Lee, S. H., Jamali, M., Say, C., Carter, J. N., Lee, L. P., Kuschner, W. G., Schwartz, E. J., Shrager, J. B., Neal, J. W., Wakelee, H. A., Diehn, M., Nair, V. S., Wang, S. X., Gambhir, S. S. 2016; 113 (52): E8379-E8386


    Circulating tumor cells (CTCs) are established cancer biomarkers for the "liquid biopsy" of tumors. Molecular analysis of single CTCs, which recapitulate primary and metastatic tumor biology, remains challenging because current platforms have limited throughput, are expensive, and are not easily translatable to the clinic. Here, we report a massively parallel, multigene-profiling nanoplatform to compartmentalize and analyze hundreds of single CTCs. After high-efficiency magnetic collection of CTC from blood, a single-cell nanowell array performs CTC mutation profiling using modular gene panels. Using this approach, we demonstrated multigene expression profiling of individual CTCs from non-small-cell lung cancer (NSCLC) patients with remarkable sensitivity. Thus, we report a high-throughput, multiplexed strategy for single-cell mutation profiling of individual lung cancer CTCs toward minimally invasive cancer therapy prediction and disease monitoring.

    View details for DOI 10.1073/pnas.1608461113

    View details for PubMedID 27956614

  • Distinct biological subtypes and patterns of genome evolution in lymphoma revealed by circulating tumor DNA SCIENCE TRANSLATIONAL MEDICINE Scherer, F., Kurtz, D. M., Newman, A. M., Stehr, H., Craig, A. F., Esfahani, M. S., Lovejoy, A. F., Chabon, J. J., Klass, D. M., Liu, C. L., Zhou, L., Glover, C., Visser, B. C., Poultsides, G. A., Advani, R. H., Maeda, L. S., Gupta, N. K., Levy, R., Ohgami, R. S., Kunder, C. A., Diehn, M., Alizadeh, A. A. 2016; 8 (364)


    Patients with diffuse large B cell lymphoma (DLBCL) exhibit marked diversity in tumor behavior and outcomes, yet the identification of poor-risk groups remains challenging. In addition, the biology underlying these differences is incompletely understood. We hypothesized that characterization of mutational heterogeneity and genomic evolution using circulating tumor DNA (ctDNA) profiling could reveal molecular determinants of adverse outcomes. To address this hypothesis, we applied cancer personalized profiling by deep sequencing (CAPP-Seq) analysis to tumor biopsies and cell-free DNA samples from 92 lymphoma patients and 24 healthy subjects. At diagnosis, the amount of ctDNA was found to strongly correlate with clinical indices and was independently predictive of patient outcomes. We demonstrate that ctDNA genotyping can classify transcriptionally defined tumor subtypes, including DLBCL cell of origin, directly from plasma. By simultaneously tracking multiple somatic mutations in ctDNA, our approach outperformed immunoglobulin sequencing and radiographic imaging for the detection of minimal residual disease and facilitated noninvasive identification of emergent resistance mutations to targeted therapies. In addition, we identified distinct patterns of clonal evolution distinguishing indolent follicular lymphomas from those that transformed into DLBCL, allowing for potential noninvasive prediction of histological transformation. Collectively, our results demonstrate that ctDNA analysis reveals biological factors that underlie lymphoma clinical outcomes and could facilitate individualized therapy.

    View details for DOI 10.1126/scitranslmed.aai8545

    View details for PubMedID 27831904

  • Integrated digital error suppression for improved detection of circulating tumor DNA NATURE BIOTECHNOLOGY Newman, A. M., Lovejoy, A. F., Klass, D. M., Kurtz, D. M., Chabon, J. J., Scherer, F., Stehr, H., Liu, C. L., Bratman, S. V., Say, C., Zhou, L., Carter, J. N., West, R. B., Sledge, G. W., Shrager, J. B., Loo, B. W., Neal, J. W., Wakelee, H. A., Diehn, M., Alizadeh, A. A. 2016; 34 (5): 547-555


    High-throughput sequencing of circulating tumor DNA (ctDNA) promises to facilitate personalized cancer therapy. However, low quantities of cell-free DNA (cfDNA) in the blood and sequencing artifacts currently limit analytical sensitivity. To overcome these limitations, we introduce an approach for integrated digital error suppression (iDES). Our method combines in silico elimination of highly stereotypical background artifacts with a molecular barcoding strategy for the efficient recovery of cfDNA molecules. Individually, these two methods each improve the sensitivity of cancer personalized profiling by deep sequencing (CAPP-Seq) by about threefold, and synergize when combined to yield ∼15-fold improvements. As a result, iDES-enhanced CAPP-Seq facilitates noninvasive variant detection across hundreds of kilobases. Applied to non-small cell lung cancer (NSCLC) patients, our method enabled biopsy-free profiling of EGFR kinase domain mutations with 92% sensitivity and >99.99% specificity at the variant level, and with 90% sensitivity and 96% specificity at the patient level. In addition, our approach allowed monitoring of NSCLC ctDNA down to 4 in 10(5) cfDNA molecules. We anticipate that iDES will aid the noninvasive genotyping and detection of ctDNA in research and clinical settings.

    View details for DOI 10.1038/nbt.3520

    View details for PubMedID 27018799

  • The Causal Role of IL-4 and IL-13 in Schistosoma mansoni Pulmonary Hypertension AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE Kumar, R., Mickael, C., Chabon, J., Gebreab, L., Rutebemberwa, A., Garcia, A. R., Koyanagi, D. E., Sanders, L., Gandjeva, A., Kearns, M. T., Barthel, L., Janssen, W. J., Mauad, T., Bandeira, A., Schmidt, E., Tuder, R. M., Graham, B. B. 2015; 192 (8): 998-1008


    The etiology of schistosomiasis-associated pulmonary arterial hypertension (PAH), a major cause of PAH worldwide, is poorly understood. Schistosoma mansoni exposure results in prototypical type-2 inflammation. Furthermore, transforming growth factor (TGF)-β signaling is required for experimental pulmonary hypertension (PH) caused by Schistosoma exposure.We hypothesized type-2 inflammation driven by IL-4 and IL-13 is necessary for Schistosoma-induced TGF-β-dependent vascular remodeling.Wild-type, IL-4(-/-), IL-13(-/-), and IL-4(-/-)IL-13(-/-) mice (C57BL6/J background) were intraperitoneally sensitized and intravenously challenged with S. mansoni eggs to induce experimental PH. Right ventricular catheterization was then performed, followed by quantitative analysis of the lung tissue. Lung tissue from patients with schistosomiasis-associated and connective tissue disease-associated PAH was also systematically analyzed.Mice with experimental Schistosoma-induced PH had evidence of increased IL-4 and IL-13 signaling. IL-4(-/-)IL-13(-/-) mice, but not single knockout IL-4(-/-) or IL-13(-/-) mice, were protected from Schistosoma-induced PH, with decreased right ventricular pressures, pulmonary vascular remodeling, and right ventricular hypertrophy. IL-4(-/-)IL-13(-/-) mice had less pulmonary vascular phospho-signal transducer and activator of transcription 6 (STAT6) and phospho-Smad2/3 activity, potentially caused by decreased TGF-β activation by macrophages. In vivo treatment with a STAT6 inhibitor and IL-4(-/-)IL-13(-/-) bone marrow transplantation also protected against Schistosoma-PH. Lung tissue from patients with schistosomiasis-associated and connective tissue disease-associated PAH had evidence of type-2 inflammation.Combined IL-4 and IL-13 deficiency is required for protection against TGF-β-induced pulmonary vascular disease after Schistosoma exposure, and targeted inhibition of this pathway is a potential novel therapeutic approach for patients with schistosomiasis-associated PAH.

    View details for DOI 10.1164/rccm.201410-1820OC

    View details for Web of Science ID 000363359400015

    View details for PubMedID 26192556

    View details for PubMedCentralID PMC4642207

  • Rtp801 Suppression of Epithelial mTORC1 Augments Endotoxin-Induced Lung Inflammation. American journal of pathology Nadon, A. M., Perez, M. J., Hernandez-Saavedra, D., Smith, L. P., Yang, Y., Sanders, L. A., Gandjeva, A., Chabon, J., Koyanagi, D. E., Graham, B. B., Tuder, R. M., Schmidt, E. P. 2014; 184 (9): 2382-2389


    The mechanistic target of rapamycin (mTOR) is a central regulator of cellular responses to environmental stress. mTOR (and its primary complex mTORC1) is, therefore, ideally positioned to regulate lung inflammatory responses to an environmental insult, a function directly relevant to disease states such as the acute respiratory distress syndrome. Our previous work in cigarette smoke-induced emphysema identified a novel protective role of pulmonary mTORC1 signaling. However, studies of the impact of mTORC1 on the development of acute lung injury are conflicting. We hypothesized that Rtp801, an endogenous inhibitor of mTORC1, which is predominantly expressed in alveolar type II epithelial cells, is activated during endotoxin-induced lung injury and functions to suppress anti-inflammatory epithelial mTORC1 responses. We administered intratracheal lipopolysaccharide to wild-type mice and observed a significant increase in lung Rtp801 mRNA. In lipopolysaccharide-treated Rtp801(-/-) mice, epithelial mTORC1 activation significantly increased and was associated with an attenuation of lung inflammation. We reversed the anti-inflammatory phenotype of Rtp801(-/-) mice with the mTORC1 inhibitor, rapamycin, reassuring against mTORC1-independent effects of Rtp801. We confirmed the proinflammatory effects of Rtp801 by generating a transgenic Rtp801 overexpressing mouse, which displayed augmented inflammatory responses to intratracheal endotoxin. These data suggest that epithelial mTORC1 activity plays a protective role against lung injury, and its inhibition by Rtp801 exacerbates alveolar injury caused by endotoxin.

    View details for DOI 10.1016/j.ajpath.2014.06.002

    View details for PubMedID 25016184

    View details for PubMedCentralID PMC4188171

  • Role of vascular endothelial growth factor signaling in Schistosoma-induced experimental pulmonary hypertension. Pulmonary circulation Chabon, J. J., Gebreab, L., Kumar, R., Debella, E., Tanaka, T., Koyanagi, D., Rodriguez Garcia, A., Sanders, L., Perez, M., Tuder, R. M., Graham, B. B. 2014; 4 (2): 289-299


    There is significant evidence that Th2 (T helper 2)-mediated inflammation supports the pathogenesis of both human and experimental animal models of pulmonary hypertension (PH). A key immune regulator is vascular endothelial growth factor (VEGF), which is produced by Th2 inflammation and can itself contribute to Th2 pulmonary responses. In this study, we interrogated the role of VEGF signaling in a murine model of schistosomiasis-induced PH with a phenotype of significant intrapulmonary Th2 inflammation, vascular remodeling, and elevated right ventricular pressures. We found that VEGF receptor blockade partially suppressed the levels of the Th2 inflammatory cytokines interleukin (IL)-4 and IL-13 in both the lung and the liver after Schistosoma mansoni exposure and suppressed pulmonary vascular remodeling. These findings suggest that VEGF positively contributes to schistosomiasis-induced vascular inflammation and remodeling, and they also provide evidence for a VEGF-dependent signaling pathway necessary for pulmonary vascular remodeling and inflammation in this model.

    View details for DOI 10.1086/675992

    View details for PubMedID 25006448

    View details for PubMedCentralID PMC4070790

  • Transforming Growth Factor-beta Signaling Promotes Pulmonary Hypertension Caused by Schistosoma Mansoni CIRCULATION Graham, B. B., Chabon, J., Gebreab, L., Poole, J., Debella, E., Davis, L., Tanaka, T., Sanders, L., Dropcho, N., Bandeira, A., Vandivier, R. W., Champion, H. C., Butrous, G., Wang, X., Wynn, T. A., Tuder, R. M. 2013; 128 (12): 1354-1364


    The pathogenic mechanisms underlying pulmonary arterial hypertension resulting from schistosomiasis, one of the most common causes of pulmonary hypertension worldwide, remain unknown. We hypothesized that transforming growth factor-β (TGF-β) signaling as a consequence of Th2 inflammation is critical for the pathogenesis of this disease.Mice sensitized and subsequently challenged with Schistosoma mansoni eggs developed pulmonary hypertension associated with an increase in right ventricular systolic pressure, thickening of the pulmonary artery media, and right ventricular hypertrophy. Rho-kinase-dependent vasoconstriction accounted for ≈60% of the increase in right ventricular systolic pressure. The pulmonary vascular remodeling and pulmonary hypertension were dependent on increased TGF-β signaling, as pharmacological blockade of the TGF-β ligand and receptor, and mice lacking Smad3 were significantly protected from Schistosoma-induced pulmonary hypertension. Blockade of TGF-β signaling also led to a decrease in interleukin-4 and interleukin-13 concentrations, which drive the Th2 responses characteristic of schistosomiasis lung pathology. Lungs of patients with schistosomiasis-associated pulmonary arterial hypertension have evidence of TGF-β signaling in their remodeled pulmonary arteries.Experimental S mansoni-induced pulmonary vascular disease relies on canonical TGF-β signaling.

    View details for DOI 10.1161/CIRCULATIONAHA.113.003072

    View details for Web of Science ID 000324477900020

    View details for PubMedID 23958565

    View details for PubMedCentralID PMC3880024

  • Protective role of IL-6 in vascular remodeling in Schistosoma pulmonary hypertension. American journal of respiratory cell and molecular biology Graham, B. B., Chabon, J., Kumar, R., Kolosionek, E., Gebreab, L., Debella, E., Edwards, M., Diener, K., Shade, T., Bifeng, G., Bandeira, A., Butrous, G., Jones, K., Geraci, M., Tuder, R. M. 2013; 49 (6): 951–59


    Schistosomiasis is one of the most common causes of pulmonary arterial hypertension worldwide, but the pathogenic mechanism by which the host inflammatory response contributes to vascular remodeling is unknown. We sought to identify signaling pathways that play protective or pathogenic roles in experimental Schistosoma-induced pulmonary vascular disease via whole-lung transcriptome analysis. Wild-type mice were experimentally exposed to Schistosoma mansoni ova by intraperitoneal sensitization followed by tail-vein augmentation, and the phenotype was assessed by right ventricular catheterization and tissue histology, as well as RNA and protein analysis. Whole-lung transcriptome analysis by microarray and RNA sequencing was performed, and RNA sequencing was analyzed according to two bioinformatics methods. Functional testing of the candidate IL-6 pathway was determined using IL-6 knockout mice and the signal transducers and activators of transcription protein-3 (STAT3) inhibitor S3I-201. Wild-type mice exposed to S. mansoni demonstrated increased right ventricular systolic pressure and thickness of the pulmonary vascular media. Whole-lung transcriptome analysis determined that the IL-6-STAT3-nuclear factor of activated T cells c2(NFATc2) pathway was up-regulated, as confirmed by PCR and the immunostaining of lung tissue from S. mansoni-exposed mice and patients who died of the disease. Mice lacking IL-6 or treated with S3I-201 developed pulmonary hypertension, associated with significant intima remodeling after exposure to S. mansoni. Whole-lung transcriptome analysis identified the up-regulation of the IL-6-STAT3-NFATc2 pathway, and IL-6 signaling was found to be protective against Schistosoma-induced intimal remodeling.

    View details for DOI 10.1165/rcmb.2012-0532OC

    View details for PubMedID 23815102

    View details for PubMedCentralID PMC3931110

  • Antagonistic regulation by the transcription factors C/EBPα and MITF specifies basophil and mast cell fates. Immunity Qi, X., Hong, J., Chaves, L., Zhuang, Y., Chen, Y., Wang, D., Chabon, J., Graham, B., Ohmori, K., Li, Y., Huang, H. 2013; 39 (1): 97–110


    It remains unclear whether basophils and mast cells are derived from a common progenitor. Furthermore, how basophil versus mast cell fate is specified has not been investigated. Here, we have identified a population of granulocyte-macrophage progenitors (GMPs) that were highly enriched in the capacity to differentiate into basophils and mast cells while retaining a limited capacity to differentiate into myeloid cells. We have designated these progenitor cells "pre-basophil and mast cell progenitors" (pre-BMPs). STAT5 signaling was required for the differentiation of pre-BMPs into both basophils and mast cells and was critical for inducing two downstream molecules: C/EBPα and MITF. We have identified C/EBPα as the critical basophil transcription factor for specifying basophil cell fate and MITF as the crucial transcription factor for specifying mast cell fate. C/EBPα and MITF silenced each other's transcription in a directly antagonistic fashion. Our study reveals how basophil and mast cell fate is specified.

    View details for DOI 10.1016/j.immuni.2013.06.012

    View details for PubMedID 23871207

    View details for PubMedCentralID PMC3755602

  • Significant intrapulmonary Schistosoma egg antigens are not present in schistosomiasis-associated pulmonary hypertension. Pulmonary circulation Graham, B. B., Chabon, J., Bandeira, A., Espinheira, L., Butrous, G., Tuder, R. M. 2011; 1 (4): 456-461


    Schistosomiasis-associated pulmonary arterial hypertension (PAH) is one of the most common causes of pulmonary hypertension worldwide. A potential contributing mechanism to the pathogenesis of this disease is a localized immune reaction to retained and persistent parasite-derived antigens. We sought to identify Schistosoma-derived egg antigens present in the lungs of individuals who died of the disease. We obtained 18 lung samples collected at autopsy from individuals who died of schistosomiasis-associated PAH in Brazil. A rabbit polyclonal antibody was created to known Schistosoma mansoni-soluble egg antigen (SEA). Histologic assessment and immunostaining of the human tissue was performed, along with immunostaining and immunoblotting of lung tissue from mice experimentally infected with S. mansoni. All 18 lung samples had evidence of pulmonary vascular remodeling with plexiform lesions and arterial medial thickening, but no visible eggs were seen. The anti-SEA antibody detected S. mansoni egg antigens in visible eggs in mouse lung and human intestine specimens, but did not identify a significant amount of egg antigen in the human lung specimens. In mouse granulomas containing degraded eggs, we observed colocalization of egg antigens and macrophage lysosomes. In conclusion, there is unlikely to be a significant amount of persistent parasite-derived antigens within the lungs of individuals who die of schistosomiasis-associated PAH. This suggests that retained and persistent parasite proteins are not contributing to a localized immune response in the pathogenesis of this disease.

    View details for DOI 10.4103/2045-8932.93544

    View details for PubMedID 22530100

    View details for PubMedCentralID PMC3329075