Christopher Cheadle

Angiotensin receptor blockade attenuates cigarette smoke–induced lung injury and rescues lung architecture in mice

Chronic obstructive pulmonary disease (COPD) is a prevalent smoking-related disease for which no disease-altering therapies currently exist. As dysregulated TGF-β signaling associates with lung pathology in patients with COPD and in animal models of lung injury induced by chronic exposure to cigarette smoke (CS), we postulated that inhibiting TGF-β signaling would protect against CS-induced lung injury. We first confirmed that TGF-β signaling was induced in the lungs of mice chronically exposed to CS as well as in COPD patient samples. Importantly, key pathological features of smoking-associated lung disease in patients, e.g., alveolar injury with overt emphysema and airway epithelial hyperplasia with fibrosis, accompanied CS-induced alveolar cell apoptosis caused by enhanced TGF-β signaling in CS-exposed mice. Systemic administration of a TGF-β-specific neutralizing antibody normalized TGF-β signaling and alveolar cell death, conferring improved lung architecture and lung mechanics in CS-exposed mice. Use of losartan, an angiotensin receptor type 1 blocker used widely in the clinic and known to antagonize TGF-β signaling, also improved oxidative stress, inflammation, metalloprotease activation and elastin remodeling. These data support our hypothesis that inhibition of TGF-β signaling through angiotensin receptor blockade can attenuate CS-induced lung injury in an established murine model. More importantly, our findings provide a preclinical platform for the development of other TGF-β-targeted therapies for patients with COPD.

Identification of Candidate Genes in Scleroderma-Related Pulmonary Arterial Hypertension

We hypothesize that pulmonary arterial hypertension (PAH)-associated genes identified by expression profiling of peripheral blood mononuclear cells (PBMCs) from patients with idiopathic pulmonary arterial hypertension (IPAH) can also be identified in PBMCs from scleroderma patients with PAH (PAH-SSc). Gene expression profiles of PBMCs collected from IPAH (n = 9), PAH-SSc (n = 10) patients, and healthy controls (n = 5) were generated using HG_U133A_2.0 GeneChips and were processed by the RMA/GCOS_1.4/SAM_1.21 data analysis pipeline. Disease severity in consecutive patients was assessed by functional status and hemodynamic measurements. The expression profiles were analyzed using PAH severity-stratification, and identified candidate genes were validated with real-time polymerase chain reaction (PCR). Transcriptomics of PBMCs from IPAH patients was highly comparable with that of PMBCs from PAH-SSc patients. The PBMC gene expression patterns significantly correlate with right atrium pressure (RA) and cardiac index (CI), which are known predictors of survival in PAH. Array stratification by RA and CI identified 364 PAH-associated candidate genes. Gene ontology (GO) analysis revealed significant (Z(score) > 1.96) alterations in angiogenesis genes according to PAH severity: matrix metalloproteinase 9 (MMP9) and vascular endothelial growth factor (VEGF) were significantly upregulated in mild as compared with severe PAH and healthy controls, as confirmed by real-time PCR. These data demonstrate that PBMCs from patients with PAH-SSc carry distinct transcriptional expression. Furthermore, our findings suggest an association between angiogenesis-related gene expression and severity of PAH in PAH-SSc patients. Deciphering the role of genes involved in vascular remodeling and PAH development may reveal new treatment targets for this devastating disorder.

Autoantibody Cancer Biomarker: Extracellular Protein Kinase A

In cancer cells, cyclic AMP-dependent protein kinase (PKA) is secreted into the conditioned medium. This PKA, designated as extracellular protein kinase A (ECPKA), is markedly up-regulated in the sera of patients with cancer. The currently available tumor markers are based on the antigen determination method and lack specificity and sensitivity. Here, we present an ECPKA autoantibody detection method for a universal biomarker that detects cancer of various cell types. We tested sera from 295 patients with cancers of various cell types, 155 normal controls, and 55 patients without cancer. The specificity and sensitivity of this autoantibody enzyme immunoassay method were compared with the conventional antigen determination method by receiver-operating characteristic plots. In the sera, the presence of autoantibody directed against ECPKA was highly correlated with cancer. High anti-ECPKA autoantibody titers (frequency, 90%; mean titer, 3.0) were found in the sera of patients with various cancers, whereas low or negative titers (frequency, 12%; mean titer, 1.0) were found in the control group. The receiver-operating characteristic plot showed that autoantibody enzyme immunoassay exhibited 90% sensitivity and 88% specificity, whereas the enzymatic assay exhibited 83% sensitivity and 80% specificity. These results show that the autoantibody method distinguished between patients with cancer and controls better than the antigen method could. Our results show that autoantibody ECPKA is a universal serum biomarker for cancers of various cell types.

Activated protein C protects against ventilator-induced pulmonary capillary leak

The coagulation system is central to the pathophysiology of acute lung injury. We have previously demonstrated that the anticoagulant activated protein C (APC) prevents increased endothelial permeability in response to edemagenic agonists in endothelial cells and that this protection is dependent on the endothelial protein C receptor (EPCR). We currently investigate the effect of APC in a mouse model of ventilator-induced lung injury (VILI). C57BL/6J mice received spontaneous ventilation (control) or mechanical ventilation (MV) with high (HV(T); 20 ml/kg) or low (LV(T); 7 ml/kg) tidal volumes for 2 h and were pretreated with APC or vehicle via jugular vein 1 h before MV. In separate experiments, mice were ventilated for 4 h and received APC 30 and 150 min after starting MV. Indices of capillary leakage included bronchoalveolar lavage (BAL) total protein and Evans blue dye (EBD) assay. Changes in pulmonary EPCR protein and Rho-associated kinase (ROCK) were assessed using SDS-PAGE. Thrombin generation was measured via plasma thrombin-antithrombin complexes. HV(T) induced pulmonary capillary leakage, as evidenced by significant increases in BAL protein and EBD extravasation, without significantly increasing thrombin production. HV(T) also caused significant decreases in pulmonary, membrane-bound EPCR protein levels and increases in pulmonary ROCK-1. APC treatment significantly decreased pulmonary leakage induced by MV when given either before or after initiation of MV. Protection from capillary leakage was associated with restoration of EPCR protein expression and attenuation of ROCK-1 expression. In addition, mice overexpressing EPCR on the pulmonary endothelium were protected from HV(T)-mediated injury. Finally, gene microarray analysis demonstrated that APC significantly altered the expression of genes relevant to vascular permeability at the ontology (e.g., blood vessel development) and specific gene (e.g., MAPK-associated kinase 2 and integrin-beta(6)) levels. These findings indicate that APC is barrier-protective in VILI and that EPCR is a critical participant in APC-mediated protection.

Regulatory T cell-mediated resolution of lung injury: identification of potential target genes via expression profiling.

In animal models of acute lung injury (ALI), gene expression studies have focused on the acute phase of illness, with little emphasis on resolution. In this study, the acute phase of intratracheal lipopolysaccharide (IT LPS)-induced lung injury was similar in wild-type (WT) and recombinase-activating gene-1-deficient (Rag-1(-/-)) lymphocyte-deficient mice, but resolution was impaired and resolution-phase lung gene expression remained different from baseline only in Rag-1(-/-) mice. By focusing on groups of genes involved in similar biological processes (gene ontologies) pertinent to inflammation and the immune response, we identified 102 genes at days 4 and 10 after IT LPS with significantly different expression between WT and Rag-1(-/-) mice. After adoptive transfer of isolated CD4+CD25+Foxp3+ regulatory T cells (Tregs) to Rag-1(-/-) mice at the time of IT LPS, resolution was similar to that in WT mice. Of the 102 genes distinctly changed in either WT or Rag-1(-/-) mice from our 7 gene ontologies, 19 genes reverted from the Rag-1(-/-) to the WT pattern of expression after adoptive transfer of Tregs, implicating those 19 genes in Treg-mediated resolution of ALI.

CD14, a key candidate gene associated with a specific immune response to cockroach

Background Sensitization to cockroach allergen is one of the strongest predictors of asthma morbidity, especially among African Americans.

Abstract 446: Differential expression of immuno-regulatory genes associated with PD-L1 display: Implications for clinical blockade of the PD-1/PD-L1 pathway in melanoma.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DCnnBackground: Blockade of the immunosuppressive PD-1/PD-L1 pathway has shown promising clinical results in patients with treatment-refractory solid tumors including melanoma. PD-L1, a protein displayed by many tumors, ligates the PD-1 co-inhibitory receptor on activated T cells. We previously found that IFN-γ, a potent inducer of PD-L1, was expressed by TILs in PD-L1(+) but not PD-L1(-) melanomas, creating an immunosuppressive microenvironment by a mechanism that we term “adaptive immune resistance” (Taube et al., Science Transl Med 2012). In the current study, we assessed other factors associated with PD-L1 expression in melanoma through differential gene expression analysis, in order to better understand the biology of this pathway and identify potential targets for combination immunotherapies.nnMethods: PD-L1(+) vs. (-) melanomas including immune cell infiltrates (n=11) were laser-capture microdissected (LCM) from formalin-fixed paraffin embedded (FFPE) specimens and analyzed by whole genome array analysis with cDNA-mediated Annealing, Selection, extension and Ligation (DASL), a novel technology that allows for gene expression analysis with partially degraded mRNAs obtained from FFPE specimens. Differentially expressed genes were submitted to the NIH functional analysis tool DAVID to search for enrichment in biologically related groups. Multiplex quantitative (q)RT-PCR was used to validate differential expression of genes of interest and to examine other candidate genes in new set of PD-L1(+) vs.(-) melanomas (n=11).nnResults: DASL/DAVID analysis of PD-L1(+) vs. PD-L1(-) melanomas uncovered genes of interest in several immunologically relevant pathways, including “Defense Response” (p<1.5E-9) and “T-cell activation” (p<2.2E-5). Multiplex qRT-PCR to examine genes of interest from the DAVID analysis along with other potentially relevant candidate genes was normalized to the GUSB housekeeping gene or to CD45 (pan-leukocyte marker), revealing over-expression of genes associated with immunosuppression (PD-1, PD-L1, LAG-3, IL-10), activated CD8 T cells (CD8A, IFN-γ, lysozyme, perforin, CCL5/RANTES), and antigen presenting cells (CD163, TLR3, CXCL1) in PD-L1(+) melanomas (p<0.10).nnConclusions: These experiments identified groups of functionally related, differentially expressed immuno-regulatory genes in PD-L1(+) melanomas. These factors may coordinately create an immunosuppressive tumor microenvironment, by synergizing to enhance PD-L1 expression on tumor cells and to inhibit T cell function. Immunohistochemical and in vitro functional validation assays of candidate gene products are currently underway in order to identify new ways to overcome adaptive immune resistance in synergistic treatment combinations with PD-1/PD-L1 blockade.nnCitation Format: Geoffrey D. Young, Tracee L. McMiller, Haiying Xu, Shuming Chen, Alan E. Berger, Jinshui Fan, Robert A. Anders, Christopher Cheadle, Drew M. Pardoll, Suzanne L. Topalian, Janis M. Taube. Differential expression of immuno-regulatory genes associated with PD-L1 display: Implications for clinical blockade of the PD-1/PD-L1 pathway in melanoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 446. doi:10.1158/1538-7445.AM2013-446