Acute Respiratory Distress Syndrome (ARDS) continues to have a high mortality. Currently, there are no biomarkers that provide reliable prognostic information to guide clinical management or stratify risk among clinical trial participants. The objective of this study was to probe the bronchoalveolar lavage fluid (BALF) proteome to identify proteins that differentiate survivors from non-survivors of ARDS. Patients were divided into early-phase (1 to 7 days) and late-phase (8 to 35 days) groups based on time after initiation of mechanical ventilation for ARDS (Day 1). Isobaric tags for absolute and relative quantitation (iTRAQ) with LC MS/MS was performed on pooled BALF enriched for medium and low abundance proteins from early-phase survivors (n = 7), early-phase non-survivors (n = 8), and late-phase survivors (n = 7). Of the 724 proteins identified at a global false discovery rate of 1%, quantitative information was available for 499. In early-phase ARDS, proteins more abundant in survivors mapped to ontologies indicating a coordinated compensatory response to injury and stress. These included coagulation and fibrinolysis; immune system activation; and cation and iron homeostasis. Proteins more abundant in early-phase non-survivors participate in carbohydrate catabolism and collagen synthesis, with no activation of compensatory responses. The compensatory immune activation and ion homeostatic response seen in early-phase survivors transitioned to cell migration and actin filament based processes in late-phase survivors, revealing dynamic changes in the BALF proteome as the lung heals. Early phase proteins differentiating survivors from non-survivors are candidate biomarkers for predicting survival in ARDS.

L604 -L614, 2013. First published September 6, 2013 doi:10.1152/ajplung.00079.2013.-In rodent model systems, the sequential changes in lung morphology resulting from hyperoxic injury are well characterized and are similar to changes in human acute respiratory distress syndrome. In the injured lung, alveolar type two (AT2) epithelial cells play a critical role in restoring the normal alveolar structure. Thus characterizing the changes in AT2 cells will provide insights into the mechanisms underpinning the recovery from lung injury. We applied an unbiased systems-level proteomics approach to elucidate molecular mechanisms contributing to lung repair in a rat hyperoxic lung injury model. AT2 cells were isolated from rat lungs at predetermined intervals during hyperoxic injury and recovery. Protein expression profiles were determined by using iTRAQ with tandem mass spectrometry. Of the 959 distinct proteins identified, 183 significantly changed in abundance during the injury-recovery cycle. Gene ontology enrichment analysis identified cell cycle, cell differentiation, cell metabolism, ion homeostasis, programmed cell death, ubiquitination, and cell migration to be significantly enriched by these proteins. Gene set enrichment analysis of data acquired during lung repair revealed differential expression of gene sets that control multicellular organismal development, systems development, organ development, and chemical homeostasis. More detailed analysis identified activity in two regulatory pathways, JNK and miR 374. A novel short time-series expression miner algorithm identified protein clusters with coherent changes during injury and repair. We concluded that coherent changes occur in the AT2 cell proteome in response to hyperoxic stress. These findings offer guidance regarding the specific molecular mechanisms governing repair of the injured lung. alveolar epithelial cell proteome; acute respiratory distress syndrome; bioinformatics; hyperoxia HEALTHY RATS AND MICE EXPOSED to 100% oxygen develop respiratory failure and death within 2-3 days (2, 20). Histological examination of lungs from these animals shows pathological changes similar to those that occur in human acute respiratory distress syndrome (ARDS), with evidence of apoptosis and necrosis of the alveolar endothelium and epithelium (4, 20). There is evidence that hyperoxia is damaging to the human lung as well (8,24,33).Rodent lung morphology has been well characterized during acute oxygen-lung toxicity and subsequent recovery (19,20,58). In animals, exposure to normobaric hyperoxia for 72 h results in an exudative phase that is characterized by alveolar type I (AT1) epithelial cell death, swelling and necrosis of endothelial cells, interstitial edema, and filling of alveoli with an exudative fluid (19,33). Cessation of oxygen exposure after 60 h leads to a rapid decrease in the number of neutrophils within the first 3 days and an increase in the number of monocytes and lymphocytes, resulting in a normal differential of lung white blood cells by day 7 (58)...

Context Our previous case-control study identified human neutrophil peptide (HNP) as a potential biomarker for bronchiolitis obliterans syndrome (BOS) in lung transplant recipients. Objective To prospectively validate HNP as a biomarker for BOS. Materials and Methods HNP was measured by ELISA in bronchoalveolar lavage (BAL) fluid in lung transplant recipients. Results The first HNP measurement after reaching baseline pulmonary function was predictive of developing BOS ≥2 (p=0.0419). HNP remained elevated in those that developed BOS. The effect of potential confounders did not significantly impact BOS-free survival time. Conclusion HNP levels are elevated early and persistently in those that develop BOS.

Background: Lung transplant is an effective therapy, however, long-term survival is currently limited due to the high rate of bronchiolitis obliterans syndrome (BOS). The longitudinal biological changes that occur as a patient progresses to BOS are not well understood. The objective of this study was to evaluate the bronchoalveolar lavage fluid (BALF) proteome, seeking to identify proteins and their representative biological functions that have coherent changes in the development of BOS. Methods: Isobaric tag for relative and absolute quantification(iTRAQ ® ) with LC MS/MS were performed on BALF enriched for medium and low abundance proteins from three time points (range 699 days pre-BOS to 83 days post-BOS) taken from four patients that developed BOS. Controls consisted of pooled samples from nine patients who did not develop BOS within five years of sample acquisition. We investigated how the protein profiles changed longitudinally as the patient progressed towards BOS using Short Time-series Expression Miner, (STEM), analysis and identified gene ontology terms associated with these protein clusters. Results: We identified 871 unique proteins at a 5% FDR. STEM analysis revealed three models that met statistical significance.Gene ontology revealed three biological processes that associated with these models and included: sequestering of actin monomers, cytoskeletal organization and an inflammatory or defense response. Conclusion: Longitudinal and gene cluster models reveal coherent changes in BALF proteins as patients approach BOS.

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