Molecular Analysis of Serum and Bronchoalveolar Lavage in a Mouse Model of Influenza Reveals Markers of Disease Severity That Can Be Clinically Useful in Humans

Abstract

BackgroundManagement of influenza, a major contributor to the worldwide disease burden, is complicated by lack of reliable methods for early identification of susceptible individuals. Identification of molecular markers that can augment existing diagnostic tools for prediction of severity can be expected to greatly improve disease management capabilities.Methodology/Principal FindingsWe have analyzed cytokines, proteome flux and protein adducts in bronchoalveolar lavage (BAL) and sera from mice infected with influenza A virus (PR8 strain) using a previously established non-lethal model of influenza infection. Through detailed cytokine and protein adduct measurements of murine BAL, we first established the temporal profile of innate and adaptive responses as well as macrophage and neutrophil activities in response to influenza infection. A similar analysis was also performed with sera from a longitudinal cohort of influenza patients. We then used an iTRAQ-based, comparative serum proteome analysis to catalog the proteome flux in the murine BAL during the stages correlating with “peak viremia,” “inflammatory damage,” as well as the “recovery phase.” In addition to activation of acute phase responses, a distinct class of lung proteins including surfactant proteins was found to be depleted from the BAL coincident with their “appearance” in the serum, presumably due to leakage of the protein following loss of the integrity of the lung/epithelial barrier. Serum levels of at least two of these proteins were elevated in influenza patients during the febrile phase of infection compared to healthy controls or to the same patients at convalescence.Conclusions/SignificanceThe findings from this study provide a molecular description of disease progression in a mouse model of influenza and demonstrate its potential for translation into a novel class of markers for measurement of acute lung injury and improved case management.

Glutathione Reaction Products with a Chemical Allergen, Methylene-diphenyl Diisocyanate, Stimulate Alternative Macrophage Activation and Eosinophilic Airway Inflammation

“…The two most downregulated proteins (XRCC1 and INMT) are thought to function in repairing or limiting tissue damage, specifically that involving single-strand DNA breaks, xenobiotics, or endogenous amino, sulfo, or selenium compounds. 36,37 Overall, the protein changes in the airways of sensitized, GSH–MDI exposed mice are distinct compared with those induced by other respiratory tract exposures 49–51 and might serve as biomarkers of MDI exposure and/or asthma.…”

Maternal high‐fat diet in mice leads to innate airway hyperresponsiveness in the adult offspring

“…Total protein in BALF has been used previously to demonstrate alveolar capillary leak or airway inflammation following infection (Kumar et al. ), although it is not elevated in human atopic studies (Schock et al. ).…”

Challenges and emergent solutions for LC‐MS/MS based untargeted metabolomics in diseases

“…To circumvent limitations associated with human studies, animal model studies can be conducted, and tissues and biofluids collected and compared, within the animal model or animal‐to‐human. To this effect, serum metabolome changes gained from clinical studies were compared to humanized mouse serum, broncho alveolar‐lavage fluid (BALF), and lung tissue metabolomes . In influenza, metabolomics was used to compare qualitative and quantitative differences between the animal model and human infection.…”