Plasma Glycoproteomics Reveals Sepsis Outcomes Linked to Distinct Proteins in Common Pathways.

OBJECTIVE: Sepsis remains a predominant cause of mortality in the ICU, yet strategies to increase survival have proved largely unsuccessful. This study aimed to identify proteins linked to sepsis outcomes using a glycoproteomic approach to target extracellular proteins that trigger downstream pathways and direct patient outcomes. DESIGN: Plasma was obtained from the Lactate Assessment in the Treatment of Early Sepsis cohort. N-linked plasma glycopeptides were quantified by solid-phase extraction coupled with mass spectrometry. Glycopeptides were assigned to proteins using RefSeq (National Center of Biotechnology Information, Bethesda, MD) and visualized in a heat map. Protein differences were validated by immunoblotting, and proteins were mapped for biological processes using Database for Annotation, Visualization and Integrated Discovery (National Institute of Allergy and Infectious Diseases, National Institutes of Health; Bethesda, MD) and for functional pathways using Kyoto Encyclopedia of Genes and Genomes (Kanehisa Laboratories, Kyoto, Japan) databases. SETTING: Hospitalized care. PATIENTS: Patients admitted to the emergency department were enrolled in the study when the diagnosis of sepsis was made, within 6 hours of presentation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 501 glycopeptides corresponding to 234 proteins were identified. Of these, 66 glycopeptides were unique to the survivor group and corresponded to 54 proteins, 60 were unique to the nonsurvivor group and corresponded to 43 proteins, and 375 were common responses between groups and corresponded to 137 proteins. Immunoblotting showed that nonsurvivors had increased total kininogen; decreased total cathepsin-L1, vascular cell adhesion molecule, periostin, and neutrophil gelatinase-associated lipocalin; and a two-fold decrease in glycosylated clusterin (all p < 0.05). Kyoto Encyclopedia of Genes and Genomes analysis identified six enriched pathways. Interestingly, survivors relied on the extrinsic pathway of the complement and coagulation cascade, whereas nonsurvivors relied on the intrinsic pathway. CONCLUSION: This study identifies proteins linked to patient outcomes and provides insight into unexplored mechanisms that can be investigated for the identification of novel therapeutic targets.

Myocardial matrix metalloproteinase-2: inside out and upside down.

Since their inaugural discovery in the early 1960s, matrix metalloproteinases (MMPs) have been shown to mediate multiple physiological and pathological processes. In addition to their canonical function in extracellular matrix (ECM) remodeling, research in the last decade has highlighted new MMP functions, including proteolysis of novel substrates beyond ECM proteins, MMP localization to subcellular organelles, and proteolysis of susceptible intracellular proteins in those subcellular compartments. This review will provide a comparison of the extracellular and intracellular roles of MMPs, illustrating that MMPs are far more interesting than the one-dimensional view originally taken. We focus on the roles of MMP-2 in cardiac injury and repair, as this is one of the most studied MMPs in the cardiovascular field. We will highlight how understanding all dimensions, such as localization of activity and timing of interventions, will increase the translational potential of research findings. Building upon old ideas and turning them inside out and upside down will help us to better understand how to move the MMP field forward.

Mitochondrial DNA damage mediates hyperoxic dysmorphogenesis in rat fetal lung explants.

BACKGROUND: Numerous studies in cultured cells indicate that damage to mitochondrial DNA (mtDNA) dictates cellular responses to oxidant stress, yet the consequences of mtDNA damage have not been studied directly in the preterm lung. OBJECTIVE: We sought to determine whether hyperoxia-induced fetal lung dysmorphogenesis is linked to mtDNA damage and establish mtDNA repair as a potential therapeutic approach for treating lung dysplasia in the preterm neonate. METHODS: Hyperoxia-induced mtDNA damage was assessed by quantitative alkaline gel electrophoresis in normoxic (3% O2) and hyperoxic (21% O2) fetal rat lung explants. A fusion protein construct targeting the DNA repair enzyme endonuclease III (Endo III) to the mitochondria was used to augment mtDNA repair. Fetal lung branching and surfactant protein C (SFPTC) were assessed in these tissues. RESULTS: Hyperoxia induced mtDNA damage in lung explants and was accompanied by impaired branching morphogenesis and decreased SFPTC mRNA expression. Treatment of lung explants with Endo III fusion protein prevented hyperoxia-induced mtDNA damage and restored normal branching morphogenesis and SFPTC mRNA expression. CONCLUSION: These findings support the concept that mtDNA governs cellular responses to oxidant stress in the fetal lung and suggest that modulation of mtDNA repair is a potential pharmacologic strategy in the prevention of hyperoxic lung injury.