ABSTRACT
BACKGROUND: Traffic-generated air pollution-exposure is associated with adverse effects in the central nervous system (CNS) in both human exposures and animal models, including neuroinflammation and neurodegeneration. While alterations in the blood brain barrier (BBB) have been implicated as a potential mechanism of air pollution-induced CNS pathologies, pathways involved have not been elucidated. OBJECTIVES: To determine whether inhalation exposure to mixed vehicle exhaust (MVE) mediates alterations in BBB permeability, activation of matrix metalloproteinases (MMP) -2 and -9, and altered tight junction (TJ) protein expression. METHODS: Apolipoprotein (Apo) E(-/-) and C57Bl6 mice were exposed to either MVE (100 µg/m(3) PM) or filtered air (FA) for 6 hr/day for 30 days and resulting BBB permeability, expression of ROS, TJ proteins, markers of neuroinflammation, and MMP activity were assessed. Serum from study mice was applied to an in vitro BBB co-culture model and resulting alterations in transport and permeability were quantified. RESULTS: MVE-exposed Apo E(-/-) mice showed increased BBB permeability, elevated ROS and increased MMP-2 and -9 activity, compared to FA controls. Additionally, cerebral vessels from MVE-exposed mice expressed decreased levels of TJ proteins, occludin and claudin-5, and increased levels of inducible nitric oxide synthase (iNOS) and interleukin (IL)-1ß in the parenchyma. Serum from MVE-exposed animals also resulted in increased in vitro BBB permeability and altered P-glycoprotein transport activity. CONCLUSIONS: These data indicate that inhalation exposure to traffic-generated air pollutants promotes increased MMP activity and degradation of TJ proteins in the cerebral vasculature, resulting in altered BBB permeability and expression of neuroinflammatory markers.
Subject(s)
Blood-Brain Barrier/drug effects , Capillary Permeability/drug effects , Inhalation Exposure/adverse effects , Matrix Metalloproteinases/genetics , Tight Junction Proteins/genetics , Vehicle Emissions/toxicity , ATP Binding Cassette Transporter, Subfamily B, Member 1/blood , Animals , Apolipoproteins E/genetics , Blood-Brain Barrier/enzymology , Blood-Brain Barrier/metabolism , Blotting, Western , Coculture Techniques , Endothelial Cells/drug effects , Endothelial Cells/metabolism , Endothelial Cells/pathology , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Neurogenic Inflammation/blood , Neurogenic Inflammation/chemically induced , Neurogenic Inflammation/enzymology , Neuroglia/drug effects , Neuroglia/metabolism , Neuroglia/pathologyABSTRACT
OBJECTIVES: The aim of this study was to compare plasma biomarkers of coagulation between HIV-infected individuals and HIV-uninfected controls and to assess the impact of disturbances in coagulation on neurocognitive functioning in HIV. DESIGN: A cross-sectional study of 66 antiretroviral therapy treated, virally suppressed, HIV-infected and 34 HIV-uninfected older (≥50 years of age) adults. METHODS: Participants completed standardized neurobehavioral and neuromedical assessments. Neurocognitive functioning was evaluated using a well validated comprehensive neuropsychological battery. Plasma biomarkers associated with procoagulation (fibrinogen, p-selectin, tissue factor and von Willebrand factor), anticoagulation (antithrombin, protein C and thrombomodulin), fibrinolysis (d-dimer, plasminogen activator inhibitor-1 and plasminogen) were collected. Multivariable linear regression was used to test the interaction of HIV and coagulation on neurocognitive functioning. RESULTS: Most participants were male (78.0%) and non-Hispanic white (73.0%) with a mean age of 57.8 years. Among HIV-infected participants, mean estimated duration of HIV infection was 19.4 years and median current CD4 cell count was 654âcells/µl. Levels of soluble biomarkers of procoagulation, anticoagulation and fibrinolysis were comparable between the HIV serostatus groups. Coagulation and HIV had an interacting effect on neurocognitive functioning, such that greater coagulation imbalance was associated with poorer neurocognitive functioning among the HIV-infected participants. The moderating effect of coagulation on neurocognition was driven by procoagulant but not anticoagulant or fibrinolytic biomarkers. CONCLUSIONS: Elevated levels of procoagulants may exert a particularly detrimental effect on neurocognitive functioning among older HIV-infected persons. A better understanding of the specific role of coagulation in the cause of HIV-associated neurocognitive disorders may lead to treatments aimed at reducing coagulopathy, thereby improving neurocognitive outcomes.