Plasminogen mediates communication between the peripheral and central immune systems during systemic immune challenge with lipopolysaccharide

• Published in: Journal of neuroinflammation Vol. 16; no. 1; p. 172
• Main Authors: Baker, Sarah K, Chen, Zu-Lin, Norris, Erin H, Strickland, Sidney
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 28.08.2019; BioMed Central; BMC
• Subjects: Animal cognition; Animals; Antisense oligonucleotides; Biodegradation; Brain; Brain - drug effects; Brain - immunology; Brain - metabolism; Cell activation; Cell Communication - drug effects; Cell Communication - immunology; Cognitive ability; Dementia disorders; Development and progression; Disseminated infection; Drug therapy; Experiments; Extracellular matrix; Fibrinolysis; Fibrinolytic agents; Glial cells; Gliosis; Gram-negative bacteria; Immune response; Immune system; Immunity, Cellular - drug effects; Immunity, Cellular - immunology; Inflammation; Injection; Innate immunity; Laboratory animals; Leukocyte migration; Lipopolysaccharide; Lipopolysaccharides; Lipopolysaccharides - toxicity; Macrophages; Mice; Mice, Inbred C57BL; Microglia - drug effects; Microglia - immunology; Microglia - metabolism; Neurodegenerative diseases; Neurosciences; Observations; Oligonucleotides, Antisense - pharmacology; Patient outcomes; Perivascular macrophages; Plasma; Plasmin; Plasminogen; Plasminogen - antagonists & inhibitors; Plasminogen - metabolism; Serine; Serine proteinase; Wound healing; United States; United States > US; Lipopolysaccharide; Perivascular macrophages; Plasminogen
• ISSN: 1742-2094; 1742-2094
• DOI: 10.1186/s12974-019-1560-y

Systemic inflammation has been implicated in the progression of many neurodegenerative diseases and may be an important driver of the disease. Dementia and cognitive decline progress more rapidly following acute systemic infection, and systemic inflammation midlife is predictive of the degree of cognitive decline. Plasmin, the active form of the serine protease plasminogen (PLG), is a blood protein that plays physiological roles in fibrinolysis, wound healing, cell signaling, extracellular matrix degradation, and inflammatory regulation. Mice were treated with an antisense oligonucleotide to deplete liver-produced PLG prior to systemic challenge with lipopolysaccharide (LPS), a major component of the outer membrane of gram-negative bacteria, known to induce a strong immune response in animals. Following treatment, the innate immune response in the brains of these animals was examined. Mice that were PLG-deficient had dramatically reduced microgliosis and astrogliosis in their brains after LPS injection. We found that blood PLG regulates the brain's innate immune response to systemic inflammatory signaling, affecting the migration of perivascular macrophages into the brain after challenge with LPS. Depletion of plasma PLG with an antisense oligonucleotide dramatically reduced glial cell activation and perivascular macrophage migration into the brain following LPS injection. This study suggests a critical role for PLG in mediating communication between systemic inflammatory mediators and the brain.