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5 Cards in this Set
- Front
- Back
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Describe the basic functions of macrophages
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Removal of injured tissue/debris (phagocytosis, collagenase)
Antimicrobial (ROS, NO) Chemotaxis, prolif of fibroblasts (PGDF, TGF-beta, TNF, IL-1) Angiogenesis Deposition and remodeling of ECM (TNF, IL-1, collagenase) Classically activated macrophages are induced by microbial products and cytokines, particularly IFN-gamma and are microbicidal involved in potentially harmful inflammation Alternatively activated macrophages are induced by other cytokines and in response to helminths (not shown), and are important in tissue repair and the resolution of inflammation (and may play a role in defense against helminthic parasites). |
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Describe the process of phagocytosis in macrophages.
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actin polymerization shapes the pseudopod that extends
along target surface regulated by Rho GTPases --> switches on phosphoinositol kinase leads to accumulation of PI(4,5)P2 Phagosome is sealed off - actin depolymerizes at the base in response to accumulation of PI(3,4,5)P3 Actin contraction involves myosin X (non-muscle myosin) Four digestive processes mediated by the lysosome Specific receptor-mediated endocytosis Phagocytosis Pinocytosis (non-specific, constitutive) Autophagy (micro- and macro- ; intracellular proteins and organelles) |
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Describe the mechanism of reactive oxygen and nitrogen species microbicidal activity in macrophages.
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Generate a superoxide anion (reduction of oxygen)
O2->O2. -> H2O2->H2O + OH. -> H2O (hydroxyl radicals = very long lived, destroys anything like lipids, dna, rna) Catalase normally keeps it in check by keeping H2O2 low (le chatliers) *O2 requires 4 electrons to reduce it all the way to water |
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Enzymes in ROS
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NADPH oxidase
NADPH + 2O2 -> NADP+ + 2O2°- + H+ Superoxide dismutase 2H+ + 2O2- -> O2 + H202 Catalase 2H202 -> 2H20 + O2 Glutathione peroxidase (Glutathione essential for maintaining reducing potential in cytosol) 2 Glutathione-SH + H202 + -> 2H20 + Glutathione-S-S-Glutathione |
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Know the basic functions of nitric oxide in macrophages and blood vessels.
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Functions of nitric oxide (NO) in blood vessels and macrophages. NO is produced by two NO synthase (NOS) enzymes. It causes vasodilation, and NO-derived free radicals are toxic to microbial and mammalian cells.
Sustained production of NO endows macrophages with cytostatic or cytotoxic activity against viruses, bacteria, fungi, protozoa, helminths, and tumor cells. |
