1. General Pathology Basic Principles of Cellular and Organ Pathology Steatosis. Mitochondrial and Peroxisomal Disorders. Jaroslava Dušková Inst. Pathol.,1st Med. Faculty, Charles Univ. Prague

2. Steatosis (Fatty Change) Definition: acquired metabolic disorder with intracellular accumulation of lipid droplets (lipomatosis, adipositas - increase of fatty tissue amount)

3. Steatosis - morphology Macroscopy: yellowish - orange color of organs (+ carotenoids - lipochrom) Microscopy: microvacuolar cytoplasm - foamy cell macrovacuolar - unilocular

4. Steatosis hepatis LIVER - major organ of fat metabolism) abnormal accumulations of TRIGLYCERIDES within parenchymal cells Causes: alcohol abuse, protein malnutrition, diabetes mellitus, obesity, toxins,drugs, anoxia Macro: enlarged, yellow, greasy, soft Micro: small fatty, cytoplasmic droplets OR large vacuoles

5. Lipids accumulation in cells (sometimes causing cellular injury)  A normal cellular constituent accumulating in excess  An abnormal substance, usually a product of abnormal metabolism  A pigment

6. Processes resulting in abnormal intracellular accumulations  Abnormal metabolism of a normal endogenous substance (e. g. fatty liver)  Lack of an enzyme necessary for the metabolism of a normal or abnormal endogenous substance (e. g. lysosomal storage disease)

7. Clear Intracellular Vacuoles & adjunct techniques u accumulations of water neg. u lipides SUDAN, OIL RED u polysaccharides PAS, A-PAS

8. Lipidosis (thesaurismosis, lipid storage disease) Definition: inborn metabolic disorder with intracellular accumulation of lipid droplets (lysosomal enzymopathies)

9. Organelles Involved in Lipid Metabolism u Granular Endoplasmic Reticulum GER + Golgi app. u mitochondria u lysosomes

10. GER - l ipoprotein synthesis u enterocytes Apo B48 monoacylglycerols (fatty acids) triacylglycerols - chylomicrons u hepatocytes Apo B100 Very Low Density Lipoproteins

11. GER - l ipoprotein synthesis DISORDERS hepatocytes lack of Apo B100 synthesis - toxins toxic steatosis

12. Mitochondria - beta oxidation u fatty acids - carnitinacyltranpherase 1 + coenzyme A - carnitinacyltranspherase 2 beta oxidation

13. Mitochondria - beta oxidation DISORDERS u fatty acids - carnitinacyltranpherase 1 + coenzyme A - transport malfunction carnitinacyltranpherase 2 beta oxidation defect - hypoxia, anoxia hypoxic steatosis

14. Mitochondria - semiautonomous organelles (circular mtDNA, division) u isolated u network u spiral chain Outer membrane Inner membrane Cristae Matrix

15. Mitochondria - semiautonomous organelles (circular mtDNA, division) Function beta oxidation, Krebs cycle, OXFOS protein sorting & synthesis

16. Mitochondria - life cycle u division u majority of proteins coded in the nucleus u degradation in the autophagosomes

17. Mitochondria - genetics u circular mtDNA u haploid (maternal origin) u 2-20 mtDNA molecules in one mitochondrion u 100 -10 000 mtDNA molecules in one cell variable amplification

18. Mitochondria vs. Nucleus genetics u circular mtDNA u haploid (maternal origin) u 2-20 mtDNA molecules in one mitochondrion u 100 -10 000 mtDNA molecules in one cell u asynchrone replication u linear - chromosomes u diploid 23 pairs (maternal+paternal) u 46 macromolecules per one nucleus u 46 macromolecules per one cell u synchronized replication

19. Mitochondria vs. Nucleus genetics homoplasmia heteroplasmia polyplasmia only some copies normal + mutated mtDNA threshold effect u homozygotic u heterozygotic – carriers

20. Nuclear genes Ex. GRIM-19 Mt genes (Complex I, III, IV, V) Hürthle cell features Mitochondrial proliferation Activation of HIF-1 & Decreased apoptosis Tumourigenesis

21. Mitochondria - pathology u acquired – mitochondriosis – oncocytic change u inborn – enzymopathies

22. Mitochondria - pathology v inborn - enzymopathies Synthesis defects (partly nucleus coded): v urea and porphyrine v transport proteins v Krebs cycle enzymes succinate deh. v OXFOS nucleus & mitoch. coded

23. Lysosomes - l ipid hydrolysis u enzymes - lipase, phospholipase, sphingomyelinase etc…. membrane diffusion, reutilisation storage TAG, ChE transport from the cell - HDL, apo E

24. Lysosomes - l ipid hydrolysis DISORDERS u acquired - intensive endocytosis of lipids - histiocytes u hereditary - lipidoses, lipid storage dis.

25. Storage Diseases Def.: inborn errors of metabolism (mostly single gene abnormality) leading to an enzyme defect with subsequent accumulation of the substrate (& lack of the product) in tissues or organs „thesaurismoses“

26. Lipid Storage Diseases -1. DiseaseE- defAccum. Lipid Tissues Involved Tay-SachsHexos aminidase A GM2 ganglioside Brain, retina Gaucher  - Glucosidase Gluco cerebrosid Liver, spleen, bone marrow, brain Niemann- Pick Sphingo myelinase Sphingo myelin Brain, liver spleen

27. Lipid Storage Diseases – 2. DiseaseE- defAccum. Lipid Tissues Involved Metachro matic Leuco dystrophy Arylsulfat ase A SulfatidBrain, kidney, liver, peripheral nerves Fabry´s  -galactosid ase Ceramid trihexosid Skin, kidney Krabbe´sGalactosyl ceramidase Galactol cerebroside Brain

28. Extracellular Steatosis u blood: hyperlipemiae –increased size of lipoprotein particles (rel. decrease of the apoprotein component) –increased number of lipoprotein particles removed after oxidation via „scavenger receptors“ – resulting e.g. into aggravated & accelerated atherosclerosis, pancreatic necrosis –arcus senilis myringis, arcus senilis corneae

29. Lipids in Cell Signaling - 1 u Many of the lipids involved as second messengers in cell signaling pathways arise from the arachidonic acid (AA) pathway. u AA is an unsaturated fatty acid u a normal constituent of membrane phospholipids u released from the phospholipids by the actions of phospholipase A2 (PLA2).

30. Lipids in Cell Signaling - 2 u Prostaglandins (PG) are generated by the cyclooxygenase (COX). u There is a constitutive (COX-1) and an inducible cyclooxygenase (COX-2). u The cyclic endoperoxide intermediate is also a precursor of prostacyclin (PGI2) and thromboxane (TXA3).

31. Lipids in Cell Signaling - 3 u leukotrienes (LT) and lipoxins (LP), are derived directly from AA without the mediation of a cyclic endoperoxide. u LT induce inflammation by their chemotactic and degranulating actions on polymorphonuclear leucocytes (PML) u the amino acid containing LTs induce vasoconstriction and bronchoconstriction and are involved in asthma and anaphylaxis.

32. Peroxisomes - microbodies up to 2 microns - catalase Function Degradation: substrate oxidation (etanol) Anabolism: synthesis of prostaglandin, cholesterol, billiary acids, plasmalogens, gluconeogenesis, transamination

33. Peroxisomes - microbodies DISORDERS Lack of: Degradation: substrate oxidation e.g. etanol... Anabolism: synthesis of prostaglandin, cholesterol, billiary acids, gluconeogenesis, transamination...