1 PHM142 Metabolic Biochemistry and Immunology II WHITE CELLS CHEMICAL WARFARE lecture outline 1) Molecular mechanisms of leukocyte function • Rheumatoid arthritis • CGD disease 2) Eosinophils 3)Macrophages • Function • Growth factors and cytokines • But – macrophage - induced tissue injury
44
Embed
1 PHM142 Metabolic Biochemistry and Immunology II WHITE CELLS CHEMICAL WARFARE lecture outline 1)Molecular mechanisms of leukocyte function Rheumatoid.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
PHM142 Metabolic Biochemistry and Immunology II WHITE CELLS
CHEMICAL WARFARE lecture outline
1) Molecular mechanisms of leukocyte function• Rheumatoid arthritis• CGD disease
2) Eosinophils
3) Macrophages • Function• Growth factors and cytokines• But – macrophage - induced tissue injury• Multiple organ failure, ARDS, sepsis
2Blood CellsType of cell
Red blood cells (erythrocytes)
White blood cells (leukocytes) polymorphonuclear/granular leukocytesNeutrophils (50 60%)Eosinophils (1 4%)
Basophils (0.5 2%)
mononuclear leukocytes
Lymphocytes (20 40%)
Monocytes (2 9%) ( macrophages in extravascular tissue)Killer cells
Megakaryocytes ( platelets)
Main function
Transport O2 and CO2
Destroy invading bacteria
Phagocytose & kill invading antigensDestroy parasites and modulate allergic inflammatory reactionsRelease histamine, serotonin, bradykinin, heparin, and cytokines; converts arachidonic acid to prostaglandins & leukotrienes
(T & B) mediate cytokine release
Phagocytose & kill ingested microbes Kill virally infected cells and tumor cells (offer “natural” immunity as well as adaptive)Initiate blood clotting; also release histamine and serotonin
3
Thin sections of the major types of white blood cells (leukocytes) foundin the circulation, showing the variety of internal structures observed.
12
Macrophage3
4Molecular mechanisms of neutrophil functionAmer J Med. 109, 33-44 (2000)
superoxide detected by NBT reduction to formazan (blue precipitate).
*
* Made by bacteria; recognized by mammalian cells as foreign.
8
Trends in Biochem.Sci. 2, 63 (1977)
9
Activation of leukocyte NADPH oxidase (Nox) showing assembly of the enzyme and fusion of the oxidase-containing vesicle with the phagosomal membrane.
Babior, 2000. American Journal of Medicine. 109:33 44.
10
NADPH oxidase (Nox)activation
Proton Channel Function
Medicine 79, 170-200 (2000)
b558
+ H+
ProtonChannel
(phosphorylationby kinase)
gp91phox is b558 with proton channel (or K+?)
phox is “phagocyte oxidase”
membrane
Vacuolar space
b558
11
bact.
• CGD can kill Bacteria that produce H2O2 and have low catalase activity, e.g., streptococci.• But can’t kill bacteria which have high catalase activity or low H2O2 production, e.g., serratia, nocardia, and aspergillus; fungal, staphylococcus, burkholderia (pneumonia, sepsis).
Chronic Granulomatous Disease (CGD)
NADPH OXIDASE DEFICIENCY
White Cell
0.1 M Chloridein blood
12
1. Two-thirds have mutations in gp91phox gene Unable to form H2O2.i.e., no cyanide resistant respiratory burst & don’t live beyond childhoodHave X-linked chromosomal deficiency
Have no cyt. b558 functionb-subunit – 91kD – glycosylated – X chromosome DEFECTa-subunit – 22kD – normal chromosome 16
CGD patients have mutation in p47phox gene (reach adulthood)Have autosomal recessive deficiency
2. CGD patients have no cytosol activating protein that phosphorylates and activates NADPH oxidase which causes translocation of the oxidase from the endoplasmic reticulum to the plasma membrane.
LEUKOCYTE ELECTRON TRANSPORTChronic granulomatous disease (CGD)
• Duox1 & 2 (dual oxidase) makes thyroxine hormone and H2O2 for thyroid peroxidase TPO >lung,GI
14
15
leukocytes
Synovium (synovial fluid)
From Am J Med. (2000). 190:33-44
Rheumatoid Arthritis is an autoimmune inflammatory disease that may affect (skin, blood vessels, heart, lungs, muscles-- but principally attacks joints (proliferative synovitis progressing to cartilage destruction/joint ankylosis.
Pathogenesis (unknown etiology):genetic susceptibility; joint damage mediated by leukocytes or exogenous arthritogen (virus, mycobacteria).
Babior, 2000. American Journal of Medicine. 109:33 44.
NSAID Drug therapy for RA or OAIBUPROPHEN COX-1 inhib. 300mg 3 times pd
Cardiovascular & GI bleeding risk,inhib platelets, kidney/liver tox.
ALEVE (Naproxen) 200mg otc ; lasts 12h
• Inhibits inflammation , COX-I and COX-2 inhibitor
• Rat model: ulcers, intestinal inflammation or gastric permeability induced by indomethacin or DNP + Cox inhib (aspirin).
Aliment Pharmacol. Ther. (2000) 14,639-650
18
19Rheumatoid Arthritis Therapy
Repetitive hypoxia in joints, and endothelial cells
ATP hydrolysis
Hypoxanthine from ATP
ROS
Reperfusion O2 +endothelial cell xanthine oxidase
ALLOPURINOLinhib.
endothelial cell nitric oxide
peroxynitriteDestruction of joint
Uric acidMonosodium urate crystals in joint
20
21
Anti-Inflammation therapy
• ROS Scavenger Therapy SOD, selenomethionine/Vit E, 5-aminosalicylate, penicillamine:Cu • Macrophage inhibitor therapy: Gold thiomalate or auranofin or zinc or copper salicylate• Prostaglandin Synthetase Inhibitors:-(NSAIDS) COX-1 many cells e.g.aspirin,ibuprofen, but GI bleeding,kidney COX-2 inflammatory cells e.g. VIOXX (withdrawn), CELEBREX but
decreases bad prostaglandins, decrease Fe intake References: Semin. Arthritis Rheum. 27: 366-70 (1998). Autoimmunity Reviews 7,1-7(2007) Anti-inflammatory Biologics
22
EOSINOPHILS: (chemical warfare cont.)
Accumulate in parasite infection, asthma, rheumatoid diseases, Hodgkin’s lymphoma and allergic or inflammatory diseases
1)destroy parasitic worms, tumor cells, fungi and bacteria by forming hypobromite
H2O2 + Br- + H+ HOBr (hypobromite) + H2O
2) cytokine production e.g. PAF, LTC4 unlike neutrophils (leukocytes) .
2
Biochem J. 358, 233-239 (2001).
MPO
23
MACROPHAGES - chemical warfare function
1) Endocytosis and exocytosis via specific receptors for IgG and C3 coated in bacteria2) H2O2 production by NADPH oxidase to kill mycobacteria3) Arachidonate oxidation to prostaglandin4) Cytokine production - upon activation by PDGF a) lipopolysaccharide (endotoxin) TNF- b) immune system activation BCG infection IL-1 c) inflammation or interferon (IFN-) PAF TGF and arginine nitric oxide kill tumor cells
5) endocytosis and delivery to lysosomes (via scavenger receptor) of oxidised LDL (low density lipoprotein) - can result in transformation to foam cell (the basis of the formation of atherosclerotic plaque)
3
24SURGERY TRAUMA
e.g. if intestinal surgery causes prolonged interrupted blood flow (reperfusion injury)
EARLY ORGAN FAILURE if endotoxin from Gram –ve cell wall of Gram-ve bacteria in the intestine crosses gut barrier
Drug induced hepatocyte cytotoxicity caused by activated immune cells releasing cytokines and reactive oxygen species
(Kupffer cells , macrophages ,neutrophils) i
1) Toxic doses of drugs or chemicals injure hepatocytes. Injured hepatocytes release factors that attract Kupffer cells to specificregions of the liver. 2) Additional mononuclear phagocytes are also recruited from blood and bone marrow precursors. 3) Once localised in the liver, the macrophages become activated by hepatocyte-derived factors of endothelial cells. 4) Activated macrophages and endothelial cells release cytokines e.g.TNFα & platelet activating factor prime & activate Kupffer cells which release Reactive Oxygen Species and more cytokines. 5) Some chemoattractants and cytokines can attract and activate neutrophils that also contribute to hepatocyte injury.
27Macrophages and Tissue Injury
Toxicant
Target tissues
Activated macrophagese.g. Kupffer cells
Mediators
Cytotoxicity Amplification
Model for the role of macrophages in tissue injury by generating inflammatory mediators.
32Autoimmune disease drug therapy1. Alkylating Agents (anticancer cytostatic drugs) Inhibit cell division of both T cells and B cell (lymphocytes) • Cyclophosphamide, nitrosoureas, platinum compounds Efficient therapy for systemic lupus, autoimmune hemolytic anemias,
Wegener’s
2. Antimetabolites Interfere with synthesis of nucleic acids - a) Folic acid analogues (METHOTREXATE) binds dihydrofolate reductase
and prevents synthesis of tetrahydrofolate. Used in treatment of autoimmune diseases (rheumatoid arthritis) and in transplantations
b)Purine analogues (AZATHIOPRINE, or MYCOPHENOLATE (CellCept) inhib. IMP dehydrogenase and GMP synth. Treatment of autoimmune diseases (Wegeners,psoriasis ) also prevents transplant rejection. Mercaptopurine (leukemia,Crohns).
c)Pyrimidine analogues LEFLUNOMIDE
3. Cytotoxic anticancer e.g. mithramycin, dactinomycin inhibits RNA transcription and DNA replication
4. Biologics: anti-cytokine antibodies • TNFalfa blockers1)Etanercept for RA 2)Infliximab
(remicade) for Crohns disease,colon cancer a chimeric human Fab.
3) Adalimumab (Humira) a humanised monoclonal for colon cancer,macular degen. 4)Stelera NEW for psoriasis, 5 shots p.a.$50K
• Rituximab kills CD20 B cell NH lymphomas,RA • Abatacept,fusion protein inhib.T cell costim.RA