Pathology Week 2 p1-18

7/30/2019 Pathology Week 2 p1-18

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Inflammation: Acute, Chronic and Systemic Mon. 08/23/10

Design a System Recognize injury promptly & properly Eliminate invaders & debris Communicate & continuously adjust to changing conditions Continue the response as long as needed Prepare for rebuilding

Sources of Injury Traumatic Infectious Chemical Immune reactions (hypersensitivity)

Immune system response begins with platelets andneutrophils or mast cells

Neoplastic

Inflammation Every person, every disease Destroy, dilute or wall off the injurious agent A closely regulated protective reaction Relies on vascularized tissue

Learning Objectives1. Acute and chronic inflammation features2. 3 components of the inflammatory system3. Steps of leukocyte emigration, chemotaxis and phagocytosis4. Nine mediator classes5. How inhibitors regulate & cytokines transition to chronic phase6. Four causes of chronic inflammation7. Cardinal signs of acute inflammation

1. Acute and chronic inflammation features:

Acute vs Chronic Inflammation:Acute Chronic

Immediate Gradual Transient (does not last long) Prolonged (persistence of injury-causing agent) Edema Fibrosis & vessels (change in architecture)

Blood vessels derive from preexisting blood vessels (angiogenesis) Essential for normal wound healing

Neutrophils Mononuclear cells (monocytes, macrophages, lymphocytes, plasma cells) Fibrin Collagen Necrosis (cell death cleaned up fast) Resolution of necrosis (takes a long time to clean up debris)

FIGURE 27A Nature ofleukocyte infiltrates in

inflammatory reactions. Thephotomicrographs arerepresentative of the early(neutrophilic) (A) and later(mononuclear) cellularinfiltrates (B) seen in aninflammatory reaction in themyocardium following

ischemic necrosis(infarction). The kinetics ofedema and cellularinfiltration (C) areapproximations.

Test q: Which of the following is a marker of chronic inflammation?Capillary formation.


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Test q:A 20y/o college student comes to your office w/vague complaints of fatigue and right upper quadrant fullness. His liver enzymes are elevatedand he has a family history of primary biliary cirrhosis, so you request a liver biopsy. When you review the slides w/the pathologist, he points out

prominent periportal lymphocytic infiltration w/germinal centers and scattered fibroblasts in the interlobular zone. The most likely pathologic diagnosisis: chronic inflammation.

Figure: Histology of Acute Inflammation

FIGURE 217A The characteristic histopathology of acuteinflammation. A, Normal lung shows thin (virtually invisible)blood vessels in the alveolar walls and no cells in thealveoli. B, The vascular component of acute inflammation is

manifested by congested blood vessels (packed witherythrocytes), resulting from stasis. C, The cellular

component of the response is manifested by large numbersof leukocytes (neutrophils) in the alveoli.

Acute inflammation- dilation of blood vessels, neutrophilscome in.

2. 3 Components of the Inflammatory System:1. Vessels

Arterioles Venules Lymphatics

2. Leukocytes3. Soluble mediators: many produced by cell and effective in neighborhood around cell. Some in serum but only

activated in location of acute inflammatory response. Paracrine Serum enzyme Cytokines

Proteins produced by many cell types (activated lymphocytes and macrophages; endothelial, epithelial,connective tissue)

TNF + IL-1: produced by macrophages (activated) Endothelial activation: endothelial adhesion; chemical mediators

Vascular and Cellular Responses Increased blood flow to tissue (vasodilation)

Increased vascular permeability (leakage) only certain vessels.Arterioles dilate and let in more blood, venules become moreleaky. Migration of leukocytes out of the blood vessels (chemotaxis)

FIGURE 22 Formation of transudates and exudates. A, Normalhydrostatic pressure (blue arrows) is about 32 mm Hg at thearterial end of a capillary bed and 12 mm Hg at the venous end;the mean colloid osmotic pressure of tissues is approximately 25mm Hg (green arrows), which is equal to the mean capillarypressure. Therefore, the net flow of fluid across the vascular bedis almost nil. B, A transudate is formed when fluid leaks outbecause of increased hydrostatic pressure or decreased osmoticpressure. C, An exudate is formed in inflammation, becausevascular permeability increases as a result of increased interendothelial spaces.

Normal: slight leakage out of vessel Congestive heart failure, fluid overload: increased hydrostatic pressure fluid leaks out more. Transudate: fluid with low protein content, little or no cellular material, low specific gravity. Ultrafiltrate of blood

plasma that results from osmotic or hydrostatic imbalance across vessel wall without an increase in vascularpermeability.

Exudate: escape of fluid, proteins, blood cells from vascular system into interstitial tissue or body cavities. Increase innormal permeability of small blood vessels due to injury inflammation. Blood flow slows down in acuteinflammatory vessels. Have extravascular fluid with high protein concentration, cellular debris, high specific gravity.

Test q: In acute inflammation, the most significant increase in vascular permeability occurs in: Post-capillary venules.


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Figure: Capillaries dilate with increased pressure due to dilation of arterioles. Venules get leaky.

Vascular Changes: Transient Vasoconstriction

Hemostasis: slow moving red cells (b/c vasodilation followstransient vasoconstriction)

Vasodilation (biggest effect) Mediated by prostaglandins and Nitric oxide Arteriole smooth muscle relaxes Relax vessels allow more blood flow

Increased Permeability (leakage) Transient, sustained or delayed

Normal: Capillary has only 1 endothelial Injury: Stimulate endothelial cells tocell around vessel. Venules has ~3. contract and release tight junctions

bt cells increased interendothelialspaces.

3. Emigration, chemotaxis and phagocytosis:Leukocyte Extravasation Margination

Leukocytes approach endothelium

RBCs aggregate in venules Neutrophils pushed from central to periphery

Rolling Mediated by selectin Weak bonding bt cell and endothelium Activation of selectin adhesion molecules on

surface of neutrophils and endothelial cells Neutrophils loosely bind selectins and roll

along endothelium Adhesion (pavementing)

Tight integrin (2) binding

Communication in cytoplasm, rearrangement of cytosol Adhesion molecules firmly bind neutrophils to endothelial cells

Catecholamine, corticosteroids, and lithium inhibit activation ofadhesion molecules

Transmigration (Diapedesis) Integrin Find a hole neutrophils dissolve basement membrane and enter

interstitial tissue Functions of exudate: (1) dilutes bacterial toxins (2) provides

opsonins Chemotaxis

Neutrophils follow chemical gradients that lead to the infection site Chemotactic mediators bind to neutrophil receptors; binding

causes release of calcium which increases neutrophil motility

Above:Arrow = arteriole. Rabbitinjected with carbon blackpigment. Histamine put in area.Venules more leaky due todilated vessels. Contraction ofendothelial cells and increasedinterendothelial spaces is elicitedby histamine.

Test q: During acute inflammation, neutrophilsmigrate through the walls of the venules. This

migration requires integrins and selectins.

Test q:A 6y/o child has a history of recurrentinfections w/pyogenic bacteria, including Staphaureus and Strep pneumoniae. The infections areaccompanied by a neutrophilic leukocytosis.

Microscopic exam of a biopsy specimen obtainedfrom an area of soft tissue necrosis showsmicrobial organisms but very few neutrophils. An

analysis of neutrophil function shows a defect inrolling. This childs increased susceptibility toinfection is most likely caused by a defect in which

of the following molecules? Selectins.

Test q: In the acute inflammatory reaction, the

principal function of selectins and integrins is toenhance leukocyte binding to the endothelium.


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FIGURE 24 The multistep processof leukocyte migration through bloodvessels, shown here for neutrophils.The leukocytes first roll, then becomeactivated and adhere to endothelium,then transmigrate across theendothelium, pierce the basementmembrane, and migrate towardchemoattractants emanating from thesource of injury. Different moleculesplay predominant roles in different

steps of this processselectins inrolling; chemokines (usually

displayed bound to proteoglycans) inactivating the neutrophils to increaseavidity of integrins; integrins in firmadhesion; and CD31 (PECAM-1) intransmigration. Neutrophils expresslow levels of L-selectin; they bind toendothelial cells predominantly via P-and E-selectins. ICAM-1, intercellular

adhesion molecule 1; TNF, tumornecrosis factor.

TNF and IL-1--released by macrophages--act on

endothelial of post-capillary venules and induceexpression of adhesion molecules.

Adhesion Molecule Expression:

FIGURE 25: Regulation of expression of endothelial andleukocyte adhesion molecules. A, Redistribution of P-selectin from intracellular stores to the cell surface. B,Increased surface expression of selectins and ligands forintegrins upon cytokine activation of endothelium. C,Increased binding avidity of integrins induced bychemokines. Clustering of integrins contributes to theirincreased binding avidity (not shown). IL-1, interleukin-1;TNF, tumor necrosis factor.

Weibel-Palade bodies: endothelial granules that store P-selectin; redistribution of P-selectin in W-P bodies tosurface.

Chemokines produced at injury site enter blood vessel and bind to endothelial cell proteoglycans; inducedexpression of integrin ligands on endothelium and activation of integrins to high affinity state on leukocytes

A

Figure: Migration to extracellular space. Highresponse of inflammatory substance at core ofinflammation. Chemotaxis attacts leukocyte byhaving extracellular matrix attachment sites.


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Chemotaxis: a family of 40 peptides that attract inflammatory cells. Increasing chemical gradient Exogenous agents

Bacterial N-formyl-methionine peptides Endogenous products

Complement (C3a & C5a) Lipoxygenase products (LTB4) Cytokines (TNF, IL-1)

- IL-1 is produced by macrophages. Macrophagesrelease it once theyre at inflammatory site.

Chemokines (IL-8, ,,)

Phagocytosis: Neutrophil has to recognize that material is foreign. Recognition and attachment

- Opsonins: IgG-Fc, C3b, iC3b, collectins- attach to bacteria (or foreign bodies)- Neutrophils have receptors for IgG

and C3b- Enhances neutrophil recognition and

attachment to foreign bodies

- Leukocyte receptors: FcR, CR1/2

Engulfment: phagocytose; phagocytic vacuoles

Killing and degradation:- Oxidative burst- Enzyme digestion

Phagocytosis & Oxidative Burst:

FIGURE 29 Phagocytosis and intracellulardestruction of microbes. Phagocytosis of a particle(e.g., bacterium) involves binding to receptors on theleukocyte membrane, engulfment, and fusion of

lysosomes with phagocytic vacuoles. This is followedby destruction of ingested particles within the

phagolysosomes by lysosomal enzymes and byreactive oxygen and nitrogen species. The microbicidalproducts generated from superoxide are hypochlorite(HOCl) and hydroxyl radical (OH), and from nitricoxide (NO) it is peroxynitrite (OONO). Duringphagocytosis, granule contents may be released into

extracellular tissues (not shown). MPO,myeloperoxidase; iNOS, inducible NO synthase.

Reactive Oxygen Species: Respiratory burst: oxidizes NADPH and inprocess, reduces oxygen superoxide anion, which is converted to H2O2 Occurs in lysosome H2O2 not able to efficiently kill microbes; enzyme myeloperoxidase in

neutrophil granules converts H2O2 to hypochlorite.

Neutrophil Granules Specific (secondary)

Smaller, fuse with plasmalemma Lysozyme: hydrolyzes muramic acid-N-acetylglucosamine bond, found

in glycopeptide coat of all bacteria Collagenase IV

Azurophil (primary) Fusion with phagosome Myeloperoxidase, NADPH oxidase Acid & neutral protease

Figure:macrophage SEM. Scanningelectronmicrograph of amoving leukocytein culture showinga filopodium(upper left) and atrailing tail.

Figure:Pseudopodtoward attractant. Projectcytoplasm indirection that hasmost chemotaxis

Test q: The oxidative burst ofleukocytes produces a substance

which is the most potent bactericidalproduct of the cell. This substanceis called: Hypochlorous acid

(HOCl). (Other choices: Bacterialpermeability increasing protein(BPI); Major basic protein (MBP);

Lactoferrin; Lysozyme)

Test q: A 10y/o boy suffers recurring infections due to Strep pneumoniae. He isfound to have an inherited disorder of a complement factor such that phagocytosis

is deficient. This factor is most likely: C3b.

Test q: Phagocytosis of bacteria by neutrophils or other bactericidal cells is greatly

facilitated by coating the foreign organisms w/substances recognized by thephagocytes. These attachment-promoting substances, called opsonin, arepresent in the ECF of inflamed tissue. One example of an opsonin is: Fc

fragments of IgG. REPEATED TWICE (but on 2005 answer key, says answer isC5a even though Fc fragments of IgG is a choicetypo?)


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4. Nine mediator classes:

Soluble Factor Overview Paracrine cell products

Nitric Oxide (NO) Vasoactive amines (Histamine) Arachidonic acid metabolites (COX,LOX) Platelet Activating Factor (PAF) Neuropeptides (SP)

Plasma protease systems Bradykinin, Kallekrein Complement cascade Clotting products and enzymes

Nitric Oxide Vasodilates Produced by endothelium and macrophages From L-arginine, O2, NADPH, cofactors

NO synthesized from L-arginine via nitric oxide synthase (NOS) Nitric Oxide Synthase Endothelial, neuronal, inducible on macrophages

Inhibits rolling, adhesion of leukocytes (thought to control inflammatory response) Three types of NOS: eNOS (endothelial), nNOS (neuronal), iNOS (inducible) Antimicrobial free radicals released (NO is microbicidal)

Vasoactive Amines Histamine

Stored in granules of mast cells and basophils Granules released into surrounding inflammatory tissue by allergen binding multiple IgE molecules on mast cell

Test q: In acute inflammation, arterioles dilate and venules become more permeable (leaky). These changes occur when mast cells release HistamineTest q:A woman who is allergic to cats visits a neighbor who has several cats. During the visit, she inhales cat dander and within minutes, shedevelops nasal congestion w/abundant nasal secretions. Which of the following substances is most likely to produce these findings? Histamine.

Test q:A man w/a mold allergy returns to his recently flooded home in New Orleans. During the visit, he develops nasal congestion w/abundant nasalsecretions. Which of the following substances is most likely to produce these findings? Histamine.Test q: Of those listed, the earliest chemical mediator of inflammation is: histamine. (Other choices: Hageman factor, Bradykinin, serotonin, Kallikrein)

Serotonin (5-HT) Stored in granules of platelets and enterochromaffin cells Released when platelets aggregate

Vasodilate and increase permeability

FIGURE 211 Generation of arachidonic acid metabolitesand their roles in inflammation. The moleculartargets of action of some anti-inflammatory

drugs are indicated by a red X. Not shown areagents that inhibit leukotriene production byinhibition of 5-lipoxygenase (e.g., Zileuton) orblock leukotriene receptors (e.g.,Montelukast). COX, cyclooxygenase; HETE,hydroxyeicosatetraenoic acid; HPETE,hydroperoxyeicosatetraenoic acid.

Arachidonic acid

- when inflammatory stimulation, maybe further metabolised byCycloxygenase pathway orLipoxygenase pathway (producelipoxins- inhibitors of inflammatoryresponse and also chemotaxinsimportant in asthma response)

Cyclooxygenase pathway- balance between prostacyclin and thromboxaneTest q: We now believe that many of the anti-inflammatory effects of glucocorticoid hormone-related drugs are caused by boosting of cytoplasmic

calcium-dependent phospholipid-binding proteins called lipocortin. Since lipcortin-1 inhibits phospholipase A2, glucocorticoid indirectly decreases thelevel of free arachidonic acid by cells receiving inflammatory stimuli. One consequence of decreased free arachidonic acid is decreased vasodilation byproducts of: the cyclooxygenase pathway.

Test q:A clever pharmaceutical rep is telling you about how his companysamazing drug counteracts all of the soluble mediators of acute inflammation. He

describes how this drug counteracts the effects of plasma protease products,arachidonic acid metabolites, histamine, platelet activating factor, and evenneuropeptides. You, however, know something about acute inflammatory

mediators. Noticing that he has left something out, you ask him what his drugdoes for: Nitric oxide.


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Simplified AA Metabolism:

Platelet Activating Factor (PAF) paracrine substance produced at inflammation site Vasodilates and increases permeability

100 to10,000 times more potent than histamine also adhesion, chemotaxis, oxidative burst

Fatty acid on middle C of PC replaced by product of phospholipase A2

From endothelial cells, platelets Synthesized at site of inflammation

PAF-specific acetylhydrolase inactivates Test q: The major sources of PAF are: Platelets and endothelium.

Neuropeptides Substance P (most widely known neuropeptide) is the prototype

Tachykinin family of peptides CNS & PNS Multiple effects

Vasodilate Increase permeability Pain mediation (most important function)

Capsaicin in hot peppers

Prostacyclin unclot

Thromboxane clot

Prostaglandins vasodil

Lipoxins oppose inflam

Leukotrienes incr perm

ArachidonicAcid

MembranePhospholipids

CyclooxygenasePathway

LipoxygenasePathway

Phospholipase A2

Phopholipase A2: primary enzyme that releasesarachidonic acid from membrane phospholipids.

AA-derived mediators--aka eicosanoids--synthesizedby two major classes of enzymes:1. Cyclooxygenase: generate prostaglandins2. Lipoxygenase: Leukotriense and lipoxins

Hageman Factor XII: protein synthesized by liverthat circulates in inactive form. Inflammation andblood clotting are intertwined, with each promotingthe other. Anytime clotting promoted, you also getfibrinolysis. Deposition and degradation balance.

- Plasmin: activates fibrinolysis and complement.- Kallikrein: enzyme that cleaves precursor to

bradykinin- Bradykinin:

Increase permeability Contraction of smooth muscle Vasodilation

Pain

Fibrin clot formation also occurs with fibrinolysis(cleaves fibrin, solubilize clot)

Plasmin also cleaves complement protein C3 toproduce C3 fragment C3a + C5a: increase vascular permeability C5a: chemotaxis


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FIGURE 214The activation and functions of the complementsystem. Activation of complement by differentpathways leads to cleavage of C3. The functionsof the complement system are mediated bybreakdown products of C3 and other complementproteins, and by the membrane attack complex(MAC).

Mediator Functions:

5. How inhibitors regulate & cytokines transition to chronic phaseBecause of the destructive effects of lysosomal enzymes, the initial leukocytic infiltration if unchecked can potentiatefurther inflammation and tissue damage. Harmful proteases are kept in check by antiproteases in serum and tissue fluids.

Antiprotease Found in serum

1 - antitrypsin Inhibits neutrophilelastase

Alveoli rupture/coalescepulmonary emphysema

No alpha-1-antitrypsin =neutrophil elastase is notinhibited (sustained actionof leukocyte proteases)

2 macroglobulin

- In both serum and secretions

Nitric oxide Vasodilates, inflammation control, defense

Histamine Vasodilation, permeability

Serotonin Vasodilation, permeability

Cyclooxygenase Prostaglandins: vasodilationThromboxane: clotProstacylin: unclot

Lipoxygenase Leukotrienes: permeability

Lipoxygenase: X inflammation

PAF Vasodilation, permeability

NeuropeptideSubstance P

Vasodilation, permeability, pain

Bradykinin Vasodilation, permeability, smooth muscle

contraction, pain

Complement C3a: permeability

C5a: permeability, vasodilate

Clotting Vasodilate, cleave fibrin,solubilize clot

Antioxidant Scavenge

O2

, H2O2, HO

NO2

, OONO

-, RSNO

Extracellular Ceruloplasmin Transferrin

Intracellular Superoxide dismutase Catalase Glutathione peroxidase

Test q: If acute inflammatory responses were to proceedw/o inhibition, they would cause considerable tissue

destruction and permanent loss of function of inflamed

organs. Once important regulator of acute inflammationis the substance: alpha-1-antitrypsin.

Test q: Examples of two plasma proteins that limit,control, and regulate the potentially destructive products

of the acute inflammatory response: -1-antitrypsinand ceruloplasmin.

Test q: Which of the following cellular enzymes are

produced by polymorphonuclear cells in acuteinflammatory responses to protect against toxicbyproducts? Superoxidase.

Test q: Which of the following is assocd w/preventionof damage to human tissue by free radicals?

Glutathione peroxidase.

Test q: Nitric oxide is an important mediatiorof: vasodilation. REPEATED TWICE.

Test q:A 20y/o male presents w/acute abdominal pain.Phys exam reveals rebound tenderness indicating

peritonitis. The discomfort experienced by the youngpatient is mediated primarily by: Bradykinin.


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Cytokines: transition from acute to chronic/reparative response Interleukins

Monokines IL-1 Lymphokines IL-2

Macrophage activators

IFN (most important activator of macrophages), TNF , TNF , IL-5, IL-10, IL-12

Hematopoietic growth factors c-kit ligand, GMCSF, MCSF, G-CSF, stem cell factor

Chemokines chemotactic attract other inflammatory cells

Cytokines: Acute Inflammation:

Cytokine Principal Sources Principal Actions in Inflammation

TNF Macrophages, mast cells, Tlymphocytes

Stimulates expression of endothelial adhesion molecules andsecretion of other cytokines; systemic effects

IL-1 Macrophages, endothelial cells,some epithelial cells

Similar to TNF; greater role in fever

IL-6 Macrophages, other cells Systemic effects (acute-phase response)

Chemokines Macrophages, endothelial cells,T lymphocytes, mast cells, othercell types

Recruitment of leukocytes to sites of inflammation; migrationof cells to normal tissues

Cytokines: Chronic Inflammation:

Cytokine Principal Sources Principal Actions in Inflammation

IL-12 Dendritic cells, macrophages Increased production of IFN-

IFN- T lymphocytes, NK cells Activation of macrophages (increased ability to kill microbes andtumor cells)

IL-17 T lymphocytes Recruitment of neutrophils and monocytes

FIGURE 225 Macrophage-lymphocyte interactions in chronic inflammation.

Activated T cells produce cytokines that recruit macrophages (TNF, IL-17,chemokines) and others that activate macrophages (IFN). Different subsetsof T cells (called TH1 and TH17) may produce different sets of cytokines;these are described in Chapter 6. Activated macrophages in turn stimulate Tcells by presenting antigens and via cytokines (such as IL-12).

IFN- activates more macrophages.

Outcome of Acute Inflammation: Resolution (regeneration)

No functional or histologic change

Progression Chronic inflammation Granuloma

Abscess formation Abcess or granuloma chronic inflammation response

Healing (reconstitution) Collagen binder or filler Fibrosis (replacement by scar)


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Acute versus Chronic Lung Inflammation

Chronic inflammatory response- change in architecture

6. Four Causes of Chronic Inflammation: Serous Inflammation (skin blister): Persistent infection Persistent injurious agent Interference with healing Autoimmunity

May begin with minimal acute phase Rheumatoid arthritis Atherosclerosis Tuberculosis

Serous & Fibrinous Inflammation (Figures) Fibrinous Inflammation (fibrinous pericarditis):FIGURE 218 Serous inflammation (top). Low-power view of across-section of a skin blister showing the epidermis separatedfrom the dermis by a focal collection of serous effusion.FIGURE 219A Fibrinous pericarditis (bottom). A, Deposits offibrin on the pericardium. B, A pink meshwork of fibrin exudate (F)overlies the pericardial surface

(P).

Bread and butter pericarditis

Test q:A 53y/o male develops pericarditis after a bacterial

pneumonia and dies. At autopsy, the pericardium is coatedw/acellular pink (smudgy) material. Fibroblasts and capillaries arenot present. The best description is: fibrinous pericarditis.

FIGURE 220A (left) Purulent inflammation. A, Multiplebacterial abscesses in the lung, in a case of

bronchopneumonia. B, The abscess contains neutrophils andcellular debris, and is surrounded by congested bloodvessels.

FIGURE 221A (right) The morphology of an ulcer. A, Achronic duodenal ulcer. B, Low-power cross-section of a

duodenal ulcer crater with an acute inflammatory exudate inthe base.

FIGURE 222A A, Chronicinflammation in the lung,showing all three characteristichistologic features: (1) collectionof chronic inflammatory cells (*),(2) destruction of parenchyma(normal alveoli are replaced byspaces lined by cuboidalepithelium, arrowheads), and(3) replacement by connective

tissue (fibrosis, arrows). B, Bycontrast, in acute inflammationof the lung (acute

bronchopneumonia), neutrophilsfill the alveolar spaces andblood vessels are congested.

A

Test q:A 75y/o female develops a cough and fever of 103F.Chest x-ray shows a virtual white-out of the left upper lobe. If

the area of involvement were biopsied, you would expect to see:Gram-positive diplococci and neutrophils. (indicating Streppneumo)


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Test q:A chest radiograph of anasymptomatic, 37y/o man showed

a 3cm nodule in the middle lobe ofthe right lung. The nodule wasexcised w/a pulmonary wedge

resection, and sectioning showedthe nodule to be sharplycircumscribed with a soft, white

center. Culture of tissue from thenodule grew Mycobacteriumtuberculosis. Which of the

following pathologic processes

has most likely occurred in thisnodule? Necrotizing

granulomatous inflammation.REPEATED TWICE (once w/o thenecrotizing in the answer)

FIGURE 223 Maturation of mononuclear phagocytes:

Granuloma:

Disease Cause Tissue Reaction

Tuberculosis M. tuberculosis Caseatinggranuloma (tubercle)

Leprosy M. leprae Noncaseating granulomasAcid-fastbacilli in macrophages

Syphilis Treponema pallidum Gumma: plasma cell infiltrate; centralcells necrotic without loss of cellularoutline

Cat-scratch disease Gram-negative bacillus Stellate granuloma with neutrophils;giant cells uncommon

Sarcoidosis Unknown etiology Noncaseating granulomas withabundant activated macrophages

Crohn disease Intestinal bacteria,self-antigens

Noncaseating granulomas intestinewall, transmural inflammatory infiltrate

Test q:A 20y/o African American male hasbilateral hilar adenopathy, and radiography

reveals densities in both lung fields. Abronchoscopic biopsy revealsgranulomatous inflammation w/multiple giant

cells of the Langhans type and no evidenceof necrosis. Routine mycobacterial andfungal cultures are negative. Which of the

following is the most likely diagnosis?Sarcoidosis,

FIGURE 213 Principal local andsystemic actions of tumor necrosisfactor (TNF) and interleukin-1 (IL-1).

Prolonged inflammation- cytokines canhave systemic effects.

Systemic illness: fever (mostly from IL-1/TNF)

Test q: A 70y/o woman has worseningshortness of breath. Her temp is 38.3*C.

On percussion, there is fullness over the leftlung fields. Thoracentesis yields 800mL ofcloudy yellow fluid from the left pleural

cavity. Analysis of the fluid reveals a WBCcount of 2500/mm3 w/98% neutrophils and2% lymphocytes. A gram stain of the fluid

shows gram-positive cocci in clusters.Which of the following terms best describesthe process occurring in the left pleural

cavity? Purulent exudates. (Other choiceswere Abscess, Chronic inflammation,Transudate, and Fibrinous inflammation)


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7. Cardinal Signs of Acute Inflammation: Heat- blood flow Redness- vasodilation Swelling- increased blood flow Pain- due to swelling Loss of function- directly related to core four (above)

Learning Objectives (w/answers):1. Acute and chronic inflammation features

AI=PMNs & exudate CI=mononucs & spindle cells2. 3 components of the inflammatory system

Vessels, leukocytes, soluble mediators3. Steps of leukocyte emigration, chemotaxis and phagocytosis

Margination, rolling, adhesion, transmigration, chemotaxis, phagocytosis, oxidative burst4. Nine mediator classes

NO, amines, COX, LOX, PAF, NP, Clot, comp, kinin5. How inhibitors regulate and cytokines transition to chronic phase

Antiprotease, antioxidant; Cyt mitogenic & activate macrophages, chemotactic to endothelial & fibrocytes6. Four causes of chronic inflammation

Persistent infection, insult, healing delay, autoimmune7. Cardinal signs of acute inflammation

BF=rubor,calor (redness, heat), perm=tumor (swelling), cells=dolor (pain), functio laesa (loss of function)

Why are the above answers written in Latin?

Repair: Regeneration, Replacement, or Fibrosis Tues. 08/24/10

Learning Objectives:1. Regeneration versus replacement2. 3 Surface receptor types3. Cell cycle, 4 cyclins, 2 checkpoints4. 2 unique basement membrane molecules5. Collagen synthesis & structure6. 5 Growth factors7. Wound healing & maturation, zinc function

1. Regeneration versus replacement Depends on

Matrix preservation Parenchymal cells able to regenerate

Cells (stromal & epithelial) must Migrate chemotaxis Proliferate mitogenesis Differentiate angiogenesis,

collagen synthesis Intact matrix (BM+ECM) required for all 3

In the interstitial fibrosis (middle) picture,

there are neutrophils in the alveoli alveolarlining cells have been able to multiply andrestore the normal architecture.

In the myocardial fibrosis pic (far right), instead of expanding, the fibrosis contractsdown. Myocardial scarring never as big asthe original defect.


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Replacement Matrix disrupted or permanent cells destroyed Granulation tissue early in process

Angiogenesis (and edema) Fibroblasts Evolving inflammation

Connective tissue scar end result Replaces granulation tissue by maturation

Granulation tissue general term for tissue w/new vessels growing in it (no pericytes) never stays the same. Maturesover time and changes its appearance. Looks different in every instance.

Wound Healing

Can see overlap between inflammation and granulation tissue.Usually, in MI, granulation tissue appears at day 3 (becomes histologicallyrecognizable).

Figure: Cell Cycle.

There are two points at which the cell decides whether to proceed:1. Before it makes the enzymes in G1 phase.2. Just before the cell enters mitosis

2. 3 Surface receptor types

Cell Surface Receptors:

Intrinsic kinase activity (IK) Transmembrane with binding and catalytic domains Either Tyrosine kinase or Serine/threonine kinase Mitogenic receptors

Cytosol kinase-linked activity (CK) Transmembrane with extracellular and cytosolic enzyme binding Activates cytosoic tyrosine kinase Cytokine receptor superfamily

G protein-linked (GPCR) Seven-spanning receptors (serpentine) Intracellular second messenger (cAMP or cGMP) Chemokines, epinephrine, glucagon, drug receptors


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FIGURE 39 Overview of the main types of cell surfacereceptors and their principal signal transduction pathways.Shown are receptors with intrinsic tyrosine kinase activity,seven transmembrane G proteincoupled receptors, andreceptors without intrinsic tyrosine kinase activity. cAMP,cyclic adenosine monophosphate: IP3, inositol triphosphate;JAK, Janus kinase; MAP kinase, mitogen-activated proteinkinase; PI3 kinase, phosphatidylinositol 3-kinase; PKB,protein kinase B, also known as Akt; PLC-, phospholipaseC gamma; STATs, signal transducers and activators oftranscription.

Test q: Intrinsic kinase receptors may communicate w/the nucleusby the PI3 kinase pathway, the MAP kinase pathway, or the IP3pathway. A common ligand for this type of receptor is: Growthfactor.

Tissue Type Determines Regeneration Capacity Labile

epithelia, bone marrow respond promptly Stable

glands, mesenchyme G0 recruited to G1 Permanent

neurons, striate muscle dont proliferate

3. Cell cycle, 4 cyclins, 2 checkpoints

Regulation of Cell Division Checkpoints completion of molecular events

G1 checkpoint Rb gene regulates

G2M checkpoint p53 gene regulates

Protein phosphorylation is Upregulated by cyclins Cyclin D in early G1 Cyclin E in late G1, early S Cyclin A in S, early G2 Cyclin B in late G2, early M

Stem Cells Self renewal Asymmetric differentiation

Stem cell Progenitor cell

Adult Stem Cells Bone Marrow

Hematopoietic stem cells (HSC) Mesodermal progenitor cells Multipotent adult progenitor cells (MAPC)

Developmental plasticity in culture

MAPC similar to ES Tissue stem cell Niche locations

Hair follicles, GI crypts, muscle satellite cell, canals ofHerring, corneal limbus

Figure: Adult Stem Cell Niches B. Small intestine stem cells located near the base of a crypt, abovePaneth cells (stem cells in the small intestine may also be located at

the bottom of the crypt). C. Liver stem (progenitor) cells, known asoval cells, are located in the canals of Hering (thick arrow), structuresthat connect bile ductules (thin arrow) with parenchymal hepatocytes(bile duct and Hering canals are stained for cytokeratin 7). D. Cornealstem cells are located in the limbus region, between the conjunctivaand the cornea.

Test q: The tumor suppressorgenes Rb and p53 are found in whatcellular location? In the nucleus.

Test q: The nuclear proteins Rb and

p53 are gene products for: Tumorsuppressor genes. REPEATEDTWICE.


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Embryonic Stem Cells Up to Blastocyst stage (32 cells) Developmental plasticity in culture

Chimeras in all organs when reimplanted in another mouse blastocyst Human embryonic stem cells (HES) proliferative over 70 passages in vitro HES do not form teratomas in nude mice

No therapeutic uses yet

Stem Cell Therapy:FIGURE 36: Steps involved in stem cell therapy, using

embryonic stem (ES) cells or induced pluripotent stem (iPS)cells. Left side, Therapeutic cloning using ES cells. The diploid

nucleus of an adult cell from a patient is introduced into an enucleatedoocyte. The oocyte is activated, and the zygote divides tobecome a blastocyst that contains the donor DNA. Theblastocyst is dissociated to obtain ES cells. Right side, Stem celltherapy using iPS cells. The cells of a patient are placed inculture and transduced with genes encoding transcription factors, togenerate iPS cells. Both ES and iPS cells are capable of differentiatinginto various cell types. The goal of stem cell therapy is to

repopulate damaged organs of a patient or to correct a geneticdefect, using the cells of the same patient to avoidimmunological rejection.

4. 2 unique basement membrane molecules

Extracellular Matrix (ECM) Scaffold and support for cell adherence, migration, proliferation Binds growth factors and factors for cell migration and differentiation Binds water and ions for turgor, mineralization and mechanical properties

3 major components Structural collagen, elastin (lung) Adhesive glycoproteins fibronectin, laminin Stabilizing gel proteoglycans, hyaluronan

Figure: ECM components FIGURE 312 Main components ofthe extracellular matrix (ECM),including collagens, proteoglycans,and adhesive glycoproteins. Bothepithelial and mesenchymal cells

(e.g., fibroblasts) interact with ECMvia integrins. Basement membranesand interstitial ECM have differentarchitecture and generalcomposition, although there is someoverlap in their constituents. For thesake of simplification, many ECM

components (e.g., elastin, fibrillin,hyaluronan, and syndecan) are notincluded.

Collagen Type IV = BM


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Basement Membrane (BM) Spreading of epithelial or endothelial cells Collagen type IV Laminin

Links cells to BM matrix by collagenIV & heparan

Fibronectin Adheres to cells by RGD integrin-

binding motif Also attaches to heparan, collagen &

fibrin Heparan sulfate

Ligand for both laminin andfibronectin

Center portion of laminin attaches to base ofcell, other parts fold back into BM. Importantfor attaching epithelial cells. There are alsorelease signals for when cells begin to divide.See various binding domains for ECM(heparan, fibrin, collagen, etc.)

5. Collagen synthesis & structure

Collagen Structure Tropocollagen is basic unit (monomer) 3 alpha chains in each unit

Triple helix, left handed (DNA is right-handed helix)

27 collagen types determined by 41 genes on 14 chromosomes

Fibrillar collagens: I, II, III, V, IX Have 67 nm banding from linking

zones Present in tendon, scar, strong

connective tissue As a scar matures, type III type I

Nonfibrillary collagens: IV, others Amorphous (no banding pattern) Present in interstitium, submucosa,

BM

Lysine hydroxyl groups form very strong cross-links.

Test q:A 25y/o med student wrecks her bike in a construction zone, resulting in several abrasions to her arms and knees. In a few days, a scab forms

which contains: Type III collagen.Test q:A 23y/o woman receiving corticosteroid therapy for an autoimmune disease has an abscess on her upper outer right arm. She undergoes minosurgery to incise and drain the abscess, but the wound heals poorly over the next month. Which of the following aspects of wound healing is most likely

to be deficient in this patient? Collagen synthesis.

6. 5 Growth factors

Stages of Repair Angiogenesis Fibroblast invasion and proliferation Collagen and ECM synthesis Granulation tissue into scar Tissue Remodeling


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Five key Growth Factors:

Symbol Source Functions

EGF Platelets, macrophages, saliva, urine, milk,plasma

Mitogenic: keratinocytes (aka squamousepithelial cells) and fibroblasts; keratinocytemigration

TGF- Platelets, T-cells, endoth., macrophages, smms, FB

Chemotactic inflam., FB, sm ms; scar,angiogenic, MMP, epith. prolif.

VEGF Many types of cells vascular permeability; mitogenic:endothelial cells; angiogenic

PDGF Platelets, macrophages, endothelial cells,keratinocytes, smooth muscle cells

Chemotactic: phagocytes, fibroblasts, sm.ms;Activates: phagocytes, fibroblasts; Mitogenic:fibroblasts, endothelial, sm.muscle cells;MMPs, fibronectin, MPS, angiogenesis andwound contraction

FGF Macrophages, mast cells, T lymphocytes,endothelial cells, fibroblasts

Chemotactic: fibroblasts; Mitogenic:fibroblasts, epith. cells; keratinocytemigration, angiogenesis, wound contraction,and matrix deposition

Principal Mediators of Repair

Function Growth Factors and Cytokines

Monocyte chemotaxis Chemokines, PDGF, FGF, TGF-, TNF

Fibroblastmigration/replication

PDGF, EGF, FGF, TGF-,TNF, IL-1

Keratinocyte replication HB-EGF, KGF, HGF,EGF

Angiogenesis VEGF, FGF, angiopoietins

Collagen synthesis TGF-, PDGF

Collagenase secretion PDGF, FGF, TNF;TGF-inhibits

TGF- can be an off signal inhibits secretion and remodeling of collagen in mature scars.

Figure: different signals for each stage/zone.

Angiogenic Factors: VEGF (vascular endothelial growth factor)

Receptors have intrinsic tyrosine kinase activity VEGF-R2 for proliferation VEGF-R1 for tube formation

bFGF also angiogenic Stimulates other non-endothelial mesenchymal cells, too

(ex: pericytes) Angiopoietins turn off vascular proliferation

Ang1 binds endothelial Tie2 receptor to recruit pericytes Endostatin (breakdown product)

Collagen fragment that inhibits angiogenesis

Test q: Many researchers have produced anti-angiogenic cancer drugs. Acompound normally found in the body that inhibits angiogenesis is: Endostatin.

Test q: Basic FibroblastGrowth Factor is known to

promote new vessel formationin granulation tissue. Anotherprominent growth factor

responsible for angiogenesisis: VEGF.

Test q:A 50y/o male isinvolved in a motor vehicleaccident w/liver and spleen

trauma. Surgery requiressplenectomy and partial

hepatectomy. Two years laterthe liver has regenerated toalmost normal size. Thehepatocytes will end

regeneration with secretion of:TGF- .


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Fibroplasia Factors Fibrinogen, plasma fibronectin

Chemotactic mediators from leaky newvessels

PDGF, EGF, FGF From platelets, epithelia & histiocytes Fibroblast migration & proliferation

IL-1, TNF-

Fibrogenic cytokines

Induce PDGF, bFGF, TGF from

macrophages Induce collagen and collagenase in

fibroblasts

TGF- most pleotrophic fibrogenic mediator

All of the above plus inhibit collagenasesecretion (off signal)

Fibroblasts have some phagocytic capability canclean up debris as they migrate.

7. Wound healing & maturation, zinc function

Surgical Wound Healing A model for dealing with other wound types Primary intention

Clean, closely approximated margins Minimal clot/granulation tissue, motion, bacteria

Secondary intention Large tissue defect or reopened surgical wound Greater inflammation and granulation tissue Healing time depends on size of defect Wound contraction up to 95% at 6 weeks (Gpig, rabbit)

Myofibroblasts Elastin remodeling

Fresh Wound (gray = clot w/inflammatory cells in it) Clean incision Limit motion No infection Minimal foreign material Adequate nutrition and circulation

Granulation Tissue Replacement of Injury Collagen accumulation is dynamic

Depends on both synthesis and degradation Metalloproteinases

require zinc ions (so An important for a person with healing wounds)

Serine proteases form leaky vessels Cause continual turnover of ECM in granulation tissue

Granulation Tissue Thin wall vessels Edematous/disorganized stroma Fibroblasts Decreasing inflammation Type III collagen (wiggly lines) Reepithelialization

Test q:As granulation tissue matures, collage type III is

replaced by collagen type I, the wound contracts and bloodvessels appear to dissipate from the reparative tissue. Thisprocess of wound tissue remodeling requires a special class

of protease that requires: Zinc.Test q:A 58y/o physician experiences poor healing of a footlaceration. He decides to take a supplement of __ to

enhance metalloproteinase activity. Zinc.

Documents

Pathology Week 2 p1-18