-fattori eziologici: genetici o intrinseci e acquisiti (infettivi, nutrizionali, chimici, fisici) -patogenesi: sequenza di eventi che si verificano nella risposta cellulare o tessutale

ad un agente eziologico, dallo stimolo iniziale alla manifestazione della malattia

For example, to understand cystic fibrosis o mucoviscidosis (CFTCR (Cystic Fibrosis Transmembrane Conductance Regulator: trasportatore del cloro) is to know not only the defective gene and gene product, but also the biochemical, immunologic, and morphologic events leading to the formation of cysts and fibrosis in the lung, pancreas, and other organs. It leads to thick, viscous secretions.[1]

-modificazioni morfologiche: alterazioni strutturali delle cellule o dei tessuti -alterazioni funzionali e significato clinico: alterazione del funzionamento

normale che determina le caratteristiche cliniche (sintomi)

Patologia: logos (studio) + pathos (sofferenza)

4 elementi formano un processo patologico:

Et in Arcadia ego

Nicolas Poussin

Modulo 1

Lez 1

risposta cellulare allo stress

e adattamento cellulare

Rudolf Ludwig Karl Virchow 1821-1902

He noticed the infiltration of leukocytes in malignant tissues and suggested that cancers arise at site of chronic inflammation

Figure 1-1 Stages in the cellular response to stress and injurious stimuli.

Stadi della risposta cellulare allo stress e agli stimoli dannosi

Principal patterns of cell death -Apoptosis -Necrosis Embriogenesi e vari processi fisiologici Stress conditions

Sublethal or chronic stimuli: -subcellular alterations -intracellular accumulation

(proteins, lipids, carbohidrates) -pathologic calcification -aging

Azione lesiva debole

Modificazioni ambientali

Azione lesiva intensa

Danno cellulare reversibile

Danno cellulare irreversibile

Risoluzione

Adattamento

Necrosi Apoptosi

Danno al DNA

Alterazioni della crescita

Displasia

Infiammazione Neoplasia

Nessun danno

O2 levels

- systemic erythropoietin

- tissue VEGF iNOS

- cellular

glycolytic enzymes glucose transporter 1, 3 transferrin

Control of Oxygen Homeostasis

Nature and Severity of Injurious Stimulus Cellular Response

Altered physiologic stimuli: Cellular adaptations:

• Increased demand, increased trophic stimulation (e.g. growth factors, hormones) • Hyperplasia, hypertrophy

• Decreased nutrients, stimulation • Atrophy

• Chronic irritation (chemical or physical) • Metaplasia

Reduced oxygen supply; chemical injury; microbial infection Cell injury:

• Acute and self-limited • Acute reversible injury

• Progessive and severe (including DNA damage) • Irreversible injury → cell death

Necrosis

Apoptosis

• Mild chronic injury • Subcellular alterations in various organelles

Metabolic alterations, genetic or acquired Intracellular accumulations; calcifications

Prolonged life span with cumulative sublethal injury Cellular aging

Cell response to injury

Adattamento cellulare agli stimoli (iperplasia e ipertrofia)

Modalità di risposta di cellule e tessuti ad aumentate richieste funzionali:

ipertrofia e iperplasia

Figure 1-2 The relationships between normal, adapted, reversibly injured, and dead myocardial cells. The cellular adaptation depicted here is hypertrophy, and the type of cell death is ischemic necrosis. In reversibly injured myocardium, generally effects are only functional, without any readily apparent gross or even microscopic changes. In the example of myocardial hypertrophy, the left ventricular wall is more than 2 cm in thickness (normal is 1 to 1.5 cm). In the specimen showing necrosis, the transmural light area in the posterolateral left ventricle represents an acute myocardial infarction. All three transverse sections have been stained with triphenyltetrazolium chloride, an enzyme substrate that colors viable myocardium magenta. Failure to stain is due to enzyme leakage after cell death.

Adattamento (ipertrofia) e morte cellulare (necrosi) (aumento di miofilamenti)

Trifeniltetrazolio (substrato enzimatico)

Figure 1-4 Changes in the expression of selected genes and proteins during myocardial hypertrophy. In the embryonic heart, the gene for atrial natriuretic factor (ANF) is expressed in both the atrium and the ventricle. After birth, ventricular expression of the gene is down-regulated. Cardiac hypertrophy, however, is associated with reinduction of ANF gene expression. ANF is a peptide hormone that causes salt secretion by the kidney, decreases blood volume and pressure, and therefore serves to reduce hemodynamic load.

Espressione genica nell’ipertrofia miocardica

Geni indotti durante l’ipertrofia miocardica: TGFβIGF-1 FGF Vasoactive agents: α-adrenergic agonists, endothelin-1, angiotensin II

Ipertrofia muscolare: Catena pesante α-miosina sostituita con la forma β. Ciò porta a una riduzione dell’attività adenosin-trifosfatasica della miosina (ATPasi), E a una contrazione piu’ lenta ed economica dal punto di vista energetico

decreased myosin adenosine triphosphatase (ATPase) activity

Figure 1-3 Physiologic hypertrophy of the uterus during pregnancy. A, Gross appearance of a normal uterus (right) and a gravid uterus (removed for postpartum bleeding) (left). B, Small spindle-shaped uterine smooth muscle cells from a normal uterus (left) compared with large

plump cells in gravid uterus (right).

Ipertrofia aumento dimensioni dovuto ad azione di ormoni (estrogeni) su muscolatura liscia

The massive physiologic growth of the uterus during pregnancy is a good example of hormone-induced increase in the size of an organ that results from both hypertrophy and hyperplasia. The cellular hypertrophy is stimulated by estrogenic hormones acting on smooth muscle estrogen receptors, eventually resulting in increased synthesis of smooth muscle proteins and an increase in cell size. Similarly, prolactin and estrogen cause hypertrophy of the breasts during lactation. These are examples of physiologic hypertrophy induced by hormonal stimulation.

Iperplasia (cellule muscolari, epitelio, cellule staminali)

•  Iperplasia ormonale: necessità di aumento della capacità funzionale (aumento della ghiandola mammaria nella pubertà e utero in gravidanza)

•  Iperplasia compensatoria (fegato-Prometeo)

Meccanismi dell’iperplasia -aumento locale di fattori di crescita -aumento recettori di fattori di crescita -attivazione di segnali intracellulari

Nicolas-Sébastien Adam, Parigi, Louvre

Mechanisms of oestrogen action

Prodotti soprattutto da follicoli ovarici e placenta. Poco da fegato e surrenali

Sex steroid hormones, inflammation and cancer

Adattamento cellulare agli stimoli (atrofia)

Modalità di risposta di cellule e tessuti a diminuite richieste funzionali:

atrofia e involuzione

Es.: arto fratturato; mancata innervazione, ridotto apporto ematico, atrofia cerebrale, nutrizione inadeguata, mancata stimolazione endocrina (menopausa: mancanza estrogeni correla con atrofia fisiologica dell’endometrio, della mammella, epitelio vaginale), invecchiamento (tessuti con cellule permanenti), pressione (tumore)

Figure 1-5 A, Atrophy of the brain in an 82-year-old male with atherosclerotic disease. Atrophy of the brain is due to aging and reduced blood supply. The meninges have been stripped. B, Normal

brain of a 36-year-old male. Note that loss of brain substance narrows the gyri and widens the sulci.

Atrofia cerebrale

Mechanisms of Atrophy. The biochemical mechanisms responsible for atrophy are incompletely understood but are likely to affect the balance between protein synthesis and degradation. Increased protein degradation probably plays a key role in atrophy. Mammalian cells contain multiple proteolytic systems that serve distinct functions. Lysosomes contain acid hydrolases (e.g., cathepsins) and other enzymes that degrade endocytosed proteins from the extracellular environment and the cell surface as well as some cellular components. The ubiquitin-proteasome pathway is responsible for the degradation of many cytosolic and nuclear proteins. Proteins to be degraded by this process are first conjugated to ubiquitin and then degraded within a large cytoplasmic proteolytic organelle called the proteasome. This pathway is thought to be responsible for the accelerated proteolysis seen in a variety of catabolic conditions, including cancer cachexia. Hormones, particularly glucocorticoids and thyroid hormone, stimulate proteasome-mediated protein degradation; insulin opposes these actions. Additionally, cytokines, such as tumor necrosis factor (TNF), are capable of increasing muscle proteolysis by way of this mechanism.

Metaplasia

Trasformazione reversibile di un tipo cellulare differenziato in un altro in risposta a condizioni ambientali anomale (risposta adattativa)

Epitelio cilindrico ciliato Fumo di sigaretta Epitelio squamoso (albero bronchiale) Epitelio di transizione Trauma da calcolo Epitelio squamoso (vescica, dotti biliari) Epitelio cilindrico Deficit di vitamina A (diff. cells) Epitelio squamoso (dotti ghiandolari) Epitelio cilindrico Trauma da calcolo Epitelio squamoso (dotti ghiandolari) Epitelio squamoso Acido gastrico Epitelio cilindrico (esofago) Tessuto fibroso (dopo frattura) Trauma cronico Tessuto osseo (osteoide)

Tessuto originale Stimolo Tessuto metaplastico

Metaplasia. A, Schematic diagram of columnar to squamous metaplasia (eg. lung). B, Metaplastic transformation of esophageal stratified squamous epithelium (left) to mature columnar epithelium (so-called Barrett metaplasia).

Metaplasia: Metaplasia does not result from a change in the phenotype of a differentiated cell type; instead it is the result of a reprogramming of stem cells that are known to exist in normal tissues, or of undifferentiated mesenchymal cells present in connective tissue. In a metaplastic change, these precursor cells differentiate along a new pathway.

L'epitelio di Barrett o esofago di Barrett è una metaplasia a carico dell'epitelio esofageo, che viene sostituito con epitelio colonnare. E' una complicanza patologica dell'esofago, in seguito a reflusso gastroesofageo (RGE). In seguito al rilasciamento del cardias, il succo gastrico acido, a contatto prolungato con l'esofago, origina una modificazione dell'epitelio che tenta di difendersi dall'acido. Le cellule che sostituiscono il tratto di epitelio esofageo che viene a contatto con il reflusso acido hanno caratteristiche molto simili a quelle duodenali e costituiscono l'esofago di Barrett. Tale patologia è spesso pre-cancerosa poiché questo epitelio può andare incontro a incontrollata replicazione; questo succede circa nel 2-5% dei casi.

Bar

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squamoso cilindrico

Alv

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squamoso cilindrico

Differentiation pathways for pluripotent bone marrow stromal cells.

Activation of key regulatory proteins by growth factors, cytokines, or matrix components leads to commitment of stem cells to differentiate into specific cellular lineages. Differentiation of myotubes requires the combined action of several factors (e.g., myoD, myogenin); fat cells require PPARγ, the osteogenic lineage requires CBFA1 (also known as RUNX2), cartilage formation requires Sox9, and endothelial cells require VEGF and FGF-2.

Peroxisome proliferator-activated receptors (PPARs): nuclear hormone receptor subfamily of transcription factors.

TGFβ: promotes chondrocites e osteocites; Suppresses muscle e fat

Modulo 1

Lez 2

cause di danno cellulare, apoptosi e necrosi, bersagli biochimici del

danno cellulare

-Mancanza di ossigeno (-ipossia: causa riduzione della respirazione aerobica ossidativa. (glicolisi: 1 glucosio=2 ATP; respirazione

aerobica: 1 glucosio=38 ATP) -ischemia: compromette rifornimento di ossigeno e di substrati metabolici, es. Glucosio) L'ischemia è una mancanza assoluta o parziale di sangue in un organo (per parziale si intende una differenza tra fornitura di sangue e la richiesta di sangue necessaria per la corretta ossigenazione del tessuto). Essa può anche essere descritta come inadeguato flusso sanguigno verso una parte del corpo, causata da una costrizione o ostruzione dei vasi sanguigni.

-agenti fisici (traumi, temperatura, radiazioni, etc.)

-agenti chimici e farmaci (glucosio, Sali a concentrazioni ipertoniche (alterazione omeostasi elettrolitica); O2 ad alte concentrazioni

-agenti infettivi (virus, batteri, funghi, parassiti)

-reazioni immunologiche (autoimmunità; reazioni anafilattiche verso proteine estranee o farmaci)

-alterazioni genetiche (es.: anemia falciforme: La condizione falcemica è ereditata in maniera autosomica recessiva, ed è caratterizzata dalla produzione di una emoglobina patologica, detta HbS, che per le sue caratteristiche chimiche, tende a precipitare ed a conferire all'eritrocita la tipica forma a ridotta sopravvivenza globuli rossi; βTalassemia: emopatie ereditarie recessive, caratterizzate dalla ridotta o assente sintesi dell'emoglobina. Sintesi difettosa dell’emoglobina β. Le alterazioni del gene beta sono eterogenee: possono infatti verificarsi sia delezione, sia alterazioni puntiformi Porta a distruzione precoce delle cellule emopoietiche)

-squilibri nutrizionali (es.: carenza in popolazioni povere, anoressia, digiuno volontario; eccesso in: obesità predispone a aterosclerosi, eccesso di lipidi nella dieta a steatosi epatica)

-malattie metaboliche: diabete (glicotossicità, infiammazione, tossicità lipidi)

Cause di danno cellulare

Stages in the evolution of cell injury and death.

Fasi dell’evoluzione della morte e del danno cellulare

Necrosi e apoptosi differiscono per morfologia, meccanismi e ruoli in fisiologia e patologia

Riduzione fosforilazione ossidativa Deplezione ATP rigonfiamento cellulare per: variazione concentrazione ionica e Ingresso H2O

Danni mitocondriali

Danni membrane,

rilascio enzimi lisosomiali e digestione del citoplasma

necrosi

lethal hit

Schematic representation of a normal cell and the changes in reversible and irreversible cell injury. Reversible injury is characterized by generalized swelling of the cell and its organelles; blebbing of the plasma membrane; detachment of ribosomes from the endoplasmic reticulum; and clumping of nuclear chromatin. Transition to irreversible injury is characterized by increasing swelling of the cell; swelling and disruption of lysosomes; presence of large amorphous densities in swollen mitochondria; disruption of cellular membranes; and profound nuclear changes. The latter include nuclear codensation (pyknosis), followed by fragmentation (karyorrhexis) and dissolution of the nucleus (karyolysis). Laminated structures (myelin figures) derived from damaged membranes of organelles and the plasma membrane first appear during the reversible stage and become more pronounced in irreversibly damaged cells.

Danno cellulare reversibile e irreversibile

lethal hit

nuclear codensation (pyknosis), followed by fragmentation (karyorrhexis) and dissolution of the nucleus (karyolysis).

The sequential ultrastructural changes seen in necrosis (left) and apoptosis (right). In apoptosis, the initial changes consist of nuclear chromatin condensation and fragmentation, followed by cytoplasmic budding and

phagocytosis of the extruded apoptotic bodies. Signs of cytoplasmic blebs, and digestion and leakage of cellular components.

Alterazioni ultrastrutturali nella necrosi e nell’apoptosi

Feature Necrosis Apoptosis

Cell size Enlarged (swelling) Reduced (shrinkage)

Nucleus Pyknosis → karyorrhexis → karyolysis

Fragmentation into nucleosome size fragments

Plasma membrane

Disrupted Intact; altered structure, especially orientation of lipids

Cellular contents

Enzymatic digestion; may leak

out of cell

Intact; may be released in apoptotic bodies

Adjacent inflammation

Frequent No

Physiologic or pathologic role

Invariably pathologic (culmination of irreversible

cell injury)

Often physiologic, means of eliminating unwanted cells; may be pathologic after some forms of cell injury, especially DNA damage

Features of necrosis and apoptosis

Bersagli funzionali della lesione cellulare

-Durata stimolo lesivo -Capacità di adattamento cellula danneggiata

Cellular and biochemical sites of damage in cell injury.

Bersagli cellulari biochimici del danno cellulare respirazione aerobica, integrità membrane cellulari (omeostasi ionica), sintesi proteica, citoscheletro, integrità apparato genetico

Functional and morphologic consequences of decreased intracellular ATP during cell injury.

deplezione ATP spesso associata a danno ipossico o chimico

membrane transport sintesi proteica, lipogenesi

Es.: cervello vs fegato

Danno pompa Na/K: Na accumula, K scende

Mitochondrial dysfunction in cell injury.

Disfunzione mitocondriale nel danno cellulare

Formazione di canali MTP: Preclude mantenimento del potenziale di membrana

Cytocrome c è Componente integrale Della fosforilazione ossidativa. Induce morte cellulare

Danni mitocondriali indotti da: -aumento calcio citosolico -stress ossidativo -fosfolipasi A2 e sfingomielina (rottura fosfolipidi) -derivati di lipidi (acidi grassi liberi e ceramide)

Sources and consequences of increased cytosolic calcium in cell injury. ATP, adenosine triphosphate.

Incremento citosolico di calcio nel danno cellulare

(1,3 mmol)

(<0.01 µmol)

gradiente di Ca2+ è regolato da: Ca2+ e Mg2+ ATPase

The role of reactive oxygen species in cell injury. O2 is converted to superoxide (O2-) by oxidative enzymes in the endoplasmic reticulum (ER), mitochondria, plasma membrane, peroxisomes, and cytosol. O2- is converted to H2O2 by dismutation and thence to OH by the Cu2+/Fe2+-catalyzed Fenton reaction. H2O2 is also derived directly from oxidases in peroxisomes.

Not shown is another potentially injurious radical, singlet oxygen. Resultant free radical damage to lipid (peroxidation), proteins, and DNA leads to various forms of cell injury. Note that superoxide catalyzes the reduction of Fe3+ to Fe2+, thus enhancing OH generation by the Fenton reaction. The major antioxidant enzymes are superoxide dismutase (SOD), catalase, and glutathione peroxidase. GSH,

reduced glutathione; GSSG, oxidized glutathione; NADPH, reduced form of nicotinamide adenine dinucleotide phosphate.

Ruolo delle specie reattive nel danno cellulare (stress ossidativo da ischemia e riperfusione)

NO puo’ agire da radicale libero, ma può esser anche convertito in Anione perossinitrito (ONOO-)

o in NO2 e NO3-

Energia: riduzione O2 a H2O

H2O2

(Glutatione: tripeptide antiossidante)

(chela ferro) (chela rame e ferro)

Mechanisms of membrane damage in cell injury. Decreased O2 and increased cytosolic Ca2+ are typically seen in ischemia but may accompany other forms of cell injury. Reactive oxygen species, which are often produced on

reperfusion of ischemic tissues, also cause membrane damage.

Danno di membrana nel danno cellulare

-Ac.grassi liberi non esterificati -Acil carnitina e lisofosfolipidi -Prodotti catabolici risultanti dalla Degradazione dei fosfolipidi

Rottura membrane lisosomi libera: -RNasi -Lipasi -Glucosidasi -catepsine

Timing of biochemical and morphologic changes in cell injury.

Morphologic changes in reversible and irreversible cell injury. A, Electron micrograph of a normal epithelial cell of the proximal kidney tubule. Note abundant microvilli (mv) lining the lumen (L). N, nucleus; V, apical vacuoles (which are normal structures in this cell type). B, Epithelial cell of the proximal tubule showing reversible ischemic changes. The microvilli (mv) are lost and have been incorporated in apical cytoplasm; blebs have formed and are

extruded in the lumen (L). Mitochondria are slightly dilated. (Compare with A.) C, Proximal tubular cell showing irreversible ischemic injury. Note the markedly swollen mitochondria containing amorphous densities, disrupted

cell membranes, and dense pyknotic nucleus.

Postulated sequence of events in reversible and irreversible ischemic cell injury. Note that although reduced oxidative phosphorylation and ATP levels have a central role, ischemia can cause direct membrane damage. ER,

endoplasmic reticulum; CK, creatine kinase; LDH, lactate dehydrogenase; RNP, ribonucleoprotein.

Postulated sequence of events in reversible and irreversible ischemic

neutrofili Attivazione del complemento

Doppi strati lipidici sovrapposti che assumono la forma di sfere, di cilindri e spirali

Modulo 1

Lez 3

Danno ischemico, danno chimico, apoptosi, accumuli intracellulari

ISCHEMIA-REPERFUSION INJURY

•  Restoration of blood flow to ischemic tissues can result in recovery of cells if they are reversibly injured, or not affect the outcome if irreversible cell damage has occurred. However, depending on the intensity and duration of the ischemic insult, variable numbers of cells may proceed to die after blood flow resumes, by necrosis as well as by apoptosis. The affected tissues often show neutrophilic infiltrates. As noted earlier, this ischemia-reperfusion injury is a clinically important process in such conditions as myocardial infarction and stroke and may be amenable to therapeutic interventions.

•  How does reperfusion injury occur? The likely answer is that new damaging processes are set in motion during reperfusion, causing the death of cells that might have recovered otherwise. Several mechanisms have been proposed: New damage may be initiated during reoxygenation by increased generation of oxygen free radicals from parenchymal and endothelial cells and from infiltrating leukocytes. Superoxide anions can be produced in reperfused tissue as a result of incomplete and vicarious reduction of oxygen by damaged mitochondria or because of the action of oxidases derived from leukocytes, endothelial cells, or parenchymal cells. Cellular antioxidant defense mechanisms may also be compromised by ischemia, favoring the accumulation of radicals. Free radical scavengers may be of therapeutic benefit.

•  Reactive oxygen species can further promote the mitochondrial permeability transition, referred to earlier, which, when it occurs, precludes mitochondrial energization and cellular ATP recovery and leads to cell death.

•  Ischemic injury is associated with inflammation as a result of the production of cytokines and increased expression of adhesion molecules by hypoxic parenchymal and endothelial cells. These agents recruit circulating polymorphonuclear leukocytes to reperfused tissue; the ensuing inflammation causes additional injury. The importance of neutrophil influx in reperfusion injury has been demonstrated by experimental studies that have used anti-inflammatory interventions, such as antibodies to cytokines or adhesion molecules, to reduce the extent of the injury.

•  Recent data suggest that activation of the complement pathway may contribute to ischemia-reperfusion injury. The complement system is involved in host defense and is an important mechanism of immune injury. Some IgM antibodies have a propensity to deposit in ischemic tissues, for unknown reasons, and when blood flow is resumed, complement proteins bind to the antibodies, are activated, and cause cell injury and inflammation. Knockout mice lacking several complement proteins are resistant to this type of injury.

Sequence of events leading to fatty change and cell necrosis in carbon tetrachloride (CCl4) toxicity. RER, rough endoplasmic reticulum; SER, smooth endoplasmic reticulum.

Danno chimico -Cl-Mercurio (lega gruppi sulfidrili della membrana): Aumento permeabilità membrana cell. e blocco del trasporto attivo ATPasi-dipendente -Cianuro: avvelena citocromo ossidasi mitocondriale e blocca respirazione

ossidativa

ossidasi p450 ossidazione

-Paracetamolo: P-450 catabolizza conversione paracetamolo a metabolita tossico (NAPQ1). NAPQ1 interagisce con GSH (riducente). Se vengono Ingerite alte dosi….

lavanderie

CCl3.:highly reactive toxic free radical

citocromi P450: sono i maggiori attori coinvolti nella detossificazione dell'organismo

Interagiscono con trigliceridi per secrezione

The sequential ultrastructural changes seen in necrosis (left) and apoptosis (right). In apoptosis, the initial changes consist of nuclear chromatin condensation and fragmentation, followed by cytoplasmic budding and phagocytosis of the extruded

apoptotic bodies. Signs of cytoplasmic blebs, and digestion and leakage of cellular components.

Apoptosi •  Physiologic situations •  embriogenesi (organogenesi, sviluppo involutivo) •  Hormone-dependent involution in adults (cellule endometrio durante ciclo

mestruale; follicoli ovarici in menopausa). •  Cell deletion in proliferating epithelia (intestinal cript), to maintain costant

number •  inflammation •  Elimination of self-reactive lymphocytes •  Cell death induced by reactive T lymphocytes

•  Pathologic situations •  Cell death produced by injurious stimuli •  Cell death in viral diseases •  pathologic atrophy in parenchimal organs after duct obstruction (pancreas,

kindey) •  Cell death induced by T cells in tumors

Agarose gel electrophoresis of DNA extracted from culture cells. Ethidium bromide stain; photographed under ultraviolet illumination. Lane A, Control culture. Lane B, Culture of cells exposed to heat showing extensive apoptosis; note ladder pattern of DNA fragments, which represent multiples of oligonucleosomes. Lane C, Culture showing massive necrosis; note diffuse smearing of DNA. The ladder pattern is produced by enzymatic cleavage of nuclear DNA into nucleosome-sized fragments, usually multiples of 180-200 base pairs.

These patterns are characteristic of but not specific for apoptosis and necrosis, respectively.

Apoptosi: -clivaggio delle proteine: (caspasi) -rottura del DNA-endonucleasi: (50-300kb e taglio internucleosomico 300-500nt) -ricognizione fagocitaria: fosfatidilserina/annessina5, Trombospondina; fagocitosi

Mechanisms of apoptosis. Labeled (1) are some of the major inducers of apoptosis. These include specific death ligands (tumor necrosis factor [TNF] and Fas ligand), withdrawal of growth factors or hormones, and injurious agents (e.g., radiation). Some stimuli (such as cytotoxic cells) directly activate execution caspases (right). Others

act by way of adapter proteins and initiator caspases, or by mitochondrial events involving cytochrome c. (2) Control and regulation are influenced by members of the Bcl-2 family of proteins, which can either inhibit or promote the cell's death. (3) Executioner caspases activate latent cytoplasmic endonucleases and proteases that degrade

nuclear and cytoskeletal proteins. This results in a cascade of intracellular degradation, including fragmentation of nuclear chromatin and breakdown of the cytoskeleton. (4) The end result is formation of apoptotic bodies containing intracellular organelles and other cytosolic components; these bodies also express new ligands for binding

and uptake by phagocytic cells.

FADD-Fas-associated death domain

The extrinsic (death receptor-initiated) pathway of apoptosis, illustrated by the events following Fas engagement

The extrinsic pathway

Virus: FLIP

Nell’uomo: Caspase 10

The intrinsic (mitochondrial) pathway of apoptosis. Death agonists cause changes in the inner mitochondrial membrane, resulting in the mitochondrial permeability transition (MPT) and release of cytochrome c and other pro-apoptotic proteins into the cytosol, which activate caspases (see text).

The intrinsic (mitochondrial) pathway of apoptosis

(20 members)

(Fattore pro-apoptotico)

Caspase3/6

Proteine della trascrizione, Replicazione e riparo del DNA

Film apoptosis

http://www.youtube.com/watch?v=tf0EifpnAus

http://www.google.it/url?sa=t&rct=j&q=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3Dtf0eifpnaus&source=web&cd=1&cad=rja&sqi=2&ved=0CCAQtwIwAA&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3Dtf0EifpnAus&ei=RmNwUOeaOsjMsgaD14GgDQ&usg=AFQjCNFnzh8Uuspfz_1KnUjP9DPJIxElsA

•  Patologie associate a difetto di apoptosi: -cancro -malattie autoimmuni (Linfociti T autoimmuni)

•  Patologie associate a un aumento di apoptosi: -malattie neurodegenerative (atrofia muscolare spinale) -danno ischemico (infarto miocardico, ictus cerebrale) -infezioni virali (morte cellule infettate)

A, Schematic representation of heterophagy (left) and autophagy (right). (Redrawn from Fawcett DW: A Textbook of Histology, 11th ed. Philadelphia, WB Saunders, 1986, p 17.) B, Electron micrograph of an autophagolysosome containing a degenerating mitochondrion and amorphous material.

Enzimi idrolitici: -fosfatasi acida –glucuronidasi -solfatasi -ribonucleasi -collagenasi

Fagosomi, lisosomi

autofagolisosoma

Materiale indigerito (-malattie ereditarie da accumulo lisosomiale, neuroni: deficit di enzimi -malattie lisosomiali acquisite- farmaco indotte: clorochina aumenta pH)

Mechanisms of intracellular accumulations: (1) abnormal metabolism, as in fatty change in the liver; (2) mutations causing alterations in protein folding and transport, as in alpha1-antitrypsin deficiency; (3) deficiency of critical enzymes that prevent breakdown of substrates that accumulate in lysosomes, as in lysosomal storage diseases; and

(4) inability to degrade phagocytosed particles, as in hemosiderosis and carbon pigment accumulation.

α1-antitripsina: cirrosi, enfisema

accumulo di sostanze non metabolizzabili (silice)

Carenza di glucocerebrosidasi: Trasforma glucocerebroside in glucosio e ceramide

Fatty liver. A, Schematic diagram of the possible mechanisms leading to accumulation of triglycerides in fatty liver. Defects in any of the steps of uptake, catabolism, or secretion can result in lipid accumulation. B, High-power detail of fatty change of the liver. In most cells, the well-preserved nucleus is squeezed into the displaced rim of cytoplasm about the fat vacuole.

Cause steatosi: Tossine Malnutrizione proteica Diabete mellito Obesità Anossia Abuso alcool

este

rific

azio

ne

Fatty liver. A, Schematic diagram of the possible mechanisms leading to accumulation of triglycerides in fatty liver. Defects in any of the steps of uptake, catabolism, or secretion can result in lipid accumulation. B, High-power detail of fatty change of the liver. In most cells, the well-preserved nucleus is squeezed into the displaced rim of cytoplasm about the fat vacuole.

Mechanisms of protein folding and the role of chaperones. A, Chaperones, such as heat shock proteins (Hsp), protect unfolded or partially folded protein from degradation and guide proteins into organelles. B, Chaperones repair misfolded proteins; when this process is ineffective, proteins are targeted for degradation in the proteasome, and if misfolded proteins accumulate they

trigger apoptosis.

Role of chaperones

α elica o β foglietti

Mechanisms of protein folding and the role of chaperones. A, Chaperones, such as heat shock proteins (Hsp), protect unfolded or partially folded protein from degradation and guide proteins into organelles. B, Chaperones

repair misfolded proteins; when this process is ineffective, proteins are targeted for degradation in the proteasome, and if misfolded proteins accumulate they trigger apoptosis.

Deficit α1antitripsina: rallentamento processo ripiegamento e accumulo intermedi non ripiegati Nel reticolo endoplasmico del fegato- Enfisema

Fibrosi cistica: mutazione ritarda dissociazione della proteina canale del cloro Da un chaperonina. Ripiegamento anomalo e perdita di funzione della proteina stessa

Protein reabsorption droplets in the renal tubular epithelium.

Proteinuria: malattia renale con perdita proteine nelle urine. Grave perdita proteine dal filtro glomerulare. Aumento di riassorbimento proteico e delle vescicole. Formazione di fagolisosomi.

Gocciole proteiche ialine

•  Accumuli intracellulari •  glicogeno: disturbo del metabolismo glucosio/glicogeno. Masse di glicogeno-vacuoli

chiai-all’interno del citoplasa. (es. diabete: granuli presenti nelle cellule epiteliali dell’ansa di Henle,delle cellule b delle isole di Langerhans, cellule muscolari cardiache)

•  Pigmenti: esogeni (es. carbone nei macrofagi alveolari-antracosi,

pneumoconiosi del minatore) e endogeni (es. lipofuscina o lipocromo o pigmento della vecchiaia. Sono polimeri di lipidi e fosfolipidi complessati con proteine)

•  Melanina: malattia metabolica (alcaptonuria) causa accumulo di melanina. Da particolare pigmentazione: ocronosi

•  Emosiderina: pigmento derivato dall’emoglobina, granulare o cristallino. Aggregati di ferritina (ferro + apoferritina:trasporatore del ferro).

Hemosiderin granules in liver cells. A, H&E section showing golden-brown, finely granular pigment. B, Prussian blue reaction, specific for iron.

•  Calcificazioni patologiche: Anormale deposizione di Sali di calcio, insieme a minore quantità di

ferro, magnesio e altri sali minerali.

•  Nei tessuti morti: calcificazione distrofica

•  Nei tessuti normali: calcificazione metastatica: deriva da ipercalcemia secondaria a disturbi del metabolismo del calcio

Mechanisms of cellular aging. Genetic factors and environmental insults combine to produce the cellular abnormalities characteristic of aging.

Invecchiamento cellulare