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Role of apoptosis in cardiovascular system

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  • apoptosis in cvs
  • apoptosis in cvs
  • Apaptosis

    1. 1. APoPToSIS IncArdIovASculAr dISorderS Dr.I.TAMMI RAJU
    2. 2. overvIew• Introduction• Apoptotic pathways• Diseases in cvs-apoptosis• Imaging in apoptosis• Therapeutic options of apoptosis modulation• Anti apoptotic drugs• Set backs of apoptosis APOPTOSIS IN CVS
    3. 3. DEFNITION• Apoptosis or programmed cell death, is carefully coordinated collapse of cell, protein degradation , DNA fragmentation followed by rapid engulfment of corpses by neighbouring cells. (Tommi, 2002)• Essential part of life for every multicellular organism from worms to humans. (Faddy et al.,1992)• Apoptosis plays a major role from embryonic development to senescence. APOPTOSIS IN CVS
    4. 4. HISTory of cell deATH / APoPToSIS reSeArcH1971 Term apoptosis coined1977 Cell death genes in C. elegans1980-82 DNA ladder observed & ced-3 identified1989-91 Apoptosis genes identified, including bcl-2, fas/apo1 & p53, ced-3 sequenced (Richerd et.al., 2001)
    5. 5. InTroducTIonCell death by injury -Mechanical damage -Exposure to toxic chemicalsCell death by suicide -Internal signals -External signals APOPTOSIS IN CVS
    6. 6. wHy SHould A cell commIT SuIcIde? Apoptosis is needed for proper development Examples: – The resorption of the tadpole tail – The formation of the fingers and toes of the fetus – The sloughing off of the inner lining of the uterus – The formation of the proper connections between neurons in the brain• Apoptosis is needed to destroy cells Examples: – Cells infected with viruses – Cells of the immune system – Cells with DNA damage – Cancer cells APOPTOSIS IN CVS
    7. 7. wHAT mAkeS A cell decIde To commIT SuIcIde? Withdrawal of positive signals examples : – growth factors – Interleukin-2 (IL-2) Receipt of negative signals examples : – increased levels of oxidants within the cell – damage to DNA by oxidants – death activators : Tumor necrosis factor alpha (TNF-α) Lymphotoxin (TNF-β) Fas ligand (FasL) APOPTOSIS IN CVS
    8. 8. GloSSAry• Bcl-2 Family Proteins• This class of proteins shows homology to the C elegans protein ced-9.• The first member of this protein family was named B- cell lymphoma 2 gene (bcl-2.)• In mammalian species, both proapoptotic and antiapoptotic members of this protein family have been characterized.• Bcl-2 family proteins are localized to the outer mitochondrial and nuclear membranes and to the membrane of the endoplasmic reticulum. APOPTOSIS IN CVS
    9. 9. cASPASeS• cysteine-aspartic proteases or cysteine-dependent aspartate-directed proteases are a family of cysteine proteases that play essential roles in  apoptosis (programmed cell death), necrosis, and inflammation.• There are two types of apoptotic caspases:  – initiator (apical/upstream) caspases and – effector (executioner/downstream) caspases.• Initiator caspases (e.g., CASP2, CASP8, CASP9, and CASP10) cleave inactive pro-forms of effector caspases, thereby activating them.• Effector caspases (e.g., CASP3, CASP6, CASP7) in turn cleave other protein substrates within the cell, to trigger the apoptotic process. APOPTOSIS IN CVS
    10. 10. APOPTOSIS IN CVS
    11. 11. • Death Receptors• Death receptors are a class of cell membrane receptors belonging to the larger group of TNF receptors.• Members of this group comprise Fas, TNFR1, DR3, DR4, and DR5.• Fas• Fas, the prototypical death receptor, mediates apoptotic cell death after stimulation by Fas ligand.• Receptor activation involves the recruitment of adaptor proteins to the cell membrane and subsequent caspase activation APOPTOSIS IN CVS
    12. 12. • Inhibitor of Apoptosis Proteins• IAPs are a class of antiapoptotic proteins that were initially isolated in baculovirus, a virus infecting insect cells.• Mammalian homologues are believed to inhibit apoptosis by direct caspase inhibition and by mediating survival signals after TNFR stimulation.• p53• p53 is a transcriptional transactivator protein that is involved in cell cycle control and DNA repair.• p53 has been implicated in apoptosis induced by genotoxic agents and deregulated cell cycle control. APOPTOSIS IN CVS
    13. 13. APoPToSIS: PATHwAyS “Extrinsic Pathway” Death Death Initiator Ligands Receptors Caspase 8 Effector “Intrinsic Pathway” Caspase 3 PCD DNA Initiator Mitochondria/damage Caspase 9 Cytochrome C & p53 APOPTOSIS IN CVS
    14. 14. APOPTOSIS IN CVS DEATH SIGNALLING PATHWAYS.• Schematic of Fas death signalling pathways. Fas, the prototypic member of the tumour necrosis factor (TNF) death receptor family,binds to its cognate ligand.• Recruitment of the adapter molecule FADD and pro-caspase 8 results in activation of the latter.• Caspase 8 activation directly activates downstream caspases, (3, 6, and 7) which results in DNA fragmentation and cleavage of cellular proteins.• This pathway is thought to occur in type I cells and does not involve mitochondrial pathways.
    15. 15. APOPTOSIS IN CVS Mitochondrial death signalling• Anti-apoptotic members of the Bcl-2 family, pathways such as Bcl-2 and Bcl-X, are located on the mitochondrial outer membrane.• Here they act to prevent the release of apoptogenic factors from the inner mitochondrial space.• Binding of the pro-apoptotic proteins Bid (after cleavage by caspase 8) or Bad (after dephosphorylation) to Bcl-2 mitigates the protective effect of Bcl-2 and triggers release of cytochrome c and Smac/DIABLO.• Cytochrome c, in concert with the adapter protein apaf-1 and caspase 9, activates caspase 3 and the downstream caspase cascade.• Smac/DIABLO inhibits IAPs (inhibitor of apoptosis proteins), which in turn inhibit caspase activities, thus propagating apoptosis• Stimuli such as growth factor withdrawal or activation of p53 and Fas activation in type II cells act through this mitochondrial pathway
    16. 16. APOPTOSIS IN CVS
    17. 17. APOPTOSIS IN CVS
    18. 18. reGulATIon of APoPToSIS• The can be simplified into twomajor Pathways .• First, membrane bound death receptor of the tumour necrosis receptor family (TNF-R), such as Fas (CD95), TNF-R1, or death receptors (DR) 3–6, bind their trimerised ligands• causing receptor aggregation, and• subsequent recruitment of adapter proteins (Fas-FADD, TNF-R1 TRADD, etc) through protein:protein interactions• adapters recruit cysteine proteases (caspases) such as caspase 8 (FLICE) and caspase 2 to the complex.14• Within the complex of Fas, FADD, and caspase 8 (known as the death inducing signalling complex (DISC)), caspase 8 becomes proteolytically activated by oligomerisation.15• This in turn activates the terminal effector caspases (caspases 3, 6, and 7) responsible for cleavage of intracellular substrates required for cellular survival, architecture, and metabolic function. APOPTOSIS IN CVS
    19. 19. APOPTOSIS IN CVSmembrane bound death receptor (TNF-R), Fas (CD95), TNF-R1, (DR) 3–6, bind their trimerised ligands receptor aggregation recruitment of adapter proteins (Fas-FADD, TNF-R1 TRADD adapters recruit cysteine proteases (caspases) such as caspase 8 (FLICE) and caspase 2 to the complex activates the terminal effector caspases (caspases 3, 6, and 7)
    20. 20. APoPToSIS vIA mITocHondrIAl AmPlIfIcATIon• In addition to direct activation of caspases, caspase 8 activation causes cleavage of bcl-2 family proteins such as bid (fig 3).• Bcl-2 family members are either – pro-apoptotic (Bax, Bid, Bik, Bak) or – anti-apoptotic (Bcl-2, Bcl-XL).• Activation of pro-apoptotic Bcl-2 family members causes their translocation to mitochondria, where they interact with anti- apoptotic members .• This interaction depolarises voltage dependent mitochondrial channels and releases mitochondrial mediators of apoptosis such as cytochrome c16and Smac/DIABLO.• The association of cytochrome c with an adapter molecule apaf-1 and caspase 9 activates caspase 3, and the caspase cascade. APOPTOSIS IN CVS
    21. 21. • Smac/DIABLO promotes apoptosis by directly antagonising inhibitor of apoptosis proteins (IAPs).• Apoptosis can be blocked FLIPs (FLICE inhibitory proproteins) and IAPs .• FLIPs have the same pro-domain structure as caspase 8, but do not have the active caspase site within the C-terminus.• Binding of FLIP to caspase 8 therefore prevents its activation.• In contrast, IAPs inhibit the enzymatic activity of downstream caspases, or they can mediate anti-apoptotic signalling pathways through the activation of nuclear transcription factor kb. APOPTOSIS IN CVS
    22. 22. necroSIS vS. APoPToSIS Necrosis Apoptosis• Cellular swelling • Cellular condensation• Membranes are broken • Membranes remain intact• ATP is depleted • Requires ATP• Cell lyses, eliciting an • Cell is phagocytosed, no tissue inflammatory reaction reaction• DNA fragmentation is random, • Ladder-like DNA fragmentation or smeared • In vivo, individual cells appear• In vivo, whole areas of the affected tissue are affected APOPTOSIS IN CVS
    23. 23. necroSIS vS APoPToSIS APOPTOSIS IN CVS Wilde, 1999
    24. 24. APOPTOSIS IN CVS
    25. 25. APoPToSIS In cArdIAc develoPmenT• During cardiac development, programmed cell death was suggested to be of importance in the formation of septal, valvular, and vascular structures, implicating the potential importance of either excessive or inappropriate apoptosis in congenital heart disease.• However, so far, direct evidence for an apoptotic cell death by TUNEL staining has been provided only for mesenchymal cells in the bulbus cordis of the rat heart at 14 and 16 days of gestation. APOPTOSIS IN CVS
    26. 26. APOPTOSIS IN CVS
    27. 27. APoPToSIS And HeArT fAIlure• Besides myocyte hypertrophy, myocyte dysfunction due to altered calcium homeostasis, impaired myofilament Ca21 sensitivity, fiber slippage, and myocardial fibrosis, progressive loss of cardiomyocytes is considered to play a major contributory role.• In canine models of pacing-induced heart failure and heart failure due to chronic ischemic injury, loss of cardiomyocytes due to apoptosis was detectable by TUNEL staining, whereas in control myocardium only rare cardiomyocytes stained positive.• Narula et al reported that in myocardial specimens from patients undergoing cardiac transplantation, apoptosis detected by TUNEL staining was consistently observed in idiopathic dilated cardiomyopathy but not in ischemic cardiomyopathy. Narula J, Haider N, Apoptosis in myocytes in end-stage heart failure. N Engl J Med. 1996;335:1182–1189 APOPTOSIS IN CVS
    28. 28. • Potential mechanisms for the induction of apoptotis – mechanical factors or – elevated neurohumoral factors.• In a model of isometric stretch of papillary muscle, apoptosis of cardiomyocytes could be detected in 0.64% of cardiomyocytes by TUNEL staining, indicating that volume overload and elevated end- diastolic left ventricular pressure may constitute an initiating event for myocyte apoptosis. Cheng W, Li B, Kajstura J Stretch-induced programmed myocyte cell death. J Clin Invest. 1995;96:2247–2259.
    29. 29. The cellular basis of pacing-induced dilated cardiomyopathy in canine model: myocyte cell loss and myocyte cellular reactive hypertrophy. Circulation. 1995;92:2306 –2317• Kajstura et al observed an increased percentage of apoptotic cells with angiotensin II treatment. (0.9% apoptotic cells in angiotensin II–treated cells versus 0.2% in control cells).• This effect was mediated by AT1 angiotensin II receptors.• Recently, atrial natriuretic factor (ANF) was shown to increase the apoptotic index from 4.8% to 19% in isolated neonatal cardiomyocytes.• Because ANF levels are elevated in heart failure, sensitivity of cardiomyocytes to ANF may be of pathophysiological importance.• ??? ANF is produced at high levels in the atrial and fetal ventricular myocytes, and there is no evidence of apoptosis so far reported in these cells in vivo. APOPTOSIS IN CVS
    30. 30. • Vastly different rates of apoptosis have been reported in both human and animal heart failure, with rates of up to 35.5%.• While these death rates may be seen only in very localised areas, given that apoptosis takes less than 24 hours to complete such rates would result in rapid involution of the heart.• More recently, rates of < 0.5% have been consistently reported in end stage heart failure, which make far more physiological sense. In addition, in end stage heart failure necrosis is still (up to seven times) more frequent than apoptosis. APOPTOSIS IN CVS
    31. 31. • In acute ischemia and reperfusion, apoptosis can be high as 14% in the area at risk.• In contrast, the rate of apoptosis associated with chronic stimuli, such as pressure overload, is ,1% in nontransgenic models when measured by terminal deoxynucleotidyl transferase–mediated dUTP nick end- labeling (TUNEL) staining.• Much lower values for the apoptotic index (0.2% to 0.4%) that are still 100-fold above control values may therefore more reliably reflect the overall extent of ongoing myocyte apoptosis in heart failure Olivetti G, Abbi R, Quaini F,. Apoptosis in the failing human heart. N Engl J Med. 1997;336: 1131–1141. APOPTOSIS IN CVS
    32. 32. APOPTOSIS IN ARVD• Numerous cells in the right ventricle of patients with arrhythmogenic right ventricular dysplasia undergo apoptosis.• The affected areas had few or no apoptotic cells, whereas apoptotic nuclei were frequently seen in areas with little involvement.• This finding suggests that the loss of myocardial cells through apoptosis is, at least in part, a primary process that precedes the filling of acellular space by fat and fibrous tissue in the absence of an inflammatory reaction.
    33. 33. • The triggering factors for apoptotic myocardial cell death in arrhythmogenic right ventricular dysplasia remain to be elucidated.• Some evidence from in vitro and in vivo studies in animals suggests that hypoxia as well as reperfusion injury are possible triggers for apoptosis in cardiomyocytes.• The presence of myocarditis (and its related production of inflammatory cytokines) could also have a role . APOPTOSIS IN CVS
    34. 34. In Situ End-Labeling of Fragmented DNA with TdT and Biotinylated dUTP.Cells with fragmented DNA stained brown, whereas cells withnormal nuclei stained blue (immunoperoxidase staining with hematoxylin counterstaining).
    35. 35. Expression of CPP-32 in Right Ventricular Myocardiumfrom Patients with Arrhythmogenic Right Ventricular DysplasiaNORMAL ARVD Immunohistochemical Detection of CPP-32. Normal right ventricular myocardium does not stain for CPP-32 right ventricular myocardium from a patient with right ventricular dysplasia stains intensely for CPP-32
    36. 36. effecT of vSmc APoPToSIS• Vascular smooth muscle cells (VSMCs) within the vessel wall can both divide and undergo apoptosis throughout life.• However, the normal adult artery shows very low apoptotic and mitotic indices.• In diseased tissue additional factors are present both locally, such as inflammatory cytokines, inflammatory cells, and the presence of modified cholesterol, and systemically, such as blood pressure and flow.• These factors substantially alter the normal balance of proliferation and apoptosis, and apoptosis in particular may predominate in many disease states. APOPTOSIS IN CVS
    37. 37. • The effect of VSMC apoptosis is clearly context dependent.• Intimal VSMC apoptosis --promote plaque rupture,• Medial --promote aneurysm formation.• In neointima formation post-injury, VSMC apoptosis of both intima and media can limit neointimal formation at a defined time point.• However, apoptosis is also associated with a number of deleterious effects.• Exposure of phosphatidylserine on the surface of apoptotic cells provides a potent substrate for the generation of thrombin and activation of the coagulation cascade,and apoptotic cells release membrane bound microparticles that are systemically procoagulant.• Finally, VSMC apoptosis may be directly pro-inflammatory, with release of chemoattractants and cytokines from inflammatory cells. APOPTOSIS IN CVS
    38. 38. • Remodelling• Remodelling defines a condition in which alterations in vessel size can occur through processes that do not necessarily require large changes in overall cell number or tissue mass.• For example, physiological remodelling by cell proliferation/apoptosis results in closure of the ductus arteriosus and reduction in lumen size of infra-umbilical arteries after birth, and remodelling occurs in primary atherosclerosis, after angioplasty and in restenosis.• Although surgical reduction in flow results in compensatory VSMC apoptosis, the role of VSMC apoptosis per se in determining the outcome of remodelling is unclear. APOPTOSIS IN CVS
    39. 39. • Arterial injury and aneurysm formation• Acute arterial injury at angioplasty is followed by rapid induction of medial cell apoptosis.• In animal models injury results in medial cell apoptosis 30 minutes to six hours after injury with adventitial and neointimal apoptosis occurring later.• In humans, restenosis after angioplasty has been reported to be associated with either an increase or decrease in VSMC apoptosis, and again the role of VSMC apoptosis in either the initial injury or the remodelling process in restenosis in humans requires further study. Apoptosis of APOPTOSIS IN CVS
    40. 40. ANEURYSM FORMATION• VSMCs is increased in aortic aneurysms compared with normal aorta, associated with an increase in expression of a number of pro-apoptotic molecules.• In particular, the presence of macrophages and T lymphocytes in aneurysms suggests that inflammatory mediators released by these cells may promoteVSMC apoptosis• Moreover, the production of tissue metalloproteinases by macrophages may accelerate apoptosis by degrading the extracellular matrix from which VSMCs derive survival signals APOPTOSIS IN CVS
    41. 41. PLAQUE RUPTURE• The diminished plaque cellularity of advanced lesions may be attributed to VSMC apoptosis, and it has been proposed that VSMC apoptosis eventually contributes to plaque rupture.• VSMCs cultured from atherosclerotic atherectomy specimens proliferate more slowly and demonstrate higher frequencies of apoptosis than VSMCs from normal vessels. APOPTOSIS IN CVS
    42. 42. APoPToSIS In HumAn ATHeroScleroSISAnd reSTenoS Circulation. Isner JM, Kearney M, Bortman S, Passeri J1995;91:2703–2711. • In contrast to primary atherosclerotic lesions, where apoptosis was not a consistent finding in all specimens, almost all atherectomy specimens from restenotic lesions showed evidence of apoptosis. • Apoptosis strongly correlated with the presence of intimal hyperplasia. • In a rat model of balloon vascular injury, apoptosis primarily affected neointimal smooth muscle cells 7 to 28 days after dilation. • In contrast, Perlman et al found extensive apoptosis of medial smooth muscle cells with 70% TUNEL-positive cells as early as 0.5 to 2 hours after balloon injury. • The difference in time course between neointimal and medial smooth muscle cell apoptosis suggests that balloon vascular injury may directly induce apoptosis In medial smooth muscle cells, whereas apoptosis of neointimal smooth muscle cells may be associated with the restructuring of the neointima. APOPTOSIS IN CVS
    43. 43. • Vascular Cell Apoptosis Induced by Acute Balloon Injury• Apoptotic VSMC death has been documented in numerous animal models of acute vascular injury.• Several studies demonstrate that balloon injury of vessels induces two waves of VSMC apoptosis.• First wave is a rapid burst of apoptosis in the media occurring within hours of the injury, resulting in a marked decrease in vessel wall cellularity. (1-4hrs).• Although the consequences of early-onset apoptosis in medial VSMCs are unknown, it could exacerbate neointima lesion formation at later time points by provoking a greater wound healing response to overcome the cellular deficit. APOPTOSIS IN CVS
    44. 44. • The second wave of apoptosis occurs at much later times after injury (days to weeks) and at much lower frequencies. (confined to the VSMCs of the developing neointima).• This second wave of apoptosis may limit lesion growth.• Presumably the rates of neointimal VSMC death and proliferation are in equilibrium from 2 weeks onward, thereby preventing any further increase in lesion size. Han DKM, Haudenschild CC, Hong MK,Tinkle BT, Leon MB, Liau G. Evidence for apoptosis in human atherogenesis and in a rat vascular injury. model. Am J Pathol. 1995;147:267–277. APOPTOSIS IN CVS
    45. 45. Pollman MJ, Hall JL, Gibbons GH. Determinants of vascular smooth muscle cell apoptosis after balloon angioplasty injury. Circ Res. 1999;84:113–121.• Rapid balloon angioplasty–induced apoptosis has also been documented in the rabbit iliac model.• In this case, increased balloon-to-artery ratios produce greater frequencies of VSMC apoptosis at early time points, and this correlates with more acute cell loss.• The rapid wave of apoptosis resulting from mechanical injury appears to involve a redox-sensitive pathway, because local administration of antioxidants will minimize cell loss.• Surprisingly, VSMCs of the neointima are less sensitive to rapid-onset apoptosis than are the VSMCs of the underlying media, suggesting that modulation of the VSMC phenotype influences angioplasty-induced apoptosis. APOPTOSIS IN CVS
    46. 46. • MOLECULAR CONTROL OF APOPTOSIS AND VASCULAR CELL VIABILITY• Apoptosis of VSMCs occurs during developmentally regulated or pathological vascular remodeling and correlates with changes in Bcl-2 family protein expression.• c Bcl-XL and Bcl-2 are essential for VSMC viability.• c The Fas/FasL system is essential for the inhibition of vessel inflammation.• c Fas-mediated cell death may also play a role in atherogenesis and plaque rupture, but causal data in support of these hypotheses are lacking. APOPTOSIS IN CVS
    47. 47. reGulATIon of vASculAr SmooTH muScle cell APoPToSIS• VSMCs express death receptors, and• Inflammatory ( interleukin (IL) b (IL-1b), interferon g (IFNg) and tumour necrosis factor a (TNFa ) cells in plaque express death ligands;• Interaction between membrane bound ligands and receptors may therefore induce VSMC death.• In contrast, soluble ligand binding to death receptors is a very weak inducer of VSMC apoptosis, and does not induce apoptosis in the absence of “priming” of the cell.• Some of this resistance can be explained by intracellular location of death receptors in VSMCs, and priming may be associated with increased receptor expression.• Physiologically, combinations of cytokines increase surface death receptors, possibly via nitric oxide and p53 stabilisation. APOPTOSIS IN CVS
    48. 48. • This reflects differences in expression of pro- and anti- apoptotic molecules, regulating, cell:cell and cell:matrix interactions, and members of the bcl-2 family.• This may underlie observations that despite (apparently) the same stimulus for apoptosis, VSMC apoptosis in either normal or diseased vessels wall is highly localised.• Indeed, insulin-like growth factor 1 receptor concentrations (IGF-1R), a potent survival signalling system for normal VSMCs, are downregulated in plaque VSMCs. APOPTOSIS IN CVS
    49. 49. APoPToSIS In IScHemIc HeArT dISeASe • Saraste A, Pulkki K, Kallajoki M, Henriksen K, Parvinen M,Voipio- Pulkki LM. Apoptosis in human acute myocardial infarction. Circulation.1997;95:320• Although myocardial infarction was long considered to be characterized by nonapoptotic (“necrotic”) cell death due to the breakdown of cellular energy metabolism, there is growing evidence that myocyte loss during the acute stage of myocardial infarction involves both apoptotic and nonapoptoticcell death.• In human postmortem studies of myocardial infarction, apoptotic cardiomyocytes appeared to be predominantly localized in the hypoperfused border zone between the central infarct area and noncompromised myocardial tissue.• InterestinglyI, myocytes in the peri-infarct region were shown to upregulate the apoptotic regulatory proteins bax and bcl-2.• In addition, myocytes showing evidence of DNA degradation, chromatin condensation, and cell fragmentation were detected in human hibernating myocardium. APOPTOSIS IN CVS
    50. 50. APOPTOSIS IN CVS Apoptosis in STEMI. Myocytes at the infarct border in thisspecimen demonstrate nuclear staining by the nick-end labeling technique (arrow) suggesting that they have undergone apoptosis
    51. 51. • APOPTOSISI IN HIBERNATING MYOCARDIUM• Apoptosis is particularly prominent during the transition from chronically stunned to hibernating myocardium(loss of 30% of regional myocytes).• Vanoverschelde and coworkers have previously described light microscopic and ultrastructural characteristics of hibernating myocardium from transmural biopsies, which are characterized by small increases in interstitial connective tissue, myofibrillar loss (myolysis), increased glycogen deposition, and minimitochondria.• Some studies have demonstrated upregulation of cardioprotective mechanisms in response to repetitive reversible ischemia, which may be operative in minimizing myocyte cell death and fibrosis in the chronic setting. APOPTOSIS IN CVS
    52. 52. • An interesting mechanism potentially linking altered metabolism and protection is the regional downregulation of glycogen synthase kinase-3β , which can ameliorate cell death and also explains the increased tissue glycogen in hibernating myocardium.• In experimental studies in animals without heart failure, antiapoptotic and stress proteins such as HSP-70 have been found to be upregulated whereas increased proapoptotic proteins and a profile of progressive cell death and fibrosis have been reported in human biopsies of patients with hibernating myocardium and heart failure APOPTOSIS IN CVS
    53. 53. • Ischemia is associated with multiple alterations in the extracellular and intracellular milieu of cardiomyocytes that may act as inducers of apoptosis• A p53-mediated mechanism for myocyte apoptosis under hypoxic conditions was suggested.• The death receptor Fas is markedly upregulated in cardiomyocytes during ischemia and hypoxia, and cardiomyocytes may thus become susceptible to apoptotic cell death by interaction with FasL.• Whereas under control conditions ,1% of cardiomyocytes expressed the Fas antigen, Fas was detectable in 50% of cardiomyocytes within a few hours of ischemia and ischemia/reperfusion. Tanaka M, Ito H, Adachi S Hypoxia induces apoptosis with enhanced expression of Fas antigen. Circ Res. 1994;75:426–433 APOPTOSIS IN CVS
    54. 54. • observation in animal models of myocardia infarction suggest that apoptosis may contribute substantially to cell death even within the central infarct area with 5% to 33% of the cardiomyocytes staining positive for DNA fragmentation.• Treatment with the caspase inhibitor zVAD.fmk led to a reduction in infarct size and an improvement of acute functional parameters.• However, these measurements were obtained 24 hours after infarction, and it is not known whether the beneficial effects of zVAD.fm persists in the chronic stage APOPTOSIS IN CVS
    55. 55. REPERFUSION INJURY• The role of apoptosis in reperfusion injury has recently been addressed in rat and rabbit animal models, where reperfusion was shown to accelerate the occurrence of apoptotic cell death in cardiomyocytes.• Because the formation of reactive oxygen species has been implicated as one of the pathomechanisms for tissue injury during reperfusion, the recent finding that oxidative stress induces apoptosis in isolated neonatal rat ventricular cardiomyocytes may provide an important mechanistic link between reperfusion and tissue injury. Fliss H, Gattinger D. Apoptosis in ischemic and reperfused rat myocardium. Circ Res. 1996;79:949 –956. APOPTOSIS IN CVS
    56. 56. REMODELING• In addition, apoptotic cell death may have a role in the remodeling of noninfarcted myocardium, as evidenced in human myocardial specimens sampled within 10 days aftermyocardial infarction.• In myocardium remote from the infarcted area, 0.7% of the cardiomyocytes were apoptotic, whereas in control hearts no myocyte apoptosis was detectable.• Interestingly, apoptosis in noninfarcted regions of myocardium was inhibited by overexpression of IGF-1 in a transgenic mouse model, resulting in reduced ventricular dilation and wall stress 7 days after infarction. Li Q, Li B, Wang X, Overexpression of IGF-1 in mice protects from myocyte death after infarction, attenuating ventricular dilation, wall stress, and cardiac hypertrophy. J Clin Invest. 1997;100: . APOPTOSIS IN CVS
    57. 57. Apoptosis and Atherosclerosis Bjorkerud S, Bjorkerud B. Apoptosis is abundant in human atherosclerotic lesions,. Am J Pathol. 1996;149:367–380.• Apoptosis may prove to play an essential role in atherosclerotic alterations of the vessel wall.• In atherosclerotic lesions widespread apoptosis was detectable by TUNEL staining (up to 43% of cells in the lipid- rich core of atheromata.• A substantial number of cells undergoing apoptosis were immunoreactive with a polyclonal antiserum directed against caspase-1 and -3.• Remarkably, apoptosis did not occur in medial smooth muscle cells . APOPTOSIS IN CVS
    58. 58. Isner JM, Kearney M, Bortman S, Passeri J. Apoptosis in human atherosclerosis and restenosis. Circulation. 1995;91:2703–2711. • In contrast to primary atherosclerotic lesions, where apoptosis was not a consistent finding in all specimens, almost all atherectomy specimens from restenotic lesions showed evidence of apoptosis. • Apoptosis strongly correlated with the presence of intimal hyperplasia. • In a rat model of balloon vascular injury, apoptosis primarily affected neointimal smooth muscle cells 7 to 28 days after dilation. • In contrast, Perlman et al found extensive apoptosis of medial smooth muscle cells with 70% TUNEL-positive cells as early as 0.5 to 2 hours after balloon injury. • The difference in time course between neointimal and medial smooth muscle cell apoptosis suggests that balloon vascular injury may directly induce apoptosis In medial smooth muscle cells, whereas apoptosis of neointimal smooth muscle cells may be associated with the restructuring of the neointima. APOPTOSIS IN CVS
    59. 59. Bennett MR, Evan GI, Schwartz SM. Apoptosis of rat vascular smooth muscle cells is regulated by p53-dependent and -independent pathways.• Vascular smooth muscle cells undergo p53- Circ Res. 1995;77:266 –273. dependent apoptosis after overexpression of the positive cell cycle regulators c-myc or E1A.• Interestingly, isolated vascular smooth muscle cells from human atherosclerotic plaques were shown to have a higher propensity for both spontaneous apoptosis and apoptosis induced by overexpression of p53 compared with vascular smooth muscle cells from normal vessels. APOPTOSIS IN CVS
    60. 60. ALTERNATIVE MECHANISM• An alternative mechanism may involve the induction of apoptosis by a death receptor– dependent mechanism.• Twenty percent of Fas-positive cells showed evidence for internucleosomal DNA fragmentation with associate,morphological features of apoptosis, like chromatin condensation and nuclear fragmentation.• The cytokines(interleukin-1 and TNF-a) increase both the fraction of Fas-expressing cells to 90% of all cells and the density of Fas antigen on individual cells.• Interestingly, the combination of g-interferon, interleukin-1, and TNF-a alone already exerted a proapoptotic effect on cultured smooth muscle cells that may involve both No dependent and -independent mechanisms. APOPTOSIS IN CVS
    61. 61. • Activation of immune cells may involve oxidized low-density lipoprotein (LDL) particles, the cell surface receptor CD40, and its cognate ligand.• One major clinical implication of apoptotic cell death in atherosclerotic lesions may be a reduced plaque stability.• In addition to proteolysis, loss of smooth muscle cells in the fibrous cap of atherosclerotic lesions is known to predispose the lesions to plaque instability and therefore may increase the risk of unstable angina pectoris and acute myocardial infarction.• In this respect, it is noteworthy that the death receptor Fas is expressed on as many as two thirds of the cells in the fibrous cap in human atherosclerotic lesions. APOPTOSIS IN CVS
    62. 62. Dimmeler S, Haendeler J, Galle J, Zeiher AM. Oxidized LDL induces apoptosis of human endothelial cells :a mechanistic clue to the “response to injury” hypothesis. Circulation. 1997;95:1760 –1763• In recent studies, a potential role of oxidative mechanisms has been suggested in the apoptosis of vascular cells.• Cultured endothelial cells undergo apoptosis in response to oxidized LDL, indicating a potential role for apoptosis in the early phases of atherogenesis• Sensitivity to oxidized LDL could be reduced by nitric oxide or by calcium channel blockers.  Escargueil-Blanc I, Meilhac O. Oxidized LDLs induce massive apoptosis through a calcium- dependent pathway: Arterioscler ThrombVasc Biol. 1997;17:331–339.• In addition, apoptosis of vascular smooth muscle may at least partly be attributable to oxidant damage by hydrogen peroxide.  Li PF, Dietz R, von Harsdorf R. Differential effect of hydrogen peroxide and superoxide anion on apoptosis and proliferation of vascular smooth muscle cells. Circulation. 1997;96:3602–3609.• exposure of phosphatidylserine on the surface of apoptotic cells can promote thrombin generation. APOPTOSIS IN CVS
    63. 63. oTHer cArdIovASculAr dISeASeS• Apoptosis due to immune mechanisms may be of major importance in myocarditis and cardiac allograft rejection.• Indeed, in a rat model of heterotopic heart transplantation, Szabolcs et al found extensive apoptosis of cardiomyocytes, endothelial cells, and infiltrating leukocytes.• Infiltrating cells consisted initially of lymphocytes, whereas macrophages predominated in later stages, when apoptosis was prominent.• It is not known to which extent apoptosis is induced by cytotoxic T lymphocytes through Fas-dependent or granzyme B–dependent mechanisms. APOPTOSIS IN CVS
    64. 64. • Cardiomyocytes express a functional TNFR1 and can undergo apoptosis after stimulation with TNF-a in vitro.• Interestingly, TNF-a was shown to be produced in myocardium, although the cell type was not clearly defined.• When TNF-a was highly overexpressed under the control of a strong cardiomyocyte-specific promoter, a phenotype of dilated cardiomyopathy was induced in transgenic mice.• Likewise, in an animal model of myocarditis, TNF-a was shown to exert a major role in the pathogenesis of myocardial inflammation, although it is not clear in how far TNF-a– mediated apoptosis contributed to myocardial damage. APOPTOSIS IN CVS
    65. 65. • Excessive apoptosis of the cardiac conduction system was suggested to be a possible mechanism in the pathogenesis of heart block.• On the other hand, incomplete apoptotic cell deletion has been postulated to cause the persistence of accessory atrioventricular conduction pathways, such as in Wolff-Parkinson-White syndrome. APOPTOSIS IN CVS
    66. 66. ATrIAl fIBrIllATIon• Apoptosis (programmed cell death) is another likely contributor to the Staining of tissue sections with the TUNEL structural substrate of AF.• Both the pro- and activated forms of CASP-3 were detected in diseased myocardial samples, which N also showed stronger CASP-3 expression than controls.• Expression of the antiapoptotic BCL-2 protein was decreased in diseased atria.• Although there is no apoptosis in the goat model after 19 to 23 weeks of AF,  small numbers of apoptotic cells AF are identifiable in chronically fibrillating human atria.• These cells are likely to be lost structurally and functionally when apoptosis is complete, causing irreversible atrial damage. Aime-Sempe C,, et al. Myocardial cell death in fibrillating and dilated human right atria. J Am Coll Cardiol. 1999
    67. 67. ASSAyS for APoPToSIS• The gold standard for identification of apoptotic cells is ultrastructural evidence of chromatin condensation, the earliest characteristic morphologic feature.• However, although ultrastructural evidence of chromatin condensation is highly reliable, the routine use of electron microscopy to detect chromatin condensation is impractical because it is labor-intensive and costly.• The terminal deoxynucleotidyl transferase (TUNEL) method is the most widely used technique because the microscopic evaluation of myocardial samples is relatively easy and inexpensive .• The TUNEL method uses a molecular probe that anneals to DNA with double-stranded breaks characteristic of apoptosis (i.e., with 3′ overhangs).• The Taq polymerase method follows a similar principle. APOPTOSIS IN CVS
    68. 68. • TUNEL technique not only labels apoptotic nuclei but can also label necrotic and oncotic nuclei as well as nuclei undergoing DNA repair. Similar limitations apply to the Taq polymerase method, albeit to a lesser extent.• TUNEL staining and morphometry are laborious, and the duration of apoptotic cells being detectable by TUNEL may last only a few hours.• DNA laddering, though specific, is not quantitative and sensitive in tissue samples, where a small number of cells (1%) are undergoing apoptosis. APOPTOSIS IN CVS
    70. 70. nonInvASIve ImAGInG of APoPToSIS In cArdIovASculAr dISeASe 1. Atherosclerosis Kietselaer BL, ReutelingspergerNoninvasive detection of plaque instability with use of radiolabeled annexin A5 N Engl J Med 2004;350(14):1472–1473. [PubMed: 15070807]• Molecular imaging of atherosclerosis is an area of intense research.• One area of extensive investigation utilizes 99mTc-radiolabeled annexin V for SPECT imaging.• Using annexin V-enhanced micro-SPECT combined with subsequent micro-CT, murine atheroma models demonstrated excellent correlation between noninvasive and histopathological assessment of macrophage infiltration and the extent of apoptosis APOPTOSIS IN CVS
    71. 71. • Radiolabeled annexin V has also demonstrated applicability to clinical imaging of apoptosis in carotid atherosclerosis. • In a pilot clinical study, 99mTc SPECT imaging demonstrated higher uptake in carotid artery plaques of patients with recent TIA or stroke symptoms compared to patients with remote symptoms. • Resected endarterectomy specimens validated this difference, showing significantly greater immunoreactive annexin V staining of histological sections . • Ultimately, clinical noninvasive imaging of apoptosis within atherosclerosis might provide not only a risk assessment at a single time point, but also be able to assess the effectiveness of local or systemic therapies that stabilize plaques and reduce coronary risk.Noninvasive imaging of atherosclerotic lesions in apolipoprotein E-deficient and low- densitylipoprotein receptor-deficient mice with annexin A5. J Nucl Med 2006; APOPTOSIS IN CVS
    72. 72. • TO this end, Hartung and colleagues randomized balloon injured rabbits to high cholesterol diet (HCD), HCD for three months followed by one month of standard chow, and HCD for three months followed by HCD with statin treatment.• Noninvasive imaging using radiolabeled annexin V demonstrated maximum signal in untreated HCD animals, with significantly less signal in the HCD withdrawal and statin-treated groups [25]. APOPTOSIS IN CVS
    73. 73. 2.myocArdIAl IScHemIA/rePerfuSIon Injury Dumont EA, Reutelingsperger CP,Real-time imaging of apoptotic cell-membrane changes at the single-cell level in the beating murine heart. Nat Med 2001;7(12):1352–1355.• Real -time intravital microscopy of fluorescently conjugated annexin V to individual myocytes following ischemia-reperfusion injury showed detailed study of the kinetics of apoptosis in the ischemia-reperfusion injury.• Apoptosis imaging has shed light on the spatial and temporal evolution of apoptosis in models of ischemia-reperfusion injury.• In a rat model of ischemia-reperfusion injury, autoradiography of resected hearts following 99mTcradiolabeled annexin V administration revealed that the zone of apoptosis initially begins in the mid-myocardium 30 min after reperfusion, extends into the subendocardium and subepicardium 6 h after reperfusion, and then eventually regresses over 3 days . APOPTOSIS IN CVS
    74. 74. moleculAr mr ImAGeS• Molecular MR images can be correlated with MR images of myocardial function, contractility, strain, perfusion and viability in a single integrated dataset.• In a recent highresolution, noninvasive MR imaging approach, a novel annexinV- based magnetofluorescent iron oxide nanoparticle was used to quantitatively image myocardial apoptosis .• Cine MRI of the mouse heart allowed the molecular image of cardiomyocyte apoptosis to be correlated with global left ventricular function as well as regional myocardial contractility• The distribution of the magnetofluorescent annexin suggested a midmyocardial predominance of the agent, in accordance with prior observations by other investigators Taki J, Higuchi T, Kawashima A, Tait JF, Kinuya S . Detection of cardiomyocyte death in a rat model of ischemia and reperfusion using 99mTc-labeled annexin V. J Nucl Med 2004;45(9):1536–1541
    75. 75. Magnetic resonance imaging of cardiomyocyte apoptosis with a novel magneto-optical nanoparticle. Magn Reson Med 2005• The dual modality nature of the probe allowed the in vivo MRI findings to be confirmed by ex vivo fluorescent imaging .• The results of this study show that high-resolution serial quantitative imaging of cardiomyocyte apoptosis can be performed in vivo by MRI.• In addition the molecular MR image could be integrated with MR images of myocardial function in a single integrated dataset.• Further integration of molecular MR images of cardiomyocyte apoptosis with MR images of myocardial perfusion and viability would be highly feasible and demonstrate the breadth and flexibility of a molecular MR approach to apoptosis imaging.• The utility of this agent in vivo, however, remains to be determined APOPTOSIS IN CVS
    76. 76. APOPTOSIS IN CVS ScInTIGrAPHIc ImAGInG AGenTS• SPECT imaging of radiolabeled 99mTc annexin V at two time points post-infarction; images showed increased uptake in infarcted areas with a matching perfusion defect• Noninvasively imaging the extent of apoptosis resulting from acute coronary syndromes could be an important tool to help guide 1. Revascularization strategies, 2. Optimize heart failure therapies, and 3. Identify patients for emerging anti-apoptotic specific agents, 4. Preventing left ventricular dysfunction, 5. Monitoring ventricular remodeling following injury,and 6. Identifying patients at high risk for future cardiac events.Visualisation of cell death in vivo in patients with acute myocardial infarction. Lancet 2000
    77. 77. APOPTOSIS IN CVSImaging of cardiomyocyte apoptosis in acute myocardial infarction with 99mTc-annexin V. Combination of acute 99mTc-MIBI and 99mTc annexin V. 99mTc-MIBI perfusiondefects in anteroseptal and apical region (open arrows) correlate well with 99mTc-annexin V activity (grey arrows).
    78. 78. 3.HeArT fAIlure And myocArdITIS• One model utilizes mice genetically engineered to overexpress Gαq, a subunit of the cell-surface receptors involved in promoting cardiac myocyte hypertrophy (α1-adrenergic receptor, angiotensin II type 1 receptor, and endothelin-1 receptor.• the magnetofluorescent nanoparticle AnxCLIO-Cy5.5 has been used to image apoptosis in vivo in postpartum Gaq overexpressing mice by MRI .• The ability to successfully image apoptosis in this model of heart failure shows that AnxCLIO-Cy5.5 crosses an intact capillary membrane, penetrates the interstitium of the myocardium, and detects relatively low levels of apoptosis in vivo.Inhibition of cardiac myocyte apoptosis improves cardiac function and abolishes mortality in theperipartum cardiomyopathy of Galpha(q) transgenic mice. Circulation 2003;108(24):3036–3041 APOPTOSIS IN CVS
    79. 79. 4.AcuTe HeArT fAIlure• Recently, a rat model with systemic inflammatory response syndrome was used to demonstrate cardiomyocyte apoptosis by uptake of radioiodinated annexin V .• In a rat model of subacute catecholamine-induced myocarditis, 99mTc-labeled annexin V showed increased uptake compared to control animals and showed a strong correlation with imuunohistochemical evidence of apoptosis . Annexin V detection of lipopolysaccharide-induced cardiac apoptosis. Shock 2007;27(1):69–74. APOPTOSIS IN CVS
    80. 80. CLINICAL APPLICATIONS• This finding lays the groundwork for clinical imaging of apoptosis in myocarditis, a technique that would offer great benefit in 1. confirming the diagnosis of myocarditis, 2. determining the extent of involvement, 3. selecting patients for anti-apoptotic therapies, and 4. potentially identifying patientswith a heavy disease burden that may benefit from ventricular-assist devices as a bridge to recovery or transplant. APOPTOSIS IN CVS
    81. 81. 5.cHemoTHerAPeuTIc-relATed cArdIoToxIcITy Yeh ET, Tong AT, Lenihan DJ, Yusuf SW, AA, Ewer MS. Cardiovascular complications of cancer therapy: diagnosis management. Circulation 2004;109(25):3122–3131.• Chemotherapeutic-related cardiotoxicity remains a significant clinical problem, and there is an unmet need to identify susceptible patients .• Current clinical approaches utilize serial determinations of left ventricular ejection fraction to identify cardiotoxicity.• In a rat model of doxorubicin cardiotoxicity, radiolabeled annexin V was able to detect high levels of cardiomyocyte apoptosis .• Ultimately, this approach could serve as a more sensitive early marker of anthracylicne toxicity than studies based on macroscopic left ventricular dysfunction, providing the opportunity to modify or stop administration of the agent before clinically overt heart failure. APOPTOSIS IN CVS
    82. 82. 6.cArdIAc TrAnSPlAnT rejecTIon Annexin-V imaging for noninvasive detection of cardiac allograft rejection. Nat Med 2001;7 (12):1347–1352.• Current monitoring of cardiac allograft rejection relies heavily on endomyocardial biopsy, an invasive procedure with attendant risks.• Allograft rejection is characterized by varying degrees of inflammation with associated necrosis and apoptosis.• Apoptosis imaging therefore has the potential to noninvasively identify patients with transplant rejection and monitor response to immune modulation therapy.• Early efforts with a rat model of cardiac allograft rejection showed increased uptake of 99mTc annexin V that correlated well with histologic evidence of apoptosis associated with a mononuclear inflammatory infiltrate. APOPTOSIS IN CVS
    83. 83. • In a separate study of 10 transplant recipients using radiolabeled annexin V, two patients with moderate acute rejection by biopsy were correctly identified by SPECT imaging; however,specificity in this study was suboptimal with half of the patients with grade IA rejection or less having two foci of uptake on imaging .• With further refinements, these encouraging clinical efforts may reduce the need for routine surveillance endomyocardial biopsy in transplant recipients. In vivo imaging of acute cardiac rejection in human patients using (99 m)technetium labeled annexin V. Am J Transplant 2001;1(3):270–277 APOPTOSIS IN CVS
    84. 84. Diffuse myocardial uptake of 99mTc-annexin V in cardiac allograft rejection. SPECT imaging 3 h after intravenous injection of radiolabeled annexin V demonstrated diffuse myocardialuptake of radiotracer, suggesting extensive apoptosis in the myocardium and transplant
    85. 85. fuTure of ImAGInG• Whereas current clinical practice focuses on cardiac biomarkers that reflect cardiomyocyte lysis well after the damage is complete, apoptosis imaging provides a window onto areas with ongoing cellular damage that presages functional and structural impairment. APOPTOSIS IN CVS
    86. 86. THerAPeuTIc oPTIonS for APoPToSIS• Apoptosis can be interrupted at many points in the signalling pathway.• Prevention of apoptotic myocyte death may be directed at (1) inhibiting/preventing the stimulus, (2) inhibiting the regulatory mechanisms determining the decision to die, or (3) inhibiting the pathways executing apoptosis.• Clearly, many signalling pathways are activated in ischaemia and heart failure.• Interruption of a single pathway may therefore not inhibit apoptosis if there are multiple, redundant pathways inducing apoptosis. APOPTOSIS IN CVS
    87. 87. INHIBITING/PREVENTING THE PRO-APOPTOTIC STIMULUS.• The beneficial effects of B-blockers in chronic heart failure and ischaemic heart disease may counteract the pro- apoptotic effect of excess catecholamines.• Indeed, carvedilol can inhibit ischaemia/reperfusion induced myocyte apoptosis, and• Angiotensin converting enzyme inhibitors may protect against angiotensin II induced apoptosis. APOPTOSIS IN CVS
    88. 88. PROTECTION AGAINST APOPTOSIS• Many molecules protect cells from apoptosis, including 1. Anti-apoptotic Bcl-2 family members, 2. IAPs, and 3. Decoys for death receptors.• Although these agents inhibit apoptosis mediated by many stimuli, and may therefore be clinically useful, at present they cannot be selectively expressed without gene transfer into the heart, with all its inherent problems.• More promising is the potential administration of soluble survival factors following the apoptotic stimulus. APOPTOSIS IN CVS
    89. 89. • Many growth factors, including IGF-1, cardiotrophin-1, and the neuregulins, inhibit apoptosis following ischaemia, serum withdrawal, myocyte stretch, and cytotoxic drugs.• OVEREXPRESSION OF IGF-1 reduces apoptosis in non-infarcted remote zones and promotes favourable remodelling postmyocardial infarction. (AKT pathway)• Activation of the CARDIOTROPHIN-1 receptor also inhibits cardiac dilatation following aortic banding, suggesting that reduced cardiomyocyte apoptosis can be translated into improved function. (ERK pathways) APOPTOSIS IN CVS
    90. 90. HEART FAILURE• Heart failure is characterised by increased plasma concentrations of catecholamines and TNFa.• The beneficial effects of b blockers in heart failure may therefore be achieved by prevention of myocyte apoptosis.• Licensed inhibitors of TNFa are now available, although recent randomised controlled trials (RENAISSANCE and RECOVER) suggest that a soluble TNF receptor antagonist (etanercept) does not benefit patients with heart failure.• In contrast, evidence identifying the type 2 angiotensin II receptor as inducing apoptosis in models of heart failure has suggested that its inhibition may be beneficial. APOPTOSIS IN CVS
    91. 91. PREVENTING EXECUTION OF APOPTOSIS• Augmentation of endogenous inhibitors of caspases, such as the IAPs, could therefore inhibit apoptosis induced by many stimuli.• Pharmacological inhibition of caspases using cell permeable analogues of cleavage sites can inhibit myocyte apoptosis over the short term.• However, their long term benefits are unknown, as cells that are destined to die may do so anyway, and delaying apoptosis may not provide long term benefit. APOPTOSIS IN CVS
    92. 92. APOPTOSIS IN CVS
    93. 93. APoPToSIS And STATInS• Conclusions•  The present results suggest that protein prenyl-ation inhibition by statins may be involved in statin-induced VSMC apoptosis.• These data provide a new potential mechanism by which statins may modulate the evolution of atherosclerotic lesions.
    94. 94. APOPTOSIS IN CVS
    95. 95. • ACE inhibitor decreases the degradation of bradykinin, (B2receptor-dependent pathway) which may have an important role in the antiapoptotic effect of the ACE inhibitor.• ACE inhibitors reduce myocardial apoptosis, as indicated by a – reduction in TUNEL-positive myocytes, – suppression of DNA ladder formation, and – attenuation of caspase-3 activation – preservation of the Bcl-xL protein by ACE inhibition may have a role in the decrease in myocardial apoptosis. These findings may have important clinical implications in cardioprotective treatment with ACE inhibition APOPTOSIS IN CVS
    96. 96. ACEI AND APOPTOSIS• Long -term treatment with theACE inhibitor enalapril in dogs with moderate HF attenuates cardiocyte apoptosis as evidenced by reduced cardiomyocyte nDNAf events in viable myocardial regions that border scar tissue (old infarcts).• The attenuation of cardiomyocyte apoptosis with ACE inhibition therapy was associated with prevention of progressive LV dysfunction and attenuation of LV chamber remodeling.• Reduction of ongoing loss of functional cardiac units in HF through apoptosis may be one mechanism by which ACE inhibitors preserve LV function and attenuate the progression of LV chamber remodeling in the failing heart.
    97. 97. EFFECT OF VASOPEPTIDASE INHIBITOR, OMAPATRILAT ON CARDIOMYOCYTE APOPTOSIS AND LV REMODELLING.• In this study, both omapatrilat and captopril decreased apoptosis in the border zone of the infarct but also to a lesser extent in the remote non- inhibition infarcted area.• In contrast, selective NEP inhibition did not affect the number of apoptotic cells.• AT II has been earlier Cellular basis of chronic ventricular remodeling after myocardial infarction in rats but the precise mechanism is unknown. APOPTOSIS IN CVS
    98. 98. APOPTOSIS IN CVS Omapatrilat and captopril reduced fibrosis as measured 4 weeks after MIThe amount of cardiomyocyte apoptosis in the border and remote zones of the LV 4 weeks after operation
    99. 99. APOPTOSIS IN CVS  The VPI omapatrilat, with its combination of NEP and ACE inhibition,suppresses cardiomyocyte apoptosis post-MI and in neonatal cultured ratcardiomyocytes more than the ACEI captopril, but this does not result in significant hemodynamic or morphologic differences between omapatrilat and captopril
    100. 100. APOPTOSIS AND ARB• Blockade of angiotensin II type 1 receptor (AT1) signaling attenuates heart failure following myocardial infarction (MI), perhaps through reduction of fibrosis in the noninfarcted myocardium• Ten days post-MI, apoptosis among granulation tissue cells was significantly suppressed in the olmesartan-treated heart.• olmesartan dose-dependently inhibited Fas-mediated apoptosis in granulation tissue-derived myofibroblastss APOPTOSIS IN CVS
    101. 101. • Metabolically active agents such as glucose-insulin- potassium, trimetazidine and ranolazine that protect from ischemia, increase glucose metabolism relative to that of fatty acids.• By promoting glycolysis they tend to close the ATP- dependent potassium channels that help to mediate preconditioning.• By lessening the oxygen-wasting effects of fatty acids, they are mitochondrial protective and oxygen-sparing.• These qualities should help in the therapy of myocardial ischemia and also heart failure. APOPTOSIS IN CVS
    102. 102. RANOLAZINE• Agents that reduce the harmful effects of reactive oxygen may protect the heart against ischemia-reperfusion damage.• In fact, antioxidants have been demonstrated to attenuate both lipid peroxidation and myocardial damage in the ischemia-reperfused heart• Ranolazine reduce H2O2-induced derangements may contribute to its cardioprotective effect against ischemia- reperfusion damage. APOPTOSIS IN CVS
    103. 103. • The contribution of the ubiquitin– proteasome system is the formation and growth of the lipid core through inflammation,apoptosis,cell proliferation.• Inhibitors of U-P system may help prevent atherosclerosis. APOPTOSIS IN CVS
    104. 104. decreASed APoPToSIS followInG SucceSSful ABlATIon of ATrIAl fIBrIllATIon.• Twenty-five patients with AF were prospectively studied.• The success of the ablation was assessed clinically and with 3 Holter recordings.• Blood samples were drawn before surgery, and at 3 and 6 months after.• Serum concentrations of Fas ,TRAIL were measured using ELISA.• The ablation of AF is associated with decreased serum markers for apoptosis. APOPTOSIS IN CVS
    105. 105. cAlPAIn InHIBITor In A cAnIne rAPId ATrIAl fIBrIllATIon model.• The calpain is a  calcium-dependent, non lysosomalcysteine  proteases (proteolytic enzyme.) • Activation of of calpain participate in the structural remodeling of left atrial cardiac muscle and contractile dysfunction.• Calpain inhibitor suppresses the increased calpain activity and reverses the structural remodeling of sustained atrial fibrillation.• Calpain inhibition may therefore provide a possibility for therapeutic intervention in AF.• The calpain inhibitor N-Acetyl-Leu-Leu-Met attenuated apoptosis through a complicated network of apoptosis-related proteins, which may result in improvement of structural remodeling in atrial fibrillation. APOPTOSIS IN CVS
    106. 106. APOPTOSIS IN CVS
    107. 107. APOPTOSIS IN CVSOcimum sanctum,withania somnifera,curcuma longa
    108. 108. SeT BAckS of APoPToSIS• It is important to determine whether apoptosis is one of the early causes rather than a terminal event that is associated with the end stage of these disease entities.• The true incidence of apoptosis is not clear.• The initiating stimuli of apoptosis in myocardial and vascular cells at the cellular level are not well understood• With respect to the clinical situation,the role of apoptosis as a prognostic marker deserves further study. APOPTOSIS IN CVS
    109. 109. • Although pharmacological caspase inhibition prevents myocyte apoptosis induced by ischemia and reperfusion in short-term experiments, the ultimate fate of the cells is not clear.• It is not known whether ischemic myocytes that have initiated the apoptosis pathway and are acutely rescued by caspase inhibition will eventually survive or whether the drug simply delays cell death. APOPTOSIS IN CVS
    110. 110. concluSIonS• Taken together, apoptosis increasingly penetrates the field of cardiovascular research. Several exciting hypotheses need to be tested to determine whether the opportunities offered in the modulation of apoptotic cell death will finally translate into new treatment approaches for cardiovascular disease. APOPTOSIS IN CVS