G ENERAL ETIOPATHOGENESIS OF DISEASES

1. GENERAL ETIOPATHOGENESIS OF DISEASES Prof. J. Hanacek, M.D.,CSc.

2. Etiopathogenesis •etiology – causes and conditions of diseases onset •genesis – development of disease Pathomechanisms •Mechanisms which are involved in development of diseases

3. Monofactorial diseases •One „big“ cause plus appropriate conditions are necessary, e.g. tuberculosis (other infections) Multifactorial diseases •More than one cause and appropriate conditions are necessary, e.g. atherosclerosis Homogenous diseases – diseases induced always by the same cause or complex of causes, e.g.whooping cough, small pox, poissoning by toadstool Heterogenous diseases – diseases induced by different kinds of noxae or differentcomplex of noxae, e.g. diabetes mellitus type 1 and 2; hypoxia-hypoxic, histotoxic, ischemic He

4. Pathogenic factors Different kinds of energy (inappropriate quantity and/or quality) which lead to disturbances of homeostasis of iner environement of human body. Another name for pathogenetic factors are noxae

5. Main kinds of pathogenetic noxae • physical-mechanical energy, enviromental temperature, electric • current, atmospheric pressure and moisture, lasser beam, • compression and decompresion, vibration, acceleration, • deceleration, microwaves, magnetic field and others 2. chemical– elements and compounds - acids and lyes, plantand animal toxins, toxic metals, cigarette smokeandother kinds of smoke, sulphur dioxide, nitrogene oxides, ozon, pesticides,herbicides... 3. biological– microorganisms(microbes,viruses..), insect and arthropods, organic dust andpollen 4.psychological, social and ergonomic- psychologic stress, enormous strain(physical or/and mental)

6. Physical noxae: Crush syndrome • Syndrome is characterized by tissue damage induced by their compression • -  cells are damaged by pressure and ischemia • anaerobic metabolism going on release of myoglobin from cells • precipitation of Mgl in kidney vessels damage of kidney • acute renal failure After compression is removed: -  recirculation in the damaged tissue can occure after removing the compression - washing out the toxic metabolites from the damagedtissue to the whole organism toxic influence -  accumulation of the blood in the damaged tissue(blood goes very easy through the leaky capillary wall) -  hypovolemia and hypovolemic shock can occur

7. Blast syndrome Syndrome is characterized by tissue damage induced by strong pressure wave: Consequences: - bleeding to the tympanic membrane(ear drum) and/or rupture - damage of the inner ear - damage of hollow organs(e.g. stomach, intestines) - rupture of alveoli and pulmonarycapillary - commotio cerebri

8. Decompression sickness (caisson disease) Who is in risk?– underwater construction workers – deep sea divers – unpressurised aircraf fly Mechanisms:– return too quickly from deep level of sea to the surface causes a form of gas embolism – CO2 and N which are normally disolved in the blood come out and forme tiny bubbles gas emboli Consequences: – nitrogen bubbles may obturate microvessels in tissue and persist there – larger bubbles in larger vessels obstruct their lumenischemia in muscles, joints, tendons   pain, necrosis

9. Ionizing radiation (IR) IR– any form of radiation capable of removing orbital electrons from atoms  ions Sorces of IR: – x-rays, γrays, and particles, neutrons, protons, sunlight The most abundant source of exposure to IR is: – the environment – e.g. cosmic rays, buildings and soil radiation materials – diagnostic and treatment procedurese.g. CT scans may be responsible for 24% of the total „backround“ radiation to which the population is exposed in the given year (Sin et al., 2011)

10. The mechanisms by which IR damages the cells •Direct damage– influence of vulnerable molecules in the cell •Indirect damage– radiolysis of water  radicals Consequences: – damage of DNA, genes, chromosoms  •damage of somatic cells  necrosis, apoptosis, cancer • damage of gamete  genetic (inherited) diseases • damage of fetus  spontaneous abortus, increased perinatal mortality

11. Prolonged and strong vibration Main sorces:- vibrating machinery, e.g. track and bus drivers, construction workers, farmers... Whole-body vibration (resonance)- begins at 5Hz Consequences: -  oxygen consumption in tissues -  pulmonary ventilation - development of bone deformities - calcification of intervertebral discs -  incidence of bowel, blood, respiratory and musculosceletal disorders Segmental vibration– often the fingers and hands are damaged People in  risk:- operators of chain saws, pneumatic hammer, rotary grinders

12. Cosequences: - Raynaud´s phenomenon Characteristics:- numbness and white fingers - some loss of fine movements due to muscular control disorders - decreased sensitivity to heat and cold Noise –it is a sound that has potential for inflicting bodily harm (usually more than 50dB) Consequences: – hearing impairment It can be due to:- acute loud noise - cumulative effect of various intensities, frequences and durations of noise

13. • Acoustic trauma– rupture of eardrum, – displace of ossicles of the middle ear, – damage of organ of Corti in the inner ear • Noise-induced hearing loss – is gradual due to prolonged exposure to intense sounds Mechanism:– vasoconstriction of small vessels in cochlea   oxygen dilivery to hair cells  hypoxic damage • Neurosis  different kinds of psychosomatic disorders

14. Acceleration–deceleration:sudden and quick changes in movement directions of the body in the space Consequences: - negative influence on CVS - negative influence on vestibular system Kinetosis (motion sickness) – yourmindperceiving a movement that doesn't agree with what your sense of balance is telling you – manifestation of vestibular system dysfunction – dysfunction is manifested by „stormy“ reaction of vegetative nerve system  dysbalance sympathetic and parasympathetic nerve systems Main symptoms: - abdominal pain, nausea, dizziness Main signs: - tachycardia, decrese of BP, vomiting

15. Damages induced by electricity Alternate electric current is dangerous for living organisms, only when its parameters are: - more than 50 V, more than 75 mA • Consequences: • - thermic damage  burns • depolarisation of the cells  nerv system and heart dysfunctions • - mechanical damage  dysruption of skin and muscles • Mechanisms: • thermic damage – due to resistance heat creation • depolarisation – due to depolarisation of the cell membranes by • high voltage current  asystolia, ventricular • fibrilation, muscle cramps

16. Chemical noxas 1. Exogenous a/ Inorganic – elements: As, Hg, Pb.... compouds: SO2, NOx, organophosphates... b/ Organic– organic acids, amonium... – plant and animal toxins 2. Endogenous – NH3, uric acid, keton bodies... The effect of chemical noxas on cells depends on: - dose exposed to - place of entry to the body - speed of entry - duration of exposition - properties of noxa - properties of tissue/cells - capacity of detoxification systems

17. Main mechanisms involved in injury by chemicals • Damage of cell structures • a/ cytoplasmatic – by heavy metals, alcohols, acids... • b/ membranes – by organic solvents, azbest... • Disturbancies in synthesis of macromolecules • e.g. ribonukleotides by alfa-amanitin (from toadstool-green) • Damage of transport membrane mechanisms • e.g. by bees and snaky venoms • Damage of energetic metabolism of the cells • e.g. glycolytic process damaged by fluorids or • oxidative phosphorylation by cyanide • Cell division –e.g. by cytostatics • 6. DNA– e.g. mutagens

18. Main consequences of chemical injury A/ Inactivation or/and denaturation of cell enzymes B/ Creation of inactive complexes by interaction of noxa with important cell molecules: e.g. cyanide +Fe3+ inactive complex  impairment of oxidative phosphorylation, ihibition of cytochrome oxydase a3  ihibition of tissue “breathing“ e.g. arsenic +pyruvatedehydrogenase  inactive complex: - if it is in the heart  there is alternative way for energy creation  no heart damage - if it is in nerves  there is not alternative way for energy production  blockade of energy creation  damage of the nerve system

19. C/ Damage of conjugation process - toxic chemicals can't be conjugated and excrete from the body D/ Lethal synthesis– due to „mistake“ of detoxication proces  creation of very toxic product E/ Binding of chemicals on important molecules e.g. CO on Hb Stages of cell injury by chemicals • cytopathic effect – the functions of the cell is changed/inhibited but it is able to live and can proliferate •  cytostatic effect– cell is still alive but it lost the ability to proliferate •  cytotoxic effect – cell death

20. Intoxication by organophoshates Organophosphates: - chemical compounds used as insecticides and herbicides (e.g. Fosdrin, Intrathion) Entry to the body:- skin, conjunctives, mucose membranes of respiratory and GIT systems Detoxified in:- liver, kidney Main effects of organophoshates: – inhibition of ACH-esterases Consequences:-concentration of ACH in synaptic cleft  stimulation of postganglionic cholinergic nerve fibres Manifestations:- muscarinic effect:nausea, vomiting, abdominal pain, diarhoe, sweating, miosis, overproduction of mucus in the airway - nicotinic effect:tremor, muscle twitches, cramps - stimulation of sympathetic NS: BP, HR - stimulation of CNS: cramps, coma

21. Entry of noxae to the organism Noxae can entry to the organism through: -  skin -  mucous membranes of :respiratory tract gastrointestinal tract-CNS(psychogenic predominantly) Predilection places- places in the organism throughwhich the noxae can enter the organism more easy then through other ones

22. Spreading of noxae in the organism 1.hematogenous way 2.  lymphatic way 3.  along nerves 4.  canalicular way 5.  per continuitatem

23. Types of interaction between causes of disease and disease itself

25. Disturbances autoregulation of body functions - their importance for pathogenesis • Autoregulation - Autoregulation is a process within many biological • systems, resulting from some internal adaptive • mechanism that works to adjust (or mitigate) • the systems response to stimuli • - processes which are responsible for maintaining • homeostasis • Mechanisms of autoregulation- they are present and active at different • level of the bodystructures: • autoregulation at the level of subcellular structures • - gen regulation (cell „tels“ to DNA what the cell needs, the DNA to produce) • -enzymatic reactions, cell division, cell death, e.g. by apoptosis • b) supracellular control mechanisms- by releasingdifferent kind of cytokines,hormons by which the communication cell to cell is performed • – e.g. control number of cells in tissues

26. c) autoregulation at the level of organs and systemsof the body – neuraland endocrine (humoral) mechanisms (feed-back loops) – result is co-ordinating function of organs and systems •Homeostatic curve- it shows autoregulative capacity of the body organs,systems and whole organism (see scheme) •Dysregulative pathophysiology - deals with the pathomechanisms in which thedisturbance of autoregulation mechanisms are primary cause of disease, e.g. endocrineglands dysfunction, malignant processes

27. HOMEOSTATIC CURVE y A B C x y = the level of living processes x = external (internal) damaging factors

28. • Endogenous amplifying system of cell (EAS) - the system which amplify the signal coming tothe cell many times (107 - 108) •Disturbance of EAS a)  activity of EAS is decreased b)  activity of EAS is increased Decreasing activity of EAS e.g. enzymatic defect or decreased activity of cell enzymes due to changed cell environment (acidosis)  cell function Increased activity of EAS e.g. increased activity of cell enzymes  cell activity (body temperature)

29. Examples: •Dysregulation of calcium level in a cell [ Ca++] in cell activation of cell proteases,lipases cell proteins and membrane proteins damage cell death • Dysregulation of apoptosis apoptosis  number of cells apoptosis  number of cells ●Dysregulation of feed-back mechanisms Norm: blood glucose levelinsulin production  blood glucose level insulin production Pathol: blood glucose levelinsulin production insulin resistance  another insulin production  development glucose tolerance

30. •Dysregulative diseases Examples • Disturbances of breathing control • (e.g. central sleep apnoea sy., Pikwick sy.) • Disturbances of blood pressure control • (essential hypertension) • Diabetes mellitus type 2 • - Hypo- or hyperthyreosis, alergy, immunodeficiency, • hyporeactivity,hyperreactivity of airway,...

31. •Antagonistic regulation of body functions - repolarization of cell depolarisation - stimulationinhibition - proteasesantiproteases - oxidants antioxidants - stressantistress • sympathetic nerve parasympathetic nerve • system activitysystem activity Under normal condition there is dynamic balance between antagonistic functions in the human body homeostasis

32. Antagonistic regulation of body functions Example: it is the existence of two opposing systems (A and neg – A) activated by a common signal and controling a single target system Single target system-final reaction Vasoconstriction-Vasodilation Muscle vessels Skin vessels System A System -A Common signal Catecholamins Stressor

33. Apoptosis in the pathogenesis of disease •In multicellular organisms, homeostasis is maintained through a balance between cellproliferation and cell death • Different cell types vary widely in the mechanisms by which they maintainthemselves over the life of the organism: • •   blood cells - constant renewal • •   cell of reproductive system • - cyclical expansion andcontraction • neural cells - limited capacity for self- renewal Control of cell number is determined by balance between cell proliferation and cell death

34. Fig. 2 The effect of different rates of cell death on homeostasis In mature organisms, cell number is controlled as a result of the net effects of cell proliferation and cell death. Here, the rates of cell proliferation and cell death are indicated by the size of the arrows. In the absence of compensatory changes in the rate of cell proliferation, changes in the rate of cell death can result in either cell accumulation or cell loss

35. Regulation of cell death is just as complex as the • regulation of cell proliferation: • The cells appear to share the ability to curry out their own death • throughactivation of an internally encoded "suicide program". • When activated,characteristic form of cell death is initiated. • -This form of cell death is called apoptosis •Apoptosis can be triggered by a variety of extrinsic and intrinsic signals Theresult is: - elimination of cells: •   produced in excess •   developed improperly - have sustained genetic damage • damaged cells

36. Inducers of Apoptosis Damage-related Inducers 1.Heat shock 2. Viral infection 3. Bacterial toxins 4. Oncogenesmyc, rel, E1A 5. Tumor suppressors p53 6. Cytolytic T cells 7. Oxidants 8. Free radicals 9. Nutrient deprivation- antimetabolites Physiologic activators 1.TNF family 2. Transforming growth factor  3. Neurotransmitters -Glutamate -Dopamine -N- methyl-D-aspartate 4. Growth factor withdrawal 5. Loss of matrix attachment 6. Calcium 7. Glucocorticoids

37. Inducers of Apoptosis Therapy-associated 1.Chemotherapeuticdrugs - cisplatina, doxorubicin bleomycin, cytosine arabinoside, nitrogen mustard, metho- trexate, vincristine 2. Gamma radiation 3. UV radiation Toxins 1. Ethanol 2. -amyloid peptide

38. Diseases Associated with Increased Apoptosis 1.AIDS 2.Neurodegenerative disorders Alzheimer's disease Parkinson's disease Amyotrophic lateral sclerosis Retinitis pigmentosa Cerebellar degeneration 3.Myelodysplastic syndromes Aplastic anemia 4.Ischemic injury Myocardial infarction Stroke Reperfusion injury 5.Toxin-induced liver disease Alcohol

39. Neurodegenerative disease • Due to genetic disorders: mutated gene  repeat CAG nucleotid triplet  • (encodes glutamín) • a)  polyglutamine tract  creation of glutamine residues  toxic • properties of them  polyglutamine disease • b)  alpha – synuclein (amyloid precursor protein – in Alzheimer disease) • Autoregulative pathways in removing of pathologic proteins: •  Proteosome enzymes +ubiquitin  cleaving of irregular protein •  Autophagy-lysosome pathway = a form of programmed cell death • - macroautophagy – involved within nutrient recycling of macromolecules • under condition of starvation • - chaperon-mediated autophagy • If these processes are ineffective  accumulation of toxic protein in cells

40. •Although diverse signals can induce apoptosis in a wide variety of cell types, a number of evolutionary conserved genes regulate a final common cell death pathway that isconserved from worms to humans •Apoptotic cell death can be distinguished from necrotic cell death ●Necrotic cell death =pathologic form of cell death resulting from acute cellular injury,which is typified byrapid cell swelling and lysis,accompaniedbyinflammatory reaction

41. A hypothetical model for the regulation of apoptotic cell death Growth factor withdrawal Activation of death receptors Cytotoxic T cells Endonuclease activation Protease activation Cell surface alterations Central cell death signal Phagocytosis BCL 2 P 53 Metabolic or cell cycle perturbations Cytoskeletal reorganisation DNA damage

42. •Apoptotic cell death = physiologic form of cell death characterized by controlledautodigestionof the cell. No inflammatory reaction is present • Cells appears to initiate their own apoptotic death through the • activation ofendogenous proteasescytoskeletal disruption, • cell shrinkage, membraneblebbing • The nucleus undergoes condensationas endonucleases are • activated  degradation of nuclearDNA • -  Loss of mitochondrial function • Phagocytosis • Cells not immediately phagocytosed break down into smaller • membrane – boundfragments called apoptotic bodies

43. •  Recent evidence suggests that the failure of cells to undergo apoptotic cell death might beinvolved in the pathogenesis of a variety of human diseases •  Wide number of diseases characterized by cell loss, may result from accelerated rates ofphysiologic cell death •So, talking about pathogenesis of different kind of diseases we have to take into account the changed apoptosis for explanation of some pathological processes

44. Fig. 6 Inhibitors of Apoptosis • Viral genes • Adenovirus E1B • 2. Baculovirus p35 • 3. Baculovirus IAP • 4. Cowpox virus crmA • 5. Epstein-Barr virus BHRF1, LMP-1 • 6. African swine fever virus LMW5-HL • 7. Herpesvirus 34.5 Physiologic Inhibitors 1. Growth factors 2. Extracellular matrix 3. CD40 ligand 4. Neutral amino acids 5. Zinc 6. Estrogen 7. Androgens • Pharmacological agents • Calpain inhibitors • Cysteine protease inhibitors • 3. Tumor promoters • - PMA Phenobarbital • - Hexachlorocydohexane

45. Fig. 5 Diseases Associated with the Inhibition of apoptosis 1.Cancer Follicular lymphomas Carcinomas with p53 mutations - Hormone-dependent tumors - Breast cancer - Prostate cancer - Ovarian cancer 2.Autoimmune disorders Systemic lupus erythematosus Immune-mediated glomerulonephritis 3.Viral infections Herpesviruses, Poxviruses, Adenoviruses

46. Regulation of cell volume in health and disease • Maintenance of a constant volume in the face of extracellular and intracelullar osmoticperturbations is critically important for cells existence and function •   There is a lot of physiological and pathological situations in the body, which arecharacterized by changes of osmolality in intra- and/or extracellular space ● Most cells respond to swelling or shrinking by activating specific metabolic ormembrane – transport processes that return cell volume to its normal resting state Rememberessential biophysical law: Water will flow from hypoosmotic space to hyperosmotic one!

47. Fig. 8 Activation of mechanisms regulating cell volume in response to volume perturbations Extracellular hypotonicity Extracellular hypertonicity R e l a t í v e C e l l V o l l u m e Regulatory volume decrease Regulatory volume increase Time Time

48. •  Volume of the cell can be controled by decreasing orincreasing concentration ofosmotically active solutes in the cells. Volume-regulatory accumulation and loss of electrolytesare mediated bychanges in the activity of membrane carriers and channels (K+; Cl-; Na+K+2Cl-; H+/Na+;HCO3- /Cl-) • Key role in cell-volume homeostasis belongs to organic osmolytes • (polyols - sorbitol, myo-inositol; aminoacidstaurine, alanine and proline; • methylamines - betain,glycerylphosphorylcholine). • These are "compatible", "nonperturbing" solutes

49. Mechanisms involved in cell-volume regulation

50. When a shrinkage of a cellis present the cell reacts to the situation immediately byactivation of membrane transport system (inside of seconds - Fig. 9A - left side). It willlead to accumulation of anorganic osmolytes(Na+, K+, Cl-) inside the cell, and secondary, accumulation of water. •  When extracellular hyperosmolalitywill last longer(48h and longer) than anorganicosmolytes in the cell are substituted by organic one's (Fig. 9B - left side) •Swelling of a cellwill activate immediately the regulatory volume decrease mechanisms(Fig. 9 A - right side). If a swelling lasts for a short time,only, the regulatory volumedecrease is done by loss of KCl, very quickly.