Lecture 1 & 2: Cellular Injury and Acute Inflammation Flashcards
STEATOSIS
Hepatocytes with white globs
- intracelullar accumulation of fat and triglyceride
What are the following:
- Hypoxia (Anoxia)
- Chemical
- Physical
- Biological
- Immunologic
- Genetic
- Nutritional
- Aging (Degenerative)
8 general categories of injury
State the following:
- Cells maintain a steady state in which the intracellular milieu is kept within fairly narrow range of physiologic parameter
- process by which cells change in size, number and appearance in response to changes in cell environment
- _____: Increase in the number of cells
- _____; Increase in the size of a cell because of increased cellular substance
- ______: Decrease in the size of a cell because of loss of cellular substance
- ___: Substitution of one type of an adult cell for another type of adult cell (due to continuous stress)
- Homeostasis
- Adaptation
- Changes may be physiologic or pathologic - Hyperplasia
- Hypertrophy
- Atrophy
- Metaplasia
H&E stain
What is a basic dye that stains an acidic nucleus?
What is an acidic dye that stains cyoplasm?
- hemotoxylin
2. Eosin
What are some morphologic changes reflective of loss of brain substance?
- Widening of sulk
2. Narrowing of gyri
What is metaplasia?
Substitution of one type of an adult cell for another type of adult cell (due to continuous stress)
Clinical Example: Normal endocervix and endocervical glands are lined by simple columnar epithelium.
Chronic irritation and inflammation of the cervix uteri may cause replacement of columnar cells by stratified SQUAMOUS cells.
What is the key hallmark of REVERSIBLE cellular injury?
irreversible?
- Cellular swelling
- Membrane damage
- necrosis
- apoptosis
What happens in reversible cell injury to cell function?
What are the 4 occurrences of IRREVERSIBLE cellular injury (graph)
- Cell function declines
- Cell death
- Ultrastructural changes
- Light microscopic changes
- Gross morphologic changes
the principle mechanisms of cellular injury affect what four vulnerable biochemical systems? (4)
- Mitochondria (ATP)
- Cellular calcium
- Integrity of membranes (internal & external)
- Integrity of genetic material
ULTIMATE BIOCHEMICAL CHANGES WHICH DETERMINE DEGREE OF CELL INJURY OR INDUCTION OF CELL DEATH are what? (4):
- Depletion of adenosine triphosphate.
- Oxygen deprivation or generation of oxygen-derived free radicals.
- Concentration of intracellular calcium and loss of calcium homeostasis. (due to increase membrane permeability)
- Defective cell membrane permeability
The following describes what injury model?
- Ischemia due to cutoff of blood supply
- Mitochondria injured
- Decreased ATP produced
- Decreased Na/K pump
- Increased Na in cell, followed passively by water
End result is _____
- Hypoxic Injury Model
2. CELLULAR SWELLING
Loss of energy leads to increase in cellular _____ which leads to altered membrane permeability and activation of intracellular enzymes
What increases?
Calcium
- Phospholipase
(decrease phospholipids) - Protease - membrane & cytoskeleton is disrupted
= NUCLEAR DAMAGE - Increase endonucleases = NUCLEAR DAMAGE (DNA)
- ATPases increase which decrease ATP
What are the clinical correlations to measure diagnosis of disease due to altered membrane permeability of the cell (allowing intracellular enzymes to leak out)
What enzymes leak out?
creatine phosphokinase and lactic dehydrogenase, to leak from the cell into the vascular
compartment.
Example: Elevated level of troponin in acute myocardial infarction.
Elevated CK or troponin = acute MI (acute thrombis acute hypoxia/ischemia)
Elevated AST/ALT = hepatitis (viral hepatitis, or steatosis of liver)
Decrease intracellular oxygen (decreased ATP) causes the cell to switch from ____ to ____ respiration.
The ultimate buildup?
Clinical example?
_____ Clearance is an emerging way of confirming adequate resuscitation in shock
- aerobic to anaerobic
- lactic acid levels increase as a by-product of anaerobic glycolysis, leading to a state of metabolic acidosis in the body
- Example: Cardiac arrest (anoxia) may lead to metabolic acidosis, which may be addressed during CPR.
- Lactate
What is the free radical injury model?
A free radical is an atom or group of atoms which have a single unpaired electron in the outer orbit.
Free radicals are chemically unstable and very reactive with components of the cell, ie membrane, intracytoplasmic organelles.
What are the steps of generating a free radical?
What are 3 methods of free radical injury?
- O2 superoxide
(converted to H2O2 by SOD) - H2O2 decomposed to H20 by glutathione peroxidase
- OH radical
a) - membrane damage
b) breakdown/misfolding of proteins
c) mutations
What 3 species that are intermediate between O2 and H2O.
O2 ̅ superoxide;
H2O2, hydrogen peroxide
OH, hydroxyl radical.
Key free radical scavengers: 3
- catalase
- superoxide dismutases
- glutathione peroxidase
What is converted in hepatocytes that can cause to lipid preoccupation & damage to cell structures?
CCL4 (dry cleaning solvent) to CCL3 in hepatocytes
The following are examples of what type of injury:
1. CCL4 (carbon tetrachloride)
2. Reperfusion injury
(explain)
Free radical
- Reperfusion injury:
a) Return of blood/oxygen to ischemic tissue
b) Oxygen derived free radicals produced
c) (Paradoxical) Further injury to cells
What are 5 examples of REVERSIBLE cell injury?
- Cellular swelling
- influx of Na pulling H20 in - Steatosis (fatty change)
- Myelin figures
- ER swelling
- Membrane blebs
_____ ischemic injury
showing surface BLEBS,
increased EOSINOPHILIA of cytoplasm,
and SWELLING of occasional cells
______ injury of
epithelial cells, with pyknosis, loss of nuclei* , fragmentation of cells, leakage of contents
- Early (reversible)
- Necrotic (irreversible)
** fragmentation of CELLS**
What are the two subtypes of irreversible injury?
- Necrosis
2. Apoptosis
What is necrosis?
Necrosis: The sum total of morphologic changes, which occur in living tissue following cell death.
Necrosis includes structural changes in the nucleus and cytoplasm of dead cells.
It also is characterized by the presence of LEUKOCYTES (esp. neutrophils) infiltrating dead tissue from adjacent living tissue.
The morphologic changes occur as a result of enzymatic breakdown of the cell and denaturation of proteins.
Define the following:
- Karyolysis
- Pyknosis
- Karyorrhexis
- Karyolysis - basophilia of the chromatin may fade, a change that reflects loss of DNA because of enzymatic degradation by endonucleases.
- Pyknosis - Characterized by nuclear shrinkage and increased basophilia. The chromatin condenses into a solid, shrunken basophilic mass (also seen in apoptosis) –> DARK BLACK
- Karyorrhexis - the pyknotic nucleus undergoes FRAGMENTATION.
In a day or two, the nucleus in the necrotic cell totally disappears.
Breakdown of plasma membrane, organelles, and leakage of contents = ______
Fragmentation, chromatin condensation = ____
- Necrosis
2. Apoptosis
What are the 5 histologic patterns of necrosis?
- Coagulation necrosis
- Liquefactive necrosis
- Caseous necrosis
- Enzymatic fat necrosis
- Gangrene
COAGULATION NECROSIS:
- Pattern of necrosis associated with severe ______.
- Occurs where?
- Histologically? (lacks what, what is preserved, stains what color?)
- Macroscopically?
Examples?
- ISCHEMIA
- In solid organs (heart, kidney)
- Ghost-like remnants of intact cells which lack nuclei.
The cell outline is preserved. The cytoplasm stains intense pink (eosinophilia) - Tissue firm (in early stages)
Examples: Myocardial infarct, renal infarct
NOT THE BRAIN*
LIQUEFACTIVE NECROSIS
- Associated with what?
- Microscopic: collection of what and why?
- Macroscopic: what material? (collection of _____)
- Pattern of necrosis with hypoxia/infarct of what organ?
- Pattern of necrosis often associated with bacterial infections
- Microscopic: Bacteria release enzymes causing a rapid loss of cellular structure and a collection of liquid, amorphous debris
- Macroscopic: creamy yellow material
* ABSCESS = collection of neutrophils, dead cells, liquid* - Pattern of necrosis with BRAIN hypoxia/infarct*
(also occurs in kidney etc)
How is liquefactive necrosis different from coagulative?
Liquefactive = No cellular detail left
- necrotic, AMORPHOUS tissue
- RIM of neutrophils
CAUSEOUS NECROSIS:
- Pattern of necrosis associated with an inflammatory reaction called ______
- Histologically: amorphous, granular debris (dead cells) in the center of ______ cell reaction (chronic inflammatory reaction)
- Macroscopically: necrotic tissue is what?
- “granuloma”
- granulomatous
- soft, white, friable
- no cellular detail!
(caseous = cheese)
What defines a granuloma?
Epithelial histiocytes
surrounded by Giant cells and ring of lymphocytes
- usually in TB or fungal infection
(test with AFB or GMS stain)
ENZYMATIC FAT NECROSIS:
- Term commonly used to describe focal cell death in the _____ and adjacent fat.
pancreas
ex: acute pancreatitis!
Enzymes (lipase) release from damaged pancreatic cells digest or liquefy adipose cells. With lipid breakdown, fatty acids are released and combine with calcium to form yellowish-white insoluble soaps = SAPONIFICATION
(FA + CALCIUM)
WHAT TYPE OF NECROSIS IS THIS?
Represents coagulation (ischemic) necrosis, usually of an extremity, bowel, gallbladder ( due to ischemia --> loss of blood supply)
What is this called if bacteria contaminate dying tissue and superimpose liquefactive necrosis?
- GANGRENE
- clinical term - WET GANGRENE
- diabetes with peripheral vascular disease + superimposed infection
What type of cell death is characterized by NUCLEAR CONDENSATION & FRAGMENTATION coupled with fragmentation of CYTOPLASM?
APOPTOSIS
-Recognition, removal of dead cells by phagocytes
Apoptosis is not associated with what?
What are the drivers of apoptosis?
How can one tell on H&E stain that a cell is apoptotic?
An inflammatory Reaction
CASPASES
- Eosinophilic
- Nucleus is indistinct
- Glassy appearance of the cell
The following are examples of what:
Normal embryogenesis (ex: thryoglossal ducts)
- Hormone dependent physiologic involution Example: menstrual cycle
- Proliferating cell populations
Example: intestinal crypts - DNA damage
Example: Radiation exposure - Infections
Example: Viral hepatitis - Accumulation of misfolded proteins
Example: CNS degenerative diseases
APOPTOSIS
The reaction of vascularized tissue to injury is called ______
Acute Inflammation
What are 4 causes of inflammation?
What is the major difference between acute & chronic inflammation?
- Infections
- Tissue necrosis (ischemia etc)
- Foreign body (splinter)
- Immune RXN. (hypersensitivity)
Acute = neutrophils, plasma proteins, fui to injury (short)
Chronic: lymphocytes & macrophages &proliferating blood vessels & connective tissue (LONGER)
How does a physician recognize an acute inflammation?
- Local: redness (rubor), swelling (tumor), heat (calor), pain (dolor)
- Systemic: fever, shaking chills, malaise, leukocytosis
What are the 7 steps of acute inflammation?
- Margination
- Rolling
- Adhesion
- Transmigration & Chemotaxis
- Phagocytosis
- Destruction of phagocytes material
- Resolution (neutrophils apoptose)
RECOGNITION of the microbe:
1.______ activate TLRs and other recognition receptors on monocytes
2.This forms the _______:
A multi-protein complex characterized by activation of _____
- Cleaves cytokine ____ to activate inflammatory cytokines
+
Releases ___ due to formation of NF-KB
- DAMPS/PAMPS
- INFLAMMASOME
- CASPASE 1
- IL-1 (also IL-6 and IL-8)
- TNF-a
What is present on macrophages that recognizes the PAMPS on LPS?
CD14
Once TNF-a, Il-1, 6, 8 are activated & released by CASPASES what is the first to respond?
BLOOD VESSEL
- vasodilation occurs
Initial vasodilatation (arteriole, then capillaries), induced by the cytokine driven local release of nitric oxide, causes increased blood flow.
Increased blood flow causes increased hydrostatic pressure that, in combination with increased vascular permeability, leads to leakage of plasma proteins and decreased colloid osmotic pressure.
Both mechanisms work in concert to cause increased extravascular fluid or edema (swelling).
The quad of Inflammation (color, rubor, tumor, dolor) cause what 3 major events to occur?
- Vascular dilation and increased blood flow (causing erythema and warmth)
- Extravasation of plasma fluid and proteins (edema)
- Leukocyte (mainly neutrophil) emigration and accumulation
What is phase 1 of acute inflammation?
What is the function of chemokines in this step?
- Microbe recognized by PAMP/DAMP TLR & releases cytokines chemokines
- Chemokines - cause MARGINATION of neutrophils all around the RBC due to LECTIN & SELECTIONS
- vasodilation slows blood flow in post-capillary venues
- cells marinate from center of flow to periphery
Describe the components important for the following:
- Rolling adhesion
- Tight binding
- Diapedesis
- Migration
- Selectin (CD31)
- Tight binding (LFA-1 & ICAM)
3 &4 –> IL-1 IL-6 and TNF alpha increase all adhesion molecules
- then extend pseudopods between adjacent endothelial cells and migrate through the vessel wall (transmigration)
How do PMNs move from a blood vessel to point of injury?
What is critical for chemoattraction & transmigration?
What are powerful chemoattractants?
CHEMOTAXIS
- ACTIN –> activated cytoskeleton
(ex: Chediak - Higashi Syndrome is a protein trafficking defect) - peptides released by bacteria, components of the complement system,( C5a) arachnidonic metabolites (leukotriene B4) and the tetrad of inflammatory cytokines (IL 1,6,8 & TNF-),
LB4 & C5a = neutrophil chemotaxic agent
What is phase 2 of acute inflammation?
What promotes monocyte chemotaxis?
Monocyte/Macrophage activation & recruitment
promoted by neutrophil degranulation
What happens in Phase 3 of acute inflammation?
Monocytes recruited by NEUTROPHIL degranulation, and monocytes in the area prevent more neutrophils from being attracted to the area
What is the difference between monocyte, macrophage, and histiocyte?
NOTHING
monocyte = blood fluid = macrophage tissue = histocyte
What are the early infiltrates in ischemic necrosis of myocardium?
Late?
- neutrophilic
- Mononuclear (monocyte, mac, histiocyte)
edema –> neutrophil –> monocyte
______: increased delivery of cells/unit time increases the chance that a leucocyte can respond to a signal
Rheologic
The following is describing what cell:
- Most numerous leukocyte in circulation
- Signature cell of acute inflammation
- Bone Marrow is capable of rapid production and release
- Half life if ~12’ in blood, 1-2” at inflammatory site
NEUTROPHIL
What does “Left shift” or BANDEMIA refer to?
Bone Marrow responds by pushing mature & slightly immature but functional PMNs out early and in vast amounts
The clinical correlate of this is elevated leucocyte counts and the presence of young cells that are called “bands” (c-shaped)
mature from right to LEFT
= left shift –> maturation
What occurs to neutrophils at the site of injury? (5)
- Phagocytosis
- Recognition/attachement
- opsonins: IgG & C3b - Engulfment/degranulation
- formation of phagolysosome once pseudopods extend from leukocyte and merge with lysosome
- This amoeboid movement involves microfilaments, actin and myosin, and requires energy and intracellular calcium.
Degranulation: Lyosomal granules that are attached to the wall of the phagosome release their contents into the vacuole, a process known as degranulation.
- Killing/degradation
- Oxidative burst - NETS
- chromatin spray to the outside of the cell to trap bacteria & fungi
As the neutrophil degranulates, a series of chemical reactions is initiated by the activation of an oxidative (respiratory) burst that generates microbiocidal agents. The most important ones are:
- ROS
-Activation of NADPH converts oxygen to
superoxide ion, which is then converted to H2O2 and free oxygen radicals.
2) Lysosomal enzymes.
These are sequestered in azurophilic granules of neutrophils.
3)Myeloperoxidase is a major enzyme in the granule and,inthe presence of a halide like chloride, generates the powerful oxidant HOCl that kills by halogenation and peroxidation.
Why is NADPH oxidase important? (what does it convert)
SOD?
MPO?
Converts O2 to O2-
Converts O2- to H202
Converts H202 to HOCl
How do NETS function?
PMN sacrifices its nucleus by casting its chromatin laden with killer granules out of the cell as a net to trap bacteria and fungi
What has many granules, large golgi, and an indented nucleus?
MONOCYTES/MACROPHAGES
What is Phase IV of acute inflammation?
release of TGF - B and IL-10
–> recruit monocytes to clean debris and dying neutrophils
- Scavenging of apoptotic neutrophils promotes macrophage growth factors
and repair
- Control of acute inflammation is dependent on what?
- When the inflammatory stimulus is destroyed or neutralized, _____ subsides:
- What happens since there is no TLR or phagocytic receptor activation anymore?
- What cytokines establish the correct milieu for appropriate healing and wound repair?
- Macrophages
- acute inflammation
- a) Decreased pro-inflammatory mediator synthesis and release
b) Macrophages sense this as they clean up dying neutrophils
c) predominant cytokines are TGF-B and IL-10 - TGF - B and IL-10
- Diminished TLR activation signals M1 macrophages to convert to M2 macrophage phenotype and upregulate their synthesis of TGF-B and IL-10.
What are the 2 possible outcomes of acute inflammation?
- Resolution & repair
(neutrophils undergo apoptosis and sipper within 24 h.) - Transition to chronic inflammation
State the morphology of acute inflammation as ranked by the following:
- Lease severe
- Intermediate
- Severe
- Special category
- Lease severe - SEROUS
- protein poor
- capillary to space-peritoneal, pericardial, or pleural
clinically = TRANSUDATE - Intermediate: FIBRINOUS
- fluid w/ larger molecules & fibrinogen
- converts to fibrin = scarring - Severe - SUPPURATIVE/ABCESS
- **protein rich fluid
- inflammatory cell, alive & dead necrotic debris
- EXUDATE (a lot of neuts) - Special category- ULCERATIVE
- underlying inflammation causes excavation of mucosal or skin surface
Which acute inflammation can cause potential scarring?
Which is known as transudate & is protein poor?
Which is known as exudate and is protein rich?
Which is due to inflammation causing excavation of mucosal or skin surface?
- FIBRINOUS
- SEROUS (protein poor)
- ABCESS/ SUPPURATIVE (pus) = PURULENT
- ULCERATIVE
