PULM 4: Eicosanoids

All eicosanoids are chemically diverse ________ derived from __________

autacoids (short-lived local hormones)

derived from arachidonic acid

eicosanoids are chemically diverse autocoids that allow for local communication and signaling acting in a _______ or _______ fashion by stimulating _____ receptors

paracrine or autocrine

g protein

what are the six different subtypes of eicosanoids?

1. prostaglandins (thromboxane, prostacyclin)

2. leukotrienes

3. lipoxins

4. hepoxolins

5. epoxyeicosatreionic acids

6. hydroxyperoxyeicosatetraenoic acids

Ecosanoids are synthesized from ____ carbon long ___________ ______ ________ (__________)

• you can get ecosanoids in ur diet from _____ and _______

• which organ systems are ecosanoids essential for?

20 carbon PolyUnsaturated Fatty Acids

• plants and fish

• cardiovascular, reproductive, and inflammation

Biochemical Effects of Exosanoids:

• ________, __________, ____________

• _______ heart rate

• vision

• increase/decrease in

  • neuronal ________ ______

  • _____ _______

  • ______ ________

• gluconeogenesis, lipolysis, glycogenolysis

• increased

• increased/decreased

  • electrical activity

  • muscle contraction

  • blood pressure

arachidonic aids are synthesized from ______ _____

• they are esterified to membrane phospholipipids such as __________ , __________, and ___________

• rate limiting step: their release from membrane using __________ which can be secretory or cytosolic

• release is stimulated by _______ and _______ ________

• inhibited by ___________

linoleic acid

• phosphatidylCHOLINE

• phosphatidylETHANOLAMINE

• phosphatidylLINOSITOL

'

cytokines and growth factors

lipocortins

what allows for the release of membrane bound archadonic acids that are esterified to membrane phospholipids?

what inhibits this release?

phospholipase A2 (stimulated by cytokines and growth factors)

lipocortins

once a stimulus such as a growth factor or cytokine binds to the receptor arachidonic acid is released from

• phosphatidyl choline using ____________

OR

• phosphatidylinositol bisphosphate using ___________ which turns it into __________ which is then converted to ___________ _______ and ________________ which can further be converted to arachidonic acid

• released from phosphatidylcholine using phopholipase A2

• released from phosphatidylbiphosphate using phospholipase C turning it into 1,2 diacylclycerol which is turned into arachadonoc acid and monoacylglycerol using diacylglycewrol lipase which is further broken down into arachidonic acid using monoacylglycerol lipase

What are three examples of prostanoids?

1. prostaglandins

2. prostacyclin

3. thromboxane

Prostanoids:

• modulators of ________ ______ activity

• controls _______ _________ and inhibits the effect of _________-______ hormone

• plays a role in

  • _________ responses

  • ________

  • pregnancy (dont take NSAIDs!)

  • which organ systems?

adenyl cyclase activity

control platelet agression

inhibit anti-diuretic

inflammatory

pain

cardiovascular and renal

Prostanoids (thromboxane, prostaglandin, prostacyclin) play a significant in modulating adenylate cyclase activity which includes…

1. renal and cardiovascular system

2. inhibit anti-dieruretic

3. control platelet aggression

4. inflammation

5. pain

6. pregnancy

how are prostanoids synthesized?

cyclooxygenase pathways

what are the three COX enzymes involved in the sythesis of prostanoids? what is the significance of each?

1. COX1 = housekeeping (maintain homeostasis)

2. COX 2= pain receptor

is COX 1 or COX 2 consituitive?

(expressed regardless of external stimulus)

COX1 - required for housekeeping - constitutive

COX2- mostly induced by pain but IS constitutive in parts of the Nervous System

COX 1 vs COX 2

where is each enzyme located in terms of tissues?

1= ubiquitous expression (found almost everywhere)

2= found in tissues that are under stress (inflamed and activated tissues)

COX 1 vs COX 2

where are the enzymes located within cells?

1= endoplasmic reticulum

2= endoplasmic reticulum and nuclear membrane (so if you stain for COX 2 you will find that both the ER and nuclear membrane will have color)

COX 1 vs COX 2: Substrate Selectivity

• which substrates bind to COX 1?

• which substrates bind to COX 2?

Cox 1 = arachidonic acid and eicosatetraenoic acids

Cox 2 = arachadinoic acid, eicosatetraenoic acids AND y-linolenate, a-linolenate, linolenate

COX 1 vs COX 2: Substrate Selectivity:

• what typically happens when arachadoic acid or eicosatetrenoic acid binds to COX 1 enzyme?

• what happens when aracadoic acid, eicosaterenoic acid, a-, g-linolenate bind to COX 2?

cox 1 = protection/maintenance

cox 2= proinflamatory and mitogenic functions

how are COX 1 enzymes induced?

they don’t have to be INDUCED they are naturally expressed EVERYWHERE (ubiquitously)

how are COX 2 enzymes induced?

• Liposacharides (LPS)

• TNF-a (tumor necrosis factor)

• Interleukin 1 (IL-1)

• Epidermal Growth Factor (EGF)

• IFN-y (interferon- family of cytokines)

what inhibits COX 1 enzyme from maintaining homeostasis?

NSAIDS

what inhibits COX2 enzymes from creating proinflammatory and mitogenic responses ?

• NSAIDS

• Acetaminophen (is a costrubstate that INDIRECTLY inhibits ecosanoids from binding to COX2)

• antiinflammatory glucocorticoids

• IL4, 10 (downregulate macrophages), 13

• cox2 selective inhibitors

which interleukins INHIBIT COX 2?

which interleukins INDUCE COX 2?

what about COX 1?

IL-4, 10, 13inhibit COX 2

IL-1 and IL-2 induce COX2

COX 1 is only inhibited by NSAIDS and is not induced by interleukins

Prostanoid Synthesis:

1. arachidonic acid that is esterified to phospholipid on membrane is released by __________

2. the arachidonic acid is then converted to ________ using ___________ also known as __________ (CYCLOOXYGENASE REACTION)

3. _______ —→ ________ (PEROXIDASE REACTION) THIS IS THE PRECURSOR TO ALL PROSTOGLANDINS

1. phospholipase A2

2. arachadoic acid —> PGG2 (cyclooxygenase 1 and 2— PGH2 synthases)

3. PGG2—> PGH2 (cyclooxygenase 1 and 2 — PGH2 synthases)

what is the precursor to all prostaglandins?

how do we get there from arachidonic acid?

PGH2

1. aracadoic acid is esterified to phospolipid on membrane and detached by phospholipase A2

2. CYCLOOXYGENASE REACTION;

   arachidonic acid is converted to PGG2 using cyclooxygenase 1 and 2 (PGH2 synthase)

3. PEROXIDASE REACTION:

   PGG2 —> PGH2 using cyclooxygenase 1 and 2 (PGH2 synthase)

how do you get from PGH2 to

• PGF2a

• PGD2

• PGE2

• PGI2

• TXA2

• PGF synthase

• PGD synthase

• PGE synthase

• Prostacyclin Synthase

• thromboxane synthase

which prostanoids can you make from PGH2?

which enzyme doesnt have the most straightforward name?

1. PGD2

2. PDE (found in macrophages)

3. PGF2a

4. PDI2

5. thromboxane A2 (TXA2) - found in blood vessels

to make PDI2 from PHH2 you use prostacyclin synthase but for the rest of them its their name-synthase

Prostaglandins:

• all have ________ ring

• letter code is based on ring modifications such as ______ and ______ groups (F, D, I, E)

• the subscript refers to the number of _______ ______in the two side chains (F2a, D2, I2)

• cyclopentane

• ketone hydroxy

• double bonds

which prostanoid is shown

thromboxane A2

which prostanoid is shown?

prostacyclin (PGI2)

Prostanoid Receptors:

• where are they located

• the specificity of their receptor (what binds to them) is determined by _____ _________ and _______ on different cells

• all prostanoids are _________ coupled

• there are multiple isoforms of receptors identified due to ________ ______ _________ (ex. EP3= 1, 2, 3, 4, 5, 6, e, f)

• cell membrane

• receptor density and type

• g-protein coupled

• differential mRNA splicing

which prostanoid is the precursor to all other prostaglandins?

prostaglandin H2

which prostoglandin when bound to g-coupled receptor leads to

• broncoconstriction

• sleep control

• inhibits platelett agression

Prostaglandin D2

*sounds like a man that has a D

• sleeps, agression, bronco

which prostoglandin when bound to g-coupled receptor leads to

• vasodilation

• bronchodilation

• hyperalgesia (more responsive to pain)

• fever

• diuresis (excess urine)

• immunomodulation

Prostaglandin E2 (just like IgE during allergic reaction)

which prostaglandin when bound to g-coupled receptor leads to

• smooth muscle contraction

• bronchocontriction

• abortion (allow to give birth)

Prostoglandin F2a

• think female—abortion, smooth muscle contraction, also a broncoconstrictor with the male

which prostaglandin when bound to g-coupled receptor leads to

• vasoconstriction

• control of vascular tone

• platelet activation

thromboxane

you want to make a clot so you would wanna restrict the blood vessel first and then begin activating the platelets which is controlling the vascular tone

which prostaglandin when bound to g-coupled receptor leads to

• vasodilation

• control of vascular tone

• platelet aggregation inhibition

Prostaglandin I2 = prostacyclin

I2 is thromboxanes OP - does complete oposite, does NOT want aggregation to prevent embolism so will dilate blood vessel which is vascular tone control

which prostaglandin has both anti-inflammatory AND inflammatory responses?

what happens once it binds to receptor?

Prostaglandin E2

• bronchodilation

• vasodilation

• hyperalgesia

• fever

• diuresis (excessive pee)

• immunomodulation

Prostanoid Inactivation:

what is the half-life or prostanoids and where are they usually found?

• seconds to minutes

• lungs and liver

how are prostanoids excreted once they are inactivated?

excreted through urine

What are the five different ways that prostanoids can be inactivated?

1. hydroxylation by 15-a-hydroxy prostaglandin hydroxylase (PGH) followed by reduction by 13 prostaglandin reductase

2. oxidation of hydroxy group at C15 to keto group

3. reduction of C13 and C14 to dihydroxy derivatives

4. B-oxidation - resulting in the loss of 2 carbons

5. w-hydroxylation to dicarboxylic acid derivatives

Prostanoid Inactivation:

1. ___________by 15-a-hydroxy PGH followed by ________ by 13-PG reductase

2. oxidation of hydroxy group at carbon 15 to ______ group

3. reduction of C13 and C14 to _______ derivatives

4. ____-_______ resulting in loss of 2 carbons

5. w-hydroxylation to ______________ ____ derivatives

1. hydroxylation followed by reduction

2. hydroxy→keto at 13th carbon

3. dihydroxy

4. b-oxidation

5. dicarboxylic acid

Prostanoid Inactivation:

1. hydroxylation by 15-a-hydroxy prostaglandin hydroxylase (PGH) followed by reduction by 13 prostaglandin reductase

2. oxidation of hydroxy group at C15 to keto group

3. reduction of C13 and C14 to dihydroxy derivatives

4. B-oxidation - resulting in the loss of 2 carbons

5. w-hydroxylation to dicarboxylic acid derivatives

COLOR CODE THE WHERE THE FOLLOWING INACTIVATION ROUTES WOULD OCCUR

blue= beta oxidation (loss of 2 carbons)

green= reduction of C13 and C14 to dihydroxy

red= w-hydroxylation

purple = C15 oxidation to keto

Leukotrienes:

• produced by _________

• 100-10000 more potent than ______ in causing __________

• component of slow reacting substance of ______ ( )

• produced via ________ pathway

leukocytes

histamines bronchoCONSTRICTION

anaphylaxis (SRS-A)

5-lipoxegenase

Leukotriene Synthesis:

1. arachadoic acid is released from esterified lipoprotein from membrane using _________

2. Arachadoic acid is then converted to ________ using ___________

3. which is then converted to __________ using ________

4. which is then converted to PARENT leukotriene (_____) using ______

5. Once the parent compound _______ the cell it is able to convert into different leukotrienes

6. you can use ________ to convert the parent compound into _________ by removing ______

7. you can further convert it using _________ which removes a ________ turning it into

1. phospholipase 2

2. 5-HPETE using 5-lipoxygenase

3. LTA4 using 5-lipoxygenase

4. LTC4 using LTC4 synthase

5. LEAVES

6. gamma glutamyl transferase turn LTC4 into LTD4 by removing glutamate

7. LTE4 using dipeptidase by removing glycine

SEQ Leukotriene Synthesis

1. arachadonic acid is released from esterified phospholipid in membrane using phospholipase A2

2. arachadonic acid converted to 5-HPETE using 5- lipoxygenase

3. then converted to LTA4 using 5-lipoxxygenase

4. then converted to parent compound LTC4 using LTC4 synthase

5. LEAVING cell glutamate can be released by gamma glutamyl transferase leaving LTD4

6. further remove glycine using dipeptidase turning LTD4 —> LTE4

which prostoglandins are most likely to bind to the DP1 receptor found in

• platelets

• vascular smooth muscle

• nervous tissue

• retina

• lung

• uterus

• stomach

• small intestines

• illum

• macrophages

1. D

2. E2

3. F2a

4. I2 and TXA2

which prostoglandins are most likely to bind to the DP2 receptor found in

• esinophils

• basiphils

• T helper cells

• macrophages

1. D

2. E2 and F2a

3. I2 and TXA2

which prostoglandins are most likely to bind to the EP1 receptor found in

• kidney

• lung

• spleen

• skeletal muscle

• testis

• uterus

1. E2

2. F2a and I2

3. D2 and TXA2

which prostaglandins are most likely to bind to the EP2 receptor found in

• lung

• placenta

• heart

• macrophages

• bone marrow

1. E2

2. F2a and I2

3. D2 and TXA2

which prostaglandins are most likely to bind to the EP3 receptor found in

• kidney

• stomach

• uterus

• pancreas

• adrenal

• testis

• ovary

• small intestine

• brain

• spleen

• colon

• heart

• liver

• skeletal muscle

• lung

• thymus

• ileum

1. E2

2. F2a and I2

3. D2 and TXA

which prostaglandins are most likely to bind to the EP4 receptor found in

• small intestine

• lung

• thymus

• kidney

• uterus

• pancreas

• spleen

• heart

• stomach

• brain

• ileum

• PBMC

• macrophages

1. E2

2. F2a and I2

3. D2 and TXA

which prostaglandins are most likely to bind to the FP receptor found in

• corpus luteum (f for female!)

• uterus

• stomach

• kidney

• liver

• heart

• lung

• eye

• liver

1. F2a

2. D2

3. E2

4. I2 and TXA2

which prostaglandins are most likely to bind to the IP receptor found in

• platelets

• vascular smooth muscle

• kidney

• thymus

• liver

• lung

• spleen

• kidney

• heart

• uterus

1. I2

2. D2

3. E2 and F2a

4. TXA2

which prostaglandins are most likely to bind to the TP receptor found in

• platelets

• vascular smooth muscle

• thymus

• spleen

• lung

• kidney

• heart

• uterus

1. TXA2 and H2 (parent compound need thromboxane synthase to get)

2. D2, E2, F2a, I2

mostly thromboxane and H2 but fair game for anyone else

Leukotriene Singnalling:

• Which leukotrienes are signal to Gai/aq proteins?

• which leukotrienes signal Gaq/Ga11?

Gai/aq = BLT1, BLT2, GPR17

Gaq/Ga11= CysLTR1, CysLTR2, and CysLTRE (GPR99)

which receptors signal Gai/Gaq subunits?

what effect does leukotriene binding to these receptors have?

BLT1

BLT2

GPR17

decreased cAMP and increased Ca2+

which receptors signal Gaq/Ga11 subunits?

what effect does leukotriene binding to these receptors have?

CysLTR1

CysLTR2

CysLTRE (GPR99)

activation of PLC = increased DAG and IP3

which leukotriene binds to BLT 1?

which G protein is signaled?

what effect does this have?

B4

Gai/Gq

decreased cAMP and increased Ca2+

which leukotriene binds to BLT 2?
which G protein is signaled?

what effect does this have?

B4, 12(S)HETE, 12(S)HPETE

Gai/Gaq

decreased cAMP and increased Ca2+

which leukotriene binds to GPR17?

which G protein is signaled?

what effect does this have?

C4 more than D4

Gai/Gaq

decreased cAMP and increased Ca2+

which leukotriene binds to CysLTR1?

which G protein is signaled?

what effect does this have?

D4>C4>E4

• Gaq/Ga11

• increase PLC, DAG, and IP3

which leukotriene binds to CysLTR2?

which G protein is signaled?

what effect does this have?

C4 > D4 >E4

Gaq/Ga11

increased PLC, DAG, IP3

which leukotriene binds to CysLTRE?

which G protein is signaled?

what effect does this have?

E4> D4> C4

Gaq/ Ga11

increased PLC, DAG, IP3

which leukotriene gives rise to all other leukotrienes?

A4

which leukotriene allows for

• neutrophil activation

• chemotatic

• plasma exudation (plasma filled with proteins rushes to scene)

B4

which leukotriene allows for

• bronchoconstriction

• vasoconstriction

• decreased coronary blood flow

• decreased cardiac contractility

• plasma exudation

• promote endothelial and mesangial cell proliferation

• activation of transcription factors

• cytokine release

C4 and D4

which leukotriene allows for

• mucin release

this leukotriene can cause issues in _____ patients who already deal with an array of secretions

E4

issue in asthma patients

which leukotriene

• releases Ca2+ stores

• promotes cell proliferation

HETEs

Leukotrienes are metabolized in the _______ and excreted in the ________

metabolized in liver

excreted in urine

Leukotriene Inactivation:

LTE4 —→ __________ using ____________

—> _________ using _____________

—> _________using __________________

LTE4—> 20-COOH-LTE4 (acylcoA oxidase) —>

18-COOH-dinor-LTE4 (hydratase/dehydrogenase) → 16-COOH-tetranor-LTE3 (B-oxidation 2,4-dienoyl-CoA reductase) —→ 14-COOH-hexanor-LTE4 (B-oxidation by CoA thiolase)

What are the five structures in order of leukotriene inactivation?

LTE4

20-COOH- LTE4

18-COOH-dinor- LTE4

16-COOH- tetranor - LTE3

14- COOH -hexanor- LTE4

what are the five enzymes in order in leukotriene inactivation?

1. w- oxidation by acyl-coa oxidase

2. b-oxidation by hydratase/dehydrogenase

3. b-oxidation 2,4-dienoyl CoA reductase

4. b-oxidation by CoA Thiolase

Are lipoxins antiinflammatory or proinfllamtory?

anti-inflammatory

lipoxins are produced via -___ alone or a compination of ___-____ pathway + ___-___ followed by conversion by __________

platelets convert LTA4 via ___-____ pathway

are lipoxins short-lived or long-lived?

either 5 LOX alone or 15LOX and 5 LOX followed by conversion by hydrolase

platelets convert LTA4 via 12-LOX pathway

short lived

Lipoxins:

Neutrophils convert Arachadoic acid into _____ using _________ enzyme which the platelets will convert to ______ or ________ using ______

Epithelial cells convert arachidonic acid into __________ using the ______ enzyme which neutrophils will convert to _____ or _______ using _________

In Epithelial Cells 15 LOX coverts Arachadoic Acid into __________ which is converted to ____ or ______ using neutrophilic ________

Arachidonic Acid —> LTA4 (5 LOX in neutrophil)—> LXA4 or LXB4 (12-LOX in platelets)

Arachidonic Acid —>15-H (p) -ETE (15 LOX in epithelial cells)—> LXA4 and LXB4 (5-LOX in neutrophil)

Arachidonic Acid—> 15R-H(p)-ETE (COX-2/ASA in epithelial/endothelial cells) —> 15-epi-LXA4 or 15-epi-LXB4 (5 LOX in neutrophil)

Lipoxin Functions:

• act as negative/positive regulators of inflammation and leukotriene actions

• which type of G protein is stimulated upon binding?

• where are they found?

negative regulators

Gai

• neutrophil

• monocytes

• T cells

• Lung

• spleen

• blood vessels

• Gi protein coupled receptor

Lipoxin Functions:

• inhibit neutrophil __________, _________, ____________

• inhibit eosinophil ______________________

• stimulate ____________by stimulating production of ______ and ________

• inhibit LTC4 and LTD4 stimulated ______________

• inhibit _______ stimulated inflammatory effects

• inhibit function of _____ cells and ___ cell secretion

• chemotaxis, adhesion, transmigration

• recruitment

• STIMULATE vasodilation by stimulating PGI2 and PGE2

• vasoconstriction (cause vasodilation)

• LTB4

• NK cells and T cell secretion

what is inhibited vs stimulated by lipotoxin?

Inhibited:

neutrophil

eosinophil

LTC4 and LTD4

LTB4

NK cell and T cell secretion

Stimulate:

PGI2 and PGE2 vasodilation

How does lipoxin mediate the resolution of inflammatory response?

• stimulates _____ and ___________ of apoptotic _________ and ___________

• increases ____-______ activation of monocyte

• uptake and clearance neutrophils and macrophages

• non-phlogistic (removal of dying cells)

Which eicosanoids play a role in asthma?

LTC4

D4

E4

Which eicosanoids play a role in inflammatory bowel disease?

LTB4

Which eicosanoids play a role in glomerulophritis?

LTB4

C4

D4

Which eicosanoids play a role in cancer?

• COX2

• PGE2

Which eicosanoids play a role in cardiovascular disease?

TxA2 mediated in thrombosis

Myocardial Infarction

Leukotriene Production

Which eicosanoids play a role in inflammation?

Leukotrienes

PGE2

LXA2

TxA2

PGI2

PGD2

involved in vasodilation, edema, chemotaxis, pain, vascular permeability, fever

Epoxyeicosatetraenoic acids (EETs):

• produced via _________

• act as paracrine factors regulating ______ ______ and _____-___________

• can act as ________ to increase/decrease blood pressure

• cytochrome P450 epoxygenase

• local vascular tone and anti-inflammation

• vasodilators

where are Epoxyeicosatetraenoic acids (EETs) located?

• cardiovascular endothelium (lower blood pressure)

• ascending loop of henle

• vascular endothelium of kidney

• brain astrocytes

• airway and parenchymal lung tissue

ANY TISSUES LACKING CYCLOXEGENASE AND LIPOXYGENASE

Epoxyeicosatrataenoic Acids are found in any tissues that lack _________ and _________ as they are produced via ______________________

found in tissues that lack CYP450 epoxygenase

epoxyeicosatetraenoic acids (EETs)

which LOX enzyme is found in the

• epithelial cells

• neutrophils

• platelets

for the

• 15-LOX

• 5-LOX

• 12-LOX