MICR104A - Lesson 4: Innate Immunity B: Cells and Systemic Responses to Inflammation

neutrophils

the first line of defense

sites of inflammation

neutrophils are the first cells attracted to ______________________

walls of blood vessels, inflamed tissues

• during inflammation, neutrophil cells bind into the _________________ then migrate towards ___________________.

opsonins

invaders can be easily bound and phagocytosed by neutrophils through __________.

macrophages

form the second line of defense.

1. dead and dying neutrophils

2. foreign particles

macrophages eat

adaptive immune system, healing process

macrophages can present antigens for the _________________________; and they begin the ____________________ in damaged tissues

M2 macrophages

The healing process is carried out by ___________________

1. secrete anti-inflammatory cytokines

2. clean up dead cells and microorganisms

3. promote tissue healing and remodelling

M2 macrophages role

• distant parts of the body

• brain, sickness behavior.

• while inflammation is localized to the affected site, it can also affect ____________________.

• cytokines produced reach the _______ and result to _________________________

septic shock, cytokine storm,

________________ occurs due to excessive cytokines “_______________” that cascades into tissue damage and organ failure.

1. fine granular cytosol

2. irregular segmented nucleus.

Neutrophils structure:

condensation of chromatin

disables cell division in neutrophils

dominant, bone marrow

neutrophils are the _____________ leukocyte produced by the _________________.

• 1% to 2%

• bacterial infections

• circulating neutrophils account for only ____________ % of the total population

• circulating neutrophils will increase ten-fold during _____________________

PAMPs, TLRs

Detection of _________ by _________ on Myeloid stem cell stimulates stem cell to produce more neutrophils

1. liver

2. spleen

3. lungs

4. bone marrow.

Majority of the neutrophil are sequestered within the

1. DAMPs

2. LPS

3. thrombin

4. histamines

P-selectin (CD62P)

endothelial cells can be stimulated from

1. .

2. .

3. .

4. .

to express ______________

adhesive protein CD11a/CD18

PAF secreted by endothelial cells triggers neutrophils to express _____________________________

leukocyte function,-associated antigen-1 (LFA-1)

CD11a/CD18 or also known as

surface of neutrophil, slowing down rolling

P-selectin can bind L-selectin (CD62L) on the _____________________ thus, __________________ neutrophil

LFA-1, complete stop

___________ is an integrin that binds to an intercellular adhesion molecule-1 (ICAM-1 or CD54), causing the neutrophil to a ________________

elastase, CD43 (leukosialin)

Adherent neutrophils also secrete _______________ that removes _________________

anti-adhesive

CD43 (leukosialin) is an ____________________ protein on the neutrophil surface

1. E-selectin (CD62E)

2. CXCL8

3. IL-1, vasodilation

4. ICAM-1, vascular permeability

Neutrophil Emigration from the Bloodstream

1. Endothelial cells activated by cytokines produce ______________________, a strong adhesive

2. IL-1 and IL-23 also induce endothelial cells to produce _______________ that attracts neutrophils

3. TNF-α causes endothelial cells to produce _______ promoting _____________

4. Neutrophils bound through _______________ also produce protein that increase ____________________ downstream

phagocytosis

once they reach the sites of microbial invasion, neutrophils eat and destroy invading bacteria through ________________

1. activation

2. chemotaxis

3. adherence

4. ingestion

5. destruction

phagocytosis process can be divided into discrete stages:

1. integrin binding, TNF-α, CXCL8, and C5a

2. cleave membrane-bound TNF-α

3. oxidants, elastase, and defensin

1. activation start after _____________ and stimulation by __________, ___________, & _________

2. oxidants activate tissue proteases that _______________________ from macrophages

3. activated neutrophils produce ___________, _____________, ___________

chemoattractants

Neutrophils crawl directly toward invading microorganisms and damaged tissues through numerous _________________

Microbial invasion 

formylated methionine groups in peptides released by bacteria, C5a from complement system

 Damaged tissues 

fibrinopeptide B from fibrinogen, hydrogen peroxide

negative charge (same charges repel)

Both cells and bacteria have _________________________, thus a neutrophil will not be able to “catch” an invader by itself

mannose receptors, PAMPs

PRRs such as ________________ can directly bind bacteria through ________

surface phagocytosis

bacterial cells may be lodged or trapped between cells can be readily phagocytosed so called __________________

NETosis

activation of neutrophils by LPS and CXCL8 will induce cell death called ___________

• neutrophil extracellular trap (NETs)

• trapped, destroyed

• ______________________include decondensed DNA, antimicrobial proteins, and enzymes from ruptured granules

• In this way, bacterial cells are not only __________, their virulence factors are also ______________

positively charged molecules, opsonins

bacteria can be neutralized by coating them with ___________________, called ____________

opsonins

promote phagocytosis by neutrophil

slow onset

antibodies are effective opsonin, but has ____________

immediate protection

complement is an innate subsystem for ________________

Type I phagocytosis, CD32, lamellipodia

___________________ occurs when antibody-coated microbes bind to __________ triggering polymerization of actin in ______________ engulfing the particle

• Mycobacterium tuberculosisreadily ingested

• Streptococcus pneumoniae

• Hydrophobic bacteria =

• Hydrophilic capsule =

• Hydrophobic bacteria =

• Hydrophilic capsule

• readily ingested =

• poorly phagocytosed =

hydrophobic

opsonization will make the cell ____________

Type II phagocytosis, lamellipodia formation

______________________ – occurs when complement-coated microbes bind to CR1, the particle sinks into neutrophil without ________________

coiled phagocytosis

in Legionella pneumophilia and Borrelia burgdoferi, the lamellipodia may wrap itself several times around the organisms, called _________________

1. decondensed DNA

2. antimicrobial protein

3. enzymes from ruptured granules

neutrophil extracellular trap (NETs) includes

Respiratory Burst

neutrophils increase oxygen consumption

Hypochlorous acid (HOCl)

kills the bacteria by unfolding and aggregating their proteins and oxidizing lipids

hydrogen peroxide

superoxide anions generate __________________

superoxide anion

NOX converts NADPH to NADP+, generating ___________________

NOX

Exposure to TNF-α or other inflammatory stimuli induces the assembly of _________

bacterial LPS

When stimulated by ____________, neutrophils can produce numerous cytokines albeit in small amounts, the large numbers of neutrophils may cause significant effects

1. short-lived, spontaneous apoptosis

2. limited phagocytic activity

3. apoptosis

Neutrophil Surface Receptors & Fate

1. Neutrophils are ___________ terminally differentiated cells with a high rate of ___________________

2. limited energy that cannot be replenished and can only do ________________

3. Inflammatory stimuli, especially oxidants trigger ____________, also involving formation of NET

1. shapes:

   • round

   • bean-shaped

   • elongated

2. lysosomes

3. veil-like ruffles

Macrophages

1.  has single large nucleus; shapes varies such as:

2. large numbers of ___________ present

3. forms ________________ due to continuous

   movement

bone marrow

macrophages originate from stem cells in? _______________

monocytes

____________ enter the bloodstream and circulate before entering tissues and developing into macrophages

neutrophils

as sentinel cells, macrophages recruit _______________

nitric oxide

In rodents, cattle, sheep, and horses, macrophage release _____________ that release nitrogen dioxide radical (toxin)

Pattern recognition receptors (PRR)

__________________ is as important surface antigen receptor

1. toll- like receptor (TLRs)

2. mannose-binding receptor (CD206)

Pattern recognition receptors (PRR) example:

cytokine mixtures

As sentinel cells, macrophages express many PRRs to detect invaders and respond by producing complex _________________

HMBGB1, IFN-y

___________ is secreted by macrophages that have been activated by LPS or cytokines such as ________

TLR2 or TLR4

HMBGB1 binds to ________________ of macrophages, monocytes, neutrophils, and endothelial cells

resident macrophage

HMBGB1 stimulates _________________ to produce TNF-α, IL-6, chemokines, and reactive oxygen species

exosomes, bacteria (PAMPs)

Macrophages also release ____________ containing _________________ that transmit signals between cells. Thus, exosomes can bind to PRRs of nearby neutrophils and macrophages leading to production of more cytokines

TNF-α / Tumor Necrosis Factor-α

• Cytotoxic

• Stimulate T cell growth

• Stimulates acute-phase responses

IL-1 / Interleukin-1

• Costimulator of Th2 cells

• Stimulates acute-phase responses

IL-6 /  Interleukin-6

• Promotes B cell differentiation

• Stimulates acute-phase responses

IL-23 /  Interleukin-23

Stabilizes Th17 cells

IL-18 /  Interleukin-18

• Promotes IFN-γ

• Production of Th1 cells

IL-12 /  Interleukin-12

Costimulator of Th1 cells

1. Phagocytosis

2. Generation of Nitric Oxide

Macrophage Functions

binding β2-integrins to ICAM-1

Similar to neutrophils, monocytes roll into endothelial cells and go into complete halt from __________________ to __________

emigrate, macrophages

Once monocytes bind, monocytes __________ to tissues and become _____________

CCL2

Stimulated neutrophils produce _________ that attracts macrophages

Elastase and collagenase

__________________________ destroy surrounding connective tissue

apoptotic neutrophils, exosomes, bacteria

Monocytes phagocytose

1. M1 cells

2. M2 cells 

two subpopulations of macrophages:

M1 cells

defend against microbial invaders and produce proinflammatory cytokines

M2 cells

reduce inflammation and produce cytokines that suppress immune responses

M1 cells

produced early in infection, when inflammation is required

M2 cells

produced late in infection, when process of healing is require

M2 cells

 does NOT produce NO

M1 cells

produce NO using NOS2

NK cells

Activated macrophages produce IL-12, activating ___________

IFN-γ

NK cells produce ________ that further activates macrophages

1. phagocytosis of bacteria by neutrophils

2. ingestion of neutrophils by Kupffer cells (macrophage that lines the sinusoid of the liver)

The process of removing bacteria occurs in two stages:

dogs, humans, and rodents

In __________________________bacteria are removed by macrophages (Kupffer cells) in the liver

ruminants, pigs, horses, and cats,

In ____________________________ bacteria are removed by macrophages that line the endothelium of lung capillaries (pulmonary intravascular macrophages)

opsonized with antibodies

removal of bacteria is enhanced when it is ______________________

proteins

tend to aggregate thus are eliminated rapidly by neutrophils and monocytes.

unaggregated proteins

_____________________ are catabolized slowly until an immune response is activated which will rapidly remove remaining protein

unaggregated proteins

rapidly remove remaining protein

• digestive enzymes

• intestinal epithelium

• macrophages

Digestive tract

• Macromolecules are broken down by ________________,

• smaller particles can be absorbed by the ________________ and into the blood.

• Particles can be removed by ____________ in the liver

• mucus flow

• lung alveoli, alveolar macrophages

Respiratory tract

• Large particles can be removed by ___________

• smaller particles can reach the ___________ where they can be removed by __________________

M2 macrophages

Recovery from inflammation is carried out by ___________________, M1 macrophages eventually convert to M2 cells

break down damaged tissues first

For M2 macrophage to repair and remodel tissues, it must ____________________________

resolvin E1 and protectin D1

Endothelial cells produce ________________________ to promote phagocyte removal and ingestion of apoptotic neutrophils

Apoptotic neutrophils

________________ produce lactoferrin that suppress neutrophil recruitment