lecture 10) the innate immune system

Question 1

give 3 basic characteristics of the innate immune system

Answer 1

no immunological memory
non specific
immediate response

Question 2

what does the hummoral branch of the innate immune system refer to?

Answer 2

complement
enzymes
cytokines

Question 3

what does the cellular branch of the innate immune system refer to?

Answer 3

phagocytes
natural killer cells
pattern receptors

Question 4

what is involved in complement immunity?

Answer 4

molecules that aid immunological processes eg clotting, membrane attack

Question 5

what do phagocytes do?

Answer 5

engulf material

Question 6

where are the immune cells generally found?

Answer 6

circulation

Question 7

what are the exceptions of immune cells being found in circulation

Answer 7

alveolar macrophages

M cells

Question 8

what are alveolar macrophages?

Answer 8

specialised macrophages of the alveoli

Question 9

what are M cells?

Answer 9

specialised epithelial cells of MALT

transport antigens from lumen to immune cells

Question 10

name 5 different types of phagocytes

Answer 10

monocytes
macrophages
dendritic cells
neutrophils
mast cells

Question 11

bacteria taken up by what process and where are they destroyed?

Answer 11

taken up by endocytosis

destroyed in the phagolysosome

Question 12

what is the cytosome and what does it contain?

Answer 12

the cell body excluding the nucleus

contains regulatory compounds

Question 13

describe the changes in pH down the pathway that bacteria enter and explain the impacts this has on the bacteria

Answer 13

pH decreases down the pathway

becomes a more hostile environment for the bacteria to live in

Question 14

what enzyme do lysosomes contain and what does this enzyme do?

Answer 14

lysozyme

breaks down peptidoglycan

Question 15

what happens when lysozyme acts on the bacterial vesicle?

Answer 15

it ruptures and releases the products that can be recognised by the adaptive immune system

Question 16

what 3 categories of pattern recognition receptors (PRRs) can be engaged during phagocytosis?

Answer 16

PRRs to mediate phagocytosis
PRRs to initiate inflammatory response
PRRs that mediate and initiate

Question 17

why is it important to have more than one category of PRR?

Answer 17

bacteria have evolved resistant mechanisms againsr PRRs

Question 18

what does the mannoes receptor recognise?

Answer 18

sugar

Question 19

what category does the mannose receptor fall into?

Answer 19

mediates phagocytosis

Question 20

what domain does the mannose receptor have?

Answer 20

carbohydrate domain

Question 21

give 3 characteristics of the carbohydrate protein domain in the mannose receptor

Answer 21

not much of an intracellular protein domain
not involved in signal transduction
mostly outside (prob passing through and reaching out)

Question 22

give an example bacterium that uses the mannose receptor

Answer 22

virulent strains of mycobacterium tuberculosis

no inflammatory response

Question 23

what does M. tuberculosis do to combat the innate immune system?

Answer 23

sits in early endosome
has proteins that prevent fusion with lysosome
last vesicle will be phagolysosome

Question 24

what does L. pneumoniae do to combat the innate immune system?

Answer 24

arrests the pathway

Question 25

what does S. typhimurium do to combat the innate immune system?

Answer 25

decreases pH to prevent fusion

Question 26

what does F. tularenisis do to combat the innate immune system?

Answer 26

escapes the pathway

Question 27

what are TLRs?

Answer 27

toll like receptors

Question 28

what are TLRs used in conjunction with?

Answer 28

mannose receptor

Question 29

describe the composition of TLRs

Answer 29

dimeric transmembranal

Question 30

what do TLRs recognise?

Answer 30

different cellular components

Question 31

what do TLRs do?

Answer 31

transduce the signal through the cell to increase the transcription of certain cytokines by increasing the trancription factor

Question 32

what are NLRs?

Answer 32

nod like receptors

Question 33

why type of domain do NLRs have?

Answer 33

nod-like domain

Question 34

what type of repeats do many NLRs have?

Answer 34

leucine rich repeats

Question 35

are NLRs found on the membrane?

Answer 35

no, TLRs are found on the membrane to ensure they dont escape

Question 36

when phagocytes recognise bacterial cells, what do they signal for?

Answer 36

an increase in the production of chemokines and cytokines

Question 37

what do chemokines and cytokines do when phagocytes have recognised the bacterial cell?

Answer 37

recruit more vigorous immune cells eg killer T cells

Question 38

how do bacteria counteract recognition and killing?

Answer 38

escape from vacuole to cytoplasm

Question 39

how do bacteria escape from the vacuole to the cytoplasm when counteracting recognition and killing?

Answer 39

by the action of listeriolysis

Question 40

where does listeriolysis come from?

Answer 40

listeria monocytogenes, cholesterol dependent cytolysin

Question 41

name 3 characteristics of M. tuberculosis for the inhibition of phagolysosome fusion

Answer 41

paucity of vacuolar H+ ATPase inefficient luminal acidification due to less H+ inadequate levels of mature lysosomal hydrolases

Question 42

what does latent TB do to prevent phagolysosome fusion?

Answer 42

later in life/when immunocompromised, sits asleep in phagosome but will prevent fusion by preventing acidification

Question 43

what does autophagy target?

Answer 43

portions of cytoplasm, organelles or proteins that have been damaged for lysosome degradation

Question 44

how does autophagy work?

Answer 44

autophagosome binds with lysosome to break down products that can be reused

Question 45

when is autophagy beneficial?

Answer 45

when clearing disease

Question 46

how does autophagy start?

Answer 46

isolation membrane forms, elongates and closes to form double membrane bound vesicle (autophagosome) autophagosome fuses with lysosome = autolysosome leading to degradation of cytoplasmic contents inside autophagosome

Question 47

what type of genes are responsibe for autophagy?

Answer 47

ATG genes

Question 48

how do bacteria cope with autophagy?

Answer 48

selectively target cytosolic molecules/structures eg intracellular pathogens (xenophagy), damaged mitochondria (mitophagy) and protein aggregates (aggrephagy)

Question 49

what is LLO?

Answer 49

listeriolysin O

Question 50

how do membranes form?

Answer 50

LC3 - mammalian homologue of atg8 diff molecules embed membrane protein and ubiquitin stamp protein to signal its damaged formation of lysosome starts and autolysosome forms

Question 51

what secretion system does shigella use to induce cell death?

Answer 51

T3SS

Question 52

what effect of T3SS can repress autophagy?

Answer 52

IcsB

Question 53

why would a virulence factor like LLO want to elicit autophagy?

Answer 53

upon vascular escape autophagy is an intracellular catabolic process targets cellular or foreign material this doubles membrane vacuoles for degradation through fusion with lysosomes

Question 54

why is listeria at increased risk of running autophagy machinery?

Answer 54

cholesterol dependent

Question 55

name the 2 possible pathways of autophagy in listeria infections

Answer 55

persistent infections | fusion with lysosome

Question 56

what type of phagocytosis happens in autophagy of persistent liseria infections?

Answer 56

LC3 associated phagocytosis involving SLAPs

Question 57

what type of phagocytosis happens in autophagy of liseria infections via fusion with a lysosome?

Answer 57

ActA + Cm LC3 autophagy autophagosomes form

Question 58

describe autophagy in Burkholderia pseudomallei infections

Answer 58

bacteria wants to escape from the vacuole therefore secrete an effector to activate polymerisation so it can spread and create infection/disease

Question 59

why is diet and health an important influence in immunity?

Answer 59

normally a competition between the host and the bug to see who will win - not usually due to the immune system not working; can be down to the efficacy of the immune system and the bugs defence mechanisms