Lecture 3 aka lect 2

Question 1

what are the costs of having sensitive host response systems

Answer 1

-autoimmune disease
-allergies
-very fast at controlling the damage but is non specific which means that it can be dangerous

Question 2

can you name 3 was in which structure follows function in our immune system

Answer 2

-epithelial cells that try to cover the maximum
-dendritic cells that have dendrites that reach out to show off their antigens
-monocytes that get bigger once they differentiate into macrophages so that they can eat

Question 3

the gut rapidely replenish itself and the … cells remake themselves rapidly

Answer 3

the gut rapidely replenish itself and the epithelial cells remake themselves rapidly

Question 4

what is the reason why we are waterproof

Answer 4

our dead cells

Question 5

what are vilis

Answer 5

it is in the gut and it covers the whole small intestinal tract they kinda protrude: they are these finger like protrusion that are covered by mucus and bacteria = increase the surface area

Question 6

what is the crypt in the gut

Answer 6

the bottom cells of the gut, they are stem cells that are rapidly proliferating and they rise up so that they can differentiate

Question 7

what is on the top of the gut like the type of cells

Answer 7

mostly made of enterocytes that help absorb nutrients from the lumen or water from the intestinal contents also goblet cells are at the top: they make mucus
-After the top cells, they will go through apoptosis and go into the tract, that fast replenishing is so that we don’t get cancer

Question 8

true or false: the more differenciated you are the less you are proliferating

Answer 8

true

Question 9

true or false: the gut regenerates slowly

Answer 9

false it regenerates fastly
because lots of stuff is in your gut like microbes, fungi, phages etc, we need to protect ourselves

Question 10

what does Ki67 do

Answer 10

marks rapidly proliferating cells aka stem cells at the base of the vili

Question 11

what are covering the villi

Answer 11

mucus and bacteria

Question 12

what is epcam

Answer 12

it is a molecule that is expressed on the surface of epithelial cells that helps connect those epithelial cells along the surface of the vili

Question 13

what does cd45 do

Answer 13

it marks all hematopoietic cells aka all immune cells express cd45 and they line up inside the vili under the epithelial layer and these are a lot of tissues resident cells, they will sense stuff that is inside the epithelial cells

Question 14

why do we have intracellular and extracellulr receptors

Answer 14

because we have extracellular ad intracellular pathogens like viruses and bacteria

Question 15

true or false: epithelial cells are phagocytic

Answer 15

false they absorb nutrients and they are not really phagocytic

Question 16

what are the commonalities between all these pamps and TLRs

Answer 16

There are commonalities between all of these pamps like Toll like receptors and some alarmins: they all stimulate NFkB which is an important TF factor for driving an inflammatory response

Question 17

what is TLR-4

Answer 17

TLR4 is a transmembrane receptor that activated through this adaptor receptor called MyD88

Question 18

true or false: almost all tlr signaling gores through MyD88

Answer 18

true

Question 19

what is the other type of signalling of TLR signalling

Answer 19

TRF dependant signalling

Question 20

what is one consequence of almost always using myd88 pathway

Question 21

what does myd88 pathway do q

Answer 21

it phosphorylated nfkb that will then travel to the nucleus on DNA to upregulate the transcription of mhc and costimulatory molecs

Question 22

what are nods

Answer 22

they are able to recognize intracellular peptidoglycans on intracellular bacteria which means that they are able to recognize both gram - and + bacteria and then turns on the immune system

Question 23

true or false: Myd88 is conserved in all tlrs

Answer 23

true
is conserved in all TLRs allows us to be highly responsive to different stimuli but what specifies that stimuli is all the other signals ij the context of an infection or tissue damage

Question 24

true or false: epithelial cells are considered sentinel cells

Answer 24

true

Question 25

true or false: TLR signalling promotes separation of the microbiota and the small intestinal surface

Answer 25

true

Question 26

16S is only expressed in ....

Answer 26

bacteria which we can use a dye to bind to that specific rna

Question 27

what does dapi stains for

Answer 27

all nucleated cells

Question 28

what did the scientists see after they stained using dapi and for 16s

Answer 28

they saw that there was this barrier/gap between the nucleated cells and the bacteria present

Question 29

what happened to the mouse when myd88 was ko

Answer 29

there was no gap

Question 30

which cells express myd88 and where are they

Answer 30

all immune cells macrophages and innate immune cells and they are in the mucus

Question 31

true are false: the further away you get from the vili, the less there are bacteria

Answer 31

As you can see on the pic, as further as you get away from the villi tips, the more you get an increase in green fluorescence meaning that there ia s a gradient of bacteria

Question 32

How to test whether an epithelial cell can directly respond to a microbe through MyD88 dependent pathway?

Answer 32

cre lox

Question 33

how does cre lox work

Answer 33

-You generate LoxP sites which are very specific sequences of DNA and you engineer these 2 to flank a a gene of interest ex: MyD88 gene in one mouse -You then cross that mouse that expresses CRE recombinase which is an enzyme that will cleave at LoXP sites -In the case of the epithelium, there is a gene called Villin that all cells have -So this mouse expresses CRE recombinase at anytime aka a cell expressing villin -The 2 mouses described are breed -You now generate a progeny that contains 1 allele of the Vilain Cre and is homozygote for the LoxP flank MyD88 target gene, so now only MyD88 will be KO in the epithelium since only epithelial cells that have the Cre recombinase attached to the Villain

Question 34

what happenend to the mouse once cre lox was used and what does it show

Answer 34

-The gap was kinda loss Gene had a loss of function to show that myd88 was important in the gut -Was a loss of function experiment because they deleted a gene to show that it was important for smth -Shows that myd88 in the epithelium is necessary to maintain the gap but it does not show that it is sufficient

Question 35

gain of function with the myd88 cells

Answer 35

Gain of function experiment to show that MyD88 in epithelial cell is sufficient -They took a KO mouse of MyD88 and they put in a transgene so that only Villain expressing cells are going to be the ones that express MyD88 and all the others are KO -They showed that this restored the gao aka it is sufficient

Question 36

MyD88 is .... and ...... for inducing a barrier between the epithelium and the commensal bacteria

Answer 36

MyD88 is necessary and sufficient for inducing a barrier between the epithelium and the commensal bacteria

Question 37

WHy does MyD88 signalling into the epithelium drives the formation of the gap?

Answer 37

Epithelial cells are good at making antimicrobial peptides that have direct bactericidal activity

Question 38

where is reg iii gama expressed

Answer 38

it is a protein that is highly expressed all around the intestinal epithelial so that they can kill bacteria

Question 39

true or false: in myd88 ko mouse regiii gamma was overexpressed

Answer 39

false, it was gove

Question 40

what happend to reg iii gamma when myd88 is overexpressed

Answer 40

too much regiiigamma

Question 41

Which experiment can you do to test that RegIII gamma is responsible for the whole MyD88 dependent gap thing

Answer 41

KO RegIII gamma, you KO the gap

Question 42

is the dmz good for us or is it good for the bacteria

Answer 42

-Both -The mucus prevents the RegIII gamma from spreading to our intestines and kill everything; it provides a gradient -Mucus is there to trap the RegIIIy so that the healthy bacteria to metabolize food and stuff, and can still be there and absorb nutrients

Question 43

what are sonme inducers of inflammation

Answer 43

-pamps ex: dr-rna -damps -allergens -Injury detected by alarmins that are secreted by damaged or dead cells -Sterile inflammation: inflammation induced in the absence of microbes

Question 44

does sterile inflammation show matzinger or janeway

Answer 44

janeway

Question 45

Perks and non perks of tissue resident

Answer 45

-Non perks: they are non specific, could lead to mount a response against a self antigen (could be a mistake of interpretation of self or non self due to the fact that the self and the non self are looking similar aka molecular mimick) -Perk: the are fast acting