lecture 2 Flashcards
adaptive immunity
- takes a while to get going
innate immunity
- first responders
- but both are working together
- induces adaptive response after getting things going first
- keep potential pathogens away
micorbes
- most are innocuous
- many are beneficial
- but small number can cause disease
types of microbes
- bacteria
- viruses
- parasaties
- fungi
innate immunity functions
- keep pathogens away (barriers)
- detect and destroy invading pathogens - cells detect and destroy
- the immune cells secrete molecular messages (cytokines and chemokine) that spread the word to collect an army of cells to go to infection site
most pathogens are effectively stopped by innate immunity at an early stage?
true
properties of innate immunity
- response time
- specificty
- diversity
- memory responses
- self/non discrimination
response time
- innate immunity is the first one to act
(within minutes to hours, response for pathogen)
-
specifity
- receptors
- innate immunity receptors recognize broad characersitscs of pathogens
- our immune system has co-evovled with the pathogens to recognize the board characteristics
diversity
- a limited number of conserved, germ-line-encoded receptors
- limited diversity of receptors
- we don’t need a huge number of them because they recognize a broad characteristics of pathogens
- germ-line encodedg
germ-line encoded
- specificity of the receptors is encoded in the genomes is passed through the progeny, does not change
- adaptive immunity receptors are not the same case
memory responses
- no memory for innate immunity
- difference from adaptive
self/nonself discrimination
- good at detecting the broad characteristics of pathogens that are not present in self
- recognizing between self and non self
- innate immunity rarely fails at this distincition
innate immunity is non-adpative
- true
- at first exposure to pathogen, it acts first and has certain magnitude and speed for response and takes a few days
- next time it is exposed to same pathogen, acts the same way
- same response to same pathogen every time
adaptive immunity
- starts faster when exposed to same pathogen again
- immunnological memory
- innate is NOT adaptive
innate immune defences
- anatomical barriers
- immune cells
- proteins
anatomical barriers
- skin
- tissues
- commensal microbiota
immune cells
- detect andestory pathogens
- white blood cells
- leukocytes: phago and lympho
proteins
-secreted by cells
- cytokines
- complement proteins
- passes message along to other cells and imitates adaptive immunity through signalling
mechanical forces
- within the digestive and respiratory tract that keep things flowing and out our systems
epithelia
- digestive tract and resp tract exposed to outside, gi tract
- main portals of entry
- layered with epithelia that has specific barriers for protetion
eptihelial cells characteristis
- tight junctions
- regneration
- desquamation
- secretions
tight junctions
-molecualr structures between epithelial cells
- keep things tight and together
- nothing can sequence between the cells
regernation
- regernate quickly to replace dead cells
desquamation
- shedding helps remove attached pathgoens
- will shed themselves when pathogen attaches
- pathogen is eliminated with them
secretions
- enzymes
- am peptiedes
- ## mucus
first line of defense
skin (refer to diagram)
corneal layer
(in epidermis)
- keratin shield
- keratinocytes underneath are specialized epithelial cells that produce and secrete keratin
- when lose uncle they form the cells of the corneal layer
- thick, strong layer
dermis
- immune cells patrol tissue for anything that may breach the barrier
goblet cells
- in respiratory tract
- produce components of mucus (musings)
- mucus are secreted to outside of epithelia.
have cilia
cilia
- keeping things flowing
- mechanical forces prevent the pathogens from entering our tissues
CF
- Collapsed cilia
- thick, dry mucus
- makes CF lung a perfect environment for bacteria to thrive
- mutations in CFTR (make less or none)- dry condensed mucus collapses cilia prevents things from flowing
mucocilliary clearance
- MCC
- defective in people with CF
GI tract
- paneth cells
- goblet cells
paneth cells
- special epithelial cells
- secrete defnsins into gut
defensins
- am peptides
- prevent pathogens from going and colonizing in gut
important portals of entry for pathogens
- gut and digestive system
defective tight junctions
- leaky gut syndrome
- results in inflammation
- things filter in
- disrupt healthy epithlia
- ## people with IBD (inflammatory bowel disease)
chemical defenses
- secreted by eptuherlial cells
- can be microbicidal or microbiostatic
- e.g. lysozyme
- am peptides
microbicidalq
- kill pathogen
microbiostatic
- prevent pathogen from replication
lysozyme
- made in tera, breast milk, saliva
- effective against gram positive bacteria
- breaks down peptidoglycan (thick layer in gram positive, easily accessible to lysozyme), exposes the cell membrane, causes lysis
- glycosidaase
am peptides
- human body makes 21 different types (defensives)- other organisms make am peptides as well
- phoplipid bilayer is negative charge and defensives are positive
- attraction
- creates pores, intteruptions to membrane (in bacterium fungi and some viruses)
short cationic (pos charge) peptides
defensives cathelicidins, histatins
microbiome
- pretty much on every point of entry for pathogens
- is shaped from birth to adulthood (genetic and environmental factors)
- shifts rapidly at the beginning of life (inoculated with mother’s microbiome)
our immune system and microbiome
- we have adapted our immune system to not recognize our microbiome
chron’s disease
- inflammatory bowel disease
- chronic inflammation of gut epithelia
- genetic and environmental factors
- disrupted microbiome (consequence of disregulated immune system)
- affects proportion of microbiome that is healthy and altered microbiota can affect the immune system
gut microbiome
- important for digestion
- keeps pathogens from growing
- competition for nutrients
what happens to gut microbiome the u take atnibiotics
- wipes out healthy microbiome in gut
- opportunistic pathogens that are part of microbiome that were kept in check by healthy gut microbiota
- clostridium difficiae, resistant to many antibiotics for example can colonize in gut
COVID
- disruption of healthy microbiome in gut
- ## Microbial dysbiosis
microbial dysbiosis
opportunistic pathogens are able to outgrow the good microbes, cause problems, inflammation, etc
opportunistic pathogens
- regular pathogens cause problems healthy individuals
- these only cause problems in specific conditions
- e.g. listeria affects immunocomporised, pregnant, people)
- can be part of microbiome but are kept in check by other members of micriobiome- but when things change
barriers work together (at same time)
- epithelial cells
- tight junctions
- goblet cells
- am proteins are in the inner mucus layer
pathogens can breach
- might make mcuus binding proteins to attach to mucus
- flagella to swim through mucus
- secreted musinases to break down the musin
- things to attach the cells, and internalize cells to come into our tissues
when barriers fail
- barriers breached
- infection (in our tissues)
uropathogenic escherichia colipa
-nhave little hair like structures that adhere to surface of pethelial cells of urinary tract
- can case UTIS
pathogens in tissues
- can be contra or extracellular
extracellular
interstitial spaces (between cells), blood, lymph, epithelial surfaces (e.g. U Coli),
intracellular
- cytoplasmic (grow in cytoplasm)
- vesicular (grow in vesicles)
all known pathogens
have extracellular phase. only some have intracellular phase. immune system has diff strategies to deal with both of these
bacteria
- nuclei that is not membrane bound
- duplicate by binary fission (duplicate their contents, split to two cells)
- most live extraveullaurly
- some intracellular bacteria (both extra and intra phases)
viruses
- non cellular
- not really alive
- have DNA or RNA in a capsid
- unable to replicate without cell’s genome
- have extra phase must go intra to reproduce
all versus shave both an extra and intra phase
types of pathogens
- extra only (can attach to the epithelial surfaces) e.g.
- or both e.g. Listeria for ex
-ones tha grow in vesicles/cytosol
true or false: innate immunity Is germline-encoded
true
important features of epithelial cells
- form tight junctions
- shed to release pathogens
- secrete antimicrobial peptides
- secrete mucus
how does microbiome protect us against pathogens
- competing with other bacteria for nutrients
- our microbiome,e DOES not phagocytose on pathogens
- we do not want microbiomme to stimulate inflammation
- it forms a protective layer over epithelial cells.
