MIC 319 Exam III Flashcards
Eckhard Podack
dscovered immunology and cancer therapy
Intracellular bacteria
Kills host cell to kill pathogen by advantagious invasion
Can be eliminated only by a cellular immune response
Bacteria finds a way to escape the phagolysosome
extracellular bacteria
Does not invade cells, but uses small soluble molecules to get rid of bacteria
can also adhere to epithelial surface (v Cholera)
Examples of intracellular bacteria
chlamydia, tuberculosis, listeria, salmonella, yeast, invasive e Coli
Examples of extracellular bacteria
Strep, Staph, Influenza, v Cholera, e Coli
immediate innate response
0-4 hours, pathogen is greeted by small soluble particles that try to knock it out
induced innate response
4 hrs- 4 days, inflammation, fever, acute response, recruitment of effector cells to help the soluble particles
adaptive response
4 days- end of infection or death of host, B and T cells develop into effector cells and move to the secondary lymphoid to help take out pathogen
armed forces of immune system
barriers
recognition and recruitment of local immune response, reinforcements (innate inflammation and adaptive immune response)
classical killing
- toxic oxygen derived products- O2, H2O2, Oh-, HCl
- toxic nitrogen oxidase- NO
- enzymes- gram positive bacteria are knocked out by digestion of cell wall. Lysosome uses acidic pH to break down microbes
macropinocytosis
cell drinking, eruption of membrane ruffles to engluf fluids back into the endocytic pathway. r\Requires extensive actin mobilization. Occurs in all cell types!
autophagy
engulfment of cytosolic material. autophagosomes fuse with lysosome to take out engulfed material. Occurs in all cell types!
receptor medated endocytosis
actin independent internalization of small molecules and turning them into clathrin coated pits or caveolae
phagocytosis
Ingestion of small particles using macrophages, neutrophils and dendritic cells. PRRs are stimulated to speed this process through the activation of GPCR which causes inflammation and activates a receptor: compliment receptors, mannose receptors, Fc receptors, Dectin 1 receptors, lipid receptors.
types of phagocytosis
opsonic
non opsonic
triggered
formation of phagosome
- probing using actin related proteins
- particle binding and receptor clustering
- phagocytic cup formation
- phagosome closure
inhibition of phagocytosis by Yersinia and Psuedomonas
Type III secretion is shut off by YopH and YopE leads to distruction of actin microfilaments
traditional intracellular killing
bacteria is internallized and broken down by phagolysosome
organization of the lysosome
- contains acidic hydrolases which makes the pH acidic due to the proton pump between the cytosol and the ATP in the lysosome mebrane
- intersection between endocytic pathway and secretory pathway
- digests pathogens from phagocytosis, endocyosis and autophagy
lysosomal diseases
- Gaucher’s disease- mutation for gene encoding the breakdown of glycolipids
- I cell disease- deficiency in enzyme that tags mannose 6 phosphate onto the lysosome enzymes in the golgi
respiratory burst
the rapid release of ROS (O2 and H2O2) and the production of NO from NADPH
superoxide and nitric oxide generation
iNOS- produces NO
NOX (in inflammed area with MPO)- produces O2, H2O2, OH- and HCl
ROS and NO: a benefit or a threat
- can damage cellular proteins, lipids and nucleic acids of infected host cells or bacterial cells and can signal, control inflammation, vascular tone and injury
- can also damage healthy DNA, RNA, proteins and mitochondria which would induce apoptosis
How does ROS come about?
PNOX- phagocytic superoxide NADPH molecule which in the flavocytochrome has subunits gp91phox and p22phox as helpers
neutrophils jobs in intracellular killing
phagocytosis, degranualizes and NETs pathogen by activation Rac2 which casues death, acidification, O2 formation and pus
G protein coupled receptors intitate phagocytosis and ROS activation
- ligand binds G protein to GPCR
- respiratory burst forms alpha and gammabeta proteins which cleaves GTP to GDP
NOS types and induction
- induced by IFNg, LPS and bacterium
- iNOS creates the most No (in all cells)
- eNOS- endothelial cells
- nNOS- neuronal cells
Interactions of ROS and NO
thiols, metals, tyrosines, nucleotide bases and lipids
CGD
genetic deformation of genes encoding NADPH oxidase units
pathogen recognition
- phagocytic cell must differentiate between self and bacterium
- must react to pathogen fast and lethally to prevent intracellular replication
- non pathogen phagocytosis requires an infammatory response
- connects to a PRR for recognition
Types of PRRs
TLR, NLR (NOD), Dectin 1, RLRs, cGAMP, cGAS, STING
Examples of TLRs
TLR 4- lipopolysaccharides
TLR 5- flagella
TLR 1,2,6- lipopeptides
TLR 7,8,9- viral and bacterial RNA and DNA
** all (except 3)- activates transcription factors NFkB, AP1 and IRF 3/7 to cause inflammation and bring type I interferons
what was toll first identified as?
- fly immunity to fungal infections
- ebryogenesis and dorsal ventrical axis
- found by Medzhitov and Janeway
toll like receptors job description
detect PAMPs and initiate signaling for cytokine production, phagocyte recruitment and killing
TLR4- TRIF and myD88 pathway
- secretes type I interferons and TNFa to form inflammatory cytokines
- takes place in the cell surface, endosome and phagosome
signalosome
area in which phagosytic cells can differentiate between live and dead e Coli and can recruit other effectors if necessary
NOD or NLRs
- intracellular sensors that can detect products derived by intracellular pathogen (peptidoglycan) and then produces NFkB
- grouped based on N terminal domains
- NLRa, NLRb, NLRc (NOD1 and NOD2), NLRp
NOD 1 and NOD 2
NOD 1 detects DAP on gram negative bacteria
NOD 2 detects MDP on all other bacterium
Inflammasome
-where caspase 1 is activated to release IL1B
-causes pyroptosis which causes the release of the cytosolic contents and cell suicide (mostly in macrophages and dendritic cells)
pyroptosis is much stronger when perforin 1 is activated byNLRC4 and NLRP1B than NLRP 3
additional caspases in humans and mice (NBD-LRR)
mice- CASP11 and 12
humans- CASP4 and 5
cytosolic DNA sensing (STING)
cGAS binds to DNA to form cGAMP which uses ATP and GTP to activate STING which stimulates IFN genes (positive feedback)
STING in therapy
in cancer this pathway impedes on cell transformation and replication
in HPV and HIV a person without STING is much more effected
STING is a vaccine adjuvant in mucosal setting
keratinocytes
found on the skin, can recognize PAMPs and DAMPs and attack usng TLRs and the inflammasome
the skin as an immunological organ
- SALT and SJS, both show that skin is a traffic guard- immunoserveillance
- 20 bil T cells on skin
- early exposure to microbes on skin stops inflammatory skin conditions
How is all skin different
commesal microbiota in different areas have different confgurations of 16s rRNA, dampnesses, exposure to sunlight, oiliness, etc
Neonatal care and tregg
tregg helps babies grow their skin microbiotaa and not have as many skin conditions in the future
gamma delta t cells
- first line of defense
- YDelta chain receptors
- found in skin, intestines, lungs and reproductive tract
occludin downregulation
reduces YDelta chain receptoes in epithelium and increases migration speed of YDelta T cells which requires perforin 2
tight junctions
promotes skin barrier function
MRSA survival
in order for intracellularr MRSA to be killed there must be perforin 2 to form YDelta T cells
MACPF containing pore forming proteins jobs
- kill extracellular bacteria- C9/ polyC9 complement
- kill cancer cells- perforin 1
- kill intracellular bacteria-perforin 2
perforin 2
- ancient trans membrane, pore forming protein containing MACPF
- without P2 intracellular bacteria can not be killed becasue P2 fuses with the phagosome to kill bacteria
- ROS, NO and lysozyme enhance P2 killing skills
- all healthy cells have P2 (from sponge to human)
perforin 2 defficiency
- defficiency in P2 will cause mice to die
- P2 must be activated for septic shock, necrosis or inflammation to occur
Where is MACPF domain in P2
located in the membrane vesicles which shows P2 has ability to kill targets, cytoplasm domain signals killing
P2 deficiency proves what?
because P2 is necessary, ROS, No and lysozyme are further along the chain and P2 must first perforate (form pores) the bacteria in order for ROS and NO to get to it for later death
P2 and non pathogenic bacteria
commensal bacteria does not kill P2 defficient mice, but only pathogenic bacteria does, P2 is rate limiting in bacterial killing
P2 defficiency in humans
- Humans without P2 will be infected continually with avium intracellulare, pseudomonas aeroginosa, and aspergillus
- will not have inflammation or die of septic shock and tissue damage
- causes resistance to colitis
cytoplasm has conserved signals for P2 activation
lysines (K)- proteolytic cleavage
serines (S) and tyrosines (Y)- phosphorylation
P2 killing complex
Ubiquitin like protein- can signal for degradation of proteasome, alter cell location, affect activity and prevent protein interactions, regroups P2 to fight infection
*** requires neddylation of NEDD8 or UBL will be inactive
only two ways that pathogenic bacteria can get around P2
suppress inductionof P2 transcription
Block P2 activation at: phosphorylation, translocation, ubiquitylation, polymerization
ubiqutination
steps: activation (E1), conjugation (E2), ligation (E3)
ring ubiquitin ligases- final step to form substrate
CIF (e Coli), CexE and MLN4924 (inhibitor od NEDD8), y Tuberculosis and b Pseudomallel
deamidate and block NEDD8 activation and P2 killing using T3SS and convert to GLU40
Listeria
ubiquitous gram positive bacteria in the environment which causes foodborne disease known as listeriosis and also causes Tiger River disease
which barriers can listeria traverse
brain and placental which can result in miscarraige, premature delivery, infection of new born or stillbirth
what causes listeriosis?
grows at refrigeratiion temperatures, can get into soil or be carried in meat and dairy (cold cuts, soft cheeses and unpasteurized milk)
symtpoms of listeriosis
first symtpoms: fever, muscle aches, nausea and diarrhea
nervous system symtoms: headache, stiff neck, confusion, loss of balance, convulsions
steps of listeriosis
- escape the membrane vesicle
- replicate in cytosol
- changes shape of the cytoskeleton
- actin polymerization helps with entry
- CD8+ T cells mediate clearance of listeriosis
listeriosis virulence factors
- internalin A + E allows bacteria in the epithelium
- internalin B binds hepatocytes in GI tract
- Act A 2- responsible for actin based motility
- listeriolysin O- moves bacteria from vacuole to cytosol
- internalin P allows it in placenta
pregnant women are more likely to have listeriosis than any other group, why?
the infection in the placenta can migrate into the mothers liver and spleen causing the mother to be further infected
SYN
SYN blocks infection from mother and placental barrier, but due to clots they can become damaged
innate immune response for listeriosis
- macrophages such as kupffer cells initial killers that use ROS and NO to be successful
- macrophages secrete TNF and IL12 to increased effectiveness of the macrophages
innate immune receptors of listeriosis
-TLR2- lipoproteins and peptidoglycan
-TLR5- flagella
MyD88- starts almost all TLR signals
NOD2 and NALP3- recognize listeria easily
positive regulatory factor A
transcription activator of genes for listeria pathogenesis, glutathione is the activator
what sets listeria apart in terms of T1I
T1I are beneficial to listeria by making it grow, not other types of bacteria have this effect
