Unit 1 Flashcards
What are commensal microorganisms?
a microorganism that consistently lives on or in the human body
- does not normally cause disease or harm
- can be beneficial
what is the microbiota?
- live in or on humans
- doesn’t normally cause disease or harm
- often provides positive benefits for human health
What are opportunistic pathogens?
a microorganism that causes disease only in ppl whose immune systems are compromised
What are parasites/how do they differ from other pathogens?
- unicellular protozoa and multicellular worms that infect animals and humans
- live within the host, causing disease
What does the innate immune system depend on?
- complement
- neutrophils
- macrophages
- NK cells
What are effector mechanisms?
the processes used by the immune system to destroy and remove pathogens from the body
What are effector cells?
any terminally differentiated cells in an innate or adaptive immune response
- responsible for killing and removing pathogens
what are memory cells?
- generally lymphocytes
- responsible for immunological memory
What are leukocytes?
- white blood cells
- lymphocytes
- granulocytes
- monocytes
What are hematopoietic cells?
any blood cell or blood-cell precursor
What types of differentiated cells are in the myeloid lineage?
- granulocytes
- monocytes
- macrophages
- mast cells
- dendritic cells
What are granulocytes?
- a type of WBCs
- irregularly shaped
- multi lobed nuclei
- cytoplasmic granules
- AKA: polymorphonuclear leukocytes
What are the types of granulocytes?
- eosinophils
- neutrophils
- basophils
What types of cells are phagocytes?
- macrophages
- dendritic cells
- neutrophils
What is pus?
- dead and dying WBCs (mainly neutrophils)
- tissue debris
- dead microorganisms
What are monocytes?
- phagocytic WBCs
- have a bean-shaped nucleus
- precursor of the hematopoietic macrophage
What are mast cells?
- cells from the bone marrow
- resides in connective tissues
- have large granules that store chemical mediators (histamine)
- interacting with an antigen produces an immediate systemic hypersensitive reaction
- play a big role in allergic reactions and anti-parasite immunity
What are large granular lymphocytes?
- AKA a natural killer (NK) cell
What are natural killer (NK) cells?
- large, granular, cytotoxic lymphocyte
- circulates in the blood
- central to the innate immune response to intracellular pathogens
- have receptors to recognize and kill virus-infected cells and tumor cells
What are small lymphocytes?
- recirculating/resting B or T-cell
What are B cells?
- one of the lymphocytes in adaptive immunity
- makes immunoglobulins in the form of cell-surface antigen receptors and antibodies
What are T cells?
- another type of lymphocytes in adaptive immunity
- originate in the bone marrow
- develop in the thymus
- has cell-surface antigen receptor
- there are various subtypes: like cytotoxic T cell, regulatory T cell, and many helper T cells
- aid in macrophage activation and antibody productionW
What are plasma cells?
- terminally differentiated B lymphocytes
- dedicated to the synthesis and secretion of antibodies
what is humoral immunity?
immunity mediated by antibodies and can be transferred to a non immune recipient
What are primary lymphoid tissues?
-site of lymphocyte development
ex: bone marrow, thymus
What are secondary lymphoid tissues?
- tissues where the immune response is initiated
ex: lymph nodes, spleen, and mucosa-associated tissues
What are lymphatic vessels?
- thin-walled vessels that carries lymph (interstitial fluid)
- transports lymph from tissues to secondary tissues minus the spleen
- transports lymph from secondary tissues to the thoracic duct
What are ILCs?
- innate lymphoid cells
- NKs, ILC1-ILC3
- don’t express variable antigen receptors
- express Pathogen-Recognition Receptors (PRR), characteristic of the induced innate immunity
What are interferons?
- cytokines with pro-inflammatory functions
- activates macrophages in innate an adaptive immunity
What are dendritic cells?
- antigen-presenting cells
- from the bone marrow
- present in secondary lymphoid tissues and can stimulate T cells, forming a bridge between the innate and adaptive immune system
- interactions between dendritic cells and NK cells determine whether the adaptive immune response needs to be made
what is the main Role of the immune system?
to protect the host from environmental microbes and toxins
What problem are their with trying to protect a host from their microbial environment?
1) live in a sea of organisms
2) doesn’t take many microbes to start infection
3) microbes are adaptable to independently evolving threats
4) can be hard for the immune system to discriminate self vs non-self.
What are the sites of extracellular infection?
- interstitial spaces: blood/lymph
- epithelial surfaces
What are the types of protective immunity for infection in the extracellular interstitial spaces?
- complement system
- phagocytosis
- antibodies
What are types of protective immunity from extracellular epithelial surfaces?
- antimicrobial peptides
- antibodies
What are the intracellular sites of infection?
- cytoplasm
- vesicles
what types of organisms infect through the extracellular interstitial spaces?
- viruses
- bacteria
- fungi
- protozoa
- worms/parasites
What types of organisms infect through the extracellular epithelial surfaces?
- bacteria
- worms
What types of organisms infect the cytoplasmic region?
- viruses
- protozoa
- some bacteria
What types of organisms infect the vesicles of the cell?
- mainly bacteria
What types of protective immunity is found in the cytoplasm of the cell?
- NK cells
- cytotoxic T cells
what types of protective immunity is found in cell vesicles?
- T cell and NK cell- dependent macrophage activation
About how many deaths are infectious diseases responsible for each year?
~14%
How do microbes evolve to hide from immunity?
- evolve into structures similar to self so that it’s hard to discriminate the infection
What are the three types of immunity?
- physical barriers i.e. skin
- innate immunity
- adaptive immunity
What are characteristics of innate immunity?
- rapid
- little specificity
- always present
- modest efficacy
What are characteristics of adaptive immunity?
- slow
- high specific, recognized precise 3D structures of microbes
- highly effective
- memory
- tolerance to self
What are the main types/areas of physical barriers?
- Skin: stratified epithelium
- Gut: single cell layer of columnar epithelium
- Lung: pseudo stratified columnar epithelium in upper airway and single cell layer of columnar epithelium in lower airway
- eyes. nose, and oral cavity: pseudo stratified columnar epithelium
What is a mechanical immunity present in all 4 types of physical barriers?
- epithelial cells are joined by tight junctions
- not permeable to many microbes
what is a mechanical immunity characteristic of the skin?
- longitudinal flow of air or fluid
what is a mechanical immunity characteristic of the gut?
- longitudinal flow of air or fluid
what is a mechanical immunity characteristic of the lungs?
- movement of mucus by cilia
what is a mechanical immunity characteristic of the eyes/nose/oral cavity?
- tears
- nasal cilia
what are chemical immunity characteristics of the skin?
- fatty acids
- beta defensins, lamellar bodies, and cathelicidin
what are chemical immunity characteristics of the gut?
- low pH
- enzymes (pepsin)
- alpha defensins, cathelicidin, lecticidins, cryptdins
what are chemical immunity characteristics of the lungs?
- pulmonary surfactant
- alpha defensins + cathelicidin
what are chemical immunity characteristics of the eyes/nose/oral cavity?
- enzymes in tears and saliva (lysozyme)
- histatins + beta defensins
What are the microbiological immunity characteristics of all 4 physical barriers?
- good microbes crowd out the bad microbes (normal microbiota)
True or false: the innate immunity is present under all mucosal surfaces?
true
What cell types are present in innate immunity?
- dendritic cells
- macrophages
- granulocytes (neutrophils)
- NK cells
- ILCs
- infected cells
What are the types of phagocytes in innate immunity?
- macrophages
- dendritic cells
- Granulocytes
What do infected cells do during innate immunity?
- secrete interferons that signal the need to increase defenses of cells nearby
What do ILCs do for innate immunity?
- send signals causing cells to die
What do NK cells do for innate immunity?
- recognize and kill virally infected cells
What are the types of effector mechanisms present in innate immunity?
- neutralization
- membrane attack “opsonization”
- targeting NK cells (ADCC)
- sensitizing mast cells
- complement activation
What soluble factors are present in innate immunity?
- interleukins (cytokines)
- complement
What are cytokines?
- secreted polypeptide signaling molecule used for intercellular communication
- soluble mediator of innate immunity
- can turn off/on immune responses
- mediate inflammation
How are cytokines delivered to other cells?
- autocrine
- paracrine
- endocrine
What are chemokines?
- subset of cytokines that specialize in regulating cell motility (chemotaxis)
- recruits cells to sites of inflammation
What do phagocytes do?
use degradative enzymes against extracellular bacteria and fuses with vesicles and digest bacteria
What is the complement system?
- assembles pores/holes in bacterial membranes to cause lysis
what are the effector mechanisms of B lymphocytes?
- complement
- ADCC/opsonization
- neutralization
What is the effector mechanism of T lymphocytes?
- cytotoxic cells
What are the soluble factors of B cells?
secretes antibodies
What are the soluble factors of T cells?
- interleukins
What are the immunity responses in B cells?
secrete surface antigen receptors (antibodies)
- antigen comes in contact
- antibodies leave cell surface and coat the microbes
- tags the microbes to get rid of them
What are the immune responses of T cells?
- T- cell receptor recognizes antigen and tags the microbes with antibodies
- cytokine secretion when antigen is recognized
- T-cells will also kill infected cells when antigen is present
What are the types of lymphocytes?
- ILCs
- B cell
- T cell
What are the immunity characteristics of ILCs?
- innate lymphoid cell
- Recognition: cytokines
- effector function: cytokines
- does not have memory
What are the immunity characteristics of B cells?
- recognition: Ig
- effector function: antibodies; antigen presentation
- has memory
What are the immunity characteristics of T cells?
- recognition: TCR
- effector function: cytokines; preforin
- Has memory
What are the immunity characteristics of Phagocytes (macrophage + granulocytes)?
- recognition: PRRs, Fc Receptor, and Complement Receptor
- Effector mechanism: cytokines, phagocytosis, antigen presentation
- has no memory
What are the immunity characteristics of NK cells?
- recognition: MHC, Stress, Fc Receptor
- effector mechanism: apoptosis, cytokines
- sort of has memory
What are the immunity characteristics of Dendritic cells?
- activated T-cells + secretes cytokines and interferons
- Recognition: Bacterial products + inflammation mediators
- Effector Mechanisms: antigen presentation
- does not have memory
What cell type do all immune cells come from?
the multi-often hematopoietic stem cell
What intermediate cell does B, T, NK, and ILC cells come from?
Common lymphoid progenitor cell
What intermediate cell do dendritic cells come from?
- common myeloid progenitor
what intermediate cell do granulocytes, mast cells, and monocytes come from?
- granulocyte/macrophage progenitor
What intermediate cell do platelets come from?
- Megakaryocyte
What does the bone marrow do?
- hematopoietic cell development
What does the thymus do?
- t-cell development after leaving the bone marrow
What does the spleen do?
- blood filter
What do lymph nodes do?
- lymph filter
What is lymph?
- interstitial/tissue fluid
- dead cells
What are the roles/characteristics of the lymphatic system?
- deals with body fluids and migrating cells outside of the bloodstream
- moves interstitial fluid around
- microbes travel lymph nodes via lymphatic vessels
- where B and T cells and phagocytes congregate
What is happening in inflammation/infection site?
- microbes release vasoactive and chemotactic factors
- factors are sensed and cytokines are secreted to make capillaries leaky
- effectors leak in (complement) + microbicidal proteins
What are diseases associated with immune system disfunction?
- autoimmunity
- immunodeficiency (inherited, acquired)
- allergy
- cancer (leukemia, lymphoma)
What is Grave’s Disease?
- a hyper-thyroid disease
What occurs in a normal pituitary/thyroid communication?
- pituitary gland secretes Thyroid-stimulating hormone (TSH), inducing the release of thyroid hormones
- Thyroid hormones go through a negative feedback loop and act on the pituitary gland to shut down TSH production
What pituitary/thyroid communication occurs in Grave’s disease?
- Autoimmune B cell makes antibodies to TSH receptor, stimulating thyroid hormone production
- causing constitutive thyroid hormone production because TSH shutdown in the pituitary gland has no effect.
What is myasthenia gravis?
A neuromuscular disease
What normal events occur at the neuromuscular junction?
- on neuronal impulse, Na+ is released into the junction
- acetylcholine receptors in the muscles receive the Na+ influx = muscle contraction
What event occur at the neuromuscular junction in myasthenia gravis patients?
- Antibodies attach to acetylcholine receptors, which are internalized and degraded
- when neuronal impulse causes an Na+ influx, there is no muscle contraction because no receptors are present in the junction
What is SCID?
- severe combined immunodeficiency
- caused by little to no B and T cells
- treated with Bone marrow transplant to get B and T cell production
What are some causes of immunodeficiency?
- AIDS
- Cancer chemo
What does immunodeficiency do?
- no adequate immune response
- susceptible to many more easily fought off diseases/infections
What are the types of therapeutics for immune system disfunction?
- vaccinations
- immunotherapy
- transplantations
what is the most major success in therapies for immune system dysfunction?
- vaccines
What was the only disease ever eradicated?
- small pox
How is cancer treated with a tumor-specific antibody?
- antibodies bind to the tumor cell
- NK cells with Fc Receptors (CD16) are activated to kill the tumor cells
How is cancer treated with tumor-specific antibody/antibody fragment conjugated to a toxin?
- antibody-toxin conjugates bind to the tumor cell
- conjugates are internalized, killing the cell
How is cancer treated with tumor-specific antibody conjugated to a radionuclide?
- radioactive antibody binds to the tumor cell
- Radiation kills the tumor cell and neighboring tumor cells
What do checkpoint inhibitors do?
- activate the immune system against cancer
- antibody drug directs T cells to kill cancer cells
What are examples of biochemical barriers?
- things in secretions
- lysozyme in most secretions
What are examples of biological barriers?
- commensal organisms in gut and vagina
What are examples of physical barriers?
- mucus
- cilia lining trachea
- skin
What are some features of epithelial surfaces that give protective immunity?
- Tight junctions
- Mucous
- Cilia
- Anti-microbial Peptides (AMPs)
What are some disease that occur from issues in epithelial surface defense?
- Cystic fibrosis (no cilia in the lungs)
- Kartageners Syndrome (cilia don’t beat, infertile Sperm/can’t swim; often develops pneumonia)
What are defensins?
- small polypeptides secreted at mucosal surfaces/ epithelial + other cells
- direct bactericidal properties
- insertion into biological membranes leading to target cell lysis
- inhibited by cholesterol
- amphipathic structure promotes membrane insertion
What are some biochemical defenses?
- sequestration of essential nutrients ( Lactoferrin/iron and Psoriasin/zinc)
- Enzymatic attack against bacterial cell wall and membrane (via lysozyme and Phospholipase A2)
What do epithelial cells secrete?
Psoriacin
What does psoriacin do?
- a peptide that kills E. coli but not staph
True or False: certain cell types/regions of the body protect against different types of microbes with different features.
True
What are the general 4 steps of immune system response?
- be ready (innate immunity)
- recognize a microbe or toxin as foreign
- contain/localize it
- Eliminate it
How does the innate immune system recognize what’s foreign?
Pathogen-Associated Molecular Patterns (PAMPs) by Pattern Recognition Receptors (PRRs)
How does the acquired/adaptive immune system recognize what is foreign?
- 3D chemical structure specific to different microbial components recognized by antibodies and T cell receptors
What are the major components of innate immunity?
- Barriers
- Phagocytes
- PRRs
What is the response to repeat infection of the innate immune system?
- Same each time, but can be trained
What are the major components of adaptive immunity?
- T and B lymphocytes
- Antigen-specific receptors
- antibodies
What is the response to repeat infection for the adaptive immune system?
- more rapid and effective with each subsequent exposure (memory)
What are the advantages of the innate immune system?
- PRe-existing receptors recognize common features of classes of microbes
- allows for immediate response to protect host
What are the disadvantages of the innate immune system?
- Pathogens evolve ways to interfere with recognition
- No specific memory for past exposures
What are the 4 hallmarks of inflammation?
- redness
- pain
-swelling - heat
What causes the 4 hallmarks of inflammation?
- increased vascular diameter and blood flow (warmth, redness)
- activation of vascular endothelium = adhesion molecule expression, increasing leukocyte binding
- Increased vascular permeability (swelling, pain)
- PMNs are the first cell type recruited to site, followed by monocytes
What is causes pus in an infection?
- many dead granulocytes that died trying to kill the infections/microbes
What is the definition or inflammation?
- local injury or infection causing release of mediator like histamines, promoting vasodilation and chemotaxis
What are the functions of neutrophils?
- phagocytosis
- ROS + RNS
- Antimicrobial peptides
What are the functions of Macrophages?
- Phagocytosis?
- Inflammatory mediators
- antigen presentation
- ROS + RNS
- Cytokines
- Complement proteins
What are the functions of Dendritic cells?
- antigen presentation
- costimulatory signals
- ROS
- interferon
- cytokines
- link innate and adaptive immunity
What are the functions of NK cells?
- lysis of viral infected cells
- interferon
- macrophage activation
How do inflammatory cells exit circulation?
1) rolling along the vessel walls due to low affinity/binding, HBonding their way along: Signaled by selectins + chemokines
2) Receive signals from infection/damaged tissue: signaled by Integrins, Ig members, and chemokines
3) arrest/adhesion of granulocytes to undergo diapedesis: signaled by Integrins, Ig members, and chemokines
4) slips through junctions: signaled by Integrins, Ig members, and chemokines
What are E-selectins?
- Carbs that bind mucins
- responsible for initial binding and rolling of neutrophils/granulocytes
What do epithelial cells do in response to damages tissue?
increase ICAM (intercell adhesion molecule) production
What do ICAMs do?
- after granulocytes increase ingrain production, they bind to them to signal for diapedesis
What are the functions of inflammation?
- recruit additional immune effector cells
- Provide a physical barrier to spread of infection (coagulation in local vessels)
- promote repair of damaged tissue
What are the 3 main functions of PRRs and Other innate immunity receptors?
- phagocytic receptors to stimulate pathogen uptake
- Chemotactic receptors guide phagocytes to site of infection
- Activate cell to secrete cytokines/chemokines that induce innate responses; influence downstream adaptive immune responses
What are some examples of PAMPs?
- sugars
- lipids
- protein modifications
- Lipoproteins
- DNA oligomers
- Super-antigens
- exotoxins
- peptidoglycan
- endotoxins/lipopolysaccharides
What couldn’t you have adaptive immunity as your first line of global defense?
- would be overwhelming for the immune system to have very precise initial immunity
What would innate immune receptors recognize on microbes?
- flagellum
- familiar, but misplaced macromolecular structures (DNA in the cytoplasm)
What are the 5 classes of PRRs?
- Toll-like Receptors (TLRs)
- C-type Lectin Receptors (CLRs)
- Nucleotide-binding oligomerization domain (NOD) receptors
- Retinoic acid-inducible gene 1 (RIG-1) helices reporters
- cGas/Sting receptor
What is the Toll-dorsal pathway responsible for in flies?
- important for immunity: mutants are more susceptible to fungal infections
- allows for the development of the front on flies (front back distinction)
What is NF-KappaB?
- a transcription factor which binds to many inducible immune system genes
- transcriptional control element inside of the kappa light-chain gene
- Binds ot IgKappa locus enhancer
Where was the NF-KappaB TF found?
- in mouse B cell lines
What happens when you remove the NF-KappaB or its binding site?
- the immune genes still work in B cells
- means its not essential for activity of light-chain gene in mice
True or False: the situation in which a factor is discovered is not necessarily its most important role.
True
What is NF-KappaB homologous in?
- Dorsal pathway as a TF
- homologous as a TF for many immune genes
What are the contents of the NF-KappaB complex?
- p50
- p65
- IkappaB
What are characteristics of the inactive form of NF-KappaB?
- IKappaB is an inhibitory molecule
- in the cytoplasm
- cactus
How is NF-KappaB activated?
- activated by the IKappaB molecule getting phosphorylated, released and degraded
- goes into the nucleus as a TF
What are characteristics of the active form of NF-KappaB?
- no longer has the IKappaB molecules
- goes into the nucleus and activates genes (kappa light-chain locus)
What is a TLR?
- Toll-like receptor
- cell-surface signaling molecule
- links microbial products to TF activation for immune gene upregulation
- binds to a ligand (specifically a PAMP)
What is the process of immune gene activation with TLRs?
1) ligand/PAMP binds with TLR
2) changes conformation which activates a kinase
3) IkB kinase phosphorylates the IkB molecule on NF-kB
4) IkB molecule falls off/gets degraded
5) active NF-kB goes into the nucleus and binds to NF-kB binding sites
6) activates genes important for inflammation and activation for acquired immunity.
What are the shape characteristics/features of TLRs?
- exterior/cell-surface domain is Leucine-rich repeats that typically form a hook
- transmembrane protein
- the interior domain is called the Toll/IL-1R domain (TIR domain)
- IL-1 is a type of cytokine
- TIR domain is a signaling scaffold and multimerization
- TIR domain has homology to cytokine signaling
- all TLRs form either homo or heterodimers on cells
Why are there so much variety in TLRs?
- each is specific for different classes of microbial products
- amount varies between species, but generally about 10
- there are extracellular TLRs and ones specialized to be in endosomes
What is special about endosomal TLRs?
- recognizes viruses and intracellular bacteria
- the leucine-rich repeat region is congruent with being on the exterior face of the cell membrane cytoplasm
- TIR domain is in the
- intracellular transmembrane protein
What do variations of MyD88 molecules do?
- binds to the cytoplasmic domains of all TLRs except 1 kind of TLR
- transmit signals from TLRs
True or false: TLR signaling pathway is not conserved in mammals and drosophila.
False
- MyD88 vs dMyD88
- IRAK vs Pelle
What other molecules can TLRs activate?
- MAP kinases
- other TFs like IRF3
What would happen if all MyD88 molecules were gone?
all but 1 kind of TLR would no longer function
What kind of genes do NF-kB regulate?
- Dendritic cell maturation
- Differentiation/Activation of T cells
- pro-inflammatory gene induction (Macrophage)
- neutrophil recruitment
- Adhesion molecules (ICAMs)
- Chemokines
- Cytokines
- Cell cycle regulators
- Anti-apoptotic factors
In general, what are C-type lectin receptors?
- requires calcium for binding
- extracellular domain binds to sugars
What are the characteristics of the Macrophage Mannose Receptor?
- C-type lectin receptor
- binds to mannose-containing molecules on many bacteria and fungi
- recognition very similar to mannose binding lectin (MBL)
- functions as a phagocytic receptor
What are Dectin-1 Receptors?
- Recognizes fungal B-(1,3) gluten polysaccharides
- switches the gluten linkage from beta to alpha
- increased alpha-(1,3) correlates to increased virulence
- virulent strains have learned to hide B-glucan so it can’t bind with Dectin-1 receptors underneath alpha-(1,3) blocks
What are some characteristics of cytoplasmic sensors of infection?
- many recognize/share the same domains
- each is homologous to others, but not the exact same
- chemical patterns that are recognized
What are NOD/NOD-like receptors?
- intracellular cytoplasmic receptors
- detects bacteria
- structurally similar to TLRs (has LRRs)
- ligand binding results in dimerization = signaling to TFs
- activation = chemokine and antimicrobial peptide production
- activation secretes chemoattractants that bring in more phagocytes
What are the ligands of many NOD/NOD-like receptors?
- bacterial degradation produces from a phagolysome.
What is a special type of cell death that NLR can trigger?
- pyroptosis via inflammasome activation
What is the process of causing pyroptosis via NLR activation?
1) TLR stimulation increases expression of IL-1B and IL-18 pro-forms (inactive forms)
2) NLRs respond to PAMPs/pathogen activity and form an inflammasome (8 NLRs)
3) Inflammasome recruits and activates caspase 1
4) CC1 cleaves prol-IL-1B, pro-IL-18, and gasdermin D to activate them
5) activated gasdermin D oligomerizes and forms a pore in the cell membrane
6) releases active IL-1B and IL-18 as cytokines/signalling molecules for other immune cells
7) holes also cause cell lysis/pyroptosis
What are RIG-1 like receptors?
- retinoic acid-inducible gene
- detects cytoplasmic viral RNA
- binds to unmodified 5’ triphosphorylated (uncapped) RNA
What is the process of RIG-1 detection and reaction?
1) cytoplasmic replication of virus produces uncapped RNA with a 5’-triphosphate (doesn’t belong there, indicates presence of a virus)
2) Viral RNA binding CARD domain opens up RIG-1 so it can now multimerize
3) RIG-1 multiuser becomes poly-ubiquinated
4) poly-ubiquinated RIG-1 interacts and binds to MAVS
5) MAVS/RIG-1 complex recruits TRAFs and induces the activation of IRF3 and NF-kB pathways
What are the parts of the RIG-1 receptor?
- helices domain
- C-terminal domain (CTD)
- CARD domain (associated with the helices domain)
- exists in its inactive form, floating in the cytoplasm
What is MAVS?
- membrane-associated virus sensor
- has a CARD domain that binds to the RIG-1 CARD domain
- bound to the mitochondrial membrane
What is the cGas and Sting receptor complex/system?
- recognizes cytoplasmic dsDNA
- activates interferons
- Sting activation via cyclic GGMP
and AAMP by cGAMP - cyclic di-nucleotides are either a direct bacterial product or synthesized by cGas DNA sensor
- some viruses can evade this system by degrading cGAMP
What is the process of cGas/Sting detection and reaction?
1) dsDNA from viruses binds to cGas, creating a cyclic dinucleotide (cGAMP)
2) cGAMP, cGGMP and cAAMP (from bacteria) bind to Sting, an ER protein
3) binding to Sting causes it to dimerize, turning into a scaffold protein
4) Sting’s dimerized cytoplasmic face can recruit proteins and kinases (TBK1) to activate TFs like IRF3 ( induces expression of type 1 interferons)
What types of Pattern Recognition Receptors are extracellular?
- TLRs
- CLRs
What types of PRRs are intracellular?
-NLRs
-RIG-1
- cGas/Sting
What is DNA microarray?
- compares all gene expression under 2 different conditions
What has DNA microarrays been replaced with?
- mRNA sequencing
What is the process of a DNA microarray?
1) Isolate RNA samples from two different conditions (normal sample + sample treated/infected with bacteria)
2) Generate cDNA
3) Labeling of probe: each sample gets tagged with a different color
4) tagged sample gets put into a hybridization array
What does it mean if a well on a DNA microarray is black?
- no RNA bound/produced/found at that gene
What does it mean if a well on a DNA microarray is red?
- more RNA is present at that gene from sample 1
What does it mean if a well on a DNA microarray is green?
- more RNA is present at that gene from sample 2
What does it mean if a well on a DNA microarray is yellow/intermediate color?
- there is a relatively similar amount/ a mixture of RNA from that gene in both samples
What can DNA microarrays tell us about different microbial infections?
- different sets of genes are differentially regulated based on which microbe is causing the infection
- pathogen-specific patterns of gene expression
what are the 2 types of phagocytic cells that recognize pathogens in the innate immune system?
- Macrophages
- neutrophils
What are the characteristics of macrophages?
- generated in the bone marrow
- migrates and lives in the tissues for its life
- lives especially in the submucosal layer of the GI tract, lungs, and liver
- from blood-borne monocytes
- involved at the very beginning of infection because they already reside in the tissues
What are he characteristics of neutrophils?
- aka polymorphonuclear leukocytes (PMNs)
- short-lived (<2 days), abundant in blood
- recruited into inflamed tissue
- Can move very fast
- uses glycolysis for energy because there is little blood flow to the tissue it enters, uses an anaerobic process like glycolysis
- use rolling and diapedesis mechanisms to leave circulation
True or False: Recognition, ingestion, destruction of pathogen by phagocytes doesn’t require an adaptive immune response.
- true
- however, T cells and antibodies make phagocytes more efficient
What are distinctive features of granulocytes like neutrophils?
- its granules are vesicles packed with antimicrobial proteins, peptides, and machinery to create oxygen radicals and kill phagocytose microbes
- many nuclei
-nuclei make it rigid and hard to squeeze through the endothelial cell junctions in blood vessels
What are the 6 classes of antimicrobial mechanisms of phagocytes?
- acidification
- toxic oxygen-derived products
- toxic nitrogen oxides
- antimicrobial peptides
- enzymes
- competitors
When do macrophages begin using/producing their antimicrobial mechanisms?
- once it receives a pathogen signal, begins production
When do neutrophils begin using/producing their antimicrobial mechanisms?
- mechanisms are always present/premade in their granules