W3 Flashcards
(26 cards)
What are the three main types of pattern recognition receptors (PRRs)?
Membrane-bound phagocytic PRRs, secreted (free) PRRs, and signal-transducing PRRs.
What are PAMPs and MAMPs, and how do they differ?
PAMPs (Pathogen-Associated Molecular Patterns) are molecules found on pathogens, while MAMPs (Microbe-Associated Molecular Patterns) are microbe-derived molecules like specific metabolites or peptides
What are DAMPs, and what triggers their release?
DAMPs (Damage-Associated Molecular Patterns) are host-released molecules due to necrosis or pyroptosis induced by pathogens.
What happens when a pathogen breaches the epithelial layer?
Complement activation occurs, innate immune cells in MALT or GALT are activated, macrophages ingest the pathogen, and neutrophils are recruited.
What immune cells recognize PAMPs or MAMPs?
Macrophages, dendritic cells (DCs), and natural killer (NK) cells
What is the function of the phagolysosome in innate immunity?
It carries out oxidative bursts that kill ingested pathogens
What is NETosis, and what does it achieve?
NETosis is the release of neutrophil extracellular traps (NETs) to increase inflammatory mediators and wall off threats
Which type of PRR is involved in phagocytosis?
Membrane-bound phagocytic PRRs
What are examples of phagocytic PRRs?
Complement Fc receptor, mannose receptor, scavenger receptors, and dectin-1 receptor
What do signal-transducing PRRs do?
They recognize microbial presence and initiate signal transduction pathways leading to an immune response
What are the two main locations of TLRs?
Some are cell surface-associated (TLR2, TLR4, TLR5), while others are intracellular (TLR3, TLR7, TLR9)
What is the ligand for TLR4?
Lipopolysaccharide (LPS), found on Gram-negative bacteria
Which TLR recognizes bacterial DNA?
TLR9
How does TLR activation set the stage for the adaptive immune response?
It induces early innate immune activity, activating antigen-presenting cells (APCs) and other phagocytes
What structure do TLRs have?
They are horseshoe-shaped transmembrane proteins with a leucine-rich repeat (LRR) domain for pathogen recognition
What happens when a TLR recognizes a PAMP?
It dimerizes and initiates a signal transduction cascade
What is the role of NF-κB in TLR signaling?
NF-κB is a transcription factor that induces pro-inflammatory cytokine expression.
How is NF-κB normally held inactive in the cytoplasm?
It is bound by the inhibitor IκB.
What adaptor protein is essential for TLR signaling?
MyD88
What is the function of the IRAKs in TLR signaling?
They are serine kinases that phosphorylate other proteins to propagate the signal
What role do ubiquitin ligases play in TLR signaling?
They create polyubiquitin chains that scaffold further signaling complexes
What happens when IκB is phosphorylated?
It is degraded, allowing NF-κB to translocate to the nucleus and initiate transcription
What are the three major transcription factors activated by TLR signaling?
NF-κB, AP-1, and IRF
Name three pro-inflammatory cytokines produced after TLR activation
IL-8, IL-6, and IL-1β
