![Lecture 02: The innate immune system [SEQ 2]](https://images.unsplash.com/photo-1576086671120-8cf1f46d1373?crop=entropy&cs=srgb&fm=jpg&ixid=M3w0MjA4MDF8MHwxfHNlYXJjaHwzfHxwaGFnb2N5dG9zaXMlMkMlMjBpbW11bmUlMjByZXNwb25zZSUyQyUyMGNlbGwlMjBiaW9sb2d5fGVufDF8MHx8fDE3MzgyMzMzMDd8MA&ixlib=rb-4.0.3&q=85&w=800&fit=crop&h=300&q=75&fm=webp)
Podcast
Questions and Answers
What is the primary role of v-ATPases in the phagolysosome formation process?
What is the primary role of v-ATPases in the phagolysosome formation process?
They acidify the environment by pumping protons
How do reactive oxygen species (ROS) and nitrogen intermediates contribute to microbial killing within a phagolysosome?
How do reactive oxygen species (ROS) and nitrogen intermediates contribute to microbial killing within a phagolysosome?
They are toxic to the microbe and degrade their components.
Besides microbial killing, what is another important function of the phagolysosome in the context of the immune response?
Besides microbial killing, what is another important function of the phagolysosome in the context of the immune response?
Antigen presentation
What is the specific role of the TIR domain in the activation of immune genes?
What is the specific role of the TIR domain in the activation of immune genes?
Signup and view all the answers
Name three types of molecules that are present in lysosomes to promote degradation?
Name three types of molecules that are present in lysosomes to promote degradation?
Signup and view all the answers
What is the primary function of siderophores in the context of a macrophage's antimicrobial activity?
What is the primary function of siderophores in the context of a macrophage's antimicrobial activity?
Signup and view all the answers
What is the role of NF-κB in the macrophage?
What is the role of NF-κB in the macrophage?
Signup and view all the answers
How does the decrease in pH inside the phagolysosome affect the enclosed microbe?
How does the decrease in pH inside the phagolysosome affect the enclosed microbe?
Signup and view all the answers
What are the two primary cell types responsible for carrying out phagocytosis, and where are they primarily located?
What are the two primary cell types responsible for carrying out phagocytosis, and where are they primarily located?
Signup and view all the answers
Briefly describe the role of opsonization in the process of phagocytosis.
Briefly describe the role of opsonization in the process of phagocytosis.
Signup and view all the answers
What is the primary difference between a PAMP and a PRR in the context of pathogen recognition?
What is the primary difference between a PAMP and a PRR in the context of pathogen recognition?
Signup and view all the answers
Describe the function of toll-like receptor 4 (TLR4), including its ligand and location.
Describe the function of toll-like receptor 4 (TLR4), including its ligand and location.
Signup and view all the answers
Name two types of nucleic acids that can act as Pathogen-Associated Molecular Patterns (PAMPs) and the type of pathogen they are typically associated with.
Name two types of nucleic acids that can act as Pathogen-Associated Molecular Patterns (PAMPs) and the type of pathogen they are typically associated with.
Signup and view all the answers
What is a phagosome and how does it form during phagocytosis?
What is a phagosome and how does it form during phagocytosis?
Signup and view all the answers
List three distinct examples of carbohydrates that can act as PAMPs and state the type of microbe they are associated with.
List three distinct examples of carbohydrates that can act as PAMPs and state the type of microbe they are associated with.
Signup and view all the answers
What initiates phagocytosis after a PAMP binds to a PRR?
What initiates phagocytosis after a PAMP binds to a PRR?
Signup and view all the answers
Flashcards
Phagocytosis
Phagocytosis
The process by which immune cells engulf and digest pathogens.
Macrophages
Macrophages
Immune cells that reside in tissues and perform phagocytosis.
Neutrophils
Neutrophils
Immune cells recruited from the blood to fight infections.
PAMPs
PAMPs
Signup and view all the flashcards
PRRs
PRRs
Signup and view all the flashcards
Opsonization
Opsonization
Signup and view all the flashcards
Toll-like receptors (TLRs)
Toll-like receptors (TLRs)
Signup and view all the flashcards
Phagosome
Phagosome
Signup and view all the flashcards
Fusion with Early Endosomes
Fusion with Early Endosomes
Signup and view all the flashcards
Fusion with Late Endosomes
Fusion with Late Endosomes
Signup and view all the flashcards
Fusion with Lysosomes
Fusion with Lysosomes
Signup and view all the flashcards
Microbial Killing Mechanisms
Microbial Killing Mechanisms
Signup and view all the flashcards
Reactive Oxygen Species (ROS)
Reactive Oxygen Species (ROS)
Signup and view all the flashcards
NF-kB
NF-kB
Signup and view all the flashcards
Cytokines
Cytokines
Signup and view all the flashcards
Inflammatory Proteins
Inflammatory Proteins
Signup and view all the flashcards
Study Notes
Phagocytosis Overview
- Phagocytosis is a process where immune cells engulf and destroy pathogens.
- Key cells involved are macrophages (resident tissues) and neutrophils (recruited from blood).
- The process involves several steps: chemotaxis, attachment, ingestion, lysosome fusion, microbial killing & digestion, and waste release.
Steps in Phagocytosis
- Chemotaxis: Attraction of phagocytes to the site of infection.
- Attachment: Phagocyte binds to the pathogen via surface receptors.
- Ingestion: The pathogen is engulfed by the phagocyte, forming a phagosome.
- Phagosome Formation: The phagosome is the vesicle containing the engulfed pathogen.
- Lysosome Fusion: The phagosome fuses with lysosomes, creating a phagolysosome.
- Microbial Killing and Digestion: Lysosomal enzymes (e.g., proteases, lipases) and ROS/RNOS break down the pathogen; the acidic environment of the phagolysosome also contributes.
- Debris Release: Waste products are expelled, or the pathogen components can be processed for antigen presentation.
Recognizing Microbes
-
PAMPs (Pathogen-Associated Molecular Patterns): Unique molecular structures on pathogens.
-
PRRs (Pattern Recognition Receptors): Found on immune cells, they recognize PAMPs.
-
TLR (Toll-like Receptors): A class of PRRs, with diverse ligand recognition capabilities. Key TLRs include:
- TLR2: Recognizes peptidoglycans (bacterial cell wall component).
- TLR4: Recognizes lipopolysaccharide (LPS) (bacterial cell wall component).
- TLR5: Recognizes flagellin (bacterial appendage).
- TLR7: Recognizes ssRNA (viral).
- TLR9: Recognizes dsRNA (viral/bacterial).
- TLR10: Recognizes flagellin (bacterial appendage).
Opsonization
- Opsonization: Coating of pathogens with opsonins (like antibodies or complement proteins) to enhance phagocytosis.
- Steps:
- Antibody tagging: Antibodies mark a pathogen.
- Recognition: Phagocytes recognize the antibodies.
- Engulfing: Phagocyte binds and ingests the pathogen.
- Killing: The pathogen is destroyed within the phagocyte.
Phagosome Maturation
- Formation: The internalisation of the pathogen into a phagosome.
- Early Endosome Interaction: The phagosome fuses with early endosomes, which provide specific proteins.
- Late Endosome Fusion: The phagosome fuses with late endosomes where the lysosomal enzymes are present along with the proton pumps, that decrease pH.
- Lysosome Fusion: The phagosome fuses with lysosomes to form a phagolysosome.
Microbial Killing & Debris Clearance
- Phagocytosis vs. Microbial Clearance and Digestion: Interior environment with acidic PH reduces pH to 3.5-4
- ROS (Reactive Oxygen Species): Toxic molecules generated to kill the pathogen.
- AMP (Antimicrobial Peptides): e.g., defensins, cationic peptides form ion channels in the membrane
- Enzymes (Lysosomal): Break down pathogen structures (peptidoglycans, polysaccharides).
- Nutrient Deprivation: Removal of nutrients required by pathogens.
Signaling and Immune Response
- Cytokines: Signal molecules to recruit and activate other immune cells.
- Inflammatory proteins: Amplify the inflammatory response.
- NF-κB: Key transcription factor activated by TLR signalling.
- Inflammation and immune gene expression: The process is regulated and controls expressions of cytokines, inflammatory mediators etc
- Phagolysosomal protein upregulation: Proteins are altered to enhance the killing and degradation process inside the phagolysosome
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz explores the essential process of phagocytosis, where immune cells like macrophages and neutrophils engulf and destroy pathogens. Students will learn the key steps involved, including chemotaxis, attachment, ingestion, and more. Gain a deeper understanding of how immune cells protect the body from infections.
