Cytokines and TLR Quiz
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Questions and Answers

What is a major function of cytokines, according to the provided text?

Stimulation of growth

What type of cells can release cytokines, based on the information provided?

All cells

What is the role of caspases in relation to cytokines?

They cleave cytokines

What is the effect of macrophage colony factor on bone marrow, as described?

<p>Stimulation</p> Signup and view all the answers

Where are cytokines found after being cleaved by caspases?

<p>extracellular</p> Signup and view all the answers

What does PRR stand for, as mentioned in the context?

<p>Pattern Recognition Receptor</p> Signup and view all the answers

What do many PRRs recognize?

<p>Ligands</p> Signup and view all the answers

What part of the TLR faces the cytosol?

<p>C-term</p> Signup and view all the answers

How many different TLRs are mentioned in the text?

<p>10</p> Signup and view all the answers

Which TLR is specifically mentioned to recognize Lipid A?

<p>TLR4</p> Signup and view all the answers

What is the name of the protein that resides with TLR4 in the plasma membrane?

<p>MDL</p> Signup and view all the answers

Which TLR recognizes lipoteichoic acids and lipoproteins?

<p>TLR2</p> Signup and view all the answers

What type of molecule is Lipopolysaccharide (LPS), as related to TLR4?

<p>sugar</p> Signup and view all the answers

What type of molecules do TLR 3/7/8 recognize?

<p>Viral RNAs, specifically double-stranded RNAs.</p> Signup and view all the answers

What is the primary function of the acyl group as depicted?

<p>The primary function of the acyl group is to stabilize the binding of the TLR.</p> Signup and view all the answers

What is the specific structural feature that TLR9 recognizes in microbial DNAs?

<p>TLR9 recognizes unmethylated cytosine-guanine dinucleotide (CpG) motifs.</p> Signup and view all the answers

Where are TLR 3/7/8 located within the cell?

<p>They are located in the endosomal compartment.</p> Signup and view all the answers

What is the significance of dimerization in the context of TLR activation?

<p>Dimerization is necessary to initiate the activation signal.</p> Signup and view all the answers

What type of RNA is most important for binding to TLR 3/7/8?

<p>Double-stranded RNA is the most important ligand.</p> Signup and view all the answers

What is the primary role of TLRs in initiating an immune response?

<p>TLRs recognize viral or bacterial components and initiate signaling cascades.</p> Signup and view all the answers

According to the figure, what role does a peptide play in TLR activation?

<p>The peptide links the sugar and acyl group, and stabilizes the binding of the TLR.</p> Signup and view all the answers

What type of cells are crucial for bridging the innate and adaptive immune responses, based on the diagram?

<p>Dendritic cells.</p> Signup and view all the answers

According to the diagram, what is one type of molecule that TLR activation might detect?

<p>Viral RNA or DNA.</p> Signup and view all the answers

What is the relevance of ‘unmethylated’ in the context of TLR9 activation?

<p>Unmethylated DNA is associated with microbial DNA and not typically found in the host, allowing it to be recognized by the immune system.</p> Signup and view all the answers

What is the immediate result of activation of signalling transduction pathways by TLRs?

<p>Activation of genes.</p> Signup and view all the answers

What is the role of cytokines released during immune activation?

<p>To work together and regulate the immune response.</p> Signup and view all the answers

Which branch of the immune system, innate or adaptive, can distinguish the type of infection?

<p>Innate immunity</p> Signup and view all the answers

What kind of immune response do TLRs help initiate when they detect a pathogen?

<p>Antiviral immune response.</p> Signup and view all the answers

What type of immune cell releases cytokines that work together?

<p>Monocytes.</p> Signup and view all the answers

What type of molecule are cytokines?

<p>Helical Proteins</p> Signup and view all the answers

Which interleukins are listed as key anti-inflammatory cytokines?

<p>IL-1RA, 10, 27, 35, 37</p> Signup and view all the answers

What process do pro-inflammatory cytokines induce in leukocytes?

<p>activation</p> Signup and view all the answers

Where are regulatory T cells located?

<p>In follicles (lymphoid)</p> Signup and view all the answers

What is the general function of the highlighted Interleukins?

<p>Anti-inflammatory actions</p> Signup and view all the answers

What is another term for 'vasodilation', as listed in the diagram?

<p>anneut</p> Signup and view all the answers

Which molecules are important in T cell differentiation?

<p>Cytokines and antigen</p> Signup and view all the answers

Is IL-1RA a pro-inflammatory or anti-inflammatory cytokine?

<p>anti-inflammatory</p> Signup and view all the answers

Flashcards

What are Pattern Recognition Receptors (PRRs)?

Pattern Recognition Receptors (PRRs) are proteins on immune cells that recognize specific patterns found on pathogens, triggering an immune response.

What are Toll-like Receptors (TLRs)?

Toll-like Receptors (TLRs) are a type of PRR that detect specific pathogen-associated molecular patterns (PAMPs) to initiate innate immunity.

Where are TLRs located in the cell?

TLRs are located in different parts of the cell, depending on which pathogen they need to recognize.

What is the role of the C-terminal domain in TLRs?

TLRs have a C-terminal domain that faces the cytosol of the cell, where it can activate signaling pathways to trigger an immune response.

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What does TLR4 recognize?

TLR4 recognizes the LPS (lipopolysaccharide) found on the outer membrane of Gram-negative bacteria, helping the immune system fight these infections.

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What does TLR2 recognize?

TLR2 recognizes Lipoteichoic acids and Lipoproteins, common components of bacterial cell walls. It plays a role in recognizing a variety of bacterial infections.

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Why are TLR4 and TLR2 important?

TLR4 and TLR2 are important for activating immune responses against bacterial infections by recognizing specific components of bacterial cell walls.

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How many TLRs exist and how do they work together?

There are 10 different TLRs, each recognizing unique PAMPs and triggering specific immune responses. TLR2 and TLR1 form heterodimers to recognize specific bacterial components.

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What is the role of TLRs in immunity?

TLRs are crucial for initiating the innate immune response.

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How do TLRs work?

TLRs trigger signaling cascades within cells, leading to the activation of genes involved in inflammation and immune responses.

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How do TLRs connect innate and adaptive immunity?

TLRs help bridge the innate and adaptive immune responses by activating dendritic cells, which then present antigens to T cells.

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What do TLRs recognize?

TLRs recognize a variety of PAMPs, including viral RNA/DNA and bacterial components, triggering specific antiviral or antibacterial responses.

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What are cytokines?

Cytokines are small signaling proteins released by immune cells that help coordinate immune responses.

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What are the concentrations of cytokines?

Cytokines are released in picomolar concentrations.

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How do cytokines work together?

Cytokines work together to create a complex network that regulates immune responses.

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What are Monokines?

A group of cytokines known as "monokines" are produced by monocytes and macrophages, which are types of white blood cells. These cytokines play a crucial role in immune responses, inflammation, and the development of other immune cells.

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What is M-CSF?

Macrophage Colony-Stimulating Factor (M-CSF) is a specific cytokine (monokine) involved in the production and differentiation of macrophages. It is considered a growth factor and is also important for the maintenance and survival of these immune cells.

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What are Caspases?

Caspase is a family of enzymes that play a central role in apoptosis or programmed cell death. They are involved in breaking down cellular components in a controlled manner, preventing uncontrolled cell death and inflammation.

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What is Caspase-8?

Caspase-8 is a specific type of caspase involved in the initiation of apoptosis. It is often activated by external signals, such as the binding of a death receptor on a cell's surface.

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TLR3/7/8

A type of immune receptor found inside cells (endosomes) that detects viral RNA. TLR3, TLR7, and TLR8 specifically recognize double-stranded RNA, a common feature of viral genomes.

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Dimerization

A molecule that is made up of two identical subunits. In the context of TLRs, dimerization means two TLR molecules come together to activate the immune response.

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Binding Site

The specific region on a TLR molecule where a viral RNA molecule binds.

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Double-Stranded RNA

A type of viral RNA that is structured in a double helix, similar to a twisted ladder.

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Endosome

A small, membrane-bound compartment within a cell that plays a role in capturing and processing material from outside the cell.

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Viral RNA Recognition

The process where these TLRs detect double-stranded RNA, leading to the activation of the immune system and the production of antiviral molecules.

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TLR9

A type of immune receptor found inside cells (endosomes) that recognizes unmethylated CpG motifs in bacterial DNA.

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Unmethylated CpG Motif

A short sequence of DNA that is often found in bacterial DNA. It's 'unmethylated' in bacteria, which means it has a specific chemical modification that helps TLR9 recognize it.

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T cell

A type of immune cell that helps regulate immune responses, preventing overactive inflammation and promoting tolerance to harmless substances.

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Cytokines

Chemical messengers that help coordinate immune responses, influencing the behavior of T cells and other immune cells.

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Pro-inflammatory cytokine

A specific type of cytokine that promotes inflammation and activates immune cells.

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Anti-inflammatory cytokine

A specific type of cytokine that suppresses inflammation and helps regulate immune responses.

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Pro-inflammatory T cell

A type of T cell that promotes inflammation and activates other immune cells.

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Anti-inflammatory T cell

A type of T cell that suppresses inflammation and promotes tolerance.

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T cell differentiation

A process that helps regulate immune responses by ensuring that the adaptive immune system recognizes and attacks only harmful invaders while tolerating harmless substances.

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Protein cleavage

The process of breaking down a protein by enzymes into smaller peptides.

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Study Notes

Innate Immunity

  • Immunity distinguishes self from non-self (microorganisms, tumors, etc.)
  • Innate immunity uses germline-encoded receptors to detect non-self
  • Innate immunity does not have somatic recombination

Pattern Recognition Receptors (PRRs)

  • PRRs detect pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs)
  • Toll-like receptors (TLRs) are a type of PRR
  • TLRs are type I transmembrane proteins with two domains:
    • Leucine-rich repeats (LRRs): horseshoe-shaped, extracellular/endosomal sensor of PAMPs/DAMPs
    • Toll/interleukin-1 receptor (TIR) domain: globular, cytosolic, signal transduction
  • Thirteen TLRs are found in mammals (10 in humans, 13 in mice)
  • TLRs have various subcellular localizations and bind to different ligands

TLR Subtypes

  • TLR1/2: bind Gram-positive bacteria triacylated lipopeptides
  • TLR3: binds doublestranded RNA (dsRNA)
  • TLR4: binds lipopolysaccharide (LPS) from Gram-negative bacteria (specifically Lipid A); requires MD-2 co-receptor
  • TLR5: binds bacterial flagellin
  • TLR6/2: bind diacylated lipopeptides from Gram-positive bacteria
  • TLR7/8: bind single-stranded RNA (ssRNA)
  • TLR9: binds unmethylated CpG DNA
  • TLR10: similar structure to TLR1/6, functions likely anti-inflammatory

Cytokines

  • Small proteins (5–30 kDa)
  • Released by many cell types, play a crucial role in cell-cell interactions
  • Function via autocrine and paracrine mechanisms
  • Approximately 250 cytokines in humans
  • Classes based on structure and function: interleukins, interferons, tumor necrosis factor (TNF) family, colony stimulating factors, chemokines, growth factors, and others

Role of TLRs in Adaptive Immunity

  • TLRs stimulate antigen processing in antigen-presenting cells (APCs) by phagocytosis
  • They induce the expression of co-stimulatory molecules on APCs and release cytokines
  • TLRs help the adaptive immune system by relaying information about infections

Cytokine Signaling

  • Cytokines initiate signal transduction pathways, turning on gene expression in target cells.
  • Pro-inflammatory cytokines (TNF-α, IL-1β, IL-12) induce inflammation, fever, and attract immune cells to sites of infection or damage
  • Anti-inflammatory cytokines (IL-1ra, IL-10, TGF-β) dampen excessive inflammation

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Description

Test your knowledge on cytokines and Toll-like receptors (TLRs) with this quiz. Explore the functions of cytokines, the role of caspases, and the recognition mechanisms of various TLRs. Challenge yourself with questions about their structural features and interactions in the immune response.

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