Lecture 3 Flashcards
(20 cards)
What are some anatomical barriers?
mucosal surfaces (respiratory tract, gastrointestinal tract, vaginal tract), skin
How do these anatomical barriers function mechanically?
epithelial cells joined by tight junctions
What are mucosal surfaces?
epithelial surfaces that produce mucus
How does each anatomical barrier “flush” things?
Skin: longitudinal flow of air or fluid
Gut: longitudinal flow of air or fluid
Lungs: movement of mucus by cilia
Eyes/nose/oral cavity: tears, nasal cilia
What are goblet cells?
specialized intestinal epithelial cells that make mucus (MUC2 monomer –> c-term disulfide linked dimer –> O-glycosylated dimer into MUC2 multimer –> MUC2 expansion and mucus network formation)
How does the microbiome prevent microbial invasion?
Competition for nutrients and space –> colonization resistance
Why don’t our immune systems attack our microbiomes?
localization away from the intestinal epithelium and commensals do not harbor the necessary elements for invasion
How does each anatomical barrier function chemically?
Skin: fatty acids, beta-defensins and lamellar bodies and cathelicidin
Gut: low pH/enzymes like pepsin, alpha-defensins (cryptdins) and RegIII (lecticidins) and cathelicidin
Lungs: pulmonary surfactant, alpha-defensins and cathelicidin
Eyes/nose/oral cavity: enzymes in tears and saliva (lysozyme), histatins and beta-defensins
What defines a harmonious microbiome?
Proper composition and spatial localization (separation from the epithelium)
What produces lysozyme?
epithelial cells, tear ducts, neutrophils
What produces cathelicidin (LL-37)? What is LL-37?
multiple epithelial cells and neutrophils produce it.
disordered structure that forms alpha helix in presence of lipids, then makes a toroidal pore in bacterial membrane
What produces alpha-defensins? What do they do?
paneth cells.
alpha defensin dimers make a pore in the bacterial membrane
What produces RegIIIa? What does it do?
intestinal epithelial cells
pore formation like a donut
How do LCN2 and Calprotectin work to defend?
limit availability of essential metals required for growth (iron for LCN2 and calcium/zinc for Calprotectin)
What are TLRs?
Toll-Like Receptors, membrane bound receptors
What does TLR4 recognize?
lipopolysaccharide (LPS) from gram-negative bacteria
What does TLR5 recognize?
flagellin from flagella of bacteria
What does TLR7 recognize?
single-stranded RNA (ssRNA) from viruses
What is MYD88?
protein that helps immune cells signal, adapter protein that receives signals from outside cell to relay inside. contains TLR/IL-1receptor/resistance (TIR) domain
Do the antimicrobial proteins secreted at anatomical barriers circulate in the blood?
NO!!!!
