MIC 319 Exam III Flashcards
Eckhard Podack
dscovered immunology and cancer therapy
Intracellular bacteria
Kills host cell to kill pathogen by advantagious invasion
Can be eliminated only by a cellular immune response
Bacteria finds a way to escape the phagolysosome
extracellular bacteria
Does not invade cells, but uses small soluble molecules to get rid of bacteria
can also adhere to epithelial surface (v Cholera)
Examples of intracellular bacteria
chlamydia, tuberculosis, listeria, salmonella, yeast, invasive e Coli
Examples of extracellular bacteria
Strep, Staph, Influenza, v Cholera, e Coli
immediate innate response
0-4 hours, pathogen is greeted by small soluble particles that try to knock it out
induced innate response
4 hrs- 4 days, inflammation, fever, acute response, recruitment of effector cells to help the soluble particles
adaptive response
4 days- end of infection or death of host, B and T cells develop into effector cells and move to the secondary lymphoid to help take out pathogen
armed forces of immune system
barriers
recognition and recruitment of local immune response, reinforcements (innate inflammation and adaptive immune response)
classical killing
- toxic oxygen derived products- O2, H2O2, Oh-, HCl
- toxic nitrogen oxidase- NO
- enzymes- gram positive bacteria are knocked out by digestion of cell wall. Lysosome uses acidic pH to break down microbes
macropinocytosis
cell drinking, eruption of membrane ruffles to engluf fluids back into the endocytic pathway. r\Requires extensive actin mobilization. Occurs in all cell types!
autophagy
engulfment of cytosolic material. autophagosomes fuse with lysosome to take out engulfed material. Occurs in all cell types!
receptor medated endocytosis
actin independent internalization of small molecules and turning them into clathrin coated pits or caveolae
phagocytosis
Ingestion of small particles using macrophages, neutrophils and dendritic cells. PRRs are stimulated to speed this process through the activation of GPCR which causes inflammation and activates a receptor: compliment receptors, mannose receptors, Fc receptors, Dectin 1 receptors, lipid receptors.
types of phagocytosis
opsonic
non opsonic
triggered
formation of phagosome
- probing using actin related proteins
- particle binding and receptor clustering
- phagocytic cup formation
- phagosome closure
inhibition of phagocytosis by Yersinia and Psuedomonas
Type III secretion is shut off by YopH and YopE leads to distruction of actin microfilaments
traditional intracellular killing
bacteria is internallized and broken down by phagolysosome
organization of the lysosome
- contains acidic hydrolases which makes the pH acidic due to the proton pump between the cytosol and the ATP in the lysosome mebrane
- intersection between endocytic pathway and secretory pathway
- digests pathogens from phagocytosis, endocyosis and autophagy
lysosomal diseases
- Gaucher’s disease- mutation for gene encoding the breakdown of glycolipids
- I cell disease- deficiency in enzyme that tags mannose 6 phosphate onto the lysosome enzymes in the golgi
respiratory burst
the rapid release of ROS (O2 and H2O2) and the production of NO from NADPH
superoxide and nitric oxide generation
iNOS- produces NO
NOX (in inflammed area with MPO)- produces O2, H2O2, OH- and HCl
ROS and NO: a benefit or a threat
- can damage cellular proteins, lipids and nucleic acids of infected host cells or bacterial cells and can signal, control inflammation, vascular tone and injury
- can also damage healthy DNA, RNA, proteins and mitochondria which would induce apoptosis
How does ROS come about?
PNOX- phagocytic superoxide NADPH molecule which in the flavocytochrome has subunits gp91phox and p22phox as helpers
neutrophils jobs in intracellular killing
phagocytosis, degranualizes and NETs pathogen by activation Rac2 which casues death, acidification, O2 formation and pus
G protein coupled receptors intitate phagocytosis and ROS activation
- ligand binds G protein to GPCR
- respiratory burst forms alpha and gammabeta proteins which cleaves GTP to GDP
NOS types and induction
- induced by IFNg, LPS and bacterium
- iNOS creates the most No (in all cells)
- eNOS- endothelial cells
- nNOS- neuronal cells
Interactions of ROS and NO
thiols, metals, tyrosines, nucleotide bases and lipids
CGD
genetic deformation of genes encoding NADPH oxidase units