saliva protein defences Flashcards
which glands produce which saliva secretions??
role of serous amylase
Starch digestion to glucose
Main function to clear starchy food debris from mouth
roles of mucins
Enamel surface protection and bacterial defence
Mucins allow growth of less harmful bacterial on the tooth surface.
- s.mutants does not grow well
what are 3 mucin sub-families and what is their role in the oral cavity?
Muc5B or MG1
- binds Calcium ions
- Contributes to calcium balance in oral cavity
Muc7 or MG2
- Promotes bacterial agglutination
- Binds bacteria and allows agglutination
- Precipitates bacteria
- We can then swallow bacteria to remove them from oral cavity
what proteins are found in saliva?
- serous amylase
- mucins
- sIGA
- lysozyme
- lactoferrin
- salivary peroxidase
- histatins
- gp340
- defensins
- acidic proline rich phosphoprotein (aPRP)
- statherin
role of sIGA in saliva
- plasma cells
- bacterial/viral defence
- binds oral bacteria
- agglutination
- allows clearing from ooral cavity
*
role of lysozymes in saliva
bacterial defence
- aggregates bacterial cells in suspension
- enzymatically cleaves glycosidic linkage in peptidoglycan components of bacterial cell wall
- lysis of bacteria
- Protects oral cavity from pathogens
- In times of increased inflammation more lysozyme is present
- fungicidal properties
- inhibits viral replication
- antioxidant properties
roles of lactoferrin in saliva
- bacterial defence
- iron binding protein
- binds Fe3+ - essential microbial nutrient
- antibacterial activity
- some bacteria require ferric ions for growth
- prevents binding of pathogens to host cells
- antioxidant
roles of salivary peroxidase
bacterial defence
- catalyses the bacterial metabolic products to hypothiocyanate
- Hypothiocyanate blocks bacterial glycolysis & kills bacteria.
- Protects host cell/proteins from H2O2 cytotoxicity.
- Converts H2O2 into water
- Protected from cytotoxicity
roles of innate immunity scavenger receptor glycoprotein-340 in saliva
bacterial defence
- in saliva and tears
- secreted by epithelial cells at mucosal surfaces
- aggregation of bacterial
- bacterial clearance through swallowing
roles of histatins in saliva
Serous contributions
Produced by all 3 major glands
- phosphorylated HIS1 binds to hydroxyapatite
- protects against proteolytic cleavage
- inhibits spontaneous growth of HAP crystals
- other histatins
- antimicrobial activity
- blocks proteases
where are histatins used in dentistry?
- histatin-1 is used to modify titanium implants to prevent bacterial infection at interface
- Protein can regulate enamel mineral homeostasis
- used in oral wound healing
- activates signalling pathways which make cells migrate to wound areas
- populates wound area to close the wound
why are histatins of pharmacological interest
Peptides can be synthesised using chemistry
Potentially possible to add to mouth rinses, gels & implants
They represent the bodies own defence antibiotic/antifungal
roles of defensins in saliva?
antibacterial peptides
- neutrophil defensins
- stored in granules
- released from neutrophils to fight bacterial infection
- epithelial defensins
- in response to high bacterial contents
- periodontal disease
- antibacterial properties
- in response to high bacterial contents
roles of acidic proline rich phosphoprotein (aPRP)
‘calcium balancing act’
- inhibitor of calcium phosphate crystal growth
- prevents sialolith formation
- balance of calcium required to allow remineralisation of enamel
- interaction with oral bacteria and pellicle proteins
- Proteolytic fragmentation releases bacterial binding domain (C-terminus), thus this fragment blocks bacterial adhesion to tooth surfaces
