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Oral biology > OB S- pellicle 2 > Flashcards

OB S- pellicle 2 Flashcards

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1
Q

what is the enamel pellicle?

A

the layer of material acquired by a cleaned tooth

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2
Q

what is included in the enamel pellicle?

A 
–  Mucins
–  Acidic Proline-rich proteins 
–  Statherin
–  Amylase
–  Lysozyme
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3
Q

what are mucin functions?

A
  • forming buffer between 2 surfaces
  • allowing movement of materials across and providing protection
  • tissue coating (aggregate microbes for removal and concentrates anti-microbial molecules at mucosal interface)
  • lubrication
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4
Q

Describe the bacterial interactions of MG1 .

A

– Attracts some species S. sanguinis, S. mitis & Actinomyces spp.
– Associated with soluble phase, and rapid flushing out of material

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5
Q

Describe the bacterial interactions of MG2.

A

– Attracts many bacterial species;
• S. sanguinis, S. gordonii, E. corrodens, S. aureus, P. aeruginosa
– Long protein core with short CHO chains that often end in sialic acid
• S. sanguinis, S. mitis (sialic acid adhesins)
– Neuraminidase cleaves sialic acid exposing galactose
– Galactose binding bacteria

(sides chains can be modified , can take carbohydrates which can be used as binding sites for certain bacteria (reveal sites)

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6
Q

Describe the proteolytic cleavage of MG2.

A

-peptides assessed in vitro kill bacteria (streptococci, P. gingivalis)
- potent anti fungal peptides characterised (kill azole & amphotericin B resistant Candida & Crytpotoccus sp.
, Crosses fungal membrane and accumulates within the cell, Effective in animal models of Candidiasis)

Cleavage that goes on can release antimicrobial properties

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7
Q

what does proteolytic cleavage cause a release of?

A

Release of peptides derived (in particular) from Acidic & Basic PRPs, Statherin & Histatins

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8
Q

Describe acidic (16kD) PRPs.

A 
–  unique to saliva
–  affinity for hydroxyapatite
–  newly formed pellicle
–  important for Ca2+ & PO4- levels
–  degradation products (peptides) have antibacterial activity
-Conformational change 
- C-terminus exposed as receptor
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9
Q

Describe basic (6-9kD) PRPs.

A

– found in saliva & nasal/ bronchial secretions

– complex with tannin & tannic acid

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10
Q

Describe glycosylated (36kD) PRPs.

A

-newly formed pellicle
– bind to hydroxyapatite
– binds S. mutans efficiently

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11
Q

what do salivary proteins appear to be involved in?

A

Preventing or promoting bacterial adhesion to oral soft and hard tissues

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12
Q

What are PRPs strong promoters of?

A

bacterial adhesion:

  • Amino terminal :control calcium phosphate chemistry
  • Carboxy terminal :interaction with oral bacteria
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13
Q

Describe how interactions of oral bacteria with PRPs and other pellicle proteins is highly specific.

A

– Depends on proline-glutamine carboxy-terminal dipeptide
• e.g. P. gingivalis preference for HA coated with PRPs
– PRPs in solution do not inhibit adhesion of bacteria

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14
Q

What does statherin prevent?

A

both primary and secondary calcium phosphate disposition

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15
Q

what does Statherin aid?

A

Aids A. viscosus & F. nucleatum binding to HAp

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16
Q

What is the C-terminal of statherin involved in?

A

only upon binding to pellicle & conformational change

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17
Q

What are the functions of alpha- amylase?

A 
•  α-amylase
–  α 1-4 glycosidic bonds
•  Digestivefunction
–  e.g. starch, amylose
•  Essential component of salivary pellicle
•  Bacterial Receptor
–  S. sanguinis, S. gordonii
•  Forms heterotypic mixed
micelle like structures
18
Q

what are glucans?

A

glucose polysaccharides with glucose molecules joined by 1,3-α- or 1,6-α- linkages

19
Q

Name water-soluble glucans with 1,6-α- links.

A

dextrans

20
Q

Name water-insoluble glucans with 1,3-α- links and 1,6-α- links.

A

Mutans

21
Q

Describe binding pellicle-attached glucosyltransferases .

A
  • Such immobilized enzymes are still active and continue to produce sticky polysaccharide
  • Bound GTFs also act as binding sites for bacterial adhesion
22
Q

what immunoglobulins are found in the pellicle?

A

IgA and IgG

23
Q

what immunoglobulin predominates?

A

IgA2 -shorter hinge resists proteases

24
Q

what does pellicle -attached immunoglobulins inhibit?

A

Inhibits growth of some species & contributes to adherence of other species

25
Q

what underpins the idea of immunising against S.mutans?

A

presence of antiseptic paint

26
Q

Describe cystatins.

A

• Inhibitors of cysteine proteases (e.g. bacterial & viral)
• Include unique cystatins restricted to oral
environment
• Cystatin SA linked with pellicle formation & remineralisation
• May function in control of periodontal disease
• Protect other salivary proteins from degradation

(protective role -reducing microbial population)

27
Q

Describe histatins.

A

• Histidine rich cationic (+ve ) peptides
– family of at least 12 (1,3&5major saliva forms)
• Incorporated into acquired pellicle

28
Q

What 2 properties does histatins have?

A
  • antifungal properties

- antibacterial properties

29
Q

Describe the antifungal properties of histatins.

A

– Histatin 5 anti-candidal

• binds receptor, target mitochondria, inhibit respiration & leads to production of reactive O2 species

30
Q

Describe the antibacterial properties of histatins.

A

– bactericidal against S.mutans
– Inhibits co-aggregation of P.gingivalis & S.mitis
-Disrupt in vitro biofilms produced by a number of oral bacteria

31
Q

Name other components of the pellicle.

A

• Lysozyme
• Lactoferrin,
– (globular protein with antimicrobial/antifungal properties)
• albumin
• Other bacterial enzymes & products

32
Q

where is lysozyme present?

A

present in numerous organs and most body fluids

33
Q

where is oral lysozyme derived from?

A

at least 4 sources:

-major and minor salivary glands, phagocytic cells and gingival crevicular fluid (GCF)

34
Q

Describe the actions of lysozyme.

A

• Cleaves β-1,4 linkage between N- acetylmuramic acid (NAM) & N- acetylglucosamine (NAG)
– Gram negative bacteria are generally more resistant due to outer LPS layer
• Activates bacterial autolysins - ‘suicide packages’

(attacking cell wall and causing its degredation)

35
Q

What is lactoferrin?

A

• Iron chelating glycoprotein
– Single polypeptide, MW 80 kD
– Member of transferrin family of iro-binding antibacterial proteins

36
Q

what does lactoferrin have a high affinity for?

A

Fe+3

37
Q

what is the principal action of lactoferrin?

A

blocks growth of iron dependent organisms with bacteriostatic effect

38
Q

what does lactoferrin do?

A

– N-terminal peptide product of pepsin (contains no Fe binding sites).
– Broad spectrum bactericidal, antiviral & antifungal
– Binds to LPS & inhibits endotoxin activity

39
Q

Describe antimicrobial activity of HOSCN/OSCN-

A

• Product of Salivary Peroxidase activity
– Enzymes absorb onto Hydroxyapatite
• Against a variety of microorganisms
– e.g. S. mutans, lactobacilli, yeasts, even some viruses
• Can oxidize sulfhydryl groups of enzymes
• Block glucose uptake
• Inhibit amino acid transport
• Damage inner membrane, leading to leakage of cell
• Disrupt electrochemical gradients
• Inhibits hexokinase (essential for Glycolysis)

40
Q

What are antimicrobial components of salvia?

A 
•  Lactoferrin
•  IgA
•  Mucins
•  Antimicrobial peptides
•  Enzymes
–  Lysozyme, glycosidases, peroxidase, esterase, transferase 
•  Proteins
–  Glycoproteins
–  Statherins
–  Histidine-rich Proteins 
–  Proline-rich Proteins
41
Q

what binds carbohydrates and what does this allow?

A

Group of adhesins- called lectins , binding allows build up of bacteria, insoluble phae its good cause it collect bacteria for removal

42
Q

Describe the stages of pellicle formation.

A 
•  Molecules attach immediately
•  1-2 μMs thick before bacteria attach
–  1 hour
•  Transition from pellicle to plaque
–  MG1, sIgA, lysozyme all bind to bacterial cell walls 
–  Pioneer species
–  S. gordonii, S. sanguinis etc.
•  Rapid increase up to 2 hours
•  Slower growth until reaches 5-10 μMs

Oral biology (29 decks)

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