mechanisms by which the gingiva responds to the oral microflora

2. Immunity of Gingiva
Dr. Madhusudhanreddy

3. Introduction

4. Type of immunity
• Innate immunity consists of epithelial barriers,
phagocytes, complement system and natural killer cells
• Adaptive immunity consists of
– Passive
– Active
• Humoral immunity
• Cell mediated immunity

5. Immune mechanismof mucosa

6. Defence systemof gingiva
• Defence system of gingiva consists of
– Innate immunity – Toll like receptors, Complement
system, Natural killer cells.
– Gingival clevicular fluid

7. TOLL LIKE RECEPTORS
• Definition: cell surface receptors on phagocytes and other cell
types that act as pettern recognition receptors important in the
innate immune response to lipopolysaccharides and other
microbial products. Toll like receptors share homology and
signal transduction pathways with the type I interleukin
receptors. (Abul K Abbas)
• Toll protein – first discovered in 1985
• Toll receptor has the structural similarity to that of the protein
discovered in Drosophila which helps in determining dorsal-
ventral polarity.

8. Structure of TOLL LIKE RECEPTORS
• Toll like receptor is a trans membrane protein consisting of
– Extracellular domain – leucine and cytosine rich rich
molecule
– Intracellular domain – Toll/IL-1 receptor (TIR)

9. Cells expressingTOLL LIKE RECEPTORS
• Macrophages
• Dendritic cells
• Neutrophils
• NK cells
• Mucosal epithelial cells
• Endothelial cells
• Fibroblasts

10. • Human Toll-like receptors so far recognised are 11
types
• 12th and 13th type has been recently discovered.

11. Method of recognization
• Pathogen associated molecular pattern
• Pattern recognition receptor

14. SignallingToll-like receptors
• LPS- LipoPoly Saccharide
• MyD88- Myeloid differentiation primary –response protein 88
• IRAK 1,4- Interleukin 1 Receptor-Associated Kinase
•TRAF6- Tumor-necrosis-factor-Receptor Associated Factor 6
• IKK- inhibitor of nuclear factor-κB (IκB)-kinase complex

15. Negative regulation of TLRs
• IRAK-M- Interleukin-1-receptor (IL-1R)-associated kinase M
• SOCS1- Suppressor of cytokine signalling 1

16. GINGIVAL CLEVICULAR FLUID
• Fluid from the gingival blood vessels flows through the
junctional epithelium into the gingival crevice.
• Healthy gingiva - flow of GCF is minimal to absent
• Inflammation - rate of flow increases.
• The rate of its flow - permeability of gingival blood vessels.
• During inflammation - blood vessels dilate and plasma enters
the connective tissue spaces in greater amounts.

17. COMPOSITION OF GCF
ENZYMATIC COMPONENTS NON ENZYMATIC COMPONENTS

18. ENZYMATIC COMPONENTS
• Bacterial endotoxin
• Total proteins
• Components of the complement system
• Collagenase
• Elastase
• Cathepsins
• Connective tissue matrix breakdown products
• Antibodies directed to plaque bacteria
• Cellular adhesion molecules
• Interleukins
• Prostaglandins

19. Lipopolysaccharides (Endotoxins)
- These molecules are found in the outer membrane of
the cell wall of Gram-negative bacteria.
- The presence of endotoxins has been positively
correlated with gingival inflammation
- The level of endotoxin is related to the number of
Gram-negative bacteria.
- Lipopolysaccharides (LPS) vary in their structure
depending on bacterial source.

20. Total proteins
• Several reports suggest that, compared to periodontal
healthy controls, GCF from sites with periodontitis has
significantly elevated levels of total protein.
• Proteins namely , , 2 and 1 globulins, transferrin,
albumin, immunoglobulins such as IgG, IgM and IgA,
complement components such as C1, C4, C3, C5, have
been reported to be present in GCF.
• Proteins Include: - fibrinogen, ceruloplasmin,  -
lipoprotein, transferrin, 1 – antitrypsin and 2 –
macroglobulin.

21. Elastase
• Neutrophil elastase, sometimes referred to as granulocyte
elastase is an abundant proteinase
• Released from the azurophilic granules of neutrophils. Acts
as an indicator of neutrophil activity.
• Neutrophil elastase is a serine proteinase - degrads
microbiological components with or without phagocytosis.
• When released extracellularly, degrade host intercellular
matrix components - elastin, fibronectin and collagen.
• Smokers display higher levels of elastase than nonsmokers.

22. Cathepsins
• Cathepsin B is an enzyme active in proteolysis.
• It belongs to the class of cysteine proteinases.
• Cathepsin B in gingival crevice fluid – secreted by macrophages.
• Cathepsin B activity has been found in gingival crevice fluid in
adult periodontitis.
• It seems to be increased in periodontitis but is not increased in
gingivitis.

23. Connective tissue matrix breakdown products
Glycosaminoglycans (GAG’s):
• The GAG’s in GCF that have been most examined as
possible diagnostic markers for periodontal diseases are:
– Chondroitin – 4 – sulfate,
– chondroitin – 6 – sulfate and
– hyaluronic acid.
• The appearance of C-4-S in GCF has been suggested as a
marker for bone resorption associated with periodontal
disease or orthodontic tooth movement.

24. Hydroxyproline:
• It is a prominent aminoacid of collagen and its appearance in
GCF has been preliminary investigated as a marker for the
destruction of periodontal connective tissue.
• Data from one cross-sectional study in humans indicate that
GCF hydroxy proline levels cannot distinguish between sites
with gingivitis or periodontitis.
Fibronectin:
• These are a large group of heterogeneous glycoprotein
present in blood and connective tissues.
• Data from most studies indicate that GCF fibronectin is not a
promising diagnostic marker.

25. Connective Tissue Proteins:
• Increased GCF levels of the amino terminal propertied of
type I collagen have been reported at periodontitis sites.
• Osteocalcin
• Osteonectin
• Neither Osteocalcin nor Osteonectin levels in GCF have
been systematically evaluated as diagnostic markers for
periodontitis.

26. Antibodies directed to plaque bacteria
• Antibodies levels are probable dependent on a number of
factors
– Previous exposure to the subgingival microbiota
– Host ability to respond to particular antigens
• Antibodies to P.gigivalis and A.actinomycetemcomitans are
present in the patients with periodontitis.
• Majorly IgG (4 sub classes) and IgA (2 sub classes) are
present in GCF
• Antibodies has a protective role against periodontal diseases.

27. Cellular adhesion molecules
• Leukocytes migration into the tissues in necessary during
the inflammatory process.
• Cytokines induce the expression of adhesion molecules on
the surface of vascular endothelial cells.
– Endothelial leukocyte adhesion molecule-1 (ELAM-1)
– Intercellular adhesion molecule-1 (ICAM-1)
• These cellular adhesion moleculae helps in migration of
leukocytes to the area of inflammation.
• Insufficient levels of cellular adhesion moleculaes causes
Leukocyte Adhesion Deficiency Syndrome (LAD)

28. Cytokines
• Soluble proteins
• Secreted by cells involved in innate and adaptive immunity
• Messanger molecules that transmit signals between
leukocytes and other cells.
– Epithelial cells
– Endothelial cells
– Fibroblasts
• Regulates growth and differentiation of cells.
• These are capable of stimulating or down regulation of their
own or other cytokines.
• Interleukins are important group of cytokines consisting of
more than 20 molecules.

29. • Cytokines are potent local mediators of inflammation.
• Cytokines that are present in GCF and have been
investigated as potential diagnostic makers for periodontal
disease include:
– interleukin - 1, 1,
– interleukin – 6,
– interleukin – 8 and
– tumor necrosis factor  (TNF -).
• Both IL - 1 and IL - 1 have pro-inflammatory effects and
depending on a variety of factors can stimulate either bone
resorption or formation.

30. • Adult periodontitis patients a higher percentage of sites
are positive for IL - 1 (87%) and IL - 1 (56%) IL-6
has also been associated with bone resorption. GCF
from sites with progressing periodontitis contains
elevated amounts of IL-6.
• IL-8 was formerly called monocyte-derived neutrophil
chemotactic factor. GCF from sites with periodontitis
contains significantly more total IL-8 than GCF from
healthy sites

31. Prostaglandins
• PGE2 was first identified in GCF by Goodson et al. in
1974.
• PGE2 is a product of the cyclooxygenase pathway.
• Elevated levels of PGE2 in GCF were found in patients
with periodontitis compared to patients with gingivitis.
• PGE2 levels were three times higher in patients with
juvenile periodontitis compared to adult periodontitis.

32. NON ENZYMATIC COMPONENTS
• Cellular elements
Bacteria
Desquamated epithelial cells
Leucocytes ( PMN’S, monocytes/macrophages)
• Electrolytes
Potassium
Calcium
Sodium
• Organic compounds
Carbohydrates-GLUCOSEHEXOSAMINE
-HEXURONIC ACID
Proteins

33. Cellular components

34. Electrolytes
• Potassium, sodium, calcium, magnesium and fluoride
have been studied in gingival fluid.
• Most studies have shown a positive correlation of
calcium and sodium concentrations and the sodium to
potassium ratio with inflammation.

35. • Mean conc of sodium in GCF - 174.
• Mean conc of sodium in serum - 136 (±7.9) significantly
lower than that of GCF
• In severe inflammation – Na conc increases more then that of
normal range.
• The potassium content of GCF is also generally more than
that of serum.
• Values as high as 69 mEg/lit from the inflamed areas.
• GCF has more potassium content - cases showing more severe
periodontitis.
• Accumulation of intracellular potassium from the disrupt
cells.

36. Organic Compounds
• Carbohydrates, proteins and lipids have been
investigated. Glucose hexosamine and hexuronic acid
are two of the compounds found in gingival fluid.
Glucose concentration in gingival fluid is 3-4 times
greater than that in serum.
• This is interpreted not only as a result of metabolic
activity of adjacent tissues, but also as a function of the
local microbial flora.

37. Organic Compounds
• The total protein content - much less than that of serum.
• No significant correlations - Severity of gingivitis, pocket
depth and extent of bone loss.
• Proteins namely , , 2 and 1 globulins, transferrin,
albumin, immunoglobulins such as IgG, IgM and IgA,
complement components such as C1, C4, C3, C5, have been
reported to be present in GCF.
• Proteins Include: - fibrinogen, ceruloplasmin,  - lipoprotein,
transferrin, 1 – antitrypsin and 2 – macroglobulin.

38. Functions of GCF
• 1) Cleanse material from the sulcus
• 2) Contain plasma proteins that may improve adhesion of the
epithelium to the tooth.
• 3) Possess antimicrobial properties.
• 4) Exert antibody activity in defense of the gingiva.

40. Complement system

45. References
• Lindhe : Clinical periodontology and implant dentistry; Fifth
edition.
• Caranza’s Clinical periodontology; Ninth edition
• R. mahanonda, S. pichyangkul eta al; Toll-like receptors and
their role in periodontal health and disease: Periodontology
2000, Vol. 43, 2007, 41–55.
• S. Akira,K.Takeda et al; Toll-like Receptor Signalling: Nature
reviews; Immunology: Vol. 4, 2004, 499–511.
• M. Hans, V. M. Hans et al; Toll-like receptors and their dual
role in periodontitis: a review; Journal of Oral Science, Vol.
53, No. 3, 263-271, 2011
• Net sources