This document provides an overview of the host-bacterial interaction theory of periodontal disease. It discusses how periodontal disease was previously thought to be caused solely by calculus, then by nonspecific plaque, and later by specific pathogenic bacteria. The current understanding is that periodontal disease results from the complex interaction between pathogenic bacteria in plaque and the host immune response. Key bacteria implicated in disease include P. gingivalis, A. actinomycetemcomitans, T. denticola, and others. Virulence factors of bacteria like lipopolysaccharides and leukotoxins can promote tissue invasion and evade host defenses. The host response is also important, as an excessive or inadequate response can lead to

1. 1

3. CONTENTS
PART I
• Introduction
• Definitions
• Historical background
• Microbiologic aspects of the
microbial-host interaction
 Actinobacillus
Actinomycetum Comitans
 Treponema Denticola
PART II
T. Forsythia
P.Gingivilis
Capnocytophaga species
• Immunologic aspects of the
microbial host interaction
• Connective tissue alterations:
tissue destruction in
periodontitis
PART III
• Collagen destruction in host
bacterial interaction
• Mechanism of alveolar bone
destruction in periodontitis.
• Toll like receptors in
microbial host interaction
• Conclusion
• References
3

4. INTRODUCTION
•The mouth, like all external surfaces of the body and the gut, has a
substantial microflora living in symbiosis with a healthy host.
•The microflora of the mouth contains hundreds of species of aerobic
and anaerobic bacteria.
•Cultural studies indicate that more than 500 distinct microbial
species can be found in dental plaque.
4

5. •Although bacteria are necessary for periodontal disease to take
place, a susceptible host is also needed.
•The immune-inflammatory response that develops in the gingival and
periodontal tissues in response to the chronic presence of plaque
bacteria results in destruction of structural components of the
periodontium leading, ultimately, to clinical signs of periodontitis.
5

6. •The host response is essentially protective, but both hypo-
responsiveness and hyper-responsiveness of certain pathways can
result in enhanced tissue destruction (Bruce l Pihlstrom 2005 ).
•Closer investigations of the destructive pathway of periodontal
disease began to focus on the relation-ship between bacteria and the
host response in the initiation and progression of periodontal disease..
6

7. •This shift in etiological theory produced a paradigm that called
attention to the fact that although microorganisms are the cause of
periodontitis, the clinical expression of the disease depends on how
the host responds to the extent and virulence of the microbial
burden.
• It was found that degradation of host tissue results from this
bacterial-host interaction. (Casey Hein 2004)
7

8. A dynamic equilibrium exists between dental plaque bacterium and innate
host defense system. Dental plaque bacteria have adapted survival
strategies favoring growth, while the host limits growth by combination of
innate and adaptive immune responses. This interaction represents a highly
evolved interaction between bacteria and host.
8

9. WHAT IS HOST ?
An organism which harbors the parasite .
9

10. WHAT IS BACTERIA?
•Extremely small—usually 0.3 to 2.0
micrometers in diameter—and relatively
simple microorganisms possessing the
prokaryotic type of cell construction.
10

11. INTERACTION
•The combined effect of two or more independent variables acting
simultaneously on a dependent variable.
11

12. •Symbiosis: It is an association in which both host and parasite are so
dependent upon each other that cannot live without the help of other
and none of them suffers any harm from the association.
•Commensal: Is a non disease forming organism; part of the resident
flora.
•Commensalisms: is an association in which parasite is deriving benefits
without causing injury to its host.
12

13. •Parasitism: is an association where parasites gets benefits and the
host gets harmful effects.
•Mutualism: is an association where parasite and host both are
benefited.
13

14. •Pathogen :is an organism that causes disease.
•Opportunistic pathogens: are normally not
pathogenic , but are able to become so if their
local environment is changed, they can overgrow and
the microbial load can cause disease.
14

15. •Virulence : ability of a microorganisms to cause the disease
•Toxins : Anything that is injurious, destructive, or fatal
or
A poisonous substance, especially a protein, that is produced by living
cells or organisms and is capable of causing disease when introduced
into the body tissues but is often also capable of inducing neutralizing
antibodies or antitoxins.
15

16. ETIOLOGY OF PERIODONTAL DISEASE PAST
TO PRESENT
1960 Calculus Theory
1965 -1975 Nonspecific Plaque Theory
1975-1985 Specific Plaque Theory
1985- Today Host Bacterial Interaction Theory
16THE HOST-BACTERIAL INTERACTION THEORY AND THE RISK CONTINUUM: CASEY HEIN CONTEMPORARY ORAL HYGIENE DECEMBER 2004

17. BEFORE 1960 CALCULUS THEORY
17
Cascade equation : Calculus +
tooth = disease
Etiological Factors : Calculus
acted as mechanical irritant
thought to be the sole cause
of disease.
Clinical implications :
Prophylaxis every 6monthsto
remove calculus

18. 1965-1975 NONSPECIFIC PLAQUE THEORY
Cascade equation: too much
plaque + tooth = disease
Etiological factors : bacterial
plaque caused gingivitis and,
in great enough quantities,
would cause gingivitis to
progress to periodontitis; all
plaque was the same; too
much plaque caused disease.
Clinical implications : plaque
control alone could prevent
or control disease;
prophylaxis was
recommended
18

19. 1975-1985 SPECIFIC PLAQUE THEORY
Cascade equation : specific
bacteria +tooth = disease
Etiological factors : microbial
plaque became differentiated—
some bacterial species were
identified as pathogenic and
specifically virulent in evading
host defenses.
Clinical implications : discovery
that healthy sites had different
kinds of microbes than diseased
sites; DNA probe and sensitivity
testing introduced to identify
specific periodontal pathogens
responsible for disease
progression; eradication of
plaque still considered key.
19

20. 1985-TODAY HOST-BACTERIAL INTERACTION THEORY
Cascade equation : mixed
infection of bacteria + host
response to bacterial infection =
disease
Etiological factors : it is the
interaction of the host with
pathogenic bacteria that
determines whether periodontal
disease initiated or whether
disease progresses; recognition
of certain risk factors that make
certain patients more
susceptible to disease
Clinical implications : the
introduction of periodontal
disease risk assessment;
recognition of the need for a 2-
pronged approach to treatment
that includes the use of locally
applied antimicrobials and host
modulatory strategies, ie,
subdose doxycycline (periostat)
20

22. 22

23. •Periodontal disease has been referred to as a 'mixed bacterial
infection' to denote that more than one microbial species contributes
to the development of disease.
•In general, gram-negative facultative or anaerobic bacteria appear to
represent the predominant bacterial species that have been
implicated in the disease process include Porphyromonas gingivalis,
A cetemcomitans, Treponema denticola, Bacteroides forsythus,
fusobacterium nucleatum, Prevotella intermedia, Campylobacter
rectus, Peptostreptococcusmicros and Eikenella corrodens.
23

24. Formation
of plaque
Host tissue
invasion
Bacterial
evasion of
host
defense
mechanism
Virulence
factors of
different
micro-
organisms
24

25. FORMATION OF PLAQUE
Acquisition
Adherence or
retentation
Initial
survival
Longer term
survivial
Avoidance of
elimination
Multiplication
Elaboration
of virulence
factor
25
1. Invasion of
body tissue
2. Bacterial
endotoxins
3. Bacterial
enzymes
4. Exotoxins

26. HOST TISSUE INVASION
26
Mode of entry of bacteria:
• Through the ulceration in the epithelium
• Through gingival sulcus
• Through periodontal pockets
• Direct penetration of microorganisms
Organisms capable of invading tissues directly:(AAP 1996)
• Actinibacillus actinomycetum comitans
• P. gingivilis
• Fusobacterium nucleatum
• Trepanoma denticola

27. Advantages of tissue invasion:
• Tissues can provide reservoir for colonization
• Can not be eliminated easily by mechanical methods.
• Systemic antibodies are required to eliminate bacteria
• The presence of bacteria within the tissue makes periodontitis more resistance
to the treatment
27

28. BACTERIAL EVASION OF HOST DEFENSE MECHANISM
Direct damage to
polymorph nuclear
leucocytes and
macrophages
Reduced PMN
chemotaxis
Degradation of
immunoglobulins
Degradation of fibrin
Altered lymphocyte
function
Damage to crevicular
epithelium
Production of volatile
sulphur compounds
Degradation of
periodontal tissues by
bacterial enzyme .
28

29. VIRULENCE FACTORS OF DIFFERENT MICRO-ORGANISMS
Actinobacillus Actinomycetum Comitans
Treponema Denticola
T. Forsythia
P. Gingivilis
Capnocytophaga Species
29

30. ACTINOBACILLUS ACTINOMYCETUM COMITANS
•Actinomycetemcomitans is a gram-negative, non-spore
forming, non-motile, capnophilic , facultative anaerobic
coccobacillus .
•A. Actinomycetemcomitans can be classified into six
distinct serotypes (a–f) based on surface polysaccharides
located on the O side chains of lipopolysaccharide.
30

31. •The presence of A. Actinomycetemcomitans in subgingival
plaque has been associated with aggressive periodontitis
with serotype b twice as prevalent as serotype a .
•Animal studies have shown that serotype b induces the pro-
inflammatory cytokine interleukin-6 (IL-6) and IL-1
(another pro-inflammatory cytokine) from thymocytes than
serotype a or c.
31

32. ANTIGENS OF ACTINOBACILLUS ACTINOMYCETUM
COMITANS
Polysaccharid
e and
lipopolysaccha
ride
Leukotoxin
Extracellula
r proteolytic
enzymes
GroEL heat
shock
protein
Fimbriae
32

33. LIPOPOLYSACHRIDES OF AA
•It induce bone resorption by promoting differentiation of osteoclast
precursor cells and by activating osteoclast cells.
•Ito et al have reported that lipopolysaccharide from
A. Actinomycetemcomitans promotes differentiation of osteoclasts
in vitro in the presence of 1,25-dihydroxyvitamin D3 and
dexamethasone
33

34. LEUKOTOXIN OF AA
•Actinomycetemcomitans produces a 116 kDa immunomodulating
protein antigen, termed leukotoxin.
•The leukotoxin is a pore-forming protein and is a member of the
repeats-in-toxin (rtx) family of bacterial toxins.
34

35. •In a study by Zambon Et Al. Fifty-five percent of localized aggressive
periodontitis patients were shown to be infected with A.
Actinomycetemcomitans strains that produced a leukotoxin that was
able to lyse human peripheral blood polymorphonuclear leukocytes and
HL-60 cells (a promyelocytic cell line) in vitro.
35

36. At high concentrations the toxin binds non-specifically to cell
membranes forming large pores allowing the rapid influx of ca2+ and
loss of ATP resulting in necrosis.
At low concentrations the toxin binds to specific cell surface proteins
on susceptible cells and form small diameter pores allowing the
uncontrolled influx of na+ and the activation of apoptosis
36

37. •Thus the A. Actinomycetemcomitans leukotoxin is a potent cytotoxic
antigen able to kill immune cells, resulting in the dysregulation of the
host immune response and the release of a variety of enzymes and
reactive molecules from phagocytic cells that may result in tissue
damage and further inflammation .
37

38. EXTRACELLULAR PROTEOLYTIC ENZYMES OF AA
•Proteolytic activity in subgingival plaque, in particular trypsin-like
proteolytic activity, has been highly correlated with clinical
measurements of periodontitis.
38

39. proteolytic enzymes in A. actinomycetemcomitans culture supernatants have been
reported to degrade
IgG (all four subclasses)
Serum (but not secretory) IgA
IgM but not IgD or IgE in vitro.
Thus the proteolytic activity of A. actinomycetemcomitans may be an important
virulence factor involved in dysregulation of the host's immune response.
39

40. GROEL HEAT SHOCK PROTEIN OF AA
•A.Actinomycetemcomitans
produces an antigenic 64 kDa
GroEL protein that is equally
expressed on the cell surface of
all serotypes a–e.
40

41. •Heat shock proteins have been suggested to be associated with the
etiology and pathogenesis of both experimental and naturally occurring
autoimmune diseases such as juvenile chronic arthritis, rheumatoid
arthritis and atherosclerosis.
41

42. •Kirby et al. Reported the potent osteolytic active component in the
surface-associated material was identified as Groel, as a monoclonal
antibody inhibited A. Actinomycetemcomitans induced bone
resorption. GroEl stimulates the recruitment and activation of
osteoclasts in a dose dependent manner.
42

43. FIMBRIAE OF AA
•Actinomycetemcomitans produces highly
antigenic bundle-forming fimbriae that
are 5 nm in diameter and several μm in
length.
43

44. •The fimbriae are suggested to play an important role in colonization
as fimbriated A. Actinomycetemcomitans strains have greater
affinity for epithelial cells and saliva-coated hydroxyapatite than
non-fimbriated strains.
•Fimbriae may also have a role in A. Actinomycetemcomitans invasion
of epithelial cells by receptor-mediated endocytosis.
44

45. TREPONEMA DENTICOLA
•T. Denticola is a gram-negative, motile,
asaccharolytic, anaerobic spirochete with
typical helical morphology.
•Ultrastructure of the outer membrane sheath of T. Denticola is similar to
the outer membrane of other gram-negative bacteria. However, the lipid
composition of the outer sheath is similar to lipoteichoic acid of the cell
surface of gram-positive bacteria.
45

46. ANTIGENS OF TREPONEMA DENTICOLA
Lipopolysach
rides
Major
sheath
protein
Flagellum
Extracellula
r
proteolytic
enzymes
Other
antigenic
proteins
46

47. LIPOPOLYSACHRIDES OF T DENTICOLA
•Lipoprotein preparations of T. Denticola have been reported to induce
the inflammatory mediators, nitric oxide, tnf-α and IL-1 from
macrophages, in a dose dependent manner
•Gopalsami et al have reported that the outer membrane lipid of
T. Denticola was able to induce bone resorption .
47

48. MAJOR SHEATH PROTEIN OF TD
•A major surface protein and antigen of T. Denticola is the major
sheath protein (msp)
•It binds to host matrix proteins and form pores on gingival
fibroblasts, epithelial cells, lymphocytes and erythrocytes
48

49. •The 53-kda protein also enhances the inflammatory response by
triggering degranulation of polymorphonuclear cells and the specific
release of collagenase, gelatinase and matrix metalloproteinases mmp-
8 and mmp-9.
49

50. Flagellum of T d
•T. Denticola, like all spirochetes, result in a cork screw-like
locomotion, which aids movement in highly viscous environments like
gingival crevicular fluid and the penetration of gingival epithelial and
connective tissue.
50

51. •The flagellar filament consists of three core proteins flaB1 (35 kda),
flaB2 (35 kda) and flaB3 (34 kda) and a major sheath protein flaA
(38 kda).
•Although each of the filament proteins are antigenic, flaA and flaB3
have been shown to be the immunodominant antigens.
•FlaA has been suggested to have a role in adherence of T. Denticola
to host cells as it binds fibronectin .
51

52. EXTRACELLULAR PROTEOLYTIC ENZYMES OF TD
•Important extracellular protein antigens of T. Denticola are its
proteolytic enzymes, reviewed by Potempa Et Al.
•The prolylphenylalanine specific, chymotrypsin-like, serine proteinase
known as dentilisin or trepolisin, is the best characterized
T. Denticola protease. This enzyme occurs on the cell surface .
52

53. The proteinase has shown to degrade :
Bradyki
nin,
Substan
ce P
Angiote
nsin I
And II
Host
Proteas
e
Inhibito
rs Α1-
antitryp
sin,
Antichy
motryps
in,
А2-
macrogl
obulin,
Antithr
ombin
III,
Antiplas
min
Cystatin
C.
53

54. •Dentilisin degrade pro-Il1β into its bioactive forms and thus stimulate
the inflammatory response
•The ability to degrade host matrix proteins, inflammatory and
protease regulatory proteins and peptides may contribute to the
uncontrolled degradation of periodontal tissues and enhance disease
progression.
54

55. Ishihara et al found that dentilisin plays a
significant role in virulence.
• Helps t. Denticola to bind to the ground substance
glycosaminoglycan, hyaluronate
• Induce apoptosis in epithelial cells.
• Dysregulate the inflammatory response by degrading vasoactive
peptides, hormones and neuropeptide
55

56. OTHER ANTIGENIC PROTEINS OF TD
A putative hemolysin, a 46-kDa antigenic protein named CYSTALYSIN
is suggested to play a central role in
• Iron acquisition by T. Denticola as it is able to agglutinate and lyse
erythrocytes
• Cause the oxidation and sulphuration of hemoglobin
56

57. 57

58. 58

59. REFERENCES
The host-bacterial interaction theory and the risk continuum: casey hein,
contemporary oral hygiene december 2004
Text book of periodontology: carranza 10 th edn
Text book of microbiology: ananthnarayana 7th edn
Modulation of the host response in periodontal therapy. J periodontol. 2002;73(4):
460-470
Role of antigen in periodontal disease;periodontol 2000;2004;101
59

60. 60

61. WHAT IS HOMEOSTASIS ?
•Homeostasis, is the property of a system in which variables are
regulated so that internal conditions remain stable and relatively
constant. Examples of homeostasis include the regulation of
temperature and the balance between acidity and alkalinity (ph).
•The concept was described by Claude Bernard in 1865 and the word
was coined by Walter Bradford Cannon in 1926
61

62. BENEFICIAL MICROBES TO MAINTAIN HOMEOSTASIS
•Amongst the bacteria of more than 700 species now identified within
the human oral microbiota, it is the streptococci that are numerically
predominant.
•Streptococcus salivarius as an oral probiotic. (Burton JP et al benef
microbes. 2011 jun;2(2):93-101 )
•S. Sanguinis, S. Oralis, actinomyces naeslundii, neisseria subflava, and
veillonella dispar.(The pros and cons of oral bacteria by Rosemary )
62

63. PART II
63

64. CONTENT
PART II
T. Forsythia
P.Gingivilis
Capnocytophaga species
• Immunologic aspects of the microbial host
interaction
• Connective tissue alterations: tissue destruction
in periodontitis
PART III
• Collagen destruction in host bacterial interaction
• Mechanism of alveolar bone destruction in
periodontitis.
• Toll like receptors in microbial host interaction
• Conclusion
• References
64

65. P. GINGIVALIS
P. Gingivalis is a gram-negative, non-spore forming, non-motile,
asaccharolytic, obligate anaerobic coccobacillus.
65

66. P. GINGIVALIS ANTIGENS
Capsule
Lipopolysacch
aride
Fimbriae
Extracellula
r
proteolytic
enzymes
Heat shok
protein
Haemagglutini
ns
Antigenic
outer
membrane
proteins
66

67. CAPSULE OF PG
•One major surface antigen of P. Gingivalis is the capsule, a
polysaccharide hetero polymer up to 15 nm thick, that surrounds the
outer membrane.
•P. Gingivalis capsule also inhibits the attachment of periodontal
ligament fibroblasts to the tooth root surface and long-term
exposure to capsular-polysaccharide alters the properties of the
tooth root surface decreasing the ability of fibroblasts to attach.
67

68. •Encapsulated strains of P. Gingivalis are also more resistant to
phagocytosis by polymorphonuclear cells.
•Can multiply intracellularly, preventing neutrophil migration to the
site of inflammation, block the key step of inflammation , it also
decrease the ability of other MO to stimulate E- selectin on
endothelial cell.
68

69. The decreased ability to activate the alternative
complement pathway and the increase in cellular
hydrophilicity due to the capsular polysaccharide
are proposed mechanisms by which encapsulated
P. Gingivalis is resistant to phagocytosis.
69

70. LIPOPOLYSACCHARIDE OF PG
•P. Gingivalis lipopolysaccharide induces a variety of cytokines from a
number of different cells. Human gingival fibroblasts secrete the
pro-inflammatory cytokines Il-1β, IL-6 and IL-8 in response to
incubation with P. Gingivalis lipopolysaccharide .
70

71. •P. Gingivalis lipopolysaccharide also induces the secretion of nitric
oxide, Tnf-α, PGE-2 and IL-1 from human and murine macrophages .
•Stimulates the secretion of a higher amount of IL-6 via toll-like
receptors.
•Wendell and stein have shown that a combination of p. Gingivalis
lipopolysaccharide and nicotine had a synergistic effect upregulating
the expression of IL-6 and IL-8 in human gingival fibroblasts
71

72. •P. Gingivalis lipopolysaccharide is a potent inducer of bone resorption
by the stimulation of local Il-1α and Il-1β.
•Bomvan Noorloos Et Al have shown that other heat-sensitive
P. Gingivalis components have a greater role in activating osteoclasts
and inducing bone resorption.
•Isogai et al have suggested that P. Gingivalis lipopolysaccharide
induces apoptosis in t-cells.
72

73. FIMBRIAE OF PG
•The fimbriae are curly, single-stranded filaments, 5 nm in diameter
and are composed of fimbrillin .
•P. Gingivalis fimbriae are thought to be important for the adhesion of
the bacterium to host tissues.
•P. Gingivalis strains with type II fimbriae had a greater ability to
invade epithelial cells (types I–V) .
73

74. •Active invasion of endothelial cells by P. Gingivalis mediated via
fimbriae stimulates the expression of the surface cell adhesion
molecules ICAM-1, VCAM-1, P and E-selectins, thus recruiting
leukocytes to the site and enhancing the inflammatory response
•P. Gingivalis fimbriae have also been shown to stimulate the release of
Il-1α, Il-1β Tnf-α, neutrophil chemotactic factor, and Tnf-α, IL-6 and
IL-8 from polymorphonuclear cells
74

75. EXTRACELLULAR PROTEOLYTIC ENZYMES OF PG
•Pick et al. (1994) separated the trypsin-like activity in P. Gingivalis
culture supernatants called' gingipain' and found that there were two
separate cysteine proteinase activities, one with arginine and one with
lysine specificity.
75

76. HEAT SHOCK PROTEIN OF PG
•The P. Gingivalis heat shock protein GroEl is highly antigenic and anti-
p. Gingivalis GroEl antibodies have been detected in gingival tissue
extracts.
•P. Gingivalis GroEl may lead to an autoimmune reaction
76

77. HAEMAGGLUTININS
•The cell surface Haemagglutinating adhesin, HA-AG2, is a surface
antigen of P. Gingivalis all of the sera from chronic periodontitis
patients reacted with two HA-AG2 proteins with masses of 43 and 49
kDa .
•Specific antibodies to HA-AG2 have been shown to inhibit
haemagglutination and binding of P. Gingivalis to epithelial cells.
77

78. ANTIGENIC OUTER MEMBRANE PROTEINS
•Curtis and co-workers, have identified a 55 kDa major antigenic outer
membrane protein of P. Gingivalis .
•A number of studies have investigated the antigenic profile of the
outer membrane of P. gingivalis and have identified a range of
immunodominant proteins by their molecular mass.
78

79. •The 46 kDa antigen was suggested to be the predominant
immunoreactive protein with sera from patients with severe
periodontitis
79

80. T. FORSYTHIA
•T. Forsythia is a gram-negative, anaerobic, saccharolytic fusiform
bacterium.
80

81. T. FORSYTHEA ANTIGENS
Lipopolysachri
des
Extracellular
proteolytic enzymes
Other
antigenic
outer
membrane
proteins
81

82. LIPOPOLYSACHRIDES OF T. FORSYTHIA
Very little is known about the structure and chemical composition of
T. Forsythia lipopolysaccharide, however a study by Vasel Et Al
indicated that T. Forsythia lipopolysaccharide may be similar to
P. Gingivalis lipopolysaccharide.
82

83. EXTRACELLULAR PROTEOLYTIC ENZYMES OF T F
•Several studies have shown that T. Forsythia produces cell surface
proteolytic enzymes. These include the trypsin-like serine proteases
and hemolytic cysteine–protease
•T. Forsythia trypsin-like activity, together with trypsin-like activities
of T. Denticola and P. Gingivalis in subgingival plaque samples have
been correlated with clinical parameters of periodontitis
83

84. •The trypsin-like activity has been suggested to play a role in binding
of T. Forsythia to erythrocytes, polymorphonucleocytes and
fibroblasts .
•Using PCR Tan Et Al. Showed that T. Forsythia occurred in 91% of
subgingival plaque samples from chronic periodontitis patients
whereas only 9% of subgingival plaque samples from healthy patients
contained this genotype.
84

85. OTHER ANTIGENIC OUTER MEMBRANE PROTEINS
•T. Forsythia produces a protein that has been suggested to induce
apoptosis especially in lymphocytes by the formation of membrane
pores.
•A GroEL-like protein with a molecular mass of 58 kDa is also produced
by T. Forsythia which may have important implications for the immune
response
85

86. •A major surface antigen of T. Forsythia is BspA, a 98-kDa protein
sera from chronic periodontitis patients, but not from healthy
individuals, recognized recombinant BspA in a western blot analysis.
•BspA also has been shown to stimulate proinflammatory cytokine
production in THP-1 mononuclear cells via interaction with CD14 and
Toll-like receptor
86

87. CAPNOCYTOPHAGA SPECIES
•Capnocytophaga species is a group of facultative gram-negative
fusiform rods.
•They require co2 for growth in culture, hence their name.
•The Capnocytophaga species have been associated with localized
early-onset periodontitis Eikenella Corrodens
87

88. •Capnocytophaga ochracea has been correlated with the presence of
disease in localized juvenile periodontitis patients and was not found
in healthy subjects in a family study by Williams Et Al.
88PERIODONTOLOGY 2000, VOL. 26, 2001

90. •Innate factors such as complement, resident leukocytes and
especially mast cells play an important role in signaling endothelium,
thus initiating inflammation.
• Acute inflammatory cells (i.e. Neutrophils) protect local tissues by
controlling the periodontal mcirobiota within the gingival crevice and
junctional epithelium .
90

91. •Chronic inflammatory cells, macrophages and lymphocytes protect the
entire host from within the subjacent connective tissue and do all
that is necessary to prevent a local infection from becoming systemic
and life threatening.
91

92. Acute bacterial
challenge phase
Acute
inflammatory
response
Immune
response phase
92

93. ACUTE BACTERIAL CHALLENGE PHASE
There is a very high turnover of epithelium -that permits rapid replacement of cells and tissue components
damaged by microbial challenge.
The gingival crevicular fluid flushes the sulcus or pocket and delivers complement proteins and specific antibodies.
Salivary secretions provides continuous flushing and supply of agglutinins and specific antibodies.
The intact epithelial barrier of the gingival, sulcular and junctional epithelium prevents bacterial invasion.
The epithelial and vascular elements response to bacterial challenge
93

94. ACUTE INFLAMMATORY RESPONSE
Vascular leakage enhances the localized response:
Leukocytes selectively emigrate from the vessels to alter the immuno-inflammatory cell
populations in the gingival tissues
Neutrophil migration into the gingival sulcus:
The inflammatory infiltrate within the tissues:
• Opsonization
• Phagocytosis
94

95. VASCULAR LEAKAGE ENHANCES THE LOCALIZED
RESPONSE
•In the presence of lipopolysaccharide or cytokines, the endothelial cells
of the microcirculation become activated. The vessels of the
microcirculation become inflamed, dilated and engorged with blood, and
the blood flow slows.
•The endothelial cell junctions open and protein-rich fluid leaves the
vessels at the site of the post-capillary venules /and accumulates in the
extra cellular matrix.
95

96. LEUKOCYTES SELECTIVELY EMIGRATE FROM THE VESSELS
TO ALTER THE IMMUNE INFLAMMATORY CELL POPULATIONS
IN THE GINGIVAL TISSUES
•Neutrophils are believed to play an important role in controlling the
periodontal mcirobiota. They are the first leukocytes to arrive at the
site of inflammation and are always the dominant cell type within the
junctional epithelium and the gingival crevice
96

97. •Neutrophils exit the inflamed vessel of the' microcirculation and
migrate through the connective tissues and junctional epithelium, to
form a barrier between the subgingval microbial plaque and the
gingival tissue
•There is specific interactions among vascular cell adhesion molecules
and leukocyte integrins and thus the chance of inducing leukocyte
extravasation by diapedesis into the extravascular spaces.
97

98. NEUTROPHIL MIGRATION INTO THE GINGIVAL SULCUS
•Following extravasation, neutrophils seem to gain access to the more
coronal portion of the junctional epithelium and to selectively migrate
through this multilayered epithelium to gain access to the bacterial
flora.
98

99. Two mechanisms of possible importance in the regulation of neutrophil
migration towards the gingival sulcus or the periodontal pocket following
neutrophil extravasation:
The expression of leukocyte adhesion molecules such as the intercellular
adhesion molecule I, in epithelial cells.
Cytokines with potent and cell type-specific leukocyte chemotactic
properties: the chemokines and the neutrophil-selective interleukin 8, in
particular.
99

100. THE INFLAMMATORY INFILTRATE WITHIN THE
TISSUES:
Opsonization Phagocytosis
100

101. OPSONIZATION
•Opsonization- refers to the coating of particles, such as bacteria,
with host proteins that facilitate phagocytosis.
•Specific antibody of the IGg isotype also facilitates phagocytosis
directly by binding with the neutrophil Fc receptor and appears to be
essential for phagocytosis of certain periodontal pathogens.
101

102. Patients with periodontitis often exhibit very high serum titers of IGg
to specific periodontal pathogens
102

103. PHAGOCYTOSIS
•Once the bacterial cell is bound to the neutrophil , ingestion
(phagocytosis) results in entrapment of the bacterial cell into the
membrane delimited structure known as the phagosome.
•Bacteria within the phagosome and phagolysosome may be killed by
oxidative or nonoxidative mechanisms
103

104. IMMUNE RESPONSE PHASE
•The bacterial products and epithelial derived cytokines activate the
local tissue mononuclear cells that shape the local immune response.
• Macrophages have been reported to be few in healthy gingiva.
Although increased in gingivitis, periodontitis, macrophage density
remain in low proportions relative to other cell types.
104

105. 105

107. FACTORS CAUSING TISSUE DESTRUCTION
Bacterial
products
Proteinases
Cytokines
Prostagland
-ins
Reactive
oxygen
species
107

108. BACTERIAL PRODUCTS
•Degrade basement membrane and extracellular matrix proteins
including collagen, proteoglycans, and glycoproteins. This would
destroy periodontal connective tissue and facilitates bacterial
invasion.
•Interferes with tissue repair by inhibiting clot formation or lysing
the fibrin matrix in periodontal lesions.
108

109. •Activates latent host tissue collagenase which would enhance host-
tissue enzyme mediated tissue destruction.
• Inactivates proteins important in host defense.
109

110. PROTEINASES
•Matrix metalloproteinases (mmps) are considered to be primary
proteinases involved in periodontal tissue destruction by degradation
of extracellualr matrix molecules.
•They degrade extracellular matrix molecules, such as collagen, gelatin
and elastin.
110

111. •MMP-8 and MMP-l both collagenase are elevated in tissues and GCF
associated with periodontitis
•Elastase is capable of degrading wide range of molecules including
elastin, collagen, and fibronectin.
111

112. CYTOKINES
•Both IL-I and TNF-a induce production of proteinases in
mesenchymal cells, including MMPs, which may contribute to
connective tissue destruction.
•Il-I and TNF-a found in significant concentrations in GCF from
periodontally diseased sites.
112

113. •Increasing severity of periodontitis is associated with increased
concentrations' of IL-I and decreasing concentrations of IL-Ira .
•In a primate model of experimental periodontitis, application of
antagonists to IL-1 and TNF resulted in an 80% reduction in
recruitment of inflammatory cells in proximity to the alveolar bone
and a 60%reduction in bone loss.
113

114. PROSTAGLANDINS
•Prostaglandins are arachidonic acid metabolites generated by
cyclooxygenases (COX-I, COX-2).
•Cox-2 is upregulated by IL-Ib , TNF-a and bacterial LPS and appears to be
responsible for generating the prostaglandin PGE2 that is associated with
inflammation.
•PGE2 is increased in periodontal sites demonstrating inflammation and
attachment loss.
114

115. Elevated prostaglandin E2 levels are detected in the
gingiva and gingival crevicular fluid of patients with
periodontal diseases, compared to periodontally healthy
subjects in 1974, Goodson Et Al. reported a 10-fold
increase of prostaglandin E2 levels in inflamed gingival
tissue, compared with healthy gingival tissue.
115

116. REACTIVE OXYGEN SPECIES
•Any species capable of independent existence that contain one or more
unpaired electrons.
•Inflammatory cells and in particular PMN once stimulated produce
reactive oxygen species via metabolic pathway of the respiratory burst,
which occurs in the process of phagocytosis.
116

117. •These includes superoxide anion, hydrogen peroxide, hydroxyl radicle
and hyperchlorus acid.
117
ROS can
cause
Protein
damage
Lipid
Peroxidation
DNA
damage

118. 118

119. 119

120. 120

121. ROLE OF GINGIPAIN
•Pick et al. (1994) separated the trypsin-like activity in P. Gingivalis
culture supernatants called' gingipain' and found that there were two
separate cysteine proteinase activities, one with arginine and one with
lysine specificity
121

122. Arg-gingipain have been found potently to enhance vascular permeability.
These enzymes increase gingival crevicular fluid production and thus provide
a continuous supply of nutrients for the bacterium, enhancing its growth and
virulence.
Arg-gingipain has also been found to be a very efficient enzyme for the
production of the potent chemotactic factor c5a by directly cleaving the C5
component of complement.
These enzyme also degrades c3,and in this way eliminates the creation of
c3-derived opsonins. This render sp. Gingivalis more resistant to
phagocytosis by neutrophils
122

123. Fibrinogen is a major target for lys-gingipain and it thus increases the
local clotting time, leading to gingival bleeding.
The bleeding of periodontal sites is of primary importance for the growth
of P. Gingivalis, since it ensures the rich source of haem and iron that it
requires for survival.
Gingipains act as adhesins and have a strong binding affinity for
fibrinogen , fibronectin and laminin. It inhibits haemagglutination.
Since these complexes are present on the surfaces of both the vesicles
and membranes of P. Gingivalis , they may play an important role in the
attachment of this bacterium to host cells.
123

124. RESPIRATORY BURST
•Respiratory burst (sometimes called oxidative burst) is the rapid
release of reactive oxygen species (superoxide radical and hydrogen
peroxide) from different types of cells.
•Usually it denotes the release of these chemicals from immune cells,
e.G., Neutrophils and monocytes, as they come into contact with
different bacteria or fungi .
124

125. •Respiratory burst plays an important role in the immune system. It is
a crucial reaction that occurs in phagocytes to degrade internalized
particles and bacteria.
•NADPH oxidase, an enzyme family in the vasculature (in particular,
in vascular disease), produces superoxide, which spontaneously
recombines with other molecules to produce reactive free radicals.
125

126. •The superoxide reacts with NO, resulting in the formation
of peroxynitrite, reducing the bioactive NO needed to dilate
terminal arterioles and feed arteries and resistance arteries.
•Superoxide anion, peroxynitrite, and other reactive oxygen species
also lead to pathology via peroxidation of proteins and lipids, and via
activation of redox-sensitive signaling cascades and protein
nitrosylation
126

127. •Myeloperoxidase uses the reactive oxygen species hydrogen
peroxide to produce hypochlorous acid. Many vascular stimuli,
including all those known to lead to insulin resistance, activate NADPH
oxidase via both increased gene expression and complex activation
mechanisms.
•To combat infections, immune cells use NADPH oxidase to reduce
o2 to oxygen free radical and then H2O2.
127

128. •Neutrophils and monocytes utilize myeloperoxidase to further
combine H2O2 with cl- to produce hypochlorite, which plays a role in
destroying bacteria. Absence of NADPH oxidase will prevent the
formation of reactive oxygen species.
128

129. ZIPPER MECHANISM
The zipper mechanism, ingestion occurs by sequential engagement of a
phagocyte's membrane against the particle surface, and pseudopod
advance proceeds no further than receptor-ligand interactions permit.
129

130. SPECIFIC RESPONSE OF CAPSULE
TOWARDS HOST
•The capsule of porphyromonas gingivalis leads to a reduction in the
host inflammatory response .
•A study done by Tiana Wyant et al in 2011 reported that the higher
virulence potentials of encapsulated strains than of non encapsulated
ones, evaluated using a mouse abscess model.
130

131. •Encapsulated P. Gingivalis strains trigger different host responses
than nonencapsulated mutant strains , thus indicating that the
presence of a capsule indeed has immunomodulating properties.
•The capsular polysaccharide locus has been identified by Aduse-opoku
et al. , which allowed for the generation of isogenic capsule-deficient
mutants.
131

132. •The analysis of such a mutant by Brunner Et Al. has shown that
encapsulation reduced the production of cytokines interleukin-1 (IL-
1), IL-6, and IL-8 by fibroblasts in response to P. Gingivalis infection ,
thus further demonstrating that the capsule modulates the host
response to bacteria
132

133. PART III
133

134. CONTENTS
• Collagen destruction in host bacterial interaction
• Mechanism of alveolar bone destruction in periodontitis.
• Toll like receptors in microbial host interaction
• Conclusion
• References
134

136. •Tissue remodeling is usually tightly regulated by a complex interplay
of cell-cell and cell-matrix interactions involving the production of
enzymes, activators, inhibitors and regulatory molecules such as
cytokines and growth factors.
•The accelerated breakdown of connective tissues occurring in
pathological situations, such as periodontal diseases.
136

137. •The endopeptidases (or proteinases) are key enzymes in tissue
degradative processes, since the protein components of most
matrices are the predominant determinants of tissue structure and
function.
137

138. •Collagenase :
Collagenase 1 or MMP 1 or fibroblast collagenase can hydrolyses
collagen type 1,2,3,6,8,and 10
Collagenase 11 or MMP 8 or PMN’s collagenase can hydrolyze collagen
type 1 and 3
•Gelatinase :
MMP 2 and MMP 9 can degrade collagen type 4, 7, 10 and 11 and
Elastin.
138

139. Stromeolysin :
•Stromeolysin 1
•Stromeolysin 2
•Stromeolysin 3
Degrade proteoglycans, basement membrane , laminin and fibronectin.
139

140. •Higher levels of antibodies to collagen type I were found in the
peripheral blood of patients with periodontitis than in healthy
controls.
•In addition to antibodies to collagen type-1 there are several other
types of auto reactive components. Increased reactions of IgG auto
antibodies to desmosomal proteins were observed in sera from
patients with periodontitis in comparison to sera from controls.
140

141. •Two regulators of MMP expression are IL-1 AND TGF-β
These substance are present in inflamed tissue (Sodek And Overall
1992)
•In macrophages MMP production is stimulated by LPS and inhibited by
INF-γ, IL-4 and IL-10.
141

142. 142

143. MEDIATORS AFFECTING COLLAGEN
143

144. Increase in collagen synthesis:
• PDGF
• TGFβ
• FGF
• IGF
Decrease In Collagen Synthesis:
• Cytokines
• IL-1αβ
• INFγ
• TNFα
• Hormones like Glucocorticoids
• Others like PGE2
144

146. Bacterial factors
• Capsular and surface associated material
• LPS
• Lipoteichoic acid
• Peptodoglycans
• Muramyl dipeptide
• Lipoprotein
Host factors
• Inflammatory mediators
• PGE2
• Leukotrienes
• 12- HETE
• Heparin
• Thrombin
• Bradykinin
• Cytokines
• IL-1
• IL-6
• TNF
• TGF β
• PGDF
146

147. Bone loss in periodontal disease are listed by Haussmann in 1974
•Direct action of plaque products on bone progenitor cells induce their
differentiation into osteoclasts.
•Plaque products acts directly on bone destroying it through a non-
cellular mechanism.
147

148. •Plaque products stimulate gingival cells, causing them to release
mediators which in turn trigger bone progenitor cells to differentiate
into osteoclasts.
•Plaque products cause gingival cells to release agents that can act as
co-factor in bone resorption.
•Plaque products can cause gingival cells to release agents that destroy
bone by direct chemical action without osteoclasts.
148

149. MECHANISM OF BONE RESORPTION (BERKOVITZ)
Osteoblast
induced
Osteoclast
induced
149

150. OSTEOBLAST INDUCED
•All systemic and local bone resorbing factors exert their influence
by stimulating osteoblasts.
150

151. •Osteoblasts are involved in the regulation of osteoclasts function
because they have receptors for systemic factors such as
parathromone and 125-OH2 and locally produced factors such as
prostaglandins, leukotrienes and cytokines which effects local
changes and exert their influence by stimulating osteoblasts (Meikle
et. Al 1986)
151

152. •Stimulated osteoblasts stimulate osteoclast formation by secretion
of cytokines, growth factors in particular granulocyte macrophage
colony stimulating factors and macrophage colony stimulating factor
and interleukin-6.
152

153. •IL-6 secretion is stimulated by IL-1 attachment to osteoblasts
receptor. All these secreted cytokine in presence of IL-3 can
stimulate the development of precursors cells in marrow , these
precursors cells are stimulated by IL-6 to become osteoclasts
153

154. •Bone resorbing agent such as PTH hormone stimulates osteoblast to
synthesize and collagenase and plasminogen activator which digests
the osteoid exposing the mineralizing matrix which may be
chemotactic to osteoclast
•Osteoblasts release short range soluble activators for osteoclasts
(clinical oral science Harris and Edgar )
154

155. OSTEOCLAST MEDIATED
Osteoclastic
resorption
involves
Solubilization
of mineral
phase
Dissolution
of organic
matrix
155

156. •The resorption area is defined beneath the ruffled border of
osteoclast. This is highly specialized region of cytoplasmic in
folding of plasma membrane, this contains podosomes which are
specialized protrusion of the ventral surface of osteoclasts which
adhere directly to the bone surface being broken down.
•Osteoclasts also produce ROS which may play a role in
pathological demineralization of bone during disease (Gaarrett Et
Al in 1990)
156

157. •Osteoclasts : osteoclastogensis is enhanced by PTH, calcitriol,
PGE2, thyroxin and IL-11.
•Formation of active osteoclasts require MCSF and involve cell to
cell contact between precursors of monocyte-macrophage lineage
and osteoblasts, stromal cells, these cells express receptors
activator of NF-kb ligand (RANKL).
•RANKL attaches to RANK, A receptor on the cell surface of
osteoclasts and osteoclasts precursors to stimulate proliferation
and differentiation of cells to form osteoclast phenotype
157

158. •In the presence of
periodontopathic organisms
CD4+ T cells presents
increased expression of
RANKL, triggering the
activation of osteoclasts and
causing bone loss.
158

159. ROLE OF NO IN BONE RESORPTION
There is good evidence to suggest that NO(nitric oxide) has biphasic
effects on osteoclastic bone resorption.
Low concentrations of no have been shown to potentiate IL-1 induced
bone resorption, based on the observation that NO inhibitors inhibit
IL-1 induced bone resorption in vitro. Constitutive production of NO
within osteoclasts has been suggested to be essential for normal
osteoclast function.
159

160. 160

162. •Toll gene products were first
discovered in 1985 and were described
as being critical for the embryonic
development of dorsal–ventral polarity
in the fruit fly, drosophila.
•They contain common extracellular
leucine-rich domain and a conserved
intracellular domain.
162

163. •They are critical for
recognition of microbes by the
innate immune system and for
bridging the innate and
acquired immune system.
163

165. •Toll-like receptors are predominantly expressed on cells of the innate
immune system, including neutrophils, dendritic cells and
monocytes/macrophages.
•These cells express different toll-like receptors, allowing them to
induce a wide variety of immune responses to specific pathogens.
165

166. •Neutrophils, the predominant innate immune cells in blood, express
toll-like receptor 1, 2, and 4 and TLR 10.
•They play a key role in host defense by recognizing, engulfing, and
killing microorganisms.
166

167. •Monocytes/macrophages express toll-like receptor 1, 2, toll-like
receptor 4, and 8.
•Recent report shows that activation of toll-like receptor 1 ,2 on
monocytes leads to their differentiation into macrophages rather
than dendritic cells.
167

168. SUMMARY
168

169. CONCLUSION
•The host-bacterial interaction theory may explain why otherwise
healthy individuals with moderate levels of plaque do not exhibit loss
of periodontal support. In these individuals, PMNS are effective in
blocking invading pathogens without destroying the collagen content
of the periodontium in the process.
169

170. •If these same pathogens attempted to invade the periodontium of
people predisposed to periodontal disease, it appears that impaired
chemotaxis and phagocytosis of defense cells may put these
individuals at significantly greater risk for progressive periodontal
destruction.
170

171. REFERENCES
The host-bacterial interaction theory and the risk continuum: casey hein,:
contemporary oral hygiene December 2004
Text book of periodontology: Carranza 10 edn
Text book of microbiology: Ananthnarayana 7 edn
Mechanisms tissue matrix of connective destruction in periodontitis; john j.
Reynolds & murray c. Meikle; periodantology 2000, vol. 14, 1997,144-157
171

172. Oringer rj. American academy of periodontology, research, science, and therapy
committee. Modulation of the host response in periodontal therapy. J periodontol.
2002;73(4): 460-470.
The role of reactive oxygen and antioxidant species in periodontal tissue destruction
periodontology 2000;2007;vol43
Toll-like receptors and their role in periodontal health and disease. Periodontology
2000;2007;vol43;41-50
172

173. 173