This document discusses the immune responses involved in periodontal disease. It begins by defining periodontitis as an infectious disease caused by anaerobic bacteria. Both bacteria and a susceptible host are required to cause disease. It then describes the pathogenesis which involves environmental and genetic risk factors interacting with the microbial challenge to activate the host immune response, resulting in inflammation and bone/tissue destruction. The document discusses the types of immunity, including innate and adaptive immunity. It covers topics such as dendritic cells, T-cell and B-cell roles, the roles of cytokines and RANKL in linking the immune response to bone loss, and hypotheses about the roles of the Th1 and Th2 responses in periodontitis.

1. IMMUNE RESPONSES IN
PERIODONTAL DISEASE
DR.N.AMBALAVANAN
Prof & Head Dept. of Periodontics
Meenakshi Ammal Dental College
Chennai

2. Periodontitis is an infectious disease caused
by a small group of predominantly anaerobic,
Gm - bacteria
Bacteria are important but insufficient to
cause disease
A susceptible host is essential

3. PATHOGENESIS OF PERIODONTITIS
Environmental & Acquired risk factors
Genetic risk factors
Microbial
Challenge
Host
Immuno
Inflam.
response
Connective
Tissue
Bone
metabolism
Clinical signs
Of disease
initiation &
progression
Antibody
PMNs
Antigens
LPS
Cytokines &
Prostanoids
Roy C.Page – Annals of Periodontology
MMPs

4. IMMUNITY IS RESISTANCE
We need immunity against
Pathogenic Bacteria (Extra and Intracellular)
Viruses (Intracellular)
Fungi
Protozoa
Other parasites
and also to protect us from
Neoplastic cells

5. TYPES OF IMMUNITY
– INNATE IMMUNITY
– ADAPTIVE IMMUNITY

6. INNATE IMMUNITY

7. ADAPTIVE IMMUNITY
•Evolved in higher forms of life
•It is the most complex structural
and functional immune system
•Development & Evolution of
MHC along with T cell
differentiation are the hall marks
of Adaptive immunity

8. •Hypersensitive reactions
•Autoimmune disorders
•Graft rejection
•Excessive production of
inflammatory cytokines
Drawbacks of Adaptive Immunity

9. NEED FOR ADAPTIVE IMMUNITY IN HIGHLY
EVOLVED LIFE FORMS
•Longevity associated with neoplasms
and more viral infections
•Emergence into land and exposure to
solar radiation
•Homiothermy (warm blooded)
•Viviparity

11. •Low molecular wt. proteins secreted by
many cells (previously known as
Lymphokines)
•Assist in the regulation and development
of Immune effector cells
•Cell to Cell communication
•Direct effector function
•Autocrine, Paracrine or endocrine
•Pleiotrophic
CYTOKINES

12. IF PROTECTIVE
Can we prevent?
(by immunization)
Can we arrest?
(when disease has occurred
IF NOT PROTECTIVE & TISSUE DESTRUCTIVE
Is host modulation the only answer?
IMMUNE RESPONSE IN PERIDONTAL
DISEASES

13. SEQUENCE OF IMMUNE RESPONSE IN PERIODONTAL DISEASES
• Innate factors – complements, mast cells sends
signals to endothelium thus initiating
inflammation.
• Acute inflammatory cells (neutrophils) protect
local tissues by controlling the periodontal
microbiota within the gingival crevice and JE
• Chronic inflam.cells - macrophages and
lymphocytes protect the entire host from
within the subjacent connective tissues and do
all that is necessary to prevent a local infection
from becoming systemic and life threatening

15. Innate & Adaptive Immune responses in Periodontal disease
NEED TO KNOW
• Pathogen associated Molecular Patterns
• Toll like receptors
• Antimicrobial peptides in the gingival epithelia
• Bacterial antigens associated with periodontitis
• APCs in gingiva
• Role of T cells (TH1 or TH2 response)
• Osteoimmunology (RANK & RANKL)
• Autoimmune components in periodontal
disease
• Periodontal vaccine

16. INNATE
&
ADAPTIVE RESPOSES
IN PERIODONTAL DISEASE

17. Innate immunity (non-specific)
Physical barrier of sulcular and
junctional epithelium with
antimicrobial peptides,
phagocytic and Nkcells
Adaptive immunity (Specific)
Comes into play once the epithelial
barrier is breached.
MHC system, Lymphocytes and
Cytokines are central to adaptive
immune response
Innate & Adaptive immunity in Periodontium

18. INNATE IMMUNITY IN PERIODONTAL DISEASES
•Wall of neutrophils between the bacteria and the JE
•Diminished function of neutrophils (intrinsic defect)
responsible for the establishment and severity of
periodontal diseases ?
•Antigens released from bacteria
modulate the inflammatory response
eg. lipopolysacchrides,
lipoteichoic acid ,
Peptidoglycans,
lipid A proteins
e

19. •Pattern recognition of core
bacterial components by
phagocytic cells
•Pattern recognition
receptors (PRRs) have the
ability to discriminate
between self and non-self
•Recognition of common
bacterial patterns ensures
Polyspecificity
INNATE DEFENSE by bacterial recognition

20. TOLL LIKE RECEPTORS
• Transmembrane receptors named in reference to
the class of genes in Drosophila known as
Toll.Drosophila
• Part of innate immune response of
Drosophila to pathogens
• Related proteins (toll-like receptors)
are present in the mammals
• Expressed in a number of tissues and a variety of
cell types (Dendritic cells, epithelial cells, PMNs )
• Respond to bacterial LPS, lipoproteins, fimbriae etc

21. Response of Toll like Receptors
•TLR 2 responds to lipoteichoic acid
and microbial lipoproteins
•TLR 4 responds to LPS
•TLR 5 responds to Flagellin
•TLR 9 responds to bacterial DNA
Bar code detection system
•TLR5 + TLR4 = Flagellated Gm - bact.
•TLR2 + TLR5 = Flagellated Gm+ bact.

22. MICROBIAL COMPONENT RECOGNITION &
INTRACELLULAR SIGNALLING
•Recognition through Toll-like receptors
•Innate cell receptor binds to specific ligands
•Response is immediate (hallmark of Inn.imm.)
•Intracellular signaling through
MAPK (mitogen activated protein kinase),
PI3K (Phosphotidyl Inositol – 3 kinase) signaling
transduction pathways
•Expression of inflammatory cytokines with
enhanced clearance of bacteria by promoting
phagocytosis

23. Kinane et al

24. ALTERED INNATE IMMUNE RESPONSE
•Toll like receptor polymorphism and
other genetic polymorphisms
•Immunosuppressive therapy and
neutrophil defects
•P.gingivalis LPS disrupts the
innate immune response by host
cells within gingival tissues
P.g LPS is a natural antagonist
of E selectin expression. Thus
disrupting the host response
to other bacteria

25. INNATE IMMUNITY
ANTIMICROBIAL PEPTIDES
•JE & SE serves not only as a physical barrier
but also has diverse range of antimicrobial
peptides which can kill a range of bacteria
•More than 800 of these molecules are identified
•Eg.-neutrophil defensins, β defensins, Cathelicidins
lysozyme, histatins, proline rich proteins, salivary
agglutinin, cystatins, lactoferrins, salivary
peroxidase, mucins, etc

26. • Membrane permiabilization,
• Cell wall degradation,
• Intracellular inhibition
• Bacterial aggregation and oxidation
•Toll like receptors induce defensin gene expression
by epithelial cells
•Defensins disrupt microbial cell wall resulting in
leakage of contents
Functions of Antimicrobial Peptides

27. MECHANISM OF PORE FORMATION IN
BACTERIAL CELL WALL BY DEFENSINS
(Shai – Matsuzaki – Huang model)
Defensins are attracted electrostatically to the
negatively charged cell membrane.

This is followed by displacement of membrane
lipids in wedge like manner.

Disruption of the microbial cell wall results in the
leakage of the cytoplasmic contents.

28. Mechanism of pore formation in
bacterial cell wall by defensins

29. •Activate the classical complement
pathway
•Upregulate IL8 production
•Chemotactic for both CD8 + and CD4 +
T cells and immature dendritic cells.
•Enhance the release of TNF α and IL1
from monocytes activated by bacteria
DEFENSINS - LINK INNATE AND ADAPTIVE
IMMUNE RESPONSES

30. •Oral, sulcular, junctional epithelia are
associated with Defensin expression
•Neutrophil defensins are found in JE &
connective tissue in association with
PMNs
•β defensins are found in oral epithelia
of diseased sites. They are expressed
in healthy gingiva also probably in
response to commensal oral bacteria
GINGIVAL DEFENSINS

31. •Expressed in oral and airway epithelia
•Related to mammalian lipid binding
proteins
•These antibacterial proteins have
selectivity for Gm – bacteria
•Binds to LPS and exhibits anti-
inflammatory activity
Bactericidal/permeability-increasing
protein like proteins

32. Bacterial Antigens Associated with Periodontitis
• Over 20 bacterial species are implicated in
the pathogenesis of Periodontitis.
• Four bacterial species may be considered
as major pathogens
- P.gingivalis, B.forsythus, T.denticola,
A.actinomycetemcomitans

33. Identification of Pathogen’s Antigens
• Proteomic and Genomic Analysis:-
by (2D)-PAGE(PolyAcrylamide Gel
Electrophoresis) and by Western
Blot and mass spectrometric
techniques (PMF)
• Epitope mapping analysis:-
Identifying B cell & T cell antigenic
determinants by using computer
algorithm

34. DENTRITIC CELLS
(Antigen presentation)

35. Dentritic cells
• Dendritic cells represent a large family of APC
• They are scattered in nearly all tissues of the body
• Serve as a ‘bridge’ between innate
and adaptive immune response
• Maintain mucosal immune homeostasis
to harmless commensal bacteria and to self
antigens
• Capture microbes and their antigens
and present them in a mature form to
the T cells

36. Human Dendritic Cells
Blood
Myeloid DC
Plasmocytoid / Lymphoid DC
Langerhans Cells (LCs) (in epidermis/epithelium)
Interstitial DC (dermal DC) (in dermis/lamina propria)
Lymph stream
Veiled cells
Secondary lymphoid organs
Interdigitating DC
Germinal Center
Peripheral tissues

37. • CD1a + Langerhans cells are the principal
cells involved in the response of oral
mucosal epithelium to infection.
• Large numbers are present within the
healthy gingival epithelium.
• Langerhans cells increase in number in
gingivitis, experimental gingivitis &
periodontitis.
• Activated L cells ‘stall’ in the lamina
propria and become CD83 + mature
dendritic cells
Langerhans Cells in oral mucosa

38. • Apart from oropharyngeal and
nasopharyngeal associated lymphoid
tissues OLF is initiated in gingivitis by
Langerhans cells or their progenitors
homing to the gingival epithelium in
response to PAMPs
• OLF develops interproximally around the
teeth in periodontitis
• Formation of OLF is dependant on mature
dendritic cells becoming stalled within the
gingival lamina propria in the presence of a
disregulatory cytokine milieu.
Oral Lymphoid follicles

39. HEALTHY PERIODONTITIS

40. • Immature dendritic cells possess an array of
surface receptors that can recognize specific
microbes by their molecular patterns
• Important surface receptors are Toll like receptors
and C- type lectin receptors
• Best characterized molecular patterns are LPS,
peptidoglycans, other constituents of cell wall and
bacterial DNA
• Interaction leads to receptor agonist signal
transduction within dendritic cells which then
recognizes the antigen as ‘friend or foe’
Antigen recognition by APCs

41. Cytokines in Dendritic cell maturation
IL-1β and TNF α becomes elevated in
chronic periodontitis and play direct
role in
a) Stimulating dendritic cell
maturation
b) Dendritic cell migration out of
the epithelium towards the
lymphatics
c) Differentiation and Clonal
expansion of T Cells

42. Role of dendritic Cells in the
immunopathology of chronic periodontitis (Cutler & jotwani)

43. Dentritic cell derived osteoclasts (Cutler & Teng)

44. • T cell lesion conversion to B cell lesion
(Seymour et al 1979)
• Altered CD4/CD8 ratio (Kinane et al 1989)
• Polyclonal B cell activation (Tew et al.
1989)
• Autologous mixed lymphocyte reactions
(Kimura et al. 1991)
• Antigen restricted immune responses
(Ohyama et al.1998)
• Th1/Th2 cytokine profiles (Taubman &
Kawai 2001, Berglundh et al. 2002)
Role of T&B cells in the pathogenesis of Periodontitis

45. ROLE OF T CELLS

46. Activation of antigen specific T cells by
APCs require 2 major signals.
• Specific antigen recognition (Signal 1) and
Costimulation (Signal 2).
• Signal 1 is provided by the peptide-antigen-MHC
molecule interaction on the dendritic cells with
T cell receptors.(implies that the microbes have
been captured and processed)
• Signal 2 plays cooperative role in activating T
cells for efficient antigen presentation (B7
molecules, ICAM, LFA-3, CD 40).
Activation of T cells

47. • Implicated in the pathogenesis of
Ch.inflammatory Periodontal disease
• Immunity to infection is controlled by
distinct subset of T cells(Th1 and Th2
cells) classified on the basis of their
cytokine profile
• T cells may be induced to produce up to 22
different cytokines.
• Another subset of Tcells with
immunosuppressive function and distinct
cytokine profile called regulatory T cells
has recently been described
Role of T cells in infection and Inflammation

48. Regulatory T cells
Three subsets of Regulatory T cell
• Tr1- secrete high levels of IL-10 and low to
moderate levels of TGF β– prevents
development of Th1 mediated autoimmune
diseases and suppresses responses to
pathogens
• Th3 CD4 + cells which secrete TGF β
• CD4 + CD25 + Tcells causes
immunosuppression by inhibition of IL2
production

49. • Th1 and Th2 cells determine whether cell
mediated or humoral immunity dominates
• IFNγ produced by Th1 cells inhibit Th2
cells while IL4 & IL10 produced by Th2
cells inhibit Th1 cells
• Once either subset becomes dominant it
suppresses other subset making it difficult
to change the immune response pattern
T cell determine the type of immunity

50. T cell subsets induced in infection
Perio 2000
Vol-35

51. CYTOKINE PROFILE IN PERIODONTAL DISEASE
Essence of Pathogenesis
Disease Health
High
Low High
Low
IL- 1β, TNF-α, IFN-γ
PGE2 MMPs
IL- 10, TGF-β
IL- 1ra, TIMPs

52. RANKL – links immune cells to
pathogenic bone loss
• RANKL is a tumor necrosis factor related cytokine
• RANKL is expressed by T & B cells, Osteoblasts,
stromal cells, chondrocytes and mesenchymal cells
• Factors from T cells such as IL7, IL18, TNFα and
more importantly RANKL (Receptor activator of
nuclear factor- kB ligand) have been shown to
affect bone remodeling
• RANKL, its cell surface receptor RANK and a
soluble decoy receptor osteoprotegerin are the key
molecules that regulate osteoclast differentiation
and function

53. Tcells and Osteoclastic bone resorption
Activated Tcell

54. Potential Intervention strategies to prevent periodontal bone resorption

55. Gingivitis
Strong innate
immune response
Th1
Cell mediated immunity
& Protective antibody
production
Stable Lesion
Periodontitis
Poor innate immune response
Periodontopathic bacteria
Polyclonal B cell activation
Th2
Non-protective
antibody production
Progressive Lesion
(Hypothesis–1) Th2 Response leads to progressive Periodontitis

56. Hypothesis – 2
TH1 response leads
to attachment loss

57. Bacterial products induce apoptosis of
T cells
• Periodontal bacteria can induce
apoptosis of T cells
• Bacterial products act as negative
regulators of T cell activation
Important pathogenic mechanisms
promoting infection, inflammation
and disease.

58. ROLE OF B CELLS

59. Th cells and B cell antigen presentation function
Rodriguez & Pinto

60. B Lymphocytes
• B Lymphocytes and Plasma Cells dominate in
Periodontitis lesions
• Subsets of B cells such as B-1a and B-2 are present
• B-2 cells represent the traditional B cells
• B-1a cells produce autoantibodies of IgM type
followed by isotyping switching to IgG type
• B cells and Plasma cells contribute to tissue
destruction in Periodontitis through MMP 8
and MMP 13

61. Distribution of cell proportions in Periodontitis lesions
Plasma cells
B cells
T helper
T cytotoxic
PMN
Mae
Others
JCP 2005 – vol-32

62. • B cells and plasma cells produce and
secrete Immunoglobulins (IgG2) that
prevent bacterial adherence, inactivate
bacterial toxins and act as opsonins for
phagocytosis by PMNs.
• However production of non protective
antibodies (poor avidity and poor
antigenicity) could result in progressive
lesion
B cells and antibodies in periodontal disease

63. IgG2 serotype production by DC and NK cells

64. Induction of IgG2 platelet activating factor and PGE2

65. Polyclonal B cell activation
• Polyclonal B cell activation is induced by
periodontopathic organism
• Usually leads to production of low avidity
and non specific antibodies
• Continual activation of B cells results in
production of high levels of IL1 resulting in
tissue destruction.

66. Antibodies against Periodontal Pathogens are
protective (A recent study)
• Serum levels of IgG antibodies against A.a
or P.g were higher in periodontitis-stable
patients than those with active
periodontitis
• Elevated levels of IgG antibodies against
A.a and P.g have a detectable protective
effect against periodontal infections.
(Rams, Listgarten and Slots – JPR 2006)

67. Autoimmune components in Periodontitis
• Anticollagen antibodies
• Auto-antibodies to desmosomal proteins
• Self heat shock protein 60(hsp60) might be
a target for autoimmune response due to
molecular mimicry between human hsp60
and its bacterial homologue GroEL.

68. Hsp60 induced immune response in periodontitis

69. Regulatory Components of Adaptive host response
in Periodontitis
JCP 2005 – vol-32

70. IMMUNIZATION AGAINST PERIODONTITIS
Is it possible?
IMMUNIZATION

71. • Common bacterial antigens of periodontal
pathogens should be identified and their
potential as vaccine candidates should be
evaluated.
• This could lead to the development of a
multispecies vaccine for periodontitis.
Antigenic protein Identification for Vaccine development

72. • Target antigens(multiple?) need to be
identified and purified
• Preclinical testing in animal models (mice,
rats etc). Primary safety testing is often
specifically studied in guinea-pigs
• Vaccine should be approved as an
investigational new drug by FDA before
human trials
Vaccine for Periodontitis

73. Periodontal Vaccine- human
trials
• Phase I (less than 20 healthy subjects),
Phase II (50 to 200 subjects) and
Phase III (up to several thousand subjects)
should be performed to test the power of
vaccine
• Takes 50 years for Biologics Application
approval(BLA)
• Periodontal vaccine that go beyond testing
in animal models have not been performed
yet

74. P.gingivalis antigens as vaccine candidates
• Whole cell formalin-killed P.gingivalis
• Gingipains – Arg-X and Lys-X cysteine
proteinases and adhesins
• Outer membrane proteins (prevents
Coaggregation)

75. • Periodontitis is caused by complex
polymicrobial infection
• Biofilms protected from host immune
responses
• Bacteria disconnect from biofilms by
swarming dispersal, clumping dispersal
and surface disposal
• P.gingivalis invades epithelial cells
protecting it from humoral immune factors
Difficulties encountered in developing a
periodontal vaccine

76. Treatment induced humoral immunity
• Non-surgical treatment (SRP) causes
bacteremia leading to elevated levels
of antibodies
• Termed as ‘uncontrolled’ immunization
against periodontal pathogens
• Studies have given different
results in terms of antibody avidity

77. Other strategies
• Probiotics? – live microorganisms
administered in adequate amounts
with beneficial health effects on the
host
• Vaccine against P.gingivalis specific
Heat Shock protein (HSP60, GroEL)
to prevent autoimmune responses

78. Host Modulation
• Modulation of Arachidonic Acid
metabolites (NSAIDS)
• Modulation of MMPs – SDD (Doxycline - 20
mg twice daily)
• Modulation of bone remodeling
(Bisphosphanates)
• Inhibit Inflammatory cytokines (IL1 &
TNFα) through recombinant human IL11
(rhIL-11)
• Inhibition of Nitric Oxides by MEG
(Mercaptoalkylguanidines)

79. To conclude
• Genetic polymorphism combined with
environmental factors and specific
pathogens seem to play an important role
in the progression of periodontal diseases
• Immune responses are protective(in some)
and destructive (in others)
• Periodontal vaccine is a distant dream (we
have still not developed a vaccine for
caries)
• Host modulation is the most prevalent
strategy at present (Is it that effective?)
(How long?)

80. Thank you