Host microbe interaction in periodontal disease

MICROBIAL INTERACTION

WITH THE HOST IN

PERIODONTAL DISEASE

Periodontal diseases

GingivitisPeriodontitisInflammatory response to microorganisms in

dental plaqueTissue destruction, Bone loss, tooth loss

01/09/15 Dr Saif Khan 2

Periodontal disease

Host-microbe diseaseInteraction of Host with microrganism

determines the course and extent of the resulting disease

Microrganism cause disease throughDirect Tissue destructionIndirect through stimulating and modulating host

response


Host Response

Mediated by Microbial interaction and inherent characteristic of host including genetic factors which vary among individuals

In general host response is protective it prevents local infection from progressing to systemic, life threatening infections


Microbe Host interaction

Local alteration and destruction of host tissue

as a result of microbe-host interaction

manifest as Periodontal disease


Microbial Aspect of Microbial Host Interaction

Gram negative anaerobes are pathogenic

organisms associated with disease

The properties of microorganism that enable it

to cause disease is called Virulence Factor

Bacteria must colonize the host tissue and

then cause destruction of the host tissue


Bacterial Colonization and Survival in Periodontal region

• Bacterial Adherence– GCF flows outwards from the base of pocket– Bacterial species that colonize this region must

attach to available surfaces to avoid displacement– Surfaces available for attachment are tooth or

root, tissue, and preexisting plaque mass– Eg: A viscosus and Pgingivalis through fimbrae on bacterial surface to

proline rich proteins found on saliva-coated tooth surface


P gingivalis binds to epithelial cells and fibroblasts

The ability of Porphyromonas gingivalis to attach

to other bacteria, epithelial cells, and connective

tissue components fibrinogen and fibronectin add

to virulence of this periopathogen


Host tissue InvasionBoth gram-positive and gram- negative

bacteria, including cocci, rods, filaments and

spirochetes have been seen in gingival

connective tissue and alveolar bone

Presence of bacteria in periodontal tissue in

gingivitis, advanced chronic periodontitis

and Aggressive Periodontitis

Presence of bacteria in host tissue in NUG


Bacteria can enter host tissue through

Ulceration in epithelium of gingival sulcus or periodontal

pocket

Observed in intercellular spaces of gingival tissues

Direct penetration of bacteria into hosts epithelial or

connective tissue cell

Eg: A actinomycetemcomitans, P gingivalis, F nucleatum,

Treponema denticola to invade tissue cell directly


Bacterial species that have been identified as

capable of tissue invasion are strongly

associated with disease

Ability to invade has been proposed as a key

mechnism that distinguishes pathogenic from

non- pathogenic gram negative species

Localization of bacteria to the tissue provides

an ideal position from which organism can deliver

toxic molecules & enzymes to host tissue


• “Burst of disease activity” may be related to

phases of bacterial invasion of the tissue

• Mechanical debridement alone is insufficient, and

systemic antibiotic in combination with surgical

therapy is required to eliminate A

actinomycetemcomitans from lesion in aggressive

periodontitis


Bacterial Evasion of Host Defense System

To survive in periodontal environment

bacteria neutralize or evade host mechanism

involved in bacterial clearance and killing

Bacterial adherence and invasion are

strategies through which bacteria accomplish

this task

Ability to adhere allows bacteria to avoid

displacement by host secretions


Periodontal bacteria neutralize or evade

host defense through numerous other

mechanism as shown in the following

table


Host Defense Mechanism

Bacterial Species Bacterial Property Biologic effect

Specific Antibody Pg, Pi, P melanogenica, Capnocytophaga sp

IgA and IgG degrading protease

Degradation of Specific antibody

Polymorphonuclear leukocytes (PMNs)

Aa, F nucleatum, P gingivalis, T denticola

LeukotoxinHeat sensitive surface proteinCapsuleInhibition ofSuperoxide Production

Inhibition of PMN functionProgrammed cell death of PMN

Lymphocytes Aa, F nucleatum, T forsythia, P intermedia

LeukotoxinCytolethal distending toxin

Killing of mature B and T CellsApoptosis of lymphocytes and mononuclear cells

Release of IL-8 P gingivalis Inhibition of IL-8 production by epithelial cells

Impairment of PMN response to bacteria


Bacterial enzymes capable of Degrading Host Tissue

1. Collagenases

2. Trypsin like enzymes

3. Aryl sulfatase

4. Neuraminidase

5. Fibronectin –degrading Enzyme

6. Phospholipase -A


Immunological aspect of Microbial-Host interaction

Involves following factors in response to bacterial infection– Innate factors such as complement, resident

leukocyte and especially mast cell play significant role in signalling endothelium thus initiating inflammation

– Acute inflammatory cells (neutrphils) protect local tissue by controlling the periodontal microbiota within the gingival crevice and junctional epithelium

– 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



Periodontal disease is a well-regulated

response to protracted bacterial infection

directed by inflammatory cells of the host

immune system

Neutrophils primarily function as antimicrobial

cells, and chronic inflammatory cells orchestra

adaptive responses

Neutrophils function to contain microbial

challenge through phagocytosis and killing and

may contribute to local tissue changes by

release of tissue-degrading enzymes


PMN’s form a protective layer in regions where epithelium of the gingival sulcus has been

disrupted in Gingivitis


Clinical example of established Gingivitis with emphasis on the acute inflammatory reaction


• The chronic inflammatory cells, the

lymphocytes and monocytes orchestrate

connective tissue changes associated with

both periodontal infections and periodontal

repair and healing


Innate factors and initiation of inflammation

Onset of inflammation there is edema and

erythema leading to vascular changes

Complement activation in response to bacterial

infection result in generation of C3a and C5a


Degranulation of Mast cell

Mast cell constitutely transcribe TNF-ά,

TNF-β, IL-4, IL-6

When stimulated induce produce

Proinflammatory cytokines such as IL-1, IL-6,

INF-γ


Stimulation of endothelial cells by C5a,

IL-1β, TNF-ά and bacterial lipopolysacchrides results

in expression of selectins on the luminal surface of

endothelial cells and release of chemokine from the

endothelial cells These process are central in transendothelial

migration


Transendothelial Migration01/09/15 Dr Saif Khan 29

Complement levels

• In healthy patients complement levels in GCF

are about 3% of that serum as periodontal

inflammation increases the complement level

of C3 and C4 increases to 25% and 85% of

that in serum


Controlling Bacterial Challenge primary role of Neutrophils

• Neutrophils are the first leukocyte to arrive at site of inflammation

• Neutrophils control bacterial inflammation through– Transendothelial migration– Transepithelial migration– Opsonization– Phagocytosis– Intraphagolysosomal killing


Transepithelial migration

• 1-2% neutrophils migrate across the junctional epithelium daily through chemotactic gradient of IL-8 and ICAM-1 expressed by junctional epithelium

• Porphoromonas gingivalis impedes transepithelial migration of neutrophils by preventing epithelial cells to secrete IL-8 in response to bacterial challange


Opsonization

Coating of bacteria by host proteins to facilitate

phagocytosis

Bacteria are coated with complement components

(iC3b, C3b)

Recognized by CR3 neutrophil receptor

Antigen presenting cells such as Peripheral

Dendritic cells (langerhans,macrophages,B cells)

are abundant in gingival cells01/09/15 Dr Saif Khan 33

Phagocytosis

Bacterial cell ingestion by neutrophil results in

formation of Phagosome

Bacteria is killed by Oxidative or Non-

oxidative mechanism


Scanning Electron Micrograph of PMNs passing through epithelium.

Note bacteria attached to PMNs in process of being phagocytosed


High power view of PMN and bacteria attached

undergoing phagocytosis.


Light Microscopic view of PMNs from gingival fluid showing evidence of phagocytosis

White spheres inside PMNs have been engulfed


Oxidative Killing by – NADPH Oxidase, – Myeloperoxidase, – Nitric oxide synthase


Non-oxidative Killing by – Defensin, – Lysozyme, – Neutral serine proteases– Bacterial permeability increasing protein


DEFECT IN NEUTROPHIL FUNCTION AT ANY STAGE LEADS TO AGGRESSIVE PERIODONTITIS


Systemic neutrophil abnormalities associated with Aggressive Periodontitis

CONDITION NEUTROPHIL ABNORMALTY

PERIODONTAL MANIFESTATION

NEUTROPENIA,AGRANULOCYTOSIS

DECREASED NO. OF NEUTROPHILS

SEVERE AGGRESSIVE PERIODONTITIS

CHEDIAK HIGASHI SYNDROME

DECREASED NEUTROPHIL CHEMOTAXIS AND SECRETION NEUTROPHILS FUSE TO FORM CHARACTERISTIC GIANT GRANULES CALLED MEGABODIES

SYNDROME CAUSED BY MUTATION IN THE VESICLE TRAFFICKING GENE ,LYST

PAPPILON-LEFEVRE SYNDROME

MULTIPLE FUNCTIONAL NEUTROPHIL DEFECTS, INCLUDING MYELOPEROXIDE DEFICIENCY, DEFECTIVE CHEMOTAXIS, AND PHAGOCYTOSIS

SEVERE AGGRESSIVE PERIODONTAL DESTRUCTION AT EARLY AGE, INVOLVES PRIMARY AND PERMANENT DENTITIONMUTATION IN CATHEPSIN C GENE



LEUKOCTE ADHESION DEFICIENCY TYPE-1 (LAD-1)

DEFECTS IN LEUKOCYTE FUNCTION CAUSED LACK OF INTEGRIN β-2 SUBUNIT (CD-18).NEUTROPHIL DEFECTS INCLUDE IMPAIRED MIGRATION AND PHAGOCYTOSIS. HISTOLOGICALLY ALMOST NO EXTRAVASCULAR NEUTROPHILS ARE EVIDENT IN PERIODONTAL LESION

AGGRESSIVE PERIODONTITIS AT AN EARLY AGE AFFECTING PRIMARY AND PERMANENT DENTITION, IN INDIVDUAL WHO ARE HOMOZYGOUS FOR THE DEFECTIVE GENE

LEUKOCTE ADHESION DEFICIENCY TYPE-2 (LAD-2)

NEUTROPHILS FAIL TO EXPRESS LIGAND (CD15) FOR P- AND – E SELECTIN, RESULTING IN IMPAIRED TRANSENDOTHELIAL MIGRATION IN RESPONSE TO INFLAMMATION

AGGRESSIVE PERIODONTITIS AT YOUNG AGE


The clinical photo and the X-Ray of this 28 year-old

man show the advanced alveolar bone loss in the

absence of significant gingival inflammation, typical

of the localized aggressive periodontitis


This patient has advanced generalized aggressive

periodontitis with deep pockets throughout the mouth.


PAPILLON-LEFEVRE SYNDROME


These photos show the Palmo-plantar Hyperkeratosis

present in patients with the Papillon Lèfevre

Syndrome. These lesions remain for life but improve

when treated with retinoic acid


Connective tissue alteration: Tissue destruction in Periodontitis

Connective tissue alteration: Tissue destruction in Periodontitis

The fundamental event in the transition from

gingivitis to periodontitis is the loss of the

soft tissue attachment to the tooth and

subsequent loss of bone

Mediators produced as part of host

response contribute to tissue destruction

include Proteinase,Cytokines, Prostaglandins


Proteinases• Matrix Metalloproteinases(MMP) are primary

proteinases involved in periodontal tissue

destruction by degrading extracellular matrix

molecules

• MMPs are family of Proteolytic enzymes found

in neutrophils, macrophages,fibroblasts, epithelial

cells, osteoblasts and osteoclasts

• MMPs degrade extracellular matrix molecules,

such as collagen, gelatin, and elastin


MMP-1 is expressed by resident periodontal

tissue such as fibroblasts, monocytes,

macrophages and epithelial cells

MMP-8 is released by infiltrating neutrophils

MMP are activated by chymotrypsin-like

protease produced by Treponema denticola

as well as host enzymes such as neutrophil

cathepsin G


• MMPs are inactivated by ά-macroglobulin

found in serum and GCF and by Tissue

inhibitor of MMP’s (TIMP) produced by

many cell types and common in host tissue

and fluids

• Tetracycline also inactivates MMPs and have

significant therapeutic role


Other Proteinases associated with

Periodontitis include neutrophil serine

proteinases, Elastase and Cathepsin G

Cathepsin G is elevated in gingival tissue and

GCF

Elastase degrades a wide range of molecules

including Elastin, Collagen, and Fibronectin

Elevated Elastase level are associated with

active Periodontal attachment loss


Cytokines• Three proinflammatory cytokines IL-1, IL-6

and TNF-ά have a central role in Periodontal

tissue destruction

• IL-1 is produced primarily by activated

Macrophages or Lymphocytes

• Bacterial LPS is potent activator of

Macrophage IL-1 production

• TNF-ά is also produced by activated

macrophages in response to Bacterial LPS


• Also TNF-ά and IL-1 can activate macrophage

IL-1 production

• TNF-β is primarily produced by Th1 subset of

CD4+ T cells that have been activated by

antigen or mitogen


Proinflammatory effect of IL-1 and TNF-α are

Stimulation of endothelial cells to express

selectins that facilitates recruitment of

leukocytes

Activation of Macrophage IL-1 Production

Induction of Prostaglandin E2 (PGE2 )


IL-1 is a potent

stimulant of osteoclast

proliferation,

differentiation, and

activation

TNF-ά have same

effects on osteoclasts

but less potent


ProstaglandinsArachidonic metabolite generated by

cyclooxygenase (COX-1, COX-2)

Arachidonic acid is a 20-carbon

polyunsaturated fatty acid found in

plasma membrane of most cells

COX-2 is upregulated by IL-1β, TNF-β and

bacterial LPS leading to formation of

PGE2 associated with inflammation


• PGE2 is increased in periodontal sites demonstrating inflammation and attachment loss

• PGE2 also induces MMPs and osteoclastic Bone Resorption

• PGE2 is elevated in gingivitis and Periodontitis in active disease

• PGE2 is partly responsible for bone loss associated with periodontitis


Macrophages produce prostaglandin E (PGE) and (IL-1) and

lymphocytes produce Interleukin-1 (IL-1) which activate

osteoclasts by interacting with osteoblasts01/09/15 Dr Saif Khan 63

PGE2 is released from monocytes of patients

with severe or aggressive periodontitis

High risk patient display “Monocyte Hyper

secretory trait” leading to exaggerated response

both locally and systemically to bacterial LPS

Use of NSAID as an inhibitor of Prostglandins

synthesis has therapeutic role in preventing

bone loss in Periodontitis01/09/15 Dr Saif Khan 64

Connective tissue alteration: Healing Process in Periodontitis

The chronic immune system plays an important role in

healing process, which consists regeneration and

repair

Regeneration involves the replacement of tissue with

new, identical tissues that function same as the

orignal tissue

Repair involves replacement of one tissue with

another tissue, such as fibrous connective tissue


Periodontal Repair occurs in overlapping phases of

1. Inflammation shutdown

2. Angiogenesis

3. Fibrogenesis


Inflammation shutdown

• In post inflammatory healing process, shut down

of inflammatory processes and initiation of post

healing is orchestrated by leukocytes

• Anti inflammatory signals generated by

leukocyte are IL-1 receptor antagonist (IL-

1ra) and Transforming growth factor-β

(TGF-β)

• IL-4, IL-10, IL-11 also depress inflammatory

response


Source of Anti inflammatory signal


Angiogenesis and Fibrogenesis

• IL-1β and TNF-β participate both in

inflammation and healing

• IL-1β and IL-ά are indirectly involved in

inducing fibroblast proliferation and collagen

synthesis by stimulating the production of PGE2

or release of secondary cytokines such as

Platelet derived growth factor (PDGF)


PDGF is a protein complex formed by different

combinations of A,B, C and D chains (PDGF-

AA,AB,BB,CC,DD)

PDGF is structurally and functionally related

to vascular endothelial growth factor(VEGF),

an important factor in endothelial proliferation

PDGF activates fibroblasts and osteoblasts

resulting induction of protein synthesis


Also TGF-β promotes the elaboration of fibroblast

extracellular matrix adhesion

TGF-β is potent inhibitor of osteoclast formation

Osteoclast differentiation and activation are

inhibited by interferon-γ (INF- γ ) which is

secreted by natural killer cells, Th1 cells and

macrophages


The main effect of INF-γ appears to be inhibition

IL-1 and TNF-ά induced osteoclast activation.

IL-1ra also effective in blocking IL-1 and TNF-ά

induced osteoclast activation


Gingivitis

Intitial lesion –Neutrophils

Early lesion – lymphocytes

Established lesion-Plasma cells


Chronic Periodontitis

• Characterised by Alternative pathway activation of complement C3 and C3B in gingival fluid

• Increased MMP-8 and decreased TIMP-1• Collagenase activity is 6 times more than

gingivitis


Aggressive periodontitis

Caused by Actinobacillus

actinomycetemcomitans (Aa)

Humoral response to Aa is elevated

Most common serotype B, then A

Incidence of Aa is greater in younger than older

patients

Younger patient have more destructive disease



Aa can be identified by electron microscopy,

immunoflouresence and culture from LAP lesion

within gingival connective tissue

Aa is quite virulent releases leukotoxin,

Collagenases, Phosphatases and Bone Resorbing

factors

Positive correlation between elimination of

bacteria and resolution of the lesion

Global Membrane Receptor Defect

Defect associated with 40% defect in 110-kd

membrane glycoprotein on neutrophil

surface, Gp110

Gp110 is G-protein coupled receptor

75% of patients with LAP have dysfunctional

neutrophils, involving decreased expression of

G-protein coupled receptor


Localised Aggressive Periodontitis (LAP)- MMP-1

is increased

Chronic Periodontitis- MMP-8 is increased

In LAP antibody to Aa is increased and

predominant antibody is IgG2

Variant of Fc receptor on neutrophils(R131 allele

of FcγRII-α) does not bind efficiently to IgG2

leading to LAP01/09/15 Dr Saif Khan 78

Patients with elevated antibody response

(IgG2) have less loss of attachment

Antibody response in LAP greater than

GAP(Generalised aggressive periodontitis)


Socransky criteria

• Proposed criteria by which periodontal microorganism may be judged to be potential pathogens

1. Must be associated with disease, as evident by increase in the number of organisms at diseased sites

2. Must be eliminated or decreased in sites that demonstrate clinical resolution of disease with treatment

3. Must demonstrate a host response, in the form of an alteration in the host cellular or humoral immune response

4. Must be capable of causing disease in experimental animal model.

5. Must demonstrate virulence factors responsible for enabling the microorganism to cause destruction of periodontal tissue

Dr Saif Khan 8001/09/15

Host microbe interaction in periodontal disease

Health & Medicine

Transcript of Host microbe interaction in periodontal disease