Host defences against microbial plaque Flashcards
The balance between what 4 things prevents the formation of periodontal diseases?
- Presence of pathogen
- Absence of beneficial species
- Host response
- Conducive environment around the oral cavity
What are the functions of the host defences?
- To keep bacteria out out of the periodontium
2. Destroy any foreign microbes which succeeded in entering the system
What does plaque accumulation begin with?
Begins with pioneer species attach to the pellicle of a clean tooth surface
What are the stages of plaque formation
- Pioneer species attach to the pellicle surface of a clean tooth
- These multiply to form micro colonies
- Resulting in confluent growth of biofilm
- This increases species diversity
Name the 5 things that help defend us from plaque
- Saliva
- Gingival epithelium
- Inflammation
- Immune system
- Mediators
What are the functions of saliva?
It has a washing effect
It is a vehicle for swallowing bacteria
It also has an antimicrobial effect
Approx how many bacteria do we swallow?
10^8 bacteria in every mL of saliva we swallow
Name some antimicrobial substances in saliva
- Peroxidase/ Hypothiocyanate
- Lysozyme/ Lactoferrin
- Antibodies (IgA)
What occurs if there is a lack of saliva?
Xerostomia
What are some factors that may cause Xerostomia?
- Patients who are out breathers
- Drugs/ alcohol
- Radiotherapy
- Patients who have had their salivary glands removed surgically
What are people with xerostomia more susceptible?
Gingivitis
Cervical caries
What is the gingival epithelium comprised of?
The oral gingival epithelium
The oral sulcular epithelium
The junctional epithelium
Describe how the gingival epithelium provides a mechanical barrier
- Seals against bacterial
- Has keratinocytes
- Has langerhans cells
What is the junctional epithelium permeable to?
- Bacterial products that need to go in
- Crevicular fluid and neutrophils that need to go out
- It becomes more permeable in disease
Describe the junctional epithelium in periodontal health
Has an intact junctional epithelium
Describe east happens to the junctional epithelium as periodontal health deteriorates
Junctional epithelium migrates apically
This eventually forms a pocket between the junctional epithelium and root surface
What is associated with the formation of a pocket between the junctional epithelium and root surface
Loss of connective periodontal attachment and loss of alveolar bone
What is inflammation?
It is a response of living tissue to injury and provides a rapid first line of defence
What are the 2 types of inflammation?
- Acute
2. Chronic
What is acute inflammation?
It is non specific and has both fluid and cellular components
Describe chronic inflammation
It is slower to establish than acute inflammation §
What are the functions of the inflammatory response?
- To dilute by increasing crevicular fluid
- To wall off the inflammatory cells
- Destroy the inflammatory cells and the damaging pathogens
Describe the sources of the fluid response of inflammation
- Vasodilation
- Increased permeability of endothelial cells
- Fluid and plasma proteins are release into the tissues and through GCF
What is the inflammatory exudate
plasma proteins like antibodies and compliment that are released into the tissues and through GCF
How many proteins are involved in the compliment system?
9
Why does the compliment system play an important role in the fluid response of inflammation?
- It is responsible fro mass cells producing histamine
- Chemotaxis for neutrophils
- Responsible for lysis and inhibition of a few species off bacteria
- Can lead to opsonisation for phagocytosis
What do we expect to see as the fluid response of inflammation is occurring ?
- Increased crevicular fluid flow
- Gingival erythema
- Oedema and selling of the gingiva
Name the key components of the cellular response of inflammation
- Neutrophils
2. Macrophages
Why are neutrophils important?
- They form the first line of defence
- They can prevent bacteria from entering the gingival crevice
- They form a layer on the surface of plaque
Describe the function of neutrophils in response to UNATTACHED bacteria
- They recognise and bind to bacteria
- They perform phagocytosis
- They produce antibacterial agents
- They digest micro organisms
- They expel remnants
- Contributes to bystander damage
What can bystander damage cause?
A little bit of damage to the surrounding tissues
Describe the function of neutrophils in response to bacteria in the plaque matrix
- Neutrophils attach to the plaque matrix
- They secrete antibacterial enzymes
- They kill bacteria
- They dissolve the plaque matrix
- Contributes to bystander damage
Name some antibacterial enzymes neutrophils secrete
- Hydrogen peroxide
2. Hypochlorous acid
What is a recognised side effect to the host defence system?
Bystander damage
Where do macrophages develop?
They develop from monocytes in the blood
What do macrophages play an important role in?
Both immunity and inflammation
Where do macrophages emigrate too?
They emigrate to inflamed gingival tissue
Few of them enter the gingival crevice
What role do macrophages have in inflammation?
- Phagocytosis
- Secrete tissue degrading enzymes
- They secrete compliment components
- They secrete mediators
Name some functions macrophages secrete in relation to inflammation
IL-1
TNF
Prostaglandins
Name some functions macrophages secrete in relation to immunity
- They process and present antigens
2. They secrete IL-1
What type of inflammation is periodontal disease implicated by?
Both acute and chronic
What is gingivitis usually characterised by biochemically?
An increase in leukotriene B4 in the gingival crevicular fluid
What is leukotriene B4 a product of?
Degranulating neutrophils in the sulcus
What is periodontitis usually characterised by biochemically?
An increase in : 1. prostateglandin E2 2. IL-1 beta 3. tumour necrosis factor alpha All three of these represent an activation of macrophages and lympohcytes within the tissue
Describe the immune response
It is stimulus specific and has memory
It is initiated by antigens
Antigens are recognised by lymphocytes
What are the 2 aspects of the immune responses?
- Humoral
2. Cell mediated
Which cells are involved in the humeral response?
B lymphocytes undergo differentiation to give:
- Plasma cells
- Immunoglobulins
Which cells are involved in the cell mediated response?
T lymphocytes there are 2 types:
1. T helper cells 2. T cytotoxic cells
What activates the humoral response?
- Bacteria
- Toxins
- Other plaque antigens
What initiates the humoral response?
An antigen presented by the macrophages
Describe the humoral response
- Antigen presented by the macrophages
- B lymphocytes recognise foreign antigens and undergo clonal expansion
- B lymphocytes differentiate into plasma cells under T lymphocytes are initiated
- Antibodies are produced
What type of antibodies make up the majority of the humoral response?
IgG makes up 75% of the antibodies in the humoral response
Describe the antibody production in the saliva
- Bacteria is swallowed in the saliva
- Antigens recognised in the gut
- IgA secreted into the saliva
Describe the antibody production in the gingiva
- Antigens penetrate gingiva
- Antigens carried to lymph node outside the ginigva
- Antibodies IgG and IgM are secretes into the plasma pass to GCF
What are the 2 mechanism by which antibodies fight off antibodies?
- Binding to the bacteria
2. Binding to the soluble factors secreted by the pathogens
Describe how the antibodies fight off pathogen by binding to the bacteria
- Inhibits attachment
- Opsonisation
- Activating complement
- Inhibiting metabolism
Describe how the antibodies fight off pathogen by binding to the soluble factors
Neutralising toxins
Inhibiting enzymes
What does the cell mediated immune response regulate?
Regulates plasma cell differentiation
What are some defects in the host response?
- Reduction in neutrophil number
2. Defective neutrophil function
What can a reduction in neutrophil number cause?
- Cyclic neutropenia
- Agranulocytosis
these can have a clinical effect on gingiva and periodontal tissues
Name some genetic conditions that can result in defective neutrophil function
Downs syndrome Diabetes Papillon- Levfevre syndrom Chediak-Higashi syndrom Leucocyte adhesion deficiency
What causes down syndrome?
Trisomy chromosome 21
What can be seen in SOME patients who have down syndrome
They can have advancing forms of periodontitis in both the primary and secondary dentitions
How can having Down syndrome increase you chances of having periodontitis?
There can be defects in the:
- neutrophil chemotaxis
- neutrophil Killing
- phagocytosis
What can poorly controlled diabetes be associated with?
An increase in susceptibility to periodontitis
How can having uncontrolled diabetes increase you chances of having periodontitis?
- Decreased neutrophil function
- Decreased collagen synthesis
- Increased collagenolytic activity
- Increased periodontopathogens in sub gingival biofilm
How many people in the uk are affected by diabetes
1.8 million
How many people in the uk are affected by papillion-lefevre
1 in 4 million
What is papillion-lefevre syndrome associated with?
Palmer plantar keratosis which means the palms of the hands and feet are scaley
What is a key feature of papillion-lefevre syndrome?
Rapid and aggressive periodontal destruction
How can having uncontrolled diabetes increase you chances of having papillion-lefevre syndrome?
Defective neutrophil function
Genetics
What can happen to your gums if you smoke?
- Smoking disguises onset of many diseases
- Associated with the rapid progression of periodontal diseases
- Connective tissue loss
- Periodontal pocketing
- Alveolar bone loss
How does smoking make it harder to detect periodontal disease?
Gums look normal so it is harder to see the symptoms of periodontal disease
How many people suffering fro refractory periodontitis were smoker?
90%
How can smoking make it harder to treat a periodontitis sufferer?
Makes them resistant to treatment
Means they have a poor response to non surgical and surgical therapy
How can smoking increase you chances of having periodontitis?
- It inhibits the neutrophil function
- Impaired neutrophil oxidative bursts
- Reduced antibody number
- Depressed number of helper lymphocytes
How can having HIV increase you chances of having periodontitis?
- Reduction in number of t helper cells
What can some people suffering from advanced HIV / AIDS have?
Necrotising ulcerative periodontitis
Name some mediators?
- Histamine
- Bradykinin
- Cytokines
- Prostaglandins
- Metalloproteinases
What are histamine and bradykinin associated with?
Vasodilation
Increased vascular permeability
Describe Cytokines
They are soluble proteins
They are secreted by cells
They transmit signals
What do Cytokines co ordinate?
The inflammatory and immune response
Give examples of Cytokines
IL-1
TNF
What is the role of Cytokines?
To amplify inflammatory response
How do Cytokines amplify the inflammatory response
- They activate macrophages
- Activate lymphocytes
- Causes cells to release prostaglandins and more Cytokines
- Causes endothelial cels and fibroblast proliferation
- Causes fibroblasts to release collagenase
- Indices bone resorption
What do Prostaglandins do?
- They cause capillary dilation
- Increase endothelial permeability
- PGE2 causes bone resorption
What are Prostaglandins produced by
Produced from arachidonic acid in cell membranes of inflammatory cells
Give examples of
- Collagenase
2. Gelatinase
What are metalloproteinases involved in?
Connective tissue destruction
What are metalloproteinases produced by?
Fibroblasts
Monocytes
Neutrophils
What are metalloproteinases induced by?
IL-1
What are the major regulators of immunoinflammatroy responses that categorise periodontitis?
Cytokines
Chemokine
Prostaglandins
What is bystander damage a prominent feature of?
Of chronic inflammatory disease
How can we identify risk patients
- Medical history
- Social history
- . Family history
- Smokers
- Host response based diagnostics kits
What can we do once we have identified a high risk patient
Tailor treatment to the patients’ needs
How can we tailer treatment to high risk patients
- Liaison with there GP
- Give the oral hygiene aids
- Give them smoking advice
- Be selective about our use of adjunctive antibiotics
- Prognosis of periodontal surgery
- Put into place regular supportive programmes are available for the patient
What do Cytokines, Chemokine ,Prostaglandins have a major role in
They are major regulators of immunoinflammatroy responses that categorise periodontitis
