Periodontal Immunology - Immunopathogenesis Flashcards
What are the hallmark signs of periodontitis
Attachment loss - manifests as increased pocket depth
Alveolar bone destruction
What species in the biofilm can cause tissue destruction and how
Gingipains can clean and degrade host proteins to make them available as an energy source which can contribute to destruction of the connective tissues and attachment loss
How is gingivitis first initiated
The host detects an accumulation of plaque bacteria, detected by TLR expressed within the gingival epithelium
This will lead to upregulation and the release of pro-inflammatory mediators which will trigger the clinical signs of inflammation allowing immune cells to migrate into the tissues to try and control the infection
Which cells migrate to the gingival tissue during gingivitis and how do they do this
Mainly neutrophils and monocytes
They follow the chemokine and cytokine gradient that is produced upon activation of TLRs and they migrate through the gingival tissue towards the gingival margins
What is the role of neutrophils and monocytes in the gingival tissue
They can either phagocytose any microbes invading the tissue or they can release their degredative enzymes into the GCF and those enzymes will bathe the biofilm attached to the subgingival tissues
How does gingivitis affect the gingival crevicular fluid
There is increased flow of the GCF
What is the role of lymphocytes during gingivitis
T cells help to coordinate the responses and B cells can differentiate into plasma cells and then start releasing antibodies into the GCF and saliva
What are the possible outcomes of gingivitis
Biofilm is controlled as the threat is removed so there is resolution of inflammation and return to health
or
Periodontal pathogens in the biofilm drive dysbiosis preventing the return to homeostasis while evading the immune response so over time, the immune response will become chronic, damaging the host tissues
Describe the role of neutrophils in periodontal health
Neutrophils continually track through the gingival tissue and towards the gingival margin where they degranulation and release their contents into the GCF
Occurs constantly and is crucial for maintaining health and to suppress the expression of virulence
Why is periodontitis so aggressive in patients with lost neutrophil function
Neutrophils aren’t available and aren’t functioning correctly so they’re not available to control bacterial growth giving particular species a competitive advantage, invading the gingiva tissues leading to widespread inflammation
How can the presence of neutrophils lead to destruction of tissues
Within the degradation enzymes designed to control the biofilm, there is a major source of MMPs which are host enzymes important for clearing damaged tissues after infection
The vast number of MMPs during periodontitis contribute to tissue destruction
Describe the protective role adaptive immunity plays in periodontitis
Prevents the biofilm trafficking through the tissue and gaining access to the circulation, preventing systemic infection
Why is the adaptive immune response during periodontitis destructive
The sustained activation of inflammation contributes to alveolar bone absorption
Describe monocytes differentiation in health
Monocytes, given the right signals, can either differentiate into macrophages or osteoclasts
In health the balance between bone formation and absorption is balanced, old bone is placed with new bone
How is monocytes differentiation regulated
By a triad of cytokines, RANKL, its receptor RANK and the decoy receptor OPG
