Mucosal Immunity Flashcards
(51 cards)
To where do effector B and T cells home after activation with specific antigen?
Site of infection
True or False: The Mucosal immune system can work independently of the systemic immune system.
True
What is sterile protection?
Complete blockade of pathogen entry into the host
True or False: Mucosal tissues are more vulnerable to attack than skin.
True
What is Waldeyer’s ring?
The ring of tonsils and adenoids around the entrance to the gut and airway
What are the first mucosal lymphoid aggregates contacted by inhaled or swallowed antigens?
Waldeyer’s ring
Why is it important for the mucosal immune system to modulate inflammation?
Most mucosal tissues have a critical physiological function which can be affected by inflammation
How is inflammation modulated in the mucosal immune system?
Mucosal surfaces are enriched in TGF-b, have toleragenic dendritic cells, noninflammatory macrophages, lots of Treg cells, and more IgA producing plasma cells
How does the mucosal epithelium contribute to the pre-existing defenses of the mucosal immune system?
Simple columnar epithelial cells are impermeable due to tight junctions between the cells; stratified squamous epithelium has no tight junctions allowing diffusion of IgG Ab
True or False: Mucus and antimicrobials are only produced by mucosal epithelial cells in response to a pathogen challenge
False- constitutive production
What intestinal cells are especially good at producing antimicrobials?
Paneth cells
How does mucus contribute to innate defense?
The inner mucus layer is very dense and difficult to penetrate and contains high concentrations of antimicrobials and IgA
Are TLRs expressed on the apical (lumenal) surface of mucosal epithelium cells? What is the importance of this?
They are not otherwise they would constantly be activated by commensal bacteria
How are noninflammatory macrophages produced and how do they contribute to the innate immune defense?
In the presence of of high TGF-b, macrophages down-regulate surface receptors that trigger respiratory burst/ production of proinflammatory cytokines, but they do avidly phagocytose microbes
What makes a dendritic cell toleragenic? What type of T cells do they stimulate development of?
TGF-b and downregulation of costimulatory molecules maintain mucosal dendritic cells in a quiescent state; when they present antigen to CD4+ T cells they generate Treg cells
What is the general utility of toleragenic dendritic cells?
Maintain tolerance to harmless antigens
Which TLRs are adept at recognizing viral infections?
TLR 7-9
What are NOD proteins?
Nucleotide-binding oligomerization domain proteins
What is detected by NOD-1? NOD-2? What transcription factor is stimulated?
NOD-1 detects Gram- negative bacteria; NOD-2 detects both Gram positive and Gram negative; Causes NF-kB signaling
What would result from a mutation in NOD2?
Reduced amount of defensins and other antimicrobials in secretions mean that invasive bacteria and commensals cannot be kept in check
What is microbial translocation?
Prolonged inflammatory responses reduce epithelial barrier integrity such that large amounts of commensal bacteria and microbial products enter the host
How can microbial translocation trigger a systemic immune response?
Infiltrating bacteria and shed LPS chronically stimulate BL TLRs, and LPS drains into the bloodstream
What is Crohn’s disease?
An autoinflammatory bowel disease caused by chronic inflammation due to intestinal immune dysregulation, resulting in loss of epithelial integrity and microbial translocation
How is Crohn’s disease characterized?
Loss of epithelium at inflamed sites
