EXAM 3 Mucosal Immunity Flashcards
mucosal surfaces are ___ and prominent at sites of ___
- widespread
- infection
what are the 3 compartments of mucosal tissues?
- epithelium
- lamina propria
- mucosal-associated lymphoid tissue (MALT)
describe the epithelium of mucosal tissue
- single (gut) or multi-celled (mouth) barrier
- intraepithelial lymphocytes (IEL)
- gamma delta T cells
- CD8 alpha alpha T cells
- memory CD8 T cells
describe the lamina propria of mucosal tissues
- lymphatic tissue
- gamma delta T cells
- CD8 T cells
- CD4 T cells - Th1, Th17
- plasma cells and memory B cells
- macrophages
- dendritic cells
describe the mucosal-associated lymphoid tissue of mucosal tissue
- specialized per mucosal tissue
- lymph node-like organization
what is waldeyer’s ring?
a ring of lymphoid tissues in the oral cavity formed by the tonsils and adenoids
around the entrance of the gut and airway
what are the specialized mucosal tissues of the mouth?
tonsils and adenoids
do mucosal infections follow the traditional inflammatory cascade?
no
describe how mucosal immunity often employs limited inflammation
- strong proactive immunity, limited reactive immunity
- most infections often cleared without an inflammatory response
- local innate and adaptive cells respond
- inflammation occurs (neutrophils recruited) if the infection is severe, persists, and/or causes tissue damage
what are the anatomical features of the mucosal immune system?
- intimate interactions between mucosal epithelia and lymphoid tissues
- discrete compartments of diffuse lymphoid tissue and more organized structures such as peyer’s patches, isolated lymphoid follicles, and tonsils
- specialized antigen-uptake mechanisms; ex. m cells in peyers patches, adenoids, and tonsils
what are the effector mechanisms of the mucosal immune system?
- activated/memory T cells predominate even in the absence of infection
- multiple activated natural effectore/regulatory T cells present
- secretory IgA antibodies
- presence of distinctive microbiota
describe the immunoregulatory environment of the mucosal immune system
- active downregulation of immune responses (ex. to food and other innocuous antigens) predominate
- inhibitory macrophages and tolerance-inducing dendritic cells
describe the 2 ways that local adaptive immune cells resolve infection
referring to bacteria:
in the gingival sulcus, there is ___ diversity and richness; in a subgingival periodontal pocket, there is ___ diversity and richness
low, high
describe how the microbiome is constantly shaped at mucosal surfaces
- mucosal layer extablishment
- secreted immune components
- antimicrobial peptides
- IgA
- immune browsing
- the microbiome shapes the mucosal immune system
how does the microbiome influence CD4 T cell differentiation?
- TGF-beta prominent at mucosal surfaces
- mucosal microbiome affects local cytokine environment, and CD4 T cell differentiation
- TGF-beta + no inflammatory cytokines: Treg cells
- TGF-beta + inflammatory cytokines: Th17 cells
- Treg cells inhibit mucosal inflammation
- Th17 cells
- neutrophil recruitment
- antimicrobial peptide production
- tissue repair
in oral immunity, ___ cells protect barriers and induce inflammation when needed
Th17
Th17 cells release IL-17 and IL-22. what does this do?
- regulate tight junction protein expression
- maintain barrier integrity
- induce antimicrobial peptide production
- beta defensins
- cathelicidins
- lactoferrin
- induce neutrophil chemokine expression
impaired or excessive Th17 function is linked to ___
oral disease
what two oral diseases can result from impaired or excessive Th17 function?
chronic mucocutaneous candidiasis and periodontitis
describe chronic mucocutaneous candidiasis
- persistent fungal infection of the skin, nails, and mucous membranes (overgrowth of fungus)
- deficient IL-17 signaling
- numerous causes:
- deficient IL-17, impaired Th17 differentiation, or impaired Th17 development
- oral manifestation
describe periodontitis
- overgrowth of bacterial communities
- increased IL-17 expression corresponds to increased disease severity
- chronic and excessive neutrophil recruitment
- chronic inflammatory cytokine production
- osteoclast activation
what are the important roles that immunoglobulin secretion plays?
- pathogen neutralization
- toxin removal
- antigen browsing
- shapes microbiome
- predominantly IgA
describe how mucosal antigens are constantly browsed
- simultaneous mechanisms
- DC and macrophage antigen exposure
- impacts IgA and antimicrobial peptide production and release
- commensal bacteria repress an immune response
- pathogenic bacteria trigger an immune response
how are epithelial cells active immune components?
- actively direct immune responses
- expresses TLR and NOD receptors
- form inflammasomes
- phagocytose mucosal bacteria
- express cytokines and antimicrobial peptides
- induces local immune responses
how do established pathogens illicit inflammatory responses?
- pathogen evades mucosal immunity
- local macrophages and DCs are activated
- neutrophil recruitment
- Th17, Th1 response
what are the 6 ways mucosal antigens are constantly browsed?
