GI Mucosal Immunology - Treatment of IBD Flashcards
What is the role of the colonic mucosa in immunology?
Detects luminal contents
Recognises commensal microbiome from pathogens that require robust immune response
What are the challenges of antigen processing in the GI tract?
Develop self-tolerance
Develop exogenous tolerance - non-response to newly encountered environmental antigens (food + microbes)
Develop effective immune response - elimination/control of infections, allergic and noxious agents
What is the role of the epithelial layer of the colon in immunology?
Specialised tight junctions that regulate permeability
What is the role of the mucus layer of the colon in immunology?
Physical barrier keeping microbes from host cells
What are the innate immune responses in the colon?
sensing of bacteria and anti-microbial peptides and IgA
What are the antigen presenting cells?
Dendritic cells and macrophage
What are the soluble mediators of immunity?
Chemokines
Cytokines
What is the most important role of T cells?
Maintaining immune homeostasis
What are Peyer’s patches?
Organised lymphoid structure in gut containing large numbers of immune cells
Why are peyer’s patches so important?
Important for immune responses to commensal bacteria and pathogens
What are macrophages?
Phagocytic - ingest and kill foreign micro-organisms
1st line defence in gut
Where are dendritic cells found? + function
Lamina propria and peyer’s patches
Important for mucosal immune responses
Important for directing function of T cells
What 3 signals determine T cell response?
MHC/peptide-TCR
CD80-CD28
Cytokine
What is the innate immune system induced by?
Induced upon infection with microbes
What is the adaptive immune system induced by?
Upon infection by specialised pathogens
What is the pathogenesis of IBD?
Triggering factor unknown
What are the treatment strategies for IBD?
Target lymphocytes directly
Target single cytokines
Target migration of immune cells to GI mucosa
Target multiple cytokines
Target cytokine intracellular signalling pathways
Modulation of microbiota
What does anti-TNF do?
Neutralises cytokine by binding to it - can cause cell death/apoptosis of immune cells
What does Vedolizumab (Entyvio) do?
Blocks migration of leucocytes to intestinal mucosa
What is dysbiosis of microbiota?
Faecal microbial transplant - works in c. diff patients where antibiotics don’t work
What does celiac disease do?
Loss of villi - loss of absorptive capacity
Increase in intra-epithelial lymphocytes
What is the treatment for celiac disease?
Gluten-free diet
