GI Immunology Flashcards
antigen processing in the GI tract - define an effective immune response
elimination or control of infections, allergic and noxious agents
epithelial layer of the gut tube
specialised tight junctions that regulate permeability
mucus layer of the gut tube
physical barrier keeping microbes from host cells
innate immune response in the gut tube. What does it do?
senses bacteria + anti-microbial peptides + IgA
soluble mediators of immunity in the gut tube
chemokine and cytokines
immune cell responses
innate cells
granulocyte (neutrophil, eosinophil, basophil)
mast cell
monocyte
dendritic cell
macrophage
natural killer cell
immune cell responses
adaptive cells
CD4+ T cell (memory)
CD8+ T cell (memory)
B cell (memory)
T cell subsets have an important role in
maintaining immune homeostasis
what are payers patches?
a major organised lymphoid structure in the gut
large numbers of immune cells within
payers patches are important for
immune response to commensal bacteria (tolerance) and pathogens (active immunity)
what are macrophages
they are phagocytic and they ingest and kill foreign micro-organisms
macrophages are the first line of defence in the
gut
macrophages secrete
cytokines (eg IL-10)
dendritic cells are important in
mucosal immune responses
different dendritic cell subsets give rise to
distinct T cell responses
different dendritic cell subsets are distinguished by
cell markers
Lamina propria and dendritic cells are important for
directing the function of T cells
APC
antigen presenting cells
dendritic cells undergo maturation into potent what?
antigen presenting cells (APC)
dendritic cell maturation involves:
altered antigen uptake and presentation
increases expression of co-stimulatoru molecules
production of cytokines
Naive T cells functions as
effector cells and effector functions
3 signals that determine T cell response
MHC/peptide TCR
CD80 - CD28
cytokine
gut homeostasis is regulated by the balance between T ….. cells and T ….. cells
helper
regulatory
innate immune system is induced upon
infection with microbes
innate immune system is based on the recognition of
pathogen associated molecular patterns
adaptive immune system is induced upon
infection by specialised pathogens
the adaptive immune system is based on the recognition of
specific antigens presented by professional antigen presenting cells (eg dendritic cells)
adaptive immune response is carried out mainly by
effector cells (mainly T and B cells)
dendritic subsets and macrophages have an important role in
driving T cell differentiation (Th1 or Tregs)
what happens what normal immune homeostasis goes wrong?
IBD
coeliac disease
In IBD there is a dysbiosis in
microbial communities
dysbiosis of microbiota
leaky epithelial barrier
disordered, perpetual innate and adaptive immune response
Treatment strategies for IBD. What do we target?
lymphocytes directly
single cytokines
migration of immune cells to GI mucosa
multiple cytokines
cytokine intracellular signalling pathways
modulation of microbiota
A new drug therapy involves targeting the migration of immune cells to the GI mucosa. The aim is to block the migration of….. to the intestinal mucosal
leucocytes
New ‘biologics’ the IBD arena include:
vedolizumab
ustekinumab
Tofactinib
IBD involves what of the gut microbiota?
dysbiosis
dysbiosis
microbial imbalance or maladaption of microbiota
Coeliac disease is an inflammatory disorder of the
small bowel
coeliac disease is an intolerance to what?
dietary gluten in wheat and similar proteins
symptoms of coeliac disease
iron deficiency anaemia
fatigue
abdominal pain
loose stool
genetic susceptibility to ceoliac disease is linked to…
HLA-DQ2/8 on antigen presenting cells
celiac disease (histology) results in changes to the
gut mucosa
what changes occur in the gut mucosa due to celiac disease?
loss of villi (loss of absorptive capacity)
increase in intra-epithelial lymphocytes
