Inflammation and IBD
, Gut and IBD
background
• In a healthy gut, the mucous layer Components of the gut epithelium and their
protects the epithelium from bacterial The villi
invasion. • Within the villi is a network of blood vess
allow transport of nutrients to the rest of
• The gut starts from the mouth. When Lymphatics from the peyer’s patches and
food is eaten, it is swallowed drain into the mesenteric lymph node.
accompanied by a range of • Within the villi is the lamina propria (loos
microorganisms. Most, but not all, are connective tissue).
destroyed by the harsh acidic • At the base of the villi are the crypts whic
environment of the stomach. Those that stem cells that replenish the epithelium.
don’t, make it to the intestine. The peyer’s patches
• Embedded in the peyer’s patch is a mix o
• The surface of the intestine is covered immune cells including:
with villi (main function is absorption of • T and B cells
nutrients). • Macrophages
• DCs
• Along the intestinal mucosa are • Key function- antigen sampling. To facilita
scattered dome-like structures called peyer’s patch has a thinner mucus layer
peyer’s patches specialised phagocytotic cells called M ce
transport materials across the epithelium
• These are enriched with lymphoid tissue transcytosis.
making them important sites for
coordinating immune responses to
pathogens and tolerance to harmless
, Antigen sampling and immune
tolerance
• DCs are able to extend dendrites betwe
epithelial cells to sample antigens which
down and presented to lymphocytes.
• Antigen sampling this way usually result
‘tolerogenic activation’ of immune cells
an anti-inflammatory response
• DCs then migrate to the T-cell zones of p
When they encounter specific T cells, th
convert them into Treg cells
•
• Defective Treg cells are associated
• Treg cells migrate to the lamina propria
via the lymphatics where they secrete IL
• IL-10 has a suppressive action on immu
within the lamina propria and the epithe
• Chemical, mechanical or pathogens trig
barrier disruption coupled with some ge
predisposition may combine to set off
inflammation.
, Gut and IBD
background
• In a healthy gut, the mucous layer Components of the gut epithelium and their
protects the epithelium from bacterial The villi
invasion. • Within the villi is a network of blood vess
allow transport of nutrients to the rest of
• The gut starts from the mouth. When Lymphatics from the peyer’s patches and
food is eaten, it is swallowed drain into the mesenteric lymph node.
accompanied by a range of • Within the villi is the lamina propria (loos
microorganisms. Most, but not all, are connective tissue).
destroyed by the harsh acidic • At the base of the villi are the crypts whic
environment of the stomach. Those that stem cells that replenish the epithelium.
don’t, make it to the intestine. The peyer’s patches
• Embedded in the peyer’s patch is a mix o
• The surface of the intestine is covered immune cells including:
with villi (main function is absorption of • T and B cells
nutrients). • Macrophages
• DCs
• Along the intestinal mucosa are • Key function- antigen sampling. To facilita
scattered dome-like structures called peyer’s patch has a thinner mucus layer
peyer’s patches specialised phagocytotic cells called M ce
transport materials across the epithelium
• These are enriched with lymphoid tissue transcytosis.
making them important sites for
coordinating immune responses to
pathogens and tolerance to harmless
, Antigen sampling and immune
tolerance
• DCs are able to extend dendrites betwe
epithelial cells to sample antigens which
down and presented to lymphocytes.
• Antigen sampling this way usually result
‘tolerogenic activation’ of immune cells
an anti-inflammatory response
• DCs then migrate to the T-cell zones of p
When they encounter specific T cells, th
convert them into Treg cells
•
• Defective Treg cells are associated
• Treg cells migrate to the lamina propria
via the lymphatics where they secrete IL
• IL-10 has a suppressive action on immu
within the lamina propria and the epithe
• Chemical, mechanical or pathogens trig
barrier disruption coupled with some ge
predisposition may combine to set off
inflammation.
