08 Infection And Immunology Of The Gut Flashcards
What can cause dysbiosis (5) and what can this affect
Diet Genetics Infection and inflammation Hygiene Xenobiotics Dysbiosis is associated with asthma, IBD & coeliac disease, development of immune system, type 1 diabetes, atherosclerosis and rheumatoid arthritis
List the factors that contribute to mucosal defence
Physical - anatomical structure by epithelium - chemical by acid secretion and lysozyme Commensal bacteria Immunological - GALT - MALT
What constitutes of epithelial barrier
Mucus layer - goblet cells Epithelial monolayer - tight junction - IgA Paneth cells - bases of Crypt - antimicrobial peptides such as defensin - lysozyme
Name the organised and not organised components of GALT
Not organised: Intra epithelial and lamina propria lymphocytes
Organised: Peyer’s patches, colonic/caecal patches, isolated lymphoid follicle, mesenteric lymph node
Describe Intra epithelial lymphocytes
Makes up 1/5 of intestinal epithelium
Conventional T cells
Unconventional T cells (less diversity, gamma delta TCR)
Innate cells such as NK cells
What are the characteristics of follicle associated epithelium
No goblet cells
No secretory IgA
Lacks microvilli
Infiltrated by T, B, macrophages and DC
Distinguish the structures between small and large intestine
Small intestine uniquely has: Peyer’s patches Looser mucus Villi Fewer commensal bacteria Fewer goblet cells
Summarise the process of lymphocyte recirculation
Naive lymphocytes circulate in the blood and become rolling along endothelial cells around HEV by selecting binding which is subsequently adhered by adhesion molecules (a4B7 integrins/MAdCAM-1) and eventually cause diapedesis and migrate to mesenteric lymph node.
If not activated - death. If activated it is then recirculated into bloodstream to the site of infection via lymphatic to thoracic duct
Cholera: symptoms, diagnosis, treatment/management associated
Cholera serotupe O1 and O139
Watery diarrhoea
Rehydration therapy and vaccines available
Bacterial culture from stool on agar plate and dipsticks
Name the viruses that cause gastroenteritis
Rotavirus
Norovirus
Name the bacterium that is associated with raw poultry
Campylobacter
What is the significance of E coli (EHEC)
E. coli O157 serotype
5-10% get haemolytic uraemia syndrome: loss of kidney functions
What is the mechanism of gastroenteritis with C.difficile and its management
Antibiotic therapy kills off commensal bacteria and the accumulation of C.difficile causes mucosal damage and result in neutrophil and erythrocytes leakage into gut through the epithelium
Management: stop current antibiotics, isolate patient, treat with vancomycin or metronidazole. Alternatively: FMT (faecal microbiota transplantation)
What are the symptoms for immunological disorder of the gut. What are is the diagnosis for such disorder
Abdominal pain Altered bowel movements Diarrhoea (may be bloody) Fever Malabsorption (weight loss) Cramping/bloating Diagnosis: symptoms, blood tests and endoscopy
Compare the pathology between ulcerative colitis and Crohn’s disease
Restricted to colon vs spread throughout GI tract (mostly distal small intestine)
Continuous area of inflammation vs patches of inflammatory damage inter spread with healthy tissues
Damage to mucosa and submucosa only vs throughout entire intestinal wall
Surgery is curative vs surgery not curative but may enhance quality of life
