Autoimmune and Autoinflammatory diseases Flashcards
Define immunopathology
Define autoimmune and autoinflammatory diseases
Damage to the host cause by the immune response
Immunopathology in the absence of infection
What is the difference?
Autoinflammatory = abnormal response of innate system (macrophages, neutrophils). Often localised site
Autoimmune = breaking of tolerance in adaptive immune system (B and T cells. May get organ-specific Abs in preclinical period
Monogenic autoinflammatory diseases:
MOA
Examples
Single gene mutation -> abnormal cytokine TNF/IL-1 signalling
Familial mediterranean fever, TRAPS
Pyrin-Marenostrin -ve regulator and cryopyrin +ve on ASC protein.
ASC -> procaspase 1-> IL-1, NFkappaB, Apoptosis
inflammasome complex
(which is activated by toxins, microbial antigens and urate)
Monogenic autoinflammatory diseases there is loss function pyrin and gain function cryoparin
MEFV gene mutation
loss function pyrin-marenostrin on neutrophils
Familial mediterranean fever
Monogenic auto-inflammatory disease
Presentation of Familial mediterranean fever
Periodic fevers lasting 48-96 hours
+ ‘-itis’
Abdominal pain due to peritonitis
Chest pain due to pleurisy and pericarditis
Arthritis
Rash (often red)
Tx Familial mediterranean fever
Colchicine 500ug bd (binds to tubulin in neutrophils and disrupts neutrophil functions)
2nd line: Anakinra or Etanercept
Complications Familial mediterranean fever
AA Amyloidosis (Inflammation stimulates liver to produce lots of acute phase proteins amyloid A which deposits in kidneys, liver, spleen)
Monogenic Autoimmune diseases 3 kinds:
Abnormality in tolerance
Abnormality of regulatory T cells
Abnormality of lymphocyte apoptosis
Abnormality in tolerance = APS1/APECED, due to defect in AIRE
Abnormality of regulatory T cells = IPEX due to Foxp3 mutation
Abnormality of lymphocyte apoptosis
= ALPS due to defect in death pathway of lymphocytes
APS1/APECED
Defect in AIRE transcription factor leads to failure of central tolerance and -> Autoreactive T and B cells
Monogenic autoimmune disease
Leads to abnormality in tolerance
Clinical presentation of APS1/APECED
auto-immune diseases
- Hypoparathyroidism
- Addisons
- Hypothyroidism,
- Diabetes, Vitiligo,
- Enteropathy
- Candidiasis infections due to anti-cytokine antibodies (IL-17 and IL-22)
Monogenic AI disease
Abnormalities of regulatory T cells
IPEX
Mutations in Foxp3 ->
Failure to negatively regulate T cell responses + Autoantibody formation
Clinical presentation of IPEX
Autoimmune diseases - 3 D's (diarrhoea, diabetes, dermatitis) Enteropathy Diabetes Mellitus Hypothyroidism Dermatitis (eczema)
Monogenic AI disease
Mutations within FAS pathway - >Abnormality of lymphocyte apoptosis
ALPS
Clinical presentation of ALPS
High WCC large spleen and lymph nodes double negative (CD4-CD8-) T cells Auto-immune disease commonly auto-immune cytopenias Lymphoma
Single gene mutation involving FOXp3 resulting in abnormality of T reg cells
IPEX (immune dysregulation, polyendocrinopathy, enteropathy, X linked)
Single gene mutation involving MEFV and affecting the inflammasome complex, resulting in recurrent episodes of serositis
Familial Mediterranean Fever
Mutation within the Fas pathway associated with lymphocytosis, lymphomas and auto-immune cytopenias
Auto-immune lymphoproliferative syndrome (ALPS)
Polygenic Autoinflammatory diseases
Examples
Crohns, UC, osteoarthritis, giant cell arteritis, Takayasu’s arteritis
Local factors at sites predisposed to disease
Weak HLA associations
No auto-antibodies
Polygenic Autoinflammatory diseases
RF: NOD2 gene mutations are present in 30% patients/CARD15 mutation
Also Other genetic influences/Environmental factors
-> crypt inflammation, granulomatas, tissue damage, mucosal ulceration
Crohns disease