W19 - Autoimmune & autoinflammatory Flashcards
Immunopathology is when in the absence of __________, we have immune dysregulation
Immunopathology is when in the absence of infection, we have immune dysregulation
Describe the part of the immune system responsible for auto-inflammatory disease, autoimmune disease, and mixed immune disease
Auto-inflammatory = innate immune response pathology
Autoimmune = adaptive immune response pathology
Mixed = both innate and adaptive immune response
2 immune cells most commonly implicated in auto-inflammatory diseases are…
macrophages
neutrophils
2 immune cells most commonly implicated in autoimmune diseases are…
T cells
B cells
When discussing autoinflammatory and autoimmune diseases, are monogenic or polygenic causes more common?
Polygenic causes!
Give 1 example of a monogenic autoinflammatory disease
Familial Mediterranean Fever (FMF)
Describe the pathophysiology behind Familial Mediterranean Fever (FMF)
autosomal recessive disease with mutation in gene MEFV => encodes for pyrin-marenostrin => pyrin-marenostrin mainly expressed in neutrophils => failure to regulate cryopyrin driven activation of neutrophils
** pyrin-marenostrin is a negative regulator = less negative inhibition
Inheritence mode of familial mediterrenean fever is….
autosomal recessive
What is the clinical presentation (5) of Familial Mediterranean Fever
- Periodic fevers lasting 48-96 hours associated with:
- Abdominal pain due to peritonitis
- Chest pain due to pleurisy and pericarditis
- Arthritis
- Rash
Describe the main complication that can arise in Familial Mediterraenean Fever disease
Liver produces serum amyloid A as acute phase protein => AA amyloidosis =>
Serum amyloid A deposits in kidneys, liver, spleen => most significant is deposition in kidneys as it causes proteinuria = nephrotic syndrome => renal failure!
What would CRP and SAA show for Familial Mediterranean Fever?
high CRP
high SAA (serum amyloid A)
?What is a diagnostic test for Familial Mediterranean Fever
Blood sample to specialist genetics laboratory to identify MEFV mutation
What is the treatment (3) regimen for Familial Mediterranean Fever (FMF)?
- Colchicine 500ug bd - binds to tubulin in neutrophils and disrupts neutrophil functions including migration and chemokine secretion
- IL-1 blocker
- TNF alpha blocker
Name 2 monogenic autoimmune diseases
- Immune dysregulation, polyendocrinopathy, enteropathy, X- linked syndrome (IPEX)
- Auto-immune lymphoproliferative syndrome (ALPS)
Immune dysregulation, polyendocrinopathy, enteropathy, X- linked syndrome (IPEX)
- Where is the mutation?
- What is the pathophysiology?
IPEX:
- mutation in FOXP3, required for development of Treg cells
- Failure to negatively regulate T cell responses => autoreactive B cells
IPEX - what sort of autoimmune disease (4) do they develop?
- Diabetes Mellitus (70%)
- Hypothyroidism (35%)
- Enteropathy (100%)
- Eczema (70%)
IPEX - what is the clinical picture?
the 3 D’s - Diarrhoea, Diabetes, Dermatitis
Auto-immune lymphoproliferative syndrome (ALPS):
- What is the mutation?
- What is the pathophysiology?
Mutation within FAS pathway
- Defect in apoptosis of lymphocytes => T cells don’t die => Failure of central tolerance => failure of lymphocyte homeostasis
Auto-immune lymphoproliferative syndrome (ALPS) - what is the clinical picture (3)?
- Large spleen and large lymph nodes - due to high lymphocyte numbers
- Autoimmune cytopenias
- Lymphoma
Give 5 examples of polygenic auto-inflammatory diseases
- Crohn’s Disease
- Ulcerative colitis
- Osteoarthritis
- Giant cell arteritis
- Takayasu’s arteritis
Crohn’s disease as a polygenic autoinflammatory disease - which gene is implicated? What is the risk of developing CD in someone with 1 abnormal allele? 2 abnormal alleles
NOD2 gene mutations - are present in 30% of patients
1 abnormal NOD2 allele = 1.5-3x
2 abnormal NOD2 alleles = 14-44x
Describe how mutations of NOD2 cause disease in CD
NOD2 is expressed in cytoplasm of myeloid cells (macrophages, neutrophils, DCs) and is an intracellular receptor for bacterial peptides and promotes their clearance = impaired recognition/clearance in CD
Describe 3 genetics and 2 environmental factors that contribute to CD - describe resultant effect
3 genetics:
- Genetic mutations (NOD2 mutations)
- Epigenetic factors
- microRNAs
2 environmental:
- Intestinal microbiota
- Smoking
End result:
- expression of pro-inflammatory cytokines/chemokines
- Leukocyte recruitment
- Release of proteases, free radicals
Clinical features of CD (4)
- Abdominal pain + tenderness
- Diarrhoea - blood, pus, mucous
- Fever
- Malaise
Name 3 mixed pattern immune diseases
- Axial spondyloarthritis
- Psoriatic arthritis
- Behcet’s syndrome
Axial spondyloarthritis (ankylosing spondylitis) - describe genes implicated
HLA-B27 - accounts for <50% overall genetic risk
IL-23R, ILR-2
highly heritable condition - 90% of th risk of developing this disease is genetic!
Axial Spondyloarthritis - What is the pathophysiology?
Enhanced inflammation occurs at specific sites where there are high tensile forces (entheses - sites of insertions of ligaments or tendons)
Clinical features of Axial Spondyloarthritis (3)
- Low back pain + stiffness
- Enthesitis
- Large joint arthritis
Treatments for Axial Spondyloarthritis (2)
- NSAIDs
- Immunosuppression; anti-TNFa, anti-IL17
Which of the following is an example of a monogenic auto-inflammatory disease?
- Familial Mediterranean fever
- Graves’ disease
- Crohn’s disease
- Axial spondyloarthritis
- IPEX syndrome due to FoxP3 mutation
Familial Mediterranean fever
Which of the following is an example of a monogenic auto-immune disease?
- Familial Mediterranean fever
- Graves’ disease
- Crohn’s disease
- Axial spondyloarthritis
- IPEX syndrome due to FoxP3 mutation
IPEX syndrome due to FoxP3 mutation
Which of the following is an example of a polygenic auto-inflammatory disease?
- Familial Mediterranean fever
- Graves’ disease
- Crohn’s disease
- Axial spondyloarthritis
- IPEX syndrome due to FoxP3 mutation
Crohn’s disease
Describe the 4 types of Gel and Coombs Classification system
Type I - Anaphylactic hypersensitivity
Type II - Cytotoxic hypersensitivity
Type III - Immune complex hypersensitivity
Type IV - Delayed type hypersensitivity
Describe Type I - Anaphylactic hypersensitivity
Type I - Anaphylactic hypersensitivity => immediate hypersensitvity wich is IgE mediated (rarely self antigen)