Autoinflammatory and Autoimmune Disease Flashcards
Define immunopathology.
Damage to the host caused by the immune response
What causes the damage in
- Fevers/malaise seen in primary EBV
- Absces formation
- Sacroiliac joint inflammation in an individual with axial spondyloarthritis
- Anaemia due to red cel haemolytic secondary to anti-red cell antibodies
How do we name the different immunopathologies in the absence of infection?
Define auto-inflammatory diseases.
Local factors at sites predisposed to disease lead to activation of innate immune cells such as macrophages and neutrophils, with resulting tissue damage
Define auto-immune diseases.
Aberrant T cell and B cell responses in primary and secondary lymphoid organs lead to breaking of tolerance with development of immune reactivity towards self-antigens
Organ-specific antibodies may predate clinical
disease by years
Adaptive immune response plays the
predominant role in clinical expression of disease
What are monogenic and polygenic changes?
monogenic - polymorphism in one gene
polygenic - polymorphisms in more than one gene.
Are the immunopathologies monogenic or polygenic?
Define germline mutations.
Germline mutations affecting DNA sequence - Alteration in DNA that occurs in germ cells (sperm and ova and progenitors) and will be passed on to offspring
Define somatic mutations.
– Somatic mutations affecting DNA sequence - Alteration in DNA that occurs in a single body cell after conception, does not affect germ cells and so is not inherited
Define epigenetic.
(Heritable) change in gene expression
(eg via DNA methylation)
Define microRNA.
MicroRNA (miRNA) - Small, non-coding, single stranded RNA
targets mRNA and regulate protein production
Complete.
Define monogenic auto-inflammatory diseases. How do they classically present?
Mutations in a gene encoding a protein involved in a pathway associated with innate immune cell function
Abnormal signalling via key cytokine pathways involving TNF-alpha and/or IL-1 is common
Classically present with
- periodic fevers
- skin/joint/serosal/CNS…. inflammation
- high CRP
What are examples of monogenic auto-inflammatory diseases
Describe the the inflammasome complex in monogenic auto-inflammatory diseases.
Describe the pathogenesis of familial Mediterranean fever.
Pathogenesis
Autosomal recessive condition
Mutation in MEFV gene
MEFV gene encodes pyrin-marenostrin
Pyrin-marenostrin expressed mainly in neutrophils
Failure to regulate cryopyrin driven activation of neutrophils
What is the epidemiology of familial Mediterranean fever?
What is the clinical presentation of familial Mediterranean fever?
Clinical presentation
Periodic fevers lasting 48-96 hours associated with:
Abdominal pain due to peritonitis
Chest pain due to pleurisy and pericarditis
Arthritis
Rash
What are the complications of familial Mediterranean fever?
What are the Ix for Familial Mediterranean fever=?
High CRP, high SAA
Blood sample to specialist genetics laboratory to identify MEFV mutation
What is the Tx for Familial Mediterranean fever?
Colchicine 500ug bd - binds to tubulin in neutrophils and disrupts neutrophil functions including migration and chemokine secretion
IL-1 blocker (anakinra, canukinumab)
TNF alpha blocker
Define monogenic auto-immune diseases.
Mutation in a gene encoding a protein involved in a pathway associated with adaptive immune cell function
Abnormality of regulatory T cells - IPEX
Abnormality of lymphocyte apoptosis - ALPS
What is the mutation in Immune dysregulation, polyendocrinopathy,enteropathy,
X- linked syndrome
IPEX
Mutations in Foxp3 (Forkhead box p3) which is required for development of Treg cells
Failure to negatively regulate T cell responses
Autoreactive B cells
limited repertoire of autoreactive B cells
What are examples of monogenic auto-immune diseases?