Week 9 Autoimmune Flashcards
Etiology factors for autoimmune diseases:
Genetic predisposition
Environmental triggers
Loss of self-tolerance
T-cell activation/differentiation
Autoantibodies
Activation of autoimmune response
General process of autoimmune reaction:
Genetic predisposition + environmental factors > antigen presentation of self-antigen + faliure of self tolerance > generation of autoantibodies and self-reactive T cells > inflammation and destruction of self tissues
T cells in autoimmune:
Th1: cell mediated with TFN and IFN-gamma
Th2: antibody mediated with interleukins
Common genetics in autoimmune disorders:
HLA variants encoding for MHC proteins altering immune regulation, allowing for self targeting
Environmental triggers for autoimmunity:
Disruption to normal immune regulation > creation/activation of autoreaction
Infections, chemicals/toxins, hormone changes, physical/psych. Stress, compounded with genetic predisposition
Loss of self tolerance in autoimmune:
Faliure to recognise self-antigens > damage from autoantibodies and autoreactive T-cells
Autoantibodies in autoimmune:
Self reactive B cells > antibodies against self-antigens > Immune complex deposited in tissue > immune reaction
Common autoantibodies: rhematoid factor (RA), anti-nuclear antibodies in lupus
Adaptive immune process in autoimmune:
Antigen presenting cells (dendritic/macro.) endocytose FB > process into peptide antigens > presented to naive CD4+ T cell via MHC on APC surface > Differentiate to T helper cell (Th1/2) > mediate inflammation via cytokines
Activation of autoimmune response:
Molecular mimicry/self-presenting dendritic cell autoantigen exposure > autoimmune response > inflammatory cascades > cytokine release/macrophage recruitment > tissue damage
Graves’ disease patho:
Unknown trigger > production of IgG antibodies against thyroid stimulating hormone receptor
Activation of TSHRs > ^thyroid hormone production > hyperthyroidism
Thyroid ophthalmopathy occurs seccondary to Graves’
Graves’ disease symptoms
^metabolism > weight loss, sweating, heat intolerance
Hyperactive sympathetic NS > nervousness, irritability, heart palpatiations
Negative feedback mechanism > high TH, low thyrotropin-releasing hormone
Fatigue, enlarged thyroid gland (neck), alopecia
Thyroid eye disease risks:
Thyroid ophthalmopathy from 25-50% grave’s Px.
^with smoking, immunotherapy, radioactive iodine therapy (graves’ treatment)
TED patho:
IgG against TSHRs cross-react with similar antigens in orbit soft tissue fibroblasts/adipocytes (TSHR mRNA)
Cross-reactivity > autoreactive T cells infiltration to orbit fat/muscle (initiation) > T-cells release cytokines stimulating fibroblast proliferation and GAG production > GAG water retention/cellular infiltration > orbit fat/adipocyte/EOM swelling
TED process:
Inflammatory phase (1.5-3y) > Fibrotic (quiescent) stage
Superior and inferior lid retraction in TED:
Inflammation > fibrosis > lid retraction > clinical signs:
Dalrymple sign: retraction in primary gaze
Kocher sign: staring/attentive fixation
Von Graefe sign: abnormal descent of upper lid on downgaze