Skin Inflammation Flashcards
What are the signs of inflammation?
- heat (increased blood flow and vessel dilatation)
- redness (increased blood flow and vessel dilatation)
- swelling (accumulation of fluid)
- pain (pressure on nerve endings)
- loss of function
What are the different types of inflammation in skin?
- urticaria = mass cell mediated (oedema and inflammation of dermis)
- pemphigus (antibody mediated)
- vasculitis (immune complex mediated)
- contact allergic dermatitis (delayed hypersensitivity)
- TB, sarcoidosis (granuloma formation)
What activates mast cell mediated inflammation?
- IgE release histamine, leukotrienes and PGs via mast cell binding
- Th2 cells which have had the antigen presented to them produce IL4,5,GM-CSF which produce B cells producing IgE
What is the role of histamine?
- stimulates sensory nerves (itch)
- smooth muscle contraction (vessel leakage and oedema)
- arteriole dilatation (headache and hypotension)
- modulation of immune response via H2 receptors
- bronchospasms
What is Der P1?
- allergen
- from faecal pellets of dust mite
- breaks down components of tight junctions
- help it cross mucosa
- then get immune response
What are local allergic reactions?
- urticaria
- asthma
- hay fever
What are generalised allergic reactions?
anaphylaxis:
- antigen release into blood stream
- binds to IgE on basophils
- massive release of inflammatory mediators
- bronchospasm and circulatory collapse
What are signs of acute angioedema?
- lower lip swelling
- uvular and tonsillar swelling
- closure of pharynx so cannot talk
- need EpiPen/adrenaline
What is omalizumab used for?
- new treatment for resistant urticaria and asthma
What is pemphigus vulgaris?
- autoimmune blistering disorder
- IgG antibodies bind to desmoglein-3 (part of desmosome)
- leads to suprabasal split and acantholysis
- loss of cohesion between epidermal keratinocytes
What is the treatment for pemphigus vulgaris?
- oral steroids
- immunosuppression
- rituximab
What is immune complex mediated vasculitis?
IgG activated complement:
- deposition of fibrin
- necrosis of vessel wall due to microthrombi blocking vessel
- proteases degrade vessel BMZ
- leaky vessel extravasation of blood and oedema
What are some cutaneous manifestations of immune complex mediated vasculitis?
- early = erythema and oedema
- established = palpable purpura
- severe = ulceration and necrosis
What are some examples of human immune complex diseases in skin?
- systemic lupus erythematosus (DNA and anti-DNA)
- polyarthritis nodose HbsAG (anti-HBs antibody)
What is an example of delayed hypersensitivity?
Contact dermatitis
- wrist-nickel
- watch
- nickel, belt buckle
- rubber in elastic clothing
- topical antibiotics
- primula
What is the role of IL-2 and IFN gamma in contact dermatitis?
- promote Th1 response secretion of IL-2, IL-3, IFN gamma
- promotes macrophage-rich response
What are examples of granuloma formation?
- sarcoidosis
- lupus vulgaris -> cutaneous TB
- treat with JAK inhibitor = ruxolitinib
What are the cells found in skin during inflammation?
- neutrophil
- eosinophil
- lymphocyte
- plasma cell
- macrophage
- mast cell
What is the langerhan cell?
- in the epidermis
- has dendritic cell spine like projections
- presents antigen to CD4+ helper T cell
- picks up antigen entering skin and transport to lymph node
What can cause mast cell degranulation?
- Drugs - aspirin and NSAIDs
- serum factors
- insect sting
- nuts
- shell-fish
- house dust mite
What do mast cells release?-
- histamine
- leukotrienes
- PG
- platelet aggregating factor
What are the effects of mast cell degranulation?
- vascular leak
- bronchoconstriction
- intestinal hypermobility
- inflammation
- tissue remodelling
How does a granuloma form?
- TB causes clonal T cell expansion
- secretion of Th1, cytokines IL2/IFN-y, TNF
- macrophage formation
- fuse to form giant cells/langhans giant cells = granuloma OR transform into histiocytes to form granuloma
What are some common autoimmune skin examples?
- alopecia areata (autoimmunity to hair follicle)
- vitiligo (autoimmunity to melanocyte)
- treat both with strong topical steroids and immunosuppressants
- if Vitamin D levels are low they will not respond to treatment
