Skin diseases Flashcards
psoriasis
a complex, chronic and multi-factorial inflammatory disease which involves hyper proliferation of the keratinocytes in the epidermis. Thought to be the result of interplay between genetic predisposition and environmental factors
what can trigger psoriasis
infection, injury, allergy, extreme tips, alcohol, stress resulting in an inflammatory response
psoriasis occurs due to an increased
production of skin cells- long lasting chronic disorder.
process which causes psoriasis
1) trigger e.g. injury, infection, allergy, chemical, stress
2) langerhans cells waiting for engulfment
3) these triggers (sometimes PAMPs) will then trigger langerhans - engulfment - antigen presentation
4) langerhans migrate to the lymph nodes –> antigens presented to naive t helper cells (CD4+ cells)
5) langerhans secrete TGF-B, IL-6 and IL-23 –> stimulate T cells to turn into Th17 cells
6) Th17 cells produce IL-17 –> psoriatic skin
what can also trigger an inflammatory response
commensal bacteria
layers of the skin
outside –> inside
Stratum corneum stratum lucidum stratum granulosum stratum spinosum stratum basale
how does psoriasis affect the layers of the skin
- stratum granulosum reduced or absent
- stratum basel becomes obsessively proliferative
- quick replication of keratinocytes (no differentiated cells due to lack of apoptosis)
- nucleated undifferentiated cells one to the top layer of the skin
why is psoriasis red
due to blood vessel growth needed to satisfy vascular need of quickly reproducing cells
cells in psoriasis
dont stack very well due to being cuboidal
summary of psoriasis
auto-immune disease which involves the over activation of keratinocytes which live in the statute basal by cytokines which leads to them becoming excessively proliferative
what are SNPs
single nucleotide polymorphisms
- subsitutions
- deletion
- insertion
SNPs can be used as
biological markers
some SNPs can help predict
responses to drug or risk of developing a disease e.g. skin cancer
to find SNPs
primers extending from SNPs used
which three genes are significantly associated with psoriasis
HLA-C
IL12B
IL24R
which cytokines are produced in excess in psoriasis
TNF, IL which trigger inflammation in the skin and other organs
what effect do cytokines have
- widened blood vessels
- accumulation of WBC
- rapid multiplication of keratinocytes
normal keratinocytes
take a month to divide, mature and migrate to the skin surface and be shet
psoriatic keratinocytes
process takes 3 to 5 days, resulting in thickened, red skin, that sheds silvery scales of keratinocytes which have matured too qucikly
skin cancers
develop from abnormal cells in the skin which have he ability to spread to other parts of the body
three types of skin cancer
1) basal-cell skin cancer
2) squamous-cell skin cancer
3) melanoma
basal-cell skin cancer
arises from basal cells- slow growing and unlikely to spread to distant areas
squamous cell
more likely to spread. Uncontrolled growth of abnormal cells arising in squamous cells
melanoma
most aggressive. begins in melanocytes and is much more likely to spread to other parts of the body
