Psoriasis Flashcards
true or false: psoriasis is an autoimmune disease
true -> involves activated T cells:
-some auto-Ag triggers the autoimmune system which activates inflammatory T-cells-> these produce mediators of inflammation
-these mediators then enhance/promote proliferation of keratinocytes-> white/scaly bumps (aka the keratinocytes are not allowed to develop properly (premature maturation))
(not known if the enticing Ag is self-derived or not)
true or false: psoriasis has an unpredictable course of disease
true
true or false: psoriasis is chronic
it is both chronic and relapsing condition
psoriasis
- inflammatory and hyperplastic (increase in cell #/ proliferation) disease of skin
- characterized by erythema (redness) and elevated scaly plaques
- non-infectious
epidemiology of psoriasis
-global prevalence range between 0.1-8.5%
Age of Onset
mean age= 23-37
current theory: 2 distinct peaks with possible genetic associations
-early onset and late onset
-age and 2 peaks are both very important however there is usually some sort of event that starts it all off
early onset of psoriasis
16-22
- more severe and extensive
- more likely to have affected first-degree family member
late onset of psoriasis
57-60
- milder form
- affected first-degree family members nearly absent
Etiology/ Risk factors
- most prevalent autoimmune (?) condition -> most likely an autoimmune disease
- very rarely affects N or S America aboriginals and Japanese (genetics)
- affects M=W
- environmental contributors
- can occur at any age, but 2 onset peaks: 20-30 y/o and 50-60 y/o
- external predisposing factors
- infections
- other associated triggers
explain the reasoning between he possibility of genetics playing a role in psoriasis
- again, very rarely affects N/S American aboriginals and Japanese
- at least 7 loci related to psoriasis
- family history ranges from 35-91% of cases
- 80% concordance in monozygotic twins
What different factors leads to the inappropriate immune response
genetic predisposition +/- predisposing factor + precipitating trigger -> psoriasis development
locus
-specific location of a gene/ DNA sequence on a chromosome
what are some of the external predisposing factors
-obesity-> increases risk of inverse psoriasis
-alcohol consumption
-smoking-> increases risk of developing the disease and increases severity of the disease
-stress
-viral/bacterial infections (ex HIV)- can predispose to disease onset or trigger relapse
predisposing= increased risk of developing disease
What are some infections that can lead to psoriasis
- streptococcal pharyngitis (strep throat) -> CAN CAUSE FLARE OF PSORIASIS OR TRIGGER ONSET
- Candida albicans (thrush)
- Human immunodeficiency virus (HIV) -> INCREASES SEVERITY OF PSORIASIS
- Staphylococcal skin infections (boils) -> CAN CAUSE FLARE OF PSORIASIS
- Viral upper respiratory infections-> CAN CAUSE FLARE OF PSORIASIS
What are some other associated triggers of psoriasis
- certain drugs (lithium, NSAIDS, beta-blockers, antimalarials, interferons)
- cold, dry weather (bad for all skin conditions, including psoriasis
- skin trauma (cuts, bruises, burns, bumps, vaccinations, tattoos) aka “Koebner phenomenon”
-cycle of smoking/ stress/ and resultant headaches leads lots of smokers to take more NSAIDS and then this increases their risk of psoriasis even more
describe how certain dugs can lead to psoriasis
NSAIDS- most important to know it can trigger psoriasis
- interferons- given to people with auto-immune disease which can lead to psoriasis-> important to realize that these autoimmune diseases are often related and can be seen together/ signal the start of another
- this is the same with lithium (depression); beta-blockers (heart disease), etc
“Koebner Phenomenon”
- occurs in almost half of those who already have psoriasis
- occurs within 7 to 14 days of injury to the dermis layer
- therefore it is important to treat these areas asap (very well and aggressively) especially if they are in the risk factor ages/ have other risk factors
- wounds lead to the proliferation of keratinocytes
Linear injury (leading to psoriasis) can be caused by:
- physical injury (insect bites, cuts, scrapes, tattoos)
- chemical burns (chemical irritants)
- excessive rubbing (chafing, shaving)
- sunburns
- allergic reactions (adhesives, contact dermatitis)
- AKA ALL PHYSICAL TRAUMA TO SKIN
Physiological Roles of Skin
- barrier to the elements and pathogens
- barrier to prevent moisture loss
- thermo-regulator protecting the body from excessive heat loss or overheating
- protects from UV radiation
- wound repair and regeneration (if there is a wound, we want it to quickly repair)
- synthesizes Vitamin D (fat soluble- critical for absorption of Ca)
Three layers of the skin
1) epidermis
2) dermic
3) hypo-dermis
epidermis
- physical barrier/ protects the skin from environment
- ranges in thickness from 0.4 to 1.55mm (depending on location on the body)
dermis
-layer of connective tissue containing blood vessels (middle)
hypo-dermis
-provides structural integrity to the skin (inner)
What layer do the keratinocytes move up into during psoriasis?
epidermis
What is the outer most strata within the epidermis
-there are multiple state within the epidermis, but the outer most is the STRATUM CORNEUM
how often does the epidermis renew itself
- 4 to 6 weeks
- this is therefore the follow-up period (if treatment is working, it should be clearing up by this time)
Cells types within the epidermis
- keratinocytes (80-85%)
- melanocytes (5%)
- langerhans cells (2-5%)
- merkel cells (6-10%)
keratinocytes
- produce keratin
- move from the basal cell layer to surface (also called basal cells)
- differentiate on transit from basal cell to stratum corneum (outer skin layer)—> corneocytes
melanocytes
pigment production
langerhans cells
detects, attacks, neutralizes, and eliminates foreign bodies
merkel cells
involved in the function of touch
keratin
- produced by keratinocytes
- key structural material making up the outer layer (integrity) of the human skin (stratum corneum)
- it is also the key structural component of hair and nails
corneocytes
-are keratinocytes that have completed differentiation process and lose their nuclei and cytoplasmic organelles
what is the stratum corneum normally comprised of?
dead keratinocytes (corneocytes) that have migrated from lower stratum basale