What is Psoriasis?
Psoriasis is a not easily transmitted, persisting autoimmune disease that causes swollen skin.
It can be incredibly itchy and form silver plaques on the skin that can be embarrassing and have both physical and psychological effects.
Normally, the skin is divided into three layers-the epidermis, dermis, and hypodermis.
The hypodermis is made of fat and connective tissue that anchors the skin to the underlying muscle.
Just above the hypodermis is the dermis, which contains nerves, sweat glands, lymph and blood vessels.
Just above the dermis is the epidermis. The epidermis itself has multiple cell layers that are composed of developing keratinocytes which are named for the keratin protein that they’re filled with.
Keratin is a strong, fibrous protein that allows keratinocytes to protect themselves from getting destroyed when you rub your hands through the sand at the beach. Keratinocytes start their life at the lowest layer of the epidermis called the stratum.
There are two different types of T Cells, cytotoxic T Cells, which directly kill infected cells, and helper T cells, that help to facilitate the overall immune response. So, if the dendritic cells present these fragments and the fragments are recognized by the T-cell, then the T-cell releases cytokines.
Cytokines are small proteins used in cell signaling – such as IL-12, IL- 23, interferon-γ, tumor necrosis factor or TNF, and IL-17, which specifically has been linked to chronic inflammation.
This entire process of inflammation increases keratinocyte proliferation in the skin. This also recruits other immune cells, like neutrophils, to the site of infection.
Once the microbe is completely destroyed, the immunologic response slowly returns back to normal. In psoriasis, this immunologic response is abnormal, and it leads to excessive inflammation.
The causes of psoriasis aren’t clear but there’s definitely a genetic component and environmental triggers, like trauma, stress, dietary factors, smoking, or a previous infection.
Regardless of how the process is triggered, once it’s underway it doesn’t shut off, resulting in chronic damage to the skin. In the dermis, inflammation causes the blood vessels to dilate, particularly at the border between the dermis and epidermis.
This allows vessels to circulate and deliver more immune cells, particularly neutrophils, to the epidermis.
Symptoms of psoriasis can vary, and there are a few subtypes.
Plaque psoriasis is the most common. It appears as flattened areas of epidermal elevation that are inflamed and red or salmon-colored, from the underlying dilated blood vessels,and are topped with white-silvery scales.
Plaques are typically itchy and found on the scalp and in tensor regions, like the elbows, groin, lower back, and knees.
Guttate psoriasis appears as small, red, individual spots on the trunk and limbs. This subset usually starts in childhood and is sometimes triggered by an infection, like a strep throat.
Inverse psoriasis appears as smooth and shiny red lesions that lack scales and typically form within skin folds like in the genital region, underarms or under the breasts.
Pustular psoriasis appears as areas of red skin with small, white elevations of cloudy pus, formed from dead immune cells.
They are usually tender and form on the hands and feet.
Erythrodermic psoriasis is usually the most severe subset, and appears as fire-red scales that can cover a large area of the skin. They are often extremely itchy and painful and fall off in large sheets.
Psoriatic arthritis manifests as inflammation in the joints. Nail pitting, shallow or deep holes in the nails, may appear in any subset.
The diagnosis is typically based on the distribution of skin damage, and a tissue biopsy can be done to confirm the diagnosis by looking for classic changes in the epidermal layers.
Treatment for psoriasis can include moisturizers and emollients to help clear psoriatic plaques and minimize itchiness or may require topical or systemic immunosuppressive therapies to dampen the immune response.
UV phototherapy can also be an option to induce DNA damage in the keratinocytes and halt their proliferation.
New research has been targeting stress management, dietary intervention, and other immunotherapies to decrease whole body inflammation.
For some individuals, there can be significant feelings of depression or anxiety, especially when there are areas of skin affected by severe psoriasis.
Psychological counseling can help suffers cope with their condition.
In fact, there’s a field called psychodermatology which utilizes strategies like anti-anxiety medications, biofeedback, allergy, and immune function testing, as well as cognitive behavioral therapy.