إعـــــــلان

**wasan** · 05-05-2010, 06:21 PM

أتمنى إفادتي ..:sm204:

**caesar22** · 05-05-2010, 10:12 PM

Autoimmunity in psoriasis

Introduction

Psoriasis is an autoimmune skin condition which is sometimes associated with arthritis. Symptoms is psoriasis range from a mild rash to severe debilitating pain

Psoriasis is an autoimmune inflammatory skin disorder first described by Ferdinand von Hebra in 1841. In psoriasis skin cells replicate at a faster rate than usual, with new skin cells produced about eight times faster than normal. This causes skin cells to build up on the skin's surface, forming patches of scaling flakes. About 10 to 30 percent of people with psoriasis can also develop a related condition of arthritis known as psoriatic arthritis. Psoriasis ranges from a mild rash or itching affecting a small area of the skin surface to a condition causing widespread itching, pain, and pustules affecting nearly all areas of the body

There are five basic types of psoriasis

1.Plaque psoriasis
is the most common form of psoriasis. It affects 80 to 90% of people with psoriasis. Plaque psoriasis typically appears as raised areas of inflamed skin covered with silvery white scaly skin

2. Flexural psoriasis

appears as smooth inflamed patches of skin. It occurs in skin folds, particularly around the genitals (between the thigh and groin), the armpits, under an overweight stomach (pannus), and under the breasts (inframammary fold). It is aggravated by friction and sweat, and is vulnerable to fungal infections

3. Guttate psoriasis

appears as raised bumps that are filled with non-infectious pus (pustules). The skin under and surrounding the pustules is red and tender

4. Pustular psoriasis

appears as raised bumps that are filled with non-infectious pus (pustules). The skin under and surrounding the pustules is red and tender. Pustular psoriasis can be localised, commonly to the hands and feet (palmoplantar pustulosis), or generalised with widespread patches occurring randomly on any part of the body

a. Nail psoriasis: produces a variety of changes in the appearance of finger and toe nails

b. Psoriatic arthritis: involves joint and connective tissue inflammation

5. Erythrodermic psoriasis

involves the widespread inflammation and exfoliation of the skin over most of the body surface. It may be accompanied by severe itching, swelling and pain

Immunological factors

In psoriasis, immune cells move from the dermis to the epidermis, where they stimulate skin cells (keratinocytes) to proliferate. Psoriasis does not seem to be a true autoimmune disease
In an autoimmune disease, the immune system confuses an outside antigen with a normal body component, and attacks them both. But in psoriasis, the inflammation doesn't seem to be caused by outside antigens (although DNA does have an immunostimulatory effect). Researchers have identified many of the immune cells that are involved in psoriasis, and the chemical signals they send to each other to coordinate inflammation. At the end of this process, immune cells such as dendritic cells and T cells move from the dermis to the epidermis, secreting chemical signals, such as tumor necrosis factor-α, interleukin-1β, and interleukin-6, which cause inflammation, and interleukin-22, which causes keratinocytes to proliferate
The immune system consists of an innate immune system, and an adaptive immune system
In the innate system, immune cells have receptors that have evolved to target specific proteins and other antigens which are commonly found on pathogens. In the adaptive immune system, immune cells respond to proteins and other antigens that they may never have seen before, which are presented to them by other cells. The innate system often passes antigens on to the adaptive system. When the immune system makes a mistake, and identifies a healthy part of the body as a foreign antigen, the immune system attacks that protein, as it does in autoimmunity
In psoriasis, DNA is an inflammatory stimulus. DNA stimulates the receptors on plasmacytoid dendritic cells, which produce interferon-α, an immune stimulatory signal (cytokine). In psoriasis, keratinocytes produce antimicrobial peptides. In response to dendritic cells and T cells, they also produce cytokines, such as interleukin-1, interleukin-6, and tumor necrosis factor-α, which signals more inflammatory cells to arrive and produces further inflammation
Dendritic cells bridge the innate and adaptive immune system. They are increased in psoriatic lesions and induce the proliferation of T cells and type 1 helper T cells. Certain dendritic cells can produce tumor necrosis factor-alpha, which calls more immune cells and stimulates more inflammation. Targeted immunotherapy, and psoralen and ultraviolet A (PUVA) therapy, reduces the number of dendritic cells
T cells move from the dermis into the epidermis. They are attracted to the epidermis by alpha-1 beta-1 integrin, a signalling molecule on the collagen in the epidermis. Psoriatic T cells secrete interferon-γ and interleukin-17. Interleukin-17 is also associated with interleukin-22. Interleukin-22 induces keratocytes to proliferate
One hypothesis is that psoriasis involves a defect in regulatory T cells, and in the regulatory cytokine interleukin-10

Diagnosis

A diagnosis of psoriasis is usually based on the appearance of the skin. There are no special blood tests or diagnostic procedures for psoriasis. Sometimes a skin biopsy, or scraping, may be needed to rule out other disorders and to confirm the diagnosis. Skin from a biopsy will show clubbed Rete pegs if positive for psoriasis. Another sign of psoriasis is that when the plaques are scraped, one can see pinpoint bleeding from the skin below (Auspitz's sign)

المراجع

http://autoimmunedisease.suite101.com/article.cfm/psoriasis

http://en.wikipedia.org/wiki/Psoriasis

إن شاء الله يكون المطلوب .... تحياتي

إعـــــــلان

Autoimmunity in psoriasis

Autoimmunity in psoriasis

تعليق

تعليق