Psoriasis Can Occur In Several Forms

Plaque-type psoriasis is the most common form of the disease and is commonly referred to as psoriasis vulgaris (Camisa 56). It is characterized by inflamed skin lesions topped with silvery white scales. It can assume many different appearances based on where it is located, the activity of the disease, and the treatment being administered. It is most commonly found on the elbows, knees, scalp, sacrum, umbilicus, intergluteal cleft, and genitalia (Camisa 56).

Guttate psoriasis is characterized by small dot-like lesions. It is most common in children and young adults who have a prior history of upper respiratory infection, pharyngitis, or tonsillitis (Camisa 64). The lesions are not as scaly as plaque-type psoriasis and are likely to be found on the trunk and involve the face (Camisa 64).

Pustular psoriasis is characterized by pustules, which are blister-like lesions of non-infectious fluid, and intense scaling. Individuals with pustular psoriasis are often among the most seriously ill and may have to be hospitalized (Camisa 67).

Erythrodermic psoriasis is the most uncommon form of psoriasis and is characterized by intense redness and swelling, exfoliation of dead skin, and pain. Erythrodermic psoriasis usually develops during the course of chronic psoriasis, however in some cases it may be the initial type of psoriasis even in children (Camisa 74). Individuals with this type of psoriasis may experience chills, low grade fever, and may be rather uncomfortable (Camisa 75).

Inverse psoriasis is characterized by smooth inflamed lesions in the body folds -- armpits, under the breast, skin folds of the groin, buttocks, and genitals.

Koebner's Phenomenon psoriasis are psoriatic lesions which appear at the site of injury, infection or other skin psoriasis, or may be a new lesion in an existing case.

The degree of psoriasis can also vary from individual to individual. It ranges in severity from mild (affects less than 2% of body) to moderate (affects 2-10% of body) to severe (affects greater than 10% of the body). Skin injury and irritation, sun exposure, diet, stress and anxiety, medications, and infections have been known to make psoriasis worse.

Senate Calls For Improvements In Psoriasis Treatment

The U.S. Senate passed Senate Resolution 420 (S. Res. 420), a bipartisan resolution calling for improvements in treatment and access to care for individuals with psoriasis and psoriatic arthritis. Sen. Gordon Smith, R-Ore., lead sponsor of the resolution, is a dedicated champion for the psoriasis community and worked to ensure passage of the measure.
Sen. Frank Lautenberg, D-N.J., joined Smith in leading the effort; they were supported by Sens. Tim Johnson, D-S.D., Robert Menendez, D-N.J., Rick Santorum, R-Pa., John Warner, R-Va., and Ron Wyden, D-Ore.
The resolution recognizes that psoriasis and psoriatic arthritis can be painful, debilitating diseases that can significantly and adversely impact quality of life. Millions of people hold misconceptions about psoriasis, and it remains an often misunderstood disease. The resolution draws much-needed attention to the seriousness of psoriasis, the importance of early diagnosis and proper treatment, and the need for public awareness about psoriasis.
Through passage of the resolution, the U. S. Senate is encouraging the federal government to expand its psoriasis research efforts, including the psychological and physical effects of the disease. The Senate resolution also supports efforts to increase access to treatments for individuals living with psoriasis and psoriatic arthritis. The National Psoriasis Foundation will work with members of Congress and federal research agencies to ensure that the intent of the resolution is carried out.
"The National Psoriasis Foundation applauds today's Senate passage of an important resolution seeking to improve psoriasis research and access to care," said Gail M. Zimmerman, president and CEO of the National Psoriasis Foundation. "As many as 7.5 million Americans live with psoriasis, which is a serious disease. Thanks to the leadership of Senators Smith and Lautenberg, the need to boost psoriasis research and access to care has been elevated at the highest level of government."
Passage of S. Res. 420 is part of a comprehensive federal legislative agenda being pursued in Washington, D.C., by the Psoriasis Foundation. The Psoriasis Foundation is also advocating passage of a resolution in the House of Representatives that is similar to the Senate resolution. The House resolution (H. Con. Res. 340) urges expansion of genetic, clinical and basic research focused on increasing understanding of the causes of psoriasis and psoriatic arthritis. It also calls for the Secretary of Health and Human Services to convene a special panel to study the availability of treatments for individuals with psoriasis and psoriatic arthritis.

Immune System Involvement In Psoriasis

In 1979, researchers coincidentally found that a drug–cyclosporine–that suppresses the immune system in bone marrow transplant patients also cleared psoriasis. Since then, psoriasis has been widely accepted as a disease that is involved with the immune system. The study of the immune system is called immunology.
How does the immune system affect psoriasis?A normal immune system protects the body against "invaders" by destroying bacteria, viruses and other foreign proteins. In the person who has psoriasis, the immune system "misfires" and inappropriately causes inflammation and an accelerated growth of skin cells.
The skin cells reproduce too quickly and the skin (and the joints in some people) becomes inflamed. Many steps in this misfired immune response are targeted by old and new treatments. One goal of treatment is to block or modify the response by focusing on very specific immune cells, thus avoiding widespread effects on the rest of the body.
For example, methotrexate (a prescription systemic medication used to treat psoriasis) binds to an enzyme involved in the rapid growth of cells that is triggered by the immune system response in psoriasis. But methotrexate affects other systems in the body, too. New drugs, called biologics, have been designed to target very specific parts of the immune system response. For more information about this class of treatments, see the biologics section.
Many of today's psoriasis treatments, including cyclosporine and methotrexate, are believed to work because they affect the immune system. However, newer drugs may be "smarter" in that they target specific immune responses, not the entire immune system. Because they are new, long-term effects of these drugs are essentially unknown.
What is the role of T cells?Psoriasis is frequently referred to as a "T-cell mediated disease." T cells are a type of immune system cell (white blood cell) that have been shown to be very important in the internal process of psoriasis. T cells naturally circulate throughout the body looking for antigens, or foreign substances. The presence of the antigen, usually an outside invader like a bacterium or virus, activates the T cell, which then initiates an immune response to neutralize the antigen.
In psoriasis, activated T cells end up in the skin. It is not clear why this happens, but it may be directly related to the genetic susceptibility in people who develop psoriasis.
T cells become activated by two necessary interactions.
Interaction One
An antigen-presenting cell (APC) processes and displays an antigen on its surface. A T cell recognizes and targets that antigen. The specific antigen or antigens responsible for psoriasis are not known, but some infections (for example, strep throat) create an antigen believed to trigger some cases of guttate psoriasis.
Interaction Two
When the APC "shows" the antigen to the T cell, other receptors on the APC and T cell must also interact like a lock and key for the T cell to become activated. This lock and key mechanism is called the co-stimulatory pathway.
If T cells are not activated, the immune response and the cycle of psoriasis never get started. If the T cell becomes activated, an immune response is initiated that leads to the development of skin lesions. One part of this response includes the release of cytokines. Cytokines are proteins that the immune system uses to communicate messages. In psoriasis, cytokines tell skin cells to reproduce and mature at an accelerated rate. They also set off other reactions, including inflammation, the activation of additional T cells, the recruiting of T cells into the skin and the release of more cytokines.
The end result is a cycle of skin cells growing too fast, moving to the surface of the skin and piling up as dead cells (the white scale). The top, or epidermal, layer of the skin thickens, and redness develops as blood vessels expand and multiply, and blood flow to the skin increases.
How is the immune system modulated?The lock and key sets, or co-stimulatory pathways, are a good target for new psoriasis drugs to short-circuit psoriasis. Beyond that, other immune system cells involved in psoriasis are also a focus of drug development.
For example, some cytokines carry inflammatory messages and help fuel the overall immune response in the skin. Some of these cytokines, such as tumor necrosis factor-alpha (TNF-alpha), are targeted to be blocked by several of the biologic treatments now on the market.
On the other hand, some cytokines that normally suppress inflammation are lacking or present only in low levels in psoriatic skin. Scientists have experimented with boosting the levels of these proteins to rebalance the biochemical make-up of the skin.
What lies ahead?Psoriasis research is benefiting from the fact that psoriasis is driven by the immune system and responds to drugs that suppress the body's immune response (immunosuppressive therapy). Many other diseases and medical problems, such as diabetes, lupus and rheumatoid arthritis, are also driven by the immune system. Genes that are associated with psoriasis are also involved with rheumatoid arthritis and lupus. Because psoriasis is easily visible on the skin, the disease provides an excellent model for studying the effectiveness of various medications that might be useful in other diseases that also involve the immune system.