What is Psoriasis?
Psoriasis is a skin disease that causes red, itchy scaly patches, most commonly on the knees, elbows, trunk and scalp. It is a common, chronic disease with no cure. It tends to go through cycles, flaring for a few weeks or months, then subsiding for a while or going into remission.
The condition affects 2-3% of the population (over 125 million people) and is considered a systemic disease, rather than one limited to the skin. As a systemic inflammatory process, it predisposes, twice as frequently than in the general population, to the development of metabolic disorders, such as insulin resistance, dyslipidemia, hypertension and cardiovascular disease.
This disease decreases the quality of life of the affected and leads to withdrawal from social life and development of depressive disorders. Psoriasis constitutes a serious socioeconomic burden not only for patients but also for health care systems.
What are Common Signs and Symptoms?
Psoriasis signs and symptoms can vary from person to person and they can include:
- Red patches of skin covered with thick, silvery scales.
- Small scaling spots.
- Dry, cracked skin that may bleed or itch.
- Itching, burning or soreness.
- Thickened, pitted or ridged nails.
- Swollen and stiff joints (psoriatic arthritis).
The patches can range from a few spots to major eruptions that cover large areas.
Types of Psoriasis
- Plaque psoriasis. This is the most common form, it causes dry, raised, red skin patches covered with silvery scales.
- Nail psoriasis. It affects fingernails and toenails, causing pitting, abnormal nail growth and discoloration. They might loosen and separate from the nail bed.
- Guttate psoriasis. Affects young adults and children. It’s usually triggered by a bacterial infection such as strep throat.
- Inverse psoriasis. Affects the skin folds of the groin, buttocks and breasts. It also causes smooth patches of red skin that worsen with friction and sweating.
- Pustular psoriasis. This is a rare form of psoriasis that causes clearly defined pus-filled lesions that occur in widespread patches or in smaller areas on the palms or soles.
- Psoriatic arthritis. It causes swollen, painful joints that are typical of arthritis. Sometimes the joint symptoms are the first or only symptom or sign of psoriasis. Symptoms range from mild to severe, and psoriatic arthritis can affect any joint. It can cause stiffness and progressive joint damage that in the most serious cases may lead to permanent joint damage.
What Causes Psoriasis?
The disease is thought to be an immune system problem that causes skin to regenerate faster than normal rates. A central role is played by T helper (Th)1 and Th17 lymphocytes and by cytokines such as tumour necrosis factor (TNF)- α, interleukin 17 and 23.
Recent studies have shown that the prime mover in psoriasis pathogenesis could be linked to a dysfunction in resident mesenchymal stem cells (MSCs), resulting in altered polarization of the immune response.
Some studies suggest that many people who are predisposed to psoriasis may be free of symptoms for years until the disease is triggered by some environmental factor, such as infections, weather, injury to the skin, stress, smoking, alcohol consumption, medications like lithium and antimalarial drugs.
Current Treatment Options
Treatments for psoriasis aim to stop skin cells from growing so quickly and to remove scales. Options include creams and ointments, phototherapy and oral or injected medications.
It can include corticosteroids, which is the most frequently prescribed medication for treating mild to moderate psoriasis; vitamin D analogues that slow skin cell growth; retinoids, such as tazarotene available as a gel and cream; calcineurin inhibitors, such as tacrolimus that can reduce inflammation and plaque buildup; salicylic acid shampoos and scalp solutions reduce scaling of scalp psoriasis; and anthralin that can slow skin cell growth.
Light therapy is a first-line treatment for moderate to severe psoriasis, either alone or in combination with medications. It involves exposing the skin to controlled amounts of natural or artificial light. Repeated treatments are necessary.
Oral or Injected Medications
When topical and local medications don’t work, an oral or injected medication is usually prescribed. They can include steroids, retinoids, immunosuppressive therapy with methotrexate, cyclosporine or biologics.
Mesenchymal Stem Cells in Psoriasis
Mesenchymal stem cells (MSCs) have recently been shown to have not only regenerative capabilities but also immunomodulating properties. For this reason, they are currently under investigation in clinical trials for the treatment of several autoimmune systemic disorders. Psoriasis is a systemic immune-mediated disease for which MSCs could have therapeutic potential.
Mesenchymal stem cells (MSC) in psoriatic plaques have an abnormal profile of cytokines that they secrete, which can influence the keratinocytes stimulating their proliferation and limiting their capability of apoptosis.
A number of studies confirm the involvement of MSCs in psoriasis pathogenesis and therefore designate MSCs as an important potential therapeutic tool in this setting. Preclinical data are mostly based on imiquimod-induced murine models of psoriasis, and confirm the anti-inflammatory and immunomodulatory action of MSCs in the setting of psoriasis.
Currently, the first clinical trials are being conducted into the use of stem cells in the treatment of psoriasis. This idea originated from observation of the remission of lesions in patients treated with mesenchymal or hematopoietic stem cells because of lymphomas and leukemias as well as other autoimmune diseases.
In a study involving 6 patients affected by long-term psoriasis with previously failed topical and systemic treatments. The patients were treated with MSC-based treatments and were previously weaned off any systemic or topical treatments. All the patients had an efficacious treatment with positive clinical outcomes.
MSCs do not only display regenerative capabilities but also have immunomodulating properties. Several studies have demonstrated the efficacy of MSC administration both in patients with psoriasis and in animal models of psoriasis.
Paganelli A, Tarentini E, Benassi L, Kaleci S, Magnoni C. Mesenchymal stem cells for the treatment of psoriasis: a comprehensive review. Clin Exp Dermatol. 2020 Oct;45(7):824-830. doi: 10.1111/ced.14269. Epub 2020 Jun 10. PMID: 32386432.
Owczarczyk-Saczonek A, Krajewska-Włodarczyk M, Kruszewska A, Placek W, Maksymowicz W, Wojtkiewicz J. Stem Cells as Potential Candidates for Psoriasis Cell-Replacement Therapy. Int J Mol Sci. 2017;18(10):2182. Published 2017 Oct 20. doi:10.3390/ijms18102182