Psoriasis Causes

What causes psoriasis?

The exact cause of psoriasis is not fully understood. It is believed to involve a combination of genetic, immune system, and environmental factors. Here are some of the known factors that can contribute to the development of psoriasis:

1. Genetic Predisposition: Psoriasis tends to run in families, indicating a genetic component. Certain genes have been identified that are associated with an increased risk of developing psoriasis. However, having these genes does not guarantee that an individual will develop the condition, as other factors are also involved.
2. Immune System Dysfunction: Psoriasis is considered an autoimmune disease, in which the immune system mistakenly attacks healthy cells and tissues. In psoriasis, immune cells called T-cells become overactive, triggering an inflammatory response in the skin. This immune dysfunction leads to the rapid turnover of skin cells and the characteristic symptoms of psoriasis.
3. Environmental Triggers: Certain environmental factors can trigger or exacerbate psoriasis in individuals who are genetically predisposed. Common triggers include:
   • Infections: Bacterial or viral infections, such as strep throat or respiratory infections, can lead to the onset or worsening of psoriasis, particularly in guttate psoriasis.
   • Injury to the Skin: Trauma to the skin, including cuts, burns, or insect bites, may trigger the development of psoriasis lesions known as the Koebner phenomenon.
   • Stress: Psychological stress and emotional factors can influence the immune system and potentially trigger psoriasis flare-ups or worsen existing symptoms.
   • Medications: Certain medications, such as beta-blockers, lithium, antimalarials, and nonsteroidal anti-inflammatory drugs (NSAIDs), can induce or exacerbate psoriasis in susceptible individuals.
4. Lifestyle Factors: Lifestyle choices, including smoking, excessive alcohol consumption, obesity, and a poor diet, have been associated with an increased risk and severity of psoriasis.

It’s important to note that while these factors are known to play a role in the development of psoriasis, the condition can still occur without a clear trigger or explanation. Each person’s experience with psoriasis can be unique, and the specific combination of factors contributing to their condition may vary.

Mechanism of psoriasis

The pathogenesis, or underlying mechanism, of psoriasis involves a complex interplay of genetic, immune, and environmental factors. While the exact cause is not fully understood, scientists have made significant progress in understanding the key components involved. Here is an overview of the pathogenesis of psoriasis:

1. Genetic Predisposition: Certain genes are associated with an increased risk of developing psoriasis. Variations in these genes, particularly those related to the immune system and skin barrier function, can influence an individual’s susceptibility to psoriasis. The most well-known genetic marker is the HLA-Cw6 allele, but there are other genetic factors involved as well.
2. Immune System Activation: Psoriasis is considered an autoimmune disease, in which the immune system mistakenly targets healthy cells in the body. In psoriasis, immune cells, particularly T-cells, are activated and migrate to the skin. These T-cells release inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), interleukin-17 (IL-17), and interleukin-23 (IL-23).
3. Hyperproliferation of Keratinocytes: The activated immune cells in psoriasis produce cytokines that promote the excessive growth and proliferation of keratinocytes, the skin cells. This leads to an accelerated turnover of skin cells, with new cells being produced at a much faster rate than normal. As a result, immature keratinocytes move to the skin surface, leading to the characteristic thickening and scaling of psoriatic plaques.
4. Angiogenesis and Increased Blood Flow: Psoriasis is associated with increased blood vessel formation (angiogenesis) in the affected skin areas. This enhanced blood flow contributes to the redness and inflammation seen in psoriatic lesions.
5. Chronic Inflammation: The sustained activation of immune cells and the release of inflammatory cytokines in psoriasis lead to chronic inflammation in the skin. This chronic inflammation further perpetuates the cycle of immune cell activation, keratinocyte proliferation, and angiogenesis, contributing to the persistence of psoriatic lesions.

It’s important to note that psoriasis is a multifactorial disease, and the precise mechanisms involved may vary between individuals and different types of psoriasis. Ongoing research aims to uncover additional details about the pathogenesis of psoriasis, which may lead to the development of more targeted and effective therapies in the future.

Reference:

1. Das RP, Jain AK, Ramesh V. Current concepts in the pathogenesis of psoriasis. Indian J Dermatol. 2009;54(1):7-12. doi: 10.4103/0019-5154.48977. PMID: 20049260; PMCID: PMC2800878.
2. Rendon, A., & Schäkel, K. (2019). Psoriasis Pathogenesis and Treatment. International Journal of Molecular Sciences, 20(6). https://doi.org/10.3390/ijms20061475
3. https://www.sciencedirect.com/science/article/abs/pii/S1740676504000586
4. https://atm.amegroups.com/article/view/19154/html