The Dermatology Practice.

#psoriasis #psoriasis treatment #biologics #dermatology #dermatologist

Psoriasis is a chronic autoimmune disease affecting millions worldwide, characterized by thick, scaly, and inflamed skin lesions. Additionally, psoriasis can have extracutaneous (beyond the skin) manifestations, affecting joints of the body. Traditional treatments may not provide adequate relief, or may only be skin directed, leading to the development of biologic therapies. This essay delves into the pathophysiology of psoriasis, its clinical manifestations, and the various biologic agents available for treatment.

Pathophysiology of Psoriasis

Psoriasis results from a complex interplay between genetic, environmental, and immune system factors. Key contributors include:

  1. Genetic predisposition: Mutations in genes involved in immune response and skin barrier function
  2. Immune system dysregulation: Overactive T-cells and dendritic cells trigger inflammation
  3. Cytokine imbalance: Elevated levels of tumor necrosis factor-alpha (TNF-α), interleukin-17 (IL-17), and interleukin-23 (IL-23)
  4. Environmental triggers: Allergens, irritants, and stress exacerbate symptoms

Clinical Manifestations of Psoriasis

Psoriasis presents in various forms:

  1. Plaque psoriasis: Most common form, characterized by red, scaly patches
  2. Guttate psoriasis: Small, droplet-shaped lesions
  3. Inverse psoriasis: Smooth, red lesions in skin folds
  4. Pustular psoriasis: White pustules on red skin. It can be confluent (or joined together) to form lakes of pus
  5. Erythrodermic psoriasis: Widespread, severe inflammation
  6. Psoriatic arthritis: Joint inflammation and damage

    7. A-E: Plaque (a), guttate (b), pustular (c), inverse (d), erythrodermic (e). Credits: Sharma et al. Annals of Phytomedicine (2023)

    Sometimes, more than one appearance may be present at the same time.

Biologic Therapies for psoriasis

Psoriasis arise from a complex interplay of inflammatory signalling. Certain cell type e.g. T cells and signalling pathways / molecules.
Biologics target specific molecules involved in psoriasis pathogenesis. Available biologics can be classified into several categories based on the molecules they target. Broadly, there are a few categories:

  1. TNF-α Inhibitors
  2. IL-17 Inhibitors
  3. IL-23 Inhibitors
  4. Phosphodiesterase 4 (PDE4) Inhibitors
  5. Janus Kinase (JAK) Inhibitors (for Psoriatic arthritis)

Efficacy and Safety of Biologics

Biologics have demonstrated significant efficacy in clinical trials, with many showing:

– PASI 75/90: 75%/90% improvement in Psoriasis Area and Severity Index

– IGA 0/1: Investigator’s Global Assessment of clear or almost clear skin.

What is PASI Grading

PASI (Psoriasis Area and Severity Index)

A widely used measure to assess the severity of psoriasis:

Components:

  1. Area affected: Percentage of body surface area (BSA) affected
  2. Erythema (redness)
  3. Induration (thickness)
  4. Scaling

PASI Response Rates:

  1. PASI 50: 50% improvement from baseline
  2. PASI 75: 75% improvement from baseline
  3. PASI 90: 90% improvement from baseline

Common side effects

    N.B. A non exhaustive list of side effects include:

  1. Injection site reactions
  2. Increased risk of infections (upper respiratory tract, sinusitis)
  3. Headache
  4. Malaise or general sense of unwell

Conclusion

Biologic therapies have revolutionized psoriasis treatment, offering targeted and effective options. Understanding the different types of biologics and their mechanisms enables healthcare providers to tailor treatment strategies to individual patient needs. The choice of biologics will depend on the disease severity, any previous treatments and their responses, comorbidities, patient preferences (administrative route, frequency) and/or insurance coverage.

References

  1. Nestle et al. (2016). Psoriasis. New England Journal of Medicine
  2. Sharma et al. (2023). Annals of Phytomedicine
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