Definition

Noun: 1. A structural protein in the skin: Filaggrin is the primary protein found within keratohyalin granules in the outer layer of the skin (epidermis). It is essential for bundling keratin filaments, which helps form a strong and protective skin barrier. 2. An autoantigen in rheumatoid arthritis: In medical immunology, filaggrin is identified as a specific protein targeted by the immune system in some patients with rheumatoid arthritis.

Usage Examples

• As a structural skin protein:
  • A genetic deficiency in filaggrin is a major cause of dry skin and eczema.
  • The proper function of filaggrin is crucial for maintaining skin hydration and barrier integrity.
• As an autoantigen:
  • Research indicates that antibodies against filaggrin are present in a subset of rheumatoid arthritis cases.
  • The study focused on why the immune system mistakenly attacks filaggrin.

Advanced Usage

• "Filaggrin deficiency": A common genetic condition leading to impaired skin barrier function, often associated with atopic dermatitis (eczema) and ichthyosis vulgaris.
  • Patients with filaggrin deficiency often require intensive moisturizing routines.
• "Filaggrin breakdown products": Refers to the natural metabolites (like urocanic acid and pyrrolidone carboxylic acid) produced when filaggrin degrades, which are important for skin pH and hydration.
  • The concentration of filaggrin breakdown products can be measured to assess skin health.

Variants and Related Words

• Profilaggrin (noun): The large, inactive precursor protein stored in keratohyalin granules, which is later processed into multiple active filaggrin molecules.
  • Profilaggrin is cleaved by specific enzymes to release functional filaggrin.
• Anti-filaggrin antibody (noun): An autoantibody directed against filaggrin, often tested for in the diagnosis of rheumatoid arthritis.
  • The presence of anti-filaggrin antibodies can help classify the type of arthritis.

Synonyms

• Filament-aggregating protein (descriptive synonym, less common).
• Autoantigen (in the specific immunological context, but this is a broader category).

Related Terms and Concepts

• Keratohyalin granule (noun): A cellular structure in the skin where profilaggrin is stored.
• Keratin filament (noun): The structural proteins that filaggrin bundles together.
• Stratum corneum (noun): The outermost layer of the skin, whose formation and function depend on filaggrin.
• Citrullination (noun): A chemical modification of proteins; citrullinated filaggrin is a common target of antibodies in rheumatoid arthritis.

Noun

1. the main protein of the keratohyalin granules
   • the specific target of the immune response in rheumatoid arthritis is filaggrin