Wound Care: Collagen

Collagen

Synthesis

  • Occurs Mainly in Fibroblast Cells
  • Mechanism: Hydroxylation & Cross-Linking of Lysine & Proline Residues
    • Composed of 3 Chains Wound Together as a Triple-Helix
  • Required Cofactors:
    • Oxygen
    • Iron
    • Vitamin C
    • α-Ketoglutarate

Types

  • Type I:
    • Most Common Type (90%)
    • Flexible, Strong & Resistant to Force
    • Found In: Skin, Bone, Tendon & Ligaments
    • Most Common Type in Remodeling & Healed Wounds
  • Type II:
    • Resistant to Pressure
    • Found In: Cartilage
  • Type III:
    • Flexible for Cellular Support
    • Found In: Skin & Blood Vessels
    • Most Common Type During the Proliferation Phase of Wound Healing
  • Type IV:
    • Meshwork Providing Support & Attachment
    • Found In: Basement Membrane
  • Type V:
    • Plays an Essential Role in Collagen Fibrillation & Limiting Size of Heterotypic Type I Collagen Fibrils
    • Found In: Highest Concentration in Cornea & Placenta

Genetic Defects in Collagen

Osteogenesis Imperfecta (Brittle Bone Disease)
  • Defect: Type I Collagen Mn
  • Presentation:
    • Fragile Bones & Growth Deformities
      • Curved Spine
      • Barrel-Shaped Chest
      • Short Stature
      • Bowed Legs
      • Triangle-Shaped Face
    • Easy Bruising
    • Discolored Teeth
    • Hearing Loss in Early Adulthood
    • Blue/Gray Sclera Discoloration
  • Often Mistaken for Child Abuse
  • Diagnosis: Generally a Clinical Diagnosis
  • Treatment: Bisphosphonates & Physical Therapy
Alport Syndrome (Hereditary Nephritis)
  • Defect: Type IV Collagen Mn
  • Presentation:
    • Progressive Glomerular Nephritis
    • Hearing Loss
    • Ocular Abnormalities
  • Diagnosis: Genetic Testing or Kidney Biopsy
  • Treatment: May Require Kidney Transplant
Epidermolysis Bullosa
  • Defect: Type VII (7) Collagen
    • Causes Fragile Epithelium
  • Presentation:
    • Blisters & Erosions After Minor Trauma
    • Fragile Hair
    • Nail Bed Blistering
    • Oral Blisters
  • Diagnosis: Skin Biopsy of an Induced Blister
  • Treatment: Primarily Supportive
Bullous Pemphigoid
  • Defect: Type XVII (17) Collagen & BP Antigen 1
  • Most Common in Older Patients
  • Presentation:
    • Tense Fluid-Filled Bullae on the Skin
  • Diagnosis: Perilesional Skin Biopsy
  • Treatment: Immunosuppressants & Anti-inflammatory Medications
Ehlers-Danlos
  • Defect: Can Affect Multiple Types of Collagen Mn
    • Type V Collagen is Most Common (Classical EDS)
    • Type III Collagen – Vascular EDS
  • Presentation:
    • Joint Laxity & Frequent Dislocations
    • Skin Hyperextensibility
    • Aortic Dilation
    • Mitral Valve Prolapse
    • Poor Wound Healing with Atrophic Papyraceous Scars
  • Diagnosis: Largely Clinical
Marfan Syndrome
  • Defect: Fibrillin-1 (Not Collagen) Mn
  • Presentation:
    • Aortic Disease – Aneurysmal Dilation, Regurgitation & Dissection
      • Primary Cause of Morbidity & Mortality
    • Mitral Valve Prolapse
    • Joint Laxity
    • Tall Stature & Excess Long Bone Linear Growth
    • Abnormally Long Arm Span
    • Scoliosis or Kyphosis
    • Pectus Deformity – Carinatum or Excavatum
    • Ectopia Lentis – Lens Displacement/Dislocation
  • Diagnosis: Primarily Clinical

Mnemonics

Genetic Defects in Collagen

  • I-I: Type I in Imperfecta
  • Al-Four-t: Type IV in Alport
  • “ED Happens to All Men”: All Types in ED
  • Fib-Fan: Fibrillin in Marfan’s