🦋 Photosensitivity & UV Flare Trigger Simulator

UV Radiation Injures Epidermal Keratinocytes

Placeholder: UV-B and UV-A penetrate skin and damage keratinocyte DNA and membranes.

• Epidermis: UV-B penetration (Placeholder short note)
• Dermis: UV-A penetration (Placeholder short note)
• CPDs: DNA lesion type (Placeholder short note)
• Minutes: Damage onset (Placeholder short note)

Mechanism of UV keratinocyte injury

Placeholder: UV photons induce direct DNA damage and oxidative stress in keratinocytes.

Apoptosis Exposes Nuclear Autoantigens

Placeholder: damaged keratinocytes undergo apoptosis, translocating antigens to cell surface blebs.

• Intrinsic: Apoptosis pathway (Placeholder short note)
• Ro/La, dsDNA: Key antigens (Placeholder short note)
• Impaired: Clearance defect (Placeholder short note)
• Surface: Bleb exposure (Placeholder short note)

Antigen translocation during apoptosis

Placeholder: nuclear antigens relocate to apoptotic blebs, becoming accessible.

Autoantibodies Recognize Exposed Antigens

Placeholder: circulating autoantibodies bind exposed antigens, forming immune complexes.

• IgG, IgM: Antibody classes (Placeholder short note)
• Rapid: Complex formation (Placeholder short note)
• Yes: Complement activation (Placeholder short note)
• Triggered: Local inflammation (Placeholder short note)

Immune complex formation at skin surface

Placeholder: antibody-antigen binding activates complement and recruits immune cells.

Inflammation Produces Visible Skin Lesions

Placeholder: immune complex deposition drives erythema and characteristic lupus lesions.

• Malar rash: Lesion type (Placeholder short note)
• Hours–days: Onset window (Placeholder short note)
• Interface dermatitis: Histology (Placeholder short note)
• Face, chest: Common sites (Placeholder short note)

From immune complex to visible rash

Placeholder: local inflammatory cascade manifests as cutaneous lupus lesions.

Cutaneous Injury Provokes Systemic Flare

Placeholder: skin-derived inflammatory signals can trigger systemic disease activity.

• Joints, kidney: Flare organs (Placeholder short note)
• IFN-alpha: Cytokine surge (Placeholder short note)
• Sun protection: Risk modifier (Placeholder short note)
• SPF50+: Prevention (Placeholder short note)

Systemic amplification of cutaneous injury

Placeholder: cytokines from skin injury circulate and provoke systemic flare.

Placeholder: consistent photoprotection substantially reduces flare risk.