Amyloidogenesis in healing wound. Electron microscopic studies of biopsied wounds in macular amyloidosis
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Abstract:
Clinically and histologically typical skin lesions of macular and lichenoid amyloidoses were biopsied. Rebiopsies were performed after 2 to 16 weeks, and the sequence of amyloid reproduction in granulation tissue was followed. Initially, medium electron-dense proteinaceous substance with fine filaments was produced within or in close relation to the rough-surfaced endoplasmic reticulum of fibroblasts and subsequently discharged. Typical amyloid filaments emerged within and in the vicinity of this substance. A significant number of collagen fibrils were admixed in the centers of some amyloid islands. Predominantly amorphous amyloid substance was seen in contact with the basal laminae. No plasma cells were observed in foci of amyloid. Nonepithelialized wounds did not contain amyloid. It was suggested that, in the primary skin amyloidoses, abnormal dermal fibroblasts produce amyloid precursors under the influence of the epidermis.
Insights
In primary skin amyloidoses, abnormal dermal fibroblasts produce amyloid precursors. This process involves initial proteinaceous substance discharge, followed by amyloid filament formation, suggesting an epidermal influence.
Area of Science:
- Dermatology
- Pathology
- Biochemistry
Background:
- Amyloidosis is a group of diseases characterized by the deposition of amyloid fibrils in various organs.
- Primary cutaneous amyloidoses, such as macular and lichenoid amyloidosis, affect the skin.
- The exact pathogenesis of primary cutaneous amyloidosis remains incompletely understood.
Purpose of the Study:
- To investigate the sequential process of amyloid formation in primary cutaneous amyloidoses.
- To identify the cellular origin and precursors of amyloid deposits in skin lesions.
- To elucidate the relationship between fibroblasts, collagen, and amyloid deposition.
Main Methods:
- Biopsies of clinically and histologically typical skin lesions of macular and lichenoid amyloidoses were obtained.
- Rebiopsies were performed at intervals of 2 to 16 weeks to track amyloid development.
- Electron microscopy was utilized to examine the ultrastructural changes during amyloidogenesis.
Main Results:
- Initially, fibroblasts discharged a proteinaceous substance containing fine filaments, originating from the rough endoplasmic reticulum.
- Typical amyloid filaments emerged within and around this substance, with collagen fibrils admixed in some areas.
- Amorphous amyloid substance was observed adjacent to basal laminae, and no plasma cells were found in amyloid foci. Amyloid was absent in nonepithelialized wounds.
Conclusions:
- Abnormal dermal fibroblasts are implicated in producing amyloid precursors in primary cutaneous amyloidoses.
- The epidermis may influence the process of amyloid precursor production by fibroblasts.
- The findings suggest a fibroblast-driven mechanism for amyloid deposition in the skin, potentially modulated by epidermal factors.