Curvicircular intracytoplasmic membranous structures in keratinocytes of pemphigus foliaceus

Area of Science:

• Dermatology
• Cell Biology
• Immunology

Background:

• Pemphigus foliaceus (PF) is an autoimmune blistering disease affecting keratinocyte adhesion.
• The precise mechanism of acantholysis in PF remains debated, particularly its initiation.
• Distinguishing PF from pemphigus vulgaris (PV) at the ultrastructural level is crucial.

Purpose of the Study:

• To investigate the ultrastructural basis of acantholysis in pemphigus foliaceus.
• To compare the cellular changes in PF with those observed in pemphigus vulgaris.
• To elucidate the role of specific cellular structures in the pathogenesis of PF.

Main Methods:

• Transmission electron microscopy (TEM) of skin lesions from PF and PV patients.
• Immunoelectron microscopy (IEM) using antibodies against desmoglein, plakoglobin, connexin 43, and IgG.
• Analysis of keratinocyte ultrastructure, including desmosomes and gap junctions.

Main Results:

• Intracytoplasmic curvicircular membranous bodies (60-70 nm wide, 4 electron-dense layers) were found in PF keratinocytes but not in PV.
• These bodies were continuous with intact desmosomes and gap junctions and labeled for desmoglein, plakoglobin, connexin 43, and IgG.
• Desmosome splitting was seldom observed in PF, unlike the dissolution of intercellular desmoglea seen in PV.

Conclusions:

• Curvicircular bodies in PF are likely internalized desmosomes and gap junctions.
• Internalization of these structures weakens cell-to-cell adhesion, initiating acantholysis in PF.
• This mechanism differs from PV, where desmoglea dissolution is the primary event.