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Dermal extracellular matrix in cutaneous leprosy lesions
S L Antunes1, M E Gallo, S M de Almeida
1Laboratory of Leprosy, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil. santunes@gene.dbbm.fiocruz.br
Abstract:
Thirty-eight biopsies of cutaneous lesions from leprosy patients [borderline tuberculoid (BT) 14, borderline lepromatous (BL) 18, lepromatous (LL) 6] were processed for staining of some extracellular matrix (ECM) components (collagen, proteoglycans, elastic fibers and fibronectin). Specific histological staining and the indirect immunofluorescence method with antibodies to collagen and fibronectin were utilized. The ECM of the normal dermis was strikingly modified in the inflammatory infiltrate. By Gomori's reticulin and anti-fibronectin immunostaining, replacement of the dense interlaced collagen fibers with a reticular mesh was observed in the infiltrate. The immunoreactivity obtained with anti-type I and anti-type III collagens showed positive fibrils and a lumpy pattern in the lepromatous and tuberculoid lesions with a higher amount in the lepromatous lesions. The lack of clear-cut boundaries between the normal dermis and the inflammatory infiltrate in the lepromatous (BL, LL) lesions was correlated with the blurred limits of the clinical lesions of this pole of the leprosy spectrum. Absence of elastic fibers in the infiltrate was a constant finding, and fuchsin-positive microfibrils were found in some infiltrates. The clear zone of lepromatous lesions was devoid of oxytalan fibers. Elaunin fiber rings around sweat gland acini were present even when the leprosy infiltrate was seen enveloping them. The original ECM is replaced by a newly assembled one, which is suited for the dynamic nature of the inflammatory process. The trophic effects of the ECM upon the cutaneous epithelial structures are modified so that atrophy and late degeneration ensues. These ECM modifications contribute, therefore, to the biological alterations of the skin functions in leprosy.
Insights
Leprosy alters the skin's extracellular matrix (ECM), replacing normal collagen and elastic fibers with a new structure. These changes impact skin function, leading to atrophy and degeneration in leprosy lesions.
Area of Science:
- Dermatopathology
- Extracellular Matrix Biology
- Leprosy Research
Background:
- Leprosy significantly affects skin structure and function.
- The extracellular matrix (ECM) plays a crucial role in maintaining dermal integrity and supporting cutaneous structures.
Purpose of the Study:
- To investigate the alterations in specific extracellular matrix components within cutaneous lesions of leprosy patients.
- To correlate these ECM changes with the different forms of leprosy and their clinical manifestations.
Main Methods:
- Histological staining and indirect immunofluorescence were used to analyze ECM components (collagen, proteoglycans, elastic fibers, fibronectin) in 38 leprosy biopsies.
- Patients included borderline tuberculoid (BT), borderline lepromatous (BL), and lepromatous (LL) forms.
Main Results:
- The inflammatory infiltrate in leprosy lesions showed a modified ECM, with replacement of dense collagen by a reticular mesh.
- Absence of elastic fibers within the infiltrate was a consistent finding.
- Lepromatous (BL, LL) lesions exhibited blurred boundaries correlating with indistinct clinical lesion limits, and showed higher amounts of type I and III collagen fibrils.
Conclusions:
- Leprosy induces significant remodeling of the cutaneous ECM, creating a new matrix suited for the inflammatory process.
- These ECM modifications disrupt trophic support to epithelial structures, leading to skin atrophy and degeneration.
- Altered ECM contributes to the biological dysfunction of the skin in leprosy.