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Extracellular matrix components in a case of retrocorneal membrane associated with syphilitic interstitial keratitis
R Kawaguchi1, S Saika, M Wakayama
1Second Department of Ophthalmology, Ohashi Hospital, Toho University School of Medicine, Tokyo, Japan.
Purpose:
A web-like retrocorneal membrane (RCM) is an uncommon complication of chronic syphilitic interstitial keratitis. Extracellular matrix components have not yet been defined in this structure, although previous histologic examinations have suggested the presence of collagen. We examined the presence and distribution of extracellular matrix components in a patient with an RCM.
Methods:
A specimen of the opaque cornea affected by syphilitic interstitial keratitis with RCM formation was obtained during penetrating keratoplasty in a 62-year-old woman and was evaluated by histology, immunohistochemistry, and scanning electron microscopy (SEM). Antibodies against collagen types I, III, and IV; fibronectin; vimentin; alpha-smooth muscle actin (alpha-SMA); heat shock protein 47 (Hsp 47); proliferating cell nuclear antigen (PCNA); and Ki67 were used.
Results:
Histologic analysis detected multiple concentric, acellular layers positive for collagen types I, III, and IV. The corneal endothelial cells (CECs) were positive for vimentin, collagen I, fibronectin, and Hsp 47 but not for alpha-SMA. Furthermore, the CECs were negative for PCNA and Ki67, indicating that they were not proliferating. SEM revealed the RCM was covered by CECs with a fibroblastic appearance.
Conclusion:
RCM associated with syphilitic interstitial keratitis contained collagen types I, III, and IV and fibroblast-like CECs. These CECs may secrete the extracellular matrix components found in the RCM. Hsp 47 up-regulation in the CECs may play an important role in RCM formation. These findings provide further insights into the phenotypic modulation of CECs.
Insights
Retrocorneal membranes (RCM) in syphilitic keratitis contain collagen and fibroblast-like corneal endothelial cells (CECs). These CECs may produce RCM components, with heat shock protein 47 playing a key role.
Area of Science:
- Ophthalmology
- Cell Biology
- Extracellular Matrix Research
Background:
- Syphilitic interstitial keratitis can lead to uncommon web-like retrocorneal membranes (RCM).
- The extracellular matrix composition of RCM has not been fully defined.
- Previous studies suggested collagen presence in RCM.
Observation:
- Histology revealed concentric, acellular layers containing collagen types I, III, and IV.
- Corneal endothelial cells (CECs) expressed vimentin, collagen I, fibronectin, and heat shock protein 47 (Hsp 47).
- CECs did not show proliferation markers (PCNA, Ki67) or alpha-smooth muscle actin (alpha-SMA).
Findings:
- RCM associated with syphilitic keratitis is composed of collagen types I, III, and IV.
- CECs exhibit a fibroblastic phenotype and express matrix proteins.
- Hsp 47 upregulation in CECs is implicated in RCM formation.
Implications:
- CECs may be responsible for secreting extracellular matrix components in RCM.
- These findings enhance understanding of CEC phenotypic modulation in disease.
- This research provides insights into the pathogenesis of syphilitic interstitial keratitis complications.