Effect of excess synthesis of extracellular matrix components by trabecular meshwork cells: possible consequence on aqueous outflow.

The extracellular matrix (ECM) of the trabecular meshwork (TM) is an important determinant of its functional properties. This study was performed to investigate whether overexpression of ECM components, laminin (LM) and collagen type IV (Col) by TM cells may play a role in the development of outflow resistance. To determine the effect of excess LM and Col expression on cell monolayer permeability, an in vitro cell culture model was used in which overexpression of the two ECM components, LM and Col, was induced by high glucose (HG) (30 mM) or 0.1 microM dexamethasone (D) in bovine and human trabecular meshwork (BTM and HTM) cells. Western blot analysis and immunofluorescence staining confirmed increased LM and Col synthesis in cells exposed to HG or D. Increased level of LM and Col protein resulted in reduced cell monolayer permeability. Transfection with antisense oligos (AS-oligos) targeted against LM or Col inhibited HG- or D-induced LM and Col gene overexpression in TM cells with concomitant increase in permeability. The AS-oligo strategy was effective in reducing LM or Col level in the TM cells in all conditions tested in this study. These findings suggest that increased LM and Col deposition in the outflow pathway may cause resistance to aqueous outflow and contribute to the development of primary open angle glaucoma (POAG).

Fibronectin overexpression inhibits trabecular meshwork cell monolayer permeability.

PURPOSE: To study whether excess synthesis of an extracellular matrix (ECM) component, fibronectin (FN), underlying the monolayer of human trabecular meshwork (HTM) cells, influences permeability. METHODS: To upregulate FN expression, HTM cells were grown in high glucose (30 mM) medium for 10 days. In parallel, cells were grown in normal (5 mM) medium as control, and two separate groups of HTM cells were grown in high glucose medium for transfection with FN antisense phosphorothioate oligonucleotides (AS-FN oligos) to modulate high glucose induced FN overexpression, or random phosphorothioate oligonucleotides (Ran oligos) as control. FN protein expression and distribution was assessed by western blot analysis and immunofluorescence microscopy. In parallel, HTM cells were grown in transwell plates in normal or high glucose medium to perform in vitro permeability (IVP) assays and to assess transelectrical resistance (TER). RESULTS: Western blot analysis showed FN expression was upregulated by 27% (p=0.018) in HTM cells grown in high glucose medium compared to cells grown in normal medium. Immunofluorescence microscopy showed intense FN immunostaining, and IVP results showed a consistent reduction in monolayer permeability (13% reduction, p=0.004) in cells grown in high glucose medium compared to cells grown in normal medium. When cells grown in high glucose medium were transfected with AS-FN oligos FN expression was reduced by 33% (p=0.009) and resulted in increased permeability to near normal levels (98+/-7% of control, p=0.01), whereas random oligos had no effect on either FN expression or IVP. TER was significantly increased across TM cell monolayers grown in high glucose compared to those grown in normal medium (143+/-11% of control, p=0.001), which was reduced when cells were transfected with AS-FN oligos (109+/-7% of control, p=0.02) whereas cells transfected with random oligos showed no change. CONCLUSIONS: Excess FN synthesis by trabecular meshwork cells may contribute to blockage in aqueous outflow associated with the development of primary angle open glaucoma (POAG).

Concomitant cavernous hemangioma and venous angioma of the orbit.

BACKGROUND: An unusual case of cavernous hemangioma coexisting with venous angioma in the ipsilateral orbit is described. CASE: A 67-year-old woman had a mass in the lower eyelid of her right eye and proptosis. Imaging examinations showed two masses connected to each other in the extraconal space of the right orbit. OBSERVATIONS: Anterior orbitotomy was performed to remove the tumors. Histopathological evaluation of the anteriorly located tumor revealed cavernous hemangioma. The posteriorly located tumor was found to be a venous angioma. Endothelial cells in both tumors showed positive immunostaining for factor VIII-related antigen and smooth muscle actin. Immunoreactivity of smooth muscle actin was more prominent in the interstitium of the posteriorly located tumor. CONCLUSION: Coexistence of cavernous hemangioma and venous angioma in the same area suggests that they are a continuum and of the same origin.

Sclerosing sweat duct carcinoma of the eyelid.

BACKGROUND: Sclerosing sweat duct carcinoma (SSDC) is a rare variant of sweat gland carcinomas. We report a case of SSDC of the eyelid. CASE: A 33-year-old woman presented with a painless, slowly enlarging nodule in her left lower eyelid. Incisional biopsy revealed proliferated ducts lined by two layers of epithelium embedded in a dense fibrous stroma. Cytologic atypia was not evident. Initial histopathological diagnosis was a syringoma or an inflammatory reaction. OBSERVATIONS: Four years after initial biopsy, the mass had enlarged slightly. Madarosis was observed thereafter. The lesion was excised completely with frozen section evaluation of the margins and repaired by a semicircular rotation flap. Microscopically, variable sized tubular structures could be seen invading the deep dermis and muscle. The final diagnosis was SSDC. CONCLUSIONS: This tumor is seldom recognized and is frequently confused with benign syringoma or inflammation. Wide and deep excisional biopsy is necessary for correct diagnosis and successful treatment.