Effect of fibrostatin C, an inhibitor of prolyl 4-hydroxylase, on collagen secretion by human Tenon's capsule fibroblasts in vitro.
OBJECTIVE
To investigate the effect of fibrostatin C, a prolyl 4-hydroxylase (PH) inhibitor produced by Streptomyces catenulae subsp. griseospora, on type I collagen secretion by human Tenon's capsule fibroblasts (TCFs) in vitro, as an indication of the potential therapeutic efficacy of this compound in antifibrotic therapy after glaucoma filtering surgery.


METHODS
The concentrations of type II procollagen COOH-terminal peptide (PIP) in culture medium or cell lysate were determined by immunoassays. For comparison with its effect on PIP secretion, we determined the effects of the agent on the secretion of other peptides, including laminin, vitronectin receptor, and a metalloproteinase inhibitor. The expression of collagens I and III, fibronectin, and PH by TCFs was examined by immunohistochemistry, and cellular ultrastructure was evaluated by transmission electron microscopy.


RESULTS
Fibrostatin C (50 microM) significantly reduced the concentration of PIP in culture medium and increased its concentration in the cell lysate in a dose-dependent manner, but it had no effect on the secretion of other peptides. Cell viability and proliferation were not affected by fibrostatin C. Fibrostatin C also increased the number of cytoplasmic granules immunoreactive with antibodies to collagen I or III, but had no effect on fibronectin or PH immunoreactivity. Ultrastructurally, cisternae of the endoplasmic reticulum were dilated in fibrostatin C-treated TCFs, consistent with the retention of underhydroxylated collagen precursors in this organelle.


CONCLUSIONS
Fibrostatin C inhibits the secretion of type I collagen by cultured TCFs. This agent may thus prove therapeutically beneficial for inhibiting the excess fibrosis in the wound of filtering surgery.
Saika
S
S
Department of Ophthalmology, Wakayama Medical College, Japan.
Ooshima
A
A
Yamanaka
O
O
Okada
Y
Y
Tanaka
S
S
Ohnishi
Y
Y
D000368:Aged; D018929:Cell Culture Techniques; D002455:Cell Division / Q000187:drug effects; D003094:Collagen / Q000187:drug effects / Q000378:metabolism*; D003238:Connective Tissue / Q000187:drug effects / Q000378:metabolism*; D003239:Connective Tissue Cells; D003545:Cysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D018463:Filtering Surgery / Q000009:adverse effects; D005901:Glaucoma / Q000473:pathology / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009285:Naphthoquinones / Q000494:pharmacology*; D011393:Procollagen-Proline Dioxygenase / Q000037:antagonists & inhibitors*; D014945:Wound Healing / Q000187:drug effects
D004791:Enzyme Inhibitors; D009285:Naphthoquinones; D003094:Collagen; C058033:fibrostatin C; D011393:Procollagen-Proline Dioxygenase; D003545:Cysteine