Expression changes of transforming growth factor-β1 and fibronectin in bovine trabecular meshwork cells cultured by iris pigment particles

Background

Pigmentary glaucoma and pseudoexfoliation glaucoma are characterized by pigment dispersion in trabecular meshwork, and the dipersitional pigment probably contributes to the resistance of aqueous outflow pathway, irreversible damage of the trabecular meshwork and the remodeling abnormality of extracellular matrix.Researches determined that contents of transforming growth factor-β (TGF-β) in the aqueous humor are increased in glaucomatous eyes.However, the effects of TGF-β and fibronectin (FN) in the trabecular meshwork cells (TMCs) acted by iris pigmentary particles still are not elucidated.

Objective

This study was to investigate the effects of iris pigment particles on TGF-β₁ and FN expression in bovine TMCs (BTMCs) cultured in vitro.

Methods

BTMCs were cultured in vitro by explant culture method and identified by morphological evaluation.The third generation of BTMCs were divided into normal control group and pigment group, and 100 μl PBS and 100 μl iris pigment suspension (final concentration of 1×10⁷ particles/ml) were added into the medium for 24 hours, respectively.The expressions of TGF-β₁ mRNA, FN mRNA and their proteins in the BTMCs were assayed by real-time fluorescence quantitative PCR and ELISA, respectively.

Results

Cultured cells grew well and showed the fusiform, polygon and dendritic like in shape, with pigmented and round nuclei.The relative expression levels of TGF-β₁ mRNA and FN mRNA in the cells were 2.98±0.27 and 0.36±0.10 in the iris pigment group, which were significantly higher than 1.00±0.00 and 1.00±0.00 in the normal control group (t=12.68, 10.60, both at P=0.00). The concentrations of TGF-β₁ protein and FN protein in the cell suspension were (156.60±9.74)ng/L and (59.29±15.79)mg/ml in the iris pigment group, showing significant differences in comparison with (65.46±14.24)ng/L and (102.10±12.14)mg/ml in the normal control group (t=9.15, P=0.00; t=3.72, P=0.02).

Conclusions

The expression of TGF-β₁ is up-regulated and that of FN is down-regulated in BTMCs cultured by iris pigment, inferring that TGF-β₁ and FN participate in the pathogenesis and development of pigmentary and pseudoexfoliation glaucoma.

Glaucoma; Gene expression regulation; Iris/metabolism; Melanins/metabolism; Trabecular meshwork/metabolism; Transforming growth factor beta1/metabolism; Fibronectin; Cells, cultured