Effect of cataract surgery on aqueous TGF-beta and lens epithelial cell proliferation

To study lens epithelial cell (LEC) regulation after experimental cataract surgery in rabbits. The effect of aqueous humor (AqH) on LECs in vitro was investigated and the AqH concentrations of basic fibroblast growth factor (bFGF) and transforming growth factor-beta (TGF-beta) were determined.

Aqueous humor was aspirated immediately before, and 1, 5, 10, 15, and 30 days after cataract surgery (n=8 each day). The effect of AqH on LEC proliferation was investigated by the incorporation of [3H]thymidine. The following concentrations were determined in AqH: bFGF, active and total TGF-beta, leukocytes, and total protein.

Aqueous humor collected after surgery triggered LEC growth on each occasion, except on (postoperative) day 30, in contrast to the effect of normal AqH. Lens epithelial cell proliferation peaked on day 1, displaying a sixfold increase. The bFGF concentration in AqH increased 6 to 10-fold after surgery and remained high throughout the experimental period. The AqH concentration of active TGF-beta decreased sevenfold 1 day after surgery. It then returned to normal levels on day 15. Total TGF-beta in postoperative AqH was twice as high as that in normal AqH on all days. Lens epithelial cell proliferation correlated with protein (r=0.685), leukocytes (r=0.565), and active TGF-beta (r=-0.418).

The stimulating effect of postoperative AqH on LEC proliferation may be caused by a reduction in the concentration of TGF-beta.