THE LENS INFLUENCES AQUEOUS-HUMOR LEVELS OF TRANSFORMING GROWTH-FACTOR-BETA-2

Background: Transforming growth factor-beta 2 (TGF-beta 2) is a plurip otent cytokine which has been suggested to play a number of roles in o cular physiologic and pathologic states. Intraocular fluid (IOF) level s of TGF-beta 2 are quite high. Although the sources of ocular TGF-bet a are not completely defined, the retinal pigment epithelium, the epit helium of the ciliary body and trabecular meshwork cells all secrete i t. In this study we utilized canine lens and rabbit ciliary pigmented epithelial cell cultures to quantitate the in vitro secretion of TGF-b eta 2. In addition, the effects of aphakia or the presence of cataract ous lenses on IOF TGF-beta 2 levels were determined. Methods: Lens and ciliary body epithelial cell culture supernatants and aqueous humors were assayed for total TGF-beta 2 levels by ELISA and bioassay. Result s: TGF-beta 2 accumulated in the media bathing lens epithelial cell cu ltures (0.7 +/- 0,03 ng/ml at day 2) and ciliary pigmented epithelial cell cultures (0.8 +/- 0.06 ng/ml at day 2) in a time-dependent manner . Surprisingly, aqueous humor from aphakic rabbit eyes contained signi ficantly higher levels of TGF-beta 2 than their contralateral phakic c ontrols. Furthermore, aqueous humor from canine eyes with cataracts al so contained significantly higher levels of TGF-beta 2 than normal eye s. Conclusions: These results suggest that the lens secretes TGF-beta 2 and that the presence and status of the lens may influence IOF TGF-b eta 2 levels.