Abstract
Purpose::
Primary open angle glaucoma is characterized by increased outflow resistance in the trabecular meshwork (TM). Previous morphological investigations have shown an increased cellular senescence. One growth factor known to increase cellular senescence is Transforming Growth Factor- beta2 (TGF-ß2). This growth factor is increased in nearly half of POAG patients. The goal of this study was to investigate whether TGF-ß2 induces cellular senescence in TM cells.
Methods::
Cultured TM cells from 5 donors, passage 3-5 were exposed to 1.0 ng/ml TGF-ß2 for 12, 24 and 48 hours. After treatment cells were kept for 72 h under serum free conditions. Cellular senescence was investigated by expression of senescence associated beta- galactosidase (ß-gal) staining. The age related genes ApoJ/clusterin, CTGF and FN were examined by real time PCR. Furthermore cellular signalling using p21, p16, and pRb antibodies was performed
Results::
Treatment of TM cells for 24 and 48 hours markedly increased the number of ß-gal positive TM cells (Co = 3,5 % +/- 0.6; 12 hours = 2,7 % +/- 1.4; 24 hours = 26,6 +/- 4.8; 48 hours = 33,7 % +/- 9,4) and the expression of SA genes ApoJ/ clusterin (Co = 100; 12 hours = 145,7 % +/- 12,4; 24 hours = 223,6 +/- 24.8; 48 hours = 233,7 % +/- 10,5), CTGF (Co = 100; 12 hours = 182,7 % +/- 23,4; 24 hours = 254,6 +/- 54.8; 48 hours = 238,7 % +/- 29,4), and FN (Co = 100; 12 hours = 221,7 % +/- 43.4; 24 hours = 434,6 +/- 4.8; 48 hours = 398,7 % +/- 29,4). Cellular senescence was accompanied by increased phosphorylation of p21 and hypophosphorylation of th Rb gene, whereas p16 was not influenced.
Conclusions::
Our in vitro experiments clearly show a TGF-ß2 induced cellular senescence of TM cells. Therefore targeting cellular events leading to senescence of the TM coluld help to lower age related changes of the TM
Keywords: aging • trabecular meshwork • growth factors/growth factor receptors