Effect of tTG inhibitor on the expression of FN and Col-IV induced by TGF-β₂ in human lens epithelial cells

Background: Our previous research and other reports disclosed that the expression of tissue transglutaminase (tTG) in lens epithelial cells (LECs) of patients with cataract is enhanced, indicating tTG is related to formation of posterior capsule opacification (PCO). Objective: Present study is to observe the effect of tTG specific inhibitor monodansyl-cadaverineon(MDC) on the expression of fibronectin (FN) and collagen IV(Col-IV) induced by TGF-β₂ in human LECs. Methods: HLE-B3 was cultured in vitro in DMEM containing 10% fetal bovine serum and then were divided into 5 groups. The free-serum culture was used as normal control group. Free-serum culture containing 10 μg/L TGF-β₂ was utilized as treatment group. 10 μg/L TGF-β₂ plused 100 μmol/L, 200 μmol/L and 400 μmol/L MDC respectively in different concentrations as MDC-treatment group. Semiquantitative RT-PCR was used to assay the expression of tTG, FN and Col-IV in HLE-B3. A(tTG/β-actin), A(FN/β-actin) and A(Col-IV/β-actin) was calculated separately as the detecting indexes. Results: tTG, FN and Col-IV were positively expressed in cultured HLE-B3. The expression levels of tTG, FN and Col-IV in HLE-B3 were remarkably increased in the group with 10 μg/L TGF-β₂ compared with normal control group (t = 33.95, P < 0.01; t = 38.24, P < 0.01; t = 13.48, P < 0.01). The expression levels of FN and Col-IV were gradually declined in 100,200 and 400 μmol/L MDC groups in comparison with TGF-μ₂ treatment(P <0.01). The significant differences were also found in the expressions of FN and Col-IV in HLE-B3 among 100,200 and 400 μmol/L MDC groups (P < 0.01). Conclusion: MDC inhibits the expression of FN and Col-IV induced by TGF-β₂ in human LECs at a concentration-dependent manner. tTG may be involved in the formation of posterior capsule opacification through up-regulating the expressions of FN and Col-IV in human LECs.