TGF-ß1 Induces Interlukin-11 Expression and Pro-Fibrotic Effect by DNA Demethylation in Subconjunctival Fibroblasts.

Objective: To assess Interlukin-11 (IL11) expression in the tears of patients after filtration surgery and to find out its pro-transdifferentiational and pro-fibrotic functions and mechanisms on subconjunctival human Tenon's capsule fibroblasts (HTFs) induced by transforming growth factor beta1 (TGF-ß1). Methods: Tears were collected from glaucoma patients with or without filtration surgery. The expression of IL11 in tears was examined by enzyme-linked immunosorbent assay. Primary HTFs were prepared as an expansion culture of human Tenon's explants from patients undergoing cataract surgery. TGF-ß1 and IL11 were used to stimulate the cultured HTFs. Quantitative RT-PCR and western blot analyzed the roles of TGF-ß1 in IL11 and DNA methyltransferase (DNMT) expression and the effects of IL11 on collagen-1A1 and α-smooth muscle actin expression. The effects of IL11 on human HTFs' migration were tested via the scratch-wound assay. MassARRAY platform of Sequenom was applied for analyzing the quantitative methylation of the IL11 promoter region. Result: Our data presented significantly high levels of IL11 in the tears of patients who underwent filtration surgery with uncontrolled intraocular pressure (IOP) compared with those who underwent filtration surgery with controlled IOP. The up-regulation of IL11 was related to TGF-ß1. We also found that TGF-ß induced IL11 up-regulation in the HTFs, which activates the HTFs and enhanced the translation of the pro-fibrotic protein expression. This is correlated with inhibiting the activity and expression of DNMTs and demethylating the IL11 promoter. Therefore, IL11 may be an ideal target to be regulated to control the filtering pathway scar formation.

5-Aza-2'-deoxycytidine induces human Tenon's capsule fibroblasts differentiation and fibrosis by up-regulating TGF-ß type I receptor.

The principle reason of high failure rate of glaucoma filtration surgery is the loss of filtration function caused by postoperative scar formation. We investigated the effects of 5-aza-2'-deoxycytidine (5-Aza-dc), a DNA methyltransferases inhibitor, on human Tenon's capsule fibroblasts (HTFs) differentiation and fibrosis and its mechanism of action, especially in relation to transforming growth factor (TGF)-ß1 signaling. TGF-ß1 was used to induce differentiation of cultured HTFs. 5-Aza-dc suppressed DNA methyltransferases (DNMTs) activity 6 h after treatment with a course corresponding to that of TGF-ß1-induced reduction of DNMT activity without affecting cell viability as measured by Cell Counting Kit-8 assay. 5-Aza-dc also reduced DNMT1 and DNMT3a protein expression from 24 to 48 h. HTFs migration evaluated by scratch-wound assay were significantly increased 24 h after 5-Aza-dc treatment, a time course similar to that of TGF-ß1. Treatment with 5-Aza-dc significantly increased the mRNA and protein levels of α-smooth muscle actin (α-SMA), collagen-1A1 (Col1A1), fibronectin (FN) and TGF-ß type I receptor (TGFßRI). Furthermore, the effects of 5-Aza-dc on DNMT activity suppression, cell migration, and fibrosis were all reversed by a TGFßRI inhibitor- SB-431542. Meanwhile, knockdown of DNMT1 upregulated TGFßRI expression and had the same fibrosis-inducing effect in HTFs, which was also inhibited by SB-431542. Thus, the results indicate that DNA hypomethylation induces HTFs differentiation and fibrosis through up-regulation of TGFßRI. DNA methylation status plays an important role in subconjunctival wound healing.

Overexpression of ALK5 Induces Human Tenon's Capsule Fibroblasts Transdifferentiation and Fibrosis In Vitro.

PURPOSE: To investigate the involvement of activin receptor-like kinase 5 (ALK5) in human Tenon's capsule fibroblasts (HTFs) transdifferentiation and fibrosis. METHODS: (1) Cultured HTFs were treated with transforming growth factor beta 1 (TGF-ß1) at different concentrations for different durations, mRNA expression of ALK5 and plasminogen activator inhibitor-1 (PAI-1) was measured by quantitative polymerase chain reaction (PCR) while protein expression of ALK5, α-smooth muscle actin (α-SMA), and extracellular matrix deposition including fibronectin (FN) and collagen I (Col1) was assessed by western blot. HTFs with or without TGF-ß1 were also treated with an ALK5 activity inhibitor, SB-431542, and fibrosis-related genes were assessed. (2) HTFs were transduced with ALK5 lentivirus (ALK5-OE group) or empty lentivirus (NC-OE) with or without the treatment of SB-431542. Protein expression of ALK5, α-SMA, FN, and Col1 was evaluated. (3) HTFs in the ALK5-OE group and NC-OE group were subjected to a scratch-wound assay and their migratory activities assessed. RESULTS: (1) TGF-ß1, in a concentration-dependent manner, upregulated ALK5 and PAI-1 expressions in the HTFs, which peaked between 24 and 36 h. These changes were associated with increases in protein levels of FN, Col1, and α-SMA. These TGF-ß1 effects were blocked by the ALK5 inhibitor SB-431542. (2) Similarly, overexpression of ALK5 by lentiviral vector significantly increased protein expression of α-SMA, FN, and Col1. Addition of TGF-ß1 to the ALK5-OE cells did not produce additional expression of any of the marker proteins. The upregulation of extracellular matrix and α-SMA can be reduced by SB-431542. (3) In ALK5-OE group, HTFs migration was significantly increased compared with normal control and TGF-ß1 could still promote ALK5-OE cells migration. CONCLUSIONS: Our findings suggest that ALK5 is an important mediator of HTFs fibrosis. ALK5 is a potential therapeutic target to suppress scar formation after filtration surgery.

Angiotensin II as a morphogenic cytokine stimulating fibrogenesis of human tenon's capsule fibroblasts.

PURPOSE: To examine the expression of Angiotensin II (Ang II) and its type I, and type II receptors (AT1R, AT2R) in rabbit Tenon's capsule fibroblasts after trabeculectomy, and to investigate the effects of Ang II on cultured human Tenon's capsule fibroblasts (HTFs) proliferation, migration, phenotype transition, and extracellular matrix (ECM) synthesis. METHODS: In the rabbit, expression of Ang II, AT1R, and AT2R in Tenon's capsule fibroblasts of eyes after trabeculectomy was evaluated by immunohistochemistry. Ang II levels in aqueous humor and plasma were assessed by ELISA. Cultured HTFs, obtained from patients undergoing cataract surgery, were treated with Ang II, TGF-ß1, or vehicle control. Cell proliferation and migration were evaluated by Cell Counting Kit-8 and Transwell assay, and wound scratch assay, respectively. Protein expressions of α-smooth muscle actin (α-SMA) and fibronectin (FN) were measured by Western blot and immunofluorescence. Messenger RNA expressions of α-SMA and FN were measured by real-time PCR. RESULTS: In the rabbit, the expression of Ang II and AT1R increased from 1 day after surgery while AT2R increased from 7 days. In cultured HTFs, Ang II promoted cell proliferation and migration significantly (P < 0.05). Interestingly, the effect of 10(-7) M Ang II was more prominent than higher concentrations (10(-5) M; P < 0.05). Ang II also markedly induced the expression of α-SMA and FN, suggesting a phenotypic transition to myofibroblasts. CONCLUSIONS: Our results show that trabeculectomy alter the levels of Ang II and its receptors in Tenon's capsule fibroblasts, and that Ang II increase HTFs proliferation, migration, and phenotype transition, suggesting that Ang II may play a role in wound healing after trabeculectomy.