Active transforming growth factor-β2 in the aqueous humor of posterior polymorphous corneal dystrophy patients

TGF-β-Mediated Modulation of Cell-Cell Interactions in Postconfluent Maturing Corneal Endothelial Cells

Purpose

Transforming growth factor-beta (TGF-β) is known to influence many cell functions. In the corneal endothelium, TGF-β1 exerts contextual effects, promoting endothelial–mesenchymal transition in proliferating cells and enhancing barrier integrity in early confluent maturing cells. Herein, we studied how TGF-β isoforms participate in the formation of corneal endothelial intercellular junctions.

Methods

Corneal endothelial cells (CECs) were cultured using a two-phase media approach. When CECs reached confluence, the proliferation medium was replaced with maturation medium, which was supplemented or not with TGF-β isoforms. The cell morphology (circularity index), intercellular junction protein expression, trans-endothelial electrical resistance (TEER), and permeability of 7-day postconfluent CECs were assessed. Gene transcription and signaling pathways that were activated following maturation in the presence of TGF-β2 were also studied. The beneficial effect of TGF-β2 on CEC maturation was evaluated using ex vivo corneas mounted on a corneal bioreactor.

Results

The results showed increases in circularity index, membrane localization of junction-related proteins, and TEER when TGF-β isoforms were individually added during the maturation phase, and TGF-β2 was the most effective isoform. Gene profiling revealed an increase in extracellular matrix-related gene expression. In ex vivo cell adhesion experiments, CECs that were matured in the presence of TGF-β2 had a higher circularity index and cell density and exhibited cell membrane-localized junction-related protein expression at earlier time points.

Conclusions

These results suggest that TGF-β2 can strengthen cell–cell and cell–substrate adhesion, which accelerates barrier integrity establishment and thus enhances CEC functionality.

PTEN Inhibition Accelerates Corneal Endothelial Wound Healing through Increased Endothelial Cell Division and Migration

Purpose

To investigate the role of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) in the regulation of corneal endothelial cell (CECs) focusing on proliferation and migration, and to further evaluate the application of PTEN inhibitors in the treatment of corneal endothelial dysfunction in a rat model.

Methods

Expression of PTEN in human and rat corneal endothelium was determined by immunocytochemistry, western blotting, and ELISA. A small molecular inhibitor of PTEN, bpV(pic), was applied in the culture of human CEC cell line B4G12 and organ-cultured rat cornea in the presence of transforming growth factor beta 2 (TGF-β2). Cell cycle status was detected by flow cytometry and BrdU staining. Subcellular localization for endogenous p27Kip1 was detected by immunocytochemistry and western blotting. Moreover, exogenous transfected YFP-p27Kip1 was observed under a fluorescent microscope. Cell migration was examined with a wound scratch model and transwell invasion assay. Finally, bpV(pic) was intracamerally injected in a rat corneal endothelial injury model. The wound healing process was evaluated by slit lamp biomicroscopy, optical coherence tomography, histological and scanning electron microscope examination.

Results

The expression of PTEN in human corneal endothelium was higher compared with rat, which we speculate was mostly responsible for the relatively less proliferation capacity of human CEC than rat. PTEN inhibition by bpV(pic) could reverse TGF-β2-induced CEC G1-arrest by alleviating p27Kip1 nuclear accumulation and decreasing total p27Kip1 expression. In addition, bpV(pic) promoted CEC migration, which acted synergistically with TGF-β2. Finally, intracameral injection of bpV(pic) could promote corneal endothelial wound healing in a rat model.

Conclusions

Our study provided experimental basis for the development of therapeutic agent targeting on PTEN for the treatment of corneal endothelial dysfunction.

Multiple cytokine analyses of aqueous humor from the patients with retinitis pigmentosa

PURPOSE

Cataracts are the most common eye complications of retinitis pigmentosa (RP). This study aimed to investigate the cytokine profiles of the aqueous humor of RP with cataracts.

METHODS

The aqueous humor was collected from RP eyes with cataract (RP group, n = 20) and age-related cataract eyes (ARC group, n = 20) during cataract surgery. The levels of 37 mediators were measured with multiplex fluorescent bead-based immunoassay and compared across groups. The correlation among chemokines, growth factors, and cytokines was analyzed with Spearman's rank correlation coefficient.

RESULTS

Twelve cytokines (IL-1α, IL-1β, IL-4, IL-10, TNF-α, IFN-γ, EGF, GM-CSF, PDGF-AB/BB, TGF-α, BMP-9, and E-selection) were below the limit of detection, and the detection rate of IL-6 was significantly higher in RP group than in the ARC group (P < 0.01). Compared with those in the control group, the aqueous humor levels of monocyte chemoattractant protein-1 (MCP-1), interleukin-(IL-)8, interferon gamma-induced protein (IP)-10, hepatocyte growth factor (HGF), platelet-derived growth factor AA (PDGF-AA), matrix metalloproteinase-2 (MMP-2), MMP3, MMP-7, MMP-8, plasminogen activator inhibitor-1 (PAI-1), and thrombospondin-2 (TSP-2) in the RP group increased significantly (P < 0.01). A lower level of BMP-4 in the aqueous humor was observed in the RP patients than in the controls (P < 0.05).

CONCLUSIONS

Significantly increased levels of PDGF-AA, MMP2, MMP3, MMP-7, MMP-8, PAI-1, and TSP-2 and lower levels of BMP-4 were found in the aqueous humor of RP patients. This result indicates a disturbance of the extracellular matrix (ECM) and cytokines in RP patients and suggests a possible role of these cytokines in the pathogenesis of capsular contraction syndrome (CCS) in RP patients.