Purpose: In congenital aniridia, not only limbal epithelial cells but also limbal stromal cells may contribute to the development of aniridia associated keratopathy (AAK). Secondary glaucoma affects 50–75% of patients with congenital aniridia, and prostaglandin analogs are commonly used for conservative treatment. This study aimed to explore the effect of travoprost on corneal limbal stromal cells from healthy (LSCs) and congenital aniridia subjects (AN-LSCs), in vitro. Materials and methods: Cells were extracted from aniridia (AN-LSCs) (n=7) and healthy donors (LSCs) (n=7). In culture, the cells were treated with travoprost at concentrations ranging from 0.039–40 μg/mL for 20 minutes. Cell viability, proliferation and migration were determined to assess the effect of travoprost on AN-LSCs and LSCs. Analysis of inflammation-, retinoic acid signaling-, and apoptosis-related genes and proteins was performed using qPCR, Western blot, and ELISA. One-way ANOVA was used to analyze cell viability and proliferation. The Mann–Whitney test was applied to compare between-group differences, while the Friedman test was used to assess within-group differences. Results: Both in LSCs and AN-LSCs, travoprost treatment at 0.078 μg/mL and higher concentrations significantly reduced cell viability (p≤0.033; p<0.001) and proliferation decreased both in LSCs and AN-LSCs at 40 μg/mL travoprost concentration (p=0.006; p=0.002). At 6 and 12 hours, 0.313 μg/mL travoprost significantly increased the migration rate of AN-LSCs (p=0.021; p=0.021). AN-LSCs displayed lower PAX6 and JNK (MAPK8) mRNA (p<0.001) but higher MMP-3, MMP-9, ADH7, FABP5 and VEGFA mRNA levels (p≤0.037) than LSCs. PTGFR and JNK mRNA levels, MMP9 and ADH7 protein levels increased significantly in AN-LSCs after 0.313 μg/mL travoprost treatment (p≤0.039), while NF-κB and ADH7 protein levels decreased significantly in LSCs using 0.313 μg/mL travoprost (p=0.039; p<0.001). Conclusions: Travoprost may affect viability, proliferation, and migration of both LSCs and AN-LSCs, with AN-LSCs exhibiting greater sensitivity than LSCs. Additionally, travoprost may regulate MMP-9 expression in AN-LSCs via the JNK signaling pathway. Furthermore, in AN-LSCs, travoprost treatment does not lead to a decrease in NF-κB and ADH7 protein levels.

Purpose: In the present study, we evaluate gene and protein expression levels in an in vitro siRNA-mediated PAX6 knockdown limbal epithelial cell (LEC) model after RA treatment. This study aims to investigate the direct effects of active RA products and their association with key regulators of the RA signaling pathway in siRNA PAX6 knockdown LECs, providing further insights into the potential role of RA signaling in AAK pathogenesis. Methods: Primary human limbal epithelial cells (LECs) were subjected to siRNA-mediated PAX6 knockdown to mimic PAX6 deletion in congenital aniridia (n = 8). Following knockdown, 0 µM, 1 µM, and 5 µM all-trans retinoic acid (RA) treatments were applied to both the siRNA PAX6 control and knockdown groups. After 48 hours of incubation, the mRNA expression levels of paired box 6 (PAX6), alcohol dehydrogenase 7 (ADH7), retinol dehydrogenase 10 (RDH10), aldehyde dehydrogenase 1 family member A1 (ALDH1A1), cytochrome P450 family 26 subfamily A member 1 (CYP26A1), retinol-binding protein 1 (RBP1), cellular retinoic acid-binding protein 2 (CRABP2), fatty acid-binding protein 5 (FABP5), retinoid X receptor alpha (RXRA), retinoid X receptor beta (RXRB), retinoic acid receptor alpha (RARA), retinoic acid receptor beta (RARB), peroxisome proliferator-activated receptor gamma (PPARG), and vascular endothelial growth factor A (VEGFA) were analyzed using qPCR. Protein expression levels were assessed using ELISA or Western blot, while cell proliferation rates were measured using the BrdU assay. Results: PAX6, ADH7, ALDH1A1, FABP5 mRNA levels and PAX6, ADH7, ALDH1A1, FABP5, PPARG2, RARB protein levels were significantly lower in the PAX6 knockdown group, than in controls (p ≤ 0.018). PPARG mRNA level was significantly higher in the PAX6 knockdown group than in controls (p = 0.012). ALDH1A1 mRNA expression was significantly downregulated using 5 µM RA treatment in the control group (p = 0.038). CYP26A1 mRNA expression was upregulated using 1 µM and 5 µM RA treatment in both the PAX6 control (p < 0.001; p < 0.001) and the PAX6 knockdown group (p = 0.001; p = 0.002). CRABP2 mRNA expression in the PAX6 knockdown group (p = 0.02) and CRABP2 protein expression in both groups were downregulated using 5 µM RA concentration (p = 0.003; p = 0.02). Protein expression of RXRA was downregulated to 5 µM RA treatment in the controls (p = 0.007). mRNA expression of RARA in the PAX6 knockdown groups (p = 0.023) and mRNA expression of RARB in both groups (p = 0.007, p < 0.001) were downregulated to 5 µM RA treatment. RARB protein expression was downregulated to 1 µM and 5 µM RA treatment (p = 0.02, p = 0.004) in the controls. VEGFA mRNA expression in PAX6 controls was upregulated using 5 µM RA (p = 0.041). Cell proliferation rate was downregulated in PAX6 knockdown groups compared to the controls and downregulated using 5 µM RA concentration only in the controls (p < 0.001, p = 0.025). Conclusions: Our results reveal a reduced proliferation rate in PAX6 knockdown LECs, along with a less pronounced downregulation of proliferation in response to increased RA concentration. Additionally, the study highlights altered expression of key regulators in the RA signaling pathway, influenced by both PAX6 activity and RA treatment. These findings suggest a potential disruption in RA-mediated cellular regulation in PAX6-deficient LECs.

Congenital aniridia is a rare genetic disorder primarily caused by pathogenic variants of the PAX6 gene. It leads to various panocular anomalies, including aniridia‐associated keratopathy (AAK). This review highlights recent insights into its pathogenesis, focusing on clinical staging, microstructural changes in the cornea and molecular dysregulation. We synthesized clinical and experimental findings from large European cohorts, integrating data on over 550 eyes. AAK severity correlates with iris malformation, secondary glaucoma and lens status. In vivo confocal microscopy reveals a reduction in subbasal nerve plexus density, altered keratocyte and endothelial morphology and an increase in Langerhans cell infiltration. RNA and miRNA microarrays, as well as RNA‐seq studies, highlight dysregulated miRNAs (such as miR‐204‐5p and miR‐138‐5p) and altered expression of PAX6 and keratocyte markers. Limbal fibroblasts show enhanced inflammatory responses and vulnerability to oxidative stress. Advanced AAK is associated with a reduced quality of life. The progression of AAK involves intricate interactions between developmental deficits, inflammation and changes in the limbal microenvironment, suggesting molecular targets for future therapies.

This study aimed to evaluate FOXC1-mediated regulatory mechanisms on gene and protein expression profiles in primary human limbal epithelial cells (pLECs) using siRNA-mediated FOXC1 knockdown under basal conditions and following lipopolysaccharide (LPS) and interleukin-1β (IL-1β)-induced inflammatory conditions. The gene expression related to inflammation, epithelial differentiation, cell proliferation and remodeling, and retinoic acid metabolism was analyzed using qPCR. Corresponding protein levels were assessed through Western blotting and ELISA. FOXC1 silencing significantly downregulated epithelial differentiation markers KRT12 and KRT13 at the mRNA and protein levels (p ≤ 0.045), whereas KRT3 and KRT19 were unaffected. Inflammatory signaling was markedly altered, with a reduced IL-6 and IL-8 mRNA expression (p ≤ 0.029), increased IL-1α expression (p ≤ 0.015), and condition-dependent changes in IL-6 and IL-8 protein secretion. CCL2 was increased at the mRNA level only (p = 0.007). VEGFA mRNA was consistently reduced (p ≤ 0.022) without corresponding protein changes, while TGF-β protein was increased under non-inflammatory and LPS conditions (p ≤ 0.011). Genes involved in retinoid metabolism, including CYP1B1, FABP5, CRABP2, RDH10, STRA6, and ALDH3A1, were significantly downregulated (p ≤ 0.037), with reduced CRABP2 and RDH10 protein levels (p ≤ 0.017) and a decreased FABP5/CRABP2 ratio under IL-1β stimulation (p = 0.006). FOXC1 knockdown affected proliferation-related genes, with decreased FOSL2 (p = 0.048) and increased MKi67 (p = 0.006). FOXC1 silencing disrupts epithelial differentiation, inflammatory signaling, retinoid metabolism, and selected proliferation-related pathways at the transcriptional level, with more selective effects on protein levels. Such changes may potentially predispose the ocular surface to lineage instability, fibrosis, and impaired regenerative capacity.

Purpose: The aim of this study was to investigate apoptosis in primary aniridia limbal stromal cells (LSCs) and to assess changes in the expression of genes and proteins associated with the apoptotic pathway in response to cobalt chloride (CoCl₂)-induced hypoxic stress, in vitro. Methods: Primary human limbal stromal cells were isolated from the limbal region of both aniridia (AN-LSCs; n = 8) and healthy (LSCs; n = 8) donors. The cells were treated with 0 µM, 50 µM, and 75 µM CoCl₂ for 48 hours. Apoptosis in each group was assessed by Flow cytometry (FC). The expression levels of apoptosis-related genes, including CASP 3/7/8/9/10, BCL2, BID, BAX, CDKN1A (p21), CDKN1B (p27), TNFα, XIAP, and BIRC5 (Survivin), were measured by qPCR. Protein level of these markers was analyzed by FC. TNFα protein expression in the supernatant was quantified using ELISA. Results: Flow cytometry analysis revealed a significantly higher apoptosis rate in AN-LSCs compared to LSCs (p < 0.0001). In AN-LSCs, treatment with 75 µM CoCl₂ further increased the apoptosis rate compared to untreated AN-LSCs (p = 0.047). BCL2 mRNA levels (p = 0.0291), Caspase-8 (p = 0.0341), Caspase-10 (p = 0.0085), Bcl-2 (p = 0.0014), XIAP (p = 0.0003) and Survivin (p = 0.0074) protein levels were significantly higher in LSCs than in AN-LSCs. Conversely, Caspase-3 (p = 0.0366), Caspase-9 (p = 0.0354), p21 (p = 0.0003), and p27 (p = 0.0164) protein levels were significantly higher in AN-LSCs than in LSCs. In LSCs, exposure to 75 µM CoCl₂ led to a reduction in BCL2 mRNA (p = 0.0102) and protein levels (p = 0.0484), accompanied by an increase in CDKN1B mRNA level (p = 0.0265). In AN-LSCs, 75 µM CoCl₂ treatment resulted in a decrease in CASP3 (p = 0.049), CASP7 (p = 0.041) and BCL2 (p = 0.0218) mRNA and Bcl-2 protein levels (p = 0.0405) and an increase of TNF-α protein levels in the cell culture supernatant (p = 0.0251). Conclusions: The apoptosis rate of LSCs from patients with congenital aniridia is higher than that of the control group, accompanied by alterations in multiple apoptosis-related markers. Additionally, CoCl₂-induced hypoxic stress further increases apoptosis in AN-LSCs and leads to changes in the expression of Caspase 3, Caspase 7, Bcl-2, and CDKN1B (p27). Further research is needed to elucidate the potential therapeutic targets in AAK, with the aim of preventing or slowing the progression of aniridia-associated keratopathy.

Purpose: To establish and comprehensively characterize immortalized limbal epithelial cell lines derived from patients with PAX6 haploinsufficiency-associated congenital aniridia, as well as from a healthy donor. These well-defined cell models provide a reliable and reproducible platform for long-term experimental studies, facilitating mechanistic investigations and the development and evaluation of novel therapeutic approaches. Methods: Primary limbal epithelial cells were isolated from biopsies of two patients with distinct PAX6 variants and from a healthy donor. Immortalization was performed by InSCREENex GmbH. The resulting cell lines were characterized using microscopy, BrdU assay, qPCR, flow cytometry, immunocytochemistry, and mRNA sequencing. Results: Immortalized aniridia and control cell lines displayed typical polygonal epithelial morphology and comparable proliferation rates. Total PAX6 mRNA and protein levels were similar among groups; however, nuclear PAX6 immunosignals were significantly reduced in aniridia-derived lines. Expression of ABCG2, TP63, FOSL2, ALDH1A1, and FABP5 showed no significant differences, except for reduced ΔNp63α protein levels in one aniridia line. mRNA sequencing detected more than 14,000 transcripts, including subsets uniquely expressed in control and aniridia-derived lines. Conclusions: Immortalized aniridia limbal epithelial cell lines preserve key epithelial characteristics and overall transcriptomic similarity to controls while exhibiting disease-relevant molecular alterations. These cell lines represent models of PAX6-associated ocular surface disease.