Characterization and functional performance of a commercial human conjunctival epithelial cell line.

The conjunctiva is a complex tissue that covers the eye beginning at the corneal limbus and extending over the inner surfaces of the eyelids. Due to its important functions in maintaining the health of the ocular surface, adequate in vitro models of conjunctival structure and function are essential to understand its roll in different pathologies. Because there is scarcity of human conjunctival tissue that can be used in research, cell lines are often the only option for initial studies. An immortalized human conjunctival epithelial cell (IM-HConEpiC) line is now commercially available; however, it is not very well characterized. In this study, we have developed a new protocol to culture these cells without the use of collagen-coated culture surfaces, but with a defined cell culture medium. We characterized IM-HConEpiCs cultured under these conditions and corroborated that the cells maintained a conjunctival epithelial phenotype, including acidic and neutral mucins, junctional proteins E-cadherin and zonula occludens 1, and expression of CK8 and CK19, among others. In addition, we analyzed the response to oxidative stress and inflammatory stimuli and found that IM-HConEpiCs respond as expected for conjunctival epithelial tissue. For instance, cells exposed to oxidative stress increased the production of reactive oxygen species, and that increase was blocked in the presence of an antioxidant agent. In addition, after stimulation with TNF-α, IM-HConEpiCs significantly increased the production of IL-1ß, IL-6, IL-8, and IP-10. Therefore, with this study we conclude that IM-HConEpiCs can be a useful tool in functional studies to determine the response of the conjunctiva to pathological conditions and/or to test new therapeutic strategies.

Olive Pomace Phenolic Compounds Stability and Safety Evaluation: From Raw Material to Future Ophthalmic Applications.

Nowadays, increasing interest in olive pomace (OP) valorization aims to improve olive's industry sustainability. Interestingly, several studies propose a high-value application for OP extracts containing its main phenolic compounds, hydroxytyrosol and oleuropein, as therapy for ocular surface diseases. In this work, the stability and accessibility of OP total phenolic and flavonoid content, main representative compounds, and antioxidant activity were assessed under different pretreatment conditions. Among them, lyophilization and supercritical CO2 extraction were found to increase significantly most responses measured in the produced extracts. Two selected extracts (CONV and OPT3) were obtained by different techniques (conventional and pressurized liquid extraction); Their aqueous solutions were characterized by HPLC-DAD-MS/MS. Additionally, their safety and stability were evaluated according to EMA requirements towards their approval as ophthalmic products: their genotoxic effect on ocular surface cells and their 6-months storage stability at 4 different temperature/moisture conditions (CPMP/ICH/2736/99), together with pure hydroxytyrosol and oleuropein solutions. The concentration of hydroxytyrosol and oleuropein in pure or extract solutions was tracked, and possible degradation products were putatively identified by HPLC-DAD-MS/MS. Hydroxytyrosol and oleuropein had different stability as standard or extract solutions, with oleuropein also showing different degradation profile. All compounds/extracts were safe for ophthalmic use at the concentrations tested.

Olive Pomace Phenolic Compounds: From an Agro-Industrial By-Product to a Promising Ocular Surface Protection for Dry Eye Disease.

Dry eye (DED) is a prevalent disease with immune-mediated inflammation as the principal pathophysiological etiology. Olive pomace, the major by-product of the olive oil industry, is rich in high-value polyphenols. Their anti-inflammatory and immunomodulatory activities were determined on human CD4+ T cells (hTCD4+) and in a DED animal model. The viability of hTCD4+ cells isolated from peripheral blood and activated with phytohemagglutinin-M was evaluated after treatment for 48 h with an olive pomace extract (OPT3, 0.10-0.40 mg/mL) and its major compound, hydroxytyrosol (25-100 µM). Regarding the DED animal model, 100 µM hydroxytyrosol, 0.20 mg/mL OPT3, or vehicle (borate buffer) were topically administered to 14 days-desiccating stress-exposed (constant airflow/scopolamine administration) C57BL/6 mice. Tear volume, corneal fluorescein staining (CFS), CD4+, and CD8+ T cell count in lymph nodes (flow cytometry), and IP-10 and TNF-α gene expression (qRT-PCR) in the cornea, conjunctiva, and lacrimal glands were evaluated. OPT3 (0.2-0.4 mg/mL) and hydroxytyrosol (100 µM) significantly reduced hTCD4+ proliferation. In mice, both treatments reduced lacrimal gland IP-10 gene expression. OPT3 also decreased CFS, and conjunctival IP-10 and corneal TNF-α gene expression. In lymph nodes, hydroxytyrosol reduced CD3+, OPT3, and CD8+ count. Thus, a high-value application as a promising DED protection was proposed for olive pomace.

Olive Pomace Phenolic Compounds and Extracts Can Inhibit Inflammatory- and Oxidative-Related Diseases of Human Ocular Surface Epithelium.

Oxidative- and inflammatory-related ocular surface diseases have high prevalence and are an emerging issue in ophthalmology. Olive pomace (OP) is the olive oil's industry main by-product, and is potentially environmentally hazardous. Nevertheless, it contains phenolic compounds with important bioactivities, like oleuropein (OL) and hydroxytyrosol (HT). The antioxidant and anti-inflammatory effects of four OP extracts (CONV, OPT(1-3)), pure OL and HT, and mixtures thereof were screened on human corneal (HCE) and conjunctival epithelial (IM-ConjEpi) cells. CONV was conventionally extracted, while OPT(1-3) were produced by pressurized liquid extraction. Thanks to their improved activity, CONV and OPT3 (HT-enriched) were selected for dose-dependent studies. Cells were stimulated with tumor necrosis factor-α or ultraviolet-B radiation, measuring interleukin (IL)-1ß, IL-6, IL-8, and IL-17A as well as interferon γ-induced protein [IP]-10 secretion or intracellular ROS production, respectively. On HCE, both extracts and HT inhibited the secretion of most measured ILs, demonstrating a strong anti-inflammatory effect; while in IM-ConjEpi, all samples decreased IP-10 secretion. Moreover, HT, OL, and both extracts showed strong dose-dependent antioxidant activity in both cell lines. Compared with CONV, OPT3 was active at lower concentrations, demonstrating that intensified extraction techniques are selective towards targeted biomarkers. Hence, a high-value application as potential ocular surface therapy was proposed for the OP valorization.