1,5-Dicaffeoylquinic acid from Pseudognaphalium affine ameliorates dry eye disease via suppression of inflammation and protection of the ocular surface.

PURPOSE: Pseudognaphalium affine (P. affine), a medicinal plant, has long been used to treat various diseases due to its astringent and vulnerary effects. These therapeutic benefits are largely attributed to high contents of phytochemicals, such as flavonoids and polyphenols, that have anti-inflammatory and tissue-protective activities. Herein, we investigated the potential of dicaffeoylquinic acids (diCQAs), polyphenols from P. affine, as a novel treatment for dry eye disease (DED). METHODS: We isolated 1,5-, 3,4-, 3,5- and 4,5-diCQAs from the P. affine methanol extract, and tested the effects of diCQA isomers in cultures of human corneal epithelial cells (CECs) under desiccating hyperosmolar stress and in two mouse models for DED: desiccating environmental stress-induced DED and the NOD.B10-H2b mouse model of ocular Sjögren's syndrome. RESULTS: Initial screening showed that, among the diCQAs, 1,5-diCQA significantly inhibited apoptosis and enhanced viability in cultures of CECs under hyperosmolar stress. Moreover, 1,5-diCQA protected CECs by promoting proliferation and downregulating inflammatory activation. Subsequent studies with two mouse models of DED revealed that topical 1,5-diCQA administration dose-dependently decreased corneal epithelial defects and increased tear production while repressing inflammatory cytokines and T cell infiltration on the ocular surface and in the lacrimal gland. 1,5-diCQA was more effective in alleviating DED, as compared with two commercially-available dry eye treatments, 0.05% cyclosporine and 0.1% sodium hyaluronate eye drops. CONCLUSIONS: Together, our results demonstrate that 1,5-diCQA isolated from P. affine ameliorates DED through protection of corneal epithelial cells and suppression of inflammation, thus suggesting a novel DED therapeutic strategy based on natural compounds.

Inhibition of Aberrant α(1,2)-Fucosylation at Ocular Surface Ameliorates Dry Eye Disease.

Fucosylation is involved in a wide range of biological processes from cellular adhesion to immune regulation. Although the upregulation of fucosylated glycans was reported in diseased corneas, its implication in ocular surface disorders remains largely unknown. In this study, we analyzed the expression of a fucosylated glycan on the ocular surface in two mouse models of dry eye disease (DED), the NOD.B10.H2b mouse model and the environmental desiccating stress model. We furthermore investigated the effects of aberrant fucosylation inhibition on the ocular surface and DED. Results demonstrated that the level of type 2 H antigen, an α(1,2)-fucosylated glycan, was highly increased in the cornea and conjunctiva both in NOD.B10.H2b mice and in BALB/c mice subjected to desiccating stress. Inhibition of α(1,2)-fucosylation by 2-deoxy-D-galactose (2-D-gal) reduced corneal epithelial defects and increased tear production in both DED models. Moreover, 2-D-gal treatment suppressed the levels of inflammatory cytokines in the ocular surface and the percentages of IFN-γ+CD4+ cells in draining lymph nodes, whereas it did not affect the number of conjunctival goblet cells, the MUC5AC level or the meibomian gland area. Together, the findings indicate that aberrant fucosylation underlies the pathogenesis of DED and may be a novel target for DED therapy.

Corneal Epithelial Toxicity after Intravitreal Methotrexate Injection for Vitreoretinal Lymphoma: Clinical and In Vitro Studies.

Methotrexate is widely used as an intraocular chemotherapy for vitreoretinal lymphoma (VRL). Although corneal toxicity has been reported in patients after intravitreal methotrexate injections, the incidence, outcome, and mechanism of the toxicity are unclear. Herein, we performed a clinical study to evaluate the incidence, predisposing factors, and treatment outcome of corneal epitheliopathy associated with intravitreal methotrexate injection. In addition, we directly investigated cytotoxic effects and mechanisms of methotrexate in cultures of human corneal epithelial cells (CECs). Medical chart reviews revealed that corneal epitheliopathy occurred in 15 eyes (22.7%, 12 patients) out of 66 eyes (45 patients) after intravitreal methotrexate injections for treatment of VRL. The use of topical anti-glaucoma medication was significantly associated with development of corneal epitheliopathy. The epitheliopathy resolved in all patients 2.4 months after onset. In culture, methotrexate decreased the survival of CECs by inducing apoptosis, increasing oxidative stress, suppressing proliferation, and upregulating inflammatory cytokines. The addition of folinic acid significantly protected the cells from the methotrexate-induced toxicity. Hence, our results suggest that care should be taken to minimize the contact of methotrexate with corneal epithelium during injection, and folic or folinic acid supplementation might be beneficial for preventing corneal complications in patients undergoing intravitreal methotrexate injections.

Anti-inflammatory protein TSG-6 secreted by activated MSCs attenuates zymosan-induced mouse peritonitis by decreasing TLR2/NF-κB signaling in resident macrophages.

Human mesenchymal stem/progenitor cells (hMSCs) repair tissues and modulate immune systems but the mechanisms are not fully understood. We demonstrated that hMSCs are activated by inflammatory signals to secrete the anti-inflammatory protein, TNF-α-stimulated gene 6 protein (TSG-6) and thereby create a negative feedback loop that reduces inflammation in zymosan-induced peritonitis. The results demonstrate for the first time that TSG-6 interacts through the CD44 receptor on resident macrophages to decrease zymosan/TLR2-mediated nuclear translocation of the NF-κB. The negative feedback loop created by MSCs through TSG-6 attenuates the inflammatory cascade that is initiated by resident macrophages and then amplified by mesothelial cells and probably other cells of the peritoneum. Because inflammation underlies many pathologic processes, including immune responses, the results may explain the beneficial effects of MSCs and TSG-6 in several disease models.