T helper (Th)-17 is a recently identified subtype of Th response that has been implicated in host defense and autoimmunity. We investigated whether there is evidence for a Th-17 response in human and experimental murine dry eye (DE). Gene expression in the human DE conjunctiva showed increased levels of the Th-17 inducers, interleukin (IL)-23, IL-17A, and interferon-gamma (IFN-γ). In the murine model, we found that desiccating stress increased matrix metalloproteinase-9, Th-17-associated genes (IL-6, IL-23, transforming growth factor-β1 and -2, IL-23R, IL-17R, IL-17A, retinoid-related orphan receptor-γt, and CC chemokine attractant ligand-20) and IFN-γ in cornea and conjunctiva. Furthermore, we found a significantly increased concentration of IL-17 in tears and number of IL-17-producing cells on the ocular surface. Antibody neutralization of IL-17 ameliorated experimental DE-induced corneal epithelial barrier dysfunction and decreased the expression of matrix metalloproteinases 3 and 9. Taken together, these findings suggest that IL-17 has a role in corneal epithelial barrier disruption in DE.

Experimental dry eye stimulates expression and production of IL-1beta, TNF-alpha, and MMP-9 and activates MAPK signaling pathways on the ocular surface. MAPKs are known to stimulate the production of inflammatory cytokines and MMPs, and they could play an important role in the induction of these factors that have been implicated in the pathogenesis of dry eye disease.

This study evaluated proposed molecular markers related to stem cell (SC) properties with the intention of characterizing a putative SC phenotype in human limbal epithelia. Human corneal and limbal tissues were cut in the vertical and horizontal meridians for histology, transmission electron microscopy (TEM), and immunostaining. Semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ hybridization were used to evaluate gene expression. TEM showed that the limbal basal cells were small primitive cells. Immunostaining disclosed that p63, ABCG2 and integrin α α9 were primarily expressed by the basal epithelial cells of limbus. Antibodies against integrin β β1, epidermal growth factor receptor (EGFR), K19, enolase-α α, and CD71 stained the basal cells of the limbus more brightly than the suprabasal epithelia. Integrin α α6, nestin, E-cadherin and connexin 43 did not stain the limbal basal cells, but the suprabasal epithelia of the cornea and limbus showed strong immunoreactivity. K3 and involucrin stained only corneal and limbal superficial cells. RT-PCR showed higher levels of p63, ABCG2 and integrin α α9 mRNA, but lower levels of K3, K12 and connexin 43 expressed in the limbal epithelia than the corneal epithelia. In situ hybridization showed that p63 transcripts were located in basal layer of the limbal epithelium. This work suggests that the basal epithelial cells of the limbus are p63, ABCG2 and integrin α α9 positive, and nestin, E-cadherin, connexin 43, involucrin, K3, and K12 negative, with relatively higher expression of integrin β β1, EGFR, K19, and enolase-α α. This putative SC phenotype may facilitate the identification and isolation of limbal epithelial SCs.

Purpose to compare tear cytokine and chemokine concentrations in asymptomatic control and dysfunctional tear syndrome (DTS) patients and determine the correlations between tear inflammatory mediators and clinical severity. Design Prospective observational cohort study Methods Concentrations of epidermal growth factor (EGF), interleukin (IL) - 1α, 1β, 6, 10, 12 and 13, interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α) and chemokines: IL-8 (CXC), MIP-1α (CCL3) and RANTES (CCL5) were measured by a multiplex immunobead assay in an asymptomatic control group and DTS patients with and without MGD. Spearman correlations between tear cytokines and severity of irritation symptoms and ocular surface signs were calculated. Results Tear concentrations of IL-6, IL-8 and TNF-α were significantly higher in DTS with and without MGD and EGF was significantly reduced in the DTS without MGD group compared to the control group. MIP-1α was greater in entire DTS and DTS without MGD groups than the control group and RANTES was greater in DTS with MGD than the control and DTS without MGD groups. IL-12 was significantly higher in the DTS with MGD than the DTS without MGD subgroup. Significant correlations were observed between IL-6 and irritation symptoms and between a number of cytokines and chemokines and clinical parameters. Conclusions As predicted, patients with DTS have higher levels of inflammatory mediators in their tears that show correlation with clinical disease parameters. Furthermore, different tear cytokine/chemokine profiles were observed in DTS patients with and without MGD groups.

Subjective assessments and objective diagnostic tests have clinical utility as diagnostic tools in tear-film disorders. ATD is correlated with ocular-surface disease. An algorithm summarizing the diagnostic utility of these tests is included.

The balance of cytokines in the tear fluid and conjunctival epithelium is altered in Sjögren's syndrome. The severity of keratoconjunctivitis sicca in this condition increases as tear fluid EGF concentration decreases and levels of inflammatory cytokines in the conjunctival epithelium increase. These findings provide new insight into the pathogenesis of keratoconjunctivitis and provide potential targets for therapy.

There is mounting evidence that the microbiome has potent immunoregulatory functions. We assessed the effects of intestinal dysbiosis in a model of Sjögren syndrome (SS) by subjecting mice to desiccating stress (DS) and antibiotics (ABX). We characterized the conjunctival, tongue and fecal microbiome profiles of patients with SS. Severity of ocular surface and systemic disease was graded. 16S ribosomal RNA gene sequencing characterized the microbiota. ABX + DS mice had a significantly worse dry eye phenotype compared to controls, a decrease in Clostridium and an increase in Enterobacter, Escherichia/Shigella, and Pseudomonas in stool after ABX + DS for 10 days. Goblet cell density was significantly lower in ABX treated groups compared to controls. Stool from SS subjects had greater relative abundances of Pseudobutyrivibrio, Escherichia/Shigella, Blautia, and Streptococcus, while relative abundance of Bacteroides, Parabacteroides, Faecalibacterium, and Prevotella was reduced compared to controls. The severity of SS ocular and systemic disease was inversely correlated with microbial diversity. These findings suggest that SS is marked by a dysbiotic intestinal microbiome driven by low relative abundance of commensal bacteria and high relative abundance of potentially pathogenic genera that is associated with worse ocular mucosal disease in a mouse model of SS and in SS patients.

Chronic dry eye syndrome affects over 10 million people in the United States; it is associated with inflammation of the lacrimal gland (LG) and in some cases involves T cell infiltration of the conjunctiva. We demonstrate that environmental desiccating stress (DS) elicits T cell-mediated inflammation of the cornea, conjunctiva, and LG, but not other organs in mice. The lacrimal keratoconjunctivitis (LKC) was mediated by CD4+ T cells, which, when adoptively transferred to T cell-deficient nude mice, produced inflammation in the LG, cornea, and conjunctiva, but not in any other organ. Adoptively transferred CD4+ T cells produced LKC even though recipients were not exposed to DS. LKC was exacerbated in euthymic mice depleted of CD4+CD25+forkhead/winged helix transcription factor+ regulatory T cells. The results suggest that DS exposes shared epitopes in the cornea, conjunctiva, and LG that induce pathogenic CD4+ T cells that produce LKC, which under normal circumstances is restrained by CD4+CD25+forkhead/winged helix transcription factor+ regulatory T cells.