Laura Contreras-Ruiz

Expression of MUC5AC in ocular surface epithelial cells using cationized gelatin nanoparticles.

Decreased production of the mucin MUC5AC in the eye is related to several pathological conditions, including dry eye syndrome. A specific strategy for increasing the ocular levels of MUC5AC is not yet available. Using a plasmid specially designed to encode human MUC5AC, we evaluated the ability of hybrid cationized gelatin nanoparticles (NPs) containing polyanions (chondroitin sulfate or dextran sulfate) to transfect ocular epithelial cells. NPs were developed using the ionic gelation technique and characterized by a small size (<200 nm), positive zeta potential (+20/+30 mV), and high plasmid association efficiency (>95%). MUC5AC mRNA and protein were detected in conjunctival cells after in vitro transfection of the NPs. The in vivo administration of the NPs resulted in significantly higher MUC5AC expression in the conjunctiva compared to untreated control and naked plasmid. These results provide a proof-of-concept that these NPs are effective vehicles for gene therapy and candidates for restoring the MUC5AC concentration in the ocular surface.

Modulation of Conjunctival Goblet Cell Function by Inflammatory Cytokines

Ocular surface inflammation associated with Sjögrens syndrome is characterized by a loss of secretory function and alteration in numbers of mucin secreting goblet cells. Such changes are a prominent feature of ocular surface inflammatory diseases and are attributed to inflammation; however, the exact effect of the inflammatory cytokines on conjunctival goblet cell function remains largely unknown. In this study, we developed a primary culture of mouse goblet cells from conjunctival tissue and evaluated the effects on their function by inflammatory cytokines detected in the conjunctiva of mouse model of Sjögrens syndrome (Thrombospondin-1 deficient mice). We found that apoptosis of goblet cells was primarily induced by TNF-α and IFN-γ. These two cytokines also inhibited mucin secretion by goblet cells in response to cholinergic stimulation, whereas IL-6 enhanced such secretion. No changes in secretory response were detected in the presence of IL-13 or IL-17. Goblet cells proliferated to varying degrees in response to all the tested cytokines with the greatest response to IL-13 followed by IL-6. Our results therefore reveal that inflammatory cytokines expressed in the conjunctiva during an ocular surface disease directly disrupt conjunctival goblet cell functions, compromising the protective function of tears, thereby contributing to ocular surface damage.

Immunomodulatory cross-talk between conjunctival goblet cells and dendritic cells.

Goblet cells are secretory epithelial cells of mucosal tissues that confer protection from environmental agents or pathogens via expression and secretion of soluble mucins. Loss of these cells is associated with several chronic inflammatory disorders of the mucosa. Although demonstrated to transfer antigens from the luminal surface to stromal cells in the intestinal mucosa, it is not known if goblet cells contribute to the regulation of an immune response. In this study we report that similar to intestinal and respiratory mucosal epithelia, mouse ocular surface epithelia predominantly express the TGF-ß2 isoform. Specifically, we demonstrate the ability of goblet cells to express TGF-ß2 and increase it in response to Toll-Like Receptor 4 mediated stimulus in cultures. Goblet cells not only express TGF-ß2, but are also able to activate it in a thrombospondin-1 (TSP-1) dependent manner via their cell surface receptor CD36. Furthermore, goblet cell derived soluble factors that possibly include TGF-ß2, alter dendritic cell (DC) phenotype to a tolerogenic type by downregulating DC expression of MHC class II and co-stimulatory molecules CD80, CD86 and CD40. Thus our study demonstrates goblet cells as a cellular source of active TGF-ß2 in ocular mucosa and implicates their immunomodulatory function in maintaining mucosal immune homeostasis.

Structural and Functional Alteration of Corneal Epithelial Barrier Under Inflammatory Conditions

Purpose: The aim of the study was to determine the effect of inflammatory conditions on the expression of tight junction (TJ) and adherens junction (AJ) proteins between human corneal epithelial cells and, consequently, on corneal epithelial barrier integrity. Materials and methods: Zonula occludens proteins ZO-1 and ZO-2, claudin-1 and -2 (CLDN-1 and CLDN-2), occludin (OCLN) as well as E-cadherin (E-cad) expression were analyzed in a human corneal epithelial cell line (HCE) at basal conditions and after stimulation with inflammatory cytokines (TNFα, TGFβ, IL-10, IL-13, IL-17, IL-6), using real time RT-PCR, Western blotting and immunofluorescence. Actin cytoskeleton staining was performed after all stimulations. Transepithelial electrical resistance (TER) and fluorescein transepithelial permeability (TEP) were measured as barrier integrity functional assays. Results: ZO-1, ZO-2, CLDN-1, CLDN-2, OCLN and E-cad were detected in HCE cell membranes at basal conditions. Cytokine stimulation resulted in significant changes in the expression of TJ and AJ proteins, both at mRNA and protein level, a remarkable change in their localization pattern, as well as a reorganization of actin cytoskeleton. Pro-inflammatory cytokines TNFα, TGFβ, IL-13, IL-17 and IL-6 induced a structural and functional disruption of the epithelial barrier, while IL-10 showed a barrier protective effect. Conclusion: Simulated inflammatory conditions lead to an alteration of corneal barrier integrity by modulating TJ, and to a lesser extent also AJ, protein composition, at least In Vitro. The observed barrier protective effects of IL-10 support its well-known anti-inflammatory functions and highlight a potential therapeutic perspective.

Trefoil factor family peptide 3 (TFF3) is upregulated under experimental conditions similar to dry eye disease and supports corneal wound healing effects in vitro.

PURPOSE To elucidate the role of trefoil family peptide (TFF) 3 at the ocular surface under conditions similar to dry eye disease (DED) and in tears of patients suffering from DED. METHODS Trefoil family peptide 3 levels in tear samples from non-Sjögrens DED patients with moderate dry eye were analyzed by ELISA and compared with tears from healthy volunteers. A human corneal epithelial (HCE) cell line was treated with proinflammatory cytokines IL-1β and TNF-α, hyperosmolar medium, or scratching for up to 24 hours. Trefoil family peptide 3 gene expression and protein biosynthesis were analyzed by RT-PCR, immunofluorescence, and ELISA. Migration and proliferation of HCE cells under recombinant (r) human (h) trefoil factor family peptide 3 (TFF3) stimulation were investigated by scratching and bromodeoxyuridine (BrdU) proliferation assays. RESULTS Tears of patients suffering from DED contained significantly higher TFF3 levels than tears from healthy volunteers. Stimulation of HCE cells with proinflammatory cytokines, culture under hyperosmolar conditions, or scratching resulted, with the exception of hyperosmolar conditions, in an increase in TFF3 expression and elevated secretion level of TFF3. Cell proliferation decreased and cell migration increased after 24-hours stimulation with rhTFF3. CONCLUSIONS These results suggest that inflammatory factors or ocular surface damage as they occur in DED, lead to an increase of TFF3 tear film concentration, whereas hyperosmolarity does not. Our data underline a potential role for TFF3 as a candidate therapeutic for the ocular surface damage observed in DED.

Polymorphism in THBS1 Gene Is Associated with Post-Refractive Surgery Chronic Ocular Surface Inflammation

PURPOSE To determine the association of single nucleotide polymorphisms (SNPs) of the thrombospondin 1 (THBS1) gene with development of chronic ocular surface inflammation (keratoconjunctivitis) after refractive surgery. DESIGN Retrospective cohort study. PARTICIPANTS Active duty U.S. Army soldiers (n = 143) who opted for refractive surgery. METHODS Conjunctival impression cytology samples collected from participants before the surgery were used to harvest DNA for genotyping 5 THBS1 SNPs (rs1478604, rs2228262, rs2292305, rs2228262, and rs3743125) using the Sequenom iPLEX Gold platform (Sequenom, San Diego, CA). Samples collected after surgery were used to harvest RNA for gene expression analysis by real-time polymerase chain reaction (PCR). Participants were followed for 1 year after surgery to monitor the status of keratoconjunctivitis. MAIN OUTCOME MEASURES Genetic basis of the development of chronic keratoconjunctivitis after refractive surgery. RESULTS Carriers of minor alleles of 3 SNPs each were found to be more susceptible to developing chronic keratoconjunctivitis (rs1478604: odds ratio [OR], 2.5; 95% confidence interval [CI], 1.41-4.47; P = 2.5 × 10(-3); rs2228262 and rs2292305: OR, 1.9; 95% CI, 1.05-3.51; P = 4.8 × 10(-2)). Carriers of the rs1478604 minor allele expressed significantly reduced levels of thrombospondin 1 (TSP1) (P = 0.042) and increased levels of an inflammatory cytokine associated with keratoconjunctivitis, interleukin-1β (P = 0.025), in their ocular surface epithelial cells compared with homozygous major allele controls. CONCLUSIONS Genetic variation in the THBS1 gene that results in decreased expression of the encoded glycoprotein TSP1 in ocular surface epithelial cells significantly increases the susceptibility to develop chronic ocular surface inflammation after refractive surgery. Further investigation of THBS1 SNPs in a larger sample size is warranted.

Thrombospondin-1-dependent immune regulation by transforming growth factor-β2-exposed antigen-presenting cells

An important role of transforming growth factor‐β (TGF‐β) in the development of regulatory T cells is well established. Although integrin‐mediated activation of latent TGF‐β1 is considered essential for the induction of regulatory T (Treg) cells by antigen‐presenting cells (APCs), such an activation mechanism is not applicable to the TGF‐β2 isoform, which lacks an integrin‐binding RGD sequence in its latency‐associated peptide. Mucosal and ocular tissues harbour TGF‐β2‐expressing APCs involved in Treg induction. The mechanisms that regulate TGF‐β activation in such APCs remain unclear. In this study, we demonstrate that murine APCs exposed to TGF‐β2 in the environment predominantly increase expression of TGF‐β2. Such predominantly TGF‐β2‐expressing APCs use thrombospondin‐1 (TSP‐1) as an integrin‐independent mechanism to activate their newly synthesized latent TGF‐β2 to induce Foxp3+ Treg cells both in vitro and in vivo. Expression of Treg induction by TGF‐β2‐expressing APCs is supported by a TSP‐1 receptor, CD36, which facilitates activation of latent TGF‐β during antigen presentation. Our results suggest that APC‐derived TSP‐1 is essential for the development of an adaptive regulatory immune response induced by TGF‐β2‐expressing APCs similar to those located at mucosal and ocular sites. These findings introduce the integrin‐independent mechanism of TGF‐β activation as an integral part of peripheral immune tolerance associated with TGF‐β2‐expressing tissues.

Conjunctival Goblet Cell Function: Effect of Contact Lens Wear and Cytokines.

Abstract: This review focuses on conjunctival goblet cells and their essential function in the maintenance of eye health. The main function of goblet cells is to produce and secrete mucins that lubricate the ocular surface. An excess or a defect in those mucins leads to several alterations that makes goblet cells central players in maintaining the proper mucin balance and ensuring the correct function of ocular surface tissues. A typical pathology that occurs with mucous deficiency is dry eye disease, whereas the classical example of mucous hyperproduction is allergic conjunctivitis. In this review, we analyze how goblet cell number and function can be altered in these diseases and in contact lens (CL) wearers. We found that most published studies focused exclusively on the goblet cell number. However, recent advances have demonstrated that, along with mucin secretion, goblet cells are also able to secrete cytokines and respond to them. We describe the effect of different cytokines on goblet cell proliferation and secretion. We conclude that it is important to further explore the effect of CL wear and cytokines on conjunctival goblet cell function.

TSP-1 Deficiency Alters Ocular Microbiota: Implications for Sjögren's Syndrome Pathogenesis

PURPOSE The potential role of commensals as triggering factors that promote inflammation in dry eye disease has not been explored. The objective of this study was to evaluate whether ocular microbiota changes with the onset of dry eye disease in thrombospondin-1-deficient (TSP-1(-/-)) mice, a strain that develops Sjögrens syndrome-like disease. METHODS Conjunctival swabs were collected from TSP-1(-/-) and C57BL/6 mice and analyzed for bacterial presence. Opsonophagocytosis of the bacterial conjunctival isolates derived from the aged TSP-1(-/-) mice by neutrophils derived from either TSP-1(-/-) or C57BL/6 bone marrow was evaluated. The bactericidal activities of TSP-1-derived peptide were examined. RESULTS We found that in TSP-1(-/-) mice, the conjunctival colonization with Staphylococcus aureus and coagulase negative staphylococci sp (CNS) species was significantly increased with aging and preceded that of the wild-type C57BL/6 control mice. This correlated with increased neutrophil infiltration into the conjunctiva of the TSP-1(-/-) mice, suggesting that TSP-1 plays a significant role in regulating immunity to commensals. Accordingly, the TSP-1(-/-) PMNs opsonophagocytozed the ocular commensals less efficiently than the TSP-1-sufficient neutrophils. Furthermore, a TSP-1-derived peptide, 4N1K, exhibited significant antimicrobial activity when compared to a control peptide against commensal sp. CONCLUSION These studies illustrate that alterations in the commensal frequency occur in the early stages of development of Sjögrens-like pathology and suggest that interventions that limit commensal outgrowth such as the use of TSP-1-derived peptides could be used for treatment during the early stages of the disease to reduce the commensal burden and ensuing inflammation.

Thrombospondin derived peptide attenuates Sjögren's syndrome‐associated ocular surface inflammation in mice

Sjögrens syndrome is the second most common rheumatic disease in which autoimmune response targets exocrine glands (salivary and lacrimal glands) result in clinical symptoms of dry mouth and dry eye. Inflammation of the lacrimal gland induces tear abnormalities that contribute to the inflammation of the ocular surface, which includes ocular mucosa. Thrombospondin‐1 (TSP‐1) plays a critical regulatory role in the ocular mucosa and as such TSP‐1–/– mice develop spontaneously chronic ocular surface inflammation associated with Sjögrens syndrome. The autoimmune pathology is also accompanied by a peripheral imbalance in regulatory (Treg) and inflammatory Th17 effectors. In this study, we demonstrate an in‐vitro effect of a CD47‐binding TSP‐derived peptide in the induction of transforming growth factor (TGF)‐β1‐secreting forkhead box protein 2 (Foxp3+) Tregs from activated CD4+CD25– T cells and the inhibition of pathogenic T helper type 17 (Th17)‐promoting interleukin (IL)‐23 derived from antigen‐presenting cells. The in‐vivo administration of this peptide promotes Foxp3+ Treg induction and inhibition of Th17 development. Consistent with these results, topical administration of CD47‐binding TSP peptide, both before and after the onset of the disease, attenuates clinical symptoms of SS‐associated dry eye in TSP‐1–/– mice. Augmented expression of Foxp3 detected in the draining lymph nodes of TSP peptide ‐treated mice compared to those treated with control peptide suggests the ability of TSP peptide to restore peripheral immune imbalance. Thus, our results suggest that TSP‐derived peptide attenuates Sjögrens syndrome‐associated dry eye and autoimmune inflammation by preventing Th17 development while promoting the induction of Tregs. Collectively, our data identify TSP‐derived peptide as a novel therapeutic option to treat autoimmune diseases.