Analysis of the mucosal chemokines CCL28, CXCL14, and CXCL17 in dry eye disease: An in vitro and clinical investigation.

Mucosal chemokines have antimicrobial properties and play an important role in mucosal immunity. However, little is known about their expression on the ocular surface. This study aimed to analyze the expression of the mucosal chemokines CCL28, CXCL14 and CXCL17 in corneal and conjunctival epithelial cells under in vitro dry eye (DE) conditions, and in conjunctival samples from healthy subjects and DE patients. Human corneal epithelial cells (HCE) and immortalized human conjunctival epithelial cells (IM-HConEpiC) were incubated under hyperosmolar (400-500 mOsM) or inflammatory (TNF-α 25 ng/mL) conditions for 6 h and 24 h to measure CCL28, CXCL14, and CXCL17 gene expression by RT-PCR and their secretion by immunobead-based analysis (CCL28, CXCL14) and ELISA (CXCL17). Additionally, twenty-seven DE patients and 13 healthy subjects were included in this study. DE-related questionnaires (OSDI, mSIDEQ and NRS) evaluated symptomatology. Ocular surface integrity was assessed using vital staining. Tactile sensitivity was measured with Cochet-Bonnet esthesiometer, and mechanic and thermal (heat and cold) sensitivity using Belmonte's non-contact esthesiometer. Subbasal nerve plexus and dendritic cell density were analyzed by in vivo confocal microscopy. Conjunctival cells from participants were collected by impression cytology to measure mucosal chemokines gene expression by RT-PCR. Our results showed that HCE and IM-HConEpiC cells increased CCL28, CXCL14, and CXCL17 secretion under hyperosmolar conditions. The gene expression of CCL28 was significantly upregulated in conjunctival samples from DE patients. CCL28 expression correlated positively with symptomatology, corneal staining, heat sensitivity threshold, and dendritic cell density. CXCL14 expression correlated positively with age, ocular pain, conjunctival staining, tactile sensitivity, and image reflectivity. CXCL17 expression correlated positively with corneal staining. These results suggest that corneal and conjunctival epithelial cells could be a source of CCL28, CXCL14, and CXCL17 on the ocular surface and that CCL28 might be involved in DE pathogenesis.

Cytokine profile of human limbal myofibroblasts: Key players in corneal antiviral response.

BACKGROUND: Corneal transparency may be compromised by viral infections causing corneal scarring, edema, and neovascularization. Ocular injury results from collateral damage induced by exacerbated immune response in corneal stroma. Myofibroblasts play a key role in this process by producing a disorganized extracellular matrix and inflammatory mediators. However, the immune response profile of myofibroblasts during viral infections is still under study. The aim of this work was to analyze the cytokine profile of human limbal myfibroblasts (HLMs) stimulated with the double-stranded RNA analog polyinosinic:polycytidylic acid (poly I:C) and to identify their signaling pathways. METHODS: HLMs were isolated from cadaveric sclera-corneal rims and stimulated with poly I:C (10 µg/ml) for 12 h. The secretion of 36 cytokines was measured using the Human Cytokine Array Panel A. The secretion of IFN-ß was quantified by ELISA. The expression of pattern recognition receptors (PRRs) such as TLR3, RIG-1 and MDA5 were analyzed by western blot assays. Furthermore, translocation of the nuclear factors NF-κB, IRF3, and IRF7 was assessed by fluorescence staining. In addition, the differentially expressed cytokines were analyzed using the Core Analysis Tool of the Ingenuity Pathway Analysis IPA software. RESULTS: HLMs stimulated with poly I:C increased (fold change > 2) the secretion of G-CSF, sTREM-1, CXCL1, CCL1, CXCL8, CXCL10, CXCL11, CCL2, CCL5, IL-13, IL-6, IL-1ra, and IFN-ß compared with HLMs under basal conditions. Poly I:C stimulation also induced the expression of RIG-1 (p < 0.001), but the expression of TLR3 and MDA5 was unmodified. Finally, HLMs increased nuclear translocation of NF-κB, IRF3, and IRF7 after poly I:C stimulation. Bioinformatic analysis identified canonical signaling pathways associated with cell adhesion and diapedesis, chemokine signaling, and activation of IRFs by cytosolic pattern recognition receptors. CONCLUSIONS: These results demonstrate that HLMs secrete cytokines involved in immune cell activation and chemotaxis. The data suggest a key role for HLMs during viral infections in cornea and extend our knowledge about the signaling pathways they trigger.

Microbial Warfare on Three Fronts: Mixed Biofilm of Aspergillus fumigatus and Staphylococcus aureus on Primary Cultures of Human Limbo-Corneal Fibroblasts.

Background: Coinfections with fungi and bacteria in ocular pathologies are increasing at an alarming rate. Two of the main etiologic agents of infections on the corneal surface, such as Aspergillus fumigatus and Staphylococcus aureus, can form a biofilm. However, mixed fungal-bacterial biofilms are rarely reported in ocular infections. The implementation of cell cultures as a study model related to biofilm microbial keratitis will allow understanding the pathogenesis in the cornea. The cornea maintains a pathogen-free ocular surface in which human limbo-corneal fibroblast cells are part of its cell regeneration process. There are no reports of biofilm formation assays on limbo-corneal fibroblasts, as well as their behavior with a polymicrobial infection. Objective: To determine the capacity of biofilm formation during this fungal-bacterial interaction on primary limbo-corneal fibroblast monolayers. Results: The biofilm on the limbo-corneal fibroblast culture was analyzed by assessing biomass production and determining metabolic activity. Furthermore, the mixed biofilm effect on this cell culture was observed with several microscopy techniques. The single and mixed biofilm was higher on the limbo-corneal fibroblast monolayer than on abiotic surfaces. The A. fumigatus biofilm on the human limbo-corneal fibroblast culture showed a considerable decrease compared to the S. aureus biofilm on the limbo-corneal fibroblast monolayer. Moreover, the mixed biofilm had a lower density than that of the single biofilm. Antibiosis between A. fumigatus and S. aureus persisted during the challenge to limbo-corneal fibroblasts, but it seems that the fungus was more effectively inhibited. Conclusion: This is the first report of mixed fungal-bacterial biofilm production and morphological characterization on the limbo-corneal fibroblast monolayer. Three antibiosis behaviors were observed between fungi, bacteria, and limbo-corneal fibroblasts. The mycophagy effect over A. fumigatus by S. aureus was exacerbated on the limbo-corneal fibroblast monolayer. During fungal-bacterial interactions, it appears that limbo-corneal fibroblasts showed some phagocytic activity, demonstrating tripartite relationships during coinfection.

Amniotic membrane conditioned medium (AMCM) reduces inflammatory response on human limbal myofibroblast, and the potential role of lumican.

Purpose: Viral infections such as herpetic keratitis (HSK) activate the innate immune response in the cornea triggering opacity and loss of vision. This condition is performed mainly by myofibroblasts that exacerbate secretion of inflammatory cytokines. Amniotic membrane transplantation (AMT) reduces ocular opacity and scarring inhibiting secretion of inflammatory cytokines and proliferation of myofibroblasts. We previously reported that the amniotic membrane (AM) favors an anti-inflammatory microenvironment inhibiting the secretion of inflammatory cytokines, expression of innate immune receptors, and translocation of nuclear NF-κB on human limbal myofibroblasts (HLMs). The aim of the present study was to determine whether the soluble factors of the AM decrease the immune response of HLMs stimulated with polyinosinic-polycytidylic acid sodium salt (poly I:C). Methods: The AM was incubated in Dulbecco's modified eagle medium (DMEM)/F12, and the supernatant was collected to obtain amniotic membrane conditioned medium (AMCM). HLMs were isolated from cadaveric sclera-corneal rims. HLMs were cultured in DMEM/F12 or AMCM and stimulated or not with poly I:C (10 µg/ml) for 12 h to analyze synthesis of CCL2, CCL5, CXCL10, MDA5, RIG-1, and TLR3 or for 2 h to analyze translocation of nuclear NF-kB, IRF3, and IRF7. The proteins contained on AMCM were analyzed by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and the acquired peptide ions were analyzed with the Mascot program using both National Center for Biotechnology Information (NCBI) and expressed sequence tag (EST) databases. Results: AMCM downregulated the mRNA levels of CCL2, CCL5, CXCL10, MDA5, RIG-1, and TLR3. In addition, AMCM decreased secretion of CCL2, CCL5, and CXCL10 and translocation of nuclear NF-κB. Interestingly, AMCM increased translocation of nuclear IRF3 and synthesis and secretion of type I IFN-ß. We also identified small leucine-rich proteoglycan lumican in the AMCM. The administration of rh-lumican to poly I:C-stimulated HLMs reduced the mRNA levels of CCL2, CCL5, and CXCL10. Conclusions: These results suggest that the AM can trigger an anti-inflammatory response on HLMs through soluble factors, and that lumican could play an important role in these effects.

Negative interaction of Staphylococcus aureus on Fusarium falciforme growth ocular isolates in an in vitro mixed biofilm.

The interactions between prokaryotes and eukaryotes are abundant in nature. These microorganisms also interact in the human body. Fungal-bacteria interactions are present in many diseases. In this study, we evaluated the microbial interaction of Fusarium falciforme and Staphylococcus aureus developing mixed biofilm in vitro. When both microorganisms grew up together the mixed biofilm biomass decreased than F. falciforme monobiofilm biomass. S. aureus was able to interact and form aggregates over the mycelium and conidia surface of F. falciforme. Our results suggest that S. aureus could bind to colloidal chitin. On another hand, the supernatants from S. aureus biofilm and S. aureus-F. falciforme presented an antifungal effect over F. falciforme biofilm formation. Finally we found that the pH had an inhibitory effect over fungal biofilm formation. We concluded that S. aureus can affect the F. falciforme growth negatively in mixed biofilm involving factors like pH, supernatants compounds, anchor to chitin, and bacterial viability.

Implication of Melanopsin and Trigeminal Neural Pathways in Blue Light Photosensitivity in vivo.

Photophobia may arise from various causes and frequently accompanies numerous ocular diseases. In modern highly illuminated world, complaints about greater photosensitivity to blue light increasingly appear. However, the pathophysiology of photophobia is still debated. In the present work, we investigated in vivo the role of various neural pathways potentially implicated in blue-light aversion. Moreover, we studied the light-induced neuroinflammatory processes on the ocular surface and in the trigeminal pathways. Adult male C57BL/6J mice were exposed either to blue (400-500 nm) or to yellow (530-710 nm) LED light (3 h, 6 mW/cm2). Photosensitivity was measured as the time spent in dark or illuminated parts of the cage. Pharmacological treatments were applied: topical instillation of atropine, pilocarpine or oxybuprocaine, intravitreal injection of lidocaine, norepinephrine or "blocker" of the visual photoreceptor transmission, and intraperitoneal injection of a melanopsin antagonist. Clinical evaluations (ocular surface state, corneal mechanical sensitivity and tear quantity) were performed directly after exposure to light and after 3 days of recovery in standard light conditions. Trigeminal ganglia (TGs), brainstems and retinas were dissected out and conditioned for analyses. Mice demonstrated strong aversion to blue but not to yellow light. The only drug that significantly decreased the blue-light aversion was the intraperitoneally injected melanopsin antagonist. After blue-light exposure, dry-eye-related inflammatory signs were observed, notably after 3 days of recovery. In the retina, we observed the increased immunoreactivity for GFAP, ATF3, and Iba1; these data were corroborated by RT-qPCR. Moreover, retinal visual and non-visual photopigments distribution was altered. In the trigeminal pathway, we detected the increased mRNA expression of cFOS and ATF3 as well as alterations in cytokines' levels. Thus, the wavelength-dependent light aversion was mainly mediated by melanopsin-containing cells, most likely in the retina. Other potential pathways of light reception were also discussed. The phototoxic message was transmitted to the trigeminal system, inducing both inflammation at the ocular surface and stress in the retina. Further investigations of retina-TG connections are needed.

Anti-Inflammatory and Anti-Fibrotic Effects of Human Amniotic Membrane Mesenchymal Stem Cells and Their Potential in Corneal Repair.

Acute ocular chemical burns are ophthalmic emergencies requiring immediate diagnosis and treatment as they may lead to permanent impairment of vision. The clinical manifestations of such burns are produced by exacerbated innate immune response via the infiltration of inflammatory cells and activation of stromal fibroblasts. New therapies are emerging that are dedicated to repair mechanisms that improve the ocular surface after damage; for example, transplantation of stem cells (SC) has been successfully reported for this purpose. The pursuit of easily accessible, noninvasive procedures to obtain SC has led researchers to focus on human tissues such as amniotic membrane. Human amniotic mesenchymal SC (hAM-MSC) inhibits proinflammatory and fibrotic processes in different diseases. hAM-MSC expresses low levels of classical MHC-I and they do not express MHC-II, making them suitable for regenerative medicine. The aim of this study was to evaluate the effect of intracameral injection of hAM-MSC on the clinical manifestations, the infiltration of inflammatory cells, and the activation of stromal fibroblasts in a corneal alkali-burn model. We also determined the in vitro effect of hAM-MSC conditioned medium (CM) on α-SMA+ human limbal myofibroblast (HLM) frequency and on release of neutrophil extracellular traps (NETs). Our results show that intracameral hAM-MSC injection reduces neovascularization, opacity, stromal inflammatory cell infiltrate, and stromal α-SMA+ cells in our model. Moreover, in in vitro assays, CM from hAM-MSC decreased the quantity of α-SMA+ HLM and the release of NETs. These results suggest that intracameral hAM-MSC injection induces an anti-inflammatory and anti-fibrotic environment that promotes corneal wound healing. Stem Cells Translational Medicine 2018;7:906-917.

Characterization of free fatty acid receptors expression in an obesity rat model with high sucrose diet.

INTRODUCTION/AIMS: In recent years, it has been shown that free fatty acids receptors (FFAR) of whose function in the cell surface plays a significant role in the regulation of cell function and nutrition as well are activated by various endogenous ligands, but mainly by fatty acids. Within FFAR of our interest are GPR 41, 43 and 120. The functions of these receptors are varied and dependent on the tissue where they are. The activation and signaling of these receptors, FFAR, are involved in many physiological processes, and currently the target of many drugs in metabolic disorders like obesity, diabetes and atherosclerosis. MATERIAL AND METHODS: Obesity was induced with hypercaloric diet (HD) in male Wistar rats for 20 weeks (n = 10). At the end, adipose tissue (abdominal and subcutaneous) was taken to perform assays for relative quantification mRNA expression by end-point RT-PCR and protein level expression by Western blot. RESULTS: These present data have shown for the first time that total mRNA isolation and protein expression from both adipose tissues (abdominal and subcutaneous) of rat in obesity condition yield significative statistical difference among the control versus obese groups, showing that the diet high in carbohydrates modifies the total presence of mRNA and protein level expression of the receptors GPR41, 43 and 120. CONCLUSIONS: Further comparative methods are in process to clarify whether or not the obesity changes the functional receptors in these two tissues for new pharmacological approaches.

Human Amniotic Membrane Mesenchymal Stem Cells inhibit Neutrophil Extracellular Traps through TSG-6.

The mesenchymal stem cells obtained from human amniotic membrane (hAMSC) possess immunosuppressive functions through soluble factors such as prostanoids and proteins; thus, they have been proposed to ameliorate inflammatory processes. On the other hand, activated neutrophils are cells of the first line of immune defense that are able to release extracellular traps (NETs). NETs are formed of DNA and granular components; however, the excessive release of NETs is associated with the development of autoimmune and chronic inflammatory diseases. In this study, we identified that conditioned medium (CM) from hAMSC was able to diminish NETs release, as well as the production of reactive oxygen species (ROS) and the mitochondrial membrane potential from LPS-stimulated mouse bone marrow-derived neutrophils (BMN). Interestingly, NETs inhibition, ROS levels decrease and mitochondrial membrane potential loss were reverted when LPS-stimulated murine derived BMN were exposed to the CM from hAMSC transfected with TSG-6-siRNA. Finally, rhTSG6 was able to significantly diminish NETs release in BMN. These data suggest an inhibition mechanism of NETs ROS-dependent in which TSG-6 participates. Consequently, we propose the hAMSC use as a therapeutic candidate in the treatment of inflammatory diseases in which NETs are involved.

Amniotic membrane modulates innate immune response inhibiting PRRs expression and NF-κB nuclear translocation on limbal myofibroblasts.

Corneal damage observed in a viral infection such as herpetic stromal keratitis is mainly caused by proinflammatory molecules released by resident cells in the response to viral antigens. There are pattern recognition receptors like MDA5, RIG-1, and TLR3, that recognize viral dsRNA and after activation, the innate immune response is exacerbated inducing the synthesis and secretion of inflammatory cytokines through NF-κB activation. Amniotic membrane (AM) has demonstrated to reduce inflammation by several mechanisms, however the effect of AM on innate immune receptors such as MDA5, RIG-1, and TLR3 has not been reported. In this study, we have determined that the presence of AM significantly inhibited the synthesis and secretion of proinflammatory cytokines on human limbal myofibroblasts (HLM) stimulated with poly I:C. Similarly, the presence of AM reduced the protein expression of MDA5, RIG-1, and TLR3 on poly I:C stimulated HLM. Additionally, the presence of the AM significantly inhibited the NF-κB nuclear translocation when the HLM were poly I:C stimulated, and concomitantly, the AM was able to relocate cadherins affecting the myofibroblastic cellular morphology. These results suggest that AM generates an anti-inflammatory microenvironment, and specific inhibition of NFκB nuclear translocation on infected corneal tissue would reduce the inflammation undesirable effects, explaining in part the beneficial usefulness of transplanting AM on herpetic stromal keratitis.