Dealing with the Persistent Pathogenic Issues of Dry Eye Disease: The Importance of External and Internal Stimuli and Tissue Responses

The immune system plays a central role in protecting the ocular surface from exogenous and endogenous insults, maintaining tissue homeostasis thanks to the mechanism of para-inflammation. This physiological adaptive response may induce resident macrophages/monocytes to produce cytokines and growth factors in order to promote epithelial cell recovery. In case of well-controlled para-inflammation, caused by a low amount of stress, cell viability and function are maintained. When stress becomes too intense, there is a response characterized by the activation of autophagic pathways and consequent cell death. Dysregulated homeostasis and chronic sub-clinical inflammation are the starting points for the development of a stable, chronic inflammatory disease, which leads to ocular surface damage, and, in turn, to the onset or progression of chronic dry eye disease (DED). The long-term management of DED should consider all of the pathogenic issues involved in the disease, including the control of persistent external or internal stresses that are capable of activating and maintaining the para-inflammatory adaptive mechanisms, potentially leading to full-blown inflammation. Dysregulated para-inflammation can be corrected by means of the prolonged use of tear substitutes containing minimal doses of safe corticosteroids or other anti-inflammatory molecules (e.g., corticosteroid, cyclosporine) in order to re-equilibrate ocular surface homeostasis

Optimal Operation of an Innovative Electric Vehicle Charging Hub directly fed by Renewables

The reduction of Green House Gases (GHGs) emissions has been the top priority of the European Union (EU) in recent times. The increase in use of Electric Vehicles (EVs) to combat climate change is viable only with the use of Renewable Energy Sources (RESs) to power them. Since the Paris Agreement in 2015, the integration of RESs into the charging infrastructure has increased in the EU. The increasing market share of EVs in various categories has called for immediate changes in the EV charging infrastructure and in the operation of charging hubs. This paper aims to present an Energy Management System (EMS) to efficiently manage an EV charging hub fed by RESs, reducing the daily costs of operation and GHG emissions. The mathematical model of the EMS is developed in Matlab as a Mixed Integer Linear Programming (MILP) model. The MILP-based EMS is applied to the real-world case of an innovative EV charging hub located in the Ligurian region of Italy and the results of the optimization are reported

Corneal epithelial proliferation and thickness in a mouse model of dry eye

Although several studies have previously focused on the conjunctival epithelial response to surface dryness, little is known about the effect of a dry environment on corneal epithelium, which is the most clinically significant tissue affected in dry eye. The aim of this study was to quantitatively evaluate the effect of desiccating stress on the number of proliferating corneal epithelial cells and corneal epithelial thickness in mice placed in a controlled-environment chamber (CEC) that induces dry eye. Corneal epithelial cell proliferation and thickness were studied in 8–12 week old female BALB/c mice placed in the CEC (temperature: 22.3 ± 0.7°C; relative humidity: 22.5 ± 4.5%; airflow: 15 L/min) for 7 days and compared to a control group of mice with no dry eye. Actively proliferating cells were identified by immunofluorescence using a FITC-conjugated antibody against the Ki-67 protein, a cell proliferation marker expressed during active phases of the cell cycle. To detect the spatial distribution of proliferative cells, Ki-67+ cells were counted in three areas of the epithelium: center, periphery, and limbus. Corneal epithelial thickness was evaluated in the central cornea after staining with hematoxylin-eosin. Results from each experimental group were compared using the Mann-Whitney test. The number of Ki-67+ cells observed in the corneal epithelium of mice exposed to the CEC was significantly higher in each area (center: 32.1 ± 1.1; periphery: 94.2 ± 5.3; limbus: 4.0 ± 1.5) than in the control group (center: 13.2 ± 1.0, p = 0.02; periphery: 42.9 ± 2.3, p = 0.02; limbus: 0.0, p = 0.01). In mice subjected to desiccating stress, a significant number of Ki-67+ positive cells were detected in the basal and suprabasal cell layers (central area 46%; periphery 30.8%: limbus 0%), whereas in the control group the cells were exclusively distributed through the basal cell layer. Ki-67+ cells were not found in the corneal stroma or endothelium in any group. The corneal epithelium was found to be significantly thicker in dry eye mice (54.94 ± 6.09 μm) as compared to the controls (43.9 ± 6.23 μm: p < 0.0001) by a mean of 25%. These results demonstrate that desiccating stress increases corneal epithelial turnover and thickness, similar to what is observed in other chronic inflammatory states of other epithelialized surfaces. The CEC can facilitate the study of the regulation of epithelial cell function and turnover at the molecular and cellular levels under desiccating stress conditions

Effect of the Ocular Microenvironment in Regulating Corneal Dendritic Cell Maturation

Objective To determine whether the ocular anterior segment (aqueous humor and cornea) actively inhibits dendritic cell (DC) maturation. Methods Dendritic cells were injected into syngeneic corneas or conjunctivae, and their surface major histocompatibility complex class II expression in response to the local milieu was assessed using confocal microscopy. Immature DCs were cocultured with corneal supernatant or with aqueous humor to evaluate their regulation of DC phenotypic and functional maturity. Results In contrast to conjunctivally injected DCs, DCs injected into the cornea resisted up-regulation in expression of surface major histocompatibility complex class II. Corneal supernatant–treated and aqueous humor–treated DCs retained their immaturity, as reflected by high antigen uptake but low costimulatory molecule (CD80 and CD86) expression and poor T-cell stimulation. Anti–transforming growth factor β2 treatment of aqueous humor and of corneal supernatant led to complete and partial blockade of their inhibition of DC maturation, respectively. However, α-melanocyte–stimulating hormone and calcitonin gene-related peptide had no demonstrable effect on DC maturation. Conclusion Cornea and aqueous humor, principally through transforming growth factor β2, promote generation of phenotypically and functionally immature DCs. Clinical Relevance Our results indicate that relative immune quiescence in the cornea and in the anterior segment is actively maintained in part by the inhibitory effect of transforming growth factor β2 on resident DCs and by their suppression of T-cell–mediated immune and inflammatory responses

modulation of inflammation related genes in the cornea of a mouse model of dry eye upon treatment with cyclosporine eye drops

ABSTRACTPurpose/Aim: Inflammation is recognized as playing an etiological role in dry eye disease. This study aimed to assess the efficacy of various topical cyclosporine A (CsA) formulations on co..

Multicentric Case-Control Study on Azathioprine Dose and Pharmacokinetics in Early-onset Pediatric Inflammatory Bowel Disease

BACKGROUND: Early-onset inflammatory bowel disease (IBD) is generally aggressive, with a high probability of complications and need of surgery. Despite the introduction of highly effective biological drugs, treatment with azathioprine continues to be important even for early-onset IBD; however, in these patients azathioprine response seems to be reduced. This study evaluated azathioprine doses, metabolite concentrations, and their associations with patients' age in children with IBD treated at 6 tertiary pediatric referral centers. METHODS: Azathioprine doses, metabolites, and clinical effects were assessed after at least 3 months of therapy in 17 early-onset (age 12 and <18 yrs, controls) patients with IBD. Azathioprine dose was titrated on therapeutic efficacy (response and adverse effects). Azathioprine metabolites and thiopurine methyltransferase activity were determined by high-performance liquid chromatography with ultra violet-vis detection (HPLC-UV) methods. RESULTS: Frequency of patients in remission was similar among early-onset and control groups, respectively (82% and 84%, P value = 0.72). Early-onset patients required higher doses of azathioprine (median 2.7 versus 2.0 mg\ub7kg\ub7d, P value = 1.1 7 10). Different doses resulted in comparable azathioprine active thioguanine nucleotide metabolite concentrations (median 263 versus 366 pmol/8 7 10 erythrocytes, P value = 0.41) and methylmercaptopurine nucleotide concentrations (median 1455 versus 1532 pmol/8 7 10 erythrocytes, P value = 0.60). Lower ratios between thioguanine nucleotide metabolites and azathioprine doses were found in early-onset patients (median 98 versus 184 pmol/8 7 10 erythrocytes\ub7mg\ub7kg\ub7d, P value = 0.017). Interestingly, early-onset patients presented also higher thiopurine methyltransferase activity (median 476 versus 350 nmol methylmercaptopurine/mg hemoglobin/h, P-value = 0.046). CONCLUSIONS: This study demonstrated that patients with early-onset IBD present increased inactivating azathioprine metabolism, likely because of elevated activity of the enzyme thiopurine methyltransferase

Artificial Tears: Biological Role of Their Ingredients in the Management of Dry Eye Disease

Dry eye disease (DED) is the most common ocular surface disease, characterized by insufficient production and/or instability of the tear film. Tear substitutes are usually the first line of treatment for patients with DED. Despite the large variety of tear substitutes available on the market, few studies have been performed to compare their performance. There is a need to better understand the specific mechanical and pharmacological roles of each ingredient composing the different formulations. In this review, we describe the main categories of ingredients composing tear substitutes (e.g., viscosity-enhancing agents, electrolytes, osmo-protectants, antioxidants, lipids, surfactants and preservatives) as well as their effects on the ocular surface, and we provide insight into how certain components of tear substitutes may promote corneal wound healing, and/or counteract inflammation. Based on these considerations, we propose an approach to select the most appropriate tear substitute formulations according to the predominant etiological causes of DED

The HYLAN M Study: Efficacy of 0.15% High Molecular Weight Hyaluronan Fluid in the Treatment of Severe Dry Eye Disease in a Multicenter Randomized Trial

The aim of the HYLAN M study was to investigate if symptoms and/or signs of patients suffering from severe dry eye disease (DED) can be improved by substituting individually optimized artificial tear therapy by high molecular weight hyaluronan (HMWHA) eye drops. In this international, multicenter study, patients with symptoms of at least ocular surface disease index (OSDI) 33 and corneal fluorescein staining (CFS) of at least Oxford grade 3 were included. A total of 84 per-protocol patients were randomized in two study arms. The control group continued to use their individual optimum artificial tears over the study period of eight weeks; in the verum group, the artificial tears were substituted by eye drops containing 0.15% HMWHA. At the week 8 visit, the average OSDI of the verum group had improved by 13.5 as compared to the control group (p = 0.001). The best corrected visual acuity (BCVA) had improved by 0.04 logMAR (p = 0.033). CFS, tear film break-up time (TBUT), Schirmer I, lid wiper epitheliopathy (LWE), mucocutaneous junction (Yamaguchi score), and tear osmolarity were not significantly different between the verum and control groups (p > 0.050). We conclude that for most patients with severe DED, 0.15% HMWHA eye drops provide excellent improvement of symptoms without impairment of dry eye signs

The Management of Dry Eye Disease: Proceedings of Italian Dry Eye Consensus Group Using the Delphi Method

Dry eye disease (DED) is a highly prevalent, chronic and progressive condition that affects 5–33% of the world’s adult population [1]. The 1995 definition of DED only considered patient-reported symptoms (ocular discomfort) and damage to the inter-palpebral ocular surface [2]. However, as it became apparent that this failed to reflect the complexity of the disease and its impact on visual function, inducing a risk of under-diagnosis, the 2007 International Dry Eye WorkShop (DEWS) redefined it as follows: “A multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. It is accompanied by increased osmolarity of the tear film and inflammation of the ocular surface” [3]. This introduced the concept that the ocular surface is a single system, added visual disturbances to the symptoms of ocular discomfort and drew attention to the key concepts of inflammation and tear hyperosmolarity. Subsequently, as it is not unusual in everyday clinical practice to encounter patients with moderate–severe symptoms who have no pathological signs on the ocular surface or, conversely, patients with severe signs who are asymptomatic because of decreased corneal sensitivity, DEWS II revised its definition to read “Dry eye is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film, and accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles” [4] in order to indicate the occurrence of corneal nerves impairment, too. The symptoms characterizing the disease can severely affect the patients’ quality of life and everyday activities such as reading, driving or working on a computer [5–8] and are also associated with high levels of anxiety and depression [9]. Consequently, it is not only important to prescribe the appropriate treatment, but also to monitor its effects over time in order to ensure long-term relief and prevent disease chronicity [10,11]. Clinicians are clearly aware of the need to adopt a standardized approach to diagnose and treat DED that includes counselling, patient education and the establishment of a medical alliance to promote effective treatment [12,13]. The aim of this paper is to describe the process used by a group of Italian ophthalmologists (“Italian Dry Eye Consensus Group”) focused on DED for identifying four major statements related to the disease aimed at improving overall DED patient care [14]. Given the complexity of the disease and the different clinical contexts in which it may occur, the method used was based on real-life experience, as well as scientific data, and allowed the consideration of areas of still uncertain or unproven knowledge that may nevertheless help to guide everyday clinical practice and future research