Ilaria Macchi

The cellular mechanisms of dry eye: From pathogenesis to treatment

Dry eye is a complex disease characterized by changes in the ocular surface epithelia related to reduced quality and/or quantity of tears, inflammatory reaction, and impairment of ocular surface sensitivity. It has recently been proposed that increased tear osmolarity represents a main trigger to the altered cellular mechanisms leading to epithelial damage in dry eye. However, dry eye pathogenesis is multifactorial, with cytotoxic inflammatory mediators, altered lacrimal gland secretion and nerve function, squamous metaplasia of the conjunctival epithelium and decrease of goblet cells density, all playing a role in a detrimental loop that perpetuates and worsens damage to the corneal and conjunctival epithelia. Current topical treatments for dry eye patients include the use of lubricants and anti‐inflammatory drugs. However, lubricants only improve symptoms temporarily, and chronic use of topical steroids is associated to severe ocular side effects such as cataract and glaucoma. The deeper understanding of the cellular mechanisms that are altered in dry eye is opening novel perspectives for patients and physicians, who are seeking treatments capable not only of improving symptoms but also of restoring the homeostasis of the ocular surface. In this review, we will focus on novel anti‐inflammatory agents and on nerve growth factor, a neurotrophin that is altered in dry eye and has been suggested as a main player in the neuroimmune cross‐talk of the ocular surface as well as in the stimulation of corneal sensitivity, epithelial proliferation and differentiation, and stimulation of mucin production by goblet cells. J. Cell. Physiol. 228: 2253–2256, 2013.

Variability of Tear Osmolarity in Patients With Dry Eye

IMPORTANCE Knowledge about the variability of measurements using the TearLab Osmolarity System is necessary when evaluating the clinical utility of readings. OBJECTIVE To examine the variability of tear osmolarity measured by the TearLab Osmolarity System in patients with Sjögren syndrome (SS), patients with blepharitis, and control participants. DESIGN, SETTING, AND PARTICIPANTS Cross-sectional study at a tertiary care academic center from June 13, 2012, to March 21, 2013. Participants included 74 eyes of 37 patients from a volunteer sample (18 patients with SS, 11 patients with blepharitis, and 8 control participants) who were evaluated using the TearLab Osmolarity System, with 3 consecutive osmolarity measurements taken at 1-minute intervals in a session; 15 of these patients had the same measurements taken by the same examiner in 2 additional sessions on the same day (9 AM-10 AM, 12 PM-1 PM, or 3 PM-4 PM). Most patients with SS and patients with blepharitis were taking systemic or topical dry eye medications at the time of enrollment. MAIN OUTCOMES AND MEASURES Mean osmolarity and its variability calculated from a linear mixed model for each disease group that accounts for the variations attributable to different patients, eyes, and sessions and measurement error specific to each disease group. RESULTS Mean tear osmolarity was 307 mOsm/L, 304 mOsm/L, and 301 mOsm/L in the SS, blepharitis, and control groups, respectively (P = .46). The error associated with repeated measurements within a session in the patients without dry eye (10.5 mOsm/L [95% CI, 9.0-12.4]) was significantly lower than in the patients with blepharitis (14.6 mOsm/L [95% CI, 12.5-17.5]; P = .006) and patients with SS (15.8 mOsm/L [95% CI, 14.2-17.8]; P < .001) but a difference in the error of repeated measurements between patients with blepharitis and patients with SS was not identified (P = .46). CONCLUSIONS AND RELEVANCE There was increased variability attributable to error in repeated measurements in patients with SS and patients with blepharitis compared with control participants. The high variability of TearLab osmolarity readings in all groups makes the clinical interpretation of measurements unclear.

NGF and VEGF effects on retinal ganglion cell fate: new evidence from an animal model of diabetes.

Purpose: To investigate if the survival effects of nerve growth factor (NGF) eyedrops on retinal ganglion cell (RGCs) are related to vascular endothelial growth factor (VEGF) in a rat model of diabetic retinopathy. Methods: Diabetes was induced in adult rats by streptozotocin injection and changes in the NGF/TrkA and VEGF retina levels were related to the progression of RGC loss. Diabetic rats were subjected to administration of NGF eyedrops or intraocular injection of anti-NGF antibody. All morphologic, immunohistochemical, and biochemical analyses were performed on whole retinas dissected after 7 or 11 weeks after diabetes induction. Results: Diabetes was successfully induced in rats as shown by glycemic levels >250 mg/dL. The NGF levels increased in diabetic retinas at 7 weeks and decreased at 11 weeks, while VEGF levels increased at all time points. The RGC loss in diabetic retinopathy worsened with anti-NGF administration, which did not alter retina VEGF levels significantly. Administration of NGF eyedrops restored TrkA levels in the retina, and protected RGCs from degeneration without influencing VEGF levels. Conclusions: The early increase of NGF in diabetic retina might be an endogenous response for protecting RGCs from degeneration. This protective mechanism is impaired at 11 weeks following diabetes induction, and results in a marked RGC degeneration that is improved by exogenous NGF administration and worsened by anti-NGF. The observed NGF-induced neuroprotection on damaged RGCs was not associated with changes in VEGF retina levels, which were constantly high in diabetic rats and were not altered by anti-NGF administration.

Nerve growth factor modulation of retinal ganglion cell physiology.

Nerve growth factor (NGF) is an endogenous neurotrophin involved in the development, maintenance and regeneration of mammalian sympathetic and sensory neurons. Additionally, NGF is known to have trophic and differentiating activity on several populations of cholinergic neurons of the central nervous system (CNS), and to act as a differentiation factor in the development of the visual cortex. The paramount functions of NGF in the visual system are also highlighted by the presence of this neurotrophin and both its receptors TrkA and p75 in most intra‐ocular tissues, including lens, vitreous, choroid, iris, and trabecular meshwork. In the retina, NGF is produced and utilized specifically by retinal ganglion cells (RGC), bipolar neurons and glial cells, and is thought to have crucial protective effects in several disease states. Studies on the role of NGF on RGCs survival following optic nerve transection, ischemic injury, ocular hypertension and glaucoma are discussed in this review. J. Cell. Physiol. 229: 1130–1133, 2014.

Diagnosis and Management of Iridocorneal Endothelial Syndrome

The iridocorneal endothelial (ICE) syndrome is a rare ocular disorder that includes a group of conditions characterized by structural and proliferative abnormalities of the corneal endothelium, the anterior chamber angle, and the iris. Common clinical features include corneal edema, secondary glaucoma, iris atrophy, and pupillary anomalies, ranging from distortion to polycoria. The main subtypes of this syndrome are the progressive iris atrophy, the Cogan-Reese syndrome, and the Chandler syndrome. ICE syndrome is usually diagnosed in women in the adult age. Clinical history and complete eye examination including tonometry and gonioscopy are necessary to reach a diagnosis. Imaging techniques, such as in vivo confocal microscopy and ultrasound biomicroscopy, are used to confirm the diagnosis by revealing the presence of “ICE-cells” on the corneal endothelium and the structural changes of the anterior chamber angle. An early diagnosis is helpful to better manage the most challenging complications such as secondary glaucoma and corneal edema. Treatment of ICE-related glaucoma often requires glaucoma filtering surgery with antifibrotic agents and the use of glaucoma drainage implants should be considered early in the management of these patients. Visual impairment and pain associated with corneal edema can be successfully managed with endothelial keratoplasty.

Effects of Sex Hormones on Ocular Surface Epithelia: Lessons Learned From Polycystic Ovary Syndrome.

Polycystic ovary syndrome (PCOS) is the most common endocrine abnormality in women of reproductive age. Although its clinical consequences have been known for a long time to extend beyond the reproductive system, with type‐2 diabetes and obesity being the most common, the involvement of the ocular surface in PCOS has been described only more recently. The ocular surface is a morphofunctional unit comprising eyelid margin, tear film, cornea, and conjunctiva. Increasing evidence indicates that these structures are under a sex hormone control and relevant diseases such as ocular allergy and dry eye are often caused by alterations in circulating or local steroid hormones levels. Novel treatments targeting sex hormone receptors on ocular surface epithelial cells are also being developed. In this review we aim to describe the current knowledge on the effects of sex hormones at the ocular surface, with a special focus on the effects of androgen imbalance in PCOS. J. Cell. Physiol. 231: 971–975, 2016.

Pathophysiology of Corneal Dystrophies: From Cellular Genetic Alteration to Clinical Findings

Corneal dystrophies are a heterogeneous group of bilateral, inherited, rare diseases characterized by slowly progressive corneal opacities, that lead to visual impairment. Most of them have an autosomal dominant pattern of inheritance with variable expressivity, but new mutations have been described. Many corneal dystrophies have been genetically characterized and the specific gene mutations identified, such as for the epithelial–stromal TGFBI dystrophies. Current classification systems identified four main groups of corneal dystrophies based on clinical, histologic, and genetic information. Diagnosis is performed during a routine ophthalmic examination that shows typical cellular abnormalities of the corneal epithelium, stroma, or endothelium. Disease progression should be carefully monitored to decide the proper clinical management. The treatment of corneal dystrophies is variable, depending on symptoms, clinical course, severity, and type of dystrophy. Management aimed to reduce symptoms and to improve vision, includes different surgical approaches. Novel cellular and genetic therapeutic approaches are under evaluation. J. Cell. Physiol. 231: 261–269, 2016.

A new scale for the assessment of conjunctival bulbar redness

PURPOSE Current scales for assessment of bulbar conjunctival redness have limitations for evaluating digital images. We developed a scale suited for evaluating digital images and compared it to the Validated Bulbar Redness (VBR) scale. METHODS From a digital image database of 4889 color corrected bulbar conjunctival images, we identified 20 images with varied degrees of redness. These images, ten each of nasal and temporal views, constitute the Digital Bulbar Redness (DBR) scale. The chromaticity of these images was assessed with an established image processing algorithm. Using 100 unique, randomly selected images from the database, three trained, non-physician graders applied the DBR scale and printed VBR scale. Agreement was assessed with weighted Kappa statistics (Kw). RESULTS The DBR scale scores provide linear increments of 10 from 10-100 when redness is measured objectively with an established image processing algorithm. Exact agreement of all graders was 38% and agreement with no more than a difference of ten units between graders was 91%. Kw for agreement between any two graders ranged from 0.57 to 0.73 for the DBR scale and from 0.38 to 0.66 for the VBR scale. The DBR scale allowed direct comparison of digital to digital images, could be used in dim lighting, had both temporal and nasal conjunctival reference images, and permitted viewing reference and test images at the same magnification. CONCLUSION The novel DBR scale, with its objective linear chromatic steps, demonstrated improved reproducibility, fewer visualization artifacts and improved ease of use over the VBR scale for assessing conjunctival redness.

Effect of sex steroid hormone fluctuations in the pathophysiology of male-retinal pigment epithelial cells

Gender‐based differences may influence the occurrence of several ocular conditions suggesting the possibility that fluctuations in sex steroid homeostasis may have direct effects on the eye physiology. Here, we evaluated the effect of sex steroid hormone fluctuations in male retinal pigment epithelial cells, RPEs (ARPE‐19). To mimic hormonal fluctuations occurring during aging, we exposed ARPE‐19 to acute, prolonged or chronic estradiol, and progesterone challenges. We found that chronic estradiol treatment promotes a remarkable necrosis of RPE cells, and does not affect pRb2/p130 or PAI‐2 sub‐cellular localization. In contrast, chronic progesterone exposure induces nuclear subcellular rearrangement of pRb2/p130, co‐immunolocalization of pRb2/p130 with PAI‐2, and accumulation of cells in G2/M phase, which is accompanied by a remarkable reduction of necrosis in favour of apoptosis activation.