Marcella Nebbioso

Biomolecular modulation of neurodegenerative events during ageing

The objective is to assess the modulation of retinal and optic nerve degenerative events induced by the combination of α-lipoic acid (ALA) and superoxide dismutase (SOD) in an animal model of ageing. For this study, 24 male Wistar-Harlan strain rats were left to age for up to 24 months. One group of rats was subjected to a diet supplemented with ALA and SOD for 8 weeks, while another group was used as a positive control and not subjected to any dietary treatment. To assess the cytoprotective effects of the antioxidants, a morphological analysis was carried out on sections of retina and optic nerve head, stained with haematoxylin-eosin, followed by an analysis of the modifications to nuclear DNA detected by the TUNEL technique. The lipid peroxidation assay was used to assess the damage induced by oxidative stress at cell membrane level. The molecules involved in apoptosis mediated by oxidative stress, such as caspase-3 and inducible nitric oxide synthase, were also assayed by immunolocalization and western blot. ALA and SOD are able to counteract senile neurodegenerative deterioration to the retina and optic nerve. Indeed, the combination of these antioxidant molecules can reduce oxidative stress levels and thus prevent both nuclear degradation and subsequent cell death.

Curcumin: Therapeutical Potential in Ophthalmology

Curcumin (diferuloylmethane) is the main curcuminoid of the popular Indian spice turmeric (Curcuma longa). In the last 50 years, in vitro and in vivo experiments supported the main role of polyphenols and curcumin for the prevention and treatment of many different inflammatory diseases and tumors.The anti-inflammatory, antioxidant, and antitumor properties of curcumin are due to different cellular mechanisms: this compound, in fact, produces different responses in different cell types. Unfortunately, because of its low solubility and oral bioavailability, the biomedical potential of curcumin is not easy to exploit; for this reason more attention has been given to nanoparticles and liposomes, which are able to improve curcumins bioavailability. Pharmacologically, curcumin does not show any dose-limiting toxicity when it is administered at doses of up to 8 g/day for three months. It has been demonstrated that curcumin has beneficial effects on several ocular diseases, such as chronic anterior uveitis, diabetic retinopathy, glaucoma, age-related macular degeneration, and dry eye syndrome. The purpose of this review is to report what has so far been elucidated about curcumin properties and its potential use in ophthalmology.

SIRT1 silencing confers neuroprotection through IGF-1 pathway activation

The following study demonstrated that, in in vitro differentiated neurons, SIRT1 silencing induced an increase of IGF‐1 protein expression and secretion and of IGF‐1R protein levels which, in turn, prolonged neuronal cell survival in presence of an apoptotic insult. On the contrary, SIRT1 overexpression increased cell death. In particular, IGF‐1 and IGF‐1R expression levels were negatively regulated by SIRT1. In SIRT1 silenced cells, the increase in IGF‐1 and IGF‐1R expression was associated to an increase in AKT and ERK1/2 phosphorylation. Moreover, neuronal differentiation was reduced in SIRT1 overexpressing cells and increased in SIRT1 silenced cells. We conclude that SIRT1 silenced neurons appear more committed to differentiation and more resistant to cell death through the activation of IGF‐1 survival pathway. J. Cell. Physiol. 228: 1754–1761, 2013.

Oxidative Stress in Preretinopathic Diabetes Subjects and Antioxidants

BACKGROUNDnThis study assessed the effect of a systemic oral treatment with antioxidants (AOs) in preretinopathic diabetes (PRD) patients, through the evaluation of oxidative stress in plasma and changes in the full-field electroretinogram (ERG).nnnMETHODSnThirty-two PRD subjects with good metabolic control were recruited. Patients were randomized in two groups, one of which received oral AO treatment with α-lipoic acid at 400u2009mg/day in association with genistein and vitamins, whereas the other group received a placebo. Free radicals and the AO barrier were evaluated in plasma with the Free Radical Analytical System 4 instrument (H&D srl, Parma, Italy), and the same day the electrophysiological response was measured by ERG. These analyses were performed at enrollment and after 30 days of treatment.nnnRESULTSnStatistically significant increases of plasma AO levels and ERG oscillatory potential values were observed in the group treated with AO, but not in the control group.nnnCONCLUSIONSnResults of this preliminary study suggest that an oral treatment with AOs in PRD subjects may have a protective effect on retinal cells, as detected by ERG analysis, through the strengthening of the plasma AO barrier.

Lipoic acid in animal models and clinical use in diabetic retinopathy.

Introduction: Oxidative stress, a consequence of excessive production of reactive oxygen species (ROS), is a factor in the development of many diseases, including diabetes and its complications. Alpha-lipoic acid (ALA), a natural thiol antioxidant, has been shown to have beneficial effects on oxidative stress parameters in various tissues. This article is an up-to-date review of current thinking regarding ALA and its use in providing antioxidant (AO) drug therapy for ocular dysfunction due to diabetic retinopathy (DR). Areas covered: ALA prevents micro- and macro-vascular damage through normalized pathways downstream of mitochondrial overproduction of ROS, and preserves pericyte coverage of retinal capillaries. In addition, clinical studies suggest that oral administration of ALA can improve insulin sensitivity in patients with type-2 diabetes. Moreover, ALA treatment has been shown to suppress expression of vascular endothelial growth factor (VEGF), angiopoietin 2 and erythropoietin via blockade of superoxide formation. Expert opinion: The diverse beneficial effects of ALA, many of which have only recently been uncovered, suggest that it acts by multiple mechanisms on oxidative stress parameters. Consequently, ALA supplementation is an achievable adjunct therapy to help prevent vision loss in diabetic patients. Finally, further research to better understand the mechanism of ALA will be useful for the development of more effective therapies in patients affected by DR.

Psychophysical and Electrophysiological Testing in Ocular Hypertension

Purpose. The purpose of this study was to compare psychophysical and electrophysiological testings in early optic nerve dysfunction in a group of clinically asymptomatic subjects with suspect ocular hypertension (OHT). Methods. Forty eyes of 40 patients with suspect OHT and asymmetrical horizontal cup/disc ratio (0.2/0.4), 22 eyes of 22 patients with open-angle glaucoma (OAG), and 40 eyes of 40 healthy controls were evaluated by using frequency-doubling technology perimetry (FDT), contrast sensitivity (CS), pattern electroretinography (PERG), and pattern visual-evoked potentials (VEP). The VEP were elicited by checkerboard stimuli with large (VEP 120), medium (VEP 45), and small (VEP 15) checks; then the values of the amplitude (A) and latency (L) of P100 peaks were studied. Receiver operator characteristic (ROC) curves were calculated to determine the sensitivity, specificity, and optimal cutoff points of abnormal values. A logistic regression analysis was performed to determine which tests were providing the most useful information. In addition, Kruskal-Wallis test was performed to test the differences between the control group and the OHT group. Results. VEP P100 peak latency (VEP L15 and VEP L45) and amplitude (VEP A120), PERG N95 peak amplitude, CS at medium spatial frequencies (CS 4SF), and FDT pattern standard deviation (PSD) yielded the greatest sensitivity (85.0 to 60.0%) and specificity (80.0 to 60.0%) ratio, displaying the largest ROC curve areas; whereas PERG N95 peak latency ROC curve had the smallest areas. Kruskal-Wallis test showed that most diagnostic tests were able to differentiate the OHT group from the control group. Stepwise logistic regression analysis identified VEP L15 (p < 0.001), CS 4SF (p = 0.023), FDT PSD (p = 0.032), and VEP A120 (p = 0.072) as tests that could be useful to distinguish controls from OHT. Conclusions. Our data confirm that psychophysical and electrophysiological tests are useful for early detection of patients at risk of developing OAG.

High‐mobility group box‐1 (HMGB‐1) and serum soluble receptor for advanced glycation end products (sRAGE) in children affected by vernal keratoconjunctivitis

Vernal keratoconjunctivitis (VKC) is a chronic disease affecting conjunctiva even though the immunopathogenetic mechanisms underlying this inflammation are unclear. The aim of our study is to investigate serum levels of HMGB1 and circulating sRAGE in children affected by VKC before and after treatment with cyclosporine A (CsA) eye drops and in a group of healthy children.

Monoamine oxidase enzymes and oxidative stress in the rat optic nerve: age-related changes

In this study, age‐related changes in the monoamine oxidases (MAO) were studied in the optic nerve (ON) of both young and aged male rats. The aim of the study was to assess the role of MAO in age‐related changes in the rat ON and explain the mechanisms of neuroprotection mediated by MAO‐B‐specific inhibitors. Fifteen three month old and fifteen 26 month old Sprague–Dawley rats were used. The animals were killed by terminal anaesthesia. Staining of MAO, quantitative analysis of images, biochemical assays and statistical analysis of data were carried out. Samples of the ON were washed in water, fixed in Bowen fluid, dehydrated and embedded in Entellan. Histological sections were stained for MAO‐enzymatic activities. The specificity of the reaction was evaluated by incubating control sections in a medium either without substrate or without dye. The quantitative analysis of images was carried out at the same magnification and the same lighting using a Zeiss photomicroscope. The histochemical findings were compared with the biochemical results. After enzymatic staining, MAO could be demonstrated in the ON fibres of both young and aged animals; however, MAO were increased in the nerve fibres of the elderly rats. These morphological findings were confirmed biochemically. The possibility that age‐related changes in MAO levels may be attributed to impaired energy production mechanisms and/or represent the consequence of reduced energy needs is discussed.

Early detection of macular changes with multifocal ERG in patients on antimalarial drug therapy.

PURPOSEnTo compare and to evaluate the use of the multifocal electroretinography (mfERG) to conventional systems in assessing early changes of the retinal electric signals in patients with ocular dysfunction due to antimalarial drug therapy.nnnMETHODSnThis article represents an up-to-date review of the current thoughts regarding the mfERG technique and its use in providing a topographic measure of the retinal electrophysiological activity.nnnRESULTSnVarious investigations have been suggested to be useful in the assessment of toxic retinopathy, but, since they involve subjective responses by the patients and lack of sensibility, the mfERG may be particularly useful for documenting early toxic retinopathy.nnnCONCLUSIONSnA small percentage of patients face retinal functional alterations and ocular lesions and that is possible thanks to the use of lower dosages of hydroxychloroquine (Hy) and chloroquine (CQ), but the problem still remains because of the cumulative dose of the drugs in therapy that many of these patients go through. The mfERG can be considered a good method of early detection and tracking of the progression of macular changes of retinopathy and could occupy a key position in assessing macular changes in patients on antimalarial drug therapy.

Retina in rheumatic diseases: standard full field and multifocal electroretinography in hydroxychloroquine retinal dysfunction.

Background:u2002 The purpose of this study was to evaluate and compare full‐field electroretinography (ERG) and multifocal electroretinography (mfERG) results in detecting retinal dysfunction in a large number of asymptomatic patients treated with hydroxychloroquine (Hy).