Anti-angiogenic and antioxidant effects of axitinib in human retinal endothelial cells: implications in diabetic retinopathy.

Diabetic retinopathy is a secondary microvascular complication of diabetes mellitus. This disease progresses from two stages, non-proliferative and proliferative diabetic retinopathy, the latter characterized by retinal abnormal angiogenesis. Pharmacological management of retinal angiogenesis employs expensive and invasive intravitreal injections of biologic drugs (anti-vascular endothelial growth factor agents). To search small molecules able to act as anti-angiogenic agents, we focused our study on axitinib, which is a tyrosine kinase inhibitor and represents the second line treatment for renal cell carcinoma. Axitinib is an inhibitor of vascular endothelial growth factor receptors, and among the others tyrosine kinase inhibitors (sunitinib and sorafenib) is the most selective towards vascular endothelial growth factor receptors 1 and 2. Besides the well-known anti-angiogenic and immune-modulatory functions, we hereby explored the polypharmacological profile of axitinib, through a bioinformatic/molecular modeling approach and in vitro models of diabetic retinopathy. We showed the anti-angiogenic activity of axitinib in two different in vitro models of diabetic retinopathy, by challenging retinal endothelial cells with high glucose concentration (fluctuating and non-fluctuating). We found that axitinib, along with inhibition of vascular endothelial growth factor receptors 1 (1.82 ± 0.10; 0.54 ± 0.13, phosphorylated protein levels in fluctuating high glucose vs . axitinib 1 µM, respectively) and vascular endothelial growth factor receptors 2 (2.38 ± 0.21; 0.98 ± 0.20, phosphorylated protein levels in fluctuating high glucose vs . axitinib 1 µM, respectively), was able to significantly reduce (p < 0.05) the expression of Nrf2 (1.43 ± 0.04; 0.85 ± 0.01, protein levels in fluctuating high glucose vs . axitinib 1 µM, respectively) in retinal endothelial cells exposed to high glucose, through predicted Keap1 interaction and activation of melanocortin receptor 1. Furthermore, axitinib treatment significantly (p < 0.05) decreased reactive oxygen species production (0.90 ± 0.10; 0.44 ± 0.06, fluorescence units in high glucose vs . axitinib 1 µM, respectively) and inhibited ERK pathway (1.64 ± 0.09; 0.73 ± 0.06, phosphorylated protein levels in fluctuating high glucose vs . axitinib 1 µM, respectively) in HRECs exposed to high glucose. The obtained results about the emerging polypharmacological profile support the hypothesis that axitinib could be a valid candidate to handle diabetic retinopathy, with ancillary mechanisms of action.

Ocular pharmacological and biochemical profiles of 6-thioguanine: a drug repurposing study.

Introduction: The purine analog 6-thioguanine (6TG), an old drug approved in the 60s to treat acute myeloid leukemia (AML), was tested in the diabetic retinopathy (DR) experimental in vivo setting along with a molecular modeling approach. Methods: A computational analysis was performed to investigate the interaction of 6TG with MC1R and MC5R. This was confirmed in human umbilical vein endothelial cells (HUVECs) exposed to high glucose (25 mM) for 24 h. Cell viability in HUVECs exposed to high glucose and treated with 6TG (0.05-0.5-5 µM) was performed. To assess tube formation, HUVECs were treated for 24 h with 6TG 5 µM and AGRP (0.5-1-5 µM) or PG20N (0.5-1-5-10 µM), which are MC1R and MC5R antagonists, respectively. For the in vivo DR setting, diabetes was induced in C57BL/6J mice through a single streptozotocin (STZ) injection. After 2, 6, and 10 weeks, diabetic and control mice received 6TG intravitreally (0.5-1-2.5 mg/kg) alone or in combination with AGRP or PG20N. Fluorescein angiography (FA) was performed after 4 and 14 weeks after the onset of diabetes. After 14 weeks, mice were euthanized, and immunohistochemical analysis was performed to assess retinal levels of CD34, a marker of endothelial progenitor cell formation during neo-angiogenesis. Results: The computational analysis evidenced a more stable binding of 6TG binding at MC5R than MC1R. This was confirmed by the tube formation assay in HUVECs exposed to high glucose. Indeed, the anti-angiogenic activity of 6TG was eradicated by a higher dose of the MC5R antagonist PG20N (10 µM) compared to the MC1R antagonist AGRP (5 µM). The retinal anti-angiogenic effect of 6TG was evident also in diabetic mice, showing a reduction in retinal vascular alterations by FA analysis. This effect was not observed in diabetic mice receiving 6TG in combination with AGRP or PG20N. Accordingly, retinal CD34 staining was reduced in diabetic mice treated with 6TG. Conversely, it was not decreased in diabetic mice receiving 6TG combined with AGRP or PG20N. Conclusion: 6TG evidenced a marked anti-angiogenic activity in HUVECs exposed to high glucose and in mice with DR. This seems to be mediated by MC1R and MC5R retinal receptors.

Integrating network pharmacology: The next-generation approach in ocular drug discovery.

With the spread of the "omics" sciences, the approaches of systems biology can be considered as new paradigms of pharmacological research for discovery of novel targets and/or treatments for complex multifactorial diseases. Data from omics sciences can be used for the design of biologic networks, that in turn can be quantitatively analyzed to identify new pharmacological targets. In this review, we will introduce the concept of network pharmacology, particularly the application of this innovative approach in the field of ocular pharmacology, with a focus on retinal diseases such as diabetic retinopathy (DR), age-related macular degeneration (AMD) and glaucoma.

Vitamin D3 preserves blood retinal barrier integrity in an in vitro model of diabetic retinopathy.

The impairment of the blood retinal barrier (BRB) represents one of the main features of diabetic retinopathy, a secondary microvascular complication of diabetes. Hyperglycemia is a triggering factor of vascular cells damage in diabetic retinopathy. The aim of this study was to assess the effects of vitamin D3 on BRB protection, and to investigate its regulatory role on inflammatory pathways. We challenged human retinal endothelial cells with high glucose (HG) levels. We found that vitamin D3 attenuates cell damage elicited by HG, maintaining cell viability and reducing the expression of inflammatory cytokines such as IL-1ß and ICAM-1. Furthermore, we showed that vitamin D3 preserved the BRB integrity as demonstrated by trans-endothelial electrical resistance, permeability assay, and cell junction morphology and quantification (ZO-1 and VE-cadherin). In conclusion this in vitro study provided new insights on the retinal protective role of vitamin D3, particularly as regard as the early phase of diabetic retinopathy, characterized by BRB breakdown and inflammation.

The P2X7 receptor as a new pharmacological target for retinal diseases.

Purinergic ionotropic receptors, such as the P2X7 receptor, are activated by extracellular adenosine triphosphate (ATP). The P2X7 receptor is a trimeric ATP-gated cation channel and its activation results in several downstream events, including the release of proinflammatory mediators and cell damage. The P2X7 receptor has been studied as a pharmacological target for inflammatory and neuroinflammatory diseases, and preclinical studies have recently provided evidence that P2X7 receptor activation is implicated in pathophysiology of several retinal age-related diseases. These diseases are devastating conditions that have an deep impact on the quality of life of patients and on the health systems of all countries. In this review, we discuss the role of the P2X7 receptor in retinal age-related conditions such as glaucoma, age-related macular degeneration, and diabetic retinopathy. Furthermore, we focus on the pharmacological modulation of the P2X7 receptor that could have a relevant clinical impact to prevent retinal diseases.

Do Extracellular RNAs Provide Insight into Uveal Melanoma Biology?

Uveal melanoma (UM) is the most common primary intraocular malignant tumor in adults, showing a high mortality due to metastasis. Although it is considered a rare disease, a growing number of papers have reported altered levels of RNAs (i.e., coding and non-coding RNAs) in cancerous tissues and biological fluids from UM patients. The presence of circulating RNAs, whose dysregulation is associated with UM, paved the way to the possibility of exploiting it for diagnostic and prognostic purposes. However, the biological meaning and the origin of such RNAs in blood and ocular fluids of UM patients remain unexplored. In this review, we report the state of the art of circulating RNAs in UM and debate whether the amount and types of RNAs measured in bodily fluids mirror the RNA alterations from source cancer cells. Based on literature data, extracellular RNAs in UM patients do not represent, with rare exceptions, a snapshot of RNA dysregulations occurring in cancerous tissues, but rather the complex and heterogeneous outcome of a systemic dysfunction, including immune system activity, that modifies the mechanisms of RNA delivery from several cell types.

Effects of Vitamin D3 and Meso-Zeaxanthin on Human Retinal Pigmented Epithelial Cells in Three Integrated in vitro Paradigms of Age-Related Macular Degeneration.

Age-related macular degeneration (AMD) is a degenerative retinal disease and one of major causes of irreversible vision loss. AMD has been linked to several pathological factors, such as oxidative stress and inflammation. Moreover, Aß (1-42) oligomers have been found in drusen, the extracellular deposits that accumulate beneath the retinal pigmented epithelium in AMD patients. Hereby, we investigated the hypothesis that treatment with 1,25(OH) 2D3 (vitamin D3) and meso-zeaxathin, physiologically present in the eye, would counteract the toxic effects of three different insults on immortalized human retinal pigmented epithelial cells (ARPE-19). Specifically, ARPE-19 cells have been challenged with Aß (1-42) oligomers, H2O2, LPS, and TNF-α, respectively. In the present study, we demonstrated that the combination of 1,25(OH)2D3 and meso-zeaxanthin significantly counteracted the cell damage induced by the three insults, at least in these in vitro integrated paradigms of AMD. These results suggest that combination of 1,25(OH)2D3 and meso-zeaxathin could be a useful approach to contrast pathological features of AMD, such as retinal inflammation and oxidative stress.

Fingolimod and Diabetic Retinopathy: A Drug Repurposing Study.

This study aimed to investigate the interactions between fingolimod, a sphingosine 1-phosphate receptor (S1PR) agonist, and melanocortin receptors 1 and 5 (MCR1, MCR5). In particular, we investigated the effects of fingolimod, a drug approved to treat relapsing-remitting multiple sclerosis, on retinal angiogenesis in a mouse model of diabetic retinopathy (DR). We showed, by a molecular modeling approach, that fingolimod can bind with good-predicted affinity to MC1R and MC5R. Thereafter, we investigated the fingolimod actions on retinal MC1Rs/MC5Rs in C57BL/6J mice. Diabetes was induced in C57BL/6J mice through streptozotocin injection. Diabetic and control C57BL/6J mice received fingolimod, by oral route, for 12 weeks and a monthly intravitreally injection of MC1R antagonist (AGRP), MC5R antagonist (PG20N), and the selective S1PR1 antagonist (Ex 26). Diabetic animals treated with fingolimod showed a decrease of retinal vascular endothelial growth factor A (VEGFA) and vascular endothelial growth factor receptors 1 and 2 (VEGFR1 and VEGFR2), compared to diabetic control group. Fingolimod co-treatment with MC1R and MC5R selective antagonists significantly (p < 0.05) increased retinal VEGFR1, VEGFR2, and VEGFA levels compared to mice treated with fingolimod alone. Diabetic animals treated with fingolimod plus Ex 26 (S1PR1 selective blocker) had VEGFR1, VEGFR2, and VEGFA levels between diabetic mice group and the group of diabetic mice treated with fingolimod alone. This vascular protective effect of fingolimod, through activation of MC1R and MC5R, was evidenced also by fluorescein angiography in mice. Finally, molecular dynamic simulations showed a strong similarity between fingolimod and the MC1R agonist BMS-470539. In conclusion, the anti-angiogenic activity exerted by fingolimod in DR seems to be mediated not only through S1P1R, but also by melanocortin receptors.

Targeting the miRNA-155/TNFSF10 network restrains inflammatory response in the retina in a mouse model of Alzheimer's disease.

Age-related disorders, such as Alzheimer's disease (AD) and age-related macular degeneration (AMD) share common features such as amyloid-ß (Aß) protein accumulation. Retinal deposition of Aß aggregates in AMD patients has suggested a potential link between AMD and AD. In the present study, we analyzed the expression pattern of a focused set of miRNAs, previously found to be involved in both AD and AMD, in the retina of a triple transgenic mouse model of AD (3xTg-AD) at different time-points. Several miRNAs were differentially expressed in the retina of 3xTg-AD mice, compared to the retina of age-matched wild-type (WT) mice. In particular, bioinformatic analysis revealed that miR-155 had a central role in miRNA-gene network stability, regulating several pathways, including apoptotic and inflammatory signaling pathways modulated by TNF-related apoptosis-inducing ligand (TNFSF10). We showed that chronic treatment of 3xTg-AD mice with an anti-TNFSF10 monoclonal antibody was able to inhibit the retinal expression of miR-155, which inversely correlated with the expression of its molecular target SOCS-1. Moreover, the fine-tuned mechanism related to TNFSF10 immunoneutralization was tightly linked to modulation of TNFSF10 itself and its death receptor TNFRSF10B, along with cytokine production by microglia, reactive gliosis, and specific AD-related neuropathological hallmarks (i.e., Aß deposition and Tau phosphorylation) in the retina of 3xTg-AD mice. In conclusion, immunoneutralization of TNFSF10 significantly preserved the retinal tissue in 3xTg-AD mice, suggesting its potential therapeutic application in retinal degenerative disorders.

1α,25-dihydroxyvitamin D3 protects retinal ganglion cells in glaucomatous mice.

BACKGROUND: Glaucoma is an optic neuropathy characterized by loss of function and death of retinal ganglion cells (RGCs), leading to irreversible vision loss. Neuroinflammation is recognized as one of the causes of glaucoma, and currently no treatment is addressing this mechanism. We aimed to investigate the anti-inflammatory and neuroprotective effects of 1,25(OH)2D3 (1α,25-dihydroxyvitamin D3, calcitriol), in a genetic model of age-related glaucomatous neurodegeneration (DBA/2J mice). METHODS: DBA/2J mice were randomized to 1,25(OH)2D3 or vehicle treatment groups. Pattern electroretinogram, flash electroretinogram, and intraocular pressure were recorded weekly. Immunostaining for RBPMS, Iba-1, and GFAP was carried out on retinal flat mounts to assess retinal ganglion cell density and quantify microglial and astrocyte activation, respectively. Molecular biology analyses were carried out to evaluate retinal expression of pro-inflammatory cytokines, pNFκB-p65, and neuroprotective factors. Investigators that analysed the data were blind to experimental groups, which were unveiled after graph design and statistical analysis, that were carried out with GraphPad Prism. Several statistical tests and approaches were used: the generalized estimated equations (GEE) analysis, t-test, and one-way ANOVA. RESULTS: DBA/2J mice treated with 1,25(OH)2D3 for 5 weeks showed improved PERG and FERG amplitudes and reduced RGCs death, compared to vehicle-treated age-matched controls. 1,25(OH)2D3 treatment decreased microglial and astrocyte activation, as well as expression of inflammatory cytokines and pNF-κB-p65 (p < 0.05). Moreover, 1,25(OH)2D3-treated DBA/2J mice displayed increased mRNA levels of neuroprotective factors (p < 0.05), such as BDNF. CONCLUSIONS: 1,25(OH)2D3 protected RGCs preserving retinal function, reducing inflammatory cytokines, and increasing expression of neuroprotective factors. Therefore, 1,25(OH)2D3 could attenuate the retinal damage in glaucomatous patients and warrants further clinical evaluation for the treatment of optic neuropathies.

Glucose-impaired Corneal Re-epithelialization Is Promoted by a Novel Derivate of Dimethyl Fumarate.

Glucose induces corneal epithelial dysfunctions characterized by delayed wound repair. Nuclear erythroid 2-related factor 2 (Nrf2) mediates cell protection mechanisms even through the Heme oxygenase-1 (HO-1) up-regulation. Here, we synthesized new HO-1 inducers by modifying dimethyl fumarate (DMF) and used docking studies to select VP13/126 as a promising compound with the best binding energy to Kelch-like ECH-associated protein 1 (keap1), which is the the regulator of Nrf2 nuclear translocation. We verified if VP13/126 protects SIRC cells from hyperglycemia compared to DMF. SIRC were cultured in normal (5 mM) or high glucose (25 mM, HG) in presence of DMF (1-25 µM) or VP13/126 (0.1-5 µM) with or without ERK1/2 inhibitor PD98059 (15 µM). VP13/126 was more effective than DMF in the prevention of HG-induced reduction of cell viability and proliferation. Reduction of wound closure induced by HG was similarly counteracted by 1 µM VP13/126 and 10 µM DMF. VP13/126 strongly increased phospho/total ERK1/2 and restored HO-1 protein in HG-treated SIRC; these effects are completely counteracted by PD98059. Moreover, high-content screening analysis showed a higher rate of Nrf2 nuclear translocation induced by VP13/126 than DMF in HG-stimulated SIRC. These data indicate that VP13/126 exerts remarkable pro-survival properties in HG-stimulated SIRC, promoting the Nrf2/HO-1 axis.

Assessment of a New Nanostructured Microemulsion System for Ocular Delivery of Sorafenib to Posterior Segment of the Eye.

Eye drop formulations allowing topical treatment of retinal pathologies have long been sought as alternatives to intravitreal administration. This study aimed to assess whether a novel nanostructured microemulsions system (NaMESys) could be usefully employed to deliver sorafenib to the retina following topical instillation. NaMESys carrying 0.3% sorafenib (NaMESys-SOR) proved to be cytocompatible in vitro on rabbit corneal cells, and well-tolerated following b.i.d. ocular administration to rabbits during a 3-month study. In rats subject to retinal ischemia-reperfusion, NaMESys-SOR significantly inhibited retinal expression of tumor necrosis factor-alpha (TNFα, 20.7%) and inducible nitric oxide synthase (iNos, 87.3%) mRNAs in comparison to controls. Similarly, in streptozotocin-induced diabetic rats, NaMESys-SOR inhibited retinal expression of nuclear factor kappa B (NFκB), TNFα, insulin like growth factor 1 (IGF1), IGF1 receptor (IGF1R), vascular endothelial growth factor receptor 1 (VEGFR1) and 2 (VEGFR2) mRNAs by three-fold on average compared to controls. Furthermore, a reduction in TNFα, VEGFR1 and VEGFR2 protein expression was observed by western blot. Moreover, in mice subject to laser-induced choroidal neovascularization, NaMESys-SOR significantly inhibited neovascular lesions by 54%. In conclusion, NaMESys-SOR was shown to be a well-tolerated ophthalmic formulation able to deliver effective amounts of sorafenib to the retina, reducing proinflammatory and pro-angiogenic mediators in reliable models of proliferative retinopathies. These findings warrant further investigations on the full therapeutic potential of NaMESys-SOR eye drops, aiming to address unmet needs in the pharmacotherapy of retinal neovascular diseases.

Circulating miRNAs in diabetic retinopathy patients: Prognostic markers or pharmacological targets?

In this study we analyzed the expression of circulating miRNAs, in the serum of diabetic retinopathy (DR) patients. Five miRNAs (hsa-miR-195-5p, hsa-miR-20a-5p, hsa-miR-20b-5p, hsa-miR-27b-3p and hsa-miR-451a) were validated as biomarkers for stratification of DR stages, from the early non-proliferative (NPDR) to the late proliferative (PDR) phase. Furthermore, circulating levels of these miRNAs correlated with retinal hyper-reflective spots (HRS), assessed by optical coherence tomography (OCT). The number of HRS increased with worsening of DR stages. On the contrary, no significant vascular density differences between NPDR and PDR patients were detected by angio-OCT (OCTA). A post-hoc bioinformatics analysis associated these five miRNAs to target genes belonging to the "Tumor Necrosis Factor alfa signaling" pathway, and several molecules were predicted to modify miRNAs expression. In conclusion, correlation between specific circulating miRNAs and intraretinal hyper-reflective spots was demonstrated, confirming that these miRNAs were validated as prognostic biomarkers, and also as potential pharmacological targets, warranting further clinical evaluation to explore novel therapeutics for diabetic retinopathy.

Molecular Dynamics Simulation Techniques as Tools in Drug Discovery and Pharmacology: A Focus on Allosteric Drugs.

Allosteric drugs are ligands that when bound to an allosteric site modify the conformational state of the pharmacological target, leading then to a modification of functional response upon binding of the endogenous ligand. Pharmacological targets are defined as biological entities, to which a ligand/drug binds and leads to a functional effect. Pharmacological targets can be proteins or nucleic acids. Computational approaches such as molecular dynamics (MD) sped up discovery and identification of allosteric binding sites and allosteric ligands. Classical all-atom and hybrid classical/quantum MD simulations can be generalized as simulation techniques aimed at analysis of atoms and molecular motion. Main limitations of MD simulations are related to high computational costs, that in turn limit the conformational sampling of biological systems. Indeed, other techniques have been developed to overcome limitations of MD, such as enhanced sampling MD simulations. In this chapter, classical MD and enhanced sampling MD simulations will be described, along with their application to drug discovery, with a focus on allosteric drugs.

Caffeine Protects Against Retinal Inflammation.

Caffeine, one of the most consumed central nervous system (CNS) stimulants, is an antagonist of A1 and A2A adenosine receptors. In this study, we investigated the potential protective effects of this methylxanthine in the retinal tissue. We tested caffeine by using in vitro and in vivo paradigms of retinal inflammation. Human retinal pigment epithelial cells (ARPE-19) were exposed to lipopolysaccharide (LPS) with or without caffeine. This latter was able to reduce the inflammatory response in ARPE-19 cells exposed to LPS, attenuating the release of IL-1ß, IL-6, and TNF-α and the nuclear translocation of p-NFκB. Additionally, caffeine treatment restored the integrity of the ARPE-19 monolayer assessed by transepithelial electrical resistance (TEER) and the sodium fluorescein permeability test. Finally, the ischemia reperfusion (I/R) injury model was used in C57BL/6J mice to induce retinal inflammation and investigate the effects of caffeine treatment. Mouse eyes were treated topically with caffeine, and a pattern electroretinogram (PERG) was used to assess the retinal ganglion cell (RGC) function; furthermore, we evaluated the levels of IL-6 and BDNF in the retina. Retinal BDNF dropped significantly (p < 0.05) in the I/R group compared to the control group (normal mice); on the contrary, caffeine treatment maintained physiological levels of BDNF in the retina of I/R eyes. Caffeine was also able to reduce IL-6 mRNA levels in the retina of I/R eyes. In conclusion, these findings suggest that caffeine is a good candidate to counteract inflammation in retinal diseases.

Dihydrotanshinone, a Natural Diterpenoid, Preserves Blood-Retinal Barrier Integrity via P2X7 Receptor.

Activation of P2X7 signaling, due to high glucose levels, leads to blood retinal barrier (BRB) breakdown, which is a hallmark of diabetic retinopathy (DR). Furthermore, several studies report that high glucose (HG) conditions and the related activation of the P2X7 receptor (P2X7R) lead to the over-expression of pro-inflammatory markers. In order to identify novel P2X7R antagonists, we carried out virtual screening on a focused compound dataset, including indole derivatives and natural compounds such as caffeic acid phenethyl ester derivatives, flavonoids, and diterpenoids. Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) rescoring and structural fingerprint clustering of docking poses from virtual screening highlighted that the diterpenoid dihydrotanshinone (DHTS) clustered with the well-known P2X7R antagonist JNJ47965567. A human-based in vitro BRB model made of retinal pericytes, astrocytes, and endothelial cells was used to assess the potential protective effect of DHTS against HG and 2'(3')-O-(4-Benzoylbenzoyl)adenosine-5'-triphosphate (BzATP), a P2X7R agonist, insult. We found that HG/BzATP exposure generated BRB breakdown by enhancing barrier permeability (trans-endothelial electrical resistance (TEER)) and reducing the levels of ZO-1 and VE-cadherin junction proteins as well as of the Cx-43 mRNA expression levels. Furthermore, HG levels and P2X7R agonist treatment led to increased expression of pro-inflammatory mediators (TLR-4, IL-1ß, IL-6, TNF-α, and IL-8) and other molecular markers (P2X7R, VEGF-A, and ICAM-1), along with enhanced production of reactive oxygen species. Treatment with DHTS preserved the BRB integrity from HG/BzATP damage. The protective effects of DHTS were also compared to the validated P2X7R antagonist, JNJ47965567. In conclusion, we provided new findings pointing out the therapeutic potential of DHTS, which is an inhibitor of P2X7R, in terms of preventing and/or counteracting the BRB dysfunctions elicited by HG conditions.

Novel Heme Oxygenase-1 (HO-1) Inducers Based on Dimethyl Fumarate Structure.

Novel heme oxygenase-1 (HO-1) inducers based on dimethyl fumarate (DMF) structure are reported in this paper. These compounds are obtained by modification of the DMF backbone. Particularly, maintaining the α, ß-unsaturated dicarbonyl function as the central chain crucial for HO-1 induction, different substituted or unsubstituted phenyl rings are introduced by means of an ester or amide linkage. Symmetric and asymmetric derivatives are synthesized. All compounds are tested on a human hepatic stellate cell line LX-2 to assay their capacity for modifying HO-1 expression. Compounds 1b, 1l and 1m stand out for their potency as HO-1 inducers, being 2-3 fold more active than DMF, and for their ability to reverse reactive oxygen species (ROS) production mediated using palmitic acid (PA). These properties, coupled with a low toxicity toward LX-2 cell lines, make these compounds potentially useful for treatment of diseases in which HO-1 overexpression may counteract inflammation, such as hepatic fibrosis. Docking studies show a correlation between predicted binding free energy and experimental HO-1 expression data. These preliminary results may support the development of new approaches in the management of liver fibrosis.

TGF-ß Serum Levels in Diabetic Retinopathy Patients and the Role of Anti-VEGF Therapy.

Transforming growth factor ß1 (TGFß1) is a proinflammatory cytokine that has been implicated in the pathogenesis of diabetic retinopathy (DR), particularly in the late phase of disease. The aim of the present study was to validate serum TGFß1 as a diagnostic and prognostic biomarker of DR stages. Thirty-eight subjects were enrolled and, after diagnosis and evaluation of inclusion and exclusion criteria, were assigned to six groups: (1) healthy age-matched control, (2) diabetic without DR, (3) non-proliferative diabetic retinopathy (NPDR) naïve to treatment, (4) NPDR treated with intravitreal (IVT) aflibercept, (5) proliferative diabetic retinopathy (PDR) naïve to treatment and (6) PDR treated with IVT aflibercept. Serum levels of vascular endothelial growth factor A (VEGF-A), placental growth factor (PlGF) and TGFß1 were measured by means of enzyme-linked immunosorbent assay (ELISA). Foveal macular thickness (FMT) in enrolled subjects was evaluated by means of structural-optical coherence tomography (S-OCT). VEGF-A serum levels decreased in NPDR and PDR patients treated with aflibercept, compared to naïve DR patients. PlGF serum levels were modulated only in aflibercept-treated NPDR patients. Particularly, TGFß1 serum levels were predictive of disease progression from NPDR to PDR. A Multivariate ANOVA analysis (M-ANOVA) was also carried out to assess the effects of fixed factors on glycated hemoglobin (HbA1c) levels, TGFß1, and diabetes duration. In conclusion, our data have strengthened the hypothesis that TGFß1 would be a biomarker and pharmacological target of diabetic retinopathy.

Stabilization of HIF-1α in Human Retinal Endothelial Cells Modulates Expression of miRNAs and Proangiogenic Growth Factors.

Retinal hypoxia is one of the causative factors of diabetic retinopathy and is also one of the triggers of VEGF release. We hypothesized that specific dysregulated miRNAs in diabetic retinopathy could be linked to hypoxia-induced damage in human retinal endothelial cells (HRECs). We investigated in HRECs the effects of chemical (CoCl2) hypoxia on the expression of HIF-1α, VEGF, PlGF, and of a focused set of miRNAs. We found that miR-20a-5p, miR-20b-5p, miR-27a-3p, miR-27b-3p, miR-206-3p, miR-381-3p correlated also with expression of TGFß signaling pathway genes in HRECs, challenged with chemical hypoxic stimuli. In conclusion, our data suggest that retinal angiogenesis would be promoted, at least under HIF-1α activation, by upregulation of PlGF and other factors such as miRNAs, VEGFA, and TGFß1.