Anti-inflammatory Effect of Curcumin, Homotaurine, Vitamin D3 on Human Vitreous in Patients With Diabetic Retinopathy


Dosage of pro-inflammatory cytokines and soluble mediators (TNFα, IL6, IL2 and PDGF-AB) performed on 25 vitreous biopsies taken from patients with diabetic retinopathy and treated with increasing doses of curcumin (0.5uM and 1uM), with or without homotaurine (100uM) and vitamin D3 (50nM).

Full Title of Study: “Analysis of Soluble Mediators of Inflammation and Angiogenesis in the Vitreous of Patients With Diabetic Retinopathy Treated With Curcumin/Homotaurine/Vit. D3”

Study Type

  • Study Type: Observational
  • Study Design
    • Time Perspective: Other
  • Study Primary Completion Date: November 16, 2019

Detailed Description

Diabetic retinopathy is one of the most common complications of diabetes mellitus and is a leading cause of vision loss and blindness in the working-age population worldwide. DR is being recognized as a neurodegenerative disease of the retina as opposed to previously considered solely as a microvascular disease. Progressive blindness is due to the long-term accumulation of pathological abnormalities in the retina of hyperglycemic patients. In the initial phase, non-proliferative diabetic retinopathy (NPDR) is almost asymptomatic with the onset of microhemorrhagic and microischemic episodes and an increase in vascular permeability. Subsequently, the progression of the disease is accompanied by the onset of a chronic inflammatory state and neovascularization in a vicious circle that feeds and determines the accumulation of damage to the retina through hypoxia, oxidative stress and widespread neurodegeneration. Among metabolites, hyperglycemia is known to be the major factor which activates several metabolic pathways harmful for retina. Moreover, an increased level of glutamate has been reported in the diabetic retina and also in the vitreous of diabetic patients, suggesting a neurotoxic role of glutamate which may damage retinal neurons and especially retinal ganglion cells by excitotoxicity. In proliferative diabetic retinopathy (PDR), vitreous humor undergoes structural and molecular changes, with changes also in composition, which play a central role in supporting disease progression.The vitreous, 4 ml in volume, is a transparent gel-like structure which fills the space between the lens and the retina. It is composed of 98-99% of water with traces of cations, ions, proteins (mainly collagen) and polysaccharides such as hyaluronic acid. In PDR patients undergoing pars plana vitrectomy, vitreous samples are characterized by altered levels of bioactive molecules with pro-angiogenic, proinflammatory and neuromodulatory activities. So, it is clear that the vitreous acts as a reservoir of soluble signaling mediators that could exacerbate retinal damage. On the other hand, the vitreous obtained from patients with PDR can be a powerful tool to evaluate the anti-angiogenic / anti-inflammatory activity of new biomolecules that could be potential candidates for the treatment of diabetic vitreoretinopathy. Currently, PDR is treated with laser photocoagulation, vitreoretinal surgery or intravitreal injection of drugs targeted to the vascular endothelial growth factor (VEGF) and steroid agents.However, these protocols are effective in the short term, cause side effects and, above all, are indicated only for advanced stages of the disease. So, noninvasive, nondestructive, and longer-duration treatment options are also needed. Recently, research efforts have been made to identify neuroprotective drugs able to prevent visual field loss and preserve visual function and a promising alternative for the treatment of early-stage NPDR comes from nutraceuticals. In fact, in vitro and in vivo studies have revealed that a variety of nutraceuticals has important antioxidant and anti-inflammatory properties that can compromise the first diabetes-driven molecular events that cause vitreoretinopathy, acting upstream of the disease. Based on the results of several investigations, it is reasonable to assert that a single constituent that affects one target has limited efficacy in preventing the progression of multifactorial diseases. A large body of research revealed that the use of a combination of compounds with synergistic multitarget effects may offer a more powerful approach for disease prevention, including retinal neurodegeneration. In experimental models of retinal neurodegeneration it has been shown that cotreatment of citicoline and homotaurine has a direct neuroprotective effect on primary retinal cells exposed to glutamate toxicity and HG levels. Glutamate-induced excitotoxicity is implicated in the pathophysiology of several degenerative diseases of the retina, including glaucoma. Moreover, HG-induced neurotoxicity is a characteristic of diabetic retinopathy. Curcumin, a yellowish non-flavonoid polyphenol that constitutes the main active compound of Curcuma longa, is widely known for its antioxidant and anti-inflammatory properties . Many studies have also described its marked protective effect on retinal cells against oxidative stress and inflammation. Lastly, vitamin D levels appeared to be lower in diabetes mellitus type 2 patients and this could have therapeutic implications. Therefore, the aim of the investigator's study is to analyze the soluble mediators of inflammation and angiogenesis in the vitreous of patients with diabetic retinopathy treated with homotaurine, curcumin and vitamin D3.


  • Other: curcumin, homotaurine, vitamin D3
    • ELISA tests on supernatants of 25 vitreous biopsies incubated with bioactive molecules at 37 ° C for 20 h. The concentration of soluble mediators was calculated from a calibration curve.
  • Other: control
    • ELISA tests on supernatants of 25 vitreous biopsies. The concentration of soluble mediators was calculated from a calibration curve.

Arms, Groups and Cohorts

    • 25 portions of vitreous samples from 25 eyes of patients operated on vitrectomy for complications from diabetic retinopathy, incubated with curcumin, homotaurine and vitamin D3. The substances will be used individually and in triple association, to evaluate a possible synergistic effect on the expression of inflammatory cytokines and endothelial growth factors.
    • The same fractions of vitreous samples (n = 25) evaluated for the expression of oxidative biomarkers, inflammatory cytokines and metalloproteinases, without prior incubation with the substances of the treated group.

Clinical Trial Outcome Measures

Primary Measures

  • pro-inflammatory cytokines analysis
    • Time Frame: 7 days
    • Evaluation of the anti-inflammatory effect of curcumin, homotaurine and vitamin D3 on the expression of inflammatory cytokines in human vitreous samples of patients suffering from diabetic retinopathy.

Participating in This Clinical Trial

Inclusion Criteria

  • age ≥18 years – patients with diabetic retinopathy requiring vitrectomy – willingness to participate in the study following its indications Exclusion Criteria:

  • previous vitrectomy in the study eye – previous buckle surgery in the study eye – previous intravitreal injection in the study eye – concurrent retinovascular or other ocular inflammatory disease – history of ocular trauma – concomitant intake of any topical or systemic NSAID or corticosteroid therapy – presence of systemic inflammations

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: 80 Years

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • University of Molise
  • Collaborator
    • Ospedale Humanitas Gradenigo, Torino
  • Provider of Information About this Clinical Study
    • Principal Investigator: Ciro Costagliola, Full Professor in Ophthalmology – University of Molise
  • Overall Official(s)
    • Ciro Costagliola, Full Professor, Principal Investigator, University of Molise

Citations Reporting on Results

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Jenkins AJ, Joglekar MV, Hardikar AA, Keech AC, O'Neal DN, Januszewski AS. Biomarkers in Diabetic Retinopathy. Rev Diabet Stud. 2015 Spring-Summer;12(1-2):159-95. doi: 10.1900/RDS.2015.12.159. Epub 2015 Aug 10. Review.

Semeraro F, Cancarini A, dell'Omo R, Rezzola S, Romano MR, Costagliola C. Diabetic Retinopathy: Vascular and Inflammatory Disease. J Diabetes Res. 2015;2015:582060. doi: 10.1155/2015/582060. Epub 2015 Jun 7. Review.

Semeraro F, Russo A, Gambicorti E, Duse S, Morescalchi F, Vezzoli S, Costagliola C. Efficacy and vitreous levels of topical NSAIDs. Expert Opin Drug Deliv. 2015;12(11):1767-82. doi: 10.1517/17425247.2015.1068756. Epub 2015 Jul 14. Review.

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Nawaz IM, Rezzola S, Cancarini A, Russo A, Costagliola C, Semeraro F, Presta M. Human vitreous in proliferative diabetic retinopathy: Characterization and translational implications. Prog Retin Eye Res. 2019 Sep;72:100756. doi: 10.1016/j.preteyeres.2019.03.002. Epub 2019 Apr 2. Review.

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