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

Completed

• Conditions: Diabetic Retinopathy
• Interventions: Other: curcumin, homotaurine, vitamin D3; Other: control

• Registration Number: NCT04378972
• Lead Sponsor: University of Molise

Brief Summary

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).

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.

Study Timeline

• Study Start: 2019-09-16
• Primary Completion: 2019-11-16
• Study Completion: 2019-12-02
• Status Verified: 2020-05
• Study First Submitted: 2020-05-04
• Study First Submitted QC: 2020-05-06
• Last Update Submitted: 2020-05-06
• Study First Posted: 2020-05-07
• Last Update Posted: 2020-05-07

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 25

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

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
TREATED GROUP	curcumin, homotaurine, vitamin D3	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.
CONTROL GROUP	control	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.

Primary Outcome Measures

Name	Time	Method
pro-inflammatory cytokines analysis	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.

Trial Locations

Locations (1)

University of Molise; 🇮🇹 Campobasso, Italy