Liver X Receptor (LXR) as a Novel Therapeutic Target in Diabetic Retinopathy (DR)

Study Overview
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Brief Summary
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Results from large clinical trials demonstrate a strong association between lipid abnormalities and progression of the most common microvascular complication, diabetic retinopathy (DR). We found that activation of a master regulator of cholesterol metabolism, the nuclear hormone receptors liver X receptors (LXRα/LXRβ), prevents DR in rodent models. In this application, we seek to understand the mechanisms responsible for the beneficial effects of LXR agonists on retina and on bone marrow (BM) to preserve the function of reparative cells while reducing inflammatory cell.

Detailed Description
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Diabetic retinopathy (DR) is a disabling microvascular complication. Despite recent advances using pharmacotherapy, a cure for DR has yet to be realized. Thus, a conceptual and technical breakthrough to identify novel targets, and a strategy to cure this complication is paramount. We believe that the recent clinical evidence from large clinical trials demonstrating a strong association between lipid abnormalities and DR progression and the discovery that activation of the nuclear hormone receptors liver X receptors (LXRα/LXRβ) prevents DR in rodent models offers such a breakthrough. The detrimental effect of dyslipidemia is not limited to the vasculature but also leads to dysfunction of circulating angiogenic cells (CAC) and of macrophages. The endogenous ligands for LXRs are oxidative metabolites of cholesterol that serve as intracellular cholesterol sensors. LXR agonists operate, in part, by transcriptional upregulation of genes involved in promoting cholesterol efflux and inhibition of cholesterol uptake; and by inhibiting inflammation. Our published studies and new preliminary data show that pharmacological LXR activation prevents DR development in both T1D and T2D rodent models. In this application, we seek to understand the mechanisms involved in this beneficial effect. We put forth the hypothesis that LXR activation will restore cholesterol homeostasis in the diabetic retina and correct diabetes-induced bone marrow dysfunction to sustain CAC levels and function and to reduce of myeloid cell production.

Official Title
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LXR as a Novel Therapeutic Target in DR

Conditions
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Diabetic Retinopathy

Intervention / Treatment
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* Biological: blood draw


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Any man or woman between the ages of 21- 98 years of age will be eligible to participate. To participate in the study as a study subject we will require: a) the subject must either carry the diagnosis of diabetes or be a healthy aged control and b) the patient be willing and have the ability to cooperate with the protocol. Exclusion Criteria: Exclusion criteria: We will apply the following exclusion criteria: a) evidence of ongoing acute or chronic infection (HIV, Hepatitis B or C, tuberculosis); b) ongoing malignancy; c) cerebral vascular accident or cerebral vascular procedure; d) current pregnancy; e) history of organ transplantation; f) presence of a graft (to avoid any effect of the graft on inflammatory parameters; g) uremic symptoms, an estimated glomerular filtration rate of less than 20 cc/min (by Modification of Diet in Renal Disease equation), or an albumin of less than 3.6 (to avoid malnutrition as a confounding variable); h) be unwilling to abstain from drinking alcohol and i) patients with anemia. Subjects with AMD, glaucoma, uveitis, known hereditary degenerations or other significant ocular complications other than diabetic retinopathy will be excluded.

Ages Eligible for Study
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Minimum Age: 21 Years
Maximum Age: 98 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Controls<br>Any man or woman between the ages of 21- 98 years of age will be eligible to participate. To participate in the study as a study subject we will require that the subject must carry the diagnosis of healthy control. | Biological: blood draw<br>* Blood sample will be obtained and CD34+ cells will be isolated for functional testing.<br>|
| Diabetic no retinopathy<br>Patients with diabetes but with no evidence of diabetic retinopathy | Biological: blood draw<br>* Blood sample will be obtained and CD34+ cells will be isolated for functional testing.<br>|
| Diabetic with mild retinopathy<br>Diabetics with mild non proliferative diabetic retinopathy (NPDR). | Biological: blood draw<br>* Blood sample will be obtained and CD34+ cells will be isolated for functional testing.<br>|
| Diabetic with moderate retinopathy<br>Diabetics with moderate NPDR | Biological: blood draw<br>* Blood sample will be obtained and CD34+ cells will be isolated for functional testing.<br>|
| Diabetics with severe retinopathy<br>Diabetic with severe NPDR. | Biological: blood draw<br>* Blood sample will be obtained and CD34+ cells will be isolated for functional testing.<br>|
| Diabetics with proliferative diabetic retinopathy (PDR)<br>Diabetics with proliferative diabetic retinopathy (PDR) | Biological: blood draw<br>* Blood sample will be obtained and CD34+ cells will be isolated for functional testing.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Assessing CD34+ cells function | We are isolating CD34+ cells from peripheral blood and then examining the cell membrane characteristics of CD34+ cells and their in vitro function. | from blood draw to 48 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Liver X receptor, Circulating angiogenic cells