Cholesterol crystal formation is a unifying pathogenic mechanism in the development of diabetic retinopathy.

AIMS/HYPOTHESIS: Hyper-reflective crystalline deposits found in retinal lesions have been suggested to predict the progression of diabetic retinopathy, but the nature of these structures remains unknown. METHODS: Scanning electron microscopy and immunohistochemistry were used to identify cholesterol crystals (CCs) in human donor, pig and mouse tissue. The effects of CCs were analysed in bovine retinal endothelial cells in vitro and in db/db mice in vivo using quantitative RT-PCR, bulk RNA sequencing, and cell death and permeability assays. Cholesterol homeostasis was determined using 2H2O and 2H7-cholesterol. RESULTS: We identified hyper-reflective crystalline deposits in human diabetic retina as CCs. Similarly, CCs were found in the retina of a diabetic mouse model and a high-cholesterol diet-fed pig model. Cell culture studies demonstrated that treatment of retinal cells with CCs can recapitulate all major pathogenic mechanisms leading to diabetic retinopathy, including inflammation, cell death and breakdown of the blood-retinal barrier. Fibrates, statins and α-cyclodextrin effectively dissolved CCs present in in vitro models of diabetic retinopathy, and prevented CC-induced endothelial pathology. Treatment of a diabetic mouse model with α-cyclodextrin reduced cholesterol levels and CC formation in the retina, and prevented diabetic retinopathy. CONCLUSIONS/INTERPRETATION: We established that cholesterol accumulation and CC formation are a unifying pathogenic mechanism in the development of diabetic retinopathy.

Pilot study for the evaluation of safety profile of a potential inhibitor of SARS-CoV-2 endocytosis.

BACKGROUND AND AIM OF THE WORK: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the current pandemics of coronavirus disease. This virus is able to attack the cells of the airway epithelium by binding to the transmembrane angiotensin I converting enzyme 2 (ACE2). We developed an oral spray that could inhibit the SARS-CoV-2 endocytosis. The spray contains hydroxytyrosol for its anti-viral, anti-inflammatory and anti-oxidant properties, and α-cyclodextrin for its ability to deplete sphingolipids, that form the lipid rafts where ACE2 localizes. The aim of the present pilot multi-centric open non-controlled observational study was to evaluate the safety profile of the "Endovir Stop" spray. METHODS: An MTT test was performed to evaluate cytotoxicity of the spray in two human cell lines. An oxygen radical absorbance capacity assay was performed to evaluate the antioxidant capacity of the spray. The spray was also tested on 87 healthy subjects on a voluntary basis. RESULTS: The MTT test revealed that the spray is not cytotoxic. The ORAC assay showed a good antioxidant capacity for the spray. Endovir Stop tested on healthy volunteers showed the total absence of side effects and drug interactions during the treatment. CONCLUSIONS: We demonstrated that Endovir Stop spray is safe. The next step would be the administration of the efficacy of the spray by testing it to a wider range of people and see whether there is a reduced infection rate of SARS-CoV-2 in the treated subjects than in the non-treated individuals.

Cyclodextrins: Potential therapeutics against atherosclerosis.

Atherosclerosis is an inflammatory disease resulting from subendothelial accumulation of lipoprotein-derived cholesterol in susceptible arterial segments, ultimately leading to the formation of clinically significant atherosclerotic plaques. Despite significant advances in the treatment of atherosclerosis, atherosclerotic cardiovascular diseases remain the leading cause of death and disabilities worldwide. Accordingly, there is an urgent need for novel therapies. Cyclodextrins are cyclic oligosaccharides produced from many sources of starch by enzymatic degradation. The frequently used cyclodextrins are α-, ß-, and γ-cyclodextrins, which are composed of six, seven, and eight glucose moieties, respectively. Especially ß-cyclodextrin can entrap hydrophobic compounds, such as cholesterol, into its hydrophobic cavity and form stable inclusion complexes with cholesterol. This inherent affinity of cyclodextrins has been exploited to extract excess cholesterol from cultured cells, as well as intra- and extracellular cholesterol stores present in atherosclerotic lesions of experimental animals. Accordingly, cyclodextrins could be considered as potentially effective therapeutic agents for the treatment of atherosclerosis. In this review, we address recent advances and the current status of the development of cyclodextrins and provide an update of the latest in vitro and in vivo experiments that pave the way to clinical studies. The emerging therapeutic opportunities by using cyclodextrins could aid us in our efforts to ultimately eradicate the residual risk after other cholesterol-lowering pharmacotherapies, and also reduce the associated burden of premature deaths due to atherosclerotic cardiovascular diseases.

The oligosaccharide α-cyclodextrin has modest effects to slow gastric emptying and modify the glycaemic response to sucrose in healthy older adults.

In healthy older subjects, the glycaemic response to carbohydrate-containing meals is dependent on gastric emptying and intestinal absorption; when the latter is slowed, the magnitude of the rise in glucose is attenuated. The oligosaccharide α-cyclodextrin has been reported to diminish the glycaemic response to starch in young adults; this effect has been attributed to the inhibition of pancreatic amylase. We examined the effects of α-cyclodextrin on gastric emptying of, and the glycaemic and insulinaemic responses to, oral sucrose in healthy older subjects; as sucrose is hydrolysed by intestinal disaccharides, any effect(s) of α-cyclodextrin would not be attributable to amylase inhibition. A total of ten subjects (seven males and three females, age 68-76 years) were studied on 2 d. Gastric emptying, blood glucose and serum insulin were measured after ingestion of a 300 ml drink containing 100 g sucrose, labelled with (99m)Tc-sulphur colloid, with or without 10 g α-cyclodextrin. Gastric emptying was slowed slightly by α-cyclodextrin; this effect was evident between 135 and 195 min and was associated with a slight increase (P < 0·05) in distal stomach retention. After α-cyclodextrin, blood glucose was slightly less (P < 0·05) at 60 min, and serum insulin was less (P < 0·0005) at 90 and 120 min. There was no difference in the incremental areas under the curve (iAUC) for blood glucose, but there was a trend for the iAUC for serum insulin to be lower (P = 0·09) after α-cyclodextrin. We conclude that in a dose of 10 g, α-cyclodextrin has modest effects to slow gastric emptying of, and modify the glycaemic and insulinaemic responses to, oral sucrose, probably due to delayed intestinal carbohydrate absorption.

The beneficial effects of α-cyclodextrin on blood lipids and weight loss in healthy humans.

α-Cyclodextrin (α-CD) is a soluble fiber derived from corn. It has previously been reported that early intervention with Mirafit fbcx, a trademarked name for α-CD, has beneficial effects on weight management in obese individuals with type 2 diabetes, and that it preferentially reduces blood levels of saturated and trans fats in the LDL receptor knockout mice. The current investigation involves overweight but not obese nondiabetic individuals and was intended to confirm the effects of α-CD on both weight management and improving blood lipid levels. Forty-one healthy adults (age: 41.4 ± 13.6 years) participated in this 2-month, double-blinded, crossover study. In 28 compliant participants (8 males and 20 females), when the active phase was compared to the control phase, there were significant decreases in body weight (-0.4 ± 0.2 kg, P < 0.05), serum total cholesterol (mean ± s.e.m., -0.295 ± 0.10 mmol/l, 5.3%, P < 0.02) and low-density lipoprotein (LDL) cholesterol (-0.23 ± 0.11 mmol/l, -6.7%, P < 0.05). Apolipoprotein B (Apo B) (-0.0404 ± 0.02 g/l, -5.6%, P = 0.06) and insulin levels also decreased by 9.5% (-0.16 ± 0.08 pmol/l, P = 0.06) while blood glucose and leptin levels did not change. These results suggest that α-CD exerts its beneficial health effects on body weight and blood lipid profile in healthy nonobese individuals, as previously reported in obese individuals with type 2 diabetes.

Dose-dependent inhibition of the post-prandial glycaemic response to a standard carbohydrate meal following incorporation of alpha-cyclodextrin.

BACKGROUND: This study evaluated the dose-response effects of alpha-cyclodextrin, a cyclic oligosaccharide, on the glycaemic and insulinaemic responses to the consumption of a standard carbohydrate meal. METHODS: In a double-blind, randomised, cross-over design, 10 healthy subjects consumed boiled white rice containing 50 g of digestible carbohydrate to which 0 (control), 2, 5 or 10 g of alpha-cyclodextrin was added. Plasma glucose and insulin concentrations were determined prior to and for 2 h after consumption of each meal. RESULTS: The area under the plasma glucose curve was negatively related to the dose of alpha-cyclodextrin (r(2)=0.97, p=0.02), with the areas being significantly reduced at the 5- and 10-gram doses compared with the control (p<0.05). alpha-Cyclodextrin did not affect the area under the plasma insulin curve (p=0.39). Higher doses of alpha-cyclodextrin resulted in greater satiety, but were associated with reduced palatability and an increased incidence of minor gastrointestinal complaints (stomach ache, nausea, bloating). CONCLUSION: alpha-Cyclodextrin reduces the glycaemic response to a standard carbohydrate meal in a dose-dependent manner and may be useful as an ingredient for reducing the glycaemic impact of such foods.