Association of Zinc Status with Matrix Metalloproteinases, Advanced Glycation End-Products, and Blood Pressure in Patients with Chronic Kidney Disease

Inflammation, oxidative stress, and hypertension trigger the development of chronic kidney disease (CKD). Zinc is known to have antioxidant and anti-inflammatory properties and a possible role in regulating blood pressure. The aim of this study was to investigate the correlation of serum zinc with matrix metalloproteinase-2 and-9 (MMP-2, MMP-9), advanced glycation end products (AGEs), and blood pressure in patients with CKD. This cross-sectional study included 90 patients with CKD. Serum zinc and the levels of MMP-2, MMP-9, AGEs, and creatinine were measured using validated biochemical methods. Three 24-h food recalls were completed to evaluate dietary zinc intake. Systolic and diastolic blood pressure (SBP, DBP) were measured using a digital sphygmomanometer. Participants' mean age was 60.68 ± 8.81 years. The prevalence of zinc deficiency in our participants was 10%. Serum zinc was negatively correlated with MMP-9 (r =  - 0.231, p = 0.032) and creatinine (r =  - 0.304, p = 0.004). However, after adjusting for confounding variables, the association between serum zinc and MMP-9 was near the significance level (β =  - 0.174, p = 0.09) and zinc remained in the model as one of the predictors. Serum zinc was positively correlated with the dietary intake of zinc (r = 0.241, p = 0.025) and estimated glomerular filtration rate (eGFR) (r = 0.259, p = 0.015). In conclusion, our results showed that serum zinc might be one of the predictors of serum MMP-9 in patients with CKD. In addition, serum zinc was positively associated with its dietary intake and eGFR. Future longitudinal studies or clinical trials are required to reveal any causal association between zinc status and profibrotic or inflammatory biomarkers among patients with CKD.

Research Advances on the Damage Mechanism of Skin Glycation and Related Inhibitors

Our skin is an organ with the largest contact area between the human body and the external environment. Skin aging is affected directly by both endogenous factors and exogenous factors (e.g., UV exposure). Skin saccharification, a non-enzymatic reaction between proteins, e.g., dermal collagen and naturally occurring reducing sugars, is one of the basic root causes of endogenous skin aging. During the reaction, a series of complicated glycation products produced at different reaction stages and pathways are usually collectively referred to as advanced glycation end products (AGEs). AGEs cause cellular dysfunction through the modification of intracellular molecules and accumulate in tissues with aging. AGEs are also associated with a variety of age-related diseases, such as diabetes, cardiovascular disease, renal failure (uremia), and Alzheimer's disease. AGEs accumulate in the skin with age and are amplified through exogenous factors, e.g., ultraviolet radiation, resulting in wrinkles, loss of elasticity, dull yellowing, and other skin problems. This article focuses on the damage mechanism of glucose and its glycation products on the skin by summarizing the biochemical characteristics, compositions, as well as processes of the production and elimination of AGEs. One of the important parts of this article would be to summarize the current AGEs inhibitors to gain insight into the anti-glycation mechanism of the skin and the development of promising natural products with anti-glycation effects.

Accumulation of Advanced Glycation End-Products in the Body and Dietary Habits

The formation of advanced glycation end-products (AGE) in tissues is a physiological process; however, excessive production and storage are pathological and lead to inflammation. A sedentary lifestyle, hypercaloric and high-fructose diet and increased intake of processed food elements contribute to excessive production of compounds, which are created in the non-enzymatic multi-stage glycation process. The AGE’s sources can be endogenous and exogenous, mainly due to processing food at high temperatures and low moisture, including grilling, roasting, and frying. Accumulation of AGE increases oxidative stress and initiates various disorders, leading to the progression of atherosclerosis, cardiovascular disease, diabetes and their complications. Inborn defensive mechanisms, recovery systems, and exogenous antioxidants (including polyphenols) protect from excessive AGE accumulation. Additionally, numerous products have anti-glycation properties, occurring mainly in fruits, vegetables, herbs, and spices. It confirms the role of diet in the prevention of civilization diseases.

The effect of resveratrol on advanced glycation end products in diabetes mellitus: a systematic review

Advanced glycation end products (AGEs) lead to chronic oxidative stress and inflammation, which in turn augment diabetes complications. Resveratrol plays a potential role in relation to diabetes due to improving of hyperglycemia, oxidative stress, and inflammation. The aim of this review was to evaluate the scientific literature to identify the impacts of resveratrol on the accumulation of AGEs. The literature was searched in the online databases, viz. PubMed, SCOPUS, Embase, ProQuest, and Google Scholar until May 2019. From a total of 338 retrieved articles, 10 papers were eligible for the present analysis. Except one clinical trial, all studies were conducted on animals. All the included studies, except one, showed inhibitory effects of resveratrol on the accumulation of AGE or receptor for AGEs. The findings indicate that resveratrol is a potential protective agent against the accumulation of AGEs. There is, however, the need for future studies to investigate this effect on human.

Zinc supplementation prior to heat shock enhances HSP70 synthesis through HSF1 phosphorylation at serine 326 in human peripheral mononuclear cells

Zinc supplementation prior to heat shock increases HSP70 (Heat shock protein 70) expression, which has cytoprotective effects in tissue cells during inflammation. Effects of zinc deficiency in this regard are...

Zinc status, insulin resistance and glycoxidative stress in elderly subjects with type 2 diabetes mellitus

Zinc deficiencies have been reported in numerous pathologies, such as diabetes mellitus, but also in the physiological process of ageing. Similarly, the end products of glycoxidation processes, advanced glycation end products (AGEs), are damaging compounds, a myriad of reports linking them to the development and progression of several age-associated chronic diseases. The aim of the present study was to analyze the relationships between zinc status, glycoxidative stress and insulin resistance (IR) in elderly subjects with type 2 diabetes mellitus (T2DM). A group of 52 non-smoking subjects (9 men and 43 women, aged 65-83 years) were enrolled in this cross-sectional study: 27 patients with T2DM, and 25 apparently healthy control subjects. Serum zinc (Zn) levels were assessed using a commercial kit based on an end-point colorimetric method, and serum AGEs were evaluated with a fluorimetric analytic procedure. The calculated glucose-to-zinc ratio (Gly/Zn), insulin-to-zinc ratio (Ins/Zn) and insulin-zinc resistance index (HOMA-IR/Zn) were further used to study the associations between serum Zn levels, secretory function of β-pancreatic cells and AGEs. T2DM patients presented significantly higher serum insulin and Zn levels, as compared to the controls. We found a significant inverse correlation between Zn and AGEs, and a strong positive correlation between AGEs and the Gly/Zn ratio, suggesting that both Zn and AGEs are biomarkers that could reflect the persistence of hyperglycemia. We identified new surrogate biomarkers useful for the assessment of glycemic control with great potential for the development of preventive and therapeutic strategies for elderly diabetics, based on the evaluation of serum Zn levels.

Dietary Intervention With a Targeted Micronutrient Formulation Reduces the Visual Discomfort Associated With Vitreous Degeneration

Purpose

To investigate the impact of supplementation with a targeted micronutrient formulation on the visual discomfort associated with vitreous degeneration.

Methods

In this clinical trial, 61 patients with symptomatic vitreous floaters were randomized to consume daily, the active supplement consisting of 125 mg L-lysine, 40 mg vitamin C, 26.3 mg Vitis vinifera extract, 5 mg zinc, and 100 mg Citrus aurantium or placebo for 6 months. Change in visual discomfort from floaters, assessed with the Floater Disturbance Questionnaire, was the primary outcome measure. Secondary outcome measures included best-corrected visual acuity, letter contrast sensitivity, photopic functional contrast sensitivity with positive and negative contrast polarity, and quantitative vitreous opacity areas.

Results

After supplementation, the active group reported a significant decrease in their visual discomfort from floaters (P < 0.001), whereas the placebo group had no significant change in their visual discomfort (P = 0.416). At 6 months, there was a significant decrease in vitreous opacity areas in the active group (P < 0.001) and an insignificant increase in vitreous opacity areas in the placebo group (P = 0.081). Also, there was a significant improvement in photopic functional contrast sensitivity with positive contrast polarity in the active group after supplementation (P = 0.047).

Conclusions

The findings of this study indicate improvements in vision-related quality of life and visual function of patients suffering from vitreous floaters after supplementation with a formulation of antioxidative and antiglycation micronutrients. Notably, these improvements were confirmed by the decrease in vitreous opacity areas in the active group.

Translational Relevance

This targeted dietary intervention should be considered to support patients with symptomatic vitreous degeneration.

Zinc enhances carnosine inhibitory effect against structural and functional age-related protein alterations in an albumin glycoxidation model

Age-related complications including protein alterations seen in diabetes and Alzheimer's disease are a major issue due to their accumulation and deleterious effects. This report aims to investigate the effect of zinc supplementation on the anti-glycoxidation activity of carnosine on the in vitro model of albumin-based protein modification. Besides, the therapeutic effect of this combination was tested through the addition of the molecules in tandem (co-treatment) or post initiation (post-treatment) of the protein modification process. Glycation was induced via the addition of glucose to which carnosine (5 mM) alone or with various zinc concentrations (125, 250, and 500 μM) were added either at 0 h or 24 h post-glycation induction. On the other hand, protein oxidation was induced using chloramine T (20 mM) and treated in the same way with carnosine and zinc. The different markers of glycation (advanced glycation end products (AGEs), dityrosine, and beta-sheet formation (aggregation)) and oxidation (AOPP, advanced oxidation protein products) were estimated via fluorescence and colorimetric assays. Zinc addition induced a significant enhancement of carnosine activity by reducing albumin modification that outperformed aminoguanidine both in the co- and post-treatment protocols. Zinc demonstrated a supplementary effect in combination with carnosine highlighting its potential in the protection against age-related protein modifications processes such as the ones found in diabetes.

Effects of the Lysulin™ supplementation on pre-diabetes: A randomized double-blind, placebo-controlled clinical trial

BACKGROUND AND AIMS

Diabetes is a leading cause of morbidity and mortality worldwide. Recent studies have demonstrated that nutraceutical products have beneficial effects in diabetes. Present study aims to investigate whether a product (Lysulin™) containing amino acid lysine, micronutrient zinc and vitamin C will have beneficial effects in pre-diabetes.

METHODS

A randomized, double-blind, placebo-controlled trial was conducted for a period of 6 months. The two parallel groups (1:1) were Lysulin™ (Interventional group-IG) and placebo (control group-CG). Evaluations were done at baseline, 1, 3 and 6 months. Primary outcome was defined as change in glycaemic control measured by HbA1c from baseline. Other outcomes included change in; fasting plasma glucose (FPG), 2-h OGTT plasma glucose and lipid profile from baseline. Three multiple regression analyses were performed, where change in FPG, 2-h OGTT, and HbA1c post intervention from baseline respectively were the continuous dependent variable with other independent variables.

RESULTS

One hundred and ten participants were recruited, 50% (n = 55) were males and mean age (±SD) was 46.7 ± 9.9 years. A significantly higher percentage of participants in CG (25.4%, n = 14) developed diabetes in comparison to IG (7.3%, n = 4) (p = 0.018). FPG, 2-h OGTT and HbA1c significantly reduced in the IG only. Both total cholesterol and LDL cholesterol decreased significantly from baseline only in the IG. In all three regression models the best predictor of respective dependent variable was Lysulin™ treatment.

CONCLUSIONS

Lysulin™ improved glycaemic control, with reduced progression to diabetes, in those with pre-diabetes. Treatment also showed a beneficial reduction in total and LDL cholesterol levels.

TRIAL REGISTRATION

Sri Lanka Clinical Trials Registry, identifier: SLCTR/2018/022 (http://slctr.lk/trials/1290). Registered on 13th July 2018; Study protocol version 2.0 (23rd March 2018).

Chamomile (Matricaria recutita L.) and diabetes mellitus, current knowledge and the way forward: A systematic review

Chamomile, as a rich source of phenolic compounds and terpenoids, seems to be an effective approach in the management of chronic conditions such as diabetes mellitus. The aim of this systematic review was to evaluate evidence from animal and human studies of the effects of chamomile on metabolic risk markers and complications of diabetes mellitus. The literature search was conducted in PubMed, SCOPUS, Embase, ProQuest and Google Scholar electronic and were considered the articles published on April 2019. Original studies that investigated the effect of chamomile in diabetes mellitus which met the inclusion criteria were eligible. After screening 208 citations, 15 studies were included. The results of these studies demonstrated a significant effect of chamomile administration on metabolic profiles. All 12 studies that examined the impact of chamomile supplementation on glycemic control indicated this feature. Four of the five studies appraising the impact of chamomile on lipid profiles showed that it improved dyslipidemia. Six studies showed that chamomile markedly decreased oxidative stress particularly malondialdehyde. Altogether, four chamomile studies evaluating diabetes complications, including renal and hepatic profiles, found significant decreases compared to controls. These findings extend the novel functions of chamomile in the improvement of glycemic and lipid profiles and oxidative stress indicators in diabetes mellitus and related complications. In-depth studies focusing on underlying mechanisms are warranted to make useful conclusions.

Potential roles of Citrulline and watermelon extract on metabolic and inflammatory variables in diabetes mellitus, current evidence and future directions: A systematic review

OBJECTIVE

Diabetes mellitus is a prevalent endocrine disorder worldwide. Citrulline is an α-amino acid, which is abundant in watermelon, and a precursor of arginine and nitric oxide. Decreased bioavailability of nitric oxide is associated with insulin resistance. The present systematic review focused on the existing evidence of citrulline and watermelon extract effects on metabolic and inflammatory parameters in diabetes mellitus.

METHODS

A systematic search of the databases PubMed, Scopus, EMBASE, ProQuest and Google Scholar was conducted for relevant papers published from inception until October 2018. All clinical trials, animal and in vitro studies published in the English language that assessed the role of citrulline and watermelon extract on diabetes mellitus, were eligible. Studies providing inadequate information were excluded.

RESULTS

Out of 1262 articles we found, only eight articles met the inclusion criteria for analysis. In three studies an increase in the synthesis of nitric oxide was reported with citrulline and watermelon extract supplementation. Four studies showed a significant reduction in blood glucose after supplementation with watermelon extract, and two studies reported a decrease in a number of inflammatory biomarkers following citrulline supplementation. Although citrulline intake caused a significant reduction in HOMA-IR in one study, inconsistent results were revealed on the effects of citrulline and watermelon extract on insulin levels and lipid profile.

CONCLUSION

Citrulline and watermelon extract could improve nitric oxide synthesis, glycaemic status and inflammation in diabetes mellitus. However, further studies are required to shed light on the underlying mechanisms.

Agonism of GPR39 displays protective effects against advanced glycation end-product (AGE)-induced degradation of extracellular matrix in human SW1353 cells

Excessive degradation of the cartilage articular extracellular matrix (ECM) in chondrocytes has been considered as an important pathological characteristics of OA. In the present study, we demonstrate that the G protein-coupled receptor GPR39 is expressed on SW1353 chondrocytes and is significantly downregulated in response to advanced glycation end products (AGEs). Our findings show that agonism of GPR39 exerts significant protective effects against AGE-induced degradation of articular extracellular matrix. Agonism of GPR39 rescued degradation of type II collagen by decreasing expression of the collagen-degrading enzymes matrix metalloproteinase (MMP)-3 and MMP-13. Additionally, agonism of GPR39 rescued AGE-induced suppression of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2. Agonism of GPR39 prevented degradation of aggrecan by downregulating AGE-induced expression of a disintegrin and metalloproteinase with type I thrombospondin motif (ADAMTS)-4 and ADAMTS-5. Finally, we demonstrate that the effects of GPR39 are mediated through the p38 mitogen activated protein kinase (MAPK)/nuclear factor-κB (NF-κB) cellular signaling pathway. Taken together, our findings show for the first time that targeted therapies involving GPR39 may provide a novel approach for the prevention and treatment of osteoarthritis.

Effects of Royal jelly on metabolic variables in diabetes mellitus: A systematic review

Diabetes mellitus is one of the most common endocrine disorders in the world. This systematic review was conducted with focus on the current knowledge on the effect of royal jelly on metabolic variables in diabetes mellitus. PubMed, Scopus, Embase, ProQuest and Google Scholar databases were searched from inception until June 2018. All clinical trials and animal studies that evaluated the effects of royal jelly on diabetes mellitus, and were published in English-language journals were eligible. Studies that provided insufficient outcomes were excluded. Out of 522 articles found in the search, only twelve articles were eligible for analysis. Seven studies showed a significant reduction in FBS, and one reported HbA1c decrease following royal jelly supplementation. Although royal jelly supplementation resulted in significant reductions in HOM A-I R in three studies, the findings on insulin levels were controversial. In addition, royal jelly substantially improved serum levels of triglycerides, cholesterol, HDL, LDL, VLDL and Apo-A1 in diabetes mellitus. In addition, royal jelly resulted in a decrease oxidative stress indicators and increase antioxidant enzymes levels. In conclusion, royal jelly could improve glycemic status, lipid profiles and oxidative stress in diabetes mellitus. However, exploring the underlying mechanisms warrants further studies.

Carnosine supplementation does not affect serum concentrations of advanced glycation and precursors of lipoxidation end products in autism: a randomized controlled clinical trial

BACKGROUND

Abundant evidence indicate the increased levels of oxidative stress in patients with autism. Advanced glycation end products and advanced lipoxidation end products and their precursors play a major role in increased oxidative stress in numerous metabolic and neurologic diseases. Carnosine is a natural dipeptide with antiglycation effects. The aim of this trial was to examine the effects of carnosine supplementation on the advanced glycation end products and the precursors of advanced lipoxidation end products in patients with autism.

METHOD

This randomized double-blind, placebo-controlled clinical trial was conducted on 36 autistic children, 18 in the carnosine group and 18 in the placebo group. The groups received a daily supplement of 500 mg carnosine or placebo for two months, respectively. Plasma concentrations of glycation and precursors of lipoxidation markers were evaluated by enzyme-linked immunosorbent assay method.

RESULTS

In all, 63.9% of the autistic children had normal nutritional status. Carnosine supplementation did not significantly alter plasma concentrations of advanced glycation end products and precursors of advanced lipoxidation end products in autistic children.

CONCLUSION

The findings indicate that supplementation of carnosine could not change advanced glycation end products and precursor of advanced lipoxidation end products in autistic children.

Effectiveness and Safety of Dietetic Supplementation of a New Nutraceutical on Lipid Profile and Serum Inflammation Biomarkers in Hypercholesterolemic Patients

Background: To assess the effectiveness and safety of a new nutraceutical (NC) on lipid profile, inflammation biomarkers and creatine phosphokinase (CPK) serum levels in hypercholesterolemic patients. Methods: 40 patients underwent hypolipemic treatment with NC. Initial and final (after 12 weeks) screening included medical history, physical examination, and measurement of serum lipid profile (total cholesterol, HDL-cholesterol, LDL-cholesterol, and triglycerides), hepatic (GOT, GPT, γGT), and renal (serum creatinine and urea) functions, CPK level and many inflammation biomarkers (hs-CRP and fibrinogen). At the screening visit, all patients were instructed to follow a normocaloric and hypolipidic diet during the study period. Results: The treatment with supplementation of NC demonstrated a significant reduction of serum total cholesterol (224 ± 11.2 mg/dL vs. 178 ± 10.7; p < 0.001), LDL-cholesterol (141 ± 10.6 vs. 116 + 10.1; p < 0.001), triglycerides (183 ± 13 vs. 159 ± 11.5; p < 0.01), serum inflammatory biomarkers as hs-CRP (2.24 ± 0.83 vs. 1.76 ± 0.61 mg/dL; p < 0.01), fibrinogen (315 ± 43 vs. 199 ± 41 mg/dL; p < 0.01) and a significantly increase of HDL-cholesterol (44 ± 7 vs. 53 ± 7 mg/dL; p < 0.01). Hepatic and renal function and serum CPK were normal. No adverse events was reported. Conclusions: The treatment with NC has demonstrated a significant reduction of LDL-cholesterol (−17.73%), total cholesterol (−20.53%) and triglycerides (−13.1%), with a significant increase of HDL-cholesterol values (+20.45%). The improvement of lipid profile was associated with a significant reduction of serum inflammation biomarkers as hs-PCR (−27%) and fibrinogen (−36.8%) with good tolerability profile.