Fucoidan exerts protective effects against diabetic nephropathy related to spontaneous diabetes through the NF-κB signaling pathway in vivo and in vitro

Marine Compounds and Age-Related Diseases: The Path from Pre-Clinical Research to Approved Drugs for the Treatment of Cardiovascular Diseases and Diabetes

Ageing represents a main risk factor for several pathologies. Among them, cardiovascular diseases (CVD) and type 2 diabetes mellitus (T2DM) are predominant in the elderly population and often require prolonged use of multiple drugs due to their chronic nature and the high proportion of co-morbidities. Hence, research is constantly looking for novel, effective molecules to treat CVD and T2DM with minimal side effects. Marine active compounds, holding a great diversity of chemical structures and biological properties, represent interesting therapeutic candidates to treat these age-related diseases. This review summarizes the current state of research on marine compounds for the treatment of CVD and T2DM, from pre-clinical studies to clinical investigations and approved drugs, highlighting the potential of marine compounds in the development of new therapies, together with the limitations in translating pre-clinical results into human application.

Fucoidan Improves Early Stage Diabetic Nephropathy via the Gut Microbiota-Mitochondria Axis in High-Fat Diet-Induced Diabetic Mice

Diabetic nephropathy (DN) is a common microvascular complication of diabetes. Fucoidan, a polysaccharide containing fucose and sulfate group, ameliorates DN. However, the underlying mechanism has not been fully understood. This study aimed to explore the effects and mechanism of fucoidan on DN in high-fat diet-induced diabetic mice. A total of 90 C57BL/6J mice were randomly assigned to six groups (n = 15) as follows: normal control (NC), diabetes mellitus (DM), metformin (MTF), low-dose fucoidan (LFC), medium-dose fucoidan (MFC), and high-dose fucoidan (HFC). A technique based on fluorescein isothiocyanate (FITC-sinistin) elimination kinetics measured percutaneously was applied to determine the glomerular filtration rate (GFR). After 24 weeks, the mice were sacrificed and an early stage DN model was confirmed by GFR hyperfiltration, elevated urinary creatinine, normal urinary albumin, tubulointerstitial fibrosis, and glomerular hypertrophy. Fucoidan significantly improved the GFR hyperfiltration and renal fibrosis. An enriched SCFAs-producing bacteria and increased acetic concentration in cecum contents were found in fucoidan groups, as well as increased renal ATP levels and improved mitochondrial dysfunction. The renal inflammation and fibrosis were ameliorated through inhibiting the MAPKs pathway. In conclusion, fucoidan improved early stage DN targeting the microbiota-mitochondria axis by ameliorating mitochondrial oxidative stress and inhibiting the MAPKs pathway.

The therapeutic effects of marine sulfated polysaccharides on diabetic nephropathy

Marine sulfated polysaccharide (MSP) is a natural high molecular polysaccharide containing sulfate groups, which widely exists in various marine organisms. The sources determine structural variabilities of MSPs which have high security and wide biological activities, such as anticoagulation, antitumor, antivirus, immune regulation, regulation of glucose and lipid metabolism, antioxidant, etc. Due to the structural similarities between MSP and endogenous heparan sulfate, a majority of studies have shown that MSP can be used to treat diabetic nephropathy (DN) in vivo and in vitro. In this paper, we reviewed the anti-DN activities, the dominant mechanisms and structure-activity relationship of MSPs in order to provide the overall scene of MSPs as a modality of treating DN.

Fucoidan's Molecular Targets: A Comprehensive Review of Its Unique and Multiple Targets Accounting for Promising Bioactivities Supported by In Silico Studies

Fucoidan is a class of multifunctional polysaccharides derived from marine organisms. Its unique and diversified physicochemical and chemical properties have qualified them for potential and promising pharmacological uses in human diseases, including inflammation, tumors, immunity disorders, kidney diseases, and diabetes. Physicochemical and chemical properties are the main contributors to these bioactivities. The previous literature has attributed such activities to its ability to target key enzymes and receptors involved in potential disease pathways, either directly or indirectly, where the anionic sulfate ester groups are mainly involved in these interactions. These findings also confirm the advantageous pharmacological uses of sulfated versus non-sulfated polysaccharides. The current review shall highlight the molecular targets of fucoidans, especially enzymes, and the subsequent responses via either the upregulation or downregulation of mediators' expression in various tissue abnormalities. In addition, in silico studies will be applied to support the previous findings and show the significant contributors. The current review may help in understanding the molecular mechanisms of fucoidan. Also, the findings of this review may be utilized in the design of specific oligomers inspired by fucoidan with the purpose of treating life-threatening human diseases effectively.

In Vitro and in silico studies to explore potent antidiabetic inhibitor against human pancreatic alpha-amylase from the methanolic extract of the green microalga Chlorella vulgaris

Today's era and lifestyle have led to a quick rise in cases of diabetes. Diabetes mellitus (DM) has risen to the top of the list of serious diseases and stems from different health disorders. Human pancreatic alpha-amylase (HPA) enzyme plays a critical role in the digestion of carbohydrates, and inhibitors of alpha-amylase have been investigated as a way to slow the absorption of carbohydrates and reduce postprandial (after meal) hyperglycemia in patients with diabetes. Recently algal derivatives have been studied for their potential as a new drug against diabetes and other diseases. The study is aimed to find active biochemical compounds from the methanolic extract of Chlorella vulgaris. The in vitro studies were carried out and the results revealed that methanolic extract from C. vulgaris showed abundant inhibition efficacy of the α-amylase (IC50 of about 2.66 µg/mL) compared to acarbose (IC50 of about 2.85 µg/mL), a standard, commercial inhibitor. All the bioactive compounds from the methanolic extract were identified from the GCMS study and considered for in silico evaluation. Out of 14 bioactive compounds from GCMS, compound C3 showed higher docking energy (-8.3 kcal/mol) compared to other compounds. Subsequently, the comparative molecular dynamic simulation of apo and ligand-bound (compound C3 and acarbose) α-amylase complexes showed overall structural stability for compound C3 at the active site of α-amylase from various MD analyses. Hence, we believe, the bioactive compounds identified from GCMS may assist in diabetic therapeutics. Moreover, the compound C3 identified in this study could be a potential antidiabetic therapeutic inhibitor.Communicated by Ramaswamy H. Sarma.

Albiflorin ameliorates mesangial proliferative glomerulonephritis by PI3K/AKT/NF-κB pathway

Background: The most common type of glomerulonephritis in China is mesangial proliferative glomerulonephritis (MPGN) featured with mesangial cell overproliferation and inflammation, as well as fibrosis. Albiflorin (AF) is an effective composition extracted from Paeonia Alba Radix and has been administrated for various diseases. Nevertheless, there is no research reporting the effect of AF on MPGN.Purpose: Our work aims to probe into the role and possible mechanism of AF on MPGN.Research Design: We investigated the effects of AF on mesangial cell overproliferation, inflammation, and fibrosis in vitro and in vivo and identified the related signaling pathways.Study Sample: human mesangial cells (HMCs) and male Sprague Dawley (SD) rats.Data Analysis: SPSS 18.0 was used to analyze the data.Results: AF attenuated the proliferation and inflammation both in vitro and in vivo. In detail, AF decreased the ki67 expression in lipopolysaccharides (LPS)-treated HMCs and MPGN rats, and the mRNA expression or contents of inflammatory cytokines were reduced after AF treatment. The fibrosis of LPS-treated HMCs and MPGN rats was also reduced by AF. Moreover, AF effectively restrained 24 h urinary protein, improved kidney function, and mitigated dyslipidemia and pathological injury of MPGN rats. Additionally, we found that the protective effects of AF were accompanied by the blocking of PI3K/AKT/NF-κB pathway, and the inhibitory effects of AF on MPGN were reversed by insulin-like growth factor (IGF-1), the PI3K agonist.Conclusions: AF alleviates MPGN via restraining mesangial cell overproliferation, inflammation, and fibrosis via PI3K/AKT/NF-κB signaling.

Marine polysaccharide laminarin embedded ZnO nanoparticles and their based chitosan capped ZnO nanocomposites: Synthesis, characterization and in vitro and in vivo toxicity assessment

In the current scenario where more and more products containing nanomaterials are on the technological or pharmaceutical market, it is crucial to have a thorough knowledge of their toxicity before proposing possible applications. A proper analysis of the toxicity of the nanoproducts should include both in vitro and in vivo biological approaches and should consider that the synthesis and purification methods of nanomaterials may affect such toxicity. In the current work, the green synthesis of laminarin embedded ZnO nanoparticles (Lm-ZnO NPs) and their based chitosan capped ZnO nanocomposites (Ch-Lm-ZnO NCmps) is described for the first time. Furthermore, the evaluation of their in vitro cytotoxicity, phytotoxicity, and in vivo (Zebrafish embryo) toxicity was described. First, the green synthesized Lm-ZnO NPs and Ch-Lm-ZnO NCmps were fully physicochemically characterized. Lm-ZnO NPs were greatly agglomerated and had a spindle morphology ranging from 100 to 350 nm, while Ch-Lm-ZnO NCmps had irregular rod shape with flake-like structure clusters randomly aggregated with diverse sizes ranging from 20 to 250 nm. The in vitro cytotoxicity assessment of the green synthesized Lm-ZnO NPs and Ch-Lm-ZnO NCmps was carried out in normal human dermal fibroblasts (HDF) cells and human colon cancer (HT-29) cells by MTT assay. Lm-ZnO NPs and Ch-Lm-ZnO NCmps (0.1-500 μg/mL), significantly inhibited the viability of both cell lines, revealing dose-dependent cytotoxicity. Besides, the Lm-ZnO NPs and Ch-Lm-ZnO NCmps significantly affected seed germination and roots and shoots length of mung (Vigna radiata). Moreover, the zebrafish embryo toxicity of Lm-ZnO NPs and Ch-Lm-ZnO NCmps among the various concentrations used (0.1-500 μg/mL) caused deformities, increased mortality and decreased the survival rate of zebrafish embryo dose-dependently.

The potential mechanisms of Macrocystis pyrifera polysaccharides mitigating type 2 diabetes in rats

Our previous studies have proved that the anti-digestive polysaccharide from Macrocystis pyrifera possesses potential hypoglycemic and lipid-lowering activities; however, its potential mechanisms for improving diabetes have not been elucidated. The current study was aimed to determine the anti-diabetic effects and possible mechanisms of Macrocystis pyrifera polysaccharides (MPP) in diabetic rats. After 8-week MPP treatment, the serum profiles, gut bacteria composition and relative gene expressions of rats were determined. MPP administration effectively ameliorated the diabetic symptoms, dyslipidemia, liver and kidney damage, oxidative stress and chronic inflammation in diabetic rats. In addition, MPP treatment could also notably improve the microbial dysbiosis by increasing the beneficial bacteria and decreasing a bacterial pathogen in the diabetic rats. The RT-qPCR analysis indicated that MPP intervention significantly up-regulated the IRS/PI3K/AKT signaling pathway and down-regulated the relative expressions of glucose-6-phosphatase (G-6-Pase), phosphoenolpyruvate carboxykinase (PEPCK), acetyl-CoA carboxylase (ACC), hydroxymethylglutaryl CoA reductase (HMGCR) and sterol regulatory element binding protein 1c (SREBP-1c) in diabetic rats. These results demonstrated that MPP had the potential to be exploited as functional foods or pharmaceutical supplements for preventing and treating diabetes.

Protective effects of fucoidan against kidney diseases: Pharmacological insights and future perspectives

Chronic kidney disease (CKD) is a major public health concern that costs millions of lives worldwide. Natural products are consistently being explored for the development of novel therapeutics in the management of CKD. Fucoidan is a sulfated polysaccharide predominantly extracted from brown seaweed, which has multiple pharmacological benefits against various kidney problems, including chronic renal failure and diabetic nephropathy. This review aimed at exploring literature to update the renoprotective effects of fucoidan, to get an understanding of pharmacological mechanisms, and to highlight the recent progress of fucoidan-based therapeutic development. Evidence shows that fucoidan is effective against inflammation, oxidative stress, and fibrosis in kidney. Fucoidan targets multiple signaling systems, including Nrf2/HO-1, NF-κB, ERK and p38 MAPK, TGF-β1, SIRT1, and GLP-1R signaling that are known to be associated with CKD pathobiology. Despite these pharmacological prospects, the application of fucoidan is limited by its larger molecular size. Notably, low molecular weight fucoidan has shown therapeutic promise in some recent studies. However, future research is warranted to translate the outcome of preclinical studies into clinical use in kidney patients.

Scavenger receptor A in immunity and autoimmune diseases: Compelling evidence for targeted therapy

INTRODUCTION

Scavenger receptor A (SR-A) is reported to be involved in innate and adaptive immunity and in recent years, the soluble form of SR-A has also been identified. Intriguingly, SR-A displays double-edged sword features in different diseases. Moreover, targeted therapy on SR-A, including genetic modulation, small molecule inhibitor, inhibitory peptides, fucoidan, and blocking antibodies, provides potential strategies for treatment. Currently, therapeutics targeting SR-A are in preclinical studies and clinical trials, revealing great perspectives in future immunotherapy.

AREAS COVERED

Through searching PubMed (January 1979-March 2022) and clinicaltrials.gov, we review most of the research and clinical trials involving SR-A. This review briefly summarizes recent study advances on SR-A, with particular concern on its role in immunity and autoimmune diseases.

EXPERT OPINION

Given the emerging evidence of SR-A in immunity, its targeted therapy has been studied in various diseases, especially autoimmune diseases. However, many challenges still remain to be overcome, such as the double-sworded effects and the specific isoform targeting. For further clinical success of SR-A targeted therapy, the crystal structure illustration and the dual function discrimination of SR-A should be further investigated. Nevertheless, although challenging, targeting SR-A would be a potential effective strategy in the treatment of autoimmune diseases and other immune-related diseases.

Low molecular weight fucoidan fraction LF2 improves metabolic syndrome via up-regulating PI3K-AKT-mTOR axis and increasing the abundance of Akkermansia muciniphila in the gut microbiota

Metabolic syndrome (MetS) is a pathological condition of a variety of metabolic abnormalities, which requires more urgent treatment and intervention. Fucoidan has been recommended as a supplement for health enhancement and disease management. Here, we first propose that the beneficial effect of low molecular weight fucoidan fraction LF2 in regulating metabolic syndrome induced by high-fat diet is similar to that of metformin, in terms of molecular mechanism and gut microbiota. The study found that LF2 significantly reduces fasting blood glucose, enhances insulin sensitivity and restores insulin homeostasis and lipid homeostasis. Moreover, LF2 reduced liver oxidative stress and inflammation, and improved hepatocyte steatosis. To decipher the mechanism behind this therapeutic effect, both the molecular mechanisms and gut microbiota were further analyzed. LF2 inhibited the activation of PI3K-Akt-mTOR axis and decreased the expression of SREBP-1c and PPARγ in liver. Interestingly, we found that LF2 and metformin have similar effects on gut microbiota, increasing the proportion of Verrucomicrobia and enriching the abundance of Akkermansia muciniphila, which is beneficial to host health. Collectively, our research clarifies the new application of fucoidan as a functional food for anti-MetS, and provides a new insight for fucoidan to exert systemic therapeutic effects from the perspective of molecular mechanism and gut microbiota.

Brown Algae Carbohydrates: Structures, Pharmaceutical Properties, and Research Challenges

Brown algae (Phaeophyceae) have been consumed by humans for hundreds of years. Current studies have shown that brown algae are rich sources of bioactive compounds with excellent nutritional value, and are considered functional foods with health benefits. Polysaccharides are the main constituents of brown algae; their diverse structures allow many unique physical and chemical properties that help to moderate a wide range of biological activities, including immunomodulation, antibacterial, antioxidant, prebiotic, antihypertensive, antidiabetic, antitumor, and anticoagulant activities. In this review, we focus on the major polysaccharide components in brown algae: the alginate, laminarin, and fucoidan. We explore how their structure leads to their health benefits, and their application prospects in functional foods and pharmaceuticals. Finally, we summarize the latest developments in applied research on brown algae polysaccharides.

Pharmacological Activities of Sulfated Fucose-Rich Polysaccharides after Oral Administration: Perspectives for the Development of New Carbohydrate-Based Drugs

Marine organisms are a source of active biomolecules with immense therapeutic and nutraceutical potential. Sulfated fucose-rich polysaccharides are present in large quantities in these organisms with important pharmacological effects in several biological systems. These polysaccharides include sulfated fucan (as fucoidan) and fucosylated chondroitin sulfate. The development of these polysaccharides as new drugs involves several important steps, among them, demonstration of the effectiveness of these compounds after oral administration. The oral route is the more practical, comfortable and preferred by patients for long-term treatments. In the past 20 years, reports of various pharmacological effects of these polysaccharides orally administered in several animal experimental models and some trials in humans have sparked the possibility for the development of drugs based on sulfated polysaccharides and/or the use of these marine organisms as functional food. This review focuses on the main pharmacological effects of sulfated fucose-rich polysaccharides, with an emphasis on the antidislipidemic, immunomodulatory, antitumor, hypoglycemic and hemostatic effects.

Cancer-fighting potentials of algal polysaccharides as nutraceuticals

Cancer has been listed as one of the world's five incurable diseases by the World Health Organization and causes tens of thousands of deaths every year. Unfortunately, anticancer agents either show limited efficacy or show serious side effects. The algae possess high nutritional value and their polysaccharides have a variety of biological activities, especially anti-cancer and immunomodulatory properties. Algal polysaccharides exert anti-cancer effects by inducing apoptosis, cell cycle arrest, anti-angiogenesis, and regulating intestinal flora and immune function. Algal polysaccharides can be combined with nanoparticles and other drugs to reduce the side effects caused by chemotherapy and increase the anticancer effects. This review shows the signal pathways related to the anti-cancer mechanisms of algal polysaccharides, including their influence on intestinal flora and immune regulation, the application of nanoparticles, and the effects on combination therapy and clinical trials of cancer treatments.

Fucoidan mitigated diabetic nephropathy through the downregulation of PKC and modulation of NF-κB signaling pathway: in vitro and in vivo investigations

The persistence of hyperglycemia and oxidative stress in diabetic patients ultimately leads to diabetic nephropathy (DN). In this study, we investigated the effect of sulfated polysaccharides (SPS) extracted from Laminaria japonica in relieving DN symptoms. To induce the diabetic model, normal rats were kept on a high-sugar, high-fat diet, then they were injected with streptozocin. Groups of these rats were later treated with SPS and/or protein kinase C (PKC) inhibitor. The analyses performed herein demonstrate that although diabetes significantly decreases the body weights of rats, SPS and inhibitor treatments increase these weights, as well as the ratios of renal to total body weight. Serum biochemical analyses indicate that blood urea nitrogen and serum creatinine levels gradually decrease in the SPS group. In addition, DN symptoms are substantially relieved by SPS and/or inhibitor treatments, as evidenced by histopathological analyses. Changes in the expressions of PKC-α, PKC-β, P-selectin, nuclear factor kappa B (NF-κB), and p65, detected by immunohistochemistry and western blot assessments, show that SPS regulates diabetic nephropathy via the PKC/NF-κB pathway.

Wogonin Ameliorates Renal Inflammation and Fibrosis by Inhibiting NF-κB and TGF-β1/Smad3 Signaling Pathways in Diabetic Nephropathy

Introduction

Diabetic nephropathy (DN) has become an increasing threat to health, and inflammation and fibrosis play important roles in its progression. Wogonin, a flavonoid, has been proven to suppress inflammation and fibrosis in various diseases, including acute kidney injury. This study aimed at investigating the effect of wogonin on diabetes-induced renal inflammation and fibrosis.

Materials and Methods

Streptozotocin (STZ)-induced diabetic mouse models received gavage doses of wogonin (10, 20, and 40 mg/kg) for 12 weeks. Metabolic indices from blood and urine and pathological damage of glomerulus in the diabetic model were assessed. Glomerular mesangial cells SV40 were cultured in high glucose (HG) medium containing wogonin at concentrations of 1.5825, 3.125, and 6.25 μg/mL for 24 h. Inflammation and fibrosis indices were evaluated by histopathological, Western blotting, and PCR analyses.

Results

Wogonin treatment ameliorated albuminuria and histopathological lesions in diabetic mice. Inflammatory cytokines, such as monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and related signaling pathway NF-κB were downregulated after the administration of wogonin in vivo and in vitro. Furthermore, wogonin reduced the expression of extracellular matrix (ECM), including fibronectin (FN), collagen IV (Col-IV), α-smooth muscle actin (α-SMA), and transforming growth factor-β1 (TGF-β1) in the kidneys of diabetic mice and HG-induced mesangial cells. Moreover, the inhibition of TGF-β1/Smad3 pathway might be responsible for these changes.

Conclusion

Wogonin may ameliorate renal inflammation and fibrosis in diabetic nephropathy by inhibiting the NF-κB and TGF-β1/Smad3 signaling pathways.

Oligo-Fucoidan Improves Diabetes-Induced Renal Fibrosis via Activation of Sirt-1, GLP-1R, and Nrf2/HO-1: An In Vitro and In Vivo Study

Fucoidan extracted from brown algae has multiple beneficial functions. In this study, we investigated the effects of low-molecular-weight fucoidan (oligo-FO) on renal fibrosis under in vitro and in vivo diabetic conditions, and its molecular mechanisms. Advanced glycation product (AGE)-stimulated rat renal proximal tubular epithelial cells (NRK-52E) and diabetic mice induced by high-fat diet and intraperitoneal injection of streptozotocin and nicotinamide were used. Oligo-FO treatment significantly inhibited anti-high mobility group box 1 (HMGB1)/RAGE/ anti-nuclear factor-kappa B (NF-κB)/transforming growth factor-β1 (TGF-β1)/TGF-β1R/Smad 2/3/fibronectin signaling pathway and HIF-1α activation in AGE-stimulated NRK-52E cells. Conversely, the expression and activity of Sirt-1; the levels of ubiquitin-specific peptidase 22 (USP22), p-AMPK, glucagon-like peptide-1 receptor (GLP-1R), and heme oxygenase-1 (HO-1); and Nrf2 activation were remarkably increased by oligo-FO in AGE-stimulated cells. However, the above effects of oligo-FO were greatly diminished by inhibiting Sirt-1, HO-1, or GLP-1R activity. Similar changes of these pro-fibrotic genes in the kidney and a marked attenuation of renal injury and dysfunction were observed in oligo-FO-treated diabetic mice. These findings indicated that the inhibitory effects of the oligo-FO on diabetes-evoked renal fibrosis are mediated by suppressing TGF-β1-activated pro-fibrogenic processes via Sirt-1, HO-1, and GLP-1R dependence. Collectively, fucoidan-containing foods or supplements may be potential agents for ameliorating renal diseases due to excessive fibrosis.

Multifunctional role of fucoidan, sulfated polysaccharides in human health and disease: A journey under the sea in pursuit of potent therapeutic agents

Fucoidan is a complex polysaccharide (molecular weight 10,000-100,000 Da) derived from brown algae which comprises of L-fucose and sulfate groups have potential as therapeutic diligences against several human diseases. The fucoidan has expanded a widespread range of pharmacological properties as an anti-inflammatory, anticoagulant, antiangiogenic, immunomodulatory, anti-adhesive, anticancer, antidiabetic, antiviral and anti-neurodegenerative agents owing to their diverse chemical conformation and potent antioxidant activity. The antioxidant and immunomodulatory activities of the fucoidan contribute towards their disease preventive potency through dynamic modulation of key intracellular signalling pathways, regulation of ROS accumulation, and maintenance of principal cell survival and death pathways. Additionally, it also reduces cancer-associated cachexia. Despite the wide range of therapeutic potency, the fucoidan is heavily regarded as an unexplored plethora of druggable entities in the current situation. The isolation, screening, biological application, pre-clinical, and clinical assessment along with large scale cost-effective production remain a foremost task to be assessed. Moreover, the chemical synthesis of the present bioactive drug with confirmational rearrangement for enhanced availability and bioactivity also need tenacious investigation. Hence, in the present review, we give attention to the source of isolation of fucoidan, their principle strategic deployment in disease prevention, and the mechanistic investigation of how it works to combat different diseases that can be used for future therapeutic intervention.

Cyanidin-3-glucoside from Black Rice Ameliorates Diabetic Nephropathy via Reducing Blood Glucose, Suppressing Oxidative Stress and Inflammation, and Regulating Transforming Growth Factor β1/Smad Expression

Diabetic nephropathy (DN) is one of the serious complications in diabetes. Cyanidin-3-glucoside (C3G) from black rice was reported to have hypoglycemic effects and an anti-osteoporosis effect in diabetic rats. Whether it has preventive effects on DN has not been reported. In this study, we established a rat model of DN, and C3G at two doses (10 and 20 mg kg^-1 day^-1) were administered to see its anti-DN effect. A total of 8 weeks of C3G supplementation decreased blood glucose and serum insulin, improved the renal function, and relieved renal glomerular sclerosis and interstitial fibrosis of DN rats. Also, the kidneys of DN rats had improved the oxidative defense system. Pro-inflammatory mediators were markedly reduced in serum and kidneys of the C3G-treated groups. Transforming growth factor β1 (TGF-β1), phosphor-Smad2, and phosphor-Smad3 protein expression levels were significantly decreased in the kidney of the C3G-treated group, whereas the Smad7 expression level was upregulated by C3G. Our results indicate that C3G can ameliorate DN via antioxidative stress and anti-inflammation and regulate the TGF-β1/Smad2/3 pathway. Our results suggest that C3G from black rice might be used as a renal-protective nutrient in DN.

A comparative study of sulphated polysaccharide effects on advanced glycation end-product uptake and scavenger receptor class A level in macrophages

Advanced glycation end-products, especially toxic advanced glycation end-products derived from glyceraldehyde (advanced glycation end-product-2) and glycolaldehyde (advanced glycation end-product-3), are biologically reactive compounds associated with diabetic complications. We previously demonstrated that toxic advanced glycation end-products were internalised into macrophage-like RAW264.7 cells through scavenger receptor-1 class A (CD204). Toxic advanced glycation end-product uptake was inhibited by fucoidan, a sulphated polysaccharide and antagonistic ligand for scavenger receptors, suggesting that sulphated polysaccharides are emerging candidates for treatment of advanced glycation end-product-related diseases. In this study, we compared the effects of six types of sulphated and non-sulphated polysaccharides on toxic advanced glycation end-product uptake in RAW264.7 cells. Fucoidan, carrageenan and dextran sulphate attenuated toxic advanced glycation end-product uptake. Fucoidan and carrageenan inhibited advanced glycation end-product-2-induced upregulation of SR-A, while advanced glycation end-product-3-induced upregulation of scavenger receptor-1 class A was only suppressed by fucoidan. Dextran sulphate did not affect scavenger receptor-1 class A levels in toxic advanced glycation end-product-treated cells. Chondroitin sulphate, heparin and hyaluronic acid failed to attenuate toxic advanced glycation end-product uptake. Heparin and hyaluronic acid had no effect on scavenger receptor-1 class A levels, while chondroitin sulphate inhibited advanced glycation end-product-3-induced upregulation of scavenger receptor-1 class A. Taken together, fucoidan and carrageenan, but not the other sulphated polysaccharides examined, had inhibitory activities on toxic advanced glycation end-product uptake and toxic advanced glycation end-product-induced upregulation of scavenger receptor-1 class A, possibly because of structural differences among sulphated polysaccharides.

Fucoidan prevent murine autoimmune diabetes via suppression TLR4-signaling pathways, regulation DC/Treg induced immune tolerance and improving gut microecology

Background

This study was to investigate the effect and its possible mechanism of fucoidan on the development of spontaneous autoimmune diabetes in non-obese diabetic (NOD) mice.

Methods

7-week-old NOD mice were randomly divided into three groups: control group, low-dose (300 mg/kg) and high-dose (600 mg/kg) fucoidan-treatment groups. After 5 weeks of treatment, 10 mice per group were randomly selected to be sacrificed after feces collection. The remaining 12 mice per group were fed until 26 weeks of age to assess the incidence of diabetes.

Results

Treatment with fucoidan increased serum insulin level, delayed the onset and decreased the development of diabetes in NOD mice. Fucoidan reduced the levels of strong Th1 proinflammatory cytokines, but induced Th2-bias ed. cytokine response. And dentridic cells (DCs) in fucoidan treatment group were characterized as low expression of MHC class II and CD86 molecules. TLR4 expressions and the downstream molecules in pancreas were down-regulated in fucoidan-treated groups. There were significant differences in the composition of gut flora between NOD control group and fucoidan group. Lactobacillus and Akkermansia were significantly enriched in fucoidan group.

Conclusions

Fucoidan could prevent the development of autoimmune diabetes in NOD mice via regulating DC/Treg induced immune tolerance, improving gut microecology, down-regulating TLR4 signaling pathway, and maintaining pancreatic internal environment.

Effects of scavenger receptors-1 class A stimulation on macrophage morphology and highly modified advanced glycation end product-protein phagocytosis

Advanced glycation end-products (AGEs), which comprise non-enzymatically glycosylated proteins, lipids, and nucleic acid amino groups, play an important role in several diseases and aging processes including angiopathy, renal failure, diabetic complications, and neurodegenerative diseases. Among AGE-associated phenotypes, toxic AGEs, glyceraldehyde-derived AGE-2, and glycolaldehyde-derived AGE-3 are involved in the pathogenesis of diabetic complications. In addition, macrophages are reported to remove extracellular AGEs from tissues via scavenger receptors, leading to the progression of atherosclerosis. In the present study, we found that AGE-2 and AGE-3 enhanced their own endocytic uptake by RAW264.7 mouse macrophage-like cells in a concentration-dependent manner. Furthermore, we demonstrated, for the first time, the morphology of phagocytic macrophages and the endocytosis of AGE particles. The toxic AGEs induced the expression of a scavenger receptor, CD204/scavenger receptors-1 class A (SR-A). Notably, an antibody against CD204 significantly prevented toxic AGE uptake. Moreover, an SR-A antagonistic ligand, fucoidan, also attenuated the AGE-2- and AGE-3-evoked uptake in a concentration-dependent manner. These results indicated that SR-A stimulation, at least in part, plays a role in AGE uptake.

Improved anticoagulant effect of fucosylated chondroitin sulfate orally administered as gastroresistant tablets

Fucosylated chondroitin sulfate (FucCS) is a potent anticoagulant polysaccharide extracted from sea cucumber. Its anticoagulant activity is attributed to the presence of unique branches of sulfated fucose. Although this glycosaminoglycan exerts an antithrombotic effect following oral administration, high doses are necessary to achieve the maximum effect. The diminished activity of FucCS following oral administration is likely due to its degradation in the gastrointestinal tract and its limited ability to cross the intestinal cell membranes. The latter aspect is particularly difficult to overcome. However, gastroresistant tablet formulation may help limit the degradation of FucCS in the gastrointestinal tract. In the present work, we found that the oral administration of FucCS as gastroresistant tablets produces a more potent and prolonged anticoagulant effect compared with its administration as an aqueous solution, with no significant changes in the bleeding tendency or arterial blood pressure. Experiments using animal models of arterial thrombosis initiated by endothelial injury demonstrated that FucCS delivered as gastro-protective tablets produced a potent antithrombotic effect, whereas its aqueous solution was ineffective. However, there was no significant difference between the effects of FucCS delivered as gastroresistant tablets or as aqueous solution in a venous thrombosis model, likely due to the high dose of thromboplastin used. New oral anticoagulants tested in these experimental models for comparison showed significantly increased bleeding tendencies. Our study provides a framework for developing effective oral anticoagulants based on sulfated polysaccharides from marine organisms. The present results suggest that FucCS is a promising oral anticoagulant.

Supplementary Material to this article is available online at www.thrombosis-online.com.

Protective effects of fucoidan against hyperoxic lung injury via the ERK signaling pathway

High oxygen mechanical ventilation is widely used to treat various lung diseases; however, it may result in hyperoxia, which induces inflammation and lung injury. Fucoidan is an extract of the seaweed Fucus vesiculosus, which has previously been reported to exert effects against diabetic nephropathy. The present study is the first, to the best of our knowledge, to investigate the protective effects of fucoidan against hyperoxic lung injury. Balb/c mice were ventilated with 100% oxygen, with or without the atomization inhalation of fucoidan, for 36 h. Hyperoxia reduced the body weight and increased the relative lung weight of the mice. In addition, cell quantity and differentiation were determined using a hemocytometer, hyperoxia increased the total number of cells, and the number of macrophages, neutrophils and lymphocytes in the bronchoalveolar lavage fluid. Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) demonstrated that hyperoxia also increased the mRNA expression levels of cluster of differentiation (CD)68, F4/80, CD64 and CD19 in lung tissue, and induced lung morphological alterations. Furthermore, western blotting assay demonstrated that hyperoxia increased the expression levels of interleukin (IL)‑1, IL‑6 and tumor necrosis factor (TNF)‑α, and the phosphorylation of extracellular signal‑regulated kinase (ERK)1/2. Conversely, hyperoxia‑induced inflammation and morphological alterations were significantly attenuated in the mice treated with fucoidan. Atomization inhalation of fucoidan also reduced the hyperoxia‑induced expression of IL‑1, IL‑6 and TNF‑α, and the phosphorylation of ERK1/2. These findings suggested that fucoidan may attenuate hyperoxic lung injury via the ERK1/2 signaling pathway.

Protective effects of tacrolimus on podocytes in early diabetic nephropathy in rats

The aim of the present study was to investigate the protective effect of tacrolimus on early podocyte damage in rats with diabetic nephropathy (DN). A total of 38 normal male Sprague‑Dawley rats were randomly divided into four groups: Normal control group (group N; n=8), DN group (n=10), tacrolimus (FK506) treatment group (group F; n=10), benazepril (Lotensin) treatment group (group L; n=10). The rats in groups DN, F and L were administered with streptozotocin (STZ; 60 mg/kg) by intraperitoneal injection to establish the diabetic rat model. After 4 weeks, the diabetic rat model was established, and rats in the different groups were administered intragrastically with the respective drugs. Blood glucose (BS), body weight (BW) and 24‑h urine protein were detected every 4 weeks, serum creatinine (SCr), blood urea nitrogen (BUN) and kidney weight/body weight (KW/BW) were measured at the end of the 8 weeks of drug treatment. Renal pathological changes were observed under a light microscope and electron microscope. Expression of nephrin, which is a podocyte‑specific marker, was detected using western blot analysis. The results showed that the levels of SCr, BUN, KW/BW and 24‑h urine protein in groups D, F and L were significantly higher, compared with those in group N (P<0.05). No significant differences were found between groups F and L for the above indicators, with the exception of BS. However, all indices were significantly lower, compared with those in group DN (P<0.05). Renal pathological expression was normal in group N under light microscopy. There were significant increases in the glomerular volume, proliferative mesangial cells, width of the mesangial area and thickness of the basement membrane in group DN, however, all the above pathological characteristics were reduced in groups F and L, compared with group DN (P<0.05). No significant difference was found between groups F and L. A widened glomerular basement membrane, and disorder, widening and fusion of podocyte processes were observed under the electron microscope in group DN, however, these were reduced in groups F and L, compared with group DN (P<0.05). The results of the western blot analysis showed that the expression of nephrin decreased by 60.1% in group DN, compared with group N, and significant recovery in the expression of nephrin was observed in groups F and L (P<0.05). Tacrolimus reduced urinary protein and slowed the progression of DN, partially by recovering the protein expression of nephrin in the renal tissue of diabetic rats, and maintaining the integrity of the structure and function of podocytes.

Estimation of ellagic acid and/or repaglinide effects on insulin signaling, oxidative stress, and inflammatory mediators of liver, pancreas, adipose tissue, and brain in insulin resistant/type 2 diabetic rats

Even though ellagic acid has previously been valued in many models of cancer, so far its full mechanistic effect as a natural antiapoptotic agent in the prevention of type 2 diabetes complications has not been completely elucidated, which was the goal of this study. We fed albino rats a high-fat fructose diet (HFFD) for 2 months to induce insulin resistance/type 2 diabetes and then treated the rats with ellagic acid (10 mg/kg body weight, orally) and/or repaglinide (0.5 mg/kg body weight, orally) for 2 weeks. At the serum level, ellagic acid challenged the consequences of HFFD, significantly improving the glucose/insulin balance, liver enzymes, lipid profile, inflammatory cytokines, redox level, adipokines, ammonia, and manganese. At the tissue level (liver, pancreas, adipose tissue, and brain), ellagic acid significantly enhanced insulin signaling, autophosphorylation, adiponectin receptors, glucose transporters, inflammatory mediators, and apoptotic markers. Remarkably, combined treatment with both ellagic acid and repaglinide had a more pronounced effect than treatment with either alone. These outcomes give new insight into the promising molecular mechanisms by which ellagic acid modulates numerous factors induced in the progression of diabetes.

Rodent models of diabetic nephropathy: their utility and limitations

Diabetic nephropathy is the most common cause of end-stage renal disease. Therefore, novel therapies for the suppression of diabetic nephropathy must be developed. Rodent models are useful for elucidating the pathogenesis of diseases and testing novel therapies, and many type 1 and type 2 diabetic rodent models have been established for the study of diabetes and diabetic complications. Streptozotocin (STZ)-induced diabetic animals are widely used as a model of type 1 diabetes. Akita diabetic mice that have an Ins2+/C96Y mutation and OVE26 mice that overexpress calmodulin in pancreatic β-cells serve as a genetic model of type 1 diabetes. In addition, db/db mice, KK-Ay mice, Zucker diabetic fatty rats, Wistar fatty rats, Otsuka Long-Evans Tokushima Fatty rats and Goto-Kakizaki rats serve as rodent models of type 2 diabetes. An animal model of diabetic nephropathy should exhibit progressive albuminuria and a decrease in renal function, as well as the characteristic histological changes in the glomeruli and the tubulointerstitial lesions that are observed in cases of human diabetic nephropathy. A rodent model that strongly exhibits all these features of human diabetic nephropathy has not yet been developed. However, the currently available rodent models of diabetes can be useful in the study of diabetic nephropathy by increasing our understanding of the features of each diabetic rodent model. Furthermore, the genetic background and strain of each mouse model result in differences in susceptibility to diabetic nephropathy with albuminuria and the development of glomerular and tubulointerstitial lesions. Therefore, the validation of an animal model reproducing human diabetic nephropathy will significantly facilitate our understanding of the underlying genetic mechanisms that contribute to the development of diabetic nephropathy. In this review, we focus on rodent models of diabetes and discuss the utility and limitations of these models for the study of diabetic nephropathy.

Anti-diabetic polysaccharides from natural sources: A review

Diabetes mellitus (DM) is a metabolic disease attracted worldwide concerns, which severely impairs peoples' quality of life and is attributed to several life-threatening complications, including atherosclerosis, nephropathy and retinopathy. The current therapies for DM include mainly oral anti-diabetic drugs and insulin. However, continuous use of these causes insulin resistance and side-effects, and the demand of effective, nontoxic and affordable drugs for DM patients is eager. Several previous studies have shown that non-toxic biological macromolecules, mainly polysaccharides, possess prominent efficacies on DM. Based on these encouraging observations, a great deal of efforts have been focused on discovering anti-diabetic polysaccharides for the development of effective therapeutics for DM. This review focuses on the advancements in the anti-diabetic efficacy of various natural polysaccharides and polysaccharide complexes from 2010 to 2015.

Fucoidan from Fucus vesiculosus Fails to Improve Outcomes Following Intracerebral Hemorrhage in Mice

Intracerebral hemorrhage (ICH) is the most fatal stroke subtype, with no effective therapies. Hematoma expansion and inflammation play major roles in the pathophysiology of ICH, contributing to primary and secondary brain injury, respectively. Fucoidan, a polysaccharide from the brown seaweed Fucus vesiculosus, has been reported to activate a platelet receptor that may function in limiting bleeding, and to exhibit anti-inflammatory effects. As such, the aim of the present study was to examine the effects of fucoidan on hemorrhaging and neurological outcomes after ICH. Male CD-1 mice were subjected to experimental ICH by infusion of bacterial collagenase. Animals were randomly divided into the following groups: sham, ICH + vehicle, ICH + 25 mg/kg fucoidan, ICH + 75 mg/kg fucoidan, and ICH + 100 mg/kg fucoidan. Brain water content, neurobehavioral outcomes, and hemoglobin content were evaluated at 24 h post ICH. Our findings show that fucoidan failed to attenuate the ICH-induced increase in BWC. The neurological deficits that result from ICH also did not differ in the treatment groups at all three doses. Finally, we found that fucoidan had no effect on the hemoglobin content after ICH. We postulate that fucoidan treatment did not improve the measured outcomes after ICH because we used crude fucoidan, which has a high molecular weight, in our study. High-molecular-weight fucoidans are reported to have less therapeutic potential than low molecular weight fucoidans. They have been shown to exhibit anti-coagulant and pro-apoptotic properties, which seem to outweigh their anti-inflammatory and potential procoagulant abilities. We propose that using a low-molecular-weight fucoidan, or fractionating the crude polysaccharide, may be effective in treating ICH. Future studies are needed to confirm this.