Tetrahydrocurcumin Add-On therapy to losartan in a rat model of diabetic nephropathy decreases blood pressure and markers of kidney injury.

Tetrahydrocurcumin (THC), a principal metabolite of curcumin, was tested in a rat model of type 2 diabetes mellitus. THC was administered via daily oral gavage with the lipid carrier polyenylphosphatidylcholine (PPC) as add-on therapy to losartan (angiotensin receptor blocker) to examine effects on kidney oxidative stress and fibrosis. A combination of unilateral nephrectomy, high-fat diet and low-dose streptozotocin was used to induce diabetic nephropathy in male Sprague-Dawley rats. Animals with fasting blood glucose >200 mg/dL were randomized to PPC, losartan, THC + PPC or THC + PPC + losartan. Untreated chronic kidney disease (CKD) animals had proteinuria, decreased creatinine clearance, and evidence of kidney fibrosis on histology. THC + PPC + losartan treatment significantly lowered blood pressure concurrent with increased messenger RNA levels of antioxidant copper-zinc-superoxide dismutase and decreased protein kinase C-α, kidney injury molecule-1 and type I collagen in the kidneys; there was decreased albuminuria and a trend for increased creatinine clearance compared to untreated CKD rats. There was decreased fibrosis on kidney histology in PPC-only and THC-treated CKD rats. Plasma levels of kidney injury molecule-1 were decreased in THC + PPC + losartan animals. In summary, add-on THC to losartan therapy improved antioxidant levels and decreased fibrosis in the kidneys, and lowered blood pressure in diabetic CKD rats.

The effects of 16-weeks of prebiotic supplementation and aerobic exercise training on inflammatory markers, oxidative stress, uremic toxins, and the microbiota in pre-dialysis kidney patients: a randomized controlled trial-protocol paper.

BACKGROUND: Chronic kidney disease (CKD) is characterized by dysbiosis, elevated levels of uremic toxins, systemic inflammation, and increased markers of oxidative stress. These factors lead to an increased risk of cardiovascular disease (CVD) which is common among CKD patients. Supplementation with high amylose maize resistant starch type 2 (RS-2) can change the composition of the gut microbiota, and reduce markers of inflammation and oxidative stress in patients with end-stage renal disease. However, the impact of RS-2 supplementation has not been extensively studied in CKD patients not on dialysis. Aerobic exercise training lowers certain markers of inflammation in CKD patients. Whether combining aerobic training along with RS-2 supplementation has an additive effect on the aforementioned biomarkers in predialysis CKD patients has not been previously investigated. METHODS: The study is being conducted as a 16-week, double-blind, placebo controlled, parallel arm, randomized controlled trial. Sixty stage 3-4 CKD patients (ages of 30-75 years) are being randomized to one of four groups: RS-2 & usual care, RS-2 & aerobic exercise, placebo (cornstarch) & usual care and placebo & exercise. Patients attend four testing sessions: Two baseline (BL) sessions with follow up visits 8 (wk8) and 16 weeks (wk16) later. Fasting blood samples, resting brachial and central blood pressures, and arterial stiffness are collected at BL, wk8 and wk16. A stool sample is collected for analysis of microbial composition and peak oxygen uptake is assessed at BL and wk16. Blood samples will be assayed for p-cresyl sulphate and indoxyl sulphate, c-reactive protein, tumor necrosis factor α, interleukin 6, interleukin 10, monocyte chemoattractant protein 1, malondialdehyde, 8-isoprostanes F2a, endothelin-1 and nitrate/nitrite. Following BL, subjects are randomized to their group. Individuals randomized to conditions involving exercise will attend three supervised moderate intensity (55-65% peak oxygen uptake) aerobic training sessions (treadmills, bikes or elliptical machine) per week for 16 weeks. DISCUSSION: This study has the potential to yield information about the effect of RS-2 supplementation on key biomarkers believed to impact upon the development of CVD in patients with CKD. We are examining whether there is an additive effect of exercise training and RS-2 supplementation on these key variables. TRIAL REGISTRATION: Clinicaltrials.gov Trial registration# NCT03689569 . 9/28/2018, retrospectively registered.

Poricoic acid A activates AMPK to attenuate fibroblast activation and abnormal extracellular matrix remodelling in renal fibrosis.

BACKGROUND: In chronic kidney disease, although fibrosis prevention is beneficial, few interventions are available that specifically target fibrogenesis. Poricoic acid A (PAA) isolated from Poria cocos exhibits anti-fibrotic effects in the kidney, however the underlying mechanisms remain obscure. PURPOSE: We isolated PAA and investigated its effects and the underlying mechanisms in renal fibrosis. STUDY DESIGN: Unilateral ureteral obstruction (UUO) and 5/6 nephrectomy (Nx) animal models and TGF-ß1-induced renal fibroblasts (NRK-49F) were used to investigate the anti-fibrotic activity of PAA and its underlying mechanisms. METHODS: Western blots, qRT-PCR, immunofluorescence staining, co-immunoprecipitation and molecular docking methods were used. Knock-down and knock-in of adenosine monophosphate-activated protein kinase (AMPK) in the UUO model and cultured NRK-49F cells were employed to verify the mechanisms of action of PAA. RESULTS: PAA improved renal function and alleviated fibrosis by stimulating AMPK and inhibiting Smad3 specifically in Nx and UUO models. Reduced AMPK activity was associated with Smad3 induction, fibroblast activation, and the accumulation and aberrant remodelling of extracellular matrix (ECM) in human renal puncture samples and cultured NRK-49F cells. PAA stimulated AMPK activity and decreased fibrosis in a dose-dependent manner, thus showing that AMPK was essential for PAA to exert its anti-fibrotic effects. AMPK deficiency reduced the anti-fibrotic effects of PAA, while AMPK overexpression enhanced its effect. CONCLUSION: PAA activated AMPK and further inhibited Smad3 specifically to suppress fibrosis by preventing aberrant ECM accumulation and remodelling and facilitating the deactivation of fibroblasts.

Combined melatonin and poricoic acid A inhibits renal fibrosis through modulating the interaction of Smad3 and ß-catenin pathway in AKI-to-CKD continuum.

BACKGROUND: Acute kidney injury (AKI) is one of the major risk factors for progression to chronic kidney disease (CKD) and renal fibrosis. However, effective therapies remain poorly understood. Here, we examined the renoprotective effects of melatonin and poricoic acid A (PAA) isolated from the surface layer of Poria cocos, and investigated the effects of combined therapy on the interaction of TGF-ß/Smad and Wnt/ß-catenin in a rat model of renal ischemia-reperfusion injury (IRI) and hypoxia/reoxygenation (H/R) or TGF-ß1-induced HK-2 cells. METHODS: Western blot and immunohistochemical staining were used to examine protein expression, while qRT-PCR was used to examine mRNA expression. Coimmunoprecipitation, chromatin immunoprecipitation, RNA interference, and luciferase reporter gene analysis were employed to explore the mechanisms of PAA and melatonin's renoprotective effects. RESULTS: PAA and combined therapy exhibited renoprotective and antifibrotic effects, but the underlying mechanisms were different during AKI-to-CKD continuum. Melatonin suppressed Smad-dependent and Smad-independent pathways, while PAA selectively inhibited Smad3 phosphorylation through distrupting the interactions of Smad3 with TGFßRI and SARA. Further studies demonstrated that the inhibitory effects of melatonin and PAA were partially depended on Smad3, especially PAA. Melatonin and PAA also inhibited the Wnt/ß-catenin pathway and its profibrotic downstream targets, and PAA performed better. We further determined that IRI induced a nuclear Smad3/ß-catenin complex, while melatonin and PAA disturbed the interaction of Smad3 and ß-catenin, and supplementing with PAA could enhance the inhibitory effects of melatonin on the TGF-ß/Smad and Wnt/ß-catenin pathways. CONCLUSIONS: Combined melatonin and PAA provides a promising therapeutic strategy to treat renal fibrosis during the AKI-to-CKD continuum.

Dietary natural flavonoids treating cancer by targeting aryl hydrocarbon receptor.

The role of aryl hydrocarbon receptor (AhR) as a ligand-activated transcription factor in the field of cancer has gradually been unveiled. A strong body of evidence indicated that AhR is implicated in cell proliferation and apoptosis, immune metabolism and other processes, which further affected tumor growth, survival, migration, and invasion. Therefore, AhR targeted therapy may become a new method for cancer treatment and provide a new direction for clinical tumor treatment. Astonishingly, the largest source of exposure of animals and humans to AhR ligands (synthetic and natural) comes from the diet. Myriad studies have described that various natural dietary chemicals can directly activate and/or inhibit the AhR signaling pathway. Of note, numerous natural products contribute to AhR active, of which dietary flavonoids are the largest class of natural AhR ligands. As interest in AhR and its ligands increases, it seems sensible to summarize current research on these ligands. In this review, we highlight the role of AhR in tumorigenesis and focus on the double effect of AhR in cancer therapy. We explored the molecular mechanism of AhR ligands on cancer through a few AhR agonists/antagonists currently in clinical practice. Ultimately, we summarize and highlight the latest progression of dietary flavonoids as AhR ligands in cancer inhibition, including the limitations and deficiencies of it in clinical research. This review will offer a comprehensive understanding of AhR and its dietary ligands which may dramatically pave the way for targeted cancer treatment.

Natural products against renin-angiotensin system for antifibrosis therapy.

Fibrosis is a final pathological feature of many chronic diseases, but few interventions are available that specifically target the pathogenesis of fibrosis. The highlights of common cellular and molecular mechanisms of fibrosis facilitate the discovery of effective antifibrotic drugs. The renin-angiotensin system (RAS) plays a central physiological role in the control of blood pressure and fluid homeostasis. Emerging evidence has revealed that activation of RAS was consistently found in fibrotic tissue. At the same time, as more components of the RAS are described, other pot Potential therapeutic targets emerge, so it seems sensible to revisit the contribution of RAS in anti-fibrotic therapy. So far, angiotensin converting enzyme inhibitors (ACEI) and angiotensin II type 1 receptor blockers (ARB) are the main commercial available drugs for intervening RAS. However, RAS inhibitors had lots of limitations in long-term application owing to occurring AngII and aldosterone escape. Over the past decades, natural products have aroused growing attention as potential RAS inhibitors due to their high efficacy and low risk of side effects. In this review, we revisit the contribution of RAS and its new members to anti-fibrotic therapy. Ultimately, we summarize and evaluate the use of natural products including isolated compounds, crude extracts and traditional Chinese herbal formulas to regulate RAS. These natural products can retard tissue fibrosis by targeting different RAS components, which provide us new therapeutic strategies to discover anti-fibrotic drugs.

Amylose resistant starch (HAM-RS2) supplementation increases the proportion of Faecalibacterium bacteria in end-stage renal disease patients: Microbial analysis from a randomized placebo-controlled trial.

INTRODUCTION: Many of the deleterious effects associated with chronic kidney disease (CKD) are secondary to the resultant systemic inflammation. The gut microbial changes caused by CKD are thought to perpetuate systemic inflammation. Therefore, strategies aimed at modulating the gut microbiota may be helpful in reducing complications associated with CKD. We hypothesized that supplementation with high-amylose maize resistant starch type 2 (HAM-RS2) would beneficially alter the gut microbiome and lead to lower levels of systemic inflammation. METHODS: A double-blind, parallel, randomized, placebo-controlled trial was performed comparing dietary supplementation of HAM-RS2 with placebo in patients with end-stage CKD. Fecal microbial data were obtained from a subset of patients after DNA extraction and 16s sequencing. FINDINGS: Supplementation of HAM-RS2 led to a decrease in serum urea, IL-6, TNFα, and malondialdehyde (P < 0.05). The Faecalibacterium genus was significantly increased in relative abundance following HAM-RS2 supplementation (HAM-RS2-Day 0: 0.40 ± 0.50 vs. HAM-RS2-Day 56: 3.21 ± 4.97 P = 0.03) and was unchanged by placebo (Control-Day 0: 0.72 ± 0.72 vs. Control-Day 56: 0.83 ± 1.57 P = 0.5). DISCUSSION: Supplementation of amylose resistant starch, HAM-RS2, in patients with CKD led to an elevation in Faecalibacterium and decrease in systemic inflammation. Microbial manipulation in CKD patients by using the prebiotic fiber may exert an anti-inflammatory effect through an elevation in the bacterial genera Faecalibacterium.

Phosphate Binder, Ferric Citrate, Attenuates Anemia, Renal Dysfunction, Oxidative Stress, Inflammation, and Fibrosis in 5/6 Nephrectomized CKD Rats.

Chronic kidney disease (CKD) causes anemia and impairs intestinal iron absorption. However, use of the phosphate binder ferric citrate (FC) increases body iron stores and hemoglobin levels in CKD patients. By intensifying oxidative stress and inflammation iron overload resulting from excessive use of intravenous iron can accelerate CKD progression. The present study explored the route of absorption and tissue distribution of iron with FC administration and its effect on renal function, histology, and inflammatory, oxidative, and fibrosis pathways in CKD rats. Male Sprague Dawley rats were randomized to sham-operated control (CTL) group and 5/6 nephrectomized (CKD) groups fed either regular or 4% FC-supplemented diets for 6 weeks. Animals were then sacrificed, and blood and target tissues were harvested and processed. The untreated CKD rats exhibited anemia, hypertension, upregulation of renal tissue inflammatory, oxidative, and fibrotic pathways, impaired nuclear translocation, and downregulation of Nrf2's target gene products and depletion of colonic epithelial tight junction proteins. FC administration raised serum iron, improved anemia, attenuated hyperphosphatemia, partially improved renal function, reduced oxidative stress, inflammation, and fibrosis, and restored colonic epithelial zonula occludens-1 protein abundance. Tissue iron staining detected presence of iron in epithelial cells and subepithelium of colon and in renal proximal tubules. In conclusion ferric citrate administration resulted in modest amelioration of renal function and histology and partial improvements of fibrosis, inflammation, and oxidative stress in the kidney tissues of CKD rats.

Novel RAS Inhibitors Poricoic Acid ZG and Poricoic Acid ZH Attenuate Renal Fibrosis via a Wnt/ß-Catenin Pathway and Targeted Phosphorylation of smad3 Signaling.

Renal fibrosis is a common end point of the progression of chronic kidney disease (CKD). Suppressing the development and progression of renal fibrosis is essential in the treatment of kidney disease. Our previous study demonstrated that the ethyl acetate extract of the surface layer of Poria cocos exhibited beneficial antitubulointerstitial fibrosis. In this study, we isolated new diterpene (PZF) and triterpenes (PZG and PZH) and examined their antifibrotic effect. TGF-ß1 upregulated the collagen I protein expression in HK-2 cells, and PZG and PZH treatment significantly inhibited the upregulated collagen I expression (TGF group 0.59 ± 0.08 vs TGF+PZG group 0.36 ± 0.08, P < 0.01; TGF+PZH group 0.39 ± 0.12, P < 0.01). Triterpenes, PZG and PZH, exhibited a stronger inhibitory effect on renal fibrosis and podocyte injury than PZF. PZG and PZH further showed a stronger inhibitory effect on the activation of the renin-angiotensin system (RAS) than PZF. Additionally, PZG and PZH markedly inhibited the activation of Wnt/ß-catenin signaling, which played an important role in fibrogenesis. Interestingly, PZG and PZH suppressed the TGF-ß/Smad pathway by selectively inhibiting the phosphorylation of Smad3 through blocking the interactions of SARA with TGFßI and Smad3. The analysis of the structure-activity relationship demonstrated that their antifibrotic effects were closely associated with the first six-membered ring structure and the number of carboxyl groups in this type of compounds. Additionally, fifteen known triterpenes were identified. These novel tetracyclic triterpenoid compounds provided the potential lead compounds for the research and development of antifibrosis drug, and they possessed the potential to be utilized as RAS inhibitors.

Dietary tetrahydrocurcumin reduces renal fibrosis and cardiac hypertrophy in 5/6 nephrectomized rats.

Tetrahydrocurcumin (THC) is the principal metabolite of curcumin and has antioxidant properties. In the present investigation, the effect of THC on renal and cardiovascular outcomes was studied in rats with chronic kidney disease (CKD). CKD rats were randomized following 5/6 nephrectomy to a special diet for 9 weeks which contained 1% THC (CKD+THC group). Low-dose polyenylphosphatidylcholine was used as a lipid carrier to increase bioavailability. Endpoints included tail blood pressure, normalized heart weight, plasma and urine biochemical data, and kidney tissue analyses. CKD animals demonstrated increased proteinuria, decreased creatinine clearance, hypertension, and cardiac hypertrophy. The antioxidant proteins CuZn SOD and glutathione peroxidase were decreased in the remnant kidney, while apoptosis (caspase-3) and fibrosis (alpha-SM actin) were increased. Renal fibrosis was confirmed histologically on trichrome staining. These pathologic changes were ameliorated in the CKD+THC group with significant decrease in proteinuria, hypertension, and kidney fibrosis. THC therapy restored levels of CuZn SOD and glutathione peroxidase. Consistent with prior reports, dietary THC did not improve nuclear Nrf2 levels. In summary, dietary THC therapy improved expression of antioxidant proteins in the remnant kidney, decreased renal fibrosis and proteinuria, and ameliorated hypertension in 5/6 nephrectomized rats.

An integrated lipidomics and metabolomics reveal nephroprotective effect and biochemical mechanism of Rheum officinale in chronic renal failure.

Chronic renal failure (CRF) is a major public health problem worldwide. Earlier studies have revealed salutary effects of rhubarb extracts in CRF. In this study, we employed lipidomic and metabolomic approaches to identify the plasma biomarkers and to determine the effect of treatment with petroleum ether, ethyl acetate and n-butanol extracts of rhubarb in a rat model of CRF with adenine-induced chronic tubulointerstitial nephropathy. In addition, clinical biochemistry, histological evaluation and pro-fibrotic protein expression were analyzed. Significant changes were found between the CRF and control groups representing characteristic phenotypes of rats with CRF. Treatment with the three rhubarb extracts improved renal injury and dysfunction, either fully or partially reversed the plasma metabolites abnormalities and attenuated upregulation of pro-fibrotic proteins including TGF-ß1, α-SMA, PAI-1, CTGF, FN and collagen-1. The nephroprotective effect of ethyl acetate extract was better than other extracts. The differential metabolites were closely associated with glycerophospholipid, fatty acid and amino acid metabolisms. The results revealed a strong link between renal tubulointerstitial fibrosis and glycerophospholipid metabolism and L-carnitine metabolism in the development of CRF. Amelioration of CRF with the three rhubarb extracts was associated with the delayed development and/or reversal the disorders in key metabolites associated with adenine-induced CRF.

New Options for Iron Supplementation in Maintenance Hemodialysis Patients.

End-stage renal disease results in anemia caused by shortened erythrocyte survival, erythropoietin deficiency, hepcidin-mediated impairment of intestinal absorption and iron release, recurrent blood loss, and impaired responsiveness to erythropoiesis-stimulating agents (ESAs). Iron malabsorption renders oral iron products generally ineffective, and intravenous (IV) iron supplementation is required in most patients receiving maintenance hemodialysis (HD). IV iron is administered at doses far exceeding normal intestinal iron absorption. Moreover, by bypassing physiologic safeguards, indiscriminate use of IV iron overwhelms transferrin, imposing stress on the reticuloendothelial system that can have long-term adverse consequences. Unlike conventional oral iron preparations, ferric citrate has recently been shown to be effective in increasing serum ferritin, hemoglobin, and transferrin saturation values while significantly reducing IV iron and ESA requirements in patients treated with HD. Ferric pyrophosphate citrate is a novel iron salt delivered by dialysate; by directly reaching transferrin, its obviates the need for storing administered iron and increases transferrin saturation without increasing serum ferritin levels. Ferric pyrophosphate citrate trials have demonstrated effective iron delivery and stable hemoglobin levels with significant reductions in ESA and IV iron requirements. To date, the long-term safety of using these routes of iron administration in patients receiving HD has not been compared to IV iron and therefore awaits future investigations.

Metabolomics insights into chronic kidney disease and modulatory effect of rhubarb against tubulointerstitial fibrosis.

Chronic kidney disease (CKD) is a major public health problem worldwide. Rhubarb has been shown to have nephroprotective and anti-fibrotic activities in patients with CKD. However, bioactive fractions and biochemical mechanism of anti-fibrotic properties of rhubarb remain unclear. Here we applied ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry together with univariate and multivariate statistical analyses to investigate the urinary metabolite profile in rats with adenine-induced CKD treated with the petroleum ether (PE)-, ethyl acetate (EA)- and n-butanol (BU)- extracts of rhubarb. Significant differences in renal function, kidney histopathology as well as metabolic profiles were observed between CKD and control rats. Changes in these parameters reflected characteristic phenotypes of CKD rats. We further identified a series of differential urinary metabolites for CKD rats, suggesting metabolic dysfunction in pathway of amino acid, purine, taurine, and choline metabolisms. Treatment with EA, BU and PE extracts of rhubarb improved renal function and histopathological abnormalities including interstitial fibrosis and inflammation, and either fully or partially reversed the abnormalities of the urinary metabolites. Among them, the nephroprotective effect of EA extract was stronger than BU and PE extracts. This work provides important mechanistic insights into the CKD and nephroprotective effects of different rhubarb extract against tubulo-interstitial fibrosis.

Dose-dependent deleterious and salutary actions of the Nrf2 inducer dh404 in chronic kidney disease.

Oxidative stress and inflammation play a central role in the progression and complications of chronic kidney disease (CKD) and are, in part, due to impairment of the Nrf2 system, which regulates the expression of antioxidant and detoxifying molecules. Natural Nrf2-inducing phytochemicals have been shown to ameliorate kidney disease in experimental animals. However, owing to adverse outcomes a clinical trial of a synthetic Nrf2 activator, bardoxolone methyl (BARD), in CKD patients was terminated. BARD activates Nrf2 via covalent modification of reactive cysteine residues in the Nrf2 repressor molecule, Keap1. In addition to Nrf2, Keap1 suppresses IKKB, the positive regulator of NF-κB. Treatment with a BARD analog, dh404, at 5-20mg/kg/day in diabetic obese Zucker rats exacerbates, whereas its use at 2mg/kg/day in 5/6 nephrectomized rats attenuates, CKD progression. We, therefore, hypothesized that deleterious effects of high-dose BARD are mediated by the activation of NF-κB. CKD (5/6 nephrectomized) rats were randomized to receive dh404 (2 or 10mg/kg/day) or vehicle for 12 weeks. The vehicle-treated group exhibited glomerulosclerosis; interstitial fibrosis and inflammation; activation of NF-κB; upregulation of oxidative, inflammatory, and fibrotic pathways; and suppression of Nrf2 activity and its key target gene products. Treatment with low-dose dh404 restored Nrf2 activity and expression of its target genes, attenuated activation of NF-κB and fibrotic pathways, and reduced glomerulosclerosis, interstitial fibrosis, and inflammation. In contrast, treatment with a high dh404 dosage intensified proteinuria, renal dysfunction, and histological abnormalities; amplified upregulation of NF-κB and fibrotic pathways; and suppressed the Nrf2 system. Thus therapy with BARD analogs exerts a dose-dependent dimorphic impact on CKD progression.

Green tea polyphenol (-)-epigallocatechin-3-gallate restores Nrf2 activity and ameliorates crescentic glomerulonephritis.

Crescentic glomerulonephritis (GN) is the most severe form of GN and is associated with significant morbidity and mortality despite aggressive immunotherapy with steroids, cytotoxic drugs, and plasmapheresis. We examined the therapeutic efficacy of the green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG, 50 mg/kg BW/day x3 weeks), a potent anti-inflammatory and anti-oxidant agent, on experimental crescentic GN induced in 129/svJ mice by administration of rabbit anti-mouse glomerular basement membrane sera. Routine histology and key molecules involved in inflammatory and redox signaling were studied. EGCG treatment significantly reduced mortality, decreased proteinuria and serum creatinine, and markedly improved renal histology when compared with vehicle-treated mice. The improvements in renal function and histology were accompanied by the restoration of Nrf2 signaling (which was impaired in vehicle-treated mice) as shown by increased nuclear translocation of Nrf2 and cytoplasmic glutamate cysteine ligase catalytic subunit, glutamate cysteine ligase modifier subunit, and glutathione peroxidase. EGCG-treated mice also showed reduction in p-Akt, p-JNK, p-ERK1/2 and p-P38 as well as restoration of PPARγ and SIRT1 levels. Lower dose of EGCG (25 mg/kg BW/day x2 weeks) treatment also significantly decreased proteinuria and serum creatinine, and markedly improved renal histology when compared with vehicle-treated mice. Thus, our data illustrate the efficacy of EGCG in reversing the progression of crescentic GN in mice by targeting multiple signaling and inflammatory pathways as well as countering oxidative stress.

High amylose resistant starch diet ameliorates oxidative stress, inflammation, and progression of chronic kidney disease.

Inflammation is a major mediator of CKD progression and is partly driven by altered gut microbiome and intestinal barrier disruption, events which are caused by: urea influx in the intestine resulting in dominance of urease-possessing bacteria; disruption of epithelial barrier by urea-derived ammonia leading to endotoxemia and bacterial translocation; and restriction of potassium-rich fruits and vegetables which are common sources of fermentable fiber. Restriction of these foods leads to depletion of bacteria that convert indigestible carbohydrates to short chain fatty acids which are important nutrients for colonocytes and regulatory T lymphocytes. We hypothesized that a high resistant starch diet attenuates CKD progression. Male Sprague Dawley rats were fed a chow containing 0.7% adenine for 2 weeks to induce CKD. Rats were then fed diets supplemented with amylopectin (low-fiber control) or high fermentable fiber (amylose maize resistant starch, HAM-RS2) for 3 weeks. CKD rats consuming low fiber diet exhibited reduced creatinine clearance, interstitial fibrosis, inflammation, tubular damage, activation of NFkB, upregulation of pro-inflammatory, pro-oxidant, and pro-fibrotic molecules; impaired Nrf2 activity, down-regulation of antioxidant enzymes, and disruption of colonic epithelial tight junction. The high resistant starch diet significantly attenuated these abnormalities. Thus high resistant starch diet retards CKD progression and attenuates oxidative stress and inflammation in rats. Future studies are needed to explore the impact of HAM-RS2 in CKD patients.

Iron toxicity: relevance for dialysis patients.

Iron deficiency is common among patients with advanced kidney disease, particularly those requiring hemodialysis. Intravenous iron is a convenient treatment to supplement iron and is widely used among hemodialysis patients. Its efficacy is well established that, with treatment, hemoglobin levels rise and erythropoiesis-stimulating agent dose requirements are reduced. However, the safety of intravenous iron with respect to patient-centered outcomes has not been adequately studied. A variety of studies have indicated potential safety concerns, but most have been of small numbers of patients and with end points studied that have unclear clinical relevance. In this study, issues related to iron toxicity are reviewed.

Iron overdose: a contributor to adverse outcomes in randomized trials of anemia correction in CKD.

Administration of intravenous iron to supplement erythropoiesis stimulating agents (ESAs) has become a common practice in the management of anemia in patients with end-stage renal disease. Randomized clinical trials of anemia correction in this population have shown more adverse outcomes in CKD and ESRD patients assigned to the higher hemoglobin targets. Retrospective analysis of these trials suggests that morbidity is higher in subjects who fail to achieve the designated hemoglobin target and are typically exposed to higher doses of ESAs and iron than those that easily achieve the intended targets. Intravenous iron administration circumvents the natural biologic mechanisms for handling and utilization of iron. There is in vitro and in vivo evidence that intravenous iron preparations can cause oxidative stress, endothelial dysfunction, inflammation, impaired immunity, and renal injury. Since iron overload is known to promote endothelial dysfunction, cardiovascular disease, and immune dysfunction which are the leading causes of premature mortality in CKD and ESRD patients, it is imperative to exercise caution with the use of IV iron preparations in this population. The present review is intended to provide a brief overview of the potential adverse effects of the overzealous use of these agents.

The green tea polyphenol (-)-epigallocatechin-3-gallate ameliorates experimental immune-mediated glomerulonephritis.

The unchecked overproduction of reactive oxygen and nitrogen species by inflammatory cells can cause tissue damage, intensify inflammation, promote apoptosis, and accelerate the progression of immune-mediated glomerulonephritis (GN). Here we tested whether the anti-inflammatory and antioxidant properties of the green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) favorably affect the development of immune-mediated GN. Pretreatment of 129/svJ mice with EGCG from 2 days before to 2 weeks after the induction of GN led to reduced proteinuria and serum creatinine, and marked improvement in renal histology when compared with vehicle-pretreated diseased mice. This pretreatment reduced oxidative stress, and normalized osteopontin, p65/nuclear factor-κB, inducible nitric oxide synthase, nitric oxide metabolites, p-Akt, phosphorylated extracellular signal-regulated kinases 1 and 2, p47phox, and myeloperoxidase, all of which were elevated in vehicle-pretreated diseased mice. Levels of glutathione peroxidase and peroxisome proliferator-activated receptor-γ (PPARγ), both reduced in the vehicle-pretreated diseased mice, were normalized. This renoprotective effect was reversed by concomitant administration of the PPARγ antagonist GW9662 throughout the EGCG pretreatment period. Importantly, mortality and renal dysfunction were significantly attenuated even when the polyphenol treatment was initiated 1 week after the onset of GN. Thus, EGCG reversed the progression of immune-mediated GN in mice by targeting redox and inflammatory pathways.

A novel cystine based antioxidant attenuates oxidative stress and hepatic steatosis in diet-induced obese mice.

Nonalcoholic fatty liver disease (NAFLD) is the most common form of liver pathologies and is associated with obesity and the metabolic syndrome. Here, we investigated the molecular mechanisms by which a novel cystine based glutathione precursor with added selenomethionine (F1) prevents hepatic steatosis in a moderate high fat dietary model of NAFLD. Adult (8 weeks old), male apolipoprotein E (ApoE)-/- mice were fed with a normal diet (ND) or high fat diet (HFD), consisting of 21% fat and 0.21% cholesterol, with or without dietary supplementation of F1 (3 g/kg food) for 16 weeks. Compared with ApoE-/- mice fed with ND with or without F1, ApoE-/- mice fed with HFD exhibited significant weight gain, hepatomegaly, and increased serum cholesterol and triglycerides levels with no change in serum albumin levels. High resolution light and electron microscopy revealed micro-and macro-vesicular steatosis in ApoE-/- mice fed on a HFD. HFD-induced obesity also led to increased lipogenesis, oxidative stress, activation of c-Jun-NH(2)-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), perturbation of the BAX/BCL-2 rheostat, hepatocyte apoptosis, and activation of caspases 9 and 3. F1 fully prevented the adverse effects of HFD on serum triglyceride levels, body and liver weights, and hepatic steatosis and substantially attenuated HFD-induced increase in lipogenesis, oxidative stress, kinase activation, apoptotic signaling, and hepatocyte ultrastructural abnormalities. These results demonstrate that administration of F1, a glutathione precursor, ameliorates HFD-induced hepatic steatosis in ApoE-/- mice and emphasizes the role of oxidative stress in diet-induced obesity and hepatic steatosis.