Epigallocatechin-3-Gallate Attenuates Oxidative Stress and Inflammation in Obstructive Nephropathy via NF-κB and Nrf2/HO-1 Signalling Pathway Regulation

The anti-inflammatory properties of green tea extract protect against gentamicin-induced kidney injury

We assessed in vivo the protective effects and underlying antioxidant and anti-inflammatory properties of dry green tee extract (GTE) on glomerular and tubular kidney function and structure in an experimental model of gentamicin (GEN)-induced nephrotoxicity. Wistar rats were divided into four groups and treated daily for 10 days. The control group received distilled water; the GTE group received 20 μg/g body weight (BW) GTE by gavage; the GEN group received 100 mg/g BW GEN intraperitoneally; and the GEN+GTE group received GTE and GEN simultaneously, as described above. At the beginning and end of treatment, the serum creatinine, fractional excretion of sodium and potassium, and plasma heme oxygenase (HO)-1 levels and oxidative stress (OS) were assessed. At the end of the experiment, kidney fragments were collected for histological evaluation and immunohistochemical studies of cyclooxygenase (COX)-2 and nuclear factor (NF)kB. The levels of interleukin (IL)-1b, IL-4, IL-6, IL-10 and monocyte chemotactic protein (MCP)-1 were measured in kidney tissue. The results showed that GTE attenuated significantly kidney structural injury and prevented GEN-induced kidney functional injury (glomerular and tubular function). GTE significantly attenuated the kidney tissue increase of the proinflammatory mediators NF-kB, COX2, IL-1b and MCP-1 and significantly increased the kidney expression of the anti-inflammatory cytokines IL-6 and IL-10. However, GTE did not prevent OS increase in GEN-treated animals. In conclusion, GTE protected against GEN nephrotoxicity, likely due to direct blockade of the inflammatory cascade, which might had occurred independently of its antioxidant effect.

Maternal Polyphenols and Offspring Cardiovascular-Kidney-Metabolic Health

BACKGROUND

The convergence of cardiovascular, kidney, and metabolic disorders at the pathophysiological level has led to the recognition of cardiovascular-kidney-metabolic (CKM) syndrome, which represents a significant global health challenge. Polyphenols, a group of phytochemicals, have demonstrated potential health-promoting effects.

METHODS

This review highlights the impact of maternal polyphenol supplementation on the CKM health of offspring.

RESULTS

Initially, we summarize the interconnections between polyphenols and each aspect of CKM syndrome. We then discuss in vivo studies that have investigated the use of polyphenols during pregnancy and breastfeeding, focusing on their role in preventing CKM syndrome in offspring. Additionally, we explore the common mechanisms underlying the protective effects of maternal polyphenol supplementation.

CONCLUSIONS

Overall, this review underscores the potential of early-life polyphenol interventions in safeguarding against CKM syndrome in offspring. It emphasizes the importance of continued research to advance our understanding and facilitate the clinical translation of these interventions.

Epigallocatechin-3-gallate attenuates the sulfamethoxazole-induced immunotoxicity and reduces SMZ residues in Procambarus clarkii

Sulfamethoxazole (SMZ) is a commonly used antibiotic in aquaculture, and its residues in water bodies pose a significant threat to aquatic organisms in the water environment. In the present study, epigallocatechin-3-gallate (EGCG), a catecholamine, was used to mitigate the immunotoxicity caused by SMZ exposure in Procambarus clarkii. EGCG reduced the apoptosis rate, which was elevated by SMZ exposure, and increased the total hemocyte count. Simultaneously, EGCG enhanced the activities of enzymes related to antibacterial and antioxidant activities, such as superoxide dismutase (SOD), catalase (CAT), lysozyme (LZM), acid phosphatase (ACP), and GSH, which were decreased following SMZ exposure. Hepatopancreatic histology confirmed that EGCG ameliorated SMZ-induced tissue damage caused by SMZ exposure. In addition to EGCG attenuating SMZ-induced immunotoxicity in crayfish, we determined that EGCG can effectively reduce SMZ residues in crayfish exposed to SMZ. In addition, at the genetic level, the expression levels of genes related to the immune response in hemocytes were disrupted after SMZ exposure, and EGCG promoted their recovery and stimulated an increase in the expression levels of metabolism-related transcripts in hemocytes. The transcriptome analysis was conducted, and "phagosome" and "apoptosis" pathways were shown to be highlighted using Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. To the best of our knowledge, this is the first study to confirm that EGCG attenuates SMZ-induced immunotoxicity in aquatic animals and reduces SMZ residues in aquatic animals exposed to SMZ. Our study contributes to the understanding of the mechanisms by which EGCG reduces the immunotoxicity of antibiotic residues in aquatic animals.

Groundnut and tree nuts: a comprehensive review on their lipid components, phytochemicals, and nutraceutical properties

The health benefits of nut consumption have been extensively demonstrated in observational studies and intervention trials. Besides the high nutritional value, countless evidences show that incorporating nuts into the diet may contribute to health promotion and prevention of certain diseases. Such benefits have been mostly and certainly attributed not only to their richness in healthy lipids (plentiful in unsaturated fatty acids), but also to the presence of a vast array of phytochemicals, such as polar lipids, squalene, phytosterols, tocochromanols, and polyphenolic compounds. Thus, many nut chemical compounds apply well to the designation "nutraceuticals," a broad umbrella term used to describe any food component that, in addition to the basic nutritional value, can contribute extra health benefits. This contribution analyses the general chemical profile of groundnut and common tree nuts (almond, walnut, cashew, hazelnut, pistachio, macadamia, pecan), focusing on lipid components and phytochemicals, with a view on their bioactive properties. Relevant scientific literature linking consumption of nuts, and/or some of their components, with ameliorative and/or preventive effects on selected diseases - such as cancer, cardiovascular, metabolic, and neurodegenerative pathologies - was also reviewed. In addition, the bioactive properties were analyzed in the light of known mechanistic frameworks.

Association between tea drinking and disability levels in older Chinese adults: a longitudinal analysis

Objective

As the global population ages, disability among the elderly presents unprecedented challenges for healthcare systems. However, limited research has examined whether dietary interventions like tea consumption may alleviate and prevent disability in older adults. As an important dietary therapy, the health benefits of tea drinking have gained recognition across research disciplines. Therefore, this study aimed to investigate the association between tea drinking habits and disability levels in the elderly Chinese population.

Methods

Leveraging data from the 2008 to 2018 waves of the Chinese Longitudinal Healthy Longevity Survey, we disaggregated tea drinking frequency and activities of daily living (ADL) measures and deployed fixed-effect ordered logit models to examine the tea-disability association for the first time. We statistically adjusted for potential confounders and conducted stratified analyses to assess heterogeneity across subpopulations.

Results

Multivariable fixed-effect ordered logistic regression suggested tea drinking has protective effects against ADL disability. However, only daily tea drinking was associated with lower risks of basic activities of daily living (BADL) disability [odds ratio (OR) = 0.61; 95% confidence interval (CI), 0.41-0.92] and lower levels of instrumental activities of daily living (IADL) disability (OR = 0.78; 95% CI, 0.64-0.95). Stratified analyses indicated heterogeneous effects across age and income groups. Daily tea drinking protected against BADL (OR = 0.26 and OR = 0.28) and IADL disability (OR = 0.48 and OR = 0.45) for adults over 83 years old and high-income households, respectively.

Conclusion

We found that drinking tea almost daily was protective against disability in elderly people, warranting further research into optimal dosages. Future studies should utilize more rigorous causal inference methods and control for confounders.

Epigallocatechin-3-gallate in combination with corticosteroids mitigates heat stress-induced acute kidney injury through modulating heat shock protein 70 and toll-like receptor 4-dependent pathways

Recently, recurrent heat stress (HS) and dehydration have been exhibited to give rise to kidney disease epidemic in hot regions. The current study was carried out to estimate a possible renoprotective effect of dexamethasone (Dexa) and epigallocatechin-3-gallate (EGCG) as a heat shock protein (HSP)-70 inhibitor on HS-induced nephropathy. In total, five groups of rats were used: control group, HS group (exposed to heat for 40 min), Dexa+HS group (rats were injected with Dexa i.p.15 mg/kg/day for 3 days followed by HS), EGCG+HS group (rats received EGCG 100 mg/kg/day, orally, for 7 days followed by HS), and EGCG+ Dexa +HS group (rats received EGCG 100 mg/kg/day, orally, for 7 days and injected Dexa as described along the last 3 days followed by HS). Kidney sections were stained with H&E and scored for tubular injury. A marked increase in creatinine, urea, malondialdehyde (MDA), monocyte chemoattractant protein (MCP)-1, HSP-70, nuclear factor kappa B (NF-κB), toll-like receptor 4 (TLR-4) and Caspase-3 expression was observed after HS induction (p < 0.001). Treatment with EGCG combined with Dexa notably reduced tubular injury, MCP-1, HSP-70, NF-κB, and TLR-4 levels (p < 0.001). Moreover, it increased IL-10, antioxidant capacity and Bcl-2 expression levels in the kidney (p < 0.001). This renoprotective impact might be attributed to anti-inflammatory, antioxidant, and anti-apoptotic mechanisms besides interfering with TLR-4-mediated NF-κB activation pathway.

Cordyceps militaris polysaccharide alleviates ovalbumin-induced allergic asthma through the Nrf2/HO-1 and NF-κB signaling pathways and regulates the gut microbiota

Polysaccharides, as one of the main types of bioactive components of Cordyceps militaris, have anti-allergic asthma effects. Herein, an ovalbumin-induced allergic asthma mouse model was established to assess the potential mechanisms of the separated and purified Cordyceps militaris polysaccharide (CMP). CMP is an α-pyranose with a molecular weight of 15.94 kDa that consists of Glc, Man, Gal, Xyl, Ara and GlcA in a molar ratio of 81.25:21.96:13.88:3.92:3.58:1.00. CMP improved inflammatory cytokine levels, alleviated the histopathological changes in the lung and intestinal tissues, regulated the expression of mRNA and proteins related to oxidative stress and inflammatory pathways, reversed gut dysbiosis at the phylum and family levels and improved microbiota function in allergic asthma mice. Moreover, it was found that the levels of inflammatory cytokines in lung tissue of mice were significantly correlated with some intestinal microbial communities. Overall, CMP improved oxidative stress and the inflammatory response in allergic asthma mice by regulating the Nrf2/HO-1 and NF-κB signaling pathways, which may be closely correlation with maintaining the stability of the gut microbiota.

Natural products for kidney disease treatment: Focus on targeting mitochondrial dysfunction

The patients with kidney diseases are increasing rapidly all over the world. With the rich abundance of mitochondria, kidney is an organ with a high consumption of energy. Hence, renal failure is highly correlated with the breakup of mitochondrial homeostasis. However, the potential drugs targeting mitochondrial dysfunction are still in mystery. The natural products have the superiorities to explore the potential drugs regulating energy metabolism. However, their roles in targeting mitochondrial dysfunction in kidney diseases have not been extensively reviewed. Herein, we reviewed a series of natural products targeting mitochondrial oxidative stress, mitochondrial biogenesis, mitophagy, and mitochondrial dynamics. We found lots of them with great medicinal values in kidney disease. Our review provides a wide prospect for seeking the effective drugs targeting kidney diseases.

Is Nuclear Factor Erythroid 2-Related Factor 2 a Target for the Intervention of Cytokine Storms?

The term "cytokine storm" describes an acute pathophysiologic state of the immune system characterized by a burst of cytokine release, systemic inflammatory response, and multiple organ failure, which are crucial determinants of many disease outcomes. In light of the complexity of cytokine storms, specific strategies are needed to prevent and alleviate their occurrence and deterioration. Nuclear factor erythroid 2-related factor 2 (NRF2) is a CNC-basic region-leucine zipper protein that serves as a master transcription factor in maintaining cellular redox homeostasis by orchestrating the expression of many antioxidant and phase II detoxification enzymes. Given that inflammatory response is intertwined with oxidative stress, it is reasonable to assume that NRF2 activation limits inflammation and thus cytokine storms. As NRF2 can mitigate inflammation at many levels, it has emerged as a potential target to prevent and treat cytokine storms. In this review, we summarized the cytokine storms caused by different etiologies and the rationale of interventions, focusing mainly on NRF2 as a potential therapeutic target.

Epigallocatechin-3-gallate (EGCG) attenuates inflammatory responses and oxidative stress in lipopolysaccharide (LPS)-induced endometritis via silent information regulator transcript-1 (SIRT1)/nucleotide oligomerization domain (NOD)-like receptor pyrin domain-containing 3 (NLRP3) pathway

The protective effects of epigallocatechin-3-gallate (EGCG) on lipopolysaccharide (LPS)-induced endometritis in vivo and in vitro will be explored in this study. The endometritis model was induced in female BALB/c mice uterus by perfusion with lipopolysaccharide (LPS) and EGCG were administered at 1 h before LPS induction. The primary bovine endometrial epithelial cells (BEECs) were treated with EGCG for 1 h before LPS stimulation. Uterine histopathological changes, myeloperoxidase (MPO) activity, inflammatory cytokine levels and oxidative stress markers were determined. The extent of Bax, Bcl-2, cleaved caspase-3, silent information regulator transcript-1 (SIRT1), nucleotide oligomerization domain (NOD)-like receptor pyrin domain-containing 3 (NLRP3), apoptosis-associated speck-like protein (ASC) and Caspase1 was detected by Western blot and real-time quantitative PCR assays. The results showed that EGCG significantly reversed the LPS-induced uterine histopathological changes, MPO activity, pro-inflammatory cytokine levels. Additionally, EGCG decreased oxidative stress and reduced cell apoptosis by upregulating SIRT1 expression, downregulating the NLRP3 inflammasome activation. These findings indicated that EGCG exerted its greatest protective effects by blocking inflammatory responses, lowering oxidative stress, and reducing apoptosis via the SIRT1/NLRP3, making its promising candidate treatment for endometritis.

Downregulation of P300/CBP-Associated Factor Protects from Vascular Aging via Nrf2 Signal Pathway Activation

Increasing evidence has shown that vascular aging has a key role in the pathogenesis of vascular diseases. P300/CBP-associated factor (PCAF) is involved in many vascular pathological processes, but the role of PCAF in vascular aging is unknown. This study aims to explore the role and underlying mechanism of PCAF in vascular aging. The results demonstrated that the expression of PCAF was associated with age and aging, and remarkably increased expression of PCAF was present in human atherosclerotic coronary artery. Downregulation of PCAF could reduce angiotensin II (AngII)-induced senescence of rat aortic endothelial cells (ECs) in vitro. In addition, inhibition of PCAF with garcinol alleviated AngII-induced vascular senescence phenotype in mice. Downregulation of PCAF could alleviate AngII-induced oxidative stress injury in ECs and vascular tissue. Moreover, PCAF and nuclear factor erythroid-2-related factor 2 (Nrf2) could interact directly, and downregulation of PCAF alleviated vascular aging by promoting the activation of Nrf2 and enhancing the expression of its downstream anti-aging factors. The silencing of Nrf2 with small interfering RNA attenuated the protective effect of PCAF downregulation from vascular aging. These findings indicate that downregulation of PCAF alleviates oxidative stress by activating the Nrf2 signaling pathway and ultimately inhibits vascular aging. Thus, PCAF may be a promising target for aging-related cardiovascular disease.

The Effect of Polyphenols on Kidney Disease: Targeting Mitochondria

Mitochondrial function, including oxidative phosphorylation (OXPHOS), mitochondrial biogenesis, and mitochondria dynamics, are essential for the maintenance of renal health. Through modulation of mitochondrial function, the kidneys are able to sustain or recover acute kidney injury (AKI), chronic kidney disease (CKD), nephrotoxicity, nephropathy, and ischemia perfusion. Therapeutic improvement in mitochondrial function in the kidneys is related to the regulation of adenosine triphosphate (ATP) production, free radicals scavenging, decline in apoptosis, and inflammation. Dietary antioxidants, notably polyphenols present in fruits, vegetables, and plants, have attracted attention as effective dietary and pharmacological interventions. Considerable evidence shows that polyphenols protect against mitochondrial damage in different experimental models of kidney disease. Mechanistically, polyphenols regulate the mitochondrial redox status, apoptosis, and multiple intercellular signaling pathways. Therefore, this review attempts to focus on the role of polyphenols in the prevention or treatment of kidney disease and explore the molecular mechanisms associated with their pharmacological activity.

Plants as a Source of Anticancer Agents: From Bench to Bedside

Cancer is the second leading cause of death after cardiovascular diseases. Conventional anticancer therapies are associated with lack of selectivity and serious side effects. Cancer hallmarks are biological capabilities acquired by cancer cells during neoplastic transformation. Targeting multiple cancer hallmarks is a promising strategy to treat cancer. The diversity in chemical structure and the relatively low toxicity make plant-derived natural products a promising source for the development of new and more effective anticancer therapies that have the capacity to target multiple hallmarks in cancer. In this review, we discussed the anticancer activities of ten natural products extracted from plants. The majority of these products inhibit cancer by targeting multiple cancer hallmarks, and many of these chemicals have reached clinical applications. Studies discussed in this review provide a solid ground for researchers and physicians to design more effective combination anticancer therapies using plant-derived natural products.

Ethnobotanical, pharmacological, phytochemical, and clinical investigations on Moroccan medicinal plants traditionally used for the management of renal dysfunctions

ETHNOPHARMACOLOGICAL RELEVANCE

Renal disease is a significant public health concern that affects people all over the world. The main limitations of conventional therapy are the adverse reaction on human health and the expensive cost of drugs. Indeed, it is necessary to develop new therapeutic strategies that are less expensive and have fewer side effects. As a consequence of their natural compounds, medicinal plants can be used as an alternative therapy to cure various ailments including kidney diseases.

OBJECTIVE

of the study: This review paper has two principal goals: (1) to inventory and describe the plants and their ancestral use by Moroccan society to cure renal problems, (2) to link traditional use with scientific confirmations (preclinical and clinical).

METHODS

To analyze pharmacological effects, phytochemical, and clinical trials of plants, selected for renal therapy, a bibliographical search was undertaken by examining ethnobotanical investigations conducted in Morocco between 1991 and 2019 and consulting peer-reviewed papers from all over the world.

RESULTS

Approximately 290 plant species, spanning 81 families and 218 genera have been reported as being utilized by Moroccans to manage renal illness. The most frequently mentioned species in Morocco were Herniaria hirsuta subsp. cinerea (DC.), Petroselinum crispum (Mill.) Fuss and Rosmarinus officinalis L. The leaves were the most frequently used plant parts, followed by the whole plant. Decoction and infusion were the most popular methods of preparation. A record of 71 plant species was studied in vitro and/or in vivo for their therapeutic efficacy against kidney disorders, including 10 plants attempting to make it to the clinical stage. Twenty compounds obtained from 15 plants have been studied for the treatment of kidney diseases.

CONCLUSION

Medicinal herbs could be a credible alternative therapy for renal illness. However, additional controlled trials are required to confirm their efficiency in patients with kidney failure. Overall, this work could be used as a database for future exploration.

Tea polyphenols alleviates acetochlor-induced apoptosis and necroptosis via ROS/MAPK/NF-κB signaling in Ctenopharyngodon idellus kidney cells

Overuse of acetochlor pollutes soil and rivers, causing threats to the ecosystem. Studies found that acetochlor exposure could damage multiple organs and tissues in fish and mammal. Tea polyphenols (TP), a natural antioxidant that extracted from tea, has been widely used in food and feed additions. However, the mechanism by which acetochlor causes tissue damage is unclear, and its mitigating agent has yet to be developed. Therefore, we established acetochlor exposure and TP mitigation models by treating Ctenopharyngodon idellus kidney (CIK) cells with 20 μM acetochlor and/or 2.5 μg/mL TP for 24 h, and detected the programmed cell death and its related pathways. The results showed that acetochlor exposure modified antioxidant enzyme activities, induced oxidative stress, resulted in the decline of MMP and ATP levels, enhanced glycolysis and lactate accumulation, and triggered apoptosis and necroptosis in CIK cells. However, TP could inhibit CYP450s expression, activate Nrf2 pathway, enhance antioxidant capacity, further effectively alleviate acetochlor-induced CIK cell death. Overall, the present study proved that acetochlor exposure triggered mitochondrial damage and lactate accumulation-mediated apoptosis and necroptosis through CYP450s/ROS/MAPK/NF-κB pathway. Furthermore, TP could alleviate effectively cell death through relieving oxidative stress and lightening Warburg-like effect.

Polyphenols and Their Metabolites in Renal Diseases: An Overview

Kidney diseases constitute a worldwide public health problem, contributing to morbidity and mortality. The present study aimed to provide an overview of the published data regarding the potential beneficial effects of polyphenols on major kidney diseases, namely acute kidney injury, chronic kidney disease, diabetic nephropathy, renal cancer, and drug-induced nephrotoxicity. This study consists of a bibliographical review including in vitro and in vivo studies dealing with the effects of individual compounds. An analysis of the polyphenol metabolome in human urine was also conducted to estimate those compounds that are most likely to be responsible for the kidney protective effects of polyphenols. The biological effects of polyphenols can be highly attributed to the modulation of specific signaling cascades including those involved in oxidative stress responses, anti-inflammation processes, and apoptosis. There is increasing evidence that polyphenols afford great potential in renal disease protection. However, this evidence (especially when in vitro studies are involved) should be considered with caution before its clinical translation, particularly due to the unfavorable pharmacokinetics and extensive metabolization that polyphenols undergo in the human body. Future research should consider polyphenols and their metabolites that indeed reach kidney tissues.

Nutrition, Immunology, and Kidney: Looking Beyond the Horizons

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is epidemic throughout the word. Despite various novel therapeutic opportunities, CKD is still associated with high morbidity and mortality. In CKD, patient's chronic inflammation is frequent and related with adverse outcomes. Both innate and adaptive immunity are dysfunctional in CKD. Therefore, it is plausible to interfere with dysfunctional immunity in these patients. In the current review, we present the updated experimental and clinical data summarizing the effects of nutritional interventions including natural products and dietary supplements on immune dysfunction in the context of CKD.

RECENT FINDINGS

Nutritional interventions including natural products and dietary supplements (e.g., curcumin, sulforaphane, resistant starch, anthocyanin, chrysin, short chain fatty acids, fish oil resistant starch) slow down the inflammation by at least 6 mechanisms: (i) decrease nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB); (ii) decrease NLR family pyrin domain containing 3 (NLRP3); (iii) decrease interleukin-1 (IL-1), decrease interleukin-6 (IL-6) secretion; (iv) decrease polymorphonuclear priming); (v) promote anti-inflammatory pathways (nuclear factor-erythroid factor 2-related factor 2 (NFR2); (vi) increase T regulatory (Tregs) cells). Natural products and dietary supplements may provide benefit in terms of kidney health. By modulation of nutritional intake, progression of CKD may be delayed.

Advances in adjunct therapy against tuberculosis: Deciphering the emerging role of phytochemicals

Eastern countries are a major source of medicinal plants, which set up a rich source of ethnopharmacologically known medicines used in the treatment of various diseases. These traditional medicines have been known as complementary, alternative, or nonconventional therapy across globe for ages. Tuberculosis (TB) poses a huge global burden and leads to maximum number of deaths due to an infectious agent. Treatment of TB using Directly Observed Treatment Short-course (DOTS) therapy comprises multiple antibiotics is quite lengthy and causes serious side-effects in different organs. The length of the TB treatment leads to withdrawal from the patients, which paves the way for the emergence of drug resistance in the bacterial population. These concerns related to therapy need serious and immediate interventions. Traditional medicines using phytochemicals has shown to provide tremendous potential in TB treatment, mainly in the eradication of Mycobacterium tuberculosis (M.tb), increasing natural immunity, and managing the side effects of anti-TB drugs. This review describes the antituberculosis potential of selected ethnopharmacologically important phytochemicals as potential immune-modulator and as an adjunct-therapy in TB. This review will be a useful reference for researchers working on ethnopharmacology and will open the door for the discovery of novel agents as an adjunct-therapy to tuberculosis.

Catechins: Therapeutic Perspectives in COVID-19-Associated Acute Kidney Injury

Data obtained from several intensive care units around the world have provided substantial evidence of the strong association between impairment of the renal function and in-hospital deaths of critically ill COVID-19 patients, especially those with comorbidities and requiring renal replacement therapy (RRT). Acute kidney injury (AKI) is a common renal disorder of various etiologies characterized by a sudden and sustained decrease of renal function. Studies have shown that 5-46% of COVID-19 patients develop AKI during hospital stay, and the mortality of those patients may reach up to 100% depending on various factors, such as organ failures and RRT requirement. Catechins are natural products that have multiple pharmacological activities, including anti-coronavirus and reno-protective activities against kidney injury induced by nephrotoxic agents, obstructive nephropathies and AKI accompanying metabolic and cardiovascular disorders. Therefore, in this review, we discuss the anti-SARS-CoV-2 and reno-protective effects of catechins from a mechanistic perspective. We believe that catechins may serve as promising therapeutics in COVID-19-associated AKI due to their well-recognized anti-SARS-CoV-2, and antioxidant and anti-inflammatory properties that mediate their reno-protective activities.

The Therapeutic Strategies for Uremic Toxins Control in Chronic Kidney Disease

Uremic toxins (UTs) are mainly produced by protein metabolized by the intestinal microbiota and converted in the liver or by mitochondria or other enzymes. The accumulation of UTs can damage the intestinal barrier integrity and cause vascular damage and progressive kidney damage. Together, these factors lead to metabolic imbalances, which in turn increase oxidative stress and inflammation and then produce uremia that affects many organs and causes diseases including renal fibrosis, vascular disease, and renal osteodystrophy. This article is based on the theory of the intestinal-renal axis, from bench to bedside, and it discusses nonextracorporeal therapies for UTs, which are classified into three categories: medication, diet and supplement therapy, and complementary and alternative medicine (CAM) and other therapies. The effects of medications such as AST-120 and meclofenamate are described. Diet and supplement therapies include plant-based diet, very low-protein diet, probiotics, prebiotics, synbiotics, and nutraceuticals. The research status of Chinese herbal medicine is discussed for CAM and other therapies. This review can provide some treatment recommendations for the reduction of UTs in patients with chronic kidney disease.

Caffeic Acid, One of the Major Phenolic Acids of the Medicinal Plant Antirhea borbonica, Reduces Renal Tubulointerstitial Fibrosis

The renal fibrotic process is characterized by a chronic inflammatory state and oxidative stress. Antirhea borbonica (A. borbonica) is a French medicinal plant found in Reunion Island and known for its antioxidant and anti-inflammatory activities mostly related to its high polyphenols content. We investigated whether oral administration of polyphenol-rich extract from A. borbonica could exert in vivo a curative anti-renal fibrosis effect. To this aim, three days after unilateral ureteral obstruction (UUO), mice were daily orally treated either with a non-toxic dose of polyphenol-rich extract from A. borbonica or with caffeic acid (CA) for 5 days. The polyphenol-rich extract from A. borbonica, as well as CA, the predominant phenolic acid of this medicinal plant, exerted a nephroprotective effect through the reduction in the three phases of the fibrotic process: (i) macrophage infiltration, (ii) myofibroblast appearance and (iii) extracellular matrix accumulation. These effects were associated with the mRNA down-regulation of Tgf-β, Tnf-α, Mcp1 and NfkB, as well as the upregulation of Nrf2. Importantly, we observed an increased antioxidant enzyme activity for GPX and Cu/ZnSOD. Last but not least, desorption electrospray ionization-high resolution/mass spectrometry (DESI-HR/MS) imaging allowed us to visualize, for the first time, CA in the kidney tissue. The present study demonstrates that polyphenol-rich extract from A. borbonica significantly improves, in a curative way, renal tubulointerstitial fibrosis progression in the UUO mouse model.

New insights into the role of the Nrf2 signaling pathway in green tea catechin applications

Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a transcriptional signaling pathway that plays a crucial role in numerous clinical complications. Pivotal roles of Nrf2 have been proved in cancer, autoimmune diseases, neurodegeneration, cardiovascular diseases, diabetes mellitus, renal injuries, respiratory conditions, gastrointestinal disturbances, and general disorders related to oxidative stress, inflammation, apoptosis, gelatinolysis, autophagy, and fibrogenesis processes. Green tea catechins as a rich source of phenolic compounds can deal with various clinical problems and manifestations. In this review, we attempted to focus on intervention between green tea catechins and Nrf2. Green tea catechins especially epigallocatechin gallate (EGCG) elucidated the protective role of Nrf2 and its downstream molecules in various disorders through Keap-1, HO-1, NQO-1, GPx, GCLc, GCLm, NF-kB cross-link, kinases, and apoptotic proteins. Subsequently, we compiled an updated expansions of the Nrf2 role as a gate to manage and protect different disorders and feasible indications of green tea catechins through this signaling pathway. The present review highlighted recent evidence-based data in silico, in vitro, and in vivo studies on an outline for future clinical trials.

Pharmacotherapy against Oxidative Stress in Chronic Kidney Disease: Promising Small Molecule Natural Products Targeting Nrf2-HO-1 Signaling

The global burden of chronic kidney disease (CKD) intertwined with cardiovascular disease has become a major health problem. Oxidative stress (OS) plays an important role in the pathophysiology of CKD. The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant responsive element (ARE) antioxidant system plays a critical role in kidney protection by regulating antioxidants during OS. Heme oxygenase-1 (HO-1), one of the targets of Nrf2-ARE, plays an important role in regulating OS and is protective in a variety of human and animal models of kidney disease. Thus, activation of Nrf2-HO-1 signaling may offer a potential approach to the design of novel therapeutic agents for kidney diseases. In this review, we have discussed the association between OS and the pathogenesis of CKD. We propose Nrf2-HO-1 signaling-mediated cell survival systems be explored as pharmacological targets for the treatment of CKD and have reviewed the literature on the beneficial effects of small molecule natural products that may provide protection against CKD.

Are Nutraceuticals Beneficial in Chronic Kidney Disease?

Chronic kidney disease (CKD) is a worldwide health problem in which prevalence is constantly rising. The pathophysiology of CKD is complicated and has not been fully resolved. However, elevated oxidative stress is considered to play a vital role in the development of this disease. CKD is also thought to be an inflammatory disorder in which uremic toxins participate in the development of the inflammatory milieu. A healthy, balanced diet supports the maintenance of a good health status as it helps to reduce the risk of the development of chronic diseases, including chronic kidney disease, diabetes mellitus, and hypertension. Numerous studies have demonstrated that functional molecules and nutrients, including fatty acids and fiber as well as nutraceuticals such as curcumin, steviol glycosides, and resveratrol not only exert beneficial effects on pro-inflammatory and anti-inflammatory pathways but also on gut mucosa. Nutraceuticals have attracted great interest recently due to their potential favorable physiological effects on the human body and their safety. This review presents some nutraceuticals in which consumption could exert a beneficial impact on the development and progression of renal disease as well cardiovascular disease.

Enhanced renoprotective effect of GDNF-modified adipose-derived mesenchymal stem cells on renal interstitial fibrosis

Background

The therapeutic effect of mesenchymal stem cells (MSCs) from human adipose tissue on renal interstitial fibrosis has been demonstrated by several groups. However, the way to enhance the renoprotective effect of adipose-derived mesenchymal stem cells (AMSCs) and the possible mechanisms are still unclear. The present study aimed to determine whether glial cell line-derived neurotrophic factor (GDNF)-modified AMSCs hold an enhanced protective effect on renal fibrosis.

Methods

AMSCs were isolated and purified for culture. The gene GDNF has been constructed to transfect into AMSCs. The ability of GFP-AMSCs and GDNF-AMSCs supernatants to promote tube formation of endothelial cells, repair damaged endothelial cell junctions, and improve endothelial cell function was compared by using tube formation assay, immunofluorescence techniques, and vascular ring assay, respectively. Furthermore, HE and Masson staining were used to observe the histological morphology of the kidney in vivo. Peritubular capillary changes were detected and analyzed by fluorescence microangiography (FMA). Meanwhile, the hypoxia, oxidative stress, fibrotic markers, and PI3K/Akt pathway proteins were measured by western blot or qRT-PCR technics.

Results

Compared with GFP-AMSCs only, GDNF-AMSCs could enhance the repair of injured endothelial cells and promote angiogenesis through secreting more growth factors in the supernatant of GDNF-AMSC culture media demonstrated in vitro studies. Studies in vivo, unilateral ureteral obstruction (UUO)-induced mice were injected with transfected AMSCs through their tail veins. We showed that enhanced homing of AMSCs was observed in the GDNF-AMSC group compared with the GFP-AMSC group. The animals treated with GDNF-AMSCs exhibited an improvement of capillary rarefaction and fibrosis induced by obstructed kidney compared with the GFP-AMSC group. Furthermore, we reported that GDNF-AMSCs protect renal tissues against microvascular injuries via activation of the PI3K/Akt signaling pathway. Therefore, GDNF-AMSCs further ameliorated the tissue hypoxia, suppressed oxidative stress, and finally inhibited endothelial to mesenchymal transition noting by decreased coexpression of endothelial cell (CD31) and myofibroblast (a-SMA) markers.

Conclusion

Collectively, our data indicated that the GDNF gene enhances the ability of AMSCs in improving renal microcirculation through PI3K/Akt/eNOS signaling pathway and afterward inhibit the EndMT process and kidney fibrogenesis, which should have a vast of implications in designing future remedies for chronic kidney disease (CKD) treatment.

Protective Role of Nrf2 in Renal Disease

Chronic kidney disease (CKD) is one of the fastest-growing causes of death and is predicted to become by 2040 the fifth global cause of death. CKD is characterized by increased oxidative stress and chronic inflammation. However, therapies to slow or prevent CKD progression remain an unmet need. Nrf2 (nuclear factor erythroid 2-related factor 2) is a transcription factor that plays a key role in protection against oxidative stress and regulation of the inflammatory response. Consequently, the use of compounds targeting Nrf2 has generated growing interest for nephrologists. Pre-clinical and clinical studies have demonstrated that Nrf2-inducing strategies prevent CKD progression and protect from acute kidney injury (AKI). In this article, we review current knowledge on the protective mechanisms mediated by Nrf2 against kidney injury, novel therapeutic strategies to induce Nrf2 activation, and the status of ongoing clinical trials targeting Nrf2 in renal diseases.

An Overview of Nrf2 Signaling Pathway and Its Role in Inflammation

Inflammation is a key driver in many pathological conditions such as allergy, cancer, Alzheimer’s disease, and many others, and the current state of available drugs prompted researchers to explore new therapeutic targets. In this context, accumulating evidence indicates that the transcription factor Nrf2 plays a pivotal role controlling the expression of antioxidant genes that ultimately exert anti-inflammatory functions. Nrf2 and its principal negative regulator, the E3 ligase adaptor Kelch-like ECH- associated protein 1 (Keap1), play a central role in the maintenance of intracellular redox homeostasis and regulation of inflammation. Interestingly, Nrf2 is proved to contribute to the regulation of the heme oxygenase-1 (HO-1) axis, which is a potent anti-inflammatory target. Recent studies showed a connection between the Nrf2/antioxidant response element (ARE) system and the expression of inflammatory mediators, NF-κB pathway and macrophage metabolism. This suggests a new strategy for designing chemical agents as modulators of Nrf2 dependent pathways to target the immune response. Therefore, the present review will examine the relationship between Nrf2 signaling and the inflammation as well as possible approaches for the therapeutic modulation of this pathway.

The Effects of Chronic Intermittent Hypoxia in Bleomycin-Induced Lung Injury on Pulmonary Fibrosis via Regulating the NF-κB/Nrf2 Signaling Pathway

Background

Obstructive sleep apnea (OSA) is associated with pulmonary fibrosis. Chronic intermittent hypoxia (CIH) is considered to be a surrogate of OSA. However, its exact role in pulmonary fibrosis remains uncertain. Therefore, we investigated the mechanism underlying CIH-induced pulmonary fibrosis and the role of the anti-fibrotic agent in bleomycin (BLE) induced lung injury.

Methods

Mice were divided into eight groups: the normoxia (NOR), CIH, NOR plus BLE, CIH plus BLE, NOR plus pirfenidone (PF), CIH plus PF, NOR plus BLE and PF, and CIH plus BLE and PF groups. BLE was administered intratracheally on day 14 following CIH or NOR exposure. Subsequently, the mice were exposed to CIH or NOR for an additional 4 weeks. PF was administered orally on day 5 after BLE instillation once daily for 3 weeks.

Results

In the BLE-treated groups, CIH-induced more collagen deposition in lung tissues than NOR, and significantly increased hydroxyproline and transforming growth factor-β expression. The CIH and BLE-treated groups showed increased lung inflammation compared to NOR or CIH groups. Following CIH with BLE treatment, nuclear factor-κB (NF-κB) protein expression was significantly increased, whereas nuclear factor-erythroid-related factor 2 (Nrf2) and heme oxygenase-1 protein levels were decreased. After PF treatment, NF-κB and Kelch-like ECH-associated protein 1 expression were suppressed, and Nrf2 expression was increased.

Conclusion

CIH accelerated lung fibrosis in BLE-induced lung injury in mice, potentially by regulating the NF-κB/Nrf2 signaling pathway. Our results implicate PF as a potential therapeutic agent for treating pulmonary fibrosis in individuals with OSA and idiopathic pulmonary fibrosis.

The role of Nrf2 in acute kidney injury: Novel molecular mechanisms and therapeutic approaches

Acute kidney injury (AKI) is a common clinical syndrome that is related to high morbidity and mortality. Oxidative stress, including the production of reactive oxygen species (ROS), appears to be the main element in the occurrence of AKI and the cause of the progression of chronic kidney disease (CKD) into end-stage renal disease (ESRD). Nuclear factor erythroid 2 related factor 2 (Nrf2) is a significant regulator of redox balance that has been shown to improve kidney disease by eliminating ROS. To date, researchers have found that the use of Nrf2-activated compounds can effectively reduce ROS, thereby preventing or retarding the progression of various types of AKI. In this review, we summarized the molecular mechanisms of Nrf2 and ROS in AKI and described the latest findings on the therapeutic potential of Nrf2 activators in various types of AKI.

Food as medicine: targeting the uraemic phenotype in chronic kidney disease

The observation that unhealthy diets (those that are low in whole grains, fruits and vegetables, and high in sugar, salt, saturated fat and ultra-processed foods) are a major risk factor for poor health outcomes has boosted interest in the concept of 'food as medicine'. This concept is especially relevant to metabolic diseases, such as chronic kidney disease (CKD), in which dietary approaches are already used to ameliorate metabolic and nutritional complications. Increased awareness that toxic uraemic metabolites originate not only from intermediary metabolism but also from gut microbial metabolism, which is directly influenced by diet, has fuelled interest in the potential of 'food as medicine' approaches in CKD beyond the current strategies of protein, sodium and phosphate restriction. Bioactive nutrients can alter the composition and metabolism of the microbiota, act as modulators of transcription factors involved in inflammation and oxidative stress, mitigate mitochondrial dysfunction, act as senolytics and impact the epigenome by altering one-carbon metabolism. As gut dysbiosis, inflammation, oxidative stress, mitochondrial dysfunction, premature ageing and epigenetic changes are common features of CKD, these findings suggest that tailored, healthy diets that include bioactive nutrients as part of the foodome could potentially be used to prevent and treat CKD and its complications.

Molecular mechanisms of action of epigallocatechin gallate in cancer: Recent trends and advancement

Epigallocatechin gallate (EGCG), also known as epigallocatechin-3-gallate, is an ester of epigallocatechin and gallic acid. EGCG, abundantly found in tea, is a polyphenolic flavonoid that has the potential to affect human health and disease. EGCG interacts with various recognized cellular targets and inhibits cancer cell proliferation by inducing apoptosis and cell cycle arrest. In addition, scientific evidence has illustrated the promising role of EGCG in inhibiting tumor cell metastasis and angiogenesis. It has also been found that EGCG may reverse drug resistance of cancer cells and could be a promising candidate for synergism studies. The prospective importance of EGCG in cancer treatment is owed to its natural origin, safety, and low cost which presents it as an attractive target for further development of novel cancer therapeutics. A major challenge with EGCG is its low bioavailability which is being targeted for improvement by encapsulating EGCG in nano-sized vehicles for further delivery. However, there are major limitations of the studies on EGCG, including study design, experimental bias, and inconsistent results and reproducibility among different study cohorts. Additionally, it is important to identify specific EGCG pharmacological targets in the tumor-specific signaling pathways for development of novel combined therapeutic treatments with EGCG. The present review highlights the ongoing development to identify cellular and molecular targets of EGCG in cancer. Furthermore, the role of nanotechnology-mediated EGCG combinations and delivery systems will also be discussed.

Phenolic Compounds from Nuts: Extraction, Chemical Profiles, and Bioactivity

Nuts contain a vast array of phenolic compounds having important biological properties. They include substances allocated into the five major groups named phenolic acids, flavonoids, tannins, phenolic lignans, and stilbene derivatives. The complexity in composition does not allow for setting a universal extraction procedure suitable for extraction of all nut phenolics. The use of non-conventional extraction techniques, such as those based on microwave, ultrasound, and compressed fluids, combined with generally recognized as safe solvents is gaining major interest. With regard to the latter, ethanol, water, and ethanol-water mixtures have proven to be effective as extracting solvents and allow for clean, safe, and low-cost extraction operations. In recent years, there has been an increasing interest in biological properties of natural phenolic compounds, especially on their role in the prevention of several diseases in which oxidative stress reactions are involved. This review provides an updated and comprehensive overview on nut phenolic extraction and their chemical profiles and bioactive properties.

Anti-fibrotic effects of synthetic TGF-β1 and Smad oligodeoxynucleotide on kidney fibrosis in vivo and in vitro through inhibition of both epithelial dedifferentiation and endothelial-mesenchymal transitions

Kidney fibrosis is a common process of various kidney diseases leading to end-stage renal failure irrespective of etiology. Myofibroblasts are crucial mediators in kidney fibrosis through production of extracellular matrix (ECM), but their origin has not been clearly identified. Many study proposed that epithelial and endothelial cells become myofibroblasts by epithelial dedifferentiation and endothelial-mesenchymal transition (EndoMT). TGF-β1/Smad signaling plays a crucial role in partly epithelial-mensencymal transition (EMT) and EndoMT. Thus, we designed the TGF-β1/Smad oligodeoxynucleotide (ODN), a synthetic short DNA containing complementary sequence for Smad transcription factor and TGF-β1 mRNA. Therefore, this study investigated the anti-fibrotic effect of synthetic TGF-β1/Smad ODN on UUO-induced kidney fibrosis in vivo model and TGF-β1-induced in vitro model. To examine the effect of TGF-β1/Smad ODN, we performed various experiments to evaluate kidney fibrosis. The results showed that UUO induced inflammation, ECM accumulation, epithelial dedifferentiation and EndoMT processes, and tubular atrophy. However, synthetic TGF-β1/Smad ODN significantly suppressed UUO-induced fibrosis. Furthermore, synthetic ODN attenuated TGF-β1-induced epithelial dedifferentiation and EndoMT program via blocking TGF-β1/Smad signaling. In conclusion, this study demonstrated that administration of synthetic TGF-β1/Smad ODN attenuates kidney fibrosis, epithelial dedifferentiation, and EndoMT processes. The findings propose the possibility of synthetic ODN as a new effective therapeutic tool for kidney fibrosis.

Molecular Mechanisms of Epigallocatechin-3-Gallate for Prevention of Chronic Kidney Disease and Renal Fibrosis: Preclinical Evidence

Chronic kidney disease (CKD) is a common public health problem worldwide characterized by gradual decline of renal function over months/years accompanied by renal fibrosis and failure in tissue wound healing after sustained injury. Patients with CKD frequently present with profound signs/symptoms that require medical treatment, mostly culminating in hemodialysis and renal transplantation. To prevent CKD more efficiently, there is an urgent need for better understanding of the pathogenic mechanisms and molecular pathways of the disease pathogenesis and progression, and for developing novel therapeutic targets. Recently, several lines of evidence have shown that epigallocatechin-3-gallate (EGCG), an abundant phytochemical polyphenol derived from Camellia sinensis, might be a promising bioactive compound for prevention of CKD development/progression. This review summarizes current knowledge of molecular mechanisms underlying renoprotective roles of EGCG in CKD based on available preclinical evidence (from both in vitro and in vivo animal studies), particularly its antioxidant property through preservation of mitochondrial function and activation of Nrf2 (nuclear factor erythroid 2-related factor 2)/HO-1 (heme oxygenase-1) signaling, anti-inflammatory activity, and protective effect against epithelial mesenchymal transition. Finally, future perspectives, challenges, and concerns regarding its clinical use in CKD and renal fibrosis are discussed.

Unilateral Ureteral Obstruction as a Model to Investigate Fibrosis-Attenuating Treatments

Renal fibrosis is the common pathway for most forms of progressive renal disease. The Unilateral Ureteral Obstruction (UUO) model is used to cause renal fibrosis, where the primary feature of UUO is tubular injury as a result of obstructed urine flow. Furthermore, experimental UUO in rodents is believed to mimic human chronic obstructive nephropathy in an accelerated manner. Renal fibrosis is the common pathway for most forms of progressive renal disease. Removing the obstruction may not be sufficient to reverse fibrosis, so an accompanying treatment may be of benefit. In this review, we have done a revision on treatments shown to ameliorate fibrosis in the context of the UUO experimental model. The treatments inhibit the production of fibrotic and inflammatory proteins such as Transforming Growth Factor β1 (TGF-β₁), Tumor Necrosis Factor α (TNF-α), collagen and fibronectin, Heat Shock Protein 47 (HSP47), suppress the proliferation of fibroblasts, prevent epithelial-to-mesenchymal transition, reduce oxidative stress, inhibit the action of the Nuclear Factor κB (NF-κB), reduce the phosphorylation of mothers against decapentaplegic homolog (SMAD) family members 2 and 3 (Smad2/3) or Mitogen-Activated Protein Kinases (MAPKs), inhibit the activation of the renin-angiotensin system. Summaries of the UUO experimental methods and alterations observed in the UUO experiments are included.

Inhibition of p300/CBP-Associated Factor Attenuates Renal Tubulointerstitial Fibrosis through Modulation of NF-kB and Nrf2

p300/CBP-associated factor (PCAF), a histone acetyltransferase, is involved in many cellular processes such as differentiation, proliferation, apoptosis, and reaction to cell damage by modulating the activities of several genes and proteins through the acetylation of either the histones or transcription factors. Here, we examined a pathogenic role of PCAF and its potential as a novel therapeutic target in the progression of renal tubulointerstitial fibrosis induced by non-diabetic unilateral ureteral obstruction (UUO) in male C57BL/6 mice. Administration of garcinol, a PCAF inhibitor, reversed a UUO-induced increase in the renal expression of total PCAF and histone 3 lysine 9 acetylation and reduced positive areas of trichrome and α-smooth muscle actin and collagen content. Treatment with garcinol also decreased mRNA levels of transforming growth factor-β, matrix metalloproteinase (MMP)-2, MMP-9, and fibronectin. Furthermore, garcinol suppressed nuclear factor-κB (NF-κB) and pro-inflammatory cytokines such as tumor necrosis factor-α and IL-6, whereas it preserved the nuclear expression of nuclear factor erythroid-derived 2-like factor 2 (Nrf2) and levels of Nrf2-dependent antioxidants including heme oxygense-1, catalase, superoxide dismutase 1, and NAD(P)H:quinone oxidoreductase 1. These results suggest that the inhibition of inordinately enhanced PCAF could mitigate renal fibrosis by redressing aberrant balance between inflammatory signaling and antioxidant response through the modulation of NF-κB and Nrf2.

Protective Effects of Epigallocatechin-3-Gallate from Green Tea in Various Kidney Diseases

Kidney diseases are common health problems worldwide. Various etiologies (e.g., diabetes, hypertension, drug-induced nephrotoxicity, infection, cancers) can affect renal function and ultimately lead to development of chronic kidney disease (CKD) and end-stage renal disease (ESRD). The global rise in number of CKD/ESRD patients during recent years has led to tremendous concern to look for effective strategies to prevent or slow progression of CKD and ESRD. Natural compounds derived from herbs or medicinal plants have gained wide attention for scientific scrutiny to achieve such goals. One of such natural compounds that has been extensively investigated is epigallocatechin-3-gallate (EGCG), a major polyphenol found in the tea plant (Camellia sinensis). A growing body of recent evidence has shown that EGCG may be a promising therapeutic or protective agent in various kidney diseases. This article thus highlights recent progress in medical research on beneficial effects of EGCG against a broad spectrum of kidney diseases, including acute kidney injury, cisplatin-induced nephrotoxicity, kidney stone disease, glomerulonephritis, lupus nephritis, renal cell carcinoma, diabetic nephropathy, CKD, and renal fibrosis. The renoprotective mechanisms are also detailed. Finally, future perspectives of medical research on EGCG and its potential use in clinical practice for treatment and prevention of kidney diseases are discussed.

Salvianolic acid A attenuates kidney injury and inflammation by inhibiting NF-κB and p38 MAPK signaling pathways in 5/6 nephrectomized rats

Salvianolic acid A (SAA) is a minor phenolic carboxylic acid extracted from Salviae miltiorrhizae Bunge (Danshen). SAA exhibits a variety of pharmacological activities, such as antioxidative, anti-thrombotic, neuroprotective, and anti-fibrotic effects, as well as protection from myocardial ischemia and prevention of diabetes and other diseases. Furthermore, SAA has shown renal-protective effects in doxorubicin-induced nephropathy. However, there has been limited research regarding the effects of SAA and underlying mechanisms in chronic kidney disease (CKD). Here, we examined the effects and molecular mechanisms of SAA in an established animal model of 5/6 nephrectomized (5/6Nx) rats. The rats were injected with SAA (2.5, 5, and 10 mg/kg per day, intraperitoneally (ip)) for 28 days. SAA dose-dependently lowered the levels of urine protein, blood urea nitrogen, serum creatinine, plasma total cholesterol, and plasma triglycerides in 5/6Nx rats. Histological examination revealed that SAA dose-dependently attenuated renal pathological lesions, evidenced by reduced renal tubulointerstitial fibrosis by decreasing the expression levels of tumor growth factor-β1 and α-smooth muscle actin in 5/6Nx rats. Moreover, SAA dose-dependently inhibited the activation of nuclear factor-κB (NF-κB) and p38 mitogen-activated protein kinase (MAPK) signaling pathways, subsequently attenuating the secretion of tumor necrosis factor-α and interleukin-1β and inhibiting the expression of monocyte chemotactic protein-1, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 in kidneys of 5/6Nx rats. The above results were consistent with those obtained in lipopolysaccharide-induced HK-2 cells in vitro (a recognized in vitro inflammatory model). In conclusion, our results demonstrated that SAA effectively attenuates kidney injury in 5/6Nx rats. The therapeutic effects of SAA on kidney injury can be attributed to its anti-inflammatory activities through inhibition of the activation of the NF-κB and p38 MAPK signaling pathways.

Transplantation of Amniotic Fluid-Derived Stem Cells Preconditioned with Glial Cell Line-Derived Neurotrophic Factor Gene Alleviates Renal Fibrosis

Amniotic fluid-derived stem cells (AFSCs), which exhibit both embryonic and mesenchymal stem cell characteristics, have been shown to mitigate the degree of renal interstitial fibrosis. The aim of the present study was to determine whether transplantation of glial cell line-derived neurotrophic factor (GDNF)–modified AFSCs is more useful than transplantation of unmodified AFSCs for the treatment of renal interstitial fibrosis. Mice were randomly assigned to a sham-operation group (sham), a unilateral ureteral obstruction (UUO)-saline solution group (UUO), an AFSC transplantation group (AFSC) and a GDNF-modified AFSC transplantation group (GDNF-AFSC) and sacrificed at days 3 and 7 post-surgery (six in each group). We showed that GDNF-AFSCs noticeably suppressed oxidative stress and inflammation; additionally, GDNF-AFSCs positively regulated peritubular capillaries (PTCs), vascular endothelial growth factor (VEGF), hypoxia inducible factor-1α (HIF-1α), and transforming growth factor-β1 (TGF-β1) protein levels. Transmission electron microscopy (TEM) revealed that mitochondrial injury induced by the UUO model was significantly ameliorated after the mice were treated with GDNF-AFSCs. Therefore, we determined that GDNF gene promotes the abilities of AFSCs to inhibit inflammatory and oxidative stress effects, repair renal microvessels, relieve tissue hypoxia and mitochondrial damage, and, ultimately, alleviate renal interstitial fibrosis.

Cryptotanshinone Attenuates Oxidative Stress and Inflammation through the Regulation of Nrf-2 and NF-κB in Mice with Unilateral Ureteral Obstruction

Oxidative stress and inflammatory responses are closely implicated in the progression of renal interstitial fibrosis, thereby leading to chronic kidney disease. Cryptotanshinone (CTS) is a natural compound involved in antioxidant and anti-inflammatory activities. We evaluated the effects of CTS on inflammation and oxidative stress in obstructed kidneys. Mice received gastric gavage of CTS from 7 days before unilateral ureteral obstruction operation to 1 week after surgery. Administration of CTS at 50 and 100 mg/kg/day significantly decreased collagen production, as shown by Masson staining. Immunohistochemistry staining and RT-PCR confirmed that CTS reduced extracellular matrix proteins, such as fibronectin and collagen-1, in the obstructed kidneys in a dose-dependent manner. Furthermore, immunohistochemistry staining indicated that CTS inhibited infiltration of the macrophage (CD68-positive) and lymphocyte (CD3-positive) cells, which were associated with the suppression of the nuclear factor-κB signalling activation. CTS increased superoxide dismutase, catalase and glutathione while decreased malondialdehyde production. More importantly, CTS activated Nrf-2 and HO-1 in the obstructed kidneys for 7 days. CTS could protect renal interstitial fibrosis by ameliorating inflammation and oxidative stress, which might be through the regulation of NF-κB and Nrf-2/HO-1 signalling pathways.

Nutrients, Nutraceuticals, and Xenobiotics Affecting Renal Health

Chronic kidney disease (CKD) affects 8–16% of the population worldwide. In developed countries, the most important risk factors for CKD are diabetes, hypertension, and obesity, calling into question the importance of educating and acting on lifestyles and nutrition. A balanced diet and supplementation can indeed support the maintenance of a general health status, including preservation of renal function, and can help to manage and curb the main risk factors for renal damage. While the concept of protein and salt restriction in nephrology is historically acknowledged, the role of some nutrients in renal health and the importance of nutrition as a preventative measure for renal care are less known. In this narrative review, we provide an overview of the demonstrated and potential actions of some selected nutrients, nutraceuticals, and xenobiotics on renal health and function. The direct and indirect effects of fiber, protein, fatty acids, curcumin, steviol glycosides, green tea, coffee, nitrates, nitrites, and alcohol on kidney health are reviewed here. In view of functional and personalized nutrition, understanding the renal and systemic effects of dietary components is essential since many chronic conditions, including CKD, are related to systemic dysfunctions such as chronic low-grade inflammation.

MnTBAP therapy attenuates the downregulation of sodium transporters in obstructive kidney disease

Ureteral obstruction is associated with reduced expressions of renal sodium transporters, which contributes to impaired urinary concentrating capacity. In this study, we employed a synthetic mitochondrial superoxide dismutase 2 (SOD2) mimic MnTBAP to investigate the role of mitochondrial oxidative stress in modulating the sodium transporters in obstructive kidney disease. Following unilateral ureteral obstruction (UUO) for 7 days, a global reduction of sodium transporters including NHE3, NCC, NKCC2, and ENaCα was observed as determined by qRT-PCR, Western Blotting or immunohistochemistry. Among these sodium transporters, the downregulation of NHE3, NCC, and NKCC2 was partially reversed by MnTBAP treatment. In contrast, the reduction of ENaCα was not affected by MnTBAP. The β and γ subunits of ENaC were not significantly altered by ureteral obstruction or MnTBAP therapy. To further confirm the anti-oxidant effect of MnTBAP, we examined the levels of TBARs in the urine collected from the obstructed ureters of UUO mice and bladder of sham mice. As expected, the increment of urinary TBARs in UUO mice was entirely abolished by MnTBAP therapy, indicating an amelioration of oxidative stress. Meantime, we found that three types of SOD were all reduced in obstructed kidneys determined by qRT-PCR, which was unaffected by MnTBAP. Collectively, these results demonstrated an important role of mitochondrial oxidative stress in mediating the downregulation of sodium transporters in obstructive kidney disease.

Transcription factors Nrf2 and NF-κB contribute to inflammation and apoptosis induced by intestinal ischemia-reperfusion in mice

Intestinal ischemia/reperfusion (IIR) is a common pathological event associated with intestinal injury and apoptosis with high mortality. Nuclear factor (NF)-E2-related factor-2 (Nrf2) is a key transcription factor that interacts with NF-κB and has a vital anti-inflammatory effect. However, whether Nrf2 has a role in IIR-induced apoptosis and the possible underlining mechanisms, such as modulation of the inflammation regulation pathway, have remained to be fully elucidated. In the present study, IIR was identified to cause significant intestinal injury and apoptosis, with high expression levels of inflammatory cytokines, as well as the apoptotic proteins B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax) and caspase-3, while simultaneously decreasing the protein levels of Bcl-2. The effect was more pronounced after pretreatment of the animals with all-trans retinoic acid or brusatol, potent inhibitors of Nrf2. t-Butylhydroquinone, an Nrf2 activator, significantly attenuated IIR-induced intestinal injury and apoptosis, with inhibition of the overexpression of the inflammatory cytokines, Bax and caspase-3 protein and partial restoration of Bcl-2 protein expression. Taken together, these results indicated that increased Nrf2 expression reduced IIR-induced intestinal apoptosis and that the protective function of Nrf2 may be based on its anti-inflammatory effects through the inhibition of the NF-κB pathway.

Hesperetin alleviates renal interstitial fibrosis by inhibiting tubular epithelial-mesenchymal transition in vivo and in vitro

Hesperetin (HES) is a flavonoid that has been reported to exert protective effects against cardiac remodeling, lung fibrosis and hepatic fibrosis. However, reports on the effects and potential mechanisms of HES in renal fibrosis are limited. In the present study, a unilateral ureteric obstruction (UUO) mouse model and a transforming growth factor (TGF)-β1-activated normal rat kidney (NRK)-52E cell model were established. HES was subsequently administered to these models to evaluate its anti-fibrotic effects and potential underlying mechanisms of action. The results demonstrated that HES reduced obstruction-induced renal injury and deposition of the extracellular matrix components collagen-I and fibronectin in UUO mouse kidneys (P<0.05). Furthermore, HES treatment significantly suppressed EMT, as evidenced by decreased expression of α-smooth muscle actin and E-cadherin, (P<0.05). Additionally, HES inhibited the hedgehog signaling pathway in UUO mice and TGF-β1-treated NRK-52E cells. The present findings indicate that HES treatment may inhibit EMT and renal fibrosis in vivo and in vitro by antagonizing the hedgehog signaling pathway.

Tea Drinking and Its Association with Active Tuberculosis Incidence among Middle-Aged and Elderly Adults: The Singapore Chinese Health Study

Experimental studies showed that tea polyphenols may inhibit growth of Mycobacterium tuberculosis. However, no prospective epidemiologic study has investigated tea drinking and the risk of active tuberculosis. We investigated this association in the Singapore Chinese Health Study, a prospective population-based cohort of 63,257 Chinese aged 45–74 years recruited between 1993 and 1998 in Singapore. Information on habitual drinking of tea (including black and green tea) and coffee was collected via structured questionnaires. Incident cases of active tuberculosis were identified via linkage with the nationwide tuberculosis registry up to 31 December 2014. Cox proportional hazard models were used to estimate the relation of tea and coffee consumption with tuberculosis risk. Over a mean 16.8 years of follow-up, we identified 1249 incident cases of active tuberculosis. Drinking either black or green tea was associated with a dose-dependent reduction in tuberculosis risk. Compared to non-drinkers, the hazard ratio (HR) (95% confidence interval (CI)) was 1.01 (0.85–1.21) in monthly tea drinkers, 0.84 (0.73–0.98) in weekly drinkers, and 0.82 (0.71–0.96) in daily drinkers (p for trend = 0.003). Coffee or caffeine intake was not significantly associated with tuberculosis risk. In conclusion, regular tea drinking was associated with a reduced risk of active tuberculosis.

Natural antioxidants in the treatment and prevention of diabetic nephropathy; a potential approach that warrants clinical trials

Diabetic nephropathy is the major cause of end-stage renal disease and effective and new therapeutic approaches are needed in diabetic nephropathy and chronic kidney diseases. Oxidative stress and inflammatory process are important factors contributing to kidney damage by increasing production of oxidants. KEAP1/Nrf2/ARE pathway regulates the transcription of many antioxidant genes and modulation of the pathway up regulates antioxidants. NFB controls the expression of genes involved in the inflammatory response. Natural substances have antioxidant and anti-inflammatory activities and have an impact on NFB and KEAP1/Nrf2/ARE pathways. The preclinical studies explored the effectiveness of whole herbs, plants or seeds and their active ingredients in established diabetic nephropathy. They ameliorate oxidative stress induced kidney damage, enhance antioxidant system, and decrease inflammatory process and fibrosis; most likely by activating KEAP1/Nrf2/ARE pathway and by deactivating NFB pathway. Whole natural products contain balanced antioxidants that might work synergistically to induce beneficial therapeutic outcome. In this context, more clinical studies involving whole plants or herbal products or mixtures of different herbs and plants and their active ingredients might change our strategies for the management of diabetic nephropathy. The natural products might be useful as preventive interventions and studies are required in this field.