A novel compound AB38b attenuates oxidative stress and ECM protein accumulation in kidneys of diabetic mice through modulation of Keap1/Nrf2 signaling

Caffeic acid activates Nrf2 enzymes, providing protection against oxidative damage induced by ionizing radiation

Caffeic acid (CA) is a prevalent polyphenolic compound commonly found in various plant-derived foods. Due to its diverse pharmacological properties, including antioxidant activity, cardiovascular protection, and immune regulation, CA has garnered significant attention. Ionizing radiation (IR) is extensively utilized across industrial sectors, agriculture, defense applications, scientific research, and clinical medicine; however, the detrimental effects of radiation on human health cannot be ignored. IR can directly damage the DNA, proteins, and lipids within macromolecules or ionize water molecules to generate substantial quantities of free radicals that indirectly harm cells, especially those in the brain which are highly susceptible to radiation exposure. Consequently, effective strategies for preventing and treating IR-induced neurological damage represent an urgent medical challenge that necessitates resolution. Our study aims to investigate the protective effects of CA against IR-induced neuronal cell damage along with elucidating its potential mechanisms of action. The results indicate that CA can covalently modify active cysteine residues on Keap1 protein altering its conformation; this modification disrupts the interaction between Keap1 and Nrf2 while facilitating Nrf2's translocation into the nucleus where it activates downstream expression of cellular protective factors such as heme oxygenase-1 (HO-1), NAD(P)H: quinone oxidoreductase 1 (NQO1), Thioredoxin Reductase-1 (TrxR1) and other cellular protective factors to play a role in countering radiation-induced neurological damage. In conclusion, CA emerges as an effective radioprotective agent capable of exerting antiradiation effects. Our findings provide valuable insights for developing novel therapeutic agents aimed at preventing and treating IR-induced neurological impairment.

YY1/HIF-1α/mROS positive-feedback loop exacerbates glomerular mesangial cell proliferation in mouse early diabetic kidney disease

Mesangial cells (MCs) are the most active intrinsic cells in the glomerulus. MCs excessively proliferate at the early stage of diabetic kidney disease (DKD), eventually causing glomerular sclerosis and even renal failure; inhibiting glomerular MC proliferation in early DKD is a promising prevention and treatment strategy for early DKD. Our previous study shows that Yin Yang 1 (YY1), a zinc finger protein, is a novel regulator of DKD-induced renal fibrosis. In this study we investigated the role of YY1 in glomerular MC proliferation in DKD in vivo and in vitro. We first showed that YY1 expression levels were significantly increased in the glomerular MCs of DKD patients and db/db mice and in high glucose (HG)-treated SV40-MES13 cells. By using YY1 expression/knockdown plasmids, we confirmed that YY1 contributed to glomerular MC proliferation in vitro. We demonstrated that YY1 upregulated hypoxia-inducible factor-1 alpha (HIF-1α) expression and activity in HG-treated SV40-MES13 cells, leading to overproduction of mROS. Moreover, mROS contributed to positive feedback regulation of YY1/HIF-1α signaling, and the YY1/HIF-1α/mROS positive feedback loop exacerbated glomerular MC proliferation in HG-treated SV40-MES13 cells. In addition, renal-specific YY1 overexpression promoted glomerular MC proliferation in normal mice, whereas renal-specific YY1 knockdown mitigated MC proliferation in early diabetic mice by inactivating HIF-1α/ROS signaling. In conclusion, the YY1/HIF-1α/mROS positive feedback loop might be an attractive therapeutic target for overcoming glomerulosclerosis in early DKD.

Renal Implications of Dysregulated Protein Homeostasis: Insights into Ubiquitin-Proteasome and Autophagy Systems

The ubiquitin-proteasome system (UPS) and autophagy maintain protein homeostasis, which is critical to cellular function and survival. The dysregulation of these pathways has been recognized as a hallmark of acute kidney injury and chronic kidney disease. This review elucidates the role of the UPS and autophagy in kidney disease, namely through inflammation, oxidative stress, fibrosis and apoptosis. The pathways of NF-κB, TGF-β and mitochondrial failure result in glomerular injury and tubulointerstitial fibrosis due to impaired proteostasis in podocytes and tubular epithelial cells. Recent studies have revealed a connection between the autophagic process and the UPS, wherein compensatory mechanisms aim to spike down proteotoxic stress but eventually seem inadequate in cases of chronic derangement. Low-dose pharmacological inhibitors, autophagy modulators, and new gene and nanotechnology-based treatments may all help to restore the protein balance and reduce kidney injury. A more thorough understanding of these pathways is needed to develop kidney-protective and disease-modifying therapeutic interventions.

Oxidative stress and dysregulated long noncoding RNAs in the pathogenesis of Parkinson's disease

Parkinson's disease (PD) is a progressive age-related neurodegenerative disease whose annual incidence is increasing as populations continue to age. Although its pathogenesis has not been fully elucidated, oxidative stress has been shown to play an important role in promoting the occurrence and development of the disease. Long noncoding RNAs (lncRNAs), which are more than 200 nucleotides in length, are also involved in the pathogenesis of PD at the transcriptional level via epigenetic regulation, or at the post-transcriptional level by participating in physiological processes, including aggregation of the α-synuclein, mitochondrial dysfunction, oxidative stress, calcium stabilization, and neuroinflammation. LncRNAs and oxidative stress are correlated during neurodegenerative processes: oxidative stress affects the expression of multiple lncRNAs, while lncRNAs regulate many genes involved in oxidative stress responses. Oxidative stress and lncRNAs also affect other processes associated with neurodegeneration, including mitochondrial dysfunction and increased neuroinflammation that lead to neuronal death. Therefore, modulating the levels of specific lncRNAs may alleviate pathological oxidative damage and have neuroprotective effects. This review discusses the general mechanisms of oxidative stress, pathological mechanism underlying the role of oxidative stress in the pathogenesis of PD, and teases out the mechanisms through which lncRNAs regulate oxidative stress during PD pathogenesis, as well as identifies the possible neuroprotective mechanisms of lncRNAs. Reviewing published studies will help us further understand the mechanisms underlying the role of lncRNAs in the oxidative stress process in PD and to identify potential therapeutic strategies for PD.

Disturbed Follicular Microenvironment in Polycystic Ovary Syndrome: Relationship to Oocyte Quality and Infertility

Polycystic ovary syndrome (PCOS) is a common endocrine disorder associated with infertility and poor reproductive outcomes. The follicular fluid (FF) microenvironment plays a crucial role in oocyte development. This review summarizes evidence elucidating the alterations in FF composition in PCOS. Various studies demonstrated a pronounced proinflammatory milieu in PCOS FF, characterized by increased levels of cytokines, including but not limited to interleukin-6 (IL-6), tumor necrosis factor α, C-reactive protein, and IL-1β, concomitant with a reduction in anti-inflammatory IL-10. T lymphocytes and antigen-presenting cells are dysregulated in PCOS FF. PCOS FF exhibit heightened reactive oxygen species production and the accumulation of lipid peroxidation byproducts, and impaired antioxidant defenses. Multiple microRNAs are dysregulated in PCOS FF, disrupting signaling critical to granulosa cell function. Proteomic analysis reveals changes in pathways related to immune responses, metabolic perturbations, angiogenesis, and hormone regulation. Metabolomics identify disturbances in glucose metabolism, amino acids, lipid profiles, and steroid levels with PCOS FF. Collectively, these pathological alterations may adversely affect oocyte quality, embryo development, and fertility outcomes. Further research on larger cohorts is needed to validate these findings and to forge the development of prognostic biomarkers of oocyte developmental competence within FF. Characterizing the follicular environment in PCOS is key to elucidating the mechanisms underlying subfertility in this challenging disorder.

Regeneration and anti-inflammatory effects of stem cells and their extracellular vesicles in gynecological diseases

There are many gynecological diseases, among which breast cancer (BC), cervical cancer (CC), endometriosis (EMs), and polycystic ovary syndrome (PCOS) are common and difficult to cure. Stem cells (SCs) are a focus of regenerative medicine. They are commonly used to treat organ damage and difficult diseases because of their potential for self-renewal and multidirectional differentiation. SCs are also commonly used for difficult-to-treat gynecological diseases because of their strong directional differentiation ability with unlimited possibilities, their tendency to adhere to the diseased tissue site, and their use as carriers for drug delivery. SCs can produce exosomes in a paracrine manner. Exosomes can be produced in large quantities and have the advantage of easy storage. Their safety and efficacy are superior to those of SCs, which have considerable potential in gynecological treatment, such as inhibiting endometrial senescence, promoting vascular reconstruction, and improving anti-inflammatory and immune functions. In this paper, we review the mechanisms of the regenerative and anti-inflammatory capacity of SCs and exosomes in incurable gynecological diseases and the current progress in their application in genetic engineering to provide a foundation for further research.

Nrf2 protects against myocardial ischemia-reperfusion injury in diabetic rats by inhibiting Drp1-mediated mitochondrial fission

Mitochondrial dysfunction and oxidative stress are considered to be two main drivers of diabetic myocardial ischemia-reperfusion injury (DM + MIRI). Nuclear factor-erythroid 2-related factor 2 (Nrf2) and Dynamin-related protein 1 (Drp1) play central roles in maintaining mitochondrial homeostasis and regulating oxidative stress, but the effects of the Nrf2-Drp1 pathway on DM-MIRI have not been reported. The aim of this study is to investigate the role of the Nrf2-Drp1 pathway in DM + MIRI rats. A rat model of DM + MIRI and H9c2 cardiomyocyte injury were constructed. The therapeutic effect of Nrf2 was assessed by detecting myocardial infarct size, mitochondrial structure, levels of myocardial injury markers and oxidative stress, apoptosis, and Drp1 expression. The results showed that DM + MIRI rats had increased myocardial infarct size and Drp1 expression in myocardial tissue, accompanied by increased mitochondrial fission and oxidative stress. Interestingly, Nrf2 agonist dimethyl fumarate (DMF) could significantly improve cardiac function, mitochondrial fission, and decrease oxidative stress levels and Drp1 expression after ischemia. However, these effects of DMF would be largely counteracted by the Nrf2 inhibitor ML385. Additionally, Nrf2 overexpression significantly suppressed Drp1 expression, apoptosis, and oxidative stress levels in H9c2 cells. Nrf2 attenuates myocardial ischemia-reperfusion injury in DM rats by reducing Drp1-mediated mitochondrial fission and oxidative stress.

Naringin abrogates angiotensin-converting enzyme (ACE) activity and podocin signalling pathway in cobalt chloride-induced nephrotoxicity and hypertension

PurposeThe persistent and alarming rates of increase in cardiovascular and renal diseases caused by chemicals such as cobalt chloride (CoCl₂) in mammalian tissues have led to the use of various drugs for the treatment of these diseases. This study aims at evaluating the nephron-protective action of Naringin (NAR), a metal-chelating antioxidant against CoCl₂-induced hypertension and nephrotoxicity.MethodsForty-two male Wistar rats were randomly distributed to seven rats of six groups and classified into Group A (Control), Group B (300 part per million; ppm CoCl₂), Group C (300 ppm CoCl₂ + 80 mg/kg NAR), Group D (300 ppm CoCl₂ + 160 mg/kg NAR), Group E (80 mg/kg NAR), and Group F (160 mg/kg NAR). NAR and CoCl₂ were administered via oral gavage for seven days. Biomarkers of renal damage, oxidative stress, antioxidant status, blood pressure parameters, immunohistochemistry of renal angiotensin-converting enzyme and podocin were determined.ResultsCobalt chloride intoxication precipitated hypertension, renal damage, and oxidative stress. Immunohistochemistry revealed higher expression of angiotensin-converting enzyme (ACE) and podocin in rats administered only CoCl₂.ConclusionTaken together, the antioxidant and metal-chelating action of Naringin administration against cobalt chloride-induced renal damage and hypertension could be through abrogation of angiotensin-converting enzyme and podocin signalling pathway.

Electroacupuncture Alleviates Diabetic Neuropathic Pain and Downregulates p-PKC and TRPV1 in Dorsal Root Ganglions and Spinal Cord Dorsal Horn

Diabetic neuropathic pain (DNP) is a common complication of diabetes. Streptozotocin (STZ)-induced changes of protein in dorsal root ganglion (DRG) and spinal cord dorsal horn (SCDH) are critical for DNP genesis. However, which proteins change remains elusive. Here, the DNP model was established by a single intraperitoneal injection of STZ, accompanied by increased fasting blood glucose (FBG), decreased body weight (BW), and decreased paw withdrawal latency (PWL). Proteins change in L4-L6 DRGs and SCDH of rats were detected. Western blot and immunofluorescence results showed that expression levels of phosphorylated protein kinase C (p-PKC), transient receptor potential vanilloid-1 (TRPV1), Substance P (SP) and calcitonin gene-related peptide (CGRP) in the DRG and the SCDH of rats were increased after STZ injection. A preliminary study from our previous study showed that 2 Hz electroacupuncture (EA) effectively alleviates DNP. However, the analgesic mechanism of EA needs further elucidation. Here, EA at the bilateral Zusanli (ST36) and KunLun (BL60) acupoints was applied for one week, and to investigate the effect on DNP. EA reversed thermal hyperalgesia in DNP rats and downregulated the expression of p-PKC, TRPV1, SP, and CGRP in DRG and SCDH.

Fyn deficiency inhibits oxidative stress by decreasing c-Cbl-mediated ubiquitination of Sirt1 to attenuate diabetic renal fibrosis

OBJECTIVE

Oxidative stress (OS) is the main cause leading to diabetic renal fibrosis. Recently, Fyn was paid much attention on OS and emerged as a pivotal player in acute kidney injury, while whether Fyn regulates oxidative stress in chronic diabetes nephropathy (DN) has not been clarified yet. The purpose of this study was to identify the role of Fyn in DN and elucidated its regulatory mechanism.

METHODS

The db/db mice and littermate control C57BKS/J mice were injected by tail vein with Fyn interfering adenovirus or Fyn overexpressing adenovirus to investigate the role of Fyn in vivo. Primary glomerular mesangial cells (GMCs) were used for in vitro studies.

RESULTS

Fyn was up-regulated in high glucose (HG)-induced GMCs and kidneys of diabetic mice. Additionally, Fyn knockdown reduced the level of OS in HG-induced GMCs and kidneys of diabetic mice, thereby ameliorating diabetic renal fibrosis. While overexpression of Fyn significantly increased the level of OS in GMCs and kidney tissues, resulting in renal damage. Moreover, Fyn deficiency exerted antioxidant effects by activating the Sirt1/Foxo3a pathway. Mechanistically, Fyn facilitated the combination of c-Cbl and Sirt1 by phosphorylating c-Cbl at Tyr⁷³¹, which triggered K48-linked polyubiquitination of Sirt1 at Lys³⁷⁷ and Lys⁵¹³ by c-Cbl and promoted Sirt1 degradation, impairing the antioxidant effects of Foxo3a.

CONCLUSIONS

Fyn deficiency promoted Foxo3a nuclear transcription via reducing the ubiquitination of Sirt1 by c-Cbl, thereby alleviating renal oxidative damage in diabetic mice. These results identified Fyn as a potential therapeutic target against DN.

The impact of oxidative stress-induced mitochondrial dysfunction on diabetic microvascular complications

Diabetes mellitus (DM) is a metabolic disease characterized by chronic hyperglycaemia, with absolute insulin deficiency or insulin resistance as the main cause, and causes damage to various target organs including the heart, kidney and neurovascular. In terms of the pathological and physiological mechanisms of DM, oxidative stress is one of the main mechanisms leading to DM and is an important link between DM and its complications. Oxidative stress is a pathological phenomenon resulting from an imbalance between the production of free radicals and the scavenging of antioxidant systems. The main site of reactive oxygen species (ROS) production is the mitochondria, which are also the main organelles damaged. In a chronic high glucose environment, impaired electron transport chain within the mitochondria leads to the production of ROS, prompts increased proton leakage and altered mitochondrial membrane potential (MMP), which in turn releases cytochrome c (cyt-c), leading to apoptosis. This subsequently leads to a vicious cycle of impaired clearance by the body's antioxidant system, impaired transcription and protein synthesis of mitochondrial DNA (mtDNA), which is responsible for encoding mitochondrial proteins, and impaired DNA repair systems, contributing to mitochondrial dysfunction. This paper reviews the dysfunction of mitochondria in the environment of high glucose induced oxidative stress in the DM model, and looks forward to providing a new treatment plan for oxidative stress based on mitochondrial dysfunction.

Inhibition of S100A8/A9 ameliorates renal interstitial fibrosis in diabetic nephropathy

BACKGROUND

Renal interstitial fibrosis (RIF) is one of the main features of diabetic nephropathy (DN), but the molecular mechanisms mediating RIF in DN has yet been fully understood. S100A8 and S100A9 are the proteins associated with immune and inflammation response. Here we reported the expression of S100A8 and S100A9 were significantly increased on tubular epithelial cells in diabetic kidneys through a proteomic analysis.

METHODS

We detected the expression of S100A8/A9 in diabetic kidneys by using immunoblotting, real-time PCR and immunostaining. RNA silencing and overexpression were performed by using S100A8/A9 expression/knockdown lentivirus to investigate the connection between S100A8/A9 and epithelial to mesenchymal transition (EMT) process. We also identify the expression of TLR4/NFκB pathway-related molecules in the case mentioned above. Afterwards a CO-IP assay was used to verify that compound AB38b ameliorates the EMT by interfering S100A8/A9 expression.

RESULTS

The expression of S100A8 and S100A9 were significantly increased on tubular epithelial cells in diabetic kidneys. S100A8/A9 knocking-down alleviate and over-expression promote the renal interstitial fibrosis of diabetic mice. Mechanically, high levels of S100A8/A9 expression in tubular epithelial cells during diabetic condition activated the TLR4/NF-κB signal pathway which promoted the EMT process and finally led to RIF progression. S100A8/A9 knockdown ameliorated RIF of diabetic mice. Further experiments revealed that compound AB38b inhibited the EMT progression of tubular epithelial cells induced by S100A8/A9 through interfering the expressions of S100A8/A9.

CONCLUSIONS

Our study suggest that abnormal expression of S100A8/A9 in the disease condition promotes EMT process and RIF through TLR4/NF-κB signal pathway. Using small molecular inhibitor AB38b to inhibit the abnormal expressions of S100A8/A9 might be a novel therapeutic strategy in treating DN.

NRF2 and Diabetes: The Good, the Bad, and the Complex

Despite decades of scientific effort, diabetes continues to represent an incredibly complex and difficult disease to treat. This is due in large part to the multifactorial nature of disease onset and progression and the multiple organ systems affected. An increasing body of scientific evidence indicates that a key mediator of diabetes progression is NRF2, a critical transcription factor that regulates redox, protein, and metabolic homeostasis. Importantly, while experimental studies have confirmed the critical nature of proper NRF2 function in preventing the onset of diabetic outcomes, we have only just begun to scratch the surface of understanding the mechanisms by which NRF2 modulates diabetes progression, particularly across different causative contexts. One reason for this is the contradictory nature of the current literature, which can often be accredited to model discrepancies, as well as whether NRF2 is activated in an acute or chronic manner. Furthermore, despite therapeutic promise, there are no current NRF2 activators in clinical trials for the treatment of patients with diabetes. In this review, we briefly introduce the transcriptional programs regulated by NRF2 as well as how NRF2 itself is regulated. We also review the current literature regarding NRF2 modulation of diabetic phenotypes across the different diabetes subtypes, including a brief discussion of contradictory results, as well as what is needed to progress the NRF2 diabetes field forward.

Diabetic Nephropathy: Pathogenesis to Cure

Diabetic nephropathy (DN) is a leading cause of end-stage renal disorder (ESRD). It is defined as the increase in urinary albumin excretion (UAE) when no other renal disease is present. DN is categorized into microalbuminuria and macroalbuminuria. Factors like high blood pressure, high blood sugar levels, genetics, oxidative stress, hemodynamic and metabolic changes affect DN. Hyperglycemia causes renal damage through activating protein kinase C (PKC), producing advanced end glycation products (AGEs) and reactive oxygen species (ROS). Growth factors, chemokines, cell adhesion molecules, inflammatory cytokines are found to be elevated in the renal tissues of the diabetic patient. Many different and new diagnostic methods and treatment options are available due to the increase in research efforts and progression in medical science. However, until now, no permanent cure is available. This article aims to explore the mechanism, diagnosis, and therapeutic strategies in current use for increasing the understanding of DN.

Diphenyl Diselenide Alleviates Tert-Butyl Hydrogen Peroxide-Induced Oxidative Stress and Lipopolysaccharide-Induced Inflammation in Rat Glomerular Mesangial Cells

Hyperglycemia, oxidative stress, and inflammation play key roles in the onset and development of diabetic complications such as diabetic nephropathy (DN). Diphenyl diselenide (DPDS) is a stable and simple organic selenium compound with anti-hyperglycemic, anti-inflammatory, and anti-oxidative activities. Nevertheless, in vitro, the role and molecular mechanism of DPDS on DN remains unknown. Therefore, we investigated the effects of DPDS on tert-butyl hydrogen peroxide (t-BHP)-induced oxidative stress and lipopolysaccharide (LPS)-induced inflammation in rat glomerular mesangial (HBZY-1) cells and explored the underlying mechanisms. DPDS attenuated t-BHP-induced cytotoxicity, concurrent with decreased intracellular ROS and MDA contents and increased SOD activity and GSH content. Moreover, DPDS augmented the protein and mRNA expression of Nrf2, HO-1, NQO1, and GCLC in t-BHP-stimulated HBZY-1 cells. In addition, DPDS suppressed LPS-induced elevations of intracellular content and mRNA expression of interleukin (IL)-6, IL-1β and TNF-α. Furthermore, LPS-induced NFκB activation and high phosphorylation of JNK and ERK1/2 were markedly suppressed by DPDS in HBZY-1 cells. In summary, these data demonstrated that DPDS improves t-BHP-induced oxidative stress by activating the Nrf2/Keap1 pathway, and also improves LPS-induced inflammation via inhibition of the NFκB/MAPK pathways in HBZY-1 cells, suggesting that DPDS has the potential to be developed as a candidate for the prevention and treatment of DN.

Therapeutic and Nutraceutical Effects of Polyphenolics from Natural Sources

The prevalence of cardiovascular disease, oxidative stress-related complications, and chronic age-related illnesses is gradually increasing worldwide. Several causes include the ineffectiveness of medicinal treatment therapies, their toxicity, their inability to provide radical solutions in some diseases, and the necessity of multiple drug therapy in certain chronic diseases. It is therefore necessary for alternative treatment methods to be sought. In this review, polyphenols were identified and classified according to their chemical structure, and the sources of these polyphenol molecules are indicated. The cardioprotective, ROS scavenging, anti-aging, anticancer properties of polyphenolic compounds have been demonstrated by the results of many studies, and these natural antioxidant molecules are potential alternative therapeutic agents.

Molecular Mechanistic Pathways Targeted by Natural Compounds in the Prevention and Treatment of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is one of the most common complications of diabetes, and its prevalence is still growing rapidly. However, the efficient therapies for this kidney disease are still limited. The pathogenesis of DKD involves glucotoxicity, lipotoxicity, inflammation, oxidative stress, and renal fibrosis. Glucotoxicity and lipotoxicity can cause oxidative stress, which can lead to inflammation and aggravate renal fibrosis. In this review, we have focused on in vitro and in vivo experiments to investigate the mechanistic pathways by which natural compounds exert their effects against the progression of DKD. The accumulated and collected data revealed that some natural compounds could regulate inflammation, oxidative stress, renal fibrosis, and activate autophagy, thereby protecting the kidney. The main pathways targeted by these reviewed compounds include the Nrf2 signaling pathway, NF-κB signaling pathway, TGF-β signaling pathway, NLRP3 inflammasome, autophagy, glycolipid metabolism and ER stress. This review presented an updated overview of the potential benefits of these natural compounds for the prevention and treatment of DKD progression, aimed to provide new potential therapeutic lead compounds and references for the innovative drug development and clinical treatment of DKD.

Oxidative Stress and NRF2/KEAP1/ARE Pathway in Diabetic Kidney Disease (DKD): New Perspectives

Diabetes mellitus (DM) is one of the most debilitating chronic diseases worldwide, with increased prevalence and incidence. In addition to its macrovascular damage, through its microvascular complications, such as Diabetic Kidney Disease (DKD), DM further compounds the quality of life of these patients. Considering DKD is the main cause of end-stage renal disease (ESRD) in developed countries, extensive research is currently investigating the matrix of DKD pathophysiology. Hyperglycemia, inflammation and oxidative stress (OS) are the main mechanisms behind this disease. By generating pro-inflammatory factors (e.g., IL-1,6,18, TNF-α, TGF-β, NF-κB, MCP-1, VCAM-1, ICAM-1) and the activation of diverse pathways (e.g., PKC, ROCK, AGE/RAGE, JAK-STAT), they promote a pro-oxidant state with impairment of the antioxidant system (NRF2/KEAP1/ARE pathway) and, finally, alterations in the renal filtration unit. Hitherto, a wide spectrum of pre-clinical and clinical studies shows the beneficial use of NRF2-inducing strategies, such as NRF2 activators (e.g., Bardoxolone methyl, Curcumin, Sulforaphane and their analogues), and other natural compounds with antioxidant properties in DKD treatment. However, limitations regarding the lack of larger clinical trials, solubility or delivery hamper their implementation for clinical use. Therefore, in this review, we will discuss DKD mechanisms, especially oxidative stress (OS) and NRF2/KEAP1/ARE involvement, while highlighting the potential of therapeutic approaches that target DKD via OS.

Baicalin Alleviates Contrast-Induced Acute Kidney Injury Through ROS/NLRP3/Caspase-1/GSDMD Pathway-Mediated Proptosis in vitro

Purpose

To investigate the effect of baicalin on the reactive oxygen species (ROS)/ NOD-like receptor protein 3 (NLRP3)/Caspase-1/gasdermin-D (GSDMD) inflammasome pathway and its related mechanism in regulating pyroptosis of human renal tubular epithelial cells (HK-2) induced by contrast media.

Methods

Iohexol was used to act on HK-2 cells to establish a renal tubular cell pyroptosis model; and the signal pathway genes were silenced, cytokines were detected by enzyme-linked immunosorbent assay (ELISA), and cell viability, gene expression, and protein expression were evaluated by double fluorescence staining and flow cytometry. To assess the cytotoxicity caused by the contrast agent; cells were pretreated with different concentrations of baicalin; and then the cells were exposed to iohexol again, and the relevant indicators were tested again.

Results

After HK-2 cells were exposed to iohexol, the NLRP3 inflammasome pathway markers NLRP3, interleukin (IL)-1β, and IL-18 mRNA levels as well as the protein expression levels of NLRP3, ASC, Caspase-1, and GSDMD were up-regulated. In addition, the effect also significantly increased the IL-18, IL-1β, lactate dehydrogenase (LDH), superoxide dismutase (SOD), malondialdehyde (MDA) release, and cellular ROS levels. The results of Annexin V-FITC/PI flow cytometry showed that the level of apoptosis was increased. However, after the intervention of baicalin, the changes in the above indexes caused by iohexol stimulation of HK-2 cells were inhibited.

Conclusion

Exposure to iohexol can induce pyroptosis of HK-2 cells through the ROS/NLRP3/Caspase-1/GSDMD signaling pathway. Baicalin ameliorated iohexol-induced pyroptosis in HK-2 cells by regulating the NLRP3 inflammasome pathway.

Steatosis is involved in the progression of kidney disease in a high-fat-diet-induced non-alcoholic steatohepatitis mouse model

Chronic kidney disease (CKD) and non-alcoholic steatohepatitis (NASH) are major health issues associated with the metabolic syndrome. Although NASH is a known risk factor of CKD, the mechanisms linking these two diseases remain poorly understood. We aimed to investigate alterations in the kidney complicated with dyslipidemia in an established NASH mouse model. Male C57BL6/J mice were fed with control diet or high-fat diet (HFD), containing 40% fat, 22% fructose, and 2% cholesterol for 16 weeks. Metabolic characteristics, histological changes in the kidney, endoplasmic reticulum (ER) stress, apoptosis, and fibrosis were evaluated by histological analysis, immunoblotting, and quantitative reverse transcription-polymerase chain reaction. Levels of serum aspartate aminotransferase, alanine aminotransferase, alkali-phosphatase, total cholesterol, and urinary albumin were significantly higher in mice fed with HFD. Remarkable steatosis, glomerular hypertrophy, and interstitial fibrosis were also shown in in the kidney by leveraging HFD. Furthermore, HFD increased the mRNA expression levels of Casp3, Tgfb1, and Nfe2l2 and the protein level of BiP. We observed the early changes of CKD and speculate that the underlying mechanisms that link CKD and NASH are the induction of ER stress and apoptosis. Further, we observed the activation of Nfe2l2 in the steatosis-induced CKD mouse model. This NASH model holds implications in investigating the mechanisms linking dyslipidemia and CKD.

Therapeutic potential of resveratrol in diabetic nephropathy according to molecular signaling

BACKGROUND

Diabetic nephropathy (DN) as a severe complication of diabetes mellitus (DM), is a crucial menace for human health and survival and remarkably elevates the healthcare systems' costs. Therefore, it is worth noting to identify novel preventive and therapeutic strategies to alleviate the disease conditions. Resveratrol, as a well-defined anti-diabetic/ antioxidant agent has capabilities to counteract diabetic complications. It has been predicted that resveratrol will be a fantastic natural polyphenol for diabetes therapy in the next few years.

OBJECTIVE

Accordingly, the current review aims to depict the role of resveratrol in the regulation of different signaling pathways that are involved in the reactive oxygen species (ROS) production, inflammatory processes, autophagy, and mitochondrial dysfunction, as critical contributors to DN pathophysiology.

RESULTS

The pathogenesis of DN can be multifactorial; hyperglycemia is one of the prominent risk factors of DN development that is closely related to oxidative stress. Resveratrol, as a well-defined polyphenol, has various biological and medicinal properties, including anti-diabetic, anti-inflammatory, and anti-oxidative effects.

CONCLUSION

Resveratrol prevents kidney damages that are caused by oxidative stress, enhances antioxidant capacity, and attenuates the inflammatory and fibrotic responses. For this reason, resveratrol is considered an interesting target in DN research due to its therapeutic possibilities during diabetic disorders and renal protection.

A novel biphenyl diester derivative, AB38b, inhibits glioblastoma cell growth via the ROS-AKT/mTOR pathway

AB38b is a novel biphenyl diester derivative synthesized in our laboratory, and it has been shown to improve the pathology of nephropathy and encephalopathy in diabetic mice. Glioblastoma (GBM) is the most lethal brain tumor, without effective drugs to date. The present study aims at investigating the role of AB38b in GBM growth and revealing the underlying molecular mechanisms. We found that AB38b administration showed a dose- and time-dependent inhibition on cell proliferation in multiple immortalized and primary GBM cell lines, but it had no significant effects on human astrocyte cell line. More importantly, AB38b blocked cell cycle progression, induced early apoptosis, decreased the activity of AKT/mTOR pathway, and increased the generation of reactive oxygen species (ROS) in GBM cells. Interestingly, antioxidant treatments could reverse the AB38b-mediated abovementioned effects; overexpression of constitutively active AKT could partially rescue the suppressive effects of Ab38b on GBM cell proliferation. In addition, AB38b administration inhibited the tumor growth, decreased the activity of AKT/mTOR pathway, and prolonged the survival time in GBM animal models, without any adverse influences on the important organs. These findings suggest that AB38b exerts anti-glioma activity via elevating the ROS generation followed by inhibiting the activity of AKT/mTOR pathway.

Protective Effect of Yi Shen Pai Du Formula against Diabetic Kidney Injury via Inhibition of Oxidative Stress, Inflammation, and Epithelial-to-Mesenchymal Transition in db/db Mice

OBJECTIVE

Diabetic kidney disease (DKD) is one of the most common chronic microvascular complications of diabetes; however, there remains a lack of effective therapeutic strategies. Yi Shen Pai Du Formula (YSPDF), a traditional Chinese medicine preparation, has been clinically used in treating chronic kidney disease (CKD) for more than 20 years. However, whether YSPDF has a therapeutic effect on DKD has not been studied.

METHODS

This study was conducted to investigate the effect of YSPDF administration on db/db mice, a model of type 2 diabetes that develops DKD, and reveal its underlying mechanism of action through a high glucose- (HG-) induced renal injury cell model.

RESULTS

We found that YSPDF significantly improved numerous biochemical parameters (fasting blood glucose, serum creatinine, blood urea nitrogen, 24 h urine total protein, total cholesterol, and total triglycerides) and ameliorated the abnormal histology and fibrosis of renal tissue. Moreover, the status of oxidative stress and levels of inflammatory cytokines (TNF-α, IL-6, IL-1β, and MCP-1) were markedly inhibited by YSPDF treatment. YSPDF treatment significantly mitigated renal fibrosis, with evidence suggesting that this was by inhibiting epithelial-to-mesenchymal transition (EMT) via suppression of the TGF-β1/Smad pathway. Interestingly, the expression of Nrf2, HO-1, and NQO1, proteins known to be associated with oxidative stress, were significantly increased upon administration of YSPDF. The levels of NLRP3 inflammasome proteins, including NLRP3, ASC, caspase-1, and cleaved caspase-1 were decreased in the YSPDF-treated group. Cell experiments showed that YSPDF inhibited EMT and the NLRP3 inflammasome in HG-exposed HK-2 cells, possibly via activation of Nrf2.

CONCLUSION

Our study indicates that YSPDF may ameliorate renal damage in db/db mice via inhibition of oxidative stress, inflammation, and EMT, with the mechanism potentially being related to the activation of the Nrf2 pathway.

An updated pharmacological insight of resveratrol in the treatment of diabetic nephropathy

As one of the most common complications of diabetes, nephropathy develops in approximately 40% of diabetic individuals. Although end stage kidney disease is known as one of the most consequences of diabetic nephropathy, the majority of diabetic individuals might die from cardiovascular diseases and infections before renal replacement treatment. Moreover, the routine medical treatments for diabetes hold undesirable side effects. The explosive prevalence of diabetes urges clinicians and scientists to investigate the complementary or alternative therapies. Phytochemicals are emerging as alternatives with a wide range of therapeutic effects on various pathologies, including diabetic kidney disease. Of those phytochemicals, resveratrol, a natural polyphenolic stilbene, has been found to exert a broad spectrum of health benefits via various signaling molecules. In particular, resveratrol has gained a great deal of attention because of its anti-oxidative, anti-inflammatory, anti-diabetic, anti-obesity, cardiovascular-protective, and anti-tumor properties. In the renal system, emerging evidence shows that resveratrol has already been used to ameliorate chronic or acute kidney injury. This review critically summarizes the current findings and molecular mechanisms of resveratrol in diabetic renal damage. In addition, we will discuss the adverse and inconsistent effects of resveratrol in diabetic nephropathy. Although there is increasing evidence that resveratrol affords great potential in diabetic nephropathy therapy, these results should be treated with caution before its clinical translation. In addition, the unfavorable pharmacokinetics and/or pharmacodynamics profiles, such as poor bioavailability, may limit its extensive clinical applications. It is clear that further research is needed to unravel these limitations and improve its efficacy against diabetic nephropathy. Increasing investigation of resveratrol in diabetic kidney disease will not only help us better understand its pharmacological actions, but also provide novel potential targets for therapeutic intervention.

Humanin regulates oxidative stress in the ovaries of polycystic ovary syndrome patients via the Keap1/Nrf2 pathway

Polycystic ovary syndrome (PCOS) is the most common endocrinological pathology among women of reproductive age, whereas the pathogenesis is still not fully understood. Systemic and ovarian oxidative stress (OS) imbalance is a pivotal feature of PCOS. Humanin, a mitochondria-derived peptide, has been reported to function as an antioxidant in cardiomyocytes, pancreatic beta cells and other cells, but how this function is regulated remains unclear. In this study, we investigated whether humanin expression differs in the granulosa cells (GCs) of PCOS patients versus controls, and whether humanin alleviates OS in PCOS ovaries. Sixteen PCOS patients and 28 age- and BMI-matched controls undergoing IVF were recruited, and their serum, follicular fluid and GCs were collected for humanin analysis. Dehydroepiandrosterone-induced rat PCOS models, and vitamin K3-induced OS COV434 cell lines were applied to investigate the mechanism. Humanin expression was significantly down-regulated in the ovaries of PCOS patients relative to those of non-PCOS patients. Exogenous humanin supplementation significantly attenuated body weight gain, ovarian morphological abnormalities, endocrinological disorders and ovarian and systemic OS in PCOS rat models. Our study further demonstrated that this attenuation effect was involved in the modulation of the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor-erythroid 2-related factor 2 (Nrf2) signalling pathway. In summary, this study reported for the first time that decreased expression of humanin in the GCs was associated with oxidative imbalance in PCOS. Humanin alleviates OS in ovarian GCs of PCOS patients via modulation of the Keap1/Nrf2 signalling pathway.

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.

Sarsasapogenin alleviates diabetic nephropathy through suppression of chronic inflammation by down-regulating PAR-1: In vivo and in vitro study

BACKGROUND

Sarsasapogenin (Sar) shows good effects on diabetic nephropathy (DN) through inhibition of the NLRP3 inflammasome, yet the potential mechanism is not well known.

PURPOSE

This study was designed to explore the regulation of thrombin and/or its receptor protease-activated receptor 1 (PAR-1) on the NLRP3 inflammasome and NF-κB signaling in DN condition, and further expounded the molecular mechanism of Sar on DN.

METHODS

Streptozotocin-induced diabetic rats were treated by gavage with Sar (0, 20 and 60 mg/kg) for consecutive 10 weeks. Then urine and serum were collected for protein excretion, creatinine, urea nitrogen, and uric acid assay reflecting renal functions, renal tissue sections for periodic acid-Schiff staining and ki67 expression reflecting cell proliferation, and renal cortex for the NLRP3 inflammasome and NF-κB signaling as well as thrombin/PAR-1 signaling. High glucose-cultured human mesangial cells (HMCs) were used to further investigate the effects and mechanisms of Sar.

RESULTS

Sar markedly ameliorated the renal functions and mesangial cell proliferation in diabetic rats, and suppressed activation of the NLRP3 inflammasome and NF-κB in renal cortex. Moreover, Sar remarkably down-regulated PAR-1 in protein and mRNA levels but didn't affect thrombin activity in kidney, although thrombin activity was significantly decreased in the renal cortex of diabetic rats. Meanwhile, high glucose induced activation of the NLRP3 inflammasome and NF-κB, and increased PAR-1 expression while didn't change thrombin activity in HMCs; however, Sar co-treatment ameliorated all the above indices. Further studies demonstrated that PAR-1 knockdown attenuated activation of the NLRP3 inflammasome and NF-κB, and Sar addition strengthened these effects in high glucose-cultured HMCs.

CONCLUSION

Sar relieved DN in rat through inhibition of the NLRP3 inflammasome and NF-κB by down-regulating PAR-1 in kidney.

Polysaccharides from the Fleshy Fruits of Camellia oleifera Attenuate the Kidney Injury in High-Fat Diet/Streptozotocin-Induced Diabetic Mice

The fleshy fruits of Camellia oleifera Abel are the immature fruits of C. oleifera, which are infected by Exobasidium vexans Massee and then turn to be intumescent and hollowed. They contain rich trace elements and vitamin C and are eaten directly as wild fruits in the Chinese countryside. Recent studies report that C. oleifera has anti-inflammatory and antioxidative effects. The current study, for the first time, evaluates the renal protective capacity of polysaccharides from the fleshy fruits of C. oleifera (CFFP) in streptozotocin-induced diabetic mice fed high-fat diets. The diabetic mice were orally administered CFFP for 3 months to evaluate the renoprotective function of CFFP. Our results indicated that 250 mg/kg CFFP significantly alleviated diabetes-induced renal injury by decreasing serum creatine, blood urea nitrogen levels, the kidney/body weight ratio, expression of fibronectin and collagen, as well as the secretion of tumor necrosis factor-α and interleukin-6. Additionally, 250 mg/kg CFFP could significantly ameliorate renal oxidative stress through increasing glutathione levels and lowering malondialdehyde contents. We confirmed that CFFP could exert antioxidative, anti-inflammatory, and antifibrosis activities. CFFP might be a potential therapeutic agent, and the fleshy fruits of C. oleifera might be a diet therapy for diabetic patients in the future.