Activation of the Nrf2/ARE signaling pathway protects against palmitic acid-induced renal tubular epithelial cell injury by ameliorating mitochondrial reactive oxygen species-mediated mitochondrial dysfunction

A novel strategy for the protective effect of ginsenoside Rg1 against ovarian reserve decline by the PINK1 pathway

CONTEXT

The decline in ovarian reserve is a major concern in female reproductive health, often associated with oxidative stress and mitochondrial dysfunction. Although ginsenoside Rg1 is known to modulate mitophagy, its effectiveness in mitigating ovarian reserve decline remains unclear.

OBJECTIVE

To investigate the role of ginsenoside Rg1 in promoting mitophagy to preserve ovarian reserve.

MATERIALS AND METHODS

Ovarian reserve function, reproductive capacity, oxidative stress levels, and mitochondrial function were compared between ginsenoside Rg1-treated and untreated naturally aged female Drosophila using behavioral, histological, and molecular biological techniques. The protective effects of ginsenoside Rg1 were analyzed in a Drosophila model of oxidative damage induced by tert-butyl hydroperoxide. Protein expression levels in the PINK1/Parkin pathway were assessed, and molecular docking and PINK1 mutant analyses were conducted to identify potential targets.

RESULTS

Ginsenoside Rg1 significantly mitigated ovarian reserve decline, enhancing offspring quantity and quality, increasing the levels of ecdysteroids, preventing ovarian atrophy, and elevating germline stem cell numbers in aged Drosophila. Ginsenoside Rg1 improved superoxide dismutase, catalase activity, and gene expression while reducing reactive oxygen species levels. Ginsenoside Rg1 activated the mitophagy pathway by upregulating PINK1, Parkin, and Atg8a and downregulating Ref(2)P. Knockdown of PINK1 in the ovary by RNAi attenuated the protective effects of ginsenoside Rg1. Molecular docking analysis revealed that the ginsenoside Rg1 could bind to the active site of the PINK1 kinase domain.

DISCUSSION AND CONCLUSIONS

Ginsenoside Rg1 targets PINK1 to regulate mitophagy, preserving ovarian reserve. These findings suggest the potential of ginsenoside Rg1 as a therapeutic strategy to prevent ovarian reserve decline.

The protective effect of Ambrosia maritima versus vitamin D3 against gentamicin-induced acute cortical kidney injury in adult male albino rats: Histological and immunohistochemical study

Gentamicin (GM) is a broad-spectrum antibiotic widely used for severe bacterial infections, but itis associated with acute nephrotoxicity. Ambrosia maritima L. is an annual herbaceous plant that has avariety of medicinal and antioxidant activities. Vitamin D3 is involved in a multitude of biological functions and essential antioxidant pathways. This study aims to investigate the protective effects of Damsissa (Ambrosia maritima) versus vitamin D3 against GM-induced nephrotoxicity using 72 male rats that were randomly divided into six groups: control, Damsissa (100 mg/kg/day), vitamin D3 (1000 IU/kg/day), GM(100 mg/kg/day for 7 days), GM + Damsissa, and GM + vitamin D3. Renal function, oxidative stress biomarkers (MDA, CAT, SOD, GSH), cytokine levels (IL-1β, IL-6, TNF-α, IL-4), and gene expression (Caspase-3, Keap1, PPARγ, Nrf2) were assessed. Histopathological and ultrastructural kidney analyses were conducted using H&E, Masson's trichrome, PCNA staining, and transmission electron microscopy. Blood samples were tested for renal and liver markers (creatinine, BUN, AST, ALT). Damsissa enhanced survival rates, returned the renal indices to near normal, and ameliorated pathological changes based on immunohistopathological and ultrastructural results. They further reduced pro-inflammatory cytokine production, optimized oxidative stress markers, and normalized gene expression levels. Both treatments exhibited abundant antioxidant and anti-inflammatory effects, which remarkably reduced GM-induced acute kidney injury. These results suggest that both Damsissa and vitamin D3 may exert protective effects against drug-induced nephrotoxicity.

Transcriptome profiling of serum exosomes by RNA-Seq reveals lipid metabolic changes as a potential biomarker for evaluation of roxadustat treatment of chronic kidney diseases

The incidence of chronic kidney disease (CKD) is increasing globally; however, effective preventive and therapeutic strategies are currently limited. Roxadustat is being clinically used to treat renal anemia in CKD patients to reduce anemia-related complications and improve patients' life quality. Exosomes are small vesicles carrying important information that contribute to cell-to-cell communication and are present in various body fluids. However, little is known about the role of serum exosomes and their association with CKD after roxadustat treatment. Next-generation sequencing approaches have revealed that exosomes are enriched in noncoding RNAs and thus exhibit great potential as sensitive nucleic acid biomarkers in various human diseases. In this study, we aimed to identify the changed mRNAs-lncRNAs after roxadustat treatment as novel biomarkers for assessing the efficiency of the treatment. Through our study using RNA-seq data, we identified 957 mRNAs (626 upregulated and 331 downregulated after roxadustat treatment) and 914 lncRNAs (444 upregulated and 470 downregulated) derived from exosomes that were significantly changed, which was highly correlated to lipid metabolism. Our analysis through whole transcriptome profiling of exosome RNAs encompasses an identified differentially expressed mRNA-lncRNA regulatory axis in a larger patient cohort for the validation of suitable biomarkers for assessing CKD after roxadustat treatment.

Fluxomics combined with shotgun proteomics reveals a differential response of bovine kidney cells to extracellular palmitic and α-linolenic acid

Pyruvate carboxylase (PC) catalyzes the formation of oxaloacetate, a TCA cycle intermediate and gluconeogenic substrate. Altering saturated to unsaturated fatty acid ratio alters PC expression, suggesting a central role in mediating carbon flow through metabolic pathways. Herein, we describe changes in metabolic flux of TCA cycle intermediates and proteome in Madin-Darby bovine kidney (MDBK) cells with PC expression knocked-down (PC-KD), overexpressed (PC-OE), unaltered using a Scramble control, or cells pretreated for 21 h with vehicle control bovine serum albumin (BSA) or different ratios of palmitic acid (P) and α-linolenic acid (L) ranging from 1 mM P:0 mM L (1P:0L) to 0P:1L. All cells were collected for proteome analysis and to measure [U-13C] pyruvate flux or oxidation of [1-14C] palmitic acid and [U-14C] lactate. Compared with Scramble, 13C enrichment of all TCA cycle intermediates was greater in PC-OE, but all were reduced in PC-KD except succinate. Proteins greater in abundance in both cell lines included solute transporters, propionyl CoA carboxylase, and fatty acid binding protein 3. Relative to BSA, 1P:0L increased cell death and increased 13C flux to citrate but decreased enrichment of succinate. Abundance of citrate synthase, aconitase, glutamine aminotransferases, and succinyl CoA synthetases was greater in 1P:0L, but not different in other pretreatments. Results indicate preferential utilization of pyruvate and amino acids by 1P:0L cells whereas 0P:1L treated cells show preference for α-linolenic acid metabolism. PC regulates metabolic flux, C18:3n - 3 cis prevents lipotoxicity, and both alterations in PC and the addition of C18:3n - 3 cis promote oxidation of fatty acids.NEW & NOTEWORTHY PC overexpression increases the capacity for fatty acid oxidation, whereas PC knockdown requires extracellular amino acids to support TCA cycle intermediates. Cells incubated in palmitic acid demonstrated dependency of pyruvate and amino acids as substrates for the TCA cycle. Exposure to α-linolenic acid reduces the dependency of pyruvate as a substrate likely because carbon from α-linolenic acid can be used to supply TCA cycle intermediates whereas palmitic acid carbon is not used.

Gut-kidney interaction reinforces dapagliflozin-mediated alleviation in diabetic nephropathy

Intestinal microbiota are pathophysiologically involved in diabetic nephropathy (DN). Dapagliflozin, recognized for its blood glucose-lowering effect, has demonstrated efficacy in improving DN. However, the mechanisms beyond glycemic control that mediate the impact of dapagliflozin on DN remain unclear. Here, we investigated the effects of dapagliflozin on DN and gut microbiota, elucidating how it mitigates DN via the gut-kidney axis. Low-dose dapagliflozin markedly ameliorated renal inflammation and fibrosis and improved gut barrier function in high-fat diet (HFD)/streptozotocin (STZ)-induced DN mice and db/db mice without affecting blood glucose levels. These effects were associated with altered gut microbial composition and function. Eradication of the resident microbiota abolished the protective effects of dapagliflozin against kidney injury in DN mice. Moreover, dapagliflozin significantly altered microbial metabolites in DN mice, decreasing argininosuccinic acid (ASA) and palmitic acid (PA), while increasing S-allylcysteine (SAC) levels. ASA and PA increased the expression of renal inflammation- and fibrosis-related markers in HK-2 cells, whereas SAC ameliorated renal damage and altered the microbial composition in a manner similar to dapagliflozin in DN mice. Notably, Muribaculaceae and Desulfovibrionaceae were correlated with the alleviation of DN-associated renal dysfunction by low- and high-dose dapagliflozin treatments in DN mice. These findings demonstrate a potential application of dapagliflozin in managing DN by targeting the gut microbiota.NEW & NOTEWORTHY We demonstrated that dapagliflozin administration alleviated renal inflammation and fibrosis in vivo and in vitro, along with reshaping the gut microbiota composition and altering levels of key microbial metabolites, including argininosuccinic acid (ASA) and palmitic acid (PA), while increasing S-allylcysteine (SAC). Importantly, the genera Muribaculaceae and Desulfovibrionaceae emerged as pivotal microbial genera mediating the protective effects of dapagliflozin against diabetic nephropathy.

Radish red attenuates chronic kidney disease in obese mice through repressing oxidative stress and ferroptosis via Nrf2 signaling improvement

Chronic kidney disease (CKD) presents a significant public health concern, with obesity being a prominent contributing factor to kidney disorders by inducing oxidative stress, lipotoxicity, and tubular cell injury. Natural anthocyanins extracted from red radishes (Raphanus sativus L.) exert antioxidant and anti-apoptotic functions. This study aims to employ a novel natural pigment anthocyanin, referred to as radish red (RR) isolated from red radishes, to alleviate obesity-related metabolic disturbances and kidney impairment in a CKD mouse model induced by high-fat and high-fructose diets (HFFD). The in vitro study initially demonstrated that RR treatment significantly mitigated the palmitate acid (PA)-induced injury and cytotoxicity in human tubular epithelial HK2 cells. Subsequently, RR supplementation notably improved obesity and associated metabolic dysfunctions in mice caused by HFFD. Abnormal renal function indices including serum creatinine, blood urea nitrogen (BUN), uric acid (UA), urine protein, albuminuria and urine albumin-to-creatinine ratio (UACR) were detected in HFFD-fed mice, which were effectively alleviated by RR treatment. Histologically, renal tubular cell injury, lipid deposition, tubular dilatation, and renal fibrosis induced by HFFD were markedly improved after RR administration in mice. Furthermore, RR treatment significantly alleviated oxidative stress in HFFD-fed mice, as evidenced by the decreased renal reactive oxygen species (ROS) production, 4-HNE, and NOX4 expression levels. Anti-oxidants such as superoxide dismutase-1 (SOD1), NAD (P) H: quinone oxidoreductase (NQO1), heme oxygenase-1 (HO-1) and glutamate cysteine ligase (GCLC) were highly upregulated in kidney of HFFD-fed mice with RR consumption through improving NFE2-related factor 2 (Nrf2) signaling activation. Furthermore, ferroptosis was identified in the kidneys of HFFD-fed mice, evidenced by the elevated levels of malondialdehyde (MDA), iron content, and lipid peroxidation, along with the decreased expression of glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11). These occurrences were significantly mitigated following RR treatment. Mechanistically, we further discovered that the suppressive effects of RR in restricting oxidative stress, ferroptosis, lipid accumulation, and injury of tubular epithelial cells induced by PA were significantly counteracted by Nrf2 knockdown. Collectively, our results demonstrated that dietary supplementation with RR could potentially serve as an efficacious therapeutic modality for the management of obesity-related CKD progression by enhancing Nrf2 activation to impede oxidative stress and ferroptosis.

Sedentary Lifestyles and a Hypercaloric Diets During Middle Age, are Binomial Conducive to Fatal Progression, That is Counteracted by the Hormetic Treatment of Exercise, Metformin, and Tert-Butyl Hydroquinone: An Analysis of Female Middle-Aged Rat Liver Mitochondria

The world's population continuous to shift towards older, less active and more sedentary lifestyles especially during middle age. In addition consumption of high-caloric diets, increases the risk of metabolic and cardiovascular afflictions. Developing clinical strategies to mitigate those health complications represent a difficult challenge. Our group has previously shown that combining metformin (MTF) and tert-butyl hydroquinone (tBHQ) treatments, in addition to exercise, partially prevents liver damage associated with obesity. Hence, we evaluated the role of exercise in combination with MTF and tBHQ (triple-treatment) to counteract mitochondrial damage in the liver from obese middle-aged female rats. Animals were fed a high-fat diet (HFD) starting at 21 days till 15 months of age. The treated groups performed a Fartlek-type exercise 5 days/week for 30 min/session. MTF and tBHQ were administered at a dose of 250 mg/kg/day, and 10 mg/kg/day, respectively, for 7 days/month from 10 to 15 months of age. Triple-treatment therapeutic approach promoted animal survival, and increased AMPK and PGC1α expression. Treatments increased mitochondrial ATP synthesis and OXPHOS complexes activities, recovered membrane potential, and decreased ROS production. In summary, exercise in combination with intermittent tBHQ and MTF treatments proved to be an excellent intervention to prevent mitochondrial damage caused by HFD.

DACH1 attenuated PA-induced renal tubular injury through TLR4/MyD88/NF-κB and TGF-β/Smad signalling pathway

BACKGROUND

Palmitic acid (PA), the major saturated fatty acid in the blood, often induces the initiation and progression of diabetic kidney disease (DKD). However, the underlying mechanism remains unclear. DACH1 is an important regulator of kidney functions. Herein, we investigated the roles of DACH1 in PA-induced kidney injury.

METHODS

Clinical data from the NHANES database were subjected to analyse the association between serum PA (sPA), blood glucose and kidney function. Molecular docking of PA was performed with DACH1. Immunohistochemistry, cell viability, annexin V/7-AAD double staining, TUNEL assay, immunofluorescent staining, autophagic flux analysis, qRT-PCR and western blot were performed.

RESULTS

Clinical data confirmed that sPA was increased significantly in the pathoglycemia individuals compared with controls and correlated negatively with renal function. Our findings suggested that PA could dock with DACH1. DACH1 enhances cell viability by inhibiting apoptosis and attenuating autophagy blockage induced by PA. Furthermore, the results demonstrated that DACH1 ameliorated inflammation and fibrosis through TLR4/MyD88/NF-κB and TGF-β/Smad signalling pathway in PA-treated renal tubular epithelial cell line (HK-2).

CONCLUSIONS

This study proved that sPA presents a risk factor for kidney injuries and DACH1 might serve as a protective target against renal function deterioration in diabetic patients.

Lipotoxicity and immunometabolism in ischemic acute kidney injury: current perspectives and future directions

Dysregulated lipid metabolism is implicated in the pathophysiology of a range of kidney diseases. The specific mechanisms through which lipotoxicity contributes to acute kidney injury (AKI) remain poorly understood. Herein we review the cardinal features of lipotoxic injury in ischemic kidney injury; lipid accumulation and mitochondrial lipotoxicity. We then explore a new mechanism of lipotoxicity, what we define as "immunometabolic" lipotoxicity, and discuss the potential therapeutic implications of targeting this lipotoxicity using lipid lowering medications.

Farnesol Inhibits PI3 Kinase Signaling and Inflammatory Gene Expression in Primary Human Renal Epithelial Cells

Chronic inflammation and elevated cytokine levels are closely associated with the progression of chronic kidney disease (CKD), which is responsible for the manifestation of numerous complications and mortality. In addition to conventional CKD therapies, the possibility of using natural compounds with anti-inflammatory potential has attracted widespread attention in scientific research. This study aimed to study the potential anti-inflammatory effects of a natural oil compound, farnesol, in primary human renal proximal tubule epithelial cell (RPTEC) culture. Farnesol was encapsulated in lipid-based small unilamellar vesicles (SUVs) to overcome its insolubility in cell culture medium. The cell attachment of empty vesicles (SUVs) and farnesol-loaded vesicles (farnesol-SUVs) was examined using BODIPY, a fluorescent dye with hydrophobic properties. Next, we used multiple protein, RNA, and protein phosphorylation arrays to investigate the impact of farnesol on inflammatory signaling in RPTECs. The results indicated that farnesol inhibits TNF-α/IL-1β-induced phosphorylation of the PI3 kinase p85 subunit and subsequent transcriptional activation of the inflammatory genes TNFRSF9, CD27, TNFRSF8, DR6, FAS, IL-7, and CCL2. Therefore, farnesol may be a promising natural compound for treating CKD.

Emodin disrupts the Notch1/Nrf2/GPX4 antioxidant system and promotes renal cell ferroptosis

Emodin has been demonstrated to possess multiple pharmacological activities. However, emodin has also been reported to induce nephrotoxicity at high doses and with long-term use, and the underlying mechanism has not been fully disclosed. The current study aimed to investigate the roles of oxidative stress and ferroptosis in emodin-induced kidney toxicity. Mice were intraperitoneally treated with emodin, and NRK-52E cells were exposed to emodin in the presence or absence of treatment with Jagged1, SC79, or t-BHQ. Emodin significantly upregulated the levels of blood urea nitrogen, serum creatinine, malondialdehyde, and Fe2+ , reduced the levels of superoxide dismutase and glutathione, and induced pathological changes in the kidneys in vivo. Moreover, the viability of NRK-52E cells treated with emodin was reduced, and emodin induced iron accumulation, excessive reactive oxygen species production, and lipid peroxidation and depolarized the mitochondrial membrane potential (ΔΨm). In addition, emodin treatment downregulated the activity of neurogenic locus notch homolog protein 1 (Notch1), reduced the nuclear translocation of nuclear factor erythroid-2 related factor 2 (Nrf2), and decreased glutathione peroxidase 4 protein levels. However, Notch1 activation by Jagged1 pretreatment, Akt activation by SC79 pretreatment, or Nrf2 activation by t-BHQ pretreatment attenuated the toxic effects of emodin in NRK-52E cells. Taken together, these results revealed that emodin-induced ferroptosis triggered kidney toxicity through inhibition of the Notch1/Nrf2/glutathione peroxidase 4 axis.

Chicoric Acid Presented NLRP3-Mediated Pyroptosis through Mitochondrial Damage by PDPK1 Ubiquitination in an Acute Lung Injury Model

Chicoric acid (CA), a functional food ingredient, is a caffeic acid derivative that is mainly found in lettuce, pulsatilla, and other natural plants. However, the anti-inflammatory effects of CA in acute lung injury (ALI) remain poorly understood. This study was conducted to investigate potential drug usage of CA for ALI and the underlying molecular mechanisms of inflammation. C57BL/6 mice were given injections of liposaccharide (LPS) to establish the in vivo model. Meanwhile, BMDM cells were stimulated with LPS+ATP to build the in vitro model. CA significantly alleviated inflammation and oxidative stress in both the in vivo and in vitro models of ALI through the inhibition of NLR family pyrin domain-containing 3 (NLRP3)-mediated pyroptosis. In addition, CA attenuated mitochondrial damage to suppress NLRP3-mediated pyroptosis in the in vivo and in vitro models of ALI by suppressing the production of reactive oxygen species (ROS) via inhibiting the Akt/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. CA inhibited the interaction between Akt at T308 and phosphoinositide-dependent kinase-1 (PDPK1) at S549, thus promoting the phosphorylation of the Akt protein. Furthermore, CA directly targeted the PDPK1 protein and accelerated PDPK1 ubiquitination, indicating that 91-GLY, 111-LYS, 126-TYR, 162-ALA, 205-ASP, and 223-ASP might be responsible for the interaction between PDPK1 and CA. In conclusion, CA from Lettuce alleviated NLRP3-mediated pyroptosis in the ALI model through ROS-induced mitochondrial damage by activating Akt/Nrf2 pathway via PDPK1 ubiquitination. The present study suggests that CA might be a potential therapeutic drug to treat or prevent ALI in pneumonia or COVID-19.

Roles of Oxidative Stress and Nrf2 Signaling in Pathogenic and Non-Pathogenic Cells: A Possible General Mechanism of Resistance to Therapy

The coordinating role of nuclear factor erythroid-2-related factor 2 (Nrf2) in cellular function is undeniable. Evidence indicates that this transcription factor exerts massive regulatory functions in multiple signaling pathways concerning redox homeostasis and xenobiotics, macromolecules, and iron metabolism. Being the master regulator of antioxidant system, Nrf2 controls cellular fate, influencing cell proliferation, differentiation, apoptosis, resistance to therapy, and senescence processes, as well as infection disease success. Because Nrf2 is the key coordinator of cell defence mechanisms, dysregulation of its signaling has been associated with carcinogenic phenomena and infectious and age-related diseases. Deregulation of this cytoprotective system may also interfere with immune response. Oxidative burst, one of the main microbicidal mechanisms, could be impaired during the initial phagocytosis of pathogens, which could lead to the successful establishment of infection and promote susceptibility to infectious diseases. There is still a knowledge gap to fill regarding the molecular mechanisms by which Nrf2 orchestrates such complex networks involving multiple pathways. This review describes the role of Nrf2 in non-pathogenic and pathogenic cells.