Effective dose/duration of natural flavonoid quercetin for treatment of diabetic nephropathy: A systematic review and meta-analysis of rodent data

Use quercetin for pulmonary fibrosis: a preclinical systematic review and meta-analysis

BACKGROUND

Pulmonary fibrosis (PF) is an age-related interstitial lung disease, which lacks effective drug treatment at present. Quercetin has been shown to have favorable anti-inflammatory and anti-fibrotic properties, and preliminary evidence suggests its potential efficacy and tolerability in PF patients. However, a comprehensive systematic review and evaluation of the protective effects and potential mechanisms of quercetin in PF models remains to be completed. Therefore, we conducted this study.

METHODS

The PubMed, Cochrane Library, Embase, and Web of Science databases were searched up to the April 1, 2024. CAMARADES was the methodological quality assessment tool. And statistical analyses were conducted with R and Stata 16.0. Origin was used for a three-dimensional (3D) dosage-intervention duration-efficacy model for quercetin treatment of PF.

RESULTS

A total of 20 studies, encompassing 44 independent experiments and involving 1019 animals, were included in the analysis. Meta-analysis revealed that quercetin significantly mitigated lung pathological tissue scores and the expression of lung fibrosis markers in PF animal models. Furthermore, quercetin significantly ameliorated inflammatory responses, oxidative stress, epithelial-mesenchymal transition and myofibroblast activation, cell senescence and apoptosis, and the markers expression of extracellular matrix (ECM) deposition. Quercetin did not show significant hepatic and nephrotoxicity. The 3D dosage-intervention duration-efficacy model indicated that a dosing period over 20 days and dosages range of 5-100 mg/kg were appropriate modalities.

CONCLUSION

Herein, our study highlights the potential of quercetin in the treatment of PF and the available mechanisms.

Integrated metabolomics and mass spectrometry imaging analysis reveal the efficacy and mechanism of Huangkui capsule on type 2 diabetic nephropathy

BACKGROUND

Huangkui capsule (HKC), a Chinese patent medicine, is clinically used for treating diabetic nephropathy. However, the core disease-specific biomarkers and targets of type 2 diabetic nephropathy (T2DN) and the therapeutic mechanism of HKC are not fully elucidated.

PURPOSE

This study aimed to investigate the therapeutic effects and underlying molecular mechanisms of HKC for T2DN.

STUDY DESIGN

The db/db mouse model was used to evaluate the efficacy of HKC for T2DN, and the core pathways regulated by HKC were studied to determine its kidney protective mechanism.

METHODS

High-throughput UPLC-MS/MS and multivariate analysis were employed to analyze the serum and kidney metabolic profiles of db/db mice, identifying potential core biomarkers of T2DN. Atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry imaging was used to locate in situ spatial distribution of core biomarkers and drug active ingredients in kidney tissues. Biochemical indicators, histopathology, immunohistochemistry, immunofluorescence, molecular docking, and western blotting were combined to reveal therapeutic effects, pathways, and targets of HKC.

RESULTS

HKC substantially improved pathological characteristics, kidney function, oxidative stress, inflammation, and lipid metabolism indicators of T2DN. Twelve core disease-specific biomarker that significantly influenced clustering were identified and its unique spatial distribution information in the kidneys was revealed. 3-dehydrosphinganine, retinyl ester, and 9-cis-retinoic acid (9cRA) could serve as novel disease-specific biomarkers for T2DN. Based on newly discovered biomarkers, quercetin, myricetin, and isorhamnetin were found to act on key enzymes SPT, ALDH1A1, AOX, LRAT, and DGAT1 in retinol and sphingolipid metabolism pathways. Western blotting showed that HKC ameliorated T2DN by targeting these enzymes, upregulating 9cRA and retinyl ester, downregulating 3-dehydrosphinganine, increasing TGF-β signal transduction, inhibiting the expression of the immune fibrosis proteins OX-8, Col-I and α-SMA, inhibiting Th17 cell development and ceramide synthesis, reducing IL-1β, TNF-α, MDA, TC, LDL-C, and TG levels, and increaseing SOD activity.

CONCLUSIONS

HKC exerts significant therapeutic effects on T2DN. HKC corrects the metabolic disorder of sphingolipids and retinol, and improves T2DN by regulating the activities of SPT, ALDH1A1, AOX, LRAT, and DGAT1. This study provides valuable ideas and new mechanistic insights for the treatment of T2DN with HKC.

Oxidative stress and NRF2 signaling in kidney injury

Oxidative stress plays a crucial role in the pathogenesis of acute kidney injury (AKI), chronic kidney disease (CKD), and the AKI-to-CKD transition. This review examines the intricate relationship between oxidative stress and kidney pathophysiology, emphasizing the potential therapeutic role of nuclear factor erythroid 2-related factor 2 (NRF2), a master regulator of cellular redox homeostasis. In diverse AKI and CKD models, diminished NRF2 activity exacerbates oxidative stress, whereas genetic and pharmacological NRF2 activation alleviates kidney damage induced by nephrotoxic agents, ischemia-reperfusion injury, fibrotic stimuli, and diabetic nephropathy. The renoprotective effects of NRF2 extend beyond antioxidant defense, encompassing its anti-inflammatory and anti-fibrotic properties. The significance of NRF2 in renal fibrosis is further underscored by its interaction with the transforming growth factor-β signaling cascade. Clinical trials using bardoxolone methyl, a potent NRF2 activator, have yielded both encouraging and challenging outcomes, illustrating the intricacy of modulating NRF2 in human subjects. In summary, this overview suggests the therapeutic potential of targeting NRF2 in kidney disorders and highlights the necessity for continued research to refine treatment approaches.

The mediating role of C-reactive protein (CRP) in the dietary intake of flavonoids and the risk of albuminuria

Background: Prior experimental investigations have highlighted the beneficial effects of flavonoid consumption on renal function. However, a comprehensive evaluation of their impact on modulating albuminuria risk within population-based epidemiological studies is still limited. This study aimed to fill this gap by examining the correlation between flavonoid intake and albuminuria risk, while also shedding light on the potential mediating influence of inflammation in this association. Methods: We utilized data from 29 940 participants spanning three cycles (2007-2008, 2009-2010, and 2017-2018) of the National Health and Nutrition Examination Survey (NHANES). We employed rigorous analytical methods, encompassing logistic regression, restricted cubic splines (RCS), and mediation analysis, to assess the link between dietary flavonoid intake and albuminuria risk. Results: Our findings reveal consistent negative associations between total flavonoids and specific subclasses, including flavonols, flavones, flavan-3-ols, anthocyanidins, and catechins, and the risk of albuminuria. Specifically, after adjusting for confounding factors, each logarithmic unit increase in these flavonoid categories was associated with a decrease in albuminuria risk ranging from 3% to 12%. The mediating proportion of C-reactive protein (CRP) in the relationships between the intake of total flavonoids, flavonols, flavones, catechins, and flavan-3-ols and albuminuria risk was 7.3%, 5.6%, 2.3%, 7.7%, and 4.6%, respectively. Conclusions: These results indicate that increased consumption of flavonoid-rich foods contributes to a reduced risk of albuminuria.

Houttuynia cordata Thunb. Extracts Alleviate Atherosclerosis and Modulate Gut Microbiota in Male Hypercholesterolemic Hamsters

Background and Aims: Hypercholesterolemia leads to cardiovascular diseases and atherosclerosis. Previous studies have highlighted the crucial role of gut microbiota in alleviating atherosclerosis progression and reducing plasma cholesterol. However, the protective effects of Houttuynia cordata Thunb (HCT), a well-known fishy Chinese herb, against hypercholesterolemia and vasculopathy remain largely unknown. This study aims to explore the effects of HCT extracts on vascular health and gut microbiota in golden Syrian hamsters with hypercholesterolemia. Methods: The hypercholesterolemia hamster model was established by feeding with a high-cholesterol diet. Aqueous or ethanolic HCT extracts were mixed with diet and concurrently given to hamsters for Six weeks. Plasma lipid profiles were evaluated. Aortas were collected to detect fatty streak areas. Feces were collected to analyze the abundance of microorganisms in the gut microbiota. Results: HCT ethanolic extract treatment remarkedly decreased plasma levels of total cholesterol and high-density lipoprotein cholesterol in hypercholesterolemic hamsters. Notably, both aqueous and ethanolic extracts of HCT reduced atherosclerotic plaques in hamsters fed with a high-cholesterol diet. Strikingly, the effects of HCT ethanolic extract in reducing atherosclerotic plaques are greater than aqueous extract. Furthermore, at the phylum level, the relative abundance of Firmicutes was decreased in hamsters treated with aqueous and ethanolic extracts of HCT. By contrast, the abundance of Bacteroidetes was increased by HCT treatment. At the family level, HCT extract favourably modulated the relative abundance of Porphyromonadaceae and Bacteroidales_S24-7_group. These findings indicate that HCT extracts may facilitate the growth of short-chain fatty acids-producing bacteria to alter gut microbiota composition, contributing to the reduction of plasma lipid levels. Conclusions: This study offers evidence demonstrating the effects of HCT extracts on alleviating atherosclerosis and lowering plasma cholesterol levels in the male hypercholesterolemic hamster model, offering novel insights into the pharmacological effects and promoting the application of HCT. This study highlights the potential of HCT as a dietary supplement to alleviate atherosclerosis, lower plasma cholesterol, and modulate the abundance of microorganisms in gut microbiota.

Network pharmacology and molecular dynamics study of the effect of the Astragalus-Coptis drug pair on diabetic kidney disease

BACKGROUND

Diabetic kidney disease (DKD) is the primary cause of end-stage renal disease. The Astragalus-Coptis drug pair is frequently employed in the management of DKD. However, the precise molecular mechanism underlying its therapeutic effect remains elusive.

AIM

To investigate the synergistic effects of multiple active ingredients in the Astragalus-Coptis drug pair on DKD through multiple targets and pathways.

METHODS

The ingredients of the Astragalus-Coptis drug pair were collected and screened using the TCMSP database and the SwissADME platform. The targets were predicted using the SwissTargetPrediction database, while the DKD differential gene expression analysis was obtained from the Gene Expression Omnibus database. DKD targets were acquired from the GeneCards, Online Mendelian Inheritance in Man database, and DisGeNET databases, with common targets identified through the Venny platform. The protein-protein interaction network and the "disease-active ingredient-target" network of the common targets were constructed utilizing the STRING database and Cytoscape software, followed by the analysis of the interaction relationships and further screening of key targets and core active ingredients. Gene Ontology (GO) function and Kyoto Ency-clopedia of Genes and Genomes (KEGG) pathway enrichments were performed using the DAVID database. The tissue and organ distributions of key targets were evaluated. PyMOL and AutoDock software validate the molecular docking between the core ingredients and key targets. Finally, molecular dynamics (MD) simulations were conducted to simulate the optimal complex formed by interactions between core ingredients and key target proteins.

RESULTS

A total of 27 active ingredients and 512 potential targets of the Astragalus-Coptis drug pair were identified. There were 273 common targets between DKD and the Astragalus-Coptis drug pair. Through protein-protein interaction network topology analysis, we identified 9 core active ingredients and 10 key targets. GO and KEGG pathway enrichment analyses revealed that Astragalus-Coptis drug pair treatment for DKD involves various biological processes, including protein phosphorylation, negative regulation of apoptosis, inflammatory response, and endoplasmic reticulum unfolded protein response. These pathways are mainly associated with the advanced glycation end products (AGE)-receptor for AGE products signaling pathway in diabetic complications, as well as the Lipid and atherosclerosis. Molecular docking and MD simulations demonstrated high affinity and stability between the core active ingredients and key targets. Notably, the quercetin-AKT serine/threonine kinase 1 (AKT1) and quercetin-tumor necrosis factor (TNF) protein complexes exhibited exceptional stability.

CONCLUSION

This study demonstrated that DKD treatment with the Astragalus-Coptis drug pair involves multiple ingredients, targets, and signaling pathways. We propose a novel approach for investigating the molecular mechanism underlying the therapeutic effects of the Astragalus-Coptis drug pair on DKD. Furthermore, we suggest that quercetin is the most potent active ingredient and specifically targets AKT1 and TNF, providing a theoretical foundation for further exploration of pharmacologically active ingredients and elucidating their molecular mechanisms in DKD treatment.

Quercetin prevented diabetic nephropathy by inhibiting renal tubular epithelial cell apoptosis via the PI3K/AKT pathway

Diabetic nephropathy (DN) is the most common and serious complication of diabetes, posing a significant threat to human health. Currently, safe and effective preventive strategies for DN are lacking. The study aimed to explore the preventive effect and the underlying mechanism of quercetin against DN. In the in vivo experiments, we established a mouse model of type 2 diabetes mellitus (T2DM) induced by a combination of high-fat diet (HFD) and streptozotocin (STZ) to explore the preventive effect of quercetin on DN and its protective role against renal tubular epithelial cell apoptosis. Subsequently, in vitro experiments using human tubular epithelial cells (HK-2 cells) were conducted to further validate the protective effects of quercetin on renal tubular epithelial cell apoptosis. Additionally, we employed RNA sequencing analysis (RNA-seq) and network pharmacology analysis to comprehensively elucidate the molecular mechanisms involved. In vivo, we observed a significant increase in the ratio of urinary microalbumin to creatinine in diabetic mice compared to control mice, accompanied by the activation of renal tubular epithelial cell apoptosis. Remarkably, all of these changes were reversed after quercetin treatment. In vitro, high-glucose-induced apoptosis in HK-2 cells was significantly attenuated by quercetin. Subsequent RNA sequencing analysis and network pharmacology analysis revealed that quercetin was most likely to inhibit high-glucose-induced HK-2 cell apoptosis through the PI3K/AKT signaling pathway. Western Blotting results further demonstrated that quercetin could inhibit the activation of the PI3K/AKT signaling pathway in HK-2 cells induced by high glucose. Our results supported that quercetin could prevent DN by inhibiting tubular epithelial cell apoptosis via the PI3K/AKT pathway. Quercetin might be a promising candidate for the prevention of DN.

Modulatory Effects of XIAOPI Formula on CXCL1 and Selected Outcomes in Triple-Negative Breast Cancer: A Randomized Controlled Clinical Trial

Background

Triple-negative breast cancer (TNBC) is the most aggressive malignancy. Psychological distress and elevated CXCL1 level have been reported to be closely associated with the poor prognosis and quality of life of patients with TNBC. In preclinical studies using xenograft mouse models, XIAOPI formula, a nationally approved drug prescribed to patients at high risk for breast cancer, inhibited CXCL1 expression and improved survival. Traditional Chinese medicine has unique advantages in improving patients' emotional disorders and quality of life. However, the impact of XIAOPI formula on the serum level of CXCL1, psychological distress, and quality of life among patients with TNBC is currently unknown.

Methods

In this study, we designed a randomized, double-blind, placebo-controlled trial. Patients with TNBC were randomly assigned to receive either the XIAOPI formula or a placebo for three months. The primary outcomes include serum CXCL1 expression, Self-Rating Anxiety Scale (SAS), and the Self-Rating Depression Scale (SDS). Secondary outcomes included the Pittsburgh Sleep Quality Index (PSQI) and the Functional Assessment of Cancer Therapy-Breast (FACT-B).

Results

A total of 60 patients with TNBC were enrolled in the investigation. The results showed that the XIAOPI formula significantly decreased CXCL1 expression compared with the control group. Moreover, in comparison to the placebo, the XIAOPI formula increased FACT-B scores while decreasing SDS, SAS, and PSQI scores.

Conclusion

In patients with TNBC, XIAOPI formula may be effective in reducing CXCL1 levels, enhancing psychological well-being, and quality of life. While our research offers a natural alternative therapy that may enhance the prognosis of TNBC, future validation of its therapeutic effects will require large-scale, long-term clinical trials.

Clinical Registration Number

Registration website: www.chictr.org.cn, Registration date: 2018-1-19, Registration number: ChiCTR1800014535.

Integrated chemical characterization, metabolite profiling, and pharmacokinetics analysis of Zhijun Tangshen Decoction by UPLC-Q/TOF-MS

Diabetic nephropathy (DN) is the main cause of end-stage renal disease worldwide and a major public issue affecting the health of people. Therefore, it is essential to explore effective drugs for the treatment of DN. In this study, the traditional Chinese medicine (TCM) formula, Zhijun Tangshen Decoction (ZJTSD), a prescription modified from the classical formula Didang Decoction, has been used in the clinical treatment of DN. However, the chemical basis underlying the therapeutic effects of ZJTSD in treating DN remains unknown. In this study, compounds of ZJTSD and serum after oral administration in rats were identified and analyzed using ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q/TOF-MS). Meanwhile, a semi-quantitative approach was used to analyze the dynamic changes in the compounds of ZJTSD in vivo. UPLC-Q/TOF-MS analysis identified 190 compounds from ZJTSD, including flavonoids, anthraquinones, terpenoids, phenylpropanoids, alkaloids, and other categories. A total of 156 xenobiotics and metabolites, i.e., 51 prototype compounds and 105 metabolites, were identified from the compounds absorbed into the blood of rats treated with ZJTSD. The results further showed that 23 substances with high relative content, long retention time, and favorable pharmacokinetic characteristics in vivo deserved further investigations and validations of bioactivities. In conclusion, this study revealed the chemical basis underlying the complexity of ZJTSD and investigated the metabolite profiling and pharmacokinetics of ZJTSD-related xenobiotics in rats, thus providing a foundation for further investigation into the pharmacodynamic substance basis and metabolic regulations of ZJTSD.

Quercetin inhibits caspase-1-dependent macrophage pyroptosis in experimental folic acid nephropathy

BACKGROUND

The role of pyroptosis in kidney disease is limited and incomplete. Quercetin, a flavonoid compound present in a variety of fruits, vegetables, and plants, has shown antioxidant and anti-inflammatory properties. This study was designed to validate the importance of pyroptosis in an experimental model of folic acid nephropathy and to explore the effect of quercetin in protecting against pyroptosis.

METHODS

Gene set enrichment analysis (GSEA) and weighted gene co-expression network analysis (WGCNA) were used to establish the correlation between pyroptosis and folic acid nephropathy. Immune cell infiltration, network pharmacology and single-cell RNA sequencing analysis were utilized to ascertain the specific target of quercetin in relation to pyroptosis. Finally, quercetin's role was verified in vivo and in vitro.

RESULTS

The GSEA analysis revealed a significant correlation between pyroptosis and folic acid nephropathy (NES = 1.764, P = 0.004). The hub genes identified through WGCNA were closely associated with inflammation. Molecular docking demonstrated a strong binding affinity between quercetin and caspase-1, a protein known to be involved in macrophage function, as confirmed by immune cell infiltration and single-cell analysis. Quercetin demonstrated a significant amelioration of kidney injury and reduction in macrophage infiltration in the animal model. Furthermore, quercetin exhibited a significant inhibition of caspase-1 expression, subsequently leading to the inhibition of pro-inflammatory cytokines expression, such as IL-1β, IL-18, TNF-α, and IL-6. The inhibitory effect of quercetin on macrophage pyroptosis was also confirmed in RAW264.7 cells.

CONCLUSION

This study contributes substantial evidence to support the significant role of pyroptosis in the development of folic acid nephropathy, and highlights the ability of quercetin to downregulate caspase-1 in macrophages as a protective mechanism against pyroptosis.

QiDiTangShen granules alleviates diabetic nephropathy podocyte injury: A network pharmacology study and experimental validation in vivo and vitro

Background

QiDiTangShen granules (QDTS), a traditional Chinese medicine (TCM) compound prescription, have remarkable efficacy in diabetic nephropathy (DN) patients, and their pharmacological mechanism needs further exploration.

Methods

According to the active ingredients and targets of the QDTS in the TCMSP database, the network pharmacology of QDTS was investigated. The potential active ingredients were chosen based on the oral bioavailability and the drug similarity index. At the same time, targets for DN-related disease were obtained from GeneCards, OMIM, PharmGKB, TTD, and DrugBank. The TCM-component-target network and the protein-protein interaction (PPI) network were constructed with the Cytoscape and STRING platforms, respectively, and then the core targets of DN were selected with CytoNCA. GO and KEGG enrichment analysis using R software. Molecular docking to identify the core targets of QDTS for DN. In vivo, db/db mice were treated as DN models, and the urine microalbuminuria, the pathological changes in the kidney and the protein expression levels of p-PI3K, p-Akt, JUN, nephrin and synaptopodin were detected by immunohistochemistry, immunofluorescence method and Western blotting. After QDTS was used in vitro, the protein expression of mouse podocyte clone-5 (MPC5) cells was detected by immunohistochemistry, immunofluorescence and Western blot.

Results

Through network pharmacology analysis, 153 potential targets for DN in QDTS were identified, 19 of which were significant. The KEGG enrichment analysis indicated that QDTS might have therapeutic effects on IL-17, TNF, AGE-RAGE, PI3K-Akt, HIF-1, and EGFR through interfering with Akt1 and JUN. The main active ingredients in QDTS are quercetin, β-sitosterol, stigmasterol and kaempferol. Both in vivo and in vitro studies showed that QDTS could decrease the urine microalbuminuria and renal pathology of db/db mice, and alleviate podocyte injuries through the PI3K/Akt signaling pathway.

Conclusion

Through network pharmacology, in vivo and in vitro experiments, QDTS has been shown to improve the urine microalbuminuria and renal pathology in DN, and to reduce podocyte damage via the PI3K/Akt pathway.

Research progress of natural active compounds on improving podocyte function to reduce proteinuria in diabetic kidney disease

Diabetic kidney disease (DKD) is a primary cause of end-stage renal disease. Proteinuria is a clinical indicator of the different stages of DKD, and podocyte injury is a major cause of proteinuria. Podocyte-specific proteins (PSPs) play important roles in the normal filtration of podocytes. Studies have shown that natural active compounds (NACs) can ameliorate proteinuria; however, the mechanism related to PSPs needs to be explored. In this study, the five stages of DKD related to proteinuria and the functions of PSPs are displayed separately. Mechanisms for ameliorating proteinuria and improving the PSPs of the 15 NACs are summarized. The in vitro and in vivo mechanistic research showed that five compounds, astragaloside IV, ligustrazine, berberine, emodin and resveratrol, exerted renal protective effects via AMPK signaling, icariin and berberine via TLR4 signaling, hirudin and baicalin via MAPK signaling, curcumin and baicalin via NF-κB signaling, and emodin via protein kinase RNA-like endoplasmic reticulum kinase signaling. The 13 PSPs were divided into five categories: actin cytoskeleton, basal domain, apical domain, slit diaphragm, and others. In conclusion, anti-inflammatory effects, anti-oxidative stress, and enhanced autophagy are the main mechanisms underlying the ameliorative effects of NACs. Podocyte apoptosis is mainly related to nephrin and podocin, which are the most studied slit diaphragm PSPs.

The neuroprotective effect of quercetin nanoparticles in the therapy of neuronal damage stimulated by acrolein

A gradual loss of neuronal function or structure causes neurodegenerative disorders such as Parkinson's and Alzheimer's. Neurological damage might cause cell death. Acrolein is a high-risk air and water contaminant that causes neurodegenerative disorders. Quercetin has several strategies for treating neurodegenerative disorders but has limited bioavailability inside the body. One of the hypotheses offered to improve quercetin's bioavailability is to convert it into quercetin nanoparticles. This study aims to comprehend the immunohistochemical devastation that might arise in the cerebellum because of acrolein treatment. Furthermore, the protective and ameliorative roles of quercetin nanoparticles against oxidative stress and neurotoxicity induced in mice by acrolein were assessed. Ninety male albino rats weighing 120 to 200 g were used in the present investigation. The animals were split up into the following six groups: the control group, the acrolein-treated group: animals were given acrolein (3 mg/kg) for 30 days, quercetin nanoparticles treated group: animals were given quercetin nanoparticles (30 mg/kg) for 30 days. The administration of acrolein was found to be connected to immunohistochemical abnormalities in the cerebellum. Marked differences were observed in Bax, Bcl-2, TNF-α, and GFAP expressions in the cerebellum. Treatment of rats with quercetin nanoparticles either before or after treatment with acrolein has been found to preserve the cerebellum tissues from the toxic impacts and oxidative stress induced by acrolein. This may open the door to more nanomedicine studies and a new avenue for employing nanoparticles as a therapeutic intervention in neurodegenerative illnesses.

Quercetin ameliorates nonalcoholic fatty liver disease (NAFLD) via the promotion of AMPK-mediated hepatic mitophagy

The global incidence of nonalcoholic fatty liver disease (NAFLD) has been surging in recent years, however, no drug is currently approved to treat this disease. Quercetin, a natural flavonoid abundant in plants and fruits, has been reported to alleviate NAFLD, however, the exact molecular mechanism remains unclear. This study aims to further elucidate its potential mechanism of action. The beneficial effects and the underlying mechanism of quercetin in alleviating NAFLD were explored both in vitro and in vivo, by employing chemical inhibitors of autophagosomes (3-methyladenine, 3-MA), autolysosomes (chloroquine, CQ), AMPK (Compound C, CC) and SIRT1 (selisistat, EX-527). The levels of intracellular lipids, reactive oxygen species, mitochondria function, autophagy, and mitophagy were assessed by fluorescent labeling and examined using flow cytometry or confocal microscopy. Key protein expressions of autophagy, mitophagy, and inflammation were also determined. In vivo, quercetin was shown to dose-dependently effectively alleviate NAFLD, but intraperitoneal injection of 3-MA could block the beneficial effects of quercetin on body weight, liver weight, serum ALT/AST, hepatic ROS and inflammation. In vitro, quercetin could reduce intracellular lipids (Nile Red staining) and ROS/DHE accumulation, which could be also blocked by 3-MA or CQ. Furthermore, we found that CC could abrogate the protective effects of quercetin on lipid and ROS accumulation in vitro. Also, CC abolished the proautophagic and anti-inflammatory effects of quercetin, as shown by western blot determination and Lyso-Tracker labeling. Importantly, mitophagy, a specific form of mitochondria-targeted autophagy, was enhanced by quercetin, as demonstrated by PINK1/Parkin protein variation and immunofluorescence colocalization of autophagosomes and mitochondria, which could also be blocked by the intervention of CC. This study demonstrates that quercetin prevents NAFLD through AMPK-mediated mitophagy and suggests that promoting mitophagy via an upregulation of AMPK may be a promising therapeutic strategy against NAFLD.

Protective effect of paeoniflorin in diabetic nephropathy: A preclinical systematic review revealing the mechanism of action

BACKGROUND

Paeoniflorin (PF), the main active glucoside of Paeonia Lactiflora, has many pharmacological activities, such as inhibition of vasodilation, hypoglycemia, and immunomodulation. Although the current evidence has suggested the therapeutic effects of PF on diabetic nephropathy (DN), its potential mechanism of action is still unclear.

PURPOSE

A systematic review and meta-analysis of the existing literature on paeoniflorin treatment in DN animal models was performed to evaluate the efficacy and mechanism of PF in DN animal models.

METHODS

The risk of bias in each study was judged using the CAMARADES 10-item quality checklist with the number of criteria met varying from 4 / 10 to 7 / 10, with an average of 5.44. From inception to July 2022, We searched eight databases. We used the Cochrane Collaboration's 10-item checklist and RevMan 5.3 software to assess the risk of bias and analyze the data. Three-dimensional dose/time-effect analyses were conducted to examine the dosage/time-response relations between PF and DN.

RESULTS

Nine animal studies were systematically reviewed to evaluate the effectiveness of PF in improving animal models of DN. Meta-analysis data and intergroup comparisons indicated that PF slowed the index of mesangial expansion and tubulointerstitial injury, 24-h urinary protein excretion rate, expression of anti-inflammatory mediators (mRNA of MCP-1, TNF-α, iNOS, and IL-1 β), and expression of immune downstream factors (P-IRAK1, TIRF, P-IRF3, MyD88, and NF-κBp-p65). Furthermore, modeling methods, animal species, treatment duration, thickness of tissue sections during the experiment, and experimental procedures were subjected to subgroup analyses.

CONCLUSION

The present study demonstrated that the reno-protective effects of PF were associated with its inhibition on macrophage infiltration, reduction of inflammatory mediators, and immunomodulatory effects. In conclusion, PF can effectively slow down the progression of DN and hold promise as a protective drug for the treatment of DN. Due to the low bioavailability of PF, further studies on renal histology in animals are urgently needed. We therefore recommend an active exploration of the dose and therapeutic time frame of PF in the clinic and in animals. Moreover, it is suggested to actively explore methods to improve the bioavailability of PF to expand the application of PF in the clinic.

Integrative evidence construction for resveratrol treatment of nonalcoholic fatty liver disease: preclinical and clinical meta-analyses

Background: Resveratrol, a polyphenol found in various plants, is known for its diverse bioactivities and has been explored in relation to nonalcoholic fatty liver disease (NAFLD). However, no high-quality evidence exists regarding its efficacy. Objective: a meta-analysis was conducted to evaluate the potential efficacy of resveratrol in treating nonalcoholic fatty liver disease by analyzing both preclinical studies and clinical trials. Method: PubMed, Embase and Web of Science were searched for the included literature with the criteria for screening. Quantitative synthesis and meta-analyses were performed by STATA 16.0. Results: Twenty-seven studies were included, and the results indicated that resveratrol effectively improved liver function, reduced fatty liver indicators, and affected other indices in preclinical studies. The effective dosage ranged from 50 mg/kg-200 mg/kg, administered over a period of 4-8 weeks. While there were inconsistencies between clinical trials and preclinical research, both study types revealed that resveratrol significantly reduced tumor necrosis factor-α levels, further supporting its protective effect against nonalcoholic fatty liver disease. Additionally, resveratrol alleviated nonalcoholic fatty liver disease primarily via AMPK/Sirt1 and anti-inflammatory signaling pathways. Conclusion: Current meta-analysis could not consistently verify the efficacy of resveratrol in treating nonalcoholic fatty liver disease, but demonstrated the liver-protective effects on nonalcoholic fatty liver disease. The large-sample scale and single region RCTs were further needed to investigate the efficacy.

Oxidative stress and inflammation in diabetic nephropathy: role of polyphenols

Diabetic nephropathy (DN) often leads to end-stage renal disease. Oxidative stress demonstrates a crucial act in the onset and progression of DN, which triggers various pathological processes while promoting the activation of inflammation and forming a vicious oxidative stress-inflammation cycle that induces podocyte injury, extracellular matrix accumulation, glomerulosclerosis, epithelial-mesenchymal transition, renal tubular atrophy, and proteinuria. Conventional treatments for DN have limited efficacy. Polyphenols, as antioxidants, are widely used in DN with multiple targets and fewer adverse effects. This review reveals the oxidative stress and oxidative stress-associated inflammation in DN that led to pathological damage to renal cells, including podocytes, endothelial cells, mesangial cells, and renal tubular epithelial cells. It demonstrates the potent antioxidant and anti-inflammatory properties by targeting Nrf2, SIRT1, HMGB1, NF-κB, and NLRP3 of polyphenols, including quercetin, resveratrol, curcumin, and phenolic acid. However, there remains a long way to a comprehensive understanding of molecular mechanisms and applications for the clinical therapy of polyphenols.

Natural products in attenuating renal inflammation via inhibiting the NLRP3 inflammasome in diabetic kidney disease

Diabetic kidney disease (DKD) is a prevalent and severe complications of diabetes and serves as the primary cause of end-stage kidney disease (ESKD) globally. Increasing evidence indicates that renal inflammation is critical in the pathogenesis of DKD. The nucleotide - binding oligomerization domain (NOD) - like receptor family pyrin domain containing 3 (NLRP3) inflammasome is the most extensively researched inflammasome complex and is considered a crucial regulator in the pathogenesis of DKD. The activation of NLRP3 inflammasome is regulated by various signaling pathways, including NF- κB, thioredoxin-interacting protein (TXNIP), and non-coding RNAs (ncRNA), among others. Natural products are chemicals extracted from living organisms in nature, and they typically possess pharmacological and biological activities. They are invaluable sources for drug design and development. Research has demonstrated that many natural products can alleviate DKD by targeting the NLRP3 inflammasome. In this review, we highlight the role of the NLRP3 inflammasome in DKD, and the pathways by which natural products fight against DKD via inhibiting the NLRP3 inflammasome activation, so as to provide novel insights for the treatment of DKD.

Alterations in Oxidative Stress Markers and Na,K-ATPase Enzyme Properties in Kidney after Fructose Intake and Quercetin Intervention in Rats

The study aimed to characterize the consequences of a 15-week intake of 10% fructose on the kidney, with the focus on oxidative stress markers and properties of the Na,K-ATPase enzyme. Various antioxidants naturally occurring in common food were demonstrated to be protective against fructose-induced deterioration of kidneys. Therefore, we also aimed to observe the effect of 6-week quercetin administration (20 mg/kg/day) that was initiated following the 9-week period of higher fructose intake, by determining the concentration of sodium, potassium, creatinine, urea, and glucose in blood plasma and oxidative status directly in the renal tissue. Kinetic studies of renal Na,K-ATPase were utilized for a deeper insight into the molecular principles of expected changes in this enzyme activity under conditions of presumed fructose-induced renal injury. Fructose intake led to increase in body weight gain, plasma glucose and sodium levels, and deterioration of kidney properties, although some compensatory mechanisms were observable. Quercetin administration improved glycemic control in rats exposed to fructose overload. However, an increase in plasma creatinine, a decrease in GSH/GSSG ratio in renal tissue homogenate, and a controversial effect on renal Na,K-ATPase enzyme suggest that quercetin treatment may not be beneficial in the condition of pre-existing renal pathology.

Quercetin ameliorates hepatic fat accumulation in high-fat diet-induced obese mice via PPARs

As a natural pigment in food, quercetin possesses multiple biological activities and plays a crucial role in regulating metabolic syndrome. Herein, we aim to explore the potential mechanism of quercetin to ameliorate hepatic fat accumulation. In vivo experiments showed that quercetin significantly relieved inflammation response by decreasing the serum TNF-α and IL-6 levels and also improved high-fat diet-induced hepatic steatosis without other organ injuries. Quercetin can effectively reduce lipid aggregation and down-regulate the protein expression of PCK1 in HepG2 cells induced by oleic acid and palmitic acid, indicating that inhibiting gluconeogenesis leads to hepatic fat accumulation reduction. Furthermore, molecular docking results suggested that quercetin can bind to both PPARα and PPARγ, with an even more potent binding affinity than indeglitazar, a pan-agonist of PPARs. In conclusion, quercetin may regulate gluconeogenesis to ameliorate hepatic fat accumulation via targeting PPARα/γ.

Treatment with quercetin inhibits SARS-CoV-2 N protein-induced acute kidney injury by blocking Smad3-dependent G1 cell-cycle arrest

Increasing evidence shows that SARS-CoV-2 can infect kidneys and cause acute kidney injury (AKI) in critically ill COVID-19 patients. However, mechanisms through which COVID-19 induces AKI are largely unknown, and treatment remains ineffective. Here, we report that kidney-specific overexpressing SARS-CoV-2 N gene can cause AKI, including tubular necrosis and elevated levels of serum creatinine and BUN in 8-week-old diabetic db/db mice, which become worse in those with older age (16 weeks) and underlying diabetic kidney disease (DKD). Treatment with quercetin, a purified product from traditional Chinese medicine (TCM) that shows effective treatment of COVID-19 patients, can significantly inhibit SARS-CoV-2 N protein-induced AKI in diabetic mice with or without underlying DKD. Mechanistically, quercetin can block the binding of SARS-CoV-2 N protein to Smad3, thereby inhibiting Smad3 signaling and Smad3-mediated cell death via the p16-dependent G1 cell-cycle arrest mechanism in vivo and in vitro. In conclusion, SARS-CoV-2 N protein is pathogenic and can cause severe AKI in diabetic mice, particularly in those with older age and pre-existing DKD, via the Smad3-dependent G1 cell-cycle arrest mechanism. Importantly, we identify that quercetin may be an effective TCM compound capable of inhibiting COVID-19 AKI by blocking SARS-CoV-2 N-Smad3-mediated cell death pathway.

Niaoduqing alleviates podocyte injury in high glucose model via regulating multiple targets and AGE/RAGE pathway: Network pharmacology and experimental validation

Purpose: The aim of present study was to explore the pharmacological mechanisms of Niaoduqing granules on the treatment of podocyte injury in diabetic nephropathy (DN) via network pharmacology and experimental validation. Methods: Active ingredients and related targets of Niaoduqing, as well as related genes of podocyte injury, proteinuria and DN, were obtained from public databases. Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and protein-protein interaction (PPI) network analysis were performed to investigate the potential mechanisms. High glucose (HG) -induced MPC5 cell injury model was treated with the major core active ingredients of Niaoduqing and used to validate the predicted targets and signaling pathways. Results: Totally, 16 potential therapeutic targets were identified by intersecting the targets of Niaoduqing and disease, in which 7 of them were considered as the core targets via PPI network analysis. KEGG enrichment analysis showed that AGE-RAGE signaling pathway was identified as the most crucial signaling pathway. The results of in vitro experiments revealed that the treatment of Niaoduqing active ingredients significantly protected MPC5 cells from HG-induced apoptosis. Moreover, Niaoduqing could significantly attenuate the HG-induced activation of AGE-RAGE signaling pathway, whereas inhibited the over-expression of VEGF-A, ICAM-1, PTGS-2 and ACE in HG-induced MPC5 cells. Conclusion: Niaoduqing might protect against podocyte injury in DN through regulating the activity of AGE/RAGE pathway and expression of multiple genes. Further clinical and animal experimental studies are necessary to confirm present findings.

Cyproterone Acetate Mediates IRE1α Signaling Pathway to Alleviate Pyroptosis of Ovarian Granulosa Cells Induced by Hyperandrogen

OBJECTIVE

Hyperandrogenemia (HA) is the main pathophysiological change that takes place in polycystic ovary syndrome (PCOS). Cyproterone acetate (CYA) is a drug commonly used to reduce androgen in patients with PCOS. Long-term and continuous exposure to HA can cause ovarian granulosa cells (GCs), pyroptotic death, and follicular dysfunction in PCOS mice. The aim of this study was to investigate whether CYA could ameliorate the hyperandrogenemia-induced pyroptosis of PCOS ovarian GCs by alleviating the activation of the IRE1α signaling pathway.

METHODS

Firstly, thirty PCOS patients with HA as their main clinical manifestation were selected as the study group, and thirty non-PCOS patients were selected as the control group. The GCs and follicular fluid of the patients were collected, and the expression of pyroptosis-related proteins was detected. Secondly, a PCOS mouse model induced by dehydroepiandrosterone (DHEA) was constructed, and the treatment group model was constructed with the subcutaneous injection of cyproterone acetate in PCOS mice. The expression of pyroptosis-related protein in ovarian GCs was detected to explore the alleviating effect of CYA on the pyroptosis of ovarian GCs in PCOS mice. Thirdly, KGN cells-i.e., from the human GC line-were cultured with dihydrotestosterone, CYA, and ERN1 (IRE1α gene) small interfering RNA in vitro to explore whether CYA can alleviate the activation of the IRE1α signaling pathway and ameliorate the hyperandrogenemia-induced pyroptosis of PCOS ovarian GCs.

RESULTS

The expression of pyroptosis-related proteins was significantly increased in ovarian GCs of PCOS patients with HA as the main clinical manifestation, and in the PCOS mouse model induced by DHEA. After treatment with CYA, the expression of pyroptosis-related proteins in the ovarian GCs of mice was significantly lower than that in PCOS mice. In vitro experiments showed that CYA could ameliorate KGN cells' pyroptosis by alleviating the activation of the IRE1α signaling pathway.

CONCLUSION

This study showed that CYA could ameliorate the activation of the IRE1α signaling pathway in mouse GCs and KGN cells, and also alleviate pyroptosis in ovarian GCs. This study provides a new mechanism and evidential support for CYA in the treatment of PCOS patients.