Phloretin ameliorates hyperuricemia-induced chronic renal dysfunction through inhibiting NLRP3 inflammasome and uric acid reabsorption

Gut microbiota in the association between obesity and kidney function decline: a metagenomics-based study in a rat model

OBJECTIVES

Obesity can induce dysbiosis in the gut microbiota and is considered a separate risk factor for kidney function decline. Nonetheless, the precise function of intestinal microorganisms in facilitating the connection between obesity and kidney function decline remains uncertain. Hence, the objective of this study was to investigate the alterations in the gut microbiota composition that take place during obesity and their correlations with renal function utilizing a rat model.

METHODS

For 20 weeks, 25 Sprague-Dawley rats were fed either a high-fat diet (HFD) or a normal-fat normal diet (ND). Physiological indices, peripheral plasma, kidney tissue, and colon contents were collected for comparison between groups. Metagenomic analysis of intestinal flora was performed.

RESULTS

The HFD group demonstrated significantly increased levels of creatinine and urea nitrogen in the peripheral blood. Additionally, the HFD rats exhibited a significantly larger glomerular diameter compared to the ND group, accompanied by the presence of glomerulosclerosis, tubular vacuolar transformation, and other pathological changes in certain glomeruli. Metagenomics analysis revealed a notable rise in the prevalence of the Firmicutes phylum within the HFD group, primarily comprising the Rumenococcus genus. Functional analysis indicated that the gut microbiota in the HFD group primarily correlated with infectious diseases, signal transduction, and signaling molecules and interactions.

CONCLUSIONS

This study provides evidence that the consumption of a HFD induces modifications in the composition and functionality of the gut microbiome in rats, which may serve as a potential mechanism underlying the relationship between obesity and the progression of kidney function decline.

Natural compound phloretin restores periodontal immune homeostasis via HIF-1α-regulated PI3K/Akt and glycolysis in macrophages

Periodontitis is a chronic inflammatory disease that affects about 45 %-50 % of adults worldwide, but the efficacy of current clinical therapies is unsatisfactory due to the complicated periodontal immune microenvironment. Thus, developing drugs that can regulate innate immune cells (e.g., macrophages) is a potent strategy to treat periodontitis. Here, we report that phloretin, a food plant-derived natural compound, is sufficient to alleviate periodontitis through immune regulation. In vivo, phloretin treatment could significantly reduce alveolar bone resorption and periodontal inflammation in mouse periodontitis models. In vitro, phloretin could suppress proinflammatory (M1-like) polarization and cytokine release in macrophages induced by LPS. Mechanistically, the immune regulatory role of phloretin in macrophages may be due to its metabolic regulation effect. Phloretin might restore the balance of M1/M2 macrophage transition in periodontitis by inhibiting HIF-1α-mediated glycolysis and PI3k/Akt pathways, thereby reducing the proinflammatory effect and immune disorder caused by over-activated M1 macrophages. Together, this study highlights that natural compound, such as phloretin, can restore periodontal immune homeostasis by metabolic regulation of macrophages, which may provide novel insight into the treatment of periodontitis.

Kidney Injury Evoked by Fine Particulate Matter: Risk Factor, Causation, Mechanism and Intervention Study

Fine particulate matter (PM2.5) is suggested to pose a severe risk to the kidneys by inducing functional degradation and chronic kidney diseases (CKD). This study aims to explore the nephrotoxicity of PM2.5 exposure and the underlying mechanism. Herein, based on the UK Biobank, it is found that per interquartile range (IQR) increase in PM2.5 is associated with a 6% (95% CI: 1%-11%), 7% (95% CI: 3%-11%), 9% (95% CI: 4%-13%), 11% (95% CI: 9%-13%), and 10% (95% CI: 8%-12%) increase in the risk of nephritis, hydronephrosis, kidney stone, acute renal failure, and CKD, respectively. In experimental study, noticeable kidney injury, which is the initiation of kidney diseases, is observed with PM2.5 exposure in C57BL/6N mice (n = 8), accompanied with oxidative stress, autophagy and pyroptosis. In vitro, HK-2 cells with PM2.5-stimulation exhibit tubulopathy, increased reactive oxygen species (ROS) generation and activated pyroptosis and autophagy. All changes are abolished by ROS scavenger of N-acetyl-L-cysteine (NAC) both in vivo and in vitro. In conclusion, the study provides evidence showing that PM2.5 exposure is associated with 5 kinds of kidney diseases by directly inducing nephrotoxicity, in which ROS may be the potential target by triggering autophagy and pyroptosis.

Fasudil attenuates oxidative stress-induced partial epithelial-mesenchymal transition of tubular epithelial cells in hyperuricemic nephropathy via activating Nrf2

Anti-partial epithelial-mesenchymal transition (pEMT) treatment of renal tubular epithelial cells (TECs) represents a promising therapeutic approach. Hyperuricemia nephropathy (HN) arises as a consequence of hyperuricemia (HUA)-induced tubulointerstitial fibrosis (TIF). Studies have suggested that the Ras homolog member A (RhoA)/Rho-associated kinase (ROCK) pathway is a crucial signaling transduction system in renal fibrosis. Fasudil, a RhoA/ROCK inhibitor, has exhibited the potential to prevent fibrosis progress. However, its impact on the pEMT of TECs in HN remains unclear. Here, an HN rat model and an uric acid (UA)-stimulated human kidney 2 (HK2) cell model were established and treated with Fasudil to explore its effects. Furthermore, the underlying mechanism of action involved in the attenuation of pEMT in TECs by Fasudil during HN was probed by using multiple molecular approaches. The HN rat model exhibited significant renal dysfunction and histopathological damage, whereas in vitro and in vivo experiments further confirmed the pEMT status accompanied by RhoA/ROCK pathway activation and oxidative stress in tubular cells exposed to UA. Notably, Fasudil ameliorated these pathological changes, and this was consistent with the trend of ROCK silencing in vitro. Mechanistically, we identified the Neh2 domain of nuclear factor erythroid 2-related factor 2 (Nrf2) as a target of Fasudil for the first time. Fasudil targets Nrf2 activation and antagonizes oxidative stress to attenuate the pEMT of TECs in HN. Our findings suggest that Fasudil attenuates oxidative stress-induced pEMT of TECs in HN by targeting Nrf2 activation. Thus, Fasudil is a potential therapeutic agent for the treatment of HN.

The Role of Hyperuricemia in Cardiac Diseases: Evidence, Controversies, and Therapeutic Strategies

Hyperuricemia (HUA) may lead to myocardial cell damage, thereby promoting the occurrence and adverse outcomes of heart diseases. In this review, we discuss the latest clinical research progress, and explore the impact of HUA on myocardial damage-related diseases such as myocardial infarction, arrhythmias, and heart failure. We also combined recent findings from basic research to analyze potential mechanisms linking HUA with myocardial injury. In different pathological models (such as direct action of high uric acid on myocardial cells or combined with myocardial ischemia-reperfusion model), HUA may cause damage by activating the NOD-like receptor protein 3 inflammasome-induced inflammatory response, interfering with cardiac cell energy metabolism, affecting antioxidant defense systems, and stimulating reactive oxygen species production to enhance the oxidative stress response, ultimately resulting in decreased cardiac function. Additionally, we discuss the impact of lowering uric acid intervention therapy and potential safety issues that may arise. However, as the mechanism underlying HUA-induced myocardial injury is poorly defined, further research is warranted to aid in the development novel therapeutic strategies for HUA-related cardiovascular diseases.

Integrated metabolomic and transcriptomic analysis reveals the regulatory mechanisms of flavonoid and alkaloid biosynthesis in the new and old leaves of Murraya tetramera Huang

BACKGROUND

Murraya tetramera Huang is a traditional Chinese woody medicine. Its leaves contain flavonoids, alkaloids, and other active compounds, which have anti-inflammatory and analgesic effects, as well as hypoglycemic and lipid-lowering effects, and anti-tumor effects. There are significant differences in the content of flavonoids and alkaloids in leaves during different growth cycles, but the synthesis mechanism is still unclear.

RESULTS

In April 2021, new leaves (one month old) and old leaves (one and a half years old) of M. tetramera were used as experimental materials to systematically analyze the changes in differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) with transcriptomics and metabolomics technology. This was done to identify the signaling pathways of flavonoid and alkaloid synthesis. The results showed that the contents of total alkaloids and flavonoids in old leaves were significantly higher than those in new leaves. Thirteen flavonoid compounds, three isoflavone compounds, and nineteen alkaloid compounds were identified, and 125 and 48 DEGs related to flavonoid and alkaloid synthesis were found, respectively. By constructing the KEGG (Kyoto Encyclopedia of Genes and Genomes) network of DEGs and DAMs, it was shown that the molecular mechanism of flavonoid biosynthesis in M. tetramera mainly focuses on the "flavonoid biosynthetic pathway" and the "flavonoid and flavonol biosynthetic pathway". Among them, p-Coumaryl alcohol, Sinapyl alcohol, Phloretin, and Isoquercitrin were significantly accumulated in old leaves, the up-regulated expression of CCR (cinnamoyl-CoA reductase) might promote the accumulation of p-Coumaryl alcohol, upregulation of F5H (ferulate-5-hydroxylase) might promote Sinapyl alcohol accumulation. Alkaloids, including indole alkaloids, pyridine alkaloids, imidazole alkaloids, and quinoline alkaloids, were significantly accumulated in old leaves, and a total of 29 genes were associated with these substances.

CONCLUSIONS

These data are helpful to better understand the biosynthesis of flavonoids and alkaloids in M. tetramera and provide a scientific basis for the development of medicinal components in M. tetramera.

Role of mitochondria in pathogenesis and therapy of renal fibrosis

Renal fibrosis, specifically tubulointerstitial fibrosis, represents the predominant pathological consequence observed in the context of progressive chronic kidney conditions. The pathogenesis of renal fibrosis encompasses a multifaceted interplay of mechanisms, including but not limited to interstitial fibroblast proliferation, activation, augmented production of extracellular matrix (ECM) components, and impaired ECM degradation. Notably, mitochondria, the intracellular organelles responsible for orchestrating biological oxidation processes in mammalian cells, assume a pivotal role within this intricate milieu. Mitochondrial dysfunction, when manifest, can incite a cascade of events, including inflammatory responses, perturbed mitochondrial autophagy, and associated processes, ultimately culminating in the genesis of renal fibrosis. This comprehensive review endeavors to furnish an exegesis of mitochondrial pathophysiology and biogenesis, elucidating the precise mechanisms through which mitochondrial aberrations contribute to the onset and progression of renal fibrosis. We explored how mitochondrial dysfunction, mitochondrial cytopathy and mitochondrial autophagy mediate ECM deposition and renal fibrosis from a multicellular perspective of mesangial cells, endothelial cells, podocytes, macrophages and fibroblasts. Furthermore, it succinctly encapsulates the most recent advancements in the realm of mitochondrial-targeted therapeutic strategies aimed at mitigating renal fibrosis.

The roles of pyroptosis in genitourinary diseases

Pyroptosis, a form of programmed cell death distinct from apoptosis and necrosis, is thought to be closely associated with the pathogenesis of diseases. Recently, the association between pyroptosis and urinary diseases has attracted considerable attention, and a comprehensive review focusing on this issue is not available. In this study, we reviewed the role of pyroptosis in the development and progression of benign urinary diseases and urinary malignancies. Based on this, pyroptosis has been implicated in the development of urinary diseases. In summary, this review sheds light on future research directions and provides novel ideas for using pyroptosis as a powerful tool to fight urinary diseases.

Uric acid-lowering effect of harpagoside and its protective effect against hyperuricemia-induced renal injury in mice

Hyperuricemia (HUA) is caused by increased synthesis and/or insufficient excretion of uric acid (UA). Long-lasting HUA may lead to a number of diseases including gout and kidney injury. Harpagoside (Harp) is a bioactive compound with potent anti-inflammatory activity from the roots of Scrophularia ningpoensis. Nevertheless, its potential effect on HUA was not reported. The anti-HUA and nephroprotective effects of Harp on HUA mice were assessed by biochemical and histological analysis. The proteins responsible for UA production and transportation were investigated to figure out its anti-HUA mechanism, while proteins related to NF-κB/NLRP3 pathway were evaluated to reveal its nephroprotective mechanism. The safety was evaluated by testing its effect on body weight and organ coefficients. The results showed that Harp significantly reduced the SUA level and protected the kidney against HUA-induced injury but had no negative effect on safety. Mechanistically, Harp significantly reduced UA production by acting as inhibitors of xanthine oxidase (XOD) and adenosine deaminase (ADA) and decreased UA excretion by acting as activators of ABCG2, OAT1 and inhibitors of GLUT9 and URAT1. Moreover, Harp markedly reduced infiltration of inflammatory cells and down-regulated expressions of TNF-α, NF-κB, NLRP3 and IL-1β in the kidney. Harp was a promising anti-HUA agent.

Phloretamide Protects against Diabetic Kidney Damage and Dysfunction in Diabetic Rats by Attenuating Hyperglycemia and Hyperlipidemia, Suppressing NF-κβ, and Upregulating Nrf2

Potent hypoglycemic and antioxidant effects were recently reported for the apple-derived phenolic compound phloretamide (PLTM). The renoprotective effects of this compound are yet to be shown. This study aimed to examine the potential of PLTM to prevent diabetic nephropathy in streptozotocin-induced diabetic rats and to examine the possible mechanisms of protection. Non-diabetic and STZ-diabetic male rats were treated orally by gavage with either the vehicle or with PTLM (200 mg/kg; twice/week) for 12 weeks. PTLM significantly increased urine volume and prevented glomerular and tubular damage and vacuolization in STZ-diabetic rats. It also increased creatinine excretion and reduced urinary albumin levels and the renal levels of kidney injury molecule-1 (KIM-1), 8-hydroxy-2'-deoxyguanosine (8-OHdG), neutrophil gelatinase-associated lipocalin (NGAL), and nephrin in the diabetic rats. PTLM also prevented an increase in the nuclear levels of NF-κβ, as well as the total levels of tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), caspase-3, and Bax in the kidneys of diabetic rats. These effects were associated with reduced serum levels of triglycerides, cholesterol, and low-density lipoprotein cholesterol. In both the control and diabetic rats, PTLM significantly reduced fasting plasma glucose and enhanced the renal mRNA and cytoplasmic levels of Nrf2, as well as the levels of Bcl2, superoxide dismutase (SOD), and glutathione (GSH). However, PTLM failed to alter the cytoplasmic levels of keap1 in diabetic rats. In conclusion, PTLM prevents renal damage and dysfunction in STZ-diabetic rats through its hypoglycemic and hypolipidemic activities, as well as through its antioxidant potential, which is mediated by activating the Nrf2/antioxidant axis.

Piperine Improves Hyperuricemic Nephropathy by Inhibiting URAT1/GLUT9 and the AKT-mTOR Pathway

Uncontrolled hyperuricemia often leads to the development of hyperuricemic nephropathy (HN), characterized by excessive inflammation and oxidative stress. Piperine, a cinnamic acid alkaloid, possesses various pharmacological activities, such as antioxidant and anti-inflammatory effects. In this study, we intended to investigate the protective effects of piperine on adenine and potassium oxonate-induced HN mice and a uric-acid-induced injury model in renal tubular epithelial cells (mRTECs). We observed that treatment with piperine for 3 weeks significantly reduced serum uric acid levels and reversed kidney function impairment in mice with HN. Piperine (5 μM) alleviated uric acid-induced damage in mRTECs. Moreover, piperine inhibited transporter expression and dose-dependently inhibited the activity of both transporters. The results revealed that piperine regulated the AKT/mTOR signaling pathway both in vivo and in vitro. Overall, piperine inhibits URAT1/GLUT9 and ameliorates HN by inhibiting the AKT/mTOR pathway, making it a promising candidate for patients with HN.

Catalpol ameliorates fructose-induced renal inflammation by inhibiting TLR4/MyD88 signaling and uric acid reabsorption

Accumulating evidence suggests that excess fructose uptake induces metabolic syndrome and kidney injury. Here, we primarily investigated the influence of catalpol on fructose-induced renal inflammation in mice and explored its potential mechanism. Treatment with catalpol improved insulin sensitivity and hyperuricemia in fructose-fed mice. Hyperuricemia induced by high-fructose diet was associated with increases in the expressions of urate reabsorptive transporter URAT1 and GLUT9. Treatment with catalpol decreased the expressions of URAT1 and GLUT9. Futhermore, treatment with catalpol ameliorated renal inflammatory cell infiltration and podocyte injury, and these beneficial effects were associated with inhibiting the production of inflammatory cytokines including IL-1β, IL-18, IL-6 and TNF-α. Moreover, fructose-induced uric acid triggers an inflammatory response by activiting NLRP3 inflammasome, which then processes pro-inflammatory cytokines. Treatment with catalpol could inhibit the activation of NLRP3 inflammasome as well. Additionally, TLR4/MyD88 signaling was activated in fructose-fed mice, while treatment with catalpol inhibited this activation along with promoting NF-κB nuclear translocation in fructose-fed mice. Thus, our study demonstrated that catalpol could ameliorate renal inflammation in fructose-fed mice, attributing its beneficial effects to promoting uric acid excretion and inhibit the activation of TLR4/MyD88 signaling.

Hesperitin-Copper(II) Complex Regulates the NLRP3 Pathway and Attenuates Hyperuricemia and Renal Inflammation

BACKGROUND

Hyperuricaemia (HUA) is a disorder of purine metabolism in the body. We previously synthesized a hesperitin (Hsp)-Cu(II) complex and found that the complex possessed strong uric acid (UA)-reducing activity in vitro. In this study we further explored the complex's UA-lowering and nephroprotective effects in vivo.

METHODS

A mouse with HUA was used to investigate the complex's hypouricemic and nephroprotective effects via biochemical analysis, RT-PCR, and Western blot.

RESULTS

Hsp-Cu(II) complex markedly decreased the serum UA level and restored kidney tissue damage to normal in HUA mice. Meanwhile, the complex inhibited liver adenosine deaminase (ADA) and xanthine oxidase (XO) activities to reduce UA synthesis and modulated the protein expression of urate transporters to promote UA excretion. Hsp-Cu(II) treatment significantly suppressed oxidative stress and inflammatory in the kidney, reduced the contents of cytokines and inhibited the activation of the nucleotide-binding oligomerization domain (NOD)-like receptor thermal protein domain associated protein 3 (NLRP3) inflammatory pathway.

CONCLUSIONS

Hsp-Cu(II) complex reduced serum UA and protected kidneys from renal inflammatory damage and oxidative stress by modulating the NLRP3 pathway. Hsp-Cu(II) complex may be a promising dietary supplement or nutraceutical for the therapy of hyperuricemia.

Fuling-Zexie formula attenuates hyperuricemia-induced nephropathy and inhibits JAK2/STAT3 signaling and NLRP3 inflammasome activation in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Fuling-Zexie (FZ) formula, a traditional Chinese herbal prescription composed of Poria cocos (Schwan.) Wolf. (Poria), Pueraria lobate (Willd.) Howe. (Puerariae Lobatae Radix), Alisma orientale (Sam.) Julep. (Alismatis Rhizoma), and Atractylodes lancea (Thunb.) Dc. (Atractylodis Rhizoma), has been clinically used to ameliorate hyperuricemia (HUA) and its associated renal injury.

AIM OF STUDY

This study aims to explore the action and mechanism of FZ on renal inflammation and dysfunction caused by HUA.

MATERIALS AND METHODS

FZ was orally administered to rapid HUA mouse induced by potassium oxonate (PO) and hypoxanthine (HX) for 7 days. Serum levels of uric acid (UA), creatinine (CRE), blood urea nitrogen (BUN), xanthine oxidase (XOD), adenosine deaminase (ADA), alanine aminotransferase (ALT), aspartate aminotransferase (AST), urine levels of UA, CRE and urinary albumin were determined by biochemical assays. Serum levels of interleukin (IL)-1β and IL-6 were tested by ELISA. Hematoxylin-eosin and Masson staining were used to examine kidney and liver histopathological alterations. The expressions of renal glucose transporter 9 (GLUT9), ATP-binding cassette subfamily G member 2 (ABCG2), organic anion transporter 1 (OAT1), phospho-janus kinase 2 (p-JAK2), p-signal transducer and activator of transcription 3 (p-STAT3), suppression of cytokine signaling 3 (SOCS3), NLR family pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein (ASC), and cleaved-cysteinyl aspartate specific proteinase-1 (cleaved-Cas-1) were detected by western blots. The potential protein targets and pathways of FZ intervention on HUA were predicted by network pharmacology. The constituents in FZ aqueous extract were analyzed by UPLC-MS.

RESULTS

FZ reduced serum UA, CRE, BUN, and urinary albumin and increased urine UA, CRE levels in HUA mice. In addition, the treatment with FZ to HUA mice inhibited the elevated serum levels of XOD and ADA, and regulated renal urate transports including OAT1, GLUT9 and ABCG2. FZ also attenuated kidney inflammation and fibrosis and downregulated the expressions of IL-1β, p-JAK2, p-STAT3, SOCS3, IL-6, NLRP3, ASC, and cleaved-Cas-1. Thirteen compounds were identified in the FG, including L-phenylalanine, D-tryptophan, 3'-hydroxypuerarin, Puerarin, 3'-Methoxy Puerarin, Daidzin, Pueroside A, formononetin-8-C- [xylosyl (1→6)]-glucoside, Ononin, Alisol I 23-acetate, 16-oxo-alisol A, Alisol C and Alisol A.

CONCLUSION

FZ inhibits serum UA generation and promotes urine UA excretion as well as attenuates kidney inflammation and fibrosis in HUA mouse with nephropathy. The underlying mechanism of its action may be associated with suppression of the JAK2/STAT3 signaling pathway and NLRP3 inflammasome activation. This formula may offer a novel source for developing anti-HUA drugs.

Phloretin targets SIRT1 to alleviate oxidative stress, apoptosis, and inflammation in deep venous thrombosis

Deep vein thrombosis (DVT) is a type of venous thromboembolism posing a serious threat to health on a global scale. Phloretin is a potential natural product that has a variety of pharmacological activities. Besides, some Chinese medicines reported that deacetylase sirtuin (SIRT)1 treats DVT by anti-inflammatory and anti-platelet production. However, the specific binding targets and binding modes have not been elaborated. The present study was to investigate whether phloretin attenuates DVT in model rats and oxidized low‑density lipoprotein (ox‑LDL) induced human umbilical vein endothelial cells (HUVECs), and to explore its potential target. The results revealed that the treatment of phloretin, especially pretreatment of it elevated tissue plasminogen activator (t-PA), superoxide dismutase (SOD), prothrombin time (PT), thrombin time (TT), activated partial thromboplastin time (APTT), and cell apoptosis proteins whereas it suppressed plasminogen activator inhibitor (PAI), malondialdehyde (MDA), reactive oxygen species (ROS), fibrinogen (FIB) in DVT rats and cells. Concurrently, phloretin inhibited collagen type I alpha 1 (COL1A1), transforming growth factor-β1 (TGF-β1), and inflammatory factors while it enhanced nuclear factor erythroid 2-related factor 2 (Nrf-2), heme oxygenase 1 (HO-1). In addition, 20 μM phloretin exerted powerful effective protection in HUVECs with DVT model. Later, the surface plasmon resonance (SPR) confirmed that phloretin has a high affinity with SIRT1. Furthermore, siRNA-SIRT1 transfection abolished the protective effect of phloretin against ox‑LDL‑induced DVT in HUVECs, indicating that phloretin targets SIRT1 to alleviate oxidative stress, cell apoptosis, and inflammation in DVT rats and HUVECs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43188-023-00207-y.

Injectable Multifunctional Composite Hydrogel as a Combination Therapy for Preventing Postsurgical Adhesion

Postsurgical adhesion (PA) is a common and serious postoperative complication that affects millions of patients worldwide. However, current commercial barrier materials are insufficient to inhibit diverse pathological factors during PA formation, and thus, highly bioactive materials are needed. Here, this work designs an injectable multifunctional composite hydrogel that can serve as a combination therapy for preventing PA. In brief, this work reveals that multiple pathological events, such as chronic inflammatory and fibrotic processes, contribute to adhesion formation in vivo, and such processes can not be attenuated by barrier material (e.g., hydrogel) alone treatments. To solve this limitation, this work designs a composite hydrogel made of the cationic self-assembling peptide KLD2R and TGF-β receptor inhibitor (TGF-βRi)-loaded mesenchymal stem cell-derived nanovesicles (MSC-NVs). The resulting composite hydrogel displays multiple functions, including physical separation of the injured tissue areas, antibacterial effects, and local delivery and sustained release of anti-inflammatory MSC-NVs and antifibrotic TGF-βRi. As a result, this composite hydrogel effectively inhibited local inflammation, fibrosis and adhesion formation in vivo. Moreover, the hydrogel also exhibits good biocompatibility and biodegradability in vivo. Together, the results highlight that this "all-in-one" composite hydrogel strategy may provide insights into designing advanced therapies for many types of tissue injury.

Shizhifang ameliorates pyroptosis of renal tubular epithelial cells in hyperuricemia through inhibiting NLRP3 inflammasome

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese Medicine (TCM) Compound Shizhifang (SZF), consisting of the seeds of four Chinese herbs, has been used in Shanghai Shuguang Hospital in China for more than 20 years and has proven its clinical safety and efficacy in lowering uric acid and protecting kidney function.

AIM OF THE STUDY

Hyperuricemia (HUA)-induced pyroptosis of renal tubular epithelial cells serves as a significant cause of tubular damage. SZF proves to be effective in alleviating renal tubular injury and inflammation infiltration of HUA. However, the inhibiting effect of SZF on pyroptosis in HUA still remains elusive. This study aims to verify whether SZF could ameliorate pyroptosis in tubular cells induced by uric acid (UA).

MATERIALS AND METHODS

Quality control analysis and chemical and metabolic identification for SZF and SZF drug serum were performed by using UPLC-Q-TOF-MS. In vitro, human renal tubular epithelial cells (HK-2) stimulated by UA were treated with SZF or NLRP3 inhibitor (MCC950). HUA mouse models were induced by intraperitoneal injection of potassium oxonate (PO). Mice were treated with SZF, allopurinol or MCC950. We focused on evaluated the effect of SZF on the NLRP3/Caspase-1/GSDMD pathway, renal function, pathologic structure and inflammation.

RESULTS

SZF significantly restrained the activation of the NLRP3/Caspase-1/GSDMD pathway in vitro and in vivo induced by UA. SZF was better than allopurinol and MCC950 in reducing pro-inflammatory cytokine levels, attenuating tubular inflammatory injury, inhibiting interstitial fibrosis and tubular dilation, maintaining tubular epithelial cell function, and protecting kidney. Furthermore, 49 chemical compounds of SZF and 30 metabolites in serum after oral administration were identified.

CONCLUSIONS

SZF inhibits UA-induced renal tubular epithelial cell pyroptosis via by targeting NLRP3 to inhibit tubular inflammatory and prevent the progression of HUA-induced renal injury effectively.

Double Emulsion-Mediated Delivery of Polyphenol Mixture Alleviates Atopic Dermatitis

Although the polyphenols have been studied to alleviate inflammation, there are still challenges to delivering the polyphenols with stabilized formulation due to their low water solubility and susceptibility to oxidation. Herein, the transdermal delivery system of polyphenol mixture (PM), including quercetin (Q), phloretin (P), and ellagic acid (E), is developed using double emulsion for applying to atopic dermatitis (AD). Through the in vitro anti-degranulation assay, the optimal molar ratio of each polyphenol (Q:P:E = 5:1:1) is obtained, and the PM shows at most a 43.6% reduction of degranulation of immune cells, which is the primary factor of AD. Moreover, the water-in-oil-in-water double emulsion (W/O/W) enhances the PM's stability and has a higher anti-degranulation effect than the oil-in-water emulsion (O/W). In the in vivo 1-chloro-2,4-dinitrobenzene (DNCB)-induced mice AD model, PM reduces more AD symptoms than every single polyphenol. The PM-encapsulated W/O/W (PM_W/O/W) shows the most effectiveness in AD by decreasing dermatitis score, i.e., skin/ear thickness, mast cells, and serum IgE level. Finally, this suggests that the findings on the optimal ratio of PM and double emulsion-based delivery would be beneficial in treating AD and can be applied to other allergic diseases.

NLRP3 inhibitors: Unleashing their therapeutic potential against inflammatory diseases

The NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome has been linked to the release of pro-inflammatory cytokines and is essential for innate defence against infection and danger signals. These secreted cytokines improve the inflammatory response caused by tissue damage and associated inflammation. Consequently, the development of NLRP3 inflammasome inhibitors are viable option for the treatment of diverse inflammatory disorders. The significant anti-inflammatory effects of the NLRP3 inhibitors have severe side effects. Hence, the application of NLRP3 inhibitors against inflammatory disease has not yet been understood and most of the developed inhibitors are unsuccessful in clinical trials. The processes behind the NLRP3 complex, priming, and activation are the main emphasis of this review, which also covers therapeutical inhibitors of the NLRP3 inflammasome and potential therapeutic strategies for directing the NLRP3 inflammasome towards clinical development.

Phloretin alleviates doxorubicin-induced cardiotoxicity through regulating Hif3a transcription via targeting transcription factor Fos

BACKGROUND

Doxorubicin (Dox), a chemotherapeutic agent known for its efficacy, has been associated with the development of severe cardiotoxicity, commonly referred to as doxorubicin-induced cardiotoxicity (DIC). The role and mechanism of action of phloretin (Phl) in cardiovascular diseases are well-established; however, its specific function and underlying mechanism in the context of DIC have yet to be fully elucidated.

OBJECTIVE

This research aimed to uncover the protective effect of Phl against DIC in vivo and in vitro, while also providing a comprehensive understanding of the underlying mechanisms involved.

METHODS

DIC cell and murine models were established. The action targets and mechanism of Phl against DIC were comprehensively examined by systematic network pharmacology, molecular docking, transcriptomics technologies, transcription factor (TF) prediction, and experimental validation.

RESULTS

Phl relieved Dox-induced cell apoptosis in vitro and in vivo. Through network pharmacology analysis, a total of 554 co-targeted genes of Phl and Dox were identified. Enrichment analysis revealed several key pathways including the PI3K-Akt signaling pathway, Apoptosis, and the IL-17 signaling pathway. Protein-protein interaction (PPI) analysis identified 24 core co-targeted genes, such as Fos, Jun, Hif1a, which were predicted to bind well to Phl based on molecular docking. Transcriptomics analysis was performed to identify the top 20 differentially expressed genes (DEGs), and 202 transcription factors (TFs) were predicted for these DEGs. Among these TFs, 10 TFs (Fos, Jun, Hif1a, etc.) are also the co-targeted genes, and 3 TFs (Fos, Jun, Hif1a) are also the core co-targeted genes. Further experiments validated the finding that Phl reduced the elevated levels of Hif3a (one of the top 20 DEGs) and Fos (one of Hif3a's predicted TFs) induced by Dox. Moreover, the interaction between Fos protein and the Hif3a promoter was confirmed through luciferase reporter assays.

CONCLUSION

Phl actively targeted and down-regulated the Fos protein to inhibit its binding to the promoter region of Hif3a, thereby providing protection against DIC.

Phloretin ameliorates heart function after myocardial infarction via NLRP3/Caspase-1/IL-1β signaling

OBJECTIVES/AIMS

Inflammation is crucial in structural and electrical remodeling after myocardial infarction (MI), affecting cardiac pump function and conduction pathways. Phloretin possesses an anti-inflammation role by inhibiting the NLRP3/Caspase-1/IL-1β pathway. However, the effects of Phloretin on cardiac contractile and electrical conduction function after MI remained unclear. Therefore, we aimed to investigate the potential role of Phloretin in a rat model of MI.

METHODS

Rats were assigned into four groups: Sham, Sham+Phloretin, MI and MI+Phloretin, with ad libitum food and water. In the MI and MI+Phloretin groups, the left anterior descending coronary artery was occluded for 4 weeks, while the Sham and Sham+Phloretin groups received sham operation. The Sham+Phloretin group and the MI+Phloretin group received oral administration of Phloretin. In vitro, H9c2 cells were subjected to hypoxic conditions to simulate an MI model, with Phloretin for 24 h. Cardiac electrophysiological properties were assessed following MI, including the effective refractory period (ERP), action potential duration (APD)90 and ventricular fibrillation (VF) incidence. Echocardiography evaluated left ventricular ejection fraction (LVEF), left ventricular fraction shortening (LVFS), left ventricular internal diameter at end-diastole (LVIDd), left ventricular internal diameter at end-systole (LVIDs), left ventricular end-systolic volume (LVESV) and left ventricular end-diastolic volume (LVEDV) to assess cardiac function. Serum type B natriuretic peptide (BNP) level was applied to evaluate the degree of Heart failure (HF). The fibrosis area and severity were assessed by Masson staining and protein expression levels of collagen 3, collagen 1, TGF-β and α-SMA. Western blot analysis estimated the protein expression levels of NLRP3, Pro Caspase-1, Caspase-1, ASC, IL-18, IL-1β, pp38, p38, and Connexin43(Cx43) to elucidate the influence of inflammation on electrical remodeling after MI.

RESULTS

Our findings demonstrate that Phloretin inhibits the NLRP3/Caspase-1/IL-1β pathway, leading to the upregulation of Cx43 by limiting p38 phosphorylation, which further decreases susceptibility to ventricular arrhythmias (VAs). Additionally, Phloretin attenuated fibrosis by inhibiting inflammation to prevent HF. In vitro experiments also provided strong evidence supporting the inhibitory effects of Phloretin on the NLRP3/Caspase-1/IL-1β pathway.

CONCLUSION

Our results suggest that Phloretin could suppress the NLRP3/Caspase-1/IL-1β pathway to reverse structural and electrical remodeling after MI to prevent the occurrence of VAs and HF.

Possible correlated signaling pathways with chronic urate nephropathy: A review

Hyperuricemia nephropathy, also known as gouty nephropathy, refers to renal damage induced by hyperuricemia caused by excessive production of serum uric acid or low excretion of uric acid. the persistence of symptoms will lead to changes in renal tubular phenotype and accelerate the progress of renal fibrosis. The existence and progressive aggravation of symptoms will bring a heavy burden to patients, their families and society, affect their quality of life and reduce their well-being. With the increase of reports on hyperuricemia nephropathy, the importance of related signal pathways in the pathogenesis of hyperuricemia nephropathy is becoming more and more obvious, but most studies are limited to the upper and lower mediating relationship between 1 or 2 signal pathways. The research on the comprehensiveness of signal pathways and the breadth of crosstalk between signal pathways is limited. By synthesizing the research results of signal pathways related to hyperuricemia nephropathy in recent years, this paper will explore the specific mechanism of hyperuricemia nephropathy, and provide new ideas and methods for the treatment of hyperuricemia nephropathy based on a variety of signal pathway crosstalk and personal prospects.

Pyroptosis in renal inflammation and fibrosis: current knowledge and clinical significance

Pyroptosis is a novel inflammatory form of regulated cell death (RCD), characterized by cell swelling, membrane rupture, and pro-inflammatory effects. It is recognized as a potent inflammatory response required for maintaining organismal homeostasis. However, excessive and persistent pyroptosis contributes to severe inflammatory responses and accelerates the progression of numerous inflammation-related disorders. In pyroptosis, activated inflammasomes cleave gasdermins (GSDMs) and generate membrane holes, releasing interleukin (IL)-1β/18, ultimately causing pyroptotic cell death. Mechanistically, pyroptosis is categorized into caspase-1-mediated classical pyroptotic pathway and caspase-4/5/11-mediated non-classical pyroptotic pathway. Renal fibrosis is a kidney disease characterized by the loss of structural and functional units, the proliferation of fibroblasts and myofibroblasts, and extracellular matrix (ECM) accumulation, which leads to interstitial fibrosis of the kidney tubules. Histologically, renal fibrosis is the terminal stage of chronic inflammatory kidney disease. Although there is a multitude of newly discovered information regarding pyroptosis, the regulatory roles of pyroptosis involved in renal fibrosis still need to be fully comprehended, and how to improve clinical outcomes remains obscure. Hence, this review systematically summarizes the novel findings regarding the role of pyroptosis in the pathogenesis of renal fibrosis and discusses potential biomarkers and drugs for anti-fibrotic therapeutic strategies.

Association between dietary intake of flavonoids and hyperuricemia: a cross-sectional study

BACKGROUND

Previous research has demonstrated flavonoid intake was closely related to hyperuricemia. The purpose of this study was to examine whether flavonoid intake was associated with serum uric acid and hyperuricemia in U.S. adults.

METHODS

The study sample consisted of 8,760 participants enrolled in the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2010. Flavonoid consumption was measured using a two-day recall questionnaire on dietary intake. Hyperuricemia was defined based on the serum uric acid levels, determined as ≥ 7 mg/dL for males and ≥ 6 mg/dL for females. The study utilized multivariate linear regression to determine the correlation between flavonoid consumption and serum uric acid levels. Additionally, analyses involving multivariate logistic regression and restricted cubic splines (RCS) were conducted to evaluate the potential link between flavonoid consumption and hyperuricemia. All analyses were adjusted for possible confounding variables.

RESULTS

The study revealed a negative correlation between serum uric acid levels and elevated levels of anthocyanidins and flavanones, with significant p-trends of < 0.001 and 0.02 respectively. The multivariate analysis showed that anthocyanidins and flavanones intake had a significant negative association with the risk of hyperuricemia, with p-trend value being < 0.001 and 0.01, respectively. Flavan-3-ols, flavonols, and all flavonoids exhibited a non-linear association with the incidence of hyperuricemia, with significant p-nonlinear values of < 0.001, 0.04, and 0.01 respectively.

CONCLUSION

Our study demonstrated that individuals who follow a diet rich in anthocyanins and flavanones had significantly lower serum uric acid levels and a lower incidence of hyperuricemia.

Chloroquine inhibits NLRP3 inflammasomes activation and alleviates renal fibrosis in mouse model of hyperuricemic nephropathy with aggravation by a high-fat-diet

Numerous epidemiological studies have demonstrated that hyperuricemia (HUA) is a risk factor for renal diseases and renal fibrosis. Dietary patterns can influence serum urate levels and hyperuricemic nephropathy (HN). NLRP3 inflammasomes play a crucial role in various inflammatory responses and contribute to HN progression. Chloroquine (CQ) is an anti-inflammatory and disease-modifying anti-rheumatic drug (DMARD) utilized in treating autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. In this study, we examined the effects and underlying mechanisms of CQ in a high-fat-diet (HFD) exacerbated mouse model of HN. C57BL/6 mice were randomized into either a control group or an HN group (induced by adenine/potassium oxonate treatment), followed by a normal diet or HFD, with or without CQ treatment. Our findings revealed that the HN group exhibited elevated serum levels of blood urea nitrogen (BUN) and creatinine compared to the control group. Additionally, the HN + HFD group displayed increased serum levels of uric acid, BUN, and creatinine relative to the control + HFD group. Moreover, the HFD exacerbated renal uric acid crystal deposition and fibrosis in HN mice compared to a normal diet. CQ ameliorated renal dysfunction, as evidenced by reduced serum creatinine levels, renal fibrosis, and renal tubular injury scores, and significantly decreased NLRP3, ASC, caspase-1, and IL-1β levels in HN mice. These findings suggest that CQ inhibits the activation of NLRP3 inflammasomes and may serve as a potential therapeutic strategy for HN treatment.

A Non-Immunized and BSA-Template Aggregation-Induced Emission Sensor for Noninvasive Detection of Cystatin C in the Clinical Diagnosis of Diabetes Nephropathy

Diabetes nephropathy (DN) is one of the main causes of death in patients with diabetes. Cystatin C (Cys C) is a reliable indicator of glomerular filtration function. Therefore, it is urgent and meaningful to obtain early warning of DN by noninvasive measurement of Cys C. In this investigation, a novel fluorescence sensor (BSA-AIEgen sensor) was synthesized by cross-linking the aggregation-induced emission (AIE) characteristics of 2-(4-bromophenyl)-3-(4-(4-(diphenylamino) styryl) phenyl) fumaronitrile (TPABDFN) and bovine serum albumin (BSA), which exhibited the "On" state owing to the restriction of the intramolecular motions (RIM) phenomenon of TPABDFN. Intriguingly, a decrease in fluorescence of BSA-AIEgen sensors could be found owing to BSA on the surface of BSA-AIEgen sensor hydrolyzed by papain, but a reverse phenomenon emerged with the increase of Cys C content as the inhibitor of papain. Hence, Cys C was successfully detected by employing the fluorescent differential display and the linear range was from 12.5 ng/mL to 800 ng/mL (R² = 0.994) with the limit of detection (LOD) of 7.10 ng/mL (S/N = 3). Further, the developed BSA-AIEgen sensor successfully differentiates patients with diabetes nephropathy from volunteers with the advantages of high specificity, low cost, and simple operation. Accordingly, it is expected to become a non-immunized method to monitor Cys C for the early warning, noninvasive diagnosis, and drug efficacy evaluation of diabetes nephropathy.

Effectiveness of targeting the NLRP3 inflammasome by using natural polyphenols: A systematic review of implications on health effects

Globally, inflammation and metabolic disorders pose serious public health problems and are major health concerns. It has been shown that natural polyphenols are effective in the treatment of metabolic diseases, including anti-inflammation, anti-diabetes, anti-obesity, neuron-protection, and cardio-protection. NLRP3 inflammasome, which are multiprotein complexes located within the cytosol, play an important role in the innate immune system. However, aberrant activation of the NLRP3 inflammasome were discovered as essential molecular mechanisms in triggering inflammatory processes as well as implicating it in several major metabolic diseases, such as type 2 diabetes mellitus, obesity, atherosclerosis or cardiovascular disease. Recent studies indicate that natural polyphenols can inhibit NLRP3 inflammasome activation. In this review, the progress of natural polyphenols preventing inflammation and metabolic disorders via targeting NLRP3 inflammasome is systemically summarized. From the viewpoint of interfering NLRP3 inflammasome activation, the health effects of natural polyphenols are explained. Recent advances in other beneficial effects, clinical trials, and nano-delivery systems for targeting NLRP3 inflammasome are also reviewed. NLRP3 inflammasome is targeted by natural polyphenols to exert multiple health effects, which broadens the understanding of polyphenol mechanisms and provides valuable guidance to new researchers in this field.

Naringenin Ameliorates Hyperuricemia by Regulating Renal Uric Acid Excretion via the PI3K/AKT Signaling Pathway and Renal Inflammation through the NF-κB Signaling Pathway

Hyperuricemia characterized by high serum levels of uric acid (UA, >6.8 mg/dL) is regarded as a common chronic metabolic disease. When used as a food supplement, naringenin might have various pharmacological activities, including antioxidant, free-radical-scavenging, and inflammation-suppressing activities. However, the effects of naringenin on hyperuricemia and renal inflammation and the underlying mechanisms remain to be elucidated. Here, we comprehensively examined the effects of naringenin on hyperuricemia and the attenuation of renal impairment. Mice were injected with 250 mg/kg of potassium oxonate (PO) and given 5% fructose water to induce hyperuricemia. The pharmacological effects of naringenin (10 and 50 mg/kg) and benzbromarone (positive control group, 20 mg/kg) on hyperuricemic mice were evaluated in vivo. The disordered expression of urate transporters in HK-2 cells was stimulated by 8 mg/dL UA, which was used to determine the mechanisms underlying the effects of naringenin in vitro. Naringenin markedly reduced the serum UA level in a dose-dependent manner and improved renal dysfunction. Moreover, the increased elimination of UA in urine showed that the effects of naringenin were associated with the regulation of renal excretion. Further examination indicated that naringenin reduced the expression of GLUT9 by inhibiting the PI3K/AKT signaling pathway and reinforced the expression of ABCG2 by increasing the abundance of PDZK1 in vivo and in vitro. Furthermore, sirius red staining and western blotting indicated that naringenin plays a protective role in renal injury by suppressing increases in the levels of pro-inflammatory cytokines, including IL-6 and TNF-α, which contribute to the inhibition of the TLR4/NF-κB signaling pathway in vivo and in vitro. Naringenin supplementation might be a potential therapeutic strategy to ameliorate hyperuricemia by promoting UA excretion in the kidney and attenuating the inflammatory response by decreasing the release of inflammatory cytokines. This study shows that naringenin could be used as a functional food or dietary supplement for hyperuricemia prevention and treatment.

Protective effect of natural products in the metabolic-associated kidney diseases via regulating mitochondrial dysfunction

Metabolic syndrome (MS) is a complex group of metabolic disorders syndrome with hypertension, hyperuricemia and disorders of glucose or lipid metabolism. As an important organ involved in metabolism, the kidney is inevitably attacked by various metabolic disorders, leading to abnormalities in kidney structure and function. Recently, an increasing number of studies have shown that mitochondrial dysfunction is actively involved in the development of metabolic-associated kidney diseases. Mitochondrial dysfunction can be used as a potential therapeutic strategy for the treatment of metabolic-associated kidney diseases. Many natural products have been widely used to improve the treatment of metabolic-associated kidney diseases by inhibiting mitochondrial dysfunction. In this paper, by searching several authoritative databases such as PubMed, Web of Science, Wiley Online Library, and Springer Link. We summarize the Natural Products Protect Against Metabolic-Associated Kidney Diseases by Regulating Mitochondrial Dysfunction. In this review, we sought to provide an overview of the mechanisms by which mitochondrial dysfunction impaired metabolic-associated kidney diseases, with particular attention to the role of mitochondrial dysfunction in diabetic nephropathy, gouty nephropathy, hypertensive kidney disease, and obesity-related nephropathy, and then the protective role of natural products in the kidney through inhibition of mitochondrial disorders, thus providing a systematic understanding of the targets of mitochondrial dysfunction in metabolic-associated kidney diseases, and finally a review of promising therapeutic targets and herbal candidates for metabolic-associated kidney diseases through inhibition of mitochondrial dysfunction.

Study on the mechanism of Phellinus igniarius total flavonoids in reducing uric acid and protecting uric acid renal injury in vitro

Background

Uric acid nephropathy (UN) is a complication of hyperuricemia (HUA), which has a great impact on people's lives. Here, we evaluated the therapeutic potential of total flavonoids of Phellinus igniarius (TFPI) in vivo and studied the anti UN effect of TFPI in vitro.

Methods

Hyperuricemia was induced by intraperitoneal injection of potassium oxonate in ICR mice. After intervention with TFPI, we evaluated the levels of serum uric acid (UA) and creatinine (CR), and the contents of xanthine oxidase (XOD) and adenosine deaminase (ADA) in liver. To explore the effect and molecular mechanism of TFPI on UN, we treated HK-2 cells with monosodium urate (MSU) to study the effect of TFPI on apoptosis and inflammation. In addition, to explore the mechanism of TFPI on uric acid transport we evaluated the relationship between uric acid transporter ABCG2 and inflammatory signaling pathway TLR4-NLRP3.

Results

In the model mice, TFPI significantly decreased the levels of UA and Cr, which may be related to the inhibition of XOD enzyme activity. In HK-2 cells, the response of TFPI to MSU can effectively inhibit apoptosis and activation of TLR4-NLRP3 signaling pathway and promote the expression of ABCG2.

Conclusions

TFPI can significantly inhibit the release of inflammatory factors and promote the expression of ABCG2 by targeting TLR4 receptor and NLRP3 inflammasome. And targeted inhibition of XOD enzyme activity to reduce uric acid level and inhibit the development of UN.

The Molecular Pharmacology of Phloretin: Anti-Inflammatory Mechanisms of Action

The isolation of phlorizin from the bark of an apple tree in 1835 led to a flurry of research on its inhibitory effect on glucose transporters in the intestine and kidney. Using phlorizin as a prototype drug, antidiabetic agents with more selective inhibitory activity towards glucose transport at the kidney have subsequently been developed. In contrast, its hydrolysis product in the body, phloretin, which is also found in the apple plant, has weak antidiabetic properties. Phloretin, however, displays a range of pharmacological effects including antibacterial, anticancer, and cellular and organ protective properties both in vitro and in vivo. In this communication, the molecular basis of its anti-inflammatory mechanisms that attribute to its pharmacological effects is scrutinised. These include inhibiting the signalling pathways of inflammatory mediators' expression that support its suppressive effect in immune cells overactivation, obesity-induced inflammation, arthritis, endothelial, myocardial, hepatic, renal and lung injury, and inflammation in the gut, skin, and nervous system, among others.

Folic Acid Protects against Hyperuricemia in C57BL/6J Mice via Ameliorating Gut-Kidney Axis Dysfunction

Emerging lines of research evidence point to a vital role of gut-kidney axis in the development of hyperuricemia (HUA), which has been identified as an increasing burden worldwide due to the high prevalence. The involved crosstalk which links the metabolic and immune-related pathways is mainly responsible for maintaining the axial homeostasis of uric acid (UA) metabolism. Nowadays, the urate-lowering drugs only aim to treat acute gouty arthritis as a result of their controversial clinical application in HUA. In this study, we established the HUA model of C57BL/6J mice to evaluate the effectiveness of folic acid on UA metabolism and further explored the underlying mechanisms. Folic acid attenuated the kidney tissue injury and excretion dysfunction, as well as the typical fibrosis in HUA mice. Molecular docking results also revealed the structure-activity relationship of the folic acid metabolic unit and the UA transporters GLUT9 and URAT1, implying the potential interaction. Also, folic acid alleviated HUA-induced Th17/Treg imbalance and intestinal tissue damage and inhibited the active state of the TLR4/NF-κB signaling pathway, which is closely associated with the circulating LPS level caused by the impaired intestinal permeability. Furthermore, the changes of intestinal microecology induced by HUA were restored by folic acid, including the alteration in the structure and species composition of the gut microbiome community, and metabolite short-chain fatty acids. Collectively, this study revealed that folic acid intervention exerted improving effects on HUA by ameliorating gut-kidney axis dysfunction.

New insight into the management of renal excretion and hyperuricemia: Potential therapeutic strategies with natural bioactive compounds

Hyperuricemia is the result of increased production and/or underexcretion of uric acid. Hyperuricemia has been epidemiologically associated with multiple comorbidities, including metabolic syndrome, gout with long-term systemic inflammation, chronic kidney disease, urolithiasis, cardiovascular disease, hypertension, rheumatoid arthritis, dyslipidemia, diabetes/insulin resistance and increased oxidative stress. Dysregulation of xanthine oxidoreductase (XOD), the enzyme that catalyzes uric acid biosynthesis primarily in the liver, and urate transporters that reabsorb urate in the renal proximal tubules (URAT1, GLUT9, OAT4 and OAT10) and secrete urate (ABCG2, OAT1, OAT3, NPT1, and NPT4) in the renal tubules and intestine, is a major cause of hyperuricemia, along with variations in the genes encoding these proteins. The first-line therapeutic drugs used to lower serum uric acid levels include XOD inhibitors that limit uric acid biosynthesis and uricosurics that decrease urate reabsorption in the renal proximal tubules and increase urate excretion into the urine and intestine via urate transporters. However, long-term use of high doses of these drugs induces acute kidney disease, chronic kidney disease and liver toxicity. Therefore, there is an urgent need for new nephroprotective drugs with improved safety profiles and tolerance. The current systematic review summarizes the characteristics of major urate transporters, the mechanisms underlying the pathogenesis of hyperuricemia, and the regulation of uric acid biosynthesis and transport. Most importantly, this review highlights the potential mechanisms of action of some naturally occurring bioactive compounds with antihyperuricemic and nephroprotective potential isolated from various medicinal plants.

Mechanism of PDZK1 in Hepatocellular Carcinoma Complicated with Hyperuricemia

Background

Hepatocellular carcinoma (HCC) is a kind of primary liver cancer that accounts for more than 90% of primary hepatocellular carcinomas. Hyperuricemia is closely related to the development, recurrence, metastasis, and prognosis of cancer. Previous studies have proved that the serum uric acid level can increase the incidence rate and mortality of malignant tumors. However, the specific pathogenesis remains unstudied.

Methods

RT-qPCR analysis showed that the mRNA expression of PDZK1 and ABCG2 increased significantly after HCC cells were exposed to different concentrations of soluble uric acid (2.5, 5, 10, 20 mg/dl) for 24 hours. Then, in HCC shRNAs, PDZK1, or over expression PDZK1 were used. CCK8, wound healing, and Transwell assay showed that PDZK1 regulates cell proliferation, invasion, and migration. Flow cytometry results revealed that PDZK1 affects cell apoptosis. Western blot results show that PDZK1 affects the STAT3/C-myc pathway. Then, in vivo tumorigenesis, allopurinol maybe an effective drug to advance: the prognosis of HCC.

Results

In our study, RT-qPCR analysis showed that the mRNA expression of PDZK1 and ABCG2 increased significantly after different concentrations of soluble uric acid in HCC. Then, PDZK1 affects the proliferation, migration, and apoptosis of HCC through the STAT3/C-myc pathway.

Conclusions

Hyperuricemia response affects the expression of PDZK1; PDZK1 affects the proliferation, migration, and apoptosis through the STAT3/C-myc pathway in hepatocellular carcinoma. It is suggested that PDZK1 maybe closely related to the occurrence, development, and prognosis of HCC and allopurinol maybe have potential anticancer effects.

T-2 Toxin Induces Kidney Fibrosis via the mtROS-NLRP3-Wnt/β-Catenin Axis

T-2 toxin causes kidney fibrosis. Wnt/β-catenin signaling promotes kidney fibrosis when sustained and activated. However, whether T-2-induced kidney fibrosis involves Wnt/β-catenin signaling activation has not been explored yet. T-2 toxin causes renal mitochondrial damage, leading to mitochondrial reactive oxygen species (mtROS) overproduction and NLRP3-inflammasome activation. The activated NLRP3-inflammasome can mediate fibrosis. However, whether the NLRP3-inflammasome can be mediated by mtROS and further regulate T-2-induced kidney fibrosis through Wnt/β-catenin signaling is unclear. In this study, first, we confirmed that T-2 toxin caused Wnt/β-catenin signaling activation in mice kidneys and HK-2 cells. Second, we confirmed that mtROS activated the NLRP3-inflammasome in T-2-exposed mice kidneys and HK-2 cells. Third, we confirmed that the NLRP3-inflammasome regulated the Wnt/β-catenin signaling in T-2 toxin-exposed mice kidneys and HK-2 cells. Finally, we confirmed that Wnt/β-catenin signaling regulated fibrosis in T-2 toxin-exposed mice kidneys and HK-2 cells. The above results confirm that T-2 toxin induces kidney fibrosis via the mtROS-NLRP3-Wnt/β-catenin axis.

The gut microbe Bacteroides fragilis ameliorates renal fibrosis in mice

Renal fibrosis is an inevitable outcome of various manifestations of progressive chronic kidney diseases (CKD). The need for efficacious treatment regimen against renal fibrosis can therefore not be overemphasized. Here we show a novel protective role of Bacteroides fragilis (B. fragilis) in renal fibrosis in mice. We demonstrate decreased abundance of B. fragilis in the feces of CKD patients and unilateral ureteral obstruction (UUO) mice. Oral administration of live B. fragilis attenuates renal fibrosis in UUO and adenine mice models. Increased lipopolysaccharide (LPS) levels are decreased after B. fragilis administration. Results of metabolomics and proteomics studies show decreased level of 1,5-anhydroglucitol (1,5-AG), a substrate of SGLT2, which increases after B. fragilis administration via enhancement of renal SGLT2 expression. 1,5-AG is an agonist of TGR5 that attenuates renal fibrosis by inhibiting oxidative stress and inflammation. Madecassoside, a natural product found via in vitro screening promotes B. fragilis growth and remarkably ameliorates renal fibrosis. Our findings reveal the ameliorative role of B. fragilis in renal fibrosis via decreasing LPS and increasing 1,5-AG levels.

Fibroblast Growth Factor 21 Attenuates the Progression of Hyperuricemic Nephropathy through Inhibiting Inflammation, Fibrosis and Oxidative stress

Elevated levels of circulating fibroblast growth factor 21 (FGF21) have been reported in patients with hyperuricemia. However, the effect of FGF21 in hyperuricemic nephropathy (HN) remains unexplored. Here, we investigated the effect and mechanism of action of FGF21 on HN. HN model was induced with adenine and potassium oxysalt in wild-type C57BL/6 mice and FGF21^-/- mice. For in vitro studies, human renal tubular epithelial (HK-2) cells were exposed to uric acid with/without FGF21 or β-Klotho-siRNA. Here, we reported aggravated renal dysfunction and structural damage in the FGF21^-/- mice compared to the wild-type mice. These were evident in the upsurge of inflammatory factors IL-1β, TNF-α, IL-6 and IL-18, fibrotic markers Collagen I and α-SMA, and oxidation products ROS and MDA. However, exogenous administration of FGF21 to wild-type HN mice significantly reversed these negative effects. In terms of mechanism, FGF21 significantly inhibited NF-κB/NLRP3 and TGF-β1/Smad3 pathways and promoted nuclear translocation of Nrf2 both in vivo and in vitro. Furthermore, the silencing of β-Klotho was marked by the attenuation of the improved effect of FGF21 on cell damage. In conclusion, our studies revealed that exogenous FGF21 treatment significantly improved HN, which was achieved by the inhibition of inflammation, fibrosis and oxidative stress.

Therapeutic Potential and Pharmaceutical Development of a Multitargeted Flavonoid Phloretin

Phloretin is a flavonoid of the dihydrogen chalcone class, present abundantly in apples and strawberries. The beneficial effects of phloretin are mainly associated with its potent antioxidant properties. Phloretin modulates several signaling pathways and molecular mechanisms to exhibit therapeutic benefits against various diseases including cancers, diabetes, liver injury, kidney injury, encephalomyelitis, ulcerative colitis, asthma, arthritis, and cognitive impairment. It ameliorates the complications associated with diabetes such as cardiomyopathy, hypertension, depression, memory impairment, delayed wound healing, and peripheral neuropathy. It is effective against various microbial infections including Salmonella typhimurium, Listeria monocytogenes, Mycobacterium tuberculosis, Escherichia coli, Candida albicans and methicillin-resistant Staphylococcus aureus. Considering the therapeutic benefits, it generated interest for the pharmaceutical development. However, poor oral bioavailability is the major drawback. Therefore, efforts have been undertaken to enhance its bioavailability by modifying physicochemical properties and molecular structure, and developing nanoformulations. In the present review, we discussed the pharmacological actions, underlying mechanisms and molecular targets of phloretin. Moreover, the review provides insights into physicochemical and pharmacokinetic characteristics, and approaches to promote the pharmaceutical development of phloretin for its therapeutic applications in the future. Although convincing experimental data are reported, human studies are not available. In order to ascertain its safety, further preclinical studies are needed to encourage its pharmaceutical and clinical development.

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.

The inhibition of GLUT1-induced glycolysis in macrophage by phloretin participates in the protection during acute lung injury

The increased level of glycolysis in macrophage aggravates lipopolysaccharide (LPS)-induced acute lung injury (ALI). Glucose transporter 1 (GLUT1) serves as a ubiquitously expressed glucose transporter, which could activate inflammatory response by mediating glycolysis. Phloretin (PHL), an apple polyphenol, is also an inhibitor of GLUT1, possessing potent anti-inflammatory effects in various diseases. However, the potential role of PHL in ALI remains unclear till now. This study aims to investigate the impacts of PHL on ALI as well as its possible mechanisms. A mouse ALI model was established via intratracheal injection of LPS. LPS-induced primary macrophages were used to mimic in vitro ALI. Mice were pretreated with low or high dosage of PHL for 7 days via intragastric administration once a day before LPS injection. The results showed that PHL pretreatment significantly prevented LPS-induced lung pathological injury and inflammatory response. Meantime, PHL pretreatment also decreased the level of glycolysis in macrophage during ALI. In terms of mechanism, PHL inhibited the mRNA and protein expression of GLUT1. In vitro experiments further showed GLUT1 overexpression in macrophage by infection with lentivirus could abolish the inhibition of inflammation and glycolysis mediated by PHL, suggesting that GLUT1 was essential for the protection of PHL. Taken together, PHL pretreatment may protect against LPS-induced ALI by inhibiting glycolysis in macrophage in a GLUT1-dependent manner, which may be a candidate against ALI in the future.

The NLRP3 Inflammasome Inhibitor Dapansutrile Attenuates Cyclophosphamide-Induced Interstitial Cystitis

Interstitial cystitis (IC)/bladder pain syndrome (BPS), hereafter referred together as IC, is a clinical syndrome characterized by sterile inflammation in the bladder. While the etiology and pathophysiology of IC remain unclear, it may involve autoimmunity in light of the significant role played by the NLRP3 inflammasome. However, the effect of NLRP3 inhibitors including dapansutrile (Dap) on IC had not been explored previously. Here, we investigated the effect of Dap in the cyclophosphamide (CYP)-induced experimental mouse model of IC, which results in functional and histological alterations confined to the urinary bladder (UB) comparable to that of clinical IC. CYP-induced mice treated with Dap exhibited improved UB pathology and reductions in inflammation scores and the frequency and the number of mast cells and neutrophils, relative to mice that received CYP alone. Dap- and CYP-treated mice also exhibited infiltration of T cells in the spleen and iliac lymph nodes (ILNs) and a concurrent significant decrease (p<0.01) in CXCR3⁺CD8⁺ T cells in the UB, induction of systemic and mucosal dendritic cells (DCs), and reduced levels of systemic proinflammatory cytokines, as compared to CYP alone. We also observed decreases in the expression of several signaling pathways regulators, including interleukin-1 beta (IL-1β), NLRP3, caspase-1, nuclear factor kappa B (NF-κB), and inducible nitric oxide synthase (iNOS) in the UB of CYP- and Dap-treated mice, relative to those receiving CYP alone. Taken together, these results suggest that Dap suppresses IC through the reduction of CXCR3⁺T cells, mast cells, and neutrophils in the UB and induces DCs as a protective measure. The present study identifies the mechanisms underlying the amelioration of IC by the NLRP3 inhibitor Dap and may provide an avenue for a potential therapeutic agent for the treatment of IC.

NLRP3 Inflammasome Activation: A Therapeutic Target for Cerebral Ischemia–Reperfusion Injury

Millions of patients are suffering from ischemic stroke, it is urgent to figure out the pathogenesis of cerebral ischemia–reperfusion (I/R) injury in order to find an effective cure. After I/R injury, pro-inflammatory cytokines especially interleukin-1β (IL-1β) upregulates in ischemic brain cells, such as microglia and neuron. To ameliorate the inflammation after cerebral I/R injury, nucleotide-binding oligomerization domain (NOD), leucine-rich repeat (LRR), and pyrin domain-containing protein 3 (NLRP3) inflammasome is well-investigated. NLRP3 inflammasomes are complicated protein complexes that are activated by endogenous and exogenous danger signals to participate in the inflammatory response. The assembly and activation of the NLRP3 inflammasome lead to the caspase-1-dependent release of pro-inflammatory cytokines, such as interleukin (IL)-1β and IL-18. Furthermore, pyroptosis is a pro-inflammatory cell death that occurs in a dependent manner on NLRP3 inflammasomes after cerebral I/R injury. In this review, we summarized the assembly and activation of NLRP3 inflammasome; moreover, we also concluded the pivotal role of NLRP3 inflammasome and inhibitors, targeting the NLRP3 inflammasome in cerebral I/R injury.

The NLRP3 inflammasome in fibrosis and aging: The known unknowns

Aging-related diseases such as cancer, cardiovascular diseases, diabetes, and neurodegenerative diseases are often accompanied by fibrosis. The NLRP3 inflammasome triggers the inflammatory response and subsequently promotes fibrosis through pathogen-associated molecular patterns (PAMPs). In this review, we first introduce the general background and specific mechanism of NLRP3 in fibrosis. Second, we investigate the role of NLRP3 in fibrosis in different organs/tissues. Third, we discuss the relationship between NLRP3 and fibrosis during aging. In summary, this review describes the latest progress on the roles of NLRP3 in fibrosis and aging and reveals the possibility of NLRP3 as an antifibrotic and anti-aging treatment target.

Oridonin attenuates LPS-induced early pulmonary fibrosis by regulating impaired autophagy, oxidative stress, inflammation and EMT

CONTEXT

Oridonin (Ori) possesses anti-inflammatory, antioxidant and antitumor properties. However, the effects of Ori on Lipopolysaccharide (LPS)-induced early pulmonary fibrosis remain unclear.

OBJECTIVE

We evaluated the protective effects of Ori on the mice model of pulmonary fibrosis.

MATERIALS AND METHODS

The BALB/C mice were given LPS (1 mg/kg) or Ori (20 mg/kg) according to experimental grouping. Then the left lung tissues were used for HE, immunohistochemical and Masson staining, and the right lung tissues were used for hydroxyproline measurement and western blot experiments. Bronchoalveolar lavage fluid was collected for Giemsa staining.

RESULTS

The high levels of hydroxyproline induced by LPS were reduced by Ori treatment. Immunohistochemical staining and western blot analysis showed that Ori inhibited the increased levels of fibrosis-related proteins (α-smooth muscle actin, transforming growth factor-β, Collagen Ⅰ and phosphorylated-smad). Additionally, Ori treatment increased E-cadherin levels and decreased in Snail and Slug levels. Besides, Ori could suppress LPS-induced the infiltration of neutrophils and activation of the NLRP3 inflammasome. In addition, LPS caused the upregulation of NADPH oxidase 4 and exacerbated lung fibrosis. As the activator of NF-E2 related factor-2, Ori exerted protective effects in this animal model. Moreover, Ori reversed the LPS-triggered increases in Beclin-1, P62/sequestosome 1, autophagy related 3 and LC3.

CONCLUSIONS

These findings suggested that Ori protected against LPS-induced early pulmonary fibrosis by inhibiting NLRP3-dependent inflammation, NADPH oxidase 4-dependent oxidative stress, the impaired autophagy and epithelial mesenchymal transformation.

Research progress on related mechanisms of uric acid activating NLRP3 inflammasome in chronic kidney disease

Hyperuricemia is an independent risk factor for the progression of chronic kidney disease. High levels of uric acid can lead to a series of pathological conditions, such as gout, urinary stones, inflammation, and uric acid nephropathy. There is a close relationship between uric acid and the NLRP3 inflammasome. NLRP3 inflammasome activation can cause cell damage and even death through endoplasmic reticulum stress, lysosome destruction, mitochondrial dysfunction, and the interaction between the Golgi apparatus and extracellular vesicles. In addition, the NLRP3 inflammasome acts as a molecular platform, triggering the activation of caspase-1 and the lysis of IL-1β, IL-18 and Gasdermin D (GSDMD) through different molecular mechanisms. Cleaved NT-GSDMD forms pores in the cell membrane and triggers pyrophosphorylation, thereby inducing cell death and releasing many intracellular proinflammatory molecules. In recent years, studies have found that hyperuricemia or uric acid crystals can activate NLRP3 inflammasomes, and the activation of NLRP3 inflammasomes plays an important role in kidney disease. This article reviews the possible pathophysiological mechanisms by which uric acid activates inflammasomes and induces kidney damage at the cellular and molecular levels.

Novel insights into NOD-like receptors in renal diseases

Nucleotide-binding oligomerization domain-like receptors (NLRs), including NLRAs, NLRBs (also known as NAIPs), NLRCs, and NLRPs, are a major subfamily of pattern recognition receptors (PRRs). Owing to a recent surge in research, NLRs have gained considerable attention due to their involvement in mediating the innate immune response and perpetuating inflammatory pathways, which is a central phenomenon in the pathogenesis of multiple diseases, including renal diseases. NLRs are expressed in different renal tissues during pathological conditions, which suggest that these receptors play roles in acute kidney injury, obstructive nephropathy, diabetic nephropathy, IgA nephropathy, lupus nephritis, crystal nephropathy, uric acid nephropathy, and renal cell carcinoma, among others. This review summarises recent progress on the functions of NLRs and their mechanisms in the pathophysiological processes of different types of renal diseases to help us better understand the role of NLRs in the kidney and provide a theoretical basis for NLR-targeted therapy for renal diseases.

Enhanced oral bioavailability and anti-hyperuricemic activity of liquiritin via a self-nanoemulsifying drug delivery system

BACKGROUND

This study focused on the development of a self-nanoemulsifying drug delivery system (SNEDDS) to improve, potentially, the solubility and oral bioavailability of liquiritin (LQ).

METHODS

The solubility of LQ in different types of excipient, namely oils (OLs), emulsifiers (EMs), and co-emulsifiers (CO-EMs), was evaluated, and a pseudo-ternary phase diagram (PTPD) and the formulation optimization were established. The prepared self-nanoemulsifying drug delivery system of liquiritin (LQ-SNEDDS) was assessed using droplet size (DS), zeta potential (ZP), polydispersity index (PDI), droplet morphology, drug release in vitro, and oral bioavailability.

RESULTS

After the dilution of the LQ-SNEDDS, a transparent nanoemulsion was obtained with an acceptable DS (24.70 ± 0.73 nm), ZP (-18.69 ± 1.44 mV), and PDI (0.122 ± 0.006). The LQ-SNEDDS that was developed had a better release rate in vitro than the free LQ suspension. Pharmacokinetic evaluation showed that the relative oral bioavailability of LQ-SNEDDS was increased by 5.53 times, and LQ-SNEDDS exhibited a delayed half life and longer retention time in comparison with those of free LQ. Similarly, LQ-SNEDDS had a better urate lowering effect and provided better organ protection than free LQ at the same dose (P < 0.05).

CONCLUSIONS

The incorporation of LQ into SNEDDS could serve as a promising approach to improve the solubility, oral bioavailability, and anti-hyperuricemic effect of LQ. © 2021 Society of Chemical Industry.

Phenols and terpenoids: natural products as inhibitors of NLRP3 inflammasome in cardiovascular diseases

Inflammatory infiltration has been implicated in the pathogenesis of cardiovascular diseases (CVDs). The NLRP3 inflammasome is involved in the development of several types of CVDs, including myocardial infarction, myocardial ischemia-reperfusion damage, heart failure, atrial fibrillation, and hypertension. Inhibiting the activity of NLRP3 inflammasome can inhibit the progress of CVDs. However, there is no NLRP3 inflammasome inhibitor in clinic, and it is very important to find a safe and effective NLRP3 inhibitor. Phenols and terpenoids are naturally natural products that have many anti-inflammatory effects in CVDs by modulating the NLRP3 inflammatory pathway. Thus, 20 natural products from phenols and terpenoids for the treatment of cardiovascular disease based on the inhibition of NLRP3 inflammasome were summarized and screened. Docking results showed salvianolic acid B and ellagic acid in phenols, and oridonin and triptolide in terpenoids had a better binding activity with NLRP3, which can provide theoretical support for finding novel NLRP3 inflammasome inhibitors or lead compounds in the future.