Cardiometabolic traits mediating the effect of education on the risk of DKD and CKD: a Mendelian randomization study.

Background: Both diabetic kidney disease (DKD) and chronic kidney disease (CKD) are more prevalent among individuals with lower levels of education in observational studies. To quantify the mediation effect of recognized cardiometabolic traits, we obtain causal estimates between education and DKD as well as CKD. Materials and methods: We assessed the causal effect of education on DKD and CKD, separately estimated the causal effect of 26 cardiometabolic traits on DKD and CKD, and finally calculated the mediating effects and mediating proportions of each using two-step, two-sample multivariable Mendelian randomization (MVMR). Furthermore, the genetic association between exposure, mediators, and outcomes was investigated using linkage disequilibrium score (LDSC) regression analysis. Expression quantitative trait loci (eQTL) were retrieved from the Genotype-Tissue Expression Project (GTEx) v8 to serve as genetic instrumental variables. Transcriptome-wide association studies (TWAS), Bayesian colocalization analysis, and Summary-data-based Mendelian Randomization (SMR) analysis were performed to explore underlying susceptibility genes between education, mediators, and kidney diseases. Results: Higher education with a genetically predicted 1-SD (4.2 years) was linked to a 48.64% decreased risk of DKD and a 29.08% decreased risk of CKD. After extensive evaluation of 26 cardiometabolic traits, 7 and 6 causal mediators were identified as mediating the effects of education on DKD and CKD, respectively. The largest mediating factor between education and DKD was BMI, which was followed by WHR, T2D, fasting insulin, SBP, fasting glucose, and DBP. In contrast, candidate mediators in the education-to-CKD pathway included BMI, followed by cigarettes smoked per day, WHR, SBP, T2D, and DBP. MR analysis revealed that TP53INP1 was found to be a shared susceptibility gene for cardiometabolic traits and DKD, while L3MBTL3 was found to be a shared susceptibility gene for cardiometabolic traits and CKD. Conclusion: Our findings provide solid evidence that education has a causally protective effect on the development of DKD and CKD. We additionally reveal significant directions for intervention on cardiometabolic traits that mitigate the negative effects of educational inequities on the onset of DKD and CKD. Our work demonstrates a shared genetic basis between education, cardiometabolic traits, and kidney diseases. Future research aiming at lowering kidney risk may benefit from these findings.

The role of PANoptosis in renal vascular endothelial cells: Implications for trichloroethylene-induced kidney injury.

Trichloroethylene (TCE), a widely distributed environmental chemical contaminant, is extensively dispersed throughout the environment. Individuals who are exposed to TCE may manifest occupational medicamentose-like dermatitis due to trichloroethylene (OMDT). Renal impairment typically manifests in the initial phase of OMDT and is intricately linked to the disease progression and patient outcomes. Although recombinant human tumor necrosis factor-α receptor II fusion protein (rh TNFR:Fc) has been employed in the clinical management of OMDT, there was no substantial improvement in renal function observed in patients following one week of treatment. This study primarily examined the mechanism of TNFα- and IFNγ-induced endothelial cells (ECs) PANoptosis in TCE-induced kidney injury and hypothesized that the synergistic effect of TNFα and IFNγ could be the key factor affecting the efficacy of rh TNFR:Fc therapy in OMDT patients. A TCE-sensitized mouse model was utilized in this study to investigate the effects of TNFα and IFNγ neutralizing antibodies on renal vascular endothelial cell PANoptosis. The gene of interferon regulatory factor 1 (IRF1) in human umbilical vein endothelial cells (HUVEC) was silenced by using small interfering RNA (siRNA), and the cells were then treated with TNFα and IFNγ recombinant protein to investigate the mechanism of TNFα combined with IFNγ-induced PANoptosis in HUVEC. The findings indicated that mice sensitized to TCE exhibited increased levels of PANoptosis-related markers in renal endothelial cells, and treatment with TNFα and IFNγ neutralizing antibodies resulted in a significant reduction in PANoptosis and improvement in renal function. In vitro experiments demonstrated that silencing IRF1 could reverse TNFα and IFNγ-induced PANoptosis in endothelial cells. These results suggest that the efficacy of rh TNFR:Fc may be influenced by TNFα and IFNγ-mediated PANoptosis in kidney vascular endothelial cells. The joint application of TNFα and IFNγ neutralizing antibody represented a solid alternative to existing therapeutics.

Baicalein alleviates cisplatin-induced acute kidney injury by inhibiting ALOX12-dependent ferroptosis.

BACKGROUND: In acute kidney injury (AKI), ferroptosis is the main mechanism of cell death in the renal tubular epithelium. Baicalein, a traditional Chinese medicine monomer, plays a protective role in various kidney diseases; however, the effect of baicalein on ferroptosis in AKI still needs further exploration. PURPOSE: In this study, we explored the role of baicalein and its specific mechanism in mediating ferroptosis in cisplatin-induced AKI. METHODS: We used a cisplatin-induced AKI model to study the effects of baicalein on renal tissue and tubular epithelial cell injury. The effects of baicalein on tubular epithelial cell ferroptosis were detected in cisplatin-induced AKI and further verified by folic acid-induced AKI. The Swiss Target Prediction online database was used to predict the possible mechanism by which baicalein regulates ferroptosis, and the specific target proteins were further verified. Molecular docking and SPR were used to further determine the binding potential of baicalein to the target protein. Finally, RNA interference (RNAi) technology and enzymatic inhibition were used to determine whether baicalein regulates ferroptosis through target proteins. RESULTS: Baicalein alleviated cisplatin- and folic acid-induced renal dysfunction and pathological damage and improved cisplatin-induced HK2 cell injury. Mechanistically, baicalein reduced the expression of 12-lipoxygenase (ALOX12), which inhibits phospholipid peroxidation and ferroptosis in AKI. Molecular docking and SPR demonstrated direct binding between baicalein and ALOX12. Finally, we found that silencing ALOX12 had a regulatory effect similar to that of baicalein. Comparable results were also obtained with the ALOX12 inhibitor ML355. CONCLUSION: This was the first study to confirm that baicalein regulates ferroptosis both in vitro and in vivo in cisplatin-induced AKI and to verify the regulatory effect of baicalein in folic acid-induced AKI. Our results reveal the critical role of ALOX12 in kidney damage and ferroptosis caused by cisplatin and emphasize the regulatory effect of baicalein on renal tubular epithelial cell ferroptosis mediated by ALOX12. Baicalein is an effective drug for treating AKI, and ALOX12 is a potential drug target.

Analysis of the Cadmium Removal Mechanism of Human Gut Bacteria Enterococcus faecalis Strain ATCC19433 from a Genomic Perspective.

Cadmium (Cd) is one of the most well-known toxic metals capable of entering the human body via the food chain, leading to serious health problems. Human gut microbes play a pivotal role in controlling Cd bioavailability and toxicity within the human gastrointestinal tract, primarily due to their capacity for Cd adsorption and metabolism. In this work, a Cd-resistant bacterial strain, Enterococcus faecalis strain ATCC19433 was isolated from human gut microbiota. Cd binding assays and comprehensive characterization analyses were performed, revealing the ability of strain ATCC19433 to remove Cd from the solution. Cd adsorption primarily occurred on the bacterial cell walls, which was ascribed to the exciting of functional groups on the bacterial surfaces, containing alkyl, amide II, and phosphate groups; meanwhile, Cd could enter cells, probably through transport channels or via diffusion. These results indicated that Cd removal by the strain was predominantly dependent on biosorption and bioaccumulation. Whole-genome sequencing analyses further suggested the probable mechanisms of biosorption and bioaccumulation, including Cd transport by transporter proteins, active efflux of Cd by cadmium efflux pumps, and mitigating oxidative stress-induced cell damage by DNA repair proteases. This study evaluated the Cd removal capability and mechanism of Enterococcus faecalis strain ATCC19433 while annotating the genetic functions related to Cd removal, which may facilitate the development of potential human gut strains for the removal of Cd.

Identification and validation of ferroptosis-related gene SLC2A1 as a novel prognostic biomarker in AKI.

BACKGROUND: Emerging evidence reveals the key role of ferroptosis in the pathophysiological process of acute kidney injury (AKI). Our study aimed to investigate the potential ferroptosis-related gene in AKI through bioinformatics and experimental validation. METHODS: The AKI single-cell sequencing dataset was retrieved from the GEO database and ferroptosis-related genes were extracted from the GENECARD website. The potential differentially expressed ferroptosis-related genes of AKI were selected. Functional enrichment analysis was performed. Machine learning algorithms were used to identify key ferroptosis-related genes associated with AKI. A multi-factor Cox regression analysis was used to construct a risk score model. The accuracy of the risk score model was validated using receiver operating characteristic (ROC) curve analysis. We extensively explored the immune landscape of AKI using CIBERSORT tool. Finally, expressions of ferroptosis DEGs were validated in vivo and in vitro by Western blot, ICH and transfection experiments. RESULTS: Three hub genes (BAP1, MDM4, SLC2A1) were identified and validated by constructing drug regulatory network and subsequent screening using experimentally determined interactions. The risk mode showed the low-risk group had significantly better prognosis compared to high-risk group. The risk score was independently associated with overall survival. The ROC curve analysis showed that the prognosis model had good predictive ability. Additionally, CIBERSORT immune infiltration analysis suggest that the hub gene may influence cell recruitment and infiltration in AKI. Validation experiments revealed that SLC2A1 functions by regulating ferroptosis. CONCLUSIONS: In summary, our study not only identifies SLC2A1 as diagnostic biomarker for AKI, but also sheds light on the role of it in AKI progression, providing novel insights for the clinical diagnosis and treatment of AKI.

Circ-0000953 deficiency exacerbates podocyte injury and autophagy disorder by targeting Mir665-3p-Atg4b in diabetic nephropathy.

Circular RNAs (circRNAs) are special non-coding RNA (ncRNA) molecules that play a significant role in many diseases. However, the biogenesis and regulation of circRNAs in diabetic nephropathy (DN) are largely unknown. Here, we investigated the expression profile of circRNAs in kidney of DN mice through circular RNA sequencing (circRNA-seq). The renal biopsy samples of patients with DN had low circ -0,000,953 expression, which was significantly associated with renal function. Furthermore, loss-of-function and gain-of-function experiments were carried out to prove the role of circ -0,000,953 in DN. Podocyte conditional knockin (cKI) or systemic overexpression of circ -0,000,953 alleviated albuminuria and restored macroautophagy/autophagy in kidney of diabetic mice. However, circ -0,000,953 knockdown exacerbated albuminuria and podocyte injury. Mechanistically, we found circ -0,000,953 directly binds to Mir665-3p-Atg4b to perform its function. Silencing of Mir665-3p or overexpression of Atg4b recovered podocyte autophagy both in vitro and in vivo. To examine the cause of circ -0,000,953 downregulation in DN, bioinformatics prediction found that circ -0,000,953 sequence has a high possibility of containing an m6A methylation site. Additionally, METTL3 was proved to regulate the expression and methylation level of circ -0,000,953 through YTHDF2 (YTH N6-methyladenosine RNA binding protein 2). In conclusion, this study revealed that circ -0,000,953 regulates podocyte autophagy by targeting Mir665-3p-Atg4b in DN. Therefore, circ -0,000,953 is a potential biomarker for prevention and cure of DN.Abbreviation: CCL2/MCP-1: C-C motif chemokine ligand 2; ceRNA: competing endogenous RNA; circRNA: circular RNA; cKI: conditional knockin; cKO: conditional knockout; CRE: creatinine; DM: diabetes mellitus; DN: diabetic nephropathy; ESRD: end-stage renal disease; HG: high glucose; IF: immunofluorescence; MAP1LC3/LC3B: microtubule-associated protein 1 light chain 3 beta; MPC5: mouse podocyte clone 5; MTECs: mouse tubular epithelial cells; MTOR: mechanistic target of rapamycin kinase; NC: normal control; ncRNA: non-coding RNA; NPHS1: nephrosis 1, nephrin; NPHS2: nephrosis 2, podocin; PAS: periodic acid-Schiff; RELA/p65: v-rel reticuloendotheliosis viral oncogene homolog A (avian); SDs: slit diaphragm proteins; Seq: sequencing; STZ: streptozotocin; SV40: SV40-MES13-cells, mouse mesangial cell line; T1D: type 1 diabetes mellitus; T2D: type 2 diabetes mellitus; TEM: transmission electron microscopy; TNF/TNF-α: tumor necrosis factor; VECs: vascular endothelial cells; WT1: WT1 transcription factor; YTHDF2: YTH N6-methyladenosine RNA binding protein 2.

Influence mechanism of plant litter mediated reduction of iron and sulfur on migration of potentially toxic elements from mercury-thallium mine waste.

The decomposition of plant litter in soil changes soil nutrient content and plays an important role in regulating soil pH and availability of potentially toxic elements (PTEs). However, there remains limited studies on the mechanism under which litter influences the transport of PTEs in the process of ecological restoration. This study examined the effect of plant litter decomposition mediated reduction of iron and sulfur components on migration of PTEs from mercury-thallium mine waste. The results showed that the four kinds of litter alleviated the acidity of the waste, especially the Bpa and Tre litter. The nitro and nitroso groups produced by the decomposition of the litter were adsorbed onto the waste, thereby providing an electron transfer medium for iron reducing microorganisms, such as Geobacter. This promoted the reduction and release of Fe3+ to Fe2+ and reduced the electronegativity (El) value of waste. The reduced El promoted the adsorption of metal cations such as Hg and Tl to maintain electrical neutrality. However, it was not conducive to the adsorption of oxygen containing anions of As and Sb. An increase in litter resulted in an increase in reductivity of mercury-thallium mine waste. This maintained the reduction of Fe3+ to Fe2+ and changed or destroyed the structure of silicate minerals. PTEs, such as Tl, Hg, As, and Sb, were released, resulting in reductions in their residual fraction. However, the strong reduction conditions, especially the decomposition of Bpa, caused part of the released Hg(II) combining with S2- produced by the reduction of SO42- to form insoluble HgS, thereby reducing its migration. The findings could provide a theoretical basis to guide the situ-control and ecological restoration of PTEs in waste slag site.

Paeoniflorin protects against cisplatin-induced acute kidney injury through targeting Hsp90AA1-Akt protein-protein interaction.

ETHNOPHARMACOLOGICAL RELEVANCE: Paeonia lactiflora Pall has been used in Chinese Medicine for thousands of years, especially having anti-inflammatory, sedative, analgesic and other ethnic pharmacological effects. Moreover, Paeoniflorin is the main active ingredient of the Paeonia lactiflora Pall, and most are used in the treatment of inflammation-related autoimmune diseases. In recent years, studies have found that Paeoniflorin has a therapeutic effect on a variety of kidney diseases. AIM OF THE STUDY: Cisplatin (CIS) is limited in clinical use due to its serious side effects, such as renal toxicity, and there is no effective method for prevention. Paeoniflorin (Pae) is a natural polyphenol which has a protective effect against many kidney diseases. Therefore, our study is to explore the effect of Pae on CIS-induced AKI and the specific mechanism. MATERIALS AND METHODS: Firstly, CIS induced acute renal injury model was constructed in vivo and in vitro, and Pae was continuously injected intraperitoneally three days in advance, and then Cr, BUN and renal tissue PAS staining were detected to comprehensively evaluate the protective effect of Pae on CIS-induced AKI. We then combined Network Pharmacology with RNA-seq to investigate potential targets and signaling pathways. Finally, affinity between Pae and core targets was detected by molecular docking, CESTA and SPR, and related indicators were detected in vitro and in vivo. RESULTS: In this study, we first found that Pae significantly alleviated CIS-AKI in vivo and in vitro. Through network pharmacological analysis, molecular docking, CESTA and SPR experiments, we found that the target of Pae was Heat Shock Protein 90 Alpha Family Class A Member 1 (Hsp90AA1) which performs a crucial function in the stability of many client proteins including Akt. RNA-seq found that the KEGG enriched pathway was PI3K-Akt pathway with the most associated with the protective effect of Pae which is consistent with Network Pharmacology. GO analysis showed that the main biological processes of Pae against CIS-AKI include cellular regulation of inflammation and apoptosis. Immunoprecipitation further showed that pretreatment with Pae promoted the Hsp90AA1-Akt protein-protein Interactions (PPIs). Thereby, Pae accelerates the Hsp90AA1-Akt complex formation and leads to a significant activate in Akt, which in turn reduces apoptosis and inflammation. In addition, when Hsp90AA1 was knocked down, the protective effect of Pae did not continue. CONCLUSION: In summary, our study suggests that Pae attenuates cell apoptosis and inflammation in CIS-AKI by promoting Hsp90AA1-Akt PPIs. These data provide a scientific basis for the clinical search for drugs to prevent CIS-AKI.

Serum and urinary carnosinase-1 correlate with kidney function and inflammation.

The carnosinase dipeptidase 1 (CNDP1) gene has been reported as a susceptibility locus for the development of diabetic kidney disease (DKD). While the (CTG)5 allele affords protection in the Caucasian population, we have previously shown that this allele is less frequently present in the Chinese population and therefore a protective role for the (CTG)5 allele is difficult to demonstrate. In the present study, we sought to assess if carnosinase-1 (CN-1) concentrations in serum and/or urine are associated with progression of DKD and to what extent CN-1 influences diabetes-associated inflammation. From a total of 622 individuals that enrolled in our study, 247 patients had type 2 diabetes without DKD, 165 patients had DKD and 210 subjects served as healthy controls. Uni- and multivariate regression analyses were performed to identify potential factors predicting urinary albumin creatinine ratio (UACR), estimated glomerular filtration rate (eGFR) and CN-1 concentration in serum and urine. The results indicated that serum CN-1 indeed correlated with eGFR (p = 0.001). In addition, urinary CN-1 associated with eGFR and tubular injury indicator: urinary cystatin C (Cys-C) and urinary retinol-binding protein (RBP). Interestingly, serum CN-1 also positively correlated with inflammatory indicators: neutrophils and lymphocytes. With regard to this, a STZ injected C57BL/6 mice model with surgically made skin wound was established for the generation of skin inflammation. This animal model further proved that the expression of CN-1 in liver and kidney increased remarkably in diabetic mice with skin wound as compared to those without. In conclusion, serum and urinary CN-1 significantly related to the surrogates of impaired renal function in diabetic patients; besides, CN-1 expression might also be associated with the process of inflammation.

Advances in Anti-metabolic Disease Treatments Targeting CD47.

Metabolic disorders include a cluster of conditions that result from hyperglycemia, hyperlipidemia, insulin resistance, obesity, and hepatic steatosis, which cause the dysfunction of immune cells and innate cells, such as macrophages, natural killer cells, vascular endothelial cells, hepatocytes, and human kidney tubular epithelial cells. Besides targeting the derangements in lipid metabolism, therapeutic modulations to regulate abnormal responses in the immune system and innate cell dysfunctions may prove to be promising strategies in the management of metabolic diseases. In recent years, several targets have been explored for the CD47 molecule (CD47), a glycosylated protein, which was originally reported to transmit an anti-phagocytic signal known as "don't eat me" in the atherosclerotic environment, hindering the efferocytosis of immune cells and promoting arterial plaque accumulation. Subsequently, the role of CD47 has been explored in obesity, fatty liver, and lipotoxic nephropathy, and its utility as a therapeutic target has been investigated using anti-CD47 antibodies or inhibitors of the THBS1/CD47 axis and the CD47/SIRPα signaling pathway. This review summarizes the mechanisms of action of CD47 in different cell types during metabolic diseases and the clinical research progress to date, providing a reference for the comprehensive targeting of CD47 to treat metabolic diseases and the devising of potential improvements to possible side effects.

Paeoniflorin binds to VEGFR2 to restore autophagy and inhibit apoptosis for podocyte protection in diabetic kidney disease through PI3K-AKT signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Paeoniflorin (PF) was found to exhibit renal protection from diabetic kidney disease (DKD) in previous trials, but its specific mechanism remains to be elucidated. AIM OF THE STUDY: This study furtherly explored the specific mechanism of PF in protect podocyte injury in DKD. MATERIALS AND METHODS: We observed the effects of PF on renal tissue and podocytes in DKD by constructing the vitro and vivo models after measuring the pharmacokinetic characteristics of PF. Target proteins of PF were found through target prediction, and verified by molecular docking, CESTA, and SPR, and then furtherly explored the downstream regulation mechanism related to podocyte autophagy and apoptosis by network prediction and co-immunoprecipitation. Finally, by using the target protein inhibitor in vivo and knocking down the target protein gene in vitro, it was verified that PF played a role in regulating autophagy and apoptosis through the target protein in diabetic nephropathy. RESULTS: This study found that in STZ-induced mice model, PF could improve the renal biochemical and pathological damage and podocyte injure (p < 0.05), upregulate autophagy activity (p < 0.05), but inhibit apoptosis (p < 0.01). Vascular endothelial growth factor receptor 2 (VEGFR2), predicted as the target of PF, directly bind with PF reflected by molecular docking and surface plasmon resonance detection. Animal studies demonstrated that VEGFR2 inhibitors have a protective effect similar to that of PF on DKD. Network prediction and co-immunoprecipitation further confirmed that VEGFR2 was able to bind PIK3CA to regulate PI3K-AKT signaling pathway. Furthermore, PF downregulated the phosphorylation of PI3K and AKT (p < 0.05). In vitro, similarly to autophagy inhibitors, PF was also found to improve podocyte markers (p < 0.05) and autophagy activity (p < 0.05), decrease caspase 3 protein (p < 0.05) and further inhibited VEGFR2-PI3K-AKT activity (p < 0.05). Finally, the results of VEGFR2 knockdown were similar to the effect of PF in HG-stimulated podocytes. CONCLUSION: In conclusion, PF restores autophagy and inhibits apoptosis by targeting the VEGFR2-mediated PI3K-AKT pathway to improve renal injury in DKD, that provided a theoretical basis for PF treatment in DKD.

Paeoniflorin directly binds to TNFR1 to regulate podocyte necroptosis in diabetic kidney disease.

Necroptosis was elevated in both tubulointerstitial and glomerular renal tissue in patients with diabetic kidney disease (DKD), and was most pronounced on glomerulus in the stage with macroalbuminuria. This study further explored whether paeoniflorin (PF) could affect podocyte necroptosis to protect kidney injure in vivo and in vitro. Our study firstly verified that there are obvious necroptosis-related changes in the glomeruli of DKD through bioinformatics analysis combined with clinicopathological data. STZ-induced mouse diabetes model and high-glucose induced podocyte injury model were used to evaluate the renoprotection, podocyte injury protection and necroptosis regulation of PF in DKD. Subsequently, the target protein-TNFR1 that PF acted on podocytes was found by computer target prediction, and then molecular docking and Surface plasmon resonance (SPR) experiments were performed to verify that PF had the ability to directly bind to TNFR1 protein. Finally, knockdown of TNFR1 on podocytes in vitro verified that PF mainly regulated the programmed necrosis of podocytes induced by high glucose through TNFR1. In conclusion, PF can directly bind and promote the degradation of TNFR1 in podocytes and then regulate the RIPK1/RIPK3 signaling pathway to affect necroptosis, thus preventing podocyte injury in DKD. Thus, TNFR1 may be used as a new potential target to treat DKD.

Exosomal miR-7002-5p derived from highglucose-induced macrophages suppresses autophagy in tubular epithelial cells by targeting Atg9b.

Macrophage infiltration plays an important role in the progression of diabetic nephropathy (DN). Previously, we demonstrated that highglucose-stimulated macrophage-derived exosomes (HG-exo) induces proliferation and extracellular matrix accumulation in glomerular mesangial cells, but its effect on tubular cells is unclear. This study aimed to explore the role of HG-exo on renal tubular injury in DN. The results show that HG-exo could induce dysfunction, autophagy inhibition, and inflammation in mouse tubular epithelial cell (mTEC) and C57 mouse kidney. Moreover, miR-7002-5p was differentially expressed in HG-exo based on miRNAs sequencing and bioinformatics analysis. A dual-luciferase reporter assay confirmed that Atg9b was the direct target gene of miR-7002-5p. Further experimentation showed that miR-7002-5p inhibition in vivo and vitro reserves HG-exo effects. These results demonstrated that HG-exo carries excessive miR-7002-5p and inhibits autophagy through targeting Atg9b; this process then induces renal tubular dysfunction and inflammation. In conclusion, our study clarifies the important role of macrophage-derived exosomes in DN and is expected to provide new insight on DN prevention and treatment.

Insulin-like growth factor binding protein 7 promotes acute kidney injury by alleviating poly ADP ribose polymerase 1 degradation.

The novel biomarker, insulin-like growth factor binding protein 7 (IGFBP7), is used clinically to predict different types of acute kidney injury (AKI) and has drawn significant attention as a urinary biomarker. However, as a secreted protein in the circulation of patients with AKI, it is unclear whether IGFBP7 acts as a key regulator in AKI progression, and if mechanisms underlying its upregulation still need to be determined. Here we found that IGFBP7 is highly expressed in the blood and urine of patients and mice with AKI, possibly via a c-Jun-dependent mechanism, and is positively correlated with kidney dysfunction. Global knockout of IGFBP7 ameliorated kidney dysfunction, inflammatory responses, and programmed cell death in murine models of cisplatin-, kidney ischemia/reperfusion-, and lipopolysaccharide-induced AKI. IGFBP7 mainly originated from kidney tubular epithelial cells. Conditional knockout of IGFBP7 from the kidney protected against AKI. By contrast, rescue of IGFBP7 expression in IGFBP7-knockout mice restored kidney damage and inflammation. IGFBP7 function was determined in vitro using recombinant IGFBP7 protein, IGFBP7 knockdown, or overexpression. Additionally, IGFBP7 was found to bind to poly [ADP-ribose] polymerase 1 (PARP1) and inhibit its degradation by antagonizing the E3 ubiquitin ligase ring finger protein 4 (RNF4). Thus, IGFBP7 in circulation acts as a biomarker and key mediator of AKI by inhibiting RNF4/PARP1-mediated tubular injury and inflammation. Hence, over-activation of the IGFBP7/PARP1 axis represents a promising target for AKI treatment.

Inhibition of METTL3 attenuates renal injury and inflammation by alleviating TAB3 m6A modifications via IGF2BP2-dependent mechanisms.

The role of N6-methyladenosine (m6A) modifications in renal diseases is largely unknown. Here, we characterized the role of N6-adenosine-methyltransferase-like 3 (METTL3), whose expression is elevated in renal tubules in different acute kidney injury (AKI) models as well as in human biopsies and cultured tubular epithelial cells (TECs). METTL3 silencing alleviated renal inflammation and programmed cell death in TECs in response to stimulation by tumor necrosis factor-α (TNF-α), cisplatin, and lipopolysaccharide (LPS), whereas METTL3 overexpression had the opposite effects. Conditional knockout of METTL3 from mouse kidneys attenuated cisplatin- and ischemic/reperfusion (I/R)-induced renal dysfunction, injury, and inflammation. Moreover, TAB3 [TGF-ß-activated kinase 1 (MAP3K7) binding protein 3] was identified as a target of METTL3 by m6A methylated RNA immunoprecipitation sequencing and RNA sequencing. The stability of TAB3 was increased through binding of IGF2BP2 (insulin-like growth factor 2 binding protein 2) to its m6A-modified stop codon regions. The proinflammatory effects of TAB3 were then explored both in vitro and in vivo. Adeno-associated virus 9 (AAV9)-mediated METTL3 silencing attenuated renal injury and inflammation in cisplatin- and LPS-induced AKI mouse models. We further identified Cpd-564 as a METTL3 inhibitor that had better protective effects against cisplatin- and ischemia/reperfusion-induced renal injury and inflammation than S-adenosyl-l-homocysteine, a previously identified METTL3 inhibitor. Collectively, METTL3 promoted m6A modifications of TAB3 and enhanced its stability via IGF2BP2-dependent mechanisms. Both genetic and pharmacological inhibition of METTL3 attenuated renal injury and inflammation, suggesting that the METTL3/TAB3 axis is a potential target for treatment of AKI.

Paeoniflorin ameliorates diabetic liver injury by targeting the TXNIP-mediated NLRP3 inflammasome in db/db mice.

BACKGROUND: Diabetic liver injury (DLI) is a complication that damages the quality of life in diabetes patients. While paeoniflorin (PF) exhibits anti-inflammatory and antioxidant effects, no data are available on whether PF protects against DLI. Therefore, we evaluated the effects of PF on hepatic steatosis and inflammation in db/db mice, a type 2 diabetes model. METHODS: In this study, we investigated the effects of PF on DLI using diabetic mice model (db/db mice) and high glucose (HG)-induced mouse AML12 cells. The effects of PF on TXNIP-mediated NLRP3 inflammasome in vivo and in vitro were evaluated by Western bloting, RT-PCR, immunohistochemistry (IHC) and immunofluorescence (IF) analysis. Through molecular docking experiments and cellular thermal shift assay (CETSA), we studied the binding ability of PF to thioredoxin-interacting protein (TXNIP). We use TXNIP siRNA to knock down TXNIP in AML12 cells. RESULTS: We found that PF reversed abnormal liver function and liver steatosis in db/db mice, while blocking the release of inflammatory cytokines. These effects are associated with PF inhibition of the TXNIP/NLRP3 signaling pathway. Molecular docking experiments and CETSA also demonstrated that TXNIP is a likely target of PF. In HG-treated AML12 cells, TXNIP knockdown eliminated the beneficial effects of PF. CONCLUSION: Using a combination of animal and in vitro experiments, this study demonstrated for the first time that PF ameliorates DLI through targeting the TXNIP-activated NLRP3 inflammasome. Thus, PF may be a potential therapeutic agent against DLI.

METTL3-mediated m6A modification of TIMP2 mRNA promotes podocyte injury in diabetic nephropathy.

Epigenetic changes are present in many physiological and pathological processes. The N6-methyladenosine (m6A) modification is the most common modification in eukaryotic mRNA. However, the role of m6A modification in diabetic nephropathy (DN) remains elusive. Here, we found that m6A modification was significantly upregulated in the kidney of type 1 and type 2 diabetic mice, which was caused by elevated levels of METTL3. Moreover, METTL3 is increased in podocyte of renal biopsy from patients with DN, which is related to renal damage. METTL3 knockout significantly reduced the inflammation and apoptosis in high glucose (HG)-stimulated podocytes, while its overexpression significantly aggravated these responses in vitro. Podocyte-conditional knockout METTL3 significantly alleviated podocyte injury and albuminuria in streptozotocin (STZ)-induced diabetic mice. Therapeutically, silencing METTL3 with adeno-associated virus serotype-9 (AAV9)-shMETTL3 in vivo mitigated albuminuria and histopathological injury in STZ-induced diabetic mice and db/db mice. Mechanistically, METTL3 modulated Notch signaling via the m6A modification of TIMP2 in an insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2)-dependent manner and exerted pro-inflammatory and pro-apoptotic effects. In summary, this study suggested that METTL3-mediated m6A modification is an important mechanism of podocyte injury in DN. Targeting m6A through the writer enzyme METTL3 is a potential approach for the treatment of DN.

Wogonin protects glomerular podocytes by targeting Bcl-2-mediated autophagy and apoptosis in diabetic kidney disease.

Diabetic kidney disease (DKD) is one of the microvascular complications of diabetes mellitus and a major cause of end-stage renal disease with limited treatment options. Wogonin is a flavonoid derived from the root of Scutellaria baicalensis Georgi, which has shown a potent renoprotective effect. But the mechanisms of action in DKD are not fully elucidated. In this study, we investigated the effects of wogonin on glomerular podocytes in DKD using mouse podocyte clone 5 (MPC5) cells and diabetic mice model. MPC5 cells were treated with high glucose (30 mM). We showed that wogonin (4, 8, 16 µM) dose-dependently alleviated high glucose (HG)-induced MPC5 cell damage, accompanied by increased expression of WT-1, nephrin, and podocin proteins, and decreased expression of TNF-α, MCP-1, IL-1ß as well as phosphorylated p65. Furthermore, wogonin treatment significantly inhibited HG-induced apoptosis in MPC5 cells. Wogonin reversed HG-suppressed autophagy in MPC5 cells, evidenced by increased ATG7, LC3-II, and Beclin-1 protein, and decreased p62 protein. We demonstrated that wogonin directly bound to Bcl-2 in MPC5 cells. In HG-treated MPC5 cells, knockdown of Bcl-2 abolished the beneficial effects of wogonin, whereas overexpression of Bcl-2 mimicked the protective effects of wogonin. Interestingly, we found that the expression of Bcl-2 was significantly decreased in biopsy renal tissue of diabetic nephropathy patients. In vivo experiments were conducted in STZ-induced diabetic mice, which were administered wogonin (10, 20, 40 mg · kg-1 · d-1, i.g.) every other day for 12 weeks. We showed that wogonin administration significantly alleviated albuminuria, histopathological lesions, and p65 NF-κB-mediated renal inflammatory response. Wogonin administration dose-dependently inhibited podocyte apoptosis and promoted podocyte autophagy in STZ-induced diabetic mice. This study for the first time demonstrates a novel action of wogonin in mitigating glomerulopathy and podocytes injury by regulating Bcl-2-mediated crosstalk between autophagy and apoptosis. Wogonin may be a potential therapeutic drug against DKD.

Complement-mediated M2/M1 macrophage polarization may be involved in crescent formation in lupus nephritis.

The function of the complement and macrophage crosstalk during the formation of crescents in lupus nephritis has not yet been reported. This study therefore aimed to explore the association of crescents, complements, and M2 macrophages with clinical features in lupus nephritis. We assessed a Chinese cohort comprising 301 patients with lupus nephritis. Renal biopsy specimens were collected from 64 patients with proliferative lupus nephritis (class III/III + V or IV/IV + V). The renal deposition of cluster of differentiation (CD) 68, inducible nitric oxide synthase, CD163, and C3a receptor (C3aR) was evaluated by immunostaining. The associations among crescents, complements, and M2 macrophages were also analyzed. Next, the underlying mechanism was investigated in vitro using C3a-treated macrophages. We found that M2-phenotype macrophages (CD163+) were the dominant subpopulation in human lupus nephritis. Additionally, a significant association was observed among the CD163+ macrophages, crescents, and complement activation. C3aR co-localized with CD163 and correlated with crescents and could induce polarization of macrophages to an M2 phenotype. Overall, these results suggest that complement-mediated M2/M1 macrophage polarization may contribute to the formation of crescents in lupus nephritis.

Carnosine alleviates podocyte injury in diabetic nephropathy by targeting caspase-1-mediated pyroptosis.

Diabetic nephropathy (DN) is a main complication of diabetes and often develops into end-stage nephropathy. Histologically, DN progresses as the gradual loss of podocytes with the loss of glomerular podocytes being the earliest sign of DN. Pyroptosis is a new type of programmed cell death and has been mechanistically correlated with podocyte injury in DN. The current study aimed to evaluate the protective effects of carnosine on glomerular podocytes in DN, both in vivo and in vitro. Using high glucose-treated cultured MPC5 cells and a streptozotocin (STZ)-induced diabetic mouse model, we evaluated the effects of carnosine on alleviating podocyte injury in DN. We found that carnosine significantly reversed albuminuria and histopathological lesions and alleviated renal inflammatory and pyroptosis responses in STZ-induced diabetic mice for 12 weeks. The results also showed that carnosine strongly inhibited podocyte inflammation and podocyte pyroptosis in vitro. Cellular Thermal Shift Assay (CETSA) and molecular docking results revealed that mechnaistically caspase-1 was the target of carnosine. We then found that silencing caspase-1 eliminated the protective effect of carnosine. Interestingly, we also found that caspase-1 and gasdermin D expression were increased in renal biopsy tissue of patients with DN. Our study is the first to demonstrate the novel role of carnosine in alleviating podocyte injury by inhibiting pyroptosis via the targeting of caspase-1. Carnosine may have potential as a therapeutic agent in treating DN by targeting caspase-1.