Activation of lipophagy is required for RAB7 to regulate ferroptosis in sepsis-induced acute kidney injury.

Sepsis-induced acute kidney injury (S-AKI) is the most common type of acute kidney injury (AKI), accompanied by elevated morbidity and mortality rates. This study investigated the mechanism by which lipid droplets (LDs) degraded via autophagy (lipophagy)required for RAB7 regulated ferroptosis in the pathogenesis of S-AKI. Here, we constructed the S-AKI model in vitro and in vivo to elucidate the potential relationship of lipophagy and ferroptosis, and we first confirmed that the activation of lipophagy promoted renal tubular epithelial cell ferroptosis and renal damage in S-AKI. The results showed that lipopolysaccharide (LPS) induced a marked increase in lipid peroxidation and ferroptosis, which were rescued by ferrstain-1 (Fer-1), an inhibitor of ferroptosis. In addition, LPS induced the remarkable activation of RAB7-mediated lipophagy. Importantly, silencing RAB7 alleviated LPS-induced lipid peroxidation and ferroptosis. Thus, the present study demonstrated the potential significant role of ferroptosis and lipophagy in sepsis-induced AKI, and contributed to better understanding of the pathogenesis and treatment targets of AKI.

Deconstructing the Dimensions of Mycobiome Fingerprints in Luohandu Cave, Guilin, Southern China.

Subterranean karst caves are windows into the terrestrial subsurface to deconstruct the dimensions of mycobiome fingerprints. However, impeded by the constraints of remote locations, the inaccessibility of specimens and technical limitations, the mycobiome of subterranean karst caves has remained largely unknown. Weathered rock and sediment samples were collected from Luohandu cave (Guilin, Southern China) and subjected to Illumina Hiseq sequencing of ITS1 genes. A total of 267 known genera and 90 known orders in 15 phyla were revealed in the mycobiomes. Ascomycota dominated all samples, followed by Basidiomycota and Mortierellomycota. The sediments possessed the relatively highest alpha diversity and were significantly different from weathered rocks according to the diversity indices and richness metrics. Fifteen families and eight genera with significant differences were detected in the sediment samples. The Ca/Mg ratio appeared to significantly affect the structure of the mycobiome communities. Ascomycota appeared to exert a controlling influence on the mycobiome co-occurrence network of the sediments, while Ascomycota and Basidiomycota were found to be the main phyla in the mycobiome co-occurrence network of weathered rocks. Our results provide a more comprehensive dimension to the mycobiome fingerprints of Luohandu cave and a new window into the mycobiome communities and the ecology of subterranean karst cave ecosystems.

DDRGK1-mediated ER-phagy attenuates acute kidney injury through ER-stress and apoptosis.

Acute kidney injury (AKI) constitutes a prevalent clinical syndrome characterized by elevated morbidity and mortality rates, emerging as a significant public health issue. This study investigates the interplay between endoplasmic reticulum (ER) stress, unfolded protein response (UPR), and ER-associated degradation (ER-phagy) in the pathogenesis of AKI. We employed four distinct murine models of AKI-induced by contrast media, ischemia-reperfusion injury, cisplatin, and folic acid-to elucidate the relationship between ER-phagy, ER stress, and apoptosis. Our findings reveal a marked decrease in ER-phagy coinciding with an accumulation of damaged ER, elevated ER stress, and increased apoptosis across all AKI models. Importantly, overexpression of DDRGK1 in HK-2 cells enhanced ER-phagy levels, ameliorating contrast-induced ER stress and apoptosis. These findings unveil a novel protective mechanism in AKI, wherein DDRGK1-UFL1-mediated ER-phagy mitigates ER stress and apoptosis in renal tubular epithelial cells. Our results thereby contribute to understanding the molecular underpinnings of AKI and offer potential therapeutic targets for its treatment.

Dapagliflozin alleviates renal inflammation and protects against diabetic kidney diseases, both dependent and independent of blood glucose levels.

Introduction: Diabetic kidney disease (DKD) has become the leading cause of end-stage renal disease worldwide. Therefore, efforts to understand DKD pathophysiology and prevent its development at the early phase are highly warranted. Methods: Here, we analyzed kidneys from healthy mice, diabetic mice, and diabetic mice treated with the sodium-glucose cotransporter 2 inhibitor dapagliflozin using ATAC and RNA sequencing. The findings were verified at the protein levels and in cultured cells. Results: Our combined method of ATAC and RNA sequencing revealed Csf2rb, Btla, and Isg15 as the key candidate genes associated with hyperglycemia, azotemia, and albuminuria. Their protein levels were altered together with multiple other inflammatory cytokines in the diabetic kidney, which was alleviated by dapagliflozin treatment. Cell culture of immortalized renal tubular cells and macrophages unraveled that dapagliflozin could directly effect on these cells in vitro as an anti-inflammatory agent independent of glucose concentrations. We further proved that dapagliflozin attenuated ischemia/reperfusion-induced chronic kidney injury and renal inflammation in mice. Discussion: Overall, our data emphasize the importance of inflammatory factors to the pathogenesis of DKD, and provide valuable mechanistic insights into the renoprotective role of dapagliflozin.

AMPK activation coupling SENP1-Sirt3 axis protects against acute kidney injury.

Acute kidney injury (AKI) is a critical clinical condition that causes kidney fibrosis, and it currently lacks specific treatment options. In this research, we investigate the role of the SENP1-Sirt3 signaling pathway and its correlation with mitochondrial dysfunction in proximal tubular epithelial cells (PTECs) using folic acid (FA) and ischemia-reperfusion-induced (IRI) AKI models. Our findings reveal that Sirt3 SUMOylation site mutation (Sirt3 KR) or pharmacological stimulation (metformin) protected mice against AKI and subsequent kidney inflammation and fibrosis by decreasing the acetylation level of mitochondrial SOD2, reducing mitochondrial reactive oxygen species (mtROS), and subsequently restoring mitochondrial ATP level, reversing mitochondrial morphology and alleviating cell apoptosis. In addition, AKI in mice was similarly alleviated by reducing mtROS levels using N-acetyl-L-cysteine (NAC) or MitoQ. Metabolomics analysis further demonstrated an increase in antioxidants and metabolic shifts in Sirt3 KR mice during AKI, compared with Sirt3 wild-type (WT) mice. Activation of the AMPK pathway using metformin promoted the SENP1-Sirt3 axis and protected PTECs from apoptosis. Hence, the augmented deSUMOylation of Sirt3 in mitochondria, activated through the metabolism-related AMPK pathway, protects against AKI and subsequently mitigated renal inflammation and fibrosis through Sirt3-SOD2-mtROS, which represents a potential therapeutic target for AKI.

Mitophagy alleviates cisplatin-induced renal tubular epithelial cell ferroptosis through ROS/HO-1/GPX4 axis.

Cisplatin is widely recommended in combination for the treatment of tumors, thus inevitably increasing the incidence of cisplatin-induced acute kidney injury. Mitophagy is a type of mitochondrial quality control mechanism that degrades damaged mitochondria and maintains cellular homeostasis. Ferroptosis, a new modality of programmed cell death, is characterized by iron-dependent phospholipid peroxidation and oxidative membrane damage. However, the role of mitophagy in ferroptosis in kidney disease is unclear. Here, we investigated the mechanism underlying both BNIP3-mediated and PINK1-PARK2-mediated mitophagy-induced attenuation of ferroptosis in cisplatin-induced acute kidney injury. The results showed that cisplatin induced mitochondrial injury, ROS release, intracellular iron accumulation, lipid peroxidation and ferroptosis in the kidney, which were aggravated in Bnip3 knockout, Pink1 knockout or Park2 knockout cisplatin-treated mice. Ferrstatin-1, a synthetic antioxidative ferroptosis inhibitor, rescued iron accumulation, lipid peroxidation and ferroptosis caused by inhibition of mitophagy. Thus, the present study elucidated a novel mechanism by which both BNIP3-mediated and PINK1-PARK2-mediated mitophagy protects against cisplatin-induced renal tubular epithelial cell ferroptosis through the ROS/HO1/GPX4 axis.

HIF1α-BNIP3-mediated mitophagy protects against renal fibrosis by decreasing ROS and inhibiting activation of the NLRP3 inflammasome.

Chronic kidney disease affects approximately 14.3% of people worldwide. Tubulointerstitial fibrosis is the final stage of almost all progressive CKD. To date, the pathogenesis of renal fibrosis remains unclear, and there is a lack of effective treatments, leading to renal replacement therapy. Mitophagy is a type of selective autophagy that has been recognized as an important way to remove dysfunctional mitochondria and abrogate the excessive accumulation of mitochondrial-derived reactive oxygen species (ROS) to balance the function of cells. However, the role of mitophagy and its regulation in renal fibrosis need further examination. In this study, we showed that mitophagy was induced in renal tubular epithelial cells in renal fibrosis. After silencing BNIP3, mitophagy was abolished in vivo and in vitro, indicating the important effect of the BNIP3-dependent pathway on mitophagy. Furthermore, in unilateral ureteral obstruction (UUO) models and hypoxic conditions, the production of mitochondrial ROS, mitochondrial damage, activation of the NLRP3 inflammasome, and the levels of αSMA and TGFß1 increased significantly following BNIP3 gene deletion or silencing. Following silencing BNIP3 and pretreatment with mitoTEMPO or MCC950, the protein levels of αSMA and TGFß1 decreased significantly in HK-2 cells under hypoxic conditions. These findings demonstrated that HIF1α-BNIP3-mediated mitophagy played a protective role against hypoxia-induced renal epithelial cell injury and renal fibrosis by reducing mitochondrial ROS and inhibiting activation of the NLRP3 inflammasome.

Predicting Progression of Kidney Injury Based on Elastography Ultrasound and Radiomics Signatures.

Background: Shear wave elastography ultrasound (SWE) is an emerging non-invasive candidate for assessing kidney stiffness. However, its prognostic value regarding kidney injury is unclear. Methods: A prospective cohort was created from kidney biopsy patients in our hospital from May 2019 to June 2020. The primary outcome was the initiation of renal replacement therapy or death, while the secondary outcome was eGFR < 60 mL/min/1.73 m2. Ultrasound, biochemical, and biopsy examinations were performed on the same day. Radiomics signatures were extracted from the SWE images. Results: In total, 187 patients were included and followed up for 24.57 ± 5.52 months. The median SWE value of the left kidney cortex (L_C_median) is an independent risk factor for kidney prognosis for stage 3 or over (HR 0.890 (0.796−0.994), p < 0.05). The inclusion of 9 out of 2511 extracted radiomics signatures improved the prognostic performance of the Cox regression models containing the SWE and the traditional index (chi-square test, p < 0.001). The traditional Cox regression model had a c-index of 0.9051 (0.8460−0.9196), which was no worse than the machine learning models, Support Vector Machine (SVM), SurvivalTree, Random survival forest (RSF), Coxboost, and Deepsurv. Conclusions: SWE can predict kidney injury progression with an improved performance by radiomics and Cox regression modeling.

Gene polymorphisms of VEGF and KDR are associated with initial fast peritoneal solute transfer rate in peritoneal dialysis.

BACKGROUND: Peritoneal dialysis (PD) is an effective and successful renal replacement therapy. The baseline peritoneal solute transfer rate (PSTR) is related to local membrane inflammation and may be partially genetically determined. Herein, we focused on vascular endothelial growth factor (VEGF) and its receptor, kinase insert domain containing receptor (KDR). METHODS: This study recruited 200 PD patients from Renji Hospital in Shanghai, China. We analysed the association between the polymorphisms of VEGF and KDR and the 4-hour dialysate-to-plasma ratio for creatinine (4 h D/P Cr), which was measured between one and three months after initiating PD. RESULTS: The CC genotype in VEGF rs3025039 and the AA genotype in KDR rs2071559 were both positively associated with a fast baseline PSTR (VEGF rs3025039 CC vs. TT + TC: 0.65 ± 0.12 vs. 0.61 ± 0.11; P = 0.029; KDR rs2071559 AA vs. GA + GG: 0.65 ± 0.12 vs. 0.62 ± 0.12; P = 0.039). CONCLUSION: Baseline PSTR was partly determined by VEGF and KDR gene polymorphisms.

Downregulation of PPARα mediates FABP1 expression, contributing to IgA nephropathy by stimulating ferroptosis in human mesangial cells.

Immunoglobulin A nephropathy (IgAN) is the commonest primary glomerulonephritis, and a major cause of end-stage renal disease; however, its pathogenesis requires elucidation. Here, a hub gene, FABP1, and signaling pathway, PPARα, were selected as key in IgAN pathogenesis by combined weighted gene correlation network analysis of clinical traits and identification of differentially expressed genes from three datasets. FABP1 and PPARα levels were lower in IgAN than control kidney, and linearly positively correlated with one another, while FABP1 levels were negatively correlated with urinary albumin-to-creatinine ratio, and GPX4 levels were significantly decreased in IgAN. In human mesangial cells (HMCs), PPARα and FABP1 levels were significantly decreased after Gd-IgA1 stimulation and mitochondria appeared structurally damaged, while reactive oxygen species (ROS) and malondialdehyde (MDA) were significantly increased, and glutathione and GPX4 decreased, relative to controls. GPX4 levels were decreased, and those of ACSL4 increased on siPPARα and siFABP1 siRNA treatment. In PPARα lentivirus-transfected HMCs stimulated by Gd-IgA1, ROS, MDA, and ACSL4 were decreased; glutathione and GPX4, and immunofluorescence colocalization of PPARα and GPX4, increased; and damaged mitochondria reduced. Hence, PPARα pathway downregulation can reduce FABP1 expression, affecting GPX4 and ACSL4 levels, causing HMC ferroptosis, and contributing to IgAN pathogenesis.

C4d as a Screening Tool and an Independent Predictor of Clinical Outcomes in Lupus Nephritis and IgA Nephropathy.

BACKGROUND: As an indispensable marker of complement cascades activation, C4d was confirmed of its crucial role in the pathogenesis of both lupus nephritis (LN) and IgA nephropathy (IgAN). While the studies directly comparing the diagnostic value, and outcomes predicting function of C4d between LN and IgAN are still absent. METHODS: A cohort of 120 LN patients, 120 IgAN patients who were diagnosed by renal biopsy between January 2015 and December 2017 and 24 healthy age matched controls were prospectively analyzed. The patients were followed till December 2020. The outcomes were adverse disease treatment response (disease relapse) and kidney disease progression event (decline of estimated glomerular filtration rate by more than 20% or end-stage kidney disease). The renal C4d deposition proportion and pattern were compared between IgAN and LN patients. In addition, the relationship between renal C4d deposition and disease subtypes, disease relapse as well as disease progression for LN and IgAN patients were also analyzed. RESULTS: The LN, IgAN patients and healthy controls were well matched in ages. The follow-up period was 38.5 (30.3-60.8) months for LN patients and 45.0 (30.5-57.0) months for IgAN patients. 78 patients (65.0%) with LN had renal C4d deposition, compared with only 39 IgAN patients (32.5%) with C4d deposition in renal tissues (P < 0.001). The LN patients shared different renal C4d distribution patterns with IgAN patients. Compared with IgAN patients, the C4d deposition in LN patients was significantly more in renal glomerulus (P < 0.001) and less in renal tubules (P = 0.003). For disease subtypes, renal C4d deposition was especially strong in class V membranous LN and IgAN with tubulointerstitial fibrosis (T1/T2) lesions. Renal C4d deposition was independently correlated with the disease relapse of LN patients (HR = 1.007, P = 0.040), and acted as an independent predictor of disease progression during the follow-up period for IgAN patients (HR = 1.821, P = 0.040). CONCLUSIONS: Renal C4d distribution proportion and pattern differed between LN and IgAN patients. The presence of C4d in renal tissue acted as an independent predictor of relapse for LN patients and disease progression for IgAN patients.

Astragaloside IV Targets Macrophages to Alleviate Renal Ischemia-Reperfusion Injury via the Crosstalk between Hif-1α and NF-κB (p65)/Smad7 Pathways.

(1) Background: Astragaloside IV (AS-IV) is derived from Astragalus membranous (AM), which is used to treat kidney disease. Macrophages significantly affect the whole process of renal ischemia-reperfusion (I/R). The regulation of macrophage polarization in kidneys by AS-IV was the focus. (2) Methods: Renal tubular injury and fibrosis in mice were detected by Hematoxylin and Eosin staining and Masson Trichrome Staining, separately. An ELISA and quantitative real-time polymerase chain reaction were used to explore the cytokine and mRNA expression. Western blot was used to determine protein expression and siRNA technology was used to reveal the crosstalk of signal pathways in RAW 264.7 under hypoxia. (3) Results: In the early stages of I/R injury, AS-IV reduced renal damage and macrophage infiltration. M1-associated markers were decreased, while M2 biomarkers were increased. The NF-κB (p65)/Hif-1α pathway was suppressed by AS-IV in M1. Moreover, p65 dominated the expression of Hif-1α. In the late stages of I/R injury, renal fibrosis was alleviated, and M2 infiltration also decreased after AS-IV treatment. Hif-1α expression was reduced by AS-IV, while Smad7 expression was enhanced. Hif-1α interferes with the expression of Smad7 in M2. (4) Conclusions: AS-IV promoted the differentiation of M1 to M2, relieving the proinflammatory response to alleviate the kidney injury during the early stages. AS-IV attenuated M2 macrophage infiltration to prevent kidney fibrosis during the later stages.

αKlotho protein has therapeutic activity in contrast-induced acute kidney injury by limiting NLRP3 inflammasome-mediated pyroptosis and promoting autophagy.

Contrast-induced acute kidney injury (CI-AKI) is a main cause of hospital-acquired renal failure. Nevertheless, limited measures have been shown to be effective for the treatment of CI-AKI. Here, we demonstrated that αKlotho, which is highly expressed in kidney, has therapeutic activity in CI-AKI. Our data showed that αKlotho expression levels were decreased both in the kidney and serum of CI-AKI mice. Administration of αKlotho protein protected the kidney and HK-2 cells against contrast-induced injury. Mechanistically, αKlotho reduced contrast-induced renal tubular cells pyroptosis by limiting NLRP3 inflammasome activation. Meanwhile, αKlotho up-regulated autophagy via inhibiting the AKT/mTOR pathway and decreased mitochondrial ROS level. Inhibition of autophagy blunted the suppression effect of αKlotho on NLRP3 inflammasome activation and cell pyroptosis in contrast-treated HK-2 cells. Taken together, our data suggest that αKlotho protein protects against CI-AKI through inhibiting NLRP3 inflammasome-mediated pyroptosis, which is likely by promoting autophagy. αKlotho may be a promising therapeutic strategy for CI-AKI.

A single-cell survey of the human glomerulonephritis.

Glomerulonephritis is the one of the major causes of the end-stage kidney disease, whereas the pathological process of glomerulonephritis is still not completely understood. Single-cell RNA sequencing (scRNA-seq) emerges to be a powerful tool to evaluate the full heterogeneity of kidney diseases. To reveal cellular gene expression profiles of glomerulonephritis, we performed scRNA-seq of 2 human kidney transplantation donor samples, 4 human glomerulonephritis samples, 1 human malignant hypertension (MH) sample and 1 human chronic interstitial nephritis (CIN) sample, all tissues were taken from the biopsy. After filtering the cells with < 200 genes and > 10% mitochondria (MT) genes, the resulting 14 932 cells can be divided into 20 cell clusters, consistently with the previous report, in disease samples dramatic immune cells infiltration was found, among which a proximal tubule (PT) subset characterized by wnt-ß catenin activation and a natural killer T (NKT) subset high expressing LTB were found. Furthermore, in the cluster of the podocyte, three glomerulonephritis related genes named FXYD5, CD74 and B2M were found. Compared with the mesangial of donor, the gene CLIC1 and RPS26 were up-regulated in mesangial of IgA nephropathy(IgAN), whereas the gene JUNB was up-regulated in podocyte of IgAN in comparison with that of donor. Meanwhile, some membranous nephropathy (MN) high expressed genes such as HLA-DRB5, HLA-DQA2, IFNG, CCL2 and NR4A2, which involve in highest enrichment pathway, display the cellular-specific expression style, whereas monocyte marker of lupus nephritis (LN) named TNFSF13B was also found and interferon alpha/beta signalling pathway was enriched in B and NKT of LN comparing with donor. By scRNA-seq, we first defined the podocyte markers of glomerulonephritis and specific markers in IgA, MN and LN were found at cellular level. Furthermore, the critical role of interferon alpha/beta signalling pathway was enriched in B and NKT of LN was declared.

Farnesoid X receptor promotes renal ischaemia-reperfusion injury by inducing tubular epithelial cell apoptosis.

PURPOSE: We investigated the role of farnesoid X receptor (FXR), a ligand-dependent transcription factor, in renal ischaemia-reperfusion (I/R) injury. MATERIALS AND METHODS: We performed unilateral renal I/R model in FXR knockout (Fxr-/- ) and wild-type (WT) mice in vivo and a hypoxia-reoxygenation (H/R) model in vitro. The pathways by which FXR induces apoptosis were detected using a proteome profiler array. The effects of FXR on apoptosis were evaluated using immunoblotting, TUNEL assays and flow cytometry. RESULTS: Compared with WT mice, Fxr-/- mice showed improved renal function and reduced tubular injury scores and apoptosis. Consistent with the in vivo results, the silencing of FXR decreased the number of apoptotic HK-2 cells after H/R, while FXR overexpression aggravated apoptosis. Notably, bone marrow transplantation (BMT) and immunohistochemistry experiments revealed the involvement of FXR in the tubular epithelium rather than in inflammatory cells. Furthermore, in vivo and in vitro studies demonstrated that FXR deficiency increased phosphorylated Bcl-2 agonist of cell death (p-Bad) expression levels and the ratio of Bcl-2/Bcl-xL to Bax expression in the kidney. Treatment with wortmannin, which reduced p-Bad expression, inhibited the effects of FXR deficiency and eliminated the tolerance of Fxr-/- mouse kidneys to I/R injury. CONCLUSIONS: These results established the pivotal importance of FXR inactivation in tubular epithelial cells after I/R injury. FXR may promote the apoptosis of renal tubular epithelial cells by inhibiting PI3k/Akt-mediated Bad phosphorylation to cause renal I/R damage.

Inhibiting NLRP3 inflammasome attenuates apoptosis in contrast-induced acute kidney injury through the upregulation of HIF1A and BNIP3-mediated mitophagy.

The pathogenetic mechanism of contrast-induced acute kidney injury (CI-AKI), which is the third most common cause of hospital-acquired AKI, has not been elucidated. Previously, we demonstrated that renal injury and cell apoptosis were attenuated in nlrp3 knockout CI-AKI mice. Here, we investigated the mechanism underlying NLRP3 inhibition-mediated attenuation of apoptosis in CI-AKI. The RNA sequencing analysis of renal cortex revealed that the nlrp3 or casp1 knockout CI-AKI mice exhibited upregulated cellular response to hypoxia, mitochondrial oxidation, and autophagy when compared with the wild-type (WT) CI-AKI mice, which indicated that NLRP3 inflammasome inhibition resulted in the upregulation of hypoxia signaling pathway and mitophagy. The nlrp3 or casp1 knockout CI-AKI mice and iohexol-treated HK-2 cells with MCC950 pretreatment exhibited upregulated levels of HIF1A, BECN1, BNIP3, and LC3B-II, as well as enhanced colocalization of LC3B with BNIP3 and mitochondria, and colocalization of mitochondria with lysosomes. Additionally, roxadustat, a HIF prolyl-hydroxylase inhibitor, protected the renal tubular epithelial cells against iohexol-induced injury through stabilization of HIF1A and activation of downstream BNIP3-mediated mitophagy in vivo and in vitro. Moreover, BNIP3 deficiency markedly decreased mitophagy, and also significantly exacerbated apoptosis and renal injury. This suggested the protective function of BNIP3-mediated mitophagy in CI-AKI. This study elucidated a novel mechanism in which NLRP3 inflammasome inhibition attenuated apoptosis and upregulated HIF1A and BNIP3-mediated mitophagy in CI-AKI. Additionally, this study demonstrated the potential applications of MCC950 and roxadustat in clinical CI-AKI treatment.Abbreviations: BNIP3: BCL2/adenovirus E1B interacting protein 3; Ctrl: control; DAPI: 4',6-diamidino-2-phenylindole dihydrochloride; EGLN2/PHD1: egl-9 family hypoxia-inducible factor 2; HIF1A: hypoxia inducible factor 1, alpha subunit; H-E: hematoxylin and eosin; IL18: interleukin 18; IL1B: interleukin 1 beta; LAMP1: lysosomal-associated membrane protein 1; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; mRNA: messenger RNA; NFKB/NF-κB: nuclear factor of kappa light polypeptide gene enhancer in B cells; NLRP3: NLR family, pyrin domain containing 3; NS: normal saline; PRKN/Parkin: parkin RBR E3 ubiquitin protein ligase; PINK1: PTEN induced putative kinase 1; RNA: ribonucleic acid; SEM: standard error of the mean; siRNA: small interfering RNA; TEM: transmission electron microscopy; TUBA/α-tubulin: tubulin, alpha; TUNEL: terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling; VDAC: voltage-dependent anion channel; WT: wild-type.

Integrated Analysis of m6A Methylome in Cisplatin-Induced Acute Kidney Injury and Berberine Alleviation in Mouse.

BACKGROUND: N6-methyladenosine (m6A) is the most abundant modification known in mRNAs. It participates in a variety of physiological and pathological processes, such as metabolism, inflammation, and apoptosis. AIMS: To explore the mechanism of m6A in cisplatin-induced acute kidney injury (AKI) and berberine alleviation in mouse. METHODS: This study investigated the N6-methyladenosine (m6A) methylome of kidneys from three mouse groups: C57 mice (controls), those with CI-AKI (injury group, IG), and those pretreated with berberine (treatment group, TG). Methylated RNA Immunoprecipitation Next Generation Sequencing (MeRIP-seq) and RNA-seq were performed to identify the differences between the injury group and the control group (IvC) and between the treatment group and the injury group (TvI). Western blotting was performed to identify the protein levels of candidate genes. RESULTS: In IvC, differentially methylated genes (DMGs) were enriched in metabolic processes and cell death. In TvI, DMGs were enriched in tissue development. Several genes involved in important pathways related to CI-AKI showed opposite methylation and expression trends in the IvC and TvI comparisons. CONCLUSION: m6A plays an important role in cisplatin induced AKI and berberine may alleviate this process.

Improving Prognostic and Chronicity Evaluation of Chronic Kidney Disease with Contrast-Enhanced Ultrasound Index-Derived Peak Intensity.

The capability of contrast-enhanced ultrasound (CEUS) to assess the prognosis and chronicity of chronic kidney disease (CKD) was evaluated in patients diagnosed with CKD in 2014 at Ren Ji Hospital, Shanghai, China. Time-intensity curves and quantitative indexes were created using QLab quantification software. Kidney biopsies were analyzed with α-smooth muscle actin immunohistochemistry. According to the renal chronicity score, patients were divided into four groups: minimal (n = 14), mild (n = 73), moderate (n = 49) and severe (n = 31). Multivariate logistic regression analysis revealed that the derived peak intensity (DPI) was independently associated with the renal chronicity score. Of 167 CKD patients (median follow-up: 30.4 ± 18.7 mo), 31 (18.6%) exhibited CKD progression, with a decline in the glomerular filtration rate of more than 25% or end-stage renal disease. Multivariate Cox regression analysis revealed that a lower DPI was independently associated with CKD progression. This study indicates that DPI is a reliable CEUS parameter for evaluating chronic renal changes and an independent prognostic factor of CKD.

Inhibiting pannexin-1 alleviates sepsis-induced acute kidney injury via decreasing NLRP3 inflammasome activation and cell apoptosis.

AIMS: Sepsis-induced acute kidney injury (SI-AKI) is the fifth most common cause of hospital-acquired acute kidney injury. Pannexin1 (Panx1) triggers inflammation and apoptosis which act as crucial factors in the pathogenesis of SI-AKI. We aimed to investigate the expression of Panx1 and its role on the inflammation and apoptosis in SI-AKI. MATERIALS AND METHODS: SI-AKI model was established by lipopolysaccharide (LPS) injection in mice and LPS-treated HK-2 cells in vitro. Panx1 was inhibited by pretreating with carbenoxolone (CBX) or small interfering RNA in vivo and vitro, respectively. The expression of Panx1 was determined by qPCR, western blot and immunohistochemistry (IHC). Kidney damage was evaluated by kidney function, histopathological examination and AKI biomarkers. Inflammatory cytokines were detected by qPCR and ELISA. Apoptosis was detected by TUNEL staining and the expression of apoptosis-related proteins. The activation of nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome was measured by western blot. KEY FINDINGS: Panx1 increased in LPS-induced SI-AKI mice and HK-2 cells, as well as in SI-AKI patients. CBX alleviated the renal function and pathological damage, as well as decreased the mRNA of kidney injury molecule (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL). Inhibiting Panx1 decreased the production of IL-1ß, IL-6 and TNF-α, as well as tubular cell apoptosis in SI-AKI. Inhibiting Panx1 suppressed inflammatory cytokines and apoptosis via inhibiting NLRP3 inflammasome activation and regulating apoptotic protein Bax and Bcl2 expression, respectively. SIGNIFICANCE: These observations suggest that pharmacological inhibition of Panx1 might be a potential approach in the clinical therapy of SI-AKI.