[Construction of a mouse model of type 2 diabetes induced by high fat diet alone and evaluation of pathological changes].

The purpose of the present study was to investigate the modeling time of type 2 diabetes mellitus (T2DM) mouse model induced by high fat diet (HFD) alone and the effects of HFD on the pathology and function of organs related to glucose and lipid metabolism. C57BL/6 mice were fed with normal diet (NC group) or HFD (HFD group). The time of successful T2DM modeling was evaluated by measuring body weight, fasting blood glucose and glucose tolerance at time points of 0, 4, 8, 12, 16 and 20 weeks. The functional and pathological changes of glucose and lipid metabolism related organs were evaluated by detecting insulin tolerance, plasma lipid levels, vascular function, as well as HE staining of pancreas and liver. The results showed that compared with the NC group, the HFD group had significantly increased body weight after 8 weeks of HFD. After 16 weeks of HFD, the HFD group exhibited impaired fasting glucose tolerance. After 20 weeks of HFD, the HFD group mice reached diabetic state, showing impaired glucose tolerance and insulin resistance, islet volume reduction and vacuolar degeneration; Large number of lipid droplets appeared in liver cells, and the level of AMPK phosphorylation in liver tissue was significantly increased in the HFD groups, compared with the NC group; There was endothelial dependent diastolic dysfunction in the thoracic aorta of the HFD group; Compared with the NC group, the HFD group mice showed a significant increase in urinary protein levels. These results suggest that T2DM mouse model can be successfully established by HFD induction alone for 20 weeks. The model is characterized by insulin resistance, fatty liver, hyperlipidemia, vascular dysfunction, renal dysfunction and pathological changes of islet and liver cells, which are similar to those of T2DM patients. Therefore it can be used as an ideal animal model for T2DM research.

High-Frequency Discrete-Interval Binary Sequence in Asynchronous C-VEP-Based BCI for Visual Fatigue Reduction.

In code-modulated visual evoked potential (c-VEP) based BCI systems, flickering visual stimuli may result in visual fatigue. Thus, we introduced a discrete-interval binary sequence (DIBS) as visual stimulus modulation, with its power spectrum optimized to emphasize high-frequency components (40 Hz-60 Hz). 8 and 17 subjects participated, respectively, in offline and online experiments on a 4-target asynchronous c-VEP-based BCI system designed to realize a high positive predictive value (PPV), a low false positive rate (FPR) during idle states, and a high true positive rate (TPR) in control states, while minimizing visual fatigue level. Two visual stimuli modulations were introduced and compared: a maximum length sequence (m-sequence) and the high-frequency discrete-interval binary sequence (DIBS). The decoding algorithm was compared among the canonical correlation analysis (CCA), the task-related component analysis (TRCA), and two approaches of sub-band component weight calculation (the traditional method and the proportional method) for FBCCA and FBTRCA. In the online experiments, the average PPV, FPR and TPR achieved, respectively [Formula: see text], [Formula: see text], [Formula: see text] with m-sequence, while [Formula: see text], [Formula: see text] and [Formula: see text] with DIBS. Estimated by objective eye-related metrics and a subjective questionnaire, the visual fatigue in DIBS cases is significantly smaller than that in m-sequence cases. In this study, the feasibility of a novel modulation approach for visual fatigue reduction was proved in an asynchronous c-VEP system, while maintaining comparable performance to existing methods, which provides further insights towards enhancing this field's long-term viability and user-friendliness.

Loss of MTX2 causes mitochondrial dysfunction, podocyte injury, nephrotic proteinuria and glomerulopathy in mice and patients.

Proteinuria is a common and important clinical manifestation of chronic kidney disease (CKD) and an independent risk factor for the progression of kidney disease. As a component of the glomerular filtration barrier (GFB), podocyte plays a key role in the pathogenesis of glomerular diseases and proteinuria. However, the pathophysiology of glomerular diseases associated with mitochondrial function is incompletely understood. Here, we identified three novel mutations in MTX2, encoding a membrane protein in mitochondria, associated with multisystem manifestations including nephrotic proteinuria and kidney injury in two Chinese patients. Conditional podocyte-specific Mtx2 knockout (Pod-Mtx2-KO) mice present a series of podocyte and glomerular abnormalities from 8 weeks to old age, including microalbuminuria, glomerular mesangial hyperplasia, fusion and effacement of foot process. MTX2 deficiency impaired podocyte functions in vitro, manifested by reductions of adhesion, migration and endocytosis, which were further restored by overexpression of MTX2. Moreover, MTX2 defects led to abnormal mitochondrial structure and dysfunction, evidenced with defects of complex I and III, increased production of reactive oxygen species (ROS), and decreased protein levels of Sam50-CHCHD3-Mitofilin axis in the mitochondrial intermembrane space bridging (MIB) complex which is responsible for maintaining mitochondrial cristae morphology. Collectively, these findings reveal that the normal expression of MTX2 in glomerulus plays an important role in the adhesion, migration, endocytosis, proliferation and other physiological functions of podocytes, which may be realized by maintaining the morphological structure and function of mitochondria. Abnormal expression of MTX2 can lead to mitochondrial dysfunction and structural abnormalities by Sam50-CHCHD3-Mitofilin axis in podocyte, which further induces podocyte injury, glomerular lesions and proteinuria.

Genome-wide multimediator analyses using the generalized Berk-Jones statistics with the composite test.

MOTIVATION: Mediation analysis is performed to evaluate the effects of a hypothetical causal mechanism that marks the progression from an exposure, through mediators, to an outcome. In the age of high-throughput technologies, it has become routine to assess numerous potential mechanisms at the genome or proteome scales. Alongside this, the necessity to address issues related to multiple testing has also arisen. In a sparse scenario where only a few genes or proteins are causally involved, conventional methods for assessing mediation effects lose statistical power because the composite null distribution behind this experiment cannot be attained. The power loss hence decreases the true mechanisms identified after multiple testing corrections. To fairly delineate a uniform distribution under the composite null, Huang (Genome-wide analyses of sparse mediation effects under composite null hypotheses. Ann Appl Stat 2019a;13:60-84; AoAS) proposed the composite test to provide adjusted P-values for single-mediator analyses. RESULTS: Our contribution is to extend the method to multimediator analyses, which are commonly encountered in genomic studies and also flexible to various biological interests. Using the generalized Berk-Jones statistics with the composite test, we proposed a multivariate approach that favors dense and diverse mediation effects, a decorrelation approach that favors sparse and consistent effects, and a hybrid approach that captures the edges of both approaches. Our analysis suite has been implemented as an R package MACtest. The utility is demonstrated by analyzing the lung adenocarcinoma datasets from The Cancer Genome Atlas and Clinical Proteomic Tumor Analysis Consortium. We further investigate the genes and networks whose expression may be regulated by smoking-induced epigenetic aberrations. AVAILABILITY AND IMPLEMENTATION: An R package MACtest is available on https://github.com/roqe/MACtest.

Endothelial FIS1 DeSUMOylation Protects Against Hypoxic Pulmonary Hypertension.

BACKGROUND: Hypoxia is a major cause and promoter of pulmonary hypertension (PH), a representative vascular remodeling disease with poor prognosis and high mortality. However, the mechanism underlying how pulmonary arterial system responds to hypoxic stress during PH remains unclear. Endothelial mitochondria are considered signaling organelles on oxygen tension. Results from previous clinical research and our studies suggested a potential role of posttranslational SUMOylation (small ubiquitin-like modifier modification) in endothelial mitochondria in hypoxia-related vasculopathy. METHODS: Chronic hypoxia mouse model and Sugen/hypoxia rat model were employed as PH animal models. Mitochondrial morphology and subcellular structure were determined by transmission electron and immunofluorescent microscopies. Mitochondrial metabolism was determined by mitochondrial oxygen consumption rate and extracellular acidification rate. SUMOylation and protein interaction were determined by immunoprecipitation. RESULTS: The involvement of SENP1 (sentrin-specific protease 1)-mediated SUMOylation in mitochondrial remodeling in the pulmonary endothelium was identified in clinical specimens of hypoxia-related PH and was verified in human pulmonary artery endothelial cells under hypoxia. Further analyses in clinical specimens, hypoxic rat and mouse PH models, and human pulmonary artery endothelial cells and human embryonic stem cell-derived endothelial cells revealed that short-term hypoxia-induced SENP1 translocation to endothelial mitochondria to regulate deSUMOylation (the reversible process of SUMOylation) of mitochondrial fission protein FIS1 (mitochondrial fission 1), which facilitated FIS1 assembling with fusion protein MFN2 (mitofusin 2) and mitochondrial gatekeeper VDAC1 (voltage-dependent anion channel 1), and the membrane tethering activity of MFN2 by enhancing its oligomerization. Consequently, FIS1 deSUMOylation maintained the mitochondrial integrity and endoplasmic reticulum-mitochondria calcium communication across mitochondrial-associated membranes, subsequently preserving pulmonary endothelial function and vascular homeostasis. In contrast, prolonged hypoxia disabled the FIS1 deSUMOylation by diminishing the availability of SENP1 in mitochondria via inducing miR (micro RNA)-138 and consequently resulted in mitochondrial dysfunction and metabolic reprogramming in pulmonary endothelium. Functionally, introduction of viral-packaged deSUMOylated FIS1 within pulmonary endothelium in mice improved pulmonary endothelial dysfunction and hypoxic PH development, while knock-in of SUMO (small ubiquitin-like modifier)-conjugated FIS1 in mice exaggerated the diseased cellular and tissue phenotypes. CONCLUSIONS: By maintaining endothelial mitochondrial homeostasis, deSUMOylation of FIS1 adaptively preserves pulmonary endothelial function against hypoxic stress and consequently protects against PH. The FIS1 deSUMOylation-SUMOylation transition in pulmonary endothelium is an intrinsic pathogenesis of hypoxic PH.

STING promotes ferroptosis through NCOA4-dependent ferritinophagy in acute kidney injury.

Ferroptosis in tubules has been implicated in the pathogenesis of acute kidney injury (AKI), whereas the regulatory mechanism remains unclear. The stimulator of interferon genes (STING) is previously recognized as a critical mediator of innate immunity via a DNA-sensing pathway and has been increasingly linked to lipid peroxidation, a hallmark of ferroptosis. Herein we investigated the role and the underlying mechanism of STING in AKI models established by ischemia/reperfusion (IR) in C57BL mice. The expression level of STING was predominantly increased in tubules of kidney after IR treatment. Besides, STING deficiency markedly alleviated IR-induced lipid peroxidation, tissue damage and renal dysfunction. Consistently, in vitro experiments demonstrated that the increase in ferroptotic cell death, lipid ROS production and the decrease in GSH peroxidase 4 (GPX4) expression in renal tubular cells subjected to ferroptosis agonist or hypoxia/reoxygenation intervention were all mitigated by genetic deficiency or pharmacological inhibition of STING, while all exacerbated by STING overexpression. Further, these detrimental effects of STING overexpression relied on the induction of ferritinophagy, i.e. autophagic degradation of ferritin, leading to iron overload. Mechanistically, STING mediated the initiation of ferritinophagy through interacting with nuclear receptor coactivator 4 (NCOA4), a fundamental receptor for the transfer of ferritin into lysosome. Collectively, STING contributes to ferroptosis during ischemic AKI through facilitating NCOA4-mediated ferritinophagy and shows the potential as a promising therapeutic choice for AKI.

Proteomics analyses of acute kidney injury biomarkers in a rat exertional heat stroke model.

The frequency of exertional heat stroke (EHS) increases with the gradual elevation of global temperatures during summer. Acute kidney injury (AKI) is a common complication of EHS, and its occurrence often indicates the worsening of a patient's condition or a poor prognosis. In this study, a rat model of AKI caused by EHS was established, and the reliability of the model was evaluated by HE staining and biochemical assays. The expression of kidney tissue proteins in the EHS rats was analyzed using label-free liquid chromatography-tandem mass spectrometry. A total of 3,129 differentially expressed proteins (DEPs) were obtained, and 10 key proteins were finally identified, which included three upregulated proteins (Ahsg, Bpgm, and Litaf) and seven downregulated proteins (medium-chain acyl-CoA synthetase 2 (Acsm2), Hadha, Keg1, Sh3glb1, Eif3d, Ambp, and Ddah2). The qPCR technique was used to validate these 10 potential biomarkers in rat kidney and urine. In addition, Acsm2 and Ahsg were double-validated by Western blotting. Overall, this study identified 10 reliable biomarkers that may provide potential targets for the treatment of AKI caused by EHS.

Dihydromyricetin attenuates cisplatin-induced acute kidney injury by reducing oxidative stress, inflammation and ferroptosis.

BACKGROUND: Cisplatin is effective against various types of cancers. However, its clinical application is limited owing to its adverse effects, especially acute kidney injury (AKI). Dihydromyricetin (DHM), a flavonoid derived from Ampelopsis grossedentata, has varied pharmacological activities. This research aimed to determine the molecular mechanism for cisplatin-induced AKI. METHODS: A murine model of cisplatin-induced AKI (22 mg/kg, I.P.) and a HK-2 cell model of cisplatin-induced damage (30 µM) were established to evaluate the protective function of DHM. Renal dysfunction markers, renal morphology and potential signaling pathways were investigated. RESULTS: DHM decreased the levels of renal function biomarkers (blood urea nitrogen and serum creatinine), mitigated renal morphological damage, and downregulated the protein levels of kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin. It upregulated the expression levels of antioxidant enzymes (superoxide dismutase and catalase expression), nuclear factor-erythroid-2-related factor 2 (Nrf2) and its downstream proteins, including heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic (GCLC) and modulatory (GCLM) subunits, thus eventually reducing cisplatin-induced reactive oxygen species (ROS) production. Moreover, DHM partially inhibited the phosphorylation of the active fragments of caspase-8 and -3 and mitogen-activated protein kinase and restored glutathione peroxidase 4 expression, which attenuated renal apoptosis and ferroptosis in cisplatin-treated animals. DHM also mitigated the activation of NLRP3 inflammasome and nuclear factor (NF)-κB, attenuating the inflammatory response. In addition, it reduced cisplatin-induced HK-2 cell apoptosis and ROS production, both of which were blocked by the Nrf2 inhibitor ML385. CONCLUSIONS: DHM suppressed cisplatin-induced oxidative stress, inflammation and ferroptosis probably through regulating of Nrf2/HO-1, MAPK and NF-κB signaling pathways.

Piezo1 Mediates Vasodilation Induced by Acute Hyperglycemia in Mouse Renal Arteries and Microvessels.

BACKGROUND: Acute hyperglycemia is a risk factor for developing acute kidney injury and poor renal outcome in critically ill patients, whereby the role of renal vasculature remains unclear. We hypothesize that hyperglycemia-associated hyperosmolarity facilitates vasodilation through Piezo1-mediated eNOS (endothelial NO synthase) activation. METHODS: Vasoreactivity was analyzed using wire myography in isolated mouse mesenteric arteries and renal interlobar, and using microvascular perfusion in renal afferent arterioles and efferent arterioles, and vasa recta. Immunofluorescence and Western blot were used for molecular analyses of isolated mouse blood vessels and human umbilical vein endothelial cells. RESULTS: Pretreatment with hyperglycemia (44 mmol/L glucose; 4 hours) increased acetylcholine-induced relaxation in interlobar arteries and mesenteric arteries, which was prevented by eNOS inhibition using Nω-nitro-L-arginine methylester hydrochloride. Hyperosmotic mannitol solution had a similar effect. Hyperglycemia induced an immediate, Nω-nitro-L-arginine methylester hydrochloride-inhibitable dilation in afferent arterioles, efferent arterioles, and vasa recta, whereby stronger dilation in afferent arterioles compared to efferent arterioles. Hyperglycemia also increased glomerular filtration rate in mice. In human umbilical vein endothelial cells, hyperglycemia, and the Piezo1 activator Yoda-1 increased levels of Piezo1 protein, p-CaMKII (phosphorylated Ca2+/Calmodulin-dependent protein kinase type II), Akt (protein kinase B), and p-eNOS (phosphorylated eNOS). The hyperglycemia effect could be prevented by inhibiting Piezo1 using GsMTx4 (Grammostola spatulata mechanotoxin 4) and CaMKII using KN93 (N-[2-[[[3-(4-Chlorophenyl)-2-propenyl]-methylamino]-methyl]-phenyl]-N-(2-hydroxyethyl)-4-methoxybenzenesulphonamide). Furthermore, in arteries and microvessels, inhibition of Piezo1 using GsMTx4 prevented the hyperglycemia -effect, while Yoda-1 caused relaxation and dilation, respectively. CONCLUSIONS: Results reveal that Piezo1 mediates renal vasodilation induced by hyperosmolarity in acute hyperglycemia. This mechanism may contribute to the pathogenesis of renal damage by acute hyperglycemia.

Hypertension as a Novel Link for Shared Heritability in Age at Menarche and Cardiometabolic Traits.

CONTEXT: Extremely early age at menarche, also called precocious puberty, has been associated with various cardiometabolic traits, but their shared heritability remains unclear. OBJECTIVES: This work aimed to identify new shared genetic variants and their pathways for age at menarche and cardiometabolic traits and to investigate the influence of central precocious puberty on childhood cardiometabolic traits. METHODS: Using the conjunction false discovery rate method, this study analyzed genome-wide association study data from the menarche-cardiometabolic traits among 59 655 females of Taiwanese ancestry and systemically investigated pleiotropy between age at menarche and cardiometabolic traits. To support the novel hypertension link, we used the Taiwan Puberty Longitudinal Study (TPLS) to investigate the influence of precocious puberty on childhood cardiometabolic traits. RESULTS: We discovered 27 novel loci, with an overlap between age at menarche and cardiometabolic traits, including body fat and blood pressure. Among the novel genes discovered, SEC16B, CSK, CYP1A1, FTO, and USB1 are within a protein interaction network with known cardiometabolic genes, including traits for obesity and hypertension. These loci were confirmed through demonstration of significant changes in the methylation or expression levels of neighboring genes. Moreover, the TPLS provided evidence regarding a 2-fold higher risk of early-onset hypertension that occurred in girls with central precocious puberty. CONCLUSION: Our study highlights the usefulness of cross-trait analyses for identifying shared etiology between age at menarche and cardiometabolic traits, especially early-onset hypertension. The menarche-related loci may contribute to early-onset hypertension through endocrinological pathways.

The Role of Macula Densa Nitric Oxide Synthase 1 Beta Splice Variant in Modulating Tubuloglomerular Feedback.

Abnormalities in renal electrolyte and water excretion may result in inappropriate salt and water retention, which facilitates the development and maintenance of hypertension, as well as acid-base and electrolyte disorders. A key mechanism by which the kidney regulates renal hemodynamics and electrolyte excretion is via tubuloglomerular feedback (TGF), an intrarenal negative feedback between tubules and arterioles. TGF is initiated by an increase of NaCl delivery at the macula densa cells. The increased NaCl activates luminal Na-K-2Cl cotransporter (NKCC2) of the macula densa cells, which leads to activation of several intracellular processes followed by the production of paracrine signals that ultimately result in a constriction of the afferent arteriole and a tonic inhibition of single nephron glomerular filtration rate. Neuronal nitric oxide (NOS1) is highly expressed in the macula densa. NOS1ß is the major splice variant and accounts for most of NO generation by the macula densa, which inhibits TGF response. Macula densa NOS1ß-mediated modulation of TGF responses plays an essential role in control of sodium excretion, volume and electrolyte hemostasis, and blood pressure. In this article, we describe the mechanisms that regulate macula densa-derived NO and their effect on TGF response in physiologic and pathologic conditions. © 2023 American Physiological Society. Compr Physiol 13:4215-4229, 2023.

Genotype-Phenotype Correlation Reanalysis in 83 Chinese Cases with OCRL Mutations.

Background: Both Lowe syndrome and Dent-2 disease are caused by variants in the OCRL gene. However, the reason why patients with similar OCRL gene mutations presented with different phenotypes remains uncertain. Methods: Children with hemizygous pathogenic or likely pathogenic variants in OCRL were compiled from published and unpublished consecutive cases from China. Furthermore, a Chi-square test was employed to analyze the correlation of the location and types of mutations on the phenotype of children with Lowe syndrome or Dent-2 disease. Results: Among the total 83 patients, 70.8% (34/48) cases of Lowe syndrome presented with truncating mutations, while only 31.4% (11/35) cases of Dent-2 disease presented with truncating mutation (Χ2 = 12.662; P < 0.001). Meanwhile, the majority of mutations in Dent-2 disease are located in Exon 2-12 (21/35, 60.0%), while the majority of mutations in Lowe syndrome are located in Exon 13-23 (39/48, 81.3%; Χ2 = 14.922; P < 0.001). Conclusions: Truncating mutations of the OCRL gene were more common in patients with Lowe syndrome than in Dent-2 disease, while mutation is more likely located at exon 2-12 in Dent-2 disease than that in Lowe syndrome. The type and location of mutation are important indicators for the phenotypes in patients with OCRL mutation. This is a large cohort study analyzing the genotype-phenotype correlation in patients with Lowe syndrome and Dent-2 disease in China. Our data may improve the interpretation of new OCRL variants and genetic counseling. Furthermore, a large international study would be necessary to illustrate the genotype-phenotype correlation in patients with OCRL mutations.

Tacrolimus Causes Hypertension by Increasing Vascular Contractility via RhoA (Ras Homolog Family Member A)/ROCK (Rho-Associated Protein Kinase) Pathway in Mice.

BACKGROUND: To provide tacrolimus is first-line treatment after liver and kidney transplantation. However, hypertension and nephrotoxicity are common tacrolimus side effects that limit its use. Although tacrolimus-related hypertension is well known, the underlying mechanisms are not. Here, we test whether tacrolimus-induced hypertension involves the RhoA (Ras homolog family member A)/ROCK (Rho-associated protein kinase) pathway in male C57Bl/6 mice. METHODS: Intra-arterial blood pressure was measured under anesthesia. The reactivity of renal afferent arterioles and mesenteric arteries were assessed in vitro using microperfusion and wire myography, respectively. RESULTS: Tacrolimus induced a transient rise in systolic arterial pressure that was blocked by the RhoA/ROCK inhibitor Fasudil (12.0±0.9 versus 3.2±0.7; P<0.001). Moreover, tacrolimus reduced the glomerular filtration rate, which was also prevented by Fasudil (187±20 versus 281±8.5; P<0.001). Interestingly, tacrolimus enhanced the sensitivity of afferent arterioles and mesenteric arteries to Ang II (angiotensin II), likely due to increased intracellular Ca2+ mobilization and sensitization. Fasudil prevented increased Ang II-sensitivity and blocked Ca2+ mobilization and sensitization. Preincubation of mouse aortic vascular smooth muscle cells with tacrolimus activated the RhoA/ROCK/MYPT-1 (myosin phosphatase targeting subunit 1) pathway. Further, tacrolimus increased cytoplasmic reactive oxygen species generation in afferent arterioles (107±5.9 versus 163±6.4; P<0.001) and in cultured mouse aortic vascular smooth muscle cells (100±7.5 versus 160±23.2; P<0.01). Finally, the reactive oxygen species scavenger Tempol inhibited tacrolimus-induced Ang II hypersensitivity in afferent arterioles and mesenteric arteries. CONCLUSIONS: The RhoA/ROCK pathway may play an important role in tacrolimus-induced hypertension by enhancing Ang II-specific vasoconstriction, and reactive oxygen species may participate in this process by activating the RhoA/ROCK pathway.

A critical role of the podocyte cytoskeleton in the pathogenesis of glomerular proteinuria and autoimmune podocytopathies.

Selective glomerular filtration relies on the membrane separating the glomerular arterioles from the Bowman space. As a major component of the glomerular filtration barrier, podocytes form foot processes by the actin cytoskeleton, which dynamically adjusts in response to environmental changes to maintain filtration barrier integrity. The slit diaphragms bridge the filtration slits between neighboring foot processes and act as signaling hubs interacting with the actin cytoskeleton. Focal adhesions relay signals to regulate actin dynamics while allowing podocyte adherence to the basement membrane. Mutations in actin regulatory and signaling proteins may disrupt the actin cytoskeleton, resulting in foot process retraction, effacement, and proteinuria. Large-scale gene expression profiling platforms, transgenic animal models, and other in vivo gene delivery methods now enhance our understanding of the interactions among podocyte focal adhesions, slit diaphragms, and actin dynamics. In addition, our team found that at least 66% of idiopathic nephrotic syndrome (INS) children have podocyte autoantibodies, which was defined as a new disease subgroup-, autoimmune podocytopathies. This review outlines the pathophysiological mechanisms of podocyte cytoskeleton protein interactions in proteinuria and glomerular podocytopathy.

Heteroplasmic and homoplasmic m.616T>C in mitochondria tRNAPhe promote isolated chronic kidney disease and hyperuricemia.

Inherited kidney diseases are the fifth most common cause of end-stage renal disease (ESRD). Mitochondrial dysfunction plays a vital role in the progression of inherited kidney diseases, while mitochondrial-transfer RNA (mt-tRNA) variants and their pathogenic contributions to kidney disease remain largely unclear. In this study, we identified the pathogenic mt-tRNAPhe 616T>C mutation in 3 families and documented that m.616T>C showed a high pathogenic threshold, with both heteroplasmy and homoplasmy leading to isolated chronic kidney disease and hyperuricemia without hematuria, proteinuria, or renal cyst formation. Moreover, 1 proband with homoplamic m.616T>C presented ESRD as a child. No symptoms of nervous system evolvement were observed in these families. Lymphoblast cells bearing m.616T>C exhibited swollen mitochondria, underwent active mitophagy, and showed respiratory deficiency, leading to reduced mitochondrial ATP production, diminished membrane potential, and overproduction of mitochondrial ROS. Pathogenic m.616T>C abolished a highly conserved base pair (A31-U39) in the anticodon stem-loop which altered the structure of mt-tRNAPhe, as confirmed by a decreased melting temperature and slower electrophoretic mobility of the mutant tRNA. Furthermore, the unstable structure of mt-tRNAPhe contributed to a shortage of steady-state mt-tRNAPhe and enhanced aminoacylation efficiency, which resulted in impaired mitochondrial RNA translation and a significant decrease in mtDNA-encoded polypeptides. Collectively, these findings provide potentially new insights into the pathogenesis underlying inherited kidney disease caused by mitochondrial variants.

Captopril related kidney damage: renal afferent arteriolar responses to angiotensin II and inflammatory signaling.

Captopril can have nephrotoxic effects, which are largely attributed to accumulated renin and "escaped" angiotensin II (Ang II). Here we test whether angiotensin converting enzyme-1 (ACE1) inhibition damages kidneys via alteration of renal afferent arteriolar responses to Ang II and inflammatory signaling. C57Bl/6 mice were given vehicle or captopril (60 mg/kg per day) for four weeks. Hypertension was obtained by minipump supplying Ang II (400 ng/kg per min) during the second 2 weeks. We assessed kidney histology by periodic acid-Schiff (PAS) and Masson staining, glomerular filtration rate (GFR) by FITC-labeled inulin clearance, and responses to Ang II assessed in afferent arterioles in vitro. Moreover, arteriolar H2O2 and catalase, plasma renin were assayed by commercial kits, and mRNAs of renin receptor, transforming growth factor-ß (TGF-ß) and cyclooxygenase-2 (COX-2) in the renal cortex, mRNAs of angiotensin receptor-1 (AT1R) and AT2R in the preglomerular arterioles were detected by RT-qPCR. The results showed that, compared to vehicle, mice given captopril showed lowered blood pressure, reduced GFR, increased plasma renin, renal interstitial fibrosis and tubular epithelial vacuolar degeneration, increased expression of mRNAs of renal TGF-ß and COX-2, decreased production of H2O2 and increased catalase activity in preglomerular arterioles and enhanced afferent arteriolar Ang II contractions. The latter were blunted by incubation with H2O2. The mRNAs of renal microvascular AT1R and AT2R remained unaffected by captopril. Ang II-infused mice showed increased blood pressure and reduced afferent arteriolar Ang II responses. Administration of captopril to the Ang II-infused mice normalized blood pressure, but not arteriolar Ang II responses. We conclude that inhibition of ACE1 enhances renal microvascular reactivity to Ang II and may enhance important inflammatory pathways.

rhADAMTS13 reduces oxidative stress by cleaving VWF in ischaemia/reperfusion-induced acute kidney injury.

AIMS: Acute kidney injury (AKI), a major health burden, lacks effective therapy. Anti-inflammatory actions of a disintegrin and metalloproteinase with a thrombospondin type 1 motif member 13 (ADAMTS13) may provide a new treatment option for AKI. Along with inflammation, oxidative stress is critical for AKI development, yet the impact of ADAMTS13 on oxidative stress in AKI remains to be fully elucidated. METHODS: We assess recombinant human ADAMTS13 (rhADAMTS13) actions on oxidative stress in a murine ischaemia/reperfusion (IR) model. Antioxidant stress-enzyme activities, renal morphology, kidney function markers and vascular function of isolated afferent arterioles are quantified. RESULTS: rhADAMTS13 provided after IR, reduces blood urea nitrogen (BUN) by 33% and serum creatinine (Scr) by 73% in 24 hours post-IR. rhADAMTS13 reduces BUN (40.03 ± 20.34 mmol/L vs 72.35 ± 18.74 mmol/L, P < .01), Scr (75.67 ± 51.19 µmol/L vs 176.17 ± 55.38 µmol/L, P < .01) and proteinuria by 41% in 48 hours post-IR as well. Moreover, rhADAMTS13 administration decreases malondialdehyde (MDA) and increases the activity of antioxidant stress enzymes, and attenuates reactive oxygen species production. rhADAMTS13 also upregulates nuclear factor-erythroid-2-related factor 2/haem oxygenase-1, enhances antioxidant enzymes activity and alleviates endothelial dysfunction. Finally, treatment with rhADAMTS13 mitigates severe functional and morphological injury present in IR mice. Extracellular signal-regulated kinase (ERK) phosphorylation is limited by rhADAMTS13 and PPARγ expression is partly restored in ischaemic kidneys. Co-administration of von Willebrand factor (VWF) impairs rhADAMTS13's antioxidant capacity and its protective role in IR. CONCLUSION: rhADAMTS13 alleviates renal IR injury through antioxidant effects by cleaving VWF.

Long-term predialysis blood pressure variability and outcomes in hemodialysis patients.

Blood pressure variability (BPV) is significantly associated with cardiovascular diseases (CVD) and mortality in hemodialysis patients. However, the relationship between blood pressure and CVD in hemodialysis patients is complex and affected by many factors. The present study aimed to assess the association of long-term predialysis BPV with all-cause mortality and major adverse cardiovascular events (MACE). One thousand seven hundred twenty-seven patients receiving maintenance hemodialysis were recruited in nine hemodialysis centers. Predialysis BPV was assessed over 1-year intervals. Outcomes included all-cause mortality and MACE during follow-up periods. The mean age of the final cohort was 59 years, of which 57% were males. Greater predialysis systolic BPV was associated with an increased risk of all-cause mortality (adjusted hazard ratio, 1.101; 95% confidence intervals 1.064-1.140) and MACE (adjusted hazard ratio, 1.091; 95% confidence intervals 1.059-1.125). Results were similar when systolic BPV was stratified by baseline systolic blood pressure. In conclusion, greater predialysis BPV among hemodialysis patients was associated with all-cause mortality and MACE. Strategies to reduce blood pressure variability might be beneficial for hemodialysis patients.

Trimethylamine N-oxide promotes hyperoxaluria-induced calcium oxalate deposition and kidney injury by activating autophagy.

Calcium oxalate (CaOx) is the most common component of kidney stones. Oxidative stress, inflammation and autophagy-induced cell death are the major causes of CaOx crystal deposition and CaOx crystal deposition can further lead to kidney injury. Trimethylamine N-oxide (TMAO), a gut microbiota-derived metabolite, plays an important role in the pathogenesis of many diseases, such as atherosclerosis, diabetes and chronic kidney disease, but the effect of TMAO on hyperoxaluria-induced CaOx crystal deposition and kidney injury remains unknown. We hypothesize that TMAO aggravates CaOx crystal deposition via promoting CaOx-mediated cell death. C57Bl/6 mice were given high-oxalate diet as a model of hyperoxaluria. TMAO was provided via drinking water. Serum TMAO levels increased 15 days after CaOx treatment (6.30 ± 0.17 µmol/L vs. 34.65 ± 8.95 µmol/L). High-oxalate diet induced inflammation, CaOx deposition and kidney injury, which TMAO aggravated. In accordance, TMAO intensified high-oxalate diet induced oxidative stress, autophagy and apoptosis. Moreover, TMAO enhanced CaOx crystal adhesion to HK-2 cells and reduced cell viability (from 88.9 ± 1.6% to 75.0 ± 2.7%). Protein kinase R-like endoplasmic reticulum kinase (PERK) may mediate these TMAO effects, as TMAO promoted PERK phosphorylation. Consistently, PERK knockdown alleviated TMAO-evoked CaOx-autophagy, apoptosis and oxidative stress in HK-2 cells. In conclusion, TMAO can aggravate hyperoxaluria-induced kidney injury by triggering the PERK/ROS pathway, which enhances autophagy, apoptosis and inflammation, and facilitates CaOx crystal deposition in renal tubular cells.