Atrial Natriuretic Peptide (ANP) plays an important role in blood pressure regulation. Low levels of ANP correlate with the development of salt-sensitive hypertension (SS-HTN). Our previous studies indicated that ANP deficiency exacerbated renal function decline in SS-HTN. In the heart and fat tissue, ANP was reported to affect lipid peroxidation and mitochondrial bioenergetics but the effects of ANP on mitochondrial function in the kidney are unexplored. We hypothesized that ANP deficiency in SS-HTN causes renal bioenergetic shift, leading to disruption of mitochondrial network and oxidative stress. To address the hypothesis, we placed Dahl SS wild-type (SSWT) and ANP knockout (SSNPPA-/-) rats on 4% NaCl high salt (HS) diet to induce HTN or maintained them on 0.4% NaCl normal salt (NS) diet and assessed mitochondrial bioenergetics and dynamics using spectrofluorimetry, Seahorse assay, electron paramagnetic resonance (EPR) spectroscopy, Western blotting, electron microscopy, PCR and cytokine assays. We report that under high salt conditions, associated with hypertension and renal damage, the SSNPPA-/- rats exhibit a decrease in mitochondrial membrane potential and elevation in mitochondrial ROS levels compared to SSWT. The redox shift is also evident by the presence of more pronounced medullar lipid peroxidation in the SSNPPA-/- strain. We also revealed fragmented, more damaged mitochondria in the SSNPPA-/- rats, accompanied by increased turnover and biogenesis. Overall, our data indicate that ANP deficiency causes disruptions in mitochondrial bioenergetics and dynamics which likely contributes to aggravation of the renal damage and hypertension in the Dahl SS rat; the major pathological effects are evident in the groups subjected to a combined salt and ANP deficiency-induced mitochondrial stress.

暂无摘要。

Nephrotoxicity, including electrolytic disorders and acute kidney injury (AKI), limits the clinical dosage and utility of platinated antineoplastics such as cisplatin. Cisplatin nephrotoxicity embodies a tubulopathy involving the medullary S2 and S3 segments of the proximal and the distal tubules. Higher dosage extends damage over the cortical S1 segment and intensifies overall injury. However, the standard diagnosis based on plasma creatinine as well as novel injury biomarkers lacks enough pathophysiological specificity. Further granularity in the detection of renal injury would help understand the implications of individual damage patterns needed for personalized patient handling. In this article, we studied the association of urinary ganglioside GM2 activator protein (GM2AP) with the patterns of tubular damage produced by 5 and 10 mg/kg cisplatin in rats. Our results show that GM2AP appears in the urine only following damage to the cortical segment of the proximal tubule. The information provided by GM2AP is not redundant with but distinct and complementary to that provided by urinary neutrophil gelatinase-associated lipocalin (NGAL). Similarly, treatment with 150 mg/kg/day gentamicin damages the renal cortex and increases GM2AP urinary excretion; whereas renal ischemia, which does not affect the cortex, has no effect on GM2AP. Because of the key role of the cortical proximal tubule in renal function, we contend GM2AP as a potential diagnostic biomarker to stratify AKI patients according to the underlying damage and follow their evolution and prognosis. Prospectively, urinary GM2AP may help grade the severity of platinated antineoplastic nephrotoxicity by forming part of a non-invasive liquid biopsy.

ATP6AP2 knockout in the renal nephron impairs receptor-mediated endocytosis, increasing urinary albumin and glucose excretion and impairing weight gain. Nonesterified fatty acids (NEFA) in urine are bound to albumin and reabsorbed in the proximal tubule through receptor-mediated endocytosis by the megalin-cubilin complex. We hypothesized that ATP6AP2 knockout increases urinary NEFA excretion through a reduction in megalin. Ten-week-old male C57BL/6 mice with nephron specific inducible ATP6AP2 knockout and noninduced controls were fed either normal diet (ND 12% fat) or high fat diet (HFD 45% fat) for 6 months. ATP6AP2 knockout significantly increased urine albumin:creatinine ratio in both ND and HFD fed mice while normalized urine NEFA concentration increased 489% and 259% in ND and HFD knockout mice compared to respective controls. Knockout decreased renal cortical megalin mRNA by 47% on ND and 49% on HFD while megalin protein expression decreased by 36% and 44% respectively. At the same time, markers of mTOR activity were increased while autophagy was impaired. Our results indicate that nephron specific ATP6AP2 knockout increases urinary NEFA excretion in the setting of impaired receptor-mediated endocytosis. Further investigation should determine whether ATP6AP2 contributes to obesity related ectopic lipid deposition in the proximal tubule.

Information on the clinical outcomes of feline azotemia using ultrasound examinations is limited. This study aimed to understand the correlation between cortical anisotropy backscattering artifact (CABA) and serum creatinine (sCr) changes in feline azotemia after hospitalization and to investigate whether CABA is useful for predicting the clinical outcome of feline azotemia. Sixty-five hospitalized cats with azotemia, including 49 cats with moderate or severe azotemia (severe group) and 16 cats with mild azotemia (mild group). This retrospective study reviewed the CABA using ultrasound images of cats hospitalized with azotemia between 2016 and 2021. The correlation between CABA and the clinical outcomes of cats with azotemia was investigated using the chi-squared or Fisher\'s exact test, and the intra- and inter-observer agreements in CABA were assessed using McNemar\'s and Cohen\'s kappa tests. The presence of CABA was significantly positively correlated with the clinical outcomes of cats with azotemia only in the severe group (p = 0.0034, odds ratio = 8.57). There was no association between CABA and clinical outcomes in cats with mild azotemia (p = 0.75). CABA can be used for clinical outcome prediction in moderate and severe feline azotemia, with a sensitivity of 80.8% and a specificity of 73.9%. Also, satisfactory intra- and inter-observer agreements were revealed in the detection of CABA during ultrasound image review. Our study demonstrated that cats with moderate and severe azotemia with CABA observed during ultrasonography might have better clinical outcomes. These findings provide additional information on the prognosis and treatment of feline azotemia.

A detailed knowledge of the lipid composition of components of nephrons is crucial for understanding physiological processes and the development of kidney diseases. However, the lipidomic composition of kidney tubular segments is unknown. We manually isolated the proximal convoluted tubule (PCT), the cortical thick ascending limb of Henle\'s loop, and the cortical collecting duct from 5 lean and obese mice and subjected the samples to shotgun lipidomics analysis by high-resolution mass spectrometry acquisition. Across all samples, more than 500 lipid species were identified, quantified, and compared. We observed significant compositional differences among the 3 tubular segments, which serve as true signatures. These intrinsic lipidomic features are associated with a distinct proteomic program that regulates highly specific physiological functions. The distinctive lipidomic features of each of the 3 segments are mostly based on the relative composition of neutral lipids, long-chain polyunsaturated fatty acids, sphingolipids, and ether phospholipids. These features support the hypothesis of a lipotype assigned to specific tubular segments. Obesity profoundly impacts the lipotype of PCT. In conclusion, we present a comprehensive lipidomic analysis of 3 cortical segments of mouse kidney tubules. This valuable resource provides unparalleled detail that enhances our understanding of tubular physiology and the potential impact of pathological conditions.

BACKGROUND: Clinical imaging tools to probe aggressiveness of renal masses are lacking, and T2-weighted imaging as an integral part of magnetic resonance imaging protocol only provides qualitative information. We developed high-resolution and accelerated T2 mapping methods based on echo merging and using k-t undersampling and reduced flip angles (TEMPURA) and tested their potential to quantify differences between renal tumour subtypes and grades.
METHODS: Twenty-four patients with treatment-naïve renal tumours were imaged: seven renal oncocytomas (RO); one eosinophilic/oncocytic renal cell carcinoma; two chromophobe RCCs (chRCC); three papillary RCCs (pRCC); and twelve clear cell RCCs (ccRCC). Median, kurtosis, and skewness of T2 were quantified in tumours and in the normal-adjacent kidney cortex and were compared across renal tumour subtypes and between ccRCC grades.
RESULTS: High-resolution TEMPURA depicted the tumour structure at improved resolution compared to conventional T2-weighted imaging. The lowest median T2 values were present in pRCC (high-resolution, 51 ms; accelerated, 45 ms), which was significantly lower than RO (high-resolution; accelerated, p = 0.012) and ccRCC (high-resolution, p = 0.019; accelerated, p = 0.008). ROs showed the lowest kurtosis (high-resolution, 3.4; accelerated, 4.0), suggestive of low intratumoural heterogeneity. Lower T2 values were observed in higher compared to lower grade ccRCCs (grades 2, 3 and 4 on high-resolution, 209 ms, 151 ms, and 106 ms; on accelerated, 172 ms, 160 ms, and 102 ms, respectively), with accelerated TEMPURA showing statistical significance in comparison (p = 0.037).
CONCLUSIONS: Both high-resolution and accelerated TEMPURA showed marked potential to quantify differences across renal tumour subtypes and between ccRCC grades.
BACKGROUND: ClinicalTrials.gov, NCT03741426 . Registered on 13 November 2018.
CONCLUSIONS: The newly developed T2 mapping methods have improved resolution, shorter acquisition times, and promising quantifiable readouts to characterise incidental renal masses.

OBJECTIVE: Obesity related glomerulopathy (ORG) is induced by obesity, but the pathogenesis remains unclear. This study aims to investigate the expression of early growth response protein 3 (EGR3) in the renal cortex tissues of ORG patients and high-fat diet-induced obese mice, and to further explore the molecular mechanism of EGR3 in inhibiting palmitic acid (PA) induced human podocyte inflammatory damage.
METHODS: Renal cortex tissues were collected from ORG patients (n=6) who have been excluded from kidney damage caused by other diseases and confirmed by histopathology, and from obese mice induced by high-fat diet (n=10). Human and mouse podocytes were intervened with 150 μmol/L PA for 48 hours. EGR3 was overexpressed or silenced in human podocytes. Enzyme linked immunosorbent assay (ELISA) was used to detcet the levels of interleukin-6 (IL-6) and interleukin-1β (IL-1β). Real-time RT-PCR was used to detect the mRNA expressions of EGR3, podocytes molecular markers nephrosis 1 (NPHS1), nephrosis 2 (NPHS2), podocalyxin (PODXL), and podoplanin (PDPN). RNA-seq was performed to detect differentially expressed genes (DEGs) after human podocytes overexpressing EGR3 and treated with 150 μmol/L PA compared with the control group. Co-immunoprecipitation (Co-IP) combined with liquid chromatography tandem mass spectrometry (LC-MS) was used to detect potential interacting proteins of EGR3 and the intersected with the RNA-seq results. Co-IP confirmed the interaction between EGR3 and protein arginine methyltransferases 1 (PRMT1), after silencing EGR3 and PRMT1 inhibitor intervention, the secretion of IL-6 and IL-1β in PA-induced podocytes was detected. Western blotting was used to detect the expression of phosphorylated signal transducer and activator of transcription 3 (p-STAT3) after overexpression or silencing of EGR3.
RESULTS: EGR3 was significantly upregulated in renal cortex tissues of ORG patients and high-fat diet-induced obese mice (both P<0.01). In addition, after treating with 150 μmol/L PA for 48 hours, the expression of EGR3 in human and mouse podocytes was significantly upregulated (both P<0.05). Overexpression or silencing of EGR3 in human podocytes inhibited or promoted the secretion of IL-6 and IL-1β in the cell culture supernatant after PA intervention, respectively, and upregulated or downregulated the expression of NPHS1, PODXL, NPHS2,and PDPN (all P<0.05). RNA-seq showed a total of 988 DEGs, and Co-IP+LC-MS identified a total of 238 proteins that may interact with EGR3. Co-IP confirmed that PRMT1 was an interacting protein with EGR3. Furthermore, PRMT1 inhibitors could partially reduce PA-induced IL-6 and IL-1β secretion after EGR3 silencing in human podocytes (both P<0.05). Overexpression or silencing of EGR3 negatively regulated the expression of PRMT1 and p-STAT3.
CONCLUSIONS: EGR3 may reduce ORG podocyte inflammatory damage by inhibiting the PRMT1/p-STAT3 pathway.
目的: 肥胖会导致肥胖相关性肾病(obesity related glomerulopathy，ORG)，但其发病机制并不明确。本研究拟检测早期生长反应蛋白3(early growth response protein 3，EGR3)在ORG患者和高脂饮食诱导的肥胖小鼠肾皮质组织中的表达，并探讨EGR3抑制棕榈酸(palmitic acid，PA)诱导的人足细胞炎症损伤的分子机制。方法: 收集排除其他疾病导致的肾损害并经组织病理学证实的ORG患者(n=6)和高脂饮食诱导的肥胖小鼠的肾皮质组织(n=10)。使用150 μmol/L PA干预人和小鼠足细胞48 h；人足细胞中分别过表达或沉默EGR3。采用酶联免疫吸附试验(enzyme linked immunosorbent assay，ELISA)检测白细胞介素(interleukin，IL)-6和IL-1β的含量；real-time RT-PCR检测EGR3、足细胞分子标志NPHS1(nephrosis 1)、NPHS2(nephrosis 2)、足糖萼蛋白(podocalyxin，PODXL)、平足蛋白(podoplanin，PDPN)mRNA的表达；RNA-seq检测人足细胞过表达EGR3并150 μmol/L PA干预后与对照组的差异表达基因(differentially expressed genes，DEGs)；免疫共沉淀(co-immunoprecipitation，Co-IP)+液相色谱串联质谱(liquid chromatography tandem mass spectrometry，LC-MS)检测EGR3可能的相互作用蛋白质，并与RNA-seq的结果取交集；Co-IP验证EGR3与蛋白精氨酸甲基转移酶1(protein arginine methyltransferases 1，PRMT1)的相互作用；沉默EGR3和PRMT1抑制剂干预后检测PA诱导的足细胞培养液中IL-6和IL-1β的含量；蛋白质印迹法检测分别过表达或沉默EGR3后磷酸化信号转导及转录激活蛋白3(phosphorylated signal transducer and activator of transcription 3，p-STAT3)的蛋白质表达。结果: EGR3在ORG患者和高脂饮食诱导的肥胖小鼠肾皮质组织中的表达均显著上调(均P<0.01)，150 μmol/L PA干预人和小鼠足细胞48 h后显著上调2种细胞EGR3的表达(均P<0.05)。人足细胞过表达或沉默EGR3分别抑制或促进PA干预后细胞培养液中IL-6和IL-1β的分泌，并分别上调或下调NPHS1、PODXL、NPHS2及PDPN的表达(均P<0.05)。RNA-seq结果显示共有988个DEGs，Co-IP+LC-MS共发现238个可能与EGR3相互作用的蛋白质，且Co-IP证实PRMT1为EGR3的相互作用蛋白质。PRMT1抑制剂能部分减少人足细胞沉默EGR3后PA诱导的IL-6及IL-1β的分泌(均P<0.05)；此外，过表达或沉默EGR3负调控PRMT1及p-STAT3的表达。结论: EGR3可能通过抑制PRMT1/p-STAT3通路减轻ORG足细胞炎症损伤。.

暂无摘要。

UNASSIGNED: Most functional magnetic resonance research has primarily examined alterations in the affected kidney, often neglecting the contralateral kidney. Our study aims to investigate whether imaging parameters accurately depict changes in both the renal cortex and medulla in a unilateral ureteral obstruction rat model, thereby showcasing the utility of intravoxel incoherent motion (IVIM) in evaluating contralateral renal changes.
UNASSIGNED: Six rats underwent MR scans and were subsequently sacrificed for baseline histological examination. Following the induction of left ureteral obstruction, 48 rats were scanned, and the histopathological examinations were conducted on days 3, 7, 10, 14, 21, 28, 35, and 42. The apparent diffusion coefficient (ADC), pure molecular diffusion (D), pseudodiffusion (D*), and perfusion fraction (f) values were measured using IVIM.
UNASSIGNED: On the 10th day of obstruction, both cortical and medullary ADC values differed significantly between the UUO10 group and the sham group (p < 0.01). The cortical D values showed statistically significant differences between UUO3 group and sham group (p < 0.01) but not among UUO groups at other time point. Additionally, the cortical and medullary f values were statistically significant between the UUO21 group and the sham group (p < 0.01). Especially, the cortical f values exhibited significant differences between the UUO21 group and the UUO groups with shorter obstruction time (at time point of 3, 7, 10, 14 day) (p < 0.01).
UNASSIGNED: Significant hemodynamic alterations were observed in the contralateral kidney following renal obstruction. IVIM accurately captures changes in the unobstructed kidney. Particularly, the cortical f value exhibits the highest potential for assessing contralateral renal modifications.