American Journal of Physiology-renal Physiology最新文献

Acute kidney injury (AKI) is common in surgical and critically ill patients. This study examined whether pretreatment with a novel Toll-like receptor 4 agonist attenuated ischemia-reperfusion injury (IRI)-induced AKI (IRI-AKI). We performed a blinded, randomized-controlled study in mice pretreated with 3-deacyl 6-acyl phosphorylated hexaacyl disaccharide (PHAD), a synthetic Toll-like receptor 4 agonist. Two cohorts of male BALB/c mice received intravenous vehicle or PHAD (2, 20, or 200 µg) at 48 and 24 h before unilateral renal pedicle clamping and simultaneous contralateral nephrectomy. A separate cohort of mice received intravenous vehicle or 200 µg PHAD followed by bilateral IRI-AKI. Mice were monitored for evidence of kidney injury for 3 days postreperfusion. Kidney function was assessed by serum blood urea nitrogen and creatinine measurements. Kidney tubular injury was assessed by semiquantitative analysis of tubular morphology on periodic acid-Schiff (PAS)-stained kidney sections and by kidney mRNA quantification of injury [neutrophil gelatinase-associated lipocalin (Ngal), kidney injury molecule-1 (Kim-1), and heme oxygenase-1 (Ho-1)] and inflammation [interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (Tnf-α)] using quantitative RT-PCR. Immunohistochemistry was used to quantify proximal tubular cell injury and renal macrophages by quantifying the areas stained with Kim-1 and F4/80 antibodies, respectively, and TUNEL staining to detect the apoptotic nuclei. PHAD pretreatment yielded dose-dependent kidney function preservation after unilateral IRI-AKI. Histological injury, apoptosis, Kim-1 staining, and Ngal mRNA were lower in PHAD-treated mice and IL-1β mRNA was higher in PHAD-treated mice. Similar pretreatment protection was noted with 200 mg PHAD after bilateral IRI-AKI, with significantly reduced Kim-1 immunostaining in the outer medulla of mice treated with PHAD after bilateral IRI-AKI. In conclusion, PHAD pretreatment leads to dose-dependent protection from renal injury after unilateral and bilateral IRI-AKI in mice.NEW & NOTEWORTHY Pretreatment with 3-deacyl 6-acyl phosphorylated hexaacyl disaccharide; a novel synthetic Toll-like receptor 4 agonist, preserves kidney function during ischemia-reperfusion injury-induced acute kidney injury.

Polycystic kidney disease is a disorder of renal epithelial growth and differentiation. Transcription factor EB (TFEB), a master regulator of lysosome biogenesis and function, was studied for a potential role in this disorder. Nuclear translocation and functional responses to TFEB activation were studied in three murine models of renal cystic disease, including knockouts of folliculin, folliculin interacting proteins 1 and 2, and polycystin-1 (Pkd1) as well as in mouse embryonic fibroblasts lacking Pkd1 and three-dimensional cultures of Madin-Darby canine kidney cells. Nuclear translocation of Tfeb characterized cystic but not noncystic renal tubular epithelia in all three murine models as both an early and sustained response to cyst formation. Epithelia expressed elevated levels of Tfeb-dependent gene products, including cathepsin B and glycoprotein nonmetastatic melanoma protein B. Nuclear Tfeb translocation was observed in mouse embryonic fibroblasts lacking Pkd1 but not wild-type fibroblasts. Pkd1 knockout fibroblasts were characterized by increased Tfeb-dependent transcripts, lysosomal biogenesis and repositioning, and increased autophagy. The growth of Madin-Darby canine kidney cell cysts was markedly increased following exposure to the TFEB agonist compound C1, and nuclear Tfeb translocation was observed in response to both forskolin and compound C1 treatment. Nuclear TFEB also characterized cystic epithelia but not noncystic tubular epithelia in human patients with autosomal dominant polycystic kidney disease. Noncanonical activation of TFEB is characteristic of cystic epithelia in multiple models of renal cystic disease including those associated with loss of Pkd1. Nuclear TFEB translocation is functionally active in these models and may be a component of a general pathway contributing to cystogenesis and growth.NEW & NOTEWORTHY Changes in epithelial cell metabolism are important in renal cyst development. The role of TFEB, a transcriptional regulator of lysosomal function, was explored in several models of renal cystic disease and human ADPKD tissue sections. Nuclear TFEB translocation was uniformly observed in cystic epithelia in each model of renal cystic disease examined. TFEB translocation was functionally active and associated with lysosomal biogenesis and perinuclear repositioning, increased TFEB-associated protein expression, and activation of autophagic flux. Compound C1, a TFEB agonist, promoted cyst growth in 3-D cultures of MDCK cells. Nuclear TFEB translocation is an underappreciated signaling pathway for cystogenesis that may represent a new paradigm for cystic kidney disease.

Measurement of total kidney volume (TKV) using magnetic resonance imaging (MRI) is a valuable approach for monitoring disease progression in autosomal dominant polycystic kidney disease (PKD) and is becoming more common in preclinical studies using animal models. Manual contouring of kidney MRI areas [i.e., manual method (MM)] is a conventional, but time-consuming, way to determine TKV. We developed a template-based semiautomatic image segmentation method (SAM) and validated it in three commonly used PKD models: Cys1^cpk/cpk mice, Pkd1^RC/RC mice, and Pkhd1^pck/pck rats (n = 10 per model). We compared SAM-based TKV with that obtained by clinical alternatives including the ellipsoid formula-based method (EM) using three kidney dimensions, the longest kidney length method (LM), and MM, which is considered the gold standard. Both SAM and EM presented high accuracy in TKV assessment in Cys1^cpk/cpk mice [interclass correlation coefficient (ICC) ≥ 0.94]. SAM was superior to EM and LM in Pkd1^RC/RC mice (ICC = 0.87, 0.74, and <0.10 for SAM, EM, and LM, respectively) and Pkhd1^pck/pck rats (ICC = 0.59, <0.10, and <0.10, respectively). Also, SAM outperformed EM in processing time in Cys1^cpk/cpk mice (3.6 ± 0.6 vs. 4.4 ± 0.7 min/kidney) and Pkd1^RC/RC mice (3.1 ± 0.4 vs. 7.1 ± 2.6 min/kidney, both P < 0.001) but not in Pkhd1^PCK/PCK rats (3.7 ± 0.8 vs. 3.2 ± 0.5 min/kidney). LM was the fastest (∼1 min) but correlated most poorly with MM-based TKV in all studied models. Processing times by MM were longer for Cys1^cpk/cpk mice, Pkd1^RC/RC mice, and Pkhd1^pck.pck rats (66.1 ± 7.3, 38.3 ± 7.5, and 29.2 ± 3.5 min). In summary, SAM is a fast and accurate method to determine TKV in mouse and rat PKD models.NEW & NOTEWORTHY Total kidney volume (TKV) is a valuable readout in preclinical studies for autosomal dominant and autosomal recessive polycystic kidney diseases (ADPKD and ARPKD). Since conventional TKV assessment by manual contouring of kidney areas in all images is time-consuming, we developed a template-based semiautomatic image segmentation method (SAM) and validated it in three commonly used ADPKD and ARPKD models. SAM-based TKV measurements were fast, highly reproducible, and accurate across mouse and rat ARPKD and ADPKD models.

Chronic kidney disease (CKD) of uncertain etiology (CKDu) is a global health concern affecting tropical farming communities. CKDu is not associated with typical risk factors (e.g., diabetes) and strongly correlates with environmental drivers. To gain potential insights into disease etiology and diagnosis, here we report the first urinary proteome comparing patients with CKDu and non-CKDu controls from Sri Lanka. We found 944 differentially abundant proteins. In silico analyses identified 636 proteins of likely kidney and urogenital origin. As expected, renal tubular injury in patients with CKDu was evinced by increases in albumin, cystatin C, and β₂-microglobulin. However, several proteins typically elevated under CKD, including osteopontin and α-N-acetylglucosaminidase, were decreased in patients with CKDu. Furthermore, urinary excretion of aquaporins found higher in CKD was lower in CKDu. Comparisons with previous CKD urinary proteome datasets revealed a unique proteome for CKDu. Notably, the CKDu urinary proteome was relatively similar to that of patients with mitochondrial diseases. Furthermore, we report a decrease in endocytic receptor proteins responsible for protein reabsorption (megalin and cubilin) that correlated with an increase in abundance of 15 of their cognate ligands. Functional pathway analyses identified kidney-specific differentially abundant proteins in patients with CKDu denoted significant changes in the complement cascade and coagulation systems, cell death, lysosomal function, and metabolic pathways. Overall, our findings provide potential early detection markers to diagnose and distinguish CKDu and warrant further analyses on the role of lysosomal, mitochondrial, and protein reabsorption processes and their link to the complement system and lipid metabolism in CKDu onset and progression.NEW & NOTEWORTHY CKDu is a global health concern debilitating a number of tropical rural farming communities. In the absence of typical risk factors like diabetes and hypertension and the lack of molecular markers, it is crucial to identify potential early disease markers. Here, we detail the first urinary proteome profile to distinguish CKDu from CKD. Our data and in silico pathway analyses infer the roles of mitochondrial, lysosomal, and protein reabsorption processes in disease onset and progression.

Postoperative acute kidney injury (AKI) is a common complication after surgery. The pathophysiology of postoperative AKI is complex. One potentially important factor is anesthetic modality. We, therefore, conducted a meta-analysis of the available literature regarding anesthetic modality and incidence of postoperative AKI. Records were retrieved until January 17, 2023, with the search terms ("propofol" OR "intravenous") AND ("sevoflurane" OR "desflurane" OR "isoflurane" OR "volatile" OR "inhalational") AND ("acute kidney injury" OR "AKI"). A meta-analysis for common effects and random effects was performed after exclusion assessment. Eight records were included in the meta-analysis with a total of 15,140 patients (n = 7,542 propofol and n = 7,598 volatile). The common and random effects model revealed that propofol was associated with a lower incidence of postoperative AKI compared with volatile anesthesia [odds ratio: 0.63 (95% confidence interval: 0.56-0.72) and 0.49 (95% confidence interval: 0.33-0.73), respectively]. In conclusion, the meta-analysis revealed that propofol anesthesia is associated with a lower incidence of postoperative AKI compared with volatile anesthesia. This may motivate choosing propofol-based anesthesia in patients with increased risk of postoperative AKI due to preexisting renal impairment or surgery with a high risk of renal ischemia.NEW & NOTEWORTHY This study analyzed the available literature on anesthetic modality and incidence of postoperative AKI. The meta-analysis revealed that propofol is associated with lower incidence of AKI compared with volatile anesthesia. It might therefore be considerable to use propofol anesthesia in surgeries with increased susceptibility for developing renal injuries such as cardiopulmonary bypass and major abdominal surgery.

Activation of NADPH oxidase (NOX) enzymes and the generation of reactive oxygen species and oxidative stress regulate vascular and renal function and contribute to the pathogenesis of hypertension. The present study examined the role of NOXA1/NOX1 function in vascular reactivity of renal and mesenteric resistance arteries/arterioles of wild-type and Noxa1^-/- mice. A major finding was that renal blood flow is less sensitive to acute stimulation by angiotensin II (ANG II) in Noxa1^-/- mice compared with wild-type mice, with a direct action on resistance arterioles independent of nitric oxide (NO) bioavailability. These functional results were reinforced by immunofluorescence evidence of NOXA1/NOX1 protein presence in renal arteries, afferent arterioles, and glomeruli as well as their upregulation by ANG II. In contrast, the renal vascular response to the thromboxane mimetic U46619 was effectively blunted by NO and was similar in both mouse genotypes and thus independent of NOXA1/NOX1 signaling. However, phenylephrine- and ANG II-induced contraction of isolated mesenteric arteries was less pronounced and buffering of vasoconstriction after acetylcholine and nitroprusside stimulation was reduced in Noxa1^-/- mice, suggesting endothelial NO-dependent mechanisms. An involvement of NOXA1/NOX1/O₂^•- signaling in response to ANG II was demonstrated with the specific NOXA1/NOX1 assembly inhibitor C25 and the nonspecific NOX inhibitor diphenyleneiodonium chloride in cultured vascular smooth muscle cells and isolated mesenteric resistance arteries. Collectively, our data indicate that the NOX1/NOXA1/O₂^•- pathway contributes to acute vasoconstriction induced by ANG II in renal and mesenteric vascular beds and may contribute to ANG II-induced hypertension.NEW & NOTEWORTHY Renal reactivity to angiotensin II (ANG II) is mediated by superoxide signaling produced by NADPH oxidase (NOX)A1/NOX1. Acute vasoconstriction of renal arteries by ANG was blunted in Noxa1^-/- compared with wild-type mice. NOXA1/NOX1/O₂^•- signaling was also observed in ANG II stimulation of vascular smooth muscle cells and isolated mesenteric resistance arteries, indicating that it contributes to ANG II-induced hypertension. A NOXA1/NOX1 assembly inhibitor (C25) has been characterized that inhibits superoxide production and ameliorates the effects of ANG II.

This study aimed to clarify whether downregulation of K⁺-Cl^- cotransporter 2 (KCC2) in the sacral parasympathetic nucleus (SPN) of the lumbosacral spinal cord, from which the efferent pathway innervating the bladder originates, causes cellular hyperexcitability and triggers detrusor overactivity (DO) in spinal cord injury (SCI). SCI was produced by Th8-9 spinal cord transection in female C57BL/6 mice. At 4 wk after SCI, CLP290, a KCC2 activator, was administered, and cystometry was performed. Thereafter, neuronal activity with c-fos staining and KCC2 expression in cholinergic preganglionic parasympathetic neurons in the SPN was examined using immunohistochemistry. Firing properties of neurons in the SPN region were evaluated by extracellular recordings in the spinal cord slice preparations. DO evident as nonvoiding contractions was significantly reduced by CLP290 treatment in SCI mice. The number of c-fos-positive cells and coexpression of c-fos in choline acetyltransferase-positive cells were decreased in the SPN region of the SCI CLP290-treated group versus the SCI vehicle-treated group. KCC2 immunoreactivity was present on the cell membrane of SPN neurons and normalized fluorescence intensity of KCC2 in choline acetyltransferase-positive SPN neurons was decreased in the SCI vehicle-treated group versus the spinal intact vehicle-treated group but recovered in the SCI CLP290-treated group. Extracellular recordings showed that CLP290 suppressed the high-frequency firing activity of SPN neurons in SCI mice. These results indicated that SCI-induced DO is associated with downregulation of KCC2 in preganglionic parasympathetic neurons and that activation of KCC2 transporters can reduce DO, increase KCC2 expression in preganglionic parasympathetic neurons, and decrease neuronal firing of SPN neurons in SCI mice.NEW & NOTEWORTHY This study is the first report to suggest that activation of the Cl^- transporter K⁺-Cl^- cotransporter 2 may be a therapeutic modality for the treatment of spinal cord injury-induced detrusor overactivity by targeting bladder efferent pathways.

Inflammation that develops with the release of chemokines and cytokines during acute kidney injury (AKI) has been shown to participate in functional renal recovery. Although a major research focus has been on the role of macrophages, the family of C-X-C motif chemokines that promote neutrophil adherence and activation also increases with kidney ischemia-reperfusion (I/R) injury. This study tested the hypothesis that intravenous delivery of endothelial cells (ECs) that overexpress (C-X-C motif) chemokine receptors 1 and 2 (CXCR1 and CXCR2, respectively) improves outcomes in kidney I/R injury. Overexpression of CXCR1/2 enhanced homing of endothelial cells to I/R-injured kidneys and limited interstitial fibrosis, capillary rarefaction, and tissue injury biomarkers (serum creatinine concentration and urinary kidney injury molecule-1) following AKI and also reduced expression of P-selectin and the rodent (C-X-C motif) chemokine cytokine-induced neutrophil chemoattractant (CINC)-2β as well as the number of myeloperoxidase-positive cells in the postischemic kidney. The serum chemokine/cytokine profile, including CINC-1, showed similar reductions. These findings were not observed in rats given endothelial cells transduced with an empty adenoviral vector (null-ECs) or a vehicle alone. These data indicate that extrarenal endothelial cells that overexpress CXCR1 and CXCR2, but not null-ECs or vehicle alone, reduce I/R kidney injury and preserve kidney function in a rat model of AKI.NEW & NOTEWORTHY Inflammation facilitates kidney ischemia-reperfusion (I/R) injury. Endothelial cells (ECs) that were modified to overexpress (C-X-C motif) chemokine receptor (CXCR)1/2 (CXCR1/2-ECs) were injected immediately following kidney I/R injury. The interaction of CXCR1/2-ECs, but not ECs transduced with an empty adenoviral vector, with injured kidney tissue preserved kidney function and reduced production of inflammatory markers, capillary rarefaction, and interstitial fibrosis. The study highlights a functional role for the C-X-C chemokine pathway in kidney damage following I/R injury.