scholarly journals G protein α12(Gα12) is a negative regulator of kidney injury molecule-1-mediated efferocytosis

2016 ◽  
Vol 310 (7) ◽  
pp. F607-F620 ◽  
Author(s):  
Ola Z. Ismail ◽  
Xizhong Zhang ◽  
Joseph V. Bonventre ◽  
Lakshman Gunaratnam
Keyword(s):  
Acute Kidney Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Dominant Negative ◽  
Negative Regulator ◽  
Apoptotic Cells ◽  
Α Subunit ◽  
Therapeutic Implications ◽  
Kidney Injury Molecule 1

Kidney injury molecule-1 (KIM-1) is a receptor for the “eat me” signal, phosphatidylserine, on apoptotic cells. The specific upregulation of KIM-1 by injured tubular epithelial cells (TECs) enables them to clear apoptotic cells (also known as efferocytosis), thereby protecting from acute kidney injury. Recently, we uncovered that KIM-1 binds directly to the α-subunit of heterotrimeric G12protein (Gα12) and inhibits its activation by reactive oxygen species during renal ischemia-reperfusion injury (Ismail OZ, Zhang X, Wei J, Haig A, Denker BM, Suri RS, Sener A, Gunaratnam L. Am J Pathol 185: 1207–1215, 2015). Here, we investigated the role that Gα12plays in KIM-1-mediated efferocytosis by TECs. We showed that KIM-1 remains bound to Gα12and suppresses its activity during phagocytosis. When we silenced Gα12expression using small interefering RNA, KIM-1-mediated engulfment of apoptotic cells was increased significantly; in contrast overexpression of constitutively active Gα12( QLGα12) resulted in inhibition of efferocytosis. Inhibition of RhoA, a key effector of Gα12, using a chemical inhibitor or expression of dominant-negative RhoA, had the same effect as inhibition of Gα12on efferocytosis. Consistent with this, silencing Gα12suppressed active RhoA in KIM-1-expressing cells. Finally, using primary TECs from Kim-1+/+and Kim-1−/−mice, we confirmed that engulfment of apoptotic cells requires KIM-1 expression and that silencing Gα12enhanced efferocytosis by primary TECs. Our data reveal a previously unknown role for Gα12in regulating efferocytosis and that renal TECs require KIM-1 to mediate this process. These results may have therapeutic implications given the known harmful role of Gα12in acute kidney injury.

scholarly journals Impact of cannabidiol treatment on regulatory T-17 cells and neutrophil polarization in acute kidney injury

2018 ◽  
Vol 315 (4) ◽  
pp. F1149-F1158 ◽  
Author(s):  
Babak Baban ◽  
Nasrul Hoda ◽  
Aneeq Malik ◽  
Hesam Khodadadi ◽  
Erika Simmerman ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Ischemia Reperfusion Injury ◽  
Tissue Injury ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
T Helper 17 ◽  
Th 17 ◽  
The Status ◽  
Proinflammatory Responses ◽  
Kidney Injury Molecule 1

Hallmark features of acute kidney injury (AKI) include mobilization of immune and inflammatory mechanisms culminating in tissue injury. Emerging information indicates heterogeneity of neutrophils with pro- and anti-inflammatory functions (N1 and N2, respectively). Also, regulatory T-17 (Treg17) cells curtail T helper 17 (Th-17)-mediated proinflammatory responses. However, the status of Treg17 cells and neutrophil phenotypes in AKI are not established. Furthermore, cannabidiol exerts immunoregulatory effects, but its impact on Treg17 cells and neutrophil subtypes is not established. Thus, we examined the status of Treg17 cells and neutrophil subtypes in AKI and determined whether cannabidiol favors regulatory neutrophils and T cells accompanied with renoprotection. Accordingly, mice were subjected to bilateral renal ischemia-reperfusion injury (IRI), without or with cannabidiol treatment; thereafter, kidneys were processed for flow cytometry analyses. Renal IRI increased N1 and Th-17 but reduced N2 and Treg17 cells accompanied with disruption of mitochondrial membrane potential (ψm) and increased apoptosis/necrosis and kidney injury molecule-1 (KIM-1) immunostaining compared with their sham controls. Importantly, cannabidiol treatment preserved ψm and reduced cell death and KIM-1 accompanied by restoration of N1 and N2 imbalance and preservation of Treg17 cells while decreasing Th-17 cells. The ability of cannabidiol to favor development of Treg17 cells was further established using functional mixed lymphocytic reaction. Subsequent studies showed higher renal blood flow and reduced serum creatinine in cannabidiol-treated IRI animals. Collectively, our novel observations establish that renal IRI causes neutrophil polarization in favor of N1 and also reduces Treg17 cells in favor of Th-17, effects that are reversed by cannabidiol treatment accompanied with significant renoprotection.

scholarly journals Reducing Inflammatory Cytokine Production from Renal Collecting Duct Cells by Inhibiting GATA2 Ameliorates Acute Kidney Injury

2017 ◽  
Vol 37 (22) ◽  
Author(s):  
Lei Yu ◽  
Takashi Moriguchi ◽  
Hiroshi Kaneko ◽  
Makiko Hayashi ◽  
Atsushi Hasegawa ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Inflammatory Cytokines ◽  
Inflammatory Cytokine ◽  
Cytokine Production ◽  
Ischemia Reperfusion Injury ◽  
Collecting Duct ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Cytokine Gene Expression ◽  
Renal Tubular Cell

ABSTRACT Acute kidney injury (AKI) is a leading cause of chronic kidney disease. Proximal tubules are considered to be the primary origin of pathogenic inflammatory cytokines in AKI. However, it remains unclear whether other cell types, including collecting duct (CD) cells, participate in inflammatory processes. The transcription factor GATA2 is specifically expressed in CD cells and maintains their cellular identity. To explore the pathophysiological function of GATA2 in AKI, we generated renal tubular cell-specific Gata2 deletion (G2CKO) mice and examined their susceptibility to ischemia reperfusion injury (IRI). Notably, G2CKO mice exhibited less severe kidney damage, with reduced granulomacrophagic infiltration upon IRI. Transcriptome analysis revealed that a series of inflammatory cytokine genes were downregulated in GATA2-deficient CD cells, suggesting that GATA2 induces inflammatory cytokine expression in diseased kidney CD cells. Through high-throughput chemical library screening, we identified a potent GATA inhibitor. The chemical reduces cytokine production in CD cells and protects the mouse kidney from IRI. These results revealed a novel pathological mechanism of renal IRI, namely, that CD cells produce inflammatory cytokines and promote IRI progression. In injured kidney CD cells, GATA2 exerts a proinflammatory function by upregulating inflammatory cytokine gene expression. GATA2 can therefore be considered a therapeutic target for AKI.

scholarly journals Urinary N-Acetyl-Beta-D-Glucosaminidase Activity in Rat Experimental Ischemic and Toxic Models of Acute Kidney Injury

2017 ◽  
Vol 74 (1) ◽  
pp. 105
Author(s):  
Razvan Andrei CODEA ◽  
Mircea MIRCEAN ◽  
Sidonia Alina BOGDAN ◽  
Andras Laszlo NAGY ◽  
Alexandra BIRIS ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Experimental Model ◽  
Wistar Rats ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Control Group ◽  
Tubular Injury ◽  
Group 2 ◽  
Group 1

The identification of a suitable prevention method which facilitates limiting the deleterious effects of acute kidney injuries is highly required. In order to identify a proper treatment for acute kidney injuries, a suitable experimental model that replicates the structural, metabolic and inflammatory lesions that occur in the natural acute injured kidney is highly necessary. Intense urinary NAG activity can be found in a variety of renal disease such as toxic nephropathies, ischemic renal injury following cardiac surgery or renal transplantation but also in glomerular disease especially in diabetic nephropathy. Rises in urinary NAG enzyme activity strongly suggests tubular cell damage and support NAG enzyme as a biomarker of renal tubular injury. The aim of this paper is to obtain a stable in vivo acute kidney injury experimental model, in Wistar, rats and to evaluate the urinary activity of N-acetyl-β-D-glucosaminidase (NAG) enzyme, blood levels of urea and creatinine and microstructural renal alterations induced by ischemia/reperfusion injury respectively gentamicin nephrotoxicity. For this purpose we have used a rat experimental model. Adult male Wistar rats weighing 250-300 g were randomly divided into 3 groups with 8 rats in each group. Group 1 served as a model for the renal ischemia/reperfusion injury experiment, group 2 served for toxic kidney injury experimental model and group 3 served as control group. All individuals in both groups 1 and 2 presented marked elevations in blood urea and creatinine at the moment of euthanasia (day 3 for group 1 and day 9 for group 2) compared to the control group where biochemical values remained within normal limits. Urine analysis of both group 1 and 2 showed marked urinary NAG index activity which suggests acute tubular injury, suggestion confirmed by histological evaluation of the renal parenchyma sampled from this subjects

scholarly journals P0511ENHANCER AND SUPER-ENHANCER DYNAMICS IN REPAIR AFTER ISCHEMIC ACUTE KIDNEY INJURY

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Julia Wilflingseder ◽  
Michaela Willi ◽  
Hye Kyung Lee ◽  
Hannes Olauson ◽  
Jakub Jankowsky ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Transcription Factors ◽  
Small Molecule ◽  
Ischemia Reperfusion Injury ◽  
Specific Binding ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Kidney Cortex ◽  
Super Enhancer

Abstract Background and Aims The endogenous repair process of the mammalian kidney allows rapid recovery after acute kidney injury (AKI) through robust proliferation of tubular epithelial cells. There is currently limited understanding of which transcriptional regulators activate these repair programs and how transcriptional dysregulation leads to maladaptive repair. Here we investigate the existence of enhancer dynamics in the regenerating mouse kidney. Method RNA-seq and ChIP-seq (H3K27ac, H3K4m3, BRD4, POL2 and selected transcription factors) were performed on samples from repairing kidney cortex 2 days after ischemia/reperfusion injury (IRI) to identify activated genes, transcription factors, enhancer and super-enhancers associated with kidney repair. Further we investigated the role of super-enhancer activation in kidney repair through pharmacological BET inhibition using the small molecule JQ1 in vitro and in acute kidney injury models in vivo. Results Response to kidney injury leads to genome-wide alteration in enhancer repertoire in-vivo. We identified 16,781 enhancer sites (H3K27ac and BRD4 positive, H3K4me3 negative binding) active in SHAM and IRI samples; 6,512 lost and 9,774 gained after IRI. The lost and gained enhancer sites can be annotated to 62% and 63% of down- and up-regulated transcripts at day 2 after kidney injury, respectively. Super-enhancer analysis revealed 164 lost and 216 gained super-enhancer sites at IRI day 2. 385 super-enhancers maintain activity before and after injury. ChIP-seq profiles of selected transcription factors based on motif analysis show specific binding at corresponding enhancer sites. We observed lost enhancer binding of HNF4A and GR mainly at kidney related enhancer elements. In contrast, STAT3 showed increased binding at injury induces enhancer elements. No dynamic was observed for STAT5. Both transcription factor groups show corresponding mRNA changes after injury. Pharmacological inhibition of enhancer and super-enhancer activity by BRD4 inhibition (JQ1: 50mg/kg/day) before IRI leads to suppression of 40% of injury-induced transcripts associated with cell cycle regulation and significantly increased mortality between days 2 and 3 after AKI. Conclusion This is the first demonstration of enhancer and super-enhancer function in the repairing kidney. In addition, our data call attention to potential caveats for use of small molecule inhibitors of BET proteins that are currently being tested in clinical trials in cancer patients who are at risk for AKI. Our analyses of enhancer dynamics after kidney injury in vivo have the potential to identify new targets for therapeutic intervention.

scholarly journals P0558DICLOFENAC ENHANCES RENAL INFLAMMATION IN EXPERIMENTAL SUBCLINICAL ACUTE KIDNEY INJURY (AKI)

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Johanna Störmer ◽  
Faikah Gueler ◽  
Song Rong ◽  
Mi-Sun Jang ◽  
Nelli Shushakova ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Oral Dose ◽  
Single Oral Dose ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Renal Perfusion ◽  
Tubular Atrophy ◽  
Renal Inflammation ◽  
Urine Production

Abstract Background and Aims Diclofenac is frequently used for pain control. In a previous study, we showed that already a single oral dose of diclofenac could reduce renal perfusion in healthy individuals. To investigate the influence of oral diclofenac administration on renal inflammation in the setting of pre-existing renal damage, we used a mouse model of subclinical acute kidney injury (AKI) induced by renal ischemia-reperfusion injury (IRI) followed by diclofenac administration. Method Male CD1 mice (7-8 weeks old) underwent unilateral renal pedicle clamping for 15min to induce subclinical AKI. After reperfusion mice received a single oral dose of 100 or 200mg/kg diclofenac via oral gavage. Vehicle treated mice with unilateral IRI served as control. At day 1, mice were placed into metabolic cages to collect urine. Histology was performed on day 1 and 14 for renal morphology. Inflammation and fibrosis were investigated by immunohistochemistry and qPCR. Results Diclofenac treated mice showed reduced urine production. Morphologically, signs of AKI were more pronounced in diclofenac treated kidneys which also showed more Cox-2 positive tubuli in the cortex. On mRNA expression level the pro-inflammatory markers IL-6 and CXCL2, the chemoattractant for neutrophils, were elevated in the diclofenac group. Early upregulation of the pro-fibrotic markers CTGF and PAI-1 was detected already on d1 after IRI in the diclofenac group and tubular atrophy was pronounced after two weeks. Conclusion Already, a single oral dose of diclofenac causes aggravation of renal inflammation and progressive renal fibrosis in the setting of pre-existing subclinical acute kidney injury.

scholarly journals A mouse model of Townes-Brocks syndrome expressing a truncated mutant Sall1 protein is protected from acute kidney injury

2015 ◽  
Vol 309 (10) ◽  
pp. F852-F863 ◽  
Author(s):  
Sara Hirsch ◽  
Tarek El-Achkar ◽  
Lynn Robbins ◽  
Jeannine Basta ◽  
Monique Heitmeier ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Mouse Model ◽  
Congenital Anomalies ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Acute Injury ◽  
Null Alleles ◽  
Heme Oxygenase 1 ◽  
Adult Kidney

It has been postulated that developmental pathways are reutilized during repair and regeneration after injury, but functional analysis of many genes required for kidney formation has not been performed in the adult organ. Mutations in SALL1 cause Townes-Brocks syndrome (TBS) and nonsyndromic congenital anomalies of the kidney and urinary tract, both of which lead to childhood kidney failure. Sall1 is a transcriptional regulator that is expressed in renal progenitor cells and developing nephrons in the embryo. However, its role in the adult kidney has not been investigated. Using a mouse model of TBS ( Sall1 TBS), we investigated the role of Sall1 in response to acute kidney injury. Our studies revealed that Sall1 is expressed in terminally differentiated renal epithelia, including the S3 segment of the proximal tubule, in the mature kidney. Sall1 TBS mice exhibited significant protection from ischemia-reperfusion injury and aristolochic acid-induced nephrotoxicity. This protection from acute injury is seen despite the presence of slowly progressive chronic kidney disease in Sall1 TBS mice. Mice containing null alleles of Sall1 are not protected from acute kidney injury, indicating that expression of a truncated mutant protein from the Sall1 TBS allele, while causative of congenital anomalies, protects the adult kidney from injury. Our studies further revealed that basal levels of the preconditioning factor heme oxygenase-1 are elevated in Sall1 TBS kidneys, suggesting a mechanism for the relative resistance to injury in this model. Together, these studies establish a functional role for Sall1 in the response of the adult kidney to acute injury.

scholarly journals Cell Death Patterns Due to Warm Ischemia or Reperfusion in Renal Tubular Epithelial Cells Originating from Human, Mouse, or the Native Hibernator Hamster

Biology ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 48 ◽  
Author(s):  
Theodoros Eleftheriadis ◽  
Georgios Pissas ◽  
Georgia Antoniadi ◽  
Vassilios Liakopoulos ◽  
Ioannis Stefanidis
Keyword(s):  
Lipid Peroxidation ◽  
Acute Kidney Injury ◽  
Cell Death ◽  
Epithelial Cells ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Human Cells ◽  
Tubular Epithelial Cells

Ischemia–reperfusion injury contributes to the pathogenesis of many diseases, with acute kidney injury included. Hibernating mammals survive prolonged bouts of deep torpor with a dramatic drop in blood pressure, heart, and breathing rates, interspersed with short periods of arousal and, consequently, ischemia–reperfusion injury. Clarifying the differences under warm anoxia or reoxygenation between human cells and cells from a native hibernator may reveal interventions for rendering human cells resistant to ischemia–reperfusion injury. Human and hamster renal proximal tubular epithelial cells (RPTECs) were cultured under warm anoxia or reoxygenation. Mouse RPTECs were used as a phylogenetic control for hamster cells. Cell death was assessed by both cell imaging and lactate dehydrogenase (LDH) release assay, apoptosis by cleaved caspase-3, autophagy by microtubule-associated protein 1-light chain 3 B II (LC3B-II) to LC3B-I ratio, necroptosis by phosphorylated mixed-lineage kinase domain-like pseudokinase, reactive oxygen species (ROS) fluorometrically, and lipid peroxidation, the end-point of ferroptosis, by malondialdehyde. Human cells died after short periods of warm anoxia or reoxygenation, whereas hamster cells were extremely resistant. In human cells, apoptosis contributed to cell death under both anoxia and reoxygenation. Although under reoxygenation, ROS increased in both human and hamster RPTECs, lipid peroxidation-induced cell death was detected only in human cells. Autophagy was observed only in human cells under both conditions. Necroptosis was not detected in any of the evaluated cells. Clarifying the ways that are responsible for hamster RPTECs escaping from apoptosis and lipid peroxidation-induced cell death may reveal interventions for preventing ischemia–reperfusion-induced acute kidney injury in humans.

scholarly journals Endothelial STAT3 Modulates Protective Mechanisms in a Mouse Ischemia-Reperfusion Model of Acute Kidney Injury

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Shataakshi Dube ◽  
Tejasvi Matam ◽  
Jessica Yen ◽  
Henry E. Mang ◽  
Pierre C. Dagher ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Ischemia Reperfusion Injury ◽  
Leukocyte Adhesion ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Organ Injury ◽  
Mrna Levels ◽  
Kidney Dysfunction ◽  
Stat3 Signaling ◽  
Proximal Tubular

STAT3 is a transcriptional regulator that plays an important role in coordinating inflammation and immunity. In addition, there is a growing appreciation of the role STAT3 signaling plays in response to organ injury following diverse insults. Acute kidney injury (AKI) from ischemia-reperfusion injury is a common clinical entity with devastating consequences, and the recognition that endothelial alterations contribute to kidney dysfunction in this setting is of growing interest. Consequently, we used a mouse with a genetic deletion of Stat3 restricted to the endothelium to examine the role of STAT3 signaling in the pathophysiology of ischemic AKI. In a mouse model of ischemic AKI, the loss of endothelial STAT3 signaling significantly exacerbated kidney dysfunction, morphologic injury, and proximal tubular oxidative stress. The increased severity of ischemic AKI was associated with more robust endothelial-leukocyte adhesion and increased tissue accumulation of F4/80+ macrophages. Moreover, important proximal tubular adaptive mechanisms to injury were diminished in association with decreased tissue mRNA levels of the epithelial cell survival cytokine IL-22. In aggregate, these findings suggest that the endothelial STAT3 signaling plays an important role in limiting kidney dysfunction in ischemic AKI and that selective pharmacologic activation of endothelial STAT3 signaling could serve as a potential therapeutic target.

scholarly journals Deletion of the Gamma Subunit of ENaC in Endothelial Cells Does Not Protect against Renal Ischemia Reperfusion Injury

2021 ◽  
Vol 22 (20) ◽  
pp. 10914
Author(s):  
Stephanie M. Mutchler ◽  
Mahpara Hasan ◽  
Donald E. Kohan ◽  
Thomas R. Kleyman ◽  
Roderick J. Tan
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Renal Ischemia ◽  
Α Subunit ◽  
Γ Subunit ◽  
Renal Ischemia Reperfusion Injury

Acute kidney injury due to renal ischemia-reperfusion injury (IRI) may lead to chronic or end stage kidney disease. A greater understanding of the cellular mechanisms underlying IRI are required to develop therapeutic options aimed at limiting or reversing damage from IRI. Prior work has shown that deletion of the α subunit of the epithelial Na+ channel (ENaC) in endothelial cells protects from IRI by increasing the availability of nitric oxide. While canonical ENaCs consist of an α, β, and γ subunit, there is evidence of non-canonical ENaC expression in endothelial cells involving the α subunit. We therefore tested whether the deletion of the γ subunit of ENaC also protects mice from IRI to differentiate between these channel configurations. Mice with endothelial-specific deletion of the γ subunit and control littermates were subjected to unilateral renal artery occlusion followed by 48 h of reperfusion. No significant difference was noted in injury between the two groups as assessed by serum creatinine and blood urea nitrogen, levels of specific kidney injury markers, and histological examination. While deletion of the γ subunit did not alter infiltration of immune cells or cytokine message, it was associated with an increase in levels of total and phosphorylated endothelial nitric oxide synthase (eNOS) in the injured kidneys. Our studies demonstrate that even though deletion of the γ subunit of ENaC may allow for greater activation of eNOS, this is not sufficient to prevent IRI, suggesting the protective effects of α subunit deletion may be due, in part, to other mechanisms.

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