Biomedical subjects

Joseph V Bonventre

Publications and source records attributed to Joseph V Bonventre.

At least 19 recordsLinked to original sources

PubMed2025

A hypoxia-responsive tRNA-derived small RNA confers renal protection through RNA autophagy.

Transfer RNA-derived small RNAs (tsRNAs or tDRs) perform a range of cellular functions. Here, we showed that tRNA-Asp-GTC-3'tDR, a hypoxia-induced tDR derived from the 3' end of tRNA-Asp-GTC, activated autophagic flux in kidney cells and its silencing blocked autophagic flux. Functional gain-/loss-of-function studies in murine kidney disease models demonstrated a substantial renoprotective function of tRNA-Asp-GTC-3'tDR. Mechanistically, tRNA-Asp-GTC-3'tDR assembled stable G-quadruplex structures and sequestered pseudouridine synthase 7 (PUS7), preventing catalytic pseudouridylation of histone mRNAs. The resulting pseudouridylation deficiency directed histone mRNAs to the autophagosome-lysosome pathway, triggering RNA autophagy. This tDR-induced RNA autophagy pathway was activated during murine and human kidney diseases, suggesting clinical relevance. Thus, tRNA-Asp-GTC-3'tDR plays a role in regulating RNA autophagy, which helps to maintain homeostasis in kidney cells and protects against kidney injury.

Animals↗

PubMed2006

NADPH oxidase p22phox and catalase gene variants are associated with biomarkers of oxidative stress and adverse outcomes in acute renal failure.

Reactive oxygen species are important mediators of injury in acute renal failure (ARF). Although polymorphisms that affect key pro- and antioxidant enzymes might alter the susceptibility to oxidative stress-mediated injury, the use of genetic epidemiology for the study of oxidative stress-related genes has received little attention in ARF. The relationship of single-nucleotide polymorphisms in the coding region (C to T substitution at position +242) of the pro-oxidant enzyme NADPH oxidase p22phox subunit gene and in the promoter region (C to T substitution at position -262) of the antioxidant enzyme catalase gene to adverse clinical outcomes was evaluated prospectively in a cohort of 200 hospitalized patients with established ARF of mixed cause and severity. Genomic DNA was extracted from peripheral blood leukocytes and analyzed with a restriction fragment length polymorphism PCR method. Genotype-phenotype associations were characterized by measuring circulating nitrotyrosine and catalase activity. Observed and expected genotype frequencies were not significantly different, and overall baseline characteristics were not significantly different according to the various genotype groups. A genotype-phenotype association was demonstrable between the NADPH oxidase p22phox genotypes and plasma nitrotyrosine level (P = 0.06), as well as between the catalase genotypes and whole-blood catalase activity (P < 0.001). Compared with the NADPH oxidase p22phox CC genotype group, the T-allele group had a higher cumulative probability of remaining hospitalized (P = 0.03). Compared with the NADPH oxidase p22phox CC genotype, the T-allele carrier state was associated with 2.1-fold higher odds for dialysis requirement or hospital death (P = 0.01). This association persisted with 2.0- to 2.2-fold higher odds for this composite outcome after adjustment for race; gender; age; and the Acute Physiology and Chronic Health Evaluation II score (P = 0.03), the Multiple Organ Failure score (P = 0.01), or presence of sepsis (P = 0.02). The polymorphism in the gene that encodes the NADPH oxidase p22phox subunit at position +242 is associated with dialysis requirement or hospital death among patients with ARF. Larger studies are needed to confirm these relationships.

Acute Kidney Injury↗

PubMed2006

M1 muscarinic receptors inhibit L-type Ca2+ current and M-current by divergent signal transduction cascades.

Ion channels reside in a sea of phospholipids. During normal fluctuations in membrane potential and periods of modulation, lipids that directly associate with channel proteins influence gating by incompletely understood mechanisms. In one model, M(1)-muscarinic receptors (M(1)Rs) may inhibit both Ca(2+) (L- and N-) and K(+) (M-) currents by losing a putative interaction between channels and phosphatidylinositol-4,5-bisphosphate (PIP(2)). However, we found previously that M(1)R inhibition of N-current in superior cervical ganglion (SCG) neurons requires loss of PIP(2) and generation of a free fatty acid, probably arachidonic acid (AA) by phospholipase A(2) (PLA(2)). It is not known whether PLA(2) activity and AA also participate in L- and M-current modulation in SCG neurons. To test whether PLA(2) plays a similar role in M(1)R inhibition of L- and M-currents, we used several experimental approaches and found unanticipated divergent signaling. First, blocking resynthesis of PIP(2) minimized M-current recovery from inhibition, whereas L-current recovered normally. Second, L-current inhibition required group IVa PLA(2) [cytoplasmic PLA(2) (cPLA(2))], whereas M-current did not. Western blot and imaging studies confirmed acute activation of cPLA(2) by muscarinic stimulation. Third, in type IIa PLA(2) [secreted (sPLA(2))](-/-)/cPLA(2)(-/-) double-knock-out SCG neurons, muscarinic inhibition of L-current decreased. In contrast, M-current inhibition remained unaffected but recovery was impaired. Our results indicate that L-current is inhibited by a pathway previously shown to control M-current over-recovery after washout of muscarinic agonist. Our findings support a model of M(1)R-meditated channel modulation that broadens rather than restricts the roles of phospholipids and fatty acids in regulating ion channel activity.

Animals↗

PubMed2006

Resolvin D series and protectin D1 mitigate acute kidney injury.

Omega-3 fatty acid docosahexaenoic acid is converted to potent resolvins (Rv) and protectin D1 (PD1), two newly identified families of natural mediators of resolution of inflammation. We report that, in response to bilateral ischemia/reperfusion injury, mouse kidneys produce D series resolvins (RvDs) and PD1. Administration of RvDs or PD1 to mice before the ischemia resulted in a reduction in functional and morphological kidney injury. Initiation of RvDs and RvD1 administration 10 min after reperfusion also resulted in protection of the kidney as measured by serum creatinine 24 and 48 h later. Interstitial fibrosis after ischemia/reperfusion was reduced in mice treated with RvDs. Both RvDs and PD1 reduced the number of infiltrating leukocytes and blocked TLR-mediated activation of macrophages. Thus, the renal production of Rv and protectins, a previously unrecognized endogenous anti-inflammatory response, may play an important role in protection against and resolution of acute kidney injury. These data may also have therapeutic implications for potentiation of recovery from acute kidney injury.

Acute Disease↗

PubMed2006

A highly conserved tyrosine of Tim-3 is phosphorylated upon stimulation by its ligand galectin-9.

Tim-3 is a member of the TIM family of proteins (T-cell immunoglobulin mucin) involved in the regulation of CD4+ T-cells. Tim-3 is a T(H)1-specific type 1 membrane protein and regulates T(H)1 proliferation and the development of tolerance. Binding of galectin-9 to the extracellular domain of Tim-3 results in apoptosis of T(H)1 cells, but the intracellular pathways involved in the regulatory function of Tim-3 are unknown. Unlike Tim-1, which is expressed in renal epithelia and cancer, Tim-3 has not been described in cells other than neuronal or T-cells. Using RT-PCR we demonstrate that Tim-3 is expressed in malignant and non-malignant epithelial tissues. We have cloned Tim-3 from an immortalized liver cell carcinoma line and identified a highly conserved tyrosine in the intracellular tail of Tim-3 (Y265). We demonstrate that Y265 is specifically phosphorylated in vivo by the interleukin inducible T cell kinase (ITK), a kinase which is located in close proximity of the TIM genes on the allergy susceptibility locus 5q33.3. Stimulation of Tim-3 by its ligand galectin-9 results in increased phosphorylation of Y265, suggesting that this tyrosine residue plays an important role in downstream signalling events regulating T-cell fate. Given the role of TIM proteins in autoimmunity and cancer, the conserved SH2 binding domain surrounding Y265 could represent a possible target site for pharmacological intervention.

Amino Acid Sequence↗

PubMed2006

T cell, Ig domain, mucin domain-2 gene-deficient mice reveal a novel mechanism for the regulation of Th2 immune responses and airway inflammation.

The development of asthma and other atopic diseases is influenced by cytokines produced by Th2 effector T cells. How effector T cell responses are regulated once these cell populations are established remains unclear. The recently described T cell and airway phenotype regulator locus, containing the T cell, Ig domain, mucin domain (TIM) genes, is genetically associated with Th2 cytokine production and Th2-dependent immune responses. In this study, we report the phenotype of the TIM-2 gene-deficient mouse, and demonstrate exacerbated lung inflammation in an airway atopic response model. Immune responses in the TIM-2-deficient mouse reveal disregulated expression of Th2 cytokines, and adoptive transfer experiments show that the T cell compartment is responsible for the heightened inflammatory phenotype. These studies show that TIM-2 is a novel and critical regulator of effector T cell activity.

Animals↗

PubMed2006

Induction of kidney injury molecule-1 in homozygous Ren2 rats is attenuated by blockade of the renin-angiotensin system or p38 MAP kinase.

Kidney injury molecule-1 (Kim-1) is associated with ischemic and proteinuric tubular injury; however, whether dysregulation of the renin-angiotensin system (RAS) can also induce Kim-1 is unknown. We studied Kim-1 expression in homozygous Ren2 rats, characterized by renal damage through excessive RAS activation. We also investigated whether antifibrotic treatment (RAS blockade or p38 MAP kinase inhibition) would affect Kim-1 expression. At 7 wk of age, homozygous Ren2 rats received a nonhypotensive dose of candesartan (0.05 mg x kg(-1) x day(-1) sc) or the p38 inhibitor SB-239063 (15 mg x kg(-1) x day(-1) sc) for 4 wk; untreated Ren2 and Sprague-Dawley (SD) rats served as controls. Kim-1 mRNA and protein expression were determined by quantitative PCR and immunohistochemistry, respectively, and related to markers of prefibrotic renal damage. Urinary Kim-1 was measured in 8-wk-old Ren2 and SD rats with and without angiotensin-converting enzyme inhibition (ramipril, 1 mg x kg(-1) x day(-1) in drinking water for 4 wk). Untreated Ren2 rats showed a >20-fold increase in renal Kim-1 mRNA (expressed as Kim-1-to-GAPDH ratio): 75.5 +/- 43.6 vs. 3.1 +/- 1.0 in SD rats (P < 0.01). Candesartan and SB-239063 strongly reduced Kim-1 mRNA: 3.1 +/- 1.5 (P < 0.01) and 9.8 +/- 4.2 (P < 0.05), respectively. Kim-1 protein expression in damaged tubules paralleled mRNA expression. Kim-1 expression correlated with renal osteopontin, alpha-smooth muscle actin, and collagen III expression and with tubulointerstitial fibrosis. Damaged tubular segments expressing activated p38 also expressed Kim-1. Urinary Kim-1 was increased in Ren2 vs. SD (458 +/- 70 vs. 27 +/- 2 pg/ml, P < 0.01) rats and abolished in Ren2 rats treated with ramipril (33 +/- 5 pg/ml, P < 0.01). Kim-1 is associated with development of RAS-mediated renal damage. Antifibrotic treatment through RAS blockade or p38 MAP kinase inhibition reduced Kim-1 in the homozygous Ren2 model.

Aldosterone↗

PubMed2006

Mineralocorticoid receptor blockade confers renoprotection in preexisting chronic cyclosporine nephrotoxicity.

Recent studies from our laboratory have shown that the mineralocorticoid receptor (MR) blockade with spironolactone (Sp) prevented renal dysfunction and reduced renal injury in both acute and chronic cyclosporine (CsA) nephrotoxicity. This study was designed to evaluate whether Sp administration reduces functional and structural renal damage associated in the setting of preexisting chronic CsA nephrotoxicity. Twenty eight male Wistar rats were fed a low-sodium diet. Fourteen received vehicle (V) and the others were treated with CsA (15 mg/kg sc). After 18 days one half of each group received Sp (20 mg/kg po) for the subsequent 18 days. Creatinine clearance, arteriolopathy, tubulointerstitial fibrosis, arteriolar thickening, glomerular diameter, apoptosis index and TGF-beta, procaspase-3, and kidney injury molecule 1 (Kim-1) mRNA levels as well as Kim-1 shedding in urine were evaluated. Sp reduced the progression of renal dysfunction and tubulointerstitial fibrosis in preexisting chronic CsA nephrotoxicity. There was a significant reduction of arteriolar thickening in the CsA+Sp group that was associated with greater glomerular diameter and reduction of apoptosis index. These renoprotective effects were associated with reduction of TGF-beta, procaspase-3, and Kim-1 mRNA levels as well as Kim-1 shedding into the urine. In conclusion, MR blockade with Sp prevented the progression of renal injury in preexisting chronic CsA nephropathy. These results suggest that Sp may reduce CsA-induced established nephrotoxicity in patients.

Animals↗

PubMed2006

Methylmercury-induced toxicity is mediated by enhanced intracellular calcium through activation of phosphatidylcholine-specific phospholipase C.

Methylmercury (MeHg) is a ubiquitous environmental toxicant to which humans can be exposed by ingestion of contaminated food. MeHg has been suggested to exert its toxicity through its high reactivity to thiols, generation of arachidonic acid and reactive oxygen species (ROS), and elevation of free intracellular Ca(2+) levels ([Ca(2+)](i)). However, the precise mechanism has not been fully defined. Here we show that phosphatidylcholine-specific phospholipase C (PC-PLC) is a critical pathway for MeHg-induced toxicity in MDCK cells. D609, an inhibitor of PC-PLC, significantly reversed the toxicity in a time- and dose-dependent manner with concomitant inhibition of the diacylglycerol (DAG) generation and the phosphatidylcholine (PC)-breakdown. MeHg activated the group IV cytosolic phospholipase A(2) (cPLA(2)) and acidic form of sphingomyelinase (A-SMase) downstream of PC-PLC, but these enzymes as well as protein kinase C (PKC) were not linked to the toxicity by MeHg. Furthermore, MeHg produced ROS, which did not affect the toxicity. Addition of EGTA to culture media resulted in partial decrease of [Ca(2+)](i) and partially blocked the toxicity. In contrast, when the cells were treated with MeHg in the presence of Ca(2+) in the culture media, D609 completely prevented cell death with parallel decrease in [Ca(2+)](i). Our results demonstrated that MeHg-induced toxicity was linked to elevation of [Ca(2+)](i) through activation of PC-PLC, but not attributable to the signaling pathways such as cPLA(2), A-SMase, and PKC, or to the generation of ROS.

Animals↗

PubMed2006

Orchiectomy attenuates post-ischemic oxidative stress and ischemia/reperfusion injury in mice. A role for manganese superoxide dismutase.

Males are much more susceptible to ischemia/reperfusion (I/R)-induced kidney injury when compared with females. Recently we reported that the presence of testosterone, rather than the absence of estrogen, plays a critical role in gender differences in kidney susceptibility to I/R injury in mice. Although reactive oxygen species and antioxidant defenses have been implicated in I/R injury, their roles remain to be defined. Here we report that the orchiectomized animal had significantly less lipid peroxidation and lower hydrogen peroxide levels in the kidney 4 and 24 h after 30 min of bilateral renal ischemia when compared with intact or dihydrotestosterone-treated orchiectomized males. The post-ischemic kidney expression and activity of manganese superoxide dismutase (MnSOD) in orchiectomized mice was much greater than in intact or dihydrotestosterone-administered orchiectomized mice. Four hours after 30 min of bilateral ischemia, superoxide formation was significantly lower in orchiectomized mice than in intact mice. In Madin-Darby canine kidney cells, a kidney epithelial cell line, 1 mm H(2)O(2) decreased MnSOD activity, an effect that was potentiated by pretreatment with dihydrotestosterone. Orchiectomy prevented the post-ischemic decrease of catalase activity. Treatment of male mice with manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP), a SOD mimetic, reduced the post-ischemic increase of plasma creatinine, lipid peroxidation, and tissue hydrogen peroxide. These results suggest that orchiectomy accelerates the post-ischemic activation of MnSOD and reduces reactive oxygen species and lipid peroxidation, resulting in reduced kidney susceptibility to I/R injury.

Animals↗

PubMed2006

Tubular kidney injury molecule-1 in protein-overload nephropathy.

Kim-1, a recently discovered membrane protein, is undetectable in normal kidneys but markedly induced in proximal tubules after ischemic and toxic injury. The function of Kim-1 is unclear, but it is implicated in damage/repair processes. The Kim-1 ectodomain is cleaved by metalloproteinases and detectable in urine. We studied Kim-1 in a nontoxic, nonischemic, model of tubulointerstitial damage caused by acute proteinuria. Uninephrectomized (NX) rats received daily (ip) injections of 2 g BSA (NX+BSA, n = 12) or saline (NX, n = 6) for 3 wk. Kidneys were stained for various damage markers by immunohistochemistry (IHC). Kim-1 mRNA (RT-PCR, in situ hybridization), protein (IHC, Western blotting), and urinary Kim-1 (Luminex) were determined. Spatial relations between Kim-1 and other damage markers were studied by double labeling IHC. NX+BSA rats developed massive proteinuria (1,217 +/- 313 vs. 18 +/- 2 mg/day in NX, P < 0.001) and significant renal damage. Kim-1 mRNA was upregulated eightfold in NX+BSA (ratio Kim-1/beta-actin, 4.08 +/- 2.56 vs. 0.52 +/- 0.64 in NX, P < 0.001) and localized to damaged tubules. Kim-1 protein expression was markedly induced in NX+BSA (2.46 +/- 1.19 vs. 0.39 +/- 0.10% staining/field in NX, P < 0.001). Urinary Kim-1 was significantly elevated in NX+BSA (921 +/- 592 vs. 87 +/- 164 pg/ml in NX, P < 0.001) and correlated with tissue Kim-1 expression (r = 0.66, P =0.02). Kim-1 protein was found at the apical membrane of dilated nephrons. Kim-1 expression was limited to areas with inflammation (MØ), fibrosis (alpha-smooth muscle actin), and tubular damage (osteopontin), and only occasionally with tubular dedifferentiation (vimentin). These results implicate involvement of Kim-1 in the pathogenesis of proteinuria-induced renal damage/repair. Urinary Kim-1 levels may serve as a marker of proteinuria-induced renal damage.

Animals↗

PubMed2006

Attenuation of the pulmonary inflammatory response following butylated hydroxytoluene treatment of cytosolic phospholipase A2 null mice.

Administration of butylated hydroxytoluene (BHT) to mice causes lung damage characterized by the death of alveolar type I pneumocytes and the proliferation and subsequent differentiation of type II cells to replace them. Herein, we demonstrate this injury elicits an inflammatory response marked by chemokine secretion, alveolar macrophage recruitment, and elevated expression of enzymes in the eicosanoid pathway. Cytosolic phospholipase A(2) (cPLA(2)) catalyzes release of arachidonic acid from membrane phospholipids to initiate the synthesis of prostaglandins and other inflammatory mediators. A role for cPLA(2) in this response was examined by determining cPLA(2) expression and enzymatic activity in distal respiratory epithelia and macrophages and by assessing the consequences of cPLA(2) genetic ablation. BHT-induced lung inflammation, particularly monocyte infiltration, was depressed in cPLA(2) null mice. Monocyte chemotactic protein-1 (MCP-1) content in bronchoalveolar lavage fluid increases after BHT treatment but before monocyte influx, suggesting a causative role. Bronchiolar Clara cells isolated from cPLA(2) null mice secrete less MCP-1 than Clara cells from wild-type mice, consistent with the hypothesis that cPLA(2) is required to secrete sufficient MCP-1 to induce an inflammatory monocytic response.

Animals↗

PubMed2006

Group V secretory phospholipase A2 translocates to the phagosome after zymosan stimulation of mouse peritoneal macrophages and regulates phagocytosis.

We have previously reported that group V secretory phospholipase A2 (sPLA2) amplifies the action of cytosolic phospholipase A2(cPLA2) alpha in regulating eicosanoid biosynthesis by mouse peritoneal macrophages stimulated with zymosan (Satake, Y., Diaz, B. L., Balestrieri, B., Lam, B. K., Kanaoka, Y., Grusby, M. J., and Arm, J. P. (2004) J. Biol. Chem. 279, 16488-16494). To further understand the role of group V sPLA2, we studied its localization in resting mouse peritoneal macrophages before and after stimulation with zymosan and the effect of deletion of the gene encoding group V sPLA2 on phagocytosis of zymosan. We report that group V sPLA2 is present in the Golgi apparatus and recycling endosome in the juxtanuclear region of resting peritoneal macrophages. Upon ingestion of zymosan by mouse peritoneal macrophages, group V sPLA2 is recruited to the phagosome. There it co-localizes with cPLA2alpha, 5-lipoxygenase, 5-lipoxygenase-activating protein, and leukotriene C4 synthase. Using immunostaining for the cysteinyl leukotrienes in carbodiimide-fixed cells, we show, for the first time, that the phagosome is a site of cysteinyl leukotriene formation. Furthermore, peritoneal macrophages from group V sPLA2-null mice demonstrated a >50% attenuation in phagocytosis of zymosan particles, which was restored by adenoviral expression of group V sPLA2 but IIA not group sPLA2. These data demonstrate that group V sPLA2 contributes to the innate immune response both through regulation of eicosanoid generation in response to a phagocytic stimulus and also as a component of the phagocytic machinery.

Animals↗

PubMed2006

Mechanistic biomarkers for cytotoxic acute kidney injury.

Acute kidney injury is a common condition and is associated with a high mortality rate. It has been recognised that routinely used measures of renal function, such as levels of blood urea nitrogen and serum creatinine, increase significantly only after substantial kidney injury occurs and then with a time delay. Insensitivity of such tests delays the diagnosis in humans, making it particularly challenging to administer putative therapeutic agents in a timely fashion. Furthermore, this insensitivity affects the evaluation of toxicity in preclinical studies by allowing drug candidates, which have low, but nevertheless important, nephrotoxic side effects in animals, to pass the preclinical safety criteria only to be found to be clinically nephrotoxic with great human costs. This review presents the current status of sensitive and specific biomarkers to detect preclinical and clinical renal injury and summarises the techniques used to quantitate these biomarkers in biological fluids.

Acute Kidney Injury↗

PubMed2005

Release of free F2-isoprostanes from esterified phospholipids is catalyzed by intracellular and plasma platelet-activating factor acetylhydrolases.

F2-isoprostanes are produced in vivo by nonenzymatic peroxidation of arachidonic acid esterified in phospholipids. Increased urinary and plasma F2-isoprostane levels are associated with a number of human diseases. These metabolites are regarded as excellent markers of oxidant stress in vivo. Isoprostanes are initially generated in situ, i.e. when the arachidonate precursor is esterified in phospholipids, and they are subsequently released in free form. Although the mechanism(s) responsible for the release of free isoprostanes after in situ generation in membrane phospholipids is, for the most part, unknown, this process is likely mediated by phospholipase A2 activity(ies). Here we reported that human plasma contains an enzymatic activity that catalyzes this reaction. The activity associates with high density and low density lipoprotein and comigrates with platelet-activating factor (PAF) acetylhydrolase on KBr density gradients. Plasma samples from subjects deficient in PAF acetylhydrolase do not release F2-isoprostanes from esterified precursors. The intracellular PAF acetylhydrolase II, which shares homology to the plasma enzyme, also catalyzes this reaction. We found that both the intracellular and plasma PAF acetylhydrolases have high affinity for esterified F2-isoprostanes. However, the rate of esterified F2-isoprostane hydrolysis is much slower compared with the rate of hydrolysis of other substrates utilized by these enzymes. Studies using PAF acetylhydrolase transgenic mice indicated that these animals have a higher capacity to release F2-isoprostanes compared with nontransgenic littermates. Our results suggested that PAF acetylhydrolases play key roles in the hydrolysis of F2-isoprostanes esterified on phospholipids in vivo.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed2005

Acute kidney injury, mortality, length of stay, and costs in hospitalized patients.

The marginal effects of acute kidney injury on in-hospital mortality, length of stay (LOS), and costs have not been well described. A consecutive sample of 19,982 adults who were admitted to an urban academic medical center, including 9210 who had two or more serum creatinine (SCr) determinations, was evaluated. The presence and degree of acute kidney injury were assessed using absolute and relative increases from baseline to peak SCr concentration during hospitalization. Large increases in SCr concentration were relatively rare (e.g., >or=2.0 mg/dl in 105 [1%] patients), whereas more modest increases in SCr were common (e.g., >or=0.5 mg/dl in 1237 [13%] patients). Modest changes in SCr were significantly associated with mortality, LOS, and costs, even after adjustment for age, gender, admission International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis, severity of illness (diagnosis-related group weight), and chronic kidney disease. For example, an increase in SCr >or=0.5 mg/dl was associated with a 6.5-fold (95% confidence interval 5.0 to 8.5) increase in the odds of death, a 3.5-d increase in LOS, and nearly 7500 dollars in excess hospital costs. Acute kidney injury is associated with significantly increased mortality, LOS, and costs across a broad spectrum of conditions. Moreover, outcomes are related directly to the severity of acute kidney injury, whether characterized by nominal or percentage changes in serum creatinine.

Acute Disease↗

PubMed2005

Urinary kidney injury molecule-1: a sensitive quantitative biomarker for early detection of kidney tubular injury.

Sensitive and specific biomarkers are needed to detect early kidney injury. The objective of the present work was to develop a sensitive quantitative urinary test to identify renal injury in the rodent to facilitate early assessment of pathophysiological influences and drug toxicity. Two mouse monoclonal antibodies were made against the purified ectodomain of kidney injury molecule-1 (Kim-1), and these were used to construct a sandwich Kim-1 ELISA. The assay range of this ELISA was 50 pg/ml to 5 ng/ml, with inter- and intra-assay variability of <10%. Urine samples were collected from rats treated with one of three doses of cisplatin (2.5, 5, or 7.5 mg/kg). At one day after each of the doses, there was an approximately three- to fivefold increase in the urine Kim-1 ectodomain, whereas other routinely used biomarkers measured in this study [plasma creatinine, blood urea nitrogen (BUN), urinary N-acetyl-beta-glucosaminidase (NAG), glycosuria, proteinuria] lacked the sensitivity to show any sign of renal damage at this time point. When rats were subjected to increasing periods (10, 20, 30, or 45 min) of bilateral ischemia, there was an increasing amount of urinary Kim-1 detected. After only 10 min of bilateral ischemia, Kim-1 levels on day 1 were 10-fold higher (5 ng/ml) than control levels, whereas plasma creatinine and BUN were not increased and there was no glycosuria, increased proteinuria, or increased urinary NAG levels. Thus urinary Kim-1 levels serve as a noninvasive, rapid, sensitive, reproducible, and potentially high-throughput method to detect early kidney injury in pathophysiological studies and in preclinical drug development studies for risk-benefit profiling of pharmaceutical agents.

Animals↗

PubMed2005

cPLA2-interacting protein, PLIP, causes apoptosis and decreases G1 phase in mesangial cells.

The balance between proliferation and apoptosis of mesangial cells is a critical component of proliferative glomerulonephritis. The regulation of cell proliferation and apoptosis is linked at the level of the cell cycle (Shankland SJ. Kidney Int 52: 294-308, 199). cPLA2-interacting protein (PLIP), the Tip60 splice variant, interacts with cPLA2 and enhances the susceptibility of renal mesangial cells to serum deprivation-induced apoptosis (Sheridan AM, Force T, Yoon HJ, O'Leary E, Choukroun G, Taheri MR, and Bonventre JV. Mol Cell Biol 21: 4470-4481, 2001). We report that adenoviral-driven PLIP expression results in enhanced apoptosis of non-serum-deprived mesangial cells associated with a marked decrease in G0/G1 phase cells. The effect of PLIP on the cell cycle may be independent of its interaction with cPLA2 because a mutation of PLIP that does not interact with cPLA2 also causes a decrease in G0/G1 cells. Endogenous PLIP and Tip60 protein levels are increased in cells exposed to injurious stimuli including X-irradiation and H2O2, but the intracellular localization of the splice variants may differ. Whereas PLIP localizes in the nucleus of all mesangial cells, Tip60 localizes in the cytosol of untreated mesangial cells and of cells exposed to low concentrations (50-200 microM) of H2O2. Tip60 is targeted to the nucleus of cells exposed to high concentrations (1-2 mM) of H2O2. We conclude that PLIP may cause cells to exit from the cell cycle after the S phase and may function as part of a G2/M checkpoint mechanism. Tip60 splice variants may function in both cytosolic and nuclear signaling pathways in mesangial cells.

Animals↗