Gold nanoparticles reduce tubule-interstitial injury and proteinuria in a murine model of subclinical acute kidney injury

Subclinical acute kidney injury (subAKI) is characterized by tubule-interstitial injury without significant changes in glomerular function. SubAKI is associated with the pathogenesis and progression of acute and chronic kidney diseases. Currently, therapeutic strategies to treat subAKI are limited. The use of gold nanoparticles (AuNPs) has shown promising benefits in different models of diseases. However, their possible effects on subAKI are still unknown. Here, we investigated the effects of AuNPs on a mouse model of subAKI. Animals with subAKI showed increased functional and histopathologic markers of tubular injury. There were no changes in glomerular function and structure. The animals with subAKI also presented an inflammatory profile demonstrated by activation of Th1 and Th17 cells in the renal cortex. This phenotype was associated with decreased megalin-mediated albumin endocytosis and expression of proximal tubular megalin. AuNP treatment prevented tubule-interstitial injury induced by subAKI. This effect was associated with a shift to an anti-inflammatory Th2 response. Furthermore, AuNP treatment preserved megalin-mediated albumin endocytosis in vivo and in vitro. AuNPs were not nephrotoxic in healthy mice. These results suggest that AuNPs have a protective effect in the tubule-interstitial injury observed in subAKI, highlighting a promising strategy as a future antiproteinuric treatment.     

MMP-9 gene deletion mitigates microvascular loss in a model of ischemic acute kidney injury

Microvascular rarefaction following an episode of acute kidney injury (AKI) is associated with renal hypoxia and progression toward chronic kidney disease. The mechanisms contributing to microvascular rarefaction are not well-understood, although disruption in local angioregulatory substances is thought to contribute. Matrix metalloproteinase (MMP)-9 is an endopeptidase important in modifying the extracellular matrix (ECM) and remodeling the vasculature. We examined the role of MMP-9 gene deletion on microvascular rarefaction in a rodent model of ischemic AKI. MMP-9-null mice and background control (FVB/NJ) mice were subjected to bilateral renal artery clamping for 20 min followed by reperfusion for 14, 28, or 56 days. Serum creatinine level in MMP-9-null mice 24 h after injury [1.4 (SD 0.8) mg/dl] was not significantly different from FVB/NJ mice [1.5 (SD 0.6) mg/dl]. Four weeks after ischemic injury, FVB/NJ mice demonstrated a 30-40% loss of microvascular density compared with sham-operated (SO) mice. In contrast, microvascular density was not significantly different in the MMP-9-null mice at this time following injury compared with SO mice. FVB/NJ mice had a 50% decrease in tissue vascular endothelial growth factor (VEGF) 2 wk after ischemic insult compared with SO mice. A significant difference in VEGF was not observed in MMP-9-null mice compared with SO mice. There was no significant difference in the liberation of angioinhibitory fragments from the ECM between MMP-9-null mice and FVB/NJ mice following ischemic injury. In conclusion, MMP-9 deletion stabilizes microvascular density following ischemic AKI in part by preserving tissue VEGF levels.     

Regulator of calcineurin 1 deletion attenuates mitochondrial dysfunction and apoptosis in acute kidney injury through JNK/Mff signaling pathway

Ischemia-reperfusion (I/R) induced acute kidney injury (AKI), characterized by excessive mitochondrial damage and cell apoptosis, remains a clinical challenge. Recent studies suggest that regulator of calcineurin 1 (RCAN1) regulates mitochondrial function in different cell types, but the underlying mechanisms require further investigation. Herein, we aim to explore whether RCAN1 involves in mitochondrial dysfunction in AKI and the exact mechanism. In present study, AKI was induced by I/R and cisplatin in RCAN1^flox/flox mice and mice with renal tubular epithelial cells (TECs)-specific deletion of RCAN1. The role of RCAN1 in hypoxia-reoxygenation (HR) and cisplatin-induced injury in human renal proximal tubule epithelial cell line HK-2 was also examined by overexpression and knockdown of RCAN1. Mitochondrial function was assessed by transmission electron microscopy, JC-1 staining, MitoSOX staining, ATP production, mitochondrial fission and mitophagy. Apoptosis was detected by TUNEL assay, Annexin V-FITC staining and Western blotting analysis of apoptosis-related proteins. It was found that protein expression of RCAN1 was markedly upregulated in I/R- or cisplatin-induced AKI mouse models, as well as in HR models in HK-2 cells. RCAN1 deficiency significantly reduced kidney damage, mitochondrial dysfunction, and cell apoptosis, whereas RCAN1 overexpression led to the opposite phenotypes. Our in-depth mechanistic exploration demonstrated that RCAN1 increases the phosphorylation of mitochondrial fission factor (Mff) by binding to downstream c-Jun N-terminal kinase (JNK), then promotes dynamin related protein 1 (Drp1) migration to mitochondria, ultimately leads to excessive mitochondrial fission of renal TECs. In conclusion, our study suggests that RCAN1 could induce mitochondrial dysfunction and apoptosis by activating the downstream JNK/Mff signaling pathway. RCAN1 may be a potential therapeutic target for conferring protection against I/R- or cisplatin-AKI. Subject terms: Pathogenesis, Medical research     

TNFR1-dependent pulmonary apoptosis during ischemic acute kidney injury

Despite advancements in renal replacement therapy, the mortality rate for acute kidney injury (AKI) remains unacceptably high, likely due to remote organ injury. Kidney ischemia-reperfusion injury (IRI) activates cellular and soluble mediators that incite a distinct pulmonary proinflammatory and proapoptotic response. Tumor necrosis factor receptor 1 (TNFR1) has been identified as a prominent death receptor activated in the lungs during ischemic AKI. We hypothesized that circulating TNF-α released from the postischemic kidney induces TNFR1-mediated pulmonary apoptosis, and we aimed to elucidate molecular pathways to programmed cell death. Using an established murine model of kidney IRI, we characterized the time course for increased circulatory and pulmonary TNF-α levels and measured concurrent upregulation of pulmonary TNFR1 expression. We then identified TNFR1-dependent pulmonary apoptosis after ischemic AKI using TNFR1-/- mice. Subsequent TNF-α signaling disruption with Etanercept implicated circulatory TNF-α as a key soluble mediator of pulmonary apoptosis and lung microvascular barrier dysfunction during ischemic AKI. We further elucidated pathways of TNFR1-mediated apoptosis with NF-κB (Complex I) and caspase-8 (Complex II) expression and discovered that TNFR1 proapoptotic signaling induces NF-κB activation. Additionally, inhibition of NF-κB (Complex I) resulted in a proapoptotic phenotype, lung barrier leak, and altered cellular flice inhibitory protein signaling independent of caspase-8 (Complex II) activation. Ischemic AKI activates soluble TNF-α and induces TNFR1-dependent pulmonary apoptosis through augmentation of the prosurvival and proapoptotic TNFR1 signaling pathway. Kidney-lung crosstalk after ischemic AKI represents a complex pathological process, yet focusing on specific biological pathways may yield potential future therapeutic targets.     

Important role of apoptosis signal-regulating kinase 1 in ischemic acute kidney injury

We investigated the role of apoptosis signal-regulating kinase 1 (ASK1) in ischemia/reperfusion (I/R)-induced acute kidney injury (AKI). Blood urea nitrogen (BUN) and serum creatinine were significantly higher in ASK1+/+ mice than in ASK1−/− mice after I/R injury. Renal histology of ASK1+/+ mice showed significantly greater tubular necrosis and degradation. In ASK1−/− mice, phosphorylation of ASK1, JNK, and p38K, and the number of TUNEL-positive cells and infiltrated leukocytes decreased after I/R injury. Apoptotic changes were significantly decreased in cultured renal tubular epithelial cells (TECs) from ASK1−/− mice under hypoxic condition. Transfection with dominant-active ASK1 induced apoptosis in TECs. Protein expression of monocyte chemoattractant protein-1 (MCP-1) was significantly weaker in ASK1−/− mice after I/R injury. Transfection with dominant negative-ASK1 significantly decreased MCP-1 production in TECs. These results demonstrated that ASK1 is activated in I/R-induced AKI, and blockage of ASK1 attenuates renal tubular apoptosis, MCP-1 expression, and renal function.     

Caspase-1-deficient mice have delayed neutrophil apoptosis and a prolonged inflammatory response to lipopolysaccharide-induced acute lung injury

Caspase-1, the prototypic caspase, is known to process the cytokines IL-1beta and IL-18 to mature forms but it is unclear whether, like other caspases, it can induce apoptosis by activation of downstream protease cascades. Neutrophils are known to express caspase-1, to release IL-1beta and to undergo rapid, caspase-dependent apoptosis. We examined apoptosis and IL-1beta production in peripheral blood neutrophils of caspase-1-deficient and wild-type mice. Constitutive apoptosis of caspase-1-deficient neutrophils was delayed compared with wild-type neutrophils and LPS-mediated inhibition of apoptosis was absent, but caspase-1-deficient neutrophils were susceptible to Fas-mediated apoptosis. LPS-stimulated IL-1beta production was absent from caspase-1-deficient neutrophils. To ascertain whether these differences in apoptosis and IL-1beta production would alter the response to acute lung injury, we studied pulmonary neutrophil accumulation following intratracheal administration of LPS. Caspase-1-deficient mice showed increased, predominantly neutrophilic pulmonary inflammation, but inflammation had resolved in both wild-type and deficient animals by 72 h after LPS instillation. IL-1beta production was increased in wild-type lungs but was also detected in caspase-1-deficient mice. We conclude that caspase-1 modulates apoptosis of both peripheral blood and inflammatory neutrophils, but is not essential for IL-1beta production in the lung.     

Comparison of the course of biomarker changes and kidney injury in a rat model of drug-induced acute kidney injury

Objective: To aid in evaluating the performance of biomarkers, we measured kidney injury biomarkers in rat models of drug-induced acute kidney injury.

Methods and results: Rats were treated with site-specific nephrotoxins, puromycin, gentamicin, cisplatin, or 2-bromoethylamine. Fifteen biomarkers (β-2-microglobulin, calbindin, clusterin, cystatin-C, KIM-1, GST-α, GST-μ, NGAL, osteopontin, EGF, TIMP-1, VEGF, albumin, RPA-1, and urinary total protein) were examined in comparison with BUN, serum creatinine, and NAG. Some biomarkers, which were different depending in each nephrotoxin, showed ability to detect the prodromal stage of drug-induced kidney injury. Characteristic changing patterns of biomarkers were also found depending on the specific lesion site in the kidney.

Conclusion: These data suggested that establishment of a suitable biomarker panel would facilitate detection of site-specific kidney injury with high sensitivity.     

Comparison of the course of biomarker changes and kidney injury in a rat model of drug-induced acute kidney injury

Objective: To aid in evaluating the performance of biomarkers, we measured kidney injury biomarkers in rat models of drug-induced acute kidney injury. Methods and results: Rats were treated with site-specific nephrotoxins, puromycin, gentamicin, cisplatin, or 2-bromoethylamine. Fifteen biomarkers (β-2-microglobulin, calbindin, clusterin, cystatin-C, KIM-1, GST-α, GST-μ, NGAL, osteopontin, EGF, TIMP-1, VEGF, albumin, RPA-1, and urinary total protein) were examined in comparison with BUN, serum creatinine, and NAG. Some biomarkers, which were different depending in each nephrotoxin, showed ability to detect the prodromal stage of drug-induced kidney injury. Characteristic changing patterns of biomarkers were also found depending on the specific lesion site in the kidney. Conclusion: These data suggested that establishment of a suitable biomarker panel would facilitate detection of site-specific kidney injury with high sensitivity.     

Characterization of a murine model of monocrotaline pyrrole-induced acute lung injury

Background

New animal models of chronic pulmonary hypertension in mice are needed. The injection of monocrotaline is an established model of pulmonary hypertension in rats. The aim of this study was to establish a murine model of pulmonary hypertension by injection of the active metabolite, monocrotaline pyrrole.

Methods

Survival studies, computed tomographic scanning, histology, bronchoalveolar lavage were performed, and arterial blood gases and hemodynamics were measured in animals which received an intravenous injection of different doses of monocrotaline pyrrole.

Results

Monocrotaline pyrrole induced pulmonary hypertension in Sprague Dawley rats. When injected into mice, monocrotaline pyrrole induced dose-dependant mortality in C57Bl6/N and BALB/c mice (dose range 6–15 mg/kg bodyweight). At a dose of 10 mg/kg bodyweight, mice developed a typical early-phase acute lung injury, characterized by lung edema, neutrophil influx, hypoxemia and reduced lung compliance. In the late phase, monocrotaline pyrrole injection resulted in limited lung fibrosis and no obvious pulmonary hypertension.

Conclusion

Monocrotaline and monocrotaline pyrrole pneumotoxicity substantially differs between the animal species.     

Hemodynamic changes in the kidney in a pediatric rat model of sepsis-induced acute kidney injury

Sepsis is a leading cause of acute kidney injury (AKI) and mortality in children. Understanding the development of pediatric sepsis and its effects on the kidney are critical in uncovering new therapies. The goal of this study was to characterize the development of sepsis-induced AKI in the clinically relevant cecal ligation and puncture (CLP) model of peritonitis in rat pups 17-18 days old. CLP produced severe sepsis demonstrated by time-dependent increase in serum cytokines, NO, markers of multiorgan injury, and renal microcirculatory hypoperfusion. Although blood pressure and heart rate remained unchanged after CLP, renal blood flow (RBF) was decreased 61% by 6 h. Renal microcirculatory analysis showed the number of continuously flowing cortical capillaries decreased significantly from 69 to 48% by 6 h with a 66% decrease in red blood cell velocity and a 57% decline in volumetric flow. The progression of renal microcirculatory hypoperfusion was associated with peritubular capillary leakage and reactive nitrogen species generation. Sham adults had higher mean arterial pressure (118 vs. 69 mmHg), RBF (4.2 vs. 1.1 ml·min(-1)·g(-1)), and peritubular capillary velocity (78% continuous flowing capillaries vs. 69%) compared with pups. CLP produced a greater decrease in renal microcirculation in pups, supporting the notion that adult models may not be the most appropriate for studying pediatric sepsis-induced AKI. Lower RBF and reduced peritubular capillary perfusion in the pup suggest the pediatric kidney may be more susceptible to AKI than would be predicted using adults models.     

Complement-dependent injury and protection in a murine model of acute dextran sulfate sodium-induced colitis

Complement plays a key role in the pathophysiology of many inflammatory diseases, and in this study, we investigated the role of complement in the pathogenesis of inflammatory bowel disease. Compared to wild-type mice, mice deficient in C3 or factor B were protected from acute dextran sulfate sodium (DSS)-induced colitis. C1q/mannose-binding lectin (MBL) double-deficient mice, however, exhibited more severe colitis than wild-type mice. When mice were allowed to recover after DSS treatment, all C1q/MBL(-/-) mice died by day 2 of recovery period, and, surprisingly, all C3(-/-) and factor B(-/-) mice died by day 5. Serum endotoxin levels were significantly increased in complement-deficient mice prior to death, particularly in C1q/MBL(-/-) mice, and antibiotic treatment prevented the lethal effect of DSS in all complement-deficient mice. In contrast to complement deficiency, targeted complement inhibition with either complement receptor 2 (CR2)-Crry (blocks all pathways at C3 activation) or CR2-factor H (blocks alternative pathway) was highly protective at treating established acute colitis. Endotoxin levels remained low in complement-inhibited mice, and complement inhibition also reduced inflammatory cytokines, leukocyte infiltration, and tissue injury while improving wound repair and mucosal healing. CR2-factor H provided more effective protection than CR2-Crry. Thus, complement has both pathogenic and protective roles in acute DSS-induced colitis, and whereas the alternative pathway appears to play a key role in tissue inflammation and injury, the classical/lectin pathway provides important protection in terms of host defense and wound repair. Targeted inhibition of the alternative pathway may represent a therapeutic modality for treating acute phases of inflammatory bowel disease.     

Inhibition of TLR2 promotes graft function in a murine model of renal transplant ischemia-reperfusion injury

Toll-like receptors (TLRs) are important molecules involved in the activation of innate and subsequent development of adaptive immunity. TLRs are ligated by exogenous ligands from pathogens and by endogenous ligands released in inflammatory diseases. Activation of TLR leads to activation of NF-κB and release of proinflammatory cytokines, such as IL-6 and TNF-α. TLRs play an important role in the pathogenesis of renal diseases. Increased expression of TLRs have been associated with ischemic kidney damage, acute kidney injury, end-stage renal failure, acute renal transplant rejection, and delayed allograft function. OPN301 is a mouse anti-human TLR2 antibody that cross-reacts with mouse TLR2. We show that inhibition of TLR2 promotes graft function in an isograft model of renal transplantation. Recipient mice were treated intravenously with OPN301 before reperfusion of the transplanted kidney that had been subjected to 30 min of cold ischemia. After 5 d, the residual native kidney was removed, and renal transplant function was assessed 24 h later by measurement of blood urea nitrogen. Renal function in both saline- and isotype-treated mice was similar, with significant improvement in OPN301-treated mice (isotype-treated vs. OPN301-treated: 33.9±3.2 vs. 19.8±1.9 μM; P<0.01). The histopathological appearance corresponded with renal functional results. In OPN301-treated recipients, renal structure was well preserved, whereas in the saline-treated group, tubular injury was severe, with marked tubular thinning, epithelial shedding, cast formation and necrosis. Inhibition of TLR2 also leads to a decrease in C3d deposition, although it is unclear whether this is due directly to TLR2 inhibition or a decrease in renal inflammation. This study shows that inhibition of TLR2 with a therapeutic agent (OPN301) provides significant protection from ischemia/reperfusion injury in a model of kidney transplantation.     

ERK-mediated suppression of cilia in cisplatin-induced tubular cell apoptosis and acute kidney injury

In kidneys, each tubular epithelial cell contains a primary cilium that protrudes from the apical surface. Ciliary dysfunction was recently linked to acute kidney injury (AKI) following renal ischemia–reperfusion. Whether ciliary regulation is a general pathogenic mechanism in AKI remains unclear. Moreover, the ciliary change during AKI and its underlying mechanism are largely unknown. Here we examined the change of primary cilium and its role in tubular cell apoptosis and AKI induced by cisplatin, a chemotherapy agent with notable nephrotoxicity. In cultured human proximal tubular HK-2 epithelial cells, cilia became shorter during cisplatin treatment, followed by apoptosis. Knockdown of Kif3a or Polaris (cilia maintenance proteins) reduced cilia and increased apoptosis during cisplatin treatment. We further subcloned HK-2 cells and found that the clones with shorter cilia were more sensitive to cisplatin-induced apoptosis. Mechanistically, cilia-suppressed cells showed hyperphosphorylation or activation of ERK. Inhibition of ERK by U0126 preserved cilia during cisplatin treatment and protected against apoptosis in HK-2 cells. In C57BL/6 mice, U0126 prevented the loss of cilia from proximal tubules during cisplatin treatment and protected against AKI. U0126 up-regulated Polaris, but not Kif3a, in kidney tissues. It is suggested that ciliary regulation by ERK plays a role in cisplatin-induced tubular apoptosis and AKI.     

Macrophages mediate lung inflammation in a mouse model of ischemic acute kidney injury

Serum IL-6 is increased in acute kidney injury (AKI) and inhibition of IL-6 reduces AKI-mediated lung inflammation. We hypothesized that circulating monocytes produce IL-6 and that alveolar macrophages mediate lung inflammation after AKI via chemokine (CXCL1) production. To investigate systemic and alveolar macrophages in lung injury after AKI, sham operation or 22 min of renal pedicle clamping (AKI) was performed in three experimental settings: 1) systemic macrophage depletion via diphtheria toxin (DT) injection to CD11b-DTR transgenic mice, 2) DT injection to wild-type mice, and 3) alveolar macrophage depletion via intratracheal (IT) liposome-encapsulated clodronate (LEC) administration to wild-type mice. In mice with AKI and systemic macrophage depletion (CD11b-DTR transgenic administered DT) vs. vehicle-treated AKI, blood monocytes and lung interstitial macrophages were reduced, renal function was similar, serum IL-6 was increased, lung inflammation was improved, lung CXCL1 was reduced, and lung capillary leak was increased. In wild-type mice with AKI administered DT vs. vehicle, serum IL-6 was increased. In mice with AKI and alveolar macrophage depletion (IT-LEC) vs. AKI with normal alveolar macrophage content, blood monocytes and lung interstitial macrophages were similar, alveolar macrophages were reduced, renal function was similar, lung inflammation was improved, lung CXCL1 was reduced, and lung capillary leak was increased. In conclusion, administration of DT in AKI is proinflammatory, limiting the use of the DTR-transgenic model to study systemic effects of AKI. Mice with AKI and either systemic mononuclear phagocyte depletion or alveolar macrophage depletion had reduced lung inflammation and lung CXCL1, but increased lung capillary leak; thus, mononuclear phagocytes mediate lung inflammation, but they protect against lung capillary leak after ischemic AKI. Since macrophage activation and chemokine production are key events in the development of acute lung injury (ALI), these data provide further evidence that AKI may cause ALI.     

Angiogenic growth factors in the pathophysiology of a murine model of acute lung injury

Capillary leakage and alveolar edema are hallmarks of acute lung injury (ALI). Neutrophils and serum macromolecules enter alveoli, promoting inflammation. Vascular endothelial growth factor (VEGF) causes plasma leakage in extrapulmonary vessels. Angiopoietin (Ang)-1 and -4 stabilize vessels, attenuating capillary leakage. We hypothesized that VEGF and Ang-1 and -4 modulate vessel leakage in the lung, contributing to the pathogenesis of ALI. We examined a murine model of lipopolysaccharide (LPS)-induced ALI. C57BL/6 and 129/J mice were studied at baseline and 24, 48, and 96 h after single or multiple doses of aerosolized LPS. Both strains exhibited time- and dose-dependent increases in inflammation and a deterioration of lung mechanics. Bronchoalveolar lavage (BAL) protein levels increased significantly, suggesting capillary leakage. Increased BAL neutrophil and total protein content correlated with time-dependent increased tissue VEGF and decreased Ang-1 and -4 levels, with peak VEGF and minimum Ang-1 and -4 expression after 96 h of LPS challenge. These data suggest that changes in the balance between VEGF and Ang-1 and -4 after LPS exposure may modulate neutrophil influx, protein leakage, and alveolar flooding during early ALI.     

Expression of cardiomyocytic markers on adipose tissue-derived cells in a murine model of acute myocardial injury

Animal and early clinical studies have provided evidence suggesting that intracoronary administration of autologous bone marrow-derived cells results in improved outcome following myocardial infarction. Animal studies with cultured marrow stromal cells (MSC) have provided similar data. Cells with properties that are similar to MSC have been identified in adipose tissue. Other groups have demonstrated in vivo differentiation of adipose tissue-derived cells (ADC) into cells exhibiting biochemical and functional markers of cardiac myocytes, including spontaneous beating.Based on these observations, the objective of the present study was to determine whether ADC might undergo similar differentiation in vivo in the context of myocardial injury.ADC were isolated from subcutaneous adipose tissue of Rosa26 mice (which express the beta-galactosidase transgene in almost every tissue) and injected into the intraventricular chamber of B6129S recipient mice immediately following induction of myocardial cryoinjury. Groups of recipients were euthanized at 24 hours, 7 and 14 days post surgery and examined for the presence of donor-derived cells within the heart.Beta-gal positive cells were identified in the infarcts of ADC-treated animals. No staining was observed in uninjured myocardium or in infarcts of control animals. Immunohistochemical analysis revealed co-expression of beta-gal with Myosin Heavy Chain, Nkx2.5 and with Troponin I. Co-expression of beta-galactosidase with Connexin 43, CD31, von Willebrand factor, MyoD or CD45 was not detected.Thus, these data indicate that adipose tissue contains a population of cells that has the ability to engraft injured myocardium and that this engraftment is associated with expression of cardiomyocytic markers by donor-derived cells.     

Genetic deficiency of Smad3 protects against murine ischemic acute kidney injury

TGF-β1 contributes to chronic kidney disease, at least in part, via Smad3. TGF-β1 is induced in the kidney following acute ischemia, and there is increasing evidence that TGF-β1 may protect against acute kidney injury. As there is a paucity of information regarding the functional significance of Smad3 in acute kidney injury, the present study explored this issue in a murine model of ischemic acute kidney injury in Smad3(+/+) and Smad3(-/-) mice. We demonstrate that, at 24 h after ischemia, Smad3 is significantly induced in Smad3(+/+) mice, whereas Smad3(-/-) mice fail to express this protein in the kidney in either the sham or postischemic groups. Compared with Smad3(+/+) mice, and 24 h following ischemia, Smad3(-/-) mice exhibited greater preservation of renal function as measured by blood urea nitrogen (BUN) and serum creatinine; less histological injury assessed by both semiquantitative and qualitative analyses; markedly suppressed renal expression of IL-6 and endothelin-1 mRNA (but comparable expression of MCP-1, TNF-α, and heme oxygenase-1 mRNA); and no increase in plasma IL-6 levels, the latter increasing approximately sixfold in postischemic Smad3(+/+) mice. We conclude that genetic deficiency of Smad3 confers structural and functional protection against acute ischemic injury to the kidney. We speculate that these effects may be mediated through suppression of IL-6 production. Finally, we suggest that upregulation of Smad3 after an ischemic insult may contribute to the increased risk for chronic kidney disease that occurs after acute renal ischemia.     

Evaluation of early regenerative processes in a preclinical pig model of acute kidney injury

Renal failure due to ischemic injury is a common denominator of various clinical situations in critically ill patients. This study was designed to characterize the TPSO/Cholesterol synthesis and cell division pathways in response to different levels of ischemia. Porcine kidneys were subjected to either 60 min-warm ischemia (WI) or auto-transplanted after cold storage for 24 h at 4°C (CS), or both conditions (WI+CS), pathway activation and function were evaluated at 3 h, 3 and 7 days after reperfusion. CS combined to WI affects renal functions indicating a high degree of injury. During the first week of reperfusion, renal levels of free and esterified cholesterol, major cellular components, increased in CS group with an attenuated production when WI was associated. CS and WI+CS groups exhibited an elevated expression of cell cycle induction markers such as PCNA and stathmin. TSPO expression was highest in groups with the lowest injury, and correlated with kidney outcome, revealing its potential for diagnosis.     

Method used to establish a large animal model of drug-induced acute kidney injury

Acute kidney injury is a serious health hazard disease due to its complex etiology and lack of effective treatments, resulting in high medical costs and high mortality. At present, a large number of basic research studies on acute kidney injury have been carried out. However, acute kidney injury models established in rodents sometimes do not simulate the course of human disease well. Research in large animal models of acute kidney injury is relatively rare, and methods to build a mature model of acute kidney injury have failed. Because its kidney anatomy and morphology are very similar to those in humans, the mini pig is an ideal animal in which to model kidney disease. Nephrotoxic drug-induced acute kidney injury has a high incidence. In this study, we established models of acute kidney injury induced by two drugs (gentamicin and cisplatin). Finally, the model of cisplatin-induced acute kidney injury was developed successfully, but we found the model of gentamycin-induced acute kidney injury was not reproducible. Compared to other models, these models better represent acute kidney injury caused by antibiotics and chemotherapeutic drugs and provide a basis for the study of new treatments for acute kidney injury in a large animal model.