Animal Models Of Renal Disease Research Articles

High-Glucose-Induced Injury to Proximal Tubules of the Renal System Is Alleviated by Netrin-1 Suppression of Akt/mTOR.

The kidneys have a high level of Netrin-1 expression, which protects against some acute and chronic kidney disorders. However, it is yet unknown how Netrin-1 affects renal proximal tubule cells in diabetic nephropathy (DN) under pathological circumstances. Research has shown that autophagy protects the kidneys in animal models of renal disease. In this study, we looked at the probable autophagy regulation mechanism of Netrin-1 and its function in the pathogenesis of DN. We proved that in HK-2 cell, high blood sugar levels caused Netrin-1 to be downregulated, which then triggered the Akt/mTOR signaling pathway and enhanced cell death and actin cytoskeleton disruption. By adding Netrin-1 or an autophagy activator in vitro, these pathogenic alterations were reverted. Our results indicate that Netrin-1 stimulates autophagy by blocking the Akt/mTOR signaling pathway, which underlies high-glucose-induced malfunction of the renal proximal tubules. After HK-2 cells were incubated with Netrin-1 recombination protein and rapamycin under HG conditions for 24 h, the apoptosis was significantly reduced, as shown by the higher levels of Bcl-2, as well as lower levels of Bax and cleaved caspase-3 (P = 0.012, Cohen's d = 0.489, Glass's delta = 0.23, Hedges' g = 0.641). This study reveals that targeting Netrin-1-related signaling has therapeutic potential for DN and advances our knowledge of the processes operating in renal proximal tubules in DN.

Gender and sex in the development and progression of renal diseases

Sex-based disparities in nephrology have been a historically understudied area. In nephrology, gender differences exist with regard to the epidemiology, evolution and prognosis of chronic kidney disease (CKD). In some cases, these differences run contrary to the general population trends. We discuss such gender and sex disparities, including differing impact of traditional and novel risk factors, as well as hormonal factors, all of them potentially influencing propensity, progression and biochemical and psychological aspects of CKD. The factors involved in this gender disparity may include diet, kidney and glomerular size, differences in glomerular hemodynamics, and the direct effects of sex hormones. The progression rate of many renal diseases is affected by sex. In polycystic kidney disease, membranous nephropathy, immunoglobulin A nephropathy, and “chronic renal disease of unknown etiology”, men progress at a faster rate to end-stage renal failure than women do. In many, but not all, animal models of renal disease, estrogens slow progression rate. Animal and experimental studies have tried to offer further mechanistic explanations for gender differences in disease progression. It has been suggested that the gender dimorphism of CKD progression may represent the effects of the interaction of circulating steroids with specific kidney receptors. Endogenous estrogens have in general been considered to have anti-fibrotic and anti-apoptotic effects on the kidney. On the other hand, the faster decline of kidney function in men has been attributed to the specific pro-apoptotic and pro-fibrotic properties of androgens.

The Signaling Pathway of TNF Receptors: Linking Animal Models of Renal Disease to Human CKD.

Chronic kidney disease (CKD) has been recognized as a global public health problem. Despite the current advances in medicine, CKD-associated morbidity and mortality remain unacceptably high. Several studies have highlighted the contribution of inflammation and inflammatory mediators to the development and/or progression of CKD, such as tumor necrosis factor (TNF)-related biomarkers. The inflammation pathway driven by TNF-α, through TNF receptors 1 (TNFR1) and 2 (TNFR2), involves important mediators in the pathogenesis of CKD. Circulating levels of TNFRs were associated with changes in other biomarkers of kidney function and injury, and were described as predictors of disease progression, cardiovascular morbidity, and mortality in several cohorts of patients. Experimental studies describe the possible downstream signaling pathways induced upon TNFR activation and the resulting biological responses. This review will focus on the available data on TNFR1 and TNFR2, and illustrates their contributions to the pathophysiology of kidney diseases, their cellular and molecular roles, as well as their potential as CKD biomarkers. The emerging evidence shows that TNF receptors could act as biomarkers of renal damage and as mediators of the disease. Furthermore, it has been suggested that these biomarkers could significantly improve the discrimination of clinical CKD prognostic models.

Periostin in kidney diseases.

Chronic kidney disease is an incurable to date pathology, with renal replacement therapy through dialysis or transplantation being the only available option for end-stage patients. A deeper understanding of the molecular mechanisms governing the progression of kidney diseases will permit the identification of unknown mediators and potential novel markers or targets of therapy which promise more efficient diagnostic and therapeutic applications. Over the last years, periostin was established by several studies as a novel key player in the progression of renal disease. Periostin is de novo expressed focally by the injured kidney cells during the development of renal disease. In diverse cohorts of renal disease patients, the expression levels of periostin in the kidney and urine were highly correlated with the stage of the pathology and the decline of renal function. Subsequent studies in animal models demonstrated that periostin is centrally involved in mediating renal inflammation and fibrosis, contributing to the deterioration of renal structure and function. Genetic or pharmaco-genetic inhibition of periostin in animal models of renal disease was efficient in arresting the progression of the pathology. This review will summarize the recent advances on periostin in the field of kidney diseases and will discuss its utility of as a novel target of therapy for chronic kidney disease.

Selective Activation of AMPK β1-Containing Isoforms Improves Kidney Function in a Rat Model of Diabetic Nephropathy.

Diabetic nephropathy remains an area of high unmet medical need, with current therapies that slow down, but do not prevent, the progression of disease. A reduced phosphorylation state of adenosine monophosphate-activated protein kinase (AMPK) has been correlated with diminished kidney function in both humans and animal models of renal disease. Here, we describe the identification of novel, potent, small molecule activators of AMPK that selectively activate AMPK heterotrimers containing the β1 subunit. After confirming that human and rodent kidney predominately express AMPK β1, we explore the effects of pharmacological activation of AMPK in the ZSF1 rat model of diabetic nephropathy. Chronic administration of these direct activators elevates the phosphorylation of AMPK in the kidney, without impacting blood glucose levels, and reduces the progression of proteinuria to a greater degree than the current standard of care, angiotensin-converting enzyme inhibitor ramipril. Further analyses of urine biomarkers and kidney tissue gene expression reveal AMPK activation leads to the modulation of multiple pathways implicated in kidney injury, including cellular hypertrophy, fibrosis, and oxidative stress. These results support the need for further investigation into the potential beneficial effects of AMPK activation in kidney disease.

Monocyte chemoattractant protein-1 and the kidney.

Recently, initial studies have been carried out in patients using monocyte chemoattractant protein-1 (MCP-1) inhibitors. This review summarizes the known function of MCP-1 in regulating monocytes during inflammation and its role in inflammatory disease of the kidney. MCP-1 is one of the first chemokines described and plays an important role in renal inflammatory disease. The function of MCP-1 has been investigated and analyzed in both animal models of renal disease and renal patients. MCP-1 mediates firstly the release of monocytes from the bone marrow, and then generates a gradient in the endothelial glycocalyx to direct monocytes to sites of inflammation, thereby alleviating the migration of blood leukocytes into the inflamed tissue. In addition, MCP-1 has direct signaling effects in monocytes and influences migration, proliferation, and differentiation of leukocytes. Blockade of MCP-1 in several models of renal disease has ameliorated the disease, suggesting that inhibition of MCP-1 is a promising and valid strategy to treat patients with renal inflammatory disease. Understanding the role of MCP-1 in monocyte homeostasis and the implications of MCP-1 inhibition in renal disease will help in designing better diagnostic and therapeutic strategies in patients with inflammatory renal disease.

Regulation of Formyl Peptide Receptor 2 During Chronic Kidney Disease

The G‐protein coupled receptor formyl peptide receptor 2 (FPR2) integrates signals of multiple anti‐inflammatory and anti‐fibrotic mediators including lipoxin A4, resolvin D1, and annexin A1. Previous studies have demonstrated protective effects of FPR2 in animal models of renal disease but the localization of FPR2 in the healthy kidney and its regulation in chronic kidney disease (CKD) have not been elucidated. Aim of this study was to determine the renal localization of FPR2 under control conditions and in a rat model of CKD. Newborn rats were treated with the AT1R antagonist Candesartan from postnatal d1‐14 to impair nephrogenesis and examined at 11 moth of age (CKD rats). Expression of FPR2 was studied using immunohistochemistry (IHC) and double labeling immunofluorescence (IF) for FPR2 and markers for fibroblasts, myofibroblasts, macrophages, and endothelial cells. CKD rats showed signs of renal inflammation and fibrosis with a focal accumulation of macrophages, myofibroblasts and extracellular matrix components. IHC revealed expression of FPR2 in the tubulointerstitium of controls and a strong accumulation of FPR2 expressing cells in fibrotic areas of CKD animals. IF identified fibroblasts and endothelial cells as the predominant FPR2 expressing cell types in both groups. Abundant signal was further detected in macrophages and myofibroblasts in the fibrotic areas of CKD animals. Our results show that FPR2 is abundantly expressed in the kidneys of control and CKD animals. It may therefore play an important role in the regulation of normal renal function and exert anti‐inflammatory and anti‐fibrotic effects during CKD. FPR2 may thus provide a promising target for pharmacological intervention in the treatment of CKD.

Urinary sodium excretion is the main determinant of mineralocorticoid excretion rates in patients with chronic kidney disease

Blockade of the mineralocorticoid receptor (MR) in patients with chronic kidney disease (CKD) improves surrogate cardiovascular outcomes, such as left ventricular mass. Animal models of renal disease support a pathological role of mineralocorticoids, in the context of a high sodium intake. We aimed to assess the regulation of mineralocorticoid biosynthesis in patients with CKD. Seventy patients with CKD stages 3/4 and 30 patients with essential hypertension (EH) were recruited. Patients underwent detailed clinical phenotyping, drug history and biochemical assessment. Patients completed a 24-h urine collection for measurement of urinary tetrahydroaldosterone (THALDO) and tetrahydrocorticosterone (THDOC) excretion rates (measured using gas chromatography-mass spectrometry) and urinary electrolytes. The factors which correlated significantly with THALDO and THDOC excretion were entered into linear regression models. Patients with EH and CKD were well matched with no significant differences in gender, age or weight. The mean estimated glomerular filtration rate (eGFR) in CKD patients was 38.6/min/1.73 m(2). The mean urinary excretion rates of THALDO, THDOC and 24-h urinary sodium (24-h USod) were not significantly different between CKD and EH patients. The level of renal function did not correlate with THALDO or THDOC excretion. In patients with CKD, 24-h USodium (r = 0.614, P < 0.001) and 24-h UPotassium (r = 0.538, P < 0.001) were positively correlated with THALDO excretion. On multivariate linear regression analysis, 24-h USod was the strongest independent predictor (P = 0.004) of THALDO and THDOC excretion in CKD. In patients with EH, no relationship was seen between mineralocorticoid excretion and 24-h urinary sodium excretion. In patients with CKD, 24-h urinary sodium excretion is the strongest positive predictor of urinary mineralocorticoid excretion. The nature of this relationship is unexpected, novel, not seen in patients with EH and may explain the association seen between high urinary sodium excretion, mineralocorticoids and poor outcomes in patients with CKD.

Assessment of renal function in mice with unilateral ureteral obstruction using 99mTc-MAG3 dynamic scintigraphy

BackgroundRenal scintigraphy using 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) is widely used for the assessment of renal function in humans. However, the application of this method to animal models of renal disease is currently limited, especially in rodents. Here, we have applied 99mTc-MAG3 renal scintigraphy to a mouse model of unilateral ureteral obstruction (UUO) and evaluated its utility in studying obstructive renal disease.MethodsUUO mice were generated by complete ligation of the left ureter. Sham-operated mice were used as a control. Renal function was investigated on days 0, 1, 3, and 6 post-surgery using dynamic planar imaging of 99mTc-MAG3 activity following retro-orbital injection. Time-activity curves (TACs) were produced for individual kidneys and renal function was assessed by 1) the slope of initial 99mTc-MAG3 uptake (SIU), which is related to renal perfusion; 2) peak activity; and 3) the time-to-peak (TTP). The parameters of tubular excretion were not evaluated in this study as 99mTc-MAG3 is not excreted from UUO kidneys.ResultsCompared to sham-operated mice, SIU was remarkably (>60%) reduced in UUO kidneys at day 1 post surgery and the TACs plateaued, indicating that 99mTc-MAG3 is not excreted in these kidneys. The plateau activity in UUO kidneys was relatively low (~40% of sham kidney’s peak activity) as early as day1 post surgery, demonstrating that uptake of 99mTc-MAG3 is rapidly reduced in UUO kidneys. The time to plateau in UUO kidneys exceeded 200 sec, suggesting that 99mTc-MAG3 is slowly up-taken in these kidneys. These changes advanced as the disease progressed. SIU, peak activity and TTPs were minimally changed in contra-lateral kidneys during the study period.ConclusionsOur data demonstrate that renal uptake of 99mTc-MAG3 is remarkably and rapidly reduced in UUO kidneys, while the changes are minimal in contra-lateral kidneys. The parametric analysis of TACs suggested that renal perfusion as well as tubular uptake is reduced in UUO kidneys. This imaging technique should allow non-invasive assessments of UUO renal injury and enable a more rapid interrogation of novel therapeutic agents and protocols.

Imatinib-ULS-lysozyme: A proximal tubular cell-targeted conjugate of imatinib for the treatment of renal diseases

The anticancer drug imatinib is an inhibitor of the platelet-derived growth factor receptor (PDGFR) kinases, which are involved in the pathogenesis of fibrotic diseases. In the current study we investigated the delivery of imatinib to the proximal tubular cells of the kidneys and evaluated the potential antifibrotic effects of imatinib in tubulointerstitial fibrosis.Coupling of imatinib to the low molecular weight protein lysozyme via the platinum (II)-based linker ULS yielded a 0.8:1 drug-carrier conjugate that rapidly accumulated in the proximal tubular cells upon intravenous and intraperitoneal administration. The bioavailability of intraperitoneally administered imatinib-ULS-lysozyme was 100%. Renal imatinib levels persisted for up to 3days after a single injection of imatinib-ULS-lysozyme. Compared with an equal dose imatinib mesylate, imatinib-ULS-lysozyme resulted in a 30- and 15-fold higher renal exposure of imatinib, for intravenous and intraperitoneal administration respectively. Imatinib-ULS-lysozyme could not be detected in the heart, which is the organ at risk for side-effects of prolonged treatment with imatinib.The efficacy of imatinib-ULS-lysozyme in the treatment of tubulointerstitial fibrosis was evaluated in the unilateral ureteral obstruction (UUO) model in mice. Three days UUO resulted in all signs of early fibrosis, i.e. an increased deposition of matrix and production of profibrotic factors. Although a moderately increased activity of PDGFR-β was observed, the profibrotic phenotype could not be inhibited with imatinib mesylate or with imatinib-ULS-lysozyme. Further evaluation of imatinib mesylate and imatinib-ULS-lysozyme is therefore warranted in an animal model of renal disease in which the activation of PDGFR-β is more pronounced.

Cardioprotective effect of calcineurin inhibition in an animal model of renal disease

Chronic kidney disease is directly associated with cardiovascular complications. Heart remodelling, including fibrosis, hypertrophy, and decreased vascularization, is frequently present in renal diseases. Our objective was to investigate the impact of calcineurin inhibitors (CNI) on cardiac remodelling and function in a rat model of renal disease. Male Sprague Dawley rats were divided into six groups: sham-operated rats, 5/6 nephrectomized rats (Nx) treated with vehicle, CNI (cyclosporine A 5.0 or 7.5, or tacrolimus 0.5 mg/kg/day) or hydralazine (20 mg/kg twice a day) for 14 days, starting on the day of surgery. Creatinine clearance was significantly lower and blood pressure significantly higher in Nx rats when compared with controls. Morphological and echocardiographic analyses revealed increased left ventricular hypertrophy and decreased number of capillaries in Nx rats. Treatment with CNI affected neither the renal function nor the blood pressure, but prevented the development of cardiac hypertrophy and improved vascularization. In addition, regional blood volume improved as confirmed by contrast agent-based echocardiography. Hydralazine treatment did not avoid heart remodelling in this model. Gene expression analysis verified a decrease in hypertrophic genes in the heart of CNI-treated rats, while pro-angiogenic and stem cell-related genes were upregulated. Moreover, mobilization of stem/progenitor cells was increased through manipulation of the CD26/SDF-1 system. We conclude from our studies that CNI-treatment significantly prevented cardiac remodelling and improved heart function in Nx rats without affecting renal function and blood pressure. This sheds new light on possible therapeutic strategies for renal patients at high cardiovascular risk.

Statin Pleiotropy Against Renal Injury

Statins may exhibit significant renoprotective effects beyond their lipid-lowering capacity. Herein, the authors review data from human and animal models of renal disease as well as from studies in cultured renal cells with regard to extralipid renoprotective properties of statins. Statins may exert lipid-independent benefits against renal injury in experimental states of chronic or acute renal function impairment. These include diabetic and hypertensive glomerulosclerosis, autoimmune glomerulonephritis, ischemia/reperfusion-induced renal damage, and unilateral ureteral obstructive nephropathy. Also, statins, by reducing the synthesis of mevalonate products, inhibit the activation of Rho and Ras guanosine triphosphatases that may influence various signaling pathways involving renal inflammatory, fibrogenic, proliferative, and cell-death responses. Therefore, statins exert anti-inflammatory actions in renal tissue, prevent renal scarring, and diminish mesangial or other kidney cell-type proliferation while promoting mesangial cell apoptosis. Renal antioxidant effects with consequent endothelial function regulation of renal vasculature following statin treatment may also account for pleiotropic protection against renal injury.

Silencing genes in the kidney: antisense or RNA interference?

Silencing genes in the kidney: antisense or RNA interference?

Animal models of renal disease

Mice have become a favored species to model disease. Many mouse strains have proven relatively resistant to some manipulations that have generated renal disease in other species. Kirchhoff et al. describe a means of producing hypertension, proteinuria, and glomerular sclerosis in a mouse strain.

Gender and human chronic renal disease

Gender affects the incidence, prevalence, and progression of renal disease. In animal models of the disease, female sex appears to modify the course of progression. Hormonal manipulation by male or female castration also changes the course of renal disease progression, suggesting direct effects of sex hormones in influencing the course of these maladies. This review examines the pertinent animal and human studies assessing the role of gender, and strives to shed light on the possible physiologic mechanisms underlying the effect of gender, on renal disease progression. A summary and evaluation of past and recent studies describing the rate of renal disease progression in animal models and humans as it pertains to gender is provided. In addition, studies elucidating the factors involved in the more modest renal progression rate in females are reviewed and conclusions drawn. Relevant English-language publications were identified by searching the PubMed database from January 1990 until November 2007 using the search terms gender, sex, renal disease, and kidney. In polycystic kidney disease, membranous nephropathy, immunoglobulin A nephropathy, and "chronic renal disease of unknown etiology," men progress at a faster rate to end-stage renal failure than do women. In type 1 diabetes mellitus, there is evidence that males are more likely to manifest signs of renal disease, such as proteinuria. The factors involved in this gender disparity may include diet, kidney and glomerular size, differences in glomerular hemodynamics, and the direct effects of sex hormones. In many, but not all, animal models of renal disease, estrogens slow progression rate. Several studies have recently evaluated the effect of selective estrogen receptor modulators on renal function in humans. Further studies assessing the factors involved in the gender disparity in renal disease progression and the effects of hormonal treatments are warranted.

Direct renin inhibitors: the dawn of a new era, or just a variation on a theme?

Numerous studies have demonstrated that the renin-angiotensin-aldosterone system (RAAS) plays animportant role in the progression of chronic kidneydisease (CKD). Angiotensin (Ang) II generates intra-renal haemodynamic and inflammatory changes thatpromote proteinuria, growth of glomerular andtubular cells, inhibition of NO synthesis, stimulationof extracellular matrix synthesis and induction ofchemokines, reactive oxygen species and apoptosis[1]. In addition, in animal models of renal diseases,aldosterone is also involved in endothelial dysfunction,inflammation, proteinuria and fibrosis [2]. In clinicaltrials, treatment with angiotensin-converting enzyme(ACE) inhibitors and Ang II AT1 receptor blockers(ARBs) was proved to slow down the evolution of bothdiabetic and non-diabetic nephropathies and, there-fore, it is currently regarded as the cornerstone of whatwe call ‘nephroprotection’.A controversial issue is whether these agents aresuperior to other antihypertensive drugs in terms ofnephroprotection—in other words, do they possessso-called ‘pleiotropic’ effects? A large meta-analysis [3]suggested that the benefit seen with ACE inhibitorswas related to the blood pressure (BP) decrease alone.The truth, as Sarafidis et al. [4] pointed out in a veryrecent review, is that, indeed, ACE inhibitors exhibit aBP-independent renoprotective effect, but only inpatients with proteinuria and advanced CKD(i.e. stage 3 or 4), and also that the higher the baselineurine protein excretion and its subsequent decrease, themore pronounced the beneficial effect of these drugs islikely to be [4].However, it is not sufficiently appreciated that, dueto the remarkable complexity of the RAAS, neitherACE inhibitors nor ARBs alone can completelysuppress its activity (Figure 1). The main limitationsof these agents in that regard can be summarized asfollows:(i) A substantial proportion of Ang II is generated inthe kidneys from Ang I via non-ACE pathways,such as chymase [5], which are not susceptible tothe actions of ACE inhibitors.(ii) ACE inhibition and ARB, by interrupting nega-tive feedback-loops, result in high plasma (andmost likely tissue-) renin concentrations and highplasma renin activity (PRA), which may over-come the drugs’ effectiveness. The reactivation ofAng II (or ‘Ang II escape’) has been describedwith both ACE inhibitors and ARBs [6]; how-ever, its clinical significance is not yet fullyunderstood.(iii) Renin can also bind to specific receptors in themesangium and in the subendothelium of therenal arteries. This binding leads on one hand, toa substantial increase in the catalytic efficiency ofconversion of angiotensinogen to Ang I, and, onthe other hand, to stimulation of mitogen-activated protein kinases, ERK-1 and ERK-2[7]. In animal models of nephrotic syndrome,treatment with ACE inhibitors was associatedwith a reduction in glomerular injury andproteinuria, but also with tubulo-interstitiallesions [8]. These findings support a directprofibrotic role for renin, independent of itsAng-generating effect.(iv) ACE inhibitors induce an acute decrease inplasma aldosterone. This effect, however, isoften only transient and followed by a progres-sive rise in aldosterone levels that ultimately, withlong-term ACE inhibition, can reach normal oreven elevated concentrations. This ‘aldosterone

Inhibition of CXCL16 Attenuates Inflammatory and Progressive Phases of Anti-Glomerular Basement Membrane Antibody-Associated Glomerulonephritis

Chemokines recruit and activate leukocytes during inflammation. CXCL16 is a recently discovered chemokine that is expressed as a transmembrane protein that is cleaved to form the active, soluble chemokine. We analyzed the role of CXCL16 in the development of inflammation and in the progression of the anti-glomerular basement membrane (GBM) antibody-induced experimental glomerulonephritis in Wistar-Kyoto rats. CXCL16 was expressed in glomerular endothelial cells and mediated adhesion of macrophages expressing CXCL16 and its cognate receptor, CXCR6. Glomerular infiltrates displayed a strong migratory response to soluble CXCL16. Soluble CXCL16 and its receptor CXCR6 were induced in nephritic glomeruli throughout the disease, and CXCL16 expression correlated with the up-regulation of ADAM10, suggesting that this disintegrin and metalloproteinase mediates the chemokine activity of CXCL16. Blocking CXCL16 in the acute inflammatory phase or progressive phase of established glomerulonephritis significantly attenuated monocyte/macrophage infiltration and glomerular injury; proteinuria also improved. We conclude that CXCL16/CXCR6 plays a critical role in stimulating leukocyte influx, which causes glomerular damage during anti-GBM glomerulonephritis. Blocking CXCL16 actions limits the progression of anti-GBM glomerulonephritis even when the disease is established.

Aldosterone antagonists: Silver bullet or just sodium excretion and potassium retention?

ACE inhibitors or AT(1) antagonists are powerful therapeutic strategies to slow the progression of renal disease. However, they provide only imperfect protection since they cannot always prevent end-stage renal failure. Innovative approaches are needed to keep patients with chronic kidney disease off dialysis. Blockade of the aldosterone pathway may prove to be such a beneficial therapeutic concept.

Immunohistochemical Expression of Activated Caspase-3 as a Marker of Apoptosis in Glomeruli of Human Lupus Nephritis

The role of apoptosis in lupus nephritis (LN) is still controversial. One of the key events in the process of apoptosis is activation of caspase-3. Studies of experimental models suggested that activated caspase-3 is a reliable indicator of apoptotic rate, with a favorable comparison against terminal transferase-mediated DNA nick-end labeling (TUNEL) assay. Our aim is to study apoptosis in various forms of LN and its relationship to histomorphological changes and selected laboratory findings by using activated caspase-3 as a novel marker of apoptosis. We investigated glomerular cell apoptosis in 51 biopsy specimens from patients with LN classified according to the International Society of Nephrology/Renal Pathology Society classification by using the TUNEL method and immunohistochemistry against activated caspase-3. In addition, activity and chronicity indices were calculated and anti-Ki-67 antibody was used to estimate proliferative activity. Activated caspase-3-positive cells were present in glomeruli of 88.2% of cases, observed in the glomerular tuft and cellular and fibrocellular crescents. In the glomerular tuft, they were found mainly in segments with active inflammatory lesions. There was good correlation between apoptotic index assessed by using activated caspase-3 immunolabeling and the TUNEL method (r = 0.72; P < 0.01). We observed a significant positive correlation between apoptotic index and LN class (P < 0.001). Apoptotic index correlated significantly with activity index, proliferation index, and daily protein excretion (P < 0.001), but not chronicity index, creatinine concentration, or anti-DNA antibody-binding activity in serum. Apoptotic rate is greater in severe active glomerular lesions in human LN, suggesting that apoptosis may be involved in augmenting inflammation in human LN.

Hepatocyte growth factor suppresses acute renal inflammation by inhibition of endothelial E-selectin

Vascular endothelial activation, marked by de novo expression of E-selectin, is an early and essential event in the process of leukocyte extravasation and inflammation. Evidence suggests that hepatocyte growth factor (HGF) ameliorates inflammation in animal models of renal disease, implying that HGF might inhibit specific components of the inflammatory response. This study examined the effect of HGF on endothelial E-selectin expression in acute inflammation induced by tumor necrosis factor (TNF)-α. In vitro, HGF suppressed TNF-α-induced cell surface expression of E-selectin in human umbilical vein endothelial cells (HUVEC) and inhibited E-selectin mediated monocytic adhesion to endothelial monolayers. HGF activated phosphatidylinositol 3-kinase (PI3K)–Akt that in turn inhibited its downstream transducer glycogen synthase kinase (GSK)3. Blockade of the PI3K–Akt pathway with specific inhibitors abrogated HGF induced inhibitory phosphorylation of GSK3 and suppression of E-selectin. In addition, selective inhibition of GSK3 activity by lithium suppressed TNF-α-induced E-selectin expression and monocytic adhesion, reminiscent of the action of HGF. Moreover, ectopic expression of an uninhibitable mutant GSK3β, in which the regulatory serine-9 is replaced by alanine, abolished HGF's suppressive effect on endothelial E-selectin. In vivo, administration of exogenous HGF reduced endothelial expression of E-selectin induced by bolus injection of TNF-α. This was associated with less sequestration of circulating fluorescence-labeled macrophages in the kidney. These findings suggest that HGF ameliorates acute renal inflammation in part by downregulating E-selectin mediated macrophage adhesion to the inflamed endothelium.