Tubulointerstitial Compartment Research Articles

Interstitial Vascular Rarefaction and Reduced VEGF-A Expression in Human Diabetic Nephropathy

Diabetic nephropathy (DN) is a frequent complication in patients with diabetes. Although the majority of DN models and human studies have focused on glomeruli, tubulointerstitial damage is a major feature of DN and an important predictor of renal dysfunction. This study sought to investigate molecular markers of pathogenic pathways in the renal interstitium of patients with DN. Microdissected tubulointerstitial compartments from biopsies with established DN and control kidneys were subjected to expression profiling. Analysis of candidate genes, potentially involved in DN on the basis of common hypotheses, identified 49 genes with significantly altered expression levels in established DN in comparison with controls. In contrast to some rodent models, the growth factors vascular endothelial growth factor A (VEGF-A) and epidermal growth factor (EGF) showed a decrease in mRNA expression in DN. This was validated on an independent cohort of patients with DN by real-time reverse transcriptase-PCR. Immunohistochemical staining for VEGF-A and EGF also showed a reduced expression in DN. The decrease of renal VEGF-A expression was associated with a reduction in peritubular capillary densities shown by platelet-endothelial cell adhesion molecule-1/CD31 staining. Furthermore, a significant inverse correlation between VEGF-A and proteinuria, as well as EGF and proteinuria, and a positive correlation between VEGF-A and hypoxia-inducible factor-1alpha mRNA was found. Thus, in human DN, a decrease of VEGF-A, rather than the reported increase as described in some rodent models, may contribute to the progressive disease. These findings and the questions about rodent models in DN raise a note of caution regarding the proposal to inhibit VEGF-A to prevent progression of DN.

Glomerular adaptation after kidney transplantation

In renal transplantation, surrogate variables of low nephron endowment are associated with a decreased allograft survival. However, total glomerular number can only be precisely estimated in experimental models or autopsy studies because the whole kidney is necessary for this purpose. The combination of magnetic resonance imaging of the kidney and a renal biopsy allows estimating total glomerular number in vivo, and the application of this approach to stable renal allografts has shown that total glomerular number is a major determinant of graft function. Protocol biopsies performed in stable grafts have allowed the characterization of subclinical rejection (SCR) and chronic allograft nephropathy as well as their predictive value on graft outcome. However, glomerular adaptation after transplantation has not captured the interest of the transplant community despite only one kidney is transplanted and a large proportion of transplant recipients will receive an insufficient nephron number for their metabolic demand. Using protocol biopsies, it has been shown that glomeruli enlarge after transplantation to provide an adequate filtration surface area to the recipient metabolic demand. Glomerular size increases during the first year and this adaptation process is necessary to achieve an adequate renal function. This adaptation is impaired in patients with SCR and/or chronic allograft nephropathy. Furthermore, glomerulosclerosis is also increased in patients with impaired glomerular adaptation. Taken together, these data suggest that the primary target of SCR is the tubulointerstitial compartment leading to interstitial fibrosis/tubular atrophy and to impaired glomerular adaptation/glomerulosclerosis thereafter.

Inhibition of p38 Mitogen-Activated Protein Kinase and Transforming Growth Factor-β1/Smad Signaling Pathways Modulates the Development of Fibrosis in Adriamycin-Induced Nephropathy

Inflammation and fibrogenesis are the two determinants of the progression of renal fibrosis, the common pathway leading to end-stage renal disease. The p38 mitogen-activated protein kinase (MAPK) and transforming growth factor (TGF)-beta1/Smad signaling pathways play critical roles in inflammation and fibrogenesis, respectively. The present study examined the beneficial renoprotective effect of combination therapy using the p38 MAPK pathway inhibitor (SB203580) and a TGF-beta receptor I (ALK5) inhibitor (ALK5I) in a mouse model of adriamycin (ADR) nephrosis. The p38 MAPK and TGF-beta1/Smad2 signaling pathways were activated in ADR-induced nephropathy in a sequential time course manner. Two weeks after ADR injection, the combined administration of SB203580 (1 mg/kg/24 hours) and ALK5I (1 mg/kg/24 hours) markedly reduced p38 MAPK and Smad2 activities. Moreover, the co-administration of SB203580 and ALK5I to ADR-injected mice resulted in a down-regulation of total and active TGF-beta1 production, reduced myofibroblast accumulation, and decreased expression of collagen type IV and fibronectin. In these mice, retardation in the development of glomerulosclerosis and interstitial fibrosis was observed. In conclusion, although p38 MAPK and TGF-beta1/Smad signaling pathways are distinct they coordinate the progression of renal fibrosis in ADR nephrosis. The co-administration of a p38 MAPK inhibitor and an ALK5 inhibitor may have potential applications in the treatment of renal fibrosis.

Modular Activation of Nuclear Factor-κB Transcriptional Programs in Human Diabetic Nephropathy

Diabetic nephropathy (DN) is the leading cause of end-stage renal failure and a major risk factor for cardiovascular mortality in diabetic patients. To evaluate the multiple pathogenetic factors implicated in DN, unbiased mRNA expression screening of tubulointerstitial compartments of human renal biopsies was combined with hypothesis-driven pathway analysis. Expression fingerprints obtained from biopsies with histological diagnosis of DN (n = 13) and from control subjects (pretransplant kidney donors [n = 7] and minimal change disease [n = 4]) allowed us to segregate the biopsies by disease state and stage by the specific expression signatures. Functional categorization showed regulation of genes linked to inflammation in progressive DN. Pathway mapping of nuclear factor-kappaB (NF-kappaB), a master transcriptional switch in inflammation, segregated progressive from mild DN and control subjects by showing upregulation of 54 of 138 known NF-kappaB targets. The promoter regions of regulated NF-kappaB targets were analyzed using ModelInspector, and the NF-kappaB module NFKB_IRFF_01 was found to be specifically enriched in progressive disease. Using this module, the induction of eight NFKB_IRFF_01-dependant genes was correctly predicted in progressive DN (B2M, CCL5/RANTES, CXCL10/IP10, EDN1, HLA-A, HLA-B, IFNB1, and VCAM1). The identification of a specific NF-kappaB promoter module activated in the inflammatory stress response of progressive DN has helped to characterize upstream pathways as potential targets for the treatment of progressive renal diseases such as DN.

Acute sodium overload produces renal tubulointerstitial inflammation in normal rats

The aim of the present study was to determine whether acute sodium overload could trigger an inflammatory reaction in the tubulointerstitial (TI) compartment in normal rats. Four groups of Sprague-Dawley rats received increasing NaCl concentrations by intravenous infusion. Control (C): Na+ 0.15 M; G1: Na+ 0.5 M; G2: Na+ 1.0 M; and G3: Na+ 1.5 M. Creatinine clearance, mean arterial pressure (MAP), renal blood flow (RBF), and sodium fractional excretion were determined. Transforming growth factor beta1 (TGF-beta1), alpha-smooth muscle actin (alpha-SMA), RANTES, transcription factor nuclear factor-kappa B (NF-kappaB), and angiotensin II (ANG II) were evaluated in kidneys by immunohistochemistry. Animals with NaCl overload showed normal glomerular function without MAP and RBF modifications and exhibited a concentration-dependent natriuretic response. Plasmatic sodium increased in G2 (P < 0.01) and G3 (P < 0.001). Light microscopy did not show renal morphological damage. Immunohistochemistry revealed an increased number of ANG II-positive tubular cells in G2 and G3, and positive immunostaining for NF-kappaB only in G3 (P < 0.01). Increased staining of alpha-SMA in the interstitium (P < 0.01), TGF-beta1 in tubular cells (P < 0.01), and a significant percentage (P < 0.01) of positive immunostaining for RANTES in tubular epithelium and in glomerular and peritubular endothelium were detected in G3 > G2 > C group. These results suggest that an acute sodium overload is able 'per se' to initiate TI endothelial inflammatory reaction (glomerular and peritubular) and incipient fibrosis in normal rats, independently of hemodynamic modifications. Furthermore, these findings are consistent with the possibility that activation of NF-kappaB and local ANG II may be involved in the pathway of this inflammatory process.

Adriamycin nephropathy in severe combined immunodeficient (SCID) mice

Experimental focal glomerulosclerosis is a model of chronic proteinuric renal disease that has been induced in both rats and mice. In mice, the adriamycin (ADR)induced nephropathy model is a robust experimental analogue of human focal glomerulosclerosis [1]. Renal injury in the ADR-induced nephropathy model is characterized by changes in both the tubulointerstitial and glomerular compartments. Within the interstitium, there is an increase in interstitial volume, tubular atrophy, collagen deposition and increased numbers of CD4þ T cells, CD8þ T cells and macrophages [1]. In mice with established adriamycin nephropathy, depletion of CD4þ T lymphocytes worsens glomerular and interstitial injury [2] whilst depletion of CD8þ T lymphocytes ameliorates disease [3]. Therefore, lymphocytes play a pivotal role in renal injury in adriamycin nephropathy (AN). The tubulointerstitium also contains other inflammatory cells such as macrophages, dendritic cells and NK cells. Using lymphocyte-deplete animals enables study of the individual contribution of these cell populations to renal injury. SCID (severe combined immunodeficient) mice are homozygous for an autosomal recessive mutation that leads to the absence of lymphocytes and hypogammaglobulinaemia [4], and are found in BALB/c mice. Adriamycin nephropathy can be induced in immunocompetent BALB/c mice [1]. Previous studies in our laboratory have shown that NK cells do not play a significant role in this model [5]. The aim of the present study was to determine if the model of AN could be established in SCID mice. We found that tail-vein injection of adriamycin induces a stable and reproducible model of proteinuric renal disease in lymphocyte-deplete BALB/c mice at half the dose required for immunocompetent BALB/c mice.

Stem Cell Therapy for Glomerular Disease

Stem cell therapy holds great promise for the repair of injured tissues and organs, including the kidney. Although still surrounded by uncertainties, such as the role of specific stem cell or progenitor populations, the relative contribution of local versus circulating cells or the modes of action, recent years have witnessed considerable progress in bringing stem cells closer to the bedside in nephrology. Concerning the kidney, most studies on repair have concentrated on the tubulointerstitial compartment, and less information is available for glomerular repair. In this issue of JASN, Kunter et al. demonstrate that intrarenal administration of bone marrow– derived mesenchymal stem cells (MSC) can be used as cell therapy in the anti-Thy1.1– mediated model of antibody-mediated mesangiolysis and glomerular capillary destruction. Importantly, recovery of the glomerular lesions is accelerated when MSC are instilled locally 2 d after the induction of disease. The study elegantly demonstrates that these beneficial effects are not mediated through replacement of damaged glomerular cells by differentiated MSC but rather are caused by paracrine effects. The authors convincingly show that these actions are specific for MSC and dependent on local delivery. MSC are a rare minority of cells in the bone marrow and are

Renal cell apoptosis and proliferation may be linked to nuclear factor– κB activation and expression of inducible nitric oxide synthase in patients with lupus nephritis

The mechanism of renal cell apoptosis involves transcriptional activation of the inducible nitric oxide synthase (iNOS) gene by nuclear factor (NF)-kappaB. The role of apoptosis in mediating tubulointerstitial injury in human lupus nephritis (LN) remains unclear. We examined the relationship between alterations in NF-kappaB activation and iNOS expression levels and the degree of apoptosis in both glomerular and tubulointerstitial compartments of subjects with LN. Studies were done in renal biopsies from 49 patients with LN and 10 normal kidney tissues. Apoptotic and proliferating cells were identified by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and staining with anti-proliferating cell nuclear antigen antibody, respectively. Nuclear factor-kappaB and iNOS expression was examined by Southwestern histochemistry and immunohistochemistry, respectively. Glomerular cell apoptosis and proliferation increased concomitantly in LN. Glomerular apoptosis correlated with the activity index, the degree of proliferation, and the level of glomerular overexpression of iNOS and activated NF-kappaB in LN. Tubular cell apoptosis correlated with the activity and chronicity indices, the degree of tubular atrophy, and decline in renal function at the time of biopsy. Tubular expression of iNOS and activated NF-kappaB correlated with tubular cell proliferation in LN. Nuclear factor-kappaB activation accompanied overexpression of iNOS in both glomerular and tubulointerstitium compartments in LN. Apoptosis of renal cells associated with NF-kappaB activation and iNOS overexpression may play an important role in mediating chronic renal injury, especially tubulointerstitial lesions that may manifest clinically as progressive renal insufficiency.

Progression of chronic kidney disease: insights from animal models

Chronic kidney diseases are emerging as a worldwide public health problem. Clarification of the mechanisms underlying progression of proteinuric nephropathies received significant input from the generation of transgenic and knockout animals and from novel approaches to block mediators of injury. Reviewed here are advances in animal models used as a tool to address some relevant questions to the pathophysiology of human chronic nephropathies. Gene targeting in rodents identified podocyte loss as central event in the development of glomerulosclerosis. The trigger is dysfunction or absence of podocyte molecules that stabilize the slit diaphragm or anchor foot processes to the basement membrane. Sustained injury of the glomerular barrier to proteins is transmitted to the tubulointerstitial compartment leading to inflammation and fibrosis. Blocking NF-kappaB activity and chemokine signals in the kidney effectively interrupts such process. Growth factors produced by tubular cells and inflammatory cells contribute to interstitial fibrogenesis via myofibroblast activation. Development of genetically engineered animals and techniques to specifically manipulate cellular mediators has highlighted the determinants of glomerulosclerosis and tubulointerstitial injury. This knowledge will provide basis for novel interventions to protect the podocyte in chronic progressive glomerulopathies and to halt renal scarring and loss of function.

Glomerular and Tubular Basement Membrane Calcinosis: Case Report and Literature Review

Nephrocalcinosis most commonly manifests as renal calculi or deposition within the tubulointerstitial compartment. Conversely, calcium deposition within glomeruli is extremely rare. We present the case of a 50-year-old man with multiple medical problems, including hepatitis C, diabetes, hypertension, proteinuria, and chronic renal failure. Renal biopsy showed impressive calcium deposits along glomerular basement membranes and tubular basement membranes, within intracellular organelles, and in the interstitium in the setting of a normal serum calcium level. Seven months after biopsy, the patient is on hemodialysis therapy. Although serological and medical examination failed to show a treatable cause for this patient's glomerular calcinosis, individual case reports in the literature have described resolution of calcinosis-associated nephrotic syndrome with treatment of the primary cause of hypercalcemia.

Modulation of renal kallikrein by a high potassium diet in rats with intense proteinuria

Injury of the renal tubulointerstitial compartment is recognized to play an important role in hypertension. Its damage may in turn, impair the activity of vasodepressor systems, like the kallikrein-kinin, in blood pressure regulation. The overload proteinuria model induces tubulointerstitial injury with activation of the renin-angiotensin system, but renal kallikrein and the development of hypertension have not received special attention. Sprague-Dawley rats received seven intraperitoneal doses of bovine serum albumin (BSA) 2 g/day under normosodic diet and were hydrated ad libitum. A second group received a high potassium diet to stimulate kallikrein production during the previous four weeks and while under BSA administration. A third one received potassium and BSA in the same schedule, but with the kinin B2 receptor antagonist, HOE140, added during the protein load phase. A control group received seven saline injections. Kallikrein protein was detected by immune labeling on renal sections and enzymatic activity in the urine. The BSA group showed massive proteinuria followed by intense tubulointerstitial damage. Blood pressure increased after the third dose in BSA animals, remaining elevated throughout the experiment, associated with significant reductions in renal expression and urinary activity of kallikrein, compared with controls. An inverse correlation was found between blood pressure and immunohistochemistry and urinary activity of kallikrein. Potassium induced a significant increase in both urinary activity and renal kallikrein expression, associated with significant reduction in blood pressure. The HOE140 antagonist blunted the antihypertensive effect of kallikrein stimulation in proteinuric rats. Loss of renal kallikrein, produced by tubulointerstitial injury, may participate in the pathogenesis of the hypertension observed in this model.

Compartment-Specific Expression and Function of the Chemokine IP-10/CXCL10 in a Model of Renal Endothelial Microvascular Injury

The recruitment of inflammatory cells into renal tissue, mainly T cells and monocytes, is a typical feature of various renal diseases such as glomerulonephritis, thrombotic angiopathies, allograft rejection, and vasculitis. T cells predominantly infiltrate the tubulointerstitium, whereas monocytes are present in the tubulointerstitial and glomerular compartment. Because chemokines play a pivotal role in leukocyte trafficking under inflammatory conditions, this study investigated whether a differential expression of chemokines contributes to the precise coordination of leukocyte subtype trafficking in a rat model of renal microvascular endothelial injury. Renal microvascular endothelial injury was induced in rats by selective renal artery perfusion with an anti-endothelial antibody. Induction of the disease led to severe glomerular and tubulointerstitial endothelial injury with subsequent upregulation of chemokines followed by inflammatory cell recruitment. Among the analyzed chemokine mRNA, IP-10/CXCL10 (119-fold), acting via CXCR3 on activated T cells, and MCP-1/CCL2 (65-fold), acting via CCR2 on monocytes, were by far the most strongly upregulated chemokines. In situ hybridization revealed that IP-10/CXCL10 mRNA was selectively expressed by endothelial cells in the tubulointerstitial area, co-localizing with infiltrating T cells. Despite extensive damage of glomerular vasculature, no IP-10/CXCL10 expression by glomerular endothelial cells was detected. MCP-1/CCL2 mRNA in contrast was detectable in the glomerulus and the tubulointerstitium. Treatment with a neutralizing anti-IP-10/CXCL10 antibody significantly reduced the number of infiltrating tubulointerstitial T cells without affecting monocyte migration and led to an improved renal function. Our study demonstrates a role of IP-10/CXCL10 on T cell recruitment in a rat model of renal endothelial microvascular injury. Furthermore, a differential chemokine expression profile by endothelial cells in different renal compartments was found. These findings are consistent with the hypothesis that functional heterogeneity of endothelial cells from different vascular sites exists and provide an insight into the molecular mechanisms that may mediate compartment-specific T cell and monocyte recruitment in inflammatory renal disease.

Association between endothelin-1 and collagen deposition in db/ db diabetic mouse kidneys

Endothelin-1 has been implicated in diabetic kidney injury, but there are few firm data establishing the temporal and spatial expression of kidney endothelin-1 in diabetes. We performed an immunohistochemical and histopathological analysis to determine endothelin-1 peptide expression in the kidneys of diabetic db/ db mice and non-diabetic db/ m controls. Diabetic mice were studied at 8 weeks, before histological damage is evident, and again at 16 weeks, when significant glomerular injury has occurred. Urinary endothelin-1 was 6.2- and 3.6-fold higher in 8- and 16-week diabetic mice compared to age-matched controls ( P < 0.01 db/ db vs. db/ m). Compared to non-diabetic kidneys, immunoreactive endothelin-1 was first elevated 2.5-fold ( P = 0.02) in the tubulointerstitial compartment at 8-week and remained high (3.8-fold, P < 0.01) at 16 weeks. In contrast, glomerular endothelin-1 was elevated 3.2-fold ( P = 0.03) only in 16-week diabetic mice. Glomerular and tubulointerstitial endothelin-1 were unchanged in 8- and 16-week non-diabetic mice. Elevated endothelin-1 in diabetic mice associated temporally and spatially with collagen deposition, especially in the tubulointerstitial compartment. The localization of kidney endothelin-1 is consistent with a role for this peptide in renal fibrogenesis. These results also highlight the potential role of ET-1 in the pathogenesis of early tubulointerstitial changes in diabetes.

Chemokine Receptor Ccr2 Deficiency Reduces Renal Disease and Prolongs Survival in MRL/lpr Lupus-Prone Mice

MRL/MpJ-Fas(lpr)/J (MRL/lpr) mice represent a well-established mouse model of human systemic lupus erythematosus. MRL/lpr mice homozygous for the spontaneous lymphoproliferation mutation (lpr) are characterized by systemic autoimmunity, massive lymphadenopathy associated with proliferation of aberrant T cells, splenomegaly, hypergammaglobulinemia, arthritis, and fatal immune complex-mediated glomerulonephritis. It was reported previously that steady-state mRNA levels for the chemokine (C-C motif) receptor 2 (Ccr2) continuously increase in kidneys of MRL/lpr mice. For examining the role of Ccr2 for development and progression of immune complex-mediated glomerulonephritis, Ccr2-deficient mice were generated and backcrossed onto the MRL/lpr genetic background. Ccr2-deficient MRL/lpr mice developed less lymphadenopathy, had less proteinuria, had reduced lesion scores, and had less infiltration by T cells and macrophages in the glomerular and tubulointerstitial compartment. Ccr2-deficient MRL/lpr mice survived significantly longer than MRL/lpr wild-type mice despite similar levels of circulating immunoglobulins and comparable immune complex depositions in the glomeruli of both groups. Anti-dsDNA antibody levels, however, were reduced in the absence of Ccr2. The frequency of CD8+ T cells in peripheral blood was significantly lower in Ccr2-deficient MRL/lpr mice. Thus Ccr2 deficiency influenced not only monocyte/macrophage and T cell infiltration in the kidney but also the systemic T cell response in MRL/lpr mice. These data suggest an important role for Ccr2 both in the general development of autoimmunity and in the renal involvement of the lupus-like disease. These results identify Ccr2 as an additional possible target for the treatment of lupus nephritis.

NF-kappaB regulates Fas-mediated apoptosis in HIV-associated nephropathy.

Renal parenchymal injury in HIV-associated nephropathy (HIVAN) is characterized by epithelial proliferation, dedifferentiation, and apoptosis along the entire length of the nephron. Although apoptotic cell death in HIVAN has been well documented, the mechanism for HIV-induced apoptosis is poorly understood. Whether the epithelial apoptosis in HIVAN is mediated by NF-kappaB-activated Fas ligand expression was investigated here. In human HIVAN and HIV-1 transgenic mouse kidney specimens, the expression of Fas receptor and ligand proteins were markedly upregulated on epithelium in diseased glomerular and tubulointerstitial compartments when compared with normal. Podocyte cell lines that were derived from HIV-1 transgenic mice showed a similar upregulation of Fas receptor expression and de novo expression of Fas ligand by semiquantitative reverse transcription-PCR and Western blotting. In cultured podocytes, cross-linking of the Fas receptor to mimic ligand binding induced caspase 8 activity and apoptosis in both normal and HIVAN podocytes. Because constitutive NF-kappaB activity has been demonstrated in HIVAN epithelia, evidence for transcriptional control of the Fas ligand expression by NF-kappaB was sought. With the use of cultured podocytes, expression of a Fas ligand promoter reporter plasmid was higher in HIVAN podocytes, indicating increased transcriptional activity. In addition, chromatin immunoprecipitation assays were performed to demonstrate that p65-containing (RelA) complexes bound the Fas ligand promoter and that suppression of activated NF-kappaB with a peptide inhibitor could reduce the expression of Fas ligand mRNA in HIVAN podocytes. These results suggest that NF-kappaB may regulate Fas-mediated apoptosis in HIVAN by controlling the expression of Fas ligand in renal epithelium.

Apoptosis and proliferation in childhood acute proliferative glomerulonephritis

Acute proliferative glomerulonephritis is characterized by glomerular hypercellularity that can be caused by many different etiologies and pathogenetic mechanisms. A balance between cell birth by mitosis and cell death by apoptosis is crucial. In this study, apoptosis and the regenerative activity (Ki67/apoptosis index) were investigated in acute proliferative glomerulonephritis. Thirty-five children with biopsy-proven acute proliferative glomerulonephritis and five controls with MCD were studied retrospectively. According to the clinical outcome, patients were divided into 2 groups: group 1 (n =21) were patients with normal renal functions at follow-up; group 2 (n =8) were patients with end-stage renal failure or those who died. Immunohistochemical staining of proliferating cells (Ki67) was done. In situ end labeling of DNA was used to evaluate apoptosis. Glomerular cell apoptosis was 45% in the patients with acute proliferative glomerulonephritis and 3% in controls ( p <0.001). Apoptotic cells were identified in the tubulointerstitial compartment with higher and heavier immunostaining in patients than controls (p =0.001). Tubular proliferative index (= tubular proliferation/tubular apoptosis ratio) was significantly higher in group 1 patients than in group 2 patients (2.03+/-2% versus 0.32+/-0.6%, p =0.002). Tubulointerstitial regenerative ratio (=tubular proliferation/interstitial proliferation ratio) was significantly higher in controls than in patients (3.4+/-1.9 versus 1.52+/-0.8, p =0.01). In addition, it was significantly increased in group 1 patients when compared with those in group 2 patients (1.89+/-0.8 versus 0.73+/-0.2, p =0.001). Since 17 patients presented with postinfectious proliferative glomerulonephritis, which is known to exhibit better course, we also evaluated those parameters in patients with postinfectious proliferative glomerulonephritis separately. We found statistically significant differences only in the tubulointerstitial regenerative ratio, which was higher in postinfectious cases when compared with those in other cases [1.60 interquartile range (IQR) 1.54 versus 1.22 IQR 1.26, respectively, p =0.003]. In conclusion, tubular proliferative index and tubulointerstitial regenerative ratio might be useful parameters for predicting final functional outcome in acute proliferative glomerulonephritis. Further studies, however, are still needed to clarify the importance of these histopathological parameters.

α‐SM Actin Expression as Prognostic Indicator in IgA Nephropathy (Berger’s Disease)

Recent studies have demonstrated that α-Smooth Muscle actin expression in glomerular and tubulointerstitial compartments of renal tissue could represent a prognostic marker in several renal diseases. Our objective was to identify the prognostic value of α-SM actin actin expression on the evolution of renal damage in Primary IgA nephropathy (Berger’s Disease). 43 patients followed up from 1988 to 1999 at the University Hospital, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Brazil, was studied. Clinical-laboratory data were obtained from the medical records of the patients using a protocol containing name, race, gender, origin, profession, age at clinical presentation of the disease and personal and family history. The parameters assessed in the approach to IgA nephropathy were serum creatinine, creatinine clearance, serum albumin, total serum protein, 24 hours proteinuria, glycaemia, serum sodium, potassium, calcium and phosphorus ions, analysis of urinary sediment, serum complement profile, blood count, and renal biopsy. Morphological evaluation was performed by renal biopsy using common light and immunofluorescence microscopy. Immunohistochemical studies were performed using a murine monoclonal antibody to α-SM actin. Our data showed that α-SM actin expression in the glomerular and tubulointerstitial compartments are not correlated with unfavorable clinical course of primary IgA nephropathy.

Alterations in Gene Expression in Cadaveric vs. Live Donor Kidneys Suggest Impaired Tubular Counterbalance of Oxidative Stress at Implantation

Recipients of live donor transplant kidneys (LIV) exhibit a significantly longer allograft half-life compared with cadaveric donor organs (CADs). The reasons are incompletely understood. Therefore this study sought to elucidate the genome-wide gene expression profiles in microdissected transplant kidney biopsies obtained from five cadaveric and five matched live donors before transplantation. cDNA microarrays were used to determine the transcripts in isolated glomeruli (G) and the tubulointerstitial (TI) compartment. Data were subjected to hierarchical clustering, maxT adjustment and a jackknife procedure to ensure robustness of reported findings; validation was performed by independent analysis of split biopsies and TaqMan-PCR.One hundred and thirteen sequences representing 62 unique genes (17 redundant features), and 34 ESTs separated G from TI. No difference in gene expression was found in G between LIV and CAD kidneys, but nine genes (two represented twice) and three ESTs were abundantly expressed in the CAD TI compared with LIV. The main biological function of these genes is counter regulation of oxidative stress. Promoter analysis of significant features suggested coregulated gene groups.These data suggest that CAD kidneys exhibit a distinctly different set of transcripts in the TI compartment but not in the G compartment when compared with LIV kidneys.

Selective lymphocyte inhibition by FTY720 slows the progressive course of chronic anti-thy 1 glomerulosclerosis

Progression is a hallmark of chronic renal disease and histologically characterized by fibrosis and inflammation of the tubulointerstitial compartment. To define the role of lymphocytes in this process, the novel lymphocyte-specific inhibitor FTY720 was administered to rats with anti-thy 1-induced chronic progressive glomerulosclerosis. In this model, the initial and short-term inflammatory glomerular injury progresses self-perpetuatedly toward tubulointerstitial fibrosis by not primarily immune-mediated, intrarenal mechanisms. Chronic progressive glomerulosclerosis was induced by murine anti-thy 1 antibody injection into uninephrectomized rats. Treatment with FTY720 (0.3 mg/kg body weight) was started 7 days after disease induction. Proteinuria was measured every 4 weeks. In week 20, the following parameters were determined: blood lymphocyte number, kidney function, both glomerular and tubulointerstitial histologic matrix accumulation, protein expression of transforming growth factor-beta1 (TGF-beta1), fibronectin, and plasminogen activator inhibitor-1 (PAI-1) as well as infiltration with macrophages and lymphocytes. Treatment with FTY720 lowered blood lymphocyte count and renal lymphocyte infiltration highly significantly. In comparison to the untreated chronic progressive glomerulosclerosis animals, the lymphocyte depletion achieved significantly limited the progression of the disease, as shown by lowered proteinuria, tubulointerstitial matrix expansion, and TGF-beta1, fibronectin, and PAI-1 expression, as well as improved renal function. Glomerular matrix protein expression and accumulation was moderately lowered by FTY720. Glomerular macrophage infiltration was not, tubulointerstitial macrophage infiltration was moderately, but not significantly, decreased by FTY720 treatment. Lymphocyte depletion by FTY720 limits the progression of anti-thy 1-induced glomerulosclerosis toward chronic tubulointerstitial fibrosis and renal insufficiency. The data suggest that lymphocytes actively participate in the progression of chronic experimental kidney disease, and that FTY720 may be a novel approach to slow the progressive course of human chronic renal diseases.

Palliative Care: More than Just Care from a Friendly Relative

### Background: In patients with lupus nephritis (LN), clinical response to treatment and renal histopathology have been shown to be discordant. No clinical or laboratory markers have to date been shown to reliably portend renal prognosis, in particular renal function impairment. ### Objectives: To investigate whether per-protocol repeat renal biopsies are predictive of LN relapses and long-term impairment of renal function. ### Methods: Forty-two patients with an incident biopsy-proven active proliferative (class III/IV ± V) LN from the LN database of the Université catholique de Louvain were included in the present retrospective study. Per-protocol repeat kidney biopsies were performed in all patients after a median time of 24.3 (IQR: 21.3--26.2) months. The NIH activity index (AI) and chronicity index (CI) scores were assessed in both baseline and repeat biopsies. We defined acute glomerular lesions as cellular proliferation, fibrinoid necrosis or karyorrhexis, cellular crescents, hyaline thrombi or wire loops, and leucocyte infiltration, and chronic glomerular lesions as glomerular sclerosis and fibrous crescents, in alignment with the NIH activity and chronicity indices. Similarly, we defined acute tubulointerstitial lesions as mononuclear cell infiltration and chronic tubulointerstitial lesions as interstitial fibrosis and tubular atrophy. ### Results: Despite a moderate correlation between urinary protein/creatinine (U-P/C) ratios and AI scores at repeat biopsy (r=0.48; P=0.001), ten patients (23.8%) with U-P/C ratios \<1.0 g/g still had a high degree of histological activity (AI score \>3). High AI scores in repeat (but not baseline) kidney biopsies were associated with an increased probability and/or shorter time to renal relapse (N=11) following the repeat biopsy (HR: 1.2; 95% CI: 1.1--1.3; P=0.007), independently of proteinuria levels. This association remained significant for the NIH activity index items within the glomerular but not the tubulointerstitial compartment of the kidney biopsies. High NIH CI scores in repeat (but not baseline) kidney biopsies were associated with a sustained increase in serum creatinine levels corresponding to ≥120% of the baseline value (HR: 1.8; 95% CI: 1.1--2.9; P=0.016) through a median follow-up time of 131.5 (IQR: 73.8--178.2) months, being the case also for acute and chronic tubulointerstitial lesions in repeat but not baseline kidney biopsies. ### Conclusion: Our results highlight the usefulness of per-protocol repeat biopsies as an integral part of the treatment evaluation, also in patients who have shown adequate clinical response. Glomerular lesions consistent with active renal disease portend LN relapses, while tubulointerstitial lesions consistent with active disease and chronic damage portent long-term renal function impairment. ### Disclosure of Interests: Ioannis Parodis: None declared, Christina Adamichou: None declared, Selda Aydin: None declared, Alvaro Gomez: None declared, Nathalie Demoulin: None declared, Julia Weinmann-Menke: None declared, Frederic Houssiau Grant/research support from: UCB, Consultant of: GSK, Farah Tamirou: None declared