Computerized image analysis of Sirius Red-stained renal allograft biopsies as a surrogate marker to predict long-term allograft function

Early urinary CCL2 is associated with the later development of interstitial fibrosis and tubular atrophy in renal allografts

BACKGROUND

Chronic renal allograft injury resulting in progressive interstitial fibrosis and tubular atrophy (IFTA) is a leading cause of graft loss. The goal of this study was to identify early urinary predictors for the subsequent development of IFTA in a prospective cohort of patients (n=111) who underwent serial protocol biopsies at 0, 6, and 24 months.

METHODS

The urinary proteins evaluated were CCL2, CXCL9, CXCL10, and alpha1-microglobulin (alpha1M) using ELISA and immunonephelometry.

RESULTS

We first evaluated urines obtained at 1 to 3 months and found that alpha1M and CXCL10 were associated with IFTA at 6 months but not at 24 months. Next, we evaluated urines at 6 months and found that CCL2 was associated with both IFTA and graft dysfunction at 24 months. On univariate analysis, 6-month urinary CCL2 was a risk factor for developing 24-month IFTA, defined as ci+ct score more than 0 (odds ratio 1.045, 95% confidence interval: 1.005-1.084, P=0.028). Furthermore, CCL2 remained an independent predictor of IFTA on multivariate analysis (odds ratio 1.049, 95% confidence interval: 1.006-1.094, P=0.024) when adjusted for donor age, delayed graft function, deceased donation, and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker exposure. In comparison, alpha1M, CXCL9, and CXCL10 were not associated with late graft outcomes.

CONCLUSION

This study demonstrates that early urinary CCL2 is an independent predictor for the subsequent development of IFTA at 24 months.

FVB mouse genotype confers susceptibility to OVE26 diabetic albuminuria

OVE26 (OVE) diabetic mice on the inbred strain FVB are a valuable model of diabetic nephropathy that excretes the highest amount of urine albumin of all diabetic mouse models. Crossing of OVE mice to C57BL6 or DBA2 mice reduced albuminuria 17-fold in F1 diabetic offspring without reducing diabetes. When comparing renal histology of OVE mice on the FVB background to F1 C57BL6 crosses, we found that the F1 kidneys had significantly smaller glomeruli, much less albumin accumulation in tubules, reduced mesangial matrix expansion, and less interstitial fibrosis. A genome scan of 108 OVE-positive N2 offspring for albuminuria revealed one significant peak on chromosome 11 and nearly significant peaks on chromosomes 9, 13, and 19. Homozygosity for the FVB genotype for peaks on chromosomes 11, 13, or 19 increased albuminuria. Homozygosity for the chromosome 9 peak reduced albuminuria. Combined homozyogosity for the peaks on chromosomes 11, 13, and 19 increased albuminuria over 12-fold and accounted for >70% of the difference between OVE mice on the FVB vs. the F1 background. These loci contain sequences important to susceptibility to diabetic albuminuria.

Anti-thrombin therapy during warm ischemia and cold preservation prevents chronic kidney graft fibrosis in a DCD model

Ischemia reperfusion injury (IRI) is pivotal for renal fibrosis development via peritubular capillaries injury. Coagulation represents a key mechanism involved in this process. Melagatran (M), a thrombin inhibitor, was evaluated in an autotransplanted kidney model, using Large White pigs. To mimic deceased after cardiac death donor conditions, kidneys underwent warm ischemia (WI) for 60 min before cold preservation for 24 h in University of Wisconsin solution. Treatment with M before WI and/or in the preservation solution drastically improved survival at 3 months, reduced renal dysfunction related to a critical reduction in interstitial fibrosis, measured by Sirius Red staining. Tissue analysis revealed reduced expression of transforming growth factor-beta (TGF-beta) and activation level of its effectors phospho-Smad3, Smad4 and connective tissue growth factor (CTGF) after M treatment. Fibrinolysis activation was also observed, evidenced by downregulation of PAI-1 protein and gene expression. In addition, M reduced S100A4 expression and vimentin staining, which are markers for epithelial mesenchymal transition, a major pathway to chronic kidney fibrosis. Finally, expression of oxidative stress markers Nox2 and iNOS was reduced. We conclude that inhibition of thrombin is an effective therapy against IRI that reduces chronic graft fibrosis, with a significantly positive effect on survival.

Functional and morphologic evaluation of kidney proximal tubuli and correlation with renal allograft prognosis

Renal transplant patients with stable graft function and proximal tubular dysfunction (PTD) have an increased risk for chronic allograft nephropathy (CAN). In this study, we investigated the histologic pattern associated with PTD and its correlation with graft outcome. Forty-nine transplant patients with stable graft function were submitted to a biopsy. Simultaneously, urinary retinol-binding protein (uRBP) was measured and creatinine clearance was also determined. Banff's score and semi-quantitative histologic analyses were performed to assess tubulointerstitial alterations. Patients were followed for 24.0 + or - 7.8 months. At biopsy time, mean serum creatinine was 1.43 + or - 0.33 mg/dl. Twelve patients (24.5%) had uRBP > or = 1 mg/l, indicating PTD and 67% of biopsies had some degree of tubulointerstitial injury. At the end of the study period, 18 (36.7%) patients had lost renal function. uRBP levels were not associated with morphologic findings of interstitial fibrosis and tubular atrophy (IF/TA), interstitial fibrosis measured by Sirius red or tubulointerstitial damage. However, in multivariate analysis, the only variable associated with the loss of renal function was uRBP level > or = 1 mg/l, determining a risk of 5.290 of loss of renal function (P = 0.003). Renal transplant patients who present PTD have functional alteration, which is not associated with morphologic alteration. This functional alteration is associated to progressive decrease in renal function.

Interstitial fibrosis quantification in renal transplant recipients randomized to continue cyclosporine or convert to sirolimus

Conversion from cyclosporine (CsA) to sirolimus at week 12 after kidney transplantation is associated with a significant improvement in renal function. The aim of this analysis was to investigate the effect of this conversion on interstitial fibrosis (IF), a hallmark of chronic allograft injury, in patients taking part in the CONCEPT trial. This multicenter, prospective, trial included 193 renal recipients randomized at week 12 to switch from CsA to sirolimus or to continue CsA, with mycophenolate mofetil. Routine biopsy with automated, quantified assessment of IF by a program of color segmentation was performed at 1 year in 121 patients. At 1 year, renal function was significantly improved in the conversion group as assessed by estimated GFR (MDRD) and measured GFR. Biopsy results, however, showed no between-group difference in percentage of IF. Calculated GFR at 1 year was significantly associated with the percentage of IF (p = 0.004, R(2)= 0.07). By multivariate analysis diabetic patients had more fibrosis than non-diabetic patients. In conclusion, although kidney transplant patients converted from CsA to sirolimus showed significant improvement in renal function, we found no difference of IF on 1-year biopsies.

Collagenofibrotic glomerulopathy: three case reports in Brazil

Background

We are reporting the first Collagenofibrotic Glomerulopathy (CG) in South America. So, this collagen type III glomerulopathy is not limited to Japan but may be found throughout the world.

Case Reports

We describe three patients that presented some factors in common, such as sex, age and the presence of non-nephrotic proteinuria associated with microscopic hematuria. The findings with the immunofluorescence microscopy, of immunoglobulins, and components of the complement were usually negative. The picrosyrius staining showed the presence of reddish material in the mesangium, when it was seen under standard microscopy; however, when it was seen with birefringence, it became greenish under polarized light, showed the collagen found in this area of the glomerulus. The identification of CG was made through electronic microscopic scanning, and curved and disorganized fibers were found.

Conclusion

These cases are the first from South America to be reported, and they are about an idiopathic renal disease that is not related to any specific races or locations. The reports contribute to a better understanding of this disease, which although not so prevalent, should be considered as an importantly differential diagnostic of cases of proteinuria.

Post-transplant monitoring of renal allografts: are we there yet?

Transplantation has emerged as the therapy of choice for many patients with end organ failure. One of the major goals is to tailor immunosuppressive therapy to the individual needs of every patient to balance the risk for rejection and over-immunosuppression. This will require diagnostic tools that can detect harmful processes in the allograft early, and that can be measured repeatedly. This review will consider recent advances in our understanding of the molecular nature of these processes and how this information is being utilized to design novel diagnostic assays to non-invasively monitor allografts. Highlighted is the need for large-scale prospective multi-centre studies to validate assays that show early promise in single centre studies.

Prognostic value of computerized quantification of liver fibrosis in children with biliary atresia

Biliary atresia (BA) is the leading indication for liver transplantation (LTx) during childhood. Predictive markers for progression are lacking. We investigated the correlation between quantified fibrosis of the liver at the time of Kasai hepatic portoenterostomy (KPE) and the clinical course. Liver tissue was obtained at the time of KPE in 53 children and stained with Picrosirius red. The mean volume of fibrosis per number of periportal fields (Vfib) and the Ishak score were calculated. Vfib was 3.9%. Transplant-free survival was significantly higher in those patients with Vfib < 2.5% (P < 0.05, Kaplan-Meier analysis). Vfib < 2.5% predicted transplant-free survival with a sensitivity of 100% and a specificity of 48% (positive predictive value: 100%, negative predictive value: 17%). Vfib was correlated with bilirubin 6 months after KPE (Bili6m). The negative predictive value could be enhanced to 23% if Vfib < 2.5% was combined with Bili6m < 20 micromol/L. The Ishak score showed no correlation with transplant-free survival or Vfib. Detection of Vfib at the time of KPE is a valid marker in predicting transplant-free survival in children with BA. This method should be considered an integral part of scoring systems predicting the indication for LTx. Liver Transpl 15:876-882, 2009. (c) 2009 AASLD.

Influence of nephron mass and a phosphorylated 38 mitogen-activated protein kinase inhibitor on the development of early and long-term injury after renal warm ischaemia

BACKGROUND

Renal ischaemia is accompanied by acute and chronic complications. Tumour necrosis factor (TNF) alpha production via p38 mitogen-activated protein kinase (MAPK) is one of the pivotal mechanisms linking ischaemia to inflammation and could be a therapeutic target. FR167653 (FR), an inhibitor of p38 MAPK and TNF-alpha production, may ameliorate renal damage through its effects on TNF-alpha.

METHODS

Warm ischaemia (WI) was induced in male pigs by bilateral clamping of the renal pedicle for 60 min or unilateral renal clamping after contralateral nephrectomy. FR was administered before and during WI, and continuously for 3 h during reperfusion in pigs exposed to the same WI conditions. Experimental groups were compared with sham-operated pigs and those subjected to unilateral nephrectomy without renal ischaemia. Renal function, fibrosis and inflammation were evaluated, and expression of monocyte chemoattractant protein 1, transforming growth factor beta and TNF-alpha was determined after 12 weeks.

RESULTS

FR significantly reduced renal failure in groups subjected to unilateral nephrectomy and bilateral renal ischaemia. Proteinuria was significantly reduced, and inflammation and expression of proinjury proteins were diminished, accompanied by a reduction in renal fibrosis.

CONCLUSION

Control of TNF-alpha production and activity prevents renal damage after prolonged WI.

Calcineurin inhibitor nephrotoxicity

The use of the calcineurin inhibitors cyclosporine and tacrolimus led to major advances in the field of transplantation, with excellent short-term outcome. However, the chronic nephrotoxicity of these drugs is the Achilles' heel of current immunosuppressive regimens. In this review, the authors summarize the clinical features and histologic appearance of both acute and chronic calcineurin inhibitor nephrotoxicity in renal and nonrenal transplantation, together with the pitfalls in its diagnosis. The authors also review the available literature on the physiologic and molecular mechanisms underlying acute and chronic calcineurin inhibitor nephrotoxicity, and demonstrate that its development is related to both reversible alterations and irreversible damage to all compartments of the kidneys, including glomeruli, arterioles, and tubulo-interstitium. The main question--whether nephrotoxicity is secondary to the actions of cyclosporine and tacrolimus on the calcineurin-NFAT pathway--remains largely unanswered. The authors critically review the current evidence relating systemic blood levels of cyclosporine and tacrolimus to calcineurin inhibitor nephrotoxicity, and summarize the data suggesting that local exposure to cyclosporine or tacrolimus could be more important than systemic exposure. Finally, other local susceptibility factors for calcineurin inhibitor nephrotoxicity are reviewed, including variability in P-glycoprotein and CYP3A4/5 expression or activity, older kidney age, salt depletion, the use of nonsteroidal anti-inflammatory drugs, and genetic polymorphisms in genes like TGF-beta and ACE. Better insight into the mechanisms underlying calcineurin inhibitor nephrotoxicity might pave the way toward more targeted therapy or prevention of calcineurin inhibitor nephrotoxicity.

FR167653 improves renal recovery and decreases inflammation and fibrosis after renal ischemia reperfusion injury

OBJECTIVE

Acute tubular necrosis (ATN) secondary to induced warm ischemia (WI) results in inflammatory and delayed fibrotic processes and remains a common clinical problem with serious consequences. Because tumor necrosis factor-alpha (TNF-alpha) is a prominent proinflammatory factor implicated in the pathophysiology of acute renal ischemia reperfusion injury (IRI), we hypothesized that FR167653 (FR), a potent inhibitor of TNF-alpha and interleukin-1beta production, may reduce IRI.

METHODS

IRI was induced in male pigs by bilateral clamping of the renal pedicle for 90 minutes (WI90), or unilateral renal clamping (90 minutes) after contralateral nephrectomy (1/2Nx90), or unilateral renal clamping without contralateral nephrectomy (WIuni90). FR was administered intravenously 60 minutes before WI (1 mg/kg/h), during WI, and continuously for 3 hours (1 mg/kg/h) during reperfusion in treated groups (FRWI90, FR1/2Nx90, or FRWIuni90). Blood and urine samples were collected between day 1 and 3 months after reperfusion for assessment of renal function. Kidneys were excised and renal tissues were collected at 3 months for morphologic and inflammation evaluation and protein analysis. Experimental groups were compared with sham operated (control) and heminephrectomized (Unif) groups without renal ischemia.

RESULTS

Three WI90 animals (43%) and five 1/2Nx90 (70%) were euthanized and necropsied at day 7 because of no urine production or poor conditions. Mortality was significantly improved after FR treatment. Survival was 100% in the control, Unif, WIuni90, and FR groups. In Unif groups, FR significantly reduced renal failure and bilateral renal ischemia (P < .05). At 3 months, proteinuria was significantly reduced in FR-treated groups (P < .01). Inflammatory cells count was also dramatically diminished in FR-treated pigs (P < .01 for CD3-positive cells). The second aspect of transient ischemia is the fibrotic process determined at 3 months. FR treatment was characterized by a reduction of renal fibrosis, particularly in Unif groups. TNF-alpha protein expression was diminished in FR-treated groups.

CONCLUSION

This is the first evidence that FR reduced the early and long-term effect of WI in the severe ischemia model. This effect was particularly marked against fibrosis and inflammation, which would contribute to deterioration of a patient's renal function.

C3a receptor deficiency accelerates the onset of renal injury in the MRL/lpr mouse

The development and progression of systemic lupus erythematosus (SLE) is strongly associated with complement activation and deposition. The anaphylatoxin C3a is a product of complement activation with immunomodulatory properties, and the receptor for C3a (C3aR) is not only expressed by granulocytes and antigen presenting cell populations, but it is also strongly up-regulated in lupus prone mice with active nephritis. In order to characterize the role of the C3aR in inflammatory nephritis, we bred C3aR knock out mice onto the MRL/lpr genetic background (C3aR KO MRL). Compared to control MRL/lpr mice, C3aR KO MRL mice had elevated auto-antibody titers and an earlier onset of renal injury. At 8 weeks, renal expression of a wide range of chemokines and chemokine receptors was increased in C3aR KO MRL kidneys compared to controls. Only the expression of MCP-1 was significantly decreased in the C3aR KO MRL mice. The increased chemokine and chemokine receptor expression seen in the C3aR KO MRL mice was associated with a more rapid rise in serum creatinine and the acceleration of renal fibrosis. However, loss of the C3aR had little impact on long-term kidney injury and did not alter survival. These findings suggest that activation of the C3aR plays a protective, not pathologic, role in the early phase of inflammatory nephritis in the MRL/lpr model of SLE.

[Screening biopsies in kidney transplantation: from subclinical acute rejection to chronic allograft lesions]

Kidney biopsies for screening purposes have the advantage of revealing the early appearance of lesions having a poor prognosis before kidney function is altered. Early screening of subclinical rejections allows preventive treatment of kidney transplantation in patients taking cyclosporine or azathioprine, thus improving their renal function and reducing the incidence of chronic histological lesions. However, this benefit has yet to be demonstrated in patients taking tacrolimus or mycophenolic acid. As for interstitial fibrosis lesions and tubular atrophy, biopsies can screen subclinical immunological lesions or those related to nephrotoxicity of anticalcineurins, which have a negative prognostic value in terms of graft survival. In addition, detection of these lesions could be a very useful criterion of efficacy in clinical studies. Moreover, they could help decide on modifying immunosuppressor treatment and evaluate the therapeutic strategies in patients at risk for humoral rejection. Finally, given the cost of biopsies and the inconvenience for the patient, the question of the timing and the number of screening biopsies is crucial. However, interventional studies evaluating notably immunosuppressor treatment modifications based on histological data are necessary to justify the daily use of screening biopsies.

Second harmonic microscopy to quantify renal interstitial fibrosis and arterial remodeling

Interstitial fibrosis is a powerful pejorative predictor of progression of nephropathies in a variety of chronic renal diseases. It is characterized by the depletion of kidney cells and their replacement by extracellular matrix, in particular, type-I fibrillar collagen, a protein scarce in normal interstitium. However, assessment of fibrosis remains a challenge in research and clinical pathology. We develop a novel methodology based on second harmonic generation (SHG) microscopy, and we image collagen fibers in human and mouse unstained kidneys. We take into account the variability in renal shape, and we develop automated image processing for quantitative scoring of thick murine tissues. This approach allows quantitative 3-D imaging of interstitial fibrosis and arterial remodeling with high accuracy. Moreover, SHG microscopy helps to raise pathophysiological questions. First, imaging of a large volume within a mouse kidney shows that progression of fibrosis is a heterogeneous process throughout the different renal compartments. Second, SHG from fibrillar collagens does not overlap with the glomerular tuft, despite patent clinical and experimental glomerulosclerosis. Since glomerulosclerosis involves SHG-silent nonfibrillar collagens, our work supports pathophysiological differences between interstitial fibrosis and glomerulosclerosis, a clearly nonfibrotic process.

A p38 mitogen-activated protein kinase inhibitor protects against renal damage in a non-heart-beating donor model

Ischemia-reperfusion injury is one of the central nonimmunologic processes involved in renal allograft dysfunction. Kidneys from non-heart beating donors (NHBD) exhibit higher rates of delayed graft function (DGF) than those from other donors. Primary nonfunction and DGF are the main barriers to the use of kidneys from NHBD. Using a pig model of NHBD transplantation, we studied the effect of FR167653 (a p38 MAP kinase inhibitor) on the recovery and reparation of kidneys exposed to both warm (WI: 1 h) and cold ischemia (24 h). Our results demonstrate that the addition of FR167653 increases the kinetics of proximal tubule cell regeneration after 60 min of WI. Hypoxia-inducible factor and vascular endothelial growth factor expression was also more important in FR167653-treated kidneys compared with those in nontreated groups. Also, expression of peripheral-type benzodiazepine receptor, involved in tissue repair, was increased in the FR167653-treated groups. At 3 mo, the protective effects of FR167653 were accompanied by a reduction of long-term inflammation process and tubulointerstitial fibrosis development associated with a limitation of ischemia-induced remodeling. This study suggests that such treatment may be useful in protocols aimed at improving the quality of renal transplants from NHBD. In addition, the beneficial role of FR167653 in limiting early injury is associated with secondary reduction in development of tubular atrophy and interstitial fibrosis which are together the hallmark of failing renal transplants. The more efficient effect was observed when FR167653 was added in combination before WI, during cold storage and reperfusion.

Quantification of interstitial fibrosis by image analysis on routine renal biopsy in patients receiving cyclosporine

BACKGROUND

Renal interstitial fibrosis (IF) is the main histopathological feature of chronic allograft injury. IF is currently assessed by semiquantitative analysis, but automatic color image analysis may be more reliable and reproducible. We performed a retrospective analysis to calculate IF on routine renal biopsies performed at 1 year posttransplant.

METHODS

Data were obtained from MO2ART, a prospective multicenter trial in which cyclosporine A dose was adjusted based on C2 level. One-year routine biopsies were assessed from 26 patients from two centers. For each biopsy, a section was analyzed by a program of color segmentation imaging, which automatically extracts green color areas characteristic of IF. Results were expressed as percentage of IF and grade (grade 1: <25%, grade 2: 25-50%, and grade 3: >50%).

RESULTS

Mean IF score was 0.35+/-0.04. Quantitative IF grade 1 was observed in 9 biopsies (34.6%), grade 2 in 12 (46.1%), and grade 3 in 5 (19.2%). Diabetes and cytomegalovirus infection were significantly associated with a higher percentage of IF. There was no correlation between the group of randomization and IF. We found a statistical significant correlation between Banff 05 chronic lesions classification and the IF index (P<0.02). Repeated analysis of variance demonstrated an association between high grade of automated IF and a worsening of creatinine clearance (Modification of Diet in Renal Disease) between 1 and 3 years.

CONCLUSIONS

Automatic quantification of IF on routine renal biopsies at one year posttransplant is predictive of long-term allograft function and may assist early diagnosis of the interstitial lesions of chronic allograft injury.

Lack of benefit of early protocol biopsies in renal transplant patients receiving TAC and MMF: a randomized study

We conducted a randomized, multicenter study to determine whether treatment of subclinical rejection with increased corticosteroids resulted in beneficial outcomes in renal transplant patients receiving tacrolimus (TAC), mycophenolate mofetil (MMF) and prednisone. One hundred and twenty-one patients were randomized to biopsies at 0,1,2,3 and 6 months (Biopsy arm), and 119 to biopsies at 0 and 6 months only (Control arm). The primary endpoint of the study was the prevalence of the sum of the interstitial and tubular scores (ci + ct)> 2 (Banff) at 6 months. Secondary endpoints included clinical and subclinical rejection and renal function. At 6 months, 34.8% of the Biopsy and 20.5% of the Control arm patients had a ci + ct score >or= 2 (p = 0.07). Between months 0 and 6, clinical rejection episodes were 12 in 10 Biopsy arm patients and 8 in 8 Control arm patients (p = 0.44). Overall prevalence of subclinical rejection in the Biopsy arm was 4.6%. Creatinine clearance at 6 months was 72.9 +/- 21.7 in the Biopsy and 68.90 mL/min +/- 18.35 mL/min in the Control arm patients (p = 0.18). In conclusion, we found no benefit to the procurement of early protocol biopsies in renal transplant patients receiving TAC, MMF and prednisone, at least in the short term. This is likely due to their low prevalence of subclinical rejection.

To Biopsy or Not to Biopsy? Should We Screen the Histology of Stable Renal Grafts?

Chronic allograft dysfunction is currently the main cause of late allograft failure. Recent encouraging evidence suggests that it may be possible to delay the development of graft damages if adequate management is initiated early in the course of the disease. These observations have renewed interest in the performance of protocol biopsies as routine follow-up procedure for the screening of renal transplants. In the present review, we summarize the available data from the literature to determine the pros and cons of protocol renal allograft biopsies. On the basis of this evidence, we discuss the ethical concerns raised by this procedure.

Urinary excretion of monocyte chemoattractant protein-1: a biomarker of active tubulointerstitial damage in patients with glomerulopathies

BACKGROUND/AIMS

The urinary concentration of the monocyte chemoattractant protein-1 (uMCP-1) chemokine is increased in several proteinuric and/or inflammatory renal diseases. In the present study, we evaluated the association between uMCP-1 and renal function, proteinuria, glomerular and interstitial macrophage infiltration, and renal fibrosis in patients with primary and secondary glomerulopathies diagnosed by renal biopsy.

METHODS

Thirty-seven patients aged 32.6 +/- 7.7 years were studied. uMCP-1 was determined by ELISA. Renal macrophage expression (CD68 positive cells) is reported as number of macrophages/10(4) microm2 of the cortical tubulointerstitial (TI) area or of glomerular capillary tuft area. Cortical interstitial fibrosis was quantitated by PicroSirius red staining under polarized light by a computerized manner.

RESULTS

The uMCP-1 ratio (pg/ml/urinary creatinine mg/ml) was positively correlated (Spearman coefficient) with proteinuria (r = 0.4629; p < 0.005) and number of macrophages in the cortical TI area (r = 0.64; p = 0.0005), and negatively correlated with creatinine clearance (r = -0.4877; p < 0.001). The uMCP-1 ratio was not significantly correlated with number of macrophages/glomerular capillary tuft area (r = 0.27; p = 0.19) or with percent cortical interstitial fibrosis (r = 0.08; p = 0.62).

CONCLUSIONS

The uMCP-1 excretion is a biomarker of the inflammatory activity of the TI area, and does not reflect chronic interstitial damage.

Detection of subclinical tubular injury after renal transplantation: comparison of urine protein analysis with allograft histopathology

BACKGROUND

Tubulointerstitial injury due to rejection leads to tubular atrophy (TA)/interstitial fibrosis (IF) followed by deterioration of allograft function. This study investigated whether urinary tubular injury biomarkers can detect subclinical tubulitis found in protocol biopsies allowing for a noninvasive screening procedure.

METHODS

Four rigidly defined groups (stable transplants with normal tubular histology [n=24], stable transplants with subclinical tubulitis [n=38], patients with clinical tubulitis Ia/Ib [n=18], and patients with other clinical tubular pathologies [n=20]) were compared for differences in urinary intact/cleaved beta2-microglobulin (i/cbeta2m), retinol-binding protein (RBP), neutrophil-gelatinase-associated lipocalin (NGAL), and alpha1-microglobulin (alpha1m).

RESULTS

Tubular proteinuria was present in 38% (RBP) to 79% (alpha1m) of patients in the stable transplant with normal tubular histology group. The stable transplant with subclinical tubulitis group had slightly higher levels of i/cbeta2m (P=0.11), RBP (P=0.17), alpha1m (P=0.09), and NGAL (P=0.06) than the stable transplant with normal tubular histology group with a substantial overlap. The clinical tubulitis Ia/Ib and the other clinical tubular pathology groups had significantly higher levels of RBP, NGAL, and alpha1m than stable transplants with normal tubular histology or stable transplants with subclinical tubulitis (P<0.002).

CONCLUSIONS

None of the investigated biomarkers allow for clear differentiation between stable transplants with normal tubular histology and stable transplants with subclinical tubulitis. Therefore, the protocol allograft biopsy currently remains the preferred tool to screen for subclinical tubulitis. Further longitudinal studies should determine whether tubular proteinuria in stable transplants with normal tubular histology indicates a clear risk for early development of TA/IF.

In vitro models of TGF-β-induced fibrosis suitable for high-throughput screening of antifibrotic agents

Progressive fibrosis is a cause of progressive organ dysfunction. Lack of quantitative in vitro models of fibrosis accounts, at least partially, for the slow progress in developing effective antifibrotic drugs. Here, we report two complementary in vitro models of fibrosis suitable for high-throughput screening. We found that, in mesangial cells and renal fibroblasts grown in eight-well chamber slides, transforming growth factor-β1 (TGF-β1) disrupted the cell monolayer and induced cell migration into nodules in a dose-, time- and Smad3-dependent manner. The nodules contained increased interstitial collagens and showed an increased collagen I:IV ratio. Nodules are likely a biological consequence of TGF-β1-induced matrix overexpression since they were mimicked by addition of collagen I to the cell culture medium. TGF-β1-induced nodule formation was inhibited by vacuum ionized gas treatment of the plate surface. This blockage was further enhanced by precoating plates with matrix proteins but was prevented, at least in part, by poly-l-lysine (PLL). We have established two cell-based models of TGF-β-induced fibrogenesis, using mesangial cells or fibroblasts cultured in matrix protein or PLL-coated 96-well plates, on which TGF-β1-induced two-dimensional matrix accumulation, three-dimensional nodule formation, and monolayer disruption can be quantitated either spectrophotometrically or by using a colony counter, respectively. As a proof of principle, chemical inhibitors of Alk5 and the antifibrotic compound tranilast were shown to have inhibitory activities in both assays.

Protocol biopsies in renal transplantation: prognostic value of structural monitoring

The natural history of renal allograft damage has been characterized in serial protocol biopsies. The prevalence of subclinical rejection (SCR) is maximal during the first months and it is associated with the progression of interstitial fibrosis/tubular atrophy (IF/TA) and a decreased graft survival. IF/TA rapidly progress during the first months and constitutes an independent predictor of graft survival. IF/TA associated with transplant vasculopathy, SCR, or transplant glomerulopathy implies a poorer prognosis than IF/TA without additional lesions. These observations suggest that protocol biopsies could be considered a surrogate of graft survival. Preliminary data suggest that the predictive value of protocol biopsies is not inferior to acute rejection or renal function. Additionally, protocol biopsies have been employed as a secondary efficacy variable in clinical trials. This strategy has been useful to demonstrate a decrease in the progression of IF/TA in some calcineurin-free regimens. Quantification of renal damage is associated with graft survival suggesting that quantitative parameters might improve the predictive value of protocol biopsies. Validation of protocol biopsies as a surrogate of graft survival is actively pursued, as the utility of classical surrogates of graft outcome such as acute rejection has become less useful because of its decreased prevalence with actual immunosuppression.

Developing a tool for noninvasive monitoring of renal allografts

Renal transplantation has emerged as the therapy of choice for many patients with end-stage renal disease. One of the major goals is to tailor immunosuppressive therapy to the individual needs of every patient at every time point post transplant, balancing the risk for rejection and over-immunosuppression. Such individualized treatment will require assays that can detect harmful processes in the allograft early and that can be measured repeatedly. In this review, advantages and disadvantages of current assays to monitor renal allografts noninvasively and how proteomic technology might contribute to the development of novel biomarkers to improve patient management will be discussed.

A Novel, Semiquantitative, Clinically Correlated Calcineurin Inhibitor Toxicity Score for Renal Allograft Biopsies

Calcineurin inhibitor toxicity (CNIT) is an important cause of chronic allograft nephropathy (CAN), but clinically relevant, diagnostic pathologic criteria remain to be defined. A semiquantitative, clinically correlative CNIT scoring system was developed and validated by pathologic analyses of 254 renal transplant biopsies that were obtained from 50 consecutive pediatric renal transplant recipients. Differentially weighted pathologic criteria (glomerulosclerosis, tubular atrophy, arteriolar medial hyaline, and tubular isometric vacuolization) contributed to the composite CNIT model score. Unlike other established pathology chronicity scores, such as the chronic allograft damage index, Banff, and modified Banff, the CNIT score was highly correlated with future graft function. The 3-mo CNIT score correlated significantly with 12 mo (P = 0.021) and 24 mo (P = 0.03) calculated creatinine clearance. Arteriolar medial hyalinosis seems to be the most important factor contributing to the clinical impact of the CNIT score.

Protective role of selectin ligand inhibition in a large animal model of kidney ischemia-reperfusion injury

Experiments in rodents have demonstrated an important role for selectins in kidney ischemia-reperfusion injury (IRI). However, the relevance of this in larger mammals, as well as the impact on long-term structure and function is unknown. We tested the hypothesis that small molecule selectin ligand inhibition attenuates IRI, cellular inflammation, and long-term effects on renal interstitial fibrosis. We used a porcine model of kidney IRI and used Texas Biotechnology Corporation (TBC)-1269, a selectin ligand inhibitor. Renal function, tissue inflammation, and tubulointerstitial fibrosis development were evaluated up to 16 weeks. Both warm and cold ischemia models were studied for relevance to native and transplant kidney injury. Pigs treated with TBC-1269 during 45 min of warm ischemia (WI) showed significantly increased glomerular filtration rate compared to control animals. In pigs with severe IRI (WI for 60 min), TBC-1269 treatment during IRI significantly increased renal recovery. Cellular inflammation was strongly reduced, particularly influx of CD4 cells. Quantitative measurement of fibrosis by picrosirius red staining showed strong reduction in TBC-1269-treated groups. TBC-1269 also reduced cold IRI, inflammation, and fibrosis in kidneys preserved for 24 h at 4 degrees C and autotransplanted. The selectin ligand inhibitor TBC-1269 provides a novel and effective approach to attenuate IRI in both warm and cold ischemia in large mammals, in both short and long terms. Selectin ligand inhibition is an attractive strategy for evaluation in human kidney IRI.

An image analysis-based method for quantification of chronic allograft damage index parameters

Chronic allograft damage index (CADI) is a semi-quantitative histopathological score that predicts renal graft outcome. We aimed to develop an objective image analysis-based method for quantification of CADI parameters. Thirty-five kidney transplant biopsies were visually analyzed according to the original CADI criteria, and divided into normal, mildly, moderately and severely altered groups. Digital images of the same samples were then analyzed with IPLab software. Areas of inflammation and fibrosis measured using image analysis increased simultaneously with corresponding visual scores, although the difference between non-inflamed and mildly inflamed groups was not statistically significant. Area of normal tubuli decreased in the images of samples with visually mild/moderate tubular atrophy and tended to be even smaller in the group with severe tubular atrophy. Image analysis-based glomerular sclerosis score increased concurrently with increasing visual score. Mesangial matrix increase score in image analysis was greater in the samples with visually mild/moderate mesangial matrix increase score compared to those with normal glomeruli, and it was highest in the group with severe mesangial matrix increase. An image analysis-based CADI scoring of renal allograft biopsies could provide more precise data for scientific studies, and help pathologists in renal allograft biopsy scoring.

Untreated rejection in 6-month protocol biopsies is not associated with fibrosis in serial biopsies or with loss of graft function

Donor age, calcineurin inhibitor nephrotoxicity, and acute rejection are the most significant predictors of chronic allograft nephropathy. Protocol biopsies, both in deceased- and living-donor renal grafts, have shown that cortical tubulointerstitial fibrosis correlates with graft survival and function. The impact of not treating subclinical acute rejection (SAR) is less clear. In this study, 126 de novo renal transplant recipients were randomly assigned to receive area-under-the-curve-controlled exposure of either a cyclosporine or a tacrolimus-based immunosuppressive regimen that included steroids, mycophenolate mofetil, and basiliximab induction. Protocol biopsies were taken before and 6 and 12 mo after transplantation. The prevalence of SAR was determined retrospectively. Fibrosis was evaluated by quantitative digital analysis of Sirius red staining in serial biopsies. Donor age correlated significantly with tubulointerstitial fibrosis in pretransplantation biopsies and inferior graft function at month 6 (rtau = -0.26; P = 0.033). Acute rejection incidence was 11.5%, and no clinical late rejection occurred. The prevalence of SAR at 6 mo was 30.8% but was not associated with differences in serial quantitative Sirius red staining at 6 or 12 mo, proteinuria, or progressive loss of GFR up to 2 yr. No differences were found in donor variables, histocompatibility, rejection history, or exposure of immunosuppressants. Controlled individualized calcineurin inhibitor exposure and subsequent tapering resulted in a low early acute rejection rate and prevented late acute rejection. Because, by design, we did not treat SAR, these results provide evidence that asymptomatic infiltrates in 6-mo surveillance biopsies may not be deleterious in the intermediate term. There is need for reliable biomarkers to prove that not all cell infiltrates are equivalent or that infiltrates may change with time.

Apoptosis and Caspase-3 in Long-Term Renal Ischemia/Reperfusion Injury in Rats and Divergent Effects of Immunosuppressants

BACKGROUND

Caspase-3 plays a key role in apoptosis, but the involvement of apoptosis and caspase-3 in mediating long-term ischemia/reperfusion (I/R) and immunosuppressive injury are not fully defined. The present study was undertaken to investigate apoptosis and caspase-3 in a renal I/R injury rat model with or without immunosuppression.

METHODS

The right renal pedicle was clamped for 45 minutes and left nephrectomy was induced. Cyclosporin A (CsA), tacrolimus (Tac), rapamycin (Rap), or mycophenolate mofetil (MMF) were administered daily. Animals were killed at 16 weeks, and the levels of apoptosis (with in situ end-labeling fragmented DNA), caspase-3 protein (with immunohistochemistry, Western blotting, and activity assay), and messenger RNA (mRNA; with quantitative reverse-transcriptase polymerase chain reaction) were evaluated.

RESULTS

Kidneys with I/R injury showed increased apoptosis in tubular and interstitial areas compared with control kidneys. Tacrolimus, Rap, and MMF significantly reduced apoptosis, but CsA did not. Distribution of full-length caspase-3 widened in I/R-injured kidneys from normal distal tubules and collecting ducts to dilated proximal tubules and expanded interstitium, whereas active caspase-3 was mainly scattered in damaged tubules and interstitium. Active caspase-3 staining and 24-kDa active caspase-3 protein was enhanced in I/R-injured and CsA-treated kidneys, but decreased by Tac, Rap, and MMF. These results were also consistent with changes in caspase-3 activity. Although caspase-3 mRNA levels were significantly increased in uninephrectomy and I/R-injured kidneys, they were not significantly affected by the immunosuppressants. In addition, all changes detected were positively correlated with renal structure and function.

CONCLUSION

Apoptosis and caspase-3 are not only involved in the long-term renal I/R injury, but also mediate the divergent effects of immunosuppression in this model.

Molecular comparison of calcineurin inhibitor-induced fibrogenic responses in protocol renal transplant biopsies

The calcineurin inhibitor cyclosporine (CsA) induces a fibrogenic response that may lead to scarring of the renal allograft. This study investigated whether tacrolimus, a novel calcineurin inhibitor, exerts fibrogenic effects to a similar extent. Sixty patients were enrolled in a randomized study: 29 received CsA, and 31 received tacrolimus. Patients were subjected to tailored exposure-controlled calcineurin inhibitor regimens. Protocol biopsies were obtained at the time of transplantation and 6 and 12 mo after transplantation. Cortical TGF-beta and collagens alpha1(I) and alpha1(III) mRNA steady-state levels were determined with real-time PCR. The extent of protein deposition of TGF-beta, alpha-smooth muscle actin, and interstitial collagens in the renal cortex was quantified with computer-assisted image analysis. The extent of interstitial collagen deposition measured with Sirius red and the accumulation of alpha-smooth muscle actin and TGF-beta protein after 6 and 12 mo were similar for both immunosuppressive regimens. mRNA levels of TGF-beta and collagens alpha1(I) and alpha1(III) were not significantly different in the treatment groups either. It is concluded that the fibrogenic response in renal allografts is similar in patients who receive CsA-based regimens and patients who receive tacrolimus-based regimens.

Transcriptional analysis of the molecular basis of human kidney aging using cDNA microarray profiling

BACKGROUND

The molecular basis of renal aging is not completely understood.

METHODS

We used global gene expression monitoring by cDNA microarrays to identify age associated genes in human kidney samples. Our samples included young (8 weeks-8 years, N= 4), adult (31-46 years, N= 7), and old kidneys (71-88 years, N= 9).

RESULTS

Old kidneys had more glomerulosclerosis, tubular atrophy, interstitial fibrosis, and fibrous intimal thickening in small arteries. We identified approximately 500 genes that were differentially expressed among the three age groups. Old kidneys appeared to have increased extracellular matrix turnover and a nonspecific inflammatory response, combined with a reduction in processes dependent on energy metabolism and mitochondrial function. Quantitative supervised bioinformatics analyses of adult and old kidney expression data correlated the expression of 255 gene profiles with renal pathology scores. Microarray class prediction analysis (PAM) identified 50 unique genes that segregated old kidneys into two distinct clusters: those more similar within age class (OO, N= 5) versus old kidneys more similar to adult kidneys (OA, N= 4). The expression of six functionally significant genes was further validated by quantitative reverse transcription-polymerase chain reaction (RT-PCR) (FN1, MMP7, TNC, SERPIN3A, BPHL, CSPG2) in the experiment group and, subsequently, confirmed independently in 17 additional old and adult age-stratified test kidney samples. The p53 inducible gene, CSPG2, performed best in separating OO kidneys from adults and OA samples in this analysis.

CONCLUSION

The method described in this study using independent validation samples can be envisioned to test utility of the identified genes in assessing age-related changes that contribute to decline in renal function.

No difference in degree of interstitial Sirius red-stained area in serial biopsies from area under concentration-over-time curves-guided cyclosporine versus tacrolimus-treated renal transplant recipients at one year

Interstitial fibrosis is the main characteristic of chronic allograft nephropathy and long-term graft failure. Cyclosporin (CsA) is thought to be more fibrogenic than tacrolimus. In a prospective, randomized, multicenter trial using a calcineurin-sparing regimen, renal interstitial volume was compared in CsA- and tacrolimus-treated renal transplant recipients by image analysis of Sirius red (SR)-stained cortical areas in protocol biopsies obtained at 6 mo (n = 94) and 12 mo (n = 97) after transplantation. Immunosuppression consisted of CsA or tacrolimus, CD25 mAb, mycophenolate mofetil, and prednisolone. CsA therapy increased the 6-mo risk for subclinical rejection. The prevalence of subclinical rejection was 38.8% in the CsA-treated and 15.2% in the tacrolimus-treated patient group (P = 0.012). Strikingly, no difference in the degree of interstitial SR-stained area was detectable between the two treatment groups. In particular, previous subclinical rejection episodes did not influence the degree of interstitial volume. Also, no difference in GFR occurred at 1 yr, when the mean GFR mounted 63 ml/min. No significant differences in the degree of interstitial SR-stained area could be observed at 6 and 12 mo between CsA- and tacrolimus-treated renal transplant recipients. Although CsA-treated patients developed significantly more subclinical rejections at 6 mo, this did not influence the degree of SR staining or the change in renal function at 1 yr.

Inflammation and caspase activation in long-term renal ischemia/reperfusion injury and immunosuppression in rats

BACKGROUND

We have previously shown the long-term influence of renal ischemia/reperfusion (I/R) injury and immunosuppression on fibrotic genes and apoptosis in a rat model. For the first time, we have now investigated the effects of I/R and immunosuppression on inflammation and caspase activation.

METHODS

I/R injury was induced in the right kidney and the left was removed. Cyclosporin (CsA) (10 mg/kg), tacrolimus (0.2 mg/kg), rapamycin (1 mg/kg), or mycophenolate mofetil (MMF) (10 mg/kg) was then administered for 16 weeks. The effects of I/R and immunosuppressants on interstitial inflammation, interleukin (IL)-1beta expression, caspase-1 and caspase-3 activation, tubulointerstitial damage, and fibrosis were evaluated.

RESULTS

ED-1+ (a specific rat monocyte/macrophage marker) cells were mainly localized in the tubulointerstitium and periglomerular areas and increased in I/R group compared to controls (P < 0.01). This was further increased by CsA, but decreased by tacrolimus, rapamycin, or MMF (P < 0.05). The 17 kD active IL-1beta remained unchanged, but 35 kD IL-1beta precursor was decreased by rapamycin in comparison with I/R group (P < 0.05). The 45 kD or 20 kD caspase-1 was increased by I/R or CsA, respectively, and decreased by rapamycin (P < 0.05). The 24 kD caspase-3, which proved to be an active caspase-3 subunit, was increased in I/R and CsA groups and deceased by tacrolimus, rapamycin, or MMF (P < 0.05), but not 32 kD precursor or 17 kD active caspase-3. The activity data of caspase-1 and caspase-3 exhibited the same trend as Western blotting data. The staining of active caspase-3 was scattered in kidneys, mainly in tubular and interstitial areas, which was consistent with that of ED-1+ cells. There was a strong positive correlation between interstitial inflammation and 24 kD caspase-3 expression or caspase-3 activity (r = 0.814 or 0.484), all of which were also closely related with urinary protein (r = 0.537, 0.529, or 0.517), serum creatinine (r = 0.463, 0.573, or 0.539), tubulointerstitial damage (r = 0.794, 0.618, or 0.712) and fibrosis (r = 0.651, 0.567, or 0.469), all P < 0.01.

CONCLUSION

This study shows that the mechanisms of long-term I/R injury and immunosuppressants treatment include interstitial inflammation and caspase activation, most clearly demonstrated by the 24 kD active caspase-3.

Predicting subsequent decline in kidney allograft function from early surveillance biopsies

Identifying factors that are predictive of allograft loss might be an important step toward prolonging kidney allograft survival. In this study we sought to determine the association between histologic changes on 1-year surveillance biopsies, changes in graft function and survival. This analysis included 292 adults, recipients of kidneys from living donors (69%) or deceased donors (31%), transplanted between 1998 and 2001 and followed up for 46 +/- 14 months. The primary end point was death-censored graft loss or a >50% reduction in GFR beyond 1 year. One-year biopsies were classified as: (i) Normal (N = 87, 30%), (ii) inflammation (N = 6, 2%), (iii) fibrosis (N = 131, 45%), (iv) fibrosis and inflammation (N = 53, 18%) and (v) transplant glomerulopathy (N = 15, 5%). By multivariate Cox analysis, survival related to biopsy classification (HR = 4.2, p = 0.001), graft function (HR = 0.97, p = 0.001) and HLA mismatches (HR = 1.003, p = 0.004). Using normal histology as a reference, fibrosis and inflammation (HR = 8.5, p < 0.0001) and glomerulopathy (HR = 10, p < 0.0001) related to poorer survival but mild fibrosis alone did not. Importantly, the degree of inflammation associated with fibrosis generally did not qualify for the diagnosis of borderline rejection. In conclusion, inflammation and glomerulopathy 1 year post-transplant predict loss of graft function and graft failure independently of function and other variables.

Multiple potential clinical benefits for 1alpha,25-dihydroxyvitamin D3 analogs in kidney transplant recipients

Therapeutic trials of 1alpha,25(OH)(2)D(3) and related synthetic analogs are merited in diverse clinical fields, including treatment or prevention of bone disease, cancer, immune-mediated diseases, cardiovascular diseases, and prostatic hypertrophy. Potential difficulties of carrying out such trials successfully, include experimental data suggesting relatively modest therapeutic effects of 1alpha,25(OH)(2)D(3) analogs as stand-alone intervention and the likely requirement for large study group size and lengthy follow-up periods, if individual prophylactic effects are to be proven. Thus, it may be wise to identify patient groups with multiple potential benefits, accelerated disease risks, and the possibility for exploring synergistic pharmacological effects, in whom to carry out clinical trials of 1alpha,25(OH)(2)D(3) analogs. With this consideration in mind, the suitability of kidney transplant recipients for such studies is discussed. Although, highly effective in reversing end-stage renal disease, kidney transplantation continues to be limited by heightened risk of osteoporosis, persistent hyperparathyroidism, acute and chronic immunological injury, new cancer diagnosis, and cardiovascular events. In addition, kidney transplant recipients generally receive multiple immunosuppressants with a high prevalence of medication-related toxicities. Finally, it is pointed out that clinical trials carried out in organ transplant recipients provide a unique opportunity for longitudinal comparison of target tissue structural and gene expression profiles among treated and control patient groups. It is proposed that addition of a 1alpha,25(OH)(2)D(3) analog to conventional post-kidney transplant medication regimens is likely to be associated with measurable effects to prevent or retard multiple important complications and that this patient group is especially suitable for carrying out clinical trials of these compounds.

Kidney allograft fibrosis and atrophy early after living donor transplantation

Kidney allograft failure is most often caused by chronic allograft nephropathy, a process of interstitial fibrosis (GIF) and tubular atrophy (TA). We assessed the pathology of living donor (LD) grafts compared to deceased donor (DD). Included are 321 recipients (245 LD; 76 DD) with protocol biopsies the first 2 years of transplant. In LD, GIF was present in 7%, 31%, 61% and 71% of grafts at 0, 4, 12 and 24 months. TA progressed in parallel to GIF. Compared to LD, more DD grafts had GIF at time 0 (29%, p = 0.002); thereafter the incidence of GIF was similar. In LD, GIF was associated with lower glomerular filtration rate (GFR)(1 year) (no GIF, 62 +/- 16; GIF, 49 +/- 15 mL/min/m(2) iothalamate clearance, p = 0.001) and reduced graft survival (HR = 2.2, p = 0.009). GIF in LD related to acute rejection (HR = 2.6, p = 0.01), polyoma nephropathy (OR = 4.4, p = 0.02) and lower levels of GFR 3 weeks post-transplant (HR = 0.961; p = 0.03, multivariate). However, GIF also developed in 53% of recipients lacking these covariates. Thus, GIF/TA develops in the majority of LD grafts, it is often mild but is associated with reduced function and survival. GIF frequently develops in the absence of risk factors. Lower GFR post-transplant identify patients at highest risk of GIF.

Proteomic-based identification of cleaved urinary beta2-microglobulin as a potential marker for acute tubular injury in renal allografts

Our aim is to develop noninvasive tests to monitor the renal allograft posttransplant. Previously, we have reported that an unbiased proteomic-based approach can detect urine protein peaks associated with acute tubulointerstitial renal allograft rejection. Identification of these proteins peaks by mass spectrometry demonstrated that they all derive from nontryptic cleaved forms of beta2-microglobulin. In vitro experiments showed that cleavage of intact beta2-microglobulin requires a urine pH < 6 and the presence of aspartic proteases. Patients with acute tubulointerstitial rejection had lower urine pH than stable transplants and healthy individuals. In addition, they had higher amounts of aspartic proteases and intact beta2-microglobulin in urine. These factors ultimately lead to increased amounts of cleaved urinary beta2-microglobulin. Cleaved beta2-microglobulin as an indicator of acute tubular injury may become a useful tool for noninvasive monitoring of renal allografts.

Desmoplasia measured by computer assisted image analysis: an independent prognostic marker in colorectal carcinoma

AIMS

The assessment of desmoplasia by traditional semiquantitative methods does not provide reliable prognostic data. The aim of this study was to quantify desmoplasia by computerised image analysis in primary colorectal carcinomas and to investigate its ability to predict overall survival.

METHODS

In total, 112 colorectal adenocarcinomas, with a median follow up of 66 months, were studied. The representative tumour sections were stained by the van Gieson method, which stains collagen rich stroma red. For quantitative histochemical measurement, digital images were analysed by a computerised image analysis program to calculate the percentage of red stained tissue area. The percentage of desmoplasia (PD) was related to conventional clinicopathological prognostic factors and overall survival.

RESULTS

The mean (SD) PD was 4.85 (3.37). PD was found to be significantly associated with lymph vessel and venous invasion. By Kaplan-Meier analysis, PD was associated with survival-patients with PD > 4 had a shorter survival than those with PD

CONCLUSION

Desmoplasia measured by image analysis seems to be a significant prognostic indicator in patients with colorectal carcinoma and the improved method described in this study would be useful for routine prognostication.

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Key Words

• desmoplasia
• colorectal carcinoma
• prognosis
• quantitative histochemistry
• image analysis

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MESH Headings

• Adenocarcinoma/pathology
• Adenocarcinoma/secondary
• Adult
• Aged
• Aged, 80 and over
• Blood Vessels/pathology
• Colorectal Neoplasms/pathology
• Fibrosis
• Follow-Up Studies
• Humans
• Image Processing, Computer-Assisted/methods
• Lymphatic Vessels/pathology
• Middle Aged
• Neoplasm Invasiveness
• Neoplasm Staging
• Prognosis
• Reproducibility of Results
• Survival Analysis

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Affiliation(s)

B Sis Department of Pathology, Dokuz Eylül University School of Medicine, Inciralti, Izmir 35340, Turkey
S Sarioglu
S Sokmen
M Sakar
A Kupelioglu
M Fuzun

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Injury and progressive loss of peritubular capillaries in the development of chronic allograft nephropathy

BACKGROUND

Chronic allograft nephropathy (CAN) remains the most important cause of late renal graft loss. However, the mechanism for graft dysfunction and the process of the development of CAN are not well understood. This study examined the role of microvascular injury in the development of CAN.

METHODS

We studied renal biopsies obtained from grafts with CAN (N= 79) and pretransplant control kidneys (N= 20). Microvascular injury was examined morphologically, and was correlated with interstitial fibrosis, glomerular sclerosis, graft function, and the severity of CAN. The humoral and cellular immunity involved in CAN were examined by C4d, CD3, and TIA-1 staining.

RESULTS

In all the cases of CAN, microvascular injury was evident with or without CD3-positive T cells, TIA-1-positive cytotoxic cells, and/or C4d+ complement deposition. Irrespective of chronic rejection (N= 14), C4d+ chronic humoral rejection (N= 6), or other CAN, the development process of CAN was characterized by injury and progressive loss of identifiable peritubular capillaries (PTCs) accompanied with the development of interstitial fibrosis. Injured PTCs were characterized morphologically by the process of angioregression with the presence of apoptotic cells, lamination of the basement membrane, and loss of PTCs. The low number of PTCs correlated significantly with the severity of CAN (r=-0.74, P < 0.001), the development of interstitial fibrosis (r=-0.75, P < 0.001), graft dysfunction (r=-0.69, P < 0.001), and also correlated weakly with proteinuria (r=-0.45, P < 0.05). In the glomeruli, capillary loss significantly correlated with the degree of glomerular sclerosis (r=-0.66, P < 0.001) and proteinuria (r=-0.65, P < 0.001), but did not correlate with the severity of CAN (r=-0.24, P > 0.05) or graft dysfunction (r=-0.32, P > 0.05).

CONCLUSION

CAN was characterized by progressive injury to the renal microvasculature and the development of renal scarring. In particular, injury, angioregression and progressive loss of the PTC network strongly contributed to the development of interstitial fibrosis and graft dysfunction in CAN, and might play a crucial role in the development of CAN.

Combating Chronic Renal Allograft Dysfunction

Kidney transplantation is the best treatment for patients with end-stage renal disease, both in terms of survival benefit and quality of life. The major limitation is the continuing shortage of kidneys suitable for transplantation, reinforcing the need to maximise graft survival. After the first year of transplantation, chronic renal allograft dysfunction (CRAD) is the first cause of late graft deterioration and failure. CRAD has been defined as a progressive renal dysfunction, independent of acute rejection, drug toxicity and recurrent or de novo nephropathy, with features on biopsy of chronic allograft nephropathy (CAN) characterised by vascular intimal hyperplasia, tubular atrophy, interstitial fibrosis and chronic transplant glomerulopathy. Protocol biopsy-based studies have demonstrated a high and early prevalence of CAN lesions during the first year in patients with normal and stable renal function. Beyond 1 year, the injuries associated with calcineurin inhibitors (CNIs) appear to be very common. The physiopathology of CRAD is complex and multifactorial. Both alloantigen-dependent factors (acute rejection, HLA matching, donor-specific antibodies, inadequate immunosuppression) and alloantigen-independent factors (donor age, brain death, ischaemia/reperfusion injuries, hypertension, hyperlipidaemia, cytomegalovirus, CNI-related nephrotoxicity) are involved. Consequently, CRAD appears as a dynamic process, evolving with time, and immunosuppressive regimens need to be modulated in order to provide the most suitable treatment at the different phases of its natural history. On the basis of this scheme, the new paradigm would be the use of a CNI-based regimen during the period of maximal risk of (subclinical) acute rejection, followed by a conversion to a CNI-free regimen in order to avoid the long-term consequences of nephrotoxicity. Fortunately, new agents are being introduced in clinical practice providing a large range of combinations and allowing individualisation of immunosuppressive regimens. Large, prospective, multicentre trials are warranted, and the challenge is to define new endpoints of CRAD and to determine the best therapeutic strategy.

Methenamine silver staining quantitative digital histochemistry in chronic allograft nephropathy

Renal function and final outcome of renal allografts have been correlated with irreversible damage. This study describes a quantitative histochemical method relying on periodic acid methenamine silver (PAMS) staining of all renal compartments. Among 60 renal allograft biopsies from 43 patients, 15 biopsies showing pure chronic allograft nephropathy were selected to determine PAMS-stained area percentage (SAP), using image analysis with quantitative histochemistry. Of the 15 cases, 9 (60%) were grade I and 6 (40%) were grade II chronic allograft nephropathy (CAN). The mean serum creatinine (sCr) value was 1.86 +/- 0.47 for allograft biopsies. The mean (+/-SD) SAP for the implantation biopsies was 10.58 +/- 1.87%, and for allograft biopsies 25.26 +/- 9.67 (P <<.000). The serum creatinine (sCr) values for grade I versus II CAN were 1.63 +/- 0.24 versus 2.20 +/- 0.54 mg/dL, respectively (P=.019), and SAP values were 18.97 +/- 0.24 versus 34.7 +/- 5.89 (P=.003). There was a strong positive correlation between sCr values and SAP (P=.005; r=0.64). These findings show the PAMS approach to be a useful alternative method for reflecting damage in more than one compartment of the renal tissue. Also, the method can discriminated implantation and allograft biopsies as well as grade I and II CAN cases. The series is small for a multivariate analysis of the value of SAP measurements in PAMS-stained sections as a prognosticator, but the data support its use.

Renal arterial resistance index and computerized quantification of fibrosis as a combined predictive tool in chronic allograft nephropathy

The renal arterial resistance index (RI) and the PicroSirius-Red stained cortical fractional interstitial fibrosis volume (VintFib) proved to be two independent methods that are reliable predictive factors of poor renal allograft outcome. No data have been published, which define the correlation between ultrasound assessment and quantitative morphologic changes. Renal biopsies were performed in 56 children according to increases in s-creatinine >10%. VintFib was calculated by computerized image analysis. RI was determined in two segmental arteries, 1 yr after transplantation and at the time-point of biopsy. RIs 1 yr after transplantation correlated significantly with RIs at time of biopsy (r = 0.58, p < 0.001). VintFib was higher in children with a RI = 80 than in children with a RI < 80 (mean VintFib = 9.5 +/- 3.2% vs. 5.2 +/- 5.1%, p = 0.004). In children with VintFib > 10%, the mean RI was 77 +/- 5 compared with 69 +/- 6 in patients with VintFib < 10% (p = 0.0002). The highest positive predictive value to detect the risk of decline of GFR at 2 yr after biopsy was 98% when an RI = 80% was associated with a VintFib > 10%. For VintFib > 10% or RI = 80 alone, it was 87% or 67%, respectively. The combined measurement of RI and VintFib is a reliable predictive tool for the risk of developing long-term graft dysfunction after kidney transplantation.

Patient and graft outcomes from older living kidney donors are similar to those from younger donors despite lower GFR

BACKGROUND

Donor age adversely affects deceased-donor kidney transplant outcomes, but its influence on living-donor transplantation is less well characterized.

METHODS

Living-donor kidney transplants at a single center between 1998 and 2000 were reviewed. Data were abstracted for 52 transplants from donors aged > or =50 years and for a matched group of 104 transplants from donors aged <50 years. Survival indices were compared during the first three years' post-transplantation. Functional indices, including serial iothalamate clearances, were compared at 1, 12, and 24 months.

RESULTS

Predonation glomerular filtration rate (GFR) was lower among older donors (94 +/- 12 vs. 108 +/- 17 mL/min/SA) but post-transplant compensatory hypertrophy was similar (11.7 +/- 26.3% vs. 7.7 +/- 31.4%). Recipients of older-donor grafts were older (52.8 +/- 16.5 vs. 46.1 +/- 15.1 years) and more frequently unrelated to the donor (54% vs. 39%). Trends toward higher frequency of slow graft function, cytomegalovirus (CMV) infection, and polyomavirus nephropathy were observed for older-donor grafts. Three-year recipient, graft, and death-censored graft survivals were > or =90% for both groups. At 1, 12, and 24 months, serum creatinine was higher and GFR was lower among recipients of older- compared with younger-donor grafts. Other functional indices (urine total protein, serum potassium and uric acid, hemoglobin, and number of antihypertensives) were not different. Donor age correlated with graft GFR at 1, 12, and 24 months for the entire study cohort by linear regression.

CONCLUSION

Older donor age does not preclude excellent results from living-donor kidney transplantation but should be appreciated as being associated with relatively lower GFR.

Genetic linkage of albuminuria and renal injury in Dahl salt-sensitive rats on a high-salt diet: comparison with spontaneously hypertensive rats

Our aim was to study the effects of high-salt diet on the genetics of albuminuria and renal injury in the Dahl salt-sensitive (SS) rat. We compared SS with salt-resistant spontaneously hypertensive rats (SHR) and with genetically related salt-sensitive stroke-prone SHR (SHRSP). Moreover, we performed genome-wide linkage analysis to identify quantitative trait loci (QTL) contributing to salt-induced renal injury in an F2population derived from SS and SHR ( n = 230). In response to high-salt diet SS and SHRSP developed a striking increase in systolic blood pressure, urinary albumin excretion (UAE), and renal damage indices compared with SHR. Both SHRSP and SS developed severe glomerulosclerosis, whereas microangiopathy, tubulointerstitial fibrosis, and inflammation were more pronounced in SHRSP. We detected two QTL with significant linkage to UAE on rat chromosomes (RNO) 6 and 19. Comparison with the recently identified salt-independent UAE QTL in young animals revealed that the UAE QTL on RNO6 is unique to high-salt conditions, whereas RNO19 plays a significant role during both low- and high-salt conditions. Some F2animals demonstrated severe microangiopathy and tubulointerstitial injury, which exceeded the degree observed in the parental SS strain. Three loci demonstrated suggestive linkage to these phenotypes on RNO3, RNO5, and RNO20, whereas no linkage to glomerular damage was found. Further analyses at these loci indicated that the severity of renal injury was attributable to the SHR allele. Our data suggest that the SHR genetic background confers greater susceptibility for the development of microangiopathy and tubulointerstitial injury in salt-sensitive hypertension than the SS background.

Protective roles of polyethylene glycol and trimetazidine against cold ischemia and reperfusion injuries of pig kidney graft

Ischemia-reperfusion injury (IRI) represents an allo-independent risk factor which favors chronic allograft nephropathy (CAN). Here we analyzed the influence of preservation solutions on the function of autotransplanted pig kidneys over 1-16 weeks after surgery. Kidneys were cold-flushed and cold-stored for 24 or 48 h either in University of Wisconsin (UW), modified-UW Hôpital Edouard Herriot, polyethylene glycol 20 kDa (PEG)-supplemented preservation solutions with low K+ (ECPEG) or high K+ (ICPEG) content. Animals autotransplanted with kidneys cold-stored for 24 h in ECPEG exhibited the greatest levels of creatinine clearance (Ccr: 161 +/- 12 mL/min, n=10) and the lowest levels of proteinuria (0.5 +/- 0.03 mg/mL) 16 weeks after surgery as compared with pigs autotransplanted with kidneys cold-stored in the other solutions tested (Ccr ranging from 80 and 140 mL/min). Similar differences, but with lower Ccr levels, were achieved after a prolonged period of cold-storage(48 h). ECPEG better preserved the kidneys from monocytes/macrophages and CD4+ T cells infiltrations, VCAM-1 and MHC class II overexpressions and occurrence of renal interstitial fibrosis (2%) as compared with the other preservation solutions (5%-20%). Adding the anti-ischemic drug trimetazidine (TMZ) to the preservation solutions, particularly ECPEG, further improved the quality of the week-16 post-transplanted kidneys (Ccr: 182 +/- 12 mL/min, n=10). These findings demonstrated that adding PEG to extracellular-like (with low K+ content) preservation solutions in combination with TMZ significantly improved the long-term outcome of kidney grafts in this model of autotransplanted pig kidney.