Semiautomatic quantitation of macrophages in human renal biopsy specimens in proteinuric states

Absence of the Lectin Activation Pathway of Complement Ameliorates Proteinuria-Induced Renal Injury

Proteinuria is an adverse prognostic feature in renal diseases. In proteinuric nephropathies, filtered proteins exert an injurious effect on the renal tubulointerstitium, resulting in inflammation and fibrosis. In the present study, we assessed to what extent complement activation via the lectin pathway may contribute to renal injury in response to proteinuria-related stress in proximal tubular cells. We used the well-established mouse model of protein overload proteinuria (POP) to assess the effect of lectin pathway inhibition on renal injury and fibrotic changes characteristic of proteinuric nephropathy. To this end, we compared experimental outcomes in wild type mice with MASP-2-deficient mice or wild type mice treated with MASP-2 inhibitor to block lectin pathway functional activity. Multiple markers of renal injury were assessed including renal function, proteinuria, macrophage infiltration, and cytokine release profiles. Both MASP-2-deficient and MASP-2 inhibitor-treated wild type mice exhibited renoprotection from proteinuria with significantly less tubulointerstitial injury when compared to isotype control antibody treated mice. This indicates that therapeutic targeting of MASP-2 in proteinuric nephropathies may offer a useful strategy in the clinical management of proteinuria associated pathologies in a variety of different underlying renal diseases.

Evaluation of renal quantitative T2* changes on MRI following administration of ferumoxytol as a T2* contrast agent

PURPOSE

To evaluate the time-dependent changes in regional quantitative T2* maps of the kidney following intravenous administration of ferumoxytol.

MATERIALS AND METHODS

Twenty-four individuals with normal kidney function underwent T2*-weighted MRI of the kidney before, immediately after, and 48 hours after intravenous administration of ferumoxytol at a dose of 4 mg/kg (group A, n=12) or 6 mg/kg (group B, n=12). T2* values were statistically analyzed using two-tailed paired t-tests.

RESULTS

In group A, the percentage changes from baseline to immediate post and baseline to 48 hours were 85.3% and 64.2% for the cortex and 90.8% and 64.6% for the medulla, respectively. In group B, the percentage changes from baseline to immediate post and baseline to 48 hours were 85.2% and 73.4% for the cortex and 94.5% and 74% for the medulla, respectively. This difference was significant for both groups (P<0.0001).

CONCLUSION

There is significant and differential uptake of ferumoxytol in the cortex and medulla of physiologically normal kidneys. This differential uptake may offer the ability to interrogate renal cortex and medulla with possible clinical applications in medical renal disease and transplant organ assessment. We propose an organ of interest based dose titration of ferumoxytol to better differentiate circulating from intracellular ferumoxytol particles.

Impact of 2,3,7,8-tetrachlorodibenzo-p-dioxin on cutaneous wound healing

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a representative of a large group of polyhalogenated aromatic hydrocarbons that are widespread environmental contaminants. Administration of TCDD to laboratory animals or cultured cells results in a number of adverse effects that are well documented. For example, the effects of TCDD observed in developing organisms indicate that exposure to this class of environmental contaminants significantly alters embryo morphogenesis. However, it is not clear whether tissue regeneration in adult animals may be similarly affected. With this in mind, we examined the impact of TCDD exposure on wound healing using a murine cutaneous wound healing model. Our results indicate that TCDD exposure did not significantly alter the time needed for wound closure. However, in the TCDD-treated mice, a significant decrease in tensile strength in the healed wounds was observed which is indicative of an aberrantly healed wound. Immunostaining revealed that exposure to TCDD increased the population of macrophages detected within the wounded tissue at the latter stages of wound healing. Our findings support the idea that exposure to environmental contaminants such as TCDD is proinflammatory in the wounded tissue, disrupts normal healing and ultimately produces in a poorly healed wound.

Histopathologic features aid in predicting risk for progression of IgA nephropathy

BACKGROUND AND OBJECTIVES

IgA nephropathy (IgAN) is the most common primary glomerular disease worldwide. Accurately identifying patients who are at risk for progressive disease is challenging. The extent to which histopathologic features improves prognostication is uncertain.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We studied a retrospective cohort with biopsy-proven IgAN in Calgary, Canada. Renal biopsies were reviewed by a nephropathologist with histopathologic data abstracted using a standardized form. The primary outcome was the composite of doubling of serum creatinine, ESRD, or death. Spline models defined significant levels of interstitial fibrosis, glomerulosclerosis, hypertension, proteinuria, and creatinine. The prognostic significances of clinical and histopathologic parameters were determined using Cox proportional hazards models.

RESULTS

Data from 146 cases were available for analysis with a median follow-up of 5.8 years. Greater than 25% interstitial fibrosis, >40% glomerular sclerosis, and a systolic BP >150 mmHg were risk thresholds. In univariable analyses, baseline creatinine, proteinuria, systolic BP, glomerular sclerosis, interstitial fibrosis, and crescentic disease were predictors of the primary outcome. In multivariable models adjusted for clinical characteristics, interstitial fibrosis (hazard ratio [HR]2.7; 95% confidence interval [CI] 1.2 to 6.0), glomerular sclerosis (HR 2.6; 95% CI 1.2 to 4.5), and crescents (HR 2.4; 95% CI 1.2 to 5.1) remained independent predictors of the primary outcome and significantly improved model fit compared with clinical characteristics alone.

CONCLUSIONS

Baseline histopathologic parameters are independent predictors of adverse outcomes in IgAN even after taking into consideration clinical characteristics. Relatively small degrees of interstitial fibrosis confer an increased risk for progressive IgAN.

An efficient and reproducible method for quantifying macrophages in different experimental models of central nervous system pathology

Historically, microglia/macrophages are quantified in the pathological central nervous system (CNS) by counting cell profiles then expressing the data as cells/mm(2). However, because it is difficult to visualize individual cells in dense clusters and in most cases it is unimportant to know the absolute number of macrophages within lesioned tissue, alternative methods may be more efficient for quantifying the magnitude of the macrophage response in the context of different experimental variables (e.g., therapeutic intervention or time post-injury/infection). The present study provides the first in-depth comparison of different techniques commonly used to quantify microglial/macrophage reactions in the pathological spinal cord. Individuals from the same and different laboratories applied techniques of digital image analysis (DIA), standard cell profile counting and a computer-assisted cell counting method with unbiased sampling to quantify macrophages in focal inflammatory lesions, disseminated lesions caused by autoimmune inflammation or at sites of spinal trauma. Our goal was to find a simple, rapid and sensitive method with minimal variability between trials and users. DIA was consistently the least variable and most time-efficient method for assessing the magnitude of macrophage responses across lesions and between users. When used to evaluate the efficacy of an anti-inflammatory treatment, DIA was 5-35 x faster than cell counting and was sensitive enough to detect group differences while eliminating inter-user variability. Since lesions are clearly defined and single profiles of microglia/macrophages are difficult to discern in most pathological specimens of brain or spinal cord, DIA offers significant advantages over other techniques for quantifying activated macrophages.

Abdominal Aortic Aneurysm Rupture Is Associated With Increased Medial Neovascularization and Overexpression of Proangiogenic Cytokines

Objective— Matrix metalloproteinase (MMP) activity has been linked to abdominal aortic aneurysm (AAA) rupture. Medial neovascularization (MNV), a histopathologic characteristic of AAAs, involves proteolytic degradation of extracellular matrix by MMPs to facilitate endothelial cell migration. The role of MNV in aneurysm rupture is unknown. This study investigated whether MNV is increased in aneurysm rupture.

Methods and Results— Biopsy samples from aneurysm rupture edge were compared with control biopsy samples from aneurysm wall at the level of rupture and from anterior sac in 12 ruptured AAAs. Further controls were obtained from anterior sac of 10 nonruptured AAAs. MNV, microvessel diameter, maturity index, and inflammatory infiltrate were quantified using morphometric analyses following immunohistochemistry. Expression of proangiogenic mediators was quantified using quantitative real-time-polymerase chain reaction. Compared with anterior sac and aneurysm wall at level of rupture, MNV was increased ( P <0.001) in rupture edge biopsy samples and consisted of smaller diameter ( P <0.001) and more immature microvessels ( P <0.001). mRNA expression of α v -integrin, vascular endothelial growth factor, vascular endothelial-cadherin, monocyte chemoattractant protein-1, and vimentin was increased ( P <0.05) in rupture edge biopsy samples.

Conclusions— This study demonstrated increased medial neovascularization and overexpression of proangiogenic cytokines at aneurysm rupture edge. Further investigations into whether this angiogenic response was a causative factor of aneurysm rupture are needed.

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.

The relationship between albuminuria, MCP-1/CCL2, and interstitial macrophages in chronic kidney disease

Glomerular-derived proteins may activate tubular cells to express the macrophage-directed chemokine monocyte chemoattractant protein-1 (MCP-1/CCL2). Macrophages at interstitial sites have a central role in directing renal scarring. We have prospectively assessed the relationship between albuminuria, urinary MCP-1/CCL2, interstitial macrophage infiltration, in situ damage, and clinical outcomes in a large group of patients with chronic kidney disease. We studied 215 patients and quantified albumin-creatinine ratio (ACR), urinary MCP-1/CCL2, interstitial macrophage numbers, and in situ damage. ACR correlated with urinary MCP-1/CCL2 (correlation 0.499; P<0.001), interstitial macrophage numbers (correlation 0.481; P<0.001), and index of chronic damage (correlation 0.363; P<0.001). Macrophage numbers closely correlated with in situ damage (correlation 0.755; P<0.001). By multivariate analysis ACR, urinary MCP-1/CCL2, and interstitial macrophage numbers were interdependent. By Kaplan-Meier survival analysis albuminuria, urinary MCP-1/CCL2, interstitial macrophages, and chronic damage predict the outcome. ACR, macrophage numbers, chronic damage, and creatinine independently predicted renal survival. The association of ACR with other variables was strongest in patients with less advanced disease states. There is a close association between albuminuria, urinary MCP-1/CCL2, and interstitial macrophage infiltration with in situ damage and clinical outcomes. These findings support the hypothesis that albuminuria triggers tubular MCP-1/CCL2 expression with subsequent macrophage infiltration. These processes may represent the dominant pathway for the progression of renal injury before the establishment of advanced renal scarring.

A software package to improve image quality and isolation of objects of interest for quantitative stereology studies of rat hepatocarcinogenesis

In the studies of quantitative stereology of rat hepatocarcinogenesis, we have used image analysis technology (automatic particle analysis) to obtain data such as liver tissue area, size and location of altered hepatic focal lesions (AHF), and nuclei counts. These data are then used for three-dimensional estimation of AHF occurrence and nuclear labeling index analysis. These are important parameters for quantitative studies of carcinogenesis, for screening and classifying carcinogens, and for risk estimation. To take such measurements, structures or cells of interest should be separated from the other components based on the difference of color and density. Common background problems seen on the captured sample image such as uneven light illumination or color shading can cause severe problems in the measurement. Two application programs (BK_Correction and Pixel_Separator) have been developed to solve these problems. With BK_Correction, common background problems such as incorrect color temperature setting, color shading, and uneven light illumination background, can be corrected. With Pixel_Separator different types of objects can be separated from each other in relation to their color, such as seen with different colors in immunohistochemically stained slides. The resultant images of such objects separated from other components are then ready for particle analysis. Objects that have the same darkness but different colors can be accurately differentiated in a grayscale image analysis system after application of these programs.

Fatty acids exacerbate tubulointerstitial injury in protein-overload proteinuria

The role of the albumin-carried fatty acids in the induction of tubulointerstitial injury was studied in protein-overload proteinuria. Rats were injected with fatty acid-carrying BSA [FA(+)BSA], fatty acid-depleted BSA [FA(-)BSA], or saline. Macrophage infiltration was measured by immunohistochemical staining, apoptotic cells were detected by in situ end labeling, and proliferating cells were identified by in situ hybridization for histone mRNA. Macrophage infiltration was significantly greater in the FA(+)BSA group than in the FA(-)BSA and saline groups. The infiltrate was largely restricted to the outer cortex. Apoptosis was greater in the FA(+)BSA group than in the FA(-)BSA and saline groups. Compared with the saline group, apoptosis was significantly increased in the FA(+)BSA group but not in the FA(-)BSA group. Cortical cells proliferated significantly more in the FA(+)BSA and FA(-)BSA groups than in the saline group. FA(+)BSA is therefore a more potent inducer of macrophage infiltration and cell death than FA(-)BSA. The fatty acids carried on albumin may be the chief instigators of tubulointerstitial injury in protein-overload proteinuria.

Association of intraluminal thrombus in abdominal aortic aneurysm with local hypoxia and wall weakening

PURPOSE

Our previous computer models suggested that intraluminal thrombus (ILT) within an abdominal aortic aneurysm (AAA) attenuates oxygen diffusion to the AAA wall, possibly causing localized hypoxia and contributing to wall weakening. The purpose of this work was to investigate this possibility.

METHODS

In one arm of this study, patients with AAA were placed in one of two groups: (1) those with an ILT of 4-mm or greater thickness on the anterior surface or (2) those with little (< 4 mm) or no ILT at this site. During surgical resection but before aortic cross-clamping, a needle-type polarographic partial pressure of oxygen (PO2) electrode was inserted into the wall of the exposed AAA, and the PO2 was measured. The probe was advanced, and measurements were made midway through the thrombus and in the lumen. Mural and mid-ILT PO2 measurements were normalized by the intraluminal PO2 measurement to account for patient variability. In the second arm of this study, two AAA wall specimens were obtained from two different sites of the same aneurysm at the time of surgical resection: group I specimens had thick adherent ILT, and group II specimens had thinner or no adherent ILT. Nonaneurysmal tissue was also obtained from the infrarenal aorta of organ donors. Specimens were subjected to histologic, immunohistochemical, and tensile strength analyses to provide data on degree of inflammation (% area inflammatory cells), neovascularization (number of capillaries per high-power field), and tensile strength (peak attainable load). Additional specimens were subjected to Western blotting and immunohistochemistry for qualitative evaluation of expression of the cellular hypoxia marker oxygen-regulated protein.

RESULTS

The PO2 measured within the AAA wall in group I (n = 4) and group II (n = 7) patients was 18% +/- 9% luminal value versus 60% +/- 6% (mean +/- SEM; P <.01). The normalized PO2 within the ILT of group I patients was 39% +/- 10% (P =.08 with respect to the group I wall value). Group I tissue specimens showed greater inflammation (P <.05) compared with both group II specimens and nonaneurysmal tissue: 2.9% +/- 0.6% area (n = 7) versus 1.7% +/- 0.3% area (n = 7) versus 0.2% +/- 0.1% area (n = 3), respectively. We found similar differences for neovascularization (number of vessels/high-power field), but only group I versus control was significantly different (P <.05): 16.9 +/- 1.6 (n = 7) vs 13.0 +/- 2.3 (n = 7) vs 8.7 +/- 2.0 (n = 3), respectively. Both Western blotting and immunohistochemistry results suggest that oxygen-regulated protein is more abundantly expressed in group I versus group II specimens. Tensile strength of group I specimens was significantly less (P <.05) than that for group II specimens: 138 +/- 19 N/cm2 (n = 7) versus 216 +/- 34 N/cm2 (n = 7), respectively.

CONCLUSION

Our results suggest that localized hypoxia occurs in regions of thicker ILT in AAA. This may lead to increased, localized mural neovascularization and inflammation, as well as regional wall weakening. We conclude that ILT may play an important role in the pathology and natural history of AAA.

Nuclear-labeling index analysis (NLIA), a software package used to perform accurate automation of cell nuclear-labeling index analysis on immunohistochemically stained rat liver samples

The nuclear labeling index (labeled nuclei/100 nuclei) and the apoptotic index (apoptotic cells/100 cells) are important parameters of cell growth and death. Automatic counting of labeled nuclei is desirable since manual counting is tedious, time-consuming, and with a greater potential for inaccuracies. A nuclear-labeling index analysis (NLIA) software package was developed in this laboratory to perform the counting process automatically and accurately. This software package consists of an application program NLIA and a set of macros for obtaining nuclear data that is used in Scion Image. It is designed to work cooperatively with Scion Image, Adobe Photoshop, and Microsoft Office. NLIA has two basic functions: building nuclear data files and analyzing nuclear data. A color image captured from an immunohistochemically stained or autoradiographic sample is loaded into NLIA. Nuclear data can be entered into the program manually, automatically, or in combination. In the manual data entering mode, NLIA acts as an object-counting tool, while in the automatic mode it acts as a data picker: picking up the data generated by Scion Image into memory. A method to enter nuclear data (both labeled nuclei and unlabeled nuclei) in the automatic mode is described. The color image is processed in Adobe Photoshop, where the interested color ranges are selected and separated. These are then analyzed in Scion Image with the help of the macros for obtaining nuclear data. Since the advanced particle analysis function is used, the counting process is automatic and rapid. Data from thousands of nuclei can be obtained within seconds. To ensure the accuracy of the analysis, a nuclear data checking and edit feature is employed in NLIA: results of computer-generated counting can be compared with the original color image by overlaying the plot of counting results onto the original color image. In this way any computer counting mistakes can be easily discovered and corrected by the operator. Corrected nuclear data (including nuclear size, location, shape) are then stored in data files. These data files can be used in NLIA to obtain cell density and nuclear labeling indices. Because criteria for obtaining nuclear data (truncation diameter, shape factor) can be set by the operator in NLIA, nuclear size distribution and shape variation can be analyzed. This method provides a fast and accurate way to determine cell nuclear-labeling indices. Currently, Scion Image is a freeware on the internet, and NLIA software package is available from our lab home page. Methods presented here expand the Scion Image ability to analyze color images by using color separation techniques in a commercial graphic application. The instrumentation required can be relatively inexpensive, and the methods described may be useful in studies of cell kinetics, lesion growth, and tumor therapy.

Protection of alpha(3) integrin-mediated podocyte shape by superoxide dismutase in the puromycin aminonucleoside nephrosis rat

Because reactive oxygen species (ROS) are involved in the development of puromycin aminonucleoside nephrosis (PAN), we examined whether superoxide dismutase (SOD) could ameliorate this condition. Phosphatidyl choline-bound SOD (PC-SOD) has higher affinity for the cell membrane than recombinant human SOD (rhSOD). In this study, PC-SOD had a longer half-life in the circulation and also higher affinity to renal fractions (glomerulus, brush border, and tubulus) than rhSOD. PAN was induced in rats with single injections of puromycin aminonucleoside. Rats were divided into four groups: group P, PAN rats without treatment; group PC-T and group rh-T, PAN rats treated with 30,000 U/kg PC-SOD and rhSOD, respectively; and group C, normal controls. The effect of PC-SOD versus rhSOD on PAN was evaluated by morphological podocyte changes (podocyte density along the GBM) and alpha(3) integrin expression at days 4 and 10. Proteinuria was measured over time until day 14. Distribution and quantitation of alpha(3) integrin were studied by confocal laser scan microscopy. On day 4, glomerular ROS was measured by chemiluminescence without stimulation. PC-SOD decreased proteinuria to the control level, but rhSOD only decreased proteinuria by 31%. PC-SOD significantly improved podocyte density (P < 0.05 versus group P). Total alpha(3) integrin expression decreased in the P and rh-T groups at day 4 and then had recovered by day 10, but the polarity of the site of expression did not recover. PC-T preserved both the amount and polarity of integrin expression on days 4 and 10. PC-SOD significantly suppressed ROS generation in PAN (P < 0.05). These findings suggest that alpha(3) integrin regulates glomerular permeability by maintaining podocyte shape and adhesion, which is disrupted by ROS overproduction.

Role of glomerular ultrafiltration of growth factors in progressive interstitial fibrosis in diabetic nephropathy

BACKGROUND

The present in vivo and in vivo experiments were performed to test the hypothesis that in rats with glomerular proteinuria, the bioactive growth factors transforming growth factor-beta (TGF-beta) and hepatocyte growth factor (HGF) are ultrafiltered into tubular fluid, can interact with respective receptors in apical tubular cell membranes, increase the expression and basolateral secretion of C-C-chemokines, which interact with cells in the renal interstitium and indirectly cause myofibroblasts to increase the expression of extracellular matrix proteins.

METHODS

HGF and TGF-beta were measured by Western blot and bioassay in glomerular ultrafiltrate that was collected by nephron micropuncture from rats with diabetic nephropathy and control rats. Proximal tubular and collecting duct cells were incubated with diluted proximal tubular fluid or recombinant human HGF (rhHGF) or rhTGF-beta and expression of C-C-chemokines was measured by RT-PCR and ELISA. Interactions of tubular cell chemokines with macrophages and indirectly with myofibroblasts were also examined using cell culture models.

RESULTS

In rats with glomerular proteinuria due to diabetic nephropathy mature, bioactive HGF as well as active and latent TGF-beta were detected in early proximal tubular fluid. Specific HGF- and TGF-beta type II receptors were expressed in apical tubular membranes more in diabetic compared to control rats. Incubation of cultured mouse proximal tubular cells (mPTC) or medullary collecting duct cells (mIMCD-3) with diabetic rat proximal tubular fluid increased MCP-1 and RANTES mRNA levels as well as secreted peptide up to threefold. In contrast, high glucose (450 mg/dL), bovine serum albumin (BSA) or rat albumin (each at 100 micrograms/mL) or 10 nmol/L insulin-like growth factor-I (IGF-I; which was also present in glomerular ultrafiltrate in rats with diabetic nephropathy) did not affect expression of these chemokines. Recombinant human TGF-beta as well as rhHGF each increased MCP-1 and RANTES mRNA as well as peptide levels several-fold. In cultured macrophages MCP-1 raised the secretion of TGF-beta, which in turn increased the expression of collagen type I and III as well as fibronectin in renal interstitial myofibroblasts about 2.5 to 4-fold.

CONCLUSIONS

Proteinuria-induced progressive renal interstitial fibrosis may be caused by glomerular ultrafiltration of high molecular weight bioactive growth factors, HGF and TGF-beta, which "activate" tubular cells through apical membranes. These apical signals are translated into basolateral events that are recognized by cells in the interstitium, such as the basolateral secretion of the C-C-chemokines MCP-1 and RANTES, which may (via macrophages) stimulate interstitial myofibroblasts, and thus lead to accumulation of extracellular matrix proteins and progressive interstitial fibrosis.

Secretion of chemokines and cytokines by human tubular epithelial cells in response to proteins

BACKGROUND

Chronic interstitial scarring contributes to the progression of renal failure in glomerular disease but its cause is unknown. The development of proteinuria could stimulate tubular cells to release cytokines, chemoattractants and matrix proteins into the interstitium, thus contributing to interstitial disease.

METHODS

Polarized human tubular epithelial cells were grown on permeable supports and exposed to serum proteins on their apical surface. The release of tumour necrosis factor alpha(TNFalpha), platelet derived growth factor (PDGF) and monocyte chemoattractant protein-1 (MCP-1) by the cells was measured using immunoassays.

RESULTS

Under control conditions there was polarized release of PDGF-AB with predominant basolateral secretion (basolateral to apical ratio 4.7+/-1.6). MCP-1 release was less polarized (ratio 1. 7+/-0.5). TNFalpha was not detected. Exposure of the cells to normal human serum proteins on their apical side increased basolateral release of PDGF-AB (1.7+/-0.4 fold) and MCP-1 (2.4+/-0.2 fold). Fractionation of the serum showed that this effect on human tubular epithelial cells was reproduced by a fraction of molecular weight 40-100 kDa. The predominant proteins in this fraction were albumin and transferrin but these purified proteins alone did not alter secretion of PDGF-AB or MCP-1.

CONCLUSION

This data demonstrates that human tubular cells exposed to proteins, which would be filtered in glomerular disease, produce inflammatory mediators with the potential to stimulate inflammation and scarring in the interstitium of the kidney.

Induction of heat shock protein 70 in the rat brain following intracisternal infusion of autologous blood: evaluation of acute neuronal damage

OBJECT

Investigation into a potential treatment for the acute period following onset of spontaneous subarachnoid hemorrhage (SAH) is hampered by the lack of a standardized experimental model. For that purpose the authors elaborated on a small-animal model in which computer-controlled intracisternal blood infusion is used and investigated whether this model can reliably reproduce acute neuronal injury after SAH.

METHODS

Whole autologous blood (blood-infused group) or isotonic saline (control group) was infused into the cisterna magna or olfactory cistern of rats. The infusions decreased exponentially during a 5-minute period. Throughout the infusion period, intracranial pressure (ICP) was monitored. Neuronal injury was quantified by observing tissue immunoreactivity to a 70-kD heat shock protein (HSP70) and comparing this with the tissue's reaction to hematoxylin and eosin staining. On Days 1, 3, and 5, the CA1, CA3, and dentate gyrus regions of the hippocampus were analyzed, respectively. During saline infusion ICP increased within seconds beyond 80 mm Hg and afterward decreased in accordance with the infusion rate. During the infusion of blood, the same initial pressure peak was found, but the ICP remained increased beyond this pressure level throughout the 5-minute infusion period. The HSP70 immunoreactivity in the saline-infused group was found only on Day 1 in the CA1 region and the dentate gyrus, but not in the CA3. After injection of whole blood, there was HSP70-positive staining in the CA1, CA3, and dentate gyrus regions throughout the observation period.

CONCLUSIONS

The controlled cisternal infusion of blood caused neuronal injury that resembled that of previous experimental models that produce SAH by rupture of intracranial vessels with endovascular techniques. Unlike those experiments, the intracisternal infusion technique presented by the authors provides more standardized bleeding with regard to ICP, the volume of subarachnoid blood, and the extent of acute cellular injury.

Computerized histomorphometric assessment of protocol renal transplant biopsy specimens for surrogate markers of chronic rejection

BACKGROUND

Chronic transplant rejection has emerged as the commonest cause of long-term renal allograft failure, and early identification of those grafts at risk could allow the targeting of specific therapies aimed at delaying this process. This study explores the usefulness of quantitative immunohistochemistry in defining biopsy-based surrogate markers of allograft damage.

METHODS

A consecutive series of 52 renal transplant recipients immunosuppressed with cyclosporine were studied. Needle core transplant biopsies were performed at 1, 3, and 6 months postoperatively. Immunostaining for collagen III, and smooth muscle actin, tenascin, and infiltrating leukocytes was performed using an indirect immunoperoxidase technique. The interstitial area stained (%) was measured using a semiautomatic image analysis system. The results were related to glomerular filtration rates (GFR) measured at 6, 12, and 24 months after transplantation using rank correlation coefficients.

RESULTS

The area fraction of immunostained collagen III correlated with 6-month GFR (r=-0.42, P=0.005) and was predictive of 12-month GFR (r=-0.32, P=0.03). An area fraction of immunostained collagen III of >40% at 6 months was associated with a significantly lower GFR at 24 months, compared with a percentage area of < or =40% (31+/-4 versus 45+/-4 ml/min/1.73 m2, P=0.01). Furthermore, a collagen III of >40% at 6 months identified patients who were at risk of progressive deterioration in graft function.

CONCLUSIONS

Grafts with poorer long-term function can be predicted using 6-month protocol biopsy specimens immunostained for collagen III. This should prove to be a useful ad interim surrogate marker of allograft damage in studies addressing the effects of new immunosuppressive agents on the development of chronic rejection.

Clinical rejection is distinguished from subclinical rejection by increased infiltration by a population of activated macrophages

It has been reported previously that one-third of protocol renal biopsies in asymptomatic, biochemically stable renal transplant recipients in the first 6 mo show unsuspected subclinical graft rejection (both infiltrate and tubulitis) and that subclinical rejection is a risk factor for chronic renal dysfunction. This study was performed to determine whether differences in phenotype or activation status of graft-infiltrating cells underlie these different manifestations of acute rejection. Biopsies with normal histology (n = 10), subclinical rejection (n = 13), and clinical rejection (n = 9) were studied using immunohistochemistry and computerized image analysis. Subclinical and clinical rejections had similar histologic Banff scores. Univariate analysis showed a trend for a higher infiltration with CD8+ (P = 0.053) and CD68+(P = 0.06) cells in clinical rejection. Of the activation markers studied (CD25, perforin, tumor necrosis factor-alpha), only allograft inflammatory factor-1+-activated macrophages were significantly (P = 0.014) increased in the infiltrate of clinical rejection biopsies. These data suggest that activated macrophages or their products are responsible for acute renal dysfunction associated with clinical rejection episodes.

Artificial neural network-aided image analysis system for cell counting

BACKGROUND

In histological preparations containing debris and synthetic materials, it is difficult to automate cell counting using standard image analysis tools, i.e., systems that rely on boundary contours, histogram thresholding, etc. In an attempt to mimic manual cell recognition, an automated cell counter was constructed using a combination of artificial intelligence and standard image analysis methods.

METHODS

Artificial neural network (ANN) methods were applied on digitized microscopy fields without pre-ANN feature extraction. A three-layer feed-forward network with extensive weight sharing in the first hidden layer was employed and trained on 1,830 examples using the error back-propagation algorithm on a Power Macintosh 7300/180 desktop computer. The optimal number of hidden neurons was determined and the trained system was validated by comparison with blinded human counts. System performance at 50x and lO0x magnification was evaluated.

RESULTS

The correlation index at 100x magnification neared person-to-person variability, while 50x magnification was not useful. The system was approximately six times faster than an experienced human.

CONCLUSIONS

ANN-based automated cell counting in noisy histological preparations is feasible. Consistent histology and computer power are crucial for system performance. The system provides several benefits, such as speed of analysis and consistency, and frees up personnel for other tasks.

Proteinuria induces tubular cell turnover: A potential mechanism for tubular atrophy

BACKGROUND

Proteinuria and tubular atrophy have both been closely linked with progressive renal failure. We hypothesized that apoptosis may be induced by tubular cell exposure to heavy proteinuria, potentially leading to tubular atrophy. Apoptosis was studied in a rat model of "pure" proteinuria, which does not induce renal impairment, namely protein-overload proteinuria.

METHODS

Adult female Lewis rats underwent intraperitoneal injection of 2 g of bovine serum albumin (BSA, N = 16) or sham saline injections (controls, N = 8) daily for seven days. Apoptosis was assessed at day 7 in tissue sections using in situ end labeling (ISEL) and electron microscopy. ISEL-positive nuclei (apoptotic particles) were counted in blinded fashion using image analysis with NIH Image. Cell proliferation was assessed by detection of mRNA for histone by in situ hybridization, followed by counting of positive cells using NIH Image.

RESULTS

Animals injected with saline showed very low levels of apoptosis on image analysis. BSA-injected rats had heavy proteinuria and showed both cortical and medullary apoptosis on ISEL. This was predominantly seen in the tubules and, to a lesser extent, in the interstitial compartment. Overall, the animals injected with BSA showed a significant 30-fold increase in the number of cortical apoptotic particles. Electron microscopy of tubular cells in a BSA-injected animal showed a progression of ultrastructural changes consistent with tubular cell apoptosis. The BSA-injected animals also displayed a significant increase in proximal tubular cell proliferation. This increased proliferation was less marked than the degree of apoptosis.

CONCLUSION

Protein-overload proteinuria in rats induces tubular cell apoptosis. This effect is only partially balanced by proliferation and potentially provides a direct mechanism whereby heavy proteinuria can induce tubular atrophy and progressive renal failure.

Morphometric analysis of lymphatic and blood vessels in human chronic viral liver diseases

The purpose of this study was to elucidate the morphometric changes occurring in hepatic lymphatics in human chronic viral liver diseases and to investigate the relationship between liver fibrosis, liver inflammation, and these changes. The lymphatic vessels were stained intensely by enzyme histochemistry for 5'-nucleotidase, whereas blood vessels stained well for alkaline phosphatase. We performed a morphometric analysis to estimate the number of lymphatic and blood vessels and their areas, using computer graphics software (NIH Image). Both the number of lymphatics in the specimens and their areas were increased according to the degree of liver fibrosis, but neither showed any relationship with the degree of activity of hepatitis. Neither the number nor the areas of the blood vessels showed any obvious relationship with the degree of fibrosis or the activity of chronic hepatitis. Correlation between clinical and laboratory data and the sizes and number of the lymphatics supported these morphological data. Our results clarified that the sizes and number of lymphatics are related to the stage of fibrosis in chronic viral liver diseases. This is thought to be due to increased lymph production, which is caused by the disturbance of the microcirculation associated with liver fibrosis.