Proteinuria in membranous lupus nephritis: the pathology is in the podocyte.

BACKGROUND: Patients with membranous lupus glomerulonephritis (MLN) can present with a broad range of urine protein excretion. The glomerular lesion underlying this functional abnormality has been presumed to be immune complexes which aggregate in the subepithelial area. However, the amount of proteinuria often fails to correlate with the quantity of immune deposits demonstrable on fluorescent and electron microscopy. The purpose of this study is to determine the correlation of alterations of the morphologic components of the glomerular capillary wall with the amount of proteinuria in MLN. DESIGN: We conducted a retrospective clinicopathologic study of patients with lupus nephritis (n=236). In those with pure MLN and proteinuria (n=20), the degree of immune aggregates in the capillary walls and mesangium was detailed using fluorescent and electron microscopy. The degree of foot process effacement (FPE) was detailed using electron microscopy. RESULT: Eleven patients had nephrotic range proteinuria (≥ 3 g proteinuria/g creatinine (g/g)) and nine demonstrated subnephrotic range proteinuria (<3 g/g) (nephrotic, 8.3 ± 5.1 g/g vs. subnephrotic, 1.63 ± 0.83 g/g, p=0.001). All patients demonstrated peripheral capillary wall granular deposits by immunofluorescence microscopy, and the degree of moderate (2+) to severe (3+) deposition was not different (nephrotic, 8/11, 73% vs. subnephrotic, 5/9, 55%, p=0.64). By electron microscopy, FPE (88.6 ± 11% vs. 48.3 ± 36.1%, p=0.002) and foot process width (1798 ± 736 nm vs. 1000 ± 333 nm, p=0.008) was greater in the nephrotic group compared with subnephrotic. There were no other histopathologic differences between the groups. CONCLUSIONS: In patients with MLN, a distinguishing morphologic feature of those with nephrotic range proteinuria is diffuse visceral epithelial cell FPE. We conclude that nephrotic range proteinuria in patients with MLN may be a manifestation of concomitant glomerular visceral epithelial cell dysfunction.

Reactive oxygen species mediate high glucose-induced heparanase-1 production and heparan sulphate proteoglycan degradation in human and rat endothelial cells: a potential role in the pathogenesis of atherosclerosis.

AIMS/HYPOTHESIS: The content of heparan sulphate is reduced in the endothelium under hyperglycaemic conditions and may contribute to the pathogenesis of atherosclerosis. Heparanase-1 (HPR1) specifically degrades heparan sulphate proteoglycans. We therefore sought to determine whether: (1) heparan sulphate reduction in endothelial cells is due to increased HPR1 production through increased reactive oxygen species (ROS) production; and (2) HPR1 production is increased in vivo in endothelial cells under hyperglycaemic and/or atherosclerotic conditions. METHODS: HPR1 mRNA and protein levels in endothelial cells were analysed by RT-PCR and Western blot or HPR1 enzymatic activity assay, respectively. Cell surface heparan sulphate levels were analysed by FACS. HPR1 in the artery from control rats and a rat model of diabetes, and from patients under hyperglycaemic and/or atherosclerotic conditions was immunohistochemically examined. RESULTS: High-glucose-induced HPR1 production and heparan sulphate degradation in three human endothelial cell lines, both of which were blocked by ROS scavengers, glutathione and N-acetylcysteine. Exogenous H(2)O(2) induced HPR1 production, subsequently leading to decreased cell surface heparan sulphate levels. HPR1 content was significantly increased in endothelial cells in the arterial walls of a rat model of diabetes. Clinical studies revealed that HPR1 production was increased in endothelial cells under hyperglycaemic conditions, and in endothelial cells and macrophages in atherosclerotic lesions. CONCLUSIONS/INTERPRETATION: Hyperglycaemia induces HPR1 production and heparan sulphate degradation in endothelial cells through ROS. HPR1 production is increased in endothelial cells from a rat model of diabetes, and in macrophages in the atherosclerotic lesions of diabetic and non-diabetic patients. Increased HPR1 production may contribute to the pathogenesis and progression of atherosclerosis.

The prognosis of severe lupus nephritis based on the Modification of Diet in Renal Disease (MDRD) study estimated glomerular filtration rate.

The level of renal function at biopsy is predictive of outcome in patients with severe lupus nephritis (SLN). While renal function has been based on serum creatinine (SCr) alone, measuring the estimated glomerular filtration rate (eGFR) utilizing the Modification of Diet in Renal Disease (MDRD) Study equation has been found to be more accurate. The MDRD eGFR (ml/min/1.73 m(2)) at biopsy was calculated in 86 patients with SLN and patients were categorized based on eGFR: ≥60 (33 pts), 59-30 (33 pts) and <30 (20 pts). An eGFR was <60 in 18% of patients with a normal SCr. After 120 ± 65 months of follow-up, attainment of a complete remission (76% versus 30% versus 10%, p < 0.0001) and patient survival without end-stage renal disease (ESRD; 10 year survival: 85% versus 45% versus 14%, p < 0.0001 overall) was highest in patients with an eGFR ≥60 and lowest in those with an eGFR <30. The long-term prognosis for patients with severe lupus nephritis and an eGFR ≥60 was extremely good. Since the prognosis for patients with an eGFR <60 was poor even in those patients with a normal SCr, renal function is more accurately determined by the MDRD eGFR.

Evidence of concurrent immunopathological mechanisms determining the pathology of severe lupus nephritis.

The purpose of this study is to determine whether two distinct histopathological-immunopathological lesions, which have been reported in severe lupus nephritis, diffuse global glomerulonephritis (GN) (WHO IV) and a segmental and necrotising GN (WHO III) can be reported to coexist in a single patient. We examine the evidence of coexistence of these disparate lesions and the prognostic significance in a group of patients with severe lupus nephritis who have been subjected to a common therapeutic regimen by protocol. The simple, reproducible parameter indicating the presence of glomerular capillary necrosis was the presence of crescents. We, therefore, reviewed 39 renal biopsies with diffuse global lupus GN (WHO IV) (Churg, J, Sobin, LH. Lupus nephritis. Renal disease, classification and atlas of glomerular diseases. New York: Igaku-Shoin; 1982. p. 127-149). and used crescents as a surrogate for glomerular necrosis. Peripheral capillary immune deposits were less prominent in WHO IV with crescents compared with those without and resembled the reduced immune deposits seen in severe segmental GN (WHO III >or= 50%). Patients with WHO IV with crescents had decreased survival without end-stage renal disease (P = 0.02), fewer remissions (P = 0.04) and more adverse outcomes (12/22 vs 3/17) (P = 0.02) than those without crescents, and this was similar to patients with WHO III >or=50%. We conclude that, on the basis of immunological and morphological features, WHO IV with crescents appears to be the result of two distinct pathogenetic mechanisms. We propose that diffuse global lupus GN, associated with crescents, is best described as WHO class IV + WHO class III.

Heparanase induces a differential loss of heparan sulphate domains in overt diabetic nephropathy.

AIMS/HYPOTHESIS: Recent studies suggest that loss of heparan sulphate in the glomerular basement membrane (GBM) of the kidney with diabetic nephropathy is due to the increased production of heparanase, a heparan sulphate-degrading endoglycosidase. Our present study addresses whether heparan sulphate with different modifications is differentially reduced in the GBM and whether heparanase selectively cleaves heparan sulphate with different domain specificities. METHODS: The heparan sulphate content of renal biopsies (14 diabetic nephropathy, five normal) were analysed by immunofluorescence staining with four anti-heparan sulphate antibodies: JM403, a monoclonal antibody (mAb) recognising N-unsubstituted glucosamine residues; two phage display-derived single chain antibodies HS4C3 and EW3D10, defining sulphated heparan sulphate domains; and anti-K5 antibody, an mAb recognising unmodified heparan sulphate domains. RESULTS: We found that modified heparan sulphate domains (JM403, HS4C3 and EW3D10), but not unmodified domains (anti-K5) and agrin core protein were reduced in the GBM of kidneys from patients with diabetic nephropathy, compared with controls. Glomerular heparanase levels were increased in diabetic nephropathy kidneys and inversely correlated with the amounts of modified heparan sulphate domains. Increased heparanase production and loss of JM403 staining in the GBM correlated with the severity of proteinuria. Loss of modified heparan sulphate in the GBM as a result of degradation by heparanase was confirmed by heparan sulphate staining of heparanase-treated normal kidney biopsy specimens. CONCLUSIONS/INTERPRETATION: Our data suggest that loss of modified heparan sulphate in the GBM is mediated by an increased heparanase presence and may play a role in the pathogenesis of diabetes-induced proteinuria.

Association of glomerular podocytopathy and nephrotic proteinuria in mesangial lupus nephritis.

We investigated a series of patients with systemic lupus erythematosus (SLE), who had sparse subepithelial and mesangial immune deposits. Our goal was to determine structure: function correlation. We examined whether proteinuria correlated with either capillary wall immune aggregate formation or abnormal podocyte morphology. Renal biopsies from patients with sparse (two or fewer subepithelial or intramembranous electron dense deposits per glomerular capillary loop) immune deposits and podocyte effacement were studied. Patients fulfilled criteria for the diagnosis of SLE. Cases were excluded if the biopsy showed endocapillary proliferation or necrosis. Eighteen biopsies were studied, five from patients with nephrotic range proteinuria (> or =3 g/day) and 13 from patients with non-nephrotic proteinuria (<3 g/day). The five nephrotic patients had a mean foot process effacement of 48% +/- 39% (range 10-100%). Thirteen non-nephrotic patients had a mean foot process effacement of 11.7% +/- 8% (range 0-20%). The only distinguishing morphologic finding associated with nephrotic range proteinuria was diffuse foot process effacement. No correlation between subepithelial deposits and proteinuria was observed. There were no other histologic differences between the nephrotic and non-nephrotic patients. Among these patients, the nephrotic syndrome appears best correlated with podocytopathy rather than subepithelial electron dense deposits, mesangial deposits, or mesangial hypercellularity.

Pathology of lupus nephritis.

The glomerular pathology of lupus nephritis is the result of diverse immune insults which are probably of independent pathogenetic origins. Although lupus nephritis is looked upon as a classic example of immune complex-induced microvascular injury resulting from circulating DNA double stranded polynucleotide antigens/anti-DNA antibody complexes, other mechanisms, including in situ reactivity of free antibody with fixed antigens and the role of sensitized T-cells, are probably an important part of the picture. This complexity makes categorization of glomerular pathology into a clinically relevant classification an important goal so that our experiences can be reliably compared. This review describes the various glomerular lesions commonly encountered in lupus nephritis and, based upon data derived from experimental models, emphasizes the importance of understanding the clinical relevance of the reported morphology. We point out that the severity of glomerular damage is not merely the accrued result of immune complex induced injury to individual capillaries, but involves capillary necrosis and thrombosis, neither of which may have anything to do with immune complexes or immune aggregates. In fact, the segmental lesions of glomerular capillary necrosis and thrombosis may have a great deal to do with the response to therapy and the ultimate outcome of the patient. While discrete morphologic lesions such as mesangiopathy, acute inflammation, necrosis, thrombosis, epimembranous lesions and podocytopathy are readily described, it is important to note that any given case can represent any combination of these insults. In this context, the new proposed International Society of Nephrology Classification is presented and its strengths and weaknesses discussed.

Zoonotic protozoa in the marine environment: a threat to aquatic mammals and public health.

This collection of abstracts provides an account of four presentations at the 19th International Conference of the World Association for the Advancement of Veterinary Parasitology (WAAVP)(held in New Orleans, LA, USA from 10­14 August 2003) in a symposium session on zoonotic protozoan parasites found in the marine environment and chaired by Ronald Fayer and David Lindsay.The focus was on three genera of parasites of veterinary and public health concern­Toxoplasma,Giardia, and Cryptosporidium with emphasis on their epidemiology in the marine environment.

Age-related differences in Na+-dependent Ca2+ accumulation in rabbit hearts exposed to hypoxia and acidification.

In this study, we test the hypothesis that in newborn hearts (as in adults) hypoxia and acidification stimulate increased Na(+) uptake, in part via pH-regulatory Na(+)/H(+) exchange. Resulting increases in intracellular Na(+) (Na(i)) alter the force driving the Na(+)/Ca(2+) exchanger and lead to increased intracellular Ca(2+). NMR spectroscopy measured Na(i) and cytosolic Ca(2+) concentration ([Ca(2+)](i)) and pH (pH(i)) in isolated, Langendorff-perfused 4- to 7-day-old rabbit hearts. After Na(+)/K(+) ATPase inhibition, hypoxic hearts gained Na(+), whereas normoxic controls did not [19 +/- 3.4 to 139 +/- 14.6 vs. 22 +/- 1.9 to 22 +/- 2.5 (SE) meq/kg dry wt, respectively]. In normoxic hearts acidified using the NH(4)Cl prepulse, pH(i) fell rapidly and recovered, whereas Na(i) rose from 31 +/- 18.2 to 117.7 +/- 20.5 meq/kg dry wt. Both protocols caused increases in [Ca](i); however, [Ca](i) increased less in newborn hearts than in adults (P < 0.05). Increases in Na(i) and [Ca](i) were inhibited by the Na(+)/H(+) exchange inhibitor methylisobutylamiloride (MIA, 40 microM; P < 0.05), as well as by increasing perfusate osmolarity (+30 mosM) immediately before and during hypoxia (P < 0.05). The data support the hypothesis that in newborn hearts, like adults, increases in Na(i) and [Ca](i) during hypoxia and after normoxic acidification are in large part the result of increased uptake via Na(+)/H(+) and Na(+)/Ca(2+) exchange, respectively. However, for similar hypoxia and acidification protocols, this increase in [Ca](i) is less in newborn than adult hearts.

Contamination of Atlantic coast commercial shellfish with Cryptosporidium.

Shellfish (oysters and/or clams) were obtained from 37 commercial harvesting sites in 13 Atlantic coast states from Maine to Florida and one site in New Brunswick, Canada. Gill washings from each of 25 shellfish at each site were examined by immunofluorescence microscopy (IFA) for oocysts of Cryptosporidium. Gill washings from another 25 shellfish at each site were grouped into five pools of five shellfish each. DNA from each pool was utilized for PCR and genotyping. Oocysts were found in 3.7% of 925 oysters and clams examined by IFA in shellfish from New Brunswick and 11 of 13 states. Cryptosporidium DNA was detected by PCR in 35.2% of 185 pools. Cryptosporidium parvum genotypes 1 and 2, and Cryptosporidium meleagridis,all of which have been identified in infected humans, were identified at 37.8% of the sites. Gill washings from every site were tested for the presence of infectious oocysts by biological assay in neonatal BALB/c mice but no mice were found infected, suggesting that either the oocysts were no longer infectious or infections in mice were below the level of detection. Collectively, these findings indicate that Cryptosporidium species, indicative of pollution from human and animal feces and potentially infectious for humans, were found in commercial shellfish from 64.9% of sites examined along the Atlantic coast by either microscopy or molecular testing. Previous reports link periods of high rainfall with the elevated numbers of pathogen contaminated shellfish. Because shellfish in the present study were examined during a period of exceptionally low precipitation, the data are thought to underestimate the number of Cryptosporidium contaminated shellfish likely to be found during periods of normal or above normal precipitation.

Temporal variability of Cryptosporidium in the Chesapeake Bay.

Although Cryptosporidium has been found worldwide in molluscan shellfish from waters contaminated with human and animal feces, little or no related environmental data have been obtained. In the present study, oysters ( Crassostrea virginica) were collected eight times over 3 years from seven sites in the Chesapeake Bay or its tributaries, with accompanying data on water temperature, salinity, rainfall, and streamflow. Oyster gill washings were examined by immunofluorescence microscopy for Cryptosporidium oocysts. Of 1,590 oysters collected, 19.6% had detectable oocysts. Of 53 collections, oocysts were detected 81% of the time. The time when the greatest percentage of oysters at most sites had detectable oocysts coincided with the time of greatest weekly and monthly rainfall, greatest streamflow into the Bay, and lowest water temperatures. In 28% of 53 collections, C. parvum genotypes 1 and 2 and C. baileyi were identified by PCR and gene sequencing. Oocyst infectivity was confirmed from 37.5% of 40 collections by initiating C. parvum genotype 2 infections in mice.

A clinical trial in type 2 diabetic nephropathy.

A prospective, randomized, three-armed, double-blind, placebo-controlled clinical trial has been completed in 210 sites worldwide to determine whether the angiotensin II receptor blocker irbesartan or the calcium channel blocker amlodipine has a renoprotective effect in patients with overt type 2 diabetic nephropathy. A total of 1,715 subjects randomized during a 3-year period were followed a minimum of 2 years. The goal for all treatment groups was to achieve equivalent blood pressure control, with the blinded study drug (irbesartan, amlodipine, or placebo) as primary therapy with additional antihypertensive drugs, excluding angiotensin-converting enzyme inhibitors, calcium antagonists, and angiotensin II receptor antagonists, to achieve seated systolic blood pressure less than 135 mm Hg and diastolic blood pressure less than 85 mm Hg. The primary outcome was the combined endpoint of time to doubling of entry serum creatinine, end-stage renal disease, or death. Secondary outcomes included fatal and nonfatal cardiovascular events. A Clinical Management Committee monitored the conduct of the study. An Outcome Confirmation Committee classified all study outcome events in blinded fashion. An external Data Safety Monitoring Committee monitored unblinded data for interim safety and efficacy analyses of the study. Eligibility criteria included informed consent, age 30 to 70 years, adult-onset diabetes, hypertension, urine protein excretion greater than 900 mg/24 hours, and serum creatinine values of 90 to 265 micromol/L in women and 110 to 265 micromol/L in men. Baseline characteristics were age, 59 +/- 8 years; body mass index, 31 +/- 7 kg/m(2); 67% male; 73% white, 14% black, and 13% other; duration of diabetes, 15 +/- 9 years; retinopathy, 66%; neuropathy, 48%; congestive heart failure, 7.5%; screening seated systolic blood pressure, 156 +/- 18 mm Hg, and diastolic blood pressure, 85 +/- 11 mm Hg; urine protein excretion, 4.0 +/- 3.5 g/24 hours; serum creatinine, 150 +/- 53 micromol/L; serum potassium, 4.6 +/- 0.5 mEq/L; total cholesterol, 229 +/- 58 mg/dL; and hemoglobin A(1c), 8.1 +/- 1.7%. This large-scale international trial should help define the clinical course and standards of care for hypertensive adults with type 2 diabetes mellitus and nephropathy. Results available on May 19, 2001, will help in defining the current controversy of the risks and benefits of blockade of the renin-angiotensin system versus calcium channel blockade versus standard antihypertensive therapy in this large patient population.

Renoprotective effect of the angiotensin-receptor antagonist irbesartan in patients with nephropathy due to type 2 diabetes.

BACKGROUND: It is unknown whether either the angiotensin-II-receptor blocker irbesartan or the calcium-channel blocker amlodipine slows the progression of nephropathy in patients with type 2 diabetes independently of its capacity to lower the systemic blood pressure. METHODS: We randomly assigned 1715 hypertensive patients with nephropathy due to type 2 diabetes to treatment with irbesartan (300 mg daily), amlodipine (10 mg daily), or placebo. The target blood pressure was 135/85 mm Hg or less in all groups. We compared the groups with regard to the time to the primary composite end point of a doubling of the base-line serum creatinine concentration, the development of end-stage renal disease, or death from any cause. We also compared them with regard to the time to a secondary, cardiovascular composite end point. RESULTS: The mean duration of follow-up was 2.6 years. Treatment with irbesartan was associated with a risk of the primary composite end point that was 20 percent lower than that in the placebo group (P=0.02) and 23 percent lower than that in the amlodipine group (P=0.006). The risk of a doubling of the serum creatinine concentration was 33 percent lower in the irbesartan group than in the placebo group (P=0.003) and 37 percent lower in the irbesartan group than in the amlodipine group (P<0.001). Treatment with irbesartan was associated with a relative risk of end-stage renal disease that was 23 percent lower than that in both other groups (P=0.07 for both comparisons). These differences were not explained by differences in the blood pressures that were achieved. The serum creatinine concentration increased 24 percent more slowly in the irbesartan group than in the placebo group (P=0.008) and 21 percent more slowly than in the amlodipine group (P=0.02). There were no significant differences in the rates of death from any cause or in the cardiovascular composite end point. CONCLUSIONS: The angiotensin-II-receptor blocker irbesartan is effective in protecting against the progression of nephropathy due to type 2 diabetes. This protection is independent of the reduction in blood pressure it causes.

Severe lupus nephritis: importance of re-evaluating the histologic classification and the approach to patient care.

The histopathology of severe lupus glomerulonephritis comprises distinct patterns of injury which were initially defined by the World Health Organization Classification of 1982 as focal and segmental glomerulonephritis (category III), diffuse proliferative glomerulonephritis (category IV) and complex membranous glomerulonephritis (categories Vc, Vd). It is assumed that the morphologic abnormalities demonstrated in this classification represent distinctive differences in the mediation of the immune response which leads to a specific type of glomerular inflammation. In 1995 the World Health Organizational committee recommended a change in categorization of focal and segmental glomerulonephritis (class III) and diffuse proliferative glomerulonephritis (class IV), which would overlook the morphological differences between these categories and treat them as a continuum, recommending that biopsies classified as focal and segmental glomerulonephritis (category III) with involvement of > or =50% of glomeruli be included into the diffuse proliferative glomerulonephritis category (category IV). Since the classification of severe lupus nephritis has significant impact on prognosis and the therapeutic approach to patients with this disease, it is the purpose of this review to critically re-examine the existing classification based on new insights into differences in morphologic features and long-term outcome.

Significance of histologic patterns of glomerular injury upon long-term prognosis in severe lupus glomerulonephritis.

BACKGROUND: Patients with systemic lupus erythematosus have a spectrum of glomerular disease, but the different patterns of glomerular injury identified within the general category of "severe" lupus glomerulonephritis are responsible for much of the morbidity and mortality in this disease. The glomerular injury patterns seen with severe lupus glomerulonephritis have been separated into distinct histopathologic groups to determine whether they can predict long-term patient outcome. METHODS: We analyzed the clinical follow-up of 85 patients participating in a controlled prospective therapeutic trial for the treatment of severe lupus glomerulonephritis conducted from April 1981 to December 1988, with an average follow-up of 10 years. Patients were classified according to the 1982 World Health Organization classification for lupus glomerulonephritis. RESULTS: During the course of follow-up [120 +/- 65 (SD) months], 60% of patients with category IV (diffuse proliferative glomerulonephritis) lesions entered a remission compared with only 38% of patients with category III (> or =50%, focal and segmental glomerulonephritis) lesions and 27% of patients with category Vc (> or =50%) and Vd (P < 0.05). Renal survival at 10 years was 75% for those with category IV lesions, 47% for patients with category Vc (> or =50%) and Vd, and 52% for patients with category III (> or =50%) lesions (P < 0.05). Based on multivariate analysis, patients with category III (> or =50%) or Vc (> or =50%) and Vd lesions had a relative risk of progression to end-stage renal disease 2.9 times that of category IV patients (P < 0.01), while the likelihood of entering a remission was 8.2 times greater for category IV patients (P = 0.0001). CONCLUSION: The histopathologic categorization among patients with severe lupus glomerulonephritis provides information relevant to their long-term outcome.