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Introduction A C5 polymorphism (rs17611, 2404G>A) exists where the G allele associates with enhanced C5a-like production by neutrophil elastase. This cohort study investigated the influence of this polymorphism as a risk factor for lupus nephritis (LN), and on C5a and membrane attack complex (MAC) levels in LN during flare. Methods A cohort of lupus patients (n = 155) was genotyped for the 2404G>A polymorphism. A longitudinal LN subset (n = 66) was tested for plasma and urine levels of C5a and MAC 4 and/or 2 months before and at nonrenal or LN flare. Results The 2404G allele and 2404-GG genotype were associated with LN in black, but not white, lupus patients. In the longitudinal cohort, neither urine nor plasma C5a levels changed at nonrenal flare regardless of 2404G>A genotype or race. Urine (but not plasma) C5a levels increased at LN flare independent of race, more so in 2404-GG patients where 8 of 30 LN flares exhibited very high C5a levels. Higher proteinuria and serum creatinine levels also occurred in these eight flares. Urine (but not plasma) MAC levels also increased at LN flare in 2404-GG patients and correlated with urine C5a levels. Conclusions The C5 2404-G allele/GG genotype is a potential risk factor for LN uniquely in black lupus patients. The GG genotype is associated with sharp increases in urine C5a and MAC levels in a subset of LN flares that correspond to higher LN disease indices. The lack of corresponding changes in plasma suggests these increases reflect intrarenal complement activation., Graphical abstract

Rationale & Objective In 2009, the first case of acute kidney injury and occlusive red blood cell (RBC) tubular casts associated with a high international normalized ratio in a patient receiving warfarin was identified. This entity, named warfarin-related nephropathy, was later renamed anticoagulant-related nephropathy (ARN) after similar cases with other anticoagulants were described. We provide our 10-year experience with ARN based on a single-center kidney biopsy laboratory. Study Design The kidney pathology database at the Ohio State University Wexner Medical Center (OSUWMC) was searched for native kidney biopsy cases consistent with ARN. Clinical data were obtained from patient medical records. Setting & Participants Native kidney biopsies evaluated between January 1, 2009, and December 31, 2017 at OSUWMC. Results Among 8,636 native kidney biopsies reviewed at the OSUWMC, there were 41 (0.5%) patients for whom deterioration in kidney function could not be explained by kidney biopsy findings alone if anticoagulation was not considered. There were 63% men and 95% were white; average age was 62 ± 14 years. Most were on warfarin therapy (N = 28), although cases were also attributed to direct-acting anticoagulants (N = 2), antiplatelet medications (N = 1), heparin or enoxaparin (N = 4), and disseminated intravascular coagulopathy (N = 6). Morphologically, there was acute tubular necrosis and RBC casts. The majority of biopsies had an underlying glomerular disease and many patients had positive serologic test results. In all these cases, the severity of kidney failure, RBC tubular casts, and hematuria were disproportionate to glomerular morphologic changes. Limitations Selection bias in the decision to perform a kidney biopsy. Conclusions ARN is an uncommon diagnosis in kidney pathology practice, but it should be considered when the number of RBC tubular casts is disproportionate to the severity of glomerular changes in a kidney biopsy in patients either receiving anticoagulation therapy or who presented with acute coagulopathy. Our data suggest that anticoagulation aggravates underlying glomerular diseases rather than directly affecting the glomerular filtration barrier., Graphical abstract

Introduction Cross-sectional studies document that the spot protein/creatinine ratio (PCR) is often an inaccurate estimate of proteinuria magnitude compared with the 24-hour PCR, which is the gold standard. However, the extent to which the inaccuracy of the spot PCR varies over time and between individuals has not previously been reported. We address these crucial questions using a unique database, an National Institutes of Health trial in which lupus nephritis (LN) patients (N = 103) provided spot PCR testing each month and 24-hour PCR testing every 3 months for up to 15 months after induction therapy. Methods A gold standard proteinuria trend line was constructed for each patient by joining the points that represented the serial 24-hour PCR values of the patient. The spot PCR values of the patient were then plotted in relationship to the 24-hour PCR trend line. Using our previous work, which estimated the 95% confidence intervals for the 24-hour PCR at specific levels, we determined in each patient whether the spot PCR values were “reliable,” “problematic,” or “unreliable.” The sequential spot PCR of the patients deviated widely and often from the 24-hour PCR trend line, to the extent that, if the spot PCR results were used in real time for clinical decision-making, it was likely management errors would occur. Results Spot PCRs were reliable in 41%, problematic in 24%, and unreliable in 35% of patients. Those with unreliable spot PCRs could not be predicted and were more likely to respond poorly to treatment. Conclusion The spot PCR should not be used for management of LN, and perhaps, other glomerulopathies.

The complement system is composed of a family of soluble and membrane-bound proteins that historically has been viewed as a key component of the innate immune system, with a primary role of providing a first-line defense against microorganisms. Although this role indeed is important, complement has many other physiological roles, including the following: (1) influencing appropriate immune responses, (2) disposing of waste in the circulation (immune complexes, cellular debris), and (3) contributing to damage of self-tissue through inflammatory pathways. These three roles are believed to be significant factors in the pathogenesis of systemic lupus erythematosus, particularly its renal manifestation (lupus nephritis), contributing both protective and damaging effects. In this review, we provide an overview of the human complement system and its functions, and discuss its intricate and seemingly contradictory roles in the pathogenesis of lupus nephritis.

A spate of recent publications describes a newly recognized form of glomerulonephritis associated with active staphylococcal infection. The key kidney biopsy findings, glomerular immunoglobulin A (IgA) deposits dominant or codominant with IgG deposits, resemble those of IgA nephritis. Many authors describe this condition as "postinfectious" and have termed it "poststaphylococcal glomerulonephritis." However, viewed through the prism of poststreptococcal glomerulonephritis, the prefix "post" in poststaphylococcal glomerulonephritis is historically incorrect, illogical, and misleading with regard to choosing therapy. There are numerous reports describing the use of high-dose steroids to treat poststaphylococcal glomerulonephritis. The decision to use steroid therapy suggests that the treating physician believed that the dominant problem was a postinfectious glomerulonephritis, not the infection itself. Unfortunately, steroid therapy in staphylococcus-related glomerulonephritis can precipitate severe staphylococcal sepsis and even death and provides no observable benefits. Poststreptococcal glomerulonephritis is an authentic postinfectious glomerulonephritis; poststaphylococcal glomerulonephritis is not. Making this distinction is important from the perspective of history, pathogenesis, and clinical management.

Recent breakthrough findings revealed that most patients with idiopathic (primary) membranous glomerulonephritis have IgG4 antibodies to the phospholipase A2 receptor (PLA2R). These IgG4 antibodies can be detected in the glomerular immune complexes and they colocalize with PLA2R. In secondary forms of membranous glomerulonephritis, such IgG4 antibodies are absent or less prevalent. There are no studies addressing the IgG subclass distribution across different stages of membranous glomerulonephritis. During a 25-month period, we identified 157 consecutive biopsies with membranous glomerulonephritis with adequate tissue for light, immunofluorescence and electron microscopy. Of the 157 membranous glomerulonephritis cases, 114 were primary membranous glomerulonephritis and 43 were secondary membranous glomerulonephritis. We compared the intensity of IgG subclass staining (on a semiquantitative scale of 0 to 3+) and the IgG subclass dominance between primary and secondary membranous glomerulonephritis and between the different stages of membranous glomerulonephritis. In primary membranous glomerulonephritis most (76% of cases) were IgG4 dominant. In contrast, in secondary membranous glomerulonephritis IgG1 was dominant in 60% of biopsies (P=0.0018). Interestingly, in early stage (stage 1) primary membranous glomerulonephritis, IgG1 was the dominant IgG subclass (64% of cases); in all later stages IgG4 dominated (P=0.0493). It appears that there is an inverse relationship between the intensity of glomerular capillary IgG4 and C1q staining. In secondary forms of membranous glomerulonephritis (heterogeneous group with low case numbers), we did not find such associations. Our data indicate that in early stage membranous glomerulonephritis, antibody response is different from later stages, with IgG1 dominant deposits. It is possible that early on, antigens other than PLA2R have an important role, Alternately, there may be an IgG subclass switch in the antibody response with IgG4 taking over later as the dominant immunoglobulin.

Systemic lupus erythematosus (SLE) is a prototypic, inflammatory autoimmune disease characterized by significant gender bias. Previous studies have established a role for hormones in SLE pathogenesis, including the sex hormone estrogen. Estrogen regulates gene expression by translocating estrogen receptors (ER) α and β into the nucleus where they induce transcription by binding to estrogen response elements (EREs) of target genes. The ZAS3 locus encodes a signaling and transcriptional molecule involved in regulating inflammatory responses. We show that ZAS3 is significantly up-regulated in SLE patients at both the protein and mRNA levels in peripheral blood mononuclear cells (PBMCs). Furthermore, estrogen stimulates the expression of ZAS3 in vitro in several leukocyte and breast cancer cell lines of both human and murine origin. In vivo estrogen treatment mediates induction of tissue specific ZAS3 expression in several lymphoid organs in mice. Estrogen stimulation also significantly up-regulates ZAS3 expression in primary PBMCs, while treatment with testosterone has no effect. Mechanistically, estrogen induces differential ERα binding to putative EREs within the ZAS3 gene and ERα knockdown with siRNA prevents estrogen induced ZAS3 up-regulation. In contrast, siRNA targeting IFNα has no effect. These data demonstrate that ZAS3 expression is directly regulated by estrogen and that ZAS3 is overexpressed in lupus. Since ZAS3 has been shown to regulate inflammatory pathways, its up-regulation by estrogen could play a critical role in female-biased autoimmune disorders.

The application of molecular techniques to characterize clinical kidney biopsies has the potential to provide insights into glomerular diseases that cannot be revealed by traditional renal pathology. The present work is a proof-of-concept approach to test whether proteomic analysis of glomeruli isolated from clinical biopsies by laser capture microdissection can provide unique information regarding differentially expressed proteins relevant to disease pathogenesis. The proteomes of glomeruli isolated by laser capture microdissection from biopsies of normal kidneys (living-related donor kidneys) were compared with those from patients with diabetic nephropathy, lupus nephritis, and fibronectin glomerulopathy. Glomerular proteins were extracted, trypsin digested, and subjected to liquid chromatography-tandem mass spectrometry for identification and quantitation. Relative to normal glomeruli, all disease-associated glomeruli showed an increased presence of complement components, a marked decline in podocyte-associated proteins, and a decrease in proteins associated with cellular metabolism. Additionally, fibronectin glomerulopathy glomeruli differed from all the other glomeruli because of a significant accumulation of fibronectin and fibulin. This study demonstrates that our method acquires reproducible and quantitative proteomic information from laser capture microdissection isolates that can be used to characterize the molecular features of glomerular diseases.

An acute increase in the international normalized ratio (INR; a comparison of prothrombin time to monitor the effects of warfarin) over 3 in patients with chronic kidney disease (CKD) is often associated with an unexplained acute increase in serum creatinine (SC) and an accelerated progression of CKD. Kidney biopsy in a subset of these patients showed obstruction of the renal tubule by red blood cell casts, and this appears to be the dominant mechanism of the acute kidney injury. We termed this warfarin-related nephropathy (WRN), and previously reported cases of WRN only in patients with CKD. We now assess whether this occurs in patients without CKD, its risk factors, and consequences. In 15,258 patients who initiated warfarin therapy during a 5-year period, 4006 had an INR over 3 and SC measured at the same time; however, the large data set precluded individual patient clinical assessment. A presumptive diagnosis of WRN was made if the SC increased by over 0.3 mg/dl within 1 week after the INR exceeded 3 with no record of hemorrhage. WRN occurred in 20.5% of the entire cohort, 33.0% of the CKD cohort, and 16.5% of the no-CKD cohort. Other risk factors included age, diabetes mellitus, hypertension, and cardiovascular disease. The 1-year mortality was 31.1% with compared with 18.9% without WRN, an increased risk of 65%. Thus, WRN may be a common complication of warfarin therapy in high-risk patients and CKD doubles this risk. The mechanisms of these risks are unclear.

Lupus nephritis is a frequent and serious complication of systemic lupus erythematosus (SLE), the treatment of which often requires the use of immunosuppressives that can have severe side effects. Here we determined the low-molecular weight proteome of serial lupus urine samples to uncover novel and predictive biomarkers of SLE renal flare. Urine from 25 flare cycles of 19 patients with WHO Class III, IV, and V SLE nephritis were obtained at baseline, pre-flare, flare and post-flare. Each sample was first fractionated to remove proteins larger than 30kDa, then applied onto weak cation exchanger protein chips for analysis by SELDI-TOF mass spectrometry. We found 176 protein ions of which 27 were differentially expressed between specific flare intervals. On-chip peptide sequencing by integrated tandem mass spectrometry positively identified the 20 and 25 amino-acid isoforms of hepcidin, as well as fragments of α1-antitrypsin and albumin among the selected differentially expressed protein ions. Hepcidin 20 increased 4 months before renal flare and returned to baseline at renal flare, whereas hepcidin 25 decreased at renal flare and returned to baseline 4 months after the flare. These studies provide a beginning proteomic analysis aimed at predicting impending renal relapse, relapse severity, and the potential for recovery after SLE nephritis flare.

The diagnosis of glomerulonephritis flares in systemic lupus erythematosus (SLE) is usually based on whether the magnitude of proteinuria has changed. Our study tests two methods to assess proteinuric change: protein/creatinine (P/C) ratios of intended 24-h urine collections or that of spot urine samples. Sixty-four patients with glomerulonephritis due to SLE followed in the Ohio SLE Study provided bimonthly paired spot and intended 24-h urine collections. Completeness of each collection was estimated as the ratio of the measured creatinine to the expected creatinine based upon Cockroft–Gault. Intended 24-h urine collections with measured/expected creatinine ratios between 0.5 and 0.9 (237 samples overall) showed ratios that were not significantly different from ratios of complete 24-h urine collections with ratios of 0.9–1.1 (159 samples). To compare spot and 24 h P/C ratios, we randomly selected pairs of samples with measured/expected ratios above 0.75. Consistent with previous studies, spot and 24-h urine P/C ratios showed good correlation over the range of values as well as reasonably strong concordance. Over the range of most SLE glomerulonephritis flares, however, correlation was present but concordance was poor. Our work suggests that the use of spot urine P/C ratios will yield more false-positive and -negative diagnoses of glomerulonephritis flares in patients with SLE than the ratio in 24-h urines.

m C m ARFARIN THERAPY is a well-established cause of gross hematuria and can ndicate the presence of a focal lesion such as umor.1 Impaired kidney function, however, does ot occur except in the rare instance of severe lood loss or clot formation that obstructs the rinary tract. On the other hand, although sysemic lupus erythematosus (SLE) glomerulonehritis is a well-established cause of acutely mpaired kidney function, gross hematuria rarely ccurs.2 Thus, it seemed paradoxic when an SLE atient with warfarin coagulopathy presented ith both gross hematuria and acute renal failure n the absence of hemodynamically significant lood loss or urinary tract obstruction. The renal iopsy findings resolved this paradox.

Background: Increased fluid intake slows renal disease progression in animal models. The relevance of these findings to human renal disease is not clear, although increased fluid intake often is recommended to patients with chronic renal insufficiency. This study tested the hypothesis that urine volume, urine osmolality (Uosm), or both are significantly associated with glomerular filtration rate (GFR) decline in patients with chronic renal insufficiency. Methods: This is a retrospective analysis of Modification of Diet in Renal Disease (MDRD) study A patients with (N = 139) and without polycystic kidney disease (PKD; N=442). The key outcome measure was GFR slope in relation to mean 24-hour urine volume and Uosm during follow-up in study A (mean, 2.3 years). Results: The regression of GFR slope on mean follow-up 24-hour urine volume (adjusted for body surface area and MDRD diet and blood pressure group) showed that the greater the urine volume, the faster the GFR decline in patients both with and without PKD. For example, the difference in GFR slope for those with a mean follow-up 24-hour urine volume of 2.4 versus 1.4 L was −1.01 mL/min/y (confidence interval, −0.27 to −1.75) for patients without PKD and −1.20 mL/min/y (confidence interval, −0.06 to −2.34) for those with PKD. A similar but inverse relationship was shown between GFR decline and mean 24-hour Uosm in patients with ( P = 0.01) and without PKD ( P = 0.001). These associations remained significant after adjustment for 13 relevant baseline and follow-up covariates. Conclusion: Sustained high urine volume and low Uosm are independent risk factors for faster GFR decline in patients with chronic renal insufficiency. Thus, high fluid intake does not appear to slow renal disease progression in humans. We suggest that until better evidence becomes available, patients with chronic renal insufficiency should generally let their thirst guide fluid intake. The advice to avoid "pushing fluids" might be particularly important for patients with PKD.

Cyclosporine in patients with steroid-resistant membranous nephropathy: A randomized trial.BackgroundA clinical trial of cyclosporine in patients with steroid-resistant membranous nephropathy (MGN) was conducted. Although MGN remains the most common cause of adult-onset nephrotic syndrome, its management is still controversial. Cyclosporine has been shown to be effective in cases of progressive MGN, but it has not been used in controlled studies at an early stage of the disease.MethodsWe conducted a randomized trial in 51 biopsy-proven idiopathic MGN patients with nephrotic-range proteinuria comparing 26 weeks of cyclosporine treatment plus low-dose prednisone to placebo plus prednisone. All patients were followed for an average of 78 weeks, and the short- and long-term effects on renal function were assessed.ResultsSeventy-five percent of the treatment group versus 22% of the control group (P < 0.001) had a partial or complete remission of their proteinuria by 26 weeks. Relapse occurred in 43% (N = 9) of the cyclosporine remission group and 40% (N = 2) of the placebo group by week 52. The fraction of the total population in remission then remained almost unchanged and significant different between the groups until the end of the study (cyclosporine 39%, placebo 13%, P = 0.007). Renal function was unchanged and equal in the two groups over the test medication period. In the subsequent follow-up, renal insufficiency, defined as doubling of baseline creatinine, was seen in two patients in each group, but remained equal and stable in all of the other patients.ConclusionThis study suggests that cyclosporine is an effective therapeutic agent in the treatment of steroid-resistant cases of MGN. Although a high relapse does occur, 39% of the treated patients remained in remission and were subnephrotic for at least one-year post-treatment, with no adverse effect on filtration function.

ACE inhibition or angiotensin receptor blockade: Impact on potassium in renal failure. Background Inhibition of the renin-angiotensin system is known to raise serum potassium [K + ] levels in patients with renal insufficiency or diabetes. No study has evaluated the comparative effects of an angiotensin-converting enzyme (ACE) inhibitor versus an angiotensin receptor blocker (ARB) on the changes in serum [K + ] in people with renal insufficiency. Methods The study was a multicenter, randomized, double crossover design, with each period lasting one month. A total of 35 people (21 males and 14 females, 19 African Americans and 16 Caucasian) participated, with the mean age being 56 ± 2 years. Mean baseline serum [K + ] was 4.4 ± 0.1 mEq/L. The glomerular filtration rate (GFR) was 65 ± 5 mL/min/1.73 m 2 , and blood pressure was 150 ± 2/88 ± 1 mm Hg. The main outcome measure was the difference from baseline in the level of serum [K + ], plasma aldosterone, and GFR following the initial and crossover periods. Results For the total group, serum [K + ] changes were not significantly different between the lisinopril or valsartan treatments. The subgroup with GFR values of ≤60 mL/min/1.73 m 2 who received lisinopril demonstrated significant increases in serum [K + ] of 0.28 mEq/L above the mean baseline of 4.6 mEq/L ( P = 0.04). This increase in serum [K + ] was also accompanied by a decrease in plasma aldosterone ( P = 0.003). Relative to the total group, the change in serum [K + ] from baseline to post-treatment in the lisinopril group was higher among those with GFR values of ≤60 mL/min/1.73 m 2 . The lower GFR group taking valsartan, however, demonstrated a smaller rise in serum [K + ], 0.12 mEq/L above baseline ( P = 0.1), a 43% lower value when compared with the change in those who received lisinopril. This blunted rise in [K + ] in people taking valsartan was not associated with a significant decrease in plasma aldosterone ( P = 0.14). Conclusions In the presence of renal insufficiency, the ARB valsartan did not raise serum [K + ] to the same degree as the ACE inhibitor lisinopril. This differential effect on serum [K + ] is related to a relatively smaller reduction in plasma aldosterone by the ARB and is not related to changes in GFR. This study provides evidence that increases in serum [K + ] are less likely with ARB therapy compared with ACE inhibitor therapy in people with renal insufficiency.

Proximal tubular epithelial hyperplasia in patients with chronic glomerular proteinuria. Background Proteinuria is known to affect the proximal tubular epithelial structure and function. The present study tested the hypothesis that chronic proteinuria leads to hyperplasia of proximal tubular epithelium. Methods This hypothesis was tested by morphometric analysis of the renal biopsy specimens in two groups of patients. Group A ( N = 15) was composed of patients with chronic glomerular proteinuria who, for clinical indications, underwent renal biopsy of their native kidneys on two separate occasions. The proteinuria was sustained during the first and second renal biopsies in all but two of the patients with minimal change nephrotic syndrome who experienced transient remission. Group B ( N = 10) was composed of patients with little or no proteinuria who underwent renal biopsy because of unexplained hematuria and whose renal biopsy showed only thin glomerular basement membrane (GBM) disease. Results In Group A, the mean number of epithelial cell nuclei per proximal tubule cross-section increased significantly from the first to the second renal biopsy (11.0 ± 2.7 vs. 13.0 ± 2.2, P = 0.005, paired t -test). Also, those with severe proteinuria showed proximal tubules with reactive epithelium (large pale nuclei with a high nucleus to cytoplasm ratio) and marked hyperplasia (double and triple layers of epithelium). Such changes were not seen in group B renal biopsies. Compared with group A biopsies, group B biopsies showed a lower mean value for proximal tubular epithelial cell nuclei per tubular cross-section ( P = 0.056) and a higher mean proximal tubular volume ( P = 0.049). As a consequence, the mean number of nuclei per relative tubular volume was significantly greater in group A compared with group B (0.55 ± 0.14 vs. 0.40 ± 0.06, P = 0.003, by Wilcoxon rank sum). Conclusions Chronic heavy proteinuria is associated with hyperplasia of proximal tubular epithelium and contraction of proximal tubular volume. These events may impair glomerular filtration and represent another mechanism of progression of renal disease.

A randomized trial of cyclosporine in patients with steroid-resistant focal segmental glomerulosclerosis.BackgroundA clinical trial of cyclosporine in patients with steroid-resistant focal segmental glomerulosclerosis (FSGS) was conducted. Despite the fact that it is the most common primary glomerulonephritis to progress to renal failure, treatment trials have been very limited.MethodsWe conducted a randomized controlled trial in 49 cases of steroid-resistant FSGS comparing 26 weeks of cyclosporine treatment plus low-dose prednisone to placebo plus prednisone. All patients were followed for an average of 200 weeks, and the short- and long-term effects on renal function were assessed.ResultsSeventy percent of the treatment group versus 4% of the placebo group (P < 0.001) had a partial or complete remission of their proteinuria by 26 weeks. Relapse occurred in 40% of the remitters by 52 weeks and 60% by week 78, but the remainder stayed in remission to the end of the observation period. Renal function was better preserved in the cyclosporine group. There was a decrease of 50% in baseline creatinine clearance in 25% of the treated group compared with 52% of controls (P < 0.05). This was a reduction in risk of 70% (95% CI, 9 to 93) independent of other baseline demographic and laboratory variables.ConclusionsThese results suggest that cyclosporine is an effective therapeutic agent in the treatment of steroid-resistant cases of FSGS. Although a high relapse rate does occur, a long-term decrease in proteinuria and preservation of filtration function were observed in a significant proportion of treated patients.

The present study is a prospective, controlled, blinded trial of enalapril therapy in experimental immune complex (IC)-mediated glomerulonephritis (GN) in the nonhuman primate (cynomolgus monkey [CYN]). Two groups of CYNs were studied: those with established GN (study A) and those in which GN was being induced (study B). In study A, 12 CYNs had GN established by 8 or 10 weeks of daily intravenous infusion of bovine gamma-globulin (BGG). These CYNs were then assigned to either 4 weeks of daily oral enalapril therapy (n = 6) or daily oral placebo therapy (n = 6). The daily BGG infusions were continued during the 4 weeks of enalapril or placebo therapy. At the start of the enalapril/placebo protocol, the two groups were similar with respect to proteinuria and level of precipitating antibody to BGG, which determined the daily BGG dose. Renal biopsy was performed in each CYN at the start and end of the 4-week period of enalapril/placebo protocol. In study B, 15 normal CYNs were immunized to BGG over a period of 4 weeks. The CYNs were then assigned to daily oral enalapril therapy (n = 8) or placebo therapy (n = 7) based on level of precipitating antibody to BGG. At this point, daily intravenous BGG was begun along with daily enalapril or placebo for 8 weeks. Renal biopsy was performed in each CYN before and at the end of this 8-week period. In study A, enalapril therapy was associated with a significant decrease in mesangial matrix volume (mean change, -27.7%; P = 0.031) and a trend toward decreased mesangial matrix deposits (mean change, -34.1%; P = 0.188). By contrast, in CYNs receiving placebo therapy, mesangial matrix volume increased compared with the enalapril group (P = 0.002) and mesangial deposits were unchanged. In study B, both the enalapril and placebo groups showed significant increases in mesangial matrix volume, mesangial deposits, mesangial cell volume, and capillary wall deposits during the 8 weeks of daily BGG infusion. However, none of the differences between the groups achieved statistical significance. Changes in mesangial cell volume and capillary wall deposits were also evaluated in study A and study B, but were not found to be different between the enalapril and placebo groups. In both study A and study B, blood pressure was lower in the enalapril groups. In conclusion, in the initial phase of IC-GN induction (0 to 8 weeks), enalapril therapy does not significantly influence the glomerular accumulation of mesangial matrix or immune deposits. However, in established IC-GN (after 8 weeks of GN induction), enalapril therapy significantly decreases the further accumulation of mesangial matrix and may decrease the further accumulation of mesangial deposits. Whether this benefit of enalapril therapy was related to lower blood pressure or to other effects of angiotensin-converting enzyme (ACE) inhibition was not determined in this study.

Loin pain-hematuria syndrome associated with thin glomerular basement membrane disease and hemorrhage into renal tubules. Loin painhematuria (LPH) syndrome is a poorly understood disorder in which the patients, mainly young women, experience unexplained severe chronic unilateral or bilateral flank pain associated with gross and/or microscopic hematuria. By contrast, thin glomerular basement membrane (GBM) disease is generally thought to be a benign disorder, affecting males and females equally, in which the major manifestation is asymptomatic microscopic hematuria. Herein we describe seven patients (6 females, 1 male) in whom thin GBM appeared to be the cause of the LPH syndrome. The gross hematuria in these patients could be attributed to thin GBM disease because the renal biopsy demonstrated red cells in renal tubules (indicating glomerular hematuria) and the only glomerular abnormality present was thin GBM. In addition, the other causes of gross hematuria were excluded by appropriate testing. The flank pain in these patients might also have been the result of their thin GBM disease. This is suggested by renal biopsy findings of multiple renal tubules filled with red cells, apparently occluding the tubules. We suggest that occlusion of a relatively small fraction of renal tubules could cause renal pain if back-leak of glomerular filtrate occurred that was of sufficient magnitude to expand renal parenchymal volume and stretch the renal capsule. Preliminary observations suggest that treatment with the angiotensin converting enzyme (ACE) inhibitor enalapril importantly reduces the frequency and severity of the episodes of gross hematuria and flank pain in most patients. ACE inhibition might decrease glomerular hemorrhage in patients with thin GBM by decreasing glomerular hydrostatic pressure. We conclude that (1) Thin GBM disease can be the cause of gross hematuria, apparently as a result of rupture of thin GBM. (2) Rupture of thin GBM resulting in hemorrhage into renal tubules may be the cause of the flank pain and gross hematuria in some patients with the LPH syndrome.

Previous studies of the in vitro effects of recombinant erythropoietin (rEPO) on T and B cells and studies of lymphocyte subsets in dialysis patients receiving rEPO therapy suggest that rEPO might augment immune responses. In the present study indices of autoimmunity (antinuclear antibody, anti-double-stranded DNA, and antiphospholipid antibody [immunoglobulins G and M]) were measured before, during, and after rEPO therapy in five systemic lupus erythematosus patients without renal failure (mean serum creatinine, 1.5 +/- 0.3 mg/dL). The rEPO therapy was self-administered by subcutaneous injection in doses ranging from 4,000 units once weekly to 3,000 units three times weekly for 3 to 7 months. On rEPO therapy, each patient experienced an increase in hematocrit. The mean baseline hematocrit increased from 32 +/- 2.0 to a peak of 42.2 +/- 3 (P0.001) at 3 to 7 months and then decreased to baseline values 1 to 2 months after rEPO was discontinued. During this time the indices of autoimmunity were not significantly changed by rEPO therapy. Systemic lupus erythematosus activity, assessed by serum C3, serum creatinine, urinalysis, and 24-hour proteinuria, also was unchanged by rEPO therapy. The rEPO therapy was generally well tolerated. However, one patient, who was also receiving replacement estrogen therapy and had high-titer antiphospholipid antibody, experienced episodes of thrombophlebitis while on rEPO therapy. In conclusion, we found no evidence that rEPO increases autoimmunity in systemic lupus erythematosus. However, we observed a temporal relationship between episodes of thrombophlebitis and rEPO therapy in a single patient with high-titer anticardiolipin antibody who was also receiving replacement estrogen therapy. These associations require further investigation.

Effect of chronically increased erythrocyte complement receptors on immune complex nephritis. Experimental studies in humans and other primates have shown that the erythrocyte (E) complement receptor Type 1 (CR1), which is unique to the primate, plays an important role in clearing immune complexes (IC) from the circulation by binding C3b/C4b opsonized immune complexes and carrying the IC to liver and spleen for disposal. The results of these acute experiments suggest that increasing E-CR1 levels chronically should protect against IC-mediated glomerulonephritis (IC-GN) induced by chronic formation of IC in the circulation. In the present study this hypothesis was tested in the cynomolgus monkey (CYN). IC-GN was induced by daily bolus intravenous infusion of BGG into immunized CYN for 8, 10, or 14 weeks. Prior to and during the daily bolus infusions of BGG, sustained differences in E-CR1 levels were achieved between the experimental group (increased E-CR1 levels) and the control group (maintained or decreased E-CR1 levels), by one of two methods: (1) Twice weekly exchange transfusion. The CYN donors were blood type compatible with the recipients and had either constitutive high E-CR1 expression (3,000 to 5,000 CR1/E) or constitutive low E-CR1 expression (< 100 CR/E). The recipients of the exchange transfusions (N = 2) had constitutive mid-level E-CR1 expression. (2) Weekly phlebotomy (PL) or sham PL. CYN with mid-level E-CR1 expression were randomly assigned to receive weekly either PL (causing increased E-CR1 expression by stimulating erythropoiesis) (N = 8) or sham PL (which has no effect on E-CR1 expression (N = 9). We found that the exchange transfusion model produced large differences between the CYN in CR1/E (mean 910 in the CYN exchanged with high E-CR1 donors vs. 210 in the CYN exchanged with the low E-CR1 donors) but was labor intensive. The PL/sham PL model also induced large and sustained differences in CR1/E between the PL group (1150 ± 160 CR1/E) and the sham PL group (530 ± 80 CR1/E), and was relatively easy to perform. Deaths due to respiratory failure during BGG infusion occurred in the first week of daily BGG infusion in three CYN randomized to the Sham PL. These CYN are not included in the final analysis. The primary outcome variable was a blinded morphometric evaluation of glomerular electron dense deposits, expressed as the percent of a given glomerular component occupied by deposit, in the biopsy performed at the termination of the GN-induction protocol. The renal biopsies done prior to administration of BGG show no glomerular electron dense deposits. The terminal renal biopsy results are as follows: in the experimental group (raised E-CR1 levels) versus the control group (decreased or maintained E-CR1 levels) the glomerular capillary wall electron deposits were 3.2 ± 1.5% versus 9.8 ± 3.8% (P = 0.15), and the mesangial deposits were 14.3 ± 2.2 versus 21.5 ± 5.2%, (P = 0.34). Urine protein/urine creatinine ratio measured in the terminal urine samples was 0.7 ± 0.2 in the experimental group and 2.3 ± 1.1 in the control group (P = 0.22). Antibody levels, total BGG dose, and serum creatinine levels were not significantly different between the control and experimental groups. We conclude that increasing E-CR1 levels chronically does not provide statistically significant protection against glomerular accumulation of immune deposits or proteinuria in this bolus model of IC-GN.

Erythrocyte complement receptors (CR) are unique to primates and play a role in the clearance of immune complexes from the circulation. Immune complex-mediated diseases (e.g., systemic lupus erythematosus, SLE) cause decreased erythrocyte CR levels, resulting in decreased capacity of the erythrocytes to bind immune complexes that form in the circulation. Thus, raising erythrocyte CR levels might benefit patients with immune complex-mediated diseases. Because young erythrocytes express more CR than old erythrocytes, increasing erythropoiesis should increase the average number of CR expressed per erythrocyte. The present study was undertaken to test that hypothesis. Erythropoiesis was stimulated in nine cynomolgus monkeys (CYN) by weekly phlebotomy (30% of blood volume was removed, erythrocytes were discarded, and leukocytes were returned to the animal) for 8 weeks. Sham phlebotomy (30% of blood removed, then all components returned to the animal) was carried out weekly in four additional CYN for a period of 4 to 8 weeks. Sham phlebotomy did not change any of the parameters measured. However, phlebotomy resulted in a progressive increase in the mean number of CR expressed per erythrocyte (CR/erythrocyte): 2780 +/- 700 to 4230 +/- 820, P less than 0.0005. The increase in erythrocyte CR was first detected at about 2 weeks after the start of phlebotomy and was sustained through the course of phlebotomy. The increase in CR/erythrocyte included an increase in the percentage of erythrocyte expressing CR in clusters (37.9 +/- 6.4 vs 50.8 +/- 8.7%, P less than 0.01) as demonstrated by a flow cytometry study of the binding of fluorescent beads coated with anti-CR1 antibody. No significant change in leukocyte or platelet counts were observed. We conclude that stimulating erythropoiesis causes an increase in CR/erythrocyte. The magnitude of the increase suggests that it could be biologically significant.

To determine whether serum C3 or C4 is more likely to be normal during systemic lupus erythematosus (SLE) remission and abnormal during SLE relapse we studied twelve SLE patients who presented with severe nephritis. The patients were followed long term (12 to 77 months) through multiple relapses (N = 41) and remissions (N =13) defined by protocol. A total of 471 serum samples were obtained at defined intervals during these relapses and remissions and were analyzed for C3 and C4 levels by two different methods: nephelometry (N) and radial immunodiffusion (R). During SLE remission (defined by protocol and without reference to serum complement levels), C3 measured by Nassay (CM) and by R-assay (C3R) tended to be normal (specificity of 93% and 71 %, respectively). By contrast, C4 measured by N-assay (C4N) and by R-assay (C4R) showed no such tendency (specificity of 50% for both C4N and C4R). During SLE relapse (defined by protocol and without reference to serum complement levels), C3N and C3R were more likely to be abnormal (sensitivity 95% and 85%, respectively) compared with C4N and C4R (sensitivity 56% and 54%, respectively, P

~3 If deposition of circulating IC is im­ portant in the pathogenesis of IC-mediated dis­ ease, study of the mechanisms responsible for the clearing of IC from the circulation could elucidate the role of circulating IC in the pathogenesis of IC­ mediated disease. In this review, the mechanisms responsible for the clearance of IC from the circu­ lation are examined. Particular attention is paid to studies in man and other primates (monkeys, apes), because of recent evidence that primates handle circulating IC differently from nonpri­ mates. The possible pathophysiologic significance of the unique aspects of the IC-clearing mecha­ nisms of the primate is also discussed.

Experimental immune complex-mediated glomerulonephritis in the nonhuman primate. This study was undertaken to develop a model of immune complex (IC)-mediated glomerulonephritis (GN) in the nonhuman primate that could be used in subsequent studies to examine critically the role ofthe erythrocyte complement receptor (E-CR) in the pathogenesis of IC-mediated disease. Cynomolgus monkeys were chosen for study because they constituatively express E-CR levels that are either less than, equal to, or greater than that seen in normal man. After immunization with bovine gamma globulin (BGG), the GN induction protocol was begun in 10 cynomolgus by initiating daily i.v. administration of BGG in amounts sufficient to achieve or exceed antigen/antibody equivalence (assessed by the quantitative precipitin assay) for precipitating antibody present in the plasma volume. We found that within eight weeks of daily BGG administration all of the cynomolgus developed IC-mediated GN, irrespective ofthe initial E-CR level ofthe animals. However, the high E-CR cynomolgus tended to receive the higher BGG doses because of higher initial antibody levels to BGG. When the total number of glomerular deposits (determined by morpho-metric studies) per total BGG dose for each animal was plotted against the initial CR/E of that animal, there was a tendency for the animals with higher CR/E levels to have a lower number of glomerular deposits/ BGG dose (r = 0.62, P = 0.06). Also, the total number of glomerular deposits correlated with the severity ofthe GN. During the early weeks of the GN induction protocol, the IC that formed in vivo (assessed by infusion of 125I-BGG) bound in large amounts to the circulating erythrocytes ofthe cynomolgus with medium or high E-CR levels. However, when tested after the onset of heavy proteinuria, which occurred between weeks 5 and 8 of daily BGG administration, the IC that formed in the circulation bound only poorly to circulating erythrocytes. By this time the E-CR levels had declined to 43 ± 9% of initial values (P < 0.01). This study demonstrates that: 1) A workable model of IC-mediated GN has been developed in the nonhuman primate. 2) During the induction of GN, CR/E and the ability of the erythrocyte to bind IC in vivo are decreased significantly. This suggests that an intact E-CR system could play a role in the protection against IC-mediated disease. However, further study will be needed to test that hypothesis critically. The present model should be useful in such studies.

We thank Drs Messerli, Phung, and Nussberger for reminding the readers of Kidney International that no medication is completely free of adverse side effects, and that angiotensin-converting enzyme inhibitors (ACEi) are no exception.1 They raise the issue of fatal angioedema from ACEi therapy as an example of its dark side. While this is certainly a potential complication of ACEi, it is a dramatic event that is readily apparent, unlike the insidious development of metabolic and perhaps renal parenchymal complications of long-term thiazide therapy. Angioedema from ACEi is exceedingly rare, seen in about 0.1% of patients2 and tends to occur soon after initiation of therapy, although it can be significantly delayed.2, 3 Messerli and co-workers1, 4 point out that 20% of ACEi angioedemas are life threatening, and 16% of these may be fatal. A large, population-based study of 1.2 million people given enalapril found that 22% of angioedemas were life threatening, but only one death was attributable to ACEi-related angioedema.2 A study of the Tennessee Medicaid database from 1986 to 1992 found no ACEi-related angioedema deaths in 52 734 patient-years of ACEi therapy.5 With regard to the ALLHAT angioedema death cited by Messerli et al., this occurred when a patient was re-challenged with an ACEi (personal communication from Dr Jackson Wright, Case Western Reserve University), and thus was preventable. Furthermore, it is our sense that the medical community is now well aware of this potential problem with ACEi, and that ACEi will be stopped before major difficulties arise. Such expectation was not always the case. In the Tennessee Medicaid study only 37% of patients with ACEi-related angioedema had their condition correctly diagnosed at the time of their initial presentation.

We report 4 consecutive adult patients with steroid-responsive frequently relapsing minimal change disease (MCD) who continued to experience relapse after 1 to 4 courses of cyclophosphamide therapy. Each patient then was administered mycophenolate mofetil (MMF) and prednisone in tapering doses. This therapy was followed by sustained remission and is being well tolerated. MMF is promising therapy in frequently relapsing MCD, even in those with disease that continued to relapse after cyclophosphamide therapy. A controlled clinical trial of MMF therapy in this disorder is warranted.

Over the past five years there has been a groundswell of evidence from numerous laboratories indicating that the erythrocytes of humans and other primates may play a key role in the handling of immune complexes (IC) in the circulation. Most of this work has been reported outside the traditional nephrology literature and, to date, there has been no comprehensive review of this rapidly expanding subject from the nephrology perspective. However, there have been two excellent reviews stressing the basic immunology aspects of this topic [1, 2]. It is the goal of this review to examine the experimental evidence suggesting an important role for erythrocyte/IC interactions in the primate and to discuss their potential clinical implications. The erythrocytes of man and other primates appear to play a key role in the handling of circulating IC by providing a "clearing" mechanism and a "processing" mechanism. The essential first step in the handling of IC by the erythrocyte is the binding of the IC to the erythrocyte. Once bound to the erythrocyte, the evidence indicates that the IC can then be transported to liver and spleen for safe disposal (the "clearing" function of the erythrocyte). IC bound to the erythrocyte may also be acted on by specific plasma components which alter the IC and cause the IC to be released from the erythrocyte (the "processing" function of the erythrocyte). Released IC may have reduced pathogenicity and may provide a signal to the immune system. Although the biological importance of the IC "clearing" and "processing" function of the primate erythrocyte remains to be proven, the evidence accumulated to date strongly suggests that the normal operation of these erythrocyte functions may be important in protecting against the development of IC-mediated disease.

The present study evaluated the participation of the primate erythrocyte immune complex (IC) clearing mechanism in the clearance and organ uptake of double-stranded DNA (dsDNA) and of soluble ICs formed with human anti-DNA antibodies and dsDNA (dsDNA-ICs). Five baboons received 51Cr-labeled autologous erythrocytes and after a period of equilibration received separate intraarterial injections of [125I]free dsDNA and [125I]dsDNA-IC. Four of these five baboons were studied on a second occasion. To assess clearance from the arterial circulation and organ uptake, multiple blood samples were obtained from aorta, hepatic vein, and renal vein after injection of each probe. Two minutes after injection, a mean of 85% of dsDNA-ICs were bound to erythrocytes. By contrast, free dsDNA did not bind significantly to blood cells. The clearance rate of dsDNA-ICs from the arterial circulation was significantly faster than that of free dsDNA in all animals but one. Erythrocyte-bound dsDNA-ICs were cleared at a rate similar to that of total dsDNA-ICs. The liver was the major site of uptake of free dsDNA and of dsDNA-ICs. The hepatic uptakes of free dsDNA ( 17 ± 8% 5 min ) and dsDNA-ICs ( 27 ± 8% 5 min ) were not significantly different. 51Cr-labeled erythrocytes were not sequestered in the liver. There was not detectable uptake of free dsDNA or dsDNA-ICs by the kidney but with one exception. Thus, the primate erythrocyte IC clearing mechanism is involved in the clearance of dsDNA-ICs from the circulation but not in the clearance of free dsDNA.

We observed that renal transplant recipients with good graft function (mean serum creatinine level 1.5 mg/dl +/- 0.5 SD, N = 68) had dietary salt intakes (estimated from serial measurements of 24-hour sodium excretion rate) which averaged 43 percent higher than that of a comparable group of healthy subjects. There was no correlation between blood pressure levels and salt intake and, despite the high dietary salt intake, hypertension was present in only 29 patients and was usually mild; mean systolic and diastolic blood pressures were 132 +/- 10 mm Hg and 89 +/- 7 mm Hg, respectively while the patients were receiving antihypertensive medication (median number of standard doses of antihypertensive medication was 1.0 doses/patient patient per day). These observations suggest that high dietary salt intake does not exert a powerful blood pressure elevating effect, since any effect of high dietary salt intake to raise blood pressure should have been magnified in the renal transplant recipients because of their reduced renal mass and their chronic glucocorticoid therapy.

Whole kidney volume/pressure relationships. We measured changes in kidney volume and intrarenal pressure produced by step-wise, steady state increases and decreases in ureteral pressure (UP). The purpose of such maneuvers, termed exercises, was to examine the relationship between changes in kidney volume and the changes in intrarenal pressure responsible for those in kidney volume. Changes in kidney volume were assessed from directly measured changes in kidney weight. Changes in the intrarenal pressure distending the renal capsule (renal subcapsular pressure [RSCP]) were measured by a strain gauge diaphragm-type microtransducer placed between cortex and capsule. We measured these whole kidney volume/pressure events before and after saline loading and examined their relationship to changes in renal function following saline loading. We found that after four “exercises”, the kidney became more compliant, i.e., occupied a larger volume at any given UP or RSCP, and that the compliance of the kidney was further increased following saline loading. However, about one hour after saline loading, RSCP returned to or below pre-saline loading levels and renal volume returned to pre-saline loading levels; nevertheless, the natriuresis persisted. Thus, an increase in renal volume is not necessary to sustain increased sodium and water excretion in post-saline loading. Finally, we found evidence that the renal capsule provides the major force opposing expansion of outer cortex when intrarenal pressure is increased.Etude des relations volume/pression dans le rein global. Nous avons mesuré les modifications du volume rénal et de la pression intra-rénale produites par des augmentations et des diminutions par paliers atteignant l'état stationnaire de la pression urétérale (UP). Le but de ces manoeuvres, dites exercices, était d'étudier la relation entre les modifications de volume du rein et les modifications de la pression intra-rénale responsables des précédentes. Les modifications du volume du rein ont été appréciées a partir des modifications du poids du rein. Les modifications de la pression intra-rénale distendant la capsule (pression rénale subcapsulaire—RSCP—) ont été mesurées par un microtransducteur de jauge de contrainte du type à diaphragme placé entre le cortex et la capsule. Nous avons mesuré le volume rénal et la pression avant et après surcharge saline et étudié leurs relations avec les modifications de la fonction rénale consécutives à la charge saline. Nous avons constaté qu'après quatre “exercices”, le rein devient plus compliant, c'est-à-dire occupe un plus grand volume pour une UP ou RSCP donnée, et que la compliance du rein augmente encore après la charge saline. Cependant, une heure environ aprèsla charge saline, RSCP revient au niveau antérieur à la charge saline ou au-dessous, et le volume rénal revient à la valeur observée avant la charge. La natriurèse persiste néanmoins. Ainsi une augmentation du volume rénal n'est pas nécessaire pour entretenir une augmentation de l'excrétion d'eau et de sodium au décours d'une charge saline. Enfin, nous avons apporté la preuve que la capsule rénale fournit la force majeure qui s'oppose à l'expansion du cortex superficiel quand la pression est augmentée.