Absence of HIV-Associated Nephropathy Among Antiretroviral Naive Adults With Persistent Albuminuria in Western Kenya.

INTRODUCTION: HIV-associated nephropathy (HIVAN) has been strongly linked to African ancestry. However, studies have demonstrated wide variability in the prevalence of HIVAN in different sub-Saharan African populations. Accurate assessment of the disease burden is important because antiretroviral therapy (ART) is increasingly available and may prevent progression to end-stage renal disease. METHODS: We prospectively screened ART-naïve, afebrile, nonhypertensive, and nondiabetic adults attending a large HIV care program in Western Kenya for the presence of albuminuria (dipstick albumin ≥ trace or urine albumin to creatinine ratio [UACR] ≥ 30 mg/g). Those with albuminuria confirmed on 2 occasions, subject to consent, underwent kidney biopsy. RESULTS: Among 523 subjects screened, 85 (16.3%) had albuminuria on the initial screen, and persistent albuminuria was confirmed in 32 of the 53 (60%) who returned for confirmatory testing. A total of 27 subjects with persistent albuminuria underwent biopsy. The median age was 34 years (interquartile range [IQR] 30-42 years), and 63% were female. The median CD4 count was 369 cells/µl (IQR 89-492 cells/µl). Renal function was normal in 92%. Median UACR was 257.5 mg/g (IQR 93.5-543 mg/g), and 92% had UACR < 1 g/g. No subject had histologic features consistent with HIVAN; 41% had acute interstitial nephritis (AIN); 33% had nonspecific findings, and 2 patients had arteriosclerosis. Focal segmental glomerulosclerosis, acute postinfectious glomerulonephritis, chronic interstitial nephritis, pyelitis, and papillary sickling were seen in 1 patient each. DISCUSSION: Among ART-naïve adults with persistent albuminuria at a referral center in Western Kenya, we observed no cases of HIVAN. AIN was the most common cause of persistent proteinuria in this setting.

Advanced glycation end-products: implications for diabetic and non-diabetic nephropathies.

Glycation is the process whereby sugars bind to the free amine residues of proteins. These newly formed modified molecular species are known as 'advanced glycation end-products', or AGEs. AGE toxicity may occur through at least three mechanisms: interaction with the receptor for AGEs (RAGE); tissue deposition; and in situ glycation. AGEs trigger proinflammatory, profibrotic and procoagulant cellular responses that are capable of damaging tissues, often targeting particular organs. In diabetic patients, the conditions needed to promote AGE formation are all present, and are further accentuated by accompanying renal failure. The aim of this review is to outline the involvement of AGEs in the various forms of renal pathology associated with diabetic and non-diabetic nephropathies. AGEs are present in all renal compartments in diabetic patients, including the vessels, glomeruli, tubules and interstitium. Many cell types may be activated-specifically, endothelial, tubular and mesangial cells, and podocytes. AGEs play a major role in the accumulation of extracellular matrix, as occurs in diabetic glomerulosclerosis, and are also involved in most diabetic (renovascular, microangiopathic and glomerular) and non-diabetic renal injury associated with progressive glomerulosclerosis and ageing.

Sensitivity, specificity and clinical relevance of different cross-matching assays in deceased-donor renal transplantation.

To assess the significance of antibodies detected by complement-dependent cytotoxicity (CDC), solid phase (SPA) and flow cytometry (FC) assays we compared their predictive value in 354 consecutive cases of deceased-donor kidney transplantation. Pre-transplantation screening of anti-HLA class I and class II antibodies was performed by CDC and SPA. The direct crossmatch between recipients' sera and donors' T and B cells was performed by CDC followed by FC and SPA ("virtual cross-match"). The past history of antibodies displayed by the recipient was not considered a contraindication for transplantation even when it showed DSA. A side-by-side comparison of the correlation between graft loss, history of DSA and cross-match results indicated that sensitivity was 5%, 16% and 17% while specificity was 99%, 93% and 86% in CDC, SPA, FC crossmatches respectively. There was no significant difference between the 3 year survival of primary and secondary kidney allografts. We conclude that screening and cross-matching the sera by CDC provides reliable results and optimizes the patient's chances to receive a transplant. SPA and FC, however, are of great importance for identifying patients which require close monitoring by biopsy and serology for early diagnosis and treatment of acute antibody mediated rejection (AAMR).

High-dose melphalan and auto-SCT in patients with monoclonal Ig deposition disease.

The treatment of monoclonal Ig deposition disease (MIDD) is controversial and not standardized. We report our experience with high dose melphalan and auto-SCT (HDM/auto-SCT) in seven patients with MIDD associated with underlying Durie-Salmon stage IB multiple myeloma, including five with light chain deposition disease, one with light and heavy chain deposition disease and one with light chain crystal deposition disease. The median age of these patients was 50 years; six of them were male subjects. A monoclonal kappa-light chain was detected by Serum Free Light Chain Assay in all seven. The patients received melphalan 140 mg/m(2) followed by auto-SCT. All patients are alive and six remain in hematologic CR with a median follow up of 23.6 months (7.9-69.8 months). Renal function has improved compared to pre-HDSM/auto-SCT in five patients--two of whom had a renal transplant and became dialysis independent--remained stable in one and worsened in one leading to hemodialysis despite hematologic CR. Our results corroborate previous experience with HDM/auto-SCT in MIDD and argue in favor of kidney transplantation in patients who achieve hematologic CR after HDM/auto-SCT. Although this approach appears effective, multi-center studies are needed to define the optimal treatment for patients with MIDD.

Supersized kidneys: Lessons from the preclinical obese kidney.

The worldwide prevalence of obesity continues to rise. Obesity has been shown to increase the risk of both the development and the progression of renal failure, even after correction for other comorbid conditions. The ability of nephrologists to intervene will require greater understanding of obesity's renal physiologic effects. Kidney biopsies and functional studies performed on morbidly obese patients without overt renal disease who presented for bariatric surgery have helped to elucidate the earliest obesity-related structural and functional responses.

Podocyte injury in focal segmental glomerulosclerosis: Lessons from animal models (a play in five acts).

Genetic engineering in the mouse has ushered in a new era of disease modeling that has advanced our understanding of podocyte injury in the pathogenesis of focal segmental glomerulosclerosis. Historically, the major animal models of focal segmental glomerulosclerosis involve direct podocyte injury (exemplified by toxin models) and indirect podocyte injury due to adaptive responses (exemplified by renal ablation models). In both paradigms, recent evidence indicates that podocyte depletion is a major pathomechanism mediating proteinuria and glomerulosclerosis. Podocyte-specific toxin models support that podocyte loss is sufficient to cause focal segmental glomerulosclerosis in a dose-dependent manner. Knockout and transgenic models have provided proof of concept that mutations in specific podocyte proteins mediate genetic forms of focal segmental glomerulosclerosis. Transgenic models of HIV-associated nephropathy have helped to elucidate the role of direct viral infection and podocyte expression of viral gene products in the pathogenesis of this form of collapsing glomerulopathy. Taken together, emerging data support that injury directed to or inherent within the podocyte constitutes the critical event in diverse pathways to glomerulosclerosis.

The ISN/RPS 2003 classification of lupus nephritis: an assessment at 3 years.

The 2003 International Society of Nephrology (ISN)/Renal Pathology Society (RPS) Classification of lupus nephritis (LN) was designed to eliminate ambiguities and standardize definitions. Major changes from the 1982 Modified WHO Classification include the elimination of the normal biopsy category and the subcategories of membranous Class V, the introduction of sharper distinctions between the classes, and the addition of subcategories within diffuse LN (class IV) for predominantly segmental (LN IV-S) and global (LN IV-G) lesions. It stipulates that sclerotic glomeruli owing to scarred LN should be taken into account when assessing the percentage of glomeruli affected by LN. Since its publication, the ISN/RPS classification has been used successfully in a number of clinical-pathologic studies. Several studies addressing the relationship between LN IV-S and LN IV-G have failed to identify a significantly worse outcome in IV-S than IV-G, although there were some differences in presenting clinical and pathologic features. Importantly, the ISN/RPS classification has achieved its goal of improved interobserver reproducibility. Its use has increased the percentage of LN biopsies meeting criteria for class IV. As it gains widespread acceptance, the ISN/RPS classification is already providing a standardized approach to renal biopsy interpretation needed to compare outcome data across centers.

Microscopic intrarenal particles after pulsatile machine preservation do not adversely affect outcomes after renal transplantation.

INTRODUCTION: Our center has recently observed foreign carbohydrate-appearing particles (FP) on transplant postreperfusion biopsy specimens: (PRBx). METHODS: To further characterize FPs, we reviewed all renal transplant RBx (30-45 minutes) performed between September 1, 2004 and December 3, 2005. Donor, preservation, and outcome variables were collected among patients with FP. RESULTS: A total of 135 PRBx were performed (45 deceased donors [DD] and 90 live donors [LD]). Fifteen PRBx demonstrated FP. All 15 cases were DD kidneys that underwent machine perfusion (MP) on the Waters RM3 (Waters Medical Systems, Rochester, Minn, United States) with Belzer MP solution (Trans Med, Elk River, Minn, United States). Donor age was 39.8 +/- 15.7 years. Terminal creatinine level was 1.45 +/- 0.8 mg/dL. Two of 15 were flushed in situ with HTK solution (no starch). Cold ischemia time was 28.8 +/- 9.1 hours with 14.3 +/- 5.1 hours of MP. In 13 of 15 patients, perfusion parameters were excellent (flow > 100 mL; resistance < .35). CHARACTERISTICS OF FP: Particles were 10-30 mu and globular in shape. FP were not visible on hematoxylin and eosin stain, but stained strongly periodic acid-Schiff-(PAS) positive and were refractile under polarized light. FP were seen segmentally within glomerular capillaries in all cases and in peritubular capillaries in 3. In 11 of the 15 cases with FP, focal glomerular fibrin thrombi or intracapillary neutrophil margination was seen. Ten of 15 patients with FP had a biopsy within the first week with no identifiable FP. OUTCOMES: Recipient age was 45.3 +/- 11.6 years. Eight patients (53.3%) had delayed graft function. Biopsy-proven rejection occurred in 3 patients (20%). Three-month creatinine level was 1.59 +/- 0.35 mg/dL. One graft was lost to early thrombosis in a patient with a hypercoagulable state and 1 patient died of sepsis at 2 months. All remaining 13 patients are alive with excellent graft function at a median follow-up of 6.7 months (range, 3-17 months). CONCLUSIONS: Microscopic intrarenal particles may be seen on DD kidney PRBx after MP. These FPs likely originate from surgical gloves. FPs are too small to be captured by standard filters but clear spontaneously and do not have deleterious effects on renal function or outcomes.

Cellular focal segmental glomerulosclerosis: Clinical and pathologic features.

Five pathologic variants of idiopathic focal segmental glomerulosclerosis (FSGS) are recognized: collapsing (COLL), cellular (CELL), glomerular tip lesion (GTL), perihilar, and not otherwise specified (NOS). The prognostic significance of CELL FSGS has not been determined. We compared the presenting clinical and pathologic characteristics in 225 patients with CELL (N=22), COLL (N=56), GTL (N=60), and NOS (N=87) variants of idiopathic FSGS. CELL, COLL, and tip lesion all showed greater frequency and severity of nephrotic syndrome, and shorter time to biopsy compared to NOS. Predictors of end-stage renal disease (ESRD) for all FSGS patients included initial serum creatinine, % global sclerosis, % COLL lesions, chronic tubulo-interstitial injury score, and lack of remission response. COLL FSGS had the highest rate of renal insufficiency at presentation, most extensive glomerular involvement and chronic tubulo-interstitial disease, fewest remissions (13.2%), and highest rate of ESRD (65.3%). GTL patients were older and showed the highest remission rate (75.8%) and lowest rate of ESRD (5.7%). CELL variant showed intermediate rates of remission (44.5%) and ESRD (27.8%) compared to COLL and tip lesion. CELL variant may include cases of unsampled tip or COLL lesion, underscoring the importance of adequate sampling. Our data support the view that CELL and COLL FSGS are not equivalent and validates an approach to pathologic classification that distinguishes between COLL, CELL, and tip lesion variants of FSGS.

Immunofluorescence on pronase-digested paraffin sections: a valuable salvage technique for renal biopsies.

Direct immunofluorescence (IF) on frozen tissue is the method of choice for the study of medical renal diseases. When no glomeruli are available, IF can be performed on the formalin-fixed paraffin-embedded tissue allocated for light microscopy after antigen retrieval with proteases. In this study, the results of IF on frozen tissue (IF-F) and on deparaffinized, pronase-treated tissue (IF-P) were compared in 71 renal biopsies representing 12 major renal diseases. Using IF-P, diagnostic findings were obtained in 100% of cases of lupus nephritis, acute post-infectious glomerulonephritis, cryoglobulinemic glomerulonephritis, fibrillary glomerulonephritis, primary amyloidosis, myeloma cast nephropathy, and light-chain Fanconi syndrome (LCFS), 88% of cases of immunoglobulin (Ig)A nephropathy, 80% of cases of light-chain deposition disease, 60% of cases of membranoproliferative glomerulonephritis type 1, 50% of cases of idiopathic membranous glomerulopathy (MGN) and 20% of cases of anti-glomerular basement membrane (GBM) disease. IF-P was less sensitive than IF-F for the detection of C3 in all disease categories and for the detection of IgG in cases of MGN and anti-GBM disease. The diagnostic kappa light-chain staining was demonstrated in 100% of cases of LCFS by IF-P versus 40% by IF-F. We conclude that IF-P is a valuable salvage immunohistochemical technique for renal biopsies lacking adequate cortical sampling for IF-F, and is superior to IF-F for the diagnosis of LCFS.