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Human immunodeficiency virus (HIV) infection of kidney cells can lead to HIV-associated nephropathy (HIVAN) and aggravate the progression of other chronic kidney diseases. Thus, a better understanding of the mechanisms of HIV-induced kidney cell injury is needed for effective therapy against HIV-induced kidney disease progression. We have previously shown that the acetylation and activation of key inflammatory regulators, NF-κB p65 and STAT3, were increased in HIVAN kidneys. Here, we demonstrate the key role of sirtuin 1 (SIRT1) deacetylase in the regulation of NF-κB and STAT3 activity in HIVAN. We found that SIRT1 expression was reduced in the glomeruli of human and mouse HIVAN kidneys and that HIV-1 gene expression was associated with reduced SIRT1 expression and increased acetylation of NF-κB p65 and STAT3 in cultured podocytes. Interestingly, SIRT1 overexpression, in turn, reduced the expression of negative regulatory factor in podocytes stably expressing HIV-1 proviral genes, which was associated with inactivation of NF-κB p65 and a reduction in HIV-1 long terminal repeat promoter activity. In vivo, the administration of the small-molecule SIRT1 agonist BF175 or inducible overexpression of SIRT1 specifically in podocytes markedly attenuated albuminuria, kidney lesions, and expression of inflammatory markers in Tg26 mice. Finally, we showed that the reduction in SIRT1 expression by HIV-1 is in part mediated through miR-34a expression. Together, our data provide a new mechanism of SIRT1 regulation and its downstream effects in HIV-1-infected kidney cells and indicate that SIRT1/miR-34a are potential drug targets to treat HIV-related kidney disease.

The pathophysiology of human immunodeficiency virus (HIV)-associated cardiomyopathy remains uncertain. We used HIV-1 transgenic (Tg26) mice to explore mechanisms by which HIV-related proteins impacted on myocyte function. Compared to adult ventricular myocytes isolated from nontransgenic (wild type [WT]) littermates, Tg26 myocytes had similar mitochondrial membrane potential (ΔΨ m ) under normoxic conditions but lower Δ Ψ m after hypoxia/reoxygenation (H/R). In addition, Δ Ψ m in Tg26 myocytes failed to recover after Ca 2+ challenge. Functionally, mitochondrial Ca 2+ uptake was severely impaired in Tg26 myocytes. Basal and maximal oxygen consumption rates (OCR) were lower in normoxic Tg26 myocytes, and further reduced after H/R. Complex I subunit and ATP levels were lower in Tg26 hearts. Post-H/R, mitochondrial superoxide (O 2 •- ) levels were higher in Tg26 compared to WT myocytes. Overexpression of B-cell lymphoma 2-associated athanogene 3 (BAG3) reduced O 2 •- levels in hypoxic WT and Tg26 myocytes back to normal. Under normoxic conditions, single myocyte contraction dynamics were similar between WT and Tg26 myocytes. Post-H/R and in the presence of isoproterenol, myocyte contraction amplitudes were lower in Tg26 myocytes. BAG3 overexpression restored Tg26 myocyte contraction amplitudes to those measured in WT myocytes post-H/R. Coimmunoprecipitation experiments demonstrated physical association of BAG3 and the HIV protein Tat. We conclude: (a) Under basal conditions, mitochondrial Ca 2+ uptake, OCR, and ATP levels were lower in Tg26 myocytes; (b) post-H/R, Δ Ψ m was lower, mitochondrial O 2 •- levels were higher, and contraction amplitudes were reduced in Tg26 myocytes; and (c) BAG3 overexpression decreased O 2 •- levels and restored contraction amplitudes to normal in Tg26 myocytes post-H/R in the presence of isoproterenol.

HIV Transfer in Renal Transplantation despite ART In this case report, a low level of human immunodeficiency virus was shown to be transferred during transplantation of a kidney from an HIV-positiv...

Since highly active antiretroviral therapy improved long-term survival of acquired immunodeficiency syndrome (AIDS) patients, AIDS cardiomyopathy has become an increasingly relevant clinical problem. We used human immunodeficiency virus (HIV)-1 transgenic (Tg26) mouse to explore molecular mechanisms of AIDS cardiomyopathy. Tg26 mice had significantly lower left ventricular (LV) mass and smaller end-diastolic and end-systolic LV volumes. Under basal conditions, cardiac contractility and relaxation and single myocyte contraction dynamics were not different between wild-type (WT) and Tg26 mice. Ten days after open heart surgery, contractility and relaxation remained significantly depressed in Tg26 hearts, suggesting that Tg26 mice did not tolerate surgical stress well. To simulate heart failure in which expression of Bcl2-associated athanogene 3 (BAG3) is reduced, we down-regulated BAG3 by small hairpin ribonucleic acid in WT and Tg26 hearts. BAG3 down-regulation significantly reduced contractility in Tg26 hearts. BAG3 overexpression rescued contractile abnormalities in myocytes expressing the HIV-1 protein Tat. We conclude: (i) Tg26 mice exhibit normal contractile function at baseline; (ii) Tg26 mice do not tolerate surgical stress well; (iii) BAG3 down-regulation exacerbated cardiac dysfunction in Tg26 mice; (iv) BAG3 overexpression rescued contractile abnormalities in myocytes expressing HIV-1 protein Tat; and (v) BAG3 may occupy a role in pathogenesis of AIDS cardiomyopathy.

Background Little is known about the trends in the incidence and outcomes of patients with end-stage renal disease (ESRD) attributed to human immunodeficiency virus-associated nephropathy (HIVAN). We sought to define relative incidence among ESRD patients, changes in mortality among patients with ESRD attributed to HIVAN, as well as changes in the excess mortality experienced by patients with ESRD attributed to HIVAN compared with otherwise similar ESRD patients with non-HIVAN causes. Methods We used the US Renal Data System to identify all individuals with reported HIVAN who initiated treatment for ESRD between 1989 and 2011. We plotted their counts and proportions among all incident ESRD patients and tabulated their characteristics across years. We then compared mortality within the HIVAN group across years using Cox regression. In addition, we studied the trends in relative mortality of HIVAN patients versus those with ESRD not reported as HIVAN. Results Overall, 14 719 individuals with HIVAN-ESRD were recorded, with significant reductions in recent years (893 in 2006; 525 in 2011). Compared with patients initiating dialysis between 1989 and 1992, mortality declined by 40% (HR = 0.60; 95% CI, 0.55-0.65) and 64% (HR = 0.36; 95% CI, 0.32-0.40) for patients initiating dialysis in 1999/2000 and 2009-11, respectively. The adjusted excess mortality of HIVAN-ESRD patients versus incident ESRD patients from other causes was >5-fold in 1989-92 (HR = 5.21; 95% CI, 4.84-5.60); this excess mortality has subsequently declined but remained at almost 3-fold in recent years (e.g. HR = 2.58; 95% CI, 2.37-2.80, 2009-11 incidence cohort). Conclusions Concurrent with the increasing availability of highly active antiretroviral therapy (HAART), both the incidence of ESRD due to HIVAN and the mortality of such patients have decreased substantially. However, HIVAN patients reaching ESRD continue to experience substantial excess mortality compared with other ESRD patients even in the current era of modern HAART.

HIV-positive individuals are at increased risk for kidney disease, including HIV-associated nephropathy, non-collapsing focal segmental glomerulosclerosis, immune-complex kidney disease, and comorbid kidney disease, as well as kidney injury resulting from prolonged exposure to antiretroviral therapy or from opportunistic infections. Clinical guidelines for kidney disease prevention and treatment in HIV-positive individuals are largely extrapolated from studies in the general population, and do not fully incorporate existing knowledge of the unique HIV-related pathways and genetic factors that contribute to the risk of kidney disease in this population. We convened an international panel of experts in nephrology, renal pathology, and infectious diseases to define the pathology of kidney disease in the setting of HIV infection; describe the role of genetics in the natural history, diagnosis, and treatment of kidney disease in HIV-positive individuals; characterize the renal risk-benefit of antiretroviral therapy for HIV treatment and prevention; and define best practices for the prevention and management of kidney disease in HIV-positive individuals.

Mounting evidence suggests that epigenetic modification is important in kidney disease pathogenesis. To determine whether epigenetic regulation is involved in HIV-induced kidney injury, we performed genome-wide methylation profiling and transcriptomic profiling of human primary podocytes infected with HIV-1. Comparison of DNA methylation and RNA sequencing profiles identified several genes that were hypomethylated with corresponding upregulated RNA expression in HIV-infected podocytes. Notably, we found only one hypermethylated gene with corresponding downregulated RNA expression, namely regulator of calcineurin 1 (RCAN1). Further, we found that RCAN1 RNA expression was suppressed in glomeruli in human diabetic nephropathy, IgA nephropathy, and lupus nephritis, and in mouse models of HIV-associated nephropathy and diabetic nephropathy. We confirmed that HIV infection or high glucose conditions suppressed RCAN1 expression in cultured podocytes. This suppression was alleviated upon pretreatment with DNA methyltransferase inhibitor 5-Aza-2′-deoxycytidine, suggesting that RCAN1 expression is epigenetically suppressed in the context of HIV infection and diabetic conditions. Mechanistically, increased expression of RCAN1 decreased HIV- or high glucose–induced nuclear factor of activated T cells (NFAT) transcriptional activity. Increased RCAN1 expression also stabilized actin cytoskeleton organization, consistent with the inhibition of the calcineurin pathway. In vivo, knockout of RCAN1 aggravated albuminuria and podocyte injury in mice with Adriamycin-induced nephropathy. Our findings suggest that epigenetic suppression of RCAN1 aggravates podocyte injury in the setting of HIV infection and diabetic nephropathy.

Injury to the specialized epithelial cells of the glomerulus (podocytes) underlies the pathogenesis of all forms of proteinuric kidney disease; however, the specific genetic changes that mediate podocyte dysfunction after injury are not fully understood. Here, we performed a large-scale insertional mutagenic screen of injury-resistant podocytes isolated from mice and found that increased expression of the gene Rap1gap, encoding a RAP1 activation inhibitor, ameliorated podocyte injury resistance. Furthermore, injured podocytes in murine models of disease and kidney biopsies from glomerulosclerosis patients exhibited increased RAP1GAP, resulting in diminished glomerular RAP1 activation. In mouse models, podocyte-specific inactivation of Rap1a and Rap1b induced massive glomerulosclerosis and premature death. Podocyte-specific Rap1a and Rap1b haploinsufficiency also resulted in severe podocyte damage, including features of podocyte detachment. Over-expression of RAP1GAP in cultured podocytes induced loss of activated β1 integrin, which was similarly observed in kidney biopsies from patients. Furthermore, preventing elevation of RAP1GAP levels in injured podocytes maintained β1 integrin–mediated adhesion and prevented cellular detachment. Taken together, our findings suggest that increased podocyte expression of RAP1GAP contributes directly to podocyte dysfunction by a mechanism that involves loss of RAP1-mediated activation of β1 integrin.

Aortic Stenosis (AS) may result in maladaptive left ventricular (LV) remodeling. Wingless (Wnt) modulators have been shown to impact LV ejection fraction (LVEF) in patients with AS. In this study we investigated the additional role of podocan and its relationship with the Wnt-regulatory molecule

Human immunodeficiency virus-1 (HIV-1)-associated nephropathy (HIVAN) is a leading cause of end stage renal disease among HIV-1 seropositive patients with advanced HIV disease. Renal parenchymal features of HIVAN include focal segmental glomerulosclerosis, podocyte dedifferentiation and proliferation, tubular cell apoptosis, and tubular microcystic dilation [1]. With widespread use of combination anti-retroviral therapy (cART), the impact of HIVAN has been dramatically reduced [2, 3]. In spite of cART, however, some HIV-1 seropositive patients still progress to end stage renal failure. Furthermore, HIVAN remains a major health issue in Africa [4]. HIV-1 expression in the kidney epithelial cells is thought to be responsible for HIVAN pathogenesis [5]. When non-structural components of the HIV-1 genome [6] or the gene encoding for the HIV-1 accessory protein nef [7] were over-expressed in podocytes of transgenic mice, podocytes de-differentiated and acquired a proliferative phenotype. nef activates signal transducer and activator of transcription (STAT) 3 signaling and drives dedifferentiation and proliferation of cultured podocyte [8]. Consistent with this, STAT3 signaling is activated in podocytes of patients with HIVAN and the Tg26 murine model of HIVAN [8]. We demonstrated previously that Tg26 mice with global reduction of STAT3 activity were protected from the development of HIVAN, which suggests that STAT3 is required for podocyte proliferation [9]. However, since STAT3 expression is ubiquitous and reduction of STAT3 activity in our previous murine model was not cell specific, we could not distinguish the relative importance of STAT3 in different cell types (i.e. kidney vs. infiltrating inflammatory cells) for HIVAN pathogenesis. Here, we specifically examined the role of podocyte STAT3 on the development of HIVAN.

Despite intensive antihypertensive therapy there was a high incidence of renal end points in participants of the African American Study of Kidney Disease and Hypertension (AASK) cohort. To better understand this, coding variants in the apolipoprotein L1 ( APOL1 ) and the nonmuscle myosin heavy chain 9 ( MYH9 ) genes were evaluated for an association with hypertension-attributed nephropathy and clinical outcomes in a case–control study. Clinical data and DNA were available for 675 AASK participant cases and 618 African American non-nephropathy control individuals. APOL1 G1 and G2, and MYH9 E1 variants along with 44 ancestry informative markers, were genotyped with allele frequency differences between cases and controls analyzed by logistic regression multivariable models adjusting for ancestry, age, and gender. In recessive models, APOL1 risk variants were significantly associated with kidney disease in all cases compared to controls with an odds ratio of 2.57. In AASK cases with more advanced disease, such as a baseline urine protein to creatinine ratio over 0.6g/g or a serum creatinine over 3mg/dl during follow-up, the association was strengthened with odds ratios of 6.29 and 4.61, respectively. APOL1 risk variants were consistently associated with renal disease progression across medication classes and blood pressure targets. Thus, kidney disease in AASK participants was strongly associated with APOL1 renal risk variants.

A chromosome 22q13 locus strongly associates with increased risk for idiopathic focal segmental glomerulosclerosis (FSGS), HIV-1-associated nephropathy (HIVAN), and hypertensive ESRD among individuals of African descent. Although initial studies implicated MYH9, more recent analyses localized the strongest association within the neighboring APOL1 gene. In this replication study, we examined the six top-most associated variants in APOL1 and MYH9 in an independent cohort of African Americans with various nephropathies (44 with FSGS, 21 with HIVAN, 32 with IgA nephropathy, and 74 healthy controls). All six variants associated with FSGS and HIVAN (additive ORs, 1.8 to 3.0; P values 3 × 10−2 to 5 × 10−5) but not with IgA nephropathy. In conditional and haplotype analyses, two APOL1 haplotypes accounted for virtually all of the association with FSGS and HIVAN on chromosome 22q13 (haplotype P value = 5.6 × 10−8). To assess the role of MYH9 deficiency in nephropathy, we crossbred Myh9-haploinsufficient mice (Myh9+/−) with HIV-1 transgenic mice. Myh9+/− mice were healthy and did not demonstrate overt proteinuria or nephropathy, irrespective of the presence of the HIV-1 transgene. These data further support the strong association of genetic variants in APOL1 with susceptibility to FSGS and HIVAN among African Americans.

All-trans retinoic acid protects against the development of HIV-associated nephropathy (HIVAN) in HIV-1 transgenic mice (Tg26). In vitro, all-trans retinoic acid inhibits HIV-induced podocyte proliferation and restores podocyte differentiation markers by activating its receptor-α (RARα). Here, we report that Am580, a water-soluble RARα-specific agonist, attenuated proteinuria, glomerosclerosis, and podocyte proliferation, and restored podocyte differentiation markers in kidneys of Tg26 mice. Furthermore, RARα−/− Tg26 mice developed more severe kidney and podocyte injury than did RARα+/− Tg26 mice. Am580 failed to ameliorate kidney injury in RARα−/− Tg26 mice, confirming our hypothesis that Am580 acts through RARα. Although the expression of RARα-target genes was suppressed in the kidneys of Tg26 mice and of patients with HIVAN, the expression of RARα in the kidney was not different between patients with HIVAN and minimal change disease. However, the tissue levels of retinoic acid were reduced in the kidney cortex and isolated glomeruli of Tg26 mice. Consistent with this, the expression of two key enzymes in the retinoic acid synthetic pathway, retinol dehydrogenase type 1 and 9, and the overall enzymatic activity for retinoic acid synthesis were significantly reduced in the glomeruli of Tg26 mice. Thus, a defect in the endogenous synthesis of retinoic acid contributes to loss of the protection by retinoic acid in HIVAN. Hence, RARα agonists may be potential agents for the treatment of HIVAN.

Background Lipodystrophy in HIV type-1 (HIV-1)-infected patients is the consequence of effects originating from antiretroviral treatment and HIV-1 infection. We have studied adipose tissues and circulating parameters in mice bearing the HIV-1 transgene as a model to provide insight into the role of HIV-1-infection-related events in fat alterations. Methods Heterozygous transgenic mice expressing a 7.7 kb HIV-1 construct (Tg26+/-) were used. Cytokine and adipokine levels were quantified using multiplex procedures. Gene expression and mitochondrial DNA abundance in visceral and subcutaneous white adipose tissues and in brown fat were determined using quantitative real-time PCR. Results The amount of visceral, but not subcutaneous, adipose depot was lower in Tg26+/- mice. Serum proinflammatory cytokine levels were increased in Tg26+/-mice, whereas adiponectin and leptin levels were reduced. Gene expression of monocyte chemoattractant protein-1 was induced in visceral and subcutaneous fat, whereas tumour necrosis factor-α and interleukin-6 were induced in visceral and subcutaneous white adipose tissues, respectively. Adiponectin and leptin gene expression was repressed in all white fat depots, in concert with reduced expression of peroxisome proliferator-activated receptor γ, a master controller of adipogenesis. In brown fat, a coordinate induction in the expression of thermogenesis marker genes was observed. Conclusions HIV-1 transgene expression in mice causes changes in adipose tissue reminiscent of those in patients with HIV-1 lipodystrophy, particularly early pretreatment changes. These data support a role for HIV-1-infection-related events in eliciting adipose tissue dysfunction. The Tg26+/- mouse appears as a promising model to assess the effects of HIV-1 infection on adipose tissue and for determining the effects of antiretroviral drugs on an HIV-1-infected background.

Focal segmental glomerulosclerosis (FSGS) is a leading cause of nephrotic syndrome and end-stage renal disease worldwide. Although the mechanisms underlying this important disease are poorly understood, the glomerular podocyte clearly plays a central role in disease pathogenesis. In the current work, we demonstrate that the homophilic adhesion molecule sidekick-1 (sdk-1) is up-regulated in podocytes in FSGS both in rodent models and in human kidney biopsy samples. Transgenic mice that have podocyte-specific overexpression of sdk-1 develop gradually progressive heavy proteinuria and severe FSGS. We also show that sdk-1 associates with the slit diaphragm linker protein MAGI-1, which is already known to interact with several critical podocyte proteins including synaptopodin, alpha-actinin-4, nephrin, JAM4, and beta-catenin. This interaction is mediated through a direct interaction between the carboxyl terminus of sdk-1 and specific PDZ domains of MAGI-1. In vitro expression of sdk-1 enables a dramatic recruitment of MAGI-1 to the cell membrane. Furthermore, a truncated version of sdk-1 that is unable to bind to MAGI-1 does not induce podocyte dysfunction when overexpressed. We conclude that the up-regulation of sdk-1 in podocytes is an important pathogenic factor in FSGS and that the mechanism involves disruption of the actin cytoskeleton possibly via alterations in MAGI-1 function.

Induction of type I interferons (IFN) is a central feature of innate immune responses to microbial pathogens and is mediated via Toll-like receptor (TLR)-dependent and -independent pathways. Prothymosin-α (ProTα), a small acidic protein produced and released by CD8 + T cells, inhibits HIV-1, although the mechanism for its antiviral activity was not known. We demonstrate that exogenous ProTα acts as a ligand for TLR4 and stimulates type I IFN production to potently suppress HIV-1 after entry into cells. These activities are induced by native and recombinant ProTα, retained by an acidic peptide derived from ProTα, and lost in the absence of TLR4. Furthermore, we demonstrate that ProTα accounts for some of the soluble postintegration HIV-1 inhibitory activity long ascribed to CD8 + cells. Thus, a protein produced by CD8 + T cells of the adaptive immune system can exert potent viral suppressive activity through an innate immune response. Understanding the mechanism of IFN induction by ProTα may provide therapeutic leads for IFN-sensitive viruses.

HIV-associated nephropathy (HIVAN) is the most common cause of end-stage renal disease in persons with HIV/AIDS and is characterized by focal glomerulosclerosis and dysregulated renal tubular epithelial cell (RTEC) proliferation and apoptosis. HIV-1 viral protein r (Vpr) has been implicated in HIV-induced RTEC apoptosis but the mechanisms of Vpr-induced RTEC apoptosis are unknown. The aim of this study was therefore to determine the mechanisms of Vpr-induced apoptosis in RTEC.Apoptosis and caspase activation were analyzed in human RTEC (HK2) after transduction with Vpr-expressing and control lentiviral vectors. Bax and BID were inhibited with lentiviral shRNA, and ERK activation was blocked with the MEK1,2 inhibitor, U0126.Vpr induced apoptosis as indicated by caspase 3/7 activation, PARP-1 cleavage and mitochondrial injury. Vpr activated both caspases-8 and 9. Inhibition of Bax reduced Vpr-induced apoptosis, as reported in other cell types. Additionally, Vpr-induced cleavage of BID to tBID and suppression of BID expression prevented Vpr-induced apoptosis. Since sustained ERK activation can activate caspase-8 in some cell types, we studied the role of ERK in Vpr-induced caspase-8 activation. Vpr induced sustained ERK activation in HK2 cells and incubation with U0126 reduced Vpr-induced caspase-8 activation, BID cleavage and apoptosis. We detected phosphorylated ERK in RTEC in HIVAN biopsy specimens by immunohistochemistry.These studies delineate a novel pathway of Vpr-induced apoptosis in RTEC, which is mediated by sustained ERK activation, resulting in caspase 8-mediated cleavage of BID to tBID, thereby facilitating Bax-mediated mitochondrial injury and apoptosis.

Human immunodeficiency virus (HIV)-associated nephropathy is a significant cause of morbidity and mortality in HIV-infected persons. Vpr-induced cell cycle dysregulation and apoptosis of renal tubular epithelial cells are important components of the pathogenesis of HIV-associated nephropathy (HIVAN). FAT10 is a ubiquitin-like protein that is upregulated in renal tubular epithelial cells in HIVAN. In these studies, we report that Vpr induces increased expression of FAT10 in tubular cells and that inhibition of FAT10 expression prevents Vpr-induced apoptosis in human and murine tubular cells. Moreover, we found that Vpr interacts with FAT10 and that these proteins colocalize at mitochondria. These studies establish FAT10 as a novel mediator of Vpr-induced cell death.

HIV-associated nephropathy (HIVAN) is a major cause of HIV-related morbidity and mortality. Transgenic and infectious models of HIVAN faithfully recapitulate the human disease and are important tools in advancing our understanding of disease pathogenesis, genetic susceptibility, and therapeutic intervention beyond the inhibition of viral replication. This review discusses the available transgenic murine models and infectious models of HIVAN in mice, rats, nonhuman primates, and felines. Particular emphasis is given to cell type-specific HIV expression as well as partial HIV genome expression used to map HIV-1 Nef and Vpr as pathologic determinants.

With prolonged survival and aging of the HIV-infected population in the era of antiretroviral therapy, biopsy series have found a broad spectrum of HIV-related and co-morbid kidney disease in these patients. Our study describes the variety of renal pathology found in a prospective cohort of antiretroviral-experienced patients (the Manhattan HIV Brain Bank) who had consented to postmortem organ donation. Nearly one-third of 89 kidney tissue donors had chronic kidney disease, and evidence of some renal pathology was found in 75. The most common diagnoses were arterionephrosclerosis, HIV-associated nephropathy and glomerulonephritis. Other diagnoses included pyelonephritis, interstitial nephritis, diabetic nephropathy, fungal infection and amyloidosis. Excluding 2 instances of acute tubular necrosis, slightly over one-third of the cases would have been predicted using current diagnostic criteria for chronic kidney disease. Based on semi-quantitative analysis of stored specimens, pre-mortem microalbuminuria testing could have identified an additional 12 cases. Future studies are needed to evaluate the cost-effectiveness of more sensitive methods for defining chronic kidney disease, in order to identify HIV-infected patients with early kidney disease who may benefit from antiretroviral therapy and other interventions known to delay disease progression and prevent complications.

NACh is a nucleic acid-conducting channel found in apical membrane of rat kidney proximal tubules. It is a heteromultimeric complex consisting of at least two proteins: a 45-kDa pore-forming subunit and a 36-kDa regulatory subunit. The regulatory subunit confers ion selectivity and influences gating kinetics. The regulatory subunit has been identified as cytosolic malate dehydrogenase (cMDH). cMDH is described in the literature as a soluble protein that is not associated with plasma membrane. Yet a role for cMDH as the regulatory subunit of NACh requires that it be present at the plasma membrane. To resolve this conflict, studies were initiated to determine whether cMDH could be found at the plasma membrane. Before performing localization studies, a suitable model system that expressed NACh was identified. A channel was identified in LLC-PK(1) cells, a line derived from pig proximal tubule, that is selective for nucleic acid and has a conductance of approximately 10 pS. It exhibits dose-dependent blockade by heparan sulfate or L-malate. These characteristics are similar to what has been reported for NACh from rat kidney and indicate that NACh is present in LLC-PK(1) cells. LLC-PK(1) cells were therefore used as a model system for immunolocalization of cMDH. Both immunofluorescence and immunoelectron microscopy demonstrated cMDH at the plasma membrane of LLC-PK(1) cells. This finding supports prior functional data that describe a role for cMDH as the regulatory subunit of NACh.

Background In the era of antiretroviral therapy, non-AIDS complications such as kidney disease are important contributors to morbidity and mortality. Objective To estimate the impact of hepatitis C coinfection on the risk of kidney disease in HIV patients. Design and methods Two investigators identified English-language citations in MEDLINE and Web of Science from 1989 through 1 July 2007. References of selected articles were reviewed. Observational studies and clinical trials of HIV-related kidney disease and antiretroviral nephrotoxicity were eligible if they included at least 50 subjects and reported hepatitis C status. Data on study characteristics, population, and kidney disease outcomes were abstracted by two independent reviewers. Results After screening 2516 articles, 27 studies were eligible and 24 authors confirmed or provided data. Separate meta-analyses were performed for chronic kidney disease outcomes (n = 10), proteinuria (n = 4), acute renal failure (n = 2), and indinavir toxicity (n = 5). The pooled incidence of chronic kidney disease was higher in patients with hepatitis C coinfection [6.2 versus 4.0%; relative risk 1.49, 95% confidence interval (CI) 1.08-2.06]. In meta-regression, prevalence of black race and the proportion of patients with documented hepatitis C status were independently associated with the risk of chronic kidney disease. The relative risk associated with hepatitis C coinfection was significantly increased for proteinuria (1.15; 95% CI 1.02-1.30) and acute renal failure (1.64; 95% CI 1.21-2.23), with no significant statistical heterogeneity. The relative risk of indinavir toxicity was 1.59 (95% CI 0.99-2.54) with hepatitis C coinfection. Conclusion Hepatitis C coinfection is associated with a significant increase in the risk of HIV-related kidney disease.

HIV-associated nephropathy (HIVAN) is characterized by collapsing FSGS. Because transgenic mice with podocyte-specific overexpression of the vascular endothelial growth factor 164 (VEGF164) isoform also develop collapsing FSGS, we sought to determine whether VEGF plays a role in HIVAN. Compared with controls, immunohistochemistry revealed that kidneys from HIV-1-transgenic mice (Tg26) and from patients with HIVAN had greater expression of both VEGF and its transcriptional regulator, hypoxia-inducible factor 2alpha (HIF-2alpha). Similarly, mRNA and protein levels of VEGF and HIF-2alpha were increased in HIV-infected podocytes in vitro, and this transcriptional upregulation was found to be stimulated by the HIV viral protein Nef in a Src kinase-and Stat3-dependent manner. HIV-1 also upregulated VEGFR2 and its co-receptor neuropilin-1 and suppressed the expression of semaphorin 3a in the podocyte. Exogenous VEGF stimulated proliferation and de-differentiation of podocytes, which are features of collapsing FSGS, and VEGFR2 neutralizing antibodies reversed these features in podocytes infected with HIV-1 or isolated from Tg26 mice. In conclusion, HIV-1 induces VEGF and VEGFR2 expression in podocytes, and this may be a critical step in the pathogenesis of HIVAN.

HIV-associated nephropathy (HIVAN) is the leading cause of end-stage renal failure in HIV-1 seropositive patients. The pathologic findings include collapsing focal segmental glomerulosclerosis with proliferation of epithelial cells in Bowman’s space. Anatomically, these cells correspond to podocytes and exhibit a unique phenotype with loss of many differentiation markers including synaptopodin and dysregulation of the cell cycle markers consistent with proliferation. Podocyte dysfunction appears to be a direct result of HIV-1 protein expression, specifically Nef and Vpr as well as specific host factors that have yet to be elucidated. The mechanism by which Nef induces podocyte proliferation and dedifferentiation has been traced to its ability to activate several signaling pathways including Src-Stat3 and ras-raf-MAPK1, 2. Activation of the cAMP/PKA pathway with all-trans-retinoic acid appears to modulate these changes and returns podocytes to a differentiated, nonproliferating phenotype.

The important role of CD8(+) T cells in controlling HIV-1 infection through the innate as well as the adaptive immune system is well established. In addition to the major histocompatibility complex (MHC)-dependent cytotoxic activity of CD8(+) T cells, they produce soluble factors that suppress HIV-1 replication in an MHC-independent manner. Several of those factors have been identified, including beta-chemokines, Rantes, MIP-1alpha, MIP-1beta, and MDC. We previously identified that prothymosin alpha (ProTalpha) in the conditioned medium of HVS transformed CD8(+) T cells was a potent inhibitor of HIV-1 replication following proviral integration. In this report we further characterize the anti-HIV-1 activity of ProTalpha by demonstrating its target-cell specificity, distinction from additional inhibitors of HIV-1 transcription in CD8(+) T cell supernatants, as well as the differential regulation of host cell antiviral genes that could impact HIV-1 replication. These genes include a number of transcription factors as well IFN-alpha-inducible genes including PKR, IRF1, and Rantes, in the absence of induction of IFN-alpha. These data suggest that the anti-HIV-1 activity of ProTalpha is mediated through the modulation of a number of genes that have been reported to suppress HIV-1 replication including the dysregulation of transcription factors and the induction of PKR and Rantes mRNA.

Background: Kidney disease is an increasingly important complication of HIV. Objectives: To examine the incidence and predictors of acute renal failure before and after the introduction of HAART, and the impact of acute renal failure on in-hospital mortality in the post-HAART era. Methods: Adults hospitalized in acute care hospitals in New York State during 1995 (pre-HAART) or 2003 (post-HAART) were identified from the state Planning and Research Cooperative System database. HIV status was defined by primary or secondary diagnosis code. The impact of HIV and HAART on the incidence of acute renal failure and mortality, and the impact of acute renal failure on mortality, was assessed using Χ 2 analysis and multivariate regression. Results: There were 52 580 HIV-infected patients discharged from hospital in 1995 and 25 114 in 2003. Compared with uninfected patients, HIV-infected patients had an increased incidence of acute renal failure in both the pre-HAART [adjusted odds ratio (OR), 4.62; 95% confidence interval (Cl), 4.30-4.95] and post-HAART eras (adjusted OR, 2.82; 95% Cl, 2.66-2.99). In the post-HAART cohort, acute renal failure was associated with traditional predictors such as age, diabetes mellitus, and chronic kidney disease, as well as acute or chronic liver failure or hepatitis coinfection (P < 0.001 for all comparisons). Acute renal failure was associated with mortality among HIV-infected patients in the post-HAART era (OR, 5.83; 95% Cl, 5.11-6.65). Conclusions: Acute renal failure remains common among hospitalized patients with HIV and is associated with chronic kidney disease, liver disease, and increased mortality.

The clinical epidemiology and course of the spectrum of renal diseases associated with HIV infection. Background While an understanding of the epidemiology and clinical course of HIV-associated nephropathy (HIVAN) is growing, little is known about the risk factors and clinical course of the other renal diseases that may also occur as a complication of HIV infection. This study was undertaken to compare HIVAN to the spectrum of other kidney diseases seen among HIV-infected patients. Methods This retrospective cohort study included all HIV-infected patients who underwent renal biopsy during the course of their clinical care at six major medical centers. Demographic and clinical information were abstracted from each patient's clinical record. Time to initiation of renal replacement therapy was compared for patients with lesions other than HIVAN to patients with HIVAN using Cox proportional hazards regression. Results Eighty-nine patients (47 with lesions other than HIVAN and 42 with HIVAN) were available for inclusion. Patients with lesions other than HIVAN were less likely to be black (37/47 vs. 42/42, P = 0.02), more likely to have a positive hepatitis B surface antigen (10/37 vs. 4/42, P = 0.04), less likely to have the diagnosis of hypertension (24/46 vs. 31/42, P = 0.03), more likely to have a greater creatinine clearance at time of biopsy (60.6 vs. 39.0 cc/min, P = 0.008), and have a greater CD4 lymphocyte count at time of biopsy (287 vs. 187 cells/mL, P = 0.04) compared to patients with HIVAN. Lesions other than HIVAN were associated with a longer time to initiation of renal replacement therapy compared with HIVAN (HR 0.33, 95% CI 0.15-0.71, P = 0.005). Other factors associated with a longer time to renal replacement therapy included higher creatinine clearance at time of biopsy, greater CD4 + lymphocyte count, the absence of hepatitis C antibody, and the use of an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker. The type of renal disease (HIVAN vs. other) interacted significantly with HIV-1 RNA level and the use of antiretroviral therapy ( P = 0.0001 and 0.006, respectively). Among patients with lesions other than HIVAN, the presence of nondetectable HIV-1 RNA was not associated with a greater risk of progression of renal disease (HR 0.27, P = 0.24). Among patients with HIVAN, because all patients had detectable virus at the time of institution of renal replacement therapy, this highly significant association could not be quantified. Among patients with lesions other than HIVAN, the use of antiretroviral therapy was not associated with the progression to renal replacement therapy (HR 3.29, P = 0.06). Among patients with HIVAN, the use of antiretroviral therapy was associated with a slower progression to renal replacement therapy (HR 0.24, P = 0.03). Conclusion Among HIV-infected patients with renal disease other than HIVAN, viral suppression and the use of antiretroviral therapy are not associated with a beneficial effect on renal function; thus, additional therapeutic strategies may need to be utilized. Because renal histology is associated with prognostic differences, these data provide outcomes information that will improve the clinical utility of renal biopsy among HIV-infected patients with renal disease.

Critical role for Nef in HIV-1–induced podocyte dedifferentiation. The notable glomerular feature of human immunodeficiency virus (HIV)-associated nephropathy (HIVAN) is the collapse of the capillary tuft with marked glomerular epithelial cell hyperplasia. These data suggest a loss of normal podocyte function, which is associated with a loss of the podocyte differentiation markers, Wilm's tumor (WT-1), synaptopodin, podocalyxin, and common acute lymphoblastic leukemia antigen (CALLA). We have previously shown that HIV-1 expression can induce these changes in HIV-1 transgenic mice. To identify which HIV-1 gene product(s) are responsible for the phenotypic changes in podocytes, we created multiple mutated HIV-1 constructs and then pseudotyped them with vesticular stomatitis virus glycoprotein (VSVG) envelope to enhance the tropism of these mutant viruses. In addition to gag/pol, the mutant viruses lacked one of the following, env, nef, rev, vif, vpr, or vpu. In addition, we generated single gene expressing pseudotyped viruses to complement the scanning mutation approach of our viral parental construct. Murine podocytes were then infected with one of the viral constructs either lacking or expressing the various HIV-1 genes. We found that HIV-1 nef was necessary and sufficient for proliferation of podocytes and down-regulation of synaptopodin and CALLA. These data suggest that Nef induces many of the changes we observe in HIV transgenic model and, as a result, this now defines the pathway for exploration of host responses to HIV-1 infection.

The classic kidney disease of HIV infection, HIV-associated nephropathy (HIVAN), is an aggressive form of collapsing focal segmental glomerulosclerosis with accompanying tubular and interstitial lesions. HIVAN was first described among African-Americans and Haitian immigrants with advanced HIV disease, an early suggestion of a strong genetic association. This genetic susceptibility was recently linked to polymorphisms on chromosome 22 in individuals of African descent. The association with advanced HIV infection and evidence from HIV-transgenic mice suggested the possibility that HIV directly infects the kidney and that specific HIV gene expression induces host cellular pathways that are responsible for HIVAN pathogenesis. Although combination antiretroviral therapy has substantially reduced the impact of HIVAN in the United States, continued growth of the HIV epidemic in susceptible African populations may have important public health implications. This article reviews recent progress in the pathogenesis...

Background: Rhesus monkeys have a high prevalence of obesity and spontaneous type 2 diabetes mellitus after the age of 10 years. These monkeys go through a defined, sequential set of metabolic phases, including fasting hyperinsulinemia, impaired glucose tolerance, and fasting hyperglycemia. Using these monkeys, we addressed the hypothesis that renal structural features characteristic of diabetic nephropathy might precede the appearance of overt diabetes. Methods: We carried out a quantitative analysis of renal tissue, using light microscopy and electron microscopy, from 6 metabolically normal young monkeys, 7 metabolically normal aged monkeys, 7 hyperinsulinemic monkeys, and 18 diabetic monkeys. Results: Glomerular volume was increased significantly in hyperinsulinemic monkeys and diabetic monkeys compared with aged normal monkeys. In the normal monkey, glomerular basement membrane (GBM) width rises with age but reaches a plateau at about 20 years of age; the presence of diabetes was associated with markedly increased GBM width. Glomerular tuft volume and GBM width were correlated most closely with age and with glucose tolerance. Conclusion: Diabetic monkey kidneys are characterized by glomerular enlargement, glomerulosclerosis, and thickening of the GBM. Glomerular hypertrophy begins in the prediabetic hyperinsulinemic phase. This finding suggests that early intervention may be required in human patients to preserve normal glomerular structure. Am J Kidney Dis 40:1075-1085. © 2002 by the National Kidney Foundation, Inc.

HIV-associated nephropathy (HIVAN) is now the third leading cause of end-stage renal disease in the African American population. HIV-1 infects renal tubular and glomerular epithelial cells or podocytes, cells that are a critical part of the filtration barrier. HIV-1 infection induces the loss of podocyte differentiation markers and increases podocyte proliferation. It has been previously shown that HIV-infection induces loss of contact inhibition. Here, the HIV-1 gene responsible for proliferative changes is identified by using cultured podocytes in vitro. The HIV-1 proviral construct, pNL4-3 was rendered noninfectious by replacing the HIV-1 gag/pol sequences with an EGFP reporter gene (pNL4-3: DeltaG/P-EGFP). This construct was then pseudotyped with VSV.G envelope to infect podocytes that were conditionally immortalized with SV-40 T antigen. In addition, mutated constructs were engineered with premature stop codons in the HIV-1 env, vif, vpr, vpu, nef, or rev genes. The parental construct and all the other mutated constructs, with the exception of nef, induced proliferation under nonpermissive conditions and anchorage-independent growth (colony formation in soft agar) under permissive conditions. In contrast, deletion of nef markedly reduced proliferation and colony formation. Although tat alone, or tat plus rev induced marginal levels of anchorage-independent growth, coexpression with nef significantly increased colony formation. Finally, stable expression of Nef in a retroviral vector, pBabe-puro, was sufficient to induce increased proliferation and colony formation. Moreover, nef induced saturation density and loss of contact inhibition. These data indicate that Nef induces multiple proliferative effects in podocytes in culture and that nef may therefore be an important gene in the pathogenesis of HIVAN in vivo.

We have described previously a cell surface channel that is highly selective for nucleic acids. Nucleic acid conductance is 10 pS and the channel is at least 10,000-fold more selective for oligodeoxynucleotides than any anion tested (1). Herein we provide evidence that the nucleic acid-conducting channel (NACh) is a heteromultimeric complex of at least two proteins; a 45-kDa pore-forming subunit (p45) and a 36-kDa regulatory subunit (p36). Reconstitution of p45 in planar lipid bilayers resulted in formation of a channel which gated in the absence of nucleic acid and which was more selective for anions (including oligonucleotide) than cations. This channel exhibited transitions from one level of current to another (or to the closed state); however the incidence of transitions was rare. Channel activity was not observed when p36 was reconstituted alone. Reconstitution of p36 with p45 restored nucleic acid dependence and selectivity to the channel. Protein sequence analysis identified p36 as cytosolic malate dehydrogenase (cMDH). Experiments were performed to prove that cMDH is a regulatory subunit of NACh. Selective activity was observed when p45 was reconstituted with pig heart cMDH but not with mitochondrial MDH. Both the enzyme substrate l -malate and antiserum raised against cMDH block NACh activity. These data demonstrate that a nucleic acid conducting channel is a complex of at least two proteins, p45 and cMDH. Furthermore, these data establish that cMDH confers nucleic acid selectivity of the channel.

Polarity of α-galactosidase A uptake by renal tubule cells. Background Congenital absence of α-galactosidase in Fabry disease leads eventually to renal failure. Fabry disease is an attractive candidate for gene therapy, but uptake mechanisms of the enzyme must be understood for it to be used in treating patients with Fabry disease. Methods Immortalized human renal epithelial cells from three regions of the tubule were grown in culture on collagen-coated Transwell filters and were incubated with recombinant α-galactosidase protein placed at either the luminal or basolateral side of the cells. Uptake into cells was measured, and kinetic studies were performed. Blocking experiments were done with mannose 6-phosphate. Results Uptake from the basolateral side of the filters predominated in all three cell types. Only in distal tubule cells was mannose 6-phosphate able to block uptake to any degree. The kinetic data reveal a high K m for both luminal and basolateral cell surfaces. Conclusions These data suggest that to correct the renal phenotype in Fabry disease, high levels of the enzyme will be need to be delivered to kidney cells. This will likely best be achieved with local administration of a vector containing the transgene directly to the kidney.

Human immunodeficiency virus-associated nephropathy (HIVAN) is the most common form of chronic renal disease in HIV-1-seropositive patients. Over 85% of cases of HIVAN occur in African-American patients and it is the third leading cause of ESRD in blacks age 20 to 64. Changes in incidence rates of HIVAN have coincided with changes in AIDS incidence rates. The demographics of the AIDS/HIV-1 epidemic indicate that the risk pool for HIVAN will continue to grow and that urban Nephrology centers will continue to see high rates of HIVAN. In addition, improvements in survival rates of HIV-1-seropositive patients on hemodialysis and improved treatment of HIVAN with highly active antiretroviral therapy (HAART) and angiotensin-converting enzyme (ACE)-inhibitors will result in an increased prevalence of HIVAN in the end-stage renal disease (ESRD) and pre-ESRD patient populations.

Human immunodeficiency virus type 1 (HIV-1)-seropositive patients are at risk for the development of a variety of acute and chronic renal diseases. The most common cause of chronic renal failure in HIV-1-seropositive patients is HIV-associated nephropathy (HIVAN). HIVAN occurs almost exclusively in black patients and the majority of published cases are of patients who present with acquired immunodeficiency syndrome (AIDS). This disease is currently the third leading cause of end-stage renal disease in blacks aged 20-64. Because HIV-1-seropositive patients may develop a wide variety of acute and chronic renal diseases, definitive diagnosis requires renal biopsy. Emerging data suggest a direct role of HIV-1 infection of kidney cells in the pathogenesis of HIVAN. There have been no well-controlled clinical trials in the treatment of HIVAN. The therapeutic agents with the most promise are angiotensin-converting enzyme inhibitors and antiretroviral medications. Long-term renal prognosis may be changing in the setting of improved aggressive antiretroviral therapy. Patient survival is determined primarily by the stage of HIV-1 infection. In this article, we present the case history of a patient who developed HIVAN. We then review the current literature concerning the epidemiology, differential diagnosis, etiology, and treatment of HIVAN.

Glomerulosclerosis and viral gene expression in HIV-transgenic mice: Role of nef. Background Human immunodeficiency virus (HIV)-associated nephropathy is characterized by focal segmental glomerulosclerosis and microcystic tubular dilation. We have previously described a mouse transgenic for a δ gag-pol HIV-1 genome, which develops glomerulosclerosis, cutaneous papillomas, and cataracts. Methods We developed mice transgenic for a δ gag-pol-nef HIV genome in order to investigate the role of the nef gene in these phenotypes. Results One transgenic line, X5, expressed HIV mRNA in kidney and consistently manifested focal segmental glomerulosclerosis and tubular dilation by six weeks of age. Northern analysis indicated that renal transgene expression was higher in the δ gag-pol-nef mice compared with the δ gag-pol mice. In situ hybridization and immunostaining demonstrated HIV RNA and protein expression within the glomerular epithelial cells and tubular epithelial cells. These cell types showed histologic evidence of toxicity, including vacuolation and detachment from basement membrane, and exhibited increased rates of apoptosis. These data suggest that the renal disease seen in the δ gag-pol-nef transgenic mouse may be caused by the expression of HIV genes within renal epithelial cells, that this expression may induce cellular toxicity, including apoptosis, and that nef is not required for the induction of renal disease. We have previously described mice bearing the nef gene, which do not manifest renal disease. In further experiments, δ gag-pol-nef mice were bred with nef mice; these dual-transgenic mice developed renal disease that generally resembled that seen in δ gag-pol-nef mice, but with somewhat more severe glomerulosclerosis and less severe tubulointerstitial injury. Results The results of these transgenic studies suggest that the role of nef is complex and may act both to reduce transgene expression and to potentiate glomerular injury induced by other HIV-1 gene products.

HIV-1 induces renal epithelial dedifferentiation in a transgenic model of HIV-associated nephropathy. Background Human immunodeficiency virus-associated nephropathy (HIVAN) is the most common cause of renal failure in HIV-1–seropositive patients. Recent studies using an HIV-1 transgenic mouse model have demonstrated that expression of HIV-1 in the kidney is required for the development of HIVAN. What has remained unclear, however, is the renal cell type responsible for pathogenesis and the essential pathological process. Methods To address these issues, we used a transgenic murine model of HIVAN. We identified the cell types in kidney in which HIV transgene expression occurs using in situ hybridization. We evaluated evidence of proliferation by immunocytochemical analysis using an antibody to Ki-67 and cell type-specific markers, including WT-1, synaptopodin, Na + ,K + -ATPase, adducin, and desmin. TUNEL assay was used to evaluate apoptosis. Results We found that glomerular and tubular epithelial cells express the HIV-1 transgene early in the disease process when renal architecture is well preserved. Transgene expression is lost, however, in tubular epithelial cells when they lose their differentiated cuboidal phenotype. In glomerular epithelial cells, dedifferentiation occurs with reduced expression of WT-1 and synaptopodin, in association with activation of desmin expression. Tubular microcysts also form with mislocalization of Na + ,K + -ATPase expression to the lateral and apical cellular membranes. Conclusions These studies support the hypothesis that the glomerular and renal epithelial cells are the primary targets of HIV-1 pathogenesis in the kidney. The essential pathologic process is dysregulation of the epithelial cell cycle with increased proliferation, apoptosis, cellular dedifferentiation, and altered cellular polarity.

There has been an increasing interest recently in the possibility of treating renal diseases using gene therapy. The ability to pursue gene therapy for renal diseases has been limited by the availability of an adequate system for gene delivery to the kidney. Adeno-associated virus (AAV) is a defective virus of the parvovirus family that has a number of properties attractive for renal gene delivery: recombinant AAV contains no viral genes; expression of genes delivered by these vectors does not activate cell-mediated immunity; the virus is able to transduce nondividing as well as dividing cells; and both wild-type and recombinant AAV integrate into the host chromosome resulting in long-term gene expression. Studies were performed to determine whether AAV can deliver reporter genes to kidney cells in vitro and in vivo. These studies show that AAV can deliver reporter genes with approximately equal efficiency to human mesangial, proximal tubule, thick ascending limb, collecting tubule, and renal cell carcinoma cells in primary culture. Immortalized mouse mesangial cells are transduced at a much greater efficiency. Transduction can be enhanced by pharmaceutical agents up to sevenfold in primary cells (transducing up to 20% of primary cells per well) and as much as 400-fold in immortalized mesangial cells. AAV delivered in vivo by intraparenchymal injection results in at least 3 mo of reporter gene expression in tubular epithelial, but not glomerular or vascular, cells at the injection site. These data indicate that AAV can deliver genes to renal cells both in vitro and in vivo resulting in prolonged gene expression, and thus AAV can be a useful tool for renal gene delivery.

Chronic rejection of mouse kidney allografts. Background Chronic renal allograft rejection is the leading cause of late graft failure. However, its pathogenesis has not been defined. Methods To explore the pathogenesis of chronic rejection, we studied a mouse model of kidney transplantation and examined the effects of altering the expression of donor major histocompatibility complex (MHC) antigens on the development of chronic rejection. Results We found that long-surviving mouse kidney allografts develop pathological abnormalities that resemble chronic rejection in humans. Furthermore, the absence of MHC class I or class II antigens did not prevent the loss of graft function nor alter the pathological characteristics of chronic rejection. Expression of transforming growth factor-β (TGF-β), a pleiotropic cytokine suggested to play a role in chronic rejection, was markedly enhanced in control allografts compared with isografts. However, TGF-β up-regulation was significantly blunted in MHC-deficient grafts. Nonetheless, these differences in TGF-β expression did not affect the character of chronic rejection, including intrarenal accumulation of collagens. Conclusions Reduced expression of either class I or II direct allorecognition pathways is insufficient to prevent the development of chronic rejection, despite a reduction in the levels of TGF-β expressed in the allograft. This suggests that the severity of chronic rejection is independent of the level of MHC disparity between donor and recipient and the level of TGF-β expression within the allograft.

HIV-associated nephropathy is a late, not early, manifestation of HIV-1 infection. Background Human immunodeficiency virus–associated nephropathy (HIVAN) can be the initial presentation of HIV-1 infection. As a result, many have assumed that HIVAN can occur at any point in the infection. This issue has important implications for appropriate therapy and, perhaps, for pathogenesis. Since the development of new case definitions for acquired immunodeficiency syndrome (AIDS) and better tools to assess infection, the relationship of HIVAN to the time of AIDS infection has not been addressed. In this study, we reassessed the stage of infection at the time of HIVAN diagnosis in 10 patients, and we reviewed all previously published cases applying the new case definitions to assess stage of infection. Methods HIVAN was confirmed by kidney biopsy in HIV seropositive patients with azotemia and/or proteinuria. CD4 + cell count and plasma HIV-1 RNA copy number were measured. We also reviewed all published cases of HIVAN to determine if AIDS-defining conditions, by current Centers for Disease Control definitions, were present in patients with biopsy-proven HIVAN. Results Twenty HIV-1 seropositive patients with proteinuria and an elevated creatinine concentration were biopsied. HIVAN was the single most common cause of renal disease. CD4 + cell count was below 200/mm 3 in all patients with HIVAN, fulfilling Centers for Disease Control criteria for an AIDS-defining condition. HIV-1 plasma RNA was detectable in all patients with HIVAN. In reviewing previous reports, an AIDS-defining condition was present in virtually all patients with HIVAN. Conclusion HIVAN develops late, not early, in the course of HIV-1 infection following the development of AIDS. This likely accounts for the poor prognosis noted in previous publications and has implications for pathogenesis. In addition, given the detectable viral RNA levels, highly active antiretroviral therapy is indicated in HIVAN. Highly active antiretroviral therapy may improve survival as well as alter the natural history of HIVAN.

Kidney disease is an important complication of HIV, particularly in minority populations. We describe the burden of chronic kidney disease among 1239 adults followed at an urban AIDS center, with an estimated prevalence of 15.5% (n = 192). Independent predictors of kidney disease included older age, black race, hepatitis C virus exposure, and lower CD4 cell count. These data suggest that chronic kidney disease remains a common complication of HIV infection in the era of antiretroviral therapy.