Controversies in the pathogenesis of HIV-associated renal diseases

Human Immunodeficiency Virus-associated Immune Complex Kidney Disease Progressing to End-stage Kidney Disease

A 58-year-old man with human immunodeficiency virus (HIV) infection presented with a week-long history of gross hematuria, nephrotic proteinuria, and acute kidney injury. The patient was non-adherent with combination antiretroviral therapy. A kidney biopsy showed cellular crescents with disruption of Bowman's capsule, C3-dominant immune complex deposition, consistent with HIV-associated immune complex kidney disease (HIVICK). During the course, his worsening kidney function warranted initiation of hemodialysis. This case highlights the fact that HIV patients are at an increased risk of developing HIVICK, especially in the setting of non-adherence. A greater understanding of HIVICK among HIV patients should promote additional investigation into its etiology and viable treatments.

A Systematic Review Exploring the Range of Renal Complications of Human Immunodeficiency Virus

Human immunodeficiency virus (HIV) is a viral infection which progressively leads to acquired immunodeficiency syndrome (AIDS) in the absence of treatment. This happens through the destruction of crucial cells in the immune system, such as the helper T cells, dendritic cells, and macrophages. Since the first case was isolated in the 20th century, the disease has spread rapidly among humans, with significant renal, cardiovascular, respiratory, and neurological complications. It is predominantly sexually transmitted but non-sexual transmission. A relationship between HIV and renal diseases has been suggested for a long time, but only a few systematic studies have centered on this association. This systematic review aims to analyze the possible association between HIV and renal diseases as well as the range and pathogenesis of these renal diseases. HIV remains a critical infectious disease globally, inciting substantial morbidity and mortality. Studies have shown that people living with HIV (PLWH) are at increased risk of acute and chronic kidney disease. This review is based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed, Google Scholar, and Cochrane databases were searched exhaustively using the inclusion criteria of free full-text English papers that have exclusively studied humans in the last 20 years. Sixteen articles were selected including a systematic review, observational studies, and comprehensive narrative reviews on the role of HIV in the etiology of renal diseases, and were systemically reviewed and analyzed to elicit the wide range of possible renal complications resulting from HIV infection.

The effects of add-on corticosteroids on renal outcomes in patients with biopsy proven HIV associated nephropathy: a single centre study from South Africa

BACKGROUND

The aim of this study was to assess, the efficacy and safety of add-on corticosteroids to antiretroviral therapy [ART] in patients with biopsy proven HIV associated nephropathy.

METHODS

All included patients had histological evidence of either collapsing or non-collapsing focal segmental glomerulosclerosis (FSGS) or podocyte and/or parietal cell hypertrophy or hyperplasia. All patients had evidence of tubulointerstitial inflammation with microcysts. Patients were randomized to ART with the addition of 1 mg/kg of corticosteroids [ART+C] or remained in the group [ART Alone] and followed for 2 years. A repeat biopsy was performed at 6 months.

RESULTS

Twenty-one patients were randomized to [ART+C] and 17 to [ART Alone]. The baseline estimated glomerular filtration rate (eGFR) was significantly lower in the [ART+C] vs. [ART Alone] group [35mls/min/1.73m² vs. 47 mls/min/1.73m², p = 0.015]. The [ART+C] cohort had a statistically significant improvement in median (eGFR) from baseline to last follow up compared with [ART Alone] i.e. [Δ = 25mls/min (IQR: 15;51) vs 9 mls/min (IQR: 0-24), p = 0.008]. There were no statistically significant differences between the groups when proteinuria and histology were analyzed. There were 8 deaths during the trial period, 7 from [ART+C] (Log rank p = 0.071).

CONCLUSIONS

In the [ART+C] cohort there was a significant improvement in eGFR over 2-years with increased mortality. Routine corticosteroid use cannot currently be recommended. Further investigation to define which subgroup of this cohort would safely benefit from the positive effects is required.

TRIAL REGISTRATION

ISRCTN study ID ( 56112439 ] was retrospectively registered on the 5 September 2018.

The metabolic syndrome and renal function in an African cohort infected with human immunodeficiency virus

INTRODUCTION

The human immunodeficiency virus (HIV) is often accompanied by renal dysfunction. It is expected that metabolic syndrome (MetS) may exacerbate renal impairment.

OBJECTIVE

We therefore determined the prevalence of MetS and the association thereof with renal function in a South African cohort infected with HIV.

METHODS

We matched 114 HIV-infected (77.3% on antiretroviral therapy [ART] and 22.7% ART-naïve) and 114 HIV-uninfected individuals according to age, sex and locality. We examined cardiovascular, anthropometric and metabolic measurements and determined the MetS. Renal function was assessed using standardised procedures.

RESULTS

The prevalence of MetS was lower in the HIV-infected individuals as compared to the uninfected individuals (28% vs. 44%, p = 0.013). The HIV-infected group presented with a lower body mass index (BMI) and waist circumference (WC) (all p < 0.001), as well as blood pressure (BP) (p ≤ 0.0021). The results were confirmed when comparing the HIV-infected group using ART (N = 85) and the HIV-uninfected group. When comparing the HIV-infected individuals with MetS to the HIV-uninfected individuals with MetS, no differences in BP were seen. With regard to renal function, the HIV-infected individuals with MetS (n = 32) had 43% higher urinary albumin-creatinine ratio (uACR) compared to the HIV-uninfected individuals with MetS, after adjusting for age, sex and WC (p = 0.032). None of the other renal function markers differed after adjustments for WC or BMI.

CONCLUSION

The HIV-infected Africans with MetS had almost twofold higher uACR, despite the low prevalence of MetS, compared to their uninfected counterparts. The combination of HIV and MetS seemed to increase the risk for renal impairment.

Similar Biophysical Abnormalities in Glomeruli and Podocytes from Two Distinct Models

Background FSGS is a pattern of podocyte injury that leads to loss of glomerular function. Podocytes support other podocytes and glomerular capillary structure, oppose hemodynamic forces, form the slit diaphragm, and have mechanical properties that permit these functions. However, the biophysical characteristics of glomeruli and podocytes in disease remain unclear.Methods Using microindentation, atomic force microscopy, immunofluorescence microscopy, quantitative RT-PCR, and a three-dimensional collagen gel contraction assay, we studied the biophysical and structural properties of glomeruli and podocytes in chronic (Tg26 mice [HIV protein expression]) and acute (protamine administration [cytoskeletal rearrangement]) models of podocyte injury.Results Compared with wild-type glomeruli, Tg26 glomeruli became progressively more deformable with disease progression, despite increased collagen content. Tg26 podocytes had disordered cytoskeletons, markedly abnormal focal adhesions, and weaker adhesion; they failed to respond to mechanical signals and exerted minimal traction force in three-dimensional collagen gels. Protamine treatment had similar but milder effects on glomeruli and podocytes.Conclusions Reduced structural integrity of Tg26 podocytes causes increased deformability of glomerular capillaries and limits the ability of capillaries to counter hemodynamic force, possibly leading to further podocyte injury. Loss of normal podocyte mechanical integrity could injure neighboring podocytes due to the absence of normal biophysical signals required for podocyte maintenance. The severe defects in podocyte mechanical behavior in the Tg26 model may explain why Tg26 glomeruli soften progressively, despite increased collagen deposition, and may be the basis for the rapid course of glomerular diseases associated with severe podocyte injury. In milder injury (protamine), similar processes occur but over a longer time.

Cisplatin-Induced Nephrotoxicity and HIV Associated Nephropathy: Mimickers of Myeloma-Like Cast Nephropathy

Myeloma cast nephropathy is an obstructing disorder of renal tubules, caused by precipitation of Bence Jones proteins. Myeloma-like cast nephropathy (MLCN) has been reported in the literature to occur in various primary renal and nonrenal diseases. We present a series of three rare cases of cast nephropathy, two of which are HIV patients, and the third patient is receiving cisplatin-based chemotherapy. However, in all three patients plasma cell dyscrasia has been ruled out. A 30-year-old male was admitted to the hospital with facial cellulitis. The second patient is a 31-year-old male who presented with Pneumocystis jiroveci pneumonia. The third patient was treated with cisplatin-based chemotherapy for carcinoma. First two cases revealed foci of diffuse tubular dilatation containing hyaline casts and interstitial inflammatory infiltrate, in addition to globally sclerotic glomeruli with ultrastructural foot process fusion and mesangium expansion. The third case showed acute tubular injury and cast formation of irregular casts composed of amorphous or granular material of low density admixed with scattered high electron-dense globules. Myeloma-like cast nephropathy and true myeloma cast nephropathy pose similar destructive effects on renal parenchyma. This new pattern of HIV-related nephropathy should be considered in HIV patients with MLCN, once monoclonal gammopathy is ruled out.

Renal transplantation in human immunodeficiency virus-infected recipients: a case-control study from the Brazilian experience

BACKGROUND

Highly active antiretroviral therapy has turned human immunodeficiency virus (HIV)-infected patients with end-stage renal disease into suitable candidates for renal transplantation. We present the Brazilian experience with kidney transplantation in HIV-infected recipients observed in a multicenter study.

METHODS

HIV-infected kidney transplant recipients and matched controls were evaluated for the incidence of delayed graft function (DGF), acute rejection (AR), infections, graft function, and survival of patients and renal grafts.

RESULTS

Fifty-three HIV-infected recipients and 106 controls were enrolled. Baseline characteristics were similar, but a higher frequency of pre-transplant positivity for hepatitis C virus and cytomegalovirus infections was found in the HIV group. Immunosuppressive regimens did not differ, but a trend was observed toward lower use of anti-thymocyte globulin in the group of HIV-infected recipients (P = 0.079). The HIV-positive recipient group presented a higher incidence of treated AR (P = 0.036) and DGF (P = 0.044). Chronic Kidney Disease Epidemiology Collaboration estimated that glomerular filtration rate was similar at 6 months (P = 0.374) and at 12 months (P = 0.957). The median number of infections per patient was higher in the HIV-infected group (P = 0.018). The 1-year patient survival (P < 0.001) and graft survival (P = 0.004) were lower, but acceptable, in the group of HIV-infected patients.

CONCLUSIONS

In the Brazilian experience, despite somewhat inferior outcomes, kidney transplantation is an adequate therapy for selected HIV-infected recipients.

Renal abnormalities among HIV infected children at Muhimbili National Hospital (MNH)-Dar es Salaam, Tanzania

Background

Human Immunodeficiency Virus infection is a multisystem disease that contributes to significant morbidity. Renal involvement is reported to be common among patients with HIV. This study was carried out to determine renal involvement using simple bedside tests combined with ultrasonography examination.

Methods

We recruited 240 children from the HIV clinic at Muhimbili National Hospital. Data were collected using structured questionnaires and included demographic, clinical information, radiological tests; renal ultrasound and laboratory tests; serum creatinine, white blood cells, CD4+ counts and percent, urine for microalbuminuria and proteinuria.

Results

Microalbuminuria and proteinuria were present in 20.4 % and 7.1 % respectively. Significantly higher prevalence of microalbuminuria (p < 0.01) and proteinuria p < 0.01) were noted with low CD4 percent (<25 %). Lower mean CD4+ count were noted among children with microalbuminuria [937.4 ± 595.3 cells/μL vs 1164.7 ± 664.3 cell/μL, (p < 0.05)] and proteinuria [675.5 ± 352.3 cells/μL vs 1152 ± 662 cells/μL (p < 0.001)]. Fourteen (5.8 %) HIV infected children had estimated glomerular filtration rate (eGFR of 30–59) consistent with severe renal impairment. Increased cortical echogenicity was noted in 69/153 (39.2 %) of participants who had ultrasound examination.

Conclusion

Microalbuminuria, proteinuria and renal dysfunction were noted to be prevalent among HIV infected children indicating the need to consider routine screening of renal complications in these children.

Renal transplantation in human immunodeficiency virus-positive patients: a report of four cases

INTRODUCTION

Renal transplantation (RT) in patients infected with human immunodeficiency virus (HIV) has significantly improved under the advent of combined antiretroviral therapy (cART). The authors describe their experience in RT in patients with HIV from September 2010 to June 2013.

CASES REPORT

Four patients underwent transplantation (3 with HIV-1 and 1 with HIV-2), three patients were male, and one was black. None were coinfected with hepatitis B virus (HBV) or hepatitis C virus (HCV). Etiology of kidney disease was HIV-associated nephropathy (2 patients), immunoglobulin (Ig)A nephropathy, and unknown. Average age at RT was 51 (range, 41-63) years. No patient was of high immunologic risk. Immunosuppression consisted of basiliximab for induction and prednisolone, tacrolimus (TAC), and mycophenolate mofetil for maintenance. TAC levels varied considerably in the early days (8.5-46 ng/mL), requiring major adjustments in TAC dose. Only the HIV-2 patient had delayed graft function. The follow-up of patients with HIV-1 was 37, 19, and 16 months, and 3 months for the HIV-2 patient. CD4+ T cells decreased in the early days after transplantation with subsequent improvement, along with persistent virological suppression. In the HIV-1 group there were no major infectious, cardiovascular, or neoplastic complications. Nevertheless, the HIV-2 patient died 3 months after RT due to H1N1 pneumonia complicated by pulmonary aspergillosis. Average estimated (CKD- EPI) glomerular filtration rate (eGFR) at 6 months was 85.6 mL/min/1.73 m(2).

CONCLUSION

Besides the difficulty in adjusting calcineurin inhibitors levels due to its interaction with antiretroviral therapy, namely with protease inhibitors, no patient had acute rejection. Furthermore, all patients presented an excellent control of viro-immunologic parameters. At the last follow-up neither cardiovascular events nor neoplastic complications were observed. Our results highlight the favorable outcome of RT in HIV-1-infected patients. The HIV-2 patient died due to severe infection, and the clinical management and potential benefit of RT in HIV-2-infected patients needs further study.

Rhabdomyolysis as the first manifestation of human immunodeficiency virus infection

Renal tubular acidosis (RTA) is a known complication of anti-retroviral medications. The presence of RTA in treatment naive-HIV patients is rare. A 49-year-old Caucasian woman presented with recurrent non-anion gap metabolic acidosis, AKI, rhabdomyolysis and hypokalemia on several occasions. Diagnosis of acquired distal RTA due to HIV was made given the history and laboratory data. To the best of our knowledge, this is the first case of HIV diagnosed with an initial presentation of rhabdomyolysis. We believe that acute renal failure was due to hypokalemia precipitating rhabdomyolysis caused by HIV-induced dRTA which was further exacerbated by amphetamine use.

Urinary biomarkers of kidney diseases in HIV-infected children

A significant number of children infected with the human immunodeficiency virus 1 (HIV-1) virus all over the world are at risk of developing renal diseases that could have a significant impact on their treatment and quality of life. It is necessary to identify children undergoing the early stages of these renal diseases, as well as the potential renal toxicity that could be caused by antiretroviral drugs, in order to prevent the development of cardiovascular complications and chronic renal failure. This article describes the most common renal diseases seen in HIV-infected children, as well as the value and limitations of the clinical markers that are currently being used to monitor their renal function and histological damage in a noninvasive manner. In addition, we discuss the progress made during the last 10 years in the discovery and validation of new renal biomarkers for HIV-infected children and young adults. Although significant progress has been made during the early phases of the biomarkers discovery, more work remains to be done to validate the new biomarkers in a large number of patients. The future looks promising, however, the new knowledge needs to be integrated and validated in the context of the clinical environment where these children are living.

Renal transplantation in human immunodeficiency virus (HIV)-positive children

Renal transplantation is being performed in adult human immunodeficiency virus (HIV)-positive patients and increasingly in paediatric patients as well. A multidisciplinary team involving an infectious disease professional is required to assist with HIV viral-load monitoring and in choosing the most appropriate highly active antiretroviral therapy (HAART). Drug interactions complicate immunosuppressant therapy and require careful management. The acute rejection rates appear to be similar in adults to those in noninfective transplant recipients. Induction with basiliximab and calcineurin-based immunosuppression appears to be safe and effective in these recipients. Prophylaxis is advised for a variety of infections and may need life-long administration, especially in children. Organ shortage remains a significant problem, and kidneys from deceased HIV-positive donors have been used successfully in a small study population. Overall, with careful planning and close follow-up, successful renal transplantation for paediatric HIV-infected recipients is possible.

Clinical practice guideline for the management of chronic kidney disease in patients infected with HIV: 2014 update by the HIV Medicine Association of the Infectious Diseases Society of America

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.

Aspectos histopatológicos das lesões renais em gatos experimentalmente infectados pelo vírus da imunodeficiência felina

A infecção pelo vírus da imunodeficiência felina (FIV) em gatos domésticos é caracterizada por distúrbios imunológicos, que geralmente se manifestam tardiamente na doença. Semelhante à infecção pelo vírus da imunodeficiência humana (HIV) em humanos, a infecção pelo FIV geralmente está associada a infecções oportunistas e ao desenvolvimento progressivo de nefropatia. Portanto, o objetivo do presente estudo foi avaliar as alterações histopatológicas em rins de 10 gatos experimentalmente infectados pelo FIV submetidos a eutanásia 60 meses após a inoculação viral. Nos rins de 100% dos gatos infectados pelo FIV foram visualizadas lesões glomerulares e tubulointersticiais. As lesões glomerulares eram caracterizadas principalmente por espessamento global ou segmentar da membrana basal glomerular (glomerulonefrite membranosa). Glomeruloesclerose e, em dois casos, proliferação de células epiteliais intraglomerulares (crescente glomerular), também foram observados. Nefrite intersticial linfoplasmocítica foi a alteração tubulointersticial mais frequente, visualizada em diferentes intensidades nos rins de 100% dos gatos. Os resultados do presente estudo demonstram que o tempo prolongado entre a infecção e a avaliação histopatológica pode ter sido decisivo para o surgimento das lesões renais em todos os gatos infectados pelo FIV e para o agravamento dessas lesões em alguns gatos.

Human immunodeficiency virus-1 (HIV-1)-mediated apoptosis: new therapeutic targets

HIV has posed a significant challenge due to the ability of the virus to both impair and evade the host’s immune system. One of the most important mechanisms it has employed to do so is the modulation of the host’s native apoptotic pathways and mechanisms. Viral proteins alter normal apoptotic signaling resulting in increased viral load and the formation of viral reservoirs which ultimately increase infectivity. Both the host’s pro- and anti-apoptotic responses are regulated by the interactions of viral proteins with cell surface receptors or apoptotic pathway components. This dynamic has led to the development of therapies aimed at altering the ability of the virus to modulate apoptotic pathways. These therapies are aimed at preventing or inhibiting viral infection, or treating viral associated pathologies. These drugs target both the viral proteins and the apoptotic pathways of the host. This review will examine the cell types targeted by HIV, the surface receptors exploited by the virus and the mechanisms whereby HIV encoded proteins influence the apoptotic pathways. The viral manipulation of the hosts’ cell type to evade the immune system, establish viral reservoirs and enhance viral proliferation will be reviewed. The pathologies associated with the ability of HIV to alter apoptotic signaling and the drugs and therapies currently under development that target the ability of apoptotic signaling within HIV infection will also be discussed.

Kidney disease in children and adolescents with perinatal HIV-1 infection

Introduction

Involvement of the kidney in children and adolescents with perinatal (HIV-1) infection can occur at any stage during the child's life with diverse diagnoses, ranging from acute kidney injury, childhood urinary tract infections (UTIs), electrolyte imbalances and drug-induced nephrotoxicity, to diseases of the glomerulus. The latter include various immune-mediated chronic kidney diseases (CKD) and HIV-associated nephropathy (HIVAN).

Discussion

The introduction of highly active anti-retroviral therapy (HAART) has dramatically reduced the incidence of HIVAN, once the commonest form of CKD in children of African descent living with HIV, and also altered its prognosis from eventual progression to end-stage kidney disease to one that is compatible with long-term survival. The impact of HAART on the outcome of other forms of kidney diseases seen in this population has not been as impressive. Increasingly important is nephrotoxicity secondary to the prolonged use of anti-retroviral agents, and the occurrence of co-morbid kidney disease unrelated to HIV infection or its treatment. Improved understanding of the molecular pathogenesis and genetics of kidney diseases associated with HIV will result in better screening, prevention and treatment efforts, as HIV specialists and nephrologists coordinate clinical care of these patients. Both haemodialysis (HD) and peritoneal dialysis (PD) are effective as renal replacement therapy in HIV-infected patients with end-stage kidney disease, with PD being preferred in resource-limited settings. Kidney transplantation, once contraindicated in this population, has now become the most effective renal replacement therapy, provided rigorous criteria are met. Given the attendant morbidity and mortality in HIV-infected children and adolescents with kidney disease, routine screening for kidney disease is recommended where resources permit.

Conclusions

This review focuses on the pathogenesis and genetics, clinical presentation and management of kidney disease in children and adolescents with perinatal HIV-1 infection.

Microalbuminuria in HIV disease

BACKGROUND/AIMS

Microalbuminuria is a marker for early kidney disease and cardiovascular risk. The purposes of this study were to determine the prevalence of microalbuminuria in an HIV-infected clinic population, to test the predictive value of a single urine albumin/creatinine ratio (ACR) to identify persistent microalbuminuria and to examine covariates of microalbuminuria.

METHODS

We conducted a prospective cohort study of HIV-infected subjects (n = 182) without proteinuria (urine protein/creatinine ratio ≥0.5 g/g), elevated serum creatinine, diabetes, or chronic inflammatory conditions. Subjects completed three research visits within 9 months. Microalbuminuria was defined as the geometric mean ACR of 25-355 mg/g for females and 17-250 mg/g for males.

RESULTS

The prevalence of microalbuminuria was 14%. The negative predictive value of a single urine ACR determination was 98%, whereas the positive predictive value was only 74%. Microalbuminuria was similar among Black (15%) and non-Black (14%) subjects (p = 0.8). Subjects with microalbuminuria were more likely to have hypertension (p = 0.02) and metabolic syndrome (p = 0.03). While duration of HIV infection and the level of HIV viremia were similar between groups, those with microalbuminuria were more likely to have a CD4 count <200 cells/μl (p = 0.0003). In a multivariate logistic regression analysis, the only significant independent predictors of microalbuminuria were low CD4 count (p = 0.018) and current ritonavir exposure (p = 0.04).

CONCLUSION

The prevalence of microalbuminuria in an HIV-infected clinic population was similar to earlier reports, and was associated with hypertension and impaired immune function. A single normal ACR determination effectively excludes microalbuminuria, whereas an elevated ACR requires confirmation.

Tubular cell HIV-entry through apoptosed CD4 T cells: a novel pathway

We hypothesized that HIV-1 may enter tubular cells by phagocytosis of apoptotic fragments of HIV-1-infected T cells infiltrating tubular interstitium. The study was designed to evaluate the interaction of programmed death-1 (PD-1) receptors on CD4 T cells and programmed death ligand-1 (PD-L1) on tubular cells (HK2 and HRPTEC, primary tubular cells). Co-cultivation of HIV-1 infected lymphocytes (HIV-LY) with HK2s/HRPTECs resulted in T cell apoptosis, uptake of the apoptosed HIV-LY by HK2s/HRPTECs, tubular cell activation and HIV expression. Cytochalasin-B inhibited tubular cell HIV-LY uptake and anti-PD-L1 antibody inhibited HIV-LY apoptosis and tubular cell HIV-LY uptake, activation and HIV expression. These observations do indicate induction of apoptosis of T cells due to interaction of PD-1 and PD-L1 upon co-cultivation and subsequent phygocytosis of HIV-laden apoptotic bodies by tubular cells and thus the transfer of HIV-1 into tubular cells. These findings identify a novel pathway that facilitates HIV-1 entry into tubular cell.

Rapamycin-induced modulation of HIV gene transcription attenuates progression of HIVAN

HIV-associated nephropathy (HIVAN) is the manifestation of HIV gene expression by kidney cells in the presence of specific host factors. Recently, rapamycin (sirolimus) has been demonstrated to modulate the progression of HIVAN. We hypothesized that rapamycin would modulate the progression of HIVAN by attenuating HIV gene expression. To test our hypothesis, three weeks old Tg26 mice (n=6) were administered either vehicle or rapamycin (5 mg/kg, every other day, intraperitoneal) for eight weeks. At the end of the experimental period, the kidneys were harvested. In in vitro studies, human podocytes were transduced with either HIV-1 (NL4-3) or empty vector (EV), followed by treatment with either vehicle or rapamycin. Total RNA and proteins were extracted from renal tissues/cellular lysates and HIV gene transcription/translation was measured by real time PCR and Western blotting studies. Renal histological slides were graded for glomerular sclerosis and tubular dilatation with microcyst formation. Rapamycin attenuated both glomerular and tubular lesions in Tg26 mice. Rapamycin decreased transcription of HIV genes both in renal tissues as well as in HIV-1 transduced podocytes. Our data strongly indicate that HIV-1 long terminal repeat-mediated transcriptional activity was targeted by rapamycin. Rapamycin enhanced podocyte NF-κB and CREB activities but then it decreased AP-1 binding activity. Since expression of HIV genes by kidney cells has been demonstrated to be the key factor in the development HIVAN, it appears that rapamycin-induced altered transcription of HIV genes might have partly contributed to its disease modulating effects.

Inhibition of renin activity slows down the progression of HIV-associated nephropathy

In the present study, we evaluated the effect of inhibition of renin activity (aliskiren) on the progression of renal lesions in two different mouse models (Vpr and Tg26) of human immunodeficiency virus (HIV)-associated nephropathy (HIVAN). In protocol A, Vpr mice were fed either water (C-VprA) or doxycycline [Doxy (D-VprA)] in their drinking water for 6 wk. In protocols B and C, Vpr mice received either normal saline (C-VprB/C), Doxy + normal saline (D-VprB/C), or Doxy + aliskiren (AD-VprB/C) for 6 wk (protocol B) or 12 wk (protocol C). In protocols D and E, Vpr mice were fed Doxy for 6 wk followed by kidney biopsy. Subsequently, half of the mice were administered either normal saline (D-VprD/E) or aliskiren (AD-VprD/E) for 4 wk (protocol D) or 8 (protocol E) wk. All D-VprA mice showed renal lesions in the form of focal segmental glomerular sclerosis and dilatation of tubules. In protocols B and C, aliskiren diminished both progression of renal lesions and proteinuria. In protocol C, aliskiren also diminished (P < 0.01) the rise in blood urea. In all groups, Doxy-treated mice displayed increased serum ANG I levels (the product of plasma renin activity); on the other hand, all aliskiren-treated mice displayed diminished serum ANG I levels. Renal tissues of D-VprC displayed increased ANG II content; however, aliskiren attenuated renal tissue ANG II production in AD-VprC. In protocol D, AD-VprD showed a 24.2% increase in the number of sclerosed glomeruli compared with 139.2% increase in sclerosed glomeruli in D-VprD (P < 0.01) from their baseline. The attenuating effect of aliskiren on the progression of renal lesions continued in AD-VprE. Aliskiren also diminished blood pressure, proteinuria, and progression of renal lesions in Tg26 mice. These findings indicate that inhibition of renin activity has a potential to slow down the progression of HIVAN.

Chronic kidney disease associated with perinatal HIV infection in children and adolescents

BACKGROUND

This study describes the incidence, clinical and demographic characteristics, and spectrum of chronic kidney disease (CKD) in youths with perinatal HIV-1 infection.

METHODS

Retrospective analysis between May 1993 and December 2006 of subjects with renal disease followed in the Pediatric AIDS Clinical Trials Group 219/219C multicenter study examining the long-term consequences of perinatal HIV infection. Diagnosis confirmation was made utilizing a questionnaire mailed to research sites. Participants with CKD of other etiology than HIV were excluded. Outcome measures were biopsy-diagnosed CKD and, in the absence of biopsy, HIV-associated nephropathy (HIVAN) using established clinical criteria.

RESULTS

Questionnaires on 191 out of 2,102 participants identified 27 cases of CKD: 14 biopsy-diagnosed and 6 clinical cases of HIVAN, and 7 biopsy-diagnosed cases of immune complex-mediated kidney disease (lupus-like nephritis, 3; IgA nephropathy, 2; membranous nephropathy, 2). Incidence rates for CKD associated with HIV in pre-highly active antiretroviral therapy (HAART) (1993-1997) and HAART (1998-2002, 2003-2006) eras were 0.43, 2.84, and 2.79 events per 1,000 person years respectively. In multivariate analysis, black race and viral load ≥100,000 copies/mL (rate ratios 3.28 and 5.05, p ≤ 0.02) were associated with CKD.

CONCLUSIONS

A variety of immune complex-mediated glomerulonephritides and HIVAN occurs in this population. Black race and uncontrolled viral replication are risk factors for CKD associated with HIV.

Rodent models for HIV-associated neurocognitive disorders

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) reflect the spectrum of neural impairments seen during chronic viral infection. Current research efforts focus on improving antiretroviral and adjunctive therapies, defining disease onset and progression, facilitating drug delivery, and halting neurodegeneration and viral resistance. Because HIV is species-specific, generating disease in small-animal models has proved challenging. After two decades of research, rodent HAND models now include those containing a human immune system. Antiviral responses, neuroinflammation and immunocyte blood-brain barrier (BBB) trafficking follow HIV infection in these rodent models. We review these and other rodent models of HAND and discuss their unmet potential in reflecting human pathobiology and in facilitating disease monitoring and therapeutic discoveries.

The spectrum of renal histologies seen in HIV with outcomes, prognostic indicators and clinical correlations

BACKGROUND

Two hundred and twenty-one HIV-positive renal biopsies were analysed from Groote Schuur Hospital to determine outcomes and prognostic indicators based on histology and clinical features.

METHODS

The histology findings were compared with patient demographics, clinical and renal parameters, mortality, CD4 count and date of commencing combined anti-retroviral therapy (cART). Follow-up was between 1 and 3.5 years.

RESULTS

We found a spectrum of renal histologies in HIV-positive patients of which HIV-associated nephropathy (HIVAN) was the most common histology. cART reduced the mortality in those with any feature of HIVAN by 57% [adjusted hazard ratio (AHR) 0.43, 95% confidence interval (CI) 0.22-0.85]. Of those patients with HIVAN who died, 79% died of renal failure as registered on their death certificate. Proteinuria and microcysts were shown to be poor prognostic indicators (AHR 1.36: 1.09-1.70 and 2.04: 1.24-3.37). In patients with HIVAN alone followed for up to 2 years on cART, estimated glomerular filtration rate remained stable and there was a trend towards decreased proteinuria. cART improved survival in patients with isolated immune complex disease.

CONCLUSIONS

As mortality is improved in patients with any feature of HIVAN or isolated immune complex disease, cART should be initiated once any of these histological features are established. We believe the spectrum of disease that constitutes HIVAN needs to be more specifically defined. The ultimate outcome may be determined by the histological subtype.

Absence of APOL1 risk variants protects against HIV-associated nephropathy in the Ethiopian population

BACKGROUND

Susceptibility to end-stage kidney disease (ESKD) among HIV-infected Americans of African ancestral heritage has been attributed to APOL1 genetic variation. We determined the frequency of the APOL1 G1 and G2 risk variants together with the prevalence of HIV-associated nephropathy (HIVAN) among individuals of Ethiopian ancestry to determine whether the kidney disease genetic risk is PanAfrican or restricted to West Africa, and can explain the previously reported low risk of HIVAN among Ethiopians.

METHODS

We studied a cohort of 338 HIV-infected individuals of Ethiopian ancestry treated in one Israeli and one Ethiopian center. We sought clinical evidence for HIVAN (serum creatinine >1.4 mg/dl or proteinuria >30 mg/dl in a spot urine sample). Genetic analyses included the genotyping of the APOL1 G1 and G2 variants, and a panel of 33 genomic ancestry-informative markers. Statistical analysis compared clinical and genetic indices for HIV-infected individuals of Ethiopian ancestry and overall Ethiopians to those reported for HIV-infected African-Americans, overall African-Americans, West Africans and non-Africans.

FINDINGS

Three (0.8%) of 338 HIV-infected patients of Ethiopian ancestry showed clinical criteria compatible with renal impairment. Two of these 3 patients also have severe poorly controlled diabetes mellitus. The third nondiabetic patient underwent renal biopsy which ruled out HIVAN. This absence of clinically apparent HIVAN was significantly different from that reported for African-Americans. The APOL1 G1 and G2 risk variants were found, respectively, in 0 and 2 (heterozygote state) of the 338 HIV-infected individuals. Global ancestry and the frequencies of the APOL1 G1 and G2 variants are not statistically different from their frequencies in the general Ethiopian population, but are significantly and dramatically lower than those observed among HIV-infected African-Americans, African-Americans and West Africans.

INTERPRETATION

The coinciding absence of HIVAN and the APOL1 risk variants among HIV-infected individuals of Ethiopian ancestry support a Western rather than Pan-African ancestry risk for ESKD, and can readily explain the lack of HIVAN among individuals of Ethiopian ancestry.

Adverse host factors exacerbate occult HIV-associated nephropathy

In the present study, we hypothesized that HIV-1-induced occult HIV-associated nephropathy (HIVAN) would become apparent in the presence of adverse host factors. To test our hypothesis, Vpr mice (which display doxycycline-dependent Vpr expression in podocytes) with two, three, and four copies of the angiotensinogen (Agt) gene (Vpr-Agt-2, Vpr-Agt-3, and Vpr-Agt-4) were administered doxycycline for 3 weeks (to develop clinically occult HIVAN) followed by doxycycline-free water during the next 3 weeks. Subsequently, renal biomarkers were measured, and kidneys were harvested for renal histology. Vpr-Agt-2 developed neither proteinuria nor elevated blood pressure, and displayed minimal glomerular and tubular lesions only, without any microcyst formation. Vpr-Agt-3 showed mild glomerular and tubular lesions and microcyst formation, whereas Vpr-Agt-4 showed moderate proteinuria, hypertension, glomerular sclerosis, tubular dilation, microcysts, and expression of epithelial mesenchymal transition markers. Vpr-Agt-4 not only displayed enhanced renal tissue expression of Agt, renin, and angiotensin-converting enzyme, but also had higher renal tissue concentrations of angiotensin II. Moreover, renal cells in Vpr-Agt-4 showed enhanced expression of transforming growth factor-β, connective tissue growth factor, and vascular endothelial growth factor. These findings indicate that adverse host factors, such as the activation of the renin-angiotensin system, promote the progression of occult HIVAN to apparent HIVAN.

Identification of the nephropathy-susceptibility locus HIVAN4

HIVAN1, HIVAN2, and HIVAN3 are nephropathy-susceptibility loci previously identified in the HIV-1 transgenic mouse, a model of collapsing glomerulopathy. The HIVAN1 and HIVAN2 loci modulate expression of Nphs2, which encodes podocin and several other podocyte-expressed genes. To identify additional loci predisposing to nephropathy, we performed a genome-wide scan in 165 backcross mice generated between the nephropathy-sensitive HIV-1-transgenic FVB/NJ (TgFVB) strain and the resistant Balb/cJ (BALB) strain. We identified a major susceptibility locus (HIVAN4) on chromosome 6 G3-F3, with BALB alleles conferring a twofold reduction in severity (peak LOD score = 4.0). Similar to HIVAN1 and HIVAN2, HIVAN4 modulated expression of Nphs2, indicating a common pathway underlying these loci. We independently confirmed the HIVAN4 locus in a sister TgFVB colony that experienced a dramatic loss of nephropathy subsequent to a breeding bottleneck. In this low-penetrance line, 3% of the genome was admixed with BALB alleles, suggesting a remote contamination event. The admixture localized to discrete segments on chromosome 2 and at the HIVAN4 locus. HIVAN4 candidate genes include killer lectin-like receptor genes as well as A2m and Ptpro, whose gene products are enriched in the glomerulus and interact with HIV-1 proteins. In summary, these data identify HIVAN4 as a major quantitative trait locus for nephropathy and a transregulator of Nphs2. Furthermore, similar selective breeding strategies may help identify further susceptibility loci.

Advances in our understanding of the pathogenesis of HIV-1 associated nephropathy in children

Childhood HIV-1 associated nephropathy (HIVAN) is a clinical and renal histological disease characterized by heavy proteinuria associated with focal and segmental glomerular sclerosis and/or mesangial hyperplasia in combination with microcystic tubular dilatation. These lesions lead to renal enlargement and rapid progression to kidney failure. Children of African ancestry have a unique susceptibility to developing HIVAN. It is estimated that approximately 300,000 HIV-infected children living in the sub-Saharan Africa could develop HIVAN if they do not receive appropriate antiretroviral therapy. This article discusses recent developments and controversies related to the pathogenesis of childhood HIVAN. The role of host genetic factors, including the newly identified variants in the APOL1 gene, is discussed in the context of previous studies that established the pathological paradigm for HIVAN, and our current understanding of the functional genomics analysis. Hopefully, these advances will provide new research opportunities to generate better treatments for children with HIVAN.

TNFR2 interposes the proliferative and NF-κB-mediated inflammatory response by podocytes to TNF-α

The development of proliferative podocytopathies has been linked to ligation of tumor necrosis factor receptor 2 (TNFR2) expressed on the renal parenchyma; however, the TNFR2-positive cells within the kidney responsible for podocyte injury are unknown. We detected de novo expression of TNFR2 on podocytes before hyperplastic injury in crescentic glomerulonephritis of mice with nephrotoxic nephritis, and in collapsing glomerulopathy of Tg26(HIV/nl) mice, kd/kd mice, and human beings. We further found that serum levels of soluble TNF-α and TNFR2 correlated significantly with renal injury in Tg26(HIV/nl) mice. Thus, we asked whether ligand binding of TNFR2 on podocytes ex vivo precipitates the characteristic proliferative and pro-inflammatory diseased podocyte phenotypes. Soluble TNF-α activated NF-κB and dose-dependently induced podocyte proliferation, marked by the expression of the podocyte G(1) cyclin and NF-κB target gene, cyclin D1. Microarray gene and chemokine protein expression profiling showed a marked pro-inflammatory NF-κB signature, and activated podocytes secreting CCL2- and CCL5-induced macrophage migration in transwell assays. Neutralization of TNFR2 on podocytes with blocking antibodies abrogated NF-κB activation and the induction of cyclin D1 by TNF-α, and identified TNFR2 as the primary receptor that induced IκBα degradation, the initiating event in NF-κB activation. These results suggest that TNFR2 expressed on podocytes and its canonical NF-κB signaling may directly interpose the compound pathogenic responses by podocytes to TNF-α, in the absence of other TNFR2-positive renal cell types in proliferative podocytopathies.

The molecular pathogenesis of HIV-1 associated nephropathy: recent advances

HIV-1-associated nephropathy (HIVAN) is a major complication of HIV-1 infection, frequently resulting in kidney failure. HIVAN arises due to HIV-1-induced dysregulation of podocytes, the glomerular epithelial cells that establish and maintain the kidney filtration barrier. Host genetic factors are important for the development of HIVAN. The risk of HIVAN is greatest in populations of African ancestry, and is attributable to a genetic variation at the APOL1 locus on chromosome 22. Mouse models of HIVAN enable delineation of dysregulated pathways underlying disease. Identification of HIVAN susceptibility loci in a mouse model, combined with expression quantitative trait locus mapping, has demonstrated that murine HIVAN loci transregulate podocyte gene expression. HIV-1 induces perturbations in podocyte expression response, suggesting that HIV-1 potentially interferes with compensatory pathways that normally restore cellular homeostasis in the face of genetic mutations. These findings present a framework for identification of podocyte transregulators and reconstruction of the molecular networks connecting susceptibility genes to the development of nephropathy.