Viral DNA in microdissected renal biopsy tissue from HIV infected patients with nephrotic syndrome

NEF-Induced HIV-Associated Nephropathy Through HCK/LYN Tyrosine Kinases

HIV-1-associated nephropathy (HIVAN) is a severe complication of HIV-1 infection. To gain insight into the pathogenesis of kidney disease in the setting of HIV, a transgenic (Tg) mouse model [CD4C/HIV-negative regulator factor (Nef)] was used in which HIV-1 nef expression is under control of regulatory sequences (CD4C) of the human CD4 gene, thus allowing expression in target cells of the virus. These Tg mice develop a collapsing focal segmental glomerulosclerosis associated with microcystic dilatation, similar to human HIVAN. To identify kidney cells permissive to the CD4C promoter, CD4C reporter Tg lines were used. They showed preferential expression in glomeruli, mainly in mesangial cells. Breeding CD4C/HIV Tg mice on 10 different mouse backgrounds showed that HIVAN was modulated by host genetic factors. Studies of gene-deficient Tg mice revealed that the presence of B and T cells and that of several genes was dispensable for the development of HIVAN: those involved in apoptosis (Trp53, Tnfsf10, Tnf, Tnfrsf1b, and Bax), in immune cell recruitment (Ccl3, Ccl2, Ccr2, Ccr5, and Cx3cr1), in nitric oxide (NO) formation (Nos3 and Nos2), or in cell signaling (Fyn, Lck, and Hck/Fgr). However, deletion of Src partially and that of Hck/Lyn largely abrogated its development. These data suggest that Nef expression in mesangial cells through hematopoietic cell kinase (Hck)/Lck/Yes novel tyrosine kinase (Lyn) represents important cellular and molecular events for the development of HIVAN in these Tg mice.

Intrinsic Kidney Pathology in Children and Adolescents Following COVID-19 Vaccination: A Systematic Review

Global COVID-19 vaccination programs for children and adolescents have been developed with international clinical trial data confirming COVID-19 mRNA vaccine safety and efficacy for the pediatric population. The impact of COVID-19 vaccination in the kidneys is thought to be explained by a complex immune-mediated relationship between the two, although the pathophysiological mechanisms of how COVID-19 vaccination potentially induces kidney pathology are not presently well known. Whilst intrinsic kidney pathologies following COVID-19 vaccination have been reported in adults, such cases are only being recently reported with greater frequency in children and adolescents. Conforming to the PRISMA checklist, we conducted a systematic review of the current literature to provide an overview on the range of intrinsic kidney pathologies that have been reported following COVID-19 vaccination in children and adolescents. All English language research articles published on or before 30 June 2022 reporting new-onset or relapsed intrinsic kidney pathology in children or adolescents (≤18 years) following COVID-19 vaccination were selected for qualitative analysis. Out of 18 cases from the 13 published articles selected, there were 10 cases of IgA nephropathy (1 case of rapidly progressive glomerulonephritis requiring acute hemodialysis), 5 cases of minimal change disease (MCD), 1 case of concurrent MCD/tubulointerstitial nephritis (TIN) and 2 cases of TIN. There is no indication currently to avoid vaccination, unless specific circumstances exist, as the benefits of COVID-19 vaccination far outweigh its risks. Concluding the findings from our systematic review based on preliminary evidence, potential adverse effects to the kidney from COVID-19 vaccination affects a small number of children and adolescents among the many who have been vaccinated. There remains good reason at present to support vaccination of children and adolescents with a greater morbidity status, such as those living with preexisting chronic kidney disease. Close observation of all children and adolescents receiving COVID-19 vaccination is recommended, particularly in those with preceding intrinsic kidney pathology to identify risks of relapsed disease.

Intrinsic Kidney Pathology Following COVID-19 Infection in Children and Adolescents: A Systematic Review

Introduction: COVID-19 infections resulting in pathological kidney manifestations have frequently been reported in adults since the onset of the global COVID-19 pandemic in December 2019. Gradually, there have been an increased number of COVID-19-associated intrinsic kidney pathologies in children and adolescents reported as well. The pathophysiological mechanisms between COVID-19 and the onset of kidney pathology are not fully known in children; it remains a challenge to distinguish between intrinsic kidney pathologies that were caused directly by COVID-19 viral invasion, and cases which occurred as a result of multisystem inflammatory syndrome due to the infection. This challenge is made more difficult in children, due to the ethical limitations of performing kidney biopsies to reach a biopsy-proven diagnosis. Although previous systematic reviews have summarized the various pathological kidney manifestations that have occurred in adults following acute COVID-19 infection, such reviews have not yet been published for children and adolescents. We describe the results of a systematic review for intrinsic kidney pathology following COVID-19 infection in children and adolescents. Methods: A systematic literature search of published data up until 31 October was completed through the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guidelines. Research articles reporting new-onset or relapsed intrinsic kidney pathology in children or adolescents (≤18 years) following acute COVID-19 infection were included for qualitative review. COVID-19 infection status was defined by a positive result from a RT-PCR, or nuclear antibody testing. Only full-text articles published in the English language were selected for review. Results: Twenty-nine cases from fifteen articles were included in the qualitative synthesis of this systematic review. Nephrotic syndrome, as an umbrella condition, appeared as the most frequently observed presentation (20 cases) with disease remission noted in all cases with steroid treatment. Other cases included numerous glomerulonephritides, such as acute necrotizing glomerulonephritis, MPO vasculitis and collapsing glomerulopathy, and thrombotic microangiopathies, such as aHUS. For patients with transplanted kidneys, T-cell-mediated rejection and mild tubular interstitial infiltration were noted following testing positive for COVID-19. There were no mortalities reported in any of the included cases, although two patients remained dialysis dependent at hospital discharge. Conclusion: This systematic review highlights the various intrinsic pathological kidney manifestations in children and adolescents as a result of acute COVID-19 infection. The clinical timeline and presentation of these cases support the mechanistic hypothesis between COVID-19 infection and the onset of intrinsic kidney pathologies within this context. The progressive introduction of vaccination programs for children and adolescents may hopefully reduce the severity of COVID-19-associated illnesses, and pathological kidney manifestations in this population.

Mechanisms of Proteinuria in HIV

Proteinuria is common in the setting of HIV infection, and may reflect comorbid kidney disease, treatment-related nephrotoxicity, and HIV-related glomerular diseases. The mechanisms of podocyte and tubulointerstial injury in HIV-associated nephropathy (HIVAN) have been the subject of intense investigation over the past four decades. The pathologic contributions of viral gene expression, dysregulated innate immune signaling, and ancestry-driven genetic risk modifiers have been explored in sophisticated cellular and whole animal models of disease. These studies provide evidence that injury-induced podocyte dedifferentiation, hyperplasia, cytoskeletal dysregulation, and apoptosis may cause the loss of glomerular filtration barrier integrity and slit diaphragm performance that facilitates proteinuria and tuft collapse in HIVAN. Although the incidence of HIVAN has declined with the introduction of antiretroviral therapy, the collapsing FSGS lesion has been observed in the context of other viral infections and chronic autoimmune disorders, and with the use of interferon-based therapies in genetically susceptible populations. This highlights the fact that the lesion is not specific to HIVAN and that the role of the immune system in aggravating podocyte injury warrants further exploration. This review will summarize our progress in characterizing the molecular mechanisms of podocyte dysfunction in HIVAN and other forms of HIV-associated kidney disease.

Renal Phosphate Handling in Antiretroviral-naive HIV-Infected Patients

BACKGROUND

Human immunodeficiency virus (HIV) infection impairs renal function, thereby affecting renal phosphate metabolism.

OBJECTIVES

We prospectively estimated the prevalence of phosphate abnormalities (mild, moderate to life-threatening hypophosphataemia, and hyperphosphataemia) before initiating antiretroviral therapy (ART).

METHODS

A cross-sectional analysis was performed on 170 consecutive newly diagnosed ARTnaive, HIV-infected patients attending our HIV/AIDS clinics over a period of one year. Fifty (50) screened HIV-negative blood donors were used for comparison (controls). Blood and urine were collected simultaneously for phosphate and creatinine assay to estimate fractional phosphate excretion (FEPi %) and glomerular filtration rate (eGFR).

RESULTS

eGFR showed significant difference between patients' and controls' medians (47.89ml/ min/1.73m2 versus 60ml/min/1.73m2, p <0.001); which denotes a moderate chronic kidney disease in the patients. Of the 170 patients, 78 (45.9%) had normal plasma phosphate (0.6-1.4 mmol/L); 85 (50%) had hyperphosphataemia. Grades 1, 2 and 3 hypophosphataemia was observed in 3 (1.8%), 3 (1.8%), and 1(0.5%) patient(s) respectively. None had grade 4 hypophosphataemia. Overall, the patients had significantly higher median of plasma phosphate than the controls, 1.4 mmol/L (IQR: 1.0 - 2.2) versus 1.1 mmol/L (IQR: 0.3 - 1.6), p <0.001, implying hyperphosphataemia in the patients; significantly lower median urine phosphate than the controls, 1.5 mmol/L (IQR: 0.7 -2.1) versus 8.4 mmol/L (IQR: 3.4 - 16), p <0.001), justifying the hyperphosphataemia is from phosphate retention; but a non-significantly lower median FEPi% than the controls, 0.96% (IQR: 0.3 -2.2) versus 1.4% (IQR: 1.2 -1.6), p > 0.05. Predictors of FEPi% were age (Odds ratio, OR 0.9, p = 0.009); weight (OR 2.0, p < 0.001); CD4+ cells count predicted urine phosphate among males (p = 0.029).

CONCLUSION

HIV infection likely induces renal insufficiency with reduced renal phosphate clearance. Thus, hyperphosphataemia is highly prevalent, and there is mild to moderate hypophosphataemia but its life-threatening form (grade 4) is rare among ART-naive HIV patients.

HIV-1 infection of the kidney: mechanisms and implications

People living with HIV are at higher risk for acute and chronic kidney disease compared with uninfected individuals. Kidney disease in this population is multifactorial, with several contributors including HIV infection of kidney cells, chronic inflammation, genetic predisposition, aging, comorbidities, and coinfections. In this review, we provide a summary of recent advancements in the understanding of the mechanisms and implications of HIV infection and kidney disease, with particular focus on the role of direct HIV infection of renal cells.

Proliferation of HIV-infected renal epithelial cells following virus acquisition from infected macrophages

OBJECTIVES

HIV-1 can infect and persist in different organs and tissues, resulting in the generation of multiple viral compartments and reservoirs. Increasing evidence supports the kidney as such a reservoir. Previous work demonstrated that HIV-1 infected CD4 T-cells transfer virus to renal tubule epithelial (RTE) cells through cell-to-cell contact. In addition to CD4 T cells, macrophages represent the other major target of HIV-1. Renal macrophages induce and regulate inflammatory responses and are critical to homeostatic regulation of the kidney environment. Combined with their ability to harbour virus, macrophages may also play an important role in the spread of HIV-1 infection in the kidney.

DESIGN AND METHODS

Multiparametric histochemistry analysis was performed on kidney biopsies from individuals with HIV-1 associated nephropathy (HIVAN). Primary monocyte-derived macrophages were infected with a GFP-expressing replication competent HIV-1. HIV-1 transfer from macrophages to RTE cells was carried out in a coculture system and evaluated by fluorescence-microscopy and flow-cytometry. Live imaging was performed to assess the fate of HIV-1 infected RTE cells over time.

RESULTS

We show that macrophages are abundantly present in the renal inflammatory infiltrate of individuals with HIVAN. We observed contact-dependent HIV-1 transfer from infected macrophages to both primary and immortalized renal cells. Live imaging of HIV-1 infected RTE cells revealed four different fates: proliferation, hypertrophy, latency and cell death.

CONCLUSION

Our study suggests that macrophages may play a role in the dissemination of HIV-1 in the kidney and that proliferation of infected renal cells may contribute to HIV-1 persistence in this compartment.

APOL1-G0 protects podocytes in a mouse model of HIV-associated nephropathy

African polymorphisms in the gene for Apolipoprotein L1 (APOL1) confer a survival advantage against lethal trypanosomiasis but also an increased risk for several chronic kidney diseases (CKD) including HIV-associated nephropathy (HIVAN). APOL1 is expressed in renal cells, however, the pathogenic events that lead to renal cell damage and kidney disease are not fully understood. The podocyte function of APOL1-G0 versus APOL1-G2 in the setting of a known disease stressor was assessed using transgenic mouse models. Transgene expression, survival, renal pathology and function, and podocyte density were assessed in an intercross of a mouse model of HIVAN (Tg26) with two mouse models that express either APOL1-G0 or APOL1-G2 in podocytes. Mice that expressed HIV genes developed heavy proteinuria and glomerulosclerosis, and had significant losses in podocyte numbers and reductions in podocyte densities. Mice that co-expressed APOL1-G0 and HIV had preserved podocyte numbers and densities, with fewer morphologic manifestations typical of HIVAN pathology. Podocyte losses and pathology in mice co-expressing APOL1-G2 and HIV were not significantly different from mice expressing only HIV. Podocyte hypertrophy, a known compensatory event to stress, was increased in the mice co-expressing HIV and APOL1-G0, but absent in the mice co-expressing HIV and APOL1-G2. Mortality and renal function tests were not significantly different between groups. APOL1-G0 expressed in podocytes may have a protective function against podocyte loss or injury when exposed to an environmental stressor. This was absent with APOL1-G2 expression, suggesting APOL1-G2 may have lost this protective function.

Effects of Highly Active Antiretroviral Therapy on Renal Function and Renal Phosphate Handling in African Adults with Advanced HIV and CKD

BACKGROUND

Highly Active Antiretroviral Therapy (HAART) has been implicated in renal dysfunction with hypophosphataemia.

OBJECTIVE

We prospectively evaluated renal phosphate excretion during HAART use.

METHOD

Newly diagnosed human immunodeficiency virus (HIV)-infected individuals were treated with Tenofovir disoproxil fumarate/Emtricitabine/Efavirenz (TDF/FTC/EFV), n=33; Zidovudine/Lamivudine/Nevirapine (ZDV/3TC/NVP), n=53; and Zidovudine/Lamivudine/Efavirenz (ZDV/3TC/EFV), n=16. Creatinine and phosphate were assayed in blood and urine simultaneously at baseline, 1, 3, 6 and 9 months. Glomerular filtration rate (eGFR), fractional phosphate excretion and reabsorption (FEPi % and TRP), and the ratio of tubular maximum reabsorption of phosphate (TmP) to GFR (TmP/GFR) were estimated.

RESULTS

At baseline, eGFR showed moderate chronic kidney disease (mean: 35.50 ± 2.02, 33.14 ± 1.63, and 39.97±1.84 ml/min/1.73m2 in the 3 groups respectively); 54 (52.9%) patients had hyperphosphataemia (>1.4mmo/L); 43 (42.2%) had normophosphataemia (0.6-1.4mmol/L); 5 (4.9%) had hypophosphataemia (<0.6mmol/L). eGFR improved significantly from 1 month (≥60, 58.65 ± 1.11, and 51.76 ±1.59 ml/min/1.73m2; p=0.04, <0.001, 0.67 respectively), with a relapse at 9 months in TDFtreated subjects (50.10 ± 1.89 ml/min/1.73m2). TDF/FTC/EFV resulted in significantly greater reduction in plasma phosphate than ZDV/3TC/NVP (p=0.031), but not significantly different from ZDV/3TC/EFV (p=0.968). Similarly, ZDV/3TC/EFV resulted in significantly greater reduction in plasma phosphate than ZDV/3TC/NVP (p=0.036). FEP% progressively increased with HAART duration, more in TDF-treated and ZDV/3TC/EFV-treated groups than ZDV/3TC/NVP (p=0.014); TRP was elevated (>0.86), implying non-maximal phosphate reabsorption. TmP/GFR values were elevated, (>1.35mmol/l).

CONCLUSION

HIV causes kidney dysfunction with reduced phosphate excretion resulting in hyperphosphataemia but HAART improves renal function. Prolonged use of TDF can cause renal toxicity with hypophosphataemia as fractional excretion progressively increased with duration of therapy unlike ZDV/3TC/NVP. The use of different third agents (either NVP or EFV) in zidovudine-based therapy results in significantly different plasma phosphate levels; ZDV/3TC/EFV, like TDF/FTC/EFV, resulted in significantly greater decline in plasma phosphate than ZDV/3TC/NVP. Thus, Evafirenz (EVF) may have similar or synergistic adverse effects with tenofovir disoproxil fumarate (TDF).

HIV-associated immune complex kidney disease

The introduction in the late 20(th) century of combination antiretroviral therapy (cART) to treat patients infected with HIV has changed the natural history of the disease from an acute illness that rapidly culminates in death, to a chronic condition that can be managed with medications. Over the past decade the epidemiology of kidney disease in US patients infected with HIV has changed, perhaps because of the increased availability and use of cART. Patients with HIV infection exhibit unique immunologic characteristics, including immunodeficiency and dysregulation of immunoglobulin synthetic responses and T-cell function, which can result in glomerular immune complex deposition and subsequent kidney injury. This Review examines the differential diagnoses of HIV-associated immune complex kidney diseases (HIVICD), and discusses the clinical manifestations and mechanisms underlying their development. We address the issues associated with treatment, clinical outcomes, and research needs to enhance our ability to diagnose and optimally treat patients with HIVICD.

Prevalence and Pattern of Chronic Kidney Disease in Antiretroviral-Naïve Patients with HIV/AIDS

BACKGROUND

Chronic renal failure and HIV/AIDS are both prevalent in Nigeria. We performed a cross-sectional analysis of renal function in newly diagnosed, treatment-naive HIV-infected patients before initiating highly active antiretroviral therapy.

METHODS

Treatment-inexperienced individuals were recruited. Patients with diabetes mellitus and hypertension were excluded. Plasma creatinine level was used to measure the estimated glomerular filtration rate ([eGFR] by Modification of Diet in Renal Disease equation). Predictors of creatinine and eGFR were determined by univariate and multivariate analyses.

RESULTS

We evaluated 183 patients. In all, 44 (24%) patients had a GFR <60 mL/min/1.73 m(2), implying moderate chronic kidney disease (CKD). Considering the eGFR, 22 (12%) patients had stage 1, 117 (63.9%) stage 2, 13 (7.1%) stage 3, 27 (14.8%) stage 4, and 4 (2.2%) stage 5 CKD. Creatinine inversely correlated with CD4 (r = -.228, P = .025). CD4 predicts creatinine (odds ratio 1.6, 95% confidence interval 1.0-1.8, P = .003).

CONCLUSION

In ART-naive patients, CKD is common, and low eGFR was associated with lower CD4 counts.

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.

The clinical and histological response of HIV-associated kidney disease to antiretroviral therapy in South Africans

BACKGROUND

Little is known about the progression of kidney disease in HIV-infected patients in developing countries in the era of antiretroviral therapy (ART).

METHODS

HIV-infected patients were screened for kidney disease. Kidney biopsies were performed before and after initiation of ART to assess the clinical and histological response to treatment. Data were collected from all participants in accordance with the study protocol. The mean follow-up was 2.4 patient years on ART.

RESULTS

There was a rapid immunological and renal response to ART. The renal response was reflected by a significant rise in the estimated glomerular filtration rate (eGFR) and rapid regression of proteinuria. The histological patterns were highly variable, ranging from non-specific lesions such as mesangial hyperplasia and interstitial nephritis to HIV-immune complex disease (HIV-ICD) with or without features of HIV-associated nephropathy (HIVAN). In the follow-up biopsies, the histological response to treatment was variable with a combination of no change, progression or regression of lesions.

CONCLUSIONS

This study demonstrated a spectrum of renal histological lesions in HIV-associated kidney disease. Initiation of ART produced a rapid and sustained clinical renal response in all participants, irrespective of the histology. Follow-up biopsies showed an inconsistent histological response of lesions to treatment. In lesions that regressed, there appeared to be a discrete lag in histological response when compared with the rapid clinical response.

Renal alterations in feline immunodeficiency virus (FIV)-infected cats: a natural model of lentivirus-induced renal disease changes

Human immunodeficiency virus (HIV) is associated with several renal syndromes including acute and chronic renal failures, but the underlying pathogenic mechanisms are unclear. HIV and feline immunodeficiency virus (FIV) share numerous biological and pathological features, including renal alterations. We investigated and compared the morphological changes of renal tissue of 51 experimentally and 21 naturally infected cats. Compared to the latter, the experimentally infected cats exhibited some mesangial widening and glomerulonephritis, milder proteinuria, and lower tubular and interstitial alterations. The numbers of giant protein tubular casts and tubular microcysts were also lower. In contrast, diffuse interstitial infiltrates and glomerular and interstitial amyloidosis were detected only in naturally infected cats. Similar alterations are found in HIV infected patients, thus supporting the idea of a causative role of FIV infection in renal disease, and underlining the relevance of the FIV and its natural host as an animal model for investigating lentivirus-associated nephropathy.

Collapsing glomerulopathy in 19 patients with systemic lupus erythematosus or lupus-like disease

BACKGROUND AND OBJECTIVES

Collapsing glomerulopathy is a podocytopathy with segmental or global wrinkling and collapse of capillary walls and overlying epithelial cell proliferation. Idiopathic collapsing glomerulopathy is a distinct clinicopathologic entity with significant proteinuria, poor response to immunosuppressive therapy, and rapid progression to renal failure. Collapsing glomerulopathy is associated with viral infections, autoimmune disease, and drugs. This work presents the largest group of collapsing glomerulopathy in patients with SLE.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Clinicopathological features were retrospectively studied in 19 patients with SLE (16 patients) or SLE-like (3 patients) disease with collapsing glomerulopathy.

RESULTS

Initially, 95% of patients had nephrotic syndrome with proteinuria of 3-12 g per 24 hours, creatinine levels of 0.6-9.6 mg/dl, positive lupus serologies, and normal complement levels in 63%. Segmental and/or global collapsing glomerulopathy was seen in 11%-77% of glomeruli. Tubular atrophy with focal microcystic changes and interstitial fibrosis was seen in 35% of patients. Minimal glomerular mesangial deposits were noted in 63% of patients, and extensive foot process effacement was seen in 82% of patients. Initial treatment was with pulse/oral steroids. Follow-up from 13 patients revealed that 7 patients progressed to ESRD at the time of biopsy up to 21 months later, 1 patient returned to normal creatinine (1.1 mg/dl) without proteinuria, and 5 patients had creatinine of 1.2-3.6 mg/dl with proteinuria of 0.37-4 g per 24 hours.

CONCLUSIONS

Collapsing glomerulopathy may be seen in SLE patients presenting with massive proteinuria with or without lupus nephritis, which may have prognostic significance.

Controversies in the pathogenesis of HIV-associated renal diseases

The two most common HIV-associated renal diseases, HIV-associated nephropathy and HIV immune-complex kidney disease, share the common pathologic finding of hyperplasia within the glomerulus. Podocyte injury is central to the pathogenesis of these diseases; however, the source of the proliferating glomerular epithelial cell remains a topic of debate. Parenchymal injury has been linked to direct infection of renal epithelial cells by HIV-1, although the mechanism of viral entry into this non-lymphoid compartment is unclear. Although transgenic rodent models have provided insight into viral proteins responsible for inducing renal disease, such models have substantial limitations. Rodent HIV-1 models, for instance, cannot replicate all features of immune activation, a process that could have an important role in the pathogenesis of the HIV-associated renal diseases.

CKD in HIV-infected patients other than HIV-associated nephropathy

A spectrum of kidney diseases in HIV-infected patients has been reported both before and after the introduction of highly active antiretroviral therapy (HAART). Kidney syndromes affecting HIV-infected patients include CKD as well as proteinuria, nephrotic syndrome, and acute nephritic syndrome. Thrombotic microangiopathy should be considered in patients with kidney disease and typical clinical characteristics. As the HIV-infected population ages, there is increased concern regarding the incidence of vascular and metabolic disease, leading to an increased burden of CKD. Although HIV-associated nephropathy is still the major cause of nephrotic syndrome in HIV-infected patients, immune complex glomerulonephritis (ICGN) still comprises a substantial proportion of the disease burden, especially in people of European origin. Genetic investigations into the underpinnings of the various histologic expressions of HIV-associated kidney disease hold great promise. The single most important diagnostic test to differentiate various forms of kidney disease in HIV-infected patients is a kidney biopsy. The results of treating kidney disease in HIV-infected patients remain unclear, and properly designed randomized controlled trials of the treatment of ICGN with HAART and other approaches are desperately needed.

Immune complex renal disease and human immunodeficiency virus infection

Immune complex glomerulonephritis is a common diagnosis in renal biopsy series of human immunodeficiency virus (HIV)-infected patients. There are a variety of glomerulonephritides associated with HIV infection, including IgA nephropathy, membranoproliferative glomerulonephritis, membranous nephropathy, lupus-like glomerulonephritis, immunotactoid glomerulopathy, and fibrillary glomerulonephritis. In addition, HIV-related proteins may be implicated in circulating immune complexes directly related to a response to the infection. In some cases, the relationship of the HIV infection to the glomerulonephritis is unclear. HIV infection is associated with the development of polyclonal hypergammaglobulinemia, which can promote the development of circulating immune complexes. It is not clear if HIV-associated glomerulonephritis is caused by the passive trapping of these circulating immune complexes or the in situ deposition of antibodies binding to HIV viral antigens. Some renal lesions that are seen in the setting of HIV infection more likely may be related to the presence of a co-infection such as hepatitis C virus infection. The optimal therapy for immune complex glomerulonephritis in the setting of HIV infection is unknown. Because of the underlying immunosuppressed state of many HIV-infected patients, caution with traditional cytotoxic therapies is advised. The role of antiretroviral therapy in modifying the course of these renal lesions is unclear.

Pathogenesis of HIV-associated nephropathy

Human immunodeficiency virus-associated nephropathy (HIVAN) is a leading cause of end-stage renal disease in the HIV-1-seropositive population. HIVAN, which is characterized by heavy proteinuria and a rapid decline in renal function, is caused by infection and subsequent expression of viral genes in renal epithelial cells, although the exact mechanism of viral entry into these cells is unknown. The infected renal epithelium is a distinct compartment that supports the evolution of viral strains that may diverge from those found in the patient's blood. Research using animal models and in vitro studies has shown that vpr and nef are the HIV-1 genes most responsible for inducing the characteristic clinical and histopathologic syndrome of HIVAN. Dysregulation of several host factors, including mediators of inflammation, apoptosis, proliferation, transcription, and cell-cell interactions, are also critical factors in determining whether infection of the renal epithelium will lead to HIVAN. Additional research is required to delineate the mechanisms of HIVAN pathogenesis further so that more effective interventions can be implemented to prevent and treat this disease.

Cystatin C and creatinine in an HIV cohort: the nutrition for healthy living study

BACKGROUND

Human immunodeficiency virus (HIV)-infected persons have an increased risk of chronic kidney disease (CKD). Serum creatinine level may underestimate the prevalence of CKD in subjects with decreased lean body mass or liver disease. Level of serum cystatin C, an alternative kidney function marker, is independent of lean body mass.

STUDY DESIGN

Cross-sectional.

SETTING & PARTICIPANTS

250 HIV-infected subjects on highly active antiretroviral therapy in the Nutrition for Healthy Living (NFHL) cohort; 2,628 National Health and Nutrition Examination Survey (NHANES) 2001-2002 subjects.

PREDICTORS & OUTCOMES

Comparison of serum creatinine levels in NFHL to those in NHANES subjects; comparison of CKD in NFHL subjects ascertained using serum creatinine versus cystatin C levels.

MEASUREMENTS

Standardized serum creatinine, serum cystatin C, glomerular filtration rate (GFR) estimated from serum creatinine and cystatin C levels.

RESULTS

Creatinine levels were lower in NFHL than NHANES subjects despite greater rates of hepatitis, diabetes, and drug use (mean difference, -0.18 mg/dL; P < 0.001 adjusted for age, sex, and race). Of NFHL subjects, only 2.4% had a creatinine-based estimated GFR less than 60 mL/min/1.73 m(2), but 15.2% had a cystatin-based estimated GFR less than 60 mL/min/1.73 m(2).

LIMITATIONS

GFR was estimated rather than measured. Other factors in addition to GFR may affect creatinine and cystatin C levels. Measurements of proteinuria were not available.

CONCLUSIONS

Serum creatinine levels may overestimate GFRs in HIV-infected subjects. Kidney disease prevalence may be greater than previously appreciated.

HIV-1 and HIV-Associated Nephropathy 25 Years Later

Twenty-five years after the first published description of AIDS, HIV-associated nephropathy (HIVAN) remains an important cause of kidney disease in HIV-infected patients. The pathogenesis of HIVAN involves direct HIV infection of the kidney, with both viral and host genetic factors playing an important role. The widespread use of antiretroviral therapy has influenced the epidemiology of HIV-related kidney disease, and the nephrology community should support efforts to improve access to therapy and limit HIV transmission in susceptible minority populations. This article reviews the history of HIV and HIVAN, focusing on advances in the understanding of pathogenesis, epidemiology, and treatment.

Infection and glomerulonephritis

Glomerular injury, occurring either as primary glomerular disease or as part of a systemic disease process, is usually a result of immune-mediated mechanisms. The morphologic reaction pattern has a diverse spectrum of appearance, ranging from normal by light microscopy in minimal change disease to crescentic forms of glomerulonephritis, with conspicuous disruption of the normal glomerular morphology. The mechanisms of glomerular immune deposit formation include trapping of circulating antigen-antibody complexes and the in situ formation of immune complexes within the glomerulus. While the majority of postinfectious immune-complex-mediated glomerulonephritides are believed to result from the deposition of circulating antigen-antibody complexes, preformed outside of the kidney and secondarily deposited in the kidney, the notion of forming in situ antigen-antibody complexes to either planted antigens or to integral structural components of the glomerulus, through "cross-reacting" autoimmune reactions, is gaining popularity in a variety of forms of glomerulonephritides. Patients with HIV infection may develop a spectrum of renal pathology, the glomerular manifestations of which include both antigen-antibody complex and nonimmune-complex-mediated pathogenetic mechanisms. Similarly, patients with Streptococcal infections, Hepatitis B virus, or Hepatitis C virus infection may develop a spectrum of glomerulonephritides, which are predominantly immune-complex-mediated. Therapy for glomerular diseases due to HIV, hepatitis B, or C virus infections remains a challenge.

Emerging Paradigms in the Renal Pathology of Viral Diseases

This review considers recent information that illuminates pathogenetic mechanisms that involve three of the major viral infections that cause renal injury in the form of HIV-associated nephropathy, polyoma virus nephropathy, and hepatitis C virus-associated glomerulonephritis.

DEC-205-mediated internalization of HIV-1 results in the establishment of silent infection in renal tubular cells

HIV-1 infection of renal cells has been proposed to play a role in HIV-1-associated nephropathy. Renal biopsy data further suggest that renal tubular cells may serve as reservoir for HIV-1. The mechanism by which HIV-1 enters these cells has not been identified. Renal tubular cells do not express any of the known HIV-1 receptors, and our results confirmed lack of the expression of CD4, CCR5, CXCR4, DC-SIGN, or mannose receptors in tubular cells. The aim of this study, therefore, was to determine the mechanism that enables viral entry into renal tubular cells. An in vitro model was used to study the HIV-1 infection of human kidney tubular (HK2) cells and to identify the receptor that enables the virus to enter these cells. Results of these studies demonstrate that the C-type lectin DEC-205 acts as an HIV-1 receptor in HK2 cells. Interaction of HIV-1 with DEC-205 results in the internalization of the virus and establishment of a nonproductive infection. HIV-1-specific strong-stop DNA is detected in the infected HK2 cells for at least 7 d, and the virus can be transmitted in trans to sensitive target cells. HIV-1 entry is blocked by pretreatment with specific anti-DEC-205 antibody. Moreover, expression of DEC-205 in cells that lack the DEC-205 receptors renders them susceptible to HIV-1 infection. These findings suggest that DEC-205 acts as an HIV-1 receptor that mediates internalization of the virus into renal tubular cells, from which the virus can be rescued and disseminated by encountering immune cells.

Dual tropism of HIV-1 envelopes derived from renal tubular epithelial cells of patients with HIV-associated nephropathy

The phenotype of HIV-1 gp120 envelope derived from renal epithelium and peripheral blood mononuclear cells (PBMC) of patients with HIV-associated nephropathy was investigated in vitro. Chimeric viruses were derived from kidney or blood and used to infect primary CD4+T cells, cell lines expressing single co-receptors and a renal epithelial cell line HPT-1. HIV-1 variants derived from renal epithelium were dual tropic whereas simultaneously derived viruses from PBMC were R5-tropic. Utilization of alternative co-receptors CCR3, BONZO and BOB, also differed.

Persistent NF-kappaB activation in renal epithelial cells in a mouse model of HIV-associated nephropathy

Human immunodeficiency virus (HIV)-associated nephropathy (HIVAN) is caused, in part, by direct infection of kidney epithelial cells by HIV-1. In the spectrum of pathogenic host-virus interactions, abnormal activation or suppression of host transcription factors is common. NF-kappaB is a necessary host transcription factor for HIV-1 gene expression, and it has been shown that NF-kappaB activity is dysregulated in many naturally infected cell types. We show here that renal glomerular epithelial cells (podocytes) expressing the HIV-1 genome, similar to infected immune cells, also have a dysregulated and persistent activation of NF-kappaB. Although podocytes produce p50, p52, RelA, RelB, and c-Rel, electrophoretic mobility shift assays and immunocytochemistry showed a predominant nuclear accumulation of p50/RelA-containing NF-kappaB dimers in HIV-1-expressing podocytes compared with normal. In addition, the expression level of a transfected NF-kappaB reporter plasmid was significantly higher in HIVAN podocytes. The mechanism of NF-kappaB activation involved increased phosphorylation of IkappaBalpha, resulting in an enhanced turnover of the IkappaBalpha protein. There was no evidence for regulation by IkappaBbeta or the alternate pathway of NF-kappaB activation. Altered activation of this key host transcription factor likely plays a role in the well-described cellular phenotypic changes observed in HIVAN, such as proliferation. Studies with inhibitors of proliferation and NF-kappaB suggest that NF-kappaB activation may contribute to the proliferative mechanism in HIVAN. In addition, because NF-kappaB regulates many aspects of inflammation, this dysregulation may also contribute to disease severity and progression through regulation of proinflammatory processes in the kidney microenvironment.

HIV-associated renal disorders: recent insights into pathogenesis and treatment

Renal electrolyte disorders, acute renal failure, and a variety of chronic renal diseases are common in HIV-infected patients. Glomerular disorders include IgA nephropathy, cryoglobulinemia, amyloidosis, and a lupus-like immune complex glomerulopathy. The most attention has been focused on collapsing glomerulopathy associated with nephrotic syndrome and progressive renal failure, which appears to be unique for patients with HIV/AIDS, called HIV-associated nephropathy (HIVAN), and it occurs predominantly in African American patients. Investigations in humans and in a transgenic mouse model reveal direct infection of renal epithelial cells by HIV and toxic cellular and immunologic processes mediated by HIV glycoproteins as the principal pathophysiology of HIVAN. Highly active antiretroviral treatment may be associated with an improved renal outcome and even reversal of kidney disease in some patients. Treatment with angiotensin-converting enzyme inhibitors may avert progression of HIVAN to end-stage kidney disease and result in superior patient and kidney survival as compared with untreated patients.

p300 modulates HIV-1 gp120-induced apoptosis in human proximal tubular cells: associated with alteration of TGF-beta and Smad signaling

p300 is a key protein, which determines acceleration or deceleration of signal transduction. Recently, renal proximal tubular cells have not only been found to be a harboring site for HIV-1 but have also been shown to undergo apoptosis in response to HIV-1 exposure. Both HIV-1 and its envelop glycoprotein, i.e. gp120, triggered tubular cell apoptosis in the same magnitude. In the present study, we evaluated the role of p300 in gp120-induced tubular cell apoptosis and associated downstream signaling. We have demonstrated that by transient transfection assays, p300 significantly increases susceptibility of human proximal renal tubular HK-2 cells to apoptosis triggered by HIV-1 gp120. A mutant p300, missing the E1A/TFIIB binding site, fails to produce such sensitization potential. Smad7 and an anti-TGF-beta antibody rescue the p300 sensitization. Furthermore, p300 and HIV-1 gp120 synergistically increase TGF-beta, ATF-2 and activating protein-1 (AP-1) expression. In addition, HIV-1 gp120 results in phosphorylation of Smad2 and decreases c-Jun. These findings suggest that p300 acts as a potent transcriptional cofactor in HIV-1 gp120-induced apoptosis via TGF-beta and Smad signaling.

Focal glomerulosclerosis in proviral and c-fms transgenic mice links Vpr expression to HIV-associated nephropathy

Clinical and morphologic features of human immunodeficiency virus (HIV)-associated nephropathy (HIVAN), such as proteinuria, sclerosing glomerulopathy, tubular degeneration, and interstitial disease, have been modeled in mice bearing an HIV proviral transgene rendered noninfectious through a deletion in gag/pol. Exploring the genetic basis of HIVAN, HIV transgenic mice bearing mutations in either or both of the accessory genes nef and vpr were created. Proteinuria and focal glomerulosclerosis (FGS) only developed in mice with an intact vpr gene. Transgenic mice bearing a simplified proviral DNA (encoding only Tat and Vpr) developed renal disease characterized by FGS in which Vpr protein was localized to glomerular and tubular epithelia by immunohistochemistry. The dual transgenic progeny of HIV[Tat/Vpr] mice bred to HIV[DeltaVpr] proviral transgenic mice displayed a more severe nephropathy with no apparent increase in Vpr expression, implying that multiple viral genes contribute to HIVAN. However, the unique contribution of macrophage-specific Vpr expression in the development of glomerular disease was underscored by the induction of FGS in multiple murine lines bearing a c-fms/vpr transgene.

Mapping a locus for susceptibility to HIV-1-associated nephropathy to mouse chromosome 3

HIV-1-associated nephropathy (HIVAN) is a major complication of HIV-1 infection with distinct pathologic features. Introduction of the HIV-1 genome into mice results in a renal disease with all of the histologic and clinical hallmarks of HIVAN on the FVB/N genetic background (TgFVB). We assessed the influence of genetic background on the development or progression of HIVAN by making F1 hybrids of TgFVB with five other inbred strains (CBA, DBA/2, CAST/Ei, C3H/He, BALB/c) and determining phenotypes relevant to renal failure among transgenic offspring (histology, blood urea nitrogen, proteinuria, serum albumin, and serum cholesterol). We found striking variation in phenotypes among F1s, ranging from severe renal disease to no renal disease whatsoever (P<0.001 for ANOVA across all groups). To map genes responsible for this variation, we produced a backcross of TgFVB/CAST F1 x TgFVB. By genome-wide analysis of linkage in 185 heterozygous transgenic backcross mice, we identified a locus on chromosome 3A1-3, HIVAN1, that showed highly significant linkage to renal disease [logarithm of odds (lod) score 4.9 at D3Mit203, accounting for 15% of the variance in renal disease]. Other loci on chromosomes 11, 14, and 16 were suggestive of linkage to renal disease, and a locus on chromosome 9 influenced serum cholesterol but not nephropathy. Interestingly, HIVAN1 is syntenic to human chromosome 3q25-27, an interval showing suggestive evidence of linkage to various nephropathies. These findings demonstrate a strong genetic influence on HIVAN and demonstrate a major renal disease susceptibility locus on mouse chromosome 3A1-3.

Long-term renal survival in HIV-associated nephropathy with angiotensin-converting enzyme inhibition

BACKGROUND

Human immunodeficiency virus (HIV)-associated nephropathy (HIVAN) is the most common cause of end-stage renal disease (ESRD) in HIV-infected patients. Angiotensin-converting enzyme (ACE) inhibition has previously shown a short-term benefit in HIVAN. This study examines the long-term effects of ACE inhibition on renal survival in HIVAN.

METHODS

In this single-center prospective cohort study, 44 patients with biopsy-proven HIVAN were enrolled prior to the onset of severe renal insufficiency (serum creatinine <or=2.0 mg/dL), throughout the study period of 1890 days (5.1 years). Twenty-eight patients received fosinopril, 10 mg/day, and 16 were followed as controls. End points included ESRD and death. Treatment effects on survival were evaluated with Kaplan-Meier product-limit estimates. Survival is also described as absolute median number of days.

RESULTS

Median renal survival of treated patients was 479.5 days, with only one patient developing ESRD. All untreated controls progressed to ESRD, with a median renal survival of 146.5 days (P < 0.0001). There were no significant differences between treatment and control groups in age, significant exposure to antiretroviral therapy, defined as >or=two antiviral drugs for >or=30 consecutive days, CD4 lymphocyte count, initial median serum creatinine concentration, or proteinuria. Risk of renal failure was reduced with ACE inhibitors (RR = 0.003, P < 0.0001). Exposure to antiretroviral therapy did not have a significant impact on the risk of renal failure. Of the ACE inhibitor-treated group, 87.5% survived compared with 21.4% of the control group (P < 0.001).

CONCLUSION

ACE inhibition initiated prior to severe renal insufficiency may offer long-term renal survival benefits in HIVAN. Diagnosis should be sought early in patients with clinical signs suggestive of HIVAN.

The HIV-associated renal diseases: current insight into pathogenesis and treatment

Since the description of a new renal syndrome in patients with the acquired immunodeficiency syndrome (AIDS) in the middle 1980s, much has been learned regarding the association of human immunodeficiency virus (HIV) infection and renal disease. The HIV-associated renal diseases represent a spectrum of clinical and histopathologic conditions. In this review, epidemiologic and clinical aspects of HIV-associated renal diseases are presented. Particular attention is placed on the pathologic and pathophysiologic mechanisms involved in HIV-associated focal glomerulosclerosis, immune complex-mediated disease, and thrombotic microangiopathies. Pharmaceutical treatment options, including the use of glucocorticoids, angiotensin-converting enzyme (ACE) inhibitors, and highly active antiretroviral therapy, are discussed. The therapeutic option of renal transplantation is presented, with insight into new clinical and basic research supporting a possible role of immunosuppressive therapy in this already immunocompromised patient population.

HIV-associated nephropathy: Epidemiology, pathogenesis, and treatment

Initially described in 1984, human immunodeficiency virus-associated nephropathy (HIVAN) has now become a common disease within the HIV-seropositive population. It is a focal segmental glomerulosclerosis causing rapid deterioration of renal function. It is the most common cause of chronic renal disease in HIV patients and occurs almost exclusively in blacks. Through murine and human studies, it is now clear that HIVAN is caused by a direct effect of infection of renal cells by HIV-1 and that the virus actively replicates within renal cells. How the virus causes disease within cells is not yet understood, but there is evidence for factors within infected cells causing both proliferation and apoptosis. Steroids, angiotensin converting enzyme (ACE) inhibitors, and highly active antiretroviral therapy (HAART) have been used for the treatment of HIVAN, with HAART, in particular, showing a dramatic improvement in both the pathologic changes and clinical course of HIVAN.

Human immunodeficiency virus infection and renal failure

Renal manifestations are an important component of HIV disease. Renal disease significantly contributes to morbidity and mortality in patients with HIV. Great progress has been made in identifying specific glomerular lesions and its pathogenesis. Newer antiretroviral agents offer great promise in preventing renal disease and also in patients with established HIVAN. Survival of patients with HIV and ESRD (irrespective of cause) who are receiving RRT continues to improve over the years. Acute reversible renal failure, a preventable complication, is also declining in hospitalized HIV patients. More and more physicians, who in the past were reluctant to care for patients with HIV and renal failure because of grim prognosis, are now becoming familiar with the renal sequelae and are encouraged by recent favorable results. As knowledge about viruses is expanding, the proper use of newer highly effective antiretroviral and other agents in complicated patients should further improve both the survival and quality of life in patients with HIV infection and renal disease.

Treatment of HIV-associated nephropathy

HIV-associated nephropathy (HIVAN) is the most common cause of renal failure in patients infected with type 1 human immunodeficiency virus (HIV-1). The renal prognosis for HIVAN is poor and is typically associated with rapid progression to renal death. We report a patient with biopsy-proven HIVAN who was successfully treated with corticosteroids and review the currently available evidence supporting the specific treatments of this condition. A 34-year-old African-American male with a 2-year history of uncomplicated HIV disease developed progressive azotemia despite treatment with highly active antiretroviral therapy (HAART). He was treated with an uncomplicated 4-month course of prednisone, which improved his serum creatinine from 2.9 to 1.9 mg/dl and decreased his degree of proteinuria from 8 to 2.1 g/day. Two years post-steroid treatment his renal function remains stable. Increasing evidence supports that both ACE inhibitors and HAART are effective in preventing and in some cases of reversing HIVAN induced renal failure. In selected patients who progress despite these measures, a limited course of corticosteroid may achieve long-standing disease remissions. In general, with adequate supervision, corticosteroid therapy appears to be well tolerated and has an acceptable side effect profile. Although persuasive in view of the abysmal natural history of HIVAN, the currently available studies are subject to major methodological limitations. Appropriate randomized controlled trials are urgently required in order to further examine the efficacy, optimal timing, and potential side effects of these treatments.

Association of parvovirus B19 infection with idiopathic collapsing glomerulopathy

BACKGROUND

Collapsing glomerulopathy (CG), a disorder with severe glomerular and tubular involvement, occurs either as an idiopathic lesion or in some patients with human immunodeficiency virus (HIV) infection known as HIV-associated nephropathy (HIVAN). We previously reported a renal transplant recipient with de novo CG and red cell aplasia in association with persistent parvovirus B19 (PVB19) infection. This prompted us to look for an association between PVB19 infection and CG.

METHODS

DNA from archived biopsies of patients with CG was analyzed for PVB19 by polymerase chain reaction (PCR). Results were compared with HIVAN, idiopathic focal segmental glomerulosclerosis (FSGS), and controls. In situ hybridization (ISH) was done to localize PVB19 in renal biopsies. Peripheral blood specimens of patients with CG, HIV infection, healthy controls, and randomly selected hospitalized patients (sick controls) were also analyzed for PVB19.

RESULTS

PVB19 DNA was detected in renal biopsies of 18 out of 23 (78.3%) patients with CG, 3 out of 19 (15.8%) with HIVAN, 6 out of 27 (22.2%) with FSGS, and 7 out of 27 (25.9%) controls (P < 0.01, CG vs. HIVAN, FSGS, and controls). PVB19 was detected in peripheral blood of 7 out of 8 (87.5%) CG patients, 3 out of 22 (13.6%) with HIV infection, 4 out of 133 (3%) healthy controls, and 2 out of 50 (4%) sick controls (P < 0.001, CG vs. HIV infected, healthy, and sick controls). PVB19 was identified in glomerular parietal and visceral epithelial and tubular cells by ISH.

CONCLUSIONS

The significantly higher prevalence of PVB19 DNA in renal biopsies and peripheral blood of CG patients suggests a specific association between PVB19 infection and CG. In susceptible individuals, renal epithelial cell infection with PVB19 may induce CG.

Up-regulation of a fibroblast growth factor binding protein in children with renal diseases

BACKGROUND

Basic fibroblast growth factor (bFGF) is an angiogenic growth factor that is involved in renal growth and the pathogenesis of renal diseases. We have detected high levels of bFGF accumulated in the kidney of HIV-transgenic mice and in children with HIV-associated renal diseases and the hemolytic uremic syndrome (HUS). However, the mechanism modulating the activity of bFGF under these circumstances is poorly understood. We carried out experiments to determine whether a secreted binding protein (FGF-BP) that modulates the activity of bFGF during the process of tumor growth was expressed in pediatric kidneys and to define whether the expression of FGF-BP was altered in pediatric renal diseases associated with high levels of bFGF.

METHODS

Immunohistochemistry and in situ hybridization studies were done in 41 renal sections from children with HIV nephropathies, HUS, other pediatric renal diseases, controls, and fetal kidneys. Western blots and reverse transcriptase-polymerase chain reaction studies were done in selected urine samples and cultured renal cells. Recombinant FGF-BP was produced to study the mitogenic activity of FGF-BP in cultured human renal proximal tubular epithelial cells (RPTEcs).

RESULTS

The expression of FGF-BP was up-regulated predominately in renal tubular epithelial cells in children with renal tubular injury, HIV-associated nephropathy (HIVAN), and HUS, and FGF-BP was secreted in the urine of these patients. FGF-BP was also abundantly expressed in developing fetal renal tubules. Recombinant FGF-BP enhanced the mitogenic effects of bFGF in cultured human RPTEcs.

CONCLUSIONS

The localization of FGF-BP in renal tubular epithelial cells could provide a mechanism by which the activity of bFGF is modulated in developing and regenerating renal tubules of children.

Role of 14-3-3epsilon, c-Myc/Max, and Akt phosphorylation in HIV-1 gp 120-induced mesangial cell proliferation

Focal glomerulosclerosis (FGS) is the predominant glomerular lesion in patients with human immunodeficiency virus (HIV)-associated nephropathy. Initial mesangial cell hyperplasia and subsequent hypoplasia are common features of FGS. In the present study we evaluated the effect of HIV-1 glycoprotein (gp) 120 on human mesangial cell (HMC) growth. HIV-1 gp 120 stimulated HMC proliferation at lower concentrations, whereas it suppressed cell proliferation at higher concentrations. In parallel to the modulation of cell growth, gp 120 at low concentrations resulted in an increase in the expression of c-Myc, Max, and 14-3-3epsilon proteins and phosphorylation of ATP-dependent tyrosine kinases (Akt) at Ser(473). However, the expression of these proteins decreased with increasing concentrations of gp 120. Furthermore, gp 120 also exhibited a dose-dependent inhibition of Akt phosphorylation at Ser-473 without any significant alteration of Akt expression. Little or no effects of gp 120 were observed on the expression of extracellular signal-regulated kinase (ERK), phospho-ERK, Bcl-2, and Bax proteins. At a higher concentration, gp 120 not only promoted HMC apoptosis but also enhanced expression of Fas and FasL. These results suggest that HIV-1 gp 120 induces alterations in conflicting survival signaling pathways that contribute to the potential dual effects of gp 120 in promoting or inhibiting HMC proliferation.

HIV-associated nephropathy: case study and review of the literature

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.

Renal epithelium is a previously unrecognized site of HIV-1 infection

The striking emergence of an epidemic of HIV-related renal disease in patients with end-stage renal disease provided the rationale for the exploration of whether HIV-1 directly infects renal parenchymal cells. Renal glomerular and tubular epithelial cells contain HIV-1 mRNA and DNA, indicating infection by HIV-1. In addition, circularized viral DNA, a marker of recent nuclear import of full-length, reverse-transcribed RNA, was detected in the biopsies, suggesting active replication in renal tissue. Infiltrating infected leukocytes harbored more viral mRNA than renal epithelium. Identification of this novel reservoir suggests that effectively targeting the kidney with antiretrovirals may be critical for patients who are seropositive with renal disease. Thus, renal epithelium constitutes a unique and previously unrecognized cell target for HIV-1 infection.

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 Deltagag-pol HIV-1 genome, which develops glomerulosclerosis, cutaneous papillomas, and cataracts.

METHODS

We developed mice transgenic for a Deltagag-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 Deltagag-pol-nef mice compared with the Deltagag-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 Deltagag-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, Deltagag-pol-nef mice were bred with nef mice; these dual-transgenic mice developed renal disease that generally resembled that seen in Deltagag-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.

Infection of mesangial cells with HIV and SIV: identification of GPR1 as a coreceptor

BACKGROUND

Mesangial cells are an important component of the glomerulus. Dysfunction of mesangial cells is thought to be involved in the development of human immunodeficiency virus type 1 (HIV-1)-associated nephropathy (HIVAN). HIVAN is a structural renal failure frequently observed in patients with acquired immune deficiency syndrome. However, the susceptibility of mesangial cells to HIV-1 is disputable. More than ten G protein-coupled receptors, including chemokine receptors, have been shown to act as HIV-1 coreceptors that determine the susceptibilities of cells to HIV-1 strains with specific cell tropisms.

METHODS

We examined the susceptibility of mesangial cells to various HIV-1, HIV type 2 (HIV-2) and simian immunodeficiency virus (SIV) strains. Expression of CD4 and HIV/SIV coreceptors was examined by Western blotting and polymerase chain reaction.

RESULTS

Mesangial cells were found to be susceptible to HIV-1 variant and mutants that infect brain-derived cells, but highly resistant to T-tropic (X4), M-tropic (R5) or dual-tropic (X4R5) HIV-1 strains. In addition, mesangial cells were also susceptible to HIV-2 and SIV strains that infect the brain-derived cells. Among HIV/SIV coreceptors we tested, the expression of GPR1 mRNA was detected in mesangial cells. Expression of CD4 mRNA and protein was also detected in them. Mesangial cells and GPR1-transduced CD4-positive cells showed similar susceptibilities to the HIV-1 variant and mutants and HIV-2 and SIV strains.

CONCLUSIONS

CD4 and GPR1 mRNAs were detected in mesangial cells. Mesangial cells were susceptible to HIV/SIV strains that use GPR1 as a coreceptor. Our findings suggest that an orphan G protein-coupled receptor, GPR1, is a coreceptor expressed in mesangial cells. It remains to be investigated whether the interaction of mesangial cells with specific HIV-1 strains through GPR1 plays a role in the development of HIVAN.

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.

Chemokine receptor CCR5 and CXCR4 expression in HIV-associated kidney disease

The chemokine receptors CCR5 and CXCR4 have been identified as essential coreceptors for entry of HIV-1 strains into susceptible cells. Direct infection of renal parenchymal cells has been implicated in the pathogenesis of HIV-associated renal disease, although data are conflicting. The localization of CCR5 and CXCR4 in kidneys with HIV-associated renal disease is unknown. Formalin-fixed, paraffin-embedded renal biopsies from patients with HIV-associated nephropathy (HIVAN) (n = 13), HIV-associated immune complex glomerulonephritis (n = 3), HIV-associated thrombotic microangiopathy (n = 1), and HIV-negative patients with collapsing glomerulopathy (n = 8) were analyzed in this study. Cellular sites of expression of CCR5 and CXCR4 were identified by immunohistochemistry and by in situ hybridization. The presence of HIV-1 was detected by immunohistochemistry and by in situ hybridization. Expression of both chemokine receptors CCR5 and CXCR4 was undetectable in intrinsic glomerular, tubular, and renovascular cells in all analyzed cases. In the presence of tubulointerstitial inflammation, CCR5 and CXCR4 expression was localized to infiltrating mononuclear leukocytes. HIV-1 protein was undetectable by immunohistochemistry in all cases of HIV-associated renal disease. HIV-1 RNA was identified in one case of HIVAN but was restricted to infiltrating leukocytes. HIV-1 RNA was not detected in intrinsic renal cells in all analyzed cases. Identifying the cellular expression of HIV-coreceptors CCR5 and CXCR4 may help to clarify which tissues are permissive for direct HIV infection. These data do not support a role of productive HIV-1 infection of renal parenchymal cells in the pathogenesis of HIV-associated renal disease.