Jonathan A. Winston

Guidelines for the Management of Chronic Kidney Disease in HIV-Infected Patients: Recommendations of the HIV Medicine Association of the Infectious Diseases Society of America

Samir K. Gupta, Joseph A. Eustace, Jonathan A. Winston, Ivy I. Boydstun, Tejinder S. Ahuja, Rudolph A. Rodriguez, Karen T. Tashima, Michelle Roland, Nora Franceschini, Frank J. Palella, Jeffrey L. Lennox, Paul E. Klotman, Sharon A. Nachman, Stephen D. Hall, and Lynda A. Szczech Divisions of Infectious Diseases and Clinical Pharmacology, Department of Medicine, Indiana University School of Medicine, Indianapolis; Division of Nephrology, Johns Hopkins University, School of Medicine and Department of Epidemiology, Bloomberg School of Public Health, Baltimore, Maryland; Division of Nephrology, Department of Medicine, Mount Sinai School of Medicine, New York, and Division of Nephrology and Hypertension and Division of Infectious Diseases, Department of Pediatrics, State University of New York, Stony Brook; Division of Nephrology, Department of Medicine, University of Texas Medical Branch, Galveston; Division of Nephrology, Department of Medicine, San Francisco General Hospital and Positive Health Program at San Francisco General Hospital and the UCSF AIDS Research Institute, Department of Medicine, University of California at San Francisco; Division of Infectious Diseases, Department of Medicine, The Miriam Hospital, Brown Medical School, Providence, Rhode Island; Division of Nephrology and Hypertension, Department of Medicine, University of North Carolina at Chapel Hill, and Duke Clinical Research Institute and the Division of Nephrology, Department of Medicine, Duke University Medical Center, Durham, North Carolina; Division of Infectious Diseases, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois; and Grady Infectious Disease Program, Division of Infectious Diseases, Department of Medicine, Emory University, Atlanta, Georgia

A Phase 1/2 Clinical Trial of Enzyme Replacement in Fabry Disease: Pharmacokinetic, Substrate Clearance, and Safety Studies

Fabry disease results from deficient alpha-galactosidase A (alpha-Gal A) activity and the pathologic accumulation of the globotriaosylceramide (GL-3) and related glycosphingolipids, primarily in vascular endothelial lysosomes. Treatment is currently palliative, and affected patients generally die in their 40s or 50s. Preclinical studies of recombinant human alpha-Gal A (r-halphaGalA) infusions in knockout mice demonstrated reduction of GL-3 in tissues and plasma, providing rationale for a phase 1/2 clinical trial. Here, we report a single-center, open-label, dose-ranging study of r-halphaGalA treatment in 15 patients, each of whom received five infusions at one of five dose regimens. Intravenously administered r-halphaGalA was cleared from the circulation in a dose-dependent manner, via both saturable and non-saturable pathways. Rapid and marked reductions in plasma and tissue GL-3 were observed biochemically, histologically, and/or ultrastructurally. Clearance of plasma GL-3 was dose-dependent. In patients with pre- and posttreatment biopsies, mean GL-3 content decreased 84% in liver (n=13), was markedly reduced in kidney in four of five patients, and after five doses was modestly lowered in the endomyocardium of four of seven patients. GL-3 deposits were cleared to near normal or were markedly reduced in the vascular endothelium of liver, skin, heart, and kidney, on the basis of light- and electron-microscopic evaluation. In addition, patients reported less pain, increased ability to sweat, and improved quality-of-life measures. Infusions were well tolerated; four patients experienced mild-to-moderate reactions, suggestive of hypersensitivity, that were managed conservatively. Of 15 patients, 8 (53%) developed IgG antibodies to r-halphaGalA; however, the antibodies were not neutralizing, as indicated by unchanged pharmacokinetic values for infusions 1 and 5. This study provides the basis for a phase 3 trial of enzyme-replacement therapy for Fabry disease.

Highly Active Antiretroviral Therapy and the Epidemic of HIV+ End-Stage Renal Disease

The rise in the number of patients with HIV-associated nephropathy and HIV-infection with end-stage renal disease (HIV+ ESRD) continues to be a substantial concern for the ESRD program. In order to assess the impact of highly active antiretroviral therapy (HAART) on the progression of patients with AIDS to the development of ESRD and to project the prevalence of HIV+ ESRD through 2020, a mathematical model of the dynamics of HIV+ infection in the ESRD population was developed. Epidemiologic data on AIDS and HIV+ ESRD among black individuals in the United States were obtained since 1991 from the Centers for Disease Control and Prevention and US Renal Data System, respectively. The model was constructed to predict the prevalence of HIV+ ESRD incorporating the current rate of growth in AIDS prevalence. Two possible trends were considered: linear AIDS growth and exponential AIDS growth. The likely effectiveness of HAART in slowing progression to HIV+ ESRD was estimated from the best fit of the model to the data after 1995, when HAART was introduced. The model was then used to evaluate recent data and to project the prevalence of HIV+ ESRD through 2020. The model suggested that HAART has reduced the rate of progression from AIDS to HIV+ ESRD by 38%. The model projected an increase in HIV+ ESRD prevalence in the future as a result of the increase in the AIDS population among black individuals. This increase was predicted even assuming a 95% reduction in the progression from AIDS to HIV+ ESRD. Despite the potential benefit of HAART, the prevalence of HIV+ ESRD in the United States is expected to rise in the future as a result of the expansion of the AIDS population among black individuals. It is concluded that prevention of progression to ESRD should focus on early antiretroviral treatment of HIV-infected patients who have evidence of HIV-associated nephropathy.

Chronic kidney disease in HIV infection: an urban epidemic.

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

Endothelial Dysfunction in Patients with Chronic Kidney Disease Results from Advanced Glycation End Products (AGE)-Mediated Inhibition of Endothelial Nitric Oxide Synthase through RAGE Activation

BACKGROUND AND OBJECTIVES Advanced glycation end products, known pro-inflammatory and pro-oxidative compounds that accumulate in patients with chronic kidney disease, may play a major role in their high prevalence of endothelial dysfunction and subsequent cardiovascular disease. This study examined the association of advanced glycation end product accumulation with cellular receptor for advanced glycation end product expression and endothelial dysfunction as well as the mechanisms of this association in chronic kidney disease. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS A cross-sectional study was conducted of ambulatory patients without diabetes and with different stages of chronic kidney disease (n = 51), compared with gender- and age-matched healthy subjects. Fasting blood was obtained for measurement of advanced glycation end products and mRNA receptor for advanced glycation end product expression in peripheral blood mononuclear cells. Endothelial reactivity was assessed by the microcirculatory response to local ischemia (postocclusive reactive hyperemia) and local hyperthermia (thermal hyperemia). Sera were pooled and passed through affinity columns to separate advanced glycation end product-rich fractions, which were incubated with human aortic endothelial cells, with or without blockade of receptor for advanced glycation end product, to measure their effect on endothelial nitric oxide synthase. RESULTS Glomerular filtration rate correlated with serum advanced glycation end product, mRNA receptor for advanced glycation end product levels, postocclusive reactive hyperemia, and thermal hyperemia. Serum advanced glycation end product correlated with receptor for advanced glycation end product and inversely with postocclusive reactive hyperemia. Advanced glycation end product-rich fractions from chronic kidney disease sera suppressed endothelial nitric oxide synthase expression of human aortic endothelial cells compared with sera from healthy subjects, an effect abrogated by receptor for advanced glycation end product blockade. CONCLUSIONS This study demonstrates for the first time an association of excess advanced glycation end product burden with increased peripheral blood mononuclear cell mRNA receptor for advanced glycation end product and in vivo endothelial dysfunction in patients with chronic kidney disease. Endothelial dysfunction in chronic kidney disease may be partly mediated by advanced glycation end product-induced inhibition of endothelial nitric oxide synthase through receptor for advanced glycation end product activation.

The 3-year renal safety of a tenofovir disoproxil fumarate vs. a thymidine analogue-containing regimen in antiretroviral-naive patients.

Background:Cases of renal dysfunction in patients receiving tenofovir disoproxil fumarate (TDF) have been reported. We analyzed the renal safety of TDF compared with thymidine analogue-containing (control) regimens through 144 weeks from two clinical trials in antiretroviral-naive HIV-infected patients. Methods:We evaluated the changes in renal parameters in 1111 patients (TDF, n = 556; control, n = 555) who were enrolled in two randomized, controlled trials (Studies 903 and 934) comparing TDF vs. either stavudine or zidovudine in combination with efavirenz and either lamivudine or emtricitabine. The studies included patients with serum creatinine less than 1.5 mg/dl, serum phosphorus at least 2.2 mg/dl and estimated glomerular filtration rate by Cockcroft–Gault at least 60 and at least 50 ml/min at screening. Results:Baseline characteristics were similar between groups. No patient discontinued due to renal abnormalities in the TDF arm. Through 144 weeks, the proportion of patients who experienced confirmed abnormalities in serum creatinine (>1.5 mg/dl) or serum phosphorus (<2.0 mg/dl) was less than 1% in both groups; a similar proportion of patients experienced urine proteinuria at least 100 mg/dl (TDF, 5%; control, 6%). The median change from baseline to week 144 in glomerular filtration rate was −2 and 3 ml/min by Cockcroft–Gault, and −2 and −1 ml/min per 1.73 m2 by modification of diet in renal disease in the TDF and control groups (P < 0.05), respectively. Conclusion:In two randomized, controlled trials, small differences in glomerular filtration rate over time were noted but no clinically relevant renal disease or adverse events were demonstrated in antiretroviral-naive patients treated with TDF through 144 weeks. Additional studies on renal health and renal safety in HIV are important goals for future clinical trials.

Overweight, Obesity, and Elevated Serum Cystatin C Levels in Adults in the United States

BACKGROUND Although high body mass index (BMI) is a risk factor for hypertension, diabetes, and cardiovascular disease, limited data exist on the association of overweight and obesity with early stages of kidney disease. METHODS Cross-sectional data for 5083 participants of the nationally representative Third National Health and Nutrition Examination Survey with an estimated glomerular filtration rate > or = 60 mL/min/1.73 m(2) without micro- or macroalbuminuria were analyzed to determine the association between BMI and elevated serum cystatin C. Normal weight, overweight, class I obesity, and class II to III obesity were defined as a BMI of 18.5 to 24.9 kg/m(2), 25.0 to 29.9 kg/m(2), 30.0 to 34.9 kg/m(2), and > or = 35.0 kg/m(2), respectively. Elevated serum cystatin C was defined as > or = 1.09 mg/L (> or = 99th percentile for participants 20-39 years of age without diabetes, hypertension, micro- or macroalbuminuria, or stage 3-5 chronic kidney disease). RESULTS The age-standardized prevalence of elevated serum cystatin C was 9.6%, 12.9%, 17.4%, and 21.5% among adults of normal weight, overweight, class I obesity, and class II to III obesity, respectively (P trend < .001). After multivariate adjustment for demographics, behaviors, systolic blood pressure, and serum biomarkers, and compared with participants of normal weight, the odds ratio (95% confidence interval) of elevated serum cystatin C was 1.46 (1.02-2.10) for overweight, 2.36 (1.56-3.57) for class I obesity, and 2.82 (1.56-5.11) for class II to III obesity. CONCLUSION A graded association exists between higher BMI and elevated serum cystatin C. Further research is warranted to assess whether reducing BMI favorably affects elevated serum cystatin C and the development of chronic kidney disease.

APOL1 Variants Increase Risk for FSGS and HIVAN but Not IgA Nephropathy

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

Kidney Disease in Patients with HIV Infection and AIDS

As patients infected with human immunodeficiency virus (HIV) live longer while receiving antiretroviral therapy, kidney diseases have emerged as significant causes of morbidity and mortality. Black race, older age, hypertension, diabetes, low CD4(+) cell count, and high viral load remain important risk factors for kidney disease in this population. Chronic kidney disease should be diagnosed in its early stages through routine screening and careful attention to changes in glomerular filtration rate or creatinine clearance. Hypertension and diabetes must be aggressively treated. Antiretroviral regimens themselves have been implicated in acute or chronic kidney disease. The risk of kidney disease associated with the widely used agent tenofovir continues to be studied, although its incidence in reported clinical trials and observational studies remains quite low. Future studies about the relationship between black race and kidney disease, as well as strategies for early detection and intervention of kidney disease, hold promise for meaningful reductions in morbidity and mortality associated with kidney disease.

Medical Risks in Living Kidney Donors: Absence of Proof Is Not Proof of Absence

Living-kidney donation has become increasingly widespread, yet there has been little critical analysis of existing studies of long-term medical outcomes in living donors. This review analyzes issues in study design that affect the quality of the evidence and summarizes possible risk factors in living donors. Virtually all studies of long-term outcomes in donors are retrospective, many with large losses to follow-up, and therefore are subject to selection bias. Most studies have small sample sizes and are underpowered to detect clinically meaningful differences between donors and comparison groups. Many studies compare donors with the general population, but donors are screened to be healthier than the general population and this may not be a valid comparison group. Difficulties in measurement of BP and renal function may underestimate the impact of donation on these outcomes. Several studies have identified possible risk factors for development of hypertension, proteinuria, and ESRD, but potential vulnerability factors in donors have not been well explored and there is a paucity of data on cardiovascular risk factors in donors. Prospective registration of living kidney donors and prospective studies of diverse populations of donors are essential to protect living donors and preserve living-kidney donation.