The invasion of circulating monocytes/macrophages (MΦ)s from the peripheral blood into the central nervous system (CNS) appears to play an important role in the pathogenesis of HIV dementia (HIV-D), the most severe form of HIV-associated neurocognitive disorders (HAND), often confirmed histologically as HIV encephalitis (HIVE). In order to determine if trafficking of monocytes/MΦs is exclusive to the CNS or if it also occurs in organs outside of the brain, we have focused our investigation on visceral tissues of patients with HIVE. Liver, lymph node, spleen, and kidney autopsy tissues from the same HIVE cases investigated in earlier studies were examined by immunohistochemistry for the presence of CD14, CD16, CD68, Ki-67, and HIV-1 p24 expression. Here, we report a statistically significant increase in accumulation of MΦs in kidney, spleen, and lymph node tissues in specimens from patients with HIVE. In liver, we did not observe a significant increase in parenchymal macrophage accumulation, although perivascular macrophage accumulation was consistently observed with nodular lesions in 4 of 5 HIVE cases. We also observed an absence of CD14 expression on splenic MΦs in HIVE cases, which may implicate the spleen as a potential source of increased plasma soluble CD14 in HIV infection. HIV-1 p24 expression was observed in liver, lymph node and spleen but not kidney. Interestingly, renal pathology suggestive of chronic tubulointerstitial nephritis (possibly due to chronic pyelonephritis), including tubulointerstitial scarring, chronic interstitial inflammation and focal global glomerulosclerosis, without evidence of HIV-associated nephropathy (HIVAN), was seen in four of eight HIVE cases. Focal segmental and global glomerulosclerosis with tubular dilatation and prominent interstitial inflammation, consistent with HIVAN, was observed in two of the eight cases. Abundant cells expressing monocyte/MΦ cell surface markers, CD14 and CD68, were also CD16+ and found surrounding dilated tubules and adjacent to areas of glomerulosclerosis. The finding of co-morbid HIVE and renal pathology characterized by prominent interstitial inflammation may suggest a common mechanism involving the invasion of activated monocytes/MΦs from circulation. Monocyte/MΦ invasion of visceral tissues may play an important role in the immune dysfunction as well as comorbidity in AIDS and may, therefore, provide a high value target for the design of therapeutic strategies.
HIV; CNS; CD16; pyelonephritis; macrophage; HIVAN; co-morbidity
Approximately 15% of HIV-infected individuals have comorbid diabetes. Studies suggest that HIV and diabetes have an additive effect on chronic kidney (CKD) progression; however, this observation may be confounded by differences in traditional CKD risk factors.
We studied a national cohort of HIV-infected and matched HIV-uninfected individuals who received care through the Veterans Healthcare Administration. Subjects were divided into four groups based on baseline HIV and diabetes status, and the rate of progression to an estimated glomerular filtration rate (eGFR) < 45ml/min/1.73m2 was compared using Cox-proportional hazards modeling to adjust for CKD risk factors.
31,072 veterans with baseline eGFR ≥ 45ml/min/1.73m2 (10,626 with HIV only, 5,088 with diabetes only, and 1,796 with both) were followed for a median of 5 years. Mean baseline eGFR was 94ml/min/1.73m2, and 7% progressed to an eGFR < 45ml/min/1.73m2. Compared to those without HIV or diabetes, the relative rate of progression was increased in individuals with diabetes only [adjusted hazard ratio (HR) 2.48; 95% confidence interval (CI) 2.19–2.80], HIV only [HR 2.80, 95% CI 2.50–3.15], and both HIV and diabetes [HR 4.47, 95% CI 3.87–5.17].
Compared to patients with only HIV or diabetes, patients with both diagnoses are at significantly increased risk of progressive CKD even after adjusting for traditional CKD risk factors. Future studies should evaluate the relative contribution of complex comorbidities and accompanying polypharmacy to the risk of CKD in HIV-infected individuals, and prospectively investigate the use of cART, glycemic control, and adjunctive therapy to delay CKD progression.
non-AIDS complications; HIV; chronic kidney disease; diabetes; risk factors
HIV-related kidney disease has been associated with significant morbidity and mortality in the HIV population. It is clear that the epidemiology of HIV-related kidney disease has changed dramatically since the first case reports in 1984. During these early years, the predominant etiology of kidney disease in HIV was recognized as HIV-associated nephropathy (HIVAN), an aggressive form of kidney disease with a high rate of progression to end-stage renal disease (ESRD). Subsequently, with the widespread use of combination antiretroviral therapy (cART), there was a dramatic decrease in the incidence of ESRD attributed to HIV/AIDS. Although the incidence of HIV-related ESRD has plateaued in the last 15 years, the prevalence has continued to increase because of improved survival. Available prevalence estimates do not include HIV-infected individuals with comorbid ESRD, although there is growing evidence that the epidemiology of kidney disease in the HIV-infected population has changed. This article reviews the impact of risk factors such as race, diabetes mellitus, hypertension, hepatitis C virus coinfection, and the chronic use of cART on the changing epidemiology of HIV-related kidney disease. Additionally in this review, we propose potential areas of translational research that will help to further characterize HIV-related kidney disease in the 21st century.
HIV; AIDS; HCV
Current HIV treatment guidelines recommend using the Cockcroft-Gault equation for drug dosing adjustments. The use of newer glomerular filtration rate (GFR) estimating equations for drug dosing and the appropriateness of physician antiretroviral dosing based on estimated kidney function have not been studied in an HIV-positive population.
We evaluated concordance between measured and estimated GFR for the assignment of kidney function categories designated by the Food and Drug Administration (FDA) Guidance for Industry for pharmacokinetic studies, and appropriateness of physician antiretroviral drug dosing for level of kidney function in 200 HIV-positive patients on stable antiretroviral therapy. Estimated kidney function was determined using the Chronic Kidney Disease-Epidemiology collaboration (CKD-EPI), Modification of Diet in Renal Disease (MDRD) Study and Cockcroft-Gault equations.
For assignment of FDA-designated kidney function categories, concordance rates between measured and estimated GFR using the CKD-EPI, MDRD Study and Cockcroft-Gault equations were 79%, 71% and 77%, respectively. This pattern was consistent across most subgroups. When actual prescribed dosages were compared to recommended dosages based on the level of estimated kidney function, 3% to 19% of study participants were prescribed higher than recommended dosages. The largest discordance between prescribed and recommended dosages was observed for the Cockcroft-Gault equation.
The CKD-EPI equation has the highest concordance with measured GFR for the assignment of FDA-designated kidney function categories. Its use may lead to lower dosing related errors in HIV-infected US adults on stable antiretroviral therapy. More education is required with respect to dose adjustment for level of kidney function.
We previously reported an increased risk of all-cause and AIDS mortality among HIV-infected women with albuminuria (proteinuria or microalbuminuria) enrolled in the Women’s Interagency HIV Study (WIHS) prior to the introduction of highly active antiretroviral therapy (HAART).
The current analysis includes 1,073 WIHS participants who subsequently initiated HAART. Urinalysis for proteinuria and semi-quantitative testing for microalbuminuria from two consecutive study visits prior to HAART initiation were categorized as follows: confirmed proteinuria (both specimens positive for protein), confirmed microalbuminuria (both specimens positive with at least one microalbuminuria), unconfirmed albuminuria (one specimen positive for proteinuria or microalbuminuria), or negative (both specimens negative). Time from HAART initiation to death was modeled using proportional hazards analysis.
Compared to the reference group of women with two negative specimens, the hazard ratio (HR) for all-cause mortality was significantly elevated for women with confirmed microalbuminuria (HR 1.9; 95% CI 1.2–2.9). Confirmed microalbuminuria was also independently associated with AIDS death (HR 2.3; 95% CI 1.3–4.3), while women with confirmed proteinuria were at increased risk for non-AIDS death (HR 2.4; 95% CI 1.2–4.6).
In women initiating HAART, pre-existing microalbuminuria independently predicted increased AIDS mortality, while pre-existing proteinuria predicted increased risk of non-AIDS death. Urine testing may identify HIV-infected individuals at increased risk for mortality even after the initiation of HAART. Future studies should consider whether these widely available tests can identify individuals who would benefit from more aggressive management of HIV infection and comorbid conditions associated with mortality in this population.
HIV; microalbuminuria; proteinuria; mortality; non-AIDS death
Acute kidney injury is common in HIV-infected patients, and has been associated with increased morbidity and mortality. Prior to the introduction of effective antiretroviral therapy, acute kidney injury in HIV-positive patients was most commonly the result of volume depletion, septicemia, or nephrotoxic medications. Acute kidney injury remains a significant problem in the antiretroviral era, and is still commonly attributed to infection or nephrotoxic medications. Less common causes such as direct infectious insults, immune restoration inflammatory syndrome, rhabdomyolysis, and obstruction should be considered when the underlying process is not obvious. In addition to advanced HIV disease, several other patient characteristics have emerged as potential risk factors for acute kidney injury in the antiretroviral era, including older age, diabetes, pre-existing chronic kidney disease, and hepatitis co-infection or liver disease.
Acute kidney injury; acute tubular necrosis; HIV
The classic kidney disease of Human Immunodeficiency Virus (HIV) infection, HIV-associated nephropathy, is characterized by progressive acute renal failure, often accompanied by proteinuria and ultrasound findings of enlarged, echogenic kidneys. Definitive diagnosis requires kidney biopsy, which demonstrates collapsing focal segmental glomerulosclerosis with associated microcystic tubular dilatation and interstitial inflammation. Podocyte proliferation is a hallmark of HIV-associated nephropathy, although this classic pathology is observed less frequently in antiretroviral-treated patients. The pathogenesis of HIV-associated nephropathy involves direct HIV infection of renal epithelial cells, and the widespread introduction of combination antiretroviral therapy has had a significant impact on the natural history and epidemiology of this unique disease. These observations have established antiretroviral therapy as the cornerstone of treatment for HIV-associated nephropathy, in the absence of prospective clinical trials. Adjunctive therapy for HIV-associated nephropathy includes ACE inhibitors or angiotensin receptor blockers, as well as corticosteroids in selected patients with significant interstitial inflammation or rapid progression.
HIV-associated nephropathy; focal segmental glomerulosclerosis; HIV; kidney
With prolonged survival and aging of the HIV-infected population in the era of antiretroviral therapy, biopsy series have found a broad spectrum of HIV-related and co-morbid kidney disease in these patients. Our study describes the variety of renal pathology found in a prospective cohort of antiretroviral-experienced patients (the Manhattan HIV Brain Bank) who had consented to postmortem organ donation. Nearly one-third of 89 kidney tissue donors had chronic kidney disease, and evidence of some renal pathology was found in 75. The most common diagnoses were arterionephrosclerosis, HIV-associated nephropathy and glomerulonephritis. Other diagnoses included pyelonephritis, interstitial nephritis, diabetic nephropathy, fungal infection and amyloidosis. Excluding 2 instances of acute tubular necrosis, slightly over one-third of the cases would have been predicted using current diagnostic criteria for chronic kidney disease. Based on semi-quantitative analysis of stored specimens, pre-mortem microalbuminuria testing could have identified an additional 12 cases. Future studies are needed to evaluate the cost-effectiveness of more sensitive methods for defining chronic kidney disease, in order to identify HIV-infected patients with early kidney disease who may benefit from antiretroviral therapy and other interventions known to delay disease progression and prevent complications.
AIDS; histopathology; HIV-associated nephropathy; kidney disease
Proteinuria is associated with adverse clinical outcomes in HIV infection. Here we evaluated whether APOL1 risk alleles, previously associated with advanced kidney disease, is independently associated with proteinuria in HIV infection in a cross-sectional study of HIV-infected women in the Women’s Interagency HIV Study. We estimated the percent difference in urine protein excretion and odds of proteinuria (200 mg/g and higher) associated with two versus one or no APOL1 risk allele using linear and logistic regression, respectively. Of 1285 women successfully genotyped, 379 carried one and 80 carried two risk alleles. Proteinuria was present in 124 women; 78 of whom had proteinuria confirmed on a second sample. In women without prior AIDS, two risk alleles were independently associated with a 69% higher urine protein excretion (95% CI: 36%, 108%) and 5-fold higher odds of proteinuria (95% CI: 2.45, 10.37) versus one or no risk allele. No association was found in women with prior AIDS. Analyses in which women with impaired kidney function were excluded and proteinuria was confirmed by a second urine sample yielded similar estimates. Thus, APOL1 risk alleles are associated with significant proteinuria in HIV-infected persons without prior clinical AIDS, independent of clinical factors traditionally associated with proteinuria. Trials are needed to determine whether APOL1 genotyping identifies individuals who could benefit from earlier intervention to prevent overt renal disease.
The predictors of Fanconi syndrome (FS) accompanied by renal function decline with use of the antiretroviral tenofovir disoproxil fumarate (TDF) have not been assessed. In addition, the natural history of renal recovery from FS after TDF discontinuation is not well-described.
We prospectively enrolled HIV-infected patients receiving TDF with newly identified FS (defined as at least two markers of proximal tubulopathy and either a >25% decline in creatinine clearance (CrCl) from pre-TDF values or a CrCl <60 mL/min in those without a known pre-TDF CrCl) in a multicenter observational study. These case participants were matched 1∶2 to controls; characteristics between the two groups were compared. Case participants with known pre-TDF CrCl values were then followed over 48 weeks to assess renal recovery.
Nineteen cases and 37 controls were enrolled. In multivariable analysis, previous or concurrent use of lopinavir/ritonavir [OR 16.37, 95% CI (2.28, 117.68); P = 0.006] and reduced creatinine clearance prior to initiation of TDF [OR 1.44 for every 5 mL/min reduction, 95% CI (1.09, 1.92); P = 0.012; OR 19.77 for pre-TDF CrCl lower than 83 mL/min, 95% CI (2.24, 174.67); P = 0.007] were significantly associated with FS. Of the 14 cases followed for resolution, 7 (50%) achieved at least partial resolution (defined as recovering CrCl >70% of pre-TDF values) although most participants had full normalization of proximal tubulopathy markers within two months of TDF discontinuation.
FS, defined by specific CrCl decreases and markers of tubulopathy, is more likely in those who have received or are currently receiving concomitant lopinavir/ritonavir or who had lower CrCl prior to TDF initiation. Half of those with protocol-defined FS had CrCl recover to near pre-TDF values during the first year after TDF discontinuation.
More than two-thirds of the world's HIV-positive individuals live in sub-Saharan Africa, where genetic susceptibility to kidney disease is high and resources for kidney disease screening and antiretroviral therapy (ART) toxicity monitoring are limited. Equations to estimate glomerular filtration rate (GFR) from serum creatinine were derived in Western populations and may be less accurate in this population.
We compared results from published GFR estimating equations with a direct measure of GFR by iohexol clearance in 99 HIV-infected, ART-naïve Kenyan adults. Iohexol concentration was measured from dried blood spots on filter paper. The bias ratio (mean of the ratio of estimated to measured GFR) and accuracy (percentage of estimates within 30% of the measured GFR) were calculated.
The median age was 35 years, and 60% were women. The majority had asymptomatic HIV, with median CD4+ cell count of 355 cells/mm3. Median measured GFR was 115 mL/min/1.73 m2. Overall accuracy was highest for the Chronic Kidney Disease Epidemiology Consortium (CKD-EPI) equation. Consistent with a prior report, bias and accuracy were improved by eliminating the coefficient for black race (85% of estimates within 30% of measured GFR). Accuracy of all equations was poor in participants with GFR 60–90 mL/min/1.73 m2 (<65% of estimates within 30% of measured GFR), although this subgroup was too small to reach definitive conclusions.
Overall accuracy was highest for the CKD-EPI equation. Eliminating the coefficient for race further improved performance. Future studies are needed to determine the most accurate GFR estimate for use in individuals with GFR <90 mL/min/1.73 m2, in whom accurate estimation of kidney function is important to guide drug dosing. Direct measurement of GFR by iohexol clearance using a filter paper based assay is feasible for research purposes in resource-limited settings, and could be used to develop more accurate GFR estimates in African populations.
Chronic kidney disease (CKD) is an important cause of morbidity and mortality in HIV-positive individuals. Hepatitis C (HCV) co-infection has been associated with increased risk of CKD, but prior studies lack information on potential mechanisms. We evaluated the association between HCV or hepatitis B (HBV) co-infection and progressive CKD among 3,441 antiretroviral-treated clinical trial participants. Progressive CKD was defined as the composite of end-stage renal disease, renal death, or significant glomerular filtration rate (eGFR) decline (25% decline to eGFR <60 mL/min/1.73 m2 or 25% decline with a baseline <60). Generalized Estimating Equations were used to model the odds of progressive CKD. At baseline, 13.8% and 3.3% of participants were co-infected with HCV and HBV, respectively. Median eGFR was 111, and 3.7% developed progressive CKD. After adjustment, the odds of progressive CKD were increased in participants with HCV (OR 1.72, 95% CI 1.07–2.76) or HBV (OR 2.26, 95% CI 1.15–4.44). Participants with undetectable or low HCV-RNA had similar odds of progressive CKD as HCV seronegative participants, while participants with HCV-RNA >800,000 IU/ml had increased odds (OR 3.07; 95% CI 1.60–5.90). Interleukin-6, hyaluronic acid, and the FIB-4 hepatic fibrosis index were higher among participants who developed progressive CKD, but were no longer associated with progressive CKD after adjustment. Future studies should validate the relationship between HCV viremia and CKD.
ClinicalTrials.gov NCT00027352; NCT00004978
Prevalence of microalbuminuria is increased in patients with HIV. Microalbuminuria is associated with increased mortality in other populations, including diabetics, for whom microalbuminuria testing is standard of care. We investigated whether microalbuminuria is associated with mortality in HIV-infected women not receiving antiretroviral therapy.
Urinalysis for proteinuria and semi-quantitative testing for microalbuminuria were performed in specimens from two consecutive visits in 1,547 HIV-infected women enrolled in the Women’s Interagency HIV Study in 1994–1995. Time to death was modeled using proportional hazards analysis.
Compared to women without albuminuria, the hazard ratio (HR) for all-cause mortality was increased in women with one (HR 3.4; 95% CI 2.2–5.2) or two specimens positive for either proteinuria or microalbuminuria (HR 3.9; 95% CI 2.1–7.0). The highest risk was observed in women with both specimens positive for proteinuria (HR 5.8; 95% CI 3.4–9.8). The association between albuminuria and all-cause mortality risk remained significant after adjustment for demographics, HIV disease severity, and related comorbidities. Similar results were obtained for AIDS death.
We identified a graded relationship between albuminuria and the risk of all-cause and AIDS mortality.
HIV; microalbuminuria; proteinuria; mortality
Parathyroid hormone (PTH) elevations are associated with reduced bone mineral density and adverse health outcomes and have been reported in patients with HIV infection. We aimed to examine the impact of vitamin D status and tenofovir (TDF) use on PTH levels among HIV-infected patients receiving combination antiretroviral therapy (cART). Demographics, medication and supplement use, and clinical data, including 25-hydroxyvitamin D [25(OH)D] and PTH, were collected on 45 HIV-infected men on ART. Suboptimal vitamin D status was defined as 25(OH)D < 30 ng/ml. The relationship between antiretroviral agents, suboptimal 25(OH)D, and PTH levels was examined. Among subjects with suboptimal vitamin D status, PTH values greater than or equal to the ULN (87 pg/ml) were more common among TDF users than nonusers: 41% versus 0% (p = 0.018); and median PTH was higher in TDF users: 80 pg/ml versus 55 pg/ml (p = 0.02). Among TDF users, PTH was higher in the group with suboptimal 25(OH)D (p = 0.045). Multivariable linear regression showed that PTH was independently and directly related to TDF use (p = 0.017) and inversely related to 25(OH)D (p = 0.017). PTH was not related to the estimated glomerular filtration rate (p = 0.9). In this cross-sectional study of HIV-infected men on ART, the use of TDF and the level of 25(OH)D were independently associated with PTH levels. Because TDF is a potent and widely used antiretroviral drug, information about cofactors that may exacerbate its side effects is of significant clinical value.
In the United States, HIV-related kidney disease disproportionately affects individuals of African descent; however, there are few estimates of kidney disease prevalence in Africa. We evaluated the prevalence of kidney disease among HIV-infected and uninfected Rwandan women.
The Rwandan Women's Interassociation Study and Assessment prospectively enrolled 936 women. Associations with estimated glomerular filtration rate (eGFR)<60 mL/min/1.73 m2 and proteinuria were assessed in separate logistic regression models.
Among 891 non-pregnant women with available data, 2.4% had an eGFR<60 mL/min/1.73 m2 (calculated by the Modification of Diet in Renal Disease equation, MDRD eGFR) and 8.7% had proteinuria ≥1+. The prevalence of decreased eGFR varied markedly depending on the estimating method used, with the highest prevalence by Cockcroft-Gault. Regardless of the method used to estimate GFR, the proportion with decreased eGFR or proteinuria did not differ significantly between HIV-infected and -uninfected women in unadjusted analysis. After adjusting for age and blood pressure, HIV infection was associated with significantly higher odds of decreased MDRD eGFR but not proteinuria.
In a well-characterized cohort of Rwandan women, HIV infection was associated with decreased MDRD eGFR. The prevalence of decreased eGFR among HIV-infected women in our study was lower than that previously reported in African-Americans and in other Central and East African HIV populations, although there was substantial variability depending on the equation used to estimate GFR. Future studies are needed to optimize GFR estimates and to determine the impact of antiretroviral therapy on kidney disease in this population.
To examine the effect of hepatitis C virus (HCV) on the prevalence of chronic kidney disease (CKD) among veterans with HIV and to evaluate independent associations of HCV and CKD with mortality.
We studied a national cohort of HIV-infected patients receiving care through the Veterans Healthcare Administration from 1998 to 2004. CKD was defined as an estimated glomerular filtration rate [eGFR (mL/min/1.73 m2)] < 60. Poisson regression was used to assess relationships between CKD, HCV, and mortality.
Among 23,155 HIV-infected veterans, 12% had CKD. Forty percent of the cohort was coinfected with HCV, and a higher proportion of coinfected subjects had CKD compared with monoinfected subjects (14% vs 11%, P < 0.001). During the median follow-up of 7.6 years, 37% of subjects died and a graduated increase in adjusted mortality rates occurred with lower levels of eGFR (P < 0.001). Adjusted mortality rates were consistently higher in HCV-coinfected subjects across all levels of eGFR (P < 0.001). HCV was independently associated with increased mortality (incidence rate ratio 1.23, 95% confidence interval 1.17–1.29).
CKD is prevalent in HIV-infected veterans and associated with substantially higher mortality. Compared with their monoinfected counterparts, veterans coinfected with HCV have significantly higher rates of CKD and mortality.
death; HIV; hepatitis C; kidney failure; veterans
In the era of antiretroviral therapy, non-AIDS complications such as kidney disease are important contributors to morbidity and mortality.
To estimate the impact of hepatitis C co-infection on the risk of kidney disease in HIV patients.
Two investigators identified English-language citations in MEDLINE and Web of Science from 1989 through July 1, 2007. References of selected articles were reviewed. Observational studies and clinical trials of HIV-related kidney disease and antiretroviral nephrotoxicity were eligible if they included at least 50 participants and reported hepatitis C status. Data on study characteristics, population, and kidney disease outcomes were abstracted by two independent reviewers.
After screening 2,516 articles, twenty-seven studies were eligible and 24 authors confirmed or provided data. Separate meta-analyses were performed for chronic kidney disease outcomes (n=10), proteinuria (n=4), acute renal failure (n=2), and indinavir toxicity (n=5). The pooled incidence of chronic kidney disease was higher in patients with hepatitis C co-infection (6.2% versus 4.0%; RR 1.49, 95% CI 1.08–2.06). In meta-regression, prevalence of black race and the proportion of patients with documented hepatitis C status were independently associated with the risk of chronic kidney disease. The relative risk associated with hepatitis C co-infection was significantly increased for proteinuria (1.15; 95% CI 1.02–1.30) and acute renal failure (1.64; 95% CI 1.21–2.23), with no significant statistical heterogeneity. The relative risk of indinavir toxicity was 1.59 (95% CI 0.99–2.54) with Hepatitis C co-infection.
Hepatitis C co-infection is associated with a significant increase in the risk of HIV-related kidney disease.