Total protein, albumin and low-molecular-weight protein excretion in HIV-positive patients

Urinary biomarkers in kidney disease

BACKGROUND

Chronic kidney disease (CKD) affects many people worldwide and early diagnosis is essential for successful treatment and improved outcome. Unfortunately, current methods are insufficient especially for early disease detection. However, advances in the analytical methods for urinary biomarkers may provide a unique opportunity for diagnosis and management of CKD. This review explores evolving technology and highlights the importance of early marker detection in these patients.

APPROACH

A search strategy was set up using the terms CKD, biomarkers, and urine. The search included 53 studies comprising 37 biomarkers. The value of these biomarkers for CKD are based on their ability to diagnose CKD, monitor progression, assess mortality and nephrotoxicity.

RESULTS

KIM-1 was the best marker for diagnosis as it increased with the development of incident CKD. DKK3 increased in patients with declining eGFR, whereas UMOD decreased in those with declining kidney function. Unfortunately, none fulfilled all criteria to adequately assess mortality and nephrotoxicity.

CONCLUSION

New developments in the field of urinalysis using smart toilets may open several possibilities for urinary biomarkers. This review explored which biomarkers could be used for CKD disease detection and management.

Pharmacogenetics of tenofovir renal toxicity in HIV-positive Southern Africans

OBJECTIVE

Renal toxicity is more common with tenofovir disoproxil fumarate (TDF) than with tenofovir alafenamide fumarate (TAF). We investigated whether polymorphisms in genes relevant to tenofovir disposition affect renal toxicity among HIV-positive Southern Africans.

METHODS

Genetic sub-study of adults randomized to initiate TAF or TDF together with dolutegravir and emtricitabine was conducted. Outcomes were changes from week 4 to 48 in the estimated glomerular filtration rate (eGFR) and from baseline to week 48 in urine retinol-binding protein and urine β2-microglobulin adjusted for urinary creatinine (uRBP/Cr and uB2M/Cr). Primary analyses prioritized 14 polymorphisms previously reported to be associated with tenofovir disposition or renal outcomes, and all polymorphisms in 14 selected genes. We also explored genome-wide associations.

RESULTS

336 participants were enrolled. Among 14 polymorphisms of primary interest, the lowest P values for change in eGFR, uRBP/Cr, and uB2M/Cr were ABCC4 rs899494 ( P  = 0.022), ABCC10 rs2125739 ( P  = 0.07), and ABCC4 rs1059751 ( P  = 0.0088); and in genes of interest, the lowest P values were ABCC4 rs4148481 ( P  = 0.0013), rs691857 ( P  = 0.00039), and PKD2 rs72659631 ( P  = 0.0011). However, none of these polymorphisms withstood correction for multiple testing. Genome-wide, the lowest P values were COL27A1 rs1687402 ( P  = 3.4 × 10 -9 ), CDH4 rs66494466 ( P  = 5.6 × 10 -8 ), and ITGA4 rs3770126 ( P  = 6.1 × 10 -7 ).

CONCLUSION

Two ABCC4 polymorphisms, rs899494 and rs1059751, were nominally associated with change in eGFR and uB2M/Cr, respectively, albeit in the opposite direction of previous reports. COL27A1 polymorphism was genome-wide significantly associated with change in eGFR.

The renal-bone axis in older people living with HIV on stable antiretroviral therapy: A sub-analysis of the GS-US-104-0423 study

BACKGROUND

Data on low bone mineral density (BMD) in people living with HIV (PLWH) are mainly derived from younger adults; little is known about how antiretroviral therapy (ART) and alterations in the renal-bone axis relate to BMD in older PLWH.

METHODS

Cross-sectional study of men > 50 years and post-menopausal women with HIV. Antiretroviral therapy exposure was stratified into four groups based on use of tenofovir disoproxil fumarate (TDF) and protease inhibitors (PI): non-TDF/non-PI, non-TDF/PI, TDF/non-PI, and TDF/PI. Bone mineral density was measured by dual X-ray absorptiometry (DXA). Bone turnover/regulatory markers and renal tubular function were analysed in stored plasma and urine samples. The association of ART exposure and bone/renal biomarkers on BMD was explored using logistic regression models.

RESULTS

247 individuals (median [IQR] age 57 [53, 65] years; 47% female; 13% of Black ethnicity; CD4 count 643 [473, 811] cells/mm³; and 98% with HIV RNA < 200 copies/mL) were included. Bone turnover and renal tubular function differed significantly by ART exposure. In analyses adjusted for demographic and traditional renal/bone risk factors, exposure to TDF and PI was associated with a fourfold greater risk of low BMD at the femoral neck and exposure to TDF and/or PI with a threefold greater risk of low BMD at the lumbar spine. The relationship between ART and low BMD was not altered by further adjustment for bone turnover or renal tubular function markers.

CONCLUSIONS

The associations between low BMD and ART exposure (TDF vs. non-TDF and boosted vs. unboosted third agents) were minimally affected by adjustments for bone and kidney biomarkers.

Selected biochemical parameters in the urine of HIV-infected patients in monitoring of kidney function

Introduction

For years, there has been an increase in the number of cases of chronic kidney disease (CKD) in human immunodeficiency virus (HIV)-infected patients. Renal dysfunction can be caused by direct effects of HIV on the kidneys but also of applied combined antiretroviral therapy (cART). Therefore there is a need of renal function diagnosis to monitor the development of kidney disturbances. In this study the urinary levels of selected low molecular weight proteins (LMWP) in HIV-infected patients were measured and related to current CD4+ T lymphocyte (LT CD4+) count, the glomerular filtration rate (eGFR) value and the applied cART.

Material and methods

The levels of 5 LMWP - kidney injury molecule-1 (KIM-1), neutrophil gelatinase associated lipocalin (NGAL), glutathione S-transferase α (GST-α) and π (GST-π) isoenzymes and neopterin (NPT) - in urine were measured in HIV-infected patients and healthy controls by enzyme-linked immunosorbent assay.

Results

Taking into account the current LT CD4+ count, KIM-1, NGAL and GST-α showed statistically significant differences between groups with the CD4+ count < 500 and ≥ 500 cells (< 0.001). Depending on the eGFR, apart from KIM-1 and NGAL, NPT showed statistically significant differences in the investigated groups with normal and lower eGFR values (< 0.001). In terms of applied cART, the best parameters in the assessment of kidney damage were NGAL, GST-π and NPT (< 0.001).

Conclusions

This research shows that the analyzed LMWP parameters are useful in the assessment of kidney damage in HIV patients during cART, especially NPT, NGAL and GST-π. However, future studies should be conducted on larger groups.

Prevalence of tubulopathy and association with renal function loss in HIV-infected patients

BACKGROUND

The incidence of chronic kidney disease (CKD) is 10 times higher in human immunodeficiency virus (HIV)-infected patients than in the general population. We explored the prevalence and determinants of proximal tubular dysfunction (PTD) in HIV-infected individuals, and assessed the impact of the tubulopathy on the estimated glomerular filtration rate (eGFR) outcome.

METHODS

A cohort study was performed on 694 outpatients followed in a French centre to analyse the prevalence of PTD, the diagnosis performance of screening tools and the associated factors. eGFR was prospectively evaluated to analyse the predictive value of the tubulopathy on eGFR decrease.

RESULTS

At inclusion, 14% of the patients presented with PTD and 5% with CKD. No individual tubular marker, including non-glomerular proteinuria, glycosuria dipstick or hypophosphataemia, registered sufficient performance to identify PTD. We found a significant interaction between tenofovir disoproxil fumarate exposure and ethnicity (P = 0.03) for tubulopathy risk. Tenofovir disoproxil fumarate exposure was associated with PTD in non-Africans [adjusted odds ratio (aOR) = 4.71, P < 10-3], but not in patients of sub-Saharan African origin (aOR = 1.17, P = 0.73). Among the 601 patients followed during a median of 4.3 years, 13% experienced an accelerated eGFR decline. Unlike microalbuminuria and glomerular proteinuria, tubulopathy was not associated with accelerated eGFR decline.

CONCLUSION

PTD is not rare in HIV-infected individuals but is less frequent in sub-Saharan African patients and is associated with tenofovir disoproxil fumarate exposure only in non-Africans. Its diagnosis requires multiple biochemical testing and it is not associated with an accelerated eGFR decline.

Bone mineral density, kidney function, weight gain and insulin resistance in women who switch from TDF/FTC/NNRTI to ABC/3TC/DTG

OBJECTIVES

Tenofovir disoproxil fumarate (TDF) is associated with reduced bone mineral density (BMD). We evaluated changes in BMD in women who switched from TDF, emtricitabine and a nonnucleoside reverse transcriptase inhibitor (TDF/FTC/NNRTI) to abacavir, lamivudine and dolutegravir (ABC/3TC/DTG).

METHODS

We conducted a randomized controlled trial in which women aged ≥40 years were randomized 1:2 to continue TDF/FTC/NNRTI or switch to ABC/3TC/DTG. The primary endpoint was change in total hip BMD measured by dual-energy X-ray absorptiometry at week 48. Secondary endpoints were changes in BMD of the lumbar spine and femoral neck and markers of bone turnover and kidney function up to week 48. We conducted exploratory analyses of weight gain, insulin resistance and metabolic syndrome. Primary and secondary endpoints were analysed by linear regression, with multiple imputation for missing time points.

RESULTS

In all, 91 women [mean age = 50.4 (standard deviation [SD] = 6.6) years, median CD4 cell count = 600 (interquartile range: 479-800) cells/µL] were randomized. Women who switched to ABC/3TC/DTG maintained viral suppression and experienced improvements in total hip BMD (mean adjusted difference = 1%, P = 0.027) and lumbar spine BMD (3%, P = 0.002), with no change in specific markers of bone turnover or renal tubular function. Although participants in the ABC/3TC/DTG arm gained more weight (1.8 kg, P = 0.046), the switch strategy was not associated with reduced insulin sensitivity or new-onset metabolic syndrome.

CONCLUSIONS

Switching from TDF/FTC/NNRTI to ABC/3TC/DTG resulted in improved BMD. Although weight gain was common in women who switched from TDF/FTC/NNRTI to ABC/3TC/DTG, we did not detect adverse effects on glucose homeostasis. Larger studies need to confirm these findings.

The utility of kidney injury molecule-1 as an early biomarker of kidney injury in people living with HIV

There are increasing reports of antiretroviral therapy (ART) drug-related kidney dysfunction. Traditional markers of kidney dysfunction such as urine protein/creatinine ratio and estimated glomerular filtration rate (eGFR) have thus far proven ineffective at detecting some sub-clinical forms of ART-related kidney injury. This is a cross-sectional examination of 114 people living with HIV (PLWH), either naïve (N =104) or treatment experienced (N =10). Urinary kidney injury molecule-1 (KIM-1 ng/mg) thresholds were estimated using electrochemiluminescent assays from stored urine samples and normalised for urinary creatinine excretion (KIM-1/Cr). Correlation coefficients and predictors of kidney tubular injury were compared and derived for both adjusted and unadjusted urinary KIM-1/CR (ng/mg). In PLWH (both ART-naïve and treatment experienced) had a higher baseline unadjusted and adjusted median (≥3.7 ng/mg) and upper tertile (≥6.25 ng/mg) urinary KIM-1/Cr levels compared to either non-normal volunteers (0.39 ng/mg) or those with acute kidney injury in the general population (0.57 ng/mg). When upper tertile KIM-1/Cr (≥6.25 ng/mg) was utilised as a marker of kidney injury, eGFR (ml/min/1.73 m²), white Caucasian ethnicity, and protease inhibitor exposure were significantly associated with increased risk of kidney injury in multivariate analyses (odds ratio 0.91, confidence interval [CI] 0.68–0.98, P = 0.02; odds ratio 8.9, CI 1.6–48.6, p = 0.01; and odds ratio 0.05, CI 0.03–0.9, p =0.04, respectively). We found a significant degree of sub-clinical kidney injury (high unadjusted and adjusted KIM-1/Cr) in PLWH with normal kidney function (eGFR ≥60 ml/min/1.73 m²). We also found a higher baseline KIM-1/Cr (ng/mg) in our study cohort than reported both in normal volunteers and patients with kidney injury in the general population.

Alternative Strategy To Explore Missing Proteins with Low Molecular Weight

Identifying more missing proteins (MPs) is an important mission of C-HPP. With the number of identified MPs being attenuated year by year (2,949 to 2,129 MPs from 2016 to 2019), we have realized that the difficulty of exploring the remaining MPs is a challenge in technique. Herein, we propose a comprehensive strategy to effectively enrich, separate, and identify proteins with low molecular weights, aiming at the discovery of MPs. Basically, a protein extract from human placenta was passed through a C18 SPE column, and the bound proteins that were eluted were further separated with an SDS-PAGE gel or a 50 kDa cutoff filter. The separated proteins were subjected to trypsin digestion, and the MS/MS signals were searched against data sets with two different digestion modes (full-trypsin and semitrypsin). The strategy was adopted, resulting in the identification of 4 MPs with 8 unique peptides (≥2 non-nested unique peptides with ≥9 amino acids). Importantly, the identification of 6 out of 8 of the unique peptides derived from the MPs was further supported by parallel reaction monitoring, which confirmed the identification of 3 MPs from human placenta tissues (Q6NT89: TMF-regulated nuclear protein 1; A0A183: late cornified envelope protein 6A; and Q6UWQ7: insulin growth factor-like family member 2, mapped to chromosomes 1, 1, and 19, respectively). The three proteins ranged in length from 80 aa to 227 aa. The study not only establishes a feasible strategy for analyzing proteins with low molecular weights but also fills a small part of a large gap in the list of MPs. The data obtained in this study are available via ProteomeXchange (PXD014083) and PeptideAtlas (PASS01389).

Prevalence of Nephrotoxicity in HIV Patients Treated with Tenofovir Disoproxil Fumarate: A Single-center Observational Study

Objectives

Tenofovir disoproxil fumarate (TDF) has been reported to cause nephrotoxicity necessitating cessation in some patients. No information is available on the nephrotoxic effect of TDF in Omani or regional patients with HIV infection. We sought to determine the prevalence of the nephrotoxic effects of TDF in our cohort of Omani patients with HIV and investigate the nephrotoxic effects of other cofactors.

Methods

We conducted an observational cohort study on 83 Omani patients currently on TDF-containing antiretroviral therapy. Renal dysfunction was monitored by measuring the serum creatinine estimated glomerular function rate (eGFR), urinary protein creatinine ratio (uPCR), and fractional excretion of phosphate (FEPi). Fisher's exact test was used to determine any additional nephrotoxic effects of cofactors.

Results

The median values for the duration of TDF use, patient age, and body mass index (BMI) at the time of the study were 178 weeks (range = 3-554), 42 years (range = 21-80), and 27 (range = 17.4-42.7), respectively. The median initial CD4 count and viral load were 205 × 10⁶/L (range = 3-1745) and 37 250 copies/mL (range = undetectable-9 523 428), respectively. FEPi was high in two (2.4%) patients, moderate in 26 (31.3%), and low in 55 (66.3%) patients. uPCR was high in 10 (12.0%) patients, moderate in 28 (33.7%), and low in 45 (54.2%) patients. No cofactors added to the nephrotoxicity except hypertension (p = 0.045).

Conclusions

Better definitions for TDF-associated toxicity are needed. uPCR is not a very good indicator of TDF-associated tubular dysfunction. Omani patients with HIV on TDF have a 4% prevalence of renal toxicity, but a study with a larger number of patients is required to explore this observation further. Cofactors like duration of TDF use, age, BMI, gender, diabetes mellitus, and use of protease inhibitors did not have an impact on the severity of FEPi and uPCR.

Serum NGAL can act as an early renal safety biomarker during long-term nucleos(t)ide analogue antiviral therapy in chronic hepatitis B

Tubular renal toxicity is a side-effect of long-term therapy with nucleos(t)ide analogue(s) (NA) in chronic hepatitis B (CHB). There are no established surrogate markers in plasma of early NA-related toxicity. Neutrophil gelatinase-associated lipocalin (NGAL) is a protein produced by tubular cells following renal damage. We aimed therefore to retrospectively compare conventional renal markers (estimated glomerular filtration rates (eGFR) and urinary protein/creatinine ratio uPCR) with a sensitive biomarker (NGAL) in CHB patients on long-term NA therapy and assess the ability of new markers to predict NA-related renal toxicity (new onset of nonalbumin proteinuria). A total of 192 naïve CHB patients (median age 41 years, 78% males, 25% HBeAg+, 35% cirrhosis) were NA treated for at least 5 years (median 8.34 years, range 5.54-11.1 years). The eGFR and uPCR were compared at baseline and last clinical visit with serum NGAL concentrations measured by ELISA at same time-points and assessed according to the presence/absence of nonalbumin proteinuria at last visit. While baseline and last visit eGFR were similar (median:78 vs 84 mL/min), serum NGAL concentrations increased during therapy (median:9.4 vs 16.4 ng/mL, P < .05). The proportion of patients with proteinuria (uPCR > 15) increased between baseline and last visit (4.6% vs 21.4%, P < .05), with 30 (16%) patients having de novo nonalbumin proteinuria at last visit. High baseline NGAL concentrations were exclusive to patients with de novo nonalbumin proteinuria (median:31.7 vs 7.8 ng/mL, P < .01) and baseline NGAL levels >25 mg/mL were predictive of nonalbumin proteinuria at last visit (AUROC = 0.813). In conclusion, serum NGAL can act as a surrogate marker of early renal injury (de novo nonalbumin proteinuria) in CHB on long-term NA therapy.

The Spectrum of Kidney Diseases in Children Associated with Low Molecular Weight Proteinuria

BACKGROUND

Proteinuria, in addition to haematuria, is the most important laboratory parameter in patients with nephro-urological diseases. Low molecular weight proteinuria (LMWP) is of particular importance because some diseases genetic and tubulointerstitial are diagnosed based on its presence.

AIM

The purpose of this study is to describe the clinical features, the course and outcome of pediatric patients with a renal disease associated with LMWP.

MATERIAL AND METHODS

This retrospective observational study included 250 pediatric patients with various kidney diseases in which the type of proteinuria was defined by 4-20% gradient gel sodium dodecyl sulphate polyacrylamide gel (SDS-PAG) electrophoresis.

RESULTS

Isolated LMWP was detected in 12% of patients, while mixed glomerulotubular proteinuria was detected in 18% of patients. It was detected in all patients with the Dent-1/2 disease, Lowe's syndrome and secondary Fanconi syndrome. Transient LMWP was also detected in a series of 12 patients with distal renal tubular acidosis. In patients with nephrotic syndrome, it was associated with corticoresistence and unfavourable clinical course.

CONCLUSION

This study contributes to the understanding of the clinical spectrum of various kidney diseases associated with LMWP, their natural course, and the effect of therapy.

Renal health after long-term exposure to tenofovir disoproxil fumarate (TDF) in HIV/HBV positive adults in Ghana

OBJECTIVES

The study assessed markers of renal health in HIV/HBV co-infected patients receiving TDF-containing antiretroviral therapy in Ghana.

METHODS

Urinary protein-to-creatinine ratio (uPCR) and albumin-to-protein ratio (uAPR) were measured cross-sectionally after a median of four years of TDF. At this time, alongside extensive laboratory testing, patients underwent evaluation of liver stiffness and blood pressure. The estimated glomerular filtration rate (eGFR) was measured longitudinally before and during TDF therapy.

RESULTS

Among 101 participants (66% women, median age 44 years, median CD4 count 572 cells/mm³) 21% and 17% had detectable HIV-1 RNA and HBV DNA, respectively. Overall 35% showed hypertension, 6% diabetes, 7% liver stiffness indicative of cirrhosis, and 18% urinary excretion of Schistosoma antigen. Tubular proteinuria occurred in 16% of patients and was independently predicted by female gender and hypertension. The eGFR declined by median 1.8 ml/min/year during TDF exposure (IQR -4.4, -0.0); more pronounced declines (≥ 5 ml/min/year) occurred in 22% of patients and were associated with receiving ritonavir-boosted lopinavir rather than efavirenz. HBV DNA, HBeAg, transaminases, and liver stiffness were not predictive of renal function abnormalities.

CONCLUSIONS

The findings mandate improved diagnosis and management of hypertension and suggest targeted laboratory monitoring of patients receiving TDF alongside a booster in sub-Saharan Africa.

Predictive factors and prevalence of microalbuminuria in HIV-infected patients: a cross-sectional analysis

Background

Renal dysfunction is a common problem in the HIV+ population, due to the effect of both the HIV virus and the several classes of ARV drugs such as tenofovir (TDF). It is also known that the presence of renal damage correlates with cardiovascular risk and therefore with the risk of mortality of the patients accordingly. The detection of early renal damage is very important. Albuminuria and microalbuminuria are markers of early kidney disease and cardiovascular risk. The aim of the study is to evaluate the prevalence of microalbuminuria in a large polycentric sample, of unselected and consecutive HIV-patients followed as outpatients, and to assess its association with different therapeutic regimens.

Methods

We studied 326 patients with a mean age of 48.4 ± 1.6 years, treated at the Infectious Diseases Clinics of Chieti and Perugia for 48 weeks. The main metabolic parameters and the microalbuminuria levels in a single sample of urine were evaluated.

Results

Microalbuminuria was detected in 61.0% of patients at T0 and in 49.7% after 48 weeks of observation with a median values of 1.1 mg/L (IQR: 0-2.7) vs. 0 mg/L (IQR: 0-2.0). 70% of the enrolled population did not show changes in microalbuminuria levels over time, 19% showed improvement, and 11% of the population had a worsening of microalbuminuria levels without any alteration of creatinine, uric acid and GFR-MDRD. We also found a statistically significant association between the development of microalbuminuria and gender (p < 0.035), Arterial Hypertension (AH) (p < 0.028) and therapy with TDF (p < 0.050).

Conclusion

We showed a very high prevalence of microalbuminuria, much higher than the literature data; the use of TDF affects the renal function in a statistically significant way and should therefore be considered a risk factor for kidney damage, which can be early assessed with the measurement of microalbuminuria.

Altered Underlying Renal Tubular Function in Patients With Chronic Hepatitis B Receiving Nucleos(t)ide Analogs in a Real-World Setting: The MENTE Study

BACKGROUND

Cases of renal tubular dysfunction have been reported in patients with hepatitis B and in patients with human immunodeficiency virus who are undergoing tenofovir treatment. However, little is known about the impact on tubular function in patients with chronic hepatitis B (CHB) under long-term use of entecavir (ETV) and tenofovir disoproxil fumarate (TDF). We evaluated markers of renal tubular function and bone turnover in patients with CHB treated with ETV or TDF.

PATIENTS AND METHODS

A multicenter, cross-sectional study was performed on markers of renal tubular function and bone turnover in hepatitis B virus-monoinfected patients on long-term treatment with Entecavir or Tenofovir (the MENTE study). The analyzed parameters were: retinol-binding protein/creatinine, neutrophil gelatinase-associated lipocalin/creatinine, excretion of phosphates, uric acid excretion, glomerular filtrate, protein/creatinine, albumin/creatinine, serum creatinine, phosphate, CTX, P1NP, vitamin D, and parathormone.

RESULTS

A total of 280 patients (ETV: 89, TDF: 69, control: 122) were included in this study. The TDF group was associated with altered levels of retinol-binding protein (RBP)/creatinine (TDF 25% vs. 7% ETV and control; P<0.001). Protein/creatinine, uric acid excretion, P1NP1, and parathormone were higher in the TDF group. The proportion of patients with serum phosphate <2.5 mg/dL was higher in both the ETV and the TDF groups compared with the control. The multivariate analysis showed that the use of TDF was independently associated with a higher risk of altered excretion of RBP/creatinine (4.4; interquartile range: 1.4 to 14; P=0.013).

CONCLUSIONS

We found an independent association between TDF use and altered RBP excretion. This finding indicates subclinical tubular damage. Because tubular dysfunction can precede the decline of renal function, close monitoring of RBP levels in patients with CHB on nucleos(t)ide analog treatment must be performed for early detection of TDF-related renal toxicity. In this study, these differences in tubular function were not associated with concomitant changes in markers of bone turnover.

Urinary Markers of Tubular Injury in HIV-Infected Patients

Renal disease is a common complication of HIV-infected patients, associated with increased risk of cardiovascular events, progression to AIDS, AIDS-defining illness, and mortality. Early and accurate identification of renal disease is therefore crucial to improve patient outcomes. The use of serum creatinine, along with proteinuria, to detect renal involvement is essentially to screen for markers of glomerular disease and may not be effective in detecting earlier stages of renal injury. Therefore, more sensitive and specific markers are needed in order to early identify HIV-infected patients at risk of renal disease. This review article summarizes some new and important urinary markers of tubular injury in HIV-infected patients and their clinical usefulness in the renal safety follow-up of TDF-treated patients.

Elevation of Non-Classical (CD14+/lowCD16++) Monocytes Is Associated with Increased Albuminuria and Urine TGF-β1 in HIV-Infected Individuals on Stable Antiretroviral Therapy

OBJECTIVE

High rates of albuminuria are observed among HIV-infected individuals on stable antiretroviral therapy (ART). Though pro-inflammatory and pro-fibrotic responses are described as components of albuminuria in the general population, it is unclear how these responses are associated to albuminuria in ART-treated chronic HIV. We investigated the relationship of monocyte subsets and urine inflammatory and fibrotic biomarkers to albuminuria in ART-treated HIV-infected participants.

DESIGN AND METHODS

Cross-sectional analyses were performed on Hawaii Aging with HIV-cardiovascular disease study cohort participants who were required at entry to be ≥40 years old and on ART ≥3 months. Monocyte subpopulations were determined in banked peripheral blood mononuclear cells (PBMC) using multi-parametric flow-cytometry. Entry random urine samples were assessed for albumin-to-creatinine ratios (UACR). Urine samples were measured for inflammatory and fibrotic biomarkers using Luminex technology.

RESULTS

Among 96 HIV-infected subjects with measured UACR (87% male, 59% Caucasian, and 89% undetectable HIV RNA with median CD4 of 495.5 cells/μL), 18 patients (19%) had albuminuria. Non-classical (CD14low/+CD16++) monocytes were significantly elevated in subjects with albuminuria (p = 0.034) and were correlated to UACR (r = 0.238, p = 0.019). Elevated non-classical monocyte counts were significant predictors of worsening albuminuria, independent of traditional- and ART-associated risk factors (β = 0.539, p = 0.007). Urine TGF-β1 and collagen-IV were significantly higher in albuminuric compared to non-albuminuric participants (TGF-β1; p = 0.039 and collagen-IV; p = 0.042). Urine TGF-β1 was significantly correlated with non-classical monocyte counts (r = 0.464, p = 0.017).

CONCLUSION

Alterations in monocyte subpopulations and urine pro-fibrotic factors may play a role in kidney dysfunction during chronic HIV infection and warrants further study.

Tenofovir clearance is reduced in HIV-positive patients with subclinical tubular impairment

OBJECTIVE

To assess if tenofovir (TFV) clearance is associated with urinary retinal-binding protein (RBP) in HIV-positive patients with normal estimated filtration rate.

DESIGN

A cross-sectional diagnostic study.

METHODS

HIV-positive patients with estimated creatinine clearance above 60 ml/min, on tenofovir disoproxil fumarate (TDF)-containing combination since at least 6 months, taking TDF at night, and without significant comorbidities (diabetes, untreated hypertension, known renal malformations, recurrent nephrolithiasis) and nephrotoxic drugs were included. TFV plasma and urinary concentrations were measured 12 h after drug intake (C12). RBP was measured through enzyme immunoassay kit on spot urines and corrected per urinary creatinine (uRBP/uCr); normality ranges were below 130 μg/g (in patients aged <50 years) and below 172 μg/g (in patients aged ≥50 years).

RESULTS

Two hundred and eighty-nine patients were included (median age of 45.8 years, 71.6% male and 85.4% whites); patients were concomitantly treated with nonnucleoside reverse transcriptase inhibitors (155, 53.6%), protease inhibitors (118, 40.8%), or integrase inhibitors (16, 5.5%)-containing regimens. Estimated creatinine clearance was 89.4 ml/min (78.6-105.9). Urinary RBP (uRBP) and uRBP/uCr were 204.6 ng/ml (92-380) and 169.7 μg/g (85.8-318.3), respectively; abnormally high uRBP/uCr was observed in 157 patients (54.3%). A multivariate binary logistic regression confirmed that both ethnicity (P = 0.004, β 2.93, 95% confidence interval 1.41-6.10) and TFV urinary C12 less than 21 mg/ml (P = 0.006, β 2.04, 95% confidence interval 1.12-3.41) were significantly associated with abnormal uRBP/uCr.

CONCLUSION

HIV-positive TDF-treated patients showed a high prevalence of proximal tubular impairment: ethnicity (whites) and low urinary TFV concentrations were significantly associated with elevated uRBP. SDC VIDEO:: http://links.lww.com/QAD/A852.

Prevalence and significance of proximal renal tubular abnormalities in HIV-infected patients receiving tenofovir

OBJECTIVES

Patients receiving tenofovir, disoproxil, fumarate (TDF) had an increased prevalence of proximal renal tubular dysfunction (PRTD), but contributing factors and its clinical significance remain controversial.

DESIGN AND METHODS

Cross-sectional evaluation of different urinary parameters (proteinuria, albuminuria, phosphaturia, uricosuria, glycosuria) in 200 HIV-infected patients receiving TDF, 26 following TDF discontinuation, and 22 never treated with TDF, included in a prospective cohort study. PRTD was defined as two or more tubular abnormalities.

RESULTS

After a median of 65 months (interquartile range, 42.7-84.7), at least one tubular alteration was found in 72% of patients, mostly proteinuria (42, 50, and 14% in current, previous and never TDF use; P=0.02) and phosphaturia (46, 42, and 14%; respectively, P < 0.01). PRTD was found in 63 patients (32%) receiving TDF, ranging from 14 to 46% according to concomitant hepatitis C virus coinfection, diabetes mellitus or hypertension arterial, in contrast with six (23%) following TDF discontinuation, and zero cases in no TDF-treated patients. The use of TDF [odds ratio (OR) 13.2; 95% confidence interval (CI) 1.4-22.7; P = 0.01], cumulative time on combination antiretroviral therapy (OR 1.011; 95% CI 1.07-1.019 per month; P = 0.01), and baseline estimated glomerular filtration rate (eGFR, OR 0.97; 95% CI 0.94-0.99 per ml/min per 1.73 m higher; P = 0.04) were associated with PRTD. The number of tubular abnormalities was linearly associated with eGFR decline since TDF initiation (β-coefficient -0.15, P = 0.02), together with age (-0.18; P = 0.01), baseline eGFR (0.49, P = 0.01), diabetes mellitus (-0.19, P = 0.02), and time on TDF (-0.23; P = 0.01).

CONCLUSION

The use of TDF leads to an increased rate of tubular dysfunction, and modulated by age, baseline eGFR, and classical factors, is associated with kidney function decline.

Tenofovir monotherapy for hepatitis B after 1 year does not produce renal dysfunction, but is associated with hyperparathyroidism not related to vitamin D

INTRODUCTION

Viral hepatitis B (VHB) represents a major public health problem. Studies from HIV multidrug patients have associated the use of tenofovir disoproxil fumarate (TDF) with renal dysfunction and phosphate wasting.

OBJECTIVE

The aim of this study was to examine the effect of year-long TDF monotherapy on renal function in VHB patients.

PATIENTS AND METHODS

We evaluated adult patients diagnosed with VHB before treatment initiation (T0), and after 3 and 12 months (T3 and T12) of TDF initiation. Estimated glomerular filtration rate (eGFR) was estimated by serum cystatin C and creatinine. In addition, urinary electrolytes and tubular biomarkers (cystatin C, β2-microglobulin and neutrophil gelatinase-associated lipocalin) were analyzed, as well as parathyroid hormone (PTH) and 25(OH)vitamin D levels.

RESULTS

After 1 year, 32 patients completed the study, 22 (68.7%) men and 12 (37.5%) Whites, mean age 44.1±12.0 years. We found that serum electrolytes were similar at baseline and 3 or 12 months after initiation of TDF monotherapy. In addition, urinary fractional excretions of electrolytes as well as proteinuria, albuminuria, urinary β2-microglobulin, and urinary cystatin C showed no significant differences across the treatment timeline. There were also no statistical differences in the eGFR. There was a statistically significant increase in the PTH (Friedman's test, P=0.012), but the 25(OH)vitamin D levels were in the normal range in the beginning and did not change at the follow-up. Moreover, there was no correlation between the initial levels of vitamin D and the corresponding increases in the PTH values.

CONCLUSION

If used as monotherapy in hepatitis B patients for a 12-month period, TDF is not associated with changes in either eGFR or a panel of urinary biomarkers. Serum and urinary electrolytes also remained unchanged. Of note, a significant increase in the PTH was found, although not related to the 25(OH)vitamin D initial status.

Markers of renal disease and function are associated with systemic inflammation in HIV infection

OBJECTIVES

Both renal disease and systemic inflammation predict non-AIDS-defining events and overall mortality in HIV-infected patients. Here, we sought to determine the relationships between renal disease and circulating inflammation markers.

METHODS

We performed a secondary analysis of AIDS Clinical Trials Group Study A5224s to determine if markers of renal disease [urine protein:creatinine ratio (uPCR), urine albumin:creatinine ratio (uACR), and estimated glomerular filtration rate (eGFR), using Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine and cystatin C-creatinine] were associated with markers of systemic inflammation [high-sensitivity C-reactive protein, interleukin-6, tumour necrosis factor (TNF)-α, soluble TNF-α receptor I (sTNFRI), sTNFRII, and soluble vascular cellular and intercellular adhesion molecules]. We correlated these renal and inflammatory markers prior to antiretroviral initiation and after 96 weeks of therapy.

RESULTS

We found that eGFR (estimated using CKD-EPI cystatin C-creatinine), uPCR, and uACR were significantly correlated with most assessed markers of systemic inflammation prior to antiretroviral initiation. uPCR and eGFR (using CKD-EPI cystatin C-creatinine), but not uACR, remained significantly correlated with most of the assessed inflammatory markers after 96 weeks of antiretroviral therapy (ART). Most of these correlations, although statistically significant, were < 0.50. eGFR using CKD-EPI creatinine was much less frequently associated with inflammation markers and only significantly correlated with sTNFR1 at week 0 and with sTNFRI and II at week 96.

CONCLUSIONS

Renal disease and function were associated with systemic inflammation in HIV infection, both before and after ART. Systemic inflammation may partially explain the relationships between proteinuria, albuminuria, and reduced renal function and future adverse outcomes.

Effects on vitamin D, bone and the kidney of switching from fixed-dose tenofovir disoproxil fumarate/emtricitabine/efavirenz to darunavir/ritonavir monotherapy: a randomized, controlled trial (MIDAS)

BACKGROUND

Efavirenz (EFV) has been associated with reductions in vitamin D (25[OH]D) and tenofovir (TDF) with increased bone turnover, reductions in bone mineral density (BMD) and renal tubular dysfunction. We hypothesized that switching from fixed-dose TDF/emtricitabine (FTC)/EFV to darunavir/ritonavir monotherapy (DRV/r) might increase 25(OH)D and BMD, and improve renal tubular function.

METHODS

Subjects with HIV RNA <50 copies/ml on TDF/FTC/EFV for ≥6 months were randomized 1:1 to ongoing TDF/FTC/EFV or DRV/r (800/100 mg once daily) for 48 weeks. The primary end point was change from baseline in 25(OH)D at week 48. Secondary end points included changes in BMD, bone turnover markers and renal tubular function.

RESULTS

A total of 64 subjects (86% male, 66% white, mean [sd] CD4(+) T-cell count 537.3 [191.5]/mm(3)) were analysed. After adjustment for baseline 25(OH)D and demographics, at week 48 DRV/r monotherapy was associated with a +3.6 (95% CI 0.6, 6.6) ng/ml increase in 25(OH)D compared to TDF/FTC/EFV (P=0.02). DRV/r monotherapy was associated with an increase in BMD (+2.9% versus -0.003% at the neck of femur and +2.6% versus +0.008% at the lumbar spine for DRV/r versus TDF/FTC/EFV; P<0.05 for all) and reductions in bone biomarkers compared with those remaining on TDF/FTC/EFV. No significant difference in renal tubular function was observed. Reasons for discontinuation in the DRV/r arm included side effects (n=4) and viral load rebound (n=3), all of which resolved with DRV/r discontinuation or regimen intensification.

CONCLUSIONS

Switching from TDF/FTC/EFV to DRV/r in patients with suppressed HIV RNA resulted in significant improvements in 25(OH)D and bone biomarkers, and a 2-3% increase in BMD.

Urine alpha1-microglobulin is a better marker for early tubular dysfunction than beta2-microglobulin among tenofovir-exposed human immunodeficiency virus-infected men who have sex with men

OBJECTIVES

Men who have sex with men are at risk of tenofovir nephrotoxicity due to its wide use in both treatment and prophylaxis for human immunodeficiency virus infection, but little is known about the urinary biomarkers of early renal dysfunction in this population. This study aims to identify useful biomarkers of early renal dysfunction among human immunodeficiency virus-infected men who have sex with men exposed to tenofovir.

METHODS

In a cross-sectional study urinary alpha1-microglobulin, beta2-microglobulin, N-acetyl-β-d-glucosaminidase and albumin were measured and expressed as the ratio-to-creatinine in 239 human immunodeficiency virus-infected men who have sex with men who were treatment naïve or receiving antiretroviral therapy with tenofovir-containing or non-tenofovir-containing regimens. Additionally, 56 patients in the non-antiretroviral therapy group started a tenofovir-containing regimen and were assessed after 3 and 6 months on antiretroviral therapy.

RESULTS

Both the frequency of alpha1-microglobulin proteinuria (alpha1-microglobulin-creatinine ratio >25.8mg/g) and the median urinary alpha1-microglobulin-creatinine ratio were higher in the tenofovir disoproxil fumarate group than the other two groups (all p<0.05). A higher frequency of beta2-microglobulin proteinuria (beta2-microglobulin-creatinine ratio >0.68mg/g) was also observed in the tenofovir group (28.9%) compared to the non-tenofovir group (13.6%, p=0.024). There were no significant differences between groups for N-acetyl-β-d-glucosaminidase and albumin. In the longitudinal study, the median urinary alpha1-microglobulin-creatinine ratio after 3 and 6 months on tenofovir-containing therapy (16.8 and 17.3mg/g) was higher than baseline (12.3mg/g, p=0.023 and 0.011, respectively), while no statistically important changes were observed in urinary beta2-microglobulin-creatinine ratio or in the other biomarkers after 3 and 6 months on antiretroviral therapy (all p>0.05).

CONCLUSION

Urinary alpha1-microglobulin seems to be a more sensitive and stable indicator of tubular dysfunction than urinary beta2-microglobulin for assessing tenofovir-related nephrotoxicity and can be significantly altered after tenofovir exposure.

Monitoring of kidney function in HIV-positive patients

HIV-positive patients are at increased risk of developing chronic kidney disease. Although guidelines recommend regular monitoring of renal function in individuals living with HIV, the optimal frequency remains to be defined. In this review, we discuss the renal syndromes that may be identified at an earlier stage via routine assessment of kidney function, and provide guidance in terms of the frequency of monitoring, the most useful tests to perform, and their clinical significance. Specifically, we address whether annual monitoring of kidney function is appropriate for the majority of HIV-positive patients.

Relationships between renal parameters and serum and urine markers of inflammation in those with and without HIV infection

We sought to determine the relationships among intrarenal and systemic inflammation and renal disease in HIV. We compared paired serum and urinary levels (normalized to urine creatinine) of monocyte chemotactic protein-1 (MCP-1), regulated on activation normal T cell expressed and secreted (RANTES), interferon-γ-induced protein-10 (IP-10), interleukin-8 (IL-8), and β2-microglobulin (B2M) between two groups of HIV-infected subjects not receiving antiretroviral therapy (ART) [A: not expecting to initiate ART immediately due to having CD4 cell counts ≥350/μl, N=26; B: about to initiate ART, N=19], a group of HIV-infected subjects receiving virologically suppressive antiretroviral therapy [C, N=30], and a group of HIV-uninfected, healthy volunteers [D, N=45]. We then correlated these inflammatory biomarker levels with urine protein/creatinine ratios (uPCR), urine albumin/creatinine ratios (uACR), and estimated glomerular filtration rates (eGFR). Urine inflammatory biomarker levels were highest in Group B. When combining all four study groups, statistically significant positive correlations included uPCR with urine IL-8, urine MCP-1, urine IP-10, and serum IP-10 and uACR with urine IL-8, urine B2M, serum IP-10, and serum B2M. eGFR was statistically significantly negatively correlated with serum MCP-1 and serum B2M. Paired serum and urine levels of IP-10 and B2M (but not IL-8, RANTES, or MCP-1) were significantly correlated with each other in the overall group. The levels of urine inflammatory markers tested differed by HIV status and use of virologically suppressive ART. These urine and serum inflammatory markers were differentially correlated with uPCR, uACR, and eGFR, suggesting that different intrarenal and systemic inflammatory pathways may contribute to different measures of nephropathy.

Low-grade proteinuria is highly prevalent in HIV-positive patients on antiretroviral treatment

OBJECTIVES

HIV-positive patients are at an increased risk for chronic kidney disease. However, these data mainly derive from cohorts with a high percentage of African-American patients, representing a specific ethnical risk group for chronic kidney disease. The aim of this study was to estimate the prevalence and risk factors specifically for early signs of kidney dysfunction in a large, predominantly white cohort of HIV patients.

DESIGN

Cross-sectional study.

METHODS

Prevalence of low-grade proteinuria was measured by quantitative analysis of urinary protein-to-creatinine ratio (cutoff >70 mg/g) and further differentiated by assessing α1-microglobulin (tubular proteinuria) and albumin-to-creatinine ratio (glomerular proteinuria) of HIV patients attending the University Hospital in Cologne, Germany. Together with standard and HIV-related laboratory findings and medical history, risk factors for each form of proteinuria were identified using multivariate forward selection.

RESULTS

Of 945 enrolled patients, 55% were identified with low-grade proteinuria, 41% with tubular proteinuria, and 20% with glomerular proteinuria. Older age was a risk factor for all forms of proteinuria in multivariate analysis. Low-grade proteinuria was also associated with concomitant diabetes and exposure to nucleoside reverse transcriptase inhibitor [anytime during HIV infection, not tenofovir (TDF)-specific], whereas tubular proteinuria was linked to current and any exposure to nucleoside reverse transcriptase inhibitor (TDF-specific). Further risk factors for glomerular proteinuria were hypertension and diabetes in this cohort.

CONCLUSION

Low-grade, glomerular and tubular proteinuria are highly prevalent in this large white HIV cohort. Older age represents a nonmodifiable risk factor for all forms of proteinuria. Glomerular proteinuria is associated with modifiable cardiovascular, but not HIV-related risk factors, whereas tubular proteinuria is linked to TDF exposure.

Urine retinol-binding protein 4: a functional biomarker of the proximal renal tubule

Measurement of retinol-binding protein 4 in urine (uRBP4) is arguably the most sensitive biomarker for loss of function of the human proximal renal tubule. Megalin- and cubilin-receptor-mediated endocytosis normally absorbs > 99% of the approximately 1.5 g/24 h of protein filtered by the renal glomerulus. When this fails there is "tubular proteinuria," comprising uRBP4, albumin, and many other proteins and peptides. This tubular proteinuria is a consistent feature of the renal Fanconi syndrome (FS) and measurement of uRBP4 appears to be an excellent screening test for FS. FS occurs in rare inherited renal diseases including cystinosis, Dent disease, Lowe syndrome, and autosomal dominant FS. Acquired FS occurs in paraproteinemias, tubulointerstitial renal disease, oncogenic osteomalacia, Chinese herbs nephropathy, and Balkan endemic nephropathy. Though poorly understood, FS may be associated with HIV disease and antiretroviral treatment; cadmium poisoning may cause FS. In addition to FS, uRBP4 measurement has a different role: the early detection of acute kidney injury. Urine RBP4 comprises several isoforms, including intact plasma RBP4, MW 21.07 kDa, and C-terminal truncated forms, des-L- and des-LL-RBP4, also probably plasma derived. In FS, uRBP4 levels are about 104-fold above the upper limit of normal and small increments are frequently seen in carriers of some inherited forms of FS and in acquired disease. The very high levels in disease, frequent assay nonlinearity, lack of defined calibrants, and multiple uRBP4 isoforms make accurate assay challenging; top-down mass spectrometry has brought advances. Assays for uRBP4 with defined molecular targets allowing good interlaboratory comparisons are needed.