Early markers of tubular dysfunction in antiretroviral-experienced HIV-infected patients treated with tenofovir versus abacavir

Effect of anti-retroviral regimen on proximal tubular function in Zambian adolescents and young adults living with HIV: A cross sectional study

Background: Tenofovir regimens remain the preferred formulations in the HIV guidelines for adolescents and young adults in Zambia and globally. However, some adolescents and young adults are maintained on abacavir by clinicians because of anxiety about possible proximal tubular dysfunction from tenofovir. We assessed the effect of two regimens on proximal tubular function in adolescents and young adults living with HIV. Methods: This was a cross-sectional study involving 180 participants with HIV receiving either tenofovir or abacavir for ≥12 months at the largest tertiary teaching hospital. Two first-morning urine and blood specimens were collected and analyzed for proximal tubular markers, glomerular function, electrolytes, and routine monitoring tests. Proximal tubular function was determined by measuring the fractional excretion of phosphate (FePO4). Proximal tubular dysfunction was defined by FePO4 ≥20% regardless of serum phosphate and FePO4  ≥10-20% when serum phosphate was below 0.81mmol/L. Results: The prevalence of proximal tubular dysfunction was 6% and was higher in the tenofovir group than the abacavir (10% vs. 2%, p<0.058). However, after adjusting for potential confounders, tenofovir was not associated with worse proximal tubular function. Age, urine b2-microglobulin: creatinine ratio, C-reactive protein, and urine protein: creatinine ratio was all associated with worsening proximal tubular dysfunction. Reduced estimated glomelurar filtration rate (eGFR) was found in four (2.2%) participants; three of which were on tenofovir. Conclusions: Proximal tubular dysfunction defined by FePO4 was more prevalent in the tenofovir group than the abacavir group, but not after adjusting for age. Our findings should be interpreted with caution as age differences between the two groups confounded the results.

Treatment of Human Immunodeficiency Virus Infection With Tenofovir Disoproxil Fumarate-Containing Antiretrovirals Maintains Low Bone Formation Rate, But Increases Osteoid Volume on Bone Histomorphometry

Bone mineral density (BMD) loss is a known complication of human immunodeficiency virus (HIV) infection and its treatment, particularly with tenofovir disoproxil fumarate (TDF)-containing antiretroviral regimens. Although renal proximal tubular dysfunction and phosphaturia is common with TDF, it is unknown whether BMD loss results from inadequate mineralization. We evaluated change in BMD by dual-energy X-ray absorptiometry (DXA) and bone histomorphometry by tetracycline double-labeled transiliac crest biopsies in young men living with HIV before (n = 20) and 12 months after (n = 16) initiating TDF/lamivudine/efavirenz. We examined relationships between calciotropic hormones, urinary phosphate excretion, pro-inflammatory and pro-resorptive cytokines, and bone remodeling-related proteins with changes in BMD and histomorphometry. Mean age was 29.6 ± 5.5 years, with mean CD4 + T cell count of 473 ± 196 cells/mm³ . At baseline, decreased bone formation rate and increased mineralization lag time were identified in 16 (80%) and 12 (60%) patients, respectively. After 12 months, we detected a 2% to 3% decrease in lumbar spine and hip BMD by DXA. By histomorphometry, we observed no change in bone volume/total volume (BV/TV) and trabecular parameters, but rather, increases in cortical thickness, osteoid volume, and osteoblast and osteoclast surfaces. We did not observe significant worsening of renal phosphate excretion or mineralization parameters. Increases in PTH correlated with decreased BMD but not histomorphometric parameters. Overall, these data suggest abnormalities in bone formation and mineralization occur with HIV infection and are evident at early stages. With TDF-containing antiretroviral therapy (ART), there is an increase in bone remodeling, reflected by increased osteoblast and osteoclast surfaces, but a persistence in mineralization defect, resulting in increased osteoid volume. © 2019 American Society for Bone and Mineral Research.

Tenofovir disoproxil fumarate initiation and changes in urinary biomarker concentrations among HIV-infected men and women

OBJECTIVES

Urinary biomarkers of kidney injury may have potential to identify subclinical injury attributable to tenofovir disoproxil fumarate (TDF) toxicity.

DESIGN

This observational study included 198 HIV-infected participants from the Multicenter AIDS Cohort Study and the Women's Interagency HIV Study, who initiated TDF between 2009 and 2015 and had urine samples collected at baseline before and after TDF initiation.

METHODS

We used linear mixed-effects models controlling for urine creatinine and time on TDF to evaluate the effects of TDF initiation on changes in 14 urinary biomarkers.

RESULTS

Within 1 year after TDF initiation, concentrations of trefoil factor 3 [+78%; 95% confidence interval (CI) +38%, +129%), alpha-1 microglobulin (α1m) (+32%; 95% CI +13%, +55%), clusterin (+21%; 95% CI +6%, +38%), uromodulin (+19%; 95% CI +4%, +36%), and kidney injury molecule-1 (KIM-1) (+13%; 95% CI +1%, +26%) significantly increased, whereas interleukin-18 (IL-18) significantly decreased (-13%, 95% CI -7%, -25%). Subsequent to the first year of TDF use, biomarker concentrations stabilized, and these changes were not statistically significant. When stratifying by baseline viremia (HIV-1 RNA < vs. ≥80 copies/ml), concentration changes for most biomarkers during the first year of TDF use were greater among aviremic vs. viremic participants, with significant differences in α1m (+80 vs. +22%), KIM-1 (+43 vs. +10%), beta-2 microglobulin (+83 vs. -10%), YKL-40 (+33 vs. -5%), and IL-18 (+20 vs. -27%).

CONCLUSIONS

TDF initiation was associated with substantial changes in urinary biomarkers of kidney injury within the first year of use, particularly among aviremic participants. A urinary biomarker panel may be a clinically useful tool to detect and monitor the heterogeneous effects of TDF on the kidney.

Efavirenz reduces renal excretion of lamivudine in rats by inhibiting organic cation transporters (OCT, Oct) and multidrug and toxin extrusion proteins (MATE, Mate)

Efavirenz (EFV) is a non-nucleoside reverse transcriptase inhibitor used in first-line combination antiretroviral therapy (cART). It is usually administered with nucleoside reverse transcriptase inhibitors (NRTI), many of which are substrates of OCT uptake solute carriers (SLC22A) and MATE (SLC47A), P-gp (MDR1, ABCB1), BCRP (ABCG2), or MRP2 (ABCC2) efflux transporters. The aim of this study was to evaluate the inhibitory potential of efavirenz towards these transporters and investigate its effects on the pharmacokinetics and tissue distribution of a known Oct/Mate substrate, lamivudine, in rats. Accumulation and transport assays showed that efavirenz inhibits the uptake of metformin by OCT1-, OCT2- and MATE1-expressing MDCK cells and reduces transcellular transport of lamivudine across OCT1/OCT2- and MATE1-expressing MDCK monolayers. Only negligible inhibition of MATE2-K was observed in HEK-MATE2-K cells. Efavirenz also reduced the efflux of calcein from MDCK-MRP2 cells, but had a rather weak inhibitory effect on Hoechst 33342 accumulation in MDCK-MDR1 and MDCK-BCRP cells. An in vivo pharmacokinetic interaction study in male Wistar rats revealed that intravenous injection of efavirenz or the control Oct/Mate inhibitor cimetidine significantly reduced the recovery of lamivudine in urine and greatly increased lamivudine retention in the renal tissue. Co-administration with efavirenz or cimetidine also increased the AUC0-∞ value and reduced total body clearance of lamivudine. These data suggest that efavirenz is a potent inhibitor of OCT/Oct and MATE/Mate transporters. Consequently, it can engage in drug-drug interactions that reduce renal excretion of co-administered substrates and enhance their retention in the kidneys, potentially compromising therapeutic safety.

Bone mineral density reductions after tenofovir disoproxil fumarate initiation and changes in phosphaturia: a secondary analysis of ACTG A5224s

Background

It is unknown if the greater reductions in bone mineral density (BMD) associated with initiation of tenofovir disoproxil fumarate compared with abacavir in previously untreated HIV-infected participants in the ACTG A5224s clinical trial were associated with potentially worsening tenofovir-related phosphaturia.

Methods

We correlated changes in BMD at the hip and spine with changes in phosphaturia [transtubular reabsorption of phosphorus (TRP) and tubular maximum phosphate reabsorption per glomerular filtration rate (TmP/GFR)] from entry through week 96 in those initiating tenofovir ( n  =   134) versus abacavir ( n  =   135) with efavirenz or atazanavir/ritonavir in A5224s. We also correlated changes in BMD with tenofovir AUC measured between weeks 4 and 24.

Results

Changes in TRP and TmP/GFR through week 96 between the tenofovir and abacavir arms were not significantly different (both P  ≥   0.70) and did not differ with use of efavirenz versus atazanavir/ritonavir. There were no significant correlations between changes in either TRP or TmP/GFR and with either hip or spine BMD in the tenofovir arms. Tenofovir AUC was significantly correlated with changes in hip BMD, but not spine BMD, at week 24 ( r  =   -0.22, P  =   0.028) and week 48 ( r  =   -0.26, P  =   0.010), but not at week 96 ( r  =   -0.14, P  =   0.18).

Conclusions

Changes in phosphaturia were not different between the tenofovir and abacavir arms in A5224s. Changes in hip and spine BMD with tenofovir were not related to changes in phosphaturia. However, tenofovir exposure was weakly associated with changes in hip BMD through week 48.

Diagnostic challenges of kidney diseases in HIV-infected patients

INTRODUCTION

Chronic kidney disease (CKD) is a prevalent comorbidity in persons living with HIV infection (PLWH) associated with an increase in cardiovascular morbidity and all-cause mortality. Furthermore, early diagnosis of CKD is difficult in PLWH. Areas covered: We reviewed the main diagnostic tools for CKD in PLWH, and discussed their strengths and limits. We performed a literature search on PubMed to identify reviews and clinical trials dealing with attractive kidney biomarkers of CKD in PLWH, with the following key words: 'HIV AND kidney', 'HIV AND Kidney biomarkers', 'CKD AND Kidney biomarkers'. Expert commentary: Currently, CKD diagnosis is based on the estimation of Glomerular Filtration Rate (GFR), and measurement of proteinuria by urine protein/creatinine ratio (uPCR). These parameters are independent and complementary predictors of outcomes. GFR estimates are lacking in accuracy in PLWH. The best GFR estimate is CKD-EPI study equation. Moreover, low-grade proteinuria is associated with an increased risk of kidney disease progression in PLWH, and guidelines derived from the general population may lack sensitivity. Different biomarkers of kidney diseases like N-acetyl beta glucosaminidase (NAG), Kidney Injury Molecule-1 (KIM-1), and Alpha-1-microglobulin may predict kidney disease progression and mortality in PLWH. Others may help clinicians detect antiretroviral-induced tubulopathy, or predict cardiovascular events. More studies are needed to validate the routine use of these types of biomarkers.

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.

Endothelial Glycocalyx Damage and Renal Dysfunction in HIV Patients Receiving Combined Antiretroviral Therapy

Widespread use of combined antiretroviral therapy (cART) increased HIV patients' life expectancy, however, favored the development of kidney and cardiovascular diseases. The aim of this study was to investigate endothelial glycocalyx (eGC) damage and its association with renal function in HIV patients receiving cART. This is a cross-sectional study with HIV-infected patients with no renal and cardiovascular disease, recruited in public health centers in Brazil. Clinical and laboratory parameters of HIV patients were compared according to cART use and with a healthy control group. Blood ICAM-1 and syndecan-1 levels were quantified by ELISA kit. Estimated glomerular filtration rate (eGFR) was evaluated. A total of 69 HIV patients were included, with mean age of 33.4 ± 8.9 years, and 77.3% were male. Serum urea, creatinine, and eGFR were similar in all groups. No HIV patient had decreased GFR <60 ml/min. All HIV patients had higher systemic syndecan-1 compared with healthy controls (71.8 ± 25.4 ng/ml vs. 36.5 ± 14.3 ng/ml, p < .001). Syndecan-1 showed a significant positive correlation with serum creatinine (r = 0.437, p = .001), serum urea levels (r = 0.352, p = .006), and a negative correlation with eGFR (r = -0.315, p = .015) in HIV patients. Syndecan-1 remained independently associated with serum creatinine and reduced GFR even after we forced variables related with HIV infection status, tenofovir use, treatment time, dyslipidemia, and others in a multivariate analysis. HIV patients using cART with no clinical renal and cardiovascular disease presented eGC damage and it is associated with clinical markers of kidney dysfunction. Syndecan-1 may be a useful early biomarker to monitoring renal dysfunction in HIV patients in chronic use of cART. Further research is needed to evaluate this applicability.

Editor's Highlight: Comparative Renal Safety Assessment of the Hepatitis B Drugs, Adefovir, Tenofovir, Telbivudine and Entecavir in Rats

The aim of this study was to determine the relative safety of 4 antiviral drugs (telbivudine, tenofovir, adefovir, and entecavir) against hepatitis B virus with respect to kidney function and toxicity in male Sprague Dawley rats. The antiviral drugs were administered once daily for 4 weeks by oral gavage at ∼10 and 25-40 times the human equivalent dose. Main assessments included markers of renal toxicity in urine, magnetic resonance imaging (MRI) of kidney function, histopathology, and electron microscopic examination. Administration of adefovir at 11 and 28 mg/kg for 4 weeks caused functional and morphological kidney alterations in a time- and dose-dependent manner, affecting mainly the proximal tubules and suggesting a mechanism of toxicity related to mitochondrial degeneration/depletion. Of note, the observed adefovir-induced reduction of kidney function was not detected by the standard method of glomerular filtration rate (GFR) measurements (clearance rate of the endogenous marker, creatinine), thereby emphasizing the superiority of MRI in terms of sensitive detection of GFR in rats. For the low dose of 300 mg/kg of tenofovir, minor kidney effects such as nuclear enlargement in the tubular epithelium, and hyaline droplets accumulation were detected, which was also observed for the low dose (11 mg/kg) of adefovir. No assessments could be done at the higher dose of 600/1000 mg/kg tenofovir due to gastrointestinal tract toxicity which prevented treatment of the animals for longer than 1 week. Entecavir at 1 and 3 mg/kg and telbivudine at 600 and 1600 mg/kg caused no toxicologically relevant effects on the kidney.

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.

Efficacy and safety of switching to abacavir/lamivudine (ABC/3TC) plus rilpivirine (RPV) in virologically suppressed HIV-infected patients on HAART

We analysed the efficacy and safety of switching from a regimen based on nonnucleoside reverse transcriptase inhibitors (NNRTI) or integrase inhibitors (INI) to ABC/3TC + RPV in virologically suppressed HIV-infected patients. This multicentre, retrospective study comprised asymptomatic HIV-infected patients who switched from 2 NRTI + NNRTI or 2 NRTI + INI to ABC/3TC + RPV between February 2013 and December 2013; all had undetectable HIV viral load prior to switching. Efficacy and safety, and changes in lipids and cardiovascular risk (CVR) were analysed at 48 weeks. Of 85 patients (74.1 % men, mean age 49.5 years), 83 (97.6 %) switched from a regimen based on NNRTI (EFV 74, RPV 5, ETV 2, NVP 2), and 45 (53 %) switched from TDF/FTC to ABC/3TC. The main reasons for switching were toxicity (58.8 %) and convenience (29.4 %). At 48 weeks, 78 (91.8 %) patients continued taking the same regimen; efficacy was 88 % by intention to treat, and 96 % by per protocol. Two patients were lost to follow-up and five ceased the new regimen (4 due to adverse effects and 1 virologic failure). Mean CD4 cell counts increased (744 vs. 885 cells/μL; p = 0.0001), and there were mean decreases in fasting total cholesterol (-15.9 mg/dL; p < 0.0001) and LDL-cholesterol (-11.0 mg/dL; p < 0.004), with no changes in HDL-cholesterol, triglycerides, total cholesterol:HDL-cholesterol ratio, and CVR. ABC/3TC + RPV is effective and safe in virologically-suppressed patients on antiretroviral therapy (ART). Forty-eight weeks after switching the lipid profile improved with decreases in total and LDL cholesterol.

Tenofovir: What We Have Learnt After 7.5 Million Person-Years of Use

Tenofovir was licensed for use in patients with HIV in 2001 and since then has become a firmly established anti-retroviral in both guidelines and routine practice. Data have been presented from many pivotal studies—informing on its efficacy, use, and adverse features—and there are also over 7.5 million patient-years of experience to date. We explore the data on this nucleotide reverse transcriptase inhibitor in HIV presented since 2008—focusing on efficacy, side effects, and utility.

Proximal renal tubular dysfunction related to antiretroviral therapy among HIV-infected patients in an HIV clinic in Mexico

Proximal renal tubular dysfunction (PRTD) of varying severity has been associated with antiretroviral toxicity, especially related to the use of tenofovir (TDF). The aim of this study was to investigate whether HIV-infected patients who use a tenofovir-based regimen are at increased risk of tubular dysfunction. We conducted an observational, comparative, longitudinal, prospective study. Estimated glomerular filtration rate (eGFR) and markers of tubular damage to assess tubular dysfunction (fractional excretion of phosphate and uric acid, glycosuria, and proteinuria) were measured at baseline and at weeks 12 and 24. Of 111 participants, PRTD was found in 6.3% at week 12 and 9% at week 24, with no statistically significant difference between those on an abacavir (ABC)-containing regimen or a TDF-containing regimen. We also found an increase in triglycerides associated with the ABC-containing regimen compared with the TDF group. The use of an ABC- or TDF-containing regimen was independently associated with tubular dysfunction, but we found no significant differences between these groups, except when TDF was combined with a protease inhibitor. A better and more complete assessment of renal function is needed, because the presence of tubular dysfunction and proteinuria without impairment of eGFR may affect the renal safety of HIV-infected patients.

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

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

Impaired Urine Dilution Capability in HIV Stable Patients

Renal disease is a well-recognized complication among patients with HIV infection. Viral infection itself and the use of some antiretroviral drugs contribute to this condition. The thick ascending limb of Henle's loop (TALH) is the tubule segment where free water clearance is generated, determining along with glomerular filtration rate the kidney's ability to dilute urine. Objective. We analyzed the function of the proximal tubule and TALH in patients with HIV infection receiving or not tenofovir-containing antiretroviral treatment in comparison with healthy seronegative controls, by applying a tubular physiological test, hyposaline infusion test (Chaimowitz' test). Material & Methods. Chaimowitz' test was performed on 20 HIV positive volunteers who had normal renal functional parameters. The control group included 10 healthy volunteers. Results. After the test, both HIV groups had a significant reduction of serum sodium and osmolarity compared with the control group. Free water clearance was lower and urine osmolarity was higher in both HIV+ groups. Proximal tubular function was normal in both studied groups. Conclusion. The present study documented that proximal tubule sodium reabsorption was preserved while free water clearance and maximal urine dilution capability were reduced in stable HIV patients treated or not with tenofovir.

Association of higher plasma vitamin D binding protein and lower free calcitriol levels with tenofovir disoproxil fumarate use and plasma and intracellular tenofovir pharmacokinetics: cause of a functional vitamin D deficiency?

Tenofovir disoproxil fumarate (TDF) causes bone, endocrine, and renal changes by an unknown mechanism(s). Data are limited on tenofovir pharmacokinetics and these effects. Using baseline data from a multicenter study of HIV-infected youth on stable treatment with regimens containing TDF (n = 118) or lacking TDF (n = 85), we measured cross-sectional associations of TDF use with markers of renal function, vitamin D-calcium-parathyroid hormone balance, phosphate metabolism (tubular reabsorption of phosphate and fibroblast growth factor 23 [FGF23]), and bone turnover. Pharmacokinetic-pharmacodynamic associations with plasma tenofovir and intracellular tenofovir diphosphate concentrations were explored among those receiving TDF. The mean age was 20.9 (standard deviation [SD], 2.0) years; 63% were male; and 52% were African American. Compared to the no-TDF group, the TDF group showed lower mean estimated glomerular filtration rates and tubular reabsorption of phosphate, as well as higher parathyroid hormone and 1,25-dihydroxy vitamin D [1,25-OH(2)D] levels. The highest quintile of plasma tenofovir concentrations was associated with higher vitamin D binding protein, lower free 1,25-OH(2)D, higher 25-OH vitamin D, and higher serum calcium. The highest quintile of intracellular tenofovir diphosphate concentration was associated with lower FGF23. Higher plasma tenofovir concentrations were associated with higher vitamin D binding protein and lower free 1,25-OH(2)D, suggesting a functional vitamin D deficiency explaining TDF-associated increased parathyroid hormone. The finding of lower FGF23 accompanying higher intracellular tenofovir diphosphate suggests that different mechanisms mediate TDF-associated changes in phosphate handling. Separate pharmacokinetic properties may be associated with distinct TDF toxicities: tenofovir with parathyroid hormone and altered calcium balance and tenofovir diphosphate with hypophosphatemia and FGF23 regulation. (The clinical trial registration number for this study is NCT00490412 and is available online at http://clinicaltrials.gov/ct2/show/NCT00490412.).

Hypophosphataemia with non-tenofovir-containing antiretroviral therapy

Hypophosphataemia with tenofovir (TDF) treatment has been well described. The role of HIV infection and of other antiretroviral (ART) agents in hypophosphataemia has received less attention. The aim of this study was to determine the prevalence of hypophosphataemia in HIV-positive adults. We measured the fasting plasma phosphate level and estimated glomerular filtration rate (eGFR) in 123 HIV-positive patients. A total of 26% had hypophosphataemia and 11% had hypophosphataemia of grades 2-4 (0.65 mmol/L or less). Hypophosphataemia of any grade was more frequent in those who were ART-treated than ART-naive (35% versus 10%; P = 0.0001). Multiple linear regression analysis showed no significant association between phosphate level and gender, TDF status, duration of ART, duration of HIV infection and eGFR. Increasing age was significantly associated with a very small rise in phosphate level. Isolated hypophosphataemia was significantly more frequent in HIV-positive subjects receiving ART than ART-naive individuals, irrespective of the drug regimen.

Update on tenofovir toxicity in the kidney

Tenofovir (TFV) is a widely used and effective treatment for HIV infection. Numerous studies have shown that TFV exposure is associated with small but significant declines in estimated glomerular filtration rate (eGFR). However, TFV toxicity is targeted mainly at the proximal tubule (PT), and in severe cases can cause the renal Fanconi syndrome or acute kidney injury. Severe toxicity occurs in a minority of patients, but milder PT dysfunction is more common; the long-term significance of this on kidney and bone health is uncertain. Recent work suggests that changes in eGFR on TFV therapy might be explained by inhibition of PT creatinine secretion rather than actual alterations in glomerular function. Risk factors for nephrotoxicity include pre-existing kidney disease, increased age, and low body mass. Mitochondria in the PT are the targets of TFV toxicity, but the exact mechanisms remain unclear. Substantial improvement of renal function occurs in many patients with TFV toxicity upon stopping therapy, but function does not always return to baseline. In recent years, TFV usage has been extended to new clinical spheres, including pediatrics, resource-poor settings and treatment of hepatitis B infection; theoretical reasons exist as to why some of these patients might be at higher or lower risk of TFV toxicity. Finally, strategies have been proposed to prevent TFV toxicity or enhance recovery.

Renal dysfunction in the setting of HIV/AIDS

Antiretroviral therapy has been immensely successful in reducing the incidence of opportunistic infections and death after HIV infection. This has resulted in heightened interest in noninfectious comorbidities including kidney disease. Although HIV-associated nephropathy, the most ominous kidney disease related to the direct effects of HIV, may be prevented and treated with antiretrovirals, kidney disease remains an important issue in this population. In addition to the common risk factors for kidney disease of diabetes mellitus and hypertension, HIV-infected individuals have a high prevalence of other risk factors, including hepatitis C and exposure to antiretrovirals and other medications. Therefore, the differential diagnosis is vast. Early identification (through efficient screening) and prompt treatment of kidney disease in HIV-infected individuals are critical to lead to better outcomes. This review focuses on clinical and epidemiological issues, treatment strategies (including dialysis and kidney transplantation), and recent advances among kidney disease in the HIV population.

Renal toxicity associated with antiretroviral therapy

Renal disease is becoming an increasingly prevalent comorbidity in patients with human immunodeficiency virus (HIV) infection. The increase in life expectancy following the introduction of highly active antiretroviral therapy (HAART) and the long-term development of metabolic complications (such as diabetes and dyslipidaemia), hypertension, and vascular diseases can contribute to the increasing frequency in the recognition of renal impairment in HIV-infected patients. Some antiretroviral agents, and particularly tenofovir, have been associated with nephrotoxic drug effects, including decline in glomerular filtration rate, proximal tubular damage, and acute kidney injury. The occurrence of clinically evident renal toxicity in patients treated with HAART seems to be very low, but glomerular or tubular subclinical dysfunction may occur more frequently. Therefore, careful clinical and laboratory monitoring for the early recognition of renal abnormalities is recommended for all subjects receiving antiretroviral treatment. In this article, the current knowledge about the nephrotoxic effects of antiretroviral agents has been reviewed, and an algorithm for screening and management of HAART-related kidney disease is proposed in the light of the most recent clinical studies and international guidelines.