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

Elevated ALOX12 in renal tissue predicts progression in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the major causes of end-stage renal disease and one of the significant complications of diabetes. This study aims to identify the main differentially expressed genes in DKD from transcriptome sequencing results and analyze their diagnostic value. The present study sequenced db/m mouse and db/db mouse to determine the ALOX12 genetic changes related to DKD. After preliminary validation, ALOX12 levels were significantly elevated in the blood of DKD patients, but not during disease progression. Moreover, urine ALOX12 was increased only in macroalbuminuria patients. Therefore, to visualize the diagnostic efficacy of ALOX12 on the onset and progression of renal injury in DKD, we collected kidney tissue from patients for immunohistochemical staining. ALOX12 was increased in the kidneys of patients with DKD and was more elevated in macroalbuminuria patients. Clinical chemical and pathological data analysis indicated a correlation between ALOX12 protein expression and renal tubule injury. Further immunofluorescence double staining showed that ALOX12 was expressed in both proximal tubules and distal tubules. Finally, the diagnostic value of the identified gene in the progression of DKD was assessed using receiver operating characteristic (ROC) curve analysis. The area under the curve (AUC) value for ALOX12 in the diagnosis of DKD entering the macroalbuminuria stage was 0.736, suggesting that ALOX12 has good diagnostic efficacy. During the development of DKD, the expression levels of ALOX12 in renal tubules were significantly increased and can be used as one of the predictors of the progression to macroalbuminuria in patients with DKD.

The impact of age on antiretroviral drug pharmacokinetics in the treatment of adults living with HIV

INTRODUCTION

People living with HIV (PLWH) are aging and will receive life-long treatment: despite substantial improvement in drug efficacy and tolerability, side effects still occur and they can blunt antiretroviral treatment effectiveness. Since age may affect drug exposure and may be associated with side-effects we aimed at reviewing available data on the effect of age on antiretrovirals' pharmacokinetics in adult patients.

AREAS COVERED

We searched public databases and major conference proceedings for data on age and pharmacokinetics/pharmacodynamics in PLWH. We limited our review to currently used drugs and focused on population pharmacokinetics and physiologically-based pharmacokinetic modeling studies.

EXPERT OPINION

Available evidence of a potential detrimental effect in elderly PLWH is limited by study design and small sample sizes. Careful consideration of undoubtful benefits and potential harms is advised when prescribing ARVs to geriatric patients and the knowledge of pharmacokinetics changes need to be included in the process. With the 'greying' of the pandemic we need studies with a specific focus on geriatric patients living with HIV that will consider specific phenotypes and associated changes (including sarcopenia).

Calcaneal Quantitative Ultrasonography and Urinary Retinol-Binding Protein in Antiretroviral-Treated Patients With Human Immunodeficiency Virus in Uganda: A Pilot Study

BACKGROUND

Data on bone health and renal impairment in people with human immunodeficiency virus (HIV) in resource-limited settings are limited. The primary aim of this study was to investigate the potential role of calcaneal quantitative ultrasonography (QUS) in predicting bone mineral density (BMD) reduction in a population of Ugandan HIV-infected  individuals receiving long-term antiretroviral therapy; the secondary end point was to assess the prevalence of proximal tubular dysfunction and the correlation between elevated urinary retinol-binding protein-urinary creatinine ratio (uRBP/uCr) and reduced BMD.

METHODS

We conducted a cross-sectional study at the Infectious Diseases Institute, Kampala, Uganda. We included 101 HIV-infected adults who had been receiving continuous antiretroviral therapy for ≥10 years and had undergone dual-energy x-ray absorptiometry (DXA) during the previous 12 months. All patients underwent calcaneal QUS evaluation and urine sample collection.

RESULTS

DXA BMD measurements were significantly associated (P < .01) with calcaneal speed of sound, broadband ultrasound attenuation, and QUS index. Forty-seven individuals (47%) had abnormal uRBP/uCr values. A significant inverse correlation was observed between uRBP/uCr and DXA T scores (lumbar [P = .03], femoral neck [P < .001], and total hip [P = .002]).

CONCLUSIONS

Calcaneal QUS results showed a moderate correlation with DXA outputs. The identified high prevalence of subclinical tubular impairment also highlights the importance of expanding access to tenofovir disoproxil fumarate-sparing regimens in resource-limited settings.

Planning HIV therapy to prevent future comorbidities: patient years for tenofovir alafenamide

Since the introduction of suppressive antiretroviral therapy (ART), HIV has become a chronic disease, with infected people in high-income countries approaching similar life expectancy to the general population. As this population ages, an increasing number of people with HIV are living with age-, treatment-, and disease-related comorbidities. Lifestyle factors such as smoking, alcohol abuse, and substance misuse have a role in age-related comorbidity. Some degree of immune dysfunction is suggested by the presence of markers of immune activation/inflammation despite effective suppression of HIV replication. Cumulative exposure to some antiretroviral drugs contributes to HIV-associated comorbidities, with risk increasing with age. Specifically, tenofovir disoproxil fumarate (TDF), ritonavir-boosted atazanavir, and ritonavir-boosted lopinavir are associated with renal impairment, and TDF is known to cause loss of bone mineral density. Tenofovir alafenamide (TAF) was developed to improve on the safety profile of TDF, while maintaining its efficacy. TAF has better stability in plasma, and higher intracellular accumulation of tenofovir diphosphate in target cells, which has resulted in improved antiviral activity at lower doses with improved renal and bone safety. TAF has been studied extensively in randomized clinical trials and real-world studies. TAF-based regimens are recommended over TDF-containing regimens for the improved safety profile.

Pharmacogenetic determinants of kidney-associated urinary and serum abnormalities in antiretroviral-treated HIV-positive patients

Tenofovir disoproxyl fumarate (TDF) has been associated with renal tubular abnormalities, phosphaturia and proteinuria (retinol binding protein, RBP, loss): vitamin D (VD) and PTH affect these markers. Aim was to understand if some single nucleotide polymorphisms (SNPs) were predictors of renal abnormalities in an Italian cohort of HIV-affected patients. DNA was analyzed through real-time PCR, urinary RBP corrected by creatinine (uRBP/Cr). The majority of patients received TDF. Abnormal uRBP/Cr was more frequent in TDF recipients: eGFR <90 mL/min and TDF were predictors in the whole cohort, whereas eGFR <90 mL/min, TDF concentrations and CYP24A1-3999TT in TDF-treated patients. Phosphate levels were higher low VD level patients: age <50 years, CYP27B1 + 2838CC genotype and non-European ancestry were predictors. PTH levels were border-line higher in TDF patients: non-European ancestry, females, TDF, VD levels < 30 ng/mL and SLC28A2-124CT/TT and ABCC2-24CC were predictors. For the first time, SNPs were associated with PTH, phosphate, calcium and tubular dysfunction in HIV-infected patients.

Brief Report: Adherence Biomarker Measurements in Older and Younger HIV-Infected Adults Receiving Tenofovir-Based Therapy

BACKGROUND

Concentrations of tenofovir (TFV) in hair and tenofovir diphosphate (TFV-DP) in dried blood spots (DBSs) as measures of cumulative exposure have been primarily studied in younger, HIV-uninfected individuals taking preexposure HIV prophylaxis. Data on these measures among older HIV-infected individuals are limited.

METHODS

We evaluated longitudinal TFV and TFV-DP concentrations in hair and DBS, respectively, from HIV-infected adults. Multivariable model variables included age group (18-35 and 60 years and older), creatinine clearance (CrCl), hematocrit (TFV-DP), and gray hair color (TFV).

RESULTS

Baseline hair TFV and DBS TFV-DP were moderately correlated [r = 0.5 (0.2 to 0.7); P = 0.001] across both age groups [younger (N = 23) and older (N = 22)]. In adjusted models, CrCl was associated with increases of 15.9% (7.4% to 25.0%); P = 0.0006, and 5.7% (-0.2% to 11.9%); P = 0.057 for TFV in hair and TFV-DP in DBS, respectively, for every 20-mL/min CrCl decrease. Although older age (versus younger age) was univariately associated with increased TFV hair levels, older age was not significantly associated with higher concentrations in hair [-1.4% (-26.7% to 32.7%); P = 0.93] or DBS [4.0% (-14.1% to 25.9%); P = 0.68] after adjustment. Similarly, gray color was not significantly associated with higher TFV levels in hair [27.6% (-11.1% to 83.0%; P = 0.18)] in adjusted models. In both adjusted and unadjusted models of TFV-DP levels in DBS, a 1% hematocrit increase was associated with a 3.3% (0.2% to 6.5%) TFV-DP increase (P = 0.04).

CONCLUSIONS

Cumulative drug exposure measures (hair and DBS) were comparable in younger and older HIV-infected individuals on TFV-based therapy after adjustment for renal function.

Tenofovir disoproxil fumarate discontinuation for renal outcomes: any room for treatment personalization?

Tenofovir disoproxil fumarate (TDF) is a very effective antiviral drug that has been associated with tubular dysfunction. The aim of this study was to analyze the demographic, pharmacokinetic, and pharmacogenetic variables associated with TDF discontinuation for renal outcomes in stable HIV-positive patients using multivariable analyses. Three hundred and four patients were included (73% male, with median age and eCrCl of 45.3 years and 90.9 mL/min, respectively). After a median follow-up of 28.3 months, 27 patients discontinued TDF for renal adverse events [persistent urinary abnormalities (n = 21) or eCrCl < 60 mL/min (n = 6)] providing an incidence of 3.77 events per 100 patient-year. The probability of TDF discontinuation was higher with several features (male gender, older age, not Caucasians ancestry, absence of intravenous drug abuse, protease inhibitors, previous indinavir, HCV-positivity, lower CD4 cell count, detectable HIV-RNA, lower eCrCl, spot-urine proteinuria) and higher tenofovir concentrations but not genetic variants. Tenofovir plasma concentrations were prognostic of TDF discontinuation for renal adverse events suggesting that dose-adjustment may be warranted for long-term safety.

Precision medicine for HIV: where are we?

To date, antiretroviral therapy is highly effective in HIV-affected patients, but the individualization of such a life-long therapy may be advised. This review briefly summarizes the main factors involved in the potential personalization of antiretroviral treatment. Relevant articles in English were identified by PubMed and recent congresses’ abstracts. Foremost influences concerning pharmacodynamics, therapeutic drug monitoring, pharmacogenetics, comorbidities, immune recovery and viral characteristics affecting the healthcare of HIV-positive patients are listed here. Furthermore, pharmacoeconomic aspects are mentioned. Applying pharmacokinetic and pharmacogenetic knowledge may be informative and guide the better choice of treatment in order to achieve long-term efficacy and avoid adverse events. Randomized investigations of the clinical relevance of tailored antiretroviral regimens are needed in order to obtain a better management of HIV/AIDS-affected patients.

Genetic Polymorphisms Affecting the Pharmacokinetics of Antiretroviral Drugs

BACKGROUND

Antiretroviral treatment is highly effective in enhancing HIV-positive patients' survival and quality of life. Despite an increased tolerability in recent years, a substantial amount of patients experience side effects. Antiretrovirals' efficacy and tolerability have been associated with plasma concentrations and single nucleotide polymorphisms in selected genes involved in drug disposition.

OBJECTIVE

Our aim was to review the current knowledge in genetic polymorphisms affecting plasma, intracellular or compartmental concentrations of antiretrovirals.

METHODS

A search of the PubMed database was conducted to identify relevant articles, using the following terms: 'pharmacogenetics' or 'pharmacogenomics' or 'single nucleotide polymorphisms' or 'genetic/allelic variants' and 'pharmacokinetics' or 'concentrations' and 'HIV' or 'antiretroviral'. Abstracts from the main HIV conferences during 2015 and 2016 were also searched using the same keywords. Abstracts were manually checked and, if relevant, full papers were obtained. Only articles published in English were selected.

RESULTS

Several genetic polymorphisms in genes coding enzymes involved in drug metabolism (cytochrome P450 isoenzymes and uridine diphosphate glucuronosyltransferases) and transport (P-glycoprotein, anionic and cationic transporters, other transporters), as well as nuclear receptors (pregnane X receptor and the constitutive androstane receptor), have been associated with concentrations of antiretrovirals. The extent of such influence, the conflicting data, and the potential clinical relevance are discussed in the main section of this article.

CONCLUSION

Genetic polymorphisms may affect antiretroviral disposition, as well as both efficacy and toxicity. Despite a large amount of data, such precious knowledge has seldom been applied in patients. Studies on the clinical relevance and cost effectiveness of tailoring antiretroviral regimens to patients' genetic assets are lacking, but their importance may grow with the increasing age and complexity of persons living with HIV/AIDS.

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.