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Kidney tubular abnormalities in the absence of impaired glomerular function in HIV patients treated with tenofovir.

Background:Tenofovir (TDF) is the most widely prescribed antiretroviral drug. Kidney abnormalities are the main concern using the drug. As glomerular function is infrequently affected in patients treated with TDF, herein, we report the results of an extensive examination of tubular function. Methods:Cross-sectional study of plasma and 24 h urine markers of kidney tubulopathy (glucosuria, hyperaminoaciduria, hyperphosphaturia, hyperuricosuria and β2-microglobulinuria) could be allocated in three groups: patients under a TDF-containing HAART; patients on HAART never exposed to TDF; and antiretroviral-naive individuals. Significant tubular damage was defined when at least two of these parameters were repeatedly present, being at least one part of the Fanconi syndrome criteria (glucosuria, hyperaminoaciduria and hyperphosphaturia). Glomerular function was assessed using creatinine clearance. Results:A total of 284 consecutive HIV patients were examined, 154 on TDF, 49 on other HAART regimens and 81 drug-naive. No significant differences in creatinine clearance were observed when comparing distinct groups. The proportion of patients with tubular damage in groups 1, 2 and 3 were 22, 6 and 12%, respectively. In a multivariate analysis [odds ratio (OR) {95% confidence interval (CI)} P], the only independent predictors of tubular dysfunction were TDF use (21.6, 4.1–113, <0.001) and older age (1.1 per year, 1.0–1.1, 0.01). Conclusion:Exposure to TDF is associated with an increased risk over time of kidney tubular abnormalities in the absence of significant impaired glomerular function. Although long-term consequences of this tubulopathy are unknown, close monitoring of accelerated bone mineral loss and renal insufficiency are warranted. Periodic screening of tubular function parameters should be recommended to patients receiving TDF.

Viral hepatitis and HIV co-infection.

Chronic hepatitis B virus (HBV) infection is overall recognised in 10% of HIV+ persons worldwide, with large differences according to geographical region. Chronic hepatitis C virus (HCV) infection affects 25% of HIV+ individuals, with greater rates ( approximately 75%) in intravenous drug users and persons infected through contaminated blood or blood products. HIV-hepatitis co-infected individuals show an accelerated course of liver disease, with faster progression to cirrhosis. The number of anti-HBV drugs has increased in the last few years, and some agents (e.g. lamivudine, emtricitabine, tenofovir) also exert significant activity against HIV. Emergence of drug resistance challenges the long-term benefit of anti-HBV monotherapy, mainly with lamivudine. The results using new more potent anti-HBV drugs (e.g. tenofovir) are very promising, with prospects for stopping or even revert HBV-related liver damage in most cases. With respect to chronic hepatitis C, the combination of pegylated interferon plus ribavirin given for 1 year permits to achieve sustained HCV clearance in no more than 40% of HIV-HCV co-infected patients. Thus, new direct anti-HCV drugs are eagerly awaited for this population. Although being a minority, HIV+ patients with delta hepatitis and those with multiple hepatitis show the worst prognosis. Appropriate diagnosis and monitoring of chronic viral hepatitis, including the use of non-invasive tools for assessing liver fibrosis and measurement of viral load, may allow to confront adequately chronic viral hepatitis in HIV+ patients, preventing the development of end-stage liver disease, for which the only option available is liver transplantation. This article forms part of a special issue of Antiviral Research marking the 25th anniversary of antiretroviral drug discovery and development, Vol 85, issue 1, 2010.

Hepatotoxicity of Antiretroviral Drugs Is Reduced after Successful Treatment of Chronic Hepatitis C in HIV-Infected Patients

BACKGROUND The risk of liver toxicity during antiretroviral drug use in human immunodeficiency virus (HIV)-positive patients increases in the presence of chronic hepatitis C virus (HCV) infection. It is unknown whether sustained HCV clearance after interferon (IFN)-based therapy might reduce this complication. METHODS The incidence of severe elevations in liver enzyme levels during antiretroviral therapy was retrospectively analyzed in a group of HIV/HCV-coinfected patients after completion of a full course of IFN-based therapy. Hepatic events were recorded according to the achievement of a sustained virological response (SVR), and the presence of advanced liver fibrosis was assessed by transient elastometry. RESULTS A total of 132 HIV/HCV-coinfected patients were analyzed (66% men; mean age, 38 years). Overall, 33% achieved an SVR and 40% had advanced liver fibrosis after IFN therapy. A total of 49 episodes of liver toxicity occurred during a mean of 35 months of follow-up (9.7% per year) after IFN therapy. The yearly incidence of hepatic events was greater in patients who did not achieve an SVR than in those who did (12.9% vs. 3.1%; P<.001) and in patients with advanced liver fibrosis than in those without it (14.4% vs. 7.6%; P=.003). Drugs involved in hepatic events were dydeoxynucleoside analogues (namely, didanosine and stavudine; 40%) nevirapine (30%), efavirenz (11%), and protease inhibitors (PIs; 8%). In logistic regression analysis, lack of an SVR (odds ratio [OR], 6.13 [95% confidence interval {CI}, 1.83-37.45]; P=.003) and the use of dydeoxynucleosides (OR, 3.59 [95% CI, 1.23-10.42]; P=.02) were independent predictors of hepatotoxicity after IFN therapy. Conversely, regimens containing PIs (OR, 0.07 [95% CI, 0.02-0.30]; P<.01) or efavirenz (OR, 0.13 [95% CI, 0.04-0.44]; P=.001) were associated with a diminished risk of hepatic events. CONCLUSION Sustained HCV clearance after IFN-based therapy reduces the risk of liver toxicity during antiretroviral therapy, which should further encourage the treatment of chronic hepatitis C in HIV-coinfected patients. In this population, prescription of PIs or efavirenz decreases and use of dydeoxynucleoside analogues increases the risk of hepatotoxicity.

Natural pregnancies in HIV-serodiscordant couples receiving successful antiretroviral therapy

Summary:Increasing numbers of HIV-serodiscordant heterosexual couples are concerned about the chances for pregnancy. We reviewed all natural pregnancies attained by HIV-serodiscordant couples seen in 3 clinics in Spain, in which the infected partner had undetectable plasma viremia while receiving highly active antiretroviral therapy (HAART). In the case of HIV-infected mothers, only those with undetectable viremia during pregnancy and at delivery were chosen. A total of 62 HIV-serodiscordant couples, 22 HIV-infected women (mean CD4 count of 522 cells/μL, 55% hepatitis C virus [HCV]-seropositive) and 40 HIV-infected men (mean CD4 count of 629 cells/μL, 75% HCV-seropositive), were recorded. Overall, 76 natural pregnancies occurred, and 68 children were born. There were 9 fetal deaths, 1 twin pregnancy, 6 couples with 2 consecutive babies, and 4 couples with 3 consecutive newborns. There were no cases of HIV seroconversion in uninfected sexual partners. One case of vertical HIV transmission occurred, however. Serodiscordant couples attaining natural pregnancy are exposed to a negligible risk of sexual transmission of HIV when the infected partner presents with complete suppression of plasma viremia while receiving HAART.

Impairment in kidney tubular function in patients receiving tenofovir is associated with higher tenofovir plasma concentrations.

Tenofovir (TFV) is a nucleotide analogue active against HIV and hepatitis B virus. Although TFV rarely affects the glomerular function, abnormalities in the kidney tubular function appear to be quite common. The relationship between TFV exposure and kidney tubular dysfunction (KTD) was examined prospectively in 92 HIV-infected individuals. Median TFV plasma trough concentration was higher in patients with KTD than in the rest (182 vs. 106 ng/ml; P = 0.001). This dose-dependent effect further supports an involvement of TFV in KTD.

Liver cirrhosis in HIV-infected patients: prevalence, aetiology and clinical outcome

Summary.  Liver disease is frequently seen in HIV+ patients as a result of coinfection with hepatitis B (HBV) or C (HCV) viruses, alcohol abuse and/or exposure to hepatotoxic drugs. The aim of this study was to assess the prevalence of liver cirrhosis, its main causes and clinical presentation in HIV+ patients. Observational, cross‐sectional, retrospective study of all HIV+ individuals followed at one reference HIV outpatient clinic in Madrid. Liver fibrosis was measured in all cases using transient elastometry (FibroScan®). All 2168 HIV+ patients on regular follow‐up (76% males, 46% injecting drug users) were successfully examined by FibroScan® between October 2004 and August 2006. Liver cirrhosis was recognized in 181 (overall prevalence, 8.3%), and the main aetiologies were HCV, 82.3%; HBV, 1.6%; dual HBV/HCV, 2.8%; and triple HBV/HCV/ hepatitis delta virus (HDV) infection, 6.6%. The prevalence of cirrhosis differed among patients with distinct chronic viral hepatitis: HCV, 19.2%; HBV, 6.1%; HBV/HCV, 41.7%; and HBV/HCV/HDV, 66.7%. In 12 patients with cirrhosis (6.7%), no definite aetiology was recognized. Overall, cirrhotics had lower mean CD4 counts than noncirrhotics (408 vs 528 cells/μL respectively; P = 0.02), despite similar proportion of subjects with undetectable viraemia on highly active antiretroviral therapy. Clinical manifestations of liver cirrhosis were: splenomegaly, 61.5%; oesophageal varices, 59.8%; ascites, 22.6%; encephalopathy, 12.1%; and variceal bleeding, 6.1%. Liver cirrhosis and hepatic decompensation events are relatively frequent in HIV+ individuals. Chronic HCV and alcohol abuse, but not chronic HBV, play a major role. Transient elastometry may allow the identification of a significant number of HIV+ individuals with asymptomatic liver cirrhosis.

Renal toxicity associated with tenofovir use

Importance of the field: Tenofovir (TFV) is a nucleotide analogue widely used for the treatment of HIV infection. Despite its proven efficacy and safety, cases of kidney tubular dysfunction have increasingly been reported and concern exists about the risk of nephrotoxicity associated with the long-term use of TFV. Areas covered in this review: Evidences about the renal toxicity associated with TFV use as well as predictors are examined. The most relevant publications assessing TFV safety and those which have reported cases of tubular dysfunction were identified and carefully revised. What the reader will gain: Renal damage of clinical significance caused by TFV is uncommon in the short-mid-term. It occurs more frequently in subjects with underlying kidney conditions. TFV primarily results in kidney tubular dysfunction and less frequently in glomerular abnormalities. Kidney damage may progress over time under long-term TFV exposure but is reversible in most cases on drug discontinuation. Take home message: Severe renal damage associated with TFV use is uncommon and of multifactorial origin. However, mild tubular dysfunction is recognized in a substantial proportion of TFV-treated individuals and tends to increase with cumulative exposure.

Genetic Variants of ABCC10, a Novel Tenofovir Transporter, Are Associated With Kidney Tubular Dysfunction

BACKGROUND Tenofovir (TFV) causes kidney tubular dysfunction (KTD) in some patients, but the mechanism is poorly understood. Genetic variants in TFV transporters are implicated; we explored whether ABCC10 transports TFV and whether ABCC10 single-nucleotide polymorphisms (SNPs) are associated with KTD. METHODS TFV accumulation was assessed in parental and ABCC10-transfected HEK293 cells (HEK293-ABCC10), CD4(+) cells and monocyte-derived macrophages (MDMs). Substrate specificity was confirmed by cepharanthine (ABCC10 inhibitor) and small interfering RNA (siRNA) studies. Fourteen SNPs in ABCC10 were genotyped in human immunodeficiency virus-positive patients with KTD (n = 19) or without KTD (controls; n = 96). SNP and haplotype analysis was performed using Haploview. RESULTS TFV accumulation was significantly lower in HEK293-ABCC10 cell lines than in parental HEK293 cells (35% lower; P = .02); this was reversed by cepharanthine. siRNA knockdown of ABCC10 resulted in increased accumulation of TFV in CD4(+) cells (18%; P = .04) and MDMs (25%; P = .04). Two ABCC10 SNPs (rs9349256: odds ratio [OR], 2.3; P = .02; rs2125739, OR, 2.0; P = .05) and their haplotype (OR, 2.1; P = .05) were significantly associated with KTD. rs9349256 was associated with urine phosphorus wasting (P = .02) and β2 microglobulinuria (P = .04). CONCLUSIONS TFV is a substrate for ABCC10, and genetic variability within the ABCC10 gene may influence TFV renal tubular transport and contribute to the development of KTD. These results need to be replicated in other cohorts.

Paradoxical CD4+ T-cell decline in HIV-infected patients with complete virus suppression taking tenofovir and didanosine.

Background: Tenofovir (TDF) and didanosine (ddI) are both adenosine analogues with convenient posology, strong potency and a relatively high genetic barrier for resistance. The popularity of this combination, however, has been questioned due to concerns about pharmacokinetic interactions and increased risk of pancreatitis and hyperglycemia. Less information is available about other possible side effects. Patients and methods: HIV-infected individuals who initiated a protease inhibitor-sparing regimen between September 2002 and June 2003 at five hospitals, and had at least one subsequent visit within the next 12 months, always with complete virus suppression, were retrospectively assessed. Only drug-naive individuals and patients who simplified a prior successful antiretroviral regimen were analysed. Results: Outcomes were analysed in 570 individuals according to treatment modality (98 drug-naive versus 472 simplified); the nucleoside analogue (NA) backbone (298 with TDF + ddI, 88 with ddI, 44 with TDF, and 140 with neither ddI nor TDF); and the third agent used (378 with non-nucleoside analogues versus 192 with NA). Significant CD4+ T-cell declines were seen in patients taking ddI + TDF with respect to all other NA combinations, including ddI or TDF separately. Patients exposed to high ddI doses or taking a third NA showed more pronounced CD4 declines. Plasma levels of ddI correlated with the extent of CD4+ T-cell loss. Conclusion: Patients receiving ddI + TDF-based combinations show CD4+ T-cell declines despite achieving complete virus suppression. This effect generally progresses with time. An imbalance in adenosine metabolites within CD4+ T lymphocytes may explain this phenomenon, which resembles the genetic purine nucleoside phosphorylase deficiency syndrome.

Directly acting antivirals against hepatitis C virus

The approval of directly acting antivirals (DAA) for the treatment of chronic hepatitis C virus (HCV) infection will represent a major breakthrough for the 180 million persons infected worldwide. Paradoxically, hepatitis C is the only human chronic viral disease that can be cured, as all other pathogenic viruses infecting humans either display self-limited courses or establish non-eradicable persistent infections. Until now, treatment of chronic hepatitis C consisted of the combination of peginterferon-α plus ribavirin, which provided limited rates of cure and was associated with frequent side effects. Several DAA have been identified that inhibit the NS3 protease, the NS5B polymerase or the NS5A replication complex, and have entered the final steps of clinical development. These molecules, coupled with significant progress made in the recognition of more potent and safe interferon forms (e.g. interferon-λ) and host protein targets (e.g. alisporivir), are opening a new era in hepatitis C therapeutics. The expectations are so great that, to some extent, it is reminiscent of what happened in 1996 in the HIV field when the introduction of the first protease inhibitors as part of triple combinations revolutionized antiretroviral therapy. To maximize treatment success and reduce the likelihood of drug resistance selection, a proper individualization of hepatitis C therapy will be required, choosing the most convenient drugs and strategies according to distinct viral and host profiles. The complexity of HCV therapeutics has reached a point that presumably will lead to the birth of a new specialist, the HCV doctor.