First-line therapy and mitochondrial damage: different nucleosides, different findings

Oxidative mitochondrial DNA damage in peripheral blood mononuclear cells is associated with reduced volumes of hippocampus and subcortical gray matter in chronically HIV-infected patients

Cross-sectional relationships were examined between regional brain volumes and mitochondrial DNA (mtDNA) 8-hydroxy-2-deoxyguanosine (8-oxo-dG) in peripheral blood mononuclear cells (PBMCs) of 47 HIV patients [mean age 51years; 81% with HIV RNA ≤50copies/mL] on combination antiretroviral therapy. The gene-specific DNA damage and repair assay measured mtDNA 8-oxo-dG break frequency. Magnetic resonance imaging was performed at 3T. Higher mtDNA 8-oxo-dG was associated with lateral ventricular enlargement and with decreased volumes of hippocampus, pallidum, and total subcortical gray matter, suggesting the involvement of systemic mitochondrial-specific oxidative stress in chronic HIV-related structural brain changes and cognitive difficulties. Clarification of the mechanism may provide potential therapeutic targets.

Fatigue-related gene networks identified in CD(14)+ cells isolated from HIV-infected patients: part I: research findings

PURPOSE

Human immunodeficiency virus (HIV)-related fatigue (HRF) is multicausal and potentially related to mitochondrial dysfunction caused by antiretroviral therapy with nucleoside reverse transcriptase inhibitors (NRTIs).

METHODOLOGY

The authors compared gene expression profiles of CD14(+) cells of low versus high fatigued, NRTI-treated HIV patients to healthy controls (n = 5/group). The authors identified 32 genes predictive of low versus high fatigue and 33 genes predictive of healthy versus HIV infection. The authors constructed genetic networks to further elucidate the possible biological pathways in which these genes are involved. RELEVANCE FOR NURSING PRACTICE: Genes including the actin cytoskeletal regulatory proteins Prokineticin 2 and Cofilin 2 along with mitochondrial inner membrane proteins are involved in multiple pathways and were predictors of fatigue status. Previously identified inflammatory and signaling genes were predictive of HIV status, clearly confirming our results and suggesting a possible further connection between mitochondrial function and HIV. Isolated CD14(+) cells are easily accessible cells that could be used for further study of the connection between fatigue and mitochondrial function of HIV patients.

IMPLICATION FOR PRACTICE

The findings from this pilot study take us one step closer to identifying biomarker targets for fatigue status and mitochondrial dysfunction. Specific biomarkers will be pertinent to the development of methodologies to diagnosis, monitor, and treat fatigue and mitochondrial dysfunction.

Causes of death in pediatric patients vertically infected by the human immunodeficiency virus type 1 in Madrid, Spain, from 1982 to mid-2009

BACKGROUND

Effective therapies have increased life expectancy of human immunodeficiency virus (HIV)-infected pediatric patients. We investigated the underlying causes of death, mortality, and acquired immune deficiency syndrome (AIDS) rates in HIV-infected pediatric patients in Madrid, Spain.

METHODS

We studied a multicenter cohort of 478 HIV-infected pediatric patients in Madrid. Mortality and AIDS incidence rates, causes of death, CD4 T-cell, and HIV RNA were analyzed during calendar periods (CPs): pre-HAART (highly active antiretroviral therapy) (CP1: 1982-1996) and post-HAART era (CP2: 1997-2009).

RESULTS

During 5690 person-years of follow-up 157 (32.8%) deaths occurred. Median age at death increased (CP1: 3.2 years [1.0-6.3] vs. CP2: 7.7 years [3.1-11.4]; P < 0.01). Mortality and AIDS rates decreased 10.6-fold (95% confidence intervals [CI]: 6.9-16.7) and 6.9-fold (95% CI: 5.0-9.6), respectively, between CPs. Nevertheless, mortality was 10.4-fold (95% CI: 5.8-18.8; P < 0.001) higher than in age-similar general population in late-CP2. In all, 169 causes of death were reported. Multiple causes were reported in 16 of 151 (10.6%) patients. In 81.1% (137/169), the causes were AIDS-defining, 11.8% (20/169) HIV-related, and 7.1% (12/169) non-HIV-related. Infections were the leading causes (60.8%, 101/166); from 1999 to 2007 the risk of death from infections was 115.9 times (95% CI: 42.0-265.8; P < 0.001) higher than in the age-similar general population. Comorbidity was reported in 66.9% (101/151) of patients. Median HIV-1 RNA at death decreased (CP1: 5.9 [5.0-6.3]; CP2: 5.3 [4.2-5.8]; P < 0.01).

CONCLUSIONS

Despite decline in mortality and AIDS rates, it is important to monitor all causes of death as prolonged survival might allow underlying comorbidity to become more clinically relevant.

Pediatric antiretroviral therapy

The rate of perinatal HIV transmission has decreased significantly in developed countries. However, worldwide, it remains the main source of HIV infection within the pediatric population. Recent advances as a result of findings from clinical trials, viral resistance testing and the advent of new drugs have increased the options for initial treatment regimens. This article provides an overview of antiretroviral therapy in treatment-naive children, including recent pediatric data and updated guidelines from the NIH. It also provides information on new drugs approved for the pediatric age group, dosage information, drug resistance testing and monitoring suggestions for children and adolescents receiving antiretroviral therapy. Special issues pertaining to adherence, disclosure and contraception are also highlighted.

Metabolic abnormalities and coronary heart disease risk in human immunodeficiency virus-infected adults

BACKGROUND

Metabolic syndrome is a combination of risk factors for cardiovascular disease and diabetes, It has been reported to be increased in human immunodeficiency virus (HIV)-infected individuals.

METHODS

In a cohort of HIV-infected adults we examined parameters that contribute to defining the metabolic syndrome and to estimating the 10-year risk of coronary heart disease (CHD). The study group consisted of 296 participants (217 men and 79 women) of mixed ethnicity with a mean age of 45.3 years.

RESULTS

There was an appreciable prevalence of metabolic syndrome (30.0%), with the frequency increasing to 42.5% in those over 50 years of age. Those with the metabolic syndrome had a lower viral load. More women had abdominal obesity (59.5%) than men (20.7%, P < 0.001). The frequency of elevated plasma glucose was higher in females (37.2%) compared to males (16.9%, P = 0.004). High frequencies of decreased high-density lipoprotein cholesterol (HDL-C) and elevated blood pressure were seen in both sexes. Hypertriglyceridemia was less prevalent in African Americans. In those under 50 years of age, the 10-year CHD risk score for men was double that for women (6.2% vs 2.7%, P < 0.001). In older participants, the risk was similar between the sexes, with a third having scores over 10%.

CONCLUSIONS

The prevalence of metabolic syndrome was higher than in most other HIV cohorts. Those with the syndrome had significantly lower viral loads. Mean 10-year Framingham Cardiovascular Risk (FCR) scores were nearly doubled for those with metabolic syndrome. Both researchers and clinicians should consider age as well as sex when assessing patients with HIV infection for risks associated with metabolic syndrome.

Toxicities associated with dual nucleoside reverse-transcriptase inhibitor regimens in HIV-infected children

BACKGROUND

Human immunodeficiency virus (HIV) therapy includes a backbone of nucleoside reverse-transcriptase inhibitors (NRTIs). Toxicities associated with NRTIs are not fully defined in children.

METHODS

We studied 2233 children < or =13 years of age who were perinatally infected with HIV and were receiving > or =2 NRTIs, to determine the relative toxicities of the 5 most common NRTI pairs: zidovudine (ZDV)/lamivudine (3TC), ZDV/didanosine (ddI), stavudine (d4T)/3TC, d4T/ddI, and ddI/3TC. Incidence rates for clinical and laboratory toxicities were estimated, and NRTI pairs were compared with regard to the time to the first toxicity.

RESULTS

The most common clinical toxicities noted were hepatitis, peripheral neuropathy, lipodystrophy/lipoatrophy, and pancreatitis, whereas the most common laboratory toxicities were an elevated anion gap, an increased total amylase level, neutropenia, and thrombocytopenia. Overall, regimens containing ZDV were associated with a significantly lower rate of clinical toxicities than were those containing d4T (adjusted hazard ratio [HR], 0.49; P = .02) ); regimens containing ddI were associated with a significantly lower rate of laboratory toxicities than were those containing 3TC (adjusted HR, 0.78; P = .04). ZDV/3TC was associated with a lower rate of clinical toxicities than were d4T/ddI and ddI/3TC and with a higher rate of laboratory toxicities than was ZDV/ddI. ZDV/ddI was associated with a lower rate of clinical toxicities than was d4T/3TC.

CONCLUSIONS

In children, regimens containing ZDV have less toxicity than do those containing d4T, thereby supporting their use in first-line regimens. D4T/3TC, d4T/ddI, and ddI/3TC have similar toxicity rates and are appropriate for second-line therapy.

Trends in the prescription of antiretroviral drugs and impact on plasma HIV-RNA measurements

BACKGROUND

The choice of antiretroviral drugs has evolved over the last decade. Recognition of trends and determinants of changes may help to make predictions on prescription patterns.

METHODS

Longitudinal analyses were performed every 6 months from 1996 to 2006, of all HIV-infected individuals who attended at one HIV/AIDS referral centre located in Madrid, Spain.

RESULTS

A total of 2602 different individuals attending during the study period were examined over 23 consecutive time-points. The number and proportion of patients under antiretroviral therapy significantly increased in the period 1996-99, with a plateau since then around 1100 patients, which represented around two-thirds of the patients seen at each time-point after the year 2000. The proportion of patients under antiretroviral therapy having undetectable viraemia significantly increased from 34.5% in 1996 to 80% in 2006. The relative use of nucleoside reverse transcriptase inhibitors (NRTIs) and protease inhibitors (PIs) has risen in recent years, while prescription of non-nucleoside reverse transcriptase inhibitors has declined compared with the period 1999-2001, when it peaked. Among NRTIs, the use of zalcitabine, stavudine and didanosine has dramatically declined or vanished, while zidovudine, lamivudine, abacavir and tenofovir have gained relevance. Among PIs, indinavir and nelfinavir have almost disappeared, being replaced by ritonavir-boosted PIs, mainly atazanavir and lopinavir. After its first introduction in the year 1999, efavirenz has been generally preferred over nevirapine.

CONCLUSIONS

The choice of antiretroviral drugs has evolved during the last decade, with safety and convenience issues driving most changes in prescription patterns, while antiviral success has dramatically increased.

Nucleoside and nucleotide reverse transcriptase inhibitors in children

By the end of 2006, approximately 2.3 million children worldwide were living with HIV infection, representing about 15% of all HIV-infected individuals but only 5-7% of the total population of treated patients worldwide. Despite a general increase in the use of antiretroviral therapy (ART) in resource-limited settings, appropriate care and ART remain inaccessible for most of the world's HIV-infected children. ART of children is challenging because of a general lack of paediatric formulations (including tablets in paediatric strengths), limited options of drugs available for children (some have been approved only for use in adults), different viral and immunological responses, dependency on caregivers for administration of the therapy, and specific issues of toxicity in long-term therapy related to maturation and development. As in adults, nucleoside reverse transcriptase inhibitors (NRTIs) are a key component of any ART schedule in children, being the recommended 'backbone' treatment in US, European and WHO guidelines, and, indeed, NRTIs have been extensively studied in children. NRTIs are the class of antiretroviral drugs that have more drugs licensed for paediatric use and more paediatric formulations.Generally, the dual NRTI backbone treatment of combination with a non-NRTI (NNRTI) or protease inhibitor (PI) should comprise a cytidine analogue (lamivudine, emtricitabine) and a thymidine analogue (stavudine, zidovudine), guanosine analogue (i.e. abacavir), or nucleotide RTI (NtRTI; i.e. tenofovir). European and US guidelines recommend the use of triple NRTI therapy (abacavir/lamivudine/zidovudine) in children with anticipated poor adherence to other treatment regimens because of tablet burden. In conclusion, while use of ART in children needs to be dramatically increased, selecting and administering the best drug combination for children is still limited by a lack of paediatric formulations and knowledge of drug metabolism, safety and efficacy in children. NRTIs are already a key component of paediatric ART, but fixed-dose combinations and specific research in children are needed to optimise their use. In this article we review the available information to facilitate selection of the best NRTI for backbone treatment in combination ART for HIV-infected children.

Tratamiento antirretroviral y toxicidad mitocondrial

The introduction of highly active antiretroviral therapy for the treatment of human immunodeficiency virus (HIV) infection has led to substantial reduction in morbidity and near-complete suppression of HIV-1 replication. This progress has been tempered by a growing number of new adverse effects. Mitochondrial toxicity is one aspect of these long-term toxicities of antiretroviral drugs, with the role of nucleoside analogs being particularly underlined. Some cases of impaired mitochondrial function have been clearly identified, such as pancreatitis, neuropathy, miopathy and lactic acidosis. Beyond the inhibition of DNA polymerase-g using nucleoside analogs, it appears that several physiopathologic mechanisms interact to explain the observed toxicity. At present there is no reliable method to detect subclinical mitochondrial toxicity. There is no proven effective therapy for antiretroviral therapy-associated mitochondrial toxicity other than ceasing the implicated agent, and even with this strategy, resolution of symptoms may be incomplete. Therefore, investigation of mitochondrial toxicity of new compounds or new combinations is of growing interest for the clinical application of antiretroviral agents.

Interruption of combination antiretroviral therapy and risk of clinical disease progression to AIDS or death

OBJECTIVES

The aim of the study was to compare incidence rates (IRs) of AIDS/death in patients with and without treatment interruption (TI) of combination antiretroviral therapy (cART) for periods of 3 months or more for different categories of CD4 cell count and viral load, and to determine risk factors for clinical progression to AIDS/death.

METHODS

Patients starting cART with a CD4 cell count and a viral load available within 6 months of starting cART were included in the study. The IR and risk factors of TI were determined. We assessed the incidence rate ratios (IRRs) for TI and AIDS/death events using Poisson regression models.

RESULTS

Of 3811 patients included in the study, 26% were ART-naïve prior to cART. The median date of starting cART was July 1997, the median CD4 cell count was 226 cells/microL and the median viral load was 4.36 log(10) HIV-1 RNA copies/mL. We observed 1243 interruptions and 403 AIDS-events/deaths. The IR of AIDS/death was higher in patients with lower CD4 cell counts or higher viral loads, regardless of TI. After adjusting for baseline factors, the IR of AIDS/death was significantly higher in the TI group than in the non-TI group [IRR 2.63; 95% confidence interval (CI) 2.01-3.44; P<0.0001]; this could be explained by current CD4 cell counts and viral loads, as the CD4 cell count- and viral load-adjusted IRR was 1.14 (95% CI 0.86-1.51; P=0.37). Within the TI group, patients with a current CD4 cell count of <200 cells/microL had a 3-fold higher risk of AIDS/death than those with a CD4 cell count of 200-350 cells/microL, whereas patients with a current CD4 cell count of >350 cells/microL had a 4-fold lower risk of disease progression.

CONCLUSIONS

TI is common in clinical practice. The risk of AIDS/death increased more than 2-fold for patients stopping all cART regimen drugs for 3 months or more. Among patients experiencing a TI, those with low CD4 cell counts, high viral loads or prior AIDS had an increased risk of AIDS/death. Hence, TI should be discouraged and closely monitored if it occurs.

In vitro cytotoxicity and mitochondrial toxicity of tenofovir alone and in combination with other antiretrovirals in human renal proximal tubule cells

We assessed the in vitro toxicity of tenofovir (TFV) and compared it with those of zidovudine (AZT), didanosine (ddI), ritonavir (RTV), and lopinavir (LPV) alone and in combination in human renal proximal tubule epithelial cells (RPTECs). The cells were treated with various concentrations and combinations of the tested antiretrovirals for up to 22 days, and cytotoxicity was determined. In addition, we assessed the levels of mitochondrial DNA (mtDNA) and cytochrome oxidase II (COII) mRNA in RPTECs treated with reverse transcriptase inhibitors. TFV alone was not associated with significant cytotoxicity. ddI showed pronounced cytotoxicity that was greater than those of AZT (P = 0.002) and TFV (P = 0.0001). The combination of 10 muM RTV and 40 muM LPV significantly reduced RPTEC viability (P < 0.0001), and TFV tended to partially reduce this effect. TFV alone affected neither mtDNA nor COII mRNA levels, whereas ddI caused a profound depletion of mtDNA and a parallel reduction in COII mRNA expression. The effects of ddI, but not those of AZT, on mtDNA and COII mRNA were further enhanced in the presence of TFV, a finding consistent with the inhibition of ddI clearance by TFV. The addition of TFV to ddI or AZT appeared to slightly increase the COII mRNA/mtDNA ratio relative to that in cells treated with ddI or AZT alone. Together, these in vitro results indicate that combination with other antiretrovirals does not significantly increase the toxic potential of TFV in RPTECs.

Impact of antiretroviral treatment-related toxicities on hospital admissions in HIV-infected patients

While classical opportunistic infections have decreased as the main cause of hospital admission of HIV-infected patients, other conditions including drug-related toxicities seem to have increased. We assessed the proportion of patients with hospital admission due to antiretroviral (ARV)-related toxicities over the last 7 years at a single HIV/AIDS reference institution located in Madrid. A total of 1981 consecutive hospital admissions in 1581 different HIV-infected patients were analyzed. Nearly half of them (45%) were on ARV therapy. Overall, ARV-related toxicities were the main or secondary reason for hospital admission in 141 patients (7%). Liver toxicity was the most frequent complication (n = 42; 30%), of which one-third were associated with NVP use and 80% occurred in subjects with underlying chronic hepatitis C virus (HCV) infection. Other main ARV-related toxicities were bone marrow toxicity due to zidovudine (17%), pancreatitis (13%), and indinavirassociated nephrolithiasis (6%). Eight patients presented with symptomatic hyperlactatemia, two of them with lactic acidosis. All subjects with ARV-related toxicities had a favorable outcome, except one with prior HCVrelated end-stage liver disease, who died after experiencing hepatic decompensation following initiation of a protease inhibitor-based regimen.

Proteomic analysis of oxidatively modified proteins induced by the mitochondrial toxin 3-nitropropionic acid in human astrocytes expressing the HIV protein tat

The human immunodeficiency virus (HIV)-Tat protein has been implicated in the neuropathogenesis of HIV infection. However, its role in modulating astroglial function is poorly understood. Astrocyte infection with HIV has been associated with rapid progression of dementia. Intracellularly expressed Tat is not toxic to astrocytes. In fact, intracellularly expressed Tat offers protection against oxidative stress-related toxins such as the mitochondrial toxin 3-nitroproprionic acid (3-NP). In the current study, human astrocytes expressing Tat (SVGA-Tat) and vector controls (SVGA-pcDNA) were each treated with the irreversible mitochondrial complex II inhibitor 3-NP. Proteomics analysis was utilized to identify changes in protein expression levels. By coupling 2D fingerprinting and identification of proteins by mass spectrometry, actin, heat shock protein 90, and mitochondrial single-stranded DNA binding protein were identified as proteins with increased expression, while lactate dehydrogenase had decreased protein expression levels in SVGA-Tat cells treated with 3-NP compared to SVGA-pcDNA cells treated with 3-NP. Oxidative damage can lead to several events including loss in specific protein function, abnormal protein clearance, depletion of the cellular redox-balance and interference with the cell cycle, ultimately leading to neuronal death. Identification of specific proteins protected from oxidation is a crucial step in understanding the interaction of Tat with astrocytes. In the current study, proteomics also was used to identify proteins that were specifically oxidized in SVGA-pcDNA cells treated with 3-NP compared to SVGA-Tat cells treated with 3-NP. We found beta-actin, calreticulin precursor protein, and synovial sarcoma X breakpoint 5 isoform A to have increased oxidation in control SVGA-pcDNA cells treated with 3-NP compared to SVGA-Tat cells treated with 3-NP. These results are discussed with reference to potential involvement of these proteins in HIV dementia and protection of astrocytes against oxidative stress by the HIV virus, a prerequisite for survival of a viral host cell.

Body Composition and Metabolic Changes in Antiretroviral-Naive Patients Randomized to Didanosine and Stavudine vs. Abacavir and Lamivudine

Comparisons of body composition and metabolic changes among antiretroviral-naive patients randomly assigned to didanosine and stavudine- (ddI+d4T) vs. abacavir and lamivudine- (ABC+3TC) containing regimens were assessed in a nested substudy of an ongoing multicenter randomized trial. At baseline and every 4 months, body cell mass and total body fat were calculated, anthropometric measurements were performed, and fasting metabolic parameters were obtained. The rates of change (unit/mo) estimated using the slopes of regression lines and overall mean changes from baseline were compared by study assignment. Among 96 patients enrolled, 46 received ddI+d4T- and 50 received ABC+3TC-containing regimens with a median follow-up of 32.4 months. For both study arms, an overall increase in the rates of change was seen for body cell mass. For ddI+d4T, after an initial increase, the rates of change declined for regional fat and total body fat compared with an increase for ABC+3TC, with the 2 arms being significantly different (P<0.05). For high-density lipoprotein cholesterol rates of change, ddI+d4T decreased, while ABC+3TC increased. For both arms, low-density lipoprotein cholesterol decreased, while triglycerides increased. Early and sustained increases in insulin and insulin resistance were seen only for ddI+d4T. In this prospective study, metabolic and body composition changes varied according to whether subjects received ddI+d4T or ABC+3TC.

Hyperlactataemia and lactic acidosis in HIV-infected patients receiving antiretroviral therapy

Nucleoside reverse-transcriptase inhibitors (NRTIs) have been associated with functional and structural mitochondrial abnormalities, leading to several adverse events, such as increased serum lactic acid levels and lactic acidosis. Mild-to-moderate, asymptomatic hyperlactataemia has been frequently reported in human immunodeficiency virus (HIV)-infected patients treated with NRTIs, with an estimated prevalence between 15% and 35%. On the contrary, symptomatic, severe hyperlactataemia and lactic acidosis are less common, with an incidence ranging from 1.7 to 25.2 cases per 1000 person-years of antiretroviral treatment, and are associated with a remarkable mortality rate, which varies from 30% to 60% in different studies. The clinical presentation of lactic acid syndrome is non-specific and includes asthenia, malaise, nausea, vomiting, abdominal pain, weight loss, tachypnoea, dyspnoea, liver steatosis and increased transaminase levels, and risk factors include previous or concurrent therapy with stavudine or didanosine. Management of symptomatic lactic acid alterations involves NRTI-therapy interruption and supportive care, while natural history of hyperlactataemia is still unknown, and it is uncertain whether asymptomatic patients with increased lactate concentrations are at increased risk of developing lactic acidosis.

Mitochondrial Abnormalities in HIV-Infected Lipoatrophic Patients Treated With Antiretroviral Agents

BACKGROUND

Lipodystrophy is now widely described in HIV infected patients under antiretroviral regimen with important psychological impact. But physiopathology of loss of fat mass is still debated and the role of mitochondrial impairment is not clearly defined.

OBJECTIVE

To correlate clinical lipoatrophy (LA) in HIV patients with long-term treatment by nucleoside reverse transcriptase inhibitors (NRTIs) and muscular impairment related to mitochondrial dysfunction.

METHODS

Ten consecutive patients with clinical LA and 10 nonlipodystrophic (NLD) individuals on antiretroviral therapy were included. Patients underwent the following investigations: dual-energy x-ray absorptiometry (DEXA) scanning and lactate kinetics during standardized exercise. The mitochondrial respiratory complex activity (III and IV) and histoenzymatic abnormalities (classified as none, mild, or severe) were evaluated on muscle tissue obtained by biopsy in deltoid muscle.

RESULTS

Mean NRTI exposure was longer in the LA group than in the NLD group (81 +/- 30 months vs. 59 +/- 15 months), but mean protease inhibitor exposure was identical in both groups. Mean fat mass distribution for leg in the LA and NLD groups was 860 +/- 381 g versus 1895 +/- 999 g, respectively. The lactic acidosis threshold during exercise was reached in the LA group at lower workloads (mean: 45 +/- 17 W in the LA group vs. 68 +/- 11 W in the NLD group), and maximum power output exercise was restricted in LA patients (mean: 115 +/- 30 W vs. 153 +/- 28 W). Total complex activities in muscular tissue were lower in LA patients: the median (range) for complex III was 67 (1-128) versus 112 (28-143), and the median (range) for complex IV was 28 (1-70) versus 42 (1-75). Six patients had severe histoenzymatic abnormalities in the LA group versus none in the NLD group.

CONCLUSION

Clinical LA, confirmed by DEXA, in long-term NRTI-treated patients was associated with muscular mitochondrial dysfunction as shown by rapid lactic acidemia increase, impairment of respiratory chain activity for complexes III and IV, and mitochondrial histoenzymatic abnormalities.

Asymptomatic Hyperlactataemia: Predictive Value, Natural History and Correlates

Background

The significance of asymptomatic hyperlactataemia is unknown.

Methods

We measured serial lactate levels in a group of HIV-infected subjects. Objectives were to identify covariates associated with hyperlactataemia, and to explore the natural history of hyperlactataemia.

Results

Overall, 1487 lactate measurements were performed on 396 subjects; 299 subjects had serial lactate testing, with a median of four performed per patient (range: 2–16). At study entry, lactate was >2.4 mmol/l in 6% of subjects and >3.6 mmol/l in 1%. A multiple logistic regression analysis revealed that cholesterol and current stavudine were the only predictors of hyperlactataemia. Lactate levels were highly reproducible both for short-term (within 3 months) and long-term (>1 year) follow-up. During the study period, 16 subjects were identified with sustained hyperlactataemia; 12/16 remained asymptomatic after a median of 210 days (30–585), and four developed symptoms suggestive of lactic acidosis syndrome. In three of the four, asymptomatic hyperlactataemia had preceded the onset of symptoms by 18–122 days. A longitudinal model showed a rapid rise of lactate levels from 0 to 12 months on nucleoside reverse transcriptase inhibitor (NRTI) and then stabilization. Lactate levels did not correlate with baseline or on-study development of lipoatrophy.

Conclusions

Even when optimal methods of collection are used, asymptomatic hyperlactataemia does exist and could be sustained in a subset of NRTI-treated subjects for as long as 585 days. A subset of these subjects became symptomatic, after as long as 122 days of asymptomatic hyperlactataemia. Asymptomatic hyperlactataemia is not predictive of lipoatrophy. This work was partly presented at the 9th Conference on Retroviruses & Opportunistic Infections. Seattle, Wash., USA, February 2002.

Lactic acidosis related to nucleoside therapy in HIV-infected patients

The incidence of nucleoside analogue-related lactic acidosis has been estimated in 0.57 - 8.5 cases/1000 person years of antiretroviral therapy. The onset of lactic acidosis is usually insidious and patients complain of nausea, vomiting, abdominal pain, fatigue and weight loss. When lactate levels are high enough, a catastropic clinical situation develops, resulting in multiorgan failure. The mortality rate of patients with lactic acidosis related to nucleoside therapy is very high, 33 - 60%. Although all nucleoside analogues have been implicated in lactic acidosis, most cases are associated with stavudine. At present, there are no controlled trials to evaluate the treatment of nucleoside-induced lactic acidosis. Therapy is based on supportive measures and discontinuation of all antiretroviral drugs. Administration of essential vitamin coenzymes, electron acceptors and L-carnitine may be useful in some cases.

Toxicidad mitocondrial de los antirretrovirales: diagnóstico y monitorización

Combination of antiretroviral drugs has dramatically improved the prognosis of individuals with HIV infection. However, their long-term benefit is limited by two main factors: the selection of drug-resistant strains and side effects. A large part of the toxicity of antiretroviral drugs has been associated with mitochondrial damage. Nucleoside analogue reverse transcriptase inhibitors (NRTI), which lack the hydroxyl group needed for further DNA chain elongation, block HIV reverse transcriptase. These nucleosides can be mistaken as natural substrates by the polymerase gamma, the enzyme responsible for the replication of mitochondrial DNA (mtDNA). Depletion or damage of mtDNA may affect the aerobic metabolism of carbohydrates and lipids, resulting in the accumulation of pyruvate/lactate and fatty acids, and ultimately in lactic acidosis and lipoatrophy, respectively. However, the relationship between hyperlactatemia and/or lipoatrophy and mtDNA depletion due to NRTIs has not been demonstrated conclusively. The design of methods to measure mtDNA may help to recognize the mitochondrial toxicity of antiretroviral therapy.