Nucleoside reverse transcriptase inhibitor-induced mitochondrial toxicity as an etiology for lipodystrophy

Metabolic Dysfunction-Associated Steatotic Liver Disease in People Living with HIV-Limitations on Antiretroviral Therapy Selection

Chronic liver disease is one of the main causes of morbidity and mortality in people living with HIV (PLWH). The increasing life expectancy of PLWH, effective treatment for viral hepatitis, and Western dietary patterns as well as the adverse effects of antiretroviral therapy (ART) have rendered metabolic dysfunction-associated steatotic liver disease (MASLD) the most common chronic liver disease in PLWH. The risk factors for MASLD in PLWH include traditional MASLD risk factors and additional virus-specific factors, including the adverse effects of ART. The management of patients suffering from HIV and MASLD is often challenging. Apart from the conventional management of MASLD, there are also certain limitations concerning the use of ART in this patient population. In general, the appropriate combination of antiretroviral drugs should be chosen to achieve the triad of effective viral suppression, avoidance of mitochondrial dysfunction, and deterrence of worsening the patient's metabolic profile. In the current review, we discuss the epidemiology of MASLD in PLWH, the risk factors, and the disease pathogenesis, as well as the limitations in the use of ART in this patient population, while practical recommendations on how to overcome these limitations are also given.

Beneficial Effects of Cannabis on Blood-Brain Barrier Function in Human Immunodeficiency Virus

BACKGROUND

Human immunodeficiency virus (HIV) infection leads to blood-brain barrier (BBB) dysfunction that does not resolve despite viral suppression on antiretroviral therapy (ART) and is associated with adverse clinical outcomes. In preclinical models, cannabis restores BBB integrity.

METHODS

We studied persons with HIV (PWH) and HIV-negative (HIV-) individuals who had used cannabis recently. We assessed 2 biomarkers of BBB permeability: the cerebrospinal fluid (CSF) to serum albumin ratio (CSAR) and CSF levels of soluble urokinase plasminogen activator receptor (suPAR), a receptor for uPA, a matrix-degrading proteolytic enzyme that disrupts the BBB. A composite index of the BBB markers was created using principal components analysis. Neural injury was assessed using neurofilament light (NFL) in CSF by immunoassay.

RESULTS

Participants were 45 PWH and 30 HIV- individuals of similar age and ethnicity. Among PWH, higher CSF suPAR levels correlated with higher CSAR values (r = 0.47, P < .001). PWH had higher (more abnormal) BBB index values than HIV- individuals (mean ± SD, 0.361 ± 1.20 vs -0.501 ± 1.11; P = .0214). HIV serostatus interacted with cannabis use frequency, such that more frequent use of cannabis was associated with lower BBB index values in PWH but not in HIV- individuals. Worse BBB index values were associated with higher NFL in CSF (r = 0.380, P = .0169).

CONCLUSIONS

Cannabis may have a beneficial impact on HIV-associated BBB injury. Since BBB disruption may permit increased entry of toxins such as microbial antigens and inflammatory mediators, with consequent CNS injury, these results support a potential therapeutic role of cannabis among PWH and may have important treatment implications for ART effectiveness and toxicity.

A Review of Non-Alcoholic Fatty Liver Disease in HIV-Infected Patients: The Next Big Thing?

The burden of liver-related morbidity remains high among HIV-infected patients, despite advances in the treatment of HIV and viral hepatitis. Especially, the impact of non-alcoholic fatty liver disease (NAFLD) is significant with a prevalence of up to 50%. The pathogenesis of NAFLD and the reasons for progression to non-alcoholic steatohepatitis (NASH) are still not fully elucidated, but insulin resistance, mitochondrial dysfunction and dyslipidemia seem to be the main drivers. Both HIV-infection itself and combination antiretroviral therapy (cART) can contribute to the development of NAFLD/NASH in various ways. As ongoing HIV-related immune activation is associated with insulin resistance, early initiation of cART is needed to limit its duration. In addition, the use of early-generation nucleoside reverse transcriptase inhibitors and protease inhibitors is also associated with the development of NAFLD/NASH. Patients at risk should therefore receive antiretroviral drugs with a more favorable metabolic profile. Only weight reduction is considered to be an effective therapy for all patients with NAFLD/NASH, although certain drugs are available for specific subgroups. Since patients with NASH are at risk of developing liver cirrhosis and hepatocellular carcinoma, several non-antifibrotic and antifibrotic drugs are under investigation in clinical trials to broaden the therapeutic options. The epidemiology and etiology of NAFLD/NASH in HIV-positive patients is likely to change in the near future. Current guidelines recommend early initiation of cART that is less likely to induce insulin resistance, mitochondrial dysfunction and dyslipidemia. In contrast, as a result of increasing life expectancy in good health, this population will adopt the more traditional risk factors for NAFLD/NASH. HIV-treating physicians should be aware of the etiology, pathogenesis and treatment of NAFLD/NASH in order to identify and treat the patients at risk.

Drug-induced fatty liver disease: An overview of pathogenesis and management

Over the past decades, many drugs have been identified, that can potentially induce steatohepatitis in the predisposed individual. Classically this has been incriminated to amiodarone, perhexiline, and 4,4'-diethylaminoethoxyhexestrol (DH), all of which have been found to independently induce the histologic picture of non-alcoholic steatohepatitis (NASH). Pathogenetic mechanisms of hepatotoxicity although still evolving, demonstrate that mitochondrial dysfunction, deranged ATP production and fatty acid catabolism likely play an important role. Drugs like steroid hormones can exacerbate the pathogenetic mechanisms that lead to NASH, and other drugs like tamoxifen, cisplatin and irenotecan have been shown to precipitate latent fatty liver as well. Further research aiming to elucidate the pathogenesis of drug-induced steatosis and steatohepatitis is needed in order to better design therapeutic targets.

Lamivudine-Induced Liver Injury

BACKGROUND

Lamivudine is a nucleoside analogue antiretroviral drug, known for its low toxicity at clinically prescribed dose. However, the toxicity or mechanism of toxicity and target tissue effects during prolonged administration of higher doses were hardly given sufficient laboratory attention.

AIM

The present work was designed to investigate the biochemical and histopathological changes in the liver of rat administered with prolonged doses of lamivudine.

MATERIAL AND METHODS

Lamivudine in multiple doses of five ranging from 4 mg/kg to 2500 mg/kg were administered, in vitro, by injection into the air-sac of 10-day old fertile embryonated eggs of Gallus domesticus. Also, female rats of the Wistar strain received oral doses, up to 500 mg/kg singly or repeatedly for 15 or 45 days, respectively. Spectrophotometric techniques were employed to monitor activities of the aminotransferases (ALT and AST), γ-glutamyltransferase (GGT) and total protein concentration in serum while activities of glutathione S-transferase (GST), GGT and superoxide dismutase (SOD) as well as concentrations of malondialdehyde (MDA) and protein were determined in liver. Histopathological studies were carried out on liver. Data were analysed using ANOVA and were considered significant when p < 0.05.

RESULTS

The LD50 for the drug calculated from the incubation experiment was 427 mg/kg. Total serum protein concentration significantly reduced while enzymes activities significantly increased at 500 mg/kg only among the repeat-dosed rats. Hepatic GGT, GST and SOD activities as well as MDA concentration were significantly elevated at 20 mg/kg. Histopathological studies showed multifocal lymphoid cell population in the liver sinusoid of the chicken and hydropic degeneration of hepatocytes were recorded among rats repeatedly exposed to the drug respectively at doses ≥ 100 mg/kg.

CONCLUSION

Lamivudine toxicity in rat liver appeared to be mediated by oxidative stress.

Long-Term Changes of Subcutaneous Fat Mass in HIV-Infected Children on Antiretroviral Therapy: A Retrospective Analysis of Longitudinal Data from Two Pediatric HIV-Cohorts

OBJECTIVE

Longitudinal studies objectively evaluating changes in regional fat distribution of HIV-infected children assessed by whole body dual energy X-ray absorptiometry (DEXA) are scarce, whilst this long-term effect of HIV and antiretroviral therapy (cART) is an important issue in infected children in need for lifelong treatment.

METHODS

We assessed regional fat distribution over time, measured with sequential DEXA-scans in HIV-infected children on cART in cohorts from South Africa (SA) and the Netherlands (NL), and in healthy controls (SA). Limb and trunk fat Z-scores were calculated with the lambda-mu-sigma (LMS) method. Multivariable linear regression models with mixed effects were used to investigate the effect of cART compounds on body fat distribution over time.

RESULTS

In total, 218 children underwent 445 DEXA assessments with a median follow-up of 3.5 years. Fat mass in all limbs was decreased in HIV-infected children compared to controls (arm fat Z-score: coefficient -0.4813; P = 0.006, leg fat Z-score: coefficient -0.4345; P = 0.013). In the HIV-infected group, stavudine treatment was associated with lower subcutaneous fat mass (arm fat Z-score: coefficient -0.5838; P = 0.001), with an additional cumulative exposure effect (arm fat Z-score: coefficient -0.0867; P = 0.003).

CONCLUSIONS

Our study shows that subcutaneous fat loss is still prevalent in HIV-infected children on cART, and is strongly associated with cumulative stavudine exposure. These results underline the need for early detection of subcutaneous fat loss and alternative treatment options for HIV-infected children globally.

Changing utilization of Stavudine (d4T) in HIV-positive people in 2006-2013 in the EuroSIDA study

OBJECTIVES

The long-term side effects of stavudine (d4T) led to recommendations in 2009 to phase out use of this drug. We aimed to describe temporal patterns of d4T use across Europe.

METHODS

Patients taking combination antiretroviral therapy (cART) in EuroSIDA with follow-up after 1 January 2006 were included in the study. cART was defined as d4T-containing [d4T plus at least two other antiretrovirals (ARVs) from any class] or non-d4T-containing (at least three ARVs from any class, excluding d4T). Poisson regression was used to describe temporal changes in the prevalence of d4T use and factors associated with initiating d4T.

RESULTS

A total of 5850 patients receiving cART on 1 January 2006 were included in the current analysis, rising to 7768 patients on January 1 2013. During this time, the prevalence of d4T use fell from 11.2% to 0.7%, with an overall decline of 19% per 6 months [95% confidence interval (CI) 19-20%]. d4T use declined fastest in Northern Europe [26% (95% CI 23-29%) per 6 months], and slowest in Eastern Europe [17% (95% CI 16-19%) per 6 months]. In multivariable Poisson regression models, new d4T initiations decreased by 14% per 6 months [adjusted incidence rate ratio (aIRR) 0.86; 95% CI 0.80-0.91]. Factors associated with initiating d4T were residence in Eastern Europe (aIRR 4.31; 95% CI 2.17-9.98) versus other European regions and HIV RNA > 400 copies/mL (aIRR 3.11; 95% CI 1.60-6.02) versus HIV RNA < 400 copies/mL.

CONCLUSIONS

d4T use has declined sharply since 2006 to low levels in most regions; however, a low but persistent level of d4T use remains in Eastern Europe, where new d4T initiations post 2006 are also more common. The reasons for the regional differences may be multifactorial, but it is important to ensure that all clinicians treating HIV-positive patients are aware of the potential harmful effects associated with d4T.

Weight change after antiretroviral therapy and mortality

BACKGROUND

Weight gain after antiretroviral therapy (ART) initiation is common, but its implication for mortality is unknown. We evaluated weight change in the first year after ART initiation and its association with subsequent mortality.

METHODS

Human immunodeficiency virus-infected patients from the Veterans Aging Cohort Study (VACS) who initiated ART between 2000 and 2008, with weight recorded at baseline and 1 year later, were followed another 5 years for mortality. Baseline body mass index (BMI) was classified as underweight (<18.5 kg/m(2)), normal (18.5-24.9 kg/m(2)), overweight (25-29.9 kg/m(2)), and obese (≥30 kg/m(2)). We used multivariable Cox models to assess mortality risk with adjustment for disease severity using the VACS Index.

RESULTS

The sample consisted of 4184 men and 127 women with a mean age of 47.9 ± 10.0 years. After 1 year of ART, median weight change was 5.9 pounds (2.7 kg) (interquartile range, -2.9 to 17.0 pounds, -1.3 to 7.7 kg). Weight gain after ART initiation was associated with lower mortality among underweight and normal-weight patients. A minimum threshold of 10- to 19.9-pound (4.5 to 9.0 kg) weight gain was beneficial for normal-weight patients (hazard ratio, 0.56; 95% confidence interval, .41-.78), but there was no clear benefit to weight gain for overweight/obese patients. Baseline weight, CD4 cell count status, and hemoglobin level were strongly associated with weight gain. Risk for weight gain was higher among those with greater disease severity, regardless of weight at initiation.

CONCLUSIONS

The survival benefits of weight gain after ART initiation are dependent on starting BMI. Weight gain after ART is associated with lower mortality for those who are not initially overweight.

Endocrinopathies in children infected with human immunodeficiency virus

Endocrine changes (including adrenal insufficiency, disorders of growth and puberty, thyroid dysfunction, metabolic abnormalities and osteopenia) accompany human immunodeficiency virus (HIV) infection in pediatric patients. The cause of these changes is multifactorial and includes direct viral effects of HIV, and effects of antiretroviral therapy. These effects may be of particular importance in childhood given the critical developmental processes that occur during this time period and the likelihood of prolonged exposure to the virus and medications.

Zidovudine induces visceral mitochondrial toxicity and intra-abdominal fat gain in a rodent model of lipodystrophy

BACKGROUND

The use of zidovudine is associated with a loss of subcutaneous adipose tissue (SAT). We assessed if zidovudine treatment also affects visceral adipose tissue (VAT) and if uridine supplementation abrogates the adverse effects of zidovudine on VAT.

METHODS

Rats were fed zidovudine for 21 weeks with or without simultaneous uridine supplementation. Control animals did not receive zidovudine, or were treated with uridine alone. Changes in SAT and VAT were monitored by magnetic resonance imaging. Adipose tissue was examined for structural and molecular signs of mitochondrial toxicity.

RESULTS

Zidovudine induced lipoatrophy in SAT and fat hypertrophy in VAT. Compared with controls zidovudine-exposed VAT adipocytes had increased diameters, microvesicular steatosis and enlarged mitochondria with disrupted crystal architecture on electron microscopy. VAT adipocyte mitochondrial DNA (mtDNA) copy numbers were diminished, as were mtDNA-encoded respiratory chain proteins. The 'common' mtDNA deletion was detected in high frequencies in zidovudine treated animals, but not in the controls. Although mtDNA depletion was more profound in SAT compared with VAT, the 'common' deletion tended to be more frequent in the VAT than in the SAT. Uridine coadministration abrogated all effects of zidovudine on VAT and SAT pathology.

CONCLUSIONS

Zidovudine induces a gain of intra-abdominal fat in association with quantitative and qualitative alterations of the mitochondrial genome and impaired expression of mtDNA-encoded respiratory chain components, indicating that zidovudine may contribute to abdominal fat hypertrophy in HIV-infected patients. In this rodent model, uridine supplementation abrogates both SAT and VAT pathology induced by zidovudine.

Pharmacological management of cardiovascular conditions and diabetes in older adults with HIV infection

This review looks at the evidence for potential and theoretical risks of combining antiretroviral treatment with drugs prescribed for cardiovascular disease and diabetes. These conditions are common in the HIV-infected population as a result of ageing and the increased risk associated with both HIV infection and antiretroviral intake.

Metabolic complications and treatment of perinatally HIV-infected children and adolescents

The benefits of long-term antiretroviral therapy (ART) are recognized all over the world with infected children maturing into adults and HIV infection becoming a chronic illness. However, the improved survival is associated with serious metabolic complications, including lipodystrophy (LD), dyslipidemia, insulin resistance, lactic acidosis and bone loss. In addition, the dyslipidemia mainly seen with protease inhibitors may increase the risk of cardiovascular disease in adulthood and potentially in children as they mature into adults. Nucleoside reverse transcriptase inhibitors, particularly stavudine, zidovudine and didanosine are linked to development of LD and lactic acidosis. Perinatally infected children initiate ART early in life; they require lifelong therapy with multiple drug regimens leading to varying toxicities, all potentially impacting their quality of life. LD has a significant impact on the mental health of older children and adolescents leading to poor self-image, depression and subsequent poor adherence to therapy. Reduced bone mineral density (BMD) is reported in both adults and children on ART with the potential for children to develop more serious bone complications than adults due to their rapid growth spurts and puberty. The role of vitamin D in HIV-associated osteopenia and osteoporosis is not clear and needs further study. Most resource-limited settings are unable to monitor lipid profiles or BMD, exposing infected children and adolescents to on-going toxicities with unclear long-term consequences. Improved interventions are urgently needed to prevent and manage these metabolic complications. Longitudinal cohort studies in this area should remain a priority, particularly in resource-limited settings where the majority of infected children reside.

Mechanism of interaction of human mitochondrial DNA polymerase γ with the novel nucleoside reverse transcriptase inhibitor 4'-ethynyl-2-fluoro-2'-deoxyadenosine indicates a low potential for host toxicity

The potent antiretroviral 4'-ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) is a promising experimental agent for treating HIV infection. Pre-steady-state kinetics were used to characterize the interaction of EFdA-triphosphate (EFdA-TP) with human mitochondrial DNA polymerase γ (Pol γ) to assess the potential for toxicity. Pol γ incorporated EFdA-TP 4,300-fold less efficiently than dATP, with an excision rate similar to ddATP. This strongly indicates EFdA is a poor Pol γ substrate, suggesting minimal Pol γ-mediated toxicity, although this should be examined under clinical settings.

Pilot, randomized study assessing safety, tolerability and efficacy of simplified LPV/r maintenance therapy in HIV patients on the 1 PI-based regimen

OBJECTIVES

To compare the efficacy and safety of an individualized treatment-simplification strategy consisting of switching from a highly-active anti-retroviral treatment (HAART) with a ritonavir-boosted protease inhibitor (PI/r) and 2 nucleoside reverse-transcriptase inhibitors (NRTIs) to lopinavir/ritonavir (LPV/r) monotherapy, with intensification by 2 NRTIs if necessary, to that of continuing their HAART.

METHODS

This is a one-year, randomized, open-label, multi-center study in virologically-suppressed HIV-1-infected adults on their first PI/r-containing treatment, randomized to either LPV/r-monotherapy or continue their current treatment. Treatment efficacy was determined by plasma HIV-1 RNA viral load (VL), time-to-virologic rebound, patient-reported outcomes (PROs) and CD4+T-cell-count changes. Safety was assessed with the incidence of treatment-emergent adverse events (AE).

RESULTS

Forty-one patients were randomized to LPV/r and 39 to continue their HAART. No statistically-significant differences between the two study groups in demographics and baseline characteristics were observed. At day-360, 71(39:LPV/r;32:HAART) patients completed treatment, while 9(2:LPV/r;7:HAART) discontinued. In a Last Observation Carried Forward Intent-to-Treat analysis, 40(98%) patients on LPV/r and 37(95%) on HAART had VL<200 copies/mL (P = 0.61). Time-to-virologic rebound, changes in PROs, CD4+ T-cell-count and VL from baseline, also exhibited no statistically-significant between-group differences. Most frequent AEs were diarrhea (19%), headache (18%) and influenza (16%). Four (10%) patients on LPV/r were intensified with 2 NRTIs, all regaining virologic control. Eight serious AEs were reported by 5(2:LPV/r;3:HAART) patients.

CONCLUSION

At day-360, virologic efficacy and safety of LPV/r appears comparable to that of a PI+2NRTIs HAART. These results suggest that our individualized, simplified maintenance strategy with LPV/r-monotherapy and protocol-mandated NRTI re-introduction upon viral rebound, in virologically-suppressed patients merits further prospective long-term evaluation.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00159224.

Pathogenesis and treatment of HIV lipohypertrophy

PURPOSE OF REVIEW

This review addresses our current understanding of the pathogenesis of HIV-associated lipohypertrophy and describes an evidence-based approach to treatment.

RECENT FINDINGS

Although the pathogenesis of HIV-associated lipohypertrophy remains elusive, recent clinical and laboratory investigations in fatty acid metabolism and growth hormone dynamics have furthered our understanding of the condition. These findings have also paved the way for new therapeutic interventions, of which tesamorelin, an analog of growth hormone-releasing hormone (GHRH), has gained recognition as a promising treatment strategy against visceral fat accumulation. Recent randomized placebo-controlled trials of tesamorelin demonstrated significant reductions in visceral adipose tissue, improvement in lipid parameters, and minimal adverse effects on glucose tolerance. Optimal therapeutic dosing and treatment duration, though, are not yet known. Whether treatment with GHRH-analogs will translate into improved long-term metabolic and cardiovascular outcomes also remains to be seen.

SUMMARY

Although the pathogenesis of HIV lipohypertrophy remains unclear, several theories and observations have led to the development of treatment strategies to counter fat accumulation and its accompanying metabolic complications. Based on clinical trials, analogs of the growth hormone (GH)/GHRH axis appear to be most effective in reducing visceral adipose tissue.

Clinical, laboratory, and neuroimaging characteristics of fatigue in HIV-infected individuals

Fatigue is among the most common symptoms reported by HIV-infected individuals. Previous reports suggest that the prevalence of fatigue varies by disease status with rates close to 80% in patients with AIDS. However, most studies have not been conducted in the setting of a controlled trial and have not assessed the association of fatigue with cellular markers of brain activity. Data for this study were derived from baseline and longitudinal evaluations in ACTG A5090, a randomized, double-blind, placebo-controlled trial of the Selegiline Transdermal System for the treatment of HIV-associated cognitive impairment. Fatigue was assessed using the Fatigue Severity Scale with scores of >4 considered "fatigued". Participants in a substudy underwent brain magnetic resonance spectroscopy (MRS) imaging, an in vivo method for assessing brain metabolites associated with neuronal and glia activity. Differences between fatigued and non-fatigued participants were evaluated with respect to demographics and clinical characteristics, plasma and CSF HIV-1 RNA concentration, CD4 counts, and brain metabolites. One hundred and twenty-eight participants were enrolled (88% male, median age = 45 years) and 82 participants (64%, 95% confidence interval 55%, 72%) were fatigued at baseline. MRS was conducted in 62 of the 128 participants. Fatigued participants were significantly younger (p = 0.011), had lower Karnofsky scores (p = 0.032), and had higher levels of depressive symptoms on the Center for Epidemiologic Studies Depression (CES-D) scale (p < 0.001) than non-fatigued participants. Statistically significant differences between fatigued and non-fatigued groups were not detected for plasma and CSF HIV-1RNA concentration, CD4 counts, or on neuropsychological tests. MRS revealed significantly lower levels of the cellular energy marker total creatine (p = 0.002) in the basal ganglia of fatigued participants. Statistically significant differences in other brain metabolites were not detected. Longitudinal data showed that fatigue persisted and worse fatigue at baseline was predictor of future fatigue. Among the cognitive tests, baseline Stroop score was associated with future fatigue. Fatigue was present in 64% of A5090 study participants and persisted during the 24 weeks of follow-up. Fatigue was associated with worse functional performance and depressive mood. Lower cellular energy levels in the basal ganglia, as measured by MRS total creatine concentration, suggest energy dysmetabolism in this brain region. This observation, taken together with the association between fatigue and neuropsychological tests of frontal lobe performance is consistent with the hypothesis of a striatal-cortical circuitry involvement in the symptoms of fatigue.

New and emerging agents in the management of lipodystrophy in HIV-infected patients

Lipodystrophy remains a major long-term complication in human immunodeficiency virus-infected patients under antiretroviral (ARV) therapy. Patients may present with lipoatrophy or lipohypertrophy or both. The choice of treatments to improve fat redistribution depends on the form of lipodystrophy and its duration. Measures known to improve lipoatrophy are switches in ARV therapy (stavudine or zidovudine to abacavir or tenofovir) and filling interventions. Pioglitazone may be added to these measures, although any benefits appear small. Uridine and leptin were found to be disappointing so far. Regarding lipohypertrophy, diet and exercise, recombinant human growth hormone, and metformin may reduce visceral fat, but may worsen subcutaneous lipoatrophy. Surgical therapy may be required. Attractive pharmacologic treatments include growth hormone-releasing factor and leptin. Adiponectin and adiponectin receptors are promising therapeutic targets to explore.

Human immunodeficiency virus and highly active antiretroviral therapy-associated metabolic disorders and risk factors for cardiovascular disease

The successful introduction of highly active antiretroviral therapy (HAART), a combination of potent antiretroviral agents, including protease inhibitors, nucleoside reverse transcriptase inhibitors, and nonnucleoside reverse transcriptase inhibitors, has impacted positively on morbidity and mortality among human immunodeficiency virus (HIV)-positive patients. Over time, HAART has been associated with a number of metabolic and anthropometric abnormalities, including dyslipidemia and insulin resistance as well as subcutaneous fat loss and abdominal obesity, potentially contributing to cardiovascular risk. Recent studies have more firmly established that both HIV infection and HAART might increase the risk of clinical cardiovascular events. Furthermore, whereas HIV/HAART is associated with multiple aspects of endocrine dysfunction, there has been less focus on bone disease, although some studies indicate a higher prevalence of osteoporosis among HIV-positive subjects compared to HIV-negative controls. The relationship between bone and fat metabolism under HIV-positive conditions deserves further attention, and available data suggest the possibility of an intriguing connection. In the future, an increasing population of aging HIV-positive patients with a spectrum of antiretroviral therapies and accumulation of endocrine abnormalities and conventional cardiovascular risk factors will present preventive and therapeutic challenges to our health-care system.

Acetyl-l-carnitine and nucleoside reverse transcriptase inhibitor-associated neuropathy in HIV infection

OBJECTIVES

Antiretroviral toxic neuropathy (ATN) is associated with dideoxynucleoside reverse transcriptase inhibitor use in patients infected with HIV, possibly as a result of mitochondrial toxicity. Acetyl-l-carnitine (ALC) has been linked to symptomatic improvement in ATN. We present an open-label single-arm pilot study to evaluate changes in intra-epidermal nerve fibre (IENF) density and mitochondrial DNA (mtDNA) copies/cell among subjects treated with 3000 mg ALC daily.

METHODS

Punch skin biopsies were examined at baseline and after 24 weeks of therapy. Participants reported neuropathic symptoms using the Gracely Pain Intensity Score. Neurological examinations were completed.

RESULTS

Twenty-one subjects completed the study. ALC was generally well tolerated. The IENF density did not change in cases completing 24 weeks of ALC therapy, with median (90% confidence interval) IENF changes of -1.70 (-3.50, infinity) (P=0.98) and 2.15 (-0.10, infinity) (P=0.11) for the distal leg and proximal thigh, respectively. Fat mtDNA copies/cell did not change with therapy. Improvements in neuropathic pain (P<0.01), paresthesias (P=0.01), and symptoms of numbness (P<0.01) were noted. Similarly, improvement was noted on the Gracely Pain Intensity Score.

CONCLUSIONS

ALC therapy coincided with improvements in subjective measures of pain in this open-label single-arm study. However, changes were not observed in objective measures of IENF density or mtDNA levels, providing little objective support for use of ALC in this setting.

Mitochondrial DNA haplogroups influence lipoatrophy after highly active antiretroviral therapy

Although highly active antiretroviral therapy (HAART) has been extremely effective in lowering AIDS incidence among patients infected with HIV, certain drugs included in HAART can cause serious mitochondrial toxicities. One of the most frequent adverse events is lipoatrophy, which is the loss of subcutaneous fat in the face, arms, buttocks, and/or legs as an adverse reaction to nucleoside reverse transcriptase inhibitors. The clinical symptoms of lipoatrophy resemble those of inherited mitochondrial diseases, which suggest that host mitochondrial genotype may play a role in susceptibility. We analyzed the association between mitochondrial haplogroup and severity of lipoatrophy in HIV-infected European American patients on HAART in the Multicenter AIDS cohort Study and found that mitochondrial haplogroup H was strongly associated with increased atrophy [arms: P = 0.007, odds ratio (OR) = 1.77, 95% confidence interval (CI) = 1.17 to 2.69; legs: P = 0.037, OR = 1.54, 95% CI = 1.03 to 2.31; and buttocks: P = 0.10, OR = 1.41 95% CI = 0.94 to 2.12]. We also saw borderline significance for haplogroup T as protective against lipoatrophy (P = 0.05, OR = 0.52, 95% CI = 0.20 to 1.00). These data suggest that mitochondrial DNA haplogroup may influence the propensity for lipoatrophy in patients receiving nucleoside reverse transcriptase inhibitors.

Cytotoxicological analysis of a gp120 binding aptamer with cross-clade human immunodeficiency virus type 1 entry inhibition properties: comparison to conventional antiretrovirals

The long-term cumulative cytotoxicity of antiretrovirals (ARVs) is among the major causes of treatment failure in patients infected with human immunodeficiency virus (HIV) and patients with AIDS. This calls for the development of novel ARVs with less or no cytotoxicity. In the present study, we compared the cytotoxic effects of a cross-clade HIV type 1-neutralizing aptamer called B40 with those of a panel of nonnucleoside reverse transcriptase inhibitors (NNRTIs), nucleoside reverse transcriptase inhibitors (NRTIs), protease inhibitors (PIs), and the entry inhibitor (EI) T20 in human cardiomyocytes and peripheral blood mononuclear cells. An initial screen in which cell death was used as the end-point measurement revealed that the B40 aptamer and T20 were the only test molecules that had insignificant (0.61 < P < 0.92) effects on the viability of both cell types at the maximum concentration used. PIs were the most toxic class (0.001 < P < 0.00001), followed by NNRTIs and NRTIs (0.1 < P < 0.00001). Further studies revealed that B40 and T20 did not interfere with the cellular activity of the cytochrome P450 3A4 enzyme (0.78 < P < 0.24) or monoamine oxidases A and B (0.83 < P < 0.56) when the activities of the enzymes were compared to those in untreated controls of both cell types. Mitochondrion-initiated cellular toxicity is closely associated with the use of ARVs. Therefore, we used real-time PCR to quantify the relative ratio of mitochondrial DNA to nuclear DNA as a marker of toxicity. The levels of mitochondrial DNA remained unchanged in cells exposed to the B40 aptamer compared to the levels in untreated control cells (0.5 > P > 0.06). These data support the development of B40 and related EI aptamers as new ARVs with no cytotoxicity at the estimated potential therapeutic dose.

The role of protease inhibitors in the pathogenesis of HIV-associated lipodystrophy: cellular mechanisms and clinical implications

Metabolic complications associated with HIV infection and treatment frequently present as a relative lack of peripheral adipose tissue associated with dyslipidemia and insulin resistance. In this review we explain the connection between abnormalities of intermediary metabolism, observed either in vitro or in vivo, and this group of metabolic effects. We review molecular mechanisms by which the HIV protease inhibitor (PI) class of drugs may affect the normal stimulatory effect of insulin on glucose and fat storage. We then propose that both chronic inflammation from HIV infection and treatment with some drugs in this class trigger cellular homeostatic stress responses with adverse effects on intermediary metabolism. The physiologic outcome is such that total adipocyte storage capacity is decreased, and the remaining adipocytes resist further fat storage. The excess circulating and dietary lipid metabolites, normally "absorbed" by adipose tissue, are deposited ectopically in lean (muscle and liver) tissue, where they impair insulin action. This process leads to a pathologic cycle of lipotoxicity and lipoatrophy and a clinical phenotype of body fat distribution with elevated waist-to-hip ratio similar to the metabolic syndrome.

Toxicogenetics of Antiretroviral Therapy: Genetic Factors that Contribute to Metabolic Complications

Metabolic complications of antiretroviral therapy (ART) have emerged as a major concern for long-term, successful management of HIV infection. Variability in the response to ART between individuals has been increasingly linked to the genetic background of patients, as regards efficacy and susceptibility to adverse reactions (toxicogenetics). This review summarizes the biological and methodological background for the genetic prediction of metabolic toxicity of ART. Recent studies are discussed which suggest that single-nucleotide polymorphisms (SNPs) in several genes involved in lipid metabolism and lipid transport in the general population (ABCA1, APOA5, APOC3, APOE, CETP) might modulate plasma triglyceride and high-density lipoprotein cholesterol levels in HIV-infected patients. At present, genetic prediction of lipodystrophy is not possible. Lipodystrophy has been linked to an accumulation of mtDNA mutations, a finding causally associated with ageing phenotypes in animal models. No mutations in LMNA, a gene linked to rare, inherited forms of lipodystrophy, have been identified in small studies of patients with lipodystrophy, and a possible link to a TNF promoter SNP remains to be confirmed. With the rapidly decreasing cost of genetic testing, the main issues that need to be addressed prior to introduction of toxicogenetic prediction in HIV clinical practice include reproducibly high predictive values of SNP associations with clinically relevant and well defined metabolic outcomes, studies that evaluate the contribution of SNPs in the context of multi-SNP and haplotype analysis, and the validation of genetic markers in independent, large patient cohorts. Comprehensive, whole genome approaches are increasingly being used.

Long-Term Body Composition and Metabolic Changes in Antiretroviral Naive Persons Randomized to Protease Inhibitor-, Nonnucleoside Reverse Transcriptase Inhibitor-, or Protease Inhibitor Plus Nonnucleoside Reverse Transcriptase Inhibitor-Based Strategy

OBJECTIVE

To assess changes in metabolic parameters and body composition among 422 antiretroviral-naive patients randomized to 3 antiretroviral therapy (ART) strategies: protease inhibitor (PI; n = 141)-, nonnucleoside reverse transcriptase inhibitor (NNRTI; n = 141)-, or PI + NNRTI (n = 140)-based strategies with a median follow-up of 5 years.

METHODS

At baseline and 1-month (metabolic parameters only) and 4-month follow-up intervals, fat-free mass (FFM) and total body fat were calculated, anthropometric measurements were performed, and fasting metabolic parameters were obtained. Rates of change and mean change were compared.

RESULTS

The PI + NNRTI strategy resulted in greater increases in triglycerides and low-density lipoprotein cholesterol compared with the PI and the NNRTI strategies (P < 0.005), with no differences between the PI and NNRTI strategies. High-density lipoprotein cholesterol increased significantly more in the NNRTI strategy than in the PI strategy (P < 0.005). Insulin and insulin resistance increased similarly with all 3 strategies. Changes in total and regional body composition (loss of subcutaneous tissue area and gains in FFM, nonsubcutaneous tissue area, and visceral tissue area) were observed but did not differ by strategy.

CONCLUSIONS

Long-term follow-up of participants initiating 3 ART strategies demonstrated similar changes in total and regional fat, with no differences by ART strategy. The differential effects on lipid metabolism by strategy and the overall increases in insulin and insulin resistance with all 3 strategies necessitate close monitoring of patients on ART.

Exploratory study comparing the metabolic toxicities of a lopinavir/ritonavir plus saquinavir dual protease inhibitor regimen versus a lopinavir/ritonavir plus zidovudine/lamivudine nucleoside regimen

OBJECTIVES

To assess the safety, efficacy and metabolic toxicity of lopinavir/ritonavir + saquinavir or zidovudine/lamivudine and evaluate the pharmacokinetics of lopinavir/ritonavir + saquinavir.

METHODS

HIV-1-infected, antiretroviral-naive subjects were randomized to lopinavir/ritonavir (400/100 mg) twice daily + saquinavir (800 mg) or zidovudine/lamivudine (150/300 mg) in a Phase II, 48 week study. Subjects receiving lopinavir/ritonavir + zidovudine/lamivudine initiated escalating doses of saquinavir (400, 600 and 800 mg) weekly for 3 weeks.

RESULTS

By intent-to-treat (non-completer = failure) analysis, 10/16 (63%) lopinavir/ritonavir + saquinavir-treated and 7/14 (50%) lopinavir/ritonavir + zidovudine/lamivudine-treated subjects achieved plasma HIV-1 RNA <50 copies/mL (P=0.713) at week 48. Safety, tolerability, metabolic changes and truncal fat increases were similar between groups. Small decreases in the lower extremity fat in the zidovudine/lamivudine group (-6%) and a statistically significant increase in the lower extremity fat in the saquinavir group (+19%) were observed. Lopinavir/ritonavir co-administered with saquinavir 600 or 800 mg twice daily produced saquinavir concentrations similar to those previously reported for saquinavir/ritonavir 1000/100 mg twice daily.

CONCLUSIONS

Treatment regimens had similar efficacy and tolerability. Metabolic parameters suggested lipoatrophy in the zidovudine/lamivudine treatment group. Saquinavir 600 and 800 mg twice daily produced concentrations similar to those previously reported for saquinavir/ritonavir 1000/100 mg twice daily.

Long-term safety and tolerability of the lamivudine/abacavir combination as components of highly active antiretroviral therapy

BACKGROUND

Numerous large, long-term clinical trials have assessed the safety and efficacy of the two antiretroviral nucleoside analogs lamivudine and abacavir as components of highly active antiretroviral therapy for the treatment of patients with HIV-1 infection. This analysis pools the safety data on multi-drug regimens containing lamivudine/abacavir in combination with a protease inhibitor, non-nucleoside reverse transcriptase inhibitor, or nucleoside reverse transcriptase inhibitor.

METHODS

Data are presented from 2279 treatment-naive HIV-1-infected patients who were enrolled in one of five clinical trials that assessed the safety and tolerability of lamivudine/abacavir in combination with a third antiretroviral agent. The well characterised combination of lamivudine/zidovudine plus efavirenz was used as the comparator arm. All available safety data (including data beyond 48 weeks) were used in all analyses, which included calculation of treatment emergent laboratory values, adverse events (AEs), serious AEs, fatalities, drug discontinuations and any summaries by study week of safety data.

RESULTS

In the total lamivudine/abacavir group, 1585 of 2229 (71%) patients experienced at least one drug-related AE during the study compared with 247 of 325 (76%) patients in the lamivudine/zidovudine/efavirenz treatment group. The most common drug-related AEs reported during the study were diarrhoea (19%), nausea (18%) and dizziness (12%) in patients treated with lamivudine/abacavir plus a third agent, and nausea (31%), dizziness (27%) and headache (16%) in the comparator group. Overall, in the total lamivudine/abacavir group there were only three severe (Division of AIDS 1992 toxicity table grade 3 or 4) AEs that were reported in >1% of subjects: drug hypersensitivity, elevated ALT levels and elevated AST levels. In the lamivudine/zidovudine/efavirenz group, six severe AEs that occurred in >1% of the safety population were reported. The abacavir hypersensitivity reaction rate reported in these five studies was comparable with the previously reported rate. In addition, there were no patient fatalities attributed by investigators to the study drugs.

CONCLUSION

This analysis indicates that the combination of lamivudine/abacavir is generally safe for the majority of patients when used as part of combination therapy.

Dermatologic adverse effects of antiretroviral therapy: recognition and management

Despite the decrease in opportunistic infections associated with HIV in the highly active antiretroviral treatment (HAART) era, a significant number of patients still present with skin pathology, some of which can be attributed directly or indirectly to antiretroviral therapy. The non-nucleoside reverse transcriptase inhibitors exhibit a class effect with regard to skin adverse manifestations, and the spectrum of disease can vary from a mild morbilliform rash to Stevens-Johnson syndrome. Certain protease inhibitors are associated with rash, and indinavir causes retinoid-like manifestations such as paronychia, alopecia, ingrown toe-nails, and curling of straight hair. Abacavir, a nucleoside reverse transcriptase inhibitor, is notorious for causing a hypersensitivity reaction in select patients. The fusion inhibitor enfuvirtide causes injection-site reactions in the overwhelming majority of patients, although a new method of delivery has decreased the rate and severity of these reactions. A syndrome of lipoatrophy with or without lipohypertrophy, often termed lipodystrophy, has been described in patients receiving HAART. Potential management of lipoatrophy includes switching antiretrovirals and surgical treatment with facial fillers. Lastly, skin manifestations of the immune reconstitution inflammatory syndrome, including herpes zoster and warts, must be recognized and treated accordingly. In the evaluation of the individual HIV-infected patient receiving antiretroviral therapy who presents with a skin disorder, clinicians should consider the CD4 cell count as a marker of the degree of immunodeficiency, the specific antiretrovirals used, and the timing of the initiation of antiretroviral therapy in order to formulate a rational differential diagnosis. Management should be individualized based on the specific drug that is implicated and the severity of the reaction.

Site-specific reduction of oxidative and lipid metabolism in adipose tissue of 3'-azido-3'-deoxythymidine-treated rats

Although it is well accepted that treatment with some nucleoside reverse transcriptase inhibitors modifies both fat metabolism and fat distribution in humans, the mechanisms underlying these modifications are not yet known. The present investigation examined whether a decrease in oxidative capacity, induced by a chronic oral administration of 3'-azido-3'-deoxythymidine (AZT) in rats, could be associated with an alteration of the lipogenic capacity of white adipose tissues. The impact of obesity as a factor was then evaluated. Results showed that AZT treatment induced differential effects depending on anatomical localization. Indeed, in the inguinal adipose tissue, the specific activities of cytochrome c oxidase and fatty acid synthase, two rate-controlling enzymes in energy and lipogenic metabolisms, respectively, both decreased under AZT treatment, thus leading to a lowered cell lipid accumulation. Moreover, the AMP-activated protein kinase phosphorylation level tended to increase, thus implying that AZT causes an energy imbalance. Furthermore, the inguinal tissue of obese rats presented a sensitivity to AZT treatment that was higher than that of lean rats. In contrast, for epididymal tissue, no significant change in all these parameters could be detected under AZT treatment, regardless of the nutritional status of the animals. Taken together, these data demonstrate differential effects of AZT on subcutaneous adipose tissue and visceral white adipose tissue. It could be considered that the chronic decreases in energy and lipogenic metabolism of inguinal adipocyte, consecutive to AZT treatment, may lead, in the long term, to adipose tissue atrophy.

Patogenia de la lipodistrofia y de las alteraciones metabólicas asociadas a la infección por el VIH

Lipodystrophy, and the metabolic alterations (dislipemia, insulin-resistance) associated with human immunodeficiency virus (HIV) infection, is a multifactorial syndrome due to the interaction of host related factors (cellular immune status, diet, gene mutations), viral factors (cytokine synthesis, polyunsaturated fatty acid or PUFA depletion), and pharmacological effects (mitochondrial DNA-polymerase inhibition, lipolysis inhibition, adiponectin synthesis reduction). HIV probably modifies the adipocyte differentiation and the lipid metabolism. This retroviral effect is mediated by proinflammatory cytokines (tumor necrosis factor) and the participation of other factors (drugs, diet), all in the context of a particular host genetic setting. The adipocyte (and several cellular receptors, fatty acids, membrane proteins, and cytokines) plays a central role in the pathogenesis of HIV-associated lipodystrophy.

Anti-HIV drugs and the mitochondria

Several drugs are currently used that can significantly prolong the course of the infection with the human immunodeficiency virus (HIV), the cause of the acquired immunodeficiency syndrome (AIDS). Among these drugs, the nucleosidic inhibitors of viral reverse transcriptase can alter mitochondrial (mt) function by inhibiting the mitochondrial DNA polymerase gamma (the enzyme responsible for the replication of mtDNA). Decreased mtDNA content provokes a diminished synthesis of respiratory chain enzymes, leading to alterations in mt function. These are in turn responsible for a variety of side effects frequently observed in HIV+ patients, that range from hyperlactatemia and lactic acidosis to lipodystrophy, a pathology characterized by accumulation of visceral fat, breast adiposity, cervical fat-pads, hyperlipidemia, insulin resistance and fat wasting in face and limbs. In this paper, data concerning the effects of different compounds on mitochondria, their role in the pathogenesis of lipodystrophy, and problems related to studies on the mt toxicity of antiviral drugs are reviewed and thoroughly discussed.

[Antiretroviral treatments-related lipodystrophy syndrome: clinico-pathological findings]

Effective therapies are available that can stop or slow down the progression of HIV infection. Highly active antiretroviral therapy (HAART) is a combination of antiretroviral drugs such as viral protease inhibitors or nucleoside-analogue reverse-transcriptase inhibitors. Among the side effects due to these drugs, lipodystrophy is a pathology characterized by fat wasting in face and limbs, accumulation of visceral fat, breast adiposity, cervical fat-pads, hyperlipidemia (hypertriglyceridemia and hypercholesterolemia), insulin resistance, and lactic acidemia. The main clinical features include peripheral fat loss (presumed lipoatrophy in the face, limbs, and buttocks) and central fat accumulation (within the abdomen, breasts, and over the dorsocervical spine, so-called "buffalo hump"). Histopathological features disclose a peculiar type of involutional lipodystrophy. Skin biopsies generally show thinning of the subcutaneous fat, associated with fibrosis, lipogranuloma and sometimes vessel proliferation. There is still an open debate concerning the precise responsibility of HAART as well as the metabolic pathways and mechanisms that are involved in the onset of lipodystrophy. There is no proven therapy for any component of lipodystrophy syndrome.

Mitochondrial toxicity of nucleoside analogues: mechanism, monitoring and management

Nucleoside analogues (NRTIs) are potent antiretroviral medications and are central to effective highly active antiretroviral therapy (HAART). Their intended action is to inhibit HIV reverse transcriptase. Nucleoside analogues also inhibit replication of mitochondrial DNA, and the pathogenesis of many of the toxicities associated with HAART is thought to be NRTI-induced mitochondrial dysfunction. Individuals with HIV infection may be particularly susceptible to clinically significant mitochondrial toxicity due to possible effects of HIV itself on mitochondria. At present there is no reliable method of detecting subclinical mitochondrial toxicity in patients exposed to NRTIs. Clinical awareness of this problem is therefore important to ensure the early detection of significant side effects and to allow timely consideration of changing therapy in those affected. There is no proven, effective therapy for NRTI-associated mitochondrial toxicity other than ceasing the implicated agent, and even with this strategy, resolution of symptoms may be incomplete. Similarly, there are no established methods for preventing mitochondrial toxicity in those on therapy including NRTIs. Micronutrients may have a role, but further study is needed to clarify optimal prevention as well as monitoring strategies.

13C-methionine breath test detects distinct hepatic mitochondrial dysfunction in HIV-infected patients with normal serum lactate

OBJECTIVE

To assess mitochondrial respiratory chain dysfunction in different treatment groups of HIV-infected patients with normal serum lactate by measuring hepatic mitochondrial decarboxylation capacity by the C-methionine breath test (MeBT) and to correlate MeBT results with mitochondrial DNA (mtDNA) content in peripheral blood mononuclear cells (PBMCs).

METHODS

Four groups were studied: HIV-negative controls (n = 10), treatment-naive patients (n = 15), antiretroviral therapy (ART)-treated patients with asymptomatic disease (n = 15), and patients with long-term treatment and clinical evidence of lipoatrophy (n = 15). After oral administration of C-methionine, CO2 exhalation was determined by infrared spectroscopy. MtDNA content in PBMCs was assessed by real-time polymerase chain reaction quantification.

RESULTS

CO2 exhalation in lipoatrophic patients and therapy-naive patients was distinctly decreased when compared with that in healthy controls and asymptomatic patients (P < 0.001). The functional mitochondrial impairment in lipoatrophic patients was associated with a 47% decline in mtDNA content. MeBT results and mtDNA were significantly correlated in ART-treated patients (r = 0.77, P < 0.0001).

CONCLUSIONS

MeBT is a simple noninvasive method to detect mitochondrial dysfunction in HIV-infected patients that correlates with mtDNA depletion in PBMCs of ART-treated individuals. Decreased hepatic methionine metabolism in therapy-naive patients may reflect the functional relevance of viral-mediated mitochondrial toxicity.

Redefining Lipodystrophy Syndrome

Lipodystrophy syndrome comprises several conditions (lipoatrophy; lipohypertrophy; mixed syndrome, often associated with dyslipidemia; and insulin resistance). These conditions, though sometimes occurring together, may occur independently, suggesting a complex, multifactorial cause. To elucidate the relative contribution of risk factors of drug, disease, and host to fat redistribution, large epidemiologic studies using multivariate analysis were reviewed. In studies assessing lipoatrophy, the most common statistically significant risk factors were use of specific nucleoside analogues, increasing age, presence of markers of disease severity (CD4/HIV RNA), duration of therapy, and white race. In studies assessing lipohypertrophy, the most common statistically significant risk factors were duration of therapy, markers of disease severity, and protease inhibitor use. The pathogenesis of these disorders is complex, but recent hypotheses and evidence suggest that impairment to adipocyte differentiation, impairment of adipokine regulation, unopposed production of proinflammatory cytokines, dysregulation of 11-beta-hydroxysteroid dehydrogenase, and mitochondrial toxicity may play a role.

HIV-associated lipodystrophy syndrome: A review of clinical aspects

Approximately two years after the introduction of highly active antiretroviral therapy for the treatment of HIV infection, body shape changes and metabolic abnormalities were increasingly observed. Initially, these were ascribed to protease inhibitors, but it is now clear that nucleoside reverse transcriptase inhibitors also contribute to lipodystrophy syndrome. The syndrome groups together clinical conditions describing changes in body fat distribution that include lipoatrophy, lipoaccumulation or both. However, there does not appear to be a direct link between lipoatrophy and lipoaccumulation that would support a single mechanism for the redistribution of body fat. Currently, there is no clear definition of lipodystrophy, which explains the difficulty in determining its prevalence and etiology. There are no current guidelines for the treatment of fat distribution abnormalities that occur in the absence of other metabolic complications. The present article reviews the current state of knowledge of the definition, symptoms, risk factors, pathogenesis, diagnosis and treatment of the morphological changes associated with lipodystrophy syndrome.

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.

Nucleoside Analogue-Sparing Strategy for the Treatment of Chronic HIV Infection: Potential Interest and Clinical Experience

Nucleoside analogue-sparing antiretroviral combinations may be interesting as first-line therapies as they spare a complete class of drugs that will remain fully active for later use and prevent the risk of mitochondrial toxicity related to exposure to nucleoside reverse transcriptase inhibitors (NRTIs). This strategy is also used in patients failing NRTIs with cross-resistance to compounds in this class. Different combinations of antiretroviral drugs are theoretically available. Non-nucleoside reverse transcriptase inhibitors (NNRTIs) associated with protease inhibitor (PI) and boosted double-PI combinations have been studied through small, non-comparative clinical studies and preliminary results suggest that they are efficient and often well-tolerated. However, NNRTIs and PIs are extensively metabolized in the liver through cytochrome P450, leading to pharmacokinetic interactions; a good knowledge of the interactions between NNRTIs and PIs, or between PIs, is helpful in assisting physicians in clinical practice in choosing drugs and doses. Access to a therapeutic drug monitoring service to confirm that appropriate drug exposures are achieved is useful when using such regimens. Some negative kinetic interactions may lead to complicated combinations with a high pill burden that reduces their applicability. Gastrointestinal toxicity often remains a limiting factor in the use of boosted double-PI combinations. Non-comparative studies have allowed selection of NRTI-sparing options that now need to be compared with the current standard of care in comparative clinical trials before being considered as valuable options. Other NRTI-sparing therapeutic strategies are emerging: PI monotherapy with lopinavir/ritonavir has been evaluated in a small group of naive patients and appears promising. Drugs belonging to new classes currently under investigation, such as entry inhibitors, might be included early in the antiretroviral treatment of patients as soon as compounds with a convenient route of administration are available, increasing the number of therapeutic combinations without NRTIs.

Lopinavir/Ritonavir Plus Nevirapine as a Nucleoside-Sparing Approach in Antiretroviral-Experienced Patients (NEKA Study)

OBJECTIVES

To compare the efficacy and safety of a nucleoside-sparing approach with a conventional highly active antiretroviral therapy (HAART) regimen in antiretroviral-experienced patients with prolonged viral suppression.

METHODS

Pilot study including 31 antiretroviral-experienced patients with HIV RNA <80 copies/mL. Subjects were randomly assigned to lopinavir/ritonavir (LPV/rtv) 400/100 mg BID plus nevirapine (NVP) 200 mg BID (NVP group, n = 16) or LPV/rtv plus the 2 previous NRTIs (NRTI group, n = 15). The primary endpoint was the percentage of subjects who maintained viral suppression at week 48. Changes in lipid metabolism, mitochondrial parameters, and LPV trough levels were also assessed.

RESULTS

All patients maintained viral suppression after 48 weeks. No subject discontinued therapy because of adverse events. HDL cholesterol increased by 28% at week 24 (P < 0.0001) and 10% after 48 weeks of follow-up (P = 0.319) in the NVP group. In the NRTI group, LDL cholesterol increased by 14% at week 48 (P = 0.076). Mitochondrial DNA/nuclear DNA ratio and mitochondrial respiratory chain complex IV activity showed a trend toward increasing in the NVP group. Mean (SD) LPV trough levels were 6340 (2129) ng/mL in the NRTI group and 5161 (2703) ng/mL in the NVP group (P = 0.140).

CONCLUSIONS

In antiretroviral-experienced subjects with sustained viral suppression, dual therapy with NVP plus LPV/rtv at standard dosage was as potent and safe as standard-of-care HAART at 48 weeks of follow-up. This approach may reduce mitochondrial toxicity and improve LPV/rtv-associated lipid abnormalities. The results of this pilot study support the study of this approach in a larger, randomized trial.

Mitochondrial DNA Levels in Fat and Blood Cells from Patients with Lipodystrophy or Peripheral Neuropathy and the Effect of 90 Days of High-Dose Coenzyme Q Treatment: A Randomized, Double-Blind, Placebo-Controlled Pilot Study

BACKGROUND

Mitochondrial toxicity can be induced by reverse-transcriptase inhibitors, and an association between levels of mitochondrial DNA (mtDNA) per cell and lipodystrophy, peripheral neuropathy, and HIV infection per se has been suggested. Studies aimed at increasing the oxidative capacity in HIV-infected patients have been sparse.

METHODS

Levels of mtDNA in fat and peripheral blood mononuclear cells (PBMCs) from 25 HIV infected patients and 10 healthy control subjects were studied with real-time PCR analysis. A placebo-controlled and double-blind design was used to assign individuals to receive either 100 mg of coenzyme Q twice daily for 3 months or a matching placebo regimen. Levels of mtDNA and other parameters were assessed before and after the intervention period.

RESULTS

The mean number of mtDNA copies per cell was lower in fat tissue obtained from patients with peripheral neuropathy (1547 mtDNA copies/cell; P=.045), patients with lipodystrophy (1732 mtDNA copies/cell; P=.003) and in HIV patients with no complications associated with highly active antiretroviral therapy (2935 mtDNA copies/cell; P=.078), compared with healthy control subjects (6198 mtDNA copies/cell). No clear difference was seen in mtDNA content in PBMCs. Coenzyme Q therapy improved the general condition of patients (P=.005) and caused a reversible increase in peripheral neuropathy pain (P=.048). Compared with placebo, treatment with coenzyme Q did not result in changes in mtDNA levels in fat cells or in PBMCs after the treatment period.

CONCLUSIONS

Levels of mtDNA in fat tissue, but not in PBMCs, were associated with peripheral neuropathy and lipodystrophy. High-dose coenzyme Q therapy increased well-being in asymptomatic HIV-infected patients and those with lipodystrophy, as well as in control subjects, but aggravated pain in patients with peripheral neuropathy.

Lipodystrophy Syndrome: The Morphologic and Metabolic Effects of Antiretroviral Therapy in HIV Infection

Widespread use of highly active antiretroviral therapy (HAART) to manage HIV infection is now associated with the development of lipodystrophy syndrome. This syndrome is a combination of such morphologic and metabolic changes as hyperlipidemia, fat redistribution, and insulin resistance. Although many of the long-term effects of HAART have not been fully recognized, it is thought that lipodystrophy syndrome may now contribute to early-onset hypercholesterolemia, heart disease, and diabetes, and may have a negative psychological impact on the individual living with HIV infection.

HIV-related lipodystrophy and related factors

As new therapies for HIV infection have been developed, some of the clinical focus related to AIDS and HIV infection has shifted from acute care, to more chronic issues. Some of these new clinical issues seem related to the HIV infection itself, while others seem to be side effects of therapeutic efforts. Metabolic abnormalities, such as dyslipidemia, insulin resistance, and lipodystrophy (LD) have been observed. The clinical importance of these is demonstrated by the increased prevalence of cardiovascular disease and diabetes in HIV infected persons. LD is a general term used to describe varying degrees of fat redistribution, including lipoatrophy and lipohypertrophy, in different body regions. Though LD was observed in persons with HIV infection before highly active treatment regimens were developed, the prevalence of LD has seemingly increased drastically with the widespread use of more active therapies. It has been postulated that protease inhibitors (PI), especially, are linked to the development of LD. This review will assess the epidemiologic information related to HIV-associated LD, and related metabolic syndromes. In addition, potential mechanisms accounting for these syndromes will be reviewed. In general, the available data do not define a single, definable etiology or mechanism explaining these clinical conditions, but suggest that these conditions are caused by a complex interaction potentially involving such things as the side effects of medications, alteration of immune function, and individual subject characteristics, such as body weight and baseline lipid level.

Prevalence of Lipoatrophy and Mitochondrial DNA Content of Blood and Subcutaneous Fat in HIV-1-Infected Patients Randomly Allocated to Zidovudine- or Stavudine-Based Therapy

Introduction

Mitochondrial toxicity resulting from mitochondrial DNA (mtDNA) depletion is suggested to be involved in the pathogenesis of lipodystrophy.

Methods

We cross-sectionally assessed lipodystrophy both clinically and radiographically in patients who, 4 years before, had been enrolled in a randomized comparative trial of stavudine- or zidovudine-based therapy. mtDNA content was measured in peripheral blood mononuclear cells (PBMCs) and subcutaneous adipose tissue from the thigh and back.

Results

Twenty-eight of the 45 patients enrolled in the original trial were included. Despite comparable exposure to stavudine or zidovudine (51 and 50 months, respectively), lipoatrophy prevalence by intent-to-treat analysis was significantly greater in stavudine recipients (82 vs 9%, P=0.0001). Likewise, those allocated to stavudine had significantly less peripheral fat. In an analysis restricted to patients who had remained on randomly allocated nucleoside reverse transcriptase inhibitors (NRTIs), mtDNA in PBMCs decreased after the start of treatment in both groups ( P<0.0001) (-73% for stavudine and -67% for zidovudine, P=0.11), resulting in significantly lower levels in patients with lipoatrophy ( P=0.007). The mtDNA content in subcutaneous adipose tissue from the thigh, but not from the back, was significantly lower in patients allocated to stavudine compared to zidovudine ( P=0.01). mtDNA in adipose tissue from either location did not differ significantly between those with or without lipoatrophy.

Discussion

This study objectively confirms that regimens containing stavudine are associated with a greater risk of lipoatrophy than those containing zidovudine. mtDNA in PBMCs markedly declined with both treatments and was lowest in patients with lipoatrophy. The lack of difference in mtDNA in adipose tissue from patients with as opposed to without lipoatrophy may have been masked by a relative preponderance of stromal and vascular tissue in the subcutaneous tissue samples from these patients, combined with compensatory mitochondrial proliferation in remaining adipocytes. However, our findings may also suggest that the different risk of lipoatrophy observed between NRTIs cannot solely be explained by differences in mtDNA depletion directly at the level of peripheral adipose tissue.

Low plasma level of adiponectin is associated with stavudine treatment and lipodystrophy in HIV-infected patients

This study tested the hypothesis that in patients with HIV-associated lipodystrophy, adiponectin levels were related to insulin resistance, TNF-alpha and IL-6 and treatment with nucleoside analogues. HIV seropositive men undergoing highly active antiretroviral treatment were enrolled into three predetermined clinical groups: lipodystrophy with central fat accumulation (n = 12); lipodystrophy without central fat accumulation (n = 15); no lipodystrophy (n = 15). HIV-negative healthy men served as controls (n = 12). Both lipodystrophic groups had a low percentage of limb fat compared to the two control groups. Patients with lipodystrophy with fat accumulation had increased truncal fat compared with controls. Levels of adiponectin did not correlate with either TNF-alpha or IL-6. Low levels of adiponectin were found in both lipodystrophic groups and were associated with current or previous treatment with stavudine. Furthermore, the adiponectin level correlated with the percentage of limb fat. Patients with lipodystrophy with fat accumulation were more insulin resistant, measured by HOMA-IR, compared with controls. However, HOMA-IR did no correlate to adiponectin or other cytokines. In conclusion, the finding of no difference between the two lipodystrophic groups with regard to adiponectin, indicates that low levels of adiponectin reflects fat atrophy, whereas the insulin resistance was best explained by increased truncal fat mass.

HIV infection and advanced age emerging epidemiological, clinical, and management issues

While the mean age of HIV/AIDS patients at first diagnosis is progressively rising, no updated epidemiological estimates, controlled clinical data, and randomized therapeutic trials, are available regarding clinical and laboratory response to antiretroviral therapy, safety of anti-HIV compounds and their associations, potential drug-drug interactions, short- and long-term toxicity, consequences on underlying disorders, or interactions with concomitant pharmacological regimens, in the elderly. The life expectancy of HIV-infected persons treated with highly active antiretroviral therapy (HAART) now approximates that of general population matched for age, while also AIDS definition itself has lost most of its epidemiological and clinical significance, thanks to the immunoreconstitution resulting from the large-scale use of potent HAART regimens. The increased survival of HIV-infected patients, the late recognition of other subjects with missed or delayed diagnosis are responsible for a further expected rise of mean age of HIV-infected individuals, so that the patient population aged 60-70 years or more is expected to increase in coming years. Unfortunately, the majority of therapeutic trials involving antiretroviral therapy, as well as antimicrobial chemoprophylaxis for AIDS-related opportunistic complications, have advanced age and/or concurrent end-organ disorders among main exclusion criteria, or the design of these studies does not allow to extrapolate data regarding older patients, compared with younger ones. The very limited data presently available seem to demonstrate that HAART has a virological efficacy in the elderly comparable with that of younger adults, but immunological recovery is often slower and blunted, although several studies clearly demonstrated that thymic function is preserved until late adult age. When facing an HIV-infected patient with advanced age, health care givers have to pay careful attention to eventual end-organ disorders, all possible pharmacological interactions, overlapping toxicity due to concurrent drug administration. All these issues may significantly interfere with HAART activity, patient's adherence to prescribed medications, and frequency and severity of untoward effects. The guidelines of antiretroviral therapy and those of treatment and prophylaxis of AIDS-related diseases deserve appropriate updates, paralleling the increasing mean age of HIV-infected population. Moreover, epidemiological figures need an increased focus on older age, while clinical trials specifically targeting on the elderly population are mandatory to have reliable data on all aspects of HAART administration in advanced age.

Mitochondrial toxicity of NRTI antiviral drugs: an integrated cellular perspective

Highly active antiretroviral therapy (HAART) regimes based on nucleoside reverse transcriptase inhibitors (NRTIs) have revolutionized the treatment of AIDS in recent years. Although HAART can successfully suppress viral replication in the long term, it is not without significant toxicity, which can seriously compromise treatment effectiveness. A major toxicity that has been recognized for more than a decade is NRTI-related mitochondrial toxicity, which manifests as serious side effects such as hepatic failure and lactic acidosis. However, a lack of understanding of the mechanisms underlying mitochondrial toxicity has hampered efforts to develop novel drugs with better side-effect profiles. This review characterizes the pharmacological mechanisms and pathways that are involved in mitochondrial dysfunction caused by NRTIs, and suggests opportunities for future pharmacological research.