Osteoporosis and bone health in HIV

Urgent focus on enhanced recovery after surgery of AIDS patients with limb fractures

Aims

The incidence of limb fractures in patients living with HIV (PLWH) is increasing. However, due to their immunodeficiency status, the operation and rehabilitation of these patients present unique challenges. Currently, it is urgent to establish a standardized perioperative rehabilitation plan based on the concept of enhanced recovery after surgery (ERAS). This study aimed to validate the effectiveness of ERAS in the perioperative period of PLWH with limb fractures.

Methods

A total of 120 PLWH with limb fractures, between January 2015 and December 2023, were included in this study. We established a multidisciplinary team to design and implement a standardized ERAS protocol. The demographic, surgical, clinical, and follow-up information of the patients were collected and analyzed retrospectively.

Results

Compared with the control group, the ERAS group had a shorter operating time, hospital stay, preoperative waiting time, postoperative discharge time, less intraoperative blood loss, and higher albumin and haemoglobin on the first postoperative day. The time to removal of the urinary catheter/drainage tube was shortened, and the drainage volume was also significantly reduced in the ERAS group. There was no significant difference in the visual analogue scale (VAS) scores on postoperative return to the ward, but the ERAS group had lower scores on the first, second, and third postoperative days. There were no significant differences in the incidence of complications, other than 10% more nausea and vomiting in the control group. The limb function scores at one-year follow-up were similar between the two groups, but time to radiological fracture union and time to return to physical work and sports were significantly reduced in the ERAS group.

Conclusion

The implementation of a series of perioperative nursing measures based on the concept of ERAS in PLWH with limb fracture can significantly reduce the operating time and intraoperative blood loss, reduce the occurrence of postoperative pain and complications, and accelerate the improvement of the functional status of the affected limb in the early stage, which is worthy of applying in more medical institutions.

Navigating Post-Traumatic Osteoporosis: A Comprehensive Review of Epidemiology, Pathophysiology, Diagnosis, Treatment, and Future Directions

Post-traumatic osteoporosis (PTO) presents a significant challenge in clinical practice, characterized by demineralization and decreased skeletal integrity following severe traumatic injuries. This literature review manuscript addresses the knowledge gaps surrounding PTO, encompassing its epidemiology, pathophysiology, risk factors, diagnosis, treatment, prognosis, and future directions. This review emphasizes the complexity of the etiology of PTO, highlighting the dysregulation of biomineralization processes, inflammatory cytokine involvement, hormonal imbalances, glucocorticoid effects, vitamin D deficiency, and disuse osteoporosis. Moreover, it underscores the importance of multidisciplinary approaches for risk mitigation and advocates for improved diagnostic strategies to differentiate PTO from other musculoskeletal pathologies. This manuscript discusses various treatment modalities, including pharmacotherapy, dietary management, and physical rehabilitation, while also acknowledging the limited evidence on their long-term effectiveness and outcomes in PTO patients. Future directions in research are outlined, emphasizing the need for a deeper understanding of the molecular mechanisms underlying PTO and the evaluation of treatment strategies' efficacy. Overall, this review provides a comprehensive overview of PTO and highlights avenues for future investigation to enhance clinical management and patient outcomes.

Bone Metabolism in Men who Live with HIV Aged 50 years and Over: Impact of Infection Duration

BACKGROUND

Early diagnosis and effective antiretroviral therapy (ART) lead to similar life expectancy in people living with HIV (PLWH) compared to the general population. This population faces problems such as decreased bone mineral density (BMD) and increased fracture risk. The aim of this study was to determine the prevalence of osteoporosis in men aged 50 years and over who were PLWH and to determine risk factors and changes in bone metabolism with bone turnover markers.

METHODS

79 male PLWH aged 50 years and over were followed up in our outpatient clinic between May 2021 and October 2021. The patients' demographic, clinical, laboratory, and DEXA data were analyzed. Serum levels of bone turnover markers were measured.

RESULTS

The prevalence of osteopenia, osteoporosis, and normal BMD was found to be 55.7%, 13.9%, and 30.4%, respectively. A correlation was found between low BMD and low body mass index, elapsed time since diagnosis of HIV infection, high rate of use of ART, and long usage time of tenofovir disoproxil fumarate + protease inhibitor. A one-year increase in HIV infection duration was associated with an increased risk of low BMD by 1.246.

CONCLUSION

Compared to studies conducted on the general population, the prevalence of osteoporosis in male PLWH aged 50 years and older was two times higher. The limited effect of the duration of ART use on low BMD may be due to the patients' histories of replacement therapy. Therefore, to eliminate the negative effects of ART on BMD, it may be beneficial to start replacement therapy when necessary.

Cortical and Trabecular Bone Deficit in Middle-Aged Men Living with HIV

A significant increase in the risk of hip fracture was observed in middle-aged men living with human immunodeficiency virus (MLWH), almost a decade earlier than those without infection. Data regarding cortical and trabecular bone deficit of hip, an important determinant of bone strength, in MLWH are limited. Quantitative CT was performed in consecutive MLWH aged ≥30 years between November 2017 and October 2018 at Severance Hospital, Seoul, Korea. Volumetric bone mineral density (vBMD) and cortical bone mapping parameters of hip (cortical thickness [CTh], cortical bone vBMD [CBMD], cortical mass surface density [CMSD], endocortical trabecular density [ECTD]) were compared to age-matched and body mass index (BMI)-matched controls (1:2) using a community-based healthy adults cohort. Among 83 MLWH and 166 controls (mean age: 47.2 years; BMI: 23.6 kg/m2 ), MLWH had lower total hip vBMD (280 ± 41 versus 296 ± 41 mg/cm3 ), CMSD (155 versus 160 mg/cm2 ), and ECTD (158 versus 175 mg/cm3 ) than controls that remained robust after adjustment for covariates (adjusted β: total hip vBMD, -18.8; CMSD, -7.3; ECTD, -18.0; p < 0.05 for all). Cortical bone mapping revealed localized deficit of CTh, CBMD, and CMSD in the anterolateral trochanteric region and femoral neck in MLWH compared to controls, with a more extensive ECTD deficit. In MLWH, lower CD4 T-cell count (/100 cells/mm3 decrement) and protease inhibitor (PI)-based regimen (versus non-PI regimen) at the time of antiretroviral treatment initiation were associated with lower total hip vBMD (adjusted β -7.5 for lower CD4 count; -28.3 for PI-based regimen) and CMSD (adjusted β -2.6 for lower CD4 count; -12.7 for PI-based regimen; p < 0.05 for all) after adjustment for covariates including age, BMI, smoking, alcohol use, hepatitis C virus co-infection, tenofovir exposure, and CT scanner types. MLWH had lower hip bone density with cortical and trabecular bone deficit compared to community-dwelling controls. © 2023 American Society for Bone and Mineral Research (ASBMR).

Cell and Tissue Specific Metabolism of Nucleoside and Nucleotide Drugs: Case Studies and Implications for Precision Medicine

Many clinically used antiviral drugs are nucleoside or nucleotide analog drugs, which have a unique mechanism of action that requires intracellular phosphorylation. This dependence on intracellular activation presents novel challenges for the discovery and development of nucleoside/nucleotide analog drugs. Contrary to many small molecule drug development programs that rely on plasma pharmacokinetics and systemic exposures, the precise mechanisms that result in efficacious intracellular nucleoside triphosphate concentrations must be understood in the process of nucleoside/nucleotide drug development. The importance is highlighted here, using the following as case studies: the herpes treatment acyclovir, the cytomegalovirus therapy ganciclovir, and human immunodeficiency virus (HIV) treatments based on tenofovir, which are also in use for HIV prophylaxis. For each drug, the specificity of metabolism that results in its activation in different cells or tissues is discussed, and the implications explored. Acyclovir's dependence on a viral enzyme for activation provides selective pressure for resistance mutations. Ganciclovir is also dependent on a viral enzyme for activation, and suicide gene therapy capitalizes on that for a novel oncology treatment. The tissue of most relevance for tenofovir activation depends on its use as treatment or as prophylaxis, and the pharmacogenomics and drug-drug interactions in those tissues must be considered. Finally, differential metabolism of different tenofovir prodrugs and its effects on toxicity risk are explored. Taken together, these examples highlight the importance of understanding tissue specific metabolism for optimal use of nucleoside/nucleotide drugs in the clinic. SIGNIFICANCE STATEMENT: Nucleoside and nucleotide analogue drugs are cornerstones in current antiviral therapy and prevention efforts that require intracellular phosphorylation for activity. Understanding their cell and tissue specific metabolism enables their rational, precision use for maximum efficacy.

HIV mortality trends among older adults in the United States, 1999-2020

BACKGROUND

Despite the progress made in managing HIV, the mortality trends among older adults in the US remains understudied. The lack of evidence in this demographic hampers the ability to implement evidence-based interventions. Our aim is to analyze the trends in HIV-related mortality among US citizens aged 65 years and above by demographic characteristics such as age, gender, race/ethnicity, and census region.

METHODS

We abstracted national mortality data from the underlying cause of death files in the CDC WONDER database. The ICD-10 Codes- B20-B24 were used to identify HIV deaths among US older adults from 1999 to 2020. Trends in age-adjusted mortality rate (AAMR) were assessed using a five-year simple moving average and Joinpoint analysis. Results were expressed as annual percentage changes (APC), average annual percentage changes, and 95% confidence intervals (CI).

RESULTS

Between 1999 and 2020, a total of 15,694 older adults died from HIV in the US (AAMR= 1.7 per 100,000; 95% CI: 1.6 - 1.7). Overall mortality trends increased at an annual rate of 1.5% (95% CI: 1.2, 1.8) from 1999 through 2020. The trends increased among Non-Hispanic Whites, stabilized among Non-Hispanic Blacks, and decreased among Hispanics from 1999 to 2020. Further, the trends increased consistently across categories of age (65 to 74 years; 75 to 84 years), sex, and census region.

CONCLUSIONS

HIV mortality among older adults in the US has risen overall from 1999 to 2020, but with varying trends by race and ethnicity. This highlights the need for enhanced public health surveillance to better understand the scope of HIV mortality among older adults and identify high-risk demographic and regional subgroups for targeted interventions. Improving timely diagnosis, managing comorbidities, and stigma surrounding HIV among older adults are crucial to reducing HIV mortality in this population.

How Do Drugs Affect the Skeleton? Implications for Forensic Anthropology

Simple Summary

Forensic anthropologists analyze human remains to assist in the identification of the deceased, predominantly by assessing age-at-death, sex, stature, ancestry and any unique identifying features. Whilst methods have been established to create this biological profile of the skeleton, these may be influenced by a number of factors. This paper, for the first time, provides an overview from a reading of the clinical and pharmacological literature to explore whether the intake of drugs can affect the skeleton and whether these may have implications for forensic anthropology casework. In effect, drugs such as tobacco, heroin, and prescription medications can alter bone mineral density, can increase the risk of fractures, destroy bone and changes to the dentition. By considering how drugs can affect the skeleton, forensic anthropologists can be aware of this when attempting to identify the deceased.

Abstract

Forensic anthropologists rely on a number of parameters when analyzing human skeletal remains to assist in the identification of the deceased, predominantly age-at-death, sex, stature, ancestry or population affinity, and any unique identifying features. During the examination of human remains, it is important to be aware that the skeletal features considered when applying anthropological methods may be influenced and modified by a number of factors, and particular to this article, prescription drugs (including medical and non-medical use) and other commonly used drugs. In view of this, this paper aims to review the medical, clinical and pharmacological literature to enable an assessment of those drug groups that as side effects have the potential to have an adverse effect on the skeleton, and explore whether or not they can influence the estimation of age-at-death, sex and other indicators of the biological profile. Moreover, it may be that the observation of certain alterations or inconsistencies in the skeleton may relate to the use of drugs or medication, and this in turn may help narrow down the list of missing persons to which a set of human remains could belong. The information gathered from the clinical and medical literature has been extracted with a forensic anthropological perspective and provides an awareness on how several drugs, such as opioids, cocaine, corticosteroids, non-steroidal anti-inflammatory drugs, alcohol, tobacco and others have notable effects on bone. Through different mechanisms, drugs can alter bone mineral density, causing osteopenia, osteoporosis, increase the risk of fractures, osteonecrosis, and oral changes. Not much has been written on the influence of drugs on the skeleton from the forensic anthropological practitioner perspective; and this review, in spite of its limitations and the requirement of further research, aims to investigate the current knowledge of the possible effects of both prescription and recreational drugs on bones, contributing to providing a better awareness in forensic anthropological practice and assisting in the identification process of the deceased.

The combined effects of age and HIV on the anatomic distribution of cortical and cancellous bone in the femoral neck among men and women

OBJECTIVE

To investigate HIV-related and age-related differences in hip bone structure in men and women.

DESIGN

Cross sectional study of bone structure and HIV serostatus.

METHODS

We used Quantitative Computed Tomography (QCT) data from the Multicenter AIDS Cohort Study (MACS) and Women's Interagency HIV Study (WIHS) to examine cortical thickness (CT) and cortical (CBMD), trabecular (TBMD), and integral (IBMD) bone mineral density across anatomic quadrants of the femoral neck in older adult MSM and women with (PWH) and without (PWOH) HIV infection. The percentage difference (%diff) in the means for CT and BMD overall and by quadrant between PWH and PWOH were estimated.

RESULTS

Among 322 MSM (median age 60 years) with bone measures, distributions were similar between HIV serostatus groups with %diff in the quadrant means ranging from -7 to -1% for CT and from -1 to 4% for BMD, and overall lower hip cortical thickness than expected. In contrast, in 113 women (median age 51 years), PWH had lower CT, IBMD and TBMD consistently across all quadrants, with differences ranging from -10 to -20% for CT, -6 to -11% for IBMD and -3 to -6% for TBMD. Estimates reached statistical significance in superoanterior quadrant for CT and IBMD and inferoposterior for CT.

CONCLUSION

Among women, PWH appear to have a thinner cortex and less dense integral bone compared with PWOH, particularly in the superior quadrants whereas MSM overall had a thinner than expected hip cortex.

The prevalence and associated factors of reduced bone mineral density (BMD) among men with suppressed viral load taking antiretroviral therapy

BACKGROUND

Reduced bone mineral density (BMD) is a frequent comorbidity observed in people living with HIV (PLHIV).

OBJECTIVE

The aim of the study is to determine the prevalence and associated factors of reduced bone mineral density (BMD) among men with suppressed viral load taking antiretroviral therapy.

METHOD

The study was conducted as a cross-sectional study design between January to April 2019. 211 patients were included in the study. Z-score at either body site between -1.0 and -2.0 or -2 or less were defined as osteopenia or osteoporosis, respectively. Multivariate logistic regression analysis was used to evaluate the factors affecting the development of reduced BMD.

RESULTS

The mean age of the patients involved in the study was 34.8 ± 7.6. Osteoporosis was detected in 21.4% and osteopenia in 44.5% of the patients. There was a significant relationship between HIV diagnosis time, ART usage duration, tenofovir disoproxil fumarate (TDF) use, TDF use in the past, total TDF usage time and decreased BMD. Multivariate logistic regression analysis showed that the likelihood of reduced bone marrow density was 67% lower among those with regular milk or dairy product intake compared to those without (OR=0.330; 95% CI = 0.12-0.92, p=0.033 ) Conclusion: There is a high prevalence of reduced BMD among PLHIV aged under 50 which is mainly confounded by HIV diagnosis time, ART usage duration and TDF usage. Although virological control has been achieved, these patients should be followed up, considering that they may have decreased BMD.

Testosterone, HIV, and cardiovascular disease risk

There has been a recent increase in the use of testosterone supplementation among young adults in the United States, despite the controversy of testosterone replacement therapy (TRT) and cardiovascular safety. The lower testosterone levels and earlier age of TRT use in persons living with HIV (PLHIV) is of particular relevance for this population because cardiovascular disease (CVD) comorbidities are known to be increased among PLHIV. There is very limited data on TRT in PLHIV, as such, in this article, we sought to compile current evidence regarding the diagnosis and management of testosterone deficiency and its link to CVD risk including among PLHIV.

Advances in the occurrence and biotherapy of osteoporosis

Osteoporosis (OP) is a bone metabolic disease, is characterized by degeneration of bone structure and decreased bone mass. It happens in more than 1/3 women and 1/5 men of over than 50 years old, which affects the health and lives of people. The main mechanism of OP is mainly that the dynamic balance between the bone formation and resorption is broken, so that bone resorption is more than bone formation. It is prone to result in bone metabolism disorder. There are many precipitating factor such as elder age, low hormone level, genetic factors and bad hobbies. At the same time, the occurrence of the OP and its complications has different degrees of impact on people's quality of life. Based on the current understanding of the OP, we summarized the etiology, current clinical drugs and potential targeting therapy for OP. Although the research have made many progress in explore what is the novel mechanism and how to improve the effect, there are still many problems in the treatment method that limit its application prospects and need to be solved. In this review, we mainly focus on the mechanism of OP and related research on the targeted treatment of OP. Hopefully, our summary will provide a reference to develop some novel strategies for the target therapy of OP.

Validation of a six-item dietary calcium screening tool among HIV patients in China

OBJECTIVE

Individuals with HIV are at increased risk for osteoporosis. A healthy diet with adequate Ca is recommended to promote bone health. However, lengthy nutritional assessments pose barriers to routine screenings in clinical practice. This study aimed to examine the validity and reproducibility of a six-item dietary Ca screening tool among Chinese individuals with HIV.

DESIGN

We conducted a two time-point study in an outpatient setting. Volunteers self-administered the six-item tool upon enrolment and again at 1-month follow-up. At baseline, participants also completed a validated FFQ and surveys regarding demographic and clinical risk factors.

SETTING

Beijing, China; Shenzhen, Guangdong, China.

PARTICIPANTS

Upon enrolment, 127 individuals with HIV participated in the study, of whom 83 completed the follow-up screening.

RESULTS

Mean age of participants was 35·2 (sd 9·3) years, average BMI was 22·8 (sd 3·8) kg/m2 and 89 % were men. Among the participants, 54·7 % reported Ca intake less than 800 mg/d. The six-item tool demonstrated fair-to-moderate relative validity with a correlation of 0·39 and 75·7 % of subjects classified in same/adjacent quartiles as the reference, and moderate-to-good reproducibility with a correlation of 0·60 and 83·1 % of subjects classified in same/adjacent quartiles. Finally, receiver operating characteristic analyses yielded a sensitivity of 87·0 % and a specificity of 39·4 % with optimised cut-off level.

CONCLUSIONS

The six-item tool presented adequate validity and reproducibility to identify individuals with low Ca intake among the target population, providing a convenient instrument for categorising Ca intake in clinical practice, prompting referrals for further assessment, and raising awareness of dietary Ca in bone disease prevention.

Influence of HIV Infection and Antiretroviral Therapy on Bone Homeostasis

The human immunodeficiency virus type 1 (HIV)/AIDS pandemic represents the most significant global health challenge in modern history. This infection leads toward an inflammatory state associated with chronic immune dysregulation activation that tilts the immune-skeletal interface and its deep integration between cell types and cytokines with a strong influence on skeletal renewal and exacerbated bone loss. Hence, reduced bone mineral density is a complication among HIV-infected individuals that may progress to osteoporosis, thus increasing their prevalence of fractures. Highly active antiretroviral therapy (HAART) can effectively control HIV replication but the regimens, that include tenofovir disoproxil fumarate (TDF), may accelerate bone mass density loss. Molecular mechanisms of HIV-associated bone disease include the OPG/RANKL/RANK system dysregulation. Thereby, osteoclastogenesis and osteolytic activity are promoted after the osteoclast precursor infection, accompanied by a deleterious effect on osteoblast and its precursor cells, with exacerbated senescence of mesenchymal stem cells (MSCs). This review summarizes recent basic research data on HIV pathogenesis and its relation to bone quality. It also sheds light on HAART-related detrimental effects on bone metabolism, providing a better understanding of the molecular mechanisms involved in bone dysfunction and damage as well as how the HIV-associated imbalance on the gut microbiome may contribute to bone disease.

Efficacy and Safety of Switching to Dolutegravir With Boosted Darunavir in Virologically Suppressed Adults With HIV-1: A Randomized, Open-Label, Multicenter, Phase 3, Noninferiority Trial: The DUALIS Study

Background

Dolutegravir (DTG) and boosted darunavir (bDRV) are potent antiretrovirals with a high resistance barrier and might be valuable switch options for people with HIV (PWH).

Methods

DUALIS, a randomized, open-label, phase 3b, noninferiority clinical trial, compared the switch to DTG + bDRV (2DR) with continuation of 2 nucleoside reverse transcriptase inhibitors (2NRTI) + bDRV (3DR). PWH with HIV RNA <50 copies/mL taking 2NRTI + bDRV (3DR) for ≥24 weeks (1 accepted blip <200 copies/mL) were randomized to either switch to DTG 50 mg + DRV 800 mg (boosted with 100 mg of ritonavir) or continue taking 3DR. The primary end point (PE) was the proportion of HIV RNA <50 copies/mL at week (W) 48. Change in NRTI backbone was not classified as failure. The estimated sample size for PE analysis was 292; the noninferiority margin was ≤-10.0%.

Results

In total, 263 subjects were randomized and treated (2DR n = 131, 3DR n = 132; 90.1% male; 89.7% Caucasian; median age [interquartile range], 48 [39-54] years). At W48, 86.3% (n = 113/131) of the 2DR subject and 87.9% (n = 116/132) of the 3DR subjects had HIV RNA <50 copies/mL; the difference between arms was -1.6% (95.48% CI, based on the adjusted alpha level accounting for the interim analysis at W24, -9.9% to +6.7%; discontinuations due to adverse events: 2DR, 4.6% [n = 6]; 3DR, 0.8% [n = 1]). Kaplan-Meier estimates of confirmed HIV RNA ≥50 copies/mL at W48 were 1.6% (n = 2) in the 2DR and 3.1% (n = 4) in the 3DR group. Development of treatment-emergent resistance was not observed.

Conclusions

Switching to DTG + bDRV was noninferior to continuing 3DR in subjects already treated with bDRV.

Comorbidity and polypharmacy among women living with HIV in British Columbia

OBJECTIVE

To characterize comorbid disease and medication burden among women living with HIV (WLWH) in British Columbia (BC), Canada.

DESIGN

We examined baseline data from 267 WLWH and 276 HIV-negative women, aged at least 19 years, enrolled in the Children and Women: Antiretrovirals and Markers of Aging (CARMA) cohort.

METHODS

Self-reported demographic, medical condition, medication, vitamin, and substance exposure data were collected at baseline CARMA study visits. We considered conditions with appropriate concomitant medications to be 'treated'. Wilcoxon rank-sum and Fisher's exact tests compared continuous and categorical variables between WLWH and HIV-negative women. Number of diagnoses, prescribed medications (excluding HIV/antiretrovirals), vitamins, and prevalence of depression/anxiety/panic disorder were compared using negative binomial and logistic regressions for continuous and binary variables, respectively.

RESULTS

WLWH were younger [median, interquartile range (IQR) 39.9, 33.6-46.9 vs. 43.6, 31.8-54.6 years; P = 0.01], attained lower education (40.5 vs. 69.6% college/university; P < 0.001), and more often currently smoked tobacco (47.9 vs. 31.9%; P < 0.001) or had income less than $15 000/year (49.0 vs. 43.1%; P < 0.001). Although younger, and despite omitting HIV infection, WLWH had a greater number of diagnoses (incidence rate ratio, 95% confidence interval 1.58, 1.38-1.81; P < 0.001), and more depression/anxiety/panic disorder vs. controls (odds ratio, 95% CI 1.86, 1.22-2.83; P = 0.004). Our model predicts that with mean BMI (26.3), WLWH and HIV-negative peers would have two comorbid diagnoses by age 30 and 60, respectively.

CONCLUSIONS

WLWH living in BC have more comorbid illness earlier in life than their HIV-negative peers, and have very high rates of depression/anxiety/panic disorder. Addressing mental health and comorbid conditions is essential to improving health outcomes among WLWH.

Antiretroviral Therapy and Bone Health

Objective: To determine the incidence of osteopenia and osteoporosis in Bulgarian human immunodeficiency virus (HIV)-infected patients.

Methods: Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry in 41 Bulgarian HIV-infected patients.

Results: Overall, 27% of patients had reduced BMD (7% osteoporosis and 20% osteopenia). There was a significant correlation between low BMD and increasing age and between low BMD and duration of antiretroviral therapy (ART) but no correlation with gender, therapy regimen or serum calcium or phosphate levels. Seventy-one percent had elevated serum cystatin C levels but there was no correlation between BMD and cystatin C levels. Serum calcium, phosphate, cystatin C and creatinine levels and the T- and Z-scores were tested for dependence on duration of therapy. Dependence was found for T- and Z-scores, (p = 0.048 and p = 0.038) but not for calcium, phosphate, cystatin C or creatinine levels. These variables were subsequently tested by means of cross-tabulation tables for correlations between pairs of parameters; no significant correlation was found between any pairs (R > 0.5 for all comparisons).

Conclusions: Significant correlations were observed between low BMD and increasing age and longer duration of ART but no relationship was observed with gender or therapy regimen.

The High Genetic Barrier of EFdA/MK-8591 Stems from Strong Interactions with the Active Site of Drug-Resistant HIV-1 Reverse Transcriptase

4'-Ethynyl-2-fluoro-2'-deoxyadenosine (EFdA/MK-8591), a nucleoside reverse transcriptase inhibitor (NRTI) under clinical trials, is a potent and promising long-acting anti-HIV type 1 (HIV-1) agent. EFdA and its derivatives possess a modified 4'-moiety and potently inhibit the replication of a wide spectrum of HIV-1 strains resistant to existing NRTIs. Here, we report that EFdA and NRTIs with a 4'-ethynyl- or 4'-cyano-moiety exerted activity against HIV-1 with an M184V mutation and multiple NRTI-resistant HIV-1s, whereas NRTIs with other moieties (e.g., 4'-methyl) did not show this activity. Structural analysis indicated that EFdA and 4'-ethynyl-NRTIs (but not other 4'-modified NRTIs), formed strong van der Waals interactions with critical amino acid residues of reverse transcriptase. Such interactions were maintained even in the presence of a broad resistance-endowing M184V substitution, thus potently inhibiting drug-resistant HIV-1 strains. These findings also explain the mechanism for the potency of EFdA and provide insights for further design of anti-HIV-1 therapeutics.

How do skeletons with HIV present? A study on the identified CAL Milano Cemetery Skeletal Collection

With the Human Immunodeficiency Virus (HIV) infection and Acquired Immune Deficiency Syndrome (AIDS) pandemic, the study of HIV/AIDS on bones has become of pivotal interest for research in bone pathologies, forensic applications (especially in the matter of identification when confronted to antemortem data) and medical purposes. In this paper, we document and discuss the macroscopic lesions found on the skeletons of nine individuals with known HIV, including four with known AIDS, coming from the identified CAL Milano Cemetery Skeletal Collection. As a result, several types of lesions were observed on bones: periosteal new bone formation, dental lesions, thickening of the frontal diploë, destructive localized porosity and evidence of trauma. None of the lesions reported can be directly linked to HIV because the virus does not directly affect bones in a macroscopic way. However, HIV/AIDS-induced infections and inflammations and HIV-related risk factors may leave bone markers. The differential diagnosis of each of the lesions noted in this research and its potential link to HIV or AIDS was discussed. Although it is not possible to diagnose HIV on bare bones, this was not the focus of this study. To our knowledge, no anthropological study has ever been performed on known HIV individuals. With this paper, we present for the first time skeletons with known HIV.

Bone turnover markers in HIV-infected women on tenofovir-based antiretroviral therapy

Background

Tenofovir disoproxil fumarate (TDF) antiretroviral therapy is associated with disruption of the bone turnover process.

Objectives

The objective of this study was to determine the association between tenofovir (TFV) plasma concentration and various bone turnover markers and compare these markers in HIV-infected women and HIV-uninfected controls.

Method

A cross-sectional sub-study included 30 HIV-infected women on TDF and 30 HIV-uninfected matched participants. Serum calcium (SrCa), serum phosphate (SrP), C-terminal telopeptide (CTx), parathyroid hormone (PTH), alkaline phosphatase (ALP), C-reactive protein (CRP), vitamin D (VitD) and bone mineral density (BMD) were measured. Plasma TFV was assayed on HPLC-MS/MS. The statistical tests applied were Mann-Whitney test, unpaired t-test, analysis of covariance, regression and correlation analysis.

Results

In HIV-infected women, no correlation existed between plasma TFV concentration and CTx, PTH, ALP, SrCa, SrP, VitD or BMD (p > 0.05). After adjusting for smoking and alcohol use, ALP (p < 0.001), CTx (p = 0.027) and PTH (p = 0.050) were significantly higher in HIV-infected compared to HIV-uninfected women. Women with TFV concentration ≥ 120 ng/mL had higher PTH concentrations (p = 0.037) compared to those with ≤ 100 ng/mL. Significant correlations between SrCa and PTH and SrCa and SrP including CTx and PTH (p < 0.05) were present in HIV-uninfected women while absent in HIV-infected counterparts (p > 0.05).

Conclusion

The results indicate possible increased bone turnover at higher TFV concentrations. The normal regular bone turnover processes in HIV-infected women on TDF therapy are altered. Larger studies are warranted to confirm these results.

Body composition in HIV-infected patients receiving highly active antiretroviral therapy

BACKGROUND

The development of combination antiretroviral therapies (cART) represents a significant advance in the treatment of (human immunodeficiency virus) HIV infection. However, several studies report that a large percentage of individuals with HIV, particularly those receiving cART, present body composition differences compared with the general population. The aim of this study was to explore body composition differences by dual-energy X-ray absorptiometry (DEXA), among HIV-positive patients receiving cART, in comparison to healthy controls.

METHODS

The cross-sectional study included 60 HIV-infected patients (all under 50 years old). We analyzed the association of antiretroviral medication use and different HIV-related factors, to the body composition parameters.

RESULTS

Our cohort had significantly lower fat mass and lower bone mass compared to non HIV-infected persons. Median time since HIV infection diagnosis was 5 years (interquartile range, [IQR], 2-10.25) and viral suppression was achieved in 49 (81.66%) patients. Treatment with protease inhibitors (PIs) was strongly correlated with low fat mass, reduced lean mass and loss of bone mineral density. Nucleoside reverse transcriptase inhibitors (NRTIs)-containing treatment was associated with decrease of lean tissue mass (LM). The prevalence of osteopenia was 41.67% at the lumbar spine (L1-L4) and 36.7% at the hip. We found osteoporosis in 10% of the patients at the lumbar spine. Reduced bone mass was associated, in the patient group, with the duration of PIs use and with smoking (in the males group).

CONCLUSION

In our research, HIV-infected individuals compared to healthy controls had body composition differences, including fat mass atrophy and reduced bone mineral content.

Lipid-lowering effect and changes in estimated cardiovascular risk after switching to a tenofovir-containing regimen for the treatment of HIV-infected patients

Tenofovir could have a direct lipid-lowering effect. The aim of our retrospective study was to investigate changes in cardiovascular risk after switching from a tenofovir-sparing to a tenofovir-containing backbone. Lipid parameters and cardiovascular risk [calculated using 10-years Framingham Risk Score (FRS) and 5-years DAD Risk Score (DRS)] were analysed at baseline and after three months. 273 patients were enrolled. After switching, significant decreases in total cholesterol (TC) (-8.2mg/dl, p < 0.001), LDL (-8.7mg/dl, p < 0.001) and DRS (mean -0.26%, p < 0.001) were observed, while a reduction in FRS was only observed in patients with pre-switch high TC or medium-high (>10%) FRS. Pre-switch factors associated with DRS reduction were higher TC, abacavir, new generation protease inhibitors, while zidovudine predicted an increase of DRS. Our results suggest that the improvement of lipid parameters observed after switching to a tenofovir-containing backbone could lead to a significant reduction in predicted cardiovascular risk, which became more evident in subjects with higher cardiovascular risk.

Alveolar bone in human immunodeficiency virus infection: is it changed by long-term antiretroviral therapy?

BACKGROUND

Previous studies have reported that human immunodeficiency virus (HIV) infection and antiretroviral therapy (ART) can lead to osteoporosis in HIV-infected individuals. However, their effects on alveolar bone are not well established. The objective of this study was to measure the alveolar bone mineral density (BMD) of HIV-infected patients, with and without antiretroviral therapy (ART), in comparison with that of HIV-free individuals, and to determine factors associated with the BMD of alveolar bone.

METHODS

A cross-sectional study was performed in non-HIV-infected individuals and HIV-infected individuals, with and without ART. Medical status and clinical data were recorded. Periapical radiographs of maxillary and mandibular right premolars were analysed for changes of alveolar BMD based on HIV/ART status. Other factors associated with the changes of alveolar BMD were explored using a parametric multivariate analysis of covariance (MANCOVA).

RESULTS

One-hundred and one HIV-infected individuals receiving ART (age range: 23-57 years; median age 39 years), 58 receiving no ART (age range: 20-59 years; median age 34 years) and 50 HIV-negative individuals (age range: 19-59 years; median age 36 years) were enrolled. Neither HIV status nor use of ART was significantly associated with the changes of alveolar BMD.

CONCLUSION

Although osteoporosis has been reported in HIV-infected individuals treated with ART, alveolar BMD does not appear to be changed as a result of the infection, or use of ART.

Validation Protocol of Vitamin D Supplementation in Patients with HIV-Infection

Hypovitaminosis D and secondary hyperparathyroidism are frequent among HIV-infected patients. As there are no data about the best supplementation therapy both in treatment and in maintenance, we conducted an observational study of 300 HIV-infected patients for whom vitamin D and parathormone (PTH) had been measured in order to validate a protocol of vitamin D supplementation in patients with HIV-infection. Patients with vitamin D deficiency (defined as 25(OH)D < 10 ng/mL), insufficiency (defined as 25(OH)D < 20 ng/mL), or hyperparathyroidism (PTH > 65 pg/mL) were supplemented with cholecalciferol 16.000IU (0.266 mg) weekly (if deficiency) or fortnightly (if insufficiency or high PTH levels). Rates of normalization of 25(OH)D (levels above 20 ng/mL) and PTH levels (<65 pg/mL) were analyzed. Multivariate analysis of factors related to normalization was carried out. With a median follow-up of 2 years, 82.1% of patients with deficiency and 83.9% of cases with insufficiency reached levels above 20 ng/mL. However, only 67.2% of individuals with hyperparathyroidism at baseline reached target levels (<65 pg/mL). Independent factors for not achieving PTH objective were tenofovir (TDF) and protease inhibitors use. In HIV-infected patients with hypovitaminosis, the protocol of cholecalciferol supplementation normalized vitamin D levels regardless of antiretroviral regimen in a high proportion of patients but it was less effective to correct hyperparathyroidism.

Dolutegravir monotherapy as treatment de-escalation in HIV-infected adults with virological control: DoluMono cohort results

BACKGROUND

The potential toxicity of long-term antiretroviral therapy (ART) requires ongoing investigation of novel strategies for treatment of HIV-infected patients. Monotherapy with the integrase inhibitor (INSTI) dolutegravir (DTG) may offer a favourable safety profile. Additionally, DTG has a high barrier of resistance, crucial for successful maintenance of virological control. However, published data is sparse.

METHODS

Retrospective, single-centre cohort study. We enrolled patients on suppressive ART who were switched to DTG monotherapy in routine clinical practice and fulfilled the following inclusion criteria: HIV RNA level <50 copies/ml for ≥6 months at time of switch (one blip <200 copies/ml with re-suppression accepted), no known INSTI resistance or prior INSTI failure, no replicative HBV infection and no history of AIDS.

RESULTS

We identified 31 patients with 24-weeks of follow-up data. Previous ART included a non-nucleoside reverse transcriptase inhibitor, a boosted protease inhibitor or an INSTI in 32%, 6% and 61% of patients, respectively. At week 24, HIV RNA remained <50 copies/ml in all but two patients (94%). One patient chose to discontinue DTG monotherapy and another developed confirmed virological failure (HIV RNA 538 copies/ml) with new INSTI mutations (Q148H/G140S). Immune status and renal and metabolic function showed no statistically significant changes, apart from a significant decrease in gamma-glutamyl transferase.

CONCLUSIONS

De-escalating to DTG monotherapy in selected patients might be a safe and feasible option. However, in one case evolution of INSTI resistance was observed. Further studies should assess particular risk factors for DTG monotherapy failure. In the meanwhile, caution is warranted.

Low bone mineral density and associated risk factors in HIV-infected patients

BACKGROUND

Aging of persons with human immunodeficiency virus (HIV) resulted in high rates of osteopenia and osteoporosis. Multiple cohort studies have reported an increased prevalence of bone demineralization among HIV-infected individuals. The aim of this study was to evaluate bone mineral density (BMD) and risk factors for osteopenia/osteoporosis among HIV-positive patients attending the National Institute for Infectious Diseases "Prof.Dr. Matei Balș", Bucharest, Romania.

METHODS

We performed a cross-sectional study that enrolled 60 patients with HIV. The association between BMD and lifestyle habits (smoking), body mass index (BMI), nadir cluster of differentiation 4 (CD4) cell count, current CD4 cell count, HIV viral load and history of combination antiretroviral therapy (cART) were investigated. The BMD was measured at the lumbar spine, hips and total body using dual-energy X-ray absorptiometry (DEXA).

RESULTS

In the present study, DEXA evaluation showed an overall prevalence of osteoporosis of 16.66% (ten patients) and a prevalence of osteopenia of 48.33% (29 patients). In men, low BMI and cigarette smoking showed significant association with the diagnosis of lumbar spine demineralization (p=0.034 and p=0.041, respectively). Duration of exposure to cART classes in relation to BMD was also evaluated. The use of non-nucleoside reverse-transcriptase inhibitors (NNRTIs) was associated with low lumbar spine BMD in all patients (p=0.015). Reduced BMD was significantly associated with protease inhibitors (PIs)-containing treatment (p=0.043) in women.

CONCLUSION

At lumbar spine DEXA, male gender was statistically associated with reduced BMD. At the left hip Ward's area, decreased BMD T scores were significantly associated with aging. The reduced BMD was higher in patients receiving PI- or NNRTI-containing regimens.

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

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

Hypogonadism in the HIV-infected man

Androgen deficiency occurs frequently in men with human immunodeficiency virus (HIV) infection. Antiretroviral treatments had reduced the prevalence of male hypogonadism. The pathogenesis of testosterone (T) deficiency in HIV is multifactorial. Several mechanisms have been proposed; among them, drugs, fat redistribution, and a poor health status could explain the mechanism leading to gonadotropins inhibition and hypogonadotropic hypogonadism. The diagnosis of hypogonadism in HIV-infected men should be made based on clinical symptoms and a specific workup including T measurement. The interpretation of the results of biochemical testing is more difficult in men with HIV due to several confounding factors. T treatment should be offered to HIV-infected men with documented clinical hypogonadism and symptoms, especially if they are losing lean mass.

Focal bone lesions in HIV-positive patient treated with tenofovir

Background

Tenofovir is a widely used antiviral drug for the treatment of HIV and HBV infection. Although its side effects on renal function and bone metabolism are well known, there are no reports on focal bone lesions caused by this drug. Our case suggests this new, unusual but important scenario.

Case presentation

We report on a 46-year-old HIV-positive man treated with an antiretroviral regimen containing tenofovir who suddenly developed localized inflammatory bone lesions. The examinations performed ruled out all the disorders commonly associated with this clinical pattern, and the patient’s conditions improved only after the suspension of tenofovir.

Conclusions

The case study suggests a rare but severe adverse event, which should be taken into account when physicians treat HIV-positive patients with focal inflammatory bone lesions

Osteoporosis in Human Immunodeficiency Virus Patients - An Emerging Clinical Concern

The advent of highly active anti-retroviral therapy (HAART) has significantly improved the survival of human immunodeficiency virus (HIV)-infected patients transforming the HIV infection from a fatal illness into a manageable chronic disease. As the number of older HIV-infected individuals increases, several ageing-related co-morbidities including osteopenia/osteoporosis and fractures have emerged. Patients exposed to HIV infection and its treatment may develop fragility fractures with potential significant impact on quality of life and survival. However, the awareness of HIV-related skeletal fragility is still relatively low and most HIV-infected patients are not investigated for osteoporosis and treated with anti-osteoporotic drugs in daily clinical practice. This article reviews the literature data on osteoporosis and osteopenia in HIV infection, focusing on the pathophysiological, clinical and therapeutic aspects of fragility fractures.

Role of inflammation in HIV-1 disease progression and prognosis

Inflammation and immune activation have been thrust to center stage in the understanding of HIV-1 disease pathogenesis and progression. Early work demonstrated that heightened levels of immune activation correlated with the extent of CD4 + T cell death in lymphoid tissue; however, this concept was not incorporated into the general view of disease pathogenesis. Since these early studies, the extension of life for patients on combination antiretroviral therapies (cART) has heralded a new era of non-AIDS-related diseases and incomplete restoration of immune function. The common link appears to be ongoing inflammation and immune activation. Thus, despite good control of viral loads, persons living with HIV (PLWH) remain at increased risk of inflammatory-associated complications such as cardiovascular disease and certain cancers. HIV-specific mechanisms as well as non-specific generalized responses to infection contribute to ongoing activation of the immune system. An early loss of gastrointestinal (GI) tract mucosal integrity, the pro-inflammatory cytokine milieu, co-infections and marked destruction of lymph node architecture are all factors contributing to the ongoing activation of the immune system as well as impaired immune recovery. It is becoming increasingly evident that the CD4 count and viral load do not provide a complete picture of the underlying state of the immune system. Heightened levels of inflammatory markers have been shown to predict increased mortality and other adverse events. Therefore, it will be important to incorporate these markers into management algorithms as soon as possible. This is particularly relevant in resource-poor countries where difficulties in cART roll-out and access are still encountered and, therefore, a mechanism for prioritizing individuals for therapy would be of value. This review will focus on the closely inter-related concepts of immune activation and inflammation. Both are broad concepts involving the interaction of various key players in the immune system. Importantly, immune activation promotes inflammation and thrombosis and similarly, inflammation and thrombosis induce immune activation. These concepts are thus intricately linked. Studies highlighting the potentially harmful effects of ongoing inflammation/immune activation are reviewed and the contributions of the GI tract "damage" and other co-infections such as CMV are explored. The complications resulting from persistent immune activation include enhanced CD4 + T cell death, lymphoid tissue destruction, and various pathologies related to chronic inflammation. Ultimately, we envision that the long-term management of the disease will incorporate both the identification and the amelioration of the potentially harmful effects of ongoing immune activation and inflammation.

High prevalence of low bone mass and associated factors in Korean HIV-positive male patients undergoing antiretroviral therapy

Introduction

Low bone mass is prevalent in HIV-positive patients. However, compared to Western countries, less is known about HIV-associated osteopenia in Asian populations.

Methods

We performed a cross-sectional survey in Seoul National University Hospital from December 2011 to May 2012. We measured bone mineral density using central dual energy X-ray absorptiometry, with consent, in male HIV-positive patients, aged 40 years and older. Diagnosis of low bone mass was made using International Society for Clinical Densitometry Z-score criteria in the 40–49 years age group and World Health Organization T-score criteria in the >50-year age group. The data were compared with those of a community-based cohort in Korea.

Results

Eighty-four HIV-positive male patients were included in this study. Median age was 49 (interquartile range [IQR], 45–56) years, and median body mass index (BMI) was 22.6 (IQR, 20.9–24.4). Viral suppression was achieved in 75 (89.3%) patients and median duration of antiretroviral therapy was 71 (IQR, 36–120) months. The overall prevalence of low bone mass was 16.7% in the 40–49 years age group and 54.8% in the>50 years age group. Our cohort had significantly lower bone mass at the femur neck and total hip than HIV-negative Koreans in the 40–49 years age group. Low bone mass was significantly associated with low BMI, and a high level of serum carboxy-terminal collagen crosslinks, but was not associated with antiretroviral regimen or duration of antiretroviral therapy.

Conclusions

Low bone mass is prevalent in Korean HIV-positive males undergoing antiretroviral therapy, and may be associated with increased bone resorption.

Association of Blood Biomarkers of Bone Turnover in HIV-1 Infected Individuals Receiving Anti-Retroviral Therapy (ART)

OBJECTIVE

To evaluate the association of bone turnover biomarkers with blood levels of alkaline phosphatase (ALP), bone-specific alkaline phosphatase (BAP), osteocalcin (OC), tartrate-resistant acid phosphatase (TRAP), parathyroid hormone (PTH), and other blood markers in HIV-1 infected men receiving anti-retroviral therapy (ART). Advances in the treatment of HIV-1 infection have extended the life span of HIV-1 infected individuals. However, these advances may come at the price of metabolic side effects and bone disorders, including premature osteopenia, osteoporosis and osteonecrosis.

METHODS

Analyses of Ostase BAP, osteocalcin, and TRAP in blood were measured in three groups of MACS participants: 35 HIV-1 infected men on ART (A); 35 HIV-1- infected men not on ART (B); and 34 HIV-1 uninfected men (C).

RESULTS

The mean and standard deviation results for groups A, B, and C were 19.7 ± 6.56, 17.2 ± 3.96, and 16.9 ± 5.78 for ostase BAP; 7.9 ± 9.53, 8.5 ± 8.30, and 5.5 ± 1.65 for osteocalcin; and 3.9 ± 1.04, 3.1 ± 0.81, and 2.5 ± 0.59 for TRAP, respectively. Simple and multivariate analyses showed significant differences in mean TRAP and BAP concentrations between the three groups. In addition strong correlations between blood levels of Ostase BAP and TRAP (r=0.570, p=0.0004), and between blood levels of Ostase BAP and PTH (r=0.436, P=0.0098) for HIV-1 infected men on ART were observed.

CONCLUSION

New strategies for measurement of blood and urine biochemical markers of bone formation and resorption during bone turnover can be useful for clinical monitoring of treatment of HIV-1 infected patients. Recently developed methods for measuring serum levels of TRAP and Ostase BAP represent superior laboratory tools for assessing the hyperactivity of osteoclasts, osteoblasts and bone loss in HIV-1 infected individuals receiving ART. Measurements of TRAP and BAP as bone turnover biomarkers are economical and are important for monitoring bone metabolism during ART and the need for osteoporosis treatment.

HIV protease inhibitors induce senescence and alter osteoblastic potential of human bone marrow mesenchymal stem cells: beneficial effect of pravastatin

HIV-infected patients receiving antiretroviral therapy present an increased prevalence of age-related comorbidities, including osteoporosis. HIV protease inhibitors (PIs) have been suspected to participate to bone loss, but the mechanisms involved are unknown. In endothelial cells, some PIs have been shown to induce the accumulation of farnesylated prelamin-A, a biomarker of cell aging leading to cell senescence. Herein, we hypothesized that these PIs could induce premature aging of osteoblast precursors, human bone marrow mesenchymal stem cells (MSCs), and affect their capacity to differentiate into osteoblasts. Senescence was studied in proliferating human MSCs after a 30-day exposure to atazanavir and lopinavir with or without ritonavir. When compared to untreated cells, PI-treated MSCs had a reduced proliferative capacity that worsened with increasing passages. PI treatment led to increased oxidative stress and expression of senescence markers, including prelamin-A. Pravastatin, which blocks prelamin-A farnesylation, prevented PI-induced senescence and oxidative stress, while treatment with antioxidants partly reversed these effects. Moreover, senescent MSCs presented a decreased osteoblastic potential, which was restored by pravastatin treatment. Because age-related bone loss is associated with increased bone marrow fat, we also evaluated the capacity of PI-treated MSCs to differentiate into adipocyte. We observed an altered adipocyte differentiation in PI-treated MSCs that was reverted by pravastatin. We have shown that some PIs alter osteoblast formation by affecting their differentiation potential in association with altered senescence in MSCs, with a beneficial effect of statin. These data corroborate the clinical observations and allow new insight into pathophysiological mechanisms of PI-induced bone loss in HIV-infected patients.

Delayed emergence of HIV-1 variants resistant to 4'-ethynyl-2-fluoro-2'-deoxyadenosine: comparative sequential passage study with lamivudine, tenofovir, emtricitabine and BMS-986001

BACKGROUND

4'-Ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) contains an ethynyl moiety and the 3'-hydroxyl and exerts highly potent activity against various HIV type-1 (HIV-1) strains including multi-drug-resistant variants.

METHODS

Comparative selection passages against EFdA, lamivudine (3TC), tenofovir disoproxil fumarate (TDF), emtricitabine (FTC) or BMS-986001 (Ed4T) were conducted using a mixture of 11 highly multi-drug-resistant clinical HIV-1 isolates (HIV11MIX) as a starting virus population.

RESULTS

Before selection, HIV11MIX was sensitive to EFdA with a 50% inhibitory concentration (IC50) of 0.032 μM, less susceptible to TDF and Ed4T with IC50s of 0.57 and 2.6 μM, respectively, and highly resistant to 3TC and FTC with IC50s>10 μM. IC50s of TDF against HIV11MIX exposed to EFdA and TDF for 17 (HIV11MIX(EFdA-P17)) and 14 (HIV11MIX(TDF-P14)) passages were 8 and >10 μM, respectively, while EFdA remained active against HIV11MIX(EFdA-P17) and HIV11MIX(TDF-P14) with IC50s of 0.15 and 0.1 μM, respectively. Both selected variants were highly resistant against zidovudine, 3TC, Ed4T and FTC (IC50 values >10 μM).

CONCLUSIONS

The present data demonstrate that HIV11MIX developed resistance more rapidly against 3TC, FTC, TDF and Ed4T than against EFdA and that EFdA remained substantially active against TDF- and EFdA-selected variants. Thus, EFdA has a favourable resistance profile and represents a potentially promising new-generation nucleoside reverse transcriptase inhibitor.