Tenofovir treatment of primary osteoblasts alters gene expression profiles: implications for bone mineral density loss

Tenofovir induced Fanconi syndrome in a middle age African female from Kenya, East Africa: Case report and brief literature review

This case presentation highlights the need to routinely monitor renal function in patients on Tenofovir Disoproxil Fumarate (TDF) due to its side effect of proximal tubule dysfunction.

Abstract

This is a case presentation of a 50-year-old African female who had been on a Tenofovir based regimen for 12 years and developed Fanconi syndrome. She recovered after discontinuation of the Tenofovir Disoproxil Fumarate (TDF).

The anti-HIV drug abacavir stimulates β-catenin activity in osteoblast lineage cells

Bone mineral density (BMD) loss in people living with HIV occurs with the initiation of combined antiretroviral therapy (cART), particularly with tenofovir disoproxil fumarate (TDF) containing cART. Switching from TDF to abacavir (ABC) or dolutegravir (DTG) leads to increased BMD. Whether BMD gains are due to cessation of TDF or anabolic effects of ABC or DTG is unclear. We investigated the effects of ABC and DTG on osteoblast lineage cells in vitro and in vivo. Primary human osteoblasts and male C57BL/6 mice were treated with individual antiretrovirals (ARVs) or a combination of ABC/DTG/lamivudine (3TC). Nearly all ARVs and cART inhibited osteogenic activity in vitro. Due to the importance of Wnt/β-catenin in bone formation, we further investigated ARV effects on the Wnt/β-catenin pathway. ABC, alone and as part of ABC/DTG/3TC, increased osteoblastic β-catenin activity as indicated by increased TOPFlash activity, hypo-phosphorylated (active) β-catenin staining, and β-catenin targeted gene expression. Mice treated with TDF had decreased lumbar spine BMD and trabecular connectivity density in the vertebrae, while those treated with ABC/DTG/3TC reduced cortical area and thickness in the femur. Mice treated with ABC alone had no bone structural changes, increased circulating levels of the bone formation marker, P1NP, and elevated expression of the Wnt/β-catenin target gene, Lef1, in osteocyte enriched samples. Further, bones from ARV-treated mice were isolated to evaluate ARV distribution. All ARVs were detected in the bone tissue, which was inclusive of bone marrow, but when bone marrow was removed, only TDF, ABC, and DTG were detected at ~0.1% of the circulating levels. Overall, our findings demonstrate that ABC activates Wnt/β-catenin signaling, but whether this leads to increased bone formation requires further study. Assessing the impact of ARVs on bone is critical to informing ARV selection and/or discovery of regimens that do not negatively impact the skeleton.

Effects of Tenofovir Disoproxil Fumarate on Bone Quality beyond Bone Density-A Scoping Review of the Literature

Tenofovir disoproxil fumarate (TDF) is a widely used pharmacological agent for the treatment of human immunodeficiency virus infection. While prolonged exposure to TDF has been associated with a decrease in bone mineral density (BMD) and increased fracture risk, limited discussion exists on its effects on various aspects of bone quality. This scoping review aims to provide a comprehensive overview of the impact of TDF on bone quality beyond BMD. A literature search was conducted using the PubMed and Scopus databases to identify studies investigating the effects of TDF on bone quality. Original research articles written in English, irrespective of study type or publication year, were included in the review. Seven articles met the inclusion criteria. Findings indicate that prolonged exposure to TDF adversely affects bone microarchitecture and strength, impeding fracture healing and skeletal microdamage repair. The observed effects suggest a complex interplay involving bone cell signalling, cytokines and bone remodelling processes as potential mechanisms underlying TDF's impact on bone quality. As a conclusion, TDF impairs bone remodelling and microarchitecture by influencing dynamic bone cell behaviour and signalling pathways. Future studies should delve deeper into understanding the intricate negative effects of TDF on bone and explore strategies for reversing these effects.

The effect of daily oral PrEP use during pregnancy on bone mineral density among adolescent girls and young women in Uganda

Introduction

Oral pre-exposure prophylaxis (PrEP) is recommended during pregnancy for at-risk cisgender women. Pregnancy is known to impede bone growth and tenofovir-based PrEP may also yield detrimental changes to bone health. Thus, we evaluated the effect of PrEP use during pregnancy on bone mineral density (BMD).

Methods

We used data from a cohort of women who were sexually active, HIV-negative, ages 16-25 years, initiating DMPA or choosing condoms for contraception and enrolled in the Kampala Women's Bone Study. Women were followed quarterly with rapid testing for HIV and pregnancy, PrEP dispensation, and adherence counseling. Those who became pregnant were counseled on PrEP use during pregnancy per national guidelines. BMD of the neck of the hip, total hip, and lumbar spine was measured using dual-energy x-ray absorptiometry at baseline and annually. We compared the mean percent change in BMD from baseline to month 24.

Results

Among 499 women enrolled in the study, 105 pregnancies occurred in 90 women. At enrollment, the median age was 20 years (IQR: 19-21) and 89% initiated PrEP. During pregnancy, 67% of women continued using PrEP and PrEP was dispensed in 64% of visits. BMD declined significantly in women using PrEP during pregnancy compared to women who were not pregnant nor used PrEP: relative BMD change was -2.26% (95% CI: -4.63 to 0.11, p = 0.06) in the femoral neck, -2.57% (95% CI: -4.48 to -0.66, p = 0.01) in total hip, -3.06% (95% CI: -5.49 to -0.63, p = 0.001) lumbar spine. There was no significant difference in BMD loss when comparing PrEP-exposed pregnant women to pregnant women who never used PrEP. Women who became pregnant were less likely to continue PrEP at subsequent study visits than women who did not become pregnant (adjOR: 0.25, 95% CI: 0.16-0.37, p < 0.001). Based on pill counts, there was a 62% reduction in the odds of high PrEP adherence during pregnancy (adjOR = 0.38, 95% CI: 0.27-0.58, p < 0.001).

Conclusion

Women who used PrEP during pregnancy experienced a similar reduction in BMD as pregnant women with no PrEP exposure, indicating that BMD loss in PrEP-using pregnant women is largely driven by pregnancy and not PrEP.

Incidence of complications and revision surgery in HAART compliant HIV patients undergoing primary total hip and knee arthroplasty: an institutional review

INTRODUCTION

Human immunodeficiency virus (HIV) positive patients are at high risk for osteonecrosis along with age-related osteoarthritis, resulting in a high number of joint reconstruction surgeries at younger ages in these immunosuppressed patients. Few previous studies have reported on patient outcomes in HAART (highly active antiretroviral therapy) compliant patients undergoing primary arthroplasty. The aim of this study is to report one institution's overall rate of complications and revision in HAART-compliant patients after primary hip and knee arthroplasty.

METHODS

A retrospective chart review was performed spanning a 4 year period. This study included 50 primary joint arthroplasty patients diagnosed with HIV including 13 TKA (total knee arthroplasty) and 37 THA (total hip arthroplasty) with a prior diagnosis of HIV infection. Preoperative CD4 count and viral loads were recorded. Charts were reviewed for post-operative complications including infection and revision.

RESULTS

The were a total of 11 postoperative complications (22%). There were 3 cases (6%) of soft tissue infection, 3 cases (6%) of implant loosening, 2 cases (4%) of dislocation, 1 case (2%) of lower extremity weakness, 1 case (2%) of venous thrombosis, and 1 case (2%) of arthrofibrosis. Of all patients, there were 6 cases of revision in this cohort (12%), 5 of which were aseptic etiology. All 3 infected patients had a history of IVDU. Two of these infected patients resolved with IV antibiotics while 1 underwent two-stage revision (2%). Patients that experienced post-operative complications had significantly elevated preoperative CD4 levels (983 versus 598, p = 0.003).

CONCLUSION

Arthroplasty is a viable option for HAART-compliant patients. Most previous studies showing a higher risk for deep tissue infection and revision in HIV patients have not accounted for modern HAART. Our results show that compliance with HAART has vastly improved the outcomes of arthroplasty in these patients, while a history of IVDU is likely the largest risk factor for infection in this population.

Mechanical loading attenuated negative effects of nucleotide analogue reverse-transcriptase inhibitor TDF on bone repair via Wnt/β-catenin pathway

The nucleotide analog reverse-transcriptase inhibitor, tenofovir disoproxil fumarate (TDF), is widely used to treat hepatitis B virus (HBV) and human immunodeficiency virus infection (HIV). However, long-term TDF usage is associated with an increased incidence of bone loss, osteoporosis, fractures, and other adverse reactions. We investigated the effect of chronic TDF use on bone homeostasis and defect repair in mice. In vitro, TDF inhibited osteogenic differentiation and mineralization in MC3T3-E1 cells. In vivo, 8-week-old C57BL/6 female mice were treated with TDF for 38 days to simulate chronic medication. Four-point bending test and μCT showed reduced bone biomechanical properties and microarchitecture in long bones. To investigate the effects of TDF on bone defect repair, we utilized a bilateral tibial monocortical defect model. μCT showed that TDF reduced new bone mineral tissue and bone mineral density (BMD) in the defect. To verify whether mechanical stimulation may be a useful treatment to counteract the negative bone effects of TDF, controlled dynamic mechanical loading was applied to the whole tibia during the matrix deposition phase on post-surgery days (PSDs) 5 to 8. Second harmonic generation (SHG) of collagen fibers and μCT showed that the reduction of new bone volume and bone mineral density caused by TDF was reversed by mechanical loading in the defect. Immunofluorescent deep tissue imaging showed that chronic TDF treatment reduced the number of osteogenic cells and the volume of new vessels. In addition, chronic TDF treatment inhibited the expressions of periostin and β-catenin, but increased the expression of sclerostin. Both negative effects were reversed by mechanical loading. Our study provides strong evidence that chronic use of TDF exerts direct and inhibitory impacts on bone repair, but appropriate mechanical loading could reverse these adverse effects.

Prevalence and Risk Factors of Low Bone Mineral Density in HIV/AIDS Patients: A Chinese Cross-Sectional Study

INTRODUCTION

Our study aimed to investigate the prevalence and risk factors of low bone mineral density (BMD) among HIV/AIDS patients in China.

METHODS

We performed a cross-sectional analysis of HIV-infected patients from October 2017 to August 2020. Demographic information, clinical data, and serum parameters were obtained. Univariable and multiple logistic regression analyses were performed.

RESULTS

A total of 1143 patients were included. In the ART-naive group, low BMD was diagnosed in 19.2% (117/608), including osteoporosis in 1.0% (6/608) and osteopenia in 18.3% (111/608). In the ART group, low BMD was diagnosed in 32.2% (231/717), including osteoporosis in 2.4% (17/717) and osteopenia in 29.8% (214/717). Using multivariate analysis, we identified age older than 50 years, body mass index < 18.5 kg/m2, and treatment based on tenofovir disoproxil fumarate as independent risk factors for low BMD. Low high-density lipoprotein cholesterol was a protective factor for low BMD. Among low BMD participants, the most common number of low BMD sites for a patient to have was 4 (33.6%, 117/348).

CONCLUSION

We confirmed a high prevalence of low BMD and osteoporosis in HIV/AIDS patients, and we identified age older than 50 years, low body mass index, and a treatment based on tenofovir disoproxil fumarate as risk factors for low BMD. Low high-density lipoprotein cholesterol had a protective effect against low BMD. Among low BMD patients, patients most commonly had 4 sites with low BMD, which has been associated with fracture risk. In addition, bone changes to L1 can present before low BMD diagnosis and may be a potentially useful indicator that low BMD is developing.

Osteopenia in a young man associated with the use of tenofovir disoproxil fumarate

Tenofovir disoproxil fumarate is a recommended first-line therapy for patients with chronic hepatitis B, although the frequent Tenofovir disoproxil fumarate related adverse drug reactions are nephrotoxicity and bone toxicity. We described the case of a 21-year-old Han Chinese male patient with chronic hepatitis B with tenofovir disoproxil fumarate-associated osteopenia. The patient presented osteopenia at the site of his femoral neck with bone mineral density 0.865g/cm2 (Z = -1.9) in January 2020. Nine months after switching to TAF, bone mineral density at left femoral neck improved to 0.978g/cm2 (Z = -1.0) in September 2020. Bone mineral density of this patients was normal in January 2021. This is the first report in very young man presenting tenofovir disoproxil fumarate-associated osteopenia.

Tenofovir Modulates Semaphorin 4D Signaling and Regulates Bone Homeostasis, Which Can Be Counteracted by Dipyridamole and Adenosine A2A Receptor

Semaphorin 4D (Sema4D) is a neurotrophin that is secreted by osteoclasts and binds to its receptor PlexinB1 on osteoblasts to inhibit their differentiation and function. Adenosine A2A activation inhibits osteoclast Sema4D-mediated secretion, diminishes inflammatory osteolysis and prevents bone loss following tenofovir (one of the most used antivirals in HIV). Therefore, tenofovir might activate Sema4D signaling to alter bone turnover. Female C57Bl/6/A2AKO mice were ovariectomized and treated with saline (control), tenofovir 75 mg/Kg/day, dipyridamole 25 mg/Kg/day or a combination for 5 weeks and long bones were prepared for histology. Primary murine-induced osteoclast/osteoblast were challenged with tenofovir/dipyridamole 1 μM each, and the expression of Sema4D/PlexinB1, RhoA/ROCK/IGF1R was studied by RT-PCR, Western blot and immunostaining. In vivo tenofovir showed an increased expression of Sema4D when compared to control mice, and dipyridamole reverted the expression in an A2A-dependent manner. In vitro, tenofovir increases Sema4D expression and secretion in osteoclast precursors, and pre-treatment with dipyridamole reverted this effect. pRhoA and ROCK1 activation were increased and IRS1/IGF1R expression was diminished by tenofovir in the Vav3/ARHGAP18 mechanism in osteoblast precursors and reverted by dipyridamole in an A2A-dependent manner. This suggests that tenofovir increases bone loss by activation of Sema4D/PlexinB1 signaling, which inhibits osteoblast differentiation. Agents that increase local adenosine concentrations, such as dipyridamole, might prevent bone loss following the inhibition of this pathway.

Changing trends in lipid profile and biomarkers of renal function and bone metabolism before and after switching from tenofovir disoproxil fumarate to tenofovir alafenamide: a prospective observational study

Background

Antiretrovirals, including tenofovir, can suppress human immunodeficiency virus (HIV) infection but cannot completely eradicate it. Patients with HIV infection are administered antiretroviral drugs over a long term; thus, managing consequent adverse drug reactions, such as renal dysfunction and bone mineral loss, is important. Currently, highly sensitive biomarkers that can detect adverse drug reactions early have not been well studied.

Methods

This single-center, prospective, observational study explored changes in the biomarkers of renal function, bone metabolism, and lipid profile before and after switching from tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide (TAF) in patients with HIV infection.

Results

All 31 enrolled patients had been treated with antiretrovirals for more than 5 years. The rate of proteinuria decreased significantly after starting TAF-containing antiretroviral regimen. The urinary liver-type fatty acid binding protein (L-FABP)/creatinine ratio was significantly decreased at 3 and 6 months after switching to TAF compared with that before switching to TAF (− 0.5 μg/g Cr at 3 months, and − 0.8 μg/g Cr at 6 months; p < 005 for both at 3 and 6 months). The urinary N-terminal telopeptide (NTx)/creatinine ratio decreased over the study period, and the ratios were significantly different between 3 and 6 months (− 11 nmol/mmol Cr at 3 months, − 15.2 nmol/mmol Cr at 6 months; p = 0.0069 at 3 months, p < 0.0001 at 6 months). Low density lipoprotein-cholesterol level significantly increased at 3 (+ 26 mg/dL) and 6 months (+ 13 mg/dL) compared with that at the baseline (p < 0.0001).

Conclusions

Switching from TDF to TAF decreased the levels of renal and bone biomarkers, such as urinary L-FABP and NTx, but increased low density lipoprotein-cholesterol levels. Future studies should evaluate if these biomarkers, such as urinary L-FABP and NTx, truly detect serious adverse drug reactions early.

Administration of zoledronic acid alleviates osteoporosis in HIV patients by suppressing osteoclastogenesis via regulating RANKL expression

Background

Osteoporosis is a common phenomenon in HIV patients on tenofovir treatment, but its underlying mechanisms remain to be explored.

Methods

Quantitative real-time PCR was performed to analyze the expression of miR-302, miR-101, miR-145 and osteoclast-specific genes in the serum of HIV patients treated with tenofovir and ZOL. ELISA was used to evaluate the expression of RANKL, SMAD3 and PRKACB in the serum of these patients. Luciferase assay was carried out to explore the inhibitory effects of miR-302, miR-101 and miR-145 on the expression of PRKACB, RANKL and SMAD3, respectively. Western blot was used to examine the expression of genes involved in NF‑κB and JNK signaling pathways.

Results

ZOL treatment significantly suppressed the expression of CTx and osteocalcin in HIV patients treated with tenofovir. The BMD loss of HIV patients treated with tenofovir was effectively hindered by ZOL treatment. Mechanistically, the expression of miR-302, miR-101, miR-145, RANKL, SMAD3 and PRKACB in the serum was remarkably activated by ZOL treatment. Luciferase assays showed that miR-302, miR-101 and miR-145 effectively suppressed the expression of PRKACB, RANKL and SMAD3, respectively, through binding to their 3′ UTR. Furthermore, ZOL treatment notably restored the normal expression of osteoclast‑specific genes while activating NF‑κB and JNK signaling pathways.

Conclusion

The findings of this study demonstrated that administration of ZOL suppressed the expression of RANKL via modulating signaling pathways of miR-101-3p/RANKL, miR-302/PRKACB/RANKL and miR-145/SMAD3/RANKL. Furthermore, down-regulated expression of RANKL by ZOL treatment alleviated osteoporosis in HIV-positive subjects treated with tenofovir.

Long-term efficacy and safety of nucleos(t)ides analogues in patients with chronic hepatitis B

Nucleos(t)ide analogues with high barrier to resistance are regarded as the principal therapeutic option for chronic hepatitis B (CHB). Treatment with entecavir (ETV), tenofovir disoproxil (TDF) and the later released tenofovir alafenamide (TAF) is highly effective at controlling hepatitis B virus (HBV) infection and, in the vast majority of patients, is well tolerated. No significant differences in viral suppression have been described among the different regimens, although an earlier achievement in biochemical response has been suggested first under TDF and recently under TAF. High barrier to resistance NAs rarely achieve hepatitis B surface antigen sero-clearance, and therefore should be maintained life-long in most cases. This has increased concerns about treatment-related toxicity, especially in patients under TDF with additional risk factors for kidney and bone impairment. TAF has shown a better bone and kidney safety profile than TDF, although it is not yet available worldwide due to its higher cost. Emergence of adverse events should be monitored since treatment-switch to ETV/TAF seems to be effective and safe in HBV mono-infected subjects. Finally, although an effective antiviral treatment leads to a clear improvement in clinical outcome of CHB patients; the risk of developing hepatocellular carcinoma (HCC) is not completely avoided with viral suppression. Whether tenofovir-based regimens provide any additional benefit over ETV in HCC prevention remains unclear and requires further investigation.

Tooth loss associated with the use of tenofovir disoproxil fumarate

WHAT IS KNOWN AND OBJECTIVE

The frequent tenofovir disoproxil fumarate (TDF)-related adverse drug reactions (ADRs) are nephrotoxicity and bone toxicity; however, tooth-related ADRs of TDF have not been reported. We describe the case of a 41-year-old Han Chinese man with chronic hepatitis B with TDF-associated tooth loss.

CASE SUMMARY

He presented with halitosis, gingival swelling and tooth loss after TDF use. After excluding the possibility of other drug-related ADRs, TDF was considered a possible cause and switched with tenofovir alafenamide fumarate (TAF). After 6 months, the oral symptoms disappeared, with no additional tooth loss.

WHAT IS NEW AND CONCLUSION

This is the first report of such ADRs. The ADR score was 7, indicating tooth loss as a potential TDF-related ADR.

Bone Update: Is It Still an Issue Without Tenofovir Disoproxil Fumarate?

PURPOSE OF REVIEW

In the era of modern bone-friendly antiretroviral therapy (ART) regimens for people living with HIV (PLWH), this review discusses the research gaps and management concerns that remain for individuals who have already been exposed to ART with negative effects on bone metabolism, especially children and adolescents who have not acquired peak bone mass, and older adults who have additional risk factors for fracture.

RECENT FINDINGS

Data now support the use of avoidance of TDF and use of bone-friendly regimens that include integrase strand transfer inhibitors in PLWH with increased risk of fracture for either ART initiation or switch. Despite significant advances in our understanding of ART choice for PLWH with regard to bone health, additional diagnostic tests to determine fracture risk and management strategies beyond ART choice are necessary, especially in vulnerable PLWH populations, such as children and adolescents and older adults.

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.

Probiotics protect against tenofovir-induced mandibular bone loss in mice by rescuing mandible-derived mesenchymal stem cell proliferation and osteogenic differentiation

BACKGROUND

Tenofovir disoproxil fumarate (TDF), a primary antiretroviral agent used to treat AIDS, triggers systematic bone loss. However, the effect of TDF on osteopenia or osteoporosis in the jaw remains unclear. TDF-induced bone loss in the jaw, if any, likely involves mandible-derived mesenchymal stem cells (MMSCs), which play a key role in jawbone metabolism. Probiotics prevent long bone loss, and could prove efficacious in treating TDF-induced mandibular bone loss.

OBJECTIVES

To determine whether TDF triggers mandibular bone loss, elucidate the underlying mechanisms, and study the effect of Lactobacillus rhamnosus GG (LGG) on TDF-induced bone loss in the jaw.

METHODS

Tenofovir disoproxil fumarate was administered orally daily and LGG semiweekly from eight weeks to the end of the study (LGG group) to male C57BL6/J mice. The mice were sacrificed, and body weight (BW) and serum Ca and P were measured. Mandibular histomorphometry was evaluated by micro-CT. MMSCs and LGG culture supernatants were isolated, and MMSC proliferation and ALP production when treated with different concentrations of LGG supernatant and/or TDF were measured. Relative abundance of osteogenic markers was assessed by qPCR.

RESULTS

Orally administered LGG protected against bone mass loss and deterioration of bone microarchitecture and increased serum P levels. The BW of the TDF group was highest among the study groups. TDF partially impaired osteogenesis and proliferation of MMSCs. LGG culture supernatant rescued MMSC osteogenesis and proliferation, and osteogenic gene expression.

CONCLUSIONS

Lactobacillus rhamnosus GG protected against tenofovir-induced mandibular bone loss in mice by rescuing MMSC proliferation and osteogenesis.

Continued Interest and Controversy: Vitamin D in HIV

PURPOSE OF REVIEW

Vitamin D (VitD) deficiency is highly prevalent among HIV-infected individuals. Given the overlapping risk for several chronic disease and immunomodulatory outcomes from both long-standing HIV and VitD deficiency, there is great interest in clarifying the clinical role of VitD for this population.

RECENT FINDINGS

Recent studies have expanded our knowledge regarding the epidemiology and mechanisms of VitD deficiency-associated outcomes in the setting of HIV. Clinical trials focusing on VitD supplementation have demonstrated a positive impact on bone mineral density in subgroups of HIV-infected individuals initiating ART or on suppressive ART regimens; however, significant heterogeneity exists between studies and data are less consistent with other clinical outcomes. Further research is needed to clarify uncertainly in several domains, including identifying patients at greatest risk for poor outcomes from VitD deficiency, standardizing definitions and measurement techniques, and better quantifying the benefits and risks of VitD supplementation across different demographic strata for skeletal and extra-skeletal outcomes.

Improvement of bone mineral density and markers of proximal renal tubular function in chronic hepatitis B patients switched from tenofovir disoproxil fumarate to tenofovir alafenamide

Tenofovir alafenamide (TAF) is a novel prodrug that reduces tenofovir plasma levels by 90% compared to tenofovir disoproxil fumarate (TDF), resulting in decreased bone mineral density (BMD) loss and renal toxicity. We aimed to study changes in BMD and markers of renal function of chronic hepatitis B (CHB) patients previously treated with TDF who were switched to TAF in as early as 12 weeks. This was a prospective single-arm open-label study of 75 CHB patients treated with TDF 300 mg daily who were switched to TAF 25 mg daily and followed for 24 weeks. All patients had been treated with TDF for at least 12 months and had HBV DNA <21 IU/mL at the time of switch. BMD and markers of renal function were taken on the day of switch and repeated after 12 and 24 weeks of TAF treatment. Hip and spine bone mineral density significantly increased from baseline to week 12 (+12.9% and +2.4%, respectively, P < 0.01). There were significant decreases in urinary beta-2-microglobulin to creatinine and retinol-binding protein to creatinine ratios by week 12 (P < 0.01 for both). Mean estimated glomerular filtration rate (GFR) did not change. Tubular reabsorption of phosphate was decreased at week 24 (P < 0.05). In conclusion, CHB patients previously treated with TDF experienced significant improvement in bone density and some markers of renal tubular function and as early as 12 weeks after switching to TAF. Bone density changes associated with TDF may not be entirely related to renal handling of phosphate.

Experience of hormone replacement therapy in postmenopausal women living with HIV

Objective

To assess the uptake of hormone replacement therapy in women living with HIV (WLHIV) in particular acceptability, response to treatment and compliance.

Study design

Retrospective review of menopausal women attending a HIV medical gynaecology clinic in a tertiary referral London Hospital between 1 January 2011 and 31 December 2016.

Main outcome measures

Patient demographics, presenting symptoms, uptake of hormone replacement therapy, type of hormone replacement therapy used and bone density assessment findings at presentation.

Results

Seventy-three HIV patients were evaluated. Of them 64 (87%) were of black ethnicity and 9 (13%) were of white ethnicity. The commonest presenting complaints were vasomotor symptoms (40/73, (55%)) followed by low mood/irritability (20/73, (27%)). When offered hormone replacement therapy, this was accepted by 28/53 (52%) in WLHIV. The commonest regimen prescribed was transdermal oestradiol/micronised progesterone. A total of 22/24 (91%) women of black ethnicity reported good symptom control if they had started hormone replacement therapy, with 4/24 (17%) subsequently discontinuing it; 3/4 (75%) of white women reported good symptom control with hormone replacement therapy, with no one discontinuing it. The commonest reason for discontinuation was irregular bleeding. Of WLHIV who had a bone density assessment, 15/25 (60%) had osteopenia while 2/25 (8%) had osteoporosis.

Conclusion

Our data show that only around 50% WLHIV accepted hormone replacement therapy when offered and a high proportion of these women discontinued it. Further research is needed to explore the reason leading to low uptake and high rates of stopping hormone replacement therapy. In addition, there is a need to increase awareness of the benefits of hormone replacement therapy in WLHIV both in the context of preventing osteoporosis and menopausal symptom management.

Daily HIV pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate-emtricitabine reduced Streptococcus and increased Erysipelotrichaceae in rectal microbiota

Daily PrEP is highly effective at preventing HIV-1 acquisition, but risks of long-term tenofovir disoproxil fumarate plus emtricitabine (TDF-FTC) include renal decline and bone mineral density decrease in addition to initial gastrointestinal side effects. We investigated the impact of TDF-FTC on the enteric microbiome using rectal swabs collected from healthy MSM before PrEP initiation and after 48 to 72 weeks of adherent PrEP use. The V4 region of the 16S ribosomal RNA gene sequencing showed that Streptococcus was significantly reduced from 12.0% to 1.2% (p = 0.036) and Erysipelotrichaceae family was significantly increased from 0.79% to 3.3% (p = 0.028) after 48–72 weeks of daily PrEP. Catenibacterium mitsuokai, Holdemanella biformis and Turicibacter sanguinis were increased within the Erysipelotrichaceae family and Streptococcus agalactiae, Streptococcus oralis, Streptococcus mitis were reduced. These changes were not associated with host factors including PrEP duration, age, race, tenofovir diphosphate blood level, any drug use and drug abuse, suggesting that the observed microbiome shifts were likely induced by daily PrEP use. Long-term PrEP resulted in increases of Catenibacterium mitsuokai and Holdemanella biformis, which have been associated with gut microbiome dysbiosis. Our observations can aid in characterizing PrEP’s side effects, which is likely to improve PrEP adherence, and thus HIV-1 prevention.

Tenofovir alafenamide as compared to tenofovir disoproxil fumarate in the management of chronic hepatitis B with recent trends in patient demographics

Tenofovir alafenamide (TAF) has recently been approved for chronic hepatitis B (CHB). It is more stable than tenofovir disoproxil fumarate (TDF) in the plasma and can provide similar efficacy with lower circulating concentration in patients with hepatitis B virus (HBV) infection. Areas covered: This synopsis will review the current anti-HBV standard practice and the changing epidemiology of CHB, specifically the controversies surrounding the renal and bone safety associated with TDF use in the context of an aging CHB population. We will review data from phase 3 registration trials, which demonstrated TAF was not inferior to TDF in antiviral efficacy for both HBeAg-positive and HBeAg-negative patients, while associated with less reduction in the estimated glomerular filtration rate and bone mineral density. Expert commentary: Current data supports the use of TAF as one of the first-line antiviral agents for general CHB patients without hepatic decompensation. However, more real-world data with long-term observation are needed to better define the role of TAF among other oral regimens. Additional studies are also needed to evaluate the efficacy and safety of TAF in special populations such as those with impaired hepatic function, existing impaired renal and/or bone function, and in pregnant women.

Associations of Low Vitamin D and Elevated Parathyroid Hormone Concentrations With Bone Mineral Density in Perinatally HIV-Infected Children

BACKGROUND

Perinatally HIV-infected (PHIV) children have, on average, lower bone mineral density (BMD) than perinatally HIV-exposed uninfected (PHEU) and healthy children. Low 25-hydroxy vitamin D [25(OH)D] and elevated parathyroid hormone (PTH) concentrations may lead to suboptimal bone accrual.

METHODS

PHIV and PHEU children in the Pediatric HIV/AIDS Cohort Study had total body (TB) and lumbar spine (LS) BMD and bone mineral content (BMC) measured by dual-energy x-ray absorptiometry; BMD z-scores (BMDz) were calculated for age and sex. Low 25(OH)D was defined as ≤20 ng/mL and high PTH as >65 pg/mL. We fit linear regression models to estimate the average adjusted differences in BMD/BMC by 25(OH)D and PTH status and log binomial models to determine adjusted prevalence ratios of low 25(OH)D and high PTH in PHIV relative to PHEU children.

RESULTS

PHIV children (n = 412) were older (13.0 vs. 10.8 years) and more often black (76% vs. 64%) than PHEU (n = 207). Among PHIV, children with low 25(OH)D had lower TB-BMDz [SD, -0.38; 95% confidence interval (CI), -0.60 to -0.16] and TB-BMC (SD, -59.1 g; 95% CI, -108.3 to -9.8); high PTH accompanied by low 25(OH)D was associated with lower TB-BMDz. Among PHEU, children with low 25(OH)D had lower TB-BMDz (SD, -0.34; 95% CI, -0.64 to -0.03). Prevalence of low 25(OH)D was similar by HIV status (adjusted prevalence ratio, 1.00; 95% CI, 0.81 to 1.24). High PTH was 3.17 (95% CI, 1.25 to 8.06) times more likely in PHIV children.

CONCLUSIONS

PHIV and PHEU children with low 25(OH)D may have lower BMD. Vitamin D supplementation trials during critical periods of bone accrual are needed.

Bone and the Immune System

Osteoporosis increases fracture risk, a cause of crippling morbidity and mortality. The immunoskeletal interface (ISI) is a centralization of cell and cytokine effectors shared between skeletal and immune systems. Consequently, the immune system mediates powerful effects on bone turnover. Physiologically, B cells secrete osteoprotegerin (OPG), a potent anti-osteoclastogenic factor that preserves bone mass. However, activated T cells and B cells secrete pro-osteoclastogenic factors including receptor activator of Nuclear factor-kappaB (NF-kB) ligand (RANKL), Interleukin (IL)-17A, and tumor necrosis factor (TNF)-α promoting bone loss in inflammatory states such as rheumatoid arthritis. Recently, ISI disruption has been linked to osteoporosis in human immunodeficiency virus (HIV) infection/acquired immunodeficiency syndrome (AIDS), where elevated B cell RANKL and diminished OPG drive bone resorption. HIV-antiretroviral therapy paradoxically intensifies bone loss during disease reversal, as immune reconstitution produces osteoclastogenic cytokines. Interestingly, in estrogen deficiency, activated T cells secrete RANKL, TNF, and IL-17A that amplify bone resorption and contribute to postmenopausal osteoporosis. T cell-produced TNF and IL-17A further contribute to bone loss in hyperparathyroidism, while T cell production of the anabolic Wingless integration site (Wnt) ligand, Wnt10b, promotes bone formation in response to anabolic parathyroid hormone and the immunomodulatory costimulation inhibitor cytotoxic T lymphocyte-associated protein-4-IgG (abatacept). These findings provide a window into the workings of the ISI and suggest novel targets for future therapeutic interventions to reduce fracture risk.

Bone Loss in HIV Infection

Human immunodeficiency virus (HIV) infection is an established risk factor for low bone mineral density (BMD) and subsequent fracture, and treatment with combination antiretroviral therapy (cART) leads to additional BMD loss, particularly in the first 1-2 years of therapy. The prevalence of low BMD and fragility fracture is expected to increase as the HIV-infected population ages with successful treatment with cART. Mechanisms of bone loss in the setting of HIV infection are likely multifactorial, and include viral, host, and immune effects, as well as direct and indirect effects of cART, particularly tenofovir disoproxil fumarate (TDF) and the protease inhibitors (PIs). Emerging data indicate that BMD loss following cART initiation can be mitigated by prophylaxis with either long-acting bisphosphonates or vitamin D and calcium supplementation. In addition, newer antiretrovirals, particularly the integrase strand transfer inhibitors and tenofovir alafenamide (TAF), are associated with less intense bone loss than PIs and TDF. However, further studies are needed to establish optimal bone sparing cART regimens, appropriate screening intervals, and preventive measures to address the rising prevalence of fragility bone disease in the HIV population.

Viability of primary osteoblasts after treatment with tenofovir alafenamide: Lack of cytotoxicity at clinically relevant drug concentrations

Tenofovir alafenamide (TAF) is a phosphonoamidate prodrug of the nucleotide HIV reverse transcriptase inhibitor tenofovir (TFV). TAF is approved for the treatment of HIV-1 infection as part of the single-tablet regimen containing elvitegravir, cobicistat, emtricitabine, and TAF. When dosed once-daily, TAF results in approximately 90% lower levels of plasma TFV and a 4-fold increase in intracellular TFV-diphosphate (TFV-DP) in PBMCs compared with the TFV prodrug tenofovir disoproxil fumarate (TDF). Several antiretrovirals, including TDF, have been associated with bone mineral density decreases in patients; the effect of clinically relevant TAF concentrations on primary osteoblast viability was therefore assessed in vitro. Studies in PBMCs determined that a 2-hour TAF exposure at concentrations similar to human plasma Cmax achieved intracellular TFV-DP levels comparable to those observed after the maximum recommended human dose of 25 mg TAF. Comparable intracellular TFV-DP levels were achieved in primary osteoblasts with 2-hour TAF exposure daily for 3 days at concentrations similar to those used for PBMCs (100-400 nM). No change in cell viability was observed in either primary osteoblasts or PBMCs. The mean TAF CC50 in primary osteoblasts after 3 days of daily 2-hour pulses was >500 μM, which is >1033 times higher than the TAF maximum recommended human dose plasma Cmax. In summary, primary osteoblasts were not preferentially loaded by TAF compared with PBMCs, with comparable TFV-DP levels achieved in both cell types. Furthermore, there was no impact on osteoblast cell viability at clinically relevant TAF concentrations.

Tenofovir and bone health

PURPOSE OF REVIEW

With continued improvements to the antiviral efficacy and tolerability of antiretroviral therapy, long-term safety of antiretroviral therapy has become paramount. Low bone mineral density and fragility fractures are more common in HIV-infected individuals than in the general population. The aims of this review are to describe potential mechanisms underlying the adverse effects of tenofovir on bone, clinical studies of tenofovir disoproxil fumarate (TDF) and bone, and more recent bone data on tenofovir alafenamide.

RECENT FINDING

Several studies have demonstrated an approximately 1-3% greater bone mineral density loss with TDF compared with other agents. Recent studies with tenofovir alafenamide have shown improved bone (and renal) safety with similar virologic efficacy when compared to TDF.

SUMMARY

Given these findings, TDF-containing regimens may be gradually replaced with non-TDF containing regimens for the treatment of HIV infection, especially in those at higher risk for fragility fracture.

Physiological and pathophysiological bone turnover - role of the immune system

Osteoporosis develops when the rate of osteoclastic bone breakdown (resorption) exceeds that of osteoblastic bone formation, which leads to loss of BMD and deterioration of bone structure and strength. Osteoporosis increases the risk of fragility fractures, a cause of substantial morbidity and mortality, especially in elderly patients. This imbalance between bone formation and bone resorption is brought about by natural ageing processes, but is frequently exacerbated by a number of pathological conditions. Of importance to the aetiology of osteoporosis are findings over the past two decades attesting to a deep integration of the skeletal system with the immune system (the immuno-skeletal interface (ISI)). Although protective of the skeleton under physiological conditions, the ISI might contribute to bone destruction in a growing number of pathophysiological states. Although numerous research groups have investigated how the immune system affects basal and pathological osteoclastic bone resorption, recent findings suggest that the reach of the adaptive immune response extends to the regulation of osteoblastic bone formation. This Review examines the evolution of the field of osteoimmunology and how advances in our understanding of the ISI might lead to novel approaches to prevent and treat bone loss, and avert fractures.

Drug safety evaluation of oral tenofovir disoproxil fumarate-emtricitabine for pre-exposure prophylaxis for human immunodeficiency virus infection

INTRODUCTION

Tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) are nucleoside reverse transcriptase inhibitors approved as pre-exposure prophylaxis (PrEP) against human immunodeficiency virus (HIV). Prophylactic TDF-based regimens have been shown to reduce the risk of HIV infection by 74 to 92% among participants with detectable drug levels. Adverse events observed in clinical trials include nausea, elevated creatinine and liver enzymes, and decreased bone mineral density.

AREAS COVERED

This article reviews the pharmacology, pharmacokinetics, and the safety profile of TDF and FTC used as PrEP for HIV infection.

EXPERT OPINION

TDF-FTC can have a large impact in preventing HIV infections among high risk individuals when taken daily. Although TDF-FTC is associated with adverse events, they can be minimized with clinician-guided monitoring.

Bone Mineral Density Changes Among Young, Healthy African Women Receiving Oral Tenofovir for HIV Preexposure Prophylaxis

BACKGROUND

Limited data exist on effect of tenofovir disoproxil fumarate (TDF) when used for preexposure prophylaxis (PrEP) on bone mineral density (BMD) in HIV-negative women. We evaluated the effect of daily oral TDF and emtricitabine/TDF compared with placebo on BMD among women enrolled in an HIV-1 PrEP trial.

METHODS

HIV-uninfected women in Uganda and Zimbabwe had BMD measurements of lumbar spine (LS) and total hip (TH) by dual-energy x-ray absorptiometry at baseline and every 24 weeks for 48 weeks of active treatment and for 48 weeks after discontinuation of study medication. Plasma tenofovir levels were assessed every 12 weeks for the first 48 weeks.

RESULTS

Of 518 women enrolled, 432 had dual-energy x-ray absorptiometry results at baseline and week 48. In the primary analysis, no significant differences in percent BMD change in hip or spine between arms observed, likely because of low product adherence. Among the subset with tenofovir detection in 75%-100% of plasma samples, the mean percent BMD change from baseline to week 48 in the LS was 1.4% lower for TDF or emtricitabine/TDF recipients than for placebo (P = 0.002) and TH BMD was 0.9% lower (P = 0.018). BMD changes from end of active treatment to 48 weeks were significantly greater in the active arm participants compared with placebo participants with a net difference of approximately +0.9% at the LS (P = 0.007) and +0.7% (P = 0.003) at the TH.

CONCLUSIONS

TDF-containing oral PrEP resulted in small but significant reversible decreases in hip and spine BMD among young African women.

Bone mineral density decline according to renal tubular dysfunction and phosphaturia in tenofovir-exposed HIV-infected patients

INTRODUCTION

The mechanisms underlying the effect of tenofovir disoproxil fumarate (TDF) on the decline of bone mineral density (BMD) have not been established, especially the effect of renal tubular dysfunction.

METHODS

Longitudinal study of 90 patients with two successive dual X-ray absorptiometry scans after evaluation of serum and urinary parameters (proteinuria, albuminuria, phosphaturia, uricosuria, glycosuria, β-2-microglobulin, and retinol-binding protein).

RESULTS

After a median of 38 months on TDF, osteopenia at spine and hip was observed in 49 and 48%, and osteoporosis in 9 and 2%, respectively. There was a lineal correlation between BMD at femoral neck and time on TDF (Spearman's rho = -0.27; P = 0.01). One or more tubular abnormalities were observed in 80% of cases (hyperphosphaturia, 50%). A lower BMD correlated with phosphaturia (r = -0.25; P = 0.03), even with phosphataemia within normal limits. In fact, patients with previous improvement in phosphaturia had better BMD at inclusion (Spearman's rho = -0.33; P < 0.01). A second dual X-ray absorptiometry, after a median of 40.8 months (33.8-45.1; 627.7 patients-year on TDF), showed additional BMD reduction at hip in 50% of cases (36% with bone loss >3%), a decline associated with phosphaturia (β, -0.31; P = 0.01) or number of tubular abnormalities (β, -0.41; P = 0.01), but also with use of boosted protease inhibitors (β, -0.47; P = 0.03) and BMD at inclusion (β, -0.33; P = 0.03).

CONCLUSION

Chronic abnormal phosphaturia explains, at least in part, progressive bone loss during TDF therapy. These data suggest that tubular dysfunction leads to an altered equilibrium between phosphataemia, phosphaturia, and bone as mechanism of progressive BMD decline.

Different Impact Of Antiretroviral Drugs On Bone Differentiation In An In Vitro Model

Recently increasing emphasis is placed on preventive health and management of chronic comorbidities avoiding long-term toxicities of antiretroviral therapy (ART). Drawing from this background we decided to use the Saos-2, osteosarcoma cell line, as a cellular model, to evaluate the effects of some antiretroviral drugs such as abacavir (ABC), tenofovir (TDF), efavirenz (EFV), etravirine (ETR), and darunavir (DRV), on bone differentiation related pathways. According to our observation, treatment with TDF and ABC affects the ability of the cells to produce calcium deposits with a reduced expression of type I collagen gene and p21 mRNA, also increasing the activity of Wnt3a related pathway. On the other hand treatment with EFV and DRV was not related to any significant reduction of calcium deposits but displayed a decrease in the expression of Wnt3a at day 14 and Type I Collagen at day 7 compared with untreated cells, even if this last down regulation was not confirmed at day 14. Instead ETR administration to Saos-2 cells increases the calcium deposits collagen type I production, as a result of Wnt3a mRNA overexpression, and of an upregulation of collagen type I expression, being also the only drug able to increase the expression of p21 cdk inhibitor as further marker of terminal differentiation. In summary these data suggest the potential negative interference of TDF and ABC on bone differentiation. DRV and EFV partially affect collagen type I production, instead ETR facilitates a positive bone balance as a result of an increased osteoblasts terminal differentiation.

Bone Disease in HIV: Recommendations for Screening and Management in the Older Patient

Availability of potent antiretroviral therapy (ART) has resulted in markedly improved survival for people with human immunodeficiency virus (HIV) infection, as well as an aging HIV population. Increasing morbidity from age-related conditions has resulted in the need to understand the complex roles HIV and its treatment play in the pathogenesis of these conditions. Bone disease and fragility fractures are conditions that occur more frequently in HIV. It is therefore recommended that risk assessment for fragility fracture using the Fracture Risk Assessment Tool (FRAX(®)) algorithm, and low bone mass by dual energy X-ray absorptiometry (DXA) scan, be performed in all patients with HIV infection over the age of 50 years and in those with a history of fragility fracture, and should be repeated every 2-3 years. Because many HIV experts believe that HIV infection and its treatment is a secondary cause of osteoporosis, it should be included as such in the FRAX(®) assessment tool. Management of osteoporosis in HIV infection should follow the same guidelines as that in the general population. Attention to lifestyle factors, including vitamin D replacement, should be emphasized. Whether cessation of tenofovir- or protease inhibitor-based ART regimens should be considered prior to bisphosphonate treatment is currently unknown and should only occur in patients with active alternative ART regimens. The use of bisphosphonates has been shown to be safe and effective in HIV patients, and while there is limited data on second-line osteoporosis regimens, there is no reason to suggest they would not be effective in people with HIV.

Effects on vitamin D, bone and the kidney of switching from fixed-dose tenofovir disoproxil fumarate/emtricitabine/efavirenz to darunavir/ritonavir monotherapy: a randomized, controlled trial (MIDAS)

BACKGROUND

Efavirenz (EFV) has been associated with reductions in vitamin D (25[OH]D) and tenofovir (TDF) with increased bone turnover, reductions in bone mineral density (BMD) and renal tubular dysfunction. We hypothesized that switching from fixed-dose TDF/emtricitabine (FTC)/EFV to darunavir/ritonavir monotherapy (DRV/r) might increase 25(OH)D and BMD, and improve renal tubular function.

METHODS

Subjects with HIV RNA <50 copies/ml on TDF/FTC/EFV for ≥6 months were randomized 1:1 to ongoing TDF/FTC/EFV or DRV/r (800/100 mg once daily) for 48 weeks. The primary end point was change from baseline in 25(OH)D at week 48. Secondary end points included changes in BMD, bone turnover markers and renal tubular function.

RESULTS

A total of 64 subjects (86% male, 66% white, mean [sd] CD4(+) T-cell count 537.3 [191.5]/mm(3)) were analysed. After adjustment for baseline 25(OH)D and demographics, at week 48 DRV/r monotherapy was associated with a +3.6 (95% CI 0.6, 6.6) ng/ml increase in 25(OH)D compared to TDF/FTC/EFV (P=0.02). DRV/r monotherapy was associated with an increase in BMD (+2.9% versus -0.003% at the neck of femur and +2.6% versus +0.008% at the lumbar spine for DRV/r versus TDF/FTC/EFV; P<0.05 for all) and reductions in bone biomarkers compared with those remaining on TDF/FTC/EFV. No significant difference in renal tubular function was observed. Reasons for discontinuation in the DRV/r arm included side effects (n=4) and viral load rebound (n=3), all of which resolved with DRV/r discontinuation or regimen intensification.

CONCLUSIONS

Switching from TDF/FTC/EFV to DRV/r in patients with suppressed HIV RNA resulted in significant improvements in 25(OH)D and bone biomarkers, and a 2-3% increase in BMD.

Role of T-cell reconstitution in HIV-1 antiretroviral therapy-induced bone loss

HIV infection causes bone loss. We previously reported that immunosuppression-mediated B-cell production of receptor activator of NF-κB ligand (RANKL) coupled with decline in osteoprotegerin correlate with decreased bone mineral density (BMD) in untreated HIV infection. Paradoxically, antiretroviral therapy (ART) worsens bone loss although existing data suggest that such loss is largely independent of specific antiretroviral regimen. This led us to hypothesize that skeletal deterioration following HIV disease reversal with ART may be related to T-cell repopulation and/or immune reconstitution. Here we transplant T cells into immunocompromised mice to mimic ART-induced T-cell expansion. T-cell reconstitution elicits RANKL and TNFα production by B cells and/or T cells, accompanied by enhanced bone resorption and BMD loss. Reconstitution of TNFα- or RANKL-null T-cells and pharmacological TNFα antagonist all protect cortical, but not trabecular bone, revealing complex effects of T-cell reconstitution on bone turnover. These findings suggest T-cell repopulation and/or immune reconstitution as putative mechanisms for bone loss following ART initiation.

Hemin activation of innate cellular response blocks human immunodeficiency virus type-1-induced osteoclastogenesis

The normal skeletal developmental and homeostatic process termed osteoclastogenesis is exacerbated in numerous pathological conditions and causes excess bone loss. In cancer and HIV-1-infected patients, this disruption of homeostasis results in osteopenia and eventual osteoporesis. Counteracting the factors responsible for these metabolic disorders remains a challenge for preventing or minimizing this co-morbidity associated with these diseases. In this report, we demonstrate that a hemin-induced host protection mechanism not only suppresses HIV-1 associated osteoclastogenesis, but it also exhibits anti-osteoclastogenic activity for non-infected cells. Since the mode of action of hemin is both physiological and pharmacological through induction of heme oxygenase-1 (HO-1), an endogenous host protective response to an FDA-licensed therapeutic used to treat another disease, our study suggests an approach to developing novel, safe and effective therapeutic strategies for treating bone disorders, because hemin administration in humans has previously met required FDA safety standards.

Bone health in HIV-infected children, adolescents and young adults: a systematic review

BACKGROUND

Children and adolescents, who either acquire HIV infection perinatally, from contaminated blood products or via sexual transmission early in life, have the greatest cumulative exposure to the negative direct and indirect effects of HIV infection and ART on bone, which may lead to increased lifetime risk for osteoporosis and fracture. We conducted a systematic review to evaluate the literature on bone health in children and adolescents with HIV.

METHODS

We performed a comprehensive search of the Medline, Scopus, and Cochrane Library databases (up to April 1, 2014) for studies that reported on bone imaging or bone fractures in HIV-infected children, adolescents, or young adults.

RESULTS

A total of 32 publications met our inclusion criteria. Seventeen studies were cross-sectional and 15 were longitudinal. The majority of studies were conducted in high-income countries, three in middle-income countries and none in low-income countries. Overall, the studies we reviewed indicate that measures of bone mass are reduced, with increased prevalence of low BMD in children and adolescents with HIV. However, the studies are highly variable with respect to comparison sources, measurement methods, adjustment techniques for body size or growth retardation, and highlighted risk factors, including aspects related to medication exposures as well as the effects of HIV infection per se.

CONCLUSION

HIV infection appears to be associated with decreased bone accrual throughout childhood and adolescence. Initial studies indicate that sub-optimal bone accrual may be persistent and result in reduced peak bone mass, an important determinant of future risk of osteoporosis and fracture. Important areas for future research include evaluation of bone mass, bone quality and fracture risk across the life course among those with early-life infection with HIV, particularly in resource-limited settings where the majority of children with HIV live.

Assessment of bone mineral density in tenofovir-treated patients with chronic hepatitis B: can the fracture risk assessment tool identify those at greatest risk?

BACKGROUND

Tenofovir disoproxil fumarate (TDF) is an established nucleotide analogue in the treatment of chronic hepatitis B. Bone mineral density loss has been described in TDF-treated patients with human immunodeficiency virus infection, but limited data exist for patients with chronic hepatitis B. Dual X-ray absorptiometry (DEXA) was used to determine bone mineral density changes in TDF-exposed patients. We evaluated the accuracy of the Fracture Risk Assessment Tool (FRAX) as an alternative to DEXA in clinical practice.

METHODS

A total of 170 patients were studied: 122 were exposed to TDF, and 48 were controls. All patients underwent DEXA, and demographic details were recorded. FRAX scores (before and after DEXA) were calculated.

RESULTS

TDF was associated with a lower hip T score (P = .02). On univariate and multivariate analysis, advancing age, smoking, lower body mass index, and TDF exposure were independent predictors of low bone mineral density. In addition, the pre-DEXA FRAX score was an accurate predictor of the post-DEXA FRAX treatment recommendation (100% sensitivity and 83% specificity), area under the curve 0.93 (95% CI, .87-.97, P < .001).

CONCLUSIONS

TDF-treated patients with chronic hepatitis B have reduced bone mineral density, but the reduction is limited to 1 anatomical site. Age and advanced liver disease are additional contributing factors, underlining the importance of multifactorial fracture risk assessment. FRAX can accurately identify those at greatest risk of osteoporotic fracture.

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

Impact of antiretroviral therapy on bone metabolism markers in HIV-seropositive patients

OBJECTIVE

To evaluate the impact of antiretroviral therapy (ART) on bone and mineral metabolism and to determine the occurrence of osteopenia and/or osteoporosis in HIV-infected patients taking ART or not.

METHODS

A cross-sectional study was conducted on 50 HIV-seropositive adult men treated with or not treated with ART. Dual energy X-ray absorptiometry (DXA) was performed and biochemical analyses of the following markers were carried out: FSH, LH, testosterone, total calcium, phosphorus (Pi), magnesium (Mg), albumin, 24h calcium, creatinine, urea, parathormone (PTH), insulin-like growth factor 1 (IGF-I), 25 hydroxyvitamin D (25-OH-D), osteocalcin, and urinary deoxypyridinoline (DPD). The participants were divided into two groups according to ART use or not: Group A, 10 treatment-naive subjects; Group B, ART use for >2years, subdivided into: Group B1, 10 subjects treated with protease inhibitors (PIs) and nucleoside/nucleotide analog reverse transcriptase inhibitors (NRTIs) and Group B2, 10 subjects treated with NRTIs and non-nucleoside analog reverse transcriptase inhibitors (NNRTIs); and Group C, subjects treated with ART <2years, subdivided into: Group C1, 10 subjects treated with PIs and NRTIs and Group C2, 10 subjects treated with NRTIs and NNRTIs.

RESULTS

The values of the bone formation marker, osteocalcin, were normal in all groups, whereas urinary DPD values were increased in all groups. Whole body DXA revealed a higher percentage of osteopenia (80%) in Group B2. Lumbar spine DXA showed osteoporosis in Groups A and B1 (10%) and total femur DXA in Group B2 (10%).

CONCLUSION

The increased bone reabsorption marker indicated a high reabsorptive activity of bone tissue. These data indicate a greater osteoclastic activity in bone loss in HIV-infected patients on ART.

Differential gene expression in HIV-infected individuals following ART

Previous studies of the effect of ART on gene expression in HIV-infected individuals have identified small numbers of modulated genes. Since these studies were underpowered or cross-sectional in design, a paired analysis of peripheral blood mononuclear cells (PBMCs), isolated before and after ART, from a robust number of HIV-infected patients (N=32) was performed. Gene expression was assayed by microarray and 4157 differentially expressed genes (DEGs) were identified following ART using multivariate permutation tests. Pathways and gene ontology (GO) terms over-represented for DEGs reflected the transition from a period of active virus replication before ART to one of viral suppression (e.g., repression of JAK-STAT signaling) and possible prolonged drug exposure (e.g., oxidative phosphorylation pathway) following ART. CMYC was the DEG whose product made the greatest number of interactions at the protein level in protein interaction networks (PINs), which has implications for the increased incidence of Hodgkin's lymphoma (HL) in HIV-infected patients. The differential expression of multiple genes was confirmed by RT-qPCR including well-known drug metabolism genes (e.g., ALOX12 and CYP2S1). Targets not confirmed by RT-qPCR (i.e., GSTM2 and RPL5) were significantly confirmed by droplet digital (ddPCR), which may represent a superior method when confirming DEGs with low fold changes. In conclusion, a paired design revealed that the number of genes modulated following ART was an order of magnitude higher than previously recognized.

Changes in bone turnover and bone loss in HIV-infected patients changing treatment to tenofovir-emtricitabine or abacavir-lamivudine

Background

Those receiving tenofovir/emtricitabine (TDF-FTC) had greater bone loss compared with abacavir/lamivudine (ABC-3TC) in a randomized simplification trial (STEAL study). Previous studies associated increased bone turnover and bone loss with initiation of antiretroviral treatment, however it is unclear whether change in bone mineral density (BMD) was a result of specific drugs, from immune reconstitution or from suppression of HIV replication. This analysis determined predictors of BMD change in the hip and spine by dual-energy x-ray absorptiometry in virologically suppressed participants through week 96.

Methodology/Principal Findings

Bone turnover markers (BTMs) tested were: formation [bone alkaline phosphatase, procollagen type 1 N-terminal propeptide (P1NP)]; resorption (C-terminal cross-linking telopeptide of type 1 collagen [CTx]); and bone cytokine-signalling (osteoprotegerin, RANK ligand). Independent predictors of BMD change were determined using forward, stepwise, linear regression. BTM changes and fracture risk (FRAX®) at week 96 were compared by t-test. Baseline characteristics (n = 301) were: 98% male, mean age 45 years, current protease-inhibitor (PI) 23%, tenofovir/abacavir-naïve 52%. Independent baseline predictors of greater hip and spine bone loss were TDF-FTC randomisation (p≤0.013), lower fat mass (p-trend≤0.009), lower P1NP (p = 0.015), and higher hip T score/spine BMD (p-trend≤0.006). Baseline PI use was associated with greater spine bone loss (p = 0.004). TDF-FTC increased P1NP and CTx through Wk96 (p<0.01). Early changes in BTM did not predict bone loss at week 96. No significant between-group difference was found in fracture risk.

Conclusions/Significance

Tenofovir/emtricitabine treatment, lower bone formation and lower fat mass predicted subsequent bone loss. There was no association between TDF-FTC and fracture risk.