Markers of bone turnover are elevated in patients with antiretroviral treatment independent of the substance used

Immune Reconstitution Bone Loss Exacerbates Bone Degeneration Due to Natural Aging in a Mouse Model

BACKGROUND

Immune reconstitution bone loss (IRBL) is a common side-effect of antiretroviral therapy (ART) in people living with HIV (PWH). IRBL acts through CD4 + T-cell/immune reconstitution-induced inflammation and is independent of antiviral regimen. IRBL may contribute to the high rate of bone fracture in PWH, a cause of significant morbidity and mortality. Although IRBL is transient, it remains unclear whether bone recovers, or is permanently denuded and further compounds bone loss associated with natural aging.

METHODS

We utilized a validated IRBL mouse model involving T-cell reconstitution of immunocompromised mice. Mice underwent cross-sectional bone phenotyping of femur and/or vertebrae between 6- and 20-months-of-age by micro-computed tomography (µCT) and quantitative bone histomorphometry. CD4 + T-cells were purified at 20 months to quantify osteoclastogenic/inflammatory cytokine expression.

RESULTS

While cortical IRBL in young animals recovered with time, trabecular bone loss was permanent, and exacerbated skeletal decline associated with natural aging. At 20-months-of-age, reconstituted CD4 + T-cells express enhanced osteoclastogenic cytokines including RANKL, IL-1β, IL-17A and TNFα, consistent with elevated osteoclast numbers.

CONCLUSIONS

IRBL in the trabecular compartment is permanent and further exacerbates bone loss due to natural aging. If validated in humans, interventions to limit IRBL may be important to prevent fractures in aging PWH.

Effect of antiretroviral therapy on bone turnover and bone mineral density in men with primary HIV-1 infection

Introduction

Previous studies indicate that human immunodeficiency virus (HIV)-infection and combination antiretroviral therapy (cART) can affect bone turnover. Furthermore, HIV-infected patients have lower bone mineral density (BMD) compared to a healthy reference population.

Objective

To evaluate the longitudinal effect of HIV-infection and cART on bone turnover markers (BTMs) and BMD in men with primary HIV-infection (PHI).

Design, methods

Thirty-five PHI-men were divided into two groups, those that received cART for the first time (n = 26) versus no-cART (n = 9). Dual-energy X-ray absorptiometry (DXA) was performed on femoral neck (FN), total hip (TH) and lumbar spine (LS) and BTMs (P1NP, alkaline phosphatase, osteocalcin, ICTP and CTX) were measured at baseline and follow-up.

Results

At baseline, the median CD4+ T-cell count was 455 cells/mm3 (IQR 320–620) and plasma viral load 5.4 log10 copies/mL (IQR 4.7–6.0) in the cART treated group, compared to 630 (IQR 590–910) and 4.8 (IQR 4.2–5.1) in the untreated group. The median follow-up time was 60.7 weeks (IQR 24.7–96.0). All BTMs, except ICTP, showed a significant increase during cART versus no changes of BTMs in the untreated group. FN and TH BMD showed a significant decrease in both groups. LS BMD did not change in both groups.

Conclusion

Bone turnover increased in PHI-men treated with cART which was accompanied by a decrease in FN and TH BMD. No increase of bone turnover was seen in untreated PHI-men. Our study suggests that cART results in increased bone turnover and decreased BMD of the hip in PHI-men.

Homeostatic Expansion of CD4+ T Cells Promotes Cortical and Trabecular Bone Loss, Whereas CD8+ T Cells Induce Trabecular Bone Loss Only

Background

Bone loss occurs in human immunodeficiency virus (HIV) infection but paradoxically is intensified by HIV-associated antiretroviral therapy (ART), resulting in an increased fracture incidence that is largely independent of ART regimen. Inflammation in the bone microenvironment associated with T-cell repopulation following ART initiation may explain ART-induced bone loss. Indeed, we have reported that reconstitution of CD3+ T cells in immunodeficient mice mimics ART-induced bone loss observed in humans. In this study, we quantified the relative effects of CD4+ and CD8+ T-cell subsets on bone.

Methods

T-cell subsets in T-cell receptor β knockout mice were reconstituted by adoptive transfer with CD4+ or CD8+ T-cells subsets were reconstituted in T-cell receptor β knockout mice by adoptive transfer, and bone turnover, bone mineral density, and indices of bone structure and turnover were quantified.

Results

Repopulating CD4+ but not CD8+ T cells significantly diminished bone mineral density. However, micro-computed tomography revealed robust deterioration of trabecular bone volume by both subsets, while CD4+ T cells additionally induced cortical bone loss.

Conclusions

CD4+ T-cell reconstitution, a key function of ART, causes significant cortical and trabecular bone loss. CD8+ T cells may further contribute to trabecular bone loss in some patients with advanced AIDS, in whom CD8+ T cells may also be depleted. Our data suggest that bone densitometry used for assessment of the condition of bone in humans may significantly underestimate trabecular bone damage sustained by ART.

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.

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.

Antiretroviral therapy induces a rapid increase in bone resorption that is positively associated with the magnitude of immune reconstitution in HIV infection

OBJECTIVE

Antiretroviral therapy (ART) paradoxically intensifies bone loss in the setting of HIV infection. Although the extent of bone loss varies, it occurs with virtually all ART types, suggesting a common pathway that may be aligned with HIV disease reversal. Using an animal model of immunodeficiency we recently demonstrated that immune activation associated with CD4 T-cell reconstitution induces increased production of the osteoclastogenic cytokines RANKL and TNFα by immune cells, driving enhanced bone resorption and loss in bone mineral density.

DESIGN

To confirm these findings in humans, we investigated the early kinetics of CD4 T-cell recovery in relation to biomarkers of bone turnover and osteoclastogenic regulators in a prospective 24-week cohort study.

METHODS

Clinical data and blood sampling for HIV-RNA PCR, CD4 T-cell counts, bone turnover biomarkers, and osteoclastogenic regulators were obtained from ART-naïve HIV-infected study participants initiating standard doses of lopinavir/ritonavir plus tenofovir disoproxil fumarate/emtricitabine at baseline and at weeks 2, 8, 12, and 24 post ART.

RESULTS

C-terminal telopeptide of collagen (CTx) a sensitive biomarker of bone resorption rose by 200% above baseline at week 12, remaining elevated through week 24 (α<0.01), and was associated with significant increases in plasma levels of osteoclastogenic regulators [receptor activator of NF-kB ligand (RANKL), tumor necrosis factor alpha, (TNFα)]. Importantly, the magnitude of CD4 T-cell recovery correlated significantly with CTx (rs = 0.387, α=0.01).

CONCLUSION

Our data suggest that ART-induced bone loss occurs early, is aligned with early events of immune reconstitution, and these immune changes provide a unifying mechanism to explain in part the skeletal decline common to all ART.

Bone mineral density and inflammatory and bone biomarkers after darunavir-ritonavir combined with either raltegravir or tenofovir-emtricitabine in antiretroviral-naive adults with HIV-1: a substudy of the NEAT001/ANRS143 randomised trial

BACKGROUND

Osteopenia, osteoporosis, and low bone mineral density are frequent in patients with HIV. We assessed the 96 week loss of bone mineral density associated with a nucleoside or nucleotide reverse transcriptase inhibitor (NtRTI)-sparing regimen.

METHODS

Antiretroviral-naive adults with HIV were enrolled in 78 clinical sites in 15 European countries into a randomised (1:1), open-label, non-inferiority trial (NEAT001/ANRS143) assessing the efficacy and safety of darunavir (800 mg once per day) and ritonavir (100 mg once per day) plus either raltegravir (400 mg twice per day; NtRTI-sparing regimen) or tenofovir (245 mg once per day) and emtricitabine (200 mg once per day; standard regimen). For this bone-health substudy, 20 of the original sites in six countries participated, and any patient enrolled at one of these sites who met the following criteria was eligible: plasma viral loads greater than 1000 HIV RNA copies per mL and CD4 cell counts of fewer than 500 cells per μL, except in those with symptomatic HIV infection. Exclusion criteria included treatment for malignant disease, testing positive for hepatitis B virus surface antigen, pregnancy, creatinine clearance less than 60 mL per min, treatment for osteoporosis, systemic steroids, or oestrogen-replacement therapy. The two primary endpoints were the mean percentage changes in lumbar spine and total hip bone mineral density at week 48, assessed by dual energy x-ray absorptiometry (DXA) scans. We did the analysis with an intention-to-treat-exposed approach with antiretroviral modifications ignored. The parent trial is registered with ClinicalTrials.gov, number NCT01066962, and is closed to new participants.

FINDINGS

Between Aug 2, 2010, and April 18, 2011, we recruited 146 patients to the substudy, 70 assigned to the NtRTI-sparing regimen and 76 to the standard regimen. DXA data were available for 129, 121 and 107 patients at baseline, 48 and 96 weeks respectively. At week 48, the mean percentage loss in bone mineral density in the lumbar spine was greater in the standard group than in the NtRTI-sparing group (mean percentage change -2.49% vs -1.00%, mean percentage difference -1.49, 95% CI -2.94 to -0.04; p=0.046). Total hip bone mineral density loss was similarly greater at week 48 in the standard group than in the NtRTI-sparing group (mean percentage change -3.30% vs -0.73%; mean percentage difference -2.57, 95% CI -3.75 to -1.35; p<0.0001). Seven new fractures occurred during the trial (two in the NtRTI-sparing group and five in the standard group).

INTERPRETATION

A raltegravir-based regimen was associated with significantly less loss of bone mineral density than a standard regimen containing tenofovir disoproxil fumarate, and might be a treatment option for patients at high risk of osteopenia or osteoporosis who are not suitable for NtRTIs such as abacavir or tenofovir alafenamide.

FUNDING

The European Union Sixth Framework Programme, Inserm-ANRS, Ministerio de Sanidad y Asuntos Sociales de España, Gilead Sciences, Janssen Pharmaceuticals, and Merck Laboratories.

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.

The ASSURE study: HIV-1 suppression is maintained with bone and renal biomarker improvement 48 weeks after ritonavir discontinuation and randomized switch to abacavir/lamivudine + atazanavir

OBJECTIVES

HIV treatment guidelines endorse switching or simplification of antiretroviral therapy in therapy-experienced patients with suppressed viraemia; ritonavir discontinuation may also enhance tolerability and reduce long-term adverse events (AEs). This open-label, multicentre, noninferiority study enrolled HIV-1-infected, treatment-experienced adults with confirmed HIV-1 RNA ≤ 75 HIV-1 RNA copies/mL currently receiving tenofovir/emtricitabine + atazanavir/ritonavir (TDF/FTC + ATV/r) for ≥ 6 months with no reported history of virological failure.

METHODS

Participants were randomized 1:2 to continue current treatment or switch to abacavir/lamivudine + atazanavir (ABC/3TC + ATV). Endpoints included the proportion of participants with HIV-1 RNA < 50 copies/mL by time to loss of virological response (TLOVR), AEs, fasting lipids, and inflammatory, coagulation, bone and renal biomarkers.

RESULTS

After 48 weeks, 76% (152 of 199) of ABC/3TC + ATV-treated and 79% (77 of 97) of TDF/FTC + ATV/r-treated participants had HIV-1 RNA < 50 copies/mL (TLOVR; P = 0.564). Other efficacy analyses yielded similar results. Rates of new grade 2-4 AEs were 45% in both groups, but an excess of hyperbilirubinaemia made the rate of treatment-emergent grade 3-4 laboratory abnormalities higher with TDF/FTC + ATV/r (36%) compared with ABC/3TC + ATV (19%). Most fasting lipid levels remained stable over time; high-density lipoprotein (HDL) cholesterol increased modestly in ABC/3TC + ATV-treated participants. Bone and renal biomarkers improved significantly between baseline and week 48 in participants taking ABC/3TC + ATV and were stable in participants taking TDF/FTC + ATV/r. No significant changes occurred in any inflammatory or coagulation biomarker within or between treatment groups.

CONCLUSIONS

The ABC/3TC + ATV treatment-switch group had similar viral suppression rates up to 48 weeks to the TDF/FTC + ATV/r comparator group, with lower rates of moderate- to high-grade hyperbilirubinaemia and improvements in bone and renal biomarkers.

Increased bone resorption during tenofovir plus lopinavir/ritonavir therapy in Chinese individuals with HIV

We sought to evaluate the effects of antiretroviral therapy on skeletal metabolism in Chinese individuals with human immunodeficiency virus. Patients switched to tenofovir/lamivudine + lopinavir/ritonavir after treatment failure had an increase in bone resorption marker levels by nearly 60%, which is greater than the magnitude previously described in non-Chinese populations.

INTRODUCTION

Few studies have evaluated the effects of antiretroviral therapy on skeletal metabolism in Asian populations infected with human immunodeficiency virus (HIV).

METHODS

We performed a secondary analysis of bone turnover markers (BTM) at baseline and 2 years in stored plasma samples collected from 2/2009 to 1/2013 as part of a multi-center trial. Two groups were compared: (1) treatment-naïve patients initiated on zidovudine (AZT)/lamivudine (3TC) plus nevirapine (NVP) and (2) patients who failed first-line therapy and were switched to tenofovir (TDF)/3TC plus lopinavir/ritonavir (LPVr). Tests included the bone resorption marker, C-terminal cross-linking telopeptide of type-1 collagen (CTX), and the bone formation marker procollagen type 1 N-terminal propeptide (P1NP).

RESULTS

In the TDF/3TC + LPVr group, samples were available from 59 patients at baseline and 56 patients at 2 years. Of these, 36 patients had samples available from both time points. In the AZT/3TC + NVP group, plasma samples were analyzed from 82 participants at baseline and of those, 61 had samples at 2 years. Median change over 2 years was greater in the TDF/3TC + LPVr group for both CTX (+0.24 ng/mL, interquartile ranges (IQR) 0.10-0.43 vs. +0.09 ng/mL, IQR -0.03 to 0.18, p = 0.001) and P1NP (+25.5 ng/mL, IQR 2.4-51.3 vs. +7.11 ng/mL, IQR -4.3 to 21.6, p = 0.012). Differences remained after adjusting for potential confounders in the multivariable analysis.

CONCLUSIONS

Switching to TDF/3TC + LPVr after treatment failure resulted in greater increases in BTMs than initiation with AZT/3TC + NVP in Chinese patients with HIV. Following this change, bone resorption marker levels increased by nearly 60 %, which is greater than the 25-35% increase from baseline described previously in non-Chinese populations. Further studies are warranted to elucidate these findings.

Simplification to abacavir/lamivudine + atazanavir maintains viral suppression and improves bone and renal biomarkers in ASSURE, a randomized, open label, non-inferiority trial

Objective

Simplification of antiretroviral therapy in patients with suppressed viremia may minimize long-term adverse effects. The study’s primary objective was to determine whether abacavir/lamivudine + atazanavir (ABC/3TC+ATV) was virologically non-inferior to tenofovir/emtricitabine + atazanavir/ritonavir (TDF/FTC+ATV/r) over 24 weeks in a population of virologically suppressed, HIV-1 infected patients.

Design

This open-label, multicenter, non-inferiority study enrolled antiretroviral experienced, HIV-infected adults currently receiving a regimen of TDF/FTC+ATV/r for ≥6 months with no history of virologic failure and whose HIV-1 RNA had been ≤75 copies/mL on 2 consecutive measurements including screening. Patients were randomized 1∶2 to continue current treatment or simplify to ABC/3TC+ATV.

Methods

The primary endpoint was the proportion of patients with HIV-RNA<50 copies/mL at Week 24 by the Time to Loss of Virologic Response (TLOVR) algorithm. Secondary endpoints included alternative measures of efficacy, adverse events (AEs), and fasting lipids. Exploratory endpoints included inflammatory, coagulation, bone, and renal biomarkers.

Results

After 24 weeks, ABC/3TC+ATV (n = 199) was non-inferior to TDF/FTC+ATV/r (n = 97) by both the primary analysis (87% in both groups) and all secondary efficacy analyses. Rates of grade 2–4 AEs were similar between the two groups (40% vs 37%, respectively), but an excess of hyperbilirubinemia made the rate of grade 3–4 laboratory abnormalities higher in the TDF/FTC+ATV/r group (30%) compared with the ABC/3TC+ATV group (13%). Lipid levels were stable except for HDL cholesterol, which increased significantly in the ABC/3TC+ATV group. Bone and renal biomarkers improved significantly between baseline and Week 24 in patients taking ABC/3TC+ATV, and the difference between groups was significant at Week 24. No significant changes occurred in any inflammatory or coagulation biomarker within or between treatment groups.

Conclusions

After 24 weeks, simplification to ABC/3TC+ATV from TDF/FTC+ATV/r maintained viral suppression was well-tolerated, and led to improvements in bone and renal biomarkers and HDL cholesterol.

Trial Registration

ClinicalTrials.gov NCT01102972

GlaxoSmithKline Clinical Study Register #113734

Per oral substitution with 300000 IU vitamin D (Cholecalciferol) reduces bone turnover markers in HIV-infected patients

Background

Osteoporosis and bone fractures seem to be higher in HIV-infected Patients compared to the general populations. Moreover, bone turnover markers are increased in patients on antiretroviral therapy and vitamin D deficiency is prevalent in HIV-infected patients. However, the influence of per oral cholecalciferol on bone metabolism in HIV infected patients is not well understood.

Methods

We measured the bone turnover markers in 96 HIV-infected patients: Bone specific alkaline phosphatase (BSAP), Pyridinoline (PYR), Desoxypyridinoline (DPD) and 25-OH vitamin D. If 25-OH vitamin D was below 75 nnol/L (87/96 patients), 300000 IU cholecalciferol was given per os. 25OH-vitamin D and bone turn over markers were determinded 3 month later. 25 OH-vitamin D was corrected for circannual rythm y'=y+17.875*sin2π365*day+2.06, whereas bone turnover markers were not corrected. The paired students t-Test was used to compare the two periods. No calcium supplementation or biphosphonate therapy was given.

Results

Corrected 25OH-vitamin D levels increased significantly after supplementation (42.7 ± 26.61 vs. 52.85 ± 21.8 nmol/L, p < 0.001). After supplementation, bone turnover markers were significantly lower. The values decreased for BSAP from 21.31 ± 14.32 to 17.53 ± 8.17 μg/L (p < 0.001), PYR from 74.57 ± 36.83 to 54.82 ± 21.43 nmol/mmol creatinine (p < 0.001) and DPD from 15.17 ± 8.34 to 12.61 ± 5.02 nmol/mmol creatinine (p = 0.01).

Conclusions

After per oral substitution with cholecalciferol, bone formation as well as bone resorption markers decreased significant. We postulate a protective effect on bone structure with cholecalciferol supplementation.

Decline in serum 25 hydroxyvitamin D levels in HIV-HBV-coinfected patients after long-term antiretroviral therapy

BACKGROUND

Vitamin D insufficiency plays an important role in the development of fibrosis in chronic liver disease.

METHODS

This was a cross-sectional study from Thailand. Liver fibrosis was assessed by transient elastography. Serum 25 hydroxyvitamin D (25[OH]D)<30 ng/ml was defined as hypovitaminosis D. 25(OH)D was assessed prior to and following tenofovir disoproxil fumarate (TDF). Factors related to 25(OH)D levels were determined by logistic regression analysis.

RESULTS

A total of 158 HIV-HBV-coinfected patients (32% female, median age 43 years) were included. Overall, liver disease was mild with 13.4% having a fibrosis score (FS) of 7.1-14 kPa and 2% with a FS>14 kPa. Median (IQR) duration on TDF was 5 years (4-7). The median estimated glomerular filtration rate was 96.9 ml/min/1.73 m(2). The median (IQR) serum 25(OH)D levels prior to and following TDF were 24.8 ng/ml (21.3-30.6) and 22.8 ng/ml (18.0-27.7), respectively; P≤0.001). The proportion of patients with hypovitaminosis D significantly increased from 72.2% (95% CI 64.7, 78.6) prior to TDF to 84.2% (95% CI 77.7, 89.0) after taking TDF (P=0.01). Factors associated with hypovitaminosis D by multivariate analysis were female sex (adjusted OR 3.8, 95% CI 1.1, 13.7; P=0.038) and duration of antiretroviral therapy (ART)>5 years (OR 3.3, 95% CI 1.2, 8.8; P=0.017). Vitamin D levels were not associated with significant liver fibrosis.

CONCLUSIONS

Although our HIV-HBV-coinfected patients live in the tropics, there was a high prevalence of hypovitaminosis D, especially in female patients and those receiving prolonged ART. Since HIV-HBV-coinfection requires long-term use of the HBV-active drug, TDF, which can also contribute to bone loss, routine vitamin D assessment and supplementation as necessary should be considered.

Bone turnover and bone mineral density in HIV-1 infected Chinese taking highly active antiretroviral therapy -a prospective observational study

Background

Low bone mass and high bone turnover have been reported in HIV-infected individuals, both as a consequence of HIV infection itself, as well as from treatment with highly active antiretroviral therapy (HAART). The purpose of this study is to evaluate the impact of HAART on bone mineral density and bone turnover in HIV-1 infected Chinese patients.

Methods

Forty HIV-1 infected patients were enrolled in this study; all patients were followed through 48 weeks, and 17 patients completed 96 weeks. Bone mineral density (BMD), procollagen type 1 N-terminal propeptide (P1NP), collagen type 1 cross-linked C-telopeptide (β-CTX), parathyroid hormone (PTH), and 25-OH vitamin D levels were measured at baseline, 48 and 96 weeks. Baseline measurements were compared with an age-, gender-, and BMI-matched healthy control population.

Results

At baseline, raw BMD in the lumbar spine of HIV-1 infected patients was significantly lower than that of healthy controls (1.138 ± 0.112 g/cm² vs. 1.195 ± 0.139 g/cm², p = 0.047). During the first 48 weeks after initiating HAART, BMD of lumbar spine, femoral neck, and total hip decreased significantly in HIV-1 infected patients, with annual percent decline ranging from 1.78-3.28%. However, from week 48 to 96, BMD remained stable. Baseline levels of β-CTX (0.31 ± 0.16 ng/mL vs. 0.42 ± 0.19 ng/mL, p = 0.008) and P1NP (32.96 ± 14.00 ng/mL vs. 55.82 ± 26.87 ng/mL, p = 0.05) were lower in HIV-infected patients compared with controls, respectively. Both β-CTX and P1NP levels increased after onset of HAART until week 48, and remained elevated during the next 48 weeks. 25-OH vitamin D in HIV-infected patients was lower at baseline compared to healthy controls, but this difference was not statistically significant. PTH, however, was higher in HIV patients at baseline, and showed a significant increase throughout the study.

Conclusions

Chinese adults with HIV-1 infection have low bone turnover prior to HAART as well as lower raw BMD of the lumbar spine compared with healthy controls, with further bone loss occurring following the initiation of HAART. The long-term clinical implications of these findings remain unclear at this time.

Lopinavir/ritonavir combined with raltegravir or tenofovir/emtricitabine in antiretroviral-naive subjects: 96-week results of the PROGRESS study

Alternative combinations of antiretrovirals (ARVs) are desired to increase treatment options for HIV-infected patients. PROGRESS was a randomized, open-label, 96-week pilot study comparing a regimen of lopinavir/ritonavir (LPV/r) 400/100 mg twice daily in combination with either raltegravir (RAL) 400 mg twice daily or tenofovir/emtricitabine (TDF/FTC) 300/200 mg once daily in ARV-naive adults. A total of 206 subjects were randomized and treated (LPV/r+RAL, N=101; LPV/r+TDF/FTC, N=105). Demographics and baseline characteristics were similar across treatment groups. At 96 weeks, 66.3% of subjects receiving LPV/r+RAL and 68.6% of subjects receiving LPV/r+TDF/FTC were responders (plasma HIV-1 RNA levels<40 copies/ml) by the FDA time to loss of virologic response (FDA-TLOVR) algorithm (p=0.767). Mean CD4(+) T cell increases through 96 weeks were similar between treatment groups (LPV/r+RAL=281 cells/mm(3), LPV/r+TDF/FTC=296 cells/mm(3), p=0.598). Safety and tolerability were generally similar between groups. The LPV/r+RAL regimen resulted in greater increases in peripheral fat, but not trunk fat, compared with LPV/r+TDF/FTC. There was a statistically significantly greater mean reduction in estimated glomerular filtration rate from baseline to week 96 in the LPV/r+TDF/FTC group compared with the LPV/r+RAL group (-7.33 ml/min vs. -1.43 ml/min; p=0.035). The LPV/r+TDF/FTC group had a statistically significant (p<0.001) mean percent decrease from baseline to week 96 in bone mineral density, which was significantly different from the mean percent change in the LPV/r+RAL group (-2.48% vs. +0.68%, p<0.001). These efficacy and safety observations support further evaluation of the LPV/r+RAL regimen.

Severe hypovitaminosis D correlates with increased inflammatory markers in HIV infected patients

BACKGROUND

Even though it has been suggested that antiretroviral therapy has an impact on severe hypovitaminosis D (SHD) in HIV infected patients, it could be speculated that the different levels of residual inflammation on HAART (Highly Active Anti Retroviral Therapy) could contribute to SHD and aggravate bone catabolism in these patients.

METHODS

A cross-sectional study was carried out in an unselected cohort of 263 HIV infected outpatients consulting during Spring 2010. Clinical examinations were performed and medical history, food habits, sun exposure and addictions were collected. Fasting blood samples were taken for immunological, virological, inflammation, endocrine and bone markers evaluations.

RESULTS

Ninety-five (36%) patients had SHD. In univariate analysis, a significant and positive association was found between SHD and IL6 (p = 0.001), hsCRP (p = 0.04), increased serum C-Telopeptides X (CTX) (p = 0.005) and Parathyroid Hormon (PTH) (p < 0.0001) levels. In multivariate analysis, SHD deficiency correlated significantly with increased IL-6, high serum CTX levels, lower mean daily exposure to the sun, current or past smoking, hepatitis C, and functional status (falls), but not with the time spent on the current HAART (by specific drug or overall).

CONCLUSIONS

SHD is frequent and correlates with inflammation in HIV infected patients. Since SHD is also associated with falls and increased bone catabolism, it may be of interest to take into account not only the type of antiretroviral therapy but also the residual inflammation on HAART in order to assess functional and bone risks. This finding also suggests that vitamin D supplementation may be beneficial in these HIV-infected patients.

HIV infection and osteoporosis: pathophysiology, diagnosis, and treatment options

As the population with HIV continues to age, specialists in HIV care are increasingly encountering chronic health conditions, which now include osteoporosis, osteopenia, and fragility fractures. The pathophysiology of the bone effects of HIV infection is complex and includes traditional risk factors for bone loss as well as specific effects due to the virus itself, chronic inflammation, and HAART. Examining risk factors for low bone density and screening of certain patients is suggested, and consideration should be given to treatment for those considered high risk for fracture.

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.

Prospective evaluation of bone markers, parathormone and 1,25-(OH)₂ vitamin D in HIV-positive patients after the initiation of tenofovir/emtricitabine with atazanavir/ritonavir or efavirenz

BACKGROUND

Increased risk of fractures and osteoporosis have been associated with the use of antiretroviral drugs. There is a paucity of prospective evaluations of bone markers after the initiation of drugs currently recommended to treat HIV infection and results on the evolution of these markers are conflicting. Lastly, the effect of tenofovir on 1,25-(OH)₂ vitamin D is uncertain.

METHODS

We performed a prospective study on the evolution of bone markers, parathormone and 1,25-(OH)₂ vitamin D before and after standard antiretroviral regimens. This was a sub-study of a trial conducted in antiretroviral-naïve patients randomized to tenofovir + emtricitabine in combination with either atazanavir/ritonavir (ATV/r) or efavirenz (EFV). Follow-up lasted 48 weeks. The following bone markers were analyzed: C-terminal cross-laps (CTx), osteocalcin (OC), osteoprotegerin (OPG), and receptor activator of nuclear factor κB ligand (RANKL). Mixed-factorial analysis of variance with random-coefficient general linear model was used to compare their trends over time and linear multivariable regression was performed with a backward selection method to assess predictors of their variations from baseline to week 48. Trends of parathormone and 1,25-(OH)₂ vitamin D were also evaluated.

RESULTS

Seventy-five patients were studied: 33 received EFV and 42 ATV/r. Significant increases were found for all markers except for RANKL. There was a significant direct association between CTx and OC increases. Multivariable analysis showed that higher glomerular filtration rate (estimated through cystatin C clearance) predicted greater OPG increase, while older age, higher HIV RNA at baseline and use of ATV/r predicted greater CTx increase. A significant increase of parathormone accompanied the evolution of the study markers. 1,25-(OH)₂ vitamin D remained stable, though a seasonality variation was demonstrated.

CONCLUSIONS

These data demonstrate CTx increase (bone resorption marker) corresponding to OC increase (bone formation marker) early upon HAART initiation. Moreover, predictors of bone marker increases have been suggested, possibly indicating that a stricter monitoring of bone health and pro-active interventions are needed in older patients, those with higher HIV RNA, prescribed ATV/r rather than EFV, and with decreased renal function at baseline. Further studies are needed to clarify the mechanisms responsible for up-regulation of bone turnover markers, as well as to understand if and what markers are best correlated or predictive of pathological fractures.

Effects of vitamin D deficiency and combination antiretroviral therapy on bone in HIV-positive patients

OBJECTIVES

In the era of combination antiretroviral therapy (cART), vitamin D deficiency, low bone mineral density (BMD) and fractures have emerged as subjects of concern in HIV-positive patients. Testing for vitamin D deficiency has been widely adopted in clinical practice even though the benefits of vitamin D supplementation in this population remain uncertain. The objective of this review was to evaluate the evidence for such a strategy.

DESIGN

Systematic review of the literature on vitamin D deficiency in HIV infection, the effects of cART on vitamin D status, and the effects of vitamin D deficiency and cART on parathyroid hormone (PTH), bone turnover, BMD and the incidence of fractures in HIV-positive patients.

METHODS

PubMed was used to identify relevant articles up to September 2011.

RESULTS

Vitamin D deficiency, secondary hyperparathyroidism and low BMD are common in HIV-positive patients. Efavirenz is associated with a reduction in 25-hydroxy vitamin D levels, tenofovir with secondary hyperparathyroidism, and cART with increased bone turnover and low BMD. The clinical significance of low BMD, however, remains unclear, especially in younger patients. Although the incidence of fractures may be increased in HIV-positive patients, the contribution of low BMD and vitamin D deficiency to these fractures is uncertain. Limited data on vitamin D supplementation in HIV-positive patients have shown transient, beneficial effects on PTH, but no effects on BMD.

CONCLUSION

The benefits of vitamin D supplementation in this population need to be demonstrated before widespread 'test and treat' policies can be recommended as part of routine clinical practice.