Microstructural alterations of trabecular and cortical bone in long-term HIV-infected elderly men on successful antiretroviral therapy

Bone Tissue Changes in Individuals Living with HIV/AIDS: The Importance of a Hierarchical Approach in Investigating Bone Fragility

Skeletal alterations and their complications can significantly impact the quality of life and overall prognosis of patients living with HIV (PLWHIV). Considering skeletal alterations are often asymptomatic and unapparent during routine clinical evaluation, these conditions are frequently overlooked in the clinical management of PLWHIV. However, since the use of combined antiretroviral therapy (cART) has increased life expectancy in PLWHIV effectively, osteopenia, osteoporosis, and bone fragility are now considered to have a major health impact, with a substantial increase in healthcare costs. This narrative literature review aimed to provide a comprehensive overview of the contemporary literature related to bone changes in PLWHIV, focusing on the importance of taking a multi-scale approach in the assessment of bone hierarchical organization. Even though a low bone mineral density is frequently reported in PLWHIV, numerous ambiguities still remain to be solved. Recent data suggest that assessment of other bone properties (on various levels of the bone structure) could contribute to our understanding of bone fragility determinants in these individuals. Special attention is needed for women living with HIV/AIDS since a postmenopausal status was described as an important factor that contributes to skeletal alterations in this population. Further research on complex etiopathogenetic mechanisms underlying bone alterations in PLWHIV may lead to the development of new therapeutic approaches specifically designed to reduce the health burden associated with skeletal disorders in this population. A major challenge in the clinical management of PLWHIV lies in the adverse skeletal effects of some frequently prescribed cART regimens (e.g., regimens containing tenofovir disoproxil fumarate), which may require a switch to other pharmacological approaches for maintained HIV infection (e.g., regimens containing tenofovir alafenamide). Taken together, the findings are indicative that the HIV/AIDS status should be taken into consideration when designing new guidelines and strategies for individualized prevention, diagnosis, and treatment of increased bone fragility.

Bone Disease in HIV: Need for Early Diagnosis and Prevention

The transformation of HIV into a manageable chronic condition has unveiled new clinical challenges associated with aging-related pathologies, including bone disease. This review explores the intricate relationship between HIV, antiretroviral therapy (ART), and bone disease, highlighting the necessity of early diagnosis and preventative strategies to mitigate the increased risk of osteopenia, osteoporosis, and fractures in people living with HIV (PLWHIV). It synthesizes the current literature to elucidate the multifactorial etiology of bone pathology in this population, that includes direct viral effects, chronic immune activation, ART-associated risks, and the impact of traditional risk factors for bone loss. Through a critical examination of modern diagnostic methods, lifestyle modifications, evidence-based preventive actions, and pharmacological treatments, the necessity for comprehensive management is highlighted, along with recommendations for integrated healthcare approaches vital for achieving optimal patient outcomes. By advocating for a proactive, patient-centered, and multidisciplinary strategy, this review proposes a plan to integrate bone health into standard HIV care through active risk identification, vigilant screening, effective preventive measures, tailored treatments, and informed decision-making, in an effort to ultimately enhance the quality of life for PLWHIV.

Bone Health in People Living with HIV/AIDS: An Update of Where We Are and Potential Future Strategies

The developments in Human Immunodeficiency Virus (HIV) treatment and in the care of people living with HIV (PLWHIV) and Acquired Immunodeficiency Syndrome (AIDS) over the last three decades has led to a significant increase in life expectancy, on par with HIV-negative individuals. Aside from the fact that bone fractures tend to occur 10 years earlier than in HIV-negative individuals, HIV is, per se, an independent risk factor for bone fractures. A few available antiretroviral therapies (ARVs) are also linked with osteoporosis, particularly those involving tenofovir disoproxil fumarate (TDF). HIV and hepatitis C (HCV) coinfection is associated with a greater risk of osteoporosis and fracture than HIV monoinfection. Both the Fracture Risk Assessment Tool (FRAX) and measurement of bone mineral density (BMD) via a DEXA scan are routinely used in the assessment of fracture risk in individuals living with HIV, as bone loss is thought to start between the ages of 40 and 50 years old. The main treatment for established osteoporosis involves bisphosphonates. Supplementation with calcium and vitamin D is part of clinical practice of most HIV centers globally. Further research is needed to assess (i) the cut-off age for assessment of osteoporosis, (ii) the utility of anti-osteoporotic agents in PLWHIV and (iii) how concomitant viral infections and COVID-19 in PLWHIV can increase risk of osteoporosis.

Osteoporosis Remains Constant in Patients with Hemophilia-Long-Term Course in Consideration of Comorbidities

INTRODUCTION

 Patients with hemophilia (PWHs) suffer from an increased risk of osteoporosis. Multiple hemophilia and hemophilic arthropathy associated factors correlate with a low bone mineral density (BMD) in PWHs. The aim of this study was to assess the long-term development of BMD in PWH as well as to analyze potentially influencing factors.

METHODS

 A total of 33 adult PWHs were evaluated in a retrospective study. General medical history, specific-hemophilia-associated comorbidities, joint status using the Gilbert score, calcium level, and vitamin D level as well as at least two results of bone density measurements with a minimum range of 10 years per patient were taken into account.

RESULTS

 The BMD did not change significantly from one point of measurement to the other. A total of 7 (21.2%) cases of osteoporosis and 16 (48.5%) cases of osteopenia were identified. The two following significant correlations could be revealed: the higher the patients' body mass index, the higher their BMD (r = 0.41; p = 0.022). Moreover, a high Gilbert score came along with a low BMD (r = -0.546; p = 0.003).

CONCLUSION

 Even if PWHs frequently suffer from a reduced BMD, our data suggest that their BMD remains constant on a low level in the course of time. A risk factor of osteoporosis often found in PWHs is a vitamin D deficiency and joint destruction. Therefore, a standardized screening of PWHs on BMD reduction by collecting vitamin D blood level and assessing joint status seems appropriate.

Reproducibility and postacquisition correction methods for quantitative magnetic resonance imaging of the anterior cruciate ligament (ACL)

Quantitative magnetic resonance imaging has been used to evaluate the structural integrity of knee joint structures. However, variations in acquisition parameters between scanners pose significant challenges. Understanding the effect of small differences in acquisition parameters for quantitative sequences is vital to the validity of cross-institutional studies, and for the harmonization of large, heterogeneous datasets to train machine learning models. The study objective was to assess the reproducibility of T2 * relaxometry and the constructive interference in steady-state sequence (CISS) across scanners, with minimal hardware-necessitated changes to acquisition parameters. It was hypothesized that there would be no significant differences between scanners in anterior cruciate ligament T2 * relaxation times and CISS signal intensities (SI). Secondarily, it was hypothesized that differences could be corrected by rescaling the SI distribution to harmonize between scanners. Seven volunteers were scanned on 3T Prisma and Tim Trio scanners (Siemens). Three correction methods were evaluated for T2 *: inverse echo time scaling, z-scoring, and Nyúl histogram matching. For CISS, scans were normalized to cortical bone, scaled by the background noise ratio, and log-transformed. Before correction, significant mean differences of 6.0 ± 3.2 ms (71.8%; p = 0.02) and 0.49 ± 0.15 units (40.7%; p = 0.02) for T2 * and CISS across scanners were observed, respectively. After rescaling, T2 * differences decreased to 2.6 ± 2.7 ms (23.9%; p = 0.03), 1.3 ± 2.5 ms (10.9%; p = 0.13), and 1.27 ± 3.0 ms (19.6%; p = 0.40) for inverse echo time, z-scoring, and Nyúl, respectively, while CISS decreased to 0.01 ± 0.11 units (4.0%; p = 0.87). These findings suggest that small acquisition parameter differences may lead to large changes in T2 * and SI values that must be reconciled to compare data across magnets.

People living with HIV have low trabecular bone mineral density, high bone marrow adiposity, and poor trabecular bone microarchitecture at the proximal femur

People living with HIV (PLWH) have increased risk of osteoporosis and fractures. We assessed the proximal femur of PLWH and age-matched seronegative controls using quantitative computed tomography and magnetic resonance imaging. Results suggest that the trabecular compartment is compromised at fracture-prone regions in the proximal femur of PLWH.

INTRODUCTION

People living with HIV (PLWH) have increased risk of osteoporosis and fractures. However, studies assessing the main determinants of bone strength in the proximal femur exclude this vulnerable population. We assessed the proximal femur of 40 PLWH and 26 age-matched seronegative controls using quantitative computed tomography and magnetic resonance imaging.

METHODS

We examined cortical volumetric bone mineral density (Ct.vBMD), trabecular vBMD (Tb.vBMD), cortical thickness (Ct.Th), bone marrow adiposity (BMA), and trabecular number, separation, and bone volume fraction. Parametric comparisons between the two groups were made for the femoral head, femoral neck, trochanter, and total hip using linear regression adjusting for several covariates, including metrics of body composition. In addition, we investigated the associations of BMA with Tb.vBMD and trabecular microarchitecture with Spearman's rank partial correlations.

RESULTS

PLWH had lower Tb.vBMD and deteriorated trabecular microarchitecture in the femoral neck, trochanter and total hip, and elevated BMA in the femoral head, femoral neck, and total hip. Ct.vBMD and Ct.Th were not significantly different between the two groups. BMA was significantly associated with lower Tb.vBMD and deteriorated trabecular microarchitecture in both groups albeit at different femoral regions.

CONCLUSIONS

Our findings suggest that the trabecular, and not the cortical, compartment is compromised in the proximal femur of PLWH. The observed impairments in fracture-prone regions in PLWH indicate lower femoral strength and suggest higher fracture risk. The inverse associations of BMA with trabecular bone density and microarchitecture quality agree with findings at other anatomic sites and in other populations, suggesting that excess BMA possibly due to a switch from the osteoblast to the adipocyte lineage may be implicated in the pathogenesis of bone fragility at the femur in PLWH.

Lower bone density and microarchitecture alterations in HIV-infected Brazilian men aged 50 years and older are associated with estradiol levels

OBJECTIVE

Combination antiretroviral treatment (cART) allows for longer survival for people living with HIV and hence long-term complications of both disease and treatment are common. Our purpose was to evaluate bone alterations in men living with HIV (MLWH) and receiving cART and to identify associated factors that can be corrected or mitigated.

PATIENTS AND DESIGN

Thirty MLWH and 36 healthy controls (≥50 years) were studied for areal bone mineral density (aBMD) and body composition (dual-energy X-ray absorptiometry), volumetric bone mineral density (vBMD) and bone microstructure (high-resolution peripheral quantitative computed tomography [HR-pQCT]), serum calcium, phosphate, parathyroid hormone, 25(OH)D, testosterone (T), estradiol (E₂ ), glucose, creatinine, and albumin levels.

RESULTS

The proportion of patients classified as osteoporosis (according to the lowest aBMD T-score) was higher among MLWH as compared to controls (17.9% vs. 5.9%, p = .011). The MLWH showed significant alterations in cortical and trabecular bone on HR-pQCT, which were not associated with the duration of HIV infection or cART. These differences in vBMD and bone microstructure seen in HR-pQCT persisted in the nonosteoporotic MLWH as compared to nonosteoporotic control subjects. Body mass index (BMI) and fat mass were lower in MLWH and positively associated with total vBMD, cortical bone area, and thickness. E₂ and E₂ /T ratios were lower in MLWH than in controls and significantly correlated with several cortical and trabecular bone parameters. Multivariate regression analysis entering simultaneously age, BMI, and E₂ defined that E₂ is an independent influence on bone parameters evaluated by HR-pQCT.

CONCLUSION

MLWH have alterations in bone volumetric density and microstructure when compared with controls, irrespective of aBMD, which are associated with lower E₂ and BMI.

Bone Quality in Relation to HIV and Antiretroviral Drugs

PURPOSE OF REVIEW

People living with HIV (PLWH) are at an increased risk for osteoporosis, a disease defined by the loss of bone mineral density (BMD) and deterioration of bone quality, both of which independently contribute to an increased risk of skeletal fractures. While there is an emerging body of literature focusing on the factors that contribute to BMD loss in PLWH, the contribution of these factors to bone quality changes are less understood. The current review summarizes and critically reviews the data describing the effects of HIV, HIV disease-related factors, and antiretroviral drugs (ARVs) on bone quality.

RECENT FINDINGS

The increased availability of high-resolution peripheral quantitative computed tomography has confirmed that both HIV infection and ARVs negatively affect bone architecture. There is considerably less data on their effects on bone remodeling or the composition of bone matrix. Whether changes in bone quality independently predict fracture risk, as seen in HIV-uninfected populations, is largely unknown. The available data suggests that bone quality deterioration occurs in PLWH. Future studies are needed to define which factors, viral or ARVs, contribute to loss of bone quality and which bone quality factors are most associated with increased fracture risk.

Osteoporosis and HIV Infection

Life expectancy of people living with HIV (PLWH) is now close to that of the HIV-uninfected population. As a result, age-related comorbidities, including osteoporosis, are increasing in PLWH. This narrative review describes the epidemiology of bone fragility in PLWH, changes of bone features over the course of HIV infection and their determinants, as well as the available evidence regarding the management of osteoporosis in PLWH. The risk of fracture is higher and increases about 10 years earlier compared to the general population. The classical risk factors of bone fragility are very widespread and are major determinants of bone health in this population. The majority of bone loss occurs during virus replication and during immune reconstitution at antiretroviral therapies (ART) initiation, which both increase osteoclast activity. Abnormalities in bone formation and mineralization have also been shown in histomorphometric studies in untreated PLWH. Measurement of bone mineral density (BMD) is the first line tool for assessing fracture risk in postmenopausal women, men above 50 years, and other HIV-infected patients with clinical risk factors for osteoporosis. FRAX underestimates fracture probability in PLWH. In case of indication for anti-osteoporotic drug, bisphosphonates remain the reference option. Calcium and vitamin D supplementation should be considered as ART initiation, since it may attenuate bone loss at this stage. Bone-protective ART regimens improve BMD compared to other regimens, but to a lesser extent than bisphosphonate, and without available data on their influence on the incidence of fracture.

Deterioration of Nutritional Status and Its Negative Association with Depression Among Older HIV-Infected Asian Population: A Four-Year Longitudinal Study

There is limited evidence about the long-term changes in nutritional status among the elderly people living with human immunodeficiency virus (PLWH). We aimed to investigate the changes in nutritional status and related factors over 4 years in the elderly PLWH. The longitudinal study was conducted prospectively among 250 PLWH, 50 years of age and older, receiving antiretroviral therapy (ART). The Mini Nutritional Assessment (MNA) and Thai Depression Scale (TDS) to assess nutritional status and depression, respectively, were performed at the outpatient clinic both at baseline and 4-year follow-up. Majority were male (60.8%) with median age of 58 years. The median CD4 was 612.5 cells/mm³ and 98% had HIV RNA <50 copies/mL. Median duration of ART was 20 years. Median body mass index was 23.1 kg/m². The most common ART were rilpivirine (45.2%) and dolutegravir (18.8%). Fifty-one patients (20.4%) deteriorated in nutritional status and mean MNA scores declined (25.8 vs. 24.8, p < .001) at follow-up period. In multivariate analysis, high TDS scores (odds ratio [OR], 1.33; 95% confidence interval [CI], 1.17-1.52), polypharmacy (OR, 1.35; 95% CI, 1.10-1.65), and high-density lipoprotein cholesterol (HDL-C) levels (OR, 1.04; 95% CI, 1.01-1.07) were associated factors of deterioration in nutritional status. In this 4-year longitudinal follow-up, 20% of the aging PLWH have deterioration of nutritional status. High TDS scores (depression), polypharmacy, and high HDL-C were significantly associated with declining nutritional status. Our findings highlight the importance of screening and monitoring nutritional and depression status in routine HIV treatment and care for geriatric HIV-infected population.

Prevalence of and Risk Factors for Low Bone Mineral Density Assessed by Quantitative Computed Tomography in People Living With HIV and Uninfected Controls

BACKGROUND

Low bone mineral density (BMD) has been described in people living with HIV (PLWH). We examined the prevalence of low BMD measured by quantitative computed tomography (QCT), a method that allows 3-dimensional volumetric density measures at the thoracic spine, in well-treated PLWH and uninfected controls and assessed risk factors for reduced BMD.

METHODS

Cross-sectional study including 718 PLWH from the Copenhagen Co-Morbidity in HIV infection (COCOMO) study and 718 uninfected controls matched on age and sex from the Copenhagen General Population Study (CGPS). Trabecular BMD was determined by QCT.

RESULTS

Median BMD was 144.2 mg/cm in PLWH vs. 146.6 mg/cm in controls (P = 0.580). HIV status was not associated with BMD in univariable or multivariable linear analyses. However, a higher prevalence of very low BMD (T-score ≤ -2.5) was found in PLWH (17.2% vs. 11.0% in controls, P = 0.003). In unadjusted analysis, HIV was associated with very low BMD (odds ratio 1.68 [95% confidence interval: 1.24-2.27], P = 0.001), but this association was not significant after adjusting for age, sex, smoking, alcohol, body mass index, physical activity, and ethnicity. Previous AIDS-defining disease was associated with lower BMD, but no other associations with HIV-specific variables were identified.

CONCLUSION

Using QCT, we found a higher prevalence of very low BMD in PLWH than in controls. However, HIV status was not independently associated with BMD indicating that traditional risk factors contribute to the difference in prevalence of very low BMD. Focus on improvement of lifestyle factors, especially in PLWH with previous AIDS-defining disease, may prevent very low BMD in PLWH.

Factors associated with bone microstructural alterations assessed by HR-pQCT in long-term HIV-infected individuals

PURPOSE

In adults with long-term HIV infection, low bone density and increased fracture risk have emerged as significant comorbidities. Our aim was to assess the association of exercise, nutrition, and medications with bone quality in adults with long-term HIV infection.

METHODS

Forty-three adults with HIV infection were enrolled (median BMI 25.7, range 18.2-35.6 kg/m²; median age 57, range 50-69 years). Participants underwent ultradistal radius and tibia high-resolution peripheral quantitative CT (HR-pQCT). Questionnaires included the revised Community Healthy Activities Model Program for Seniors (CHAMPS), the Mini Nutritional Assessment (MNA) as well as medication assessments. Multivariable linear regression models were used to evaluate the association of exercise, nutritional status, tenofovir disoproxil fumarate (TDF) and protease inhibitor (PI) use with bone density and microstructure, adjusting for demographic risk factors.

RESULTS

In regression models, higher nutrition scores were associated with higher tibia cortical thickness (R² = 0.23; β = 0.03; p = 0.044) and higher radius cortical BMD (R² = 0.43; β = 8.4; p = 0.026). Higher weekly frequency of all physical activities was significantly associated with higher radius trabecular BMD (R² = 0.38; β = 0.96; p = 0.050), higher radius trabecular number (R² = 0.31; β = 0.01; p = 0.026), lower tibia and radius trabecular separation (tibia: R² = 0.30; β = -0.003; p = 0.038; radius: R² = 0.35; β = -0.003; p = 0.021), and higher radius bone stiffness (R² = 0.45; β = 0.38; p = 0.047). Higher frequency of bone loading physical activities was significantly associated with higher tibia trabecular density (R² = 0.44; β = 4.06; p = 0.036), higher tibia bone stiffness (R² = 0.46; β = 3.06; p = 0.050), and higher tibia estimated failure load (R² = 0.46; β = 0.17; p = 0.049). TDF used in combination with a PI was associated with lower radius trabecular BMD (R² = 0.39; β = -41.2; p = 0.042), lower radius trabecular number (R² = 0.34; β = -0.44; p = 0.009) and greater radius trabecular separation (R² = 0.42; β = 0.16; p = 0.002), while TDF use without a PI was not associated with reduced bone quality.

CONCLUSIONS

In adults with HIV infection, malnutrition is associated with poor cortical bone quality, while reduced frequency of physical activities and specifically reduced frequency of mechanical loading activities are associated with deficient trabecular bone structure and reduced estimates of bone strength. TDF use in combination with a PI is associated with deleterious effects on trabecular bone structure.

The IMpact of Vertical HIV infection on child and Adolescent SKeletal development in Harare, Zimbabwe (IMVASK Study): a protocol for a prospective cohort study

INTRODUCTION

The scale-up of antiretroviral therapy (ART) across sub-Saharan Africa (SSA) has reduced mortality so that increasing numbers of children with HIV (CWH) are surviving to adolescence. However, they experience a range of morbidities due to chronic HIV infection and its treatment. Impaired linear growth (stunting) is a common manifestation, affecting up to 50% of children. However, the effect of HIV on bone and muscle development during adolescent growth is not well characterised. Given the close link between pubertal timing and musculoskeletal development, any impairments in adolescence are likely to impact on future adult musculoskeletal health. We hypothesise that bone and muscle mass accrual in CWH is reduced, putting them at risk of reduced bone mineral density (BMD) and muscle function and increasing fracture risk. This study aims to determine the impact of HIV on BMD and muscle function in peripubertal children on ART in Zimbabwe.

METHODS AND ANALYSIS

Children with (n=300) and without HIV (n=300), aged 8-16 years, established on ART, will be recruited into a frequency-matched prospective cohort study and compared. Musculoskeletal assessments including dual-energy X-ray absorptiometry, peripheral quantitative computed tomography, grip strength and standing long jump will be conducted at baseline and after 1 year. Linear regression will be used to estimate mean size-adjusted bone density and Z-scores by HIV status (ie, total-body less-head bone mineral content for lean mass adjusted for height and lumbar spine bone mineral apparent density. The prevalence of low size-adjusted BMD (ie, Z-scores <-2) will also be determined.

ETHICS AND DISSEMINATION

Ethical approval for this study has been granted by the Medical Research Council of Zimbabwe and the London School of Hygiene and Tropical Medicine Ethics Committee. Baseline and longitudinal analyses will be published in peer-reviewed journals and disseminated to research communities.

Diagnosis, prevention, and treatment of bone fragility in people living with HIV: a position statement from the Swiss Association against Osteoporosis

Life expectancy of people living with HIV (PLWH) is reaching similar length as in the general population. Accordingly, age-related comorbidities, including osteoporosis, are increasing. Fracture risk is higher and increases approximately 10 years earlier in PLWH. Classical risk factors of bone fragility are highly prevalent in PLWH but factors specific for HIV infection itself and the type of antiretroviral therapy (ART) (triple combination antiretroviral therapy) regimen (especially tenofovir and protease inhibitors) also contribute to bone loss. The majority of bone loss occurs during virus activity and at initiation of ART (immune reconstitution) and is associated with an increase of bone resorption (upregulation RANKL). Recent data indicate that calcium and vitamin D supplements as ART initiation lower BMD loss. The reduction of tenofovir plasma concentrations with tenofovir alafenamide attenuates BMD loss but it remains unknown whether it will contribute to reduce fracture risk. Hence, special considerations for the management of bone fragility in PLWH are warranted. Based on the current state of epidemiology and pathophysiology of osteoporosis in PLWH, we provide the consensus of the Swiss Association against Osteoporosis on best practice for diagnosis, prevention, and management of osteoporosis in this population. Periodic assessment of fracture risk is indicated in all HIV patients and general preventive measures should be implemented. All postmenopausal women, men above 50 years of age, and patients with other clinical risk for fragility fractures qualify for BMD measurement. An algorithm clarifies when treatment with bisphosphonates and review of ART regimen in favour of more bone-friendly options are indicated.

Assessment of trabecular bone score, an index of bone microarchitecture, in HIV positive and HIV negative persons within the HIV UPBEAT cohort

Introduction

Increased prevalence of low bone mineral density (BMD) and increased fracture incidence are observed in persons living with HIV (PLWH). The trabecular bone score (TBS) is a novel index of bone microarchitecture which improves fracture prediction independent of BMD.

Methods

The HIV UPBEAT study is a single centre, prospective cohort study that enrolled subjects with and without HIV from similar sociodemographic backgrounds for annual assessments of bone health. TBS was derived from lumbar spine (LS) dual-energy X-ray absorptiometry images. Univariate and multivariable linear regression was used to assess relationships between baseline TBS, BMD, sociodemographic and clinical factors.

Results

463 subjects (201 HIV positive) were included; PLWH were younger and more likely male, of non-African ethnicity and current smokers. HIV was associated with a mean reduction of 0.037 [-0.060, -0.013] (p = 0.002) in TBS. Lower TBS was also associated with male gender, non-African ethnicity, current smoking status and lower LS BMD. HIV remained associated with lower TBS after adjustment for LS BMD, age, gender and ethnicity. However, adjustment for current smoking significantly attenuated the association between HIV and TBS, with further adjustment for higher bone turnover markers largely explaining any residual association. Among the sub-group of PLWH, exposure to protease inhibitors and lower nadir CD4+ T-cell counts were both predictors of lower TBS.

Conclusions

PLWH have lower TBS independent of LS BMD. However, this is largely explained by higher current smoking rates and higher bone turnover in those with HIV. Exposure to PI, but not tenofovir disproxil fumarate, also contributed to lower TBS in those with HIV.

Trabecular bone microstructure is impaired in the proximal femur of human immunodeficiency virus-infected men with normal bone mineral density

Background

There is evidence that human immunodeficiency virus (HIV) infection and antiretroviral therapy (ART) are independent risk factors for osteoporosis and fracture which is not solely explained by changes in bone mineral density. Thus, we hypothesized that the assessment of trabecular microstructure might play an important role for bone quality in this population and might explain the increased fracture risk. In this study, we have assessed bone microstructure in the proximal femur using high-resolution magnetic resonance imaging (MRI) as well as in the extremities using high resolution peripheral quantitative computed tomography (HR-pQCT) in HIV-infected men and healthy controls and compared these findings to those based on areal bone mineral density (aBMD) derived from dual X-ray absorptiometry (DXA) which is the standard clinical parameter for the diagnosis of osteoporosis.

Methods

Eight HIV-infected men and 11 healthy age-matched controls were recruited and informed consent was obtained before each scan. High-resolution MRI of the proximal femur was performed using fully balanced steady state free precession (bSSFP) on a 3T system. Three volumes of interest at corresponding anatomic locations across all subjects were defined based on registrations of a common template. Four MR-based trabecular microstructural parameters were analyzed at each region: fuzzy bone volume fraction (f-BVF), trabecular number (Tb.N), thickness (Tb.Th), and spacing (Tb.Sp). In addition, the distal radius and distal tibia were imaged with HR-pQCT. Four HR-pQCT-based microstructural parameters were analyzed: trabecular bone volume fraction (BV/TV), Tb.N, Tb.Th, and Tb.Sp. Total hip and spine aBMD were determined from DXA.

Results

Microstructural bone parameters derived from MRI at the proximal femur and from HR-pQCT at the distal tibia showed significantly lower bone quality in HIV-infected patients compared to healthy controls. In contrast, DXA aBMD data showed no significant differences between HIV-infected patients and healthy controls.

Conclusions

Our results suggest that high-resolution imaging is a powerful tool to assess trabecular bone microstructure and can be used to assess bone health in HIV-infected men who show no differences to healthy males by DXA aBMD. Advances in MRI technology have made microstructural imaging at the proximal femur possible. Further studies in larger patient cohorts are clearly warranted.

Trabecular bone score (TBS) is associated with sub-clinical vertebral fractures in HIV-infected patients

Fragility fractures risk is increased among HIV infected patients. Bone microstructure alterations, in addition to bone mineral density (BMD) reduction, might be responsible for the increased risk. The aim of this study was to determine the prevalence of vertebral fractures (VFs) and their association with trabecular bone score (TBS), an indirect index of bone microstructure, in a cohort of HIV-infected subjects. One-hundred and forty-one HIV-infected patients (87% males, median age 43 years, 94% on stable antiretroviral therapy with undetectable viral load) underwent viro-immunological and bone metabolism biochemical screenings. Lumbar TBS and BMD at femoral neck, total hip, and lumbar spine, were measured with dual-energy X-ray absorptiometry (DXA). VFs were identified using the semiquantitative method and quantitative morphometric analysis from thoracic and lumbar spine X-ray images. VFs were observed in 19 patients (13.5%). BMD was below the expected range for age in 18 (12.8%) subjects. No significant differences were found stratifying VFs prevalence by BMD, whereas patients with lower TBS showed a higher prevalence of VFs (p = 0.03). In multivariate analysis, TBS was the only factor significantly associated to VFs (OR = 0.56; 95% CI = 0.33-0.96; p = 0.034), with increased fracture risk for lower TBS values. VFs are prevalent and associated with low TBS among HIV-positive patients, whereas no significant association was found with BMD.

Bone health in HIV and hepatitis B or C infections

Chronic infections with human immunodeficiency virus (HIV), hepatitis B virus (HBV) or hepatitis C virus (HCV) add to age-dependent bone loss and may contribute to lower bone strength in the elderly. In this review, we report recent highlights on the epidemiology of bone fragility in chronic viral infections with HIV, HCV and HBV, its physiopathology and discuss the interference of antiviral therapies with bone metabolism. Chronic infections influence bone through the interactions between risk factors for bone fragility and falls (which are highly prevalent in infected patients), virus activity and antiviral drugs. HIV-infected patients are at increased risk of fracture and the risk is higher in cases of co-infection with HIV and untreated chronic viral hepatitis. In HIV patients, the majority of bone loss occurs during virus activity and at initiation of antiretroviral therapy (ART). However, long-term elderly HIV-infected patients on successful ART display bone microstructure alterations only partially captured by dual energy X-ray absorptiometry (DXA). Bone loss is associated with an increase of bone resorption, reflecting the upregulation of the receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) pathways via a crosstalk between virus activity, inflammation and the immune system. The use of some antiviral drugs, such as tenofovir (controlling both HBV and HIV infections) or protease inhibitors, may be associated with higher bone toxicity. The reduction of tenofovir plasma concentrations with the implementation of tenofovir alafenamide (TAF) attenuates bone mineral density (BMD) loss but it remains unknown whether it will contribute to reducing fracture risk in long-term HIV-treated patients. Moreover, to what extent the new direct-acting agents for treatment of HCV, including nucleotide inhibitors and protease inhibitors, may affect bone health similarly as ART in HIV should be investigated.

Influence of AIDS in collagen deposition and thickness of the bone marrow

Bone marrow abnormalities are frequently observed in individuals with AIDS. Dysplasia, the most common abnormality, is found in more than 50% of patients infected with the HIV. The aim of this study was to assess trabecular thickness and collagen content as well as cellularity in the bone marrow of patients with AIDS. Sixty bone marrow samples were collected from the sternum of autopsied patients with or without AIDS (n = 30, each). Cellularity and trabecular thickness was assessed by performing hematoxylin-eosin staining; picrosirius staining was used to evaluate collagen content. Morphometric analyses were performed by using a Zeiss KS300 system (Kontron-Zeiss). Patients with AIDS showed a significant reduction in trabecular bone thickness and an increase in collagen deposition. No statistically significant differences were observed in cellularity between the 2 groups. Therefore, reduced thickness and increased collagen deposition were observed in the trabeculae of the bone marrow of patients with AIDS due to possible interaction between cytokines and bone marrow components.