Inflammation status in HIV-positive individuals correlates with changes in bone tissue quality after initiation of ART

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.

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.

An Abnormal Inflammatory Pattern Associated with Long-Term Non-Progression of HIV Infection Impacts Negatively on Bone Quality

Introduction. Long-term non-progressors (LTNPs) are HIV-infected individuals (HIV+) whose viral replication is controlled. However, these individuals experience complications associated with HIV, among them, bone remodeling impairment. This study aims to perform a comprehensive bone health assessment and its association with the inflammatory status of HIV+ LTNPs. A cross-sectional study was conducted comparing bone strength components (bone mineral density and bone tissue quality) between age-, sex-, and comorbidities-matched groups of HIV+ LTNPs, HIV+ progressors, and HIV-negative individuals. A panel of bone turnover and inflammatory biomarkers was measured in fasting plasma using ELISA. Bone tissue quality was assessed by bone microindentation, a technique that directly measures the bone resistance to fracture and yields a dimensionless quantifiable parameter called bone material strength (BMSi). Thirty patients were included: ten LTNPs, ten HIV+ progressors, and ten HIV-negative individuals. LTNPs showed an abnormal pattern of immune activation that was represented by significantly lower levels of anti-inflammatory cytokine IL-10 (p = 0.03), pro-inflammatory cytokine IL-8 (p = 0.01), and TNF-α (p < 0.001) with respect to the other groups. Regarding bone health, LTNPs presented lower BMSi, and thus, worse bone tissue quality than HIV-negative individuals (83 (78−85) vs. 90 (89−93), respectively; p = 0.003), and also lower BMSi than HIV+ progressors (83 (78−85) vs. 86 (85−89), respectively; p = 0.022). A trend was found of lower BMSi in HIV+ progressors with respect to the HIV-negative individuals (86 (85−89) vs. 90 (89−93), respectively; p = 0.083). No differences were detected in bone mineral density between groups. In conclusion, LTNPs showed a different inflammatory profile, along with worse bone tissue quality, when compared to HIV+ progressors and HIV-negative individuals. This may contribute to increasing evidence that HIV infection itself has a deleterious effect on bone tissue, likely through a persistent altered inflammation status.

Factors associated to neurocognitive impairment in older adults living with HIV

OBJECTIVE

The HIV infection is a chronic disease that causes neurocognitive impairment (NI) and has been related with early development of frailty. We aimed to study the main risk factors for neurocognitive disorders and frailty in HIV older adults.

MATERIALS AND METHODS

Cross-sectional study with 40 HIV individuals older than 65 years under antiretroviral therapy in Hospital del Mar (Barcelona) recruited between November 2019 and October 2020. Data has been obtained through clinical scores and a blood sample to evaluate NI and frailty and has been analyzed with non-parametric tests and a multivariate logistic regression model.

RESULTS

Among the 40 patients admitted for the study, 14 (35%) had positive screening for NI. We found that HIV individuals with nadir CD4+ T-cell count lower than 350 cells/mm³ had 39.7 more risk for NI (95% CI 2.49-632.10; p = 0.009). Those with a lower education level had 22.78 more risk for neurocognitive disorders (95% CI 2.13-242.71; p = 0.01) and suffering any comorbidity with a punctuation ≥ 1 in the Charlson Comorbidity index had an increased risk of 18.26 of developing NI and frailty (95% CI 1.30-256.33; p = 0.031), among them diabetes was significantly more frequent in NI.

CONCLUSION

We observed that the main risk factors for a positive NI screening in HIV older adults were low education level, a nadir CD4+ T-cell count < 350 cells/mm³ and the presence of any comorbidity, highlighting diabetes among them.

Persistently lower bone mass and bone turnover among South African children living with well controlled HIV

OBJECTIVE

We evaluated longitudinal trends and associations between bone mass, bone turnover and inflammatory markers among South African children living with HIV (CLHIV) and controls.

DESIGN

We previously reported decreased bone mass among CLHIV independent of marked inflammation and increased bone turnover. The goal of this study was to evaluate longitudinal changes in bone mass, bone turnover and inflammation over 2 years.

METHODS

Longitudinal analyses were conducted among 220 CLHIV and 220 controls. Anthropometric measurements, physical activity, antiretroviral regimen, virologic and immunologic status, whole body (WB) and lumbar spine (LS) bone mineral content (BMC) and bone mineral density (BMD) were collected (enrollment, 12 and 24 months). Bone turnover markers including C-telopeptide of type I collagen (CTx) and procollagen type I N-terminal propeptide (P1NP) and inflammatory markers including interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), soluble CD14 and high-sensitivity C-reactive protein (hsCRP) were collected at enrollment and 24 months.

RESULTS

Compared with controls, CLHIV had significantly lower mean WB-BMC, WB-BMD, WB-BMC z scores, LS-BMC and LS-BMD as well as lower bone formation (P1NP) and resorption (CTx), and higher hsCRP and soluble CD14 over 24 months. CLHIV on efavirenz (EFV) had consistently lower TNF-alpha and IL-6 compared with those on ritonavir-boosted lopinavir (LPV/r) at all time points.

CONCLUSION

Over 2 years of follow-up, South African CLHIV had persistently lower bone mass, bone turnover, and macrophage activation. Lower bone mass and higher pro-inflammatory cytokine profiles were consistently observed among those on LPV/r-based compared with EFV-based regimens.

Bone density, microarchitecture and tissue quality after 1 year of treatment with dolutegravir/abacavir/lamivudine

BACKGROUND

Bone mineral density (BMD) decreases with ART initiation with a tenofovir disoproxil fumarate-containing regimen, although bone tissue quality increases. The impact of dolutegravir (DTG)/abacavir (ABC)/lamivudine (3TC)-based ART initiation on bone health parameters is not clear.

OBJECTIVES

To study the impact of DTG/ABC/3TC-based therapy on bone health parameters in ART-naive individuals with HIV after 48 weeks of treatment.

METHODS

An observational, prospective and analytical study of treatment-naive patients with HIV undergoing a DTG/ABC/3TC-based regimen at 48 week follow-up. Changes in bone strength parameters (BMD, bone microarchitecture and bone tissue quality) were assessed with non-parametric methods.

RESULTS

Sixteen HIV-infected ART-naive patients starting DTG/ABC/3TC were included. BMD in the lumbar spine showed a significant decrease of -2.25% (P = 0.007) and -4.1% in the femoral neck (P = 0.007). Bone microarchitecture, as measured by trabecular bone score, also decreased significantly by -2.5% (P = 0.03). In contrast, bone quality [bone material strength index (BMi)], as measured by microindentation, significantly increased with respect to baseline after 48 weeks of treatment, showing better bone properties of +6.53% (P < 0.001). No significant changes were found in bone turnover markers. In addition, a positive significant correlation between the CD4/CD8 cell count ratio at baseline and changes in BMSi after 48 weeks of treatment was observed (Spearman's rho = 0.4974; P = 0.04).

CONCLUSIONS

After a 48 week treatment with DTG/ABC/3TC-based ART, BMD and trabecular bone score decreased while bone tissue quality, as measured by microindentation, improved significantly. The state of the immune system at ART initiation is related to bone quality recovery. An overarching approach to assess bone toxicity in ART-treated patients is needed.

Added Value of Impact Microindentation in the Evaluation of Bone Fragility: A Systematic Review of the Literature

The current gold standard for the diagnosis of osteoporosis and the prediction of fracture risk is the measurement of bone mineral density (BMD) using dual energy x-ray absorptiometry (DXA). A low BMD is clearly associated with increased fracture risk, but BMD is not the only determinant of bone strength, particularly in secondary osteoporosis and metabolic bone disorders in which components other than BMD are affected and DXA often underestimates true fracture risk. Material properties of bone which significantly contribute to bone strength have become evaluable in vivo with the impact microindentation (IMI) technique using the OsteoProbe® device. The question arises whether this new tool is of added value in the evaluation of bone fragility. To this effect, we conducted a systematic review of all clinical studies using IMI in vivo in humans also addressing practical aspects of the technique and differences in study design, which may impact outcome. Search data generated 38 studies showing that IMI can identify patients with primary osteoporosis and fractures, patients with secondary osteoporosis due to various underlying systemic disorders, and scarce longitudinal data also show that this tool can detect changes in bone material strength index (BMSi), following bone-modifying therapy including use of corticosteroids. However, this main outcome parameter was not always concordant between studies. This systematic review also identified a number of factors that impact on BMSi outcome. These include subject- and disease-related factors such as the relationship between BMSi and age, geographical region and the presence of fractures, and technique- and operator-related factors. Taken together, findings from this systematic review confirm the added value of IMI for the evaluation and follow-up of elements of bone fragility, particularly in secondary osteoporosis. Notwithstanding, the high variability of BMSi outcome between studies calls for age-dependent reference values, and for the harmonization of study protocols. Prospective multicenter trials using standard operating procedures are required to establish the value of IMI in the prediction of future fracture risk, before this technique is introduced in routine clinical practice.