Human immunodeficiency virus infection of human bone derived cells

HIV-1 triggers apoptosis in primary osteoblasts and HOBIT cells through TNFalpha activation

Several HIV-1 infected patients show bone loss and osteopenia/osteoporosis during the course of disease. The mechanisms underlying this degenerative process are largely unsettled and it has not been determined yet whether bone dysfunction is linked to HIV-1-mediated direct and/or indirect effects on osteoblasts/osteoclasts cross-talk regulation. This study investigated the effects of HIV-1(IIIb) and HIV-1(ADA) strains on osteoblasts using the osteoblast-derived cell line (HOBIT) and primary human osteoblasts as cellular models. The challenge of these cell cultures by both HIV-1 strains triggered a significant apoptosis activation unrelated to viral infection, since proviral HIV-1 DNA and supernatant HIV-1 RNA were not detected by real time PCR or b-DNA assays respectively. Under the experimental conditions, even heat-inactivated HIV-1 or cross-linked recombinant gp120 treatment of HOBIT and osteoblasts induced programmed cell death, suggesting that apoptosis is regulated by the interaction between HIV-1 gp120 and cell membrane. The analysis of cell culture supernatants showed a significant up-regulation of TNFalpha, a pleiotropic protein considered an apoptosis inducer in the osteoblast model. In fact, pretreatment of HOBIT and osteoblast cell cultures with anti-TNFalpha polyclonal antibody tackled effectively HIV-1 related induction of cell apoptosis. As a whole, these results indicate that HIV-1 may impair bone mass structure homeostasis by TNFalpha regulated osteoblast apoptosis.

RANKL/OPG/TRAIL plasma levels and bone mass loss evaluation in antiretroviral naive HIV-1-positive men

Osteopenia and osteoporosis are common in HIV-1-infected individuals and represent a challenge in clinical and therapeutic management. This report investigated osteopenia/osteoporosis in a group of 31 antiretroviral naive HIV-1-positive men and the role of specific molecules belonging to TNF and the TNF-receptor family in HIV-1-related bone mass loss. Osteoprotegerin (OPG), the receptor activator of NF-kappab-ligand (RANKL), and the TNF-related apoptosis-inducing ligand (TRAIL) were significantly increased in the plasma of antiretroviral naive HIV-1-positive patients compared to a control group of healthy blood donors. In addition, TRAIL and RANKL plasma concentrations were positively correlated to HIV-1-RNA viral load. Measurement of bone mineral density in 20 out of 31 HIV-1-positive subjects disclosed osteopenia/osteoporosis in 40% of these patients. The antiretroviral naive HIV-1-positive subjects with low bone mineral density had a decreased plasma OPG/RANKL ratio and a plasma RANKL concentration >500 pg/ml. Together, these data indicate that plasma concentrations of specific factors involved in bone homeostasis were increased during HIV-1 infection and that RANKL and OPG/RANKL ratio deregulation may be involved in osteopenia/osteoporosis occurring in antiretroviral naive HIV-1 individuals.

Is HIV sequestered in bone? Possible implications of virological and immunological findings in some HIV-infected patients with bone disease

To determine the prevalence of CD4 lymphocyte levels less than 350 cells/mm3 accompanying viral loads (VL) less than 500 copies/ml (discordant CD4 lymphocyte levels/VL) in HIV-infected men with bone pathologies, we conducted a review of the records of 3512 men. We found discordant CD4 lymphocyte levels/VL in 26 (36.1%) out of 72 with bone pathologies, and in 704 (20.5%) out of 3440 without bone pathologies (P < 0.01), and concluded that HIV sequestered in bone was a possible explanation.

Reduced intravertebral bone marrow fat in HIV-infected men

OBJECTIVE

To measure intravertebral bone marrow fat in HIV-infected men.

DESIGN

A cross-sectional study of HIV-positive men, subcategorized by lipodystrophy and antiretroviral status, and healthy age- and body mass index (BMI)-matched HIV-negative controls.

SETTING

A tertiary care academic medical institution.

PATIENTS

Fifteen HIV-infected men and nine age- and BMI-matched healthy control subjects were recruited for bone density, intravertebral bone marrow fat, and body composition measurements.

METHODS

Magnetic resonance spectroscopy was used to measure intravertebral marrow fat. Quantitative computed tomography was used to quantify visceral and subcutaneous fat. Dual energy X-ray absorptiometry was used to determine lumbar spine bone density. Statistical comparisons were performed according to HIV, lipodystrophy, and protease inhibitor (PI) exposure status.

RESULTS

Intravertebral marrow fat was reduced in HIV-infected men (N = 15) compared with healthy HIV-negative controls (N = 9) (28.5 +/- 8.0 versus 37.3 +/- 12.5%, P = 0.04). Intravertebral bone marrow fat was most severely reduced in HIV-infected men with lipodystrophy compared with healthy HIV-negative controls (25.6 +/- 8.8% versus 37.3 +/- 12.5%, P = 0.04). Furthermore, nelfinavir (P = 0.02) was associated with decreased intravertebral marrow fat and indinavir (P < 0.05) was associated with increased intravertebral marrow fat in HIV-infected subjects.

CONCLUSION

We demonstrated reduced intravertebral marrow fat in HIV-infected men using magnetic resonance spectroscopy. Notably, reduced marrow fat occurred in the setting of reduced bone density and may be affected by specific PI and lipodystrophy status. Further studies are necessary to determine the relationship between marrow fat and osteopenia and the effect of antiretroviral therapy on marrow fat in this population.

Gamma irradiation of HIV-1

The potential for transmission of human immunodeficiency virus (HIV) type 1 has created serious concern for the continued clinical use of bone and soft-tissue allografts. Tissue banks have employed 1.5-2.5 Mrad for sterilization of bone and tendon allografts, which, according to the current literature, approaches the level at which the tissue quality is adversely affected for implantation. Our working hypothesis was that gamma irradiation at increasing doses can proportionately inactivate HIV type 1. The objective of this study was to inactivate HIV type 1 by irradiation, as determined by its capacity to infect human T-lymphocytes and established cell lines in vitro. The replicative competence of HIV type 1 was also assessed by the presence of reverse transcriptase activity, enzyme-linked immunoadsorbent assay (ELISA), immunofluorescence assays for p24 viral core antigen, and the formation of syncytia induced by HIV type 1 in the cultures inoculated with irradiated virus. The results demonstrated the presence of active viral replication in previously noninfected cells in the supernatant samples that were exposed to as much as 5.0 Mrad. The data for the 10-Mrad sample were indeterminate due to cellular damage. These data suggest that gamma irradiation (1.5-2.5 Mrad) does not constitute a virucidal dose for HIV type 1. Current technologies for screening have greatly improved, and the surgeon should rely on tissue bank screening procedures and other methods of preparation rather than sterilization by gamma radiation techniques in choosing allograft material.

Minor column structural acetabular allografts in revision hip arthroplasty

A minor column (shelf) allograft is used for uncontained defects that involve less than 50% of the acetabulum. The prospectively collected records and radiographs of 47 patients (51 hips) who had undergone minor column structural acetabular allograft reconstruction during revision hip arthroplasty were reviewed. The purpose was to identify the long-term results (minimum 5 years) and factors that may influence longevity of the allograft and predispose the patient to subsequent acetabular component failure. The mean duration of followup was 119 months (range, 68-195 months). There was one perioperative death and six patients were lost to followup. Eleven patients (22%) required additional surgery. Three acetabular cups could not be revised successfully, despite multiple attempts, and the patients were treated with Girdlestone excisions. Eight patients underwent successful revision surgery with only three requiring a repeat structural allograft. Survival time for the acetabular cup as determined by Kaplan-Meier analysis was 153 months (95% confidence interval; range, 136-169 months). Cup failure was associated with more operative procedures performed before revision surgery (mean, 3.2 procedures), and failure to restore the vertical center of hip rotation to within 12 to 14 mm of the predicted value. The acetabular abduction angle was not a predictor for failure. The current study shows that good results can be achieved with structural acetabular allograft reconstruction with mid-term to long-term implant survival (cup aseptic survival, 80.4% and allograft re-construction survival, 94.1%), especially if there is restoration of near normal hip biomechanics.

Sterilization of HIV with irradiation: relevance to infected bone allografts

BACKGROUND

Bone allograft banks commonly sterilize frozen bone by irradiation. The dose-response relationship for HIV is calculated and the dose required to inactivate the bioburden of virus that may be present in allograft bone is determined.

METHODS

A virus titre experiment is performed using irradiated frozen HIV. The virus is maintained on dry ice (approximately -70 degrees C) and is exposed to a cobalt 60 source with 0-40 kGy irradiation at 5 kGy intervals. Lymphocyte cell cultures are exposed to serial dilutions of the irradiated virus. The virus titre is quantified by cytological changes of HIV infection and p24 immunofluorescence.

RESULTS

There is a linear relationship between the virus titre and the radiation dose delivered. The inactivation rate of irradiated virus was 0.1134 log10 tissue culture infective doses 50/mL per kGy (95% confidence intervals, 0.1248-0.1020). The irradiation dose required to inactivate the HIV bioburden in allograft bone is 35 kGy. The irradiation dose required to achieve a sterility assurance level of 10(-6) is 89 kGy. This dose exceeds current recommendations for sterilizing medical products and the current practice of many bone banks.

CONCLUSIONS

It is concluded that gamma irradiation should be disregarded as a significant virus inactivation method for bone allografts.