Los Angeles | Rates of low bone mass are greater in HIV-infected males than in females, according to a new study. Researchers from Children’s Hospital Los Angeles studied 11 biomarkers associated with inflammation, bone loss and/or bone formation in about 450 individuals – assessed by sex and HIV status – to try to determine causes of this differential bone loss.
Bone loss in HIV infection is due to immune dysregulation, chronic inflammation and antiretroviral therapy, as well as increased bone turnover from the HIV-infection itself, researchers said. In HIV-infected adults, the combined rates of osteopenia and osteoporosis are as high as 90 per cent in men and 60 per cent in women, with related fractures 60 per cent higher than in the general population, they said. Researchers discovered that HIV-infected adolescent males had increased levels of sCD14 – a marker of macrophage activation.
Macrophages are a type of white blood cell critical to the innate immune system. In the bone, macrophages take the form of osteoclasts the cells responsible for the resorptive processes associated with continuous bone remodelling. Soluble CD14 levels were inversely correlated with measures of bone mineral content and density, suggesting macrophage activation as a possible mechanism for such bone loss.
Despite higher levels of general inflammation in HIV-infected females, HIV-positive males in our study showed both lower bone mass and higher sCD14 levels, said Grace Aldrovandi from Children’s Hospital. This is perhaps because estrogen is protective against some of the inflammation seen in chronic HIV, as estrogen represses macrophage function, Aldrovandi said.
We hope that interventions to decrease macrophage activation early in HIV infection will decrease associated bone loss, which has become a major adverse side effect of HIV infection and its treatment, she added.
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