Despite combined antiretroviral therapy, neuroinflammation may persist in persons living with HIV (PLWH) and contribute to cognitive impairment in this population. Positron emission tomography (PET) imaging targeting 18 kDa translocator protein (TSPO) has been used to localize neuroinflammation. We aimed to use TSPO-PET imaging to evaluate neuroinflammation in PLWH.
Twenty-four virologically suppressed PLWH on combined antiretroviral therapy and 13 HIV-negative (HIV−) controls completed TSPO-PET imaging using the radiotracer [11C]PBR28. Because of tracer complexity and differing procedures used in previous studies, we employed an expansive methodological approach, using binding potential (BP) and standard uptake value ratio and multiple different reference regions to estimate [11C]PBR28 binding.
[11C]PBR28 binding was measured in 30 cortical and subcortical regions and compared between PLWH and HIV− controls. Pearson correlation evaluated the association between [11C]PBR28 binding and cognition and clinical measures of HIV.
Analyses conducted using multiple reference regions and measures of tracer uptake revealed no significant differences between [11C]PBR28 binding in PLWH compared with HIV− controls. In addition, [11C]PBR28 binding in PLWH was not significantly associated with clinical measures of HIV or plasma biomarkers of inflammation. [11C]PBR28 binding was not significantly elevated in cognitively impaired PLWH compared with unimpaired PLWH, but there were inverse relationships between cognitive performance (executive and global function) and [11C]PBR28 binding in PLWH.
Our results suggest that neuroinflammation may play a role in cognitive deficits, but overall neuroinflammatory levels as measured by TSPO-PET imaging in PLWH are not significantly different from those seen in HIV− controls.