Imaging Neuroglial Mechanisms of Neuropathic Pain-Opioid Interaction in HIV

Introduction: Conventional neuroimaging offers limited explanatory findings for the burden of neurological symptoms in people with post-acute sequelae of SARS-CoV-2 (PASC). Recent advanced neuroimaging studies suggest neuronal and glial abnormalities are observed in people with PASC when compared to people without COVID-19. Similar findings observed in people with human immunodeficiency virus (HIV) may offer insight into the neurological burden of PASC.

Objective: The study objective was to assess whether people with PASC and HIV show greater brain glial activation and alterations in neuronal integrity compared to people with PASC and without HIV.

Methods: Brain glial activation was assessed using [11C]PBR28 positron emission tomography (PET), where increased [11C]PBR28 uptake is associated with the upregulation of the 18 kDa translocator protein (TSPO), a putative marker of neuroinflammation or glial density. Alterations in neuronal integrity were evaluated using 1H magnetic resonance spectroscopy (MRS) acquired simultaneously with the PET to measure brain levels of N-acetylaspartate (NAA), a marker of neuronal health and integrity, and myo-inositol (mIns), a marker of gliosis and inflammation. Adults with documented PCR or antibody-confirmed COVID-19 with at least one new neurological symptom following infection lasting for at least 2 months, and without contraindication to MR/PET imaging, were considered eligible to participate in the study.

Results: Twenty-four participants completed the study, consisting of 15 people without HIV (PwoH) and 9 people with HIV (PwH), and 7 age- and sex-matched PwoH without PASC (HC) were included in the analysis. Preliminary findings showed increased [11C]PBR28 signal (standardized uptake value ratio) in PwoH with PASC compared to HC, and [11C]PBR28 hippocampal signal correlated with mental fatigue scores in people with PASC. However, both PET and MRS analyses are still underway, and the preliminary findings are subject to change pending final analysis.

Conclusion/Discussion: While the results may change pending completion of analyses, preliminary findings showed increased [11C]PBR28 hippocampal signal correlated with higher mental fatigue scores in people with PASC. Furthermore, [11C]PBR28 uptake was increased in people with PASC and without HIV compared to people without PASC and HIV.

Key Topics:

• Comparative studies of Long COVID with other post-viral and post-infectious syndromes
• Long COVID and other chronic conditions
• Long COVID in special populations