Abstract
HIV-positive individuals are susceptible to expansion of the non-classical and intermediate pool of peripheral blood mononuclear cells (PBMCs). Persistent HIV-related inflammation contributes to neurodegeneration but effects on limbic brain centers are not well understood. Here, we compare PBMCs and their expression of pro-inflammatory cytokines to resting brain activity and mood within and between 19 HIV + and 19 HIV- (mean age = 54.5, SD = 5.68) post-menopausal women. Mean amplitude of low-frequency fluctuations (mALFF), Profile of Mood States Questionnaire (POMS) and PBMCs immunophenotyped by flow cytometry were collected on consecutive days. PBMCs were classified into classical (CD14++ CD16−), intermediate (CD14++ CD16+) and non-classical (CD14low/+ CD++) monocyte subsets. PBMCs underwent intracellular staining for IL-6, TNF-a, IL1-b and IL-10 cytokines. One sample t-tests indicated that, compared to classical PBMCs, there was greater nonclassical IL-6 and intermediate IL-6, IL1-b and IL-10 expression. Total mood disturbance correlated with intermediate (r = .474, p = .003) and non-classical (r = .425, p = .010) PBMCs (Bonferroni corrected). Percentage of intermediate PBMCs also predicted greater activity within the subgenual anterior cingulate cortex (sgACC), (T = 3.35, k = 50 p=.002, cluster thresholded), a region associated with sickness behavior and depression. However, using a 5-mm sphere surrounding the sgACC parameter estimates failed to correlate with mood disturbance (r = .196, p>.05). Our findings suggest that expansion of the intermediate monocyte pool may reflect increased activation within neurovisceral limbic regions.
