Neuronal ferritin heavy chain and drug abuse affect HIV-associated cognitive dysfunction
Jonathan Pitcher, … , Jay Rappaport, Olimpia Meucci
Jonathan Pitcher, … , Jay Rappaport, Olimpia Meucci
Published January 9, 2014
Citation Information: J Clin Invest. 2014;124(2):656-669. https://doi.org/10.1172/JCI70090.
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Research Article AIDS/HIV

Neuronal ferritin heavy chain and drug abuse affect HIV-associated cognitive dysfunction

Abstract

Interaction of the chemokine CXCL12 with its receptor CXCR4 promotes neuronal function and survival during embryonic development and throughout adulthood. Previous studies indicated that μ-opioid agonists specifically elevate neuronal levels of the protein ferritin heavy chain (FHC), which negatively regulates CXCR4 signaling and affects the neuroprotective function of the CXCL12/CXCR4 axis. Here, we determined that CXCL12/CXCR4 activity increased dendritic spine density, and also examined FHC expression and CXCR4 status in opiate abusers and patients with HIV-associated neurocognitive disorders (HAND), which is typically exacerbated by illicit drug use. Drug abusers and HIV patients with HAND had increased levels of FHC, which correlated with reduced CXCR4 activation, within cortical neurons. We confirmed these findings in a nonhuman primate model of SIV infection with morphine administration. Transfection of a CXCR4-expressing human cell line with an iron-deficient FHC mutant confirmed that increased FHC expression deregulated CXCR4 signaling and that this function of FHC was independent of iron binding. Furthermore, examination of morphine-treated rodents and isolated neurons expressing FHC shRNA revealed that FHC contributed to morphine-induced dendritic spine loss. Together, these data implicate FHC-dependent deregulation of CXCL12/CXCR4 as a contributing factor to cognitive dysfunction in neuroAIDS.

Authors

Jonathan Pitcher, Anna Abt, Jaclyn Myers, Rachel Han, Melissa Snyder, Alessandro Graziano, Lindsay Festa, Michele Kutzler, Fernando Garcia, Wen-Jun Gao, Tracy Fischer-Smith, Jay Rappaport, Olimpia Meucci

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Figure 4

CXCL12 regulates dendritic spine density in vitro and in vivo.

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CXCL12 regulates dendritic spine density in vitro and in vivo. (A) Rat c...
(A) Rat cortical neurons were cultured for 21 days in the presence of a glial feeder layer. CXCL12 treatment (20 nM, 3 hours) increased dendritic spine density (n = 12). (B) Rat cortical neurons were cultured for 21 days as a pure neuronal population. CXCL12 treatment (20 nM) time-dependently increased dendritic spines (n = 7–29). (C) CXCL12 treatment (20 nM) also increased nuclear HDAC4 levels in pure neuronal cultures, as visualized by immunocytochemistry at 30 minutes and quantified over time (n = 12–34). Similar results were obtained by Western blot using nuclear extracts from neurons. (D) After 8 days in culture, transfection of a pure neuronal population with siRNA specifically decreased HDAC4, but not HDAC1, 36 hours after transfection. siRNA-mediated HDAC4 deficiency completely blocked the effects of CXCL12 on dendritic spines (n = 8–17). (E) The CXCR4 antagonist AMD3100 (1 μg i.c.v.) was injected into the left lateral ventricle of 3-week-old rats. 6 hours after injection, animals were sacrificed, and layer II/III pyramidal neurons were analyzed, revealing reduced total dendritic spine density (n = 15). (F) This effect of AMD3100 was similarly confirmed in a prolonged treatment model: implantation of 3-week-old rats with osmotic pumps delivering constant levels of AMD3100 (0.75 μg/h) for 4 days decreased total dendritic spine density (n = 15). *P < 0.05; **P < 0.01; ***P < 0.001. Scale bars: 5 μm (A); 10 μm (C, E, and F). See complete unedited blots in the supplemental material.