Although the mechanisms of HIV neuroinvasion, neuronal injury, and subsequent development of HIV-1-associated AIDS dementia complex (ADC) are not fully understood, a correlation between monocyte/macrophage infiltrates in the brain and neurologic disease exists. In light of the many potential roles that chemokines and chemokine receptors may play in HIV neuropathogenesis, we sought to describe their pattern of expression in the SIV-infected rhesus macaque model of HIV encephalitis. We previously demonstrated elevated expression of the chemokines MIP-1a, MIP-1b, RANTES, and IP-10 in brain of macaque monkeys with SIV encephalitis. In this study, we demonstrate that the corresponding chemokine receptors CCR3, CCR5, CXCR3 and also CXCR4 are expressed in perivascular infiltrates in these same tissues. In addition, we detected CCR3, CCR5, and CXCR4 on subpopulations of large hippocampal and neocortical pyramidal neurons and on glial cells in both normal and encephalitic brain. These findings suggest that multiple chemokines and their receptors contribute to monocyte and lymphocyte recruitment to the brain in SIV encephalitis. Furthermore, the expression of known HIV/SIV coreceptors on neurons suggests a possible mechanism whereby HIV or SIV can directly interact with these cells, disrupting their normal physiologic function and contributing to the pathogenesis of ADC.
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