Impaired extinction of cocaine seeking in HIV-infected mice is accompanied by peripheral and central immune dysregulation.

Substance use disorders (SUDs) are highly comorbid with HIV infection, necessitating an understanding of the interactive effects of drug exposure and HIV. The relationship between progressive HIV infection and cocaine use disorder is likely bidirectional, with cocaine use having direct effects on immune function while HIV infection can alter addiction-related behavior. To better characterized the neurobehavioral and immune consequences of HIV infection and cocaine exposure, this study utilized a humanized mouse model to investigate the outcomes of progressive HIV infection on cocaine-related behaviors in a cocaine conditioned place preference (CPP) model, and the interactive effects of cocaine and HIV infection on peripheral and central nervous system inflammation. HIV infection did not impact the formation of a cocaine CPP, but did result in resistance to extinction of the CPP. No effects of HIV on yohimbine-primed reinstatement or cocaine seeking under conflict were observed. These behavioral alterations were accompanied by immune changes in HIV infected mice, including increased prefrontal cortex astrocyte immunoreactivity and brain-region specific effects on microglia number and reactivity. Peripheral immune system changes were observed in both mouse and human markers. Among other targets, this included HIV-induced reductions in mouse IL-1α and G-CSF and human TNFα and cocaine-induced alterations in human TNFα and mouse GM-CSF such that cocaine exposure increases both cytokines only in the absence of HIV infection. Together these data provide new insights into the unique neurobehavioral processes underlying HIV infection and cocaine use disorders, and further how they interact to effect immune responses.