INTRACEREBRAL CYTOKINE MESSENGER-RNA EXPRESSION IN ACQUIRED-IMMUNODEFICIENCY-SYNDROME DEMENTIA

The pathogenesis of the dementia associated with human immunodeficienc y virus (HIV) infection is unclear, but has been postulated to be due to indirect effects of HIV infection including the local production of cytokines. To determine which cytokines are produced in the nervous s ystem and to identify any correlations with dementia, cytokine and HIV messenger RNA expression was analyzed by reverse transcriptase-polyme rase chain reaction in the brains from 24 HIV-infected patients with a nd without dementia and 9 HIV-uninfected control subjects. Levels of t umor necrosis factor-alpha messenger RNA were significantly higher and levels of interleukin (IL)-4 messenger RNA were significantly lower i n demented compared to nondemented HIV-infected patients. Demented pat ients also had lower IL-1beta levels than did nondemented patients. No significant differences were detected in the amounts of leukemia inhi bitory factor, IL-6, transforming growth factor-beta1 and -beta2, mono kine induced by gamma interferon-2 (MIG-2), or interferon-gamma messen ger RNAs. IL-10 and IL-2 messenger RNAs were undetectable in all brain s examined. Cytokine messenger RNA levels in nondemented HIV-positive patients were similar to those in HIV-negative control subjects. HIV t ranscripts were more abundant in subcortical white matter than in the basal ganglia, cortex, or deep white matter. Our findings suggest a po ssible role for tumor necrosis factor-alpha in the development of neur ological dysfunction. Increased levels of tumor necrosis factor-alpha messenger RNA were not associated with increased levels of IL-1beta me ssenger RNA, suggesting differential regulation of these monokines in acquired immunodeficiency syndrome dementia. Levels of IL-4 messenger RNA were decreased in dementia and the loss of this and other macropha ge downregulatory factors in demented patients may contribute to the i ncreased expression of tumor necrosis factor-alpha.