Tumor necrosis factor-alpha levels in HIV-1 seropositive injecting drug users

TNF-α is a highly pleiotropic cytokine and plays an important role in regulating HIV-1 replication. It may compromise the integrity of the blood-brain-barrier and, thus, may contribute to the neurotoxicity of HIV-1-infection. Both intravenous drug abuse (IDU) and HIV infection can increase TNF-α activity, but little information is available on the effects of a combination of these factors on TNF-α. We investigated plasma TNF-α levels and mRNA in the peripheral monocytes of 166 men and women in three groups: HIV-1-positive IDUs, HIV-1-negative IDUs, and HIV-negative non-IDU control participants. HIV-1-positive IDUs had higher TNF-α levels than HIV-1-negative IDUs who, in turn, had higher levels than controls. TNF-α mRNA expression in peripheral monocytes was significantly increased in both HIV-1-positive and negative IDUs compared to controls. These findings show that the effects of HIV infection and intravenous drug use may be additive in increasing TNF-α levels. Given the multiple effects of TNF-α in HIV infection, additional investigation of its role is needed.