Mild-to-moderate tobacco smoking is highly prevalent in HIV-infected individuals, and is
known to exacerbate HIV pathogenesis. The objective of this study was to determine the
specific effects of mild-to-moderate smoking on viral load, cytokine production, and oxidative
stress and cytochrome P450 (CYP) pathways in HIV-infected individuals who have not
yet received antiretroviral therapy (ART). Thirty-two human subjects were recruited and assigned
to four different cohorts as follows: a) HIV negative non-smokers, b) HIV positive
non-smokers, c) HIV negative mild-to-moderate smokers, and d) HIV positive mild-tomoderate
smokers. Patients were recruited in Cameroon, Africa using strict selection criteria
to exclude patients not yet eligible for ART and not receiving conventional or traditional
medications. Those with active tuberculosis, hepatitis B or with a history of substance
abuse were also excluded. Our results showed an increase in the viral load in the plasma of
HIV positive patients who were mild-to-moderate smokers compared to individuals who did
not smoke. Furthermore, although we did not observe significant changes in the levels of
most pro-inflammatory cytokines, the cytokine IL-8 and MCP-1 showed a significant decrease
in the plasma of HIV-infected patients and smokers compared with HIV negative
non-smokers. Importantly, HIV-infected individuals and smokers showed a significant increase
in oxidative stress compared with HIV negative non-smoker subjects in both plasma
and monocytes. To examine the possible pathways involved in increased oxidative stress
and viral load, we determined the mRNA levels of several antioxidant and cytochrome
P450 enzymes in monocytes. The results showed that the levels of most antioxidants are