Platelet-activating factor (PAF) is implicated in human immunodeficiency virus (HIV)-related manifestations. Increased PAF synthesis has been recently detected in HIV-infected patients. In this study, we examined in naive HIV-infected patients the in vivo effects of a
highly active antiretroviral therapy (
HAART) regimen, containing
tenofovir-DF/
emtricitabine/
efavirenz, on PAF metabolism. The specific activities of PAF basic biosynthetic
enzymes, PAF-
cholinephosphotransferase (PAF-
CPT) and
lyso-PAF-acetyltransferase (
lyso-PAF-AT), but also the ones of PAF-basic catabolic
enzymes,
PAF acetylhydrolase (PAF-AH) in leukocytes and platelets, and lipoprotein-associated-phospholipase-A(2) (LpPLA(2)) in plasma, were measured in blood samples of eight asymptomatic naive male HIV-infected patients just before and after 1, 3, and 6 months of treatment. CD4 cell counts, viral load, and several
biochemical markers were also measured in the same blood samples of these patients. The repeated measures ANOVA and the Pearson r criterion were used to study statistical differences and correlations-partial correlations, while linear mixed models were conducted in order to estimate association(s) between time-dependent changes in these factors. Before treatment, the activities of PAF-
CPT in leukocytes and LpPLA(2) in plasma were found to be inversely correlated with CD4 cell counts and positively correlated with the viral load. After 6 months of treatment, the activities of basic PAF-biosynthetic
enzymes, PAF-
CPT and
lyso-PAF-AT, were both reduced in leukocytes. At 6 months, PAF-AH activity was also reduced in these cells, while LpPLA(2) remained stable. The reduction of PAF-
CPT occurred even from the first month, while there is a time-dependent correlation between the increase of CD4 and the decrease of both viral load and PAF-
CPT of leukocytes during treatment. Apart from its classical antiretroviral activities the
tenofovir-DF/
emtricitabine/
efavirenz regimen also exhibited favorable effects on PAF metabolism and therefore may also display beneficial effects in some HIV-related conditions, such as
cardiovascular disease (CVD), in which PAF is implicated.