Background: HIV infection is linked to higher cardiovascular risk. Adverse outcomes may be mediated through mechanisms of endothelial dysfunction attributed to nitric oxide (NO) inhibition. The aim of the study was to compare blood plasma levels of asymmetric dimethylarginine (ADMA), a natural NO inhibitor, of HIV infected patients who are either naïve to treatment or on antiretroviral therapy (ART) and healthy controls.

Methods: 108 subjects were studied: 29 non-infected controls and 79 HIV infected patients [33 naïve to treatment, 30 on a nucleoside reverse transcriptase inhibitor plus non-nucleoside reverse transcriptase inhibitor combination (NRTI/NNRTI) and 16 on a nucleoside reverse transcriptase inhibitor plus a protease inhibitor combination (NRTI/PI)]. Plasma ADMA levels were measured using a commercially available ELISA kit. Between group comparisons were made using non-parametric tests.

Results: HIV infected patients had higher ADMA levels compared to controls (P=0.003). ADMA levels differed significantly across groups; non-infected controls had the lower levels of ADMA (P=0.001). Among HIV infected patients, those on ART exhibited higher ADMA levels versus ART-naïve patients [0.84 (0.77, 1.05) μmol/L for ART versus 0.67 (0.26, 0.86) μmol/L for ART-naïve patients, P=0.002]. ADMA levels did not differ between patients on NNRTIs [0.86 (0.77, 1.10)] or PIs [0.82 (0.71, 0.95)], P=0.31.

Conclusions: ART-naïve patients exhibit lower ADMA levels, denoting increased NO bioavailability compared to patients on ART; this may be attributed to their lower viral load that translates in a diminished inflammatory burden and better functional status. Patients on NNRTIs and PIs have comparable ADMA plasma levels.