Low levels of short- and medium-chain acylcarnitines in HIV-infected patients

Abstract

Background: Carnitine plays an essential role in fatty acid metabolism, exerts substantial antioxidant action and regulates immune functions. We hypothesized that a disturbed carnitine metabolism could be involved in progression of HIV infection.

Materials and methods: Plasma levels of L-carnitine, its precursors, and short-, medium- and long-chain acylcarnitines were analysed with HPLC/mass spectrometry in HIV-infected patients with various disease severities including patients who acquired Mycobacterium avium complex (MAC) infection. In vitro, we examined the MAC-purified protein derivate (PPD)-induced release of TNF-α and IFN-γ in peripheral blood mononuclear cells (PBMCs) from patients with either high or low plasma levels of acylcarnitines.

Results: Plasma levels of the short-chain (e.g. propionyl-carnitine) and medium-chain (e.g. octanoyl-carnitine) acylcarnitines were reduced in patients with advanced HIV infection. These acylcarnitines gradually decreased in rapid progressors, while minimal changes were observed in the nonprogressors. Plasma levels of propionyl-carnitine and octanoyl-carnitine significantly increased during antiretroviral therapy (ART). However, ART did not restore levels to those observed in healthy controls. Depletion of propionyl-carnitine and octanoyl-carnitine was observed prior to MAC infection, and the release of TNF-α and IFN-γ from PBMC was decreased after stimulation with MAC-PPD in samples from HIV-infected patients with low levels of propionyl-carnitine or octanoyl-carnitine.

Conclusions: Our findings suggest an association between disturbed acylcarnitine metabolism, immune dysregulation and disease progression in HIV-infected patients. Low levels of propionyl-carnitine and octanoyl-carnitine were associated with increased susceptibility to MAC infection in HIV patients with advanced disease.

Keywords: Carnitine ester profile; HIV; mycobacterium avium complex.