09 February 2013
HIV-positive antiretroviral-naive people had impaired immune responses to malaria in a cell study. Six months of antiretroviral therapy (ART) did not fully restore that response.
Malaria and HIV are prevalent in many of the same regions of Africa. People with HIV have higher malaria parasite burdens than those without HIV, and HIV-positive people have worse clinical outcomes with malaria. The mechanisms for this interaction are not understood. Canadian researchers conducted this study to test their hypothesis that HIV coinfection impairs the innate immune response to malaria, and that ART may restore this response.
The investigators collected peripheral blood mononuclear cells from 25 HIV-positive antiretroviral-naive people and tested them for innate inflammatory responses of natural killer (NK), natural killer T (NKT), and γδ T cells to Plasmodium falciparum, the parasite that causes malaria. Study participants began cART and gave samples for retesting 3 months and 6 months after starting therapy.
NKT, NK, and γδ T-cell subsets from HIV-positive people showed marked differences from cells of people without HIV. Notably, cells from people with HIV produced less interferon γ (IFNγ) and tumor necrosis factor (TNF) in response to malaria parasites. In all three cells types, interleukin-18 receptor expression mediated IFNγ production.
Six months of cART partially reconstituted immune cell populations but had no impact on interleukin-18 receptor expression or production of IFNγ and TNF.
The researchers believe their findings “suggest that HIV infection impairs the inflammatory response of innate effector cells to malaria, and that the response is not fully restored within 6 months of cART.”
The impaired inflammatory response in people with HIV, the authors suggest, “may contribute to higher parasite burdens and ineffective immune responses, and have implications for vaccination initiatives in coinfected individuals.”
Source: Constance A.M. Finney, Kodjo Ayi, James D. Wasmuth, Prameet M. Sheth, Rupert Kaul, Mona R. Loutfy, Kevin C. Kain, Lena Serghides. HIV infection deregulates innate immunity to malaria despite combination antiretroviral therapy. AIDS. 2013; 27: 325-335.
For the study abstract
(Downloading the complete article requires a subscription to AIDS or an online payment; the abstract is free.)