Effect of leukotrienes on HIV-1 infection in the central nervous system: monocyte-derived microglial-like cells
Presented by Jonathan Bertin (Canada).
J. Bertin1,2, C. Barat1, M. Tremblay1
1Centre de Recherche du Centre Hospitalier de l'Université Laval, Centre de Recherche en Infectiologie, Québec, Canada, 2Université Laval, Biologie Médicale, Québec, Canada
Background: HIV-1 enters the central nervous system (CNS) at the early stages of the infection which often leads to HIV associated dementia (HAD). In the CNS, microglia is the main cell type productively infected by HIV. Proinflammatory molecules, including leukotriene B4 (LTB4) and cysteinyl-leukotrienes (cysLTs), secreted in the CNS of infected individuals are a major cause of HAD. Moreover, the presence of leukotriene receptors has been reported in the brain. We therefore sought to investigate whether LTs could modulate HIV-1 infection of monocyte-derived microglial-like cells (MDMi).
Methods: In vitro, monocyte-derived microglia-like cells (MDMi) were pre-treated with a PKC inhibitor (Ro318220) before being exposed to leukotrienes and HIV. In order to discriminate between virus entry via fusion or endocytosis, MDMi were subsequently infected with NL4.3 Luc-R+E-/JR-FL (R5-tropic; pH-independent entry) or NL4.3 Luc-R+E-/VSV-G (endocytosis; pH-dependant entry). To validate the effect of leukotrienes on HIV infection, we quantified by qPCR intergrated and reverse-transcribed (RT) viral DNA in MDMi. Virus entry and replication were quantified by ELISA (p24) or luciferase assay (RLU). Leukotrienes receptors were quantified by flow cytometry on MDMi. Means were compared using ANOVA.
data show that, MDMi exposed to leukotrienes are less susceptible to HIV-1
infection and consequently produce significantly lesser amounts of new virions.
More precisely, a decrease
amount of proviral cDNA was quantified in leukotrienes-exposed MDMi while
reverse-transcribed HIV products remained unaffected. Finally, leukotrienes were unable to alter the
virus entry or replication when cells were pre-incubated with a large spectrum
protein kinase C (PKC) inhibitor (Ro318220).
Conclusion: Leukotrienes negatively modulate the pH-independent entry and the early steps of the intracellular viral cycle in MDMi in a PKC dependant manner. These data will help understand how neuroinflammation in HIV infected individuals can help maintain a lower viral load in the CNS throughout the asymptomatic phase of the disease.
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