Striking changes of miRNAs expression in peripheral CD4+ T lymphocytes from HIV-1 infected and HIV-1 exposed uninfected people

Background: MiRNAs inhibit HIV-1 expression by either modulating host innate immunity or by directly interfering with viral mRNAs. Here, we investigated the miRNA profile that discriminates different classes of HIV-1 infected patients from multiple exposed uninfected individuals. Methods: 377 miRNAs were studied in CD4+ cells isolated from whole blood of HIV-1 élite LTNP (éLTNP), naive, and multiply exposed uninfected individuals (MEU). MiRNAs extraction was performed by the mirVana™ miRNA Isolation Kit (Ambion) and their expression was subsequently examined by real-time PCR-based arrays. The miRNAs expression was also determined in primary culture in CD4+ T cells and monocyte-macrophages infected in vitro by R5 strains. Expression of Dicer e Drosha was evaluated by real-time PCR. Flow cytometry was used to detect T cells activation and the main subsets of the patients under investigation. Results: We considered only microRNAs that were expressed in the 70% of patients of at least one class and varied by at least 1log10 from healthy controls. Out of 377 miRNAs, 26 were up-regulated, while 88 were down-regulated. Statistical analysis showed that 21 miRNAs significantly differentiated éLTNP from MEU and 23 miRNAs distinguished naive from MEU, while only 1 (miR-155) discriminated éLTNP from naive. By hierarchical clustering of the miRNAs according to patient class, éLTNP clustered with naive whereas all MEU subjects grouped together. The Dicer and Drosha expression in the patient classes correlated with miRNA profile changes. Among miRNAs differentially expressed in patient classes, 32 were detected in our in vitro infection model: most part of the up-regulated miRNAs were expressed in monocyte-macrophages, whereas most down-regulated miRNAs were expressed in T lymphocytes. Conclusions: The profile of miRNA could be the result not only of a productive infection, but also of the exposure to HIV products that leave a signature in immune cells. These data provide some intriguing issues relative to the development of HIV vaccines targeting viral proteins.