IDENTIFICATION OF A SPECIFIC MIRNA PROFILE INHIV EXPOSED SERONEGATIVE INDIVIDUALS

Abstract Objective: MicroRNAs (miRNAs) are small 20- to 24-nt non-coding RNAs involved in the post-transcriptional regulation of gene expression which play important defensive roles in several viral infections. Global expression profiles of cellular miRNAs have identified alterations in the expression of specific miRNA post-HIV-1 infection both in vitro and in different patient cohorts, suggesting a potential role for miRNAs in the pathogenesis and progression of HIV-1 infection. We therefore decided to verify if natural resistance to HIV-1 infection, observed in seronegative individuals repeatedly exposed to HIV-1 (HESN) through unprotected sexual intercourse, could be secondary to a different expression of their miRNA profile. Methods: Expression level of 84 miRNAs was analyzed by RT-PCR array in plasma and unstimulated PBMC of 30 seronegative individuals repeatedly exposed to HIV (HESN), 30 HIV seropositive subjects (HIV+) and 30 healthy controls (HC). Results were confirmed by individual RT-qPCR in plasma, in vitro HIV infected PBMC and supernatants, isolated monocyte and in in vitro HIV infected monocyte derived macrophages (MDM). ABCA1, Dicer and Drosha mRNA expression was analyzed as well. Results: Whereas Dicer and Drosha expression was comparable in HESN, HIV+ and HC, several miRNA were upregulated both in HESN and HIV+ compared to HC, suggesting that exposure to HIV modifies miRNA signature even in the absence of productive infection. MiRNA-29a and miR-223 were upregulated in both unstimulated PBMC and plasma of HESN alone; their expression was reduced upon in vitro HIV infection of HESN PBMC indicating that, upon infection, they are secreted in the extracellular milieu. These results were confirmed by individual qPCR. Additionally, HESN miRNA profile in monocytes clustered with HC one, while, reduced susceptibility to HIV-1 infection in in vitro HIV infected MDM from HESN was associated with higher expression of all our tested miRNAs compared to HCs. Finally, the upregulation of miR-223 in basal PBMC, monocytes and HIV-1 infected MDM resulted into an increased expression of ABCA1. Conclusions: Our studies demonstrate that HIV exposure modifies miRNAs expression. Because those miRNAs that are specifically increased only in HESN have been known to reduce HIV replication via the binding of viral mRNA 3’ UTRs, the modulation of these miRNAs could represent an important mechanism in resistance to HIV.