Hemin and Iron Modulated Intrinsic Cellular Factors Regulate HIV-1 Replication in Sickle Cell Disease

Human immunodeficiency virus type 1 (HIV-1) is challenged by intrinsic antiviral restriction factors which are counteracted with its own viral proteins. We recently showed that in Sickle Cell Disease (SCD), anti-viral restriction factor SAMHD1 is activated and inhibits ex vivo HIV-1 infection. Activation of SAMHD1 is caused by a reduced phosphorylation by CDK2, that are inhibited by reduced levels of intracellular iron as found in SCD peripheral blood mononuclear cells (PBMCs). The present study was aimed at identifying additional HIV-1 restriction factors in SCD PBMCs. We used a customized array that included 43 known anti-HIV-1 restriction factors to measure mRNA expression of anti-viral factors. The identified factors were further validated with shRNA-mediated knockdowns of the identified genes and their effect on HIV-1 replication in cultured and primary cells.We also mimicked SCD conditions by treating PBMCs from healthy donors with hemin and iron chelators. We observed an upregulation of 19 genes in SCD PBMCs including APOBEC3A, APOBEC3C, TRIM5α, TRIM22, MX2 and RSAD2 which were significantly upregulated and were further validated using real-time q-PCR. In PBMCs treated with hemin, APOBEC3A, RASD2 and MX2 mRNAs were found to be overexpressed, whereas TRIM5α expression was increased in PBMC treated with either hemin or iron chelators. Knockdowns by shRNA of APOBEC3C and TRIM5α, but not APOBEC3A or TRIM22 induced HIV-1 replication. In conclusion, APOBEC3A, APOBEC3C, TRIM5α, TRIM22, MX2 and RSAD2 may also contribute to HIV-1 restriction in SCD. Similar to SAMHD1, these factors are likely to be modulated by hemolysis and intracellular iron levels. Our findings further point to the contribution of hemolysis and deregulated iron metabolism to potential HIV-1 restriction in SCD.

This work was supported by NIH Research Grants 1P50HL118006, 1R01HL125005, and 5G12MD007597. The content is solely the responsibility of the authors and does not necessarily represent the official view of NHLBI, NIMHD or NIH.