Modeling Bone Marrow Progenitor Cell Differentiation and Susceptibility to HIV-1 Infection

Area of Science:

• Immunology
• Virology
• Cell Biology

Background:

• Human Immunodeficiency Virus type 1 (HIV-1) infection impacts the monocytic lineage, contributing to AIDS and HIV-1-associated dementia (HAD).
• Hematopoietic progenitor cells (HPCs) in bone marrow resist HIV-1, while their monocyte-macrophage descendants are susceptible.
• The TF-1 cell line, expressing CD34+/CD38+, has been used to model HPC differentiation.

Purpose of the Study:

• To investigate the differentiation of TF-1 cells using conditioned medium (CM) without phorbol-myristate-acetate (PMA).
• To determine if CM-induced differentiation increases TF-1 cell susceptibility to HIV-1.
• To explore the role of specific transcription factors in HIV-1 replication within differentiated TF-1 cells.

Main Methods:

• TF-1 cells were cultured in CM derived from PMA-treated TF-1 cells.
• Cell surface markers (CD34, CD38, CD69, CD4, CCR5, CXCR4) were analyzed to assess differentiation and activation.
• HIV-1 long terminal repeat (LTR) activity was measured, and the role of specificity protein (Sp) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) was investigated.
• Interleukin (IL)-1β levels in CM were quantified.

Main Results:

• CM induced TF-1 cell differentiation and activation, evidenced by changes in CD34, CD38, and CD69 expression.
• CM treatment upregulated CCR5 and CXCR4 while maintaining CD4 expression, increasing susceptibility to HIV-1.
• HIV-1 LTR activity was enhanced in activated TF-1 cells, with Sp and NF-κB factors playing a key role.
• Elevated IL-1β in CM partially mimicked the observed effects.

Conclusions:

• The TF-1 cell line, when differentiated by CM, serves as a valuable model for studying HIV-1 infection susceptibility in bone marrow progenitor cells.
• Cytokine-rich CM promotes TF-1 cell differentiation and activation, rendering them permissive to HIV-1.
• Sp and NF-κB transcription factors are critical for HIV-1 LTR-mediated transcription in this model system.