Curcuma Longa Induces the Transcription Factor FOXP3 to Downregulate Human Chemokine CCR5 Expression and Inhibit HIV-1 Infection.

HIV mutations occur frequently despite the substantial success of combination antiretroviral therapy, which significantly impairs HIV progression. Failure to develop specific vaccines, the occurrence of drug-resistant strains, and the high incidence of adverse effects due to combination antiviral therapy regimens call for novel and safer antivirals. Natural products are an important source of new anti-infective agents. For instance, curcumin inhibits HIV and inflammation in cell culture assays. Curcumin, the principal constituent of the dried rhizomes of Curcuma longa L. (turmeric), is known as a strong anti-oxidant and anti-inflammatory agent with different pharmacological effects. This work aims to assess curcumin's inhibitory effects on HIV in vitro and to explore the underpinning mechanism, focusing on CCR5 and the transcription factor forkhead box protein P3 (FOXP3). First, curcumin and the RT inhibitor zidovudine (AZT) were evaluated for their inhibitory properties. HIV-1 pseudovirus infectivity was determined by green fluorescence and luciferase activity measurements in HEK293T cells. AZT was used as a positive control that inhibited HIV-1 pseudoviruses dose-dependently, with IC50 values in the nanomolar range. Then, a molecular docking analysis was carried out to assess the binding affinities of curcumin for CCR5 and HIV-1 RNase H/RT. The anti-HIV activity assay showed that curcumin inhibited HIV-1 infection, and the molecular docking analysis revealed equilibrium dissociation constants of [Formula: see text]9.8[Formula: see text]kcal/mol and [Formula: see text]9.3[Formula: see text]kcal/mol between curcumin and CCR5 and HIV-1 RNase H/RT, respectively. To examine curcumin's anti-HIV effect and its mechanism in vitro, cell cytotoxicity, transcriptome sequencing, and CCR5 and FOXP3 amounts were assessed at different concentrations of curcumin. In addition, human CCR5 promoter deletion constructs and the FOXP3 expression plasmid pRP-FOXP3 (with an EGFP tag) were generated. Whether FOXP3 DNA binding to the CCR5 promoter was blunted by curcumin was examined using transfection assays employing truncated CCR5 gene promoter constructs, a luciferase reporter assay, and a chromatin immunoprecipitation (ChIP) assay. Furthermore, micromolar concentrations of curcumin inactivated the nuclear transcription factor FOXP3, which resulted in decreased expression of CCR5 in Jurkat cells. Moreover, curcumin inhibited PI3K-AKT activation and its downstream target FOXP3. These findings provide mechanistic evidence encouraging further assessment of curcumin as a dietary agent used to reduce the virulence of CCR5-tropic HIV-1. Curcumin-mediated FOXP3 degradation was also reflected in its functions, namely, CCR5 promoter transactivation and HIV-1 virion production. Furthermore, curcumin inhibition of CCR5 and HIV-1 might constitute a potential therapeutic strategy for reducing HIV progression.

A novel dual-luciferase assay for anti-HIV drug screening based on the CCR5/CXCR4 promoters.

Acquired immunodeficiency syndrome (AIDS) is a serious worldwide disease caused by infection with the human immunodeficiency virus (HIV). C-C chemokine receptor 5 (CCR5) and C-X-C chemokine receptor 4 (CXCR4) are important coreceptors mediating HIV-1 cell entry. Many new anti-HIV drugs are currently in preclinical and clinical trials; however, drug development has proceeded slowly partly because of the lack of a high-throughput system to screen these drugs. Here, we describe the development of a novel dual-luciferase assay using a CCR5/CXCR4 promoter-driven firefly and Renilla luciferase vector (pGL4.10-RLUC-CCR5/CXCR4). Drugs were screened for the ability to regulate CCR5 and CXCR4 promoter activities. The CCR5 and CXCR4 promoters were inserted separately into the recombinant vector and transfected into the acute T lymphocyte leukemia cell line H9. Treatment of stable transfected cells with four traditional Chinese medicine compounds resulted in the dose-dependent inhibition of the CXCR4 and CCR5 promoter activities. The dual-luciferase reporter assay provides a rapid and direct method to screen anti-AIDS/HIV drugs.