PolyI:C Upregulated CCR5 and Promoted THP-1-Derived Macrophage Chemotaxis via TLR3/JMJD1A Signalling.

OBJECTIVE: This study aimed to evaluate the specific roles of polyinosinic:polycytidylic acid (polyI:C) in macrophage chemotaxis and reveal the potential regulatory mechanisms related to chemokine receptor 5 ( CCR5 ).

MATERIALS AND METHODS: In this experimental study, THP-1-derived macrophages (THP1-Mφs) induced from THP- 1 monocytes were treated with 25 μg/mL polyI:C. Toll-like receptor 3 ( TLR3 ), Jumonji domain-containing protein (JMJD)1A, and JMJD1C small interfering RNA (siRNAs) were transfected into THP1-Mφs. Quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) was used to detect the expression levels of TLR3 , CCR5 , 23 Jumonji C domain-containing histone demethylase family members, JMJD1A , and JMJD1C in THP1-Mφs with different siRNAs transfections. Western blot was performed to detect JMJD1A , JMJD1C, H3K9me2, and H3K9me3 expressions. A transwell migration assay was conducted to detect THP1-Mφ chemotaxis toward chemokine ligand 3 (CCL3). A chromatin immunoprecipitation (ChIP) assay was performed to detect H3K9me2-CCR5 complexes in THP1- Mφs.

RESULTS: PolyI:C significantly upregulated CCR5 in THP1-Mφs and promoted chemotaxis toward CCL3 (P<0.05); these effects were significantly inhibited by TLR3 siRNA (P<0.01). JMJD1A and JMJD1C expression was significantly upregulated in polyI:C-stimulated THP1-Mφs, while only JMJD1A siRNA decreased CCR5 expression (P<0.05). JMJD1A siRNA significantly increased H3K9me2 expression in THP1-Mφs but not in polyI:C-stimulated THP1-Mφs. The ChIP result revealed that polyI:C significantly downregulated H3K9me2 in the promoter region of CCR5 in THP1- Mφs.

CONCLUSION: PolyI:C can enhance THP1-Mφ chemotaxis toward CCL3 regulated by TLR3 /JMJD1A signalling and activate CCR5 expression by reducing H3K9me2 in the promoter region of CCR5 .