Robinin modulates TLR/NF-κB signaling pathway in oxidized LDL induced human peripheral blood mononuclear cells

This study was designed to investigate whether robinin administration modulates toll-like receptor (TLR) and nuclear factor-kappa B (NF-κB) signaling pathway in oxidized LDL induced human peripheral blood mononuclear cells (hPBMCs). The hPBMCs were isolated from healthy human volunteers and the cells were cultured in collagen coated plates at 37°C with 5% CO2 and RPMI as culture medium and were grouped as follows: Group I - control, group II - OxLDL treated and group III - OxLDL+robinin (6μg/ml). We measured mRNA expression of TLR2 and TLR4 by reverse-transcriptase polymerase chain reaction (RT-PCR) and NF-κB transcription factor assay (ELISA), and western blotting studies were done for knowing expression of monocyte chemotactic protein-1 (MCP 1), tumor necrosis factor-alpha (TNF-α) interleukin-6 (IL-6) and vascular cell adhesion molecule 1 (VCAM-1). The result indicates that OxLDL that induces hPBMCs showed an upregulated expression of TLR2, TLR4, NF-κB, pro-inflammatory cytokines and VCAM-1. Robinin inhibited the ox-LDL induced TLR2 and TLR4 expression at mRNA level and inhibited the translocation of NF-κB p65 by modulating the TLR-NF-κB signaling pathway thereby inhibiting cytokine production and down regulated inflammatory enzymes like cyclooxygenase (COX), lipoxygenase (LOX), nitric oxide synthase (NOS) and prostaglandin E2 (PGE2), thus having protective effect against the ox-LDL induced inflammation stress in hPBMCs by inhibiting TLR4-NF-κB signaling pathway.