Poly-vinyl pyrrolidone (PVP)-coated silver (Ag) nanoparticles (Ag-PVP): A potential to regulate chlamydia trachomatis inflammation

Chlamydia trachomatis is an important cause of sexually transmitted infection worldwide. Excessive inflammatory responses play a key role in its disease progression. Early intervention strategies that can reduce inflammatory responses could benefit control efforts in reducing the disease severity. Previously we reported that Ag-PVP reduced pro-inflammatory cytokines produced by C. trachomatis-infected mouse J774 macrophages. Here we reveal that Ag-PVP also exerts its anti-inflammatory effect on primary mouse bone marrow-derived macrophages (BMDM). The MTT assay showed that Ag-PVP was relatively non-toxic to BMDM (up to 6.25 μg/mL) over 72 hr. By ELISA we document that Ag-PVP (2.5 μg/mL) inhibited IL-6 (cytokine) and CXCL10 (chemokine) as produced by C. trachomatis-infected BMDM. Employing qRT-PCR we demonstrate that Ag-PVP down-regulated the expression of the surface receptors, TLR2 and NOD2, as triggered by C. trachomatis on J774 macrophages, suggesting that Ag-PVP may exert its anti-inflammatory effect by interfering with their expression. Our results show the anti-inflammatory effect of Ag-PVP on BMDM is not associated with cell death. Of importance our data demonstrates that Ag-PVP may mediate its antiinflammatory effect in infected macrophages by reducing macrophage surface receptors expression.