Down Regulation of MyD88 in Macrophages Treated with Liposomes Composed of Phosphatidylserine

We have recently demonstrated that liposomes composed of phosphatidylserine (PS-liposomes) suppressed nitric oxide and inflammatory cytokine productions following LPS stimulation in macrophages. In this study, we examined the effect of PS-liposomes on expressions of TLR-4 and MyD88, which are essential for the signal transduction in LPS stimulation. Expression of MyD88 was suppressed when macrophages were treated with PS-liposomes, but not with liposomes of phosphatidylcholine. No change in TLR-4 expression was observed. MyD88 suppression was restored to the control levels when cells were pre-treated with anti-TGF-β antibody, suggesting that TGF-β plays an important role in down-regulation of MyD88 following PS-liposome treatment.