Figure 6.

SWCNTs trigger TLR2 and TLR4 activation. (a) HEK 293 cells co-transfected with human TLR2 (HEK-Blue™ hTLR2) or TLR4 (HEK-Blue™ hTLR4 cells) and an NF-κB/AP-1-secreted embryonic alkaline phosphatase (SEAP) reporter gene were exposed to SWCNT (30 µg/mL) for 12 h in the presence or absence of 10% FBS. LPS (0.1 µg/mL) was included as a positive control. SWCNTs activated TLR2/4 independently of the presence of serum in the culture medium. Data are shown as mean values ± S.D. of three independent experiments. (b) Schematic diagram showing the ‘sensing’ of SWCNTs by HMDMs via TLR receptors resulting in MyD88-dependent activation of NF-kB leading to nuclear translocation of NF-kB with transcription and secretion of CCL5. The secreted chemokine(s) induce chemotaxis of immune cells bearing the corresponding receptor(s).