Background: The differences between acute coronary syndrome (ACS) and stable angina pectoris (SAP) in Toll-like receptor (TLR) expression levels in coronary plaques are not well known. TLR gene expression levels were examined, not only in peripheral blood mononuclear cells (PBMCs), but also in coronary plaques in ACS and SAP patients.
Methods and results: TLR gene expression levels were examined in PBMCs using real-time RT-PCR in 27 ACS patients, 45 SAP patients and 28 control subjects. TLR2 and TLR4 expression levels in the PBMCs were significantly higher in the ACS group than in the SAP group. TLR9 expression levels were not significantly different among the 3 groups. TLR gene expression levels were also measured in directional coronary atherectomy (DCA) samples from 9 ACS and 14 SAP patients. The TLR2 expression levels in the DCA samples did not significantly differ between the 2 groups. The TLR4 expression levels were significantly higher in the ACS group than in the SAP group.
Conclusions: The results suggest that TLR4 signaling could be more associated with plaque destabilization than with plaque progression. TLR4 expression control may be a novel target for ACS treatment.