Inducible cardiac ischaemia is related to a decrease in the whole-blood Toll-like receptor 2 and 4 response

Area of Science:

• Cardiovascular Medicine
• Immunology
• Molecular Biology

Background:

• Toll-like receptor (TLR) activation drives inflammatory responses crucial to atherosclerosis progression.
• Previous research indicates TLR-dependent leukocyte responsiveness is reduced post-percutaneous coronary intervention or vascular surgery.
• Cytokine release after TLR-2 and TLR-4 stimulation correlates with fractional flow reserve, hinting chronic ischemia enhances inflammation.

Purpose of the Study:

• To investigate the link between leukocyte TLR-2 and TLR-4 responsiveness and pre-existent or inducible ischemia.
• To assess these responses in patients undergoing single-photon emission computed tomography-myocardial perfusion imaging (SPECT-MPI).

Main Methods:

• Measured TLR-2, TLR-4, and CD11b expression on monocytes from 100 patients with suspected coronary artery disease.
• Assessed IL-8 levels post-whole-blood stimulation with Pam3Cys (TLR-2) and LPS (TLR-4) before and after myocardial stress testing.
• Categorized patients into groups based on SPECT-MPI findings: reversible defect, irreversible defect, and no defect.

Main Results:

• Myocardial stress reduced TLR-4 and CD11b expression.
• TLR-induced IL-8 production after stress decreased, particularly in patients with reversible defects.
• Pre-stress TLR-induced IL-8 production did not correlate with SPECT-MPI results.

Conclusions:

• Inducible ischemia is associated with diminished whole-blood TLR-2 and TLR-4 responses.
• TLRs may play a regulatory role in preventing excessive inflammation during acute ischemia.