Serum amyloid A activation of human coronary artery endothelial cells exhibits a neutrophil promoting molecular profile.
BACKGROUND
Serum amyloid A (SAA) has been shown to be an active participant in atherosclerosis and cardiovascular diseases. SAA-stimulated human coronary artery endothelial cells (HCAEC) were reported to release pro-inflammatory cytokines, chemokines and adhesion molecules; however it remains unclear which putative SAA receptors are present in these cells and how they act. We investigated the effects of inflammatory stimuli on the expression of SAA receptors, signaling pathways and molecular profiles in HCAEC.


RESULTS
HCAEC were cultured in vitro and stimulated with SAA (1000nM) or IL-1β (1000pg/ml). Expression of mRNA was determined by qPCR, and expression and quantification of proteins were assessed by dot array blots and ELISA, respectively. Protein phosphorylation was determined by dot blot arrays and Western blots. We report that all potential SAA receptors tested (FPR2/ALX, RAGE, TANIS, TLR2, TLR4 and CLA-1/hSR-B1) are expressed in HCAEC. Importantly, IL-1β or SAA significantly increased solely the expression of the innate immune receptor TLR2. SAA upregulated the phosphorylation of ERK1/2, NF-κB (p65, p105) and JNK, as well as expression/release of IL-6, IL-8, G-CSF, GM-CSF, ICAM-1 and VCAM-1, all potent molecules involved in neutrophil-related activities. A TLR2-dependent positive feedback mechanism of SAA expression was found.


CONCLUSIONS
SAA stimulated responses in HCAEC target neutrophil rather than monocyte/macrophage activation.
University Medical Centre, Department of Rheumatology, Ljubljana, Slovenia.
Katja
K
Lakota
Katjusa
K
Mrak-Poljsak
Borut
B
Bozic
Matija
M
Tomsic
Snezna
S
Sodin-Semrl
D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000276:immunology / Q000378:metabolism*; D042783:Endothelial Cells / Q000276:immunology / Q000378:metabolism*; D025461:Feedback, Physiological; D020869:Gene Expression Profiling / Q000379:methods; D005786:Gene Expression Regulation; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism; D018375:Neutrophil Activation; D009504:Neutrophils / Q000276:immunology / Q000378:metabolism*; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism; D000685:Serum Amyloid A Protein / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection
D015815:Cell Adhesion Molecules; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D000685:Serum Amyloid A Protein