Myocardial injury modulates the innate immune system and changes myocardial sensitivity.
OBJECTIVE
Transverse aortic constriction (TAC) results in a transient increase of proinflammatory cytokines, which return to baseline levels within 3 d. In contrast to cytokine baseline levels, the myocardium remains capable to respond even stronger to a new stimulus. As the molecular mechanisms for this phenomenon are unknown, we tested whether TAC modulates the innate immune system in mice and changes the inflammatory reaction to a new stimulus.


METHODS
Following 3 d of TAC or sham-operation procedure (SOP), LPS (20 mg/kg) or PBS (control) were administered intraperitoneal for 10 min as well as for 6 h. Hemodynamic parameters were recorded to measure the effects of TAC and LPS. After TAC/SOP alone CD14 expression was monitored and after additional 6 h of LPS/PBS the expression of CD14, TLR4 and proinflammatory cytokines were determined by western-blot, ELISA and RNase protection assay, respectively. Following TAC/SOP and 10 min of LPS/PBS, NFkappaB activation was investigated by EMSA.


RESULTS
TAC induced cardiac hypertrophy and elevated blood pressure. LPS application led to hypotension and other symptoms of sepsis. CD14 expression increased after TAC alone and even further after additional LPS challenge. However, we did not detect changes of TLR4 expression. Also NFkappaB activation increased after LPS challenge higher in the TAC than in the SOP group. LPS-stimulation induced also higher cytokine expression in the TAC than in the SOP group.


CONCLUSIONS
TAC modulates innate immunity by regulating the expression of CD14 and changes the myocardial tissue to respond more powerful to LPS.
Baumgarten
Georg
G
Department of Anesthesiology and Intensive Care Medicine, Universitätsklinikum Bonn, Sigmund-Freud Strasse 25, 53105, Bonn, Germany. georg.baumgarten@ukb.uni-bonn.de
Kim
Se-Chan
SC
Stapel
Heidi
H
Vervölgyi
Volker
V
Bittig
Anne
A
Hoeft
Andreas
A
Meyer
Rainer
R
Grohé
Christian
C
Knuefermann
Pascal
P
D000818:Animals; D009202:Cardiomyopathies / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology; D016207:Cytokines / Q000032:analysis / Q000235:genetics; D006321:Heart / Q000187:drug effects*; D007113:Immunity, Innate; D018950:Lipopolysaccharide Receptors / Q000032:analysis; D008070:Lipopolysaccharides / Q000633:toxicity; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D015398:Signal Transduction; D051197:Toll-Like Receptor 4 / Q000032:analysis
D016207:Cytokines; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4