Recruitment of immune cells across atrial endocardium in human atrial fibrillation.
BACKGROUND
Although clinical studies have suggested a link between inflammation markers and atrial fibrillation (AF), it is still unclear whether local immunologic responses actually exist in human atria during AF.


RESULTS
To address this point, human left appendages were obtained from 16 patients who underwent cardiac surgery (5 with sinus rhythm (SR) and 11 with AF) and subjected to immunohistochemical analysis. In all the AF specimens, adhesion and migration of CD45-reactive cells were consistently observed predominantly in the atrial endo- and subendomyocardium and more prominently than in SR. Most of them were immunologically active CD68-positive macrophages, whereas CD3-positive T cells infiltrated to a lesser extent. Scavenger-receptor A staining revealed maturation of macrophages not in the endocardium but in the midmyocardium, a gradient from endo- to midmyocardium. In the endocardium, along with adhesion molecules (intracellular adhesion molecule-1 and vascular cell adhesion molecule-1), a chemotactic protein-1, which facilitates the recruitment, was more abundantly expressed in AF than in SR. Cytokines including transforming growth factor-beta and interleukin-6 were frequently expressed by these macrophages.


CONCLUSIONS
These observations collectively imply active adhesion and recruitment of macrophages across the endocardium in human fibrillating atria, thereby supporting the concept of local immunologic inflammatory responses around the atrial endocardium of AF.
Yamashita
Takeshi
T
The Cardiovascular Institute, Tokyo, Japan. yamt-tky@umin.ac.jp
Sekiguchi
Akiko
A
Iwasaki
Yu-ki
YK
Date
Taro
T
Sagara
Koichi
K
Tanabe
Hiroaki
H
Suma
Hisayoshi
H
Sawada
Hitoshi
H
Aizawa
Tadanori
T
D056704:Adaptive Immunity; D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000032:analysis; D020517:Atrial Appendage / Q000276:immunology* / Q000473:pathology / Q000601:surgery; D001281:Atrial Fibrillation / Q000276:immunology* / Q000473:pathology / Q000601:surgery; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000032:analysis; D002465:Cell Movement; D016207:Cytokines / Q000032:analysis; D004699:Endocardium / Q000276:immunology* / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007113:Immunity, Innate; D007150:Immunohistochemistry; D018836:Inflammation Mediators / Q000032:analysis*; D008264:Macrophages / Q000276:immunology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D051117:Scavenger Receptors, Class A / Q000032:analysis; D013601:T-Lymphocytes / Q000276:immunology
D015703:Antigens, CD; D015815:Cell Adhesion Molecules; D016207:Cytokines; D018836:Inflammation Mediators; D051117:Scavenger Receptors, Class A