Membrane-Bound Thrombomodulin Regulates Macrophage Inflammation in Abdominal Aortic Aneurysm.
OBJECTIVE
Thrombomodulin (TM), a glycoprotein constitutively expressed in the endothelium, is well known for its anticoagulant and anti-inflammatory properties. Paradoxically, we recently found that monocytic membrane-bound TM (ie, endogenous TM expression in monocytes) triggers lipopolysaccharide- and gram-negative bacteria-induced inflammatory responses. However, the significance of membrane-bound TM in chronic sterile vascular inflammation and the development of abdominal aortic aneurysm (AAA) remains undetermined.


RESULTS
Implicating a potential role for membrane-bound TM in AAA, we found that TM signals were predominantly localized to macrophages and vascular smooth muscle cells in human aneurysm specimens. Characterization of the CaCl2-induced AAA in mice revealed that during aneurysm development, TM expression was mainly localized in infiltrating macrophages and vascular smooth muscle cells. To investigate the function of membrane-bound TM in vivo, transgenic mice with myeloid- (LysMcre/TM(flox/flox)) and vascular smooth muscle cell-specific (SM22-cre(tg)/TM(flox/flox)) TM ablation and their respective wild-type controls (TM(flox/flox) and SM22-cre(tg)/TM(+/+)) were generated. In the mouse CaCl2-induced AAA model, deficiency of myeloid TM, but not vascular smooth muscle cell TM, inhibited macrophage accumulation, attenuated proinflammatory cytokine and matrix metalloproteinase-9 production, and finally mitigated elastin destruction and aortic dilatation. In vitro TM-deficient monocytes/macrophages, versus TM wild-type counterparts, exhibited attenuation of proinflammatory mediator expression, adhesion to endothelial cells, and generation of reactive oxygen species. Consistently, myeloid TM-deficient hyperlipidemic mice (ApoE(-/-)/LysMcre/TM(flox/flox)) were resistant to AAA formation induced by angiotensin II infusion, along with reduced macrophage infiltration, suppressed matrix metalloproteinase activities, and diminished oxidative stress.


CONCLUSIONS
Membrane-bound TM in macrophages plays an essential role in the development of AAA by enhancing proinflammatory mediator elaboration, macrophage recruitment, and oxidative stress.
From the Department of Biochemistry and Molecular Biology (K.-C.W., G.-Y.S., M.-H.C., C.-Y.M., Y.-Y.H., B.-I.C., H.-L.W.), Institute of Basic Medical Sciences (K.-C.W.), Cardiovascular Research Center (K.-C.W., Y.-H.L., G.-Y.S., C.-Y.L., C.-Y.M., Y.-Y.H., B.-I.C., C.-H.L., H.-L.W.), Department of Internal Medicine (Y.-H.L.), Department of Pathology (H.-W.T.), and Department of Surgery (C.-Y.L., C.-H.L.), National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; and Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (T.-L.C.).
Kuan-Chieh
KC
Wang
From the Department of Biochemistry and Molecular Biology (K.-C.W., G.-Y.S., M.-H.C., C.-Y.M., Y.-Y.H., B.-I.C., H.-L.W.), Institute of Basic Medical Sciences (K.-C.W.), Cardiovascular Research Center (K.-C.W., Y.-H.L., G.-Y.S., C.-Y.L., C.-Y.M., Y.-Y.H., B.-I.C., C.-H.L., H.-L.W.), Department of Internal Medicine (Y.-H.L.), Department of Pathology (H.-W.T.), and Department of Surgery (C.-Y.L., C.-H.L.), National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; and Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (T.-L.C.).
Yi-Heng
YH
Li
From the Department of Biochemistry and Molecular Biology (K.-C.W., G.-Y.S., M.-H.C., C.-Y.M., Y.-Y.H., B.-I.C., H.-L.W.), Institute of Basic Medical Sciences (K.-C.W.), Cardiovascular Research Center (K.-C.W., Y.-H.L., G.-Y.S., C.-Y.L., C.-Y.M., Y.-Y.H., B.-I.C., C.-H.L., H.-L.W.), Department of Internal Medicine (Y.-H.L.), Department of Pathology (H.-W.T.), and Department of Surgery (C.-Y.L., C.-H.L.), National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; and Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (T.-L.C.).
Guey-Yueh
GY
Shi
From the Department of Biochemistry and Molecular Biology (K.-C.W., G.-Y.S., M.-H.C., C.-Y.M., Y.-Y.H., B.-I.C., H.-L.W.), Institute of Basic Medical Sciences (K.-C.W.), Cardiovascular Research Center (K.-C.W., Y.-H.L., G.-Y.S., C.-Y.L., C.-Y.M., Y.-Y.H., B.-I.C., C.-H.L., H.-L.W.), Department of Internal Medicine (Y.-H.L.), Department of Pathology (H.-W.T.), and Department of Surgery (C.-Y.L., C.-H.L.), National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; and Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (T.-L.C.).
Hung-Wen
HW
Tsai
From the Department of Biochemistry and Molecular Biology (K.-C.W., G.-Y.S., M.-H.C., C.-Y.M., Y.-Y.H., B.-I.C., H.-L.W.), Institute of Basic Medical Sciences (K.-C.W.), Cardiovascular Research Center (K.-C.W., Y.-H.L., G.-Y.S., C.-Y.L., C.-Y.M., Y.-Y.H., B.-I.C., C.-H.L., H.-L.W.), Department of Internal Medicine (Y.-H.L.), Department of Pathology (H.-W.T.), and Department of Surgery (C.-Y.L., C.-H.L.), National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; and Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (T.-L.C.).
Chawn-Yau
CY
Luo
From the Department of Biochemistry and Molecular Biology (K.-C.W., G.-Y.S., M.-H.C., C.-Y.M., Y.-Y.H., B.-I.C., H.-L.W.), Institute of Basic Medical Sciences (K.-C.W.), Cardiovascular Research Center (K.-C.W., Y.-H.L., G.-Y.S., C.-Y.L., C.-Y.M., Y.-Y.H., B.-I.C., C.-H.L., H.-L.W.), Department of Internal Medicine (Y.-H.L.), Department of Pathology (H.-W.T.), and Department of Surgery (C.-Y.L., C.-H.L.), National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; and Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (T.-L.C.).
Min-Hua
MH
Cheng
From the Department of Biochemistry and Molecular Biology (K.-C.W., G.-Y.S., M.-H.C., C.-Y.M., Y.-Y.H., B.-I.C., H.-L.W.), Institute of Basic Medical Sciences (K.-C.W.), Cardiovascular Research Center (K.-C.W., Y.-H.L., G.-Y.S., C.-Y.L., C.-Y.M., Y.-Y.H., B.-I.C., C.-H.L., H.-L.W.), Department of Internal Medicine (Y.-H.L.), Department of Pathology (H.-W.T.), and Department of Surgery (C.-Y.L., C.-H.L.), National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; and Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (T.-L.C.).
Chih-Yuan
CY
Ma
From the Department of Biochemistry and Molecular Biology (K.-C.W., G.-Y.S., M.-H.C., C.-Y.M., Y.-Y.H., B.-I.C., H.-L.W.), Institute of Basic Medical Sciences (K.-C.W.), Cardiovascular Research Center (K.-C.W., Y.-H.L., G.-Y.S., C.-Y.L., C.-Y.M., Y.-Y.H., B.-I.C., C.-H.L., H.-L.W.), Department of Internal Medicine (Y.-H.L.), Department of Pathology (H.-W.T.), and Department of Surgery (C.-Y.L., C.-H.L.), National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; and Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (T.-L.C.).
Yun-Yan
YY
Hsu
From the Department of Biochemistry and Molecular Biology (K.-C.W., G.-Y.S., M.-H.C., C.-Y.M., Y.-Y.H., B.-I.C., H.-L.W.), Institute of Basic Medical Sciences (K.-C.W.), Cardiovascular Research Center (K.-C.W., Y.-H.L., G.-Y.S., C.-Y.L., C.-Y.M., Y.-Y.H., B.-I.C., C.-H.L., H.-L.W.), Department of Internal Medicine (Y.-H.L.), Department of Pathology (H.-W.T.), and Department of Surgery (C.-Y.L., C.-H.L.), National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; and Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (T.-L.C.).
Tsung-Lin
TL
Cheng
From the Department of Biochemistry and Molecular Biology (K.-C.W., G.-Y.S., M.-H.C., C.-Y.M., Y.-Y.H., B.-I.C., H.-L.W.), Institute of Basic Medical Sciences (K.-C.W.), Cardiovascular Research Center (K.-C.W., Y.-H.L., G.-Y.S., C.-Y.L., C.-Y.M., Y.-Y.H., B.-I.C., C.-H.L., H.-L.W.), Department of Internal Medicine (Y.-H.L.), Department of Pathology (H.-W.T.), and Department of Surgery (C.-Y.L., C.-H.L.), National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; and Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (T.-L.C.).
Bi-Ing
BI
Chang
From the Department of Biochemistry and Molecular Biology (K.-C.W., G.-Y.S., M.-H.C., C.-Y.M., Y.-Y.H., B.-I.C., H.-L.W.), Institute of Basic Medical Sciences (K.-C.W.), Cardiovascular Research Center (K.-C.W., Y.-H.L., G.-Y.S., C.-Y.L., C.-Y.M., Y.-Y.H., B.-I.C., C.-H.L., H.-L.W.), Department of Internal Medicine (Y.-H.L.), Department of Pathology (H.-W.T.), and Department of Surgery (C.-Y.L., C.-H.L.), National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; and Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (T.-L.C.). halnwu@mail.ncku.edu.tw.
Chao-Han
CH
Lai
From the Department of Biochemistry and Molecular Biology (K.-C.W., G.-Y.S., M.-H.C., C.-Y.M., Y.-Y.H., B.-I.C., H.-L.W.), Institute of Basic Medical Sciences (K.-C.W.), Cardiovascular Research Center (K.-C.W., Y.-H.L., G.-Y.S., C.-Y.L., C.-Y.M., Y.-Y.H., B.-I.C., C.-H.L., H.-L.W.), Department of Internal Medicine (Y.-H.L.), Department of Pathology (H.-W.T.), and Department of Surgery (C.-Y.L., C.-H.L.), National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; and Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (T.-L.C.). halnwu@mail.ncku.edu.tw.
Hua-Lin
HL
Wu
D000804:Angiotensin II; D000818:Animals; D001012:Aorta, Abdominal / Q000276:immunology / Q000378:metabolism*; D017544:Aortic Aneurysm, Abdominal / Q000139:chemically induced / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D001025:Aortitis / Q000139:chemically induced / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002122:Calcium Chloride; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism*; D002478:Cells, Cultured; D002633:Chemotaxis; D004195:Disease Models, Animal; D004549:Elastin / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells / Q000276:immunology / Q000378:metabolism; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000276:immunology / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000276:immunology / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000276:immunology / Q000378:metabolism; D018384:Oxidative Stress; D034622:RNA Interference; D012189:Retrospective Studies; D015398:Signal Transduction; D018180:Thrombomodulin / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection
D018836:Inflammation Mediators; C546931:THBD protein, human; C569169:THBD protein, mouse; D018180:Thrombomodulin; D000804:Angiotensin II; D004549:Elastin; D020780:Matrix Metalloproteinase 9; C501830:Mmp9 protein, mouse; D002122:Calcium Chloride
abdominal aortic aneurysm; macrophages; monocytes; myeloid cells; thrombomodulin