Th2-predominant inflammation and blockade of IFN-gamma signaling induce aneurysms in allografted aortas.
Abdominal aortic aneurysms (AAAs) cause death due to complications related to expansion and rupture. The underlying mechanisms that drive AAA development remain largely unknown. We recently described evidence for a shift toward T helper type 2 (Th2) cell responses in human AAAs compared with stenotic atheromas. To evaluate putative pathways in AAA formation, we induced Th1- or Th2-predominant cytokine environments in an inflammatory aortic lesion using murine aortic transplantation into WT hosts or those lacking the receptors for the hallmark Th1 cytokine IFN-gamma, respectively. Allografts in WT recipients developed intimal hyperplasia, whereas allografts in IFN-gamma receptor-deficient (GRKO) hosts developed severe AAA formation associated with markedly increased levels of MMP-9 and MMP-12. Allografts in GRKO recipients treated with anti-IL-4 antibody to block the characteristic IL-4 Th2 cytokine or allografts in GRKO hosts also congenitally deficient in IL-4 did not develop AAA and likewise exhibited attenuated collagenolytic and elastolytic activities. These observations demonstrate an important dichotomy between cellular immune responses that induce IFN-gamma- or IL-4-dominated cytokine environments. The findings establish important regulatory roles for a Th1/Th2 cytokine balance in modulating matrix remodeling and have important implications for the pathophysiology of AAAs and arteriosclerosis.
Shimizu
Koichi
K
The Donald W. Reynolds Cardiovascular Clinical Research Center, Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. ksmz@rics.bwh.harvard.edu
Shichiri
Masayoshi
M
Libby
Peter
P
Lee
Richard T
RT
Mitchell
Richard N
RN
D000818:Animals; D001012:Aorta, Abdominal / Q000166:cytology / Q000378:metabolism / Q000473:pathology / Q000637:transplantation; D017544:Aortic Aneurysm, Abdominal / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D039481:CD11b Antigen / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000378:metabolism*; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D015847:Interleukin-4 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008264:Macrophages / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000378:metabolism; D017471:Receptors, Interferon / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D018418:Th2 Cells / Q000276:immunology*; D014184:Transplantation, Homologous; D000096743:Interferon gamma Receptor
D039481:CD11b Antigen; D007371:Interferon-gamma; D015847:Interleukin-4; D020782:Matrix Metalloproteinases; D012333:RNA, Messenger; D017471:Receptors, Interferon; D000096743:Interferon gamma Receptor