Differential expression of collagen type V and XI alpha-1 in human ascending thoracic aortic aneurysms

Ann Thorac Surg. 2009 Aug;88(2):506-13. doi: 10.1016/j.athoracsur.2009.04.030.


Background: The molecular mechanisms leading to ascending thoracic aortic aneurysms (ATAAs) remain unknown. We hypothesized that alterations in expression levels of specific fibrillar collagens occur during the aneurysmal process.

Methods: Surgical samples from ascending aortas from patients with degenerative ATAAs were subdivided by aneurysm diameter: small, 5 to 6 cm; medium, 6 to 7 cm; and large, greater than 7 cm; and compared with nonaneurysmal aortas (mean diameter, 2.3 cm).

Results: Histology, immunofluorescence, and electron microscopy demonstrated greater disorganization of extracellular matrix constituents in ATAAs as compared with control with an increase in collagen alpha1(XI) within regions of cystic medial degenerative lesions. Real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) showed collagens type V and alpha1(XI) were significantly and linearly increased in ATAAs as compared with control (p < 0.001). There was no change in the messenger ribonucleic acid (mRNA) expression levels of collagens type I and III. Western blot analysis showed collagens type I and III were significantly decreased and collagens alpha1(XI) and V were significantly increased and were linearly correlated with the size of the aneurysm (p < 0.001 for both).

Conclusions: These results demonstrate that increased collagen alpha1(XI) and collagen V mRNA and protein levels are linearly correlated with the size of the aneurysm and provide a potential mechanism for the generation and progression of aneurysmal enlargement.

Publication types

  • Comparative Study
  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aortic Aneurysm, Thoracic / metabolism*
  • Aortic Aneurysm, Thoracic / physiopathology
  • Collagen Type V / metabolism*
  • Collagen Type XI / metabolism*
  • Disease Progression
  • Extracellular Matrix / pathology
  • Humans
  • Immunohistochemistry
  • Proteins / analysis
  • RNA, Messenger / analysis
  • Reverse Transcriptase Polymerase Chain Reaction


  • Collagen Type V
  • Collagen Type XI
  • Proteins
  • RNA, Messenger