T. Watanabe et al., Localization of type IV collagen alpha chain in the myocardium of dilated and hypertrophic cardiomyopathy, JPN HEART J, 39(6), 1998, pp. 753-762
A total of 6 alpha chains [alpha 1 (IV) to alpha 6 (IV)] have been identifi
ed in type IV collagen. We examined the localization of these chains in the
myocardium of patients with dilated (DCM) and hypertrophic (HCM) cardiomyo
pathy. The localization of alpha 1 (IV)-alpha 6 (IV) in biopsy specimens of
5 patients with DCM and 4 with HCM was examined using immunohistochemistry
with monoclonal antibodies. Both alpha 1 (IV) and alpha 2 (IV) immunostain
ing formed thin homogeneous outlines around myocytes in control hearts. In
the DCM specimens, alpha 1 (IV) and alpha 2 (IV) immunostaining formed thic
k and irregular patterns around myocytes. Staining for alpha 1 (IV) and alp
ha 2 (IV) was also observed in some enlarged intercellular spaces. In 3 DCM
hearts, moderate staining for alpha 1 (IV) and alpha 2 (TV) was observed i
n small replacement fibrotic lesions. In large replacement fibrotic lesions
, no alpha 1 (IV) or a2 (IV) staining was observed. In the HCM specimens, a
l N and a2 (IV) staining formed thick homogeneous patterns around myocytes.
In the enlarged intercellular spaces, no alpha 1 (IV) or alpha 2 (IV) stai
ning was observed. No labeling for alpha 3 (IV)-alpha 6 (IV) was observed i
n any heart examined. In conclusion, the present results demonstrate that t
ype IV collagen consisting of alpha 1 and a2 chains appears in the fibrotic
lesions of DCM, indicating its contribution to the development of fibrotic
changes in the myocardium of DCM patients. In contrast, type IV collagen w
as restricted to the myocyte membrane in the HCM hearts. Fibrotic processes
in the intercellular spaces may differ between DCM and HCM hearts.