Comparative pathological studies on cerebral amyloid angiopathy and hyalinosis of microvessels in the human brain

Objective To investigate the amyloid deposit component of extracelluar matrix(ECM)of cerebral amyloid angiopathy(CAA) and composition of hyaline material in cerebral blood vessels respectively.Methods Immunohistochemistry was used to observe samples obtained from 10 autopsy cases with marked amyloid angiopathy, 8 cases presenting hyaline changes of cerebral vessels and a control group of 8 postmortem cases without encephalopathy.A number of primary antisera were used to visualise different components of ECM,smooth muscle cells and endothelial cells under the microscope. Results The controls showed negative result with β-A 4 and slightly positive with collagen Ⅳ.The deposit of ECM material of CAA indicating laminin and collagen Ⅳ occurred particularly in the media.The immunostained markers of adventitia did not reveal much changes as compared with the controls.The composition of the hyaline material included collagen types Ⅰ,Ⅲ,Ⅴ and Ⅳ as well as basal lamina components collagen Ⅳ and laminin,but the actin decreased.Conclusion Severe amyloid angiopathy with deposition of collagen type Ⅳ and laminin and loss of the fibrous collagens in media may make the arteries more susceptible to rupture and hemorrhage. Degeneration of the media associated with deposition of collagen types Ⅰ Ⅲ Ⅴ Ⅳ, as well as other components of ECM, and a severe reduction of actin in the media jeopardise the regulatory functions of the afflicted vessels.