Distribution of collagen XVII in the human brain.

We have recently discovered collagen XVII to be present in neurons of the human central nervous system. Collagen XVII has previously been primarily studied in the field of dermatopathology since it is abundantly expressed in the skin, which, like the nervous system, is ectodermal in origin. A link between dermatopathological and neurological entities has been implied due to clinical case studies revealing an association between bullous pemphigoid and age-related neurodegenerative disorders. The objective of this study was to assess the distribution of collagen XVII in the human brain in relation to normal ageing. Post-mortem brain tissue was obtained from 11 neurologically unimpaired subjects who had died from cardiovascular causes at the age of 17 to 78 years. Collagen XVII expression in various neuroanatomical regions, representing essentially the entire human brain, was then assessed using immunohistochemistry. We found collagen XVII to be expressed widely in the brain and to be located primarily in the soma and proximal axons of neurons. In contrast, glial cells did not express collagen XVII. The expression varied strikingly between different neuroanatomical regions, being most notable in motor nuclei and Betz cells followed by pyramidal neurons. There was no correlation between collagen XVII expression and variables such as gender, age at death, post-mortem delay and fixation time whereas a mode of death leading to notable neuronal ischemia depleted the protein expression. Many neurodegenerative disorders display a specific pattern of neuroanatomical involvement, thus the regionally variable expression of collagen XVII offers new prospects for research.