Lewy body



Lewy bodies are abnormal aggregates of protein that develop inside nerve cells in Parkinson's disease (PD), Lewy Body Dementia and some other disorders. They are identified under the microscope when histology is performed on the brain.

Lewy bodies appear as spherical masses that displace other cell components. There are two morphological types: classical (brain stem) Lewy bodies and cortical Lewy bodies. A classical Lewy body is an eosinophilic cytoplasmic inclusion that consists of a dense core surrounded by a halo of 10-nm wide radiating fibrils, the primary structural component of which is alpha-synuclein. In contrast, a cortical Lewy body is less well defined and lacks the halo. Nonetheless, it is still made up of alpha-synuclein fibrils. Cortical Lewy bodies are a distinguishing feature of Dementia with Lewy bodies (DLB) and may occasionally be seen in ballooned neurons characteristic of Pick's disease and corticobasal degeneration, as well as in patients with other tauopathies. They are also seen in cases of multiple system atrophy, particularly the Parkinsonian variant.

History
Lewy bodies were discovered by Frederic Lewy in 1912.

Cell biology
A Lewy body is composed of the protein alpha-synuclein associated with other proteins such as ubiquitin, neurofilament protein, and alpha B crystallin. Tau proteins may also be present, and Lewy bodies may occasionally be surrounded by neurofibrillary tangles.,

It is believed that Lewy bodies represent an aggresome response in the cell.

Lewy neurites
Similarly to Lewy bodies, Lewy neurites are proteinaceous formations found in neurones of the disease brain, comprising abnormal α-synuclein filaments and granular material. They are a feature of α-synucleinopathies such as Dementia with Lewy bodies, Parkinson's disease and multiple system atrophy (MSA), and are found in the CA2-3 region of the hippocampus in Alzheimer's disease.