Lewy bodies are abnormal aggregates of protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 that develop inside nerve cells in Parkinson's disease

Parkinson's disease

Parkinson's disease is a degenerative disorder of the central nervous system...

 (PD), Lewy Body Dementia

Dementia with Lewy bodies

Dementia with Lewy bodies , also known under a variety of other names including Lewy body dementia, diffuse Lewy body disease, cortical Lewy body disease, and senile dementia of Lewy type, is a type of dementia closely allied to both Alzheimers and Parkinson's Diseases...

 and some other disorders. They are identified under the microscope

Microscope

A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...

 when histology

Histology

Histology is the study of the microscopic anatomy of cells and tissues of plants and animals. It is performed by examining cells and tissues commonly by sectioning and staining; followed by examination under a light microscope or electron microscope...

 is performed on the brain

Brain

The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

.

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

Eosinophilic

Eosinophilic refers to the staining of certain tissues, cells, or organelles after they have been washed with eosin, a dye.Eosin is an acidic dye; thus, the structure being stained is basic....

 cytoplasm

Cytoplasm

The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...

ic 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

Alpha-synuclein

Alpha-synuclein is a protein that, in humans, is encoded by the SNCA gene. An alpha-synuclein fragment, known as the non-Abeta component of Alzheimer's disease amyloid, originally found in an amyloid-enriched fraction, is shown to be a fragment of its precursor protein, NACP, by cloning of the...

. 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

Pick's disease

Pick's disease, is a rare neurodegenerative disease that causes progressive destruction of nerve cells in the brain. Symptoms include loss of speech , and dementia. While some of the symptoms can initially be alleviated, the disease progresses and patients often die within two to ten years...

 and corticobasal degeneration

Corticobasal degeneration

Corticobasal degeneration or Corticobasal Ganglionic Degeneration is a rare progressive neurodegenerative disease involving the cerebral cortex and the basal ganglia. It is characterized by marked disorders in movement and cognitive dysfunction...

, as well as in patients with other tauopathies. They are also seen in cases of multiple system atrophy

Multiple system atrophy

Multiple system atrophy is a degenerative neurological disorder. MSA is associated with the degeneration of nerve cells in specific areas of the brain. This cell degeneration causes problems with movement, balance and other autonomic functions of the body such as bladder control or blood pressure...

, particularly the Parkinsonian variant.

Cell biology

A Lewy body is composed of the protein alpha-synuclein

Alpha-synuclein

Alpha-synuclein is a protein that, in humans, is encoded by the SNCA gene. An alpha-synuclein fragment, known as the non-Abeta component of Alzheimer's disease amyloid, originally found in an amyloid-enriched fraction, is shown to be a fragment of its precursor protein, NACP, by cloning of the...

 associated with other proteins such as ubiquitin

Ubiquitin

Ubiquitin is a small regulatory protein that has been found in almost all tissues of eukaryotic organisms. Among other functions, it directs protein recycling.Ubiquitin can be attached to proteins and label them for destruction...

, neurofilament protein, and alpha B crystallin. Tau proteins may also be present, and Lewy bodies may occasionally be surrounded by neurofibrillary tangle

Neurofibrillary tangle

Neurofibrillary Tangles are aggregates of hyperphosphorylated tau protein that are most commonly known as a primary marker of Alzheimer's Disease. Their presence is also found in numerous other diseases known as Tauopathies...

s.,
It is believed that Lewy bodies represent an aggresome

Aggresome

An aggresome is a proteinaceous inclusion body that forms when cellular degradation machinery is impaired or overwhelmed, leading to an accumulation of protein for disposal...

 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

Alpha-synuclein

Alpha-synuclein is a protein that, in humans, is encoded by the SNCA gene. An alpha-synuclein fragment, known as the non-Abeta component of Alzheimer's disease amyloid, originally found in an amyloid-enriched fraction, is shown to be a fragment of its precursor protein, NACP, by cloning of the...

 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

Hippocampus

The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

 in Alzheimer's disease

Alzheimer's disease

Alzheimer's disease also known in medical literature as Alzheimer disease is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death...

.

Cultural reference

Kelsey Grammer

Kelsey Grammer

Allen Kelsey Grammer is an American actor and comedian. He is most widely known for his two-decade portrayal of psychiatrist Dr. Frasier Crane on the sitcoms Cheers and Frasier...

's lead character, mayor of Chicago

Mayor of Chicago

The Mayor of Chicago is the chief executive of Chicago, Illinois, the third largest city in the United States. He or she is charged with directing city departments and agencies, and with the advice and consent of the Chicago City Council, appoints department and agency leaders.-Appointment...

 Tom Kane in the television series Boss

Boss (TV series)

Boss is an American-Canadian political drama television series created by Farhad Safinia. The series stars Kelsey Grammer as Tom Kane, the mayor of Chicago, who has recently been diagnosed with a degenerative neurological disorder....

, suffers from early-stage Lewy body.