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ISSN:2171-6625
September 18-19, 2017 | Dallas, USA
4th International Conference on
NEUROLOGY AND NEUROIMMUNOLOGY
Alzheimer’s disease (AD) is characterized by brain deposits
of a mostly 40 to 42 amino acid peptide, the amyloid β
protein (Aβ), in senile plaques and intracranial blood vessels.
Aβ exhibits a strong tendency to aggregate into neurotoxic
oligomeric forms. The “amyloid hypothesis” of AD proposes
that elevated levels of Aβ oligomers trigger a downstream
cascade of oxidative and pro-inflammatory events which lead
to the widespread death of neurons and dementia. It has
been postulated that inadequate clearance of the amyloid
β protein (Aβ) plays an important role in the accumulation
of Aβ in sporadic late onset AD. While the blood brain
barrier (BBB) has taken the center stage in this field, little
information is available about the role of the lymphatic
system in Aβ clearance. We previously reported that Aβ is
cleared through the lymphatic system. We now assessed
lymphatic Aβ clearance by treating a mouse model of AD
amyloidosis with melatonin, an Aβ aggregation inhibitor and
immuno-regulatory neurohormone. We examined Aβ levels
in plasma and in lymph nodes of transgenic mice as surrogate
markers of vascular and lymphatic clearance, respectively.
Treatment with melatonin led to the following changes: 1-A
statistically significant increase in soluble monomeric Aβ40
and an increasing trend in Aβ42 in cervical and axillary lymph
nodes of treated mice. 2-Statistically significant decreases in
oligomeric Aβ40 and Aβ42 in the brain. 3-Lack of changes of
Aβ40 and Aβ42 levels in plasma with aging. 4-Elimination of
premature mortality in transgenic mice. Several mechanisms
involving the lymphatic system in the clearance of cell debris
and waste solutes, including amyloid, from the mammalian
central nervous system will be discussed. These include
lymphatic clearance pathways along cranial nerves, spinal
nerves, the cribriform plate, meningeal lymphatic channels
and paravascular pathways including the glymphatic system.
In addition to the pathways of clearance mentioned here,
it is likely that active cellular transport mechanisms are in
play. For example, the murine PirB (paired immunoglobulin-
like receptor B) and its human ortholog LilrB2 (leukocyte
immunoglobulin-like receptor B2), present in human brain,
are receptors for Aβ peptides. These receptors, which are
members of the immunoglobulin superfamily, are found in
dendritic cells. These cells are known to “travel” between
brain and lymph nodes. The data that will be presented
suggest that abnormalities in the clearance through the
lymphatic system may contribute to the development of
brain amyloidosis.
e:
The role of the lymphatic system in the development of brain amyloidosis
Miguel Pappolla
St. Michael’s Pain and Spine Clinics, USA
J Neurol Neurosci, 8:5
DOI: 10.21767/2171-6625-C1-003