Toll-like Receptors in Pathogenesis of Neurodegenerative Diseases and
their Therapeutic Potential
Toll-like receptors (TLRs) are a family of pattern-recognition receptors
(PRRs) triggered by pathogen-derived and tissue-damage-related ligands.
TLRs were previously believed to only be expressed in immune cells.
However, it is now confirmed that they are ubiquitously expressed in
cells within the body including neurons, astrocytes, and microglia of
the central nervous system (CNS). Activation of TLRs is capable of
inducing immunologic and inflammatory responses to injury or infection
of CNS. This response is self-limiting that usually resolves once the
infection has been eradicated or the tissue damage has been repaired.
However, the persistence of inflammation-inducing insults or a failure
in normal resolution mechanisms may result in overwhelming inflammation
which may induce neurodegeneration. This implies that TLRs may play a
role in mediating the link between inflammation and neurodegenerative
diseases namely Alzheimer’s disease (AD), Parkinson’s disease (PD), and
amyotrophic lateral sclerosis (ALS). So, new therapeutic approaches that
specifically target TLRs may be developed by better understanding TLR
expression mechanisms in the CNS and their connections to particular
neurodegenerative disorders. Therefore, this review paper discussed the
role of TLRs in neurodegenerative diseases.