Toll-like receptors in immunity and inflammatory diseases: Past, present, and future.
Int Immunopharmacol 2018;
59:391-412. [PMID:
29730580 PMCID:
PMC7106078 DOI:
10.1016/j.intimp.2018.03.002]
[Citation(s) in RCA: 408] [Impact Index Per Article: 68.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 02/28/2018] [Accepted: 03/01/2018] [Indexed: 02/07/2023]
Abstract
The immune system is a very diverse system of the host that evolved during evolution to cope with various pathogens present in the vicinity of environmental surroundings inhabited by multicellular organisms ranging from achordates to chordates (including humans). For example, cells of immune system express various pattern recognition receptors (PRRs) that detect danger via recognizing specific pathogen-associated molecular patterns (PAMPs) and mount a specific immune response. Toll-like receptors (TLRs) are one of these PRRs expressed by various immune cells. However, they were first discovered in the Drosophila melanogaster (common fruit fly) as genes/proteins important in embryonic development and dorso-ventral body patterning/polarity. Till date, 13 different types of TLRs (TLR1-TLR13) have been discovered and described in mammals since the first discovery of TLR4 in humans in late 1997. This discovery of TLR4 in humans revolutionized the field of innate immunity and thus the immunology and host-pathogen interaction. Since then TLRs are found to be expressed on various immune cells and have been targeted for therapeutic drug development for various infectious and inflammatory diseases including cancer. Even, Single nucleotide polymorphisms (SNPs) among various TLR genes have been identified among the different human population and their association with susceptibility/resistance to certain infections and other inflammatory diseases. Thus, in the present review the current and future importance of TLRs in immunity, their pattern of expression among various immune cells along with TLR based therapeutic approach is reviewed.
TLRs are first described PRRs that revolutionized the biology of host-pathogen interaction and immune response
The discovery of different TLRs in humans proved milestone in the field of innate immunity and inflammation
The pattern of expression of all the TLRs expressed by human immune cells
An association of various TLR SNPs with different inflammatory diseases
Currently available drugs or vaccines based on TLRs and their future in drug targeting along with the role in reproduction, and regeneration
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