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Signaling pathways in innate immunity
Author(s) -
SALMINEN A
Publication year - 2008
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2008.5241.x-i1
Subject(s) - innate immune system , pattern recognition receptor , tlr3 , inflammasome , biology , microbiology and biotechnology , tlr7 , tlr9 , receptor , pathogen associated molecular pattern , tlr4 , tlr2 , signal transduction , retinal pigment epithelium , inflammation , complement system , toll like receptor , immunology , immune system , neuroscience , retina , biochemistry , gene expression , dna methylation , gene
Inflammation has a key role in the pathogenesis of AMD. This lecture will review the recent progress in understanding the different host‐defence mechanisms against pathogens and self‐based danger signals involved in the activation of innate immunity. The innate defence system utilizes pattern recognition receptors (PRR) to respond to a variety of pathogen‐associated (PAMP) and danger‐associated (DAMP) molecular structures. Along with the well‐known complement and scavenger receptor systems, Toll‐like receptors (TLR) and NOD‐like receptors (NLR) have also a crucial part in host‐defence and these receptor systems can be activated both by PAMPs and DAMPs. Pattern recognition receptors are located either in cell surface, such as TLR2 and TLR4, or in intracellular locations, e.g. TLR3, TLR9 and all NLRs. PRRs show some specificity to ligands and also in downstream they activate different signaling pathways, most common of which are NF‐kB and IRF‐dependent pathways inducing inflammatory responses. Retinal pigment epithelial cells (RPE) have an important role in eye host‐defence, both at apical and basolateral surfaces. Most of the TLRs are expressed in RPE cells, especially TLR3 and TLR4, and they can participate in photoreceptor outer segment recognition. TLR3 can also suppress angiogenesis. The functions of NLRs, e.g. those forming inflammasomes, are still unknown, although the danger‐type of activation signals, such as oxidative stress and potassium efflux, are present in retinal pigment epithelium. It seems that the activation of innate immunity system via DAMPs and PRRs may have a central role in the pathogenesis of AMD.