Toll-like receptors (TLRs) in aquatic animals: Signaling pathways, expressions and immune responses

The WNT Signaling Pathway Contributes to Dectin-1-Dependent Inhibition of Toll-Like Receptor-Induced Inflammatory Signature

“…A ctivation of host pattern recognition receptors (PRRs) upon engagement by invading microbe or microbe-associated molecular patterns to elicit protective immune responses is one of the most well-studied physiological processes (1)(2)(3)(4). However, dampening of the protective innate immune cell functions during multiple infections upon engagement of many PRRs constituting different families has not been explored.…”

A member of the Tlr family is involved in dsRNA innate immune response in Paracentrotus lividus sea urchin

“…Genes encoding TLR receptors were discovered in Drosophila melanogaster, where they were first demonstrated to play a role in the establishment of the embryonic dorso-ventral axis (Hashimoto et al, 1988) and were later assigned a role in immunity (Hoffmann, 2003;Lemaitre et al, 1996). TLRs have been found in all metazoans, confirming their important role in immunity in mammals (Kawai and Akira, 2010), the ascidian Ciona intestinalis (Sasaki et al, 2009), the nematode Caenorhabditis elegans (Millet and Ewbank, 2004), sponges (Wiens et al, 2007), the Lytechinus variegatus and Strongylocentrotus purpuratus sea urchins (Buckley and Rast, 2012;Smith et al, 2006), and other invertebrates (for a review see Rauta et al, 2014).…”

Characterization of Toll-like receptor gene expression in goldfish (Carassius auratus) during Dactylogyrus intermedius infection

“…The innate immune system constitutes the first line of defense against a broad spectrum of invading pathogens through pattern recognition receptors (PPRs), which recognize highly conserved microbial structures known as pathogen associated molecular patterns (PAMPs) (Jones and Dangl, 2006;Magnad ottir, 2006;Rauta et al, 2014). Among various PRRs, the family of Toll-like receptors (TLRs) is one of the earliest and best characterized innate immune receptors (Wei et al, 2014;Zhang et al, 2014).…”

“…Shortly after this discovery, Stafford et al (2003) reported the first teleost TLR gene in goldfish. Thus far, at least 20 TLR types (TLR1,2,3,4,5M,5S,7,8,9,13,14,18,19,20,21,22,23,24,25,26 and 27) have been continually discovered and characterized for understanding their functions in diverse aquatic animals (Rauta et al, 2014;Wang et al, 2015;Zhang et al, 2014). What's more, the majority of researches on fish were focused on the roles of fish TLRs in the response to bacterial and viral infections, while the studies on their functions in parasitic infection were relatively insufficient.…”

“…Species of this genus are primarily attached on the gills of cyprinid fishes and feed on mucus, epithelial cells, and blood from the gills (Gibson et al, 1996;Tu et al, 2013). Moreover, fishes heavily infected with Dactylogyrus are more easily subjected to secondary infections with other causative agents, resulting in severe damage to the host and serious economic losses in aquaculture industry (Reed et al, 2009;Woo and Gregory, 2014). Although Dactylogyrus intermedius is considered as one of the most common pathogens of goldfish, the roles of TLRs during the infection of this parasite are still vacant.…”