Fol. Biol. 2005, 51, 188-197
Toll-like Receptors. II. Distribution and Pathways Involved in TLR Signalling
The innate immune system senses invading microorganisms by a phylogenetically conserved family of proteins - TLRs. They are expressed in several types of cells that represent a route of entry of pathogens into the host organism and that can contribute to protection against infection. Except for cells of the immune system, TLRs are present in epithelial cells of the skin, respiratory, intestinal, and genitourinary tracts that form the first protective barrier to invading pathogens. Polarized regulation of TLR expression in epithelial cells explains why pathogenic but not commensal bacteria elicit inflammatory responses. TLR-induced intracellular signalling pathways show remarkable complexity: apart from a common signalling pathway, additional signalling pathways specific for each of the TLRs are responsible for a fine tuning of the immune response, thus securing effective pathogen-directed biological responses.
Keywords
TLR distribution, MyD88, IRF, NFKB.
Funding
The study was supported by the Research Programs of the Ministry of Education of the Slovak Republic: VEGA 1/0543/03.
References
Copyright
This is an open-access article distributed under the terms of the Creative Commons Attribution License.