HEK-Blue™ TLR8 cells are designed to study the stimulation of the Toll-Like Receptor 8 (TLR8) by monitoring the activation of NF-κB and AP-1.
These cells express the human or murine TLR8 gene. In addition, they feature an NF-κB/AP-1-inducible SEAP reporter gene. SEAP (secreted embryonic alkaline phosphatase) levels produced upon TLR8 stimulation can be readily determined by performing the assay in HEK-Blue™ Detection, a cell culture medium that allows for real-time detection of SEAP. Alternatively, SEAP activity may be monitored using QUANTI-Blue™ solution, a SEAP detection reagent.
TLR8 is a pattern recognition receptor (PRR) mainly located in the endosome. Together with TLR7, it and recognizes single-stranded (ss)RNA structures and small synthetic molecules, such as R848, an imidazoquinolone with antiviral activity [2-3].
R848 induces the activation of NF-κB in HEK293 cells transfected with human TLR8 but not in HEK293 cells expressing murine TLR8, suggesting a species specificity .
TLR8 agonists are currently been tested as vaccine adjuvants and immunomodulatory therapeutics .
1. Chuang TH. and RJ. Ulevitch, 2000. Cloning and characterization of a sub-family of human toll-like receptors: hTLR7, hTLR8 and hTLR9. Eur Cytokine Netw, 11(3):372-8.
2. Jurk M. et al., 2002. Human TLR7 or TLR8 independently confer responsiveness to the antiviral compound R-848. Nat Immunol, 3(6):499.
3. Heil F. et al., 2004. Species-specific recognition of single-stranded RNA via toll-like receptor 7 and 8. Science. 303(5663):1526-9.
4. Georg P. & Sander L.E., 2019. Innate sensors that regulate vaccine responses. Curr. Op. Immunol. 59:31.