Pattern-recognition receptors and Protease-activated receptors (PRRs/PARs)

Pattern-recognition receptors (PRRs), such as Toll-like receptors (TLRs) and C-type lectin receptors (CLRs), are essential components of the innate immune system that identify conserved molecular motifs on pathogens or damaged host cells [Takeuchi & Akira, 2010, Cell]. Protease-activated receptors (PARs) are a unique class of G protein-coupled receptors that are activated by proteolytic cleavage and often work in tandem with PRRs to coordinate inflammatory and vascular responses [Shpacovitch et al., 2007, Trends Immunol]. TLR2 and TLR4 are among the most studied PRRs, recognizing bacterial lipopeptides and lipopolysaccharides, respectively, to trigger pro-inflammatory signaling pathways like NF-κB [Kawai & Akira, 2010, Nat Immunol]. PARs, particularly PAR1 and PAR2, play significant roles in thrombosis and tissue repair, making them key targets for cardiovascular and inflammatory therapies [Morrow et al., 2012, N Engl J Med]. Dysregulation of these receptor systems is implicated in a wide range of pathologies, including sepsis, autoimmune disorders, and atherosclerosis [Janeway & Medzhitov, 2002, Annu Rev Immunol]. Consequently, pharmacological modulation of these receptors—ranging from TLR agonists used as vaccine adjuvants to PAR antagonists used as anti-platelet agents—represents a diverse and critical area of drug development [Steinhagen et al., 2011, Expert Rev Vaccines].

Other names

Innate immune receptorsPathogen sensorsDanger-associated molecular pattern receptorsPAMP/DAMP receptorsToll-like receptorsC-type lectin receptorsProtease-activated receptors

Antagonism of PAR1 to inhibit protease-induced platelet aggregation; Agonism of TLR4 to enhance vaccine immunogenicity; Antagonism of TLR4 or TLR2 to reduce systemic inflammatory signaling; Antagonism of PAR2 to treat inflammatory pain and fibrosis.