Pattern recognition receptors and G protein-coupled receptors (PRRs and GPCRs)

Pattern recognition receptors (PRRs) and G protein-coupled receptors (GPCRs) represent two distinct but functionally integrated superfamilies of receptors that are fundamental to human physiology and immunology. PRRs, including Toll-like receptors (TLRs) and NOD-like receptors (NLRs), are the primary sensors of the innate immune system, recognizing conserved pathogen-associated molecular patterns (PAMPs) to initiate defensive inflammatory responses (Janeway & Medzhitov, 2002, Annu Rev Immunol). GPCRs are the largest family of cell-surface receptors, characterized by a seven-transmembrane domain structure, and they mediate responses to a vast array of ligands, including hormones, neurotransmitters, and lipids, through the activation of heterotrimeric G proteins (Pierce et al., 2002, Nat Rev Mol Cell Biol). Recent research has identified significant crosstalk between these two systems, where GPCR signaling can modulate PRR-induced pathways, thereby fine-tuning the immune response and maintaining tissue homeostasis (Sun & Ye, 2012, Trends Pharmacol Sci). Dysregulation of either receptor class is linked to numerous diseases, such as chronic inflammation, sepsis, autoimmune disorders, and cancer (O'Neill et al., 2013, Nat Rev Immunol). While GPCRs are the targets of approximately 34% of all FDA-approved drugs, PRRs are increasingly being explored as targets for novel vaccine adjuvants and cancer immunotherapies (Insel et al., 2019, Annu Rev Pharmacol Toxicol). Because this entry combines two expansive and separate receptor families, it is classified as a functional grouping rather than a single therapeutic target.

Other names

PRRGPCRInnate immune sensors7-transmembrane receptorsPattern recognition molecules

PRRs function by recognizing conserved microbial or damage-associated patterns to trigger pro-inflammatory signaling, whereas GPCRs transduce extracellular signals into intracellular responses through heterotrimeric G proteins.