Toll-like Receptor Signaling Pathway

The Toll-like receptor (TLR) signaling pathway is a fundamental component of the innate immune system, responsible for detecting and responding to pathogens such as bacteria, viruses, and fungi. TLRs are pattern recognition receptors (PRRs) that recognize pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), triggering intracellular signaling cascades that result in the production of pro-inflammatory cytokines, chemokines, and type I interferons. Key steps include recognition of PAMPs/DAMPs, activation of TLRs and recruitment of adaptor proteins (MyD88 or TRIF), signal transduction via NF-κB/MAPK/IRF pathways, and effector responses like cytokine/chemokine/interferon production. The pathway is tightly regulated to prevent excessive inflammation, and its dysregulation is implicated in various diseases.