TLR

TLR, or Toll-like Receptor, refers to a class of proteins that play a central role in the innate immune system. These receptors are pattern recognition receptors (PRRs) that detect conserved molecular patterns associated with pathogens, known as pathogen-associated molecular patterns (PAMPs), as well as danger-associated molecular patterns (DAMPs) released from damaged cells.

TLRs are expressed primarily on immune cells such as macrophages, dendritic cells, and B cells. Their activation initiates signaling pathways that lead to the production of cytokines, chemokines, and other mediators, thereby orchestrating an immediate immune response and shaping subsequent adaptive immunity. The signaling cascade involves various adaptor proteins like MyD88 and TRIF, which influence gene expression related to inflammation and immune regulation.

There are at least ten identified human TLRs (TLR1-TLR10), each recognizing specific PAMPs. For example, TLR4 detects lipopolysaccharides from Gram-negative bacteria, while TLR3 recognizes double-stranded RNA from viruses. The structural diversity among TLRs allows the immune system to recognize a wide array of microbial components.

Research into TLRs has significant implications for understanding infectious diseases, autoimmune disorders, and developing vaccine adjuvants. Abnormal TLR signaling can contribute to chronic inflammation and autoimmunity, while targeted modulation of TLR pathways holds therapeutic potential.

TLRs are conserved across species, indicating their fundamental evolutionary role in immune defense. Their study continues to be a critical area in immunology, with ongoing efforts to harness their functions for therapeutic and preventive strategies.