Toll-like receptors are a family of various related proteins that play a major role in the development and defense of plants and animals. These receptors were first discovered in Drosophila melanogaster in the late 20th century which later led to the identification of mammalian homologs. Human TLR family consists of 10 different receptors named TLR1-TLR10. TLRs are necessary for the recognition of microbes, and the subsequent development of host immunity against the pathogen.
However, TLRs have also been implicated in the development of various immune disorders. Overstimulation of innate immune cells and inflammatory factors mediated by TLR has been established to be the main reason for the development of conditions like chronic enterocolitis, atherosclerosis, rheumatoid arthritis and even allograft rejections. Therefore, the development of specific TLR antagonist is an active area of clinical and non-clinical research. Some of the companies in this class include Novimmune and Idera Pharmaceuticals.
On the other hand, activation of TLR mediated signaling pathways has proven to be highly useful in the development of specific immune response against various cancer cells. Consequently, TLR agonists are also being actively researched and developed by many companies like Immune Design and GlaxoSmithKline. Further, the TLR pathway agonists are also being developed as specific cancer vaccines and/or adjuvants for such vaccines.
