The TLRs belong to a cluster of molecules called the IL-1R/TLR super-family characterized by the presence of cytoplasmic Toll/IL-1R (TIR) domains (10) . The three subgroups are: the IL-1R (which present extracellular immunoglobulin domains), the adapter subgroup (cytoplasmic proteins without extracellular region) and the TLRs (9) . TLRs are type I transmembrane proteins with extracellular amino terminus and a carboxy terminal intracellular domain. The extracellular domain of the TLR4 contains over 600 amino acids and is highly polymorphic compared with the transmembrane and cytosolic domains (6) . The TIR domain, composed of three highly conserved regions, contains 150 amino acids and modulates protein-protein interactions between the TLRs and the adaptor proteins involved in the signal transduction cascade (10) . Unlike other receptors, TLRs do not have an enzymatic activity (6) . Researchers have identified at least fifteen different negative regulators of the TLRs, including MyD88s (a short form of MyD88), IRAKM, suppressor of cell signaling-1 (SOCS1), nucleotidebinding oligomerization domain 2 (NOD2), phosphatidylinositol-3-kinase (PI3K) and Toll-interacting protein (TOLLIP) (11) . The TLR activation leads to responses that involve the induction of new genes via transduction pathways such as NFκB and AP-1 (9) . The discovery of TLR lead to the understanding that an adaptive response mediated by antibody responses and T cell activation is tightly coupled to a second unknown process that requires the presence of microbial extracts (2, 7) .