Toll-like receptor 1 (TLR1) participates in the innate immune response to microbial agents. TLR1 cooperates with TLR2 to mediate the innate immune response to bacterial lipoproteins or lipopeptides [, ]. It acts via MYD88 and TRAF6, leading to NF-kappa-B activation, cytokine secretion and the inflammatory response.
Toll-like receptor 6 (TLR6) participates in the innate immune response to Gram-positive bacteria and fungi. TLRs recognize specific molecular patterns present only in micro-organisms. TLR1 and TLR6 are involved in the discrimination of a subtle difference between triacyl and diacyl lipopeptides through interaction with TLR2 []. Cooperatively with TLR2, TLR6 recognises mycoplasmal macrophage-activating lipopeptide-2 (MALP-2), soluble tuberculosis factor (STF), phenol-soluble modulin (PSM) and Borrelia burgdorferi outer surface protein A lipoprotein (OspA-L) []. TLR6 acts via MYD88 and TRAF6, leading to NF-kappa-B activation, cytokine secretion and the inflammatory response [].
Toll-like receptor 2 (TLR2) is a member of the Toll-like receptor (TLR) family, which plays a role in activation of innate immunity and pathogen recognition []. It helps mediate the innate immune response to bacterial lipoproteins and other microbial cell wall components, acting via MyD88 and TRAF6, leading to NF-kappa-B activation, cytokine secretion and the inflammatory response [, , , ]. TLR2 in association with TLR1 or TLR6 is essential for recognising bacterial lipoproteins and lipopeptides [, ]. It also promotes apoptosis in response to lipoproteins [].Genetic variations in TLR2 are associated with susceptibility to leprosy, a chronic disease associated with depressed cellular (but not humoral) immunity [, ].
