Redundant and regulatory roles for Toll-like receptors in Leishmania infection.
Toll-like receptors (TLRs) are germline-encoded, non-clonal innate immune receptors, which are often the first receptors to recognize the molecular patterns on pathogens. Therefore, the immune response initiated by TLRs has far-reaching consequences on the outcome of an infection. As soon as the cell surface TLRs and other receptors recognize a pathogen, the pathogen is phagocytosed. Inclusion of TLRs in the phagosome results in quicker phagosomal maturation and stronger adaptive immune response, as TLRs influence co-stimulatory molecule expression and determinant selection by major histocompatibility complex (MHC) class II and MHC class I for cross-presentation. The signals delivered by the TCR-peptide-MHC complex and co-stimulatory molecules are indispensable for optimal T cell activation. In addition, the cytokines induced by TLRs can skew the differentiation of activated T cells to different effector T cell subsets. However, the potential of TLRs to influence adaptive immune response into different patterns is severely restricted by multiple factors: gross specificity for the molecular patterns, lack of receptor rearrangements, sharing of limited number of adaptors that assemble signalling complexes and redundancy in ligand recognition. These features of apparent redundancy and regulation in the functioning of TLRs characterize them as important and probable contributory factors in the resistance or susceptibility to an infection.
['Chauhan|P|P|', 'Shukla|D|D|0000-0002-6275-5789', 'Chattopadhyay|D|D|', 'Saha|B|B|0000-0003-1873-462X']
D056704:Adaptive Immunity D000818:Animals D045142:Cross-Priming D005786:Gene Expression Regulation D006801:Humans D007113:Immunity, Innate D007891:Leishmania D007896:Leishmaniasis D051379:Mice D000069452:Pathogen-Associated Molecular Pattern Molecules D010587:Phagocytosis D015398:Signal Transduction D013601:T-Lymphocytes D051193:Toll-Like Receptors
Leishmania Toll-like Receptors (TLRs) Macrophage Pathogen associated molecular patterns (PAMP) Phagolysosome