Sialoside-based pattern recognitions discriminating infections from tissue injuries

Abstract

Recognition of pathogens-associated molecular patterns (PAMPs) by Toll-like receptors (TLRs), NOD-like receptors (NLRs) and RIG-I-like receptors (RLR) plays a critical role in protecting host against pathogens. In addition, TLR and NLR also recognize danger-associated molecular patterns (DAMPs) to initiate limited innate immune responses. While innate immune response to DAMPs may be important for tissue repairs and wound healing, it is normally well controlled to avoid autoimmune destruction. Recent data support a role for sialoside-based pattern recognition by members of the Siglec family to attenuate innate immunity. In particular, since CD24-Siglec 10/G interaction selectively dampens host response to DAMPs but not PAMPs, this sialoside-based pattern recognition may serve as a foundation to discriminate PAMPs from DAMPs.

Fig. 1

Sialoside-based pattern recognition discriminates infections from aseptic tissue injuries by two possible mechanisms. First, CD24 forms trimolecular complex with DAMPs and Siglec G that inhibits activation of TLR/NLR. Second, pathogen-encoded sialidases prevent CD24 from interacting with Siglec G. As a result, DAMPs and PAMPs become indistinguishable during infection.