ImmunoSensation - the immune sensory system

Immunity. 2012 Nov 6.

Noncanonical autophagy is required for type I interferon secretion in response to DNA-immune complexes.

Henault J, Martinez J, Riggs JM, Tian J, Mehta P, Clarke L, Sasai M, Latz E, Brinkmann MM, Iwasaki A, Coyle AJ, Kolbeck R, Green DR, Sanjuan MA

Toll-like receptor-9 (TLR9) is largely responsible for discriminating self from pathogenic DNA. However, association of host DNA with autoantibodies activates TLR9, inducing the pathogenic secretion of type I interferons (IFNs) from plasmacytoid dendritic cells (pDCs). Here, we found that in response to DNA-containing immune complexes (DNA-IC), but not to soluble ligands, IFN-α production depended upon the convergence of the phagocytic and autophagic pathways, a process called microtubule-associated protein 1A/1B-light chain 3 (LC3)-associated phagocytosis (LAP). LAP was required for TLR9 trafficking into a specialized interferon signaling compartment by a mechanism that involved autophagy-related proteins, but not the conventional autophagic preinitiation complex, or adaptor protein-3 (AP-3). Our findings unveil a new role for nonconventional autophagy in inflammation and provide one mechanism by which anti-DNA autoantibodies, such as those found in several autoimmune disorders, bypass the controls that normally restrict the apportionment of pathogenic DNA and TLR9 to the interferon signaling compartment.

PMID: 23219390