Canonical and noncanonical autophagy in immunity.

Canonical and noncanonical autophagic processes are integrated with innate and adaptive immunity and sterile or pathogen-induced inflammation. In canonical autophagy, double-membrane autophagosomes modified by ubiquitin-like ATG8 proteins in a process termed membrane atg8ylation sequester and eliminate intracellular targets such as invading microbes, defunct organelles, aggregates, and inflammatory molecules. Recently, a plethora of noncanonical processes that entail membrane atg8ylation of various intracellular organelles other than autophagosomes have been linked to immunity. This has led to confounding interpretations and conflation of diverse processes as autophagy. Here, we posit that these are divergent manifestations of a common ancestral homeostatic process of membrane atg8ylation and provide an overview of how they affect immunity and inflammation. These relationships are evident in model organisms and are reflected in human genetic predispositions to diseases with immune components. The membrane atg8ylation pathways affect acute and chronic inflammation, infections, autoimmunity, cancer, neurodegeneration, metabolic syndrome, diabetes, and other disorders.