title: The Dual NOD1/NOD2 Agonism of Muropeptides Containing a Meso-Diaminopimelic Acid Residue.
abstract: Muropeptides are fragments of peptidoglycan that trigger innate immune responses by activating nucleotide-binding oligomerization domain (NOD) 1 and NOD2. Muropeptides from Gram-negative bacteria contain a meso-diaminopimelic acid (meso-DAP) residue in either a terminal or a non-terminal position. While the former ones are known to be recognized by NOD1, much less is known about recognition of muropeptides with non-terminal meso-DAP, which are most abundant moieties of Gram-negative peptidoglycans. Here, we developed a novel system to assess biological activity of muropeptides, based on CRISPR/Cas9-mediated knockout (KO) of NOD1 and NOD2 genes in modified HEK293T cells. Using NOD1/NOD2 knockout and overexpression systems, as well as human monocytes and macrophages, we refine the current view of muropeptide recognition. We show that NOD2 can recognize different natural muropeptides containing a meso-DAP residue (preferably in a non-terminal position), provided they are present at micromolar concentrations. NOD2 accepts muropeptides with long and branched peptide chains and requires an intact N-acetylmuramyl residue. Muropeptides with non-terminal meso-DAP can activate NOD1 as well, but, in this case, probably require peptidase pre-processing to expose the meso-DAP residue. Depending on NOD1/NOD2 ratio in specific cell types, meso-DAP-containing muropeptides can be recognized either primarily via NOD2 (in monocytes) or via NOD1 (in monocyte-derived macrophages and HEK293T-derived cells). The dual NOD1/NOD2 agonism of meso-DAP-containing muropeptides should be taken into account when assessing cellular responses to muropeptides and designing muropeptide immunostimulants and vaccine adjuvants.
authors: Laboratory of Clinical Immunology, National Research Center "Institute of Immunology of the Federal Medical-Biological Agency", Moscow, Russia.
authors: Yulia A
authors: YA
authors: Dagil
authors: Laboratory of Clinical Immunology, National Research Center "Institute of Immunology of the Federal Medical-Biological Agency", Moscow, Russia.
authors: Nikolai P
authors: NP
authors: Arbatsky
authors: Laboratory of Preparative Biochemistry, National Research Center "Institute of Immunology of the Federal Medical-Biological Agency", Moscow, Russia.
authors: Biana I
authors: BI
authors: Alkhazova
authors: Laboratory of Preparative Biochemistry, National Research Center "Institute of Immunology of the Federal Medical-Biological Agency", Moscow, Russia.
authors: Vyacheslav L
authors: VL
authors: L'vov
authors: Laboratory of Immunochemistry, National Research Center "Institute of Immunology of the Federal Medical-Biological Agency", Moscow, Russia.
authors: Dmitriy V
authors: DV
authors: Mazurov
authors: Laboratory of Clinical Immunology, National Research Center "Institute of Immunology of the Federal Medical-Biological Agency", Moscow, Russia.
authors: Mikhail V
authors: MV
authors: Pashenkov
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D003960:Diaminopimelic Acid / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D007113:Immunity, Innate / Q000187:drug effects*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D053474:Nod1 Signaling Adaptor Protein / Q000819:agonists* / Q000378:metabolism; D053473:Nod2 Signaling Adaptor Protein / Q000819:agonists* / Q000378:metabolism
chemical_list: D000276:Adjuvants, Immunologic; D016207:Cytokines; C119067:NOD1 protein, human; C429018:NOD2 protein, human; D053474:Nod1 Signaling Adaptor Protein; D053473:Nod2 Signaling Adaptor Protein; D003960:Diaminopimelic Acid