Nod1-mediated innate immune recognition of peptidoglycan contributes to the onset of adaptive immunity.

Recent evidence has suggested that signals other than those from Toll-like receptors (TLRs) could contribute to the elicitation of antigen-specific immunity. Therefore, we examined the role of the Nod-like receptor (NLR) family member, Nod1, in the generation of adaptive immune responses. Our findings show that innate immune sensing of peptidoglycan by Nod1 is key for priming antigen-specific T cell immunity and subsequent antibody responses in vivo. Nod1 stimulation alone was sufficient to drive antigen-specific immunity with a predominant Th2 polarization profile. In conjunction with TLR stimulation, however, Nod1 triggering was required to instruct the onset of Th1 and Th2 as well as Th17 immune pathways. Cells outside of the hematopoietic lineage provided the early signals necessary to orchestrate the development of Nod1-dependent immune responses. These findings highlight Nod1 as a key innate immune trigger in the local tissue microenvironment that drives the development of adaptive immunity.