Activation of nucleotide-binding oligomerization domain 2 by muramyl dipeptide negatively regulates Toll-like receptor 9-mediated colonic inflammation through the induction of deubiquitinating enzyme A expression

Abstract

Mutations in nucleotide-binding oligomerization domain 2 (NOD2) are associated with Crohn’s disease (CD). Although NOD2 activation contributes to the maintenance of intestinal homeostasis through the negative regulation of pro-inflammatory cytokine responses mediated by Toll-like receptors (TLRs), the effects of NOD2 activation on interferon (IFN)-α responses induced by TLR9 have been poorly defined. To explore the cross-talk between NOD2 and TLR9, human monocytes or dendritic cells (DCs) were stimulated with NOD2 and/or TLR9 ligands to measure IFN-α production. The severity of dextran sodium sulfate (DSS)-induced colitis was compared in mice treated with NOD2 and/or TLR9 ligands. Expression of IFN-α and IFN-stimulated genes (ISGs) was examined in the colonic mucosa of patients with inflammatory bowel disease (IBD). NOD2 activation reduced TLR9-induced IFN-α production by monocytes and DCs in a deubiquitinating enzyme A (DUBA)-dependent manner. Activation of DUBA induced by the co-stimulation of TLR9 and NOD2 inhibited Lys63-linked polyubiquitination of TRAF3 and suppressed TLR9-mediated IFN-α production. NOD2 activation in hematopoietic cells protected mice from TLR9-induced exacerbation of DSS-induced colitis by down-regulating IFN-α responses and up-regulating DUBA expression. Colonic mucosa of patients with active and remitted IBD phases was characterized by the enhanced and reduced expression of ISGs, respectively. Expression levels of IFN-α and IL-6 positively correlated in the active colonic mucosa of patients with ulcerative colitis and CD, whereas DUBA expression inversely correlated with that of IFN-α in patients with CD. Collectively, these data suggest that DUBA-dependent negative effect of NOD2 on TLR9-mediated IFN-α responses contributes to the maintenance of intestinal homeostasis.

Neutrophil-fibroblast crosstalk drives immunofibrosis in Crohn’s disease through IFNα pathway

“…Several studies have indicated that loss-of-function mutations in nucleotide-binding oligomerization domain 2 (NOD2) have been associated with CD ( 28 ). Of interest, it has been recently indicated, that NOD2 activation in hematopoietic cells protected mice from TLR9-induced exacerbation of DSS-induced colitis by downregulating IFNα responses ( 29 ). Although several immune and non-immune cells may contribute, the exact sources of IFNα in the systemic circulation of CD remain to be identified.…”

“…Linking our findings with clinical practice, we found that levels of IFNα in serum or/and mRNA expression of selective IFN-signaling-related components in peripheral neutrophils could be surrogate markers of CD activity, positively correlated with the CDAI, a well-established disease severity index which includes endoscopic findings. Recently, colonic tissue biopsies of CD or UC patients with active and remitted disease phases were characterized by the enhanced and reduced expression of IFN-stimulated genes, respectively ( 29 ). Here, we suggest that targeted analysis of peripheral blood neutrophils may be a more specific, easier, and less costly diagnostic approach.…”

Cytokine and chemokine profiles in ulcerative colitis relapse after coronavirus disease 2019 vaccination

“…Colonic biopsy samples were obtained during endoscopy and subjected to qPCR as previously described. ( 24 , 34 , 35 ) qPCR analyses were performed using Quantitect primer assays (Qiagen, Valencia, CA). Primers for the target genes were purchased from Qiagen, and SYBR Green-based qPCR was performed using a LightCycler 480 system (Roche, Tokyo, Japan).…”

Ulcerative Colitis-associated Spondyloarthritis Successfully Treated with Infliximab in the Absence of Enhanced TNF-α Responses

“…A total of 200 μL of serum samples were applied to the membrane. Colonic biopsy samples obtained during endoscopy were subjected to quantitative polymerase chain reaction (qPCR) in accordance with our previous report (19)(20)(21)(22). mRNA was isolated from nontumor portions of colonic mucosa from three patients with colon adenoma to determine the mRNA expression in the healthy colonic mucosa.…”