This review seeks to examine the current knowledge regarding the regulation of this family of receptors and their signalling pathways as well as how their expression changes in disease states with particular focus on NOD1 and NOD2 in inflammatory bowel diseases among others.
Genetic mutations in the innate immune receptor nucleotide-binding oligomerization domain-containing 2 (Nod2) have demonstrated increased susceptibility to Crohn's disease, an inflammatory bowel disease that is hypothesized to be accompanied by changes in the gut microbiota.
Large consortia contributed to the elucidation of the genetics, for instance, of IBD identifying a number of genes involved in innate mucosal defense and immune tolerance (most prominent, e.g., NOD2) and other related processes.
Polymorphisms of NOD2 (R702W, G908R and L1007fs) and TLR4 (Asp299Gly and Thr399Ile) genes were analyzed in 106 patients with IBD (68 with ulcerative colitis [UC], 38 with Crohn's disease [CD]) and 160 healthy controls using polymerase chain reaction-restriction fragment length polymorphism.
Thus, in a two-hit hypothesis, decreased barrier function due to dysfunctional mitochondrial is amplified by lack of NOD2 in transporting enterocytes: subsequently, greater numbers of bacteria entering the mucosa would be a significant inflammatory threat especially since individuals with NOD2 mutations have compromised macrophage and Paneth cell responses to bacteria.<b>NEW & NOTEWORTHY</b> Increased internalization of bacteria by epithelia with dysfunctional mitochondria (reduced ATP) is potentiated if the cells lack nucleotide-binding oligomerization domain 2 (NOD2), mutations in which are inflammatory bowel disease-susceptibility traits.
In addition, 9 genes previously associated with IBD contained SNPs with significant evidence for replication (P < 1.6 × 10<sup>-6</sup>): ADCY3, CXCR6, HLA-DRB1 to HLA-DQA1 (genome-wide significance on conditioning), IL12B,PTGER4, and TNC for IBD; IL23R, PTGER4, and SNX20 (in strong linkage disequilibrium with NOD2) for CD; and KCNQ2 (near TNFRSF6B) for UC.
The aim of the study was to evaluate associations between inflammatory bowel disease (IBD) presentation and variants in NOD2, TLR4, TNF-α, IL-6, IL-1β, and IL-RN genes in order to identify possible environmental factors that may affect IBD occurrence, investigate potential predictors for surgical treatment of IBD, and correlate the presence of granulomas in biopsy specimens with clinical characteristics of Crohn's disease (CD) patients.
Thus, in a two-hit hypothesis, decreased barrier function due to dysfunctional mitochondrial is amplified by lack of NOD2 in transporting enterocytes: subsequently, greater numbers of bacteria entering the mucosa would be a significant inflammatory threat especially since individuals with NOD2 mutations have compromised macrophage and Paneth cell responses to bacteria.<b>NEW & NOTEWORTHY</b> Increased internalization of bacteria by epithelia with dysfunctional mitochondria (reduced ATP) is potentiated if the cells lack nucleotide-binding oligomerization domain 2 (NOD2), mutations in which are inflammatory bowel disease-susceptibility traits.
Macrophages from controls and ulcerative colitis patients carrying the IBD-risk rs10758669 CC genotype showed increased JAK2 expression and nucleotide-binding oligomerization domain 2-induced JAK2 phosphorylation relative to AA carriers.
VLBW infants carrying ≥ 2 NOD2 genetic risk factors of inflammatory bowel disease in adults have an increased risk for severe gastrointestinal complications, such as NEC requiring surgery.
The present study aims at investigating the interplay between autophagy, NOD2 and AIEC bacteria and assessing the expression level of autophagic proteins in intestinal biopsies of pediatric patients with inflammatory bowel disease (IBD).
The genetic risk score representing all known risk alleles for inflammatory bowel disease showed strong association with disease subphenotype (p=1·65 × 10(-78)), even after exclusion of NOD2, MHC, and 3p21 (p=9·23 × 10(-18)).
Furthermore, to determine whether these NOD2 protein partners could be encoded by IBD susceptibility genes, a transmission disequilibrium test (TDT) was performed on 101 single nucleotide polymorphisms (SNPs) and the main corresponding haplotypes in genes coding for 15 NIPs using a set of 343 IBD families with 556 patients.
This finding might provide us with a novel therapeutic target for inflammatory bowel disease to inhibit IL-23p19 over-expression via the NOD2-c-Rel pathway.
Computational studies demonstrated a correlation between the TRIM22-NOD2 network and signaling pathways and genetic factors associated very early onset and adult-onset IBD.
There is a continuous spectrum of genetic susceptibility from monogenic causative variants with complete Mendelian inheritance, over NOD2 variants with moderate penetrance to minute penetrance in most common susceptibility variants predisposing to conventional polygenic IBD.
This study aimed to evaluate the associations between IBD and variations in NOD2, TLR4, TNF-α, IL-6, IL-1β and IL-1RN genes, and to use the genetic data obtained in predictive modeling.
Some IBD associated genes are involved in innate immunity, in the autophagy and in the inflammatory response such as NOD2, ATG16L1 and IL23R, while other are implicated in immune mediated disease (STAT3) and in susceptibility to mycobacterium infection (IL12B).