DEFB114 protein enhances host resistance to fungal infection through the NOD1/2-ATG16L1-NF-κB signaling pathway.

The overuse of antibiotics has led to the enhanced resistance of many pathogenic bacteria, posing a threat to human health. Therefore, there is a need to develop green and safe alternatives to antibiotics. Beta-defensins play a crucial role in host defense against pathogens and have multifunctional properties, exerting key roles in innate and adaptive immunity, as well as non-immune processes. In this study, a 210 bp long cDNA sequence of yak DEFB114 gene was amplified and successfully expressed in a prokaryotic system. The DEFB114 protein exhibited significant inhibitory effects on the growth of Aspergillus fumigatus in vitro. When co-cultured with yak macrophages, DEFB114 protein enhanced macrophage phagocytic activity and increased nucleic acid fluorescence intensity (P < 0.05). DEFB114 protein also enhanced the activity of yak macrophages stimulated by inactivated Aspergillus fumigatus spores, increased the release of nitric oxide (NO), and promoted the expression of genes such as γ-actin, Lgals, Man2b, and Capg (P < 0.05). In mice experiments, DEFB114 protein promoted resistance against Aspergillus fumigatus infection, by regulating the NOD1/2-ATG16L1-NF-κB pathway to modulate the host immune response and exert its anti-infective effects. In summary, the yak DEFB114 protein could inhibit the growth of Aspergillus fumigatus and enhance the animal's resistance to pathogenic microorganisms, thereby having significant implications in the treatment and prevention of fungal infections.

NOD1 deficiency ameliorates the progression of diabetic retinopathy by modulating bone marrow-retina crosstalk.

BACKGROUND: Nucleotide-binding oligomerization domain-containing protein 1 (NOD1) plays a pivotal role in inducing metabolic inflammation in diabetes. Additionally, the NOD1 ligand disrupts the equilibrium of bone marrow-derived hematopoietic stem/progenitor cells, a process that has immense significance in the development of diabetic retinopathy (DR). We hypothesized that NOD1 depletion impedes the advancement of DR by resolving bone marrow dysfunction. METHODS: We generated NOD1-/--Akita double-mutant mice and chimeric mice with hematopoietic-specific NOD1 depletion to study the role of NOD1 in the bone marrow-retina axis. RESULTS: Elevated circulating NOD1 activators were observed in Akita mice after 6 months of diabetes. NOD1 depletion partially restored diabetes-induced structural changes and retinal electrical responses in NOD1-/--Akita mice. Loss of NOD1 significantly ameliorated the progression of diabetic retinal vascular degeneration, as determined by acellular capillary quantification. The preventive effect of NOD1 depletion on DR is linked to bone marrow phenotype alterations, including a restored HSC pool and a shift in hematopoiesis toward myelopoiesis. We also generated chimeric mice with hematopoietic-specific NOD1 ablation, and the results further indicated that NOD1 had a protective effect against DR. Mechanistically, loss of hematopoietic NOD1 resulted in reduced bone marrow-derived macrophage infiltration and decreased CXCL1 and CXCL2 secretion within the retina, subsequently leading to diminished neutrophil chemoattraction and NETosis. CONCLUSIONS: The results of our study unveil, for the first time, the critical role of NOD1 as a trigger for a hematopoietic imbalance toward myelopoiesis and local retinal inflammation, culminating in DR progression. Targeting NOD1 in bone marrow may be a potential strategy for the prevention and treatment of DR.

Synthesis and validation of click-modified NOD1/2 agonists.

NOD1 and NOD2 sense small bacterial peptidoglycan fragments, often called muropeptides, that access the cytosol. These muropeptides include iE-DAP and MDP, the minimal agonists for NOD1 and NOD2, respectively. Here, we synthesized and validated alkyne-modified muropeptides, iE-DAP-Alk and MDP-Alk, for use in click-chemistry reactions. While it has long been known that many cell types respond to extracellular exposure to muropeptides, it is unclear how these innate immune activators access their cytosolic innate immune receptors, NOD1 and NOD2. The subcellular trafficking and transport mechanisms by which muropeptides access these cytosolic innate immune receptors are a major gap in our understanding of these critical host responses. The click-chemistry-enabled agonists developed here will be particularly powerful to decipher the underlying cell biology and biochemistry of NOD1 and NOD2 innate immune sensing.

Fusobacterium nucleatum-triggered neutrophil extracellular traps facilitate colorectal carcinoma progression.

BACKGROUND: Fusobacterium nucleatum (Fn) acts as a procarcinogenic bacterium in colorectal carcinoma (CRC) by regulating the inflammatory tumor microenvironment (TME). Neutrophil extracellular traps (NETs), which can be generated by persistent inflammation, have been recently considered to be significant contributors in promoting cancer progression. However, whether NETs are implicated in Fn-related carcinogenesis is still poorly characterized. Here, we explored the role of NETs in Fn-related CRC as well as their potential clinical significance. METHODS: Fn was measured in tissue specimens and feces samples from CRC patients. The expression of NET markers were also detected in tissue specimens, freshly isolated neutrophils and blood serum from CRC patients, and the correlation of circulating NETs levels with Fn was evaluated. Cell-based experiments were conducted to investigate the mechanism by which Fn modulates NETs formation. In addition, we clarified the functional mechanism of Fn-induced NETs on the growth and metastasis of CRC in vitro and in vivo experiments. RESULTS: Tissue and blood samples from CRC patients, particularly those from Fn-infected CRC patients, exhibited greater neutrophil infiltration and higher NETs levels. Fn infection induced abundant NETs production in in vitro studies. Subsequently, we demonstrated that Fn-induced NETs indirectly accelerated malignant tumor growth through angiopoiesis, and facilitated tumor metastasis, as manifested by epithelial-mesenchymal transition (EMT)-related cell migration, matrix metalloproteinase (MMP)-mediated basement membrane protein degradation, and trapping of CRC cells. Mechanistically, the Toll-like receptor (TLR4)-reactive oxygen species (ROS) signaling pathway and NOD-like receptor (NOD1/2)-dependent signaling were responsible for Fn-stimulated NETs formation. More importantly, circulating NETs combined with carcinoembryonic antigen (CEA) could predict CRC occurrence and metastasis, with areas under the ROC curves (AUCs) of 0.92 and 0.85, respectively. CONCLUSIONS: Our findings indicated that Fn-induced NETs abundance by activating TLR4-ROS and NOD1/2 signalings in neutrophils facilitated CRC progression. The combination of circulating NETs and CEA was identified as a novel screening strategy for predicting CRC occurrence and metastasis.

An innate immune sensor wandering around - NOD1 promotes cell migration via non-canonical signaling.

NOD1 is a cytosolic immune receptor well known for recognizing intracellular bacteria and inducing innate immune responses. Upon ligand binding, it usually forms a complex with the serine/threonine kinase RIPK2 to activate the transcription factor NF-κB. Next to its role in pathogen recognition, NOD1 has been associated with cancer progression. In this regard, Hezinger et al. investigated a non-canonical role of NOD1 in cell migration. They discovered that NOD1 is crucial for the migration and chemotaxis of HeLa cells and identified HAX-1 as a novel interaction partner.

NOD1 cooperates with HAX-1 to promote cell migration in a RIPK2- and NF-ĸB-independent manner.

The human Nod-like receptor protein NOD1 is a well-described pattern-recognition receptor (PRR) with diverse functions. NOD1 associates with F-actin and its protein levels are upregulated in metastatic cancer cells. A hallmark of cancer cells is their ability to migrate, which involves actin remodelling. Using chemotaxis and wound healing assays, we show that NOD1 expression correlated with the migration rate and chemotactic index in the cervical carcinoma cell line HeLa. The effect of NOD1 in cell migration was independent of the downstream kinase RIPK2 and NF-ĸB activity. Additionally, NOD1 negatively regulated the phosphorylation status of cofilin, which inhibits actin turnover. Co-immunoprecipitation assays identified HCLS1-associated protein X-1 (HAX-1) as a previously unknown interaction partner of NOD1. Silencing of HAX-1 expression reduced the migration behaviour to similar levels as NOD1 knockdown, and simultaneous knockdown of NOD1 and HAX-1 showed no additive effect, suggesting that both proteins act in the same pathway. In conclusion, our data revealed an important role of the PRR NOD1 in regulating cell migration as well as chemotaxis in human cervical cancer cells and identified HAX-1 as a protein that interacts with NOD1 and is involved in this signalling pathway.

NOD1 mediates interleukin-18 processing in epithelial cells responding to Helicobacter pylori infection in mice.

The interleukin-1 family members, IL-1ß and IL-18, are processed into their biologically active forms by multi-protein complexes, known as inflammasomes. Although the inflammasome pathways that mediate IL-1ß processing in myeloid cells have been defined, those involved in IL-18 processing, particularly in non-myeloid cells, are still not well understood. Here we report that the host defence molecule NOD1 regulates IL-18 processing in mouse epithelial cells in response to the mucosal pathogen, Helicobacter pylori. Specifically, NOD1 in epithelial cells mediates IL-18 processing and maturation via interactions with caspase-1, instead of the canonical inflammasome pathway involving RIPK2, NF-κB, NLRP3 and ASC. NOD1 activation and IL-18 then help maintain epithelial homoeostasis to mediate protection against pre-neoplastic changes induced by gastric H. pylori infection in vivo. Our findings thus demonstrate a function for NOD1 in epithelial cell production of bioactive IL-18 and protection against H. pylori-induced pathology.

When SLC46A2 delivers cargo into keratinocytes.

How pattern recognition receptors NOD1 and NOD2 sense bacterial muropeptides from extracellular bacteria to drive keratinocyte inflammation remains unclear. In this issue of Immunity, Bharadwaj et al. show that the solute carrier 46A2 (SLC46A2) delivers DAP-muropeptides into the cytosol to drive NOD1 activation in keratinocytes and elicit skin inflammation during psoriasis.

NOD1 mediated D. pteronyssinus-induced allergic airway inflammation through RIP2/NF-κB.

BACKGROUND: Dermatophagoides pteronyssinus (D. pteronyssinus) is the main cause of allergic airway inflammation. As the earliest intracytoplasmic pathogen recognition receptors (PRR), NOD1 has been identified as key inflammatory mediator in NOD-like receptor (NLR) family. OBJECTIVE: Our primary aim is to elucidate whether NOD1 and its downstream regulatory proteins mediate D. pteronyssinus-induced allergic airway inflammation. METHODS: Mouse and cell models of D. pteronyssinus-induced allergic airway inflammation were established. NOD1 was inhibited in bronchial epithelium cells (BEAS-2B cells) and mice by cell transfection or application of inhibitor. The change of downstream regulatory proteins was detected by quantitative real-time PCR (qRT-PCR) and Western blot. The relative expression of inflammatory cytokines was evaluated by ELISA. RESULTS: The expression level of NOD1 and its downstream regulatory proteins increased in BEAS-2B cells and mice after treating with D. pteronyssinus extract, followed by the aggravation of inflammatory response. Moreover, inhibition of NOD1 decreased the inflammatory response, which also downregulated the expression of downstream regulatory proteins and inflammatory cytokines. CONCLUSIONS: NOD1 involves in the development of D. pteronyssinus-induced allergic airway inflammation. Inhibition of NOD1 reduces D. pteronyssinus-induced airway inflammation.

Methotrexate suppresses psoriatic skin inflammation by inhibiting muropeptide transporter SLC46A2 activity.

Cytosolic innate immune sensing is critical for protecting barrier tissues. NOD1 and NOD2 are cytosolic sensors of small peptidoglycan fragments (muropeptides) derived from the bacterial cell wall. These muropeptides enter cells, especially epithelial cells, through unclear mechanisms. We previously implicated SLC46 transporters in muropeptide transport in Drosophila immunity. Here, we focused on Slc46a2, which was highly expressed in mammalian epidermal keratinocytes, and showed that it was critical for the delivery of diaminopimelic acid (DAP)-muropeptides and activation of NOD1 in keratinocytes, whereas the related transporter Slc46a3 was critical for delivering the NOD2 ligand MDP to keratinocytes. In a mouse model, Slc46a2 and Nod1 deficiency strongly suppressed psoriatic inflammation, whereas methotrexate, a commonly used psoriasis therapeutic, inhibited Slc46a2-dependent transport of DAP-muropeptides. Collectively, these studies define SLC46A2 as a transporter of NOD1-activating muropeptides, with critical roles in the skin barrier, and identify this transporter as an important target for anti-inflammatory intervention.

Eugenol modulates the NOD1-NF-κB signaling pathway via targeting NF-κB protein in triple-negative breast cancer cells.

Background: The most aggressive subtype of breast cancer, triple-negative breast cancer (TNBC), has a worse prognosis and a higher probability of relapse since there is a narrow range of treatment options. Identifying and testing potential therapeutic targets for the treatment of TNBC is of high priority. Methods: Using a transcriptional signature of triple-negative breast cancer collected from Gene Expression Omnibus (GEO), CMap was utilized to reposition compounds for the treatment of TNBC. CCK8 and colony formation experiments were performed to detect the effect of the candidate drug on the proliferation of TNBC cells. Meanwhile, transwell and wound healing assay were implemented to detect cell metastasis change caused by the candidate drug. Moreover, the proteomic approach was presently ongoing to evaluate the underlying mechanism of the candidate drug in TNBC. Furthermore, drug affinity responsive target stability (DARTS) coupled with LC-MS/MS was carried out to explore the potential drug target candidate in TNBC cells. Results: We found that the most widely used medication, eugenol, reduced the growth and metastasis of TNBC cells. According to the underlying mechanism revealed by proteomics, eugenol could inhibit TNBC cell proliferation and metastasis via the NOD1-NF-κB signaling pathway. DARTS experiment further revealed that eugenol may bind to NF-κB in TNBC cells. Concludes: Our findings pointed out that eugenol was a potential candidate drug for the treatment of TNBC.

NOD1 activation in 3T3-L1 adipocytes confers lipid accumulation in HepG2 cells.

AIMS: Activation of specific innate immune receptors has been characterized to modulate nutrient metabolism in individual metabolic tissue directly or indirectly via secretory molecules. Activation of the nucleotide-binding oligomerization domain-containing protein 1 (NOD1) in adipocytes has been reported to induce lipolysis linked with insulin resistance and inflammatory response. These cues are positioned to modulate metabolic action in distal organs through paracrine/endocrine signaling. Here, we assessed the role of NOD1-mediated lipolysis and inflammatory response in adipocytes to affect lipid metabolism in hepatocytes. MAIN METHODS: Human hepatoma cells (HepG2) were exposed to conditioned medium obtained from 3 T3-L1 adipocytes pretreated with NOD1 ligand (iE-DAP) and the effects on lipid accumulation, inflammation and insulin response were assessed. Activation of mechanisms leading to hepatic lipid accumulation was investigated by gene expression analysis. KEY FINDINGS: The conditioned medium from NOD1-activated 3 T3-L1 adipocytes (CM-DAP) induced lipid accumulation in HepG2 cells, driven by both lipolysis and inflammatory responses. The CM-DAP-induced lipid accumulation was independent to de novo lipogenesis and resulted from the enhanced transport of fatty acids inside and consequent increase in rate of triglycerides synthesis in hepatocytes. Moreover, CM-DAP-induced lipid accumulation instigated the expression of the markers of fatty acid oxidation and VLDL assembly for the export of triglycerides from hepatocyte. Furthermore, CM-DAP-induced lipid accumulation was associated with induction of inflammatory response and impairment of insulin signaling in HepG2 cells. SIGNIFICANCE: Beyond showing liver-specific mechanisms to adipocytes-derived factors, our findings support the involvement of adipose tissue as a mediator in NOD1-mediated biological responses to modulate hepatic metabolism.

NOD1 and NOD2 Are Potential Therapeutic Targets for Cancer Immunotherapy.

The nucleotide oligomerization domain (NOD)-like receptors (NLRs) are a group of intracellular proteins that are essential for controlling the host's innate immune response. The cytosolic nucleotide binding oligomerization domains 1 and 2 receptors (NOD1 and NOD2) are the most widely investigated NLRs. As pattern recognition receptors (PRRs), NOD1 and NOD2 may recognize and bind endogenous damage associated molecular patterns (DAMPs) and external pathogenic associated molecular patterns (PAMPs), directing the activation of inflammatory caspases through engaging the adaptor protein RIP2, which further activates the NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways, thereby mediating host innate immunity and regulating the adaptive immunity. Previous research has identified NOD1 and NOD2 as key players in inflammatory disease and host-microbial defense. Despite numerous studies claiming that NOD1 and NOD2 are linked to tumorigenesis and tumor development, it is still unclear whether NOD1 and NOD2 act as cancer's friends or foes. In this review, we focus on concluding the current research progress on the role of NOD1 and NOD2 in a variety of cancers and discussing the potential reasons for the contradicting role of NOD1 and NOD2 in cancers. This review may help better understand the role of NOD1 and NOD2 in cancer and shed light on NOD1 and NOD2 as potential therapeutic targets for tumor immunotherapy.

Extracellular vesicles from colorectal cancer cells promote metastasis via the NOD1 signalling pathway.

Pattern-recognition receptors (PRRs) have been shown to promote tumour metastasis via sensing tumour cell-derived small extracellular vesicles (EVs). Nucleotide-binding oligomerisation domain 1 (NOD1), a cytoplasmic PRR, plays a role in colorectal cancer (CRC) by detecting bacterial products. However, the precise mechanisms underlying the effects of NOD1, following identification of CRC cell-derived EVs (CRC-EVs), to potentiate CRC liver metastasis (CRC-LM), remain poorly understood. Here, we demonstrate that CRC-EVs activate NOD1 in macrophages to initiate secretion of inflammatory cytokines and chemokines. NOD1-activated macrophages also promote CRC cell migration, while in a murine model of liver metastasis (LM), NOD1-deficient mice exhibit reduced metastasis following CRC-EV treatment. Furthermore, cell division cycle 42 (CDC42), a small Rho guanosine-5'-triphosphate (GTP)ase, is delivered by CRC-EVs into macrophages where it activates NOD1. In addition, EVs from the plasma of patients with CRC-LM mediate NOD1 activation in human peripheral blood mononuclear cells. Moreover, high NOD1 expression in tumour tissues is associated with poor prognosis of CRC-LM. Our findings suggest that CRC-EVs activate NOD1 to promote tumour metastasis, thus, NOD1 may serve as a potential target in the diagnosis and treatment of CRC-LM.

Activation of the pattern recognition receptor NOD1 in periodontitis impairs the osteogenic capacity of human periodontal ligament stem cells via p38/MAPK signalling.

OBJECTIVES: Nucleotide oligomerization domain receptor 1 (NOD1) mediates host recognition of pathogenic bacteria in periodontium. However, the specific role of NOD1 in regulating osteogenesis is unclear. Therefore, this study focused on the activation status of NOD1 in periodontitis and its effect on the osteogenic capacity of human periodontal ligament stem cells (hPDLSCs) as well as the underlying mechanism. METHODS: Histological staining and Western blot were utilized to assess NOD1 expression in the periodontium of people with or without periodontitis. HPDLSCs were cultured under NOD1 agonist or antagonist treatment. Q-PCR and Western blot were employed to assess the expression of osteogenic marker genes and proteins. Alizarin red staining and alkaline phosphatase staining were used to determine the osteogenic capability of hPDLSCs. The activation of downstream signalling was determined and specific inhibitors were utilized to confirm the signalling pathway in NOD1-regulated osteogenesis. RESULTS: NOD1 expression is significantly elevated in periodontitis. With NOD1 activated by particular agonist tri-DAP, the osteogenic potential of hPDLSCs was impaired. NOD1 antagonist co-incubation partially restored the decreased osteogenesis in hPDLSCs. P38/MAPK was phosphorylated in tri-DAP-induced NOD1 activation. The inhibitor of p38 rescued the suppression of osteogenesis induced by tri-DAP in hPDLSCs. CONCLUSIONS: Our study revealed the expression status of NOD1 in periodontitis. Its activation greatly decreased the osteogenic capacity of hPDLSCs which was mediated by the phosphorylation of p38 downstream signalling.

Gut Microbiota-Derived Diaminopimelic Acid Promotes the NOD1/RIP2 Signaling Pathway and Plays a Key Role in the Progression of Severe Acute Pancreatitis.

Impaired intestinal barrier function and gut microbiota dysbiosis are believed to be related to exacerbation of acute pancreatitis (AP). As a bacterial cell wall peptidoglycan component, diaminopimelic acid (DAP) is a specific ligand of NOD1 that regulates the NOD1/RIP2/NF-kB signaling pathway. Here, we investigated the role of DAP in the crosstalk between the gut microbiota and pancreas during the occurrence of AP. Upregulation of NOD1/RIP2/NF-kB and elevated serum DAP levels were found in severe AP (SAP) model rats. The accumulation of DAP in SAP patients corroborated its ability to serve as an indicator of disease severity. Subsequently, SAP rats were treated with oral administration of the traditional Chinese medicine Qingyi Keli (QYKL) as well as neomycin, which can widely eliminate DAP-containing bacteria. Both QYKL and neomycin intervention ameliorated intestinal and pancreatic damage and systemic inflammation in SAP rats. Through 16S rDNA sequencing, we found that QYKL could rehabilitate the gut microbiota structure and selectively inhibit the overgrowth of enteric bacteria, such as Helicobacter and Lactobacillus, in SAP rats without affecting some protective strains, including Romboutsia and Allobaculum. Interestingly, we demonstrated that the decrease in serum DAP was accompanied by suppression of the NOD1/RIP2/NF-kB signaling pathway in both the intestine and pancreas of the two intervention groups. Taken together, these results suggested that the gut microbiota-DAP-NOD1/RIP2 signaling pathway might play a critical role in the progression of AP and that SAP could be alleviated via intervention in the signaling pathway. Our work provides new potential early warning indicators of SAP and targets for intervention.

Nucleotide-Binding Oligomerization Domain 1 (NOD1) Positively Regulates Neuroinflammation during Japanese Encephalitis Virus Infection.

Japanese encephalitis virus (JEV) is a neurotropic flavivirus that invades the central nervous system and causes neuroinflammation and extensive neuronal cell death. Nucleotide-binding oligomerization domain 1 (NOD1) is a type of pattern recognition receptor that plays a regulatory role in both bacterial and nonbacterial infections. However, the role of NOD1 in JEV-induced neuroinflammation remains undisclosed. In this study, we evaluated the effect of NOD1 activation on the progression of JEV-induced neuroinflammation using a human astrocytic cell line and NOD1 knockout mice. The results showed that JEV infection upregulated the mRNA and protein expression of NOD1, ultimately leading to an enhanced neuroinflammatory response in vivo and in vitro. Inhibition of NOD1 in cultured cells or mice significantly abrogated the inflammatory response triggered by JEV infection. Moreover, compared to the wild-type mice, the NOD1 knockout mice showed resistance to JEV infection. Mechanistically, the NOD1-mediated neuroinflammatory response was found to be associated with increased expression or activation/phosphorylation of downstream receptor-interacting protein 2 (RIPK2), mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK), Jun N-terminal protein kinase (JNK), and NF-κB signaling molecules. Thus, NOD1 targeting could be a therapeutic approach to treat Japanese encephalitis. IMPORTANCE Neuroinflammation is the main pathological manifestation of Japanese encephalitis (JE) and the most important factor leading to morbidity and death in humans and animals infected by JEV. An in-depth understanding of the basic mechanisms of neuroinflammation will contribute to research on JE treatment. This study proved that JEV infection can activate the NOD1-RIPK2 signal cascade to induce neuroinflammation through the proven downstream MAPK, ERK, JNK, and NF-κB signal pathway. Thus, our study unveiled NOD1 as a potential target for therapeutic intervention for JE.

NOD1 activation promotes cell apoptosis in papillary thyroid cancer.

BACKGROUND: NOD1 can promote or inhibit different types of cancers, suggesting that NOD1 functions in the progression of cancers dependent on the tumour environment. However, the expression and mechanisms of NOD1 during papillary thyroid carcinoma (PTC) progression remain unclear. METHODS: To investigate the role of NOD1 in PTC development and apoptosis, we detected NOD1 expression in three cell lines and surgical specimens from patients with PTC using immunohistochemistry, quantitative real-time PCR (Q-PCR) and Western blotting; we studied the biological functions of NOD1 by loss-of-function analysis of TPC-1 and BCPAP cells and the effect of NOD1 on the progression of PTC in terms of cell proliferation and apoptosis induced by tumour necrosis factor alpha (TNF-α), Fas ligand (Fas L), tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) or Ala-γGlu-diaminopimelic acid (TriDAP) in the presence of cycloheximide (CHX) and determined its underlying molecular mechanism using PTC cell lines in vitro and mouse xenograft models in vivo. RESULTS: Increased expression of NOD1 is correlated with an improved prognosis in thyroid cancer patients. We also found that NOD1 expression was markedly upregulated in PTC cells compared to normal epithelial cells. NOD1 knockdown significantly promoted the proliferation of PTC cells in vitro, while activation of NOD1 signalling promoted PTC cell apoptosis; NOD1-induced apoptosis depends on the activation of caspase-3 and caspase-9 although the RIP2/TAK1 and MAPK pathways in PTC cells. CONCLUSIONS: This study demonstrates that NOD1 is a predictive biomarker for PTC and that PTC cell apoptosis is induced by activation of NOD1 via the RIP2/TAK1 and MAPK pathways. The above results may provide a new perspective on targeting NOD1 signalling for the treatment of PTC, which deserves further investigation.

Nucleotide-Binding Oligomerization Domain-Containing Protein 1 Regulates Inflammatory Response in Endometriosis.

BACKGROUND: Nucleotide-binding oligomerization domain-containing protein 1 (NOD1) is known to play an important role in innate immunity, while the relationship between NOD1 and inflammatory response in endometriosis remains unknown. The present study aims to investigate the effects of NOD1 on inflammatory response in endometriosis. METHODS: Immunohistochemistry staining, Western blot, and qRT-PCR were conducted to investigate the levels of NOD1 and inflammatory cytokines in the endometriotic lesions. A Spearman's rank correlation analysis was conducted to determine the correlations of NOD1 and inflammatory cytokines (interleukin (IL)-6, tumor necrosis factor (TNF)-α, and monocyte chemoattractant protein (MCP)-1). Human endometrial stromal cells (HESCs) were isolated and incubated with peritoneal fluid with or without ML130. Cell viability was determined by using an MTT assay. RESULTS: A significant elevation in NOD1 and inflammatory cytokine was observed in ectopic endometrium. Interestingly, a positive correlation between NOD1 and inflammatory cytokines was observed. In addition, treatment with ML130 significantly suppressed cell viability and the production of inflammatory cytokines in the 20% peritoneal fluid treated ectopic HESCs. CONCLUSIONS: NOD1 is related to the inflammatory response that is involved in endometriosis.

Roles of NOD1/Rip2 signal pathway in carotid artery remodelling in spontaneous hypertensive rats.

Nucleotide-binding and oligomerization domain (NOD) receptor is a member of inherent immunity recognition receptor family. We investigated the NOD1/Rip2 signalling pathway on carotid arterial remodelling in spontaneously hypertensive rats (SHRs). SHRs were treated with NOD1 agonist (iE-DAP), inhibitor (ML130), or normal saline. We determined the NOD1 and Rip2 expression in carotid artery tissues, serum tumour necrosis factor-α (TNF-α) and monocyte chemotactic protein-1 (MCP-1). The carotid artery remodelling in 16-week SHRs was higher than that of 8-week SHRs and 16-week Wistar-Kyoto (WKY) rats. Expression of NOD1, Rip2, MCP-1 and TNF-α in 16-week SHRs was higher than that of 8-week SHRs and 16-week WKY rats. Blood pressure in iE-DAP-treated SHRs was higher than SHR-C group (no treatment), together with MCP-1, TNF-α, NOD1 and Rip2 expression, as well as carotid artery remodelling. In ML130-treated group, these aspects were completely the opposite. Taken together, inhibition of NOD1/Rip2 signalling pathway could delay the vascular remodelling process.