NOD1 variation, immunoglobulin E and asthma

Revealing the mechanism of fiber promoting sow embryo implantation by altering the abundance of uterine fluid proteins: A proteomic perspective

Many studies have shown that fiber in the diet plays an important role in improving the reproductive performance of sows, but there is rarely research on the impact of fiber on early embryo implantation. This study used 4D-Label free technology to identify and analyze the effect of the fiber composition in the diet on the protein in the early pregnancy uterine fluid (UF) of sows. The results indicate that ratio of insoluble fibers to soluble fibers (ISF/SF) 4.89 can increase the concentration of progesterone (PROG) and reduce tumor necrosis factorα (TNF-α) concentration in sow UF. In addition, through 4D-Label free, we identified a total of 4248 proteins, 38 proteins abundance upregulated and 283 proteins abundance downregulated in UF. Through enrichment analysis of these differential abundance proteins (DAPs), it was found that these differential proteins are mainly related to the docking of extracellular vesicles, vesicular transport, inflammatory response, and insulin resistance. Therefore, the results of this study reveal the possible mechanism by which fiber improves the reproductive performance of sows, laying a theoretical foundation for future research on the effects of diet on reproduction. SIGNIFICANCE: This study demonstrates the importance of dietary fiber for early embryo implantation in sows. The effect of dietary ISF/SF on early embryo implantation in sows was elucidated from a proteomic perspective through 4D-Label free technology. This study not only has significant implications for improving sow reproductive efficiency, but also provides important theoretical references for studying early miscarriage and reproductive nutrition in human pregnancy.

The NLR family of innate immune and cell death sensors

Nucleotide-binding oligomerization domain (NOD)-like receptors, also known as nucleotide-binding leucine-rich repeat receptors (NLRs), are a family of cytosolic pattern recognition receptors that detect a wide variety of pathogenic and sterile triggers. Activation of specific NLRs initiates pro- or anti-inflammatory signaling cascades and the formation of inflammasomes-multi-protein complexes that induce caspase-1 activation to drive inflammatory cytokine maturation and lytic cell death, pyroptosis. Certain NLRs and inflammasomes act as integral components of larger cell death complexes-PANoptosomes-driving another form of lytic cell death, PANoptosis. Here, we review the current understanding of the evolution, structure, and function of NLRs in health and disease. We discuss the concept of NLR networks and their roles in driving cell death and immunity. An improved mechanistic understanding of NLRs may provide therapeutic strategies applicable across infectious and inflammatory diseases and in cancer.

Microbial ligand-independent regulation of lymphopoiesis by NOD1

Aberrant differentiation of progenitor cells in the hematopoietic system is known to severely impact host immune responsiveness. Here we demonstrate that NOD1, a cytosolic innate sensor of bacterial peptidoglycan, also functions in murine hematopoietic cells as a major regulator of both the generation and differentiation of lymphoid progenitors as well as peripheral T lymphocyte homeostasis. We further show that NOD1 mediates these functions by facilitating STAT5 signaling downstream of hematopoietic cytokines. In steady-state, loss of NOD1 resulted in a modest but significant decrease in numbers of mature T, B and natural killer cells. During systemic protozoan infection this defect was markedly enhanced, leading to host mortality. Lack of functional NOD1 also impaired T cell-dependent anti-tumor immunity while preventing colitis. These findings reveal that, in addition to its classical role as a bacterial ligand receptor, NOD1 plays an important function in regulating adaptive immunity through interaction with a major host cytokine signaling pathway.

Nod1-dependent NF-kB activation initiates hematopoietic stem cell specification in response to small Rho GTPases

Uncovering the mechanisms regulating hematopoietic specification not only would overcome current limitations related to hematopoietic stem and progenitor cell (HSPC) transplantation, but also advance cellular immunotherapies. However, generating functional human induced pluripotent stem cell (hiPSC)-derived HSPCs and their derivatives has been elusive, necessitating a better understanding of the developmental mechanisms that trigger HSPC specification. Here, we reveal that early activation of the Nod1-Ripk2-NF-kB inflammatory pathway in endothelial cells (ECs) primes them to switch fate towards definitive hemogenic endothelium, a pre-requisite to specify HSPCs. Our genetic and chemical embryonic models show that HSPCs fail to specify in the absence of Nod1 and its downstream kinase Ripk2 due to a failure on hemogenic endothelial (HE) programming, and that small Rho GTPases coordinate the activation of this pathway. Manipulation of NOD1 in a human system of definitive hematopoietic differentiation indicates functional conservation. This work establishes the RAC1-NOD1-RIPK2-NF-kB axis as a critical intrinsic inductor that primes ECs prior to HE fate switch and HSPC specification. Manipulation of this pathway could help derive a competent HE amenable to specify functional patient specific HSPCs and their derivatives for the treatment of blood disorders.

Clinical Disease States Related to Mutations of the NOD2 Gene: A Case Report and Literature Review

Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) is a protein encoded by the NOD2 gene and plays an important role in the immune system. NOD2 is an intracellular pattern recognition receptor (PRR) responsible for the recognition of pathogens as well as the activation of many biochemical processes within cells of the host immune system. Mutations of the NOD2 gene can significantly impact the host's immune response against a variety of pathogens. In addition to immunodeficiency, mutations of the NOD2 gene have also been linked with several atopic diseases and autoimmune conditions such as rheumatoid arthritis and Crohn's disease (CD). There is also a distinct set of autoinflammatory conditions that are now classified as NOD2-associated autoinflammatory diseases (NAID). We present a case of a 63-year-old female with common variable immunodeficiency, eosinophilic asthma, and rheumatoid arthritis who was found to have a NOD2 mutation on genetic testing. As genetic testing continues to gain popularity, several disease states that were previously thought to be unrelated are now being recognized as originating from a common genetic defect.

Recent advances in the development of RIPK2 modulators for the treatment of inflammatory diseases

Receptor-interacting serine/threonine kinase 2 (RIPK2) is a vital immunomodulator that plays critical roles in nucleotide-binding oligomerization domain 1 (NOD1), NOD2, and Toll-like receptors (TLRs) signaling. Stimulated NOD1 and NOD2 interact with RIPK2 and lead to the activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPK), followed by the production of pro-inflammatory cytokines such as TNF-α, IL-6, and IL-12/23. Defects in NOD/RIPK2 signaling are associated with numerous inflammatory diseases, including asthma, sarcoidosis, inflammatory bowel disease (Crohn's disease and ulcerative colitis), multiple sclerosis, and Blau syndrome. As RIPK2 is a crucial element of innate immunity, small molecules regulating RIPK2 functions are attractive to establish novel immunotherapies. The increased interest in developing RIPK2 inhibitors has led to the clinical investigations of novel drug candidates. In this review, we attempt to summarize recent advances in the development of RIPK2 inhibitors and degraders.

NOD-like receptors in asthma

Asthma is an extremely prevalent chronic inflammatory disease of the airway where innate and adaptive immune systems participate collectively with epithelial and other structural cells to cause airway hyperresponsiveness, mucus overproduction, airway narrowing, and remodeling. The nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) are a family of intracellular innate immune sensors that detect microbe-associated molecular patterns and damage-associated molecular patterns, well-recognized for their central roles in the maintenance of tissue homeostasis and host defense against bacteria, viruses and fungi. In recent times, NLRs have been increasingly acknowledged as much more than innate sensors and have emerged also as relevant players in diseases classically defined by their adaptive immune responses such as asthma. In this review article, we discuss the current knowledge and recent developments about NLR expression, activation and function in relation to asthma and examine the potential interventions in NLR signaling as asthma immunomodulatory therapies.

NOD1, NOD2, and NLRC5 Receptors in Antiviral and Antimycobacterial Immunity

The innate immune system recognizes pathogen-associated molecular motifs through pattern recognition receptors (PRRs) that induce inflammasome assembly in macrophages and trigger signal transduction pathways, thereby leading to the transcription of inflammatory cytokine genes. Nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) represent a family of cytosolic PRRs involved in the detection of intracellular pathogens such as mycobacteria or viruses. In this review, we discuss the role of NOD1, NOD2, and NLRC5 receptors in regulating antiviral and antimycobacterial immune responses by providing insight into molecular mechanisms as well as their potential health and disease implications.

Design, synthesis, and structure-activity relationship of novel RIPK2 inhibitors

The NOD1/2 (nucleotide-binding oligomerization domain-containing protein 1/2) signaling pathways are involved in innate immune control and host defense. NOD dysfunction can result in a variety of autoimmune disorders. NOD-induced generation of inflammatory cytokines is mediated by receptor-interacting protein kinase 2 (RIPK2), which has been considered as a promising therapeutic target. Herein, we disclose the design, synthesis, and SAR study of a series of RIPK2 inhibitors. The lead compound 17 displayed a high affinity for RIPK2 (K_d = 5.9 nM) and was capable of inhibiting RIPK2 kinase function in an ADP-Glo assay. In vitro DMPK studies showed that compound 17 had good metabolic stability and no CYP inhibition. Compound 17 effectively suppressed inflammatory cytokine production in both cells and animal model.

Bacterial subversion of NLR-mediated immune responses

Members of the mammalian Nod-like receptor (NLR) protein family are important intracellular sensors for bacteria. Bacteria have evolved under the pressure of detection by host immune sensing systems, leading to adaptive subversion strategies to dampen immune responses for their benefits. These include modification of microbe-associated molecular patterns (MAMPs), interception of innate immune pathways by secreted effector proteins and sophisticated instruction of anti-inflammatory adaptive immune responses. Here, we summarise our current understanding of subversion strategies used by bacterial pathogens to manipulate NLR-mediated responses, focusing on the well-studied members NOD1/2, and the inflammasome forming NLRs NLRC4, and NLRP3. We discuss how bacterial pathogens and their products activate these NLRs to promote inflammation and disease and the range of mechanisms used by bacterial pathogens to evade detection by NLRs and to block or dampen NLR activation to ultimately interfere with the generation of host immunity. Moreover, we discuss how bacteria utilise NLRs to facilitate immunotolerance and persistence in the host and outline how various mechanisms used to attenuate innate immune responses towards bacterial pathogens can also aid the host by reducing immunopathologies. Finally, we describe the therapeutic potential of harnessing immune subversion strategies used by bacteria to treat chronic inflammatory conditions.

Emerging Insights into the Impact of Air Pollution on Immune-Mediated Asthma Pathogenesis

PURPOSE OF REVIEW

Increases in ambient levels of air pollutants have been linked to lung inflammation and remodeling, processes that lead to the development and exacerbation of allergic asthma. Conventional research has focused on the role of CD4+ T helper 2 (TH2) cells in the pathogenesis of air pollution-induced asthma. However, much work in the past decade has uncovered an array of air pollution-induced non-TH2 immune mechanisms that contribute to allergic airway inflammation and disease.

RECENT FINDINGS

In this article, we review current research demonstrating the connection between common air pollutants and their downstream effects on non-TH2 immune responses emerging as key players in asthma, including PRRs, ILCs, and non-TH2 T cell subsets. We also discuss the proposed mechanisms by which air pollution increases immune-mediated asthma risk, including pre-existing genetic risk, epigenetic alterations in immune cells, and perturbation of the composition and function of the lung and gut microbiomes. Together, these studies reveal the multifaceted impacts of various air pollutants on innate and adaptive immune functions via genetic, epigenetic, and microbiome-based mechanisms that facilitate the induction and worsening of asthma.

Nucleotide oligomerization domain polymorphism confers no risk to Guillain-Barré syndrome

OBJECTIVES

Nucleotide oligomerization domain (NOD) proteins are cytoplasmic receptors that play important roles in host innate immune responses to pathogens by recognizing self or non-self-molecules and have been implicated in many autoimmune diseases including Guillain-Barré syndrome (GBS). The current study investigated whether NOD polymorphisms (NOD1-Glu266Lys, rs2075820, and NOD2- [Arg702Trp, rs2066844 and Gly908Arg, rs2066845]) contribute to ligand sensing and thus affect the susceptibility and/or severity of GBS.

MATERIALS AND METHODS

We determined single nucleotide polymorphisms (SNPs) of NOD gene (NOD1-Glu266Lys and NOD2-[Arg702Trp; Gly908Ar]) in 303 patients with GBS and 303 healthy controls from Bangladesh by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and Sanger sequencing. Genotypes and allele frequencies were compared by performing chi-squared or Fisher's exact test with Yates' continuity correction. Serology for Campylobacter jejuni and anti-GM1 antibodies were determined by enzyme-linked immunosorbent assay (ELISA) techniques.

RESULTS

NOD variants (NOD1-Glu266Lys and NOD2- [Arg702Trp; Gly908Arg]) were not associated with susceptibility and severity of GBS when compared with healthy controls and mild or severe form of disease. Moreover, NOD2 polymorphisms showed wild-type NOD2 C2104 and NOD2 G2722, respectively, with homozygous Arg/Arg genotype of NOD2 (Arg702Trp) polymorphism and homozygous Gly/Gly genotype of NOD2 (Gly908Arg) for all study subjects in Bangladesh. Homogenous distribution of NOD1 genotypes was observed in patients with axonal and demyelinating form of GBS.

CONCLUSIONS

NOD variants confer no risk to the susceptibility and severity of GBS. Moreover, NOD2 polymorphism is rare or absent in patients with GBS as well as in the healthy individuals of Bangladesh.

Kinases on Double Duty: A Review of UniProtKB Annotated Bifunctionality within the Kinome

Phosphorylation facilitates the regulation of all fundamental biological processes, which has triggered extensive research of protein kinases and their roles in human health and disease. In addition to their phosphotransferase activity, certain kinases have evolved to adopt additional catalytic functions, while others have completely lost all catalytic activity. We searched the Universal Protein Resource Knowledgebase (UniProtKB) database for bifunctional protein kinases and focused on kinases that are critical for bacterial and human cellular homeostasis. These kinases engage in diverse functional roles, ranging from environmental sensing and metabolic regulation to immune-host defense and cell cycle control. Herein, we describe their dual catalytic activities and how they contribute to disease pathogenesis.

Association of NOD1, NOD2, PYDC1 and PYDC2 genes with Behcet's disease susceptibility and clinical manifestations

Purpose: Behçet's disease (BD) is an autoinflammatory disease with clinical manifestations such as mucocutaneous, ocular, vascular, gastrointestinal, musculoskeletal and central nervous system involvement. Features of innate and adaptive immunity and inflammasome pathways have been claimed in the pathogenesis of BD. We aimed to investigate the roles of NOD1, NOD2, PYDC1 and PYDC2 genes in the genetic predisposition of BD.Materials and Methods: Genetic variations of NOD1 (rs2075820 and rs2075818) and NOD2 (R334Q and R334W) genes were explored in 68 BD patients and 70 controls with PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) approach. PYDC1 and PYDC2 gene variants were investigated by Sanger sequencing.Results: The polymorphism of rs2075820 (NOD1 G/A) had a statistically significant difference between the BD and controls, AA genotype was 2.460-fold protective. When compared in terms of cardiovascular involvement in BD patients, AA genotype was increased the risk of cardiovascular involvement 4.286-fold. There was a significant difference between BD and controls in rs2075818 (NOD1 G/C) polymorphism and CC genotype increased the risk of BD by 3.780-fold. In terms of rs2075818 variants, there was a statistically significant difference between BD patients with ocular lesions, joints, cardiovascular and gastrointestinal involvement and controls. There was a significant difference between the patients with joint involvement and controls and the risk increased of 3.310-fold.Conclusion: The data shed new light on the association between polymorphisms of NOD1 gene and BD and clinicial manifestations. However, NOD2, PYDC1 and PYDC2 genes were not associated with BD in the Turkish population.

Immunological Roles of NLR in Allergic Diseases and Its Underlying Mechanisms

Our understanding on the immunological roles of pathogen recognition in innate immunity has vastly increased over the past 20 years. Nucleotide-binding oligomerization domain (NOD)-like receptors (NLR) are cytosolic pattern recognition receptors (PRR) that are responsible for sensing microbial motifs and endogenous damage signals in mammalian cytosol for immune surveillance and host defense. The accumulating discoveries on these NLR sensors in allergic diseases suggest that the pathogenesis of allergic diseases may not be confined to the adaptive immune response. Therapy targeting NLR in murine models also shields light on its potential in the treatment of allergies in man. In this review, we herein summarize the recent understanding of the role of NLR sensors and their molecular mechanisms involved in allergic inflammation, including atopic dermatitis and allergic asthma.

NOD1 sensing of house dust mite-derived microbiota promotes allergic experimental asthma

BACKGROUND

Asthma severity has been linked to exposure to gram-negative bacteria from the environment that are recognized by NOD1 receptor and are present in house dust mite (HDM) extracts. NOD1 polymorphism has been associated with asthma.

OBJECTIVE

We sought to evaluate whether either host or HDM-derived microbiota may contribute to NOD1-dependent disease severity.

METHODS

A model of HDM-induced experimental asthma was used and the effect of NOD1 deficiency was evaluated. Contribution of host microbiota was evaluated by fecal transplantation. Contribution of HDM-derived microbiota was assessed by 16S ribosomal RNA sequencing, mass spectrometry analysis, and peptidoglycan depletion of the extracts.

RESULTS

In this model, loss of the bacterial sensor NOD1 and its adaptor RIPK2 improved asthma features. Such inhibitory effect was not related to dysbiosis caused by NOD1 deficiency, as shown by fecal transplantation of Nod1-deficient microbiota to wild-type germ-free mice. The 16S ribosomal RNA gene sequencing and mass spectrometry analysis of HDM allergen, revealed the presence of some muropeptides from gram-negative bacteria that belong to the Bartonellaceae family. While such HDM-associated muropeptides were found to activate NOD1 signaling in epithelial cells, peptidoglycan-depleted HDM had a decreased ability to instigate asthma in vivo.

CONCLUSIONS

These data show that NOD1-dependent sensing of HDM-associated gram-negative bacteria aggravates the severity of experimental asthma, suggesting that inhibiting the NOD1 signaling pathway may be a therapeutic approach to treating asthma.

The Role of the NOD1/Rip2 Signaling Pathway in Myocardial Remodeling in Spontaneously Hypertensive Rats

BACKGROUND Chronic hypertension changes the function and structure of the heart and blood vessels. This study aimed to explore the role of the NOD1/Rip2 (nucleotide-binding oligomerization domain 1/receptor-interacting protein 2) signaling pathway in myocardial remodeling in spontaneously hypertensive rats (SHRs). MATERIAL AND METHODS Blood pressure was measured using a tail cuff. The cardiac structure was observed using echocardiography. Slices of the myocardium were stained with hematoxylin and eosin. The expression of NOD1 and Rip2 was detected using real-time polymerase chain reaction, western blot, and immunohistochemistry. The content and distribution of collagen in the myocardium were observed using Van Gieson staining. Enzyme-linked immunosorbent assay was used to detect the interleukin-1 (IL-1) concentrations. SHRs were treated with the NOD1 agonist iE-DAP and NOD1 inhibitor ML130. RESULTS The NOD1 agonist increased blood pressure in SHRs, and the NOD1 inhibitor decreased blood pressure; the interventricular septum thickness (IVST) and left ventricular posterior wall thickness (LVPWT) of the agonist-treated group were thicker than those of the control group, and the antagonist exerted the opposite effects. The levels of the NOD1 and Rip2 mRNAs and proteins, serum IL-1 concentration, and myocardial collagen volume fraction (CVF%) increased in SHRs in the NOD1 agonist group, but the levels of NOD1 and Rip2, serum IL-1 concentration, and myocardial collagen volume fraction (CVF%) decreased in SHRs in the NOD1 inhibitor group. CONCLUSIONS NOD1/Rip2 expression increased during the progression of myocardial remodeling in SHRs. The NOD1 agonist increased NOD1 expression and promoted myocardial remodeling, while the NOD1 antagonist reduced NOD1/Rip2 expression and protected against myocardial remodeling.

Identification of benzofused five-membered sultams, potent dual NOD1/NOD2 antagonists in vitro and in vivo

Nucleotide-binding oligomerization domain-containing proteins 1 and 2 play important roles in immune system activation. Recently, a shift has occurred due to the emerging knowledge that preventing nucleotide-binding oligomerization domains (NODs) signaling could facilitate the treatment of some cancers, which warrants the search for dual antagonists of NOD1 and NOD2. Herein, we undertook the synthesis and identification of a new class of derivatives of dual NOD1/NOD2 antagonists with novel benzofused five-membered sultams. Compound 14k was finally demonstrated to be the most potent molecule that inhibits both NOD1-and NOD2-stimulated NF-κB and MAPK signaling in vitro and in vivo.

NOD1 and NOD2 in inflammatory and infectious diseases

It has been long recognized that NOD1 and NOD2 are critical players in the host immune response, primarily by their sensing bacterial peptidoglycan-conserved motifs. Significant advances have been made from efforts that characterize their upstream activators, assembly of signaling complexes, and activation of downstream signaling pathways. Disruption in NOD1 and NOD2 signaling has also been associated with impaired host defense and resistance to the development of inflammatory diseases. In this review, we will describe how NOD1 and NOD2 sense microbes and cellular stress to regulate host responses that can affect disease pathogenesis and outcomes.

Inflammasomes in Common Immune-Related Skin Diseases

The inflammasome is an important protein complex that cleaves the proinflammatory cytokines pro-IL-1β and pro-IL-18 into their active forms. Owing to its critical role in eliciting innate immune responses, IL-1β has been suggested to contribute to various skin diseases, including psoriasis, vitiligo, systemic lupus erythematosus (SLE), and atopic dermatitis (AD). Recently, several types of activators and inhibitors of different inflammasomes, as well as inflammasome-related genes and genetic susceptibility loci, have been identified in these immune-related common skin diseases. In particular, inflammasome activators and inhibitors presented highly cell-type-specific activity, suggesting that the inflammasome might perform different functions in different cell types. Moreover, most of these findings were based on experimental disease models, and the clinical features of the models partly resemble the typical symptoms of the diseases. In this review, from the perspective of activators and inhibitors, we collected evidence from the widely-studied inflammasomes, NLRP3, AIM2, and NLRP1, in psoriasis, vitiligo, SLE, and AD. Importantly, some small-molecule inhibitors hold therapeutic promise for the treatment of these diseases.

Current Understanding of Nasal Epithelial Cell Mis-Differentiation

The functional role of the respiratory epithelium is to generate a physical barrier. In addition, the epithelium supports the innate and acquired immune system through various cytokines and chemokines. However, epithelial cells are also involved in the pathogenesis of various respiratory diseases, some of which are mediated by increased permeability of the mucosal membrane or disturbed mucociliary transport. In addition, it has been shown that epithelial cells are involved in the development of inflammatory respiratory diseases. The following review article focuses on the aspects of epithelial mis-differentiation, in particular with respect to nasal mucosal barrier function, epithelial immunogenicity, nasal epithelial-mesenchymal transition and nasal microbiome.

Discovery of Pyrazolocarboxamides as Potent and Selective Receptor Interacting Protein 2 (RIP2) Kinase Inhibitors

Herein we report the discovery of pyrazolocarboxamides as novel, potent, and kinase selective inhibitors of receptor interacting protein 2 kinase (RIP2). Fragment based screening and design principles led to the identification of the inhibitor series, and X-ray crystallography was used to inform key structural changes. Through key substitutions about the N1 and C5 N positions on the pyrazole ring significant kinase selectivity and potency were achieved. Bridged bicyclic pyrazolocarboxamide 11 represents a selective and potent inhibitor of RIP2 and will allow for a more detailed investigation of RIP2 inhibition as a therapeutic target for autoinflammatory disorders.

Innate immunity in allergy

Innate immune system quickly responds to invasion of microbes and foreign substances through the extracellular and intracellular sensing receptors, which recognize distinctive molecular and structural patterns. The recognition of innate immune receptors leads to the induction of inflammatory and adaptive immune responses by activating downstream signaling pathways. Allergy is an immune-related disease and results from a hypersensitive immune response to harmless substances in the environment. However, less is known about the activation of innate immunity during exposure to allergens. New insights into the innate immune system by sensors and their signaling cascades provide us with more important clues and a framework for understanding allergy disorders. In this review, we will focus on recent advances in the innate immune sensing system.

The association of nucleotide-binding oligomerization domain 2 gene polymorphisms with the risk of asthma in the Chinese Han population

BACKGROUND

Genetic background is one of the important risk factors for development of asthma. The nucleotide-binding oligomerization domain 2 (NOD2) has been involved in the pathogenesis of asthma. The purpose of this study was to explore the relationship between NOD2 gene polymorphisms and asthma susceptibility in the Chinese Han population.

METHODS

Children with asthma (n = 309) and Healthy children (n = 163) were recruited from Yancheng Third People's Hospital, Yancheng, China, between January 2016 and December 2017. The NOD2 gene polymorphisms were measured by the Snapshot SNP genotyping assays. Genotyping was performed for 4 tag SNPs of NOD2. Serum IFN-β levels were measured by ELISA.

RESULTS

The serum IFN-β levels were significantly lower in Asthmatic children than those in the controls (p < 0.001). Low levels of IFN-β may be related to the susceptibility to severe asthma. The rs3135499 C allele was associated with a significantly increased risk of asthma as compared with the rs3135499 A allele.

CONCLUSION

The rs3135499 polymorphism of NOD2 gene and IFN-β may play a role in the pathogenesis of asthma.

Gene Variants, mRNA and NOD1/2 Protein Levels in Tunisian Childhood Asthma

INTRODUCTION

Asthma is a common respiratory childhood disease that results from an interaction between genetic, environmental and immunologic factors. The implication of nucleotide-binding and oligomerization domain 1 and 2 (NOD1/CARD4, NOD2/CARD15) was highlighted in many inflammatory diseases.

METHODS

In this case-control study, we analyzed the association of three NOD2 polymorphisms and one NOD1 variant, in 338 Tunisian asthmatic children and 425 healthy Controls, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. We also assessed NOD1 and NOD2 mRNA and protein levels by qRT-PCR and ELISA techniques.

RESULTS

The homozygous AA genotype of rs2075820 was a risk factor for asthma (OR 2.39). The influence of the E266K variant in the presence of the heterozygous AG genotype was higher in male than female groups. The homozygous AA genotype was a risk factor associated with asthma, for patients aged between 6 and 18 years OR 2.39, IC95% (1.04-5.49) p < 0.01. The mRNA expression of NOD1, but not NOD2, was enhanced in asthma patients compared to Controls. We noted a significant difference between asthmatics and healthy controls in NOD1 protein expression (asthma patients : 31.18 ± 10.9 pg/ml, Controls: 20.10 ± 2.58 pg/ml; p < 0.001).

CONCLUSIONS

The NOD1 rs2075820 variant was associated with a higher childhood asthma risk and the NOD1 expression at mRNA and protein levels was significantly increased in asthma patients.

Sequence-based structural analysis and evaluation of polymorphism in buffalo Nod-like receptor-1 gene

In this study, we have sequence characterized and analyzed the polymorphism in buffalo NOD1 (nucleotide-binding oligomerization domain 1) gene as well as its expression analysis. Full-length sequence analysis of NOD1 revealed this gene in buffalo being conserved with respect to the domain structures, similar to other species. Alternate splice variants having exon3 skipping also identified for the first time in the gene expressed in buffalo-purified peripheral blood mononuclear cells (PBMCs). Phylogenetically ruminant species were found to be clustering together and buffalo displaying maximum similarity with cattle. Sequencing of NOD1 across 12 Indian buffalo breeds identified 23 polymorphic sites within coding region, among which 16 were synonymous and 7 changes found to be non-synonymous. Four SNPs (single nucleotide polymorphisms) of them were genotyped in 393 animals belonging to 12 riverine, swamp and hybrid (riverine × swamp) buffalo populations of diverse phenotypes and utilities, showing variable allelic frequencies. Principal component analysis revealed, riverine and swamp buffaloes being distinctly placed with the distribution of breeds within the group based on the geographical isolation. Further, quantitative real-time PCR detected NOD1 expression in multiple tissues with PBMCs and lungs showing highest expression among the tissues examined. Structural analysis based on the translated amino acid sequence of buffalo NOD1 identified four protein interaction motifs LxxLL important for ligand binding. Molecular interaction analysis of iE-DAP and NOD1-LRR and their complex stability and binding-free energy studies indicated variable binding energies in buffalo and cattle NOD1. Overall, the study reveals unique structural features in buffalo NOD1, important for species-specific ligand interaction.

Pulmonary immunity and extracellular matrix interactions

The lung harbors a complex immune system composed of both innate and adaptive immune cells. Recognition of infection and injury by receptors on lung innate immune cells is crucial for generation of antigen-specific responses by adaptive immune cells. The extracellular matrix of the lung, comprising the interstitium and basement membrane, plays a key role in the regulation of these immune systems. The matrix consists of several hundred assembled proteins that interact to form a bioactive scaffold. This template, modified by enzymes, acts to facilitate cell function and differentiation and changes dynamically with age and lung disease. Herein, we explore relationships between innate and adaptive immunity and the lung extracellular matrix. We discuss the interactions between extracellular matrix proteins, including glycosaminoglycans, with prominent effects on innate immune signaling effectors such as toll-like receptors. We describe the relationship of extracellular matrix proteins with adaptive immunity and leukocyte migration to sites of injury within the lung. Further study of these interactions will lead to greater knowledge of the role of matrix biology in lung immunity. The development of novel therapies for acute and chronic lung disease is dependent on a comprehensive understanding of these complex matrix-immunity interactions.

Celiac Diasease-associated lncRNA Named HCG14 Regulates NOD1 Expression in Intestinal Cells

OBJECTIVE

The aim of the study is to identify additional celiac disease associated loci in the major histocompatibility complex (MHC) independent from classical HLA risk alleles (HLA-DR3-DQ2) and to characterize their potential functional impact in celiac disease pathogenesis at the intestinal level.

METHODS

We performed a high-resolution single-nucleotide polymorphism (SNP) genotyping of the MHC region, comparing HLA-DR3 homozygous celiac patients and non-celiac controls carrying a single copy of the B8-DR3-DQ2 conserved extended haplotype. Expression level of potential novel risk genes was determined by RT-PCR in intestinal biopsies and in intestinal and immune cells isolated from control and celiac individuals. Small interfering RNA-driven silencing of selected genes was performed in the intestinal cell line T84.

RESULTS

MHC genotyping revealed 2 associated SNPs, one located in TRIM27 gene and another in the non-coding gene HCG14. After stratification analysis, only HCG14 showed significant association independent from HLA-DR-DQ loci. Expression of HCG14 was slightly downregulated in epithelial cells isolated from duodenal biopsies of celiac patients, and eQTL analysis revealed that polymorphisms in HCG14 region were associated with decreased NOD1 expression in duodenal intestinal cells.

CONCLUSIONS

We have successfully employed a conserved extended haplotype-matching strategy and identified a novel additional celiac disease risk variant in the lncRNA HCG14. This lncRNA seems to regulate the expression of NOD1 in an allele-specific manner. Further functional studies are needed to clarify the role of HCG14 in the regulation of gene expression and to determine the molecular mechanisms by which the risk variant in HCG14 contributes to celiac disease pathogenesis.

MicroRNA-495 inhibits the high glucose-induced inflammation, differentiation and extracellular matrix accumulation of cardiac fibroblasts through downregulation of NOD1

Background

MicroRNAs (miRNAs) have physiological and pathophysiological functions that are involved in the regulation of cardiac fibrosis. This study aimed to investigate the effects of miR-495 on high glucose-induced cardiac fibrosis in human cardiac fibroblasts (CFs) and to establish the mechanism underlying these effects.

Methods

Human CFs were transfected with an miR-495 inhibitor or mimic and incubated with high glucose. The levels of NOD1 and miR-495 were then determined via quantitative RT-PCR. Pro-inflammatory cytokine levels, cell differentiation and extracellular matrix accumulation were respectively detected using ELISA, quantitative RT-PCR and western blot assays. The luciferase reporter assay, quantitative RT-PCR and western blot were used to explore whether NOD1 was a target of miR-495. The effects of miR-495 on the NF-κB and TGF-β1/Smad signaling pathways were also detected via western blot.

Results

Our results show that high glucose can significantly increase the expression of NOD1 in a time-dependent manner. Upregulation of miR-495 significantly alleviated the high glucose-induced increases in cell differentiation and collagen accumulation of CFs. Moreover, the bioinformatics analysis predicted that NOD1 was a potential target gene for miR-495. The luciferase reporter assay showed that miR-495 can directly target NOD1. The introduction of miR-495 could significantly inhibit the high glucose-activated NF-κB and TGF-β1/Smad signaling pathways.

Conclusion

Upregulation of miR-495 ameliorates the high glucose-induced inflammatory, cell differentiation and extracellular matrix accumulation of human CFs by modulating both the NF-κB and TGF-β1/Smad signaling pathways through downregulation of NOD1 expression. These results provide further evidence for the protective effect of miR-495 overexpression in cases of high glucose-induced cardiac fibrosis.

Genetic Mechanisms of Asthma and the Implications for Drug Repositioning

Asthma is a chronic disease that is caused by airway inflammation. The main features of asthma are airway hyperresponsiveness (AHR) and reversible airway obstruction. The disease is mainly managed using drug therapy. The current asthma drug treatments are divided into two categories, namely, anti-inflammatory drugs and bronchodilators. However, disease control in asthma patients is not very efficient because the pathogenesis of asthma is complicated, inducing factors that are varied, such as the differences between individual patients. In this paper, we delineate the genetic mechanisms of asthma, and present asthma-susceptible genes and genetic pharmacology in an attempt to find a diagnosis, early prevention, and treatment methods for asthma. Finally, we reposition some clinical drugs for asthma therapy, based on asthma genetics.

Immunoglobulin E-Mediated Autoimmunity

The study of autoimmunity mediated by immunoglobulin E (IgE) autoantibodies, which may be termed autoallergy, is in its infancy. It is now recognized that systemic lupus erythematosus, bullous pemphigoid (BP), and chronic urticaria, both spontaneous and inducible, are most likely to be mediated, at least in part, by IgE autoantibodies. The situation in other conditions, such as autoimmune uveitis, rheumatoid arthritis, hyperthyroid Graves’ disease, autoimmune pancreatitis, and even asthma, is far less clear but evidence for autoallergy is accumulating. To be certain of an autoallergic mechanism, it is necessary to identify both IgE autoantibodies and their targets as has been done with the transmembrane protein BP180 and the intracellular protein BP230 in BP and IL-24 in chronic spontaneous urticaria. Also, IgE-targeted therapies, such as anti-IgE, must have been shown to be of benefit to patients as has been done with both of these conditions. This comprehensive review of the literature on IgE-mediated autoallergy focuses on three related questions. What do we know about the prevalence of IgE autoantibodies and their targets in different diseases? What do we know about the relevance of IgE autoantibodies in different diseases? What do we know about the cellular and molecular effects of IgE autoantibodies? In addition to providing answers to these questions, based on a broad review of the literature, we outline the current gaps of knowledge in our understanding of IgE autoantibodies and describe approaches to address them.

NOD1 and NOD2: Beyond Peptidoglycan Sensing

NOD1 and NOD2 are pattern recognition receptors of the innate immune system with well-established roles in sensing fragments of bacterial peptidoglycan. In addition to their role as microbial sensors, recent evidence indicates that nucleotide-binding oligomerization domains (NODs) can also recognize a broader array of danger signals. Indeed, recent work has expanded the roles of NOD1 and NOD2 to encompass not only sensing of infections with viruses and parasites but also perceiving perturbations of cellular processes such as regulation of the actin cytoskeleton and maintenance of endoplasmic reticulum homeostasis. This review will comment on recent progress and point out emerging questions in these areas.

Understanding the molecular differential recognition of muramyl peptide ligands by LRR domains of human NOD receptors

Human nucleotide-binding oligomerization domain proteins, hNOD1 and hNOD2, are host intracellular receptors with C-terminal leucine-rich repeat (LRR) domains, which recognize specific bacterial peptidoglycan (PG) fragments as their ligands. The specificity of this recognition is dependent on the third amino acid of the stem peptide of the PG ligand, which is usually meso-diaminopimelic acid (mesoDAP) or l-lysine (l-Lys). Since the LRR domains of hNOD receptors had been experimentally shown to confer the PG ligand-sensing specificity, we developed three-dimensional structures of hNOD1-LRR and the hNOD2-LRR to understand the mechanism of differential recognition of muramyl peptide ligands by hNOD receptors. The hNOD1-LRR and hNOD2-LRR receptor models exhibited right-handed curved solenoid shape. The hot-spot residues experimentally proved to be critical for ligand recognition were located in the concavity of the NOD-LRR and formed the recognition site. Our molecular docking analyses and molecular electrostatic potential mapping studies explain the activation of hNOD-LRRs, in response to effective molecular interactions of PG ligands at the recognition site; and conversely, the inability of certain PG ligands to activate hNOD-LRRs, by deviations from the recognition site. Based on molecular docking studies using PG ligands, we propose few residues — G825, D826 and N850 in hNOD1-LRR and L904, G905, W931, L932 and S933 in hNOD2-LRR, evolutionarily conserved across different host species, which may play a major role in ligand recognition. Thus, our integrated experimental and computational approach elucidates the molecular basis underlying the differential recognition of PG ligands by hNOD receptors.

Danger of frustrated sensors: Role of Toll-like receptors and NOD-like receptors in aseptic and septic inflammations around total hip replacements

The innate immune sensors, Toll-like receptors (TLRs) and nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs), can recognize not only exogenous pathogen-associated molecular patterns (PAMPs), but also endogenous molecules created upon tissue injury, sterile inflammation, and degeneration. Endogenous ligands are called damage-associated molecular patterns (DAMPs), and include endogenous molecules released from activated and necrotic cells as well as damaged extracellular matrix. TLRs and NLRs can interact with various ligands derived from PAMPs and DAMPs, leading to activation and/or modulation of intracellular signalling pathways. Intensive research on the innate immune sensors, TLRs and NLRs, has brought new insights into the pathogenesis of not only various infectious and rheumatic diseases, but also aseptic foreign body granuloma and septic inflammation of failed total hip replacements (THRs). In this review, recent knowledge is summarized on the innate immune system, including TLRs and NLRs and their danger signals, with special reference to their possible role in the adverse local host response to THRs.

Translational potential of this article: A clear understanding of the roles of Toll-like receptors and NOD-like receptors in aseptic and septic loosening of joint replacements will facilitate potential strategies to mitigate these events, thereby extending the longevity of implants in humans.

Homology modeling and in silico prediction of Ulcerative colitis associated polymorphisms of NOD1

Cytosolic pattern recognition receptors play key roles in innate immune response. Nucleotide binding and oligomerisation domain containing protein 1 (NOD1) belonging to the Nod-like receptor C (NLRC) sub-family of Nod-like receptors (NLRs) is important for detection and clearance of intra-cellular Gram negative bacteria. NOD1 is involved in activation of pro-inflammatory pathways. Limited structural data is available for NOD1. Using different templates for each domain of NOD1, we determined the full-length homology model of NOD1. ADP binding amino acids within the nucleotide binding domain (NBD) of NOD1 were also predicted. Key residues in inter-domain interaction were identified by sequence comparison with Oryctolagus cuniculus NOD2, a related protein. Interactions between NBD and winged helix domain (WHD) were found to be conserved in NOD1. Functional and structural effect of single nucleotide polymorphisms within the NOD1 NBD domain associated with susceptibility risk to Ulcerative colitis (UC), an inflammatory disorder of the colon was evaluated by in silico studies. Mutations W219R and L349P were predicted to be damaging and disease associated by prediction programs SIFT, PolyPhen2, PANTHER, SNP&GO, PhD SNP and SNAP2. We further validated the effect of W219R and L349P mutation on NOD1 function in vitro. Elevated mRNA expression of pro-inflammatory cytokines IL8 and IL-1β was seen as compared to the wild type NOD1 in intestinal epithelial cell line HT29 when stimulated with NOD1 ligand. Thus, these mutations may indeed have a bearing on pathogenesis of inflammation during UC.

Genetic Variability as a Regulator of TLR4 and NOD Signaling in Response to Bacterial Driven DNA Damage Response (DDR) and Inflammation: Focus on the Gastrointestinal (GI) Tract

The fundamental role of human Toll-like receptors (TLRs) and NOD-like receptors (NLRs), the two most studied pathogen recognition receptors (PRRs), is the protection against pathogens and excessive tissue injury. Recent evidence supports the association between TLR/NLR gene mutations and susceptibility to inflammatory, autoimmune, and malignant diseases. PRRs also interfere with several cellular processes, such as cell growth, apoptosis, cell proliferation, differentiation, autophagy, angiogenesis, cell motility and migration, and DNA repair mechanisms. We briefly review the impact of TLR4 and NOD1/NOD2 and their genetic variability in the process of inflammation, tumorigenesis and DNA repair, focusing in the gastrointestinal tract. We also review the available data on new therapeutic strategies utilizing TLR/NLR agonists and antagonists for cancer, allergic diseases, viral infections and vaccine development against both infectious diseases and cancer.

Applications of reconstituted inflammasomes in a cell-free system to drug discovery and elucidation of the pathogenesis of autoinflammatory diseases

The inflammasome, typically consisting of a Nod-like receptor, apoptosis-associated speck-like protein, and pro-caspase-1, has recently been identified as a huge intracellular complex, which plays a crucial role in interleukin-1 maturation or specific physiological functions. Two Nod-like receptors, such as nucleotide-binding oligomerization domains-containing protein (Nod)1 and Nod2, interact with the receptor-interacting protein serine-threonine kinase (RIPK)2 accompanied by Iκ-B kinase (IKK) complexes to construct the nodosome, leading to nuclear factor (NF)-κB activation. The aberrant activation of inflammasomes or nodosomes causes autoinflammatory diseases. Therefore, inflammasomes may be attractive targets to treat autoinflammatory diseases. Our aim is to develop reconstituted inflammasomes in a cell-free system to discover specific molecular-target drugs and elucidate the molecular pathogenesis of autoinflammatory diseases. In this review, we describe reconstituted inflammasomes in a cell-free system.

NOD1CARD Might Be Using Multiple Interfaces for RIP2-Mediated CARD-CARD Interaction: Insights from Molecular Dynamics Simulation

The nucleotide-binding and oligomerization domain (NOD)-containing protein 1 (NOD1) plays the pivotal role in host-pathogen interface of innate immunity and triggers immune signalling pathways for the maturation and release of pro-inflammatory cytokines. Upon the recognition of iE-DAP, NOD1 self-oligomerizes in an ATP-dependent fashion and interacts with adaptor molecule receptor-interacting protein 2 (RIP2) for the propagation of innate immune signalling and initiation of pro-inflammatory immune responses. This interaction (mediated by NOD1 and RIP2) helps in transmitting the downstream signals for the activation of NF-κB signalling pathway, and has been arbitrated by respective caspase-recruitment domains (CARDs). The so-called CARD-CARD interaction still remained contradictory due to inconsistent results. Henceforth, to understand the mode and the nature of the interaction, structural bioinformatics approaches were employed. MD simulation of modelled 1:1 heterodimeric complexes revealed that the type-Ia interface of NOD1^CARD and the type-Ib interface of RIP2^CARD might be the suitable interfaces for the said interaction. Moreover, we perceived three dynamically stable heterotrimeric complexes with an NOD1:RIP2 ratio of 1:2 (two numbers) and 2:1. Out of which, in the first trimeric complex, a type-I NOD1-RIP2 heterodimer was found interacting with an RIP2^CARD using their type-IIa and IIIa interfaces. However, in the second and third heterotrimer, we observed type-I homodimers of NOD1 and RIP2 CARDs were interacting individually with RIP2^CARD and NOD1^CARD (in type-II and type-III interface), respectively. Overall, this study provides structural and dynamic insights into the NOD1-RIP2 oligomer formation, which will be crucial in understanding the molecular basis of NOD1-mediated CARD-CARD interaction in higher and lower eukaryotes.

The Pathogenetic Effect of Natural and Bacterial Toxins on Atopic Dermatitis

Atopic dermatitis (AD) is a common allergic skin disease that is associated with chronic, recurrent eczematous and pruritic lesions at the flexural folds caused by interacting factors related to environmental and immune system changes. AD results in dry skin, and immunoglobulin E-mediated allergic reactions to foods and environmental allergens. While steroids and anti-histamines temporarily relieve the symptoms of AD, the possibility of side effects from pharmacological interventions remains. Despite intensive research, the underlying mechanisms for AD have not been clarified. A study of Staphylococcus aureus (S. aureus) established the role of its toxins in the pathogenesis of AD. Approximately 90% of patients with AD experience S. aureus colonization and up to 50%–60% of the colonizing S. aureus is toxin-producing. Any damage to the protective skin barrier allows for the entry of invading allergens and pathogens that further drive the pathogenesis of AD. Some natural toxins (or their components) that have therapeutic effects on AD have been studied. In addition, recent studies on inflammasomes as one component of the innate immune system have been carried out. Additionally, studies on the close relationship between the activation of inflammasomes and toxins in AD have been reported. This review highlights the literature that discusses the pathogenesis of AD, the role of toxins in AD, and the positive and negative effects of toxins on AD. Lastly, suggestions are made regarding the role of inflammasomes in AD.

Role of nucleotide-binding oligomerization domain 1 (NOD1) and its variants in human cytomegalovirus control in vitro and in vivo

Induction of nucleotide-binding oligomerization domain 2 (NOD2) and downstream receptor-interacting serine/threonine-protein kinase 2 (RIPK2) by human cytomegalovirus (HCMV) is known to up-regulate antiviral responses and suppress virus replication. We investigated the role of nucleotide-binding oligomerization domain 1 (NOD1), which also signals through RIPK2, in HCMV control. NOD1 activation by Tri-DAP (NOD1 agonist) suppressed HCMV and induced IFN-β. Mouse CMV was also inhibited through NOD1 activation. NOD1 knockdown (KD) or inhibition of its activity with small molecule ML130 enhanced HCMV replication in vitro. NOD1 mutations displayed differential effects on HCMV replication and antiviral responses. In cells overexpressing the E56K mutation in the caspase activation and recruitment domain, virus replication was enhanced, but in cells overexpressing the E266K mutation in the nucleotide-binding domain or the wild-type NOD1, HCMV was inhibited, changes that correlated with IFN-β expression. The interaction of NOD1 and RIPK2 determined the outcome of virus replication, as evidenced by enhanced virus growth in NOD1 E56K mutant cells (which failed to interact with RIPK2). NOD1 activities were executed through IFN-β, given that IFN-β KD reduced the inhibitory effect of Tri-DAP on HCMV. Signaling through NOD1 resulting in HCMV suppression was IKKα-dependent and correlated with nuclear translocation and phosphorylation of IRF3. Finally, NOD1 polymorphisms were significantly associated with the risk of HCMV infection in women who were infected with HCMV during participation in a glycoprotein B vaccine trial. Collectively, our data indicate a role for NOD1 in HCMV control via RIPK2- IKKα-IRF3 and suggest that its polymorphisms predict the risk of infection.

Effects of genetic variations in the genes encoding NOD1 and NOD2 on type 2 diabetes mellitus and insulin resistance

WHAT IS KNOWN AND OBJECTIVE

Nucleotide-binding oligomerization domain (NOD) 1 and NOD 2 are members of the NOD-like receptor (NLR) family and contain a caspase recruitment domain. NLRs are located in the cytosol, bind bacterial and viral ligands and play a key role in the realization of innate and adaptive immune response, inflammation, apoptosis and reactive oxygen species generation. Insulin resistance (IR) is a leading cause of type 2 diabetes mellitus (T2DM) and associated with obesity, inflammation and pro-inflammatory responses. NOD1 and NOD2 gene variants may affect the risk of chronic inflammation, insulin resistance and T2DM by shifting the balance between pro- and anti-inflammatory cytokines. The aim of our study was to determine whether the NOD1/2 gene variants might contribute to the risk of T2DM and IR.

METHODS

The rs5743336 variant of NOD1 and rs2066847 variant of NOD2 were analysed by PCR-RFLP analysis in 200 subjects (T2DM: n = 100; healthy controls: n = 100) of Turkish origin. PCR products were digested with the AvaI and ApaI restriction enzymes. For the NOD1 site, the presence of the G allele was indicated by cleavage of the 379 bp amplified PCR product that yielded 209-bp and 170-bp fragments. For the NOD2 site, 151-bp PCR products were cleaved and yielded 130-bp and 21-bp fragments when the WT-insC mutation was present. Comparisons of the genotypes between controls and patients were performed by chi-square tests.

RESULTS AND DISCUSSION

The genotypes of the rs5743336 variant of NOD1 and the rs2066847 variant of NOD2 are presented, and no significant differences were observed in the genotype frequencies of the NOD1 and NOD2 variants between the healthy controls and T2DM patients (P > 0·05). According to our preliminary data, NOD1/2 gene variants are not linked with T2DM and IR.

WHAT IS NEW AND CONCLUSION

This study is the first to look for possible association of the genotype frequencies of NOD1 and NOD2 genes with T2DM and IR. The significant finding of this report is that the rs5743336 and rs2066847 variations in the NOD1/2 gene are not associated with T2DM and IR risk in patients of Turkish origin.

The Identification and Pharmacological Characterization of 6-(tert-Butylsulfonyl)-N-(5-fluoro-1H-indazol-3-yl)quinolin-4-amine (GSK583), a Highly Potent and Selective Inhibitor of RIP2 Kinase

RIP2 kinase is a central component of the innate immune system and enables downstream signaling following activation of the pattern recognition receptors NOD1 and NOD2, leading to the production of inflammatory cytokines. Recently, several inhibitors of RIP2 kinase have been disclosed that have contributed to the fundamental understanding of the role of RIP2 in this pathway. However, because they lack either broad kinase selectivity or strong affinity for RIP2, these tools have only limited utility to assess the role of RIP2 in complex environments. We present, herein, the discovery and pharmacological characterization of GSK583, a next-generation RIP2 inhibitor possessing exquisite selectivity and potency. Having demonstrated the pharmacological precision of this tool compound, we report its use in elucidating the role of RIP2 kinase in a variety of in vitro, in vivo, and ex vivo experiments, further clarifying our understanding of the role of RIP2 in NOD1 and NOD2 mediated disease pathogenesis.

Association of NOD1, CXCL16, STAT6 and TLR4 gene polymorphisms with Malaysian patients with Crohn's disease

Crohn's disease (CD) is a prominent type of inflammatory bowel disease (IBD) that can affect any part of the gastrointestinal tract. CD is known to have higher prevalence in the Western countries, but the number of cases has been increasing in the past decades in Asia, including Malaysia. Therefore, there is a need to investigate the underlining causes of CD that may shed light on its prevention and treatment. In this study, genetic polymorphisms in NOD1 (rs2075820), CXCL16 (rs2277680), STAT6 (rs324015) and TLR4 (rs4986791) genes were examined in a total of 335 individuals (85 CD patients and 250 healthy controls) with PCR-RFLP approach. There was no significant association observed between NOD1 rs2075820 and STAT6 rs324015 with the onset of CD in the studied cohort. However, the G allele of CXCL16 rs2277680 was found to have a weak association with CD patients (P = 0.0482; OR = 1.4310). The TLR4 rs4986791 was also significantly associated to CD. Both the homozygous C genotype (P = 0.0029; OR = 0.3611) and C allele (P = 0.0069; OR = 0.4369) were observed to confer protection against CD. On the other hand, the heterozygous C/T genotype was a risk genotype (P = 0.0015; OR = 3.1392). Further ethnic-stratified analysis showed that the significant associations in CXCL16 rs2277680 and TLR4 rs4986791 were accounted by the Malay cohort. In conclusion, the present study reported two CD-predisposing loci in the Malay CD patients. However, these loci were not associated to the onset of CD in Chinese and Indian patients.

Genetic variation in pattern recognition receptors: functional consequences and susceptibility to infectious disease

Cells of the innate immune system are equipped with surface and cytoplasmic receptors for microorganisms called pattern recognition receptors (PRRs). PRRs recognize specific pathogen-associated molecular patterns and as such are crucial for the activation of the immune system. Currently, five different classes of PRRs have been described: Toll-like receptors, C-type lectin receptors, nucleotide-binding oligomerization domain-like receptors, retinoic acid-inducible gene I-like receptors and absent in melanoma 2-like receptors. Following their discovery, many sequence variants in PRR genes have been uncovered and shown to be implicated in human infectious diseases. In this review, we will discuss the effect of genetic variation in PRRs and their signaling pathways on susceptibility to infectious diseases in humans.

Association of NOD1 and NOD2 polymorphisms with Guillain-Barré syndrome in Northern Indian population

BACKGROUND

Nucleotide oligomerization domain (NOD) proteins are cytosolic pattern recognition receptors that respond to bacterial substrate and induce NF-κB activation in host. Association of NOD polymorphisms have been studied in many autoimmune disorders, however its role in Guillain-Barré syndrome (GBS) remains unknown. We have investigated NOD1 Glu266Lys and NOD2 (Arg702Trp and Gly908Arg) gene polymorphisms among patients with GBS.

MATERIALS AND METHOD

Polymorphisms in NOD-1 (Glu266Lys) and NOD-2 (Arg702Trp and Gly908Arg) genes were studied using polymerase chain reaction-restriction fragment length polymorphism in 105 patients with GBS and 100 healthy controls.

RESULTS

Homozygous genotype (Lys/Lys) of NOD1 was significantly associated with GBS (p=0.013); and its subtypes viz. acute motor axonal neuropathy (AMAN) and acute inflammatory demyelinating polyneuropathy (AIDP) (p=0.008 and p=0.024 respectively) than controls. In NOD2 (Arg702Trp and Gly908Arg) polymorphisms, only heterozygous genotype (Arg/Trp and Gly/Arg) showed significant association with GBS (p=0.001 and p=0.01 respectively); subtypes AMAN, acute motor-sensory axonal neuropathy (AMSAN) and AIDP showed association with heterozygote Arg702Trp (p=0.001; p=0.029 and p=0.001 respectively) whereas only AIDP was associated with heterozygote genotype Gly908Arg (p=0.003).

CONCLUSION

NOD1 (Glu266Lys) and NOD2 (Arg702Trp and Gly908Arg) polymorphisms were associated with an increased susceptibility to GBS. These polymorphisms could be genetic marker to GBS susceptibility.

NOD-Like Receptors in Infection, Immunity, and Diseases

Nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) are pattern-recognition receptors similar to toll-like receptors (TLRs). While TLRs are transmembrane receptors, NLRs are cytoplasmic receptors that play a crucial role in the innate immune response by recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Based on their N-terminal domain, NLRs are divided into four subfamilies: NLRA, NLRB, NLRC, and NLRP. NLRs can also be divided into four broad functional categories: inflammasome assembly, signaling transduction, transcription activation, and autophagy. In addition to recognizing PAMPs and DAMPs, NLRs act as a key regulator of apoptosis and early development. Therefore, there are significant associations between NLRs and various diseases related to infection and immunity. NLR studies have recently begun to unveil the roles of NLRs in diseases such as gout, cryopyrin-associated periodic fever syndromes, and Crohn's disease. As these new associations between NRLs and diseases may improve our understanding of disease pathogenesis and lead to new approaches for the prevention and treatment of such diseases, NLRs are becoming increasingly relevant to clinicians. In this review, we provide a concise overview of NLRs and their role in infection, immunity, and disease, particularly from clinical perspectives.

NLRs: Nucleotide-Binding Domain and Leucine-Rich-Repeat-Containing Proteins

Eukaryotes have evolved strategies to detect microbial intrusion and instruct immune responses to limit damage from infection. Recognition of microbes and cellular damage relies on the detection of microbe-associated molecular patterns (MAMPs, also called PAMPS, or pathogen-associated molecular patterns) and so-called "danger signals" by various families of host pattern recognition receptors (PRRs). Members of the recently identified protein family of nucleotide-binding domain andleucine-rich-repeat-containing proteins (NLR), including Nod1, Nod2, NLRP3, and NLRC4, have been shown to detect specific microbial motifs and danger signals for regulating host inflammatory responses. Moreover, with the discovery that polymorphisms in NOD1, NOD2, NLRP1, and NLRP3 are associated with susceptibility to chronic inflammatory disorders, the view has emerged that NLRs act not only as sensors butalso can serve as signaling platforms for instructing and balancing host immune responses. In this chapter, we explore the functions of these intracellular innate immune receptors and examine their implication in inflammatory diseases.

Crystal structures of human RIP2 kinase catalytic domain complexed with ATP-competitive inhibitors: Foundations for understanding inhibitor selectivity

Receptor interacting protein 2 (RIP2) is an intracellular kinase and key signaling partner for the pattern recognition receptors NOD1 and NOD2 (nucleotide-binding oligomerization domain-containing proteins 1 and 2). As such, RIP2 represents an attractive target to probe the role of these pathways in disease. In an effort to design potent and selective inhibitors of RIP2 we established a crystallographic system and determined the structure of the RIP2 kinase domain in an apo form and also in complex with multiple inhibitors including AMP-PCP (β,γ-Methyleneadenosine 5'-triphosphate, a non-hydrolysable adenosine triphosphate mimic) and structurally diverse ATP competitive chemotypes identified via a high-throughput screening campaign. These structures represent the first set of diverse RIP2-inhibitor co-crystal structures and demonstrate that the protein possesses the ability to adopt multiple DFG-in as well as DFG-out and C-helix out conformations. These structures reveal key protein-inhibitor structural insights and serve as the foundation for establishing a robust structure-based drug design effort to identify both potent and highly selective inhibitors of RIP2 kinase.