Nod-like receptors in innate immunity and inflammatory diseases

Astragalus membranaceus as a Drug Candidate for Inflammatory Bowel Disease: The Preclinical Evidence

Inflammatory bowel disease (IBD) is a group of chronic inflammatory disorders that include Crohn's disease (CD) and ulcerative colitis (UC). Today, IBD has no successful treatment. As a result, it is of paramount importance to develop novel therapeutic agents for IBD prevention and treatment. Astragalus membranaceus (AMS) is a traditional Chinese medicine found in the AMS root. Modern pharmacological studies indicate that AMS and its constituents exhibit multiple bioactivities, such as anti-inflammatory, anti-oxidant, immune regulatory, anticancer, hypolipidemic, hypoglycemic, hepatoprotective, expectorant, and diuretic effects. AMS and its active constituents, which have been reported to be effective in IBD treatment, are believed to be viable candidate drugs for IBD treatment. These underlying mechanisms are associated with anti-inflammation, anti-oxidation, immunomodulation, intestinal epithelial repair, gut microbiota homeostasis, and improved energy metabolism. In this review, we summarize the efficacy and underlying mechanisms involved in IBD treatment with AMS and its active constituents in preclinical studies.

High-throughput data on circular RNA reveal novel insights into chronic glomerulonephritis

BACKGROUND

Circular RNAs (circRNAs), a unique novel type of RNA, have been widely reported to be involved in physiologic and pathologic processes in humans. However, the exact molecular pathogenesis of circRNAs in chronic glomerulonephritis (CGN) is far from clear.

OBJECTIVE

This paper aims to evaluate the specific expression profile of circRNAs in renal cortex tissues from Adriamycin-induced CGN rats.

METHODS

CircRNAs were screened in renal cortex tissues from 3 CGN rats and 3 control rats by using high-throughput sequencing (HTS). Then, 4 circRNAs were selected randomly for verification by quantitative real-time polymerase chain reaction (qRT-PCR). In addition, the differentially expressed (DE) circRNAs were analyzed by bioinformatics methods.

RESULTS

In total, 31 significantly DE circRNAs were identified, which revealed their potential roles in CGN; in particular, we found that 4 confirmed altered circRNAs (rno-circ-RNAs 689, 3217, 1327, and 5001) might play important roles in the development of CGN.

CONCLUSION

This study reveals a cluster of circRNAs that are DE in Adriamycin-induced CGN rats, which brings us closer to understanding the pathogenic mechanisms and may provide new potential targets for clinical treatment.

Host and Species-Specificities of Pattern Recognition Receptors Upon Infection With Leptospira interrogans

Leptospirosis is a zoonotic infectious disease affecting all vertebrates. It is caused by species of the genus Leptospira, among which are the highly pathogenic L. interrogans. Different mammals can be either resistant or susceptible to the disease which can present a large variety of symptoms. Humans are mostly asymptomatic after infection but can have in some cases symptoms varying from a flu-like syndrome to more severe forms such as Weil’s disease, potentially leading to multiorgan failure and death. Similarly, cattle, pigs, and horses can suffer from acute forms of the disease, including morbidity, abortion, and uveitis. On the other hand, mice and rats are resistant to leptospirosis despite chronical colonization of the kidneys, excreting leptospires in urine and contributing to the transmission of the bacteria. To this date, the immune mechanisms that determine the severity of the infection and that confer susceptibility to leptospirosis remain enigmatic. To our interest, differential immune sensing of leptospires through the activation of or escape from pattern recognition receptors (PRRs) by microbe-associated molecular patterns (MAMPs) has recently been described. In this review, we will summarize these findings that suggest that in various hosts, leptospires differentially escape recognition by some Toll-like and NOD-like receptors, including TLR4, TLR5, and NOD1, although TLR2 and NLRP3 responses are conserved independently of the host. Overall, we hypothesize that these innate immune mechanisms could play a role in determining host susceptibility to leptospirosis and suggest a central, yet complex, role for TLR4.

Mitochondrial Quality Control and Restraining Innate Immunity

Maintaining mitochondrial health is essential for the survival and function of eukaryotic organisms. Misfunctioning mitochondria activate stress-responsive pathways to restore mitochondrial network homeostasis, remove damaged or toxic proteins, and eliminate damaged organelles via selective autophagy of mitochondria, a process termed mitophagy. Failure of these quality control pathways is implicated in the pathogenesis of Parkinson's disease and other neurodegenerative diseases. Impairment of mitochondrial quality control has been demonstrated to activate innate immune pathways, including inflammasome-mediated signaling and the antiviral cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING)-regulated interferon response. Immune system malfunction is a common hallmark in many neurodegenerative diseases; however, whether inflammation suppresses or exacerbates disease pathology is still unclear. The goal of this review is to provide a historical overview of the field, describe mechanisms of mitochondrial quality control, and highlight recent advances on the emerging role of mitochondria in innate immunity and inflammation.

Network pharmacology approach to decipher signaling pathways associated with target proteins of NSAIDs against COVID-19

Non-steroidal anti-inflammatory drugs (NSAIDs) showed promising clinical efficacy toward COVID-19 (Coronavirus disease 2019) patients as potent painkillers and anti-inflammatory agents. However, the prospective anti-COVID-19 mechanisms of NSAIDs are not evidently exposed. Therefore, we intended to decipher the most influential NSAIDs candidate(s) and its novel mechanism(s) against COVID-19 by network pharmacology. FDA (U.S. Food & Drug Administration) approved NSAIDs (19 active drugs and one prodrug) were used for this study. Target proteins related to selected NSAIDs and COVID-19 related target proteins were identified by the Similarity Ensemble Approach, Swiss Target Prediction, and PubChem databases, respectively. Venn diagram identified overlapping target proteins between NSAIDs and COVID-19 related target proteins. The interactive networking between NSAIDs and overlapping target proteins was analyzed by STRING. RStudio plotted the bubble chart of the KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway enrichment analysis of overlapping target proteins. Finally, the binding affinity of NSAIDs against target proteins was determined through molecular docking test (MDT). Geneset enrichment analysis exhibited 26 signaling pathways against COVID-19. Inhibition of proinflammatory stimuli of tissues and/or cells by inactivating the RAS signaling pathway was identified as the key anti-COVID-19 mechanism of NSAIDs. Besides, MAPK8, MAPK10, and BAD target proteins were explored as the associated target proteins of the RAS. Among twenty NSAIDs, 6MNA, Rofecoxib, and Indomethacin revealed promising binding affinity with the highest docking score against three identified target proteins, respectively. Overall, our proposed three NSAIDs (6MNA, Rofecoxib, and Indomethacin) might block the RAS by inactivating its associated target proteins, thus may alleviate excessive inflammation induced by SARS-CoV-2.

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.

Host-microbiota interactions and responses to grass carp reovirus infection in Ctenopharyngodon idellus

Gut microbiota could facilitate host to defense diseases, but fish-microbiota interactions during viral infection and the underlying mechanism are poorly understood. We examined interactions and responses of gut microbiota to grass carp reovirus (GCRV) infection in Ctenopharyngodon idellus, which is the most important aquaculture fish worldwide. We found that GCRV infection group with serious haemorrhagic symptoms (G7s) showed considerably different gut microbiota, especially with an abnormally high abundance of gram-negative anaerobic Cetobacterium somerae. It also showed the lowest (p < 0.05) alpha-diversity but with much higher ecological process of homogenizing dispersal (28.8%), confirming a dysbiosis of the gut microbiota after viral infection. Interestingly, signaling pathways of NOD-like receptors (NLRs), toll-like receptors (TLRs), and lipopolysaccharide (LPS) stimulation genes were significantly (q-value < 0.01) enriched in G7s, which also significantly (p < 0.01) correlated with the core gut microbial genera of Cetobacterium and Acinetobacter. The results suggested that an expansion of C. somerae initiated by GCRV could aggravate host inflammatory reactions through the LPS-related NLRs and TLRs pathways. This study advances our understanding of the interplay between fish immunity and gut microbiota challenged by viruses; it also sheds new insights for ecological defense of fish diseases with the help of gut microbiota.

The function of NOD-like receptors in central nervous system diseases

NOD-like receptors (NLRs) are critical cytoplasmic pattern-recognition receptors (PRRs) that play an important role in the host innate immune response and immunity homeostasis. There is a growing body of evidence that NLRs are involved in a wide range of inflammatory diseases, including cancer, metabolic diseases, and autoimmune disorders. Recent studies have indicated that the proteins of the NLR family are linked with the pathophysiology of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS), and psychological diseases. In this review, we mainly focus on the role of NLRs and the underlying signaling pathways in central nervous system (CNS) diseases. © 2016 Wiley Periodicals, Inc.

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.

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.

Genetic Variations of NLR family genes in Behcet's Disease

This study aimed to investigate whether single nucleotide polymorphisms (SNPs) of five NLR family genes (NOD1, NOD2, NLRP1, NLRP3 and CIITA) are associated with Behcet’s disease (BD) in a Chinese Han population. The study was carried out in 950 BD patients and 1440 controls for 19 SNPs in the selected NLR genes. In the first-stage study, significantly decreased frequencies of the CIITA//rs12932187 C allele (Pc = 1.668E-02) and NOD1//rs2075818 G allele (Pc = 4.694E-02) were found in BD patients as compared to controls . After performing a second stage validation study and combination of data we confirmed the association of CIITA//rs12932187 and NOD1//rs2075818 with BD. In CIITA//rs12932187, the frequencies of the CC genotype and C allele were significantly lower in BD than in controls (Pc = 3.331E-06; Pc = 6.004E-07, respectively). In NOD1//rs2075818, the GG genotype and G allele showed significantly decreased frequencies in BD patients when compared to controls (Pc = 1.022E-02; Pc = 6.811E-05, respectively). Functional experiments showed that carriers with the CC genotype in CIITA//rs12932187 had a lower CIITA mRNA expression level and an enhanced IL-10 secretion as compared to GG and CG carriers. This study provides evidence that the CIITA and NOD1 gene are involved in the susceptibility to Behcet’s disease.

Occult spondyloarthritis in inflammatory bowel disease

Spondyloarthritis (SpA) is a frequent extra-intestinal manifestation in patients with inflammatory bowel disease (IBD), although its real diffusion is commonly considered underestimated. Abnormalities in the microbioma and genetic predisposition have been implicated in the link between bowel and joint inflammation. Otherwise, up to date, pathogenetic mechanisms are still largely unknown and the exact influence of the bowel activity on rheumatic manifestations is not clearly explained. Due to evidence-based results of clinical studies, the interest on clinically asymptomatic SpA in IBD patients increased in the last few years. Actually, occult enthesitis and sacroiliitis are discovered in high percentages of IBD patients by different imaging techniques, mainly enthesis ultrasound (US) and sacroiliac joint X-ray examinations. Several diagnostic approaches and biomarkers have been proposed in an attempt to correctly classify and diagnose clinically occult joint manifestations and to define clusters of risk for patient screening, although definitive results are still lacking. The correct recognition of occult SpA in IBD requires an integrated multidisciplinary approach in order to identify common diagnostic and therapeutic strategies. The use of inexpensive and rapid imaging techniques, such as US and X-ray, should be routinely included in daily clinical practice and trials to correctly evaluate occult SpA, thus preventing future disability and worsening of quality of life in IBD patients.

Sirt1 restrains lung inflammasome activation in a murine model of sepsis

Excessive inflammation is a major cause of organ damage during sepsis. The elderly are highly susceptible to sepsis-induced organ injury. Sirt1 expression is reduced during aging. In the present study, we investigated the role of Sirt1, a histone deacetylase, in controlling inflammatory responses in a murine sepsis model induced by cecal ligation and puncture (CLP). We examined lung inflammatory signaling in inducible Sirt1 knockout (Sirt1(-/-)) mice and wild-type littermates (Sirt1(+/+)) after CLP. Our results demonstrated that Sirt1 deficiency led to severe lung inflammatory injury. To further investigate molecular mechanisms of Sirt1 regulation of lung inflammatory responses in sepsis, we conducted a series of experiments to assess lung inflammasome activation after CLP. We detected increased lung inflammatory signaling including NF-κB, signal transducer and activator of transcription 3, and ERK1/2 activation in Sirt1(-/-) mice after CLP. Furthermore, inflammasome activity was increased in Sirt1(-/-) mice after CLP, as demonstrated by increased IL-1β and caspase-7 cleavage and activation. Aggravated inflammasome activation in Sirt1(-/-) mice was associated with the increased production of lung proinflammatory mediators, including ICAM-1 and high-mobility group box 1, and further disruption of tight junctions and adherens junctions, as demonstrated by dramatic reduction of lung claudin-1 and vascular endothelial-cadherin expression, which was associated with the upregulation of matrix metallopeptidase 9 expression. In summary, our results suggest that Sirt1 suppresses acute lung inflammation during sepsis by controlling inflammasome activation pathway.

The NLR-related protein NWD1 is associated with prostate cancer and modulates androgen receptor signaling

Prostate cancer (PCa) is among the leading causes of cancer-related death in men. Androgen receptor (AR) signaling plays a seminal role in prostate development and homeostasis, and dysregulation of this pathway is intimately linked to prostate cancer pathogenesis and progression. Here, we identify the cytosolic NLR-related protein NWD1 as a novel modulator of AR signaling. We determined that expression of NWD1 becomes elevated during prostate cancer progression, based on analysis of primary tumor specimens. Experiments with cultured cells showed that NWD1 expression is up-regulated by the sex-determining region Y (SRY) family proteins. Gene silencing procedures, in conjunction with transcriptional profiling, showed that NWD1 is required for expression of PDEF (prostate-derived Ets factor), which is known to bind and co-regulate AR. Of note, NWD1 modulates AR protein levels. Depleting NWD1 in PCa cell lines reduces AR levels and suppresses activity of androgen-driven reporter genes. NWD1 knockdown potently suppressed growth of androgen-dependent LNCaP prostate cancer cells, thus showing its functional importance in an AR-dependent tumor cell model. Proteomic analysis suggested that NWD1 associates with various molecular chaperones commonly related to AR complexes. Altogether, these data suggest a role for tumor-associated over-expression of NWD1 in dysregulation of AR signaling in PCa.

Synthesis and physicochemical characterization of novel phenotypic probes targeting the nuclear factor-kappa B signaling pathway

Activation of nuclear factor-kappa B (NF-κB) and related upstream signal transduction pathways have long been associated with the pathogenesis of a variety of inflammatory diseases and has recently been implicated in the onset of cancer. This report provides a synthetic and compound-based property summary of five pathway-related small-molecule chemical probes identified and optimized within the National Institutes of Health-Molecular Libraries Probe Center Network (NIH-MLPCN) initiative. The chemical probes discussed herein represent first-in-class, non-kinase-based modulators of the NF-κB signaling pathway, which were identified and optimized through either cellular phenotypic or specific protein-target-based screening strategies. Accordingly, the resulting new chemical probes may allow for better fundamental understanding of this highly complex biochemical signaling network and could advance future therapeutic translation toward the clinical setting.

Association between genetic polymorphisms of NOD 1 and Helicobacter pylori-induced gastric mucosal inflammation in healthy Korean population

BACKGROUND

Gastric cancer is supposed to be a result of inflammation induced by Helicobacter pylori (H. pylori) infection. Nucleotide-binding oligomerization domain 1 (NOD 1) is required for the innate immune response to H. pylori. We aim to investigate whether single nucleotide polymorphism (SNP) in NOD 1 gene is associated with H. pylori-induced gastric mucosal inflammation in a healthy Korean population.

METHODS

The study was conducted on 412 adults who visited two different healthcare centers for health examinations. The G796A (E266K) NOD 1 SNP was detected by using polymerase chain reaction/restriction fragment length polymorphism. A gastritis score was calculated by the summed values of the grade and the activity of gastritis scored according to the updated Sydney system. The expression of IL-8 and COX-2 mRNA was assessed by quantitative reverse transcription polymerase chain reaction. In the group with H. pylori infection, the complete screening of the genes comprising the cag PAI was performed.

RESULTS

The genotype frequencies were 26.7% (AA type), 58.3% (GA), and 15.0% (GG). In H. pylori-positive patients, gastritis score of the AA genotype was significantly higher than those of the others (p = .04). Also, the IL-8 and COX-2 mRNA levels increased in the AA genotype. In the group with H. pylori infection, 31.9% were found to carry the complete cag PAI. When the subjects were infected with intact cag PAI, the IL-8 and COX-2 mRNA levels were significantly high in AA genotype.

CONCLUSION

G796A (E266K) NOD 1 polymorphism is closely correlated with H. pylori-associated gastric mucosal inflammation in the Korean population.

Roles of NOD1 (NLRC1) and NOD2 (NLRC2) in innate immunity and inflammatory diseases

NOD1 {nucleotide-binding oligomerization domain 1; NLRC [NOD-LRR (leucine-rich repeat) family with CARD (caspase recruitment domain) 1]} and NOD2 (NLRC2) are among the most prominent members of the NLR (NOD-LRR) family –proteins that contain nucleotide-binding NACHT domains and receptor-like LRR domains. With over 20 members identified in humans, NLRs represent important components of the mammalian innate immune system, serving as intracellular receptors for pathogens and for endogenous molecules elaborated by tissue injury. NOD1 and NOD2 proteins operate as microbial sensors through the recognition of specific PG (peptidoglycan) constituents of bacteria. Upon activation, these NLR family members initiate signal transduction mechanisms that include stimulation of NF-κB (nuclear factor-κB), stress kinases, IRFs (interferon regulatory factors) and autophagy. Hereditary polymorphisms in the genes encoding NOD1 and NOD2 have been associated with an increasing number of chronic inflammatory diseases. In fact, potential roles for NOD1 and NOD2 in inflammatory disorders have been revealed by investigations using a series of animal models. In the present review, we describe recent experimental findings associating NOD1 and NOD2 with various autoimmune and chronic inflammatory disorders, and we discuss prospects for development of novel therapeutics targeting these NLR family proteins.

Network analysis of transcriptional responses induced by mesenchymal stem cell treatment of experimental sepsis

Although bone marrow-derived mesenchymal stem cell (MSC) systemic administration reduces sepsis-associated inflammation, organ injury, and mortality in clinically relevant models of polymicrobial sepsis, the cellular and molecular mechanisms mediating beneficial effects are controversial. This study identifies the molecular mechanisms of MSC-conferred protection in sepsis by interrogating transcriptional responses of target organs to MSC therapy. Sepsis was induced in C57Bl/6J mice by cecal ligation and puncture, followed 6 hours later by an i.v. injection of either MSCs or saline. Total RNA from lungs, hearts, kidneys, livers, and spleens harvested 28 hours after cecal ligation and puncture was hybridized to mouse expression bead arrays. Common transcriptional responses were analyzed using a network knowledge-based approach. A total of 4751 genes were significantly changed between placebo- and MSC-treated mice (adjusted P ≤ 0.05). Transcriptional responses identified three common effects of MSC administration in all five organs examined: i) attenuation of sepsis-induced mitochondrial-related functional derangement, ii down-regulation of endotoxin/Toll-like receptor innate immune proinflammatory transcriptional responses, and iii) coordinated expression of transcriptional programs implicated in the preservation of endothelial/vascular integrity. Transcriptomic analysis indicates that the protective effect of MSC therapy in sepsis is not limited to a single mediator or pathway but involves a range of complementary activities affecting biological networks playing critical roles in the control of host cell metabolism and inflammatory response.

The biodiversity hypothesis and allergic disease: world allergy organization position statement

Biodiversity loss and climate change secondary to human activities are now being associated with various adverse health effects. However, less attention is being paid to the effects of biodiversity loss on environmental and commensal (indigenous) microbiotas. Metagenomic and other studies of healthy and diseased individuals reveal that reduced biodiversity and alterations in the composition of the gut and skin microbiota are associated with various inflammatory conditions, including asthma, allergic and inflammatory bowel diseases (IBD), type1 diabetes, and obesity. Altered indigenous microbiota and the general microbial deprivation characterizing the lifestyle of urban people in affluent countries appear to be risk factors for immune dysregulation and impaired tolerance. The risk is further enhanced by physical inactivity and a western diet poor in fresh fruit and vegetables, which may act in synergy with dysbiosis of the gut flora. Studies of immigrants moving from non-affluent to affluent regions indicate that tolerance mechanisms can rapidly become impaired in microbe-poor environments. The data on microbial deprivation and immune dysfunction as they relate to biodiversity loss are evaluated in this Statement of World Allergy Organization (WAO). We propose that biodiversity, the variability among living organisms from all sources are closely related, at both the macro- and micro-levels. Loss of the macrodiversity is associated with shrinking of the microdiversity, which is associated with alterations of the indigenous microbiota. Data on behavioural means to induce tolerance are outlined and a proposal made for a Global Allergy Plan to prevent and reduce the global allergy burden for affected individuals and the societies in which they live.

Advances in research of fish immune-relevant genes: a comparative overview of innate and adaptive immunity in teleosts

Fish is considered to be an important model in comparative immunology studies because it is a representative population of lower vertebrates serving as an essential link to early vertebrate evolution. Fish immune-relevant genes have received considerable attention due to its role in improving understanding of both fish immunology and the evolution of immune systems. In this review, we discuss the current understanding of teleost immune-relevant genes for both innate and adaptive immunity, including pattern recognition receptors, antimicrobial peptides, complement molecules, lectins, interferons and signaling factors, inflammatory cytokines, chemokines, adaptive immunity relevant cytokines and negative regulators, major histocompatibility complexes, immunoglobulins, and costimulatory molecules. The implications of these factors on the evolutionary history of immune systems were discussed and a perspective outline of innate and adaptive immunity of teleost fish was described. This review may provide clues on the evolution of the essential defense system in vertebrates.

Adjuvants for Leishmania vaccines: from models to clinical application

Two million new cases of leishmaniasis occur every year, with the cutaneous leishmaniasis (CL) presentation accounting for approximately two-thirds of all cases. Despite the high incidence rates and geographic expansion of the disease, CL remains a neglected tropical disease without effective intervention strategies. Efforts to address this deficit have given rise to the experimental murine model of CL. By virtue of its simplicity and pliability, the CL model has been used to provide substantial information regarding cellular immunity, as well as in the discovery and evaluation of various vaccine adjuvants. The CL model has facilitated in vivo studies of the mechanism of action of many adjuvants, including the TLR4 agonist monophosphoryl lipid A, the TLR7/8 agonist imiquimod, the TLR9 agonist CpG, adenoviral vectors, and the immunostimulatory complexes. Together, these studies have helped to unveil the requirement for certain types of immune responses at specific stages of CL disease and provide a basis to aid the design of effective second-generation vaccines for human CL. This review focuses on adjuvants that have been tested in experimental CL, outlining how they have helped advance our understanding of the disease and ultimately, how they have performed when applied within clinical trials against human CL.

Pathogen recognition receptors in channel catfish: I. Identification, phylogeny and expression of NOD-like receptors

Innate immune system plays a significant role in all multicellular organisms. The key feature of the system is its ability to recognize and respond to invading microorganisms. Vertebrates including teleost fish have evolved an array of pathogen recognition receptors (PRRs) for detecting and responding to various pathogen-associated molecular patterns (PAMPs), including Toll-like receptors (TLRs), nucleotide-binding domain, leucine-rich repeat containing receptors (NLRs), and the retinoic acid inducible gene I (RIG-I) like receptors (RLRs). In this study, we identified 22 NLRs including six members of the NLR-A subfamily (NODs), two members of the NLR-B subfamily, 11 members of the NLR-C subfamily, and three genes that do not belong to any of these three subfamilies: Apaf1, CIITA, and NACHT-P1. Phylogenetic analysis indicated that orthologs of the mammalian NOD1, NOD2, NOD3, NOD4, and NOD5 were all identified in catfish. In addition, an additional truncated NOD3-like gene was also identified in catfish. While the identities of subfamily A NLRs could be established, the identities of the NLR-B and NLR-C subfamilies were inconclusive at present. Expression of representative NLR genes was analyzed using RT-PCR and qRT-PCR. In healthy catfish tissues, all the tested NLR genes were found to be ubiquitously expressed in all 11 tested catfish tissues. Analysis of expression of these representative NLR genes after bacterial infection with Edwardsiella ictaluri revealed a significant up-regulation of all tested genes in the spleen and liver, but a significant down-regulation in the intestine and head kidney, suggesting their involvement in the immune responses of catfish against the intracellular bacterial pathogen in a tissue-specific manner. The up-regulation and down-regulation of the tested genes exhibited an amazing similarity of expression profiles after infection, suggesting the co-regulation of these genes.

Identification of Inhibitors of NOD1-Induced Nuclear Factor-κB Activation

NOD1 (nucleotide-binding oligomerization domain 1) protein is a member of the NLR (NACHT and leucine rich repeat domain containing proteins) protein family, which plays a key role in innate immunity as a sensor of specific microbial components derived from bacterial peptidoglycans and induction of inflammatory responses. Mutations in NOD proteins have been associated with various inflammatory diseases that affect NF-κB (nuclear factor κB) activity, a major signaling pathway involved in apoptosis, inflammation, and immune response. A luciferase-based reporter gene assay was utilized in a high-throughput screening program conducted under the NIH-sponsored Molecular Libraries Probe Production Center Network program to identify the active scaffolds. Herein, we report the chemical synthesis, structure-activity relationship studies, downstream counterscreens, secondary assay data, and pharmacological profiling of the 2-aminobenzimidazole lead (compound 1c, ML130) as a potent and selective inhibitor of NOD1-induced NF-κB activation.

Current concepts and future directions in the pathogenesis and treatment of non-infectious intraocular inflammation

The blockbuster drug paradigm is under increasing scrutiny across the biopharmaceutical industry. Intraocular inflammation poses particular challenges to this, given the heterogeneity of conditions in the uveitis spectrum, and the increasing acknowledgement of individual patient and disease variance in underlying immune responses. This need has triggered a drive towards personalised and stratified medicine, supported and enabled as a result of continued development of both experimental models and molecular biological techniques and improved clinical classification. As such we have the ability now to systematically appraise at a genomic, transcriptomic, and proteomic level individual immunophenotype, and the promise that in the eye this can be augmented by in vivo immune imaging to identify individual immunopathology. With such advances all running in parallel, we are entering an era of experimental medicine that will facilitate early diagnosis, generate biomarkers for accurate prognostication, and enable the development of individualised and targeted therapies, which can progress rapidly into clinical practice.

The macrophage pattern recognition scavenger receptors SR-A and CD36 protect against microbial induced pregnancy loss

OBJECTIVES AND DESIGN

Microbial products can act via stress-induced signaling cascades to link dysregulated endogenous microbiota to immune activation (e.g., macrophages) and pregnancy loss. Our previous studies demonstrated that mice deficient in the macrophage pattern recognition scavenger receptors, SR-A and CD36, are more susceptible to inflammatory complications including gut leakiness and experimental colitis. We hypothesized that bacterial penetration of the maternal mucosal surfaces and replication in embryonic fluids compromise the fetal status and can result in miscarriage.

MATERIALS AND METHODS

Eighty pregnant ICR and SR-A/CD36-deficient mice were injected via tail vein or intraperitoneally with commensal bacteria (Streptococcus cricetus and/or Actinobacillus sp.) or sham controls. Dams were monitored daily for physical distress, pain and abortion.

RESULTS

Dams injected with single dose bacterial inoculum did not develop clinical symptoms. Day old pups injected with bacteria developed internal focal abscesses, lost weight but recovered after 1 week. Dams receiving a second bacterial inoculum delivered dead fetuses. However, SR-A/CD36-deficnet dams demonstrated 100% fetal death via aborted fetuses, and significant up-regulation of the proinflammatory markers (IL-6, serum Amyloid A) 24-74 h after single inoculum.

CONCLUSIONS

These data indicate that macrophage scavenger receptors are required for the fetal protection against microbial attack and support that maternal transfer of innate immunity contributes to this protection.

Effects of NOD-like receptors in human B lymphocytes and crosstalk between NOD1/NOD2 and Toll-like receptors

NLRs are recently discovered PRRs detecting substructures of peptidoglycans and triggering innate immunity. NLRs are expressed in several cell types, but the presence in human B lymphocytes is still unknown. This study aimed to investigate expression and function of NLRs in human B lymphocytes. B cells were isolated and analyzed for mRNA and protein expression. The functional responsiveness of NOD1 and NOD2 was investigated upon stimulation with the cognate ligands, with or without stimulation via IgM/IgD/CD40 and/or selected TLR agonists. A differential expression of NLRs was demonstrated in blood-derived and tonsillar B cells, whereas no variations were found among naive, germinal center, or memory B cells. Stimulation with the ligands alone did not induce B cell activation. However, upon concomitant BCR triggering, an increase in proliferation was seen, together with an induction of cell surface markers (CD27, CD69, CD71, CD80, CD86, and CD95) and prolonged survival. Peripheral B cells were activated by NOD1 and NOD2 ligands, whereas tonsil-derived B cells responded solely to NOD1. In contrast, costimulation with CD40L failed to induce activation. Additionally, it was found that NLR ligands could enhance TLR-induced proliferation of B cells. The present study demonstrates expression of functional NLRs in human B cells. We show that NOD1 and NOD2 have the ability to augment the BCR-induced activation independently of physical T cell help. Hence, NLRs represent a new pathway for B cell activation and a potentially important host defense system against bacterial infections.

The joint-gut axis in inflammatory bowel diseases

Inflammatory bowel diseases, Crohn's disease and ulcerative colitis, are associated with a variety of extraintestinal manifestations. The most common extraintestinal manifestation, articular involvement, occurs in 16% to 33% of inflammatory bowel disease patients. These arthropathies may increase morbidity, resulting in a worse quality of life compared with inflammatory bowel disease patients without arthropathies. Thus, arthropathies in inflammatory bowel diseases represent a major medical problem in these patients. Arthritis associated with inflammatory bowel diseases is one of the diseases captured under the umbrella of spondyloarthritis. Spondyloarthritis is a group of inflammatory diseases with overlapping features and is linked to Human Leukocyte Antigen-B27. Arthropathy in inflammatory bowel diseases is clinically divided into peripheral and axial involvement. Peripheral arthritis often flares with relapses of bowel disease resulting in a different treatment approach than axial arthritis in which the course is independent of inflammatory bowel disease activity. Definitions, prevalence, pathophysiology and treatment of the arthropathies commonly seen in inflammatory bowel diseases such as peripheral arthritis, dactylitis, enthesitis, arthralgia, sacroiliitis, inflammatory back pain and ankylosing spondylitis are summarized.

Innate instruction of adaptive immunity revisited: the inflammasome

The innate immune system regulates initial responses to pathogen invasion through a set of conserved pattern recognition receptors (PRR). The best-characterized PRRs are the Toll-like receptors, which regulate not only the initial pathogen defense response, but also adaptive immune responses. Thus, insight into the function of PRRs has major implications for our understanding of the physiology of vaccination and the pathophysiology of human disease. Recent advances in our understanding of a new class of pattern recognition receptors--NOD-like receptors (NLR)--have similarly provided insight into both innate and adaptive immunity. In particular, the NLR Nlrp3 (also known as Nalp3 or Cias1) forms an intracellular multimolecular complex with active caspase-1, called an inflammasome, creating a platform for regulating secretion of interleukin-1 (IL-1) family members. Given the important role of IL-1 in inflammatory diseases, from gout to rheumatoid arthritis, the importance of understanding the regulation of such a cytokine cannot be underestimated. In this review, we address new evidence supporting a role for adaptive immune activation by recently identified NLR agonists, with a particular focus on Nlrp3. Basic questions in our understanding of Nlrp3 inflammasome activation are also presented.

Brevetoxin 2 alters expression of apoptotic, DNA damage, and cytokine genes in Jurkat cells

Brevetoxins are potent neurotoxins that exert their toxicity through activation of voltage-gated sodium channels. Exposure to brevetoxins cause severe respiratory inflammation in marine mammals and humans. Brevetoxin activation of voltage-gated sodium channels on immune cells can lead to several biological responses including cell proliferation, gene transcription, cytokine production and even apoptosis. Jurkat E6-1 T cells were treated with brevetoxin 2 for 4 hours at a dose previously shown to induce apoptosis and DNA damage. Changes in gene expression were then assessed via PCR arrays. Gene expression analysis revealed significant change in expression of 17 genes related to apoptosis, 21 genes related to DNA damage signaling, and 19 genes encoding common cytokines. The gene expression data supports the idea that brevetoxins trigger complex reactions involving both inflammation and cell death.

The genetics of NOD-like receptors in Crohn's disease

The first Crohn's disease (CD) susceptibility gene identified was CARD15, which is a member of the emerging NOD-like receptor (NLR) family. These function as intracellular cystosolic pattern recognition receptors (PRRs) and play a central role in the innate immune response. We studied other members of the NLR family using a gene-wide haplotype tagging approach in a well-characterised collection of 547 CD patients and 465 controls. Four single nucleotide polymorphisms (SNPs) in NLRP3 had P values < 0.05 and are in high linkage disequilibrium (LD) with each other (r(2) > 0.90 for all four SNPs). rs4925648 and rs10925019 were the most strongly associated with CD susceptibility (P = 0.001, odds ratio (OR) 1.62, 95% CI 1.2-2.18; and P = 6.5 x 10(-4), OR 1.65, 95% CI 1.23-2.19, respectively). rs1363758 located in NLRP11 was associated with CD susceptibility [P = 0.002 (1.64, 1.19-2.25)], which was weakly confirmed in an independent case-cohort collection on joint analysis [P = 0.05, (1.28, 1-1.64)]. On sub-phenotype analysis, an interesting association between NLRP1 and skin extra-intestinal manifestations and colonic, inflammatory CD was identified. None of these results was replicated in the Wellcome Trust Case Control Consortium study and therefore need replication in a further large cohort.

Adjuvants for malaria vaccines

There is a renewed enthusiasm about subunit vaccines for malaria coincident with the formation of new alliances and partnerships raising international public awareness, attracting increased resources and the re-focusing of research programs on adjuvant development for infectious disease vaccines. It is generally accepted that subunit vaccines for malaria will require adjuvants to induce protective immune responses, and availability of suitable adjuvants has in the past been a barrier to the development of malaria vaccines. Several novel adjuvants are now in licensed products or in late stage clinical development, while several others are in the earlier development pipeline. Successful vaccine development requires knowing which adjuvants to use and knowing how to formulate adjuvants and antigens to achieve stable, safe, and immunogenic vaccines. For the majority of vaccine researchers this information is not readily available, nor is access to well-characterized adjuvants. In this minireview, we outline the current state of adjuvant research and development as it pertains to effective malaria vaccines.

NOD-like subfamily of the nucleotide-binding domain and leucine-rich repeat containing family receptors and their expression in channel catfish

The NLRs (nucleotide-binding domain and leucine-rich repeat containing family receptors) are a recently identified family of pattern recognition receptors in vertebrates. Several subfamilies of NLRs have been characterized in human, mouse, and zebrafish, but studies of NLRs in other species, especially teleost species, have been lacking. Here we report characterization of five NLRs from channel catfish: NOD1, NOD2, NLRC3, NLRC5, and NLRX1. Structural analysis indicated that the genes were organized in a similar fashion as in the mammals and in zebrafish. Phylogenetic analysis suggested that they were orthologous to the NOD-like subfamily of NLRs. All five NOD-like genes exist as a single copy gene in the catfish genome. Hybridization of gene-specific probes allowed mapping of three NLR genes to the catfish physical map, laying a foundation for genome characterization and for establishing orthologies with NLR genes from other species. These genes are widely expressed in various tissues and leukocyte cell lines. While the majority of the NLR genes appeared to be constitutively expressed, NOD1 was induced after infection with a bacterial pathogen, Edwardsiella ictaluri, the causative agent of enteric septicemia of catfish (ESC), suggesting its involvement in immunity against the intracellular pathogen.

Activation of NOD2-mediated intestinal pathway in a pediatric population with Crohn's disease

BACKGROUND

NOD2 is an intracellular protein involved in host recognition of specific bacterial molecules and is genetically associated with several inflammatory diseases, including Crohn's disease (CD). NOD2 stimulation activates the transcription factor, NF-kappaB, through RIP2, a caspase-recruitment domain-containing kinase. NOD2/RIP2 signaling also mediates the activation of antimicrobial peptides such as human alpha-defensin 5 (HD-5) and human alpha-defensin 6 (HD-6), both produced by Paneth cells. The present study is aimed at describing the downstream events triggered specifically by NOD2 induction in order to demonstrate that the protein, other than overexpressed, is also physiologically associated with RIP2 and Erbin in the bioptic intestinal inflamed specimens of children affected by CD.

METHODS

Fifteen children with CD and 10 children used as controls were entered in the study. Mucosal biopsy specimens were taken during endoscopy and mRNA and protein expressions were detected by using real-time polymerase chain reaction and Western blot.

RESULTS

NOD2 is able to form an immunocomplex with the kinase RIP2. As compared to controls, in the inflamed mucosa of patients both mRNA and protein expression levels of RIP2 are increased, and its active phosphorylated form is overexpressed.

CONCLUSIONS

In this study we provide for the first time ex vivo evidence of physiologically relevant protein interactions with NOD2, which are able to trigger the innate immune response in intestinal mucosal specimens of children with CD.

A novel mutation in the NOD2 gene associated with Blau syndrome: a Norwegian family with four affected members

BACKGROUND

Blau syndrome is a chronic granulomatous disease with an autosomal dominant trait characterized by the triad granulomatous dermatitis, arthritis, and uveitis. It is caused by mutations in the NOD2 gene, also termed the CARD15 gene.

OBJECTIVE

To report a novel mutation in the NOD2 gene associated with Blau syndrome.

METHODS AND RESULTS

The proband was a 68-year-old ethnic Norwegian male who had uveitis and arthritis since 10 years of age followed by lifelong recurrent arthritis and chronic eye involvement. Genetic analysis showed a heterozygous c.1814 C>A, T605N mutation in NOD2 that has not previously been described. All of his three children had Blau syndrome and had inherited the NOD2 mutation. The proband's first son had exanthema, arthritis, and uveitis from 10 years of age and later presented with granulomatous lymphadenopathy, granulomatous parotitis, and granulomatous intestinal inflammation. The proband's daughter had arthritis, uveitis, and exanthema from 3 years of age. The proband's second son had uveitis, exanthema, and arthritis from 1.5 years of age. None of the cases had any involvement of the heart or lungs.

CONCLUSION

We report a novel Blau syndrome-associated mutation with an autosomal dominant heritage. Most likely the mutation has arisen de novo in the proband. Genetic counselling and antenatal diagnostics should be available to the involved families.

Scientific rationale for the Finnish Allergy Programme 2008-2018: emphasis on prevention and endorsing tolerance

In similarity to many other western countries, the burden of allergic diseases in Finland is high. Studies worldwide have shown that an environment rich in microbes in early life reduces the subsequent risk of developing allergic diseases. Along with urbanization, such exposure has dramatically reduced, both in terms of diversity and quantity. Continuous stimulation of the immune system by environmental saprophytes via the skin, respiratory tract and gut appears to be necessary for activation of the regulatory network including regulatory T-cells and dendritic cells. Substantial evidence now shows that the balance between allergy and tolerance is dependent on regulatory T-cells. Tolerance induced by allergen-specific regulatory T-cells appears to be the normal immunological response to allergens in non atopic healthy individuals. Healthy subjects have an intact functional allergen-specific regulatory T-cell response, which in allergic subjects is impaired. Evidence on this exists with respect to atopic dermatitis, contact dermatitis, allergic rhinitis and asthma. Restoration of impaired allergen-specific regulatory T-cell response and tolerance induction has furthermore been demonstrated during allergen-specific subcutaneous and sublingual immunotherapy and is crucial for good therapeutic outcome. However, tolerance can also be strengthened unspecifically by simple means, e.g. by consuming farm milk and spending time in nature. Results so far obtained from animal models indicate that it is possible to restore tolerance by administering the allergen in certain circumstances both locally and systemically. It has become increasingly clear that continuous exposure to microbial antigens as well as allergens in foodstuffs and the environment is decisive, and excessive antigen avoidance can be harmful and weaken or even prevent the development of regulatory mechanisms. Success in the Finnish Asthma Programme was an encouraging example of how it is possible to reduce both the costs and morbidity of asthma. The time, in the wake of the Asthma Programme, is now opportune for a national allergy programme, particularly as in the past few years, fundamentally more essential data on tolerance and its mechanisms have been published. In this review, the scientific rationale for the Finnish Allergy Programme 2008-2018 is outlined. The focus is on tolerance and how to endorse tolerance at the population level.

New horizons in adjuvants for vaccine development

Over the last decade, there has been a flurry of research on adjuvants for vaccines, and several novel adjuvants are now in licensed products or in late stage clinical development. The success of adjuvants in enhancing the immune response to recombinant antigens has led many researchers to re-focus their vaccine development programs. Successful vaccine development requires knowing which adjuvants to use and knowing how to formulate adjuvants and antigens to achieve stable, safe and immunogenic vaccines. For the majority of vaccine researchers this information is not readily available, nor is access to well-characterized adjuvants. In this review, we outline the current state of adjuvant research and development and how formulation parameters can influence the effectiveness of adjuvants.

NOD-like receptors and inflammation

The nucleotide-binding and oligomerization domain, leucine-rich repeat (also known as NOD-like receptors, both abbreviated to NLR) family of intracellular pathogen recognition receptors are increasingly being recognized to play a pivotal role in the pathogenesis of a number of rare monogenic diseases, as well as some more common polygenic conditions. Bacterial wall constituents and other cellular stressor molecules are recognized by a range of NLRs, which leads to activation of the innate immune response and upregulation of key proinflammatory pathways, such as IL-1beta production and translocation of nuclear factor-kappaB to the nucleus. These signalling pathways are increasingly being targeted as potential sites for new therapies. This review discusses the role played by NLRs in a variety of inflammatory diseases and describes the remarkable success to date of these therapeutic agents in treating some of the disorders associated with aberrant NLR function.

How can calcium pyrophosphate crystals induce inflammation in hypophosphatasia or chronic inflammatory joint diseases?

Hypophosphatasia (HP) is a rare inborn error of bone and mineral metabolism characterized by a defect in the tissue non-specific alkaline phosphatase (TNSALP) gene. Calcium pyrophosphate dihydrate (CPPD) crystals are known to accumulate as substrates of TNSALP in tissues and joints of patients with HP. In CPPD-induced arthritis these crystals are known to induce an inflammatory response. HP patients do suffer from pain in their lower extremities. However, it is not clear whether CPPD crystals contribute to these musculoskeletal complaints in HP. As long as there is no curative treatment of HP, symptomatic treatment in order to improve clinical features, especially with regard to pain and physical activity, is of major interest to the patients. Knowledge of the mechanisms underlying crystal-induced cell activation, however, is limited. Here we describe recent advances in elucidating the signal transduction pathways activated by CPPD crystals as endogenous "danger signals". Recent investigations provided evidence that Toll/interleukin-1 receptor (TIR) domain containing receptors including Toll-like receptors (TLRs) and interleukin-1 receptor (IL-1R), as well as the triggering receptor expressed on myeloid cells 1 (TREM-1) and the NACHT-leucin rich repeat and pyrin-domain-containing protein (NALP3) containing inflammasome are essentially involved in acute CPPD crystal-induced inflammation. These receptors are considered in part as components of the innate immune system. Further studies are needed to improve our understanding of the pathophysiological mechanisms leading to inflammation and tissue destruction associated with deposition of microcrystals. They might support the development of new therapeutic strategies for crystal-induced inflammation. Eventually, patients with HP might as well profit from such strategies addressing these metabolic disorders secondary to the gene defect.