Microbial sensing in the intestine

The gut microbiota plays a key role in host health and disease, particularly through their interactions with the immune system. Intestinal homeostasis is dependent on the symbiotic relationships between the host and the diverse gut microbiota, which is influenced by the highly co-evolved immune-microbiota interactions. The first step of the interaction between the host and the gut microbiota is the sensing of the gut microbes by the host immune system. In this review, we describe the cells of the host immune system and the proteins that sense the components and metabolites of the gut microbes. We further highlight the essential roles of pattern recognition receptors (PRRs), the G protein-coupled receptors (GPCRs), aryl hydrocarbon receptor (AHR) and the nuclear receptors expressed in the intestinal epithelial cells (IECs) and the intestine-resident immune cells. We also discuss the mechanisms by which the disruption of microbial sensing because of genetic or environmental factors causes human diseases such as the inflammatory bowel disease (IBD).

Nod-like receptor protein 3 inflammasome in head-and-neck cancer

Activation of inflammasomes has a decisive role in host defense mechanism against pathogens and other intracellular risk factors, but recently, it has been revealed that they play a significant role in the pathogenesis of several diseases, including cancer. Nod-like receptor protein 3 (NLRP3) inflammasome, the best-studied inflammasome, has contrasting roles in cancer development and progressions. In head-and-neck cancers, the upregulated level of NLRP3 promotes tumor progression. The main objective of this review is to provide current knowledge on the involvement of NLRP3 inflammasome in head-and-neck cancers. Deeper understanding of the biology of this dynamic protein complex provides new scope for the development of more effective anticancer therapies

Damage-Associated Molecular Patterns in Inflammatory Diseases

Damage-associated molecular patterns (DAMPs) are endogenous danger molecules that are released from damaged or dying cells and activate the innate immune system by interacting with pattern recognition receptors (PRRs). Although DAMPs contribute to the host's defense, they promote pathological inflammatory responses. Recent studies have suggested that various DAMPs, such as high-mobility group box 1 (HMGB1), S100 proteins, and heat shock proteins (HSPs), are increased and considered to have a pathogenic role in inflammatory diseases. Here, we review current research on the role of DAMPs in inflammatory diseases, including rheumatoid arthritis, systemic lupus erythematosus, osteoarthritis, atherosclerosis, Alzheimer's disease, Parkinson's disease, and cancer. We also discuss the possibility of DAMPs as biomarkers and therapeutic targets for these diseases.

Dual Effect of Hepatic Macrophages on Liver Ischemia and Reperfusion Injury during Liver Transplantation

Ischemia-reperfusion injury (IRI) is a major complication in liver transplantation (LT) and it is closely related to the recovery of grafts' function. Researches has verified that both innate and adaptive immune system are involved in the development of IRI and Kupffer cell (KC), the resident macrophages in the liver, play a pivotal role both in triggering and sustaining the sterile inflammation. Damage-associated molecular patterns (DAMPs), released by the initial dead cell because of the ischemia insult, firstly activate the KC through pattern recognition receptors (PRRs) such as toll-like receptors. Activated KCs is the dominant players in the IRI as it can secret various pro-inflammatory cytokines to exacerbate the injury and recruit other types of immune cells from the circulation. On the other hand, KCs can also serve in a contrary way to ameliorate IRI by upregulating the anti-inflammatory factors. Moreover, new standpoint has been put forward that KCs and macrophages from the circulation may function in different way to influence the inflammation. Managements towards KCs are expected to be the effective way to improve the IRI.

Advance in immune and inflammatory mechanisms of age-related macular degeneration / 眼科新进展

In recent years,the incidence of age-related macular degeneration (AMD) gradually increased,but the definite cause of AMD is still unclear,and the recent study have found that the immune and inflammation in retinal play an important role in the occurrence and development of AMD,so this article will give a brief review of the latest advances in immune and inflammatory mechanisms of AMD.

Roles of dexamethasone on nucleotide -binding oligomerization domain -like receptor 1 and 2 mRNA of asthma / 中国基层医药

Objective To investigate the potential roles of nucleotide -binding oligomerization domain (NOD)-like receptor in the pathogenesis of asthma.Methods Through rat asthma model,24 rats were randomly divided into three groups on average,named asthma group,control group and dexamethasone group.Expression levels of NOD1 and NOD2 mRNA were detected by Real -time PCR in lung tissues.Results The expression levels of NOD1 mRNA in the asthma group,control group and dexamethasone group were (0.62 ±0.34)RQ value,(1 .00 ± 0.00)RQ value,(0.65 ±0.33 )RQ value respectively.The levels of NOD1 mRNA in the asthma group was significantly lower than that in the control group(F =4.75,P 0.05).Moreover,expression levels of NOD2 mRNA in the asthma group,control group and dexamethasone group were (0.92 ±0.32)RQ value, (1 .00 ±0.00)RQ value,(1 .50 ±0.56)RQ value,respectively.There was no statistically significant difference of NOD2 mRNA level between the asthma group and control group (P >0.05 ),but level of NOD2 mRNA in the dexamethasone group was significantly higher than that in the asthma group(F =5.64,P 0.05).Conclusion Expression of NOD -like receptor subtype was not at the same level,and their reaction to dexamethasone were different either.

The roles of NOD1 and NOD2 in tumorigenesis and development / 中国生化药物杂志

Theinnate immunity system of human body has more and more attention for its antibacterial, antiviral, maintainingimmunehemostasis and promoting tissue damage and repair and other physiological functions.As members of NOD-like receptors(NLRs), NOD1 and NOD2 receptors are identified as intracellular pattern recognition receptors(PRRs), can be identified with molecular damage endogenous(damage-associated molecular patterns, DAMPs)and exogenous injury-molecular pathogen associated molecular(pathogen-associated molecular patterns, PAMPs), and initiation of innate and specific immune response, maintain the steady balance of body.Recently, a bunch of evidence have demonstrated that the importance of NOD1 receptor and NOD2 receptor is not limited in field of anti-infection, and the insulin resistance, kidney and liver damage recovery, cardiovascular disease and tumorigenesis are also closely related with these two receptors.So the aim of this article is to interpret the NOD1 and NOD2 general structure and function, and summarize the link between these two PRRs and tumorigenesis and finally make a clue for cancer immunotherapy.

Agaricus brasiliensis polysaccharides stimulate human monocytes to capture Candida albicans, express toll-like receptors 2 and 4, and produce pro-inflammatory cytokines

Abstract Background Agaricus brasiliensis is a medicinal mushroom with immunomodulatory and antitumor activities attributed to the -glucans presented in the polysaccharide fraction of its fruiting body. Since -glucans enhance cellular immunoresponsiveness, in this study we aimed to evaluate the effect of an acid-treated polysaccharide-rich fraction (ATF) of A. brasiliensis on the ability of human monocytes to adhere/phagocyte C. albicans yeast cells, their expression of pattern recognition receptors and their ability to produce cytokines. Methods Adhesion/phagocytosis of FITC-labeled C. albicans was evaluated by flow cytometry. Cells were incubated with specific fluorochrome-labeled antibodies for TLR2 and 4, GR and MR and also evaluated by flow cytometry. Monocytes were cultured with ATF, and culture supernatants were collected for analysis of in vitro cytokine production by ELISA (TNF-, IL-1, IL-12 and IL-10). Results ATF significantly increased the adherence/phagocytosis of C. albicans by monocytes and this was associated with enhanced expression of TLR2 and TLR4, while no effect was observed on GR or MR. Moreover, expression of TLR4 and TLR2 was associated with higher levels of in vitro production of TNF- and IL-1, respectively. Production of IL-10 was also increased by ATF treatment, but we found no association between its production and the expression of Toll-like receptors. Conclusion Our results provided us with evidence that A. brasiliensis polysaccharides affect human monocytes probably through the modulation of Toll-like receptors.

Agaricus brasiliensis polysaccharides stimulate human monocytes to capture Candida albicans, express toll-like receptors 2 and 4, and produce pro-inflammatory cytokines

Agaricus brasiliensis é um cogumelo medicinal com atividades imunomoduladoras e antitumorais atribuídas aos ß-glucanos presentes na fração polissacarídica de seu corpo de frutificação. Uma vez que os ß-glucanos aumentam a imunorresponsividade celular, neste estudo objetivamos avaliar o efeito de uma fração rica em polissacarídeos tratados com ácido (ATF) de A. brasiliensis sobre a capacidade de monócitos humanos de aderir / fagocitar células de levedura C. albicans . expressão de receptores de reconhecimento de padrões e sua capacidade de produzir citocinas. Métodos: A adesão / fagocitose de C. albicans marcada com FITC foi avaliada por citometria de fluxo. As células foram incubadas com anticorpos marcados com fluorocromo específicos para TLR2 e 4, ßGR e MR e também avaliadas por citometria de fluxo. Os monócitos foram cultivados com ATF, e os sobrenadantes da cultura foram coletados para análise da produção de citocinas in vitro por ELISA (TNF-α, IL-1ß, IL-12 e IL-10). Resultados: ATF aumentou significativamente a aderência / fagocitose de C. albicans por monócitos e isso foi associado com expressão aumentada de TLR2 e TLR4, enquanto nenhum efeito foi observado em ßGR ou MR. Além disso, a expressão de TLR4 e TLR2 foi associada a níveis mais elevados de produção in vitro de TNF-α e IL-1, respectivamente. A produção de IL-10 também foi aumentada pelo tratamento com ATF, mas não encontramos associação entre sua produção e a expressão de receptores Toll-like. Conclusão: Nossos resultados nos forneceram evidências de que polissacarídeos de A. brasiliensis afetam monócitos humanos provavelmente através da modulação de receptores Toll-like.(AU)

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.

Polyionic vaccine adjuvants: another look at aluminum salts and polyelectrolytes

Adjuvants improve the adaptive immune response to a vaccine antigen by modulating innate immunity or facilitating transport and presentation. The selection of an appropriate adjuvant has become vital as new vaccines trend toward narrower composition, expanded application, and improved safety. Functionally, adjuvants act directly or indirectly on antigen presenting cells (APCs) including dendritic cells (DCs) and are perceived as having molecular patterns associated either with pathogen invasion or endogenous cell damage (known as pathogen associated molecular patterns [PAMPs] and damage associated molecular patterns [DAMPs]), thereby initiating sensing and response pathways. PAMP-type adjuvants are ligands for toll-like receptors (TLRs) and can directly affect DCs to alter the strength, potency, speed, duration, bias, breadth, and scope of adaptive immunity. DAMP-type adjuvants signal via proinflammatory pathways and promote immune cell infiltration, antigen presentation, and effector cell maturation. This class of adjuvants includes mineral salts, oil emulsions, nanoparticles, and polyelectrolytes and comprises colloids and molecular assemblies exhibiting complex, heterogeneous structures. Today innovation in adjuvant technology is driven by rapidly expanding knowledge in immunology, cross-fertilization from other areas including systems biology and materials sciences, and regulatory requirements for quality, safety, efficacy and understanding as part of the vaccine product. Standardizations will aid efforts to better define and compare the structure, function and safety of adjuvants. This article briefly surveys the genesis of adjuvant technology and then re-examines polyionic macromolecules and polyelectrolyte materials, adjuvants currently not known to employ TLR. Specific updates are provided for aluminum-based formulations and polyelectrolytes as examples of improvements to the oldest and emerging classes of vaccine adjuvants in use.

La estimulación de TLR, receptores tipo NOD y dectina-1 en neutrófilos humanos induce la producción de citocinas proinflamatorias / Stimulation of TLRs, Nod-like receptors and Dectin-1 in neutrophils induces the production of proinflammatory cytokines

Objetivo: evaluar la expresión y la función de receptores de reconocimiento de patrones como los de tipo Toll y los de tipo NOD, RIG-I/MDA5, la dectina-1 y moléculas adaptadoras, en neutrófilos humanos. Métodos: a partir de sangre periférica de individuos sanos se purificaron y cultivaron neutrófilos en el medio RMPI-1640, en presencia o ausencia de los agonistas específicos de los receptores de interés. La expresión de los receptores de reconocimiento de patrones se determinó por RT-PCR y la secreción de citocinas proinflamatorias, por ELISA. Resultados: los neutrófilos expresan un amplio espectro de receptores de reconocimiento de patrones y de moléculas adaptadoras. La estimulación de TLR4, TLR5, TLR7/8 induce la secreción de IL-1β e IL-6; la activación de la dectina-1 induce una alta producción de TNF-α, pero bajos niveles de IL-1β e IL-6. Conclusión: los neutrófilos expresan un amplio número de receptores de reconocimiento de patrones y su activación lleva a la expresión de diferentes citocinas proinflamatorias.

Objective: To evaluate the expression and function of pattern recognition receptors such as Toll-like receptors, RIG-I/MDA5, NOD-like receptors, Dectin-1 and adaptor proteins, in human neutrophils. Methods: Neutrophils from peripheral blood of healthy individuals were purified and cultured in RPMI-1640, in the presence or absence of specific agonists of the receptor of interest. The expression of pattern recognition receptors was determined by RT-PCR and the secretion of proinflammatory cytokines, by ELISA. Results: We observed that neutrophils express diverse patterns recognition receptors and adaptor molecules. Stimulation of TLR4, TLR5 and TLR7/8 induces the production of IL-1β and IL-6, and activation of Dectin-1 leads to secretion of high levels of TNF-α, but low levels of IL-1β and IL-6. Conclusion: Neutrophils express a large number of pattern recognition receptors and their activation leads to the expression of proinflammatory cytokines.

Interaction among Toll-like recept ro s and other pattern recogni tion receptors in innate immune / 药学实践杂志

Toll-like receptors (TLRs) are germline-encoded pattern recognition receptors (PRRs) that play a central role in host cell recognition and responses to microbial pathogens .TLRs-mediated recognition of components derived from a wide range of pathogens and their role in the subsequent initiation of innate immune responses is widely accepted ,besides, the recent discovery of non-TLR PRRs, such as C-type lectin receptors, NOD-like receptors, and RIG-I-like receptors, suggests that many aspects of innate immunity are more sophisticated and complicated .In this review, we focused on the role cooperated by TLRs in mounting protective im-mune responses against infection and their crosstalk with other PRRs with respect to pathogen recognition .

Decreased Pattern-Recognition Receptor-Mediated Cytokine mRNA Expression in Obese Children With Otitis Media With Effusion

OBJECTIVES: To assess innate and humoral immune responses in middle ear effusion of obese pediatric patients with otitis media with effusion (OME). METHODS: We evaluated 219 children with OME, of whom 21 were obese and 198 were non-obese. We compared the expression in middle ear effusion of mRNAs encoding toll-like receptors (TLR) 2, 4, 5, and 9; nucleotide-binding oligomerization domains (NOD) 1 and 2; retinoic acid-inducible gene (RIG)-I; interleukins (IL)-6, -10, and -12; interferon (IFN)-gamma; and tumor necrosis factor (TNF)-alpha mRNAs. We also compared the expression of immunoglobulins IgG, IgA, and IgM and the bacterial detection rate in the two groups. RESULTS: TLR2-mediated expression of IL-6 mRNA, TLR4-mediated expression of IL-6 and IL-10 mRNA, TLR5-mediated expression of IL-6, IL-10, and TNF-alpha mRNA, TLR9-mediated expression of IL-6 mRNA, and NOD2-mediated expression of IL-6, IL-12, and TNF-alpha mRNA were significantly lower in obese than in non-obese children (P0.05). CONCLUSION: Mean body mass index was higher and pattern-recognition receptor-mediated cytokine mRNA expression was lower in obese than in non-obese children with OME.

Autophagy in Innate Recognition of Pathogens and Adaptive Immunity

Autophagy is a specialized cellular pathway involved in maintaining homeostasis by degrading long-lived cellular proteins and organelles. Recent studies have demonstrated that autophagy is utilized by immune systems to protect host cells from invading pathogens and regulate uncontrolled immune responses. During pathogen recognition, induction of autophagy by pattern recognition receptors leads to the promotion or inhibition of consequent signaling pathways. Furthermore, autophagy plays a role in the delivery of pathogen signatures in order to promote the recognition thereof by pattern recognition receptors. In addition to innate recognition, autophagy has been shown to facilitate MHC class II presentation of intracellular antigens to activate CD4 T cells. In this review, we describe the roles of autophagy in innate recognition of pathogens and adaptive immunity, such as antigen presentation, as well as the clinical relevance of autophagy in the treatment of human diseases.

Clinical Approaches for Understanding the Expression Levels of Pattern Recognition Receptors in Otitis Media with Effusion

OBJECTIVES: Bacterial infections in the normally sterile environment of the middle ear cavity usually trigger host immune response, whereby the innate immune system plays a dominant role as the host's first line of defense. We evaluated the expression levels of Toll-like receptors (TLRs) -2, -4, -5, -9, and nucleotide-binding oligomerization domain-containing proteins (NODs) -1 and -2, all of which are related to bacterial infection in pediatric patients with otitis media with effusion (OME). METHODS: The study sample consisted of 46 pediatric patients with OME, all of whom had ventilation tubes inserted. The expression levels of TLR-2, -4, -5, -9, NOD-1 and -2 mRNA in middle ear effusion were assessed by polymerase chain reaction (PCR). Difference of pattern recognition receptors (PRRs) expression level by presence of bacteria, ventilation tube insertion rate, and effusion fluid character was assessed. RESULTS: All effusion fluid samples collected from patients with OME showed expression of TLR-2, -4, -5, -9, NOD-1, and -2 mRNA by PCR. However, we found no differences among expression levels of PRRs in relation to characteristics of exudates, presence of bacteria, or frequencies of ventilation tube insertion (P>0.05). CONCLUSION: Our findings suggest that exudates of OME patients show PRR expressions that are related to the innate immune response regardless of the characteristics of effusion fluid, presence of bacteria in exudates, or frequency of ventilation tube insertion.

Recent advance in macrophage pattern recognition receptors for lipopolysaccharide recognition / 中国病理生理杂志

Sepsis is systemic inflammatory response syndrome(SIRS)associated with the presence of pathogenic microorganisms or their toxin.Lipopolysaccharide(LPS)is an important component of the outer membrane of Gram negative bacteria and has a pivotal role in inducing Gram negative sepsis.Macrophages play an essential role in infection and inflammation.Specific recognition of LPS is of particular importance in the defense system and pattern recognition receptors(PRR)have been considered to be important in initial steps for cellular recognition of LPS and consequence initiation of LPS responses.In the past few years,intense research in the fields of PRR and their recognition mechanism has been achieved.In this review,we attempt to expound recent research advances of macrophage PRRs for LPS recognition and their mechanism.