ZBP1 Protects Against mtDNA-Induced Myocardial Inflammation in Failing Hearts.

BACKGROUND: Mitochondrial DNA (mtDNA)-induced myocardial inflammation is intimately involved in cardiac remodeling. ZBP1 (Z-DNA binding protein 1) is a pattern recognition receptor positively regulating inflammation in response to mtDNA in inflammatory cells, fibroblasts, and endothelial cells. However, the role of ZBP1 in myocardial inflammation and cardiac remodeling remains unclear. The aim of this study was to elucidate the role of ZBP1 in mtDNA-induced inflammation in cardiomyocytes and failing hearts. METHODS: mtDNA was administrated into isolated cardiomyocytes. Myocardial infarctionwas conducted in wild type and ZBP1 knockout mice. RESULTS: We here found that, unlike in macrophages, ZBP1 knockdown unexpectedly exacerbated mtDNA-induced inflammation such as increases in IL (interleukin)-1ß and IL-6, accompanied by increases in RIPK3 (receptor interacting protein kinase 3), phosphorylated NF-κB (nuclear factor-κB), and NLRP3 (nucleotide-binding domain and leucine-rich-repeat family pyrin domain containing 3) in cardiomyocytes. RIPK3 knockdown canceled further increases in phosphorylated NF-κB, NLRP3, IL-1ß, and IL-6 by ZBP1 knockdown in cardiomyocytes in response to mtDNA. Furthermore, NF-κB knockdown suppressed such increases in NLRP3, IL-1ß, and IL-6 by ZBP1 knockdown in response to mtDNA. CpG-oligodeoxynucleotide, a Toll-like receptor 9 stimulator, increased RIPK3, IL-1ß, and IL-6 and ZBP1 knockdown exacerbated them. Dloop, a component of mtDNA, but not Tert and B2m, components of nuclear DNA, was increased in cytosolic fraction from noninfarcted region of mouse hearts after myocardial infarction compared with control hearts. Consistent with this change, ZBP1, RIPK3, phosphorylated NF-κB, NLRP3, IL-1ß, and IL-6 were increased in failing hearts. ZBP1 knockout mice exacerbated left ventricular dilatation and dysfunction after myocardial infarction, accompanied by further increases in RIPK3, phosphorylated NF-κB, NLRP3, IL-1ß, and IL-6. In histological analysis, ZBP1 knockout increased interstitial fibrosis and myocardial apoptosis in failing hearts. CONCLUSIONS: Our study reveals unexpected protective roles of ZBP1 against cardiac remodeling as an endogenous suppressor of mtDNA-induced myocardial inflammation.

AIM2 in health and disease: Inflammasome and beyond.

Nucleic acid sensing is a critical mechanism by which the immune system monitors for pathogen invasion. A set of germline-encoded innate immune receptors detect microbial DNA in various compartments of the cell, such as endosomes, the cytosol, and the nucleus. Sensing of microbial DNA through these receptors stimulates, in most cases, interferon regulatory factor-dependent type I IFN synthesis followed by JAK/STAT-dependent interferon-stimulated gene expression. In contrast, the detection of DNA in the cytosol by AIM2 assembles a macromolecular complex called the inflammasome, which unleashes the proteolytic activity of a cysteine protease caspase-1. Caspase-1 cleaves and activates the pro-inflammatory cytokines such as IL-1ß and IL-18 and a pore-forming protein, gasdermin D, which triggers pyroptosis, an inflammatory form of cell death. Research over the past decade has revealed that AIM2 plays essential roles not only in host defense against pathogens but also in inflammatory diseases, autoimmunity, and cancer in inflammasome-dependent and inflammasome-independent manners. This review discusses the latest advancements in our understanding of AIM2 biology and its functions in health and disease.

Autophagy limits activation of the inflammasomes.

Inflammasomes are multiprotein complexes that control the maturation and production of interleukin-1 family members and play crucial roles in host defense against pathogens. However, dysregulated activation of inflammasomes is associated with intense inflammation, leading to the development of inflammatory diseases. Therefore, inflammasomes must be activated at a proper strength to protect against infection and avoid tissue damage. Recent studies have highlighted the cross-talk between inflammasome activation and autophagy, the cellular machinery associated with the degradation of intracellular components and maintenance of cellular homeostasis. Notably, deficiencies in autophagy-related proteins induce the aberrant activation of inflammasomes, causing severe tissue damage. In contrast, autophagy inducers ameliorate symptoms of inflammasome-related diseases. In this review, we discuss recent advances in the involvement of autophagy in regulating inflammasomes activation and in the development of inflammatory diseases.

The intra- and extracellular functions of ASC specks.

Inflammasomes are the central signaling hubs of the inflammatory response. They process cytosolic evidence of infection, cell damage, or metabolic disturbances, and elicit a pro-inflammatory response mediated by members of the interleukin-1 family of cytokines and pyroptotoic cell death. On the molecular level, this is accomplished by the sensor-nucleated recruitment and oligomerization of the adapter protein ASC. Once a tunable threshold is reached, cooperative assembly of ASC into linear filaments and their condensation into macromolecular ASC specks promotes an all-or-none response. These structures are highly regulated and provide a unique signaling platform or compartment to control the activity of caspase-1 and likely other effectors. Emerging evidence indicates that ASC specks are also released from inflammasome-activated cells and accumulate in inflamed tissues, where they can continue to mature cytokines or be internalized by surrounding cells to further nucleate ASC specks in their cytosol. Little is known about the mechanisms governing ASC speck release, uptake, and endosomal escape, as well as its contribution to inflammation and disease. Here, we describe the different outcomes of inflammasome activation and discuss the potential function of extracellular ASC specks. We highlight gaps in our understanding of this central process of inflammation, which may have direct consequences on the modulation of host responses and chronic inflammation.

The many ways tissue phagocytes respond to dying cells.

Apoptosis is an important component of normal tissue physiology, and the prompt removal of apoptotic cells is equally essential to avoid the undesirable consequences of their accumulation and disintegration. Professional phagocytes are highly specialized for engulfing apoptotic cells. The recent ability to track cells that have undergone apoptosis in situ has revealed a division of labor among the tissue resident phagocytes that sample them. Macrophages are uniquely programmed to process internalized apoptotic cell-derived fatty acids, cholesterol and nucleotides, as a reflection of their dominant role in clearing the bulk of apoptotic cells. Dendritic cells carry apoptotic cells to lymph nodes where they signal the emergence and expansion of highly suppressive regulatory CD4 T cells. A broad suppression of inflammation is executed through distinct phagocyte-specific mechanisms. A clever induction of negative regulatory nodes is notable in dendritic cells serving to simultaneously shut down multiple pathways of inflammation. Several of the genes and pathways modulated in phagocytes in response to apoptotic cells have been linked to chronic inflammatory and autoimmune diseases such as atherosclerosis, inflammatory bowel disease and systemic lupus erythematosus. Our collective understanding of old and new phagocyte functions after apoptotic cell phagocytosis demonstrates the enormity of ways to mediate immune suppression and enforce tissue homeostasis.

Dysregulated cellular functions and cell stress pathways provide critical cues for activating and targeting natural killer cells to transformed and infected cells.

Natural killer (NK) cells recognize and kill cancer cells and infected cells by engaging cell surface ligands that are induced preferentially or exclusively on these cells. These ligands are recognized by activating receptors on NK cells, such as NKG2D. In addition to activation by cell surface ligands, the acquisition of optimal effector activity by NK cells is driven in vivo by cytokines and other signals. This review addresses a developing theme in NK cell biology: that NK-activating ligands on cells, and the provision of cytokines and other signals that drive high effector function in NK cells, are driven by abnormalities that arise from transformation or the infected state. The pathways include genomic damage, which causes self DNA to be exposed in the cytosol of affected cells, where it activates the DNA sensor cGAS. The resulting signaling induces NKG2D ligands and also mobilizes NK cell activation. Other key pathways that regulate NKG2D ligands include PI-3 kinase activation, histone acetylation, and the integrated stress response. This review summarizes the roles of these pathways and their relevance in both viral infections and cancer.

The comings and goings of MHC class I molecules herald a new dawn in cross-presentation.

MHC class I (MHC-I) molecules are the centerpieces of cross-presentation. They are loaded with peptides derived from exogenous sources and displayed on the plasma membrane to communicate with CD8 T cells, relaying a message of tolerance or attack. The study of cross-presentation has been focused on the relative contributions of the vacuolar versus cytosolic pathways of antigen processing and the location where MHC-I molecules are loaded. While vacuolar processing generates peptides loaded onto vacuolar MHC-I molecules, how and where exogenous peptides generated by the proteasome and transported by TAP meet MHC-I molecules for loading has been a matter of debate. The source and trafficking of MHC-I molecules in dendritic cells have largely been ignored under the expectation that these molecules came from the Endoplasmic reticulum (ER) or the plasma membrane. New studies reveal a concentrated pool of MHC-I molecules in the endocytic recycling compartment (ERC). These pools are rapidly mobilized to phagosomes carrying microbial antigens, and in a signal-dependent manner under the control of Toll-like receptors. The phagosome becomes a dynamic hub receiving traffic from multiple sources, the ER-Golgi intermediate compartment for delivering the peptide-loading machinery and the ERC for deploying MHC-I molecules that alert CD8 T cells of infection.

Bacterial recognition pathways that lead to inflammasome activation.

Inflammasomes are multi-protein signaling platforms that upon activation trigger the maturation of the pro-inflammatory cytokines, interleukin-1ß (IL-1ß) and IL-18, and cell death. Inflammasome sensors detect microbial and host-derived molecules. Here, we review the mechanisms of inflammasome activation triggered by bacterial infection, primarily focusing on two model intracellular bacterial pathogens, Francisella novicida and Salmonella typhimurium. We discuss the complex relationship between bacterial recognition through direct and indirect detection by inflammasome sensors. We highlight regulation mechanisms that potentiate or limit inflammasome activation. We discuss the importance of caspase-1 and caspase-11 in host defense, and we examine the downstream consequences of inflammasome activation within the context of bacterial infections.

The cooperation between the autophagy machinery and the inflammasome to implement an appropriate innate immune response: do they regulate each other?

Autophagy is originally described as the main catabolic pathway responsible for maintaining intracellular nutritional homeostasis that involves the formation of a unique vacuole, the autophagosome, and the interaction with the endosome-lysosome pathways. This conserved machinery plays a key role in immune-protection against different invaders, including pathogenic bacteria, intracellular parasites, and some viruses like herpes simplex and hepatitis C virus. Importantly, autophagy is linked to a number of human diseases and disorders including neurodegenerative disease, Crohn's disease, type II diabetes, tumorigenesis, cardiomyopathy, and fatty liver disease. On the other hand, inflammasomes are multiprotein platforms stimulated upon several environmental conditions and microbial infection. Once assembled, the inflammasomes mediate the maturation of pro-inflammatory cytokines and promote phagosome-lysosome fusion to sustain an innate immune response. The intersections between autophagy and inflammasome have been observed in various diseases and microbial infections. This review highlights the molecular aspects involved in autophagy and inflammasome interactions during different medical conditions and microbial infections.

Genetic Variation in TLR10, an Inhibitory Toll-Like Receptor, Influences Susceptibility to Complicated Skin and Skin Structure Infections.

BACKGROUND: Toll-like receptors (TLRs) play a central role in the innate immune response to complicated skin and skin structure infections (cSSSIs), with TLR10 being the first family member known to have an inhibitory function. This study assessed the role of TLR10 in recognition of cSSSI-related pathogens and whether genetic variation in TLR10 influences susceptibility to cSSSIs. METHODS: Human peripheral blood mononuclear cells (PBMCs) preincubated with anti-TLR10 antibody and HEK-293 cells overexpressing TLRs were exposed to cSSSI pathogens, and cytokine secretion was determined by enzyme-linked immunosorbent assay. A total of 318 patients with cSSSI and 328 healthy controls were genotyped for 4 nonsynonymous single-nucleotide polymorphisms in TLR10, and functional consequences of the TLR10 SNPs were assessed via in vitro stimulation assays. RESULTS: PBMC stimulation with cSSSI pathogens in the presence of TLR10 neutralizing antibody significantly increased interleukin 6 secretion. Overexpression of TLR10 completely abrogated TLR2-induced interleukin 8 secretion by HEK-293 cells in response to cSSSI pathogens. Three polymorphisms in TLR10, I775L, I369L, and N241H, were associated with reduced susceptibility to cSSSIs. The presence of the TLR10 alleles 775L, 369L, or 241H increased interleukin 6 secretion by PBMCs in response to cSSSI pathogens. CONCLUSIONS: TLR10 is a modulatory receptor of innate immune responses to cSSSI-related pathogens, and genetic variants in TLR10 are associated with protection against cSSSIs.

TLR1, TLR2, and TLR6 gene polymorphisms are associated with increased susceptibility to complicated skin and skin structure infections.

BACKGROUND: Complicated skin and skin structure infections (cSSSIs) are characterized by infections with gram-positive or gram-negative aerobic or anaerobic bacteria, as well as by a polymicrobial etiology. These invading microorganisms are recognized by pattern-recognition receptors (PRRs) of the innate immune system. This study assessed whether genetic variation in genes encoding PRRs influences the susceptibility to cSSSIs. METHODS: A total of 318 patients with cSSSI and 328 healthy controls were genotyped for 9 nonsynonymous single-nucleotide polymorphisms (SNPs) in PRR genes coding for Toll-like receptors (TLRs) 1, 2, 4, and 6; NOD-like receptor 2; and the signaling adaptor molecule TIRAP. Associations between susceptibility to cSSSIs and a SNP were investigated by means of logistic regression models. In an additional cohort of 74 healthy individuals in whom the same SNPs were genotyped, peripheral blood mononuclear cells (PBMCs) were obtained and stimulated with Staphylococcus aureus. Interleukin 6 concentrations were determined in supernatants by enzyme-linked immunosorbent assay to determine the correlation between genotypes and levels of IL-6 secretion. RESULTS: In the genetic association analysis, polymorphisms in TLR1 (S248N and R80T), TLR2 (P631H), and TLR6 (P249S) were associated with an increased susceptibility to cSSSIs. No association with susceptibility to cSSSIs was observed for polymorphisms TLR2 (R753Q), TLR4 (D299G and T399I), NOD2 (P268S), and TIRAP (S180L). In the functional analysis, individuals bearing the TLR1 248N or 80T allele showed lower IL-6 secretion upon stimulation with S. aureus. CONCLUSIONS: Polymorphisms in TLR1, TLR2, and TLR6 are associated with increased susceptibility to cSSSIs. For TLR1, impaired proinflammatory cytokine production due to the polymorphism is most likely the mechanism mediating this effect.

The Role of Damage-Associated Molecular Patterns in Human Diseases: Part I - Promoting inflammation and immunity.

There is increasing interest by physicians in the impact of the innate immune system on human diseases. In particular, the role of the molecules that initiate and amplify innate immune pathways, namely damage-associated molecular patterns (DAMPs), is of interest as these molecules are involved in the pathogenesis of many human disorders. The first part of this review identifies five classes of cell stress/tissue injury-induced DAMPs that are sensed by various recognition receptor-bearing cells of the innate immune system, thereby mounting inflammation, promoting apoptosis and shaping adaptive immune responses. The DAMPs activate and orchestrate several innate immune machineries, including inflammasomes and the unfolded protein response that synergistically operates to induce inflammatory, metabolic and adaptive immune pathologies. Two examples of autoimmune diseases are discussed as they represent a typical paradigm of the intimate interplay between innate and adaptive immune responses.

The Role of Damage-Associated Molecular Patterns (DAMPs) in Human Diseases: Part II: DAMPs as diagnostics, prognostics and therapeutics in clinical medicine.

This article is the second part of a review that addresses the role of damage-associated molecular patterns (DAMPs) in human diseases by presenting examples of traumatic (systemic inflammatory response syndrome), cardiovascular (myocardial infarction), metabolic (type 2 diabetes mellitus), neurodegenerative (Alzheimer's disease), malignant and infectious diseases. Various DAMPs are involved in the pathogenesis of all these diseases as they activate innate immune machineries including the unfolded protein response and inflammasomes. These subsequently promote sterile autoinflammation accompanied, at least in part, by subsequent adaptive autoimmune processes. This review article discusses the future role of DAMPs in routine practical medicine by highlighting the possibility of harnessing and deploying DAMPs either as biomarkers for the appropriate diagnosis and prognosis of diseases, as therapeutics in the treatment of tumours or as vaccine adjuncts for the prophylaxis of infections. In addition, this article examines the potential for developing strategies aimed at mitigating DAMPs-mediated hyperinflammatory responses, such as those seen in systemic inflammatory response syndrome associated with multiple organ failure.

Inflammatory mechanisms of ischemic stroke / 国际脑血管病杂志

Inflammation plays an important role in the pathophysiological process of ischemic stroke.This article elaborates the inflammatory response process after ischemic stroke in order to improve the understanding of the pathophysiological mechanisms of ischemic stroke.

Role of DNA recognition receptors in pathogenic mechanism of hepatitis B / 临床肝胆病杂志

As a global disease,hepatitis B still threatens human health.However,the pathogenesis of hepatitis caused by HBV remains unclear.The innate immune system in the liver can detect HBV infection and use every strategy to eliminate the virus.DNA recognition receptors play an important role in this process;they recognize tlBV DNA or pgRNA in cytoplasm or nucleus,activate innate immunity through various signaling pathways to produce inflammatory cytokines and interferon,and finally exert their antiviral effect.This article summarizes the DNA recognition receptors involved in inflammation induced by HBV and HBV clearance,elaborates on their detailed pathways,and discusses the issues regarding the role of DNA recognition receptors in liver innate immunity induced by HBV and related perspectives.

Role of DNA recognition receptors in pathogenic mechanism of hepatitis B / 临床肝胆病杂志

As a global disease,hepatitis B still threatens human health.However,the pathogenesis of hepatitis caused by HBV remains unclear.The innate immune system in the liver can detect HBV infection and use every strategy to eliminate the virus.DNA recognition receptors play an important role in this process;they recognize tlBV DNA or pgRNA in cytoplasm or nucleus,activate innate immunity through various signaling pathways to produce inflammatory cytokines and interferon,and finally exert their antiviral effect.This article summarizes the DNA recognition receptors involved in inflammation induced by HBV and HBV clearance,elaborates on their detailed pathways,and discusses the issues regarding the role of DNA recognition receptors in liver innate immunity induced by HBV and related perspectives.

In vitro binding ability of transglutaminase 3 to dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin / 中华皮肤科杂志

Objective To evaluate the recognition and uptake of transglutaminase 3 (TG3) by dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) receptors on the membrane surface of DC-SIGN-transfected human embryonic kidney (HEK) 293T cells and monocytederived dendritic cells (MDDCs).Methods The eukaryotic expression vector pGCMV-enhanced green fluorescent protein (EGFP) containing DC-SIGN gene fragments was transfected into HEK293T cells to prepare DC-SIGN-EGFP-HEK293T cells by using liposome transfection method.CD14+ monocytes were isolated from peripheral blood samples by magnetic bead-based negative selection,and then were induced by granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-4 (IL-4) to prepare MDDCs.Laser confocal microscopy and flow cytometry were performed to evaluate the recognition and uptake of TG3 protein by DC-SIGN receptors on the surface of HEK293T cells and MDDCs.MDDCs treated without Alexa Fluor 647 dye-tagged TG3 served as blank control group,and those treated with Alexa Fluor 647 dye alone served as negative control group.Results After co-culture with TG3 for 3 hours,laser confocal microscopy and flow cytometry both showed that TG3 could be recognized by and uptaken through DC-SIGN receptors into HEK293T cells and MDDCs.Flow cytometry also revealed that the binding of TG3 to MDDCs could be partially blocked by DC-SIGN blocking antibodies.Neither the negative control group nor the blank control group showed the recognition and binding of TG3 to HEK293T cells and MDDCs.Conclusion TG3 can serve as a kind of autoantigen to be recognized and bound by DC-SIGN receptors,followed by uptake by dendritic cells.

Establishment and functional analysis of a cell model expressing the C-type lectin receptor Langerin / 中华皮肤科杂志

Objective To establish a cell model expressing the Langerhans cell-specific C type lectin receptor Langerin in vitro.Methods The cDNA of Langerin was obtained by PCR and cloned into a eukauotic green fluorescent protein (EGFP) expression vector pEGFP-C 1 with EGFP located in the N terminal region of the Langerin gene.Then,the recombinant plasmid was transfected into a human embryonic kidney carcinoma cell line HEK293T.Subsequently,laser confocal microscopy was performed to observe the expression of EGFP-Langerin fusion protein,and flow cytometry to measure the expression of Langerin.Laser confocal microscopy was also conducted to visualize the recognition and endocytosis of dust mite antigen (nDer p 2) by Langerin.Results PCR and Western blot confirmed the successful transfection of HEK293T cells with the recombinant plasmid as well as the expression of Langerin in the transfected cells.As flow cytometry revealed,the expression level of Langerin in transfected HEK293T cells was increased by 43％ compared with untransfected cells.Laser confocal microscopy showed that green fluorescein-labeled Langerin was successfully expressed,and could bind to and endocytose the red fluorescein-labeled antigen nDer p 2.Conclusions The fusion protein EGFP-Langerin expressed in HEK293T cells showed the distribution characteristic of cell surface receptors,and could bind to and endocytose allergens.

The regulation mechanism of RIG-Ⅰ-like receptors in antiviral innate immune responses / 军事医学科学院院刊

Immune and tissue cells usually express pattern-recognition receptors (PRRs) to detect viruses and other microorganisms, thereby inducing signal cascade amplification and host innate immune responses. Since PRRs have strain-specific substrates and mechanisms of recognition, the identification of PRRs and mechanisms of PRRs-mediated responses is highly challenging. Besides, the research on RLRs-mediated immune responses has become more popular in cellular immunology recently. Accumulating evidence shows that post-translation modifications, such as ubiquitination, deubiquitination and ISGylation, play an important role in regulating host innate immune responses. In parallel, these approaches may be used by viruses to evade PRRs-mediated responses or to actively subvert these pathways for their own benefit. It was identified that STING (also called MITA/MPYS/ERIS) plays an important role in RIG-Ⅰ-like receptor(RLR) signaling as a type Ⅰ IFN stimulator, providing a special method for the research on complex host antiviral innate immune responses.

Participação dos mastócitos e seus receptores TLR2 e dectina-1 na defesa contra Candida albicans: fagocitose e produção/liberação de óxido nítrico e de peróxido de hidrogênio / Participation of mast cells and its TLR2 and dectin-1 receptors in defense against C. albicans: phagocytosis and production/release of nitric oxide and hydrogen peroxide

Candida albicans (C. albicans) constitui um fungo comum nas mucosas do trato gastrointestinal, incluindo cavidade bucal, que pode ocasionar candidose local ou invasiva, principalmente em estados de imunossupressão. Os mecanismos de defesa contra este fungo podem ser desencadeados pela ligação dos receptores de reconhecimento de padrões, TLR2 e dectina-1, aos seus ligantes, como a fosfolipomanana e os -glucanos encontrados na parede celular de C. albicans. Os mastócitos possuem estes receptores em sua membrana celular e residem nas interfaces com o ambiente, podendo constituir umas das primeiras linhas de defesa. Seus mecanismos imunes incluem síntese e secreção de mediadores, apresentação de antígenos, bem como atividades fagocitária e microbicida. Todos estes mecanismos de defesa podem ser desencadeados de forma independente ou cooperativa entre os receptores TLR2 e dectina-1. Deste modo, o objetivo deste trabalho foi avaliar in vitro a ocorrência de fagocitose, a geração de óxido nítrico e peróxido de hidrogênio pelos mastócitos desafiados ou não com C. albicans, e a participação do TLR2 e dectina-1 nesses eventos. Para isto, mastócitos, diferenciados da medula óssea (BMMCs) de camundongos selvagens (BMMCs Wt) ou TLR2-/- (BMMCs TLR2-/-) foram desafiados com C. albicans. Células eram também bloqueadas in vitro com anticorpos específicos anti-dectina-1(BMMCs BD-1 e BMMCs TLR2-/-/BD-1). Os eventos foram analisados por meio de ensaio fluorescente de fagocitose, método colorimétrico de Griess e pelos kits DAF-FM diacetato, Cell Rox Deep e Amplex Red. Os resultados foram expressos através de porcentagem, valores médios e desvios padrão, obtidos a partir de pelo menos três experimentos independentes. As análises estatísticas foram realizadas através do teste ANOVA fatorial, seguido de Fischer. Entre os BMMCs Wt, houve maior taxa de fagocitose com uma maior produção intracelular de NO aos 60 minutos em comparação aos outros tempos. A liberação...

Candida albicans (C. albicans) is a common fungus present in gastrointestinal tract mucosa including oral cavity, which may cause local or invasive candidiasis, especially in immunosuppression. The mechanisms of defense against this fungus may be triggered by the binding of the pattern recognition receptors TLR2 and dectin-1 to its ligands, such as phospholipomannan and -glucans found in the cell wall of C. albicans. Mast cells express these receptors on cell membrane and reside in the interfaces with the environment, and may be one of the first lines of defense. Their immune mechanisms include synthesis and secretion of mediators, antigen presentation, as well as phagocytic and microbicidal activities. These mechanisms can be triggered independently or cooperatively by TLR2 and dectin-1. Therefore, the aim of the study was to evaluate in vitro the phagocytosis, the generation of nitric oxide and hydrogen peroxide by mast cells challenged or not with C. albicans, and the involvement of TLR2 and dectin-1 receptors in these mechanisms. Bone marrow-derived mast cell (BMMCs) from wild type mice (BMMCs Wt) or TLR2-/- (BMMCs TLR2-/-) was challenge with C. albicans. Cells were also in vitro blocked with specific anti-dectin-1 antibodies (BMMCs BD-1 and BMMCs TLR2-/-BD-1). The mechanisms were analyzed using fluorescent phagocytosis assay, Griess colorimetric method and by DAF-FM diacetate, CellRox® Deep Reagent and Amplex® Red enzyme assays. Results were expressed by percentage, mean and standard deviations obtained from the least three independent experiments. Statistic was performed using factorial ANOVA and Fischer. Among BMMCs Wt, there was higher phagocytosis rate associated with increased intracellular NO production at 60 minutes, comparing to other periods. The extracellular release of NO was higher at 120 minutes comparing to other periods. The number of phagocytized yeasts increased over time, however with significant difference only among the 30 and 120...