The Experts below are selected from a list of 5598 Experts worldwide ranked by ideXlab platform
Gordon D. Brown - One of the best experts on this subject based on the ideXlab platform.
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Dectin-1 (CLEC7A, BGR, CLECSF12)
C-Type Lectin Receptors in Immunity, 2016Co-Authors: Patawee Asamaphan, Janet A. Willment, Gordon D. BrownAbstract:Dectin-1 is the archetypical example of the C-type lectin receptor (CLR) family of pattern recognition receptors (PRRs). Expressed primarily by cells of the innate immune system, this receptor is best known for its role in antifungal immunity through its ability to recognise cell wall β-glucans. Upon recognition of these carbohydrates, Dectin-1 transduces intracellular signalling through several pathways activating or regulating numerous cellular responses such as phagocytosis, the respiratory burst, neutrophil extracellular trap formation, inflammasome activation and cytokine and chemokine production. Moreover, like the Toll-like receptors (TLRs), Dectin-1 is able to instruct the development of adaptive immunity, promoting Th1- and Th17-type responses. Dectin-1 collaborates with other PRRs to synergise and regulate innate and adaptive immune responses. More recently, Dectin-1 has been found to recognise a broader range of microbial pathogens, including bacteria, as well as endogenous ligands, influencing autoimmune and other diseases, including rheumatoid arthritis, ulcerative colitis and cancer. In this chapter, we will discuss the structure, expression and ligands of Dectin-1, as well as the intracellular signalling pathways and cellular responses that this receptor can induce. We will describe the role of Dectin-1 in antifungal immunity and in immunity to other pathogens. We will briefly discuss the interaction of Dectin-1 with other PRRs and its broader role in immunity, through recognition of endogenous ligands, for example.
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CD4(+) T-cell survival in the GI tract requires Dectin-1 during fungal infection.
Mucosal immunology, 2015Co-Authors: Rebecca A. Drummond, David M. Underhill, Delyth M. Reid, Ivy M. Dambuza, S. Vautier, Julie A. Taylor, Calum C. Bain, David Masopust, Daniel H. Kaplan, Gordon D. BrownAbstract:Dectin-1 is an innate antifungal C-type lectin receptor necessary for protective antifungal immunity. We recently discovered that Dectin-1 is involved in controlling fungal infections of the gastrointestinal (GI) tract, but how this C-type lectin receptor mediates these activities is unknown. Here, we show that Dectin-1 is essential for driving fungal-specific CD4+ T-cell responses in the GI tract. Loss of Dectin-1 resulted in abrogated dendritic cell responses in the mesenteric lymph nodes (mLNs) and defective T-cell co-stimulation, causing substantial increases in CD4+ T-cell apoptosis and reductions in the cellularity of GI-associated lymphoid tissues. CD8+ T-cell responses were unaffected by Dectin-1 deficiency. These functions of Dectin-1 have significant implications for our understanding of intestinal immunity and susceptibility to fungal infections.
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Dectin 1 induces m1 macrophages and prominent expansion of cd8 il 17 cells in pulmonary paracoccidioidomycosis
The Journal of Infectious Diseases, 2014Co-Authors: Flavio V Loures, Gordon D. Brown, Eliseu Frank De Araujo, Claudia Feriotti, Silvia Boschi Bazan, Tânia Alves Da Costa, Vera Lucia Garcia CalichAbstract:Dectin-1, the innate immune receptor that recognizes β-glucan, plays an important role in immunity against fungal pathogens. Paracoccidioides brasiliensis, the etiological agent of paracoccidioidomycosis, has a sugar-rich cell wall mainly composed of mannans and glucans. This fact motivated us to use Dectin-1-sufficient and -deficient mice to investigate the role of β-glucan recognition in the immunity against pulmonary paracoccidioidomycosis. Initially, we verified that P. brasiliensis infection reinforced the tendency of Dectin-1-deficient macrophages to express an M2 phenotype. This prevalent antiinflammatory activity of Dectin-1(-/-) macrophages resulted in impaired fungicidal ability, low nitric oxide production, and elevated synthesis of interleukin 10 (IL-10). Compared with Dectin-1-sufficient mice, the fungal infection of Dectin-1(-/-) mice was more severe and resulted in enhanced tissue pathology and mortality rates. The absence of Dectin-1 has also impaired the production of T-helper type 1 (Th1), Th2, and Th17 cytokines and the activation and migration of T cells to the site of infection. Remarkably, Dectin-1 deficiency increased the expansion of regulatory T cells and reduced the differentiation of T cells to the IL-17(+) phenotype, impairing the migration of IL-17(+)CD8(+) T cells and polymorphonuclear cells to infected tissues. In conclusion, Dectin-1 exerts an important protective role in pulmonary paracoccidioidomycosis by controlling the innate and adaptive phases of antifungal immunity.
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Dectin-1 Induces M1 Macrophages and Prominent Expansion of CD8+IL-17+ Cells in Pulmonary Paracoccidioidomycosis
The Journal of infectious diseases, 2014Co-Authors: Flavio V Loures, Gordon D. Brown, Eliseu Frank De Araujo, Claudia Feriotti, Silvia Boschi Bazan, Tânia Alves Da Costa, Vera Lucia Garcia CalichAbstract:Dectin-1, the innate immune receptor that recognizes β-glucan, plays an important role in immunity against fungal pathogens. Paracoccidioides brasiliensis, the etiological agent of paracoccidioidomycosis, has a sugar-rich cell wall mainly composed of mannans and glucans. This fact motivated us to use Dectin-1-sufficient and -deficient mice to investigate the role of β-glucan recognition in the immunity against pulmonary paracoccidioidomycosis. Initially, we verified that P. brasiliensis infection reinforced the tendency of Dectin-1-deficient macrophages to express an M2 phenotype. This prevalent antiinflammatory activity of Dectin-1(-/-) macrophages resulted in impaired fungicidal ability, low nitric oxide production, and elevated synthesis of interleukin 10 (IL-10). Compared with Dectin-1-sufficient mice, the fungal infection of Dectin-1(-/-) mice was more severe and resulted in enhanced tissue pathology and mortality rates. The absence of Dectin-1 has also impaired the production of T-helper type 1 (Th1), Th2, and Th17 cytokines and the activation and migration of T cells to the site of infection. Remarkably, Dectin-1 deficiency increased the expansion of regulatory T cells and reduced the differentiation of T cells to the IL-17(+) phenotype, impairing the migration of IL-17(+)CD8(+) T cells and polymorphonuclear cells to infected tissues. In conclusion, Dectin-1 exerts an important protective role in pulmonary paracoccidioidomycosis by controlling the innate and adaptive phases of antifungal immunity.
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the β glucan receptor Dectin 1 promotes lung immunopathology during fungal allergy via il 22
Journal of Immunology, 2012Co-Authors: Lauren M Lilly, Gordon D. Brown, Melissa A Gessner, Chad W Dunaway, Allison E Metz, Lisa M Schwiebert, Casey T Weaver, Chad SteeleAbstract:Sensitization to fungi, such as the mold Aspergillus fumigatus , is increasingly becoming linked with asthma severity. We have previously shown that lung responses generated via the β-glucan receptor Dectin-1 are required for lung defense during acute, invasive A. fumigatus infection. Unexpectedly, in an allergic model of chronic lung exposure to live A. fumigatus conidia, β-glucan recognition via Dectin-1 led to the induction of multiple proallergic ( Muc5ac , Clca3 , CCL17, CCL22, and IL-33) and proinflammatory (IL-1β and CXCL1) mediators that compromised lung function. Attenuated proallergic and proinflammatory responses in the absence of Dectin-1 were not associated with changes in Ido (IDO), Il12p35/Ebi3 (IL-35), IL-10, or TGF-β levels. Assessment of Th responses demonstrated that purified lung CD4 + T cells produced IL-4, IL-13, IFN-γ, and IL-17A, but not IL-22, in a Dectin-1–dependent manner. In contrast, we observed robust, Dectin-1–dependent IL-22 production by unfractionated lung digest cells. Intriguingly, the absence of IL-22 alone mimicked the attenuated proallergic and proinflammatory responses observed in the absence of Dectin-1, suggesting that Dectin-1–mediated IL-22 production potentiated responses that led to decrements in lung function. To this end, neutralization of IL-22 improved lung function in normal mice. Collectively, these results indicate that the β-glucan receptor Dectin-1 contributes to lung inflammation and immunopathology associated with persistent fungal exposure via the production of IL-22.
Aaron K. Neumann - One of the best experts on this subject based on the ideXlab platform.
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Dectin-1-Mediated DC-SIGN Recruitment to Candida albicans Contact Sites.
Life (Basel Switzerland), 2021Co-Authors: Rohan P Choraghe, Aaron K. NeumannAbstract:At host-pathogen contact sites with Candida albicans, Dectin-1 activates pro-inflammatory signaling, while DC-SIGN promotes adhesion to the fungal surface. We observed that Dectin-1 and DC-SIGN collaborate to enhance capture/retention of C. albicans under fluid shear culture conditions. Therefore, we devised a cellular model system wherein we could investigate the interaction between these two receptors during the earliest stages of host-pathogen interaction. In cells expressing both receptors, DC-SIGN was quickly recruited to contact sites (103.15% increase) but Dectin-1 did not similarly accumulate. Once inside the contact site, FRAP studies revealed a strong reduction in lateral mobility of DC-SIGN (but not Dectin-1), consistent with DC-SIGN engaging in multivalent adhesive binding interactions with cell wall mannoprotein ligands. Interestingly, in the absence of Dectin-1 co-expression, DC-SIGN recruitment to the contact was much poorer-only 35.04%. These data suggested that Dectin-1 promotes the active recruitment of DC-SIGN to the contact site. We proposed that Dectin-1 signaling activates the RHOA pathway, leading to actomyosin contractility that promotes DC-SIGN recruitment, perhaps via the formation of a centripetal actomyosin flow (AMF) directed into the contact site. Indeed, RHOA pathway inhibitors significantly reduced Dectin-1-associated DC-SIGN recruitment to the contact site. We used agent-based modeling to predict DC-SIGN transport kinetics with ("Directed + Brownian") and without ("Brownian") the hypothesized actomyosin flow-mediated transport. The Directed + Brownian transport model predicted a DC-SIGN contact site recruitment (106.64%), similar to that we observed experimentally under receptor co-expression. Brownian diffusive transport alone predicted contact site DC-SIGN recruitment of only 55.60%. However, this value was similar to experimentally observed DC-SIGN recruitment in cells without Dectin-1 or expressing Dectin-1 but treated with RHOA inhibitor, suggesting that it accurately predicted DC-SIGN recruitment when a contact site AMF would not be generated. TIRF microscopy of nascent cell contacts on glucan-coated glass revealed Dectin-1-dependent DC-SIGN and F-actin (LifeAct) recruitment kinetics to early stage contact site membranes. DC-SIGN entry followed F-actin with a temporal lag of 8.35 ± 4.57 s, but this correlation was disrupted by treatment with RHOA inhibitor. Thus, computational and experimental evidence provides support for the existence of a Dectin-1/RHOA-dependent AMF that produces a force to drive DC-SIGN recruitment to pathogen contact sites, resulting in improved pathogen capture and retention by immunocytes. These data suggest that the rapid collaborative response of Dectin-1 and DC-SIGN in early contact sties might be important for the efficient acquisition of yeast under flow conditions, such as those that prevail in circulation or mucocutaneous sites of infection.
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Dectin-1 mediated DC-SIGN Recruitment to Candida albicans Contact Sites
2020Co-Authors: Rohan P Choraghe, Aaron K. NeumannAbstract:At host-pathogen contact sites with Candida albicans, Dectin-1 activates pro-inflammatory signaling, while DC-SIGN promotes adhesion to the fungal surface. We observed that Dectin-1 and DC-SIGN collaborate to enhance capture/retention of C. albicans under fluid shear culture conditions. Therefore, we devised a cellular model system wherein we could investigate the interaction between these two receptors during the earliest stages of host-pathogen interaction. In cells expressing both receptors, DC-SIGN was quickly recruited to contact sites (103.15% increase) but Dectin-1 did not similarly accumulate. Once inside the contact site, FRAP studies revealed a strong reduction in lateral mobility of DC-SIGN (but not Dectin-1), consistent with DC-SIGN engaging in multivalent adhesive binding interactions with cell wall mannoprotein ligands. Interestingly, in the absence of Dectin-1 co-expression, DC-SIGN recruitment to the contact was much poorer, only 35.04%. These data suggested that Dectin-1 promotes the active recruitment of DC-SIGN to the contact site. We proposed that Dectin-1 signaling activates the RHOA pathway, leading to actomyosin contractility that promotes DC-SIGN recruitment, perhaps via the formation of a centripetal ActoMyosin Flow (AMF) directed into the contact site. Indeed, RHOA pathway inhibitors significantly reduced Dectin-1 associated DC-SIGN recruitment to the contact site. We used agent based modeling to predict DC-SIGN transport kinetics with (Directed+Brownian) and without (Brownian) the hypothesized actomyosin flow-mediated transport. The Directed+Brownian transport model predicted a DC-SIGN contact site recruitment (108.72%), similar to that we observed experimentally under receptor co-expression. Brownian diffusive transport alone predicted contact site DC-SIGN recruitment of only 54.02%. However, this value was similar to experimentally observed recruitment in cells without Dectin-1 or treated with RHOA inhibitor, suggesting that it accurately predicted DC-SIGN recruitment when a contact site AMF would not be generated. TIRF microscopy of nascent cell contacts on glucan-coated glass revealed Dectin-1 dependent DC-SIGN and F-actin (LifeAct) recruitment kinetics to early-stage contact site membranes. DC-SIGN entry followed F-actin with a temporal lag of 8.35 +/- 4.57 seconds, but this correlation was disrupted by treatment with RHOA inhibitor. Thus, computational and experimental evidence provides support for the existence of a Dectin-1/RHOA-dependent AMF that produces a force to drive DC-SIGN recruitment to pathogen contact sites, resulting in improved pathogen capture and retention by immunocytes. These data suggest that the rapid collaborative response of Dectin-1 and DC-SIGN in early contact sties might be important for the efficient acquisition of yeast under flow conditions, such as those that prevail in circulation or mucocutaneous sites of infection.
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RHOA-mediated mechanical force generation through Dectin-1
Journal of cell science, 2020Co-Authors: Rohan P Choraghe, Tomasz Kołodziej, Alan Buser, Zenon Rajfur, Aaron K. NeumannAbstract:Dectin-1 (Dendritic Cell associated C-type Lectin 1) is an innate immune pattern recognition receptor which recognizes β-glucan on the Candida albicans (C. albicans) cell wall. Recognition of β-glucan by immune cells leads to phagocytosis, oxidative burst, cytokine and chemokine production. We looked for specific mechanisms that coordinate phagocytosis downstream of Dectin-1 leading to actin reorganization and internalization of fungus. We found that stimulation of Dectin-1 by soluble β-glucan leads to mechanical force generation and areal contraction in Dectin-1 transfected HEK-293 cells and M1 macrophages. With inhibitor studies, we found this force generation is a SYK (Spleen Tyrosine Kinase)-independent, SFK (SRC Family Kinase)-dependent process mediated through the RHOA (Ras homolog family member type A)-ROCK (Rho associated coiled-coil containing protein kinase)-MLC (Myosin light chain) pathway. We confirmed activation of RHOA downstream of Dectin-1 using activity assays and stress fiber formation. Through phagocytosis assays, we found direct evidence for the importance of RHOA-ROCK-MLC signaling in the process of phagocytosis of C. albicans.
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RHOA mediated mechanical force generation through Dectin-1
2019Co-Authors: Rohan P Choraghe, Tomasz Kołodziej, Alan Buser, Zenon Rajfur, Aaron K. NeumannAbstract:Dectin-1 is an innate immune pattern recognition receptor which recognizes {beta}-glucan on the Candida albicans (C. albicans) cell wall. Recognition of {beta}-glucan by immune cells leads to phagocytosis, oxidative burst, cytokine and chemokine production. We looked for specific mechanisms that coordinate phagocytosis downstream of Dectin-1 leading to actin reorganization and internalization of fungus. We found that stimulation of Dectin-1 by soluble {beta}-glucan leads to mechanical force generation and areal contraction in Dectin-1 transfected HEK-293 cells and M1 macrophages. With inhibitor studies, we found this force generation is a SYK-independent, SFK (SRC Family Kinase)-dependent process mediated through the RHOA-ROCK-MLC pathway. We confirmed activation of RHOA downstream of Dectin-1 using G-LISA and stress fiber formation. Through phagocytosis assays, we found direct evidence for importance of RHOA-ROCK-MLC pathway in process of phagocytosis of C. albicans. In conclusion, we found evidence for RHOA-ROCK-MLC mediated mechanical force generation downstream of Dectin-1 for C. albicans phagocytosis.
Luis A Pedroza - One of the best experts on this subject based on the ideXlab platform.
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autoimmune regulator aire contributes to Dectin 1 induced tnf α production and complexes with caspase recruitment domain containing protein 9 card9 spleen tyrosine kinase syk and Dectin 1
The Journal of Allergy and Clinical Immunology, 2012Co-Authors: Luis A Pedroza, Vipul Kumar, Keri B Sanborn, Emily M Mace, Harri Niinikoski, Kari C Nadeau, Dewton De Moraes VasconcelosAbstract:Background Autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy (APECED) syndrome is a complex immunologic disease caused by mutation of the autoimmune regulator (AIRE) gene. Autoimmunity in patients with APECED syndrome has been shown to result from deficiency of AIRE function in transcriptional regulation of thymic peripheral tissue antigens, which leads to defective T-cell negative selection. Candidal susceptibility in patients with APECED syndrome is thought to result from aberrant adaptive immunity. Objective To determine whether AIRE could function in anticandidal innate immune signaling, we investigated an extrathymic role for AIRE in the immune recognition of β-glucan through the Dectin-1 pathway, which is required for defense against Candida species. Methods Innate immune signaling through the Dectin-1 pathway was assessed in both PBMCs from patients with APECED syndrome and a monocytic cell line. Subcellular localization of AIRE was assessed by using confocal microscopy. Results PBMCs from patients with APECED syndrome had reduced TNF-α responses after Dectin-1 ligation but in part used a Raf-1–mediated pathway to preserve function. In the THP-1 human monocytic cell line, reducing AIRE expression resulted in significantly decreased TNF-α release after Dectin-1 ligation. AIRE formed a transient complex with the known Dectin-1 pathway components phosphorylated spleen tyrosine kinase and caspase recruitment domain–containing protein 9 after receptor ligation and localized with Dectin-1 at the cell membrane. Conclusion AIRE can participate in the Dectin-1 signaling pathway, indicating a novel extrathymic role for AIRE and a defect that likely contributes to fungal susceptibility in patients with APECED syndrome.
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Autoimmune regulator (AIRE) contributes to Dectin-1–induced TNF-α production and complexes with caspase recruitment domain–containing protein 9 (CARD9), spleen tyrosine kinase (Syk), and Dectin-1
The Journal of allergy and clinical immunology, 2011Co-Authors: Luis A Pedroza, Vipul Kumar, Keri B Sanborn, Emily M Mace, Harri Niinikoski, Kari C Nadeau, Dewton De Moraes Vasconcelos, Elena E. Perez, Soma Jyonouchi, Harumi JyonouchiAbstract:Background Autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy (APECED) syndrome is a complex immunologic disease caused by mutation of the autoimmune regulator (AIRE) gene. Autoimmunity in patients with APECED syndrome has been shown to result from deficiency of AIRE function in transcriptional regulation of thymic peripheral tissue antigens, which leads to defective T-cell negative selection. Candidal susceptibility in patients with APECED syndrome is thought to result from aberrant adaptive immunity. Objective To determine whether AIRE could function in anticandidal innate immune signaling, we investigated an extrathymic role for AIRE in the immune recognition of β-glucan through the Dectin-1 pathway, which is required for defense against Candida species. Methods Innate immune signaling through the Dectin-1 pathway was assessed in both PBMCs from patients with APECED syndrome and a monocytic cell line. Subcellular localization of AIRE was assessed by using confocal microscopy. Results PBMCs from patients with APECED syndrome had reduced TNF-α responses after Dectin-1 ligation but in part used a Raf-1–mediated pathway to preserve function. In the THP-1 human monocytic cell line, reducing AIRE expression resulted in significantly decreased TNF-α release after Dectin-1 ligation. AIRE formed a transient complex with the known Dectin-1 pathway components phosphorylated spleen tyrosine kinase and caspase recruitment domain–containing protein 9 after receptor ligation and localized with Dectin-1 at the cell membrane. Conclusion AIRE can participate in the Dectin-1 signaling pathway, indicating a novel extrathymic role for AIRE and a defect that likely contributes to fungal susceptibility in patients with APECED syndrome.
Rohan P Choraghe - One of the best experts on this subject based on the ideXlab platform.
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Dectin-1-Mediated DC-SIGN Recruitment to Candida albicans Contact Sites.
Life (Basel Switzerland), 2021Co-Authors: Rohan P Choraghe, Aaron K. NeumannAbstract:At host-pathogen contact sites with Candida albicans, Dectin-1 activates pro-inflammatory signaling, while DC-SIGN promotes adhesion to the fungal surface. We observed that Dectin-1 and DC-SIGN collaborate to enhance capture/retention of C. albicans under fluid shear culture conditions. Therefore, we devised a cellular model system wherein we could investigate the interaction between these two receptors during the earliest stages of host-pathogen interaction. In cells expressing both receptors, DC-SIGN was quickly recruited to contact sites (103.15% increase) but Dectin-1 did not similarly accumulate. Once inside the contact site, FRAP studies revealed a strong reduction in lateral mobility of DC-SIGN (but not Dectin-1), consistent with DC-SIGN engaging in multivalent adhesive binding interactions with cell wall mannoprotein ligands. Interestingly, in the absence of Dectin-1 co-expression, DC-SIGN recruitment to the contact was much poorer-only 35.04%. These data suggested that Dectin-1 promotes the active recruitment of DC-SIGN to the contact site. We proposed that Dectin-1 signaling activates the RHOA pathway, leading to actomyosin contractility that promotes DC-SIGN recruitment, perhaps via the formation of a centripetal actomyosin flow (AMF) directed into the contact site. Indeed, RHOA pathway inhibitors significantly reduced Dectin-1-associated DC-SIGN recruitment to the contact site. We used agent-based modeling to predict DC-SIGN transport kinetics with ("Directed + Brownian") and without ("Brownian") the hypothesized actomyosin flow-mediated transport. The Directed + Brownian transport model predicted a DC-SIGN contact site recruitment (106.64%), similar to that we observed experimentally under receptor co-expression. Brownian diffusive transport alone predicted contact site DC-SIGN recruitment of only 55.60%. However, this value was similar to experimentally observed DC-SIGN recruitment in cells without Dectin-1 or expressing Dectin-1 but treated with RHOA inhibitor, suggesting that it accurately predicted DC-SIGN recruitment when a contact site AMF would not be generated. TIRF microscopy of nascent cell contacts on glucan-coated glass revealed Dectin-1-dependent DC-SIGN and F-actin (LifeAct) recruitment kinetics to early stage contact site membranes. DC-SIGN entry followed F-actin with a temporal lag of 8.35 ± 4.57 s, but this correlation was disrupted by treatment with RHOA inhibitor. Thus, computational and experimental evidence provides support for the existence of a Dectin-1/RHOA-dependent AMF that produces a force to drive DC-SIGN recruitment to pathogen contact sites, resulting in improved pathogen capture and retention by immunocytes. These data suggest that the rapid collaborative response of Dectin-1 and DC-SIGN in early contact sties might be important for the efficient acquisition of yeast under flow conditions, such as those that prevail in circulation or mucocutaneous sites of infection.
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Dectin-1 mediated DC-SIGN Recruitment to Candida albicans Contact Sites
2020Co-Authors: Rohan P Choraghe, Aaron K. NeumannAbstract:At host-pathogen contact sites with Candida albicans, Dectin-1 activates pro-inflammatory signaling, while DC-SIGN promotes adhesion to the fungal surface. We observed that Dectin-1 and DC-SIGN collaborate to enhance capture/retention of C. albicans under fluid shear culture conditions. Therefore, we devised a cellular model system wherein we could investigate the interaction between these two receptors during the earliest stages of host-pathogen interaction. In cells expressing both receptors, DC-SIGN was quickly recruited to contact sites (103.15% increase) but Dectin-1 did not similarly accumulate. Once inside the contact site, FRAP studies revealed a strong reduction in lateral mobility of DC-SIGN (but not Dectin-1), consistent with DC-SIGN engaging in multivalent adhesive binding interactions with cell wall mannoprotein ligands. Interestingly, in the absence of Dectin-1 co-expression, DC-SIGN recruitment to the contact was much poorer, only 35.04%. These data suggested that Dectin-1 promotes the active recruitment of DC-SIGN to the contact site. We proposed that Dectin-1 signaling activates the RHOA pathway, leading to actomyosin contractility that promotes DC-SIGN recruitment, perhaps via the formation of a centripetal ActoMyosin Flow (AMF) directed into the contact site. Indeed, RHOA pathway inhibitors significantly reduced Dectin-1 associated DC-SIGN recruitment to the contact site. We used agent based modeling to predict DC-SIGN transport kinetics with (Directed+Brownian) and without (Brownian) the hypothesized actomyosin flow-mediated transport. The Directed+Brownian transport model predicted a DC-SIGN contact site recruitment (108.72%), similar to that we observed experimentally under receptor co-expression. Brownian diffusive transport alone predicted contact site DC-SIGN recruitment of only 54.02%. However, this value was similar to experimentally observed recruitment in cells without Dectin-1 or treated with RHOA inhibitor, suggesting that it accurately predicted DC-SIGN recruitment when a contact site AMF would not be generated. TIRF microscopy of nascent cell contacts on glucan-coated glass revealed Dectin-1 dependent DC-SIGN and F-actin (LifeAct) recruitment kinetics to early-stage contact site membranes. DC-SIGN entry followed F-actin with a temporal lag of 8.35 +/- 4.57 seconds, but this correlation was disrupted by treatment with RHOA inhibitor. Thus, computational and experimental evidence provides support for the existence of a Dectin-1/RHOA-dependent AMF that produces a force to drive DC-SIGN recruitment to pathogen contact sites, resulting in improved pathogen capture and retention by immunocytes. These data suggest that the rapid collaborative response of Dectin-1 and DC-SIGN in early contact sties might be important for the efficient acquisition of yeast under flow conditions, such as those that prevail in circulation or mucocutaneous sites of infection.
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RHOA-mediated mechanical force generation through Dectin-1
Journal of cell science, 2020Co-Authors: Rohan P Choraghe, Tomasz Kołodziej, Alan Buser, Zenon Rajfur, Aaron K. NeumannAbstract:Dectin-1 (Dendritic Cell associated C-type Lectin 1) is an innate immune pattern recognition receptor which recognizes β-glucan on the Candida albicans (C. albicans) cell wall. Recognition of β-glucan by immune cells leads to phagocytosis, oxidative burst, cytokine and chemokine production. We looked for specific mechanisms that coordinate phagocytosis downstream of Dectin-1 leading to actin reorganization and internalization of fungus. We found that stimulation of Dectin-1 by soluble β-glucan leads to mechanical force generation and areal contraction in Dectin-1 transfected HEK-293 cells and M1 macrophages. With inhibitor studies, we found this force generation is a SYK (Spleen Tyrosine Kinase)-independent, SFK (SRC Family Kinase)-dependent process mediated through the RHOA (Ras homolog family member type A)-ROCK (Rho associated coiled-coil containing protein kinase)-MLC (Myosin light chain) pathway. We confirmed activation of RHOA downstream of Dectin-1 using activity assays and stress fiber formation. Through phagocytosis assays, we found direct evidence for the importance of RHOA-ROCK-MLC signaling in the process of phagocytosis of C. albicans.
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RHOA mediated mechanical force generation through Dectin-1
2019Co-Authors: Rohan P Choraghe, Tomasz Kołodziej, Alan Buser, Zenon Rajfur, Aaron K. NeumannAbstract:Dectin-1 is an innate immune pattern recognition receptor which recognizes {beta}-glucan on the Candida albicans (C. albicans) cell wall. Recognition of {beta}-glucan by immune cells leads to phagocytosis, oxidative burst, cytokine and chemokine production. We looked for specific mechanisms that coordinate phagocytosis downstream of Dectin-1 leading to actin reorganization and internalization of fungus. We found that stimulation of Dectin-1 by soluble {beta}-glucan leads to mechanical force generation and areal contraction in Dectin-1 transfected HEK-293 cells and M1 macrophages. With inhibitor studies, we found this force generation is a SYK-independent, SFK (SRC Family Kinase)-dependent process mediated through the RHOA-ROCK-MLC pathway. We confirmed activation of RHOA downstream of Dectin-1 using G-LISA and stress fiber formation. Through phagocytosis assays, we found direct evidence for importance of RHOA-ROCK-MLC pathway in process of phagocytosis of C. albicans. In conclusion, we found evidence for RHOA-ROCK-MLC mediated mechanical force generation downstream of Dectin-1 for C. albicans phagocytosis.
Naohito Ohno - One of the best experts on this subject based on the ideXlab platform.
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Barley-derived β-d-glucan induces immunostimulation via a Dectin-1-mediated pathway
Immunology letters, 2009Co-Authors: Rui Tada, Yuya Kato, Yoshiyuki Adachi, Futoshi Ikeda, Kosuke Aoki, Masashi Yoshikawa, Asuka Tanioka, Ken-ichi Ishibashi, Kazufumi Tsubaki, Naohito OhnoAbstract:Barley-derived beta-glucan, a linear mixed-linkage beta-glucan composed of 1,3- and 1,4-beta-D-glucopyranose polymers, binds to Dectin-1. However, whether it can trigger signal transduction via Dectin-1 remains unclear. In this study, we used a reporter gene assay to determine whether barley-derived beta-d-glucan can activate NF-kappaB via Dectin-1-mediated signaling when Dectin-1 is cotransfected with Syk, CARD9, and Bcl10 in 293T cells. We found that barley-derived beta-D-glucan can activate NF-kappaB leading to cytokine production when Dectin-1, Syk, CARD9, and Bcl10 are coexpressed in the cells. We also found that barley-derived beta-D-glucan can induce the phosphorylation of Syk and production of IL-6 in thioglycolate-elicited peritoneal macrophages. These results indicated that the immunostimulatory effects of barley-derived beta-d-glucan might be exerted, at least in part, via Dectin-1.
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Characterization of rat β‐glucan receptor Dectin‐1
Microbiology and immunology, 2008Co-Authors: Yuya Kato, Yoshiyuki Adachi, Naohito OhnoAbstract:Dectin-1 is a small C-type lectin receptor for fungal cell wall β-glucan. Its homologues in some species, including mouse and human, have been characterized, and their importance in antifungal immunity has also been clarified. However, its homologue in the rat has not yet been identified. In this study, DNA/amino acid sequences of rat Dectin-1 were analyzed by rapid amplification of cDNA ends. The sequence of rat Dectin-1 was found to be highly homologous to that of the mouse. It possesses essential motifs for the recognition of β-glucan and signal transduction. However, the position of the start codon in the detected sequence was not conserved, and its cytoplasmic tail was shorter than that observed in other species. Similar to mouse Dectin-1, two major isoforms of rat Dectin-1 that were generated by alternative splicing were identified: a full-length isoform and a shorter isoform deficient in the stalk domain. It was also demonstrated that rat Dectin-1 is capable of binding fungal β-glucan and activating nuclear factor-kappa B via Syk and the CARD9/Bcl10-mediated pathway. These results suggest that rat Dectin-1 also plays essential roles in immune responses against fungi.
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Blocking Effect of Anti-Dectin-1 Antibodies on the Anti-tumor Activity of 1,3-β-Glucan and the Binding of Dectin-1 to 1,3-β-Glucan
Biological & pharmaceutical bulletin, 2007Co-Authors: Yoshihiko Ikeda, Yoshiyuki Adachi, Takashi Ishii, Hiroshi Tamura, Jun Aketagawa, Shigenori Tanaka, Naohito OhnoAbstract:Schizophyllan (SPG) is used to treat cervical cancer in combination with irradiation to enhance the immunological surveillance system. Dectin-1 is a cell surface receptor for 1,3-beta-glucan. In this study, we prepared two anti-Dectin-1 monoclonal antibodies, 4B2 and SC30 having a K(D) of 7.04 x 10(-8) M and 1.55 x 10(-7) M, respectively, and evaluated the role of Dectin-1 in SPG-induced anti-tumor activity in mice. Expression of Dectin-1 on peritoneal macrophages and binding of SPG to the cells were decreased by administration of 4B2 and SC30. SPG-mediated anti-tumor activity was inhibited by 4B2 and SC30. 4B2 and SC30 inhibited the binding of SPG to splenocytes from mice. The binding of SPG-biotin to Dectin-1-transfected HEK293 cells was inhibited by 4B2, but not SC30. 4B2 and SC30 differ in their influence on Dectin-1 between primary cells and transduced cells, and Dectin-1 effects 1,3-beta-glucan-mediated anti-tumor activity in mice by binding to SPG.
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Dectin 1 is required for host defense against pneumocystis carinii but not against candida albicans
Nature Immunology, 2007Co-Authors: Shinobu Saijo, Yoshiyuki Adachi, Noriyuki Fujikado, Takahisa Furuta, Soohyun Chung, Hayato Kotaki, Keisuke Seki, Katsuko Sudo, Shizuo Akira, Naohito OhnoAbstract:Dectin-1 is a C-type lectin involved in the recognition of β-glucans found in the cell walls of fungi. We generated Dectin-1-deficient mice to determine the importance of Dectin-1 in the defense against pathogenic fungi. In vitro, β-glucan-induced cytokine production from wild-type dendritic cells and macrophages was abolished in cells homozygous for Dectin-1 deficiency ('Dectin-1-knockout' cells). In vivo, Dectin-1-knockout mice were more susceptible than wild-type mice to pneumocystis infection, even though their cytokine production was normal. However, pneumocystis-infected Dectin-1-knockout macrophages did show defective production of reactive oxygen species. In contrast to those results, wild-type and Dectin-1-knockout mice were equally susceptible to candida infection. Thus, Dectin-1 is required for immune responses to some fungal infections, as protective immunity to pneumocystis, but not to candida, required Dectin-1 for the production of antifungal reactive oxygen species.
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Dectin 1 is required for host defense against pneumocystis carinii but not against candida albicans
Nature Immunology, 2007Co-Authors: Shinobu Saijo, Yoshiyuki Adachi, Noriyuki Fujikado, Takahisa Furuta, Soohyun Chung, Hayato Kotaki, Keisuke Seki, Katsuko Sudo, Shizuo Akira, Naohito OhnoAbstract:Dectin-1 is a C-type lectin involved in the recognition of beta-glucans found in the cell walls of fungi. We generated Dectin-1-deficient mice to determine the importance of Dectin-1 in the defense against pathogenic fungi. In vitro, beta-glucan-induced cytokine production from wild-type dendritic cells and macrophages was abolished in cells homozygous for Dectin-1 deficiency ('Dectin-1-knockout' cells). In vivo, Dectin-1-knockout mice were more susceptible than wild-type mice to pneumocystis infection, even though their cytokine production was normal. However, pneumocystis-infected Dectin-1-knockout macrophages did show defective production of reactive oxygen species. In contrast to those results, wild-type and Dectin-1-knockout mice were equally susceptible to candida infection. Thus, Dectin-1 is required for immune responses to some fungal infections, as protective immunity to pneumocystis, but not to candida, required Dectin-1 for the production of antifungal reactive oxygen species.
