Antigen-specific response of murine immune system toward a yeast beta-glucan preparation, zymosan

Development of a multicolor upconversion fluorescence immunoassay for the simultaneous detection of thiamethoxam and dextran by magnetic separation

The contents of both pesticide residues and dextran are important parameters for evaluating the quality of sugarcane. In this study, a multicolor upconversion fluorescence immunoassay for the simultaneous detection of thiamethoxam and dextran was established on the basis of magnetic separation. Antigens of thiamethoxam and dextran were coupled to magnetic nanoparticles as the separation elements. Monoclonal antibodies of thiamethoxam (6C7D12) and dextran (3C6F7) were conjugated with the upconversion nanoparticles of NaYF₄:Yb,Er with an emission wavelength at 544 nm and NaYF₄:Yb,Tm with an emission wavelength at 477 nm to prepare the signaling elements, respectively. Due to the difference in the emission wavelength, the signaling elements bound on the separation elements could be detected simultaneously after separation by an external magnetic field. After optimization, the half-maximal inhibitory concentration (IC₅₀) values of the immunoassay for thiamethoxam and dextran were 0.46 and 49.33 ng mL⁻¹, respectively. The assay showed no cross-reactivity with the analogs of thiamethoxam and dextran except for clothianidin (8.7%). The average recoveries of thiamethoxam and dextran in sugarcane juice were 82.9–93.3% and 87.5–97.2%, respectively. The results indicated that the immunoassay could meet the requirements for the simultaneous quantitative detection of thiamethoxam and dextran.

The anti-thiamethoxam and anti-dextran monoclonal antibodies were prepared to develop a multicolor upconversion fluorescence immunoassay for the simultaneous determination of thiamethoxam (544 nm) and dextran (477 nm).

Subanesthetic isoflurane relieves zymosan-induced neutrophil inflammatory response by targeting NMDA glutamate receptor and Toll-like receptor 2 signaling

Neutrophil release of NO/ONOO⁻ induces endothelial cell barrier dysfunction in inflammatory acute lung injury (ALI). Previous studies using zymosan-triggered inflammation and ALI model revealed that zymosan promotes inducible NO synthase (iNOS) expression in neutrophils, and that isoflurane inhibits zymosan-induced oxidative stress and iNOS biosynthesis. However, the underlying mechanisms remain largely unknown. We found here that in zymosan-primed neutrophils, iNOS is transcriptionally activated by NF-κB, whose nuclear translocation is triggered by excessive reactive oxygen species (ROS) and consequently activated p38 MAPK. ROS production is attributed to zymosan-initiated Toll-like receptor 2 (TLR2) signaling, in which the adaptor MyD88 recruits and activates c-Src, and c-Src activates NADPH oxidase to generate ROS. Subanesthetic isoflurane counteracts the aforementioned zymosan-induced signaling by targeting N-methyl-D-aspartic acid (NMDA) glutamate receptor and thereby suppressing calcium influx and c-Src activation. Whereas iNOS accelerates NO/ONOO⁻ production in neutrophils which eventually promote protein leak from pulmonary microvascular endothelial cells (PMVEC), isoflurane reduced NO/ONOO⁻ release from zymosan-treated neutrophils, and thus relieves trans- PMVEC protein leak. This study provides novel insights into the roles of neutrophils and the underlying mechanisms in zymosan-induced ALI, and has implications for the therapeutic potential of subanesthetic isoflurane in attenuating inflammatory responses causing lung endothelial cell damage.

The Carbohydrate Lectin Receptor Dectin-1 Mediates the Immune Response to Exserohilum rostratum

Dematiaceous molds are found ubiquitously in the environment and cause a wide spectrum of human disease, including infections associated with high rates of mortality. Despite this, the mechanism of the innate immune response has been less well studied, although it is key in the clearance of fungal pathogens. Here, we focus on Exserohilum rostratum, a dematiaceous mold that caused 753 infections during a multistate outbreak due to injection of contaminated methylprednisolone. We show that macrophages are incapable of phagocytosing Exserohilum Despite a lack of phagocytosis, macrophage production of tumor necrosis factor alpha is triggered by hyphae but not spores and depends upon Dectin-1, a C-type lectin receptor. Dectin-1 is specifically recruited to the macrophage-hyphal interface but not the macrophage-spore interface due to differences in carbohydrate antigen expression between these two fungal forms. Corticosteroid and antifungal therapy perturb this response, resulting in decreased cytokine production. In vivo soft tissue infection in wild-type mice demonstrated that Exserohilum provokes robust neutrophilic and granulomatous inflammation capable of thwarting fungal growth. However, coadministration of methylprednisolone acetate results in robust hyphal tissue invasion and a significant reduction in immune cell recruitment. Our results suggest that Dectin-1 is crucial for macrophage recognition and the macrophage response to Exserohilum and that corticosteroids potently attenuate the immune response to this pathogen.

Nonspecific immunotherapy with intratumoral lipopolysaccharide and zymosan A but not GM-CSF leads to an effective anti-tumor response in subcutaneous RG-2 gliomas

PURPOSE

Nonspecific stimulation of cells of the immune system may be useful in generating an anti-tumor response for a variety of cancers and may work synergistically with currently available cytotoxic therapies. In this study we examined the response of syngeneic rat gliomas to treatment with several nonspecific stimulators of dendritic cells and macrophages alone or in combination with radiation therapy.

EXPERIMENTAL DESIGN

RG-2 gliomas were implanted subcutaneously and treated with intratumoral (IT) injections of the toll-like receptor (TLR) ligands lipopolysaccharide (LPS) and zymosan A (ZymA) and the cytokine granulocyte-macrophage colony stimulating factor (GM-CSF). Combination treatment with IT LPS and single-fraction external beam radiotherapy (EBRT) was also evaluated.

RESULTS

Treatment with IT LPS and ZymA delayed tumor growth compared to saline controls. Multiple doses of both substances were superior to single doses, and led to complete tumor regression in 71% (LPS) and 50% (ZymA) of animals. GM-CSF showed no anti-tumor effects in this study. Combinations of IT LPS and EBRT appeared to have a synergistic effect in delaying tumor growth. Rechallenge studies and IT LPS treatment of RG-2 tumors in nude rats suggested the importance of T cells in this treatment paradigm.

CONCLUSIONS

Direct IT treatment with the TLR ligands LPS and ZymA are effective in generating an anti-tumor response. These treatments may synergize with cytotoxic therapies such as EBRT, and appear to require T cells for a successful outcome.

Zymosan enhances the immune response to DNA vaccine for human immunodeficiency virus type-1 through the activation of complement system

In the present study, the adjuvant effect of zymosan on human immunodeficiency virus type-1 (HIV-1)-specific DNA vaccine and the mechanism of this enhancement were studied in a murine model. We coinoculated zymosan with our candidate HIV-1 specific DNA vaccine (pCMV160IIIB) into skeletal muscles of BALB/c mice. Higher levels of both humoral immune response and HIV-specific delayed-type hypersensitivity (DTH) response were observed when zymosan was coinoculated with pCMV160IIIB compared with that obtained using pCMV160IIIB alone. HIV-specific cytotoxic T lymphocyte (CTL) activity was also enhanced. This enhancing activity was suppressed when coinoculated to the fifth complement (C5)-deficient DDD and AKR mice. The enhanced activity was also suppressed when anti-C3 antibody was inoculated to mice intramuscularly. There was significant induction of immunoglobulin G2a (IgG2a) and interferon-gamma (IFN-gamma) in pCMV160IIIB vaccine with zymosan. These results suggest that zymosan-mediated DNA vaccination enhances helper T cell (Th) 1-mediated immunity. The effect is suggested to be based on the consequences of its recruitment and activation of macrophages, dendritic cells or antigen-presenting cells (APC) through complement activation, especially through the alternative pathway. Taken together, these results suggest that zymosan can be an effective immunological adjuvant in DNA vaccination against HIV-1.