The cooperative induction of macrophage activation by fucoidan derived from Cladosiphon okamuranus and ß-glucan derived from Saccharomyces cerevisiae.

The present study investigated immune stimulatory effects of Cladosiphon okamuranus-derived fucoidan to activate murine macrophage-like cell line RAW264, and the functional relationship with zymosan, a Saccharomyces cerevisiae-derived ß-glucan. The production of nitric oxide (NO) and tumor necrosis factor-α (TNF-α) in RAW264 cells were remarkably enhanced in the presence of 10 µg/mL fucoidan, and the stimulatory effects of fucoidan were maximally augmented in combinational treatment with 500 ng/mL zymosan, whereas any TLR ligands had no those effects. Confocal microscopic analyses suggested that fucoidan bound on plasma membrane, and it was estimated that some cell surface molecules acted as receptor for fucoidan because cytochalasin D, an inhibitor of phagocytosis, did not affect the immune enhancing activities, whereas methyl-ß-cyclodextrin (MßCD), a general agent for disruption of lipid rafts, diminished that. Furthermore, it was revealed that the additive effects of zymosan on the immune activation with fucoidan was thought to be mediated by dectin-1 based on the results with dectin-1-knockdown RAW264 cells. All of results suggested that fucoidan and some kinds of ß-glucan would cooperatively reinforce the activity of innate immune cells via interactive receptor crosstalk.

An ITAM-Syk-CARD9 signalling axis triggers contact hypersensitivity by stimulating IL-1 production in dendritic cells.

A variety of reactive organic compounds, called haptens, can cause allergic contact dermatitis. However, the innate immune mechanisms by which haptens stimulate dendritic cells (DCs) to sensitize T cells remain unclear. Here we show that the coupling of ITAM-Syk-CARD9 signalling to interleukin-1 (IL-1) secretion in DCs is crucial for allergic sensitization to haptens. Both MyD88 and Caspase recruitment domain-containing protein 9 (CARD9) signalling are required for contact hypersensitivity (CHS). Naïve T cells require signals received through IL-1R1-MyD88 for effector differentiation, whereas DCs require CARD9 and spleen tyrosine kinase (Syk) signalling for hapten-induced IL-1α/ß secretion and their ability to prime T cells. DC-specific deletion of CARD9, DAP12, Syk or NLRP3, but not MyD88, is sufficient to abolish CHS. All tested haptens, but not irritants, can induce Syk activation, leading to both the CARD9/BCL10-dependent pro-IL-1 synthesis (signal1) and reactive oxygen species-mediated NLRP3 inflammasome activation (signal2), required for IL-1 secretion. These data unveil an innate immune mechanism crucial for allergic contact sensitization to chemical compounds.

Interleukin 27 inhibits atherosclerosis via immunoregulation of macrophages in mice.

Chronic inflammation in arterial wall that is driven by immune cells and cytokines plays pivotal roles in the development of atherosclerosis. Interleukin 27 (IL-27) is a member of the IL-12 family of cytokines that consists of IL-27p28 and Epstein-Barr virus induced gene 3 (EBI3) and has anti-inflammatory properties that regulate T cell polarization and cytokine production. IL-27-deficient (Ldlr-/-Ebi3-/-) and IL-27 receptor-deficient (Ldlr-/-WSX-1-/-) Ldlr-/- mice were generated and fed with a high-cholesterol diet to induce atherosclerosis. Roles of bone marrow-derived cells in vivo and macrophages in vitro were studied using bone marrow reconstitution by transplantation and cultured peritoneal macrophages, respectively. We demonstrate that mice lacking IL-27 or IL-27 receptor are more susceptible to atherosclerosis compared with wild type due to enhanced accumulation and activation of macrophages in arterial walls. The number of circulating proinflammatory Ly6C(hi) monocytes showed no significant difference between wild-type mice and mice lacking IL-27 or IL-27 receptor. Administration of IL-27 suppressed the development of atherosclerosis in vivo and macrophage activation in vitro that was indicated by increased uptake of modified low-density lipoprotein and augmented production of proinflammatory cytokines. These findings define a novel inhibitory role for IL-27 in atherosclerosis that regulates macrophage activation in mice.

Adipose Tissue-Derived Stem Cell Imaging Using Cadmium-Free Quantum Dots.

Quantum dots (QDs) have received much attention for biomolecule and cell imaging applications because of their superior optical properties such as high quantum efficiency, size-tunable emission, and resistance to photobleaching process. However, QDs that are commercially available contain cadmium (Cd), a highly toxic element. Thus, the development of Cd-free and less toxic QDs is strongly desired. In this study, we developed Cd-free QDs (ZnS-coated ZnS-AgInS2 solid solution nanoparticles with a sulfo group: ZnS-ZAIS-SO3H) and investigated the ability of this material to label stem cells. ZnS-ZAIS-SO3H could be transduced into mouse adipose tissue-derived stem cells (mASCs) using octaarginine peptides (R8), known as cell-penetrating peptides. The optimal ratio of ZnS-ZAIS-SO3H:R8 was found to be 1:100 for labeling mASCs. More than 80% of mASCs labeled with 500 nM ZnS-ZAIS-SO3H were found to be alive, and the proliferation rates of labeled mASCs were maintained at the same rate as that of nonlabeled mASCs. In addition, no abnormalities in the morphology of mASCs labeled with ZnS-ZAIS-SO3H could be observed. These data suggest that ZnS-ZAIS-SO3H may be effective for the labeling of mASCs.

IL-27 inhibits hyperglycemia and pancreatic islet inflammation induced by streptozotocin in mice.

Inflammation driven by immune cells and pro-inflammatory cytokines is implicated in pancreatic ß-cell injury, leading to the development of diabetes mellitus. IL-27, a cytokine consisting of IL-27p28 and Epstein-Barr virus-induced gene 3 (EBI3), binds a membrane-bound heterodimeric receptor consisting of the IL-27 receptor α chain (WSX-1) and gp130. IL-27 has anti-inflammatory properties that regulate T-cell polarization and cytokine production. We evaluated blood glucose and islet proinsulin concentrations, inflammatory cell infiltration in islets, and expression of IL-1ß mRNA in pancreas in wild-type (WT), EBI3(-/-), and WSX-1(-/-) mice treated with streptozotocin (STZ). Hyperglycemia was augmented in EBI3(-/-) and WSX-1(-/-) mice compared with WT mice. Islet proinsulin levels after STZ treatment were lower in EBI3(-/-) and WSX-1(-/-) mice than in WT mice. The infiltration of islets by F4/80(+)CD11c(-)7/4(-) macrophages, CD4(+) T cells, and CD8(+) T cells was increased in EBI3(-/-) and WSX-1(-/-) mice compared with WT mice. The administration of recombinant IL-27, compared with control, decreased the blood glucose level, immune cell infiltration into islets, and IL-1ß mRNA expression in the pancreas and increased islet proinsulin levels in WT and EBI3(-/-) mice. Thus, IL-27 inhibits STZ-induced hyperglycemia and pancreatic islet inflammation in mice and represents a potential novel therapeutic approach for ß-cell protection in diabetes.

IL-17 is necessary for host protection against acute-phase Trypanosoma cruzi infection.

IL-17A is a key cytokine that induces inflammatory responses through the organized production of inflammatory cytokines, such as IL-6, TNF-alpha, and GM-CSF, and induces neutrophil migration. The roles of IL-17A in infection of intracellular protozoan parasites have not been elucidated, although augmented immune responses by IL-17A are important for the resolution of some bacterial and fungal infections. Therefore, we experimentally infected IL-17A-deficient (IL-17A(-/-)) mice with Trypanosoma cruzi. IL-17A(-/-) mice had a lower survival rate and prolonged worse parasitemia compared with control C57BL/6 wild-type (WT) mice postinfection. In the infected IL-17A(-/-) mice, multiple organ failure was observed compared with WT mice, as reflected by the marked increase in serologic markers of tissue injury, such as aspartate aminotransferase, which resulted in increased mortality of IL-17A(-/-) mice. Expression of cytokines, such as IFN-gamma, IL-6, and TNF-alpha, was lower in liver-infiltrating cells from the IL-17A(-/-) mice compared with WT mice. A similar defect was observed in the expression of neutrophil enzymes, such as myeloperoxidase and lipoxygenase, whereas cellular infiltration into the infected tissues was not affected by IL-17A deficiency. These results suggested that the efficient activation of immune-related cells critical for the killing of T. cruzi was impaired in the absence of IL-17A, resulting in the greater susceptibility of those mice to T. cruzi infection. From these results, we conclude that IL-17A is important for the resolution of T. cruzi infection.

Exacerbation of delayed-type hypersensitivity responses in EBV-induced gene-3 (EBI-3)-deficient mice.

Epstein-Barr virus-induced gene-3 (EBI-3) associates with p28 to form interleukin-27 (IL-27) or with IL-12p35 to form IL-35. Both IL-27 and IL-35 have immunosuppressive functions and especially IL-35 has been implicated in the suppressive function of regulatory T cells (Treg). To address the role of EBI-3 in immune regulation, delayed-type hypersensitivity (DTH) responses were examined in EBI-3-deficient (EBI-3(-/-)) mice. EBI-3(-/-) mice developed deteriorated DTH responses as shown by the enhanced footpad swelling and augmented infiltration of inflammatory cells into the antigen-challenged footpads as compared with wild-type (WT) mice. While EBI-3-deficiency showed little effects on antigen-specific IFN-gamma production of lymph node cells, IL-17 production was drastically augmented in EBI-3(-/-) cells as compared with in WT cells. In addition, reduced IL-10 production was also evident in EBI-3(-/-) CD4(+) T cells. Interestingly, the development and suppressive function of Treg to inhibit effector T cell proliferation was not affected by EBI-3-deficiency. These data clearly demonstrated the immunosuppressive function of EBI-3 and provided complementary evidence that EBI-3 and EBI-3-containing cytokines might be taken into consideration as potential targets for some immune-related diseases.

Tumor-specific cytotoxic T cell generation and dendritic cell function are differentially regulated by interleukin 27 during development of anti-tumor immunity.

Interleukin (IL-) 27 is a member of IL-12 cytokine family with Th1-promoting and anti-inflammatory effects. IL-27 has been shown to facilitate tumor-specific cytotoxic T lymphocyte (CTL) induction against various tumors. However, IL-27 suppresses cytokine production of lymphocytes and antigen-presenting function of dendritic cells (DCs). To examine the in vivo role of IL-27 in generation of anti-tumor immunity, we examined IL-27-mediated antitumor-effects using WSX-1 (IL-27 receptor alpha chain)-deficient (WSX-1(-/-)) mice. In WSX-1(-/-) mice inoculated with B16 melanoma cells, tumor growth was higher than in wild-type (WT) mice. Accordingly, tumor-specific CTL generation was lower in WSX-1(-/-) mice than in WT mice. CTL induction in WSX-1(-/-) mice was not restored by transfer of WT DCs pulsed with TRP2 peptide, indicating that IL-27 is directly required for generation of tumor-specific CTLs. However, when transferred into tumor-bearing mice, WSX-1(-/-) DCs pulsed with TRP2 peptide was more potent than WT DCs in tumor growth inhibition and generation of CTLs, indicating suppressive effects of IL-27 on DC function. Finally, the combination of WT CD8(+) T cells and KO DCs is more potent in generation of antigen-specific CTLs than any other combinations. Expression of perforin gene and percentages of tumor-specific CD8(+) T cells were also the highest in the combination of WT CD8+ T cells and WSX-1(-/-) DCs. It was thus revealed that IL-27 promotes CTL generation while suppressing DC function during generation of tumor immunity. The combination of WT T cells and IL-27 signal-defective DCs may have therapeutic potential against tumors.

Augmentation of antigen-presenting and Th1-promoting functions of dendritic cells by WSX-1(IL-27R) deficiency.

WSX-1 is the alpha subunit of the IL-27R complex expressed by T, B, NK/NKT cells, as well as macrophages and dendritic cells (DCs). Although it has been shown that IL-27 has both stimulatory and inhibitory effects on T cells, little is known on the role of IL-27/WSX-1 on DCs. LPS stimulation of splenic DCs in vivo resulted in prolonged CD80/CD86 expression on WSX-1-deficient DCs over wild-type DCs. Upon LPS stimulation in vitro, WSX-1-deficient DCs expressed Th1-promoting molecules higher than wild-type DCs. In an allogeneic MLR assay, WSX-1-deficient DCs were more potent than wild-type DCs in the induction of proliferation of and IFN-gamma production by responder cell proliferation. When cocultured with purified NK cells, WSX-1-deficient DCs induced higher IFN-gamma production and killing activity of NK cells than wild-type DCs. As such, Ag-pulsed WSX-1-deficient DCs induced Th1-biased strong immune responses over wild-type DCs when transferred in vivo. WSX-1-deficient DCs were hyperreactive to LPS stimulation as compared with wild-type DCs by cytokine production. IL-27 suppressed LPS-induced CD80/86 expression and cytokine production by DCs in vitro. Thus, our study demonstrated that IL-27/WSX-1 signaling potently down-regulates APC function and Th1-promoting function of DCs to modulate overall immune responses.

Estrogenic compounds suppressed interferon-gamma production in mouse splenocytes through direct cell-cell interaction.

Here, we reported the effects of 17beta-estradiol (E2), isoflavone genistein (Gen), and daidzein (Dai) on the production of interferon (IFN)-gamma by splenocytes isolated from C57BL/6N mice. When mouse splenocytes were stimulated with lipopolysaccharide, E2, Gen, and Dai suppressed the production of IFN-gamma. However, when only nonadherent cell populations of splenocytes were tested, none of these estrogenic compounds suppressed IFN-gamma production. This result indicates that IFN-gamma production by nonadherent cell populations of splenocytes treated with estrogens is regulated by adherent cell populations. Moreover, direct cell-cell interaction between both populations was necessary for suppression of IFN-gamma production by nonadherent populations. In addition, E2 conjugated with bovine serum albumin inhibited IFN-gamma production as well as E2. This result suggests that the plasma membrane-associated estrogen receptor plays a prominent role in this suppression mechanism.