Yurie Takahashi

Defect of CARD9 Leads to Impaired Accumulation of Gamma Interferon-Producing Memory Phenotype T Cells in Lungs and Increased Susceptibility to Pulmonary Infection with Cryptococcus neoformans

ABSTRACT Caspase recruitment domain-containing protein 9 (CARD9) is an adaptor molecule signal that is critical for NF-κB activation and is triggered through C-type lectin receptors (CLRs), which are pattern recognition receptors that recognize carbohydrate structures. Previous studies have reported that Cryptococcus neoformans, a fungal pathogen that causes meningoencephalitis in AIDS patients, is recognized through some CLRs, such as mannose receptors or DC-SIGN. However, the role of CARD9 in the host defense against cryptococcal infection remains to be elucidated. In the present study, we analyzed the role of CARD9 in the host defense against pulmonary infection with C. neoformans. CARD9 gene-disrupted (knockout [KO]) mice were highly susceptible to this infection, as shown by the reduced fungal clearance in the infected lungs of CARD9 KO mice, compared to that in wild-type (WT) mice. Gamma interferon (IFN-γ) production was strongly reduced in CARD9 KO mice during the innate-immunity phase of infection. Reduced IFN-γ synthesis was due to impaired accumulation of NK and memory phenotype T cells, which are major sources of IFN-γ innate-immunity-phase production; a reduction in the accumulation of these cells was correlated with reduced CCL4, CCL5, CXCL9, and CXCL10 synthesis. However, differentiation of Th17 cells, but not of Th1 cells, was impaired at the adaptive-immunity phase in CARD9 KO mice compared to WT mice, although there was no significant difference in the infection susceptibility between interleukin 17A (IL-17A) KO and WT mice. These results suggest that CARD9 KO mice are susceptible to C. neoformans infection probably due to the reduced accumulation of IFN-γ-expressing NK and memory phenotype T cells at the early stage of infection.

Toll-Like Receptor 9-Dependent Activation of Bone Marrow-Derived Dendritic Cells by URA5 DNA from Cryptococcus neoformans

ABSTRACT Cryptococcus neoformans is an opportunistic fungal pathogen that causes meningoencephalitis in immunocompromised patients. Recently, we reported that Toll-like receptor 9 (TLR9) is involved in host defense against C. neoformans: specifically, it detects the pathogens DNA. In the present study, we aimed to elucidate the mechanisms underlying TLR9-mediated activation of innate immune responses by using the URA5 gene, which encodes a virulent component of this fungal pathogen. A PCR-amplified 345-bp URA5 gene fragment induced interleukin-12 p40 (IL-12p40) production by bone marrow-derived dendritic cells (BM-DCs) in a TLR9-dependent manner. Similar activity was detected in the 5′ 129-bp DNA fragment of URA5 and in a synthesized oligodeoxynucleotide (ODN) with the same sequence. Shorter ODN fragments, which contained GTCGGT or GACGAT but had only 24 or 21 bases, induced IL-12p40 production and CD40 expression by BM-DCs, but this activity vanished when the CG sequence was replaced by GC or when a phosphorothioate modification was introduced. IL-12p40 production caused by active ODN was strikingly enhanced by treatment with DOTAP, a cationic lipid that increases the uptake of DNA by BM-DCs, though DOTAP failed to induce IL-12p40 production by inactive ODN and did not affect the activity of an ODN-containing canonical CpG motif. There was no apparent difference in intracellular trafficking between active and inactive ODNs. Finally, an extremely high dose of inactive ODN suppressed IL-12p40 production by BM-DCs that had been stimulated with active ODN. These results suggest that the C. neoformans URA5 gene activates BM-DCs through a TLR9-mediated signaling pathway, using a mechanism possibly independent of the canonical CpG motif.

The sphingosine 1-phosphate receptor modulator FTY720 prevents iodide-induced autoimmune thyroiditis in non-obese diabetic mice.

FTY720 is an immunomodulator that alters migration and homing of lymphocytes via sphingosine 1-phosphate receptors. This compound has been shown to be effective in suppressing autoimmune diseases in experimental and clinical settings. In the present study, we tested whether FTY720 prevented autoimmune thyroiditis in iodide-treated non-obese diabetic (NOD) mice, a model of Hashimotos thyroiditis (HT) in humans. Mice were given 0.05% iodide water for 8 weeks, and this treatment effectively induced thyroiditis. Iodide-treated mice were injected intraperitoneally with either saline or FTY720 during the iodide treatment. FTY720 clearly suppressed the development of thyroiditis and reduced serum anti-thyroglobulin antibody levels. The number of circulating lymphocytes and spleen cells including CD4+ T cells, CD8+ T cells, and CD4+Foxp3+ T cells was decreased in FTY720-treated mice. Our results indicate that FTY720 has immunomodulatory effects on iodide-induced autoimmune thyroiditis in NOD mice and may be a potential candidate for use in the prevention of HT.

Effects of synthetic retinoid Am80 on iodide-induced autoimmune thyroiditis in nonobese diabetic mice

We examined whether a synthetic retinoid Am80 prevented the development of autoimmune thyroiditis in iodide-treated nonobese diabetic mice, an animal model of Hashimotos thyroiditis (HT). Am80 (0, 0.1 or 1 mg/kg/day) was orally administered in feed during the 8-week iodide treatment. While iodide ingestion effectively induced thyroiditis, Am80 administration failed to interfere with thyroiditis development and serum anti-thyroglobulin antibody levels regardless of the dose of the retinoid. Splenic T cell numbers, splenocyte proliferation and interferon-γ production were decreased in the Am80-treated mice. Our data suggest that Am80 is not a candidate for use in the prevention of HT.

Effects of green tea polyphenols on iodide-induced autoimmune thyroiditis in nonobese diabetic mice.

Because green tea polyphenols (GTPs) possess anti-inflammatory properties and are effective in inhibiting autoimmune diseases in experimental settings, we examined whether GTPs prevented the development of autoimmune thyroiditis in iodide-treated nonobese diabetic (NOD) mice, an animal model of Hashimoto’s thyroiditis (HT). Mice were given 0.05% iodide water or iodide water supplemented with 0.2% GTPs for 8 weeks. GTPs administration led to an enhanced production of interleukin-10 by concanavalin A-stimulated splenocytes but did not interfere with thyroiditis development. Serum thyroxine levels were not influenced by GTPs. Our data suggest that administration of GTPs may not be an effective strategy for the prevention of HT.

Experimental autoimmune thyroiditis in human parvovirus B19 transgenic mice.

Viral infection is implicated as a cause of autoimmune diseases. Whereas its role in Hashimotos thyroiditis (HT) remains undefined, recent studies suggested a link between human parvovirus B19 (B19) infection and HT. We tested such possibility by using B19 nonstructural protein 1 (NS1) transgenic C57BL/6 mice, which harbor nonpermissive genetic background (H-2b). Mice were immunized with either thyroglobulin (Tg) or saline. No thyroiditis developed in saline-treated mice and Tg-immunized males regardless of the presence or absence of NS1. In contrast, thyroiditis was induced by Tg immunization in 25% of transgenic females, but not in wild-type females. However, the thyroiditis incidence in the former did not differ significantly from that of the latter. In addition, intrathyroidal T-cell receptor gene expression was not augmented in Tg-immunized transgenic females. Immunization with Tg led to a comparable increase in serum anti-Tg antibody levels in the wild-type and transgenic mice. Our results indicate that the introduction of B19 NS1 gene into C57BL/6 mice is insufficient to promote the development of autoimmune thyroiditis. Further studies are required, however, before concluding that B19 infection is not involved in HT induction.

sup 14 C( p , n ) sup 14 N reaction at E sub p =35 MeV

Differential cross sections for the {sup 14}C({ital p},{ital n}){sup 14}N reaction were measured at {ital E}{sub {ital p}}=35 MeV. A number of spin-isospin excitations have been observed including Gamow-Teller-type 0{sup +}{r arrow}1{sup +} and 0{h bar}{omega} and 1{h bar}{omega} jump stretched transitions. Distorted-wave Born-approximation calculations using shell-model wave functions have successfully reproduced the experimental results. Renormalization factors of about 0.5 were required for the spin-flip transitions leading to the 3.947-MeV 1{sup +} state and to the 7.026-MeV 2{sup +} state, where {Delta}{ital J}({Delta}{ital L},{Delta}{ital S})=1(0,1) and 2(2,1), respectively. Proton and neutron optical-potential parameters were derived in the course of the present work.