Publications by authors named "Ai Ikejiri"

Most anti-influenza drugs currently used, such as oseltamivir and zanamivir, inhibit the enzymatic activity of neuraminidase. However, neuraminidase inhibitor-resistant viruses have already been identified from various influenza virus isolates. Here, we report the development of a class of macrocyclic peptides that bind the influenza viral envelope protein hemagglutinin, named iHA.

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H5N1 highly pathogenic avian influenza (H5N1 HPAI) virus causes elevated mortality compared with seasonal influenza viruses like H1N1 pandemic influenza (H1N1 pdm) virus. We identified a mechanism associated with the severe symptoms seen with H5N1 HPAI virus infection. H5N1 HPAI virus infection induced a decrease of dendritic cell number in the splenic extrafollicular T-cell zone and impaired formation of the outer layers of B-cell follicles, resulting in insufficient levels of antibody production after infection.

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IL-17-producing T helper (Th17) cells comprise a distinct Th subset involved in epithelial cell- and neutrophil-mediated immune responses against extracellular microbes. At the same time, Th17 cells play significant roles in the development of autoimmune diseases including rheumatoid arthritis and multiple sclerosis. Since the identification of Th17 cells approximately a decade ago, the molecular mechanisms of their differentiation have been intensively studied and a number of signaling cascades and transcription factors have been shown to be involved.

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The PI3K-Akt-mTORC1 axis contributes to the activation, survival, and proliferation of CD4(+) T cells upon stimulation through TCR and CD28. Here, we demonstrate that the suppression of this axis by deletion of p85α or PI3K/mTORC1 inhibitors as well as T cell-specific deletion of raptor, an essential component of mTORC1, impairs Th17 differentiation in vitro and in vivo in a S6K1/2-dependent fashion. Inhibition of PI3K-Akt-mTORC1-S6K1 axis impairs the downregulation of Gfi1, a negative regulator of Th17 differentiation.

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Naive CD4(+) T cells are activated by antigen-presenting cells (APCs) and differentiate into distinct types of helper T (T(h)) cells in the lymph node or spleen. Oxygen (O(2)) tension is generally low in these secondary lymphoid tissues compared with the bloodstream or atmosphere. However, the effect of changes in O(2) concentration on the differentiation of T(h) cells remains unclear.

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The aim of this study is to investigate the immunoadjuvant activity of the crude Momordica charantia lectin (crMCL) extracted from seed using beta-galactosidase (beta-gal) as the model antigen. BALB/c mice were injected intramuscularly with beta-gal alone or beta-gal + crMCL for up to four immunizations at two-week intervals. After administration of 2 doses, the IgG-specific titer to beta-gal was significantly higher in mice in the beta-gal + crMCL group than in that from the animals from the beta-gal alone group, while it was about the same in both groups after 1 dose.

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The ability of live attenuated Salmonella enterica serovar typhimurium (S. typhimurium) as a carrier of DNA vaccine was evaluated using model plasmid encoding beta-galactosidase (beta-Gal) and BALB/c mice. We constructed pBRCMVbeta, beta-Gal expression apparatus having a replication origin from low copy pBR322.

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