Suppressive effects of vitamin C-treated induced-regulatory T cells on heart allograft rejection under vitamin C-deficient or -sufficient conditions.

Foxp3 stability of vitamin C-treated induced-regulatory T cells (V-iTregs) is superior to that of conventional iTregs (C-iTregs). However, the role of V-iTregs in allograft rejection under vitamin C-deficient conditions, such as those seen in humans, remains unclear. We aimed to elucidate the role of vitamin C treatment on generation and maintenance of iTregs from gulo knockout (Gulo-KO) mice as well as wild type (WT) mice, and in vitro and in vivo suppressive effects of V-iTregs on heart allograft rejection in either Gulo-KO or WT recipient mice.

The mTORC1/4E-BP/eIF4E Axis Promotes Antibody Class Switching in B Lymphocytes.

During an adaptive immune response, activated mature B cells give rise to Ab-secreting plasma cells to fight infection. B cells undergo Ab class switching to produce different classes of Abs with varying effector functions. The mammalian/mechanistic target of rapamycin (mTOR) signaling pathway is activated during this process, and disrupting mTOR complex 1 (mTORC1) in B cells impairs class switching by a poorly understood mechanism.

IL2 is required for functional maturation of regulatory T cells.

Regulatory T cells (Tregs), specified by the expression of transcription factor Foxp3, operate Foxp3-dependent programs to maintain self-tolerance. In addition to Foxp3, other tissue-specific transcription factors are also required by Tregs to control the corresponding immune responses like follicular Tregs which express both Foxp3 and Bcl6 controlling germinal center reactions. Here, we show that Interleukin 2 (IL2) is required for the optimal expression of T helper type 1 (Th1) transcription factor T-box 21 (, T-bet) in Tregs.

DNA Demethylation of the Foxp3 Enhancer Is Maintained through Modulation of Ten-Eleven-Translocation and DNA Methyltransferases.

Stable expression of Foxp3 is ensured by demethylation of CpG motifs in the intronic element, the conserved non-coding sequence 2 (CNS2), which persists throughout the lifespan of regulatory T cells (Tregs). However, little is known about the mechanisms on how CNS2 demethylation is sustained. In this study, we found that Ten-Eleven-Translocation (Tet) DNA dioxygenase protects the CpG motifs of CNS2 from re-methylation by DNA methyltransferases (Dnmts) and prevents Tregs from losing Foxp3 expression under inflammatory conditions.

Vitamin C enhances the expression of IL17 in a Jmjd2-dependent manner.

Previously, we reported that vitamin C facilitates the CpG demethylation of Foxp3 enhancer in CD4＋Foxp3＋ regulatory T cells (Tregs) by enhancing the activity of a DNA demethylase ten-eleven-translocation (Tet). However, it is not clear whether vitamin C affects other helper T cell lineages like T helper type 17 (Th17) cells which are related with Tregs. Here, we show that the expression of interleukin-17A (IL17) increases with the treatment of vitamin C but not with other antioxidants.

Vitamin C Facilitates Demethylation of the Foxp3 Enhancer in a Tet-Dependent Manner.

Demethylation of CpG motifs in the Foxp3 intronic element, conserved noncoding sequence 2 (CNS2), is indispensable for the stable expression of Foxp3 in regulatory T cells (Tregs). In this study, we found that vitamin C induces CNS2 demethylation in Tregs in a ten-eleven-translocation 2 (Tet2)-dependent manner. The CpG motifs of CNS2 in Tregs generated in vitro by TGF-β (iTregs), which were methylated originally, became demethylated after vitamin C treatment.

Down-regulation of Tet2 prevents TSDR demethylation in IL2 deficient regulatory T cells.

Stable expression of Foxp3 in regulatory T (Treg) cells is dependent on both intrinsic factors like epigenetic changes (demethylation) of Treg cell specific demethylation region (TSDR) and environmental cues like inflammations. Interleukin-2 (IL2) was reported to be one of the cytokines that give signals to Foxp3 stability but the underlying mechanism is still elusive. Here we show that IL2 and epigenetic changes in foxp3 locus are closely connected through tet methylcytosine dioxygenase 2 (Tet2) and, together help Treg cells to express Foxp3 stably.

Calcium/Calmodulin-Dependent Protein Kinase is Involved in the Release of High Mobility Group Box 1 Via the Interferon-β Signaling Pathway.

Previously, we have reported that high mobility group box 1 (HMGB1), a proinflammatory mediator in sepsis, is released via the IFN-β-mediated JAK/STAT pathway. However, detailed mechanisms are still unclear. In this study, we dissected upstream signaling pathways of HMGB1 release using various molecular biology methods.

Expression pattern of immunoproteasome subunits in human thymus.

The expression pattern of immunoproteasomes in human thymus has not been analyzed but may have important consequences during thymic selection. Here we examined the expression patterns of immunoproteasome subunits in fetal and adult thymic tissues by immunohistochemistry and found that all three subunits are expressed in both cortical and medullary stromal cells. These data suggest that thymic selection in human can be affected by peptide repertoires generated by immunoproteasomes.

Bacterial endotoxin induces the release of high mobility group box 1 via the IFN-beta signaling pathway.

Sepsis is a devastating condition characterized by a systemic inflammatory response. Recently, high mobility group box 1 (HMGB1) was identified as a necessary and sufficient mediator of the lethal systemic inflammation caused by sepsis. However, despite its clinical importance, the mechanism of HMGB1 release has remained to be elusive.

CD99 activates T cells via a costimulatory function that promotes raft association of TCR complex and tyrosine phosphorylation of TCR zeta.

We investigated the co-stimulatory role of a cell-surface protein, CD99. Co-ligation of CD99 and suboptimal CD3 induced T-cell activation to a level comparable to that obtained with optimal CD3 or CD3+CD28. We also noted concomitant enhancement of the earliest T-cell receptor (TCR) signaling events.

Delayed allograft rejection by the suppression of class II transactivator.

(CIITA) down-modulation on allograft rejection. To inhibit the function of CIITA, we constructed a series of CIITA mutants and found one exhibiting the dominant-negative effect on the regulation of major histocompatibility complex (MHC) class II expression. To test whether the CIITA dominant-negative mutant reduces immunogenicity, CIITA-transfected melanoma cells were injected into allogeneic host and assessed for immune evading activity against host immune cells.

Involvement of lymphocytes in dextran sulfate sodium-induced experimental colitis.

Aim: To investigate the roles of lymphocytes in the development of dextran sulfate sodium-induced colitis.

Methods: Using various doses of dextran sulfate sodium (DSS), we induced colitis in wild-type B6 control and Rag-1 knockout (H-2b haplotype) mice, and evaluated the colitis in terms of symptomatic and histologic parameters, such as weight loss, survival, severity of diarrhea, shortage of colon length and histological changes. Symptomatic parameters were checked daily and histological changes were scored.

Cloning, genomic organization, alternative transcripts and expression analysis of CD99L2, a novel paralog of human CD99, and identification of evolutionary conserved motifs.

Human CD99 (MIC2) is a 32 kDa cell surface protein and its encoding gene is localized to the pseudoautosomal regions of both Xp and Yp chromosomes. Although sequences of several genes such as human PBDX and MIC2R are known to be related to that of CD99, the murine counterpart of CD99 has not been reported. Here we have identified a novel CD99 mouse paralog, named as CD99L2 (CD99 antigen-like 2), and its human, rat and zebrafish genes.

The enhanced reactivity of endogenous biotin-like molecules by antigen retrieval procedures and signal amplification with tyramine.

In diagnostic pathology and immunocytochemical research, immunohistochemical techniques using the streptavidin-biotin-peroxidase system have played an extremely valuable role. This system, based on the high affinity of streptavidin for biotin, may, however, provoke false positive results because of endogenous streptavidin-binding sites in human tissues. With the advent of the antigen retrieval procedure and signal amplification method, this problem can be serious enough to cause mistakes in interpreting immunohistochemical staining results.

Mutations of the immunoglobulin heavy chain variable region gene in CD99-deficient BJAB cell line.

Hodgkin's disease (HD) is a lymphoid neoplasm characterized by a low frequency of malignant giant tumor cells, known as Hodgkin's and Reed-Sternberg (HRS) cells. Sequence analysis of the immunoglobulin heavy chain hypervariable region (IgH V) genes of HRS cells revealed multiple nucleotide substitutions, indicating somatic mutations, and suggested that HRS cells originate from germinal center B cells or their progeny. We previously reported that CD99-antisense transfected B cell lines led to the generation of cells with a HRS phenotype.