CD8+GITR+ T cells may negatively regulate T cell overactivation in aplastic anemia.

Aplastic anemia (AA) is a T cell immune-mediated autoimmune disease. Overactivated CD8+ T cells play a leading role in the pathogenesis of AA, which may be due to disbalance in costimulatory and coinhibitory signals in T cells. In this study, we firstly investigated the expression of OX40, 4-1BB, GITR, ICOS, CTLA-4, LAG-3, and TIM-3 on CD8+ T cells from untreated patients with AA and healthy individuals (HIs) by flow cytometry. Moreover, we further analyzed the phenotype and functional characteristics of CD8+GITR+ T cells to more fully assess the T cell activation dysfunction in AA. We for the first time demonstrated significantly decreased percentage of CD8+GITR+ T cells in AA, and CD8+GITR+CTLA-4+ T cells were significantly higher in patients with AA compared with HIs. Conversely, the percentage of CD8+GITR+granzyme B+ and CD8+GITR+perforin+ T cells in AA patients was significantly reduced. Our preliminary data illustrate that the CD8+GITR+ T cell population might negatively regulate overactive T cell activation in AA.

Increased CD8+CD27+perforin+ T cells and decreased CD8+CD70+ T cells may be immune biomarkers for aplastic anemia severity.

OBJECTIVES: Aplastic anemia (AA) is T cell immune-mediated autoimmune disease. Aberrant T cell activation involves an imbalance in T cell homeostasis in AA. However, whether the T cell activation molecule CD27 and its ligand CD70 participate in the immune pathogenesis of AA remains ill defined. METHODS: The frequencies of CD27/CD70 and perforin/granzyme B in different T cell subsets were detected in AA patients and healthy individuals by flow cytometry. RESULTS: We first time demonstrate a significantly elevated proportion of CD27+ and significantly decreased CD70+ T cells from AA. Changed frequency of CD27+ and CD70+ in different T cell subsets appeared to be associated with AA severity. In very severe aplastic anemia (VSAA) and severe aplastic anemia (SAA), increased CD8+CD27+ T cells present with a cytotoxic effector phenotype by elevating perforin proportion. CONCLUSIONS: Elevated proportion of CD27 in T cells may contribute to distinct immune pathogenesis for different severities of AA. The CD8+CD27+perforin+ T cells combined with CD8+CD70+ T cells may serve as an immune biomarker for AA severity estimation.

MiR-214 regulates CD3ζ expression in T cells.

INTRODUCTION: T-cell activation requires the T-cell receptor (TCR)-CD3 complex, which integrates and transduces signals. CD3ζ plays a vital role in TCR signalling by mediating T-cell activation. Abnormal CD3ζ expression is a common characteristic of haematological malignancies with T-cell immune dysfunction or autoimmune diseases. Targeted regulation of CD3ζ expression by either direct or indirect approaches is important for regulating T-cell activation. AIM OF THE STUDY: In this study, we focused on identifying miRNAs that may regulate CD3ζ expression. MATERIAL AND METHODS: Three microRNA target search algorithms (TargetScan, PicTar, and microrna.org) were used to identify hypothetical miRNAs that target CD3ζ in T cells. Of the predicted miRNAs, miR-214 was chosen and validated to determine whether miR-214 directly binds to the CD3ζ 3'-UTR and regulates CD3ζ expression by luciferase reporter assays, real-time PCR, and Western blotting. RESULTS: The results indicate that miR-214 specifically binds the CD3ζ 3'-UTR, and miR-214 mimics remarkably reduce the expression of CD3ζ in MOLT-4 cells. CONCLUSIONS: We identify for the first time that miR-214 targets expression in MOLT-4 cells, suggesting that miR-214 might negatively regulate T-cell activation by targeting CD3ζ.

Increased IFN-γ+ and TNF-α+ mucosal-associated invariant T cells in patients with aplastic anemia.

BACKGROUND: Aplastic anemia (AA) is known as an autoimmune disease in which T cell activation is aberrant. It has been reported that unconventional T cells, mucosal-associated invariant T (MAIT) cells, play an important role in several autoimmune diseases, but it is unclear if they are involved in AA. METHODS: In this study, we for the first time analyzed the proportions, phenotypes, and cytokine properties of MAIT cells in AA by flow cytometry. RESULTS: We found that the percentage of circulating MAIT cells was generally higher for CD3+ , CD8+ , and CD8- T cells in AA patients compared with healthy individuals. Moreover, the percentage of IL-18Rα-, NKG2D-, IFN-γ-, and TNF-α- positive MAIT cells was also significantly higher in AA patients. In addition, the percentage of IFN-γ+ CD3+ or TNF-α+ CD8- MAIT cells had a significant negative correlation with the absolute neutrophil count. CONCLUSIONS: We present the first observation of MAIT cells in patients with AA. MAIT cells are associated with a higher frequency of IFN-γ and TNF-α production and may contribute to the pathogenesis of AA.

Abnormal miR-214/A20 expression might play a role in T cell activation in patients with aplastic anemia.

Aberrant T cell activation is a major cause of aplastic anemia (AA) pathogenesis. Recent studies have shown that miRNAs regulate T cell activation and are involved in AA. A previous study found that miR-214 was significantly up-regulated upon T cell activation in a CD28-dependent fashion by targeting PTEN. However, the expression characteristics of miR-214 and its target genes in AA have not been defined. In this study, target genes for miR-214 were predicted and confirmed by bioinformatics and luciferase reporter assays. The expression levels of miR-214 and target genes were detected in 36 healthy individuals and 35 patients with AA in peripheral blood mononuclear cells by real-time quantitative reverse transcriptase-polymerase chain reaction. Bioinformatics and luciferase reporter assays identified that miR-214 could bind to the A20 3' untranslated regions. Significantly increased miR-214 and the decreased A20 expression level were detected in the AA patients compared with the healthy group. In addition, significantly increased miR-214 was found in non-severe aplastic anemia compared with severe aplastic anemia patients. These results suggested that the A20 gene was a potential target of miR-214, and elevated miR-214 might medicate T cell activation at least in part by regulating A20 expression in AA. We firstly confirmed that miR-214 regulated A20 expression, and aberrant miR-214/A20 expression might contribute to immunopathology in AA. The miR-214 expression might be used as a potential biomarker that assisted in diagnosing AA severity.