Regulatory T cells (Treg) play a central role in counteracting inflammation and autoimmunity. A more complete understanding of cellular heterogeneity and the potential for lineage plasticity in human Treg subsets may identify markers of disease pathogenesis and facilitate the development of optimized cellular therapeutics. To better elucidate human Treg subsets, we conducted direct transcriptional profiling of CD4+FOXP3+Helios+ thymic-derived Treg (tTreg) and CD4+FOXP3+Helios− T cells, followed by comparison to CD4+FOXP3−Helios− T conventional (Tconv) cells. These analyses revealed that the coinhibitory receptor T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT) was highly expressed on tTreg. TIGIT and the costimulatory factor CD226 bind the common ligand CD155. Thus, we analyzed the cellular distribution and suppressive activity of isolated subsets of CD4+CD25+CD127lo/− T cells expressing CD226 and/or TIGIT. We observed TIGIT is highly expressed and upregulated on Treg following activation and in vitro expansion and is associated with lineage stability and suppressive capacity. Conversely, the CD226+TIGIT− population was associated with reduced Treg purity and suppressive capacity following expansion, along with a marked increase in IL-10 and effector cytokine production. These studies provide additional markers to delineate functionally distinct Treg subsets that may help direct cellular therapies and provide important phenotypic markers for assessing the role of Treg in health and disease.

Tuberculosis (TB) caused by Mycobacterium tuberculosis is one of the leading fatal infectious diseases. The development of TB vaccines has been recognized as a major public health priority by the World Health Organization. In this study, three candidate antigens, ESAT-6 (6kDa early secretory antigenic target) and Mtb72F (a fusion polyprotein from two TB antigens, Mtb32 and Mtb39) fused with cholera toxin B-subunit (CTB) and LipY (a cell wall protein) were expressed in tobacco and/or lettuce chloroplasts to facilitate bioencapsulation/oral delivery. Site-specific transgene integration into the chloroplast genome was confirmed by Southern blot analysis. In transplastomic leaves, CTB fusion proteins existed in soluble monomeric or multimeric forms of expected sizes and their expression levels varied depending upon the developmental stage and time of leaf harvest, with the highest-level of accumulation in mature leaves harvested at 6PM. The CTB-ESAT6 and CTB-Mtb72F expression levels reached up to 7.5% and 1.2% of total soluble protein respectively in mature tobacco leaves. Transplastomic CTB-ESAT6 lettuce plants accumulated up to 0.75% of total leaf protein. Western blot analysis of lyophilized lettuce leaves stored at room temperature for up to six months showed that the CTB-ESAT6 fusion protein was stable and preserved proper folding, disulfide bonds and assembly into pentamers for prolonged periods. Also, antigen concentration per gram of leaf tissue was increased 22 fold after lyophilization. Hemolysis assay with purified CTB-ESAT6 protein showed partial hemolysis of red blood cells and confirmed functionality of the ESAT-6 antigen. GM1-binding assay demonstrated that the CTB-ESAT6 fusion protein formed pentamers to bind with the GM1-ganglioside receptor. The expression of functional Mycobacterium tuberculosis antigens in transplastomic plants should facilitate development of a cost-effective and orally deliverable TB booster vaccine with potential for long-term storage at room temperature. To our knowledge, this is the first report of expression of TB vaccine antigens in chloroplasts.

Key Points• Terminally differentiated CD56 neg NK cells expand in children after chronic malaria exposure and in those diagnosed with eBL.• NK cells in eBL patients express high levels of MIP-1b in lieu of TNF-a, and normal NK cell profiles appear to be restored in eBL survivors.

During acute lymphocytic choriomeningitis virus infection, pathogen-specific CD8+ cytotoxic T lymphocytes undergo clonal expansion leading to viral clearance. Following this, the majority of pathogen-specific CD8+ T cells undergo apoptosis, leaving a small number of memory CD8+ T cells that persist long-term and provide rapid protection upon secondary infection. Whereas much is known about the cytokines and transcription factors that regulate the early effector phase of the antiviral CD8+ T cell response, the factors regulating memory T cell homeostasis and survival are not well understood. In this article, we show that the Runt-related transcription factor Runx2 is important for long-term memory CD8+ T cell persistence following acute lymphocytic choriomeningitis virus-Armstrong infection in mice. Loss of Runx2 in T cells led to a reduction in KLRG1lo CD127hi memory precursor cell numbers with no effect on KLRG1hi CD127lo terminal effector cell populations. Runx2 expression levels were transcriptionally regulated by TCR signal strength via IRF4, TLR4/7, and selected cytokines. These data demonstrate a CD8+ T cell–intrinsic role for Runx2 in the long-term maintenance of antiviral memory CD8+ T cell populations.

Type 1 Diabetes (T1D) is an autoimmune disorder characterized by aberrant T cell responses. Innate immune activation defects may facilitate a T helper 1 (Th1) phenotype. The cytokine IL-18 synergizes with IL-12 to induce IFNγ production and Th1 differentiation. The IL-18R subunit (IL18RAP) SNP rs917997 has been linked to decreased IL18RAP gene expression. Prior reports link rs917997 allele A with protection from T1D, and conversely with susceptibility to Celiac disease. However, few studies have investigated the IL-18 pathway in T1D. In this study, we analyzed responsiveness to IL-18 in T1D, and the effect of rs917997 genotype on IL18RAP gene expression post-activation. Upon IL-12 and IL-18 treatment, peripheral blood mononuclear cells from subjects carrying susceptibility alleles at rs917997 produced higher levels of IFNγ than those with protective genotypes. Additionally, the SNP modified IL18RAP surface protein expression by NK cells and gene expression in activated T cells. Taken together, these data suggest that the disease-associated rs917997 allele G permits hyperresponsiveness to IL-18, providing a novel target for therapeutic intervention in T1D.