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Human B cell antigen-receptor (BCR) repertoires reflect repeated exposures to evolving influenza viruses; new exposures update the previously generated B cell memory (Bmem) population. Despite structural similarity of hemagglutinins (HAs) from the two groups of influenza A viruses,cross-reacting antibodies (Abs) are uncommon. We analyzed Bmem compartments in three unrelated,adult donors and found frequent cross-group BCRs,both HA-head directed and non-head directed. Members of a clonal lineage from one donor had a BCR structure similar to that of a previously described Ab,encoded by different gene segments. Comparison showed that both Abs contacted the HA receptor-binding site through long heavy-chain third complementarity determining regions. Affinities of the clonal-lineage BCRs for historical influenza-virus HAs from both group 1 and group 2 viruses suggested that serial responses to seasonal influenza exposures had elicited the lineage and driven affinity maturation. We propose that appropriate immunization regimens might elicit a comparably broad response. View Publication

Dendritic cells (DCs) are a heterogeneous population of professional antigen-presenting cells and are key cells of the immune system,acquiring different phenotypes in accordance with their localization during the immune response. A subset of inflammatory DCs is derived from circulating monocytes (Mo) and has a key role in inflammation and infection. The pathways controlling Mo-DC differentiation are not fully understood. Our objective was to investigate the possible role of nicotinamide adenine dinucleotide phosphate reduced form oxidases (NOXs) in Mo-DC differentiation. In this study,we revealed that Mo-DC differentiation was inhibited by NOX inhibitors and reactive oxygen species scavengers. We show that the Mo-DC differentiation was dependent on p22phox,and not on gp91phox/NOX2,as shown by the reduced Mo-DC differentiation observed in chronic granulomatous disease patients lacking p22phox. Moreover,we revealed that NOX5 expression was strongly increased during Mo-DC differentiation,but not during Mo-macrophage differentiation. NOX5 was expressed in circulating myeloid DC,and at a lower level in plasmacytoid DC. Interestingly,NOX5 was localized at the outer membrane of the mitochondria and interacted with p22phox in Mo-DC. Selective inhibitors and small interfering RNAs for NOX5 indicated that NOX5 controlled Mo-DC differentiation by regulating the JAK/STAT/MAPK and NFκB pathways. These data demonstrate that the NOX5-p22phox complex drives Mo-DC differentiation,and thus could be critical for immunity and inflammation. View Publication

Improved understanding of expression of immune checkpoint receptors (ICR) on tumor-infiltrating lymphocytes (TIL) may facilitate more effective immunotherapy in head and neck cancer (HNC) patients. A higher frequency of PD-1+ TIL has been reported in human papillomavirus (HPV)+ HNC patients,despite the role of PD-1 in T-cell exhaustion. This discordance led us to hypothesize that the extent of PD-1 expression more accurately defines T-cell function and prognostic impact,because PD-1high T cells may be more exhausted than PD-1low T cells and may influence clinical outcome and response to anti-PD-1 immunotherapy. In this study,PD-1 expression was indeed upregulated on HNC patient TIL,and the frequency of these PD-1+ TIL was higher in HPV+ patients (P = 0.006),who nonetheless experienced significantly better clinical outcome. However,PD-1high CD8+ TILs were more frequent in HPV- patients and represented a more dysfunctional subset with compromised IFN-γ secretion. Moreover,HNC patients with higher frequencies of PD-1high CD8+ TIL showed significantly worse disease-free survival and higher hazard ratio for recurrence (P < 0.001),while higher fractions of PD-1low T cells associated with HPV positivity and better outcome. In a murine HPV+ HNC model,anti-PD-1 mAb therapy differentially modulated PD-1high/low populations,and tumor rejection associated with loss of dysfunctional PD-1high CD8+ T cells and a significant increase in PD-1low TIL. Thus,the extent of PD-1 expression on CD8+ TIL provides a potential biomarker for anti-PD-1-based immunotherapy. Cancer Res; 77(22); 6353-64. textcopyright2017 AACR. View Publication

Droplet single-cell RNA-sequencing (dscRNA-seq) has enabled rapid,massively parallel profiling of transcriptomes. However,assessing differential expression across multiple individuals has been hampered by inefficient sample processing and technical batch effects. Here we describe a computational tool,demuxlet,that harnesses natural genetic variation to determine the sample identity of each droplet containing a single cell (singlet) and detect droplets containing two cells (doublets). These capabilities enable multiplexed dscRNA-seq experiments in which cells from unrelated individuals are pooled and captured at higher throughput than in standard workflows. Using simulated data,we show that 50 single-nucleotide polymorphisms (SNPs) per cell are sufficient to assign 97% of singlets and identify 92% of doublets in pools of up to 64 individuals. Given genotyping data for each of eight pooled samples,demuxlet correctly recovers the sample identity of<99% of singlets and identifies doublets at rates consistent with previous estimates. We apply demuxlet to assess cell-type-specific changes in gene expression in 8 pooled lupus patient samples treated with interferon (IFN)-β and perform eQTL analysis on 23 pooled samples. View Publication

IL2 is an immunostimulatory cytokine for key immune cells including T cells and natural killer (NK) cells. Systemic IL2 supplementation could enhance NK-mediated immunity in a variety of diseases ranging from neoplasms to viral infection. However,its systemic use is restricted by its serious side effects and limited efficacy due to activation of T regulatory cells (Tregs). IL2 signaling is mediated through interactions with a multi-subunit receptor complex containing IL2Rα,IL2Rβ,and IL2Rγ. Adult natural killer (NK) cells express only IL2Rβ and IL2Rγ subunits and are therefore relatively insensitive to IL2. To overcome these limitations,we created a novel chimeric IL2-IL2Rβ fusion protein of IL2 and its receptor IL2Rβ joined via a peptide linker (CIRB). NK92 cells expressing CIRB (NK92CIRB) were highly activated and expanded indefinitely without exogenous IL2. When compared with an IL2-secreting NK92 cell line,NK92CIRB were more activated,cytotoxic,and resistant to growth inhibition. Direct contact with cancer cells enhanced the cytotoxic character of NK92CIRB cells,which displayed superior in vivo antitumor effects in mice. Overall,our results showed how tethering IL2 to its receptor IL2Rβ eliminates the need for IL2Rα and IL2Rβ,offering a new tool to selectively activate and empower immune therapy. Cancer Res; 77(21); 5938-51. textcopyright2017 AACR. View Publication

Efforts to improve the efficacy of adoptive T-cell therapies and immune checkpoint therapies in myelogenous leukemia are desired. In this study,we evaluated the antileukemia activity of adoptively transferred polyclonal cancer antigen-reactive T cells deficient in the regulator diacylglycerol kinase zeta (DGKζ) with or without PD-1/PD-L1 blockade. In the C1498 mouse model of myeloid leukemia,we showed that leukemia was eradicated more effectively in DGKζ-deficient (DGKζ-/-) mice than wild-type mice. T cells transferred from DGKζ-deficient mice to wild-type tumor-bearing recipients conferred this benefit. Leukemia clearance was similar to mice treated with anti-PD-L1. Strikingly,we found that the activity of adoptively transferred DGKζ-/- T cells relied partly on induction of sustainable host T-cell immunity. Transferring DGKζ-deficient T cells increased the levels of IFNγ and other cytokines in recipient mice,especially with coadministration of anti-PD-L1. Overall,our results offered evidence that targeting DGKζ may leverage the efficacy of adoptive T-cell and immune checkpoint therapies in leukemia treatment. Furthermore,they suggest that DGKζ targeting might decrease risks of antigen escape or resistance to immune checkpoint blockade. Cancer Res; 77(20); 5676-86. textcopyright2017 AACR. View Publication

The control of uptake and utilization of necessary extracellular nutrients-glucose and glutamine-is an important aspect of B cell activation. Let-7 is a family of microRNAs known to be involved in metabolic control. Here,we employed several engineered mouse models,including B cell-specific overexpression of Lin28a or the let-7a-1/let-7d/let-7f-1 cluster (let-7adf) and knockout of individual let-7 clusters to show that let-7adf specifically inhibits T cell-independent (TI) antigen-induced immunoglobulin (Ig)M antibody production. Both overexpression and deletion of let-7 in this cluster leads to altered TI-IgM production. Mechanistically,let-7adf suppresses the acquisition and utilization of key nutrients,including glucose and glutamine,through directly targeting hexokinase 2 (Hk2) and by repressing a glutamine transporter Slc1a5 and a key degradation enzyme,glutaminase (Gls),a mechanism mediated by regulation of c-Myc. Our results suggest a novel role of let-7adf as a metabolic brake" on B cell antibody production." View Publication

Although most novel tuberculosis (TB) vaccines are designed for delivery via the muscle or skin for enhanced protection in the lung,it has remained poorly understood whether systemic vaccine-induced memory T cells can readily home to the lung mucosa prior to and shortly after pathogen exposure. We have investigated this issue by using a model of parenteral TB immunization and intravascular immunostaining. We find that systemically induced memory T cells are restricted to the blood vessels in the lung,unable to populate either the lung parenchymal tissue or the airway under homeostatic conditions. We further find that after pulmonary TB infection,it still takes many days before such T cells can enter the lung parenchymal tissue and airway. We have identified the acquisition of CXCR3 expression by circulating T cells to be critical for their entry to these lung mucosal compartments. Our findings offer new insights into mucosal T cell biology and have important implications in vaccine strategies against pulmonary TB and other intracellular infections in the lung. View Publication

Priming of human NK cells with IL-2 is necessary to render them functionally competent upon NKG2D engagement. We examined the underlying mechanisms that control NKG2D responsiveness in NK cells and found that IL-2 upregulates expression of the amino acid transporters SLC1A5 and CD98. Using specific inhibitors to block SLC1A5 and CD98 function,we found that production of IFN-γ and degranulation by CD56bright and CD56dim NK cells following NKG2D stimulation were dependent on both transporters. IL-2 priming increased the activity of mTORC1,and inhibition of mTORC1 abrogated the ability of the IL-2-primed NK cells to produce IFN-γ in response to NKG2D-mediated stimulation. This study identifies a series of IL-2-induced cellular changes that regulates the NKG2D responsiveness in human NK cells. View Publication

The presence of persistent,latent HIV reservoirs in CD4+ T cells obstructs current efforts to cure infection. The so-called kick-and-kill paradigm proposes to purge these reservoirs by combining latency-reversing agents with immune effectors such as cytotoxic T lymphocytes. Support for this approach is largely based on success in latency models,which do not fully reflect the makeup of latent reservoirs in individuals on long-term antiretroviral therapy (ART). Recent studies have shown that CD8+ T cells have the potential to recognize defective proviruses,which comprise the vast majority of all infected cells,and that the proviral landscape can be shaped over time due to in vivo clonal expansion of infected CD4+ T cells. Here,we have shown that treating CD4+ T cells from ART-treated individuals with combinations of potent latency-reversing agents and autologous CD8+ T cells consistently reduced cell-associated HIV DNA,but failed to deplete replication-competent virus. These CD8+ T cells recognized and potently eliminated CD4+ T cells that were newly infected with autologous reservoir virus,ruling out a role for both immune escape and CD8+ T cell dysfunction. Thus,our results suggest that cells harboring replication-competent HIV possess an inherent resistance to CD8+ T cells that may need to be addressed to cure infection. View Publication