Scientific Resources

OBJECTIVES We sought to develop medium throughput standard operating procedures for screening cryopreserved human peripheral blood mononuclear cells (PBMCs) for CD4+ and CD8+ T cell responses to potential autoantigens. METHODS Dendritic cells were loaded with a peptide cocktail from ubiquitous viruses or full-length viral protein antigens and cocultured with autologous T cells. We measured expression of surface activation markers on T cells by flow cytometry and cytometry by time of flight 24-72 h later. We tested responses among T cells freshly isolated from healthy control PBMCs,cryopreserved T cells,and T cells derived from a variety of T cell expansion protocols. We also compared the transcriptional profile of CD8+ T cells rested with interleukin (IL)7 for 48 h after 1) initial thawing,2) expansion,and 3) secondary cryopreservation/thawing of expanded cells. To generate competent antigen presenting cells from PBMCs,we promoted differentiation of PBMCs into dendritic cells with granulocyte macrophage colony stimulating factor and IL-4. RESULTS We observed robust dendritic cell differentiation from human PBMCs treated with 50 ng/mL GM-CSF and 20 ng/mL IL-4 in as little as 3 days. Dendritic cell purity was substantially increased by magnetically enriching for CD14+ monocytes prior to differentiation. We also measured antigen-dependent T cell activation in DC-T cell cocultures. However,polyclonal expansion of T cells with anti-CD3/antiCD28 abolished antigen-dependent upregulation of CD69 in our assay despite minimal transcriptional differences between rested CD8+ T cells before and after expansion. Furthermore,resting these expanded T cells in IL-2,IL-7 or IL-15 did not restore the antigen dependent responses. In contrast,T cells that were initially expanded with IL-2 + IL-7 rather than plate bound anti-CD3 + anti-CD28 retained responsiveness to antigen stimulation and these responses strongly correlated with responses measured at initial thawing. SIGNIFICANCE While screening techniques for potential pathological autoantibodies have come a long way,comparable full-length protein target assays for screening patient T cells at medium throughput are noticeably lacking due to technical hurdles. Here we advance techniques that should have broad applicability to translational studies investigating cell mediated immunity in infectious or autoimmune diseases. Future studies are aimed at investigating possible CD8+ T cell autoantigens in MS and other CNS autoimmune diseases. View Publication

Previous studies demonstrated that CD4+ T cells can uptake tumor antigen-pulsed dendritic cell-derived exosomes (DEXO),which harbor tumor antigen peptide/pMHC I complex and costimulatory molecules and show potent effects on inducing antitumor immunity. However,in preliminary study,CD4+ T cells targeted by leukemia cell-derived exosomes (LEXs) did not show the expected effects in inducing effective anti-leukemia immunity,indicating that LEX is poorly immunogenetic largely due to an inadequate costimulatory capacity. Therefore,LEX-based anti-leukemia vaccines need to be optimized. In this study,we constructed a novel LEX-based vaccine by combining CD4+ T cells with costimulatory molecules gene-modified LEXs,which harbor upregulated CD80 and CD86,and the anti-leukemia immunity of CD80 and CD86 gene-modified LEX-targeted CD4+ T cells was investigated. We used lentiviral vectors encoding CD80 and CD86 to successfully transduced the L1210 leukemia cells,and the expression of CD80 and CD86 was remarkably upregulated in leukemia cells. The LEXs highly expressing CD80 and CD86 were obtained from the supernatants of gene-transduced leukemia cells. Our data have shown that LEX-CD8086 could promote CD4+ T cell proliferation and Th1 cytokine secretion more efficiently than control LEXs. Moreover,CD4+ TLEX-CD8086 expressed the acquired exosomal costimulatory molecules. With acquired costimulatory molecules,CD4+ TLEX-CD8086 can act as APCs and are capable of directly stimulating the leukemia cell antigen-specific CD8+ CTL response. This response was higher in potency compared to that noted by the other formulations. Furthermore,the animal study revealed that the CD4+ TLEX-CD8086 significantly inhibited tumor growth and prolonged survival of tumor-bearing mice than other formulations did in both protective and therapeutic models. In conclusion,this study revealed that CD4+ TLEX-CD8086 could effectively induce more potential anti-leukemia immunity than LEX-CD8086 alone,suggesting that the utilization of a costimulatory molecule gene-modified leukemia cell-derived exosome-targeted CD4+ T cell vaccine may have promising potential for leukemia immunotherapy. View Publication

The integrated stress response (ISR) facilitates cellular adaptation to unfavorable conditions by reprogramming the cellular response. ISR activation was reported in neurological disorders and solid tumors; however,the function of ISR and its role as a possible therapeutic target in hematological malignancies still remain largely unexplored. Previously,we showed that the ISR is activated in chronic myeloid leukemia (CML) cells and correlates with blastic transformation and tyrosine kinase inhibitor (TKI) resistance. Moreover,the ISR was additionally activated in response to imatinib as a type of protective internal signaling. Here,we show that ISR inhibition combined with imatinib treatment sensitized and more effectively eradicated leukemic cells both in vitro and in vivo compared to treatment with single agents. The combined treatment specifically inhibited the STAT5 and RAS/RAF/MEK/ERK pathways,which are recognized as drivers of resistance. Mechanistically,this drug combination attenuated both interacting signaling networks,leading to BCR-ABL1- and ISR-dependent STAT5 activation. Consequently,leukemia engraftment in patient-derived xenograft mice bearing CD34+ TKI-resistant CML blasts carrying PTPN11 mutation responsible for hyperactivation of the RAS/RAF/MAPK and JAK/STAT5 pathways was decreased upon double treatment. This correlated with the downregulation of genes related to the RAS/RAF/MAPK,JAK/STAT5 and stress response pathways and was associated with lower expression of STAT5-target genes regulating proliferation,viability and the stress response. Collectively,these findings highlight the effect of imatinib plus ISRIB in the eradication of leukemic cells resistant to TKIs and suggest potential clinical benefits for leukemia patients with TKI resistance related to RAS/RAF/MAPK or STAT5 signaling. We propose that personalized treatment based on the genetic selection of patients carrying mutations that cause overactivation of the targeted pathways and therefore make their sensitivity to such treatment probable should be considered as a possible future direction in leukemia treatment. View Publication

Rationale: IgA can induce activation of neutrophils which are the most abundant cell type in blood,but the development of IgA as therapeutic has been confounded by its short half-life and a weak ability to recruit NK cells as effector cells. Therefore,we generated an X-shaped antibody (X-body) based on the principle of molecular self-assembly that combines the activities of both IgG and IgA,which can effectively recruit and activate NK cells,macrophages,and neutrophils to kill tumor cells. Methods: X-body was generated by using a self-assembly strategy. The affinity of the X-body with the antigen and Fc receptors was tested by surface plasmon resonance. The shape of X-body was examined using negative staining transmission electron microscopy. The tumor cell killing activity of X-body was assessed in vitro and in multiple syngeneic mouse models. To explore the mechanism of X-body,tumor-infiltrating immune cells were analyzed by single-cell RNA-seq and flow cytometry. The dependence of neutrophil,macrophage,and NK cells for the X-body efficacy was confirmed by in vivo depletion of immune cell subsets. Results: The X-body versions of rituximab and trastuzumab combined the full spectrum activity of IgG and IgA and recruited NK cells,macrophages,and neutrophils as effector cells for eradication of tumor cells. Treatment with anti-hCD20 and anti-hHER2 X-bodies leads to a greater reduction in tumor burden in tumor-bearing mice compared with the IgA or IgG counterpart,and no obvious adverse effect is observed upon X-body treatment. Moreover,the X-body has a serum half-life and drug stability comparable to IgG. Conclusions: The X-body,as a myeloid-cell-centered therapeutic strategy,holds promise for the development of more effective cancer-targeting therapies than the current state of the art. View Publication

G-protein coupled receptor kinases (GRKs) participate in the regulation of chemokine receptors by mediating receptor desensitization. They can be recruited to agonist-activated G-protein coupled receptors (GPCRs) and phosphorylate their intracellular parts,which eventually blocks signal propagation and often induces receptor internalization. However,there is growing evidence that GRKs can also control cellular functions beyond GPCR regulation. Immune cells commonly express two to four members of the GRK family (GRK2,GRK3,GRK5,GRK6) simultaneously,but we have very limited knowledge about their interplay in primary immune cells. In particular,we are missing comprehensive studies comparing the role of this GRK interplay for (a) multiple GPCRs within one leukocyte type,and (b) one specific GPCR between several immune cell subsets. To address this issue,we generated mouse models of single,combinatorial and complete GRK knockouts in four primary immune cell types (neutrophils,T cells,B cells and dendritic cells) and systematically addressed the functional consequences on GPCR-controlled cell migration and tissue localization. Our study shows that combinatorial depletions of GRKs have pleiotropic and cell-type specific effects in leukocytes,many of which could not be predicted. Neutrophils lacking all four GRK family members show increased chemotactic migration responses to a wide range of GPCR ligands,whereas combinatorial GRK depletions in other immune cell types lead to pro- and anti-migratory responses. Combined depletion of GRK2 and GRK6 in T cells and B cells shows distinct functional outcomes for (a) one GPCR type in different cell types,and (b) different GPCRs in one cell type. These GPCR-type and cell-type specific effects reflect in altered lymphocyte chemotaxis in vitro and localization in vivo. Lastly,we provide evidence that complete GRK deficiency impairs dendritic cell homeostasis,which unexpectedly results from defective dendritic cell differentiation and maturation in vitro and in vivo. Together,our findings demonstrate the complexity of GRK functions in immune cells,which go beyond GPCR desensitization in specific leukocyte types. Furthermore,they highlight the need for studying GRK functions in primary immune cells to address their specific roles in each leukocyte subset. View Publication

Normal density granulocytes (NDGs) can suppress T-cell responses in a similar way as myeloid-derived suppressor cells (MDSCs). In this study,we tested the hypothesis that NDGs from healthy donors preferentially inhibit T helper 1 (Th1) cells and investigated the myeloid-derived suppressive effect in different T-cell populations. We found that NDG-induced suppression of T-cell proliferation was contact dependent,mediated by integrin CD11b,and dependent on NDG-production of reactive oxygen species (ROS). The suppression was rapid and occurred within the first few hours of coculture. The suppression did not influence the CD8+/CD4+ ratio indicating an equal sensitivity in these populations. We further analyzed the CD4+ T helper subsets and found that NDGs induced a loss of Th1 surface marker,CD183,that was unrelated to ligand-binding to CD183. In addition,we analyzed the Th1,Th2,and Th17 cytokine production and found that all cytokine groups were suppressed when T-cells were incubated with NDGs. We therefore concluded that NDGs do not preferentially suppress Th1-cells. Instead,NDGs generally suppress Th cells and cytotoxic T-cells but specifically downregulate the Th1 marker CD183. View Publication

Facile and sensitive detection and isolation of circulating tumor cells (CTCs) was achieved using the aptamer-targeted magnetic nanoparticles (Apt-MNPs) in conjugation with a microfluidic device. Apt-MNPs were developed by the covalent attachment of anti-MUC1 aptamer to the silica-coated magnetic nanoparticles via the glutaraldehyde linkers. Apt-MNPs displayed high stability and functionality after 6 months of storage at 4 °C. The specific microfluidic device consisting of mixing,sorting and separation modules was fabricated through conventional photo- and soft-lithography by using polydimethylsiloxane. The capture efficiency of Apt-MNPs was first studied in vitro on MCF-7 and MDA-MB-231 cancer cell lines in the bulk and microfluidic platforms. The cell capture yields of more than 91% were obtained at the optimum condition after 60 minutes of exposure to 50 $\mu$g mL-1 Apt-MNPs with 10 to 106 cancer cells in different media. CTCs were also isolated efficiently from the blood samples of breast cancer patients and successfully propagated in vitro. The isolated CTCs were further characterized using immunofluorescence staining. The overall results indicated the high potential of the present method for the detection and capture of CTCs. View Publication

A breakdown in cellular homeostasis is thought to drive na{\{i}}ve T cell aging however the link between na{\"{i}}ve T cell homeostasis and aging in humans is poorly understood. To better address this we developed a lymphoid organoid system that maintains resting na{\"{i}}ve T cells for more than 2 weeks in conjunction with high CD45RA expression. Deep phenotypic characterization of na{\"{i}}ve T cells across age identified reduced CD45RA density as a hallmark of aging. A conversion from CD45RAhigh naive cells to a CD45RAlow phenotype was reproduced within our organoid system by structural breakdown but not by stromal cell aging or reduced lymphocyte density and mediated by alternative CD45 splicing. Together these data suggest that external influences within the lymph node microenvironment may cause phenotypic conversion of na{\"{i}}ve T cells in older adults." View Publication

BACKGROUND CD8+ T cells are important for protective immunity against intracellular pathogens. Excessive amounts of antigen and/or inflammatory signals often lead to the gradual deterioration of CD8+ T cell function,a state called exhaustion". However the association between CD8+ T cell exhaustion and acute respiratory distress syndrome (ARDS) has not been studied. This study was conducted to elucidate how CD8+ T cells and inhibitory receptors were related to the clinical prognosis of ARDS. METHODS A prospective observational study in an emergency department enrolled patients who were diagnosed with sepsis-associated ARDS according to the sepsis-3 criteria and Berlin definition. Peripheral blood samples were collected within 24??h post recruitment. CD8+ T cell count proliferation ratio cytokine secretion and the expression of coinhibitory receptors were assayed. RESULTS Sixty-two patients with ARDS met the inclusion criteria. CD8+ T cell counts and proliferation rates were dramatically decreased in non-surviving ARDS patients. Increasing programmed cell death 1 (PD-1) expression on the CD8+ T cell surface was seen in patients with worse organ function while an increasing level of T cell immunoglobulin mucin-3 (Tim-3) was associated with a longer duration of the shock. Kaplan-Meier analysis showed that low CD8+ T cell percentages and increased inhibitory molecule expression were significantly associated with a worse survival rate. CONCLUSIONS CD8+ T cells and coinhibitory receptors are promising independent prognostic markers of sepsis-induced ARDS and increased CD8+ T cell exhaustion is significantly correlated with poor prognosis." View Publication

Same day processing of biospecimens such as blood is not always feasible,which presents a challenge for research programs seeking to study a broad population or to characterize patients with rare diseases. Recruiting sites may not be equipped to process blood samples and variability in timing and technique employed to isolate peripheral blood mononuclear cells (PBMCs) at local sites may compromise reproducibility across patients. One solution is to send whole blood collected by routine phlebotomy via overnight courier to the testing site under ambient conditions. Determining the impact of shipping on subsequent leukocyte responses is a necessary prerequisite to any experimental analysis derived from transported samples. To this end,whole blood was collected from healthy control subjects and processed fresh or at 6,24 and 48 h after collection and handling under modeled shipping conditions. At endpoint,whole blood was assessed via a complete blood count with differential and immunophenotyped using a standardized panel of antibodies [HLADR,CD66b,CD3,CD14,CD16]. PBMCs and neutrophils were isolated from whole blood and subjected to ex vivo stimulation with lipopolysaccharide and heat-killed Staphylococcus aureus. Stimulated release of cytokines and chemokines was assessed by cytometric bead array. RNA was also isolated from PBMCs to analyze transcriptional changes induced by shipping. The complete blood count with differential revealed that most parameters were maintained in shipped blood held for 24 h at ambient temperature. Immunophenotyping indicated preservation of cellular profiles at 24 h,although with broadening of some populations and a decrease in CD16 intensity on classical monocytes. At the transcriptional level,RNAseq analysis identified upregulation of a transcription factor module associated with inflammation in unstimulated PBMCs derived from whole blood shipped overnight. However,these changes were limited in both scale and number of impacted genes. Ex vivo stimulation of PBMCs further revealed preservation of functional responses in cells isolated from shipped blood held for 24 h at ambient temperature. However,neutrophil responses were largely abrogated by this time. By 48 h neither cell population responded within normal parameters. These findings indicate that robust immunophenotyping and PBMC stimulated response profiles are maintained in whole blood shipped overnight and processed within 24 h of collection,yielding results that are representative of those obtained from the sample immediately following venipuncture. This methodology is feasible for many patient recruitment sites to implement and allows for sophisticated immunological analysis of patient populations derived from large geographic areas. With regard to rare disease research,this meets a universal need to enroll patients in sufficient numbers for immunoprofiling and discovery of underlying pathogenic mechanisms. View Publication

BACKGROUND There is an unmet need for developing faithful animal models for preclinical evaluation of immunotherapy. The current approach to generate preclinical models for immunotherapy evaluation has been to transplant CD34+ cells from umbilical cord blood into immune-deficient mice followed by implantation of patient derived tumor cells. However,current models are associated with high tumor rejection rate secondary to the allograft vs. tumor response from human leukocyte antigen (HLA) mismatches. We herein report the first development of a novel,humanized patient-derived xenograft (PDX) model using autologous CD34+ cells from bone marrow aspirate obtained from a patient with metastatic clear cell renal cell carcinoma (mRCC) from whom a PDX had been developed. CASE DESCRIPTION This is a 68-year-old Caucasian man diagnosed with mRCC with metastasis to the liver in 2014. He was treated with sunitinib +/- AGS-003 and underwent a cytoreductive right nephrectomy,left adrenalectomy and partial liver resection. PDX was generated using resected nephrectomy specimen. After surgery,patient received multiple lines of standard of care therapy including sunitinib,axitinib,bevacizumab,everolimus and cabozantinib. While progressing on cabozantinib,he was treated with nivolumab. Seven years after initiation of nivolumab,and 4 years after stopping systemic therapy,he remains in complete remission. To generate autologous PDX model,bone marrow aspirate was performed and CD34+ hematopoietic stem/progenitor cells (HSPCs) were isolated and injected into 150 rad irradiated non-obese diabetic scid gamma null (NSG) mice. At 11 weeks post-transplant,the matched patient PDX was injected subcutaneously into the humanized mice and the mice were treated with nivolumab. CONCLUSIONS Our case represents successful therapy of nivolumab in mRCC. Furthermore,HPSCs obtained from a single bone marrow aspirate were able to reconstitute an immune system in the mice that allowed nivolumab to inhibit the tumor growth of PDX and recapitulated the durable remission observed in the patient with nivolumab. We observed the reconstitution of human T cells,B cells and natural killer (NK) cells and unlike the humanized mouse model using cord blood,our model system eliminates the tumor rejection from mis-matched HLA. Our autologous humanized renal cell carcinoma (RCC) PDX model provides an effective tool to study immunotherapy in a preclinical setting. View Publication

Juvenile dermatomyositis (JDM) is a pediatric autoimmune disease associated with characteristic rash and proximal muscle weakness. To gain insight into differential lymphocyte gene expression in JDM,peripheral blood mononuclear cells from 4 new-onset JDM patients and 4 healthy controls were sorted into highly enriched lymphocyte populations for RNAseq analysis. NK cells from JDM patients had substantially greater differentially expressed genes (273) than T (57) and B (33) cells. Upregulated genes were associated with the innate immune response and cell cycle,while downregulated genes were associated with decreased ribosomal RNA. Suppressed ribosomal RNA in JDM NK cells was validated by measuring transcription and phosphorylation levels. We confirmed a population of low ribosome expressing NK cells in healthy adults and children. This population of low ribosome NK cells was substantially expanded in 6 treatment-na{\{i}}ve JDM patients and was associated with decreased NK cell degranulation. The enrichment of this NK low ribosome population was completely abrogated in JDM patients with quiescent disease. Together these data suggest NK cells are highly activated in new-onset JDM patients with an increased population of low ribosome expressing NK cells which correlates with decreased NK cell function and resolved with control of active disease." View Publication