Allison F. O'Neill

The role of extracellular spacer regions in the optimal design of chimeric immune receptors: evaluation of four different scFvs and antigens.

Human peripheral blood lymphocytes can be transduced to express antigen-dependent CD3ζ chimeric immune receptors (CIRs), which function independently of the T-cell receptor (TCR). Although the exact function of these domains is unclear, previous studies imply that an extracellular spacer region is required for optimal CIR activity. In this study, four scFvs (in the context of CIRs with or without extracellular spacer regions) were used to target the human tumor-associated antigens carcinoembryonic antigen (CEA), neural cell adhesion molecule (NCAM), the oncofetal antigen 5T4, and the B-cell antigen CD19. In all cases human T-cell populations expressing the CIRs were functionally active against their respective targets, but the anti-5T4 and anti-NCAM CIRs showed enhanced specific cytokine release and cytotoxicity only when possessing an extracellular spacer region. In contrast, the anti-CEA and anti-CD19 CIRs displayed optimal cytokine release activity only in the absence of an extracellular spacer. Interestingly, mapping of the scFv epitopes has revealed that the anti-CEA scFv binds close to the amino-terminal of CEA, which is easily accessible to the CIR. In contrast, CIRs enhanced by a spacer domain appear to bind to epitopes residing closer to the cell membrane, suggesting that a more flexible extracellular domain may be required to permit the efficient binding of such epitopes. These results show that a spacer is not necessary for optimal activity of CIRs but that the optimal design varies.

A Primitive ATP Receptor from the Little Skate Raja erinacea

P2Y ATP receptors are widely expressed in mammalian tissues and regulate a broad range of activities. Multiple subtypes of P2Y receptors have been identified and are distinguished both on a molecular basis and by pharmacologic substrate preference. Functional evidence suggests that hepatocytes from the little skateRaja erinacea express a primitive P2Y ATP receptor lacking pharmacologic selectivity, so we cloned and characterized this receptor. Skate hepatocyte cDNA was amplified with degenerate oligonucleotide probes designed to identify known P2Y subtypes. A single polymerase chain reaction product was found and used to screen a skate liver cDNA library. A 2314-base pair cDNA clone was generated that contained a 1074-base pair open reading frame encoding a 357-amino acid gene product with 61–64% similarity to P2Y1 receptors and 21–37% similarity to other P2Y receptor subtypes. Pharmacology of the putative P2Y receptor was examined using the Xenopus oocyte expression system and revealed activation by a range of nucleotides. The receptor was expressed widely in skate tissue and was expressed to a similar extent in other primitive organisms. Phylogenetic analysis suggested that this receptor is closely related to a common ancestor of the P2Y subtypes found in mammals, avians, and amphibians. Thus, the skate liver P2Y receptor functions as a primitive P2Y ATP receptor with broad pharmacologic selectivity and is related to the evolutionary forerunner of P2Y1 receptors of higher organisms. This novel receptor should provide an effective comparative model for P2Y receptor pharmacology and may improve our understanding of nucleotide specificity among the family of P2Y ATP receptors.

Loss-of-function and gain-of-function phenotypes of stomatocytosis mutant RhAG F65S

Four patients with overhydrated cation leak stomatocytosis (OHSt) exhibited the heterozygous RhAG missense mutation F65S. OHSt erythrocytes were osmotically fragile, with elevated Na and decreased K contents and increased cation channel-like activity. Xenopus oocytes expressing wild-type RhAG and RhAG F65S exhibited increased ouabain and bumetanide-resistant uptake of Li(+) and (86)Rb(+), with secondarily increased (86)Rb(+) influx sensitive to ouabain and to bumetanide. Increased RhAG-associated (14)C-methylammonium (MA) influx was severely reduced in RhAG F65S-expressing oocytes. RhAG-associated influxes of Li(+), (86)Rb(+), and (14)C-MA were pharmacologically distinct, and Li(+) uptakes associated with RhAG and RhAG F65S were differentially inhibited by NH(4)(+) and Gd(3+). RhAG-expressing oocytes were acidified and depolarized by 5 mM bath NH(3)/NH(4)(+), but alkalinized and depolarized by subsequent bath exposure to 5 mM methylammonium chloride (MA/MA(+)). RhAG F65S-expressing oocytes exhibited near-wild-type responses to NH(4)Cl, but MA/MA(+) elicited attenuated alkalinization and strong hyperpolarization. Expression of RhAG or RhAG F65S increased steady-state cation currents unaltered by bath Li(+) substitution or bath addition of 5 mM NH(4)Cl or MA/MA(+). These oocyte studies suggest that 1) RhAG expression increases oocyte transport of NH(3)/NH(4)(+) and MA/MA(+); 2) RhAG F65S exhibits gain-of-function phenotypes of increased cation conductance/permeability, and loss-of-function phenotypes of decreased and modified MA/MA(+) transport, and decreased NH(3)/NH(4)(+)-associated depolarization; and 3) RhAG transports NH(3)/NH(4)(+) and MA/MA(+) by distinct mechanisms, and/or the substrates elicit distinct cellular responses. Thus, RhAG F65S is a loss-of-function mutation for amine transport. The altered oocyte intracellular pH, membrane potential, and currents associated with RhAG or RhAG F65S expression may reflect distinct transport mechanisms.

Immaturity of IL-18 gene expression and protein production in cord blood (CB) versus peripheral blood (PB) mononuclear cells and differential effects in natural killer (NK) cell development and function.

We have previously demonstrated dysregulation of IL‐12 and IL‐15 gene and protein expression between activated cord blood (CB) versus peripheral blood (PB) mononuclear cells (MNCs). In the present study, we compared IL‐18 gene expression and protein production and IL‐18 mRNA half‐life in basal versus activated CB versus PB MNCs, the effects of IL‐18 ± IL‐12 on MNCs IFN‐γ protein production and ex vivo expansion and activation of CB with IL‐12 + IL‐2 + anti‐CD3 ± IL‐18. Basal and activated levels of IL‐18 were significantly higher in PB versus CB MNCs (P < 0·05). IL‐18 mRNA was coincidental with protein levels and significantly lower in CB (P < 0·05) and its half‐life significantly shorter in CB versus PB MNCs (P < 0·05). IL‐18 synergistically with IL‐12 induced IFN‐γ production from PB greater than CB MNCs (P < 0·05). NK cells expansion (P < 0·001) and cytotoxicity (P < 0·01) was significantly increased with IL‐12 + IL‐2 + anti‐CD3 and IL‐18. In summary IL‐18 gene expression and protein production are significantly decreased in activated CB versus PB MNCs, in part secondary to increased degradation of CB IL‐18 mRNA. These results may have implications for the mechanism(s) in part responsible for the immaturity of CB T‐cell immunity.

Ludwig's Angina in the Pediatric Population

As many as 1 in 3 of cases of Ludwigs angina occur in children and adolescents, and pediatricians are therefore ideally situated to detect these individuals at an early stage of their potentially life-threatening disease. The early identification and referral of children afflicted with Ludwigs angina to tertiary care centers allows for the rapid initiation of medical therapy and the consultation of those emergency services critical to providing such patients with optimal diagnostic and therapeutic interventions. This review provides an overview of the anatomical and pathophysiological considerations in Ludwigs angina and describes practical management principles to assist pediatricians in the diagnosis and treatment of this disease. Included in this review is an evidence-based algorithm for airway management.

Regulation of the type III InsP3 receptor by InsP3 and calcium

It has been proposed that the inositol 1,4,5-trisphosphate receptor (InsP(3)R) type III acts as a trigger for InsP(3)-mediated calcium (Ca(2+)) signaling, because this InsP(3) isoform lacks feedback inhibition by cytosolic Ca(2+). We tested this hypothesis in RIN-m5F cells, which express predominantly the type III receptor. Extracellular ATP increases Ca(2+) in these cells, and we found that this effect is independent of extracellular Ca(2+) but is blocked by the InsP(3)R antagonist heparin. There was a dose-dependent increase in the number of cells responding to ATP and two-photon flash photolysis of caged-Ca(2+) heightened the sensitivity of RIN-m5F cells to this increase. These findings provide evidence that Ca(2+) increases the sensitivity of the InsP(3)R type III in intact cells and supports the idea that this isoform can act as a trigger for hormone-induced Ca(2+) signaling.

Targeted Imaging of Ewing Sarcoma in Preclinical Models Using a 64Cu-Labeled Anti-CD99 Antibody

Purpose: Ewing sarcoma is a tumor of the bone and soft tissue characterized by diffuse cell membrane expression of CD99 (MIC2). Single-site, surgically resectable disease is associated with an excellent 5-year event-free survival; conversely, patients with distant metastases have a poor prognosis. Noninvasive imaging is the standard approach to identifying sites of metastatic disease. We sought to develop a CD99-targeted imaging agent for staging Ewing sarcoma and other CD99-expressing tumors. Experimental Design: We identified a CD99 antibody with highly specific binding in vitro and labeled this antibody with 64Cu. Mice with either subcutaneous Ewing sarcoma xenograft tumors or micrometastases were imaged with the 64Cu-labeled anti-CD99 antibody and these results were compared with conventional MRI and 2[18F]fluoro-2-deoxy-d-glucose–positron emission tomography (FDG–PET) imaging. Results: 64Cu-labeled anti-CD99 antibody demonstrated high avidity for the CD99-positive subcutaneous tumors, with a high tumor-to-background ratio, greater than that demonstrated with FDG–PET. Micrometastases, measuring 1 to 2 mm on MRI, were not detected with FDG–PET but were readily visualized with the 64Cu-labeled anti-CD99 antibody. Probe biodistribution studies demonstrated high specificity of the probe for CD99-positive tumors. Conclusions: 64Cu-labeled anti-CD99 antibody can detect subcutaneous Ewing sarcoma tumors and metastatic sites with high sensitivity, outperforming FDG–PET in preclinical studies. This targeted radiotracer may have important implications for the diagnosis, surveillance, and treatment of Ewing sarcoma. Similarly, it may impact the management of other CD99 positive tumors. Clin Cancer Res; 20(3); 678–87. ©2013 AACR.

Unresectable hepatoblastoma: current perspectives

Although rare, hepatoblastoma is the most common pediatric liver tumor. Complete resection is a critical component for cure; however, most patients will have tumors that are not resected at diagnosis. For these patients, administration of neoadjuvant chemotherapy renders tumors resectable in most patients. For patients whose tumors remain unresectable after chemotherapy, liver transplantation is indicated (in the absence of active unresectable metastatic disease). In patients whose tumors remain unresectable after conventional chemotherapy, interventional techniques may serve as a promising option to reduce tumor size, decrease systemic toxicity, decrease need for liver transplantation, and increase feasibility of tumor resection.

Post-transplant lymphoproliferative disorder of the pediatric airway: Presentation and management.

OBJECTIVE Post-transplant lymphoproliferative disorder (PTLD) is a rare complication of immunosuppression with little consensus on its evaluation and management. The purpose of this contemporary review is to describe a pediatric patient with PTLD of the airway and review the literature to provide multidisciplinary recommendations regarding management. DATA SOURCES Retrospective chart and literature review. REVIEW METHODS A pediatric patient with PTLD of the airway is described. An extensive literature search to review the existing data on pediatric PTLD of the upper airway was also performed. RESULTS A pediatric patient with mixed fetal/embryonal hepatoblastoma developed laryngo-tracheal PTLD following liver transplantation. Diagnostic positron emission tomography (PET) scan demonstrated multiple sites of abnormal fluorodeoxyglucose (FDG) uptake within the larynx, distal esophagus, cervical lymph nodes, and abdomen concerning for PTLD. Laryngeal biopsy demonstrated Epstein-Barr virus (EBV) positive cells confirming the diagnosis. Rituximab therapy and reduction of immunosuppression resulted in resolution of his laryngeal disease in 3 months. An extensive literature search to review the existing data on pediatric PTLD of the larynx and trachea revealed 14 reported cases. CONCLUSIONS PTLD of the pediatric airway is an EBV-associated disease that requires a high index of suspicion as patients can often present with non-specific signs and symptoms but progress to have significant airway compromise. Evaluation consists of peripheral blood polymerase chain reaction (PCR) assays, biopsy, and PET/CT imaging. Management options include reduction of immunosuppression and/or systemic therapies.

Long-term outcomes of liver transplantation for hepatoblastoma: A single-center 14-year experience

HB is the most common primary liver tumor in children. Complete tumor excision, either by partial resection or by total hepatectomy and liver transplantation, in combination with chemotherapy provides the best chance for cure. We performed a retrospective analysis of patients who underwent liver transplantation for HB and herein present our 14‐year single‐institution experience. Twenty‐five patients underwent liver transplantation for HB at a median age of 26 months (IQR: 15‐44). Graft survival was 96%, 87%, and 80% at 1, 3, and 5 years, respectively. There were four patient deaths, three of them due to disease recurrence within the first year post‐transplant. Ten‐year overall survival was 84%. Three recipients initially presented with pulmonary metastases and underwent resection of metastatic disease, of which two are alive at 3.9 years. Of three patients who underwent salvage transplants, two are alive at 1.5 years after transplant. Non‐survivors were associated with lower median alpha fetoprotein value at presentation compared to survivors (21 707 vs 343 214; P = .04). In conclusion, the overall long‐term outcome of primary liver transplantation for HB is excellent. Tumor recurrence was the highest contributor to mortality. Even patients with completely treated pulmonary metastases prior to transplant demonstrated a favorable survival.