Angiogenesis in platelet endothelial cell adhesion molecule-1-null mice.

Platelet endothelial cell adhesion molecule (PECAM)-1 has been previously implicated in endothelial cell migration; additionally, anti-PECAM-1 antibodies have been shown to inhibit in vivo angiogenesis. Studies were therefore performed with PECAM-1-null mice to further define the involvement of PECAM-1 in blood vessel formation. Vascularization of subcutaneous Matrigel implants as well as tumor angiogenesis were both inhibited in PECAM-1-null mice. Reciprocal bone marrow transplants that involved both wild-type and PECAM-1-deficient mice revealed that the impaired angiogenic response resulted from a loss of endothelial, but not leukocyte, PECAM-1. In vitro wound migration and single-cell motility by PECAM-1-null endothelial cells were also compromised. In addition, filopodia formation, a feature of motile cells, was inhibited in PECAM-1-null endothelial cells as well as in human endothelial cells treated with either anti-PECAM-1 antibody or PECAM-1 siRNA. Furthermore, the expression of PECAM-1 promoted filopodia formation and increased the protein expression levels of Cdc42, a Rho GTPase that is known to promote the formation of filopodia. In the developing retinal vasculature, numerous, long filamentous filopodia, emanating from endothelial cells at the tips of angiogenic sprouts, were observed in wild-type animals, but to a lesser extent in the PECAM-1-null mice. Together, these data further establish the involvement of endothelial PECAM-1 in angiogenesis and suggest that, in vivo, PECAM-1 may stimulate endothelial cell motility by promoting the formation of filopodia.

Identification of Predictive Biomarkers for Cytokine Release Syndrome after Chimeric Antigen Receptor T-cell Therapy for Acute Lymphoblastic Leukemia.

UNLABELLED: Chimeric antigen receptor (CAR)-modified T cells with anti-CD19 specificity are a highly effective novel immune therapy for relapsed/refractory acute lymphoblastic leukemia. Cytokine release syndrome (CRS) is the most significant and life-threatening toxicity. To improve understanding of CRS, we measured cytokines and clinical biomarkers in 51 CTL019-treated patients. Peak levels of 24 cytokines, including IFNγ, IL6, sgp130, and sIL6R, in the first month after infusion were highly associated with severe CRS. Using regression modeling, we could accurately predict which patients would develop severe CRS with a signature composed of three cytokines. Results were validated in an independent cohort. Changes in serum biochemical markers, including C-reactive protein and ferritin, were associated with CRS but failed to predict development of severe CRS. These comprehensive profiling data provide novel insights into CRS biology and, importantly, represent the first data that can accurately predict which patients have a high probability of becoming critically ill. SIGNIFICANCE: CRS is the most common severe toxicity seen after CAR T-cell treatment. We developed models that can accurately predict which patients are likely to develop severe CRS before they become critically ill, which improves understanding of CRS biology and may guide future cytokine-directed therapy. Cancer Discov; 6(6); 664-79. ©2016 AACR.See related commentary by Rouce and Heslop, p. 579This article is highlighted in the In This Issue feature, p. 561.

NY-ESO-1-specific TCR-engineered T cells mediate sustained antigen-specific antitumor effects in myeloma.

Despite recent therapeutic advances, multiple myeloma (MM) remains largely incurable. Here we report results of a phase I/II trial to evaluate the safety and activity of autologous T cells engineered to express an affinity-enhanced T cell receptor (TCR) recognizing a naturally processed peptide shared by the cancer-testis antigens NY-ESO-1 and LAGE-1. Twenty patients with antigen-positive MM received an average 2.4 × 10(9) engineered T cells 2 d after autologous stem cell transplant. Infusions were well tolerated without clinically apparent cytokine-release syndrome, despite high IL-6 levels. Engineered T cells expanded, persisted, trafficked to marrow and exhibited a cytotoxic phenotype. Persistence of engineered T cells in blood was inversely associated with NY-ESO-1 levels in the marrow. Disease progression was associated with loss of T cell persistence or antigen escape, in accordance with the expected mechanism of action of the transferred T cells. Encouraging clinical responses were observed in 16 of 20 patients (80%) with advanced disease, with a median progression-free survival of 19.1 months. NY-ESO-1-LAGE-1 TCR-engineered T cells were safe, trafficked to marrow and showed extended persistence that correlated with clinical activity against antigen-positive myeloma.

Isolation of murine lung endothelial cells.

Several protocols for the isolation of endothelial cells (ECs) from murine lung have been described in the literature. We, however, encountered a number of problems while using these procedures that prevented us from consistently or reliably obtaining pure populations of ECs from the lungs of mice. By incorporating specific elements from previously published protocols, as well as adding some novel features, we developed a new strategy for isolating ECs from murine lung. In this approach, a suspension of lung cells is initially prepared from the lungs of 7- to 14-day-old mouse pups using procedures that prevent intravascular clotting and leukocyte activation, minimize mechanical trauma to the lung tissue, and limit exposure to the digesting enzymes. The resulting cell suspension is cultured for 2-3 days, trypsinized to produce a suspension of single cells, and then subjected to fluorescence-activated cell sorting using an anti-ICAM-2 antibody. The sorted cells are then plated and split 1:2 at each passage to maintain a high density of the cells. Using this approach, we have been able to isolate pure populations of ECs that were sustainable for extended periods in culture without the emergence of fibroblast overgrowth or the development of senescence. We believe the success of this approach will provide opportunities to take advantage of the large and growing number of knockout and transgenic mouse lines to investigate the endothelial-specific roles of targeted molecules in the pulmonary vasculature.

A direct interaction between cytoplasmic dynein and kinesin I may coordinate motor activity.

Cytoplasmic dynein and kinesin I are both unidirectional intracellular motors. Dynein moves cargo toward the cell center, and kinesin moves cargo toward the cell periphery. There is growing evidence that bi-directional motility is regulated in the cell, potentially through direct interactions between oppositely oriented motors. We have identified a direct interaction between cytoplasmic dynein and kinesin I. Using the yeast two-hybrid assay and affinity chromatography, we demonstrate that the intermediate chain of dynein binds to kinesin light chains 1 and 2. The interaction is both direct and specific. Co-immunoprecipitation experiments demonstrate an interaction between endogenous proteins in rat brain cytosol. Double-label immunocytochemistry reveals a partial co-localization of vesicle-associated motor proteins. Together these observations suggest that soluble motors can interact, potentially allowing kinesin I to actively localize dynein to cellular sites of function. There is also a vesicle population with both dynein and kinesin I bound that may be capable of bi-directional motility along cellular microtubules.

Mapping and initial analysis of human subtelomeric sequence assemblies.

Physical mapping data were combined with public draft and finished sequences to derive subtelomeric sequence assemblies for each of the 41 genetically distinct human telomere regions. Sequence gaps that remain on the reference telomeres are generally small,well-defined,and for the most part,restricted to regions directly adjacent to the terminal (TTAGGG)n tract. Of the 20.66 Mb of subtelomeric DNA analyzed, 3.01 Mb are subtelomeric repeat sequences (Srpt),and an additional 2.11 Mb are segmental duplications. The subtelomeric sequence assemblies are enriched >25-fold in short,internal (TTAGGG)n-like sequences relative to the rest of the genome; a total of 114 (TTAGGG)n-like islands were found,55 within Srpt regions,35 within one-copy regions,11 at one-copy/Srpt or Srpt/segmental duplication boundaries,and 13 at the telomeric ends of assemblies. Transcripts were annotated in each assembly,noting their mapping coordinates relative to their respective telomere and whether they originate in duplicated DNA or single-copy DNA. A total of 697 transcripts were found in 15.53 Mb of one-copy DNA,76 transcripts in 2.11 Mb of segmentally duplicated DNA,and 168 transcripts in 3.01 Mb of Srpt sequence. This overall transcript density is similar (within approximately 10%) to that found genome-wide. Zinc finger-containing genes and olfactory receptor genes are duplicated within and between multiple telomere regions.