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In a locally interacting many-body system, two isolated qubits, separated by a large distance r, become correlated and entangled with each other at a time t≥r/v. This finite speed v of quantum information scrambling limits quantum information processing, thermalization, and even equilibrium correlations. Yet most experimental systems contain long range power-law interactions-qubits separated by r have potential energy V(r)∝r^{-α}. Examples include the long range Coulomb interactions in plasma (α=1) and dipolar interactions between spins (α=3). In one spatial dimension, we prove that the speed of quantum scrambling remains finite for sufficiently large α. This result parametrically improves previous bounds, compares favorably with recent numerical simulations, and can be realized in quantum simulators with dipolar interactions. Our new mathematical methods lead to improved algorithms for classically simulating quantum systems, and improve bounds on environmental decoherence in experimental quantum information processors.

Pretargeting is an increasingly explored strategy to improve nanoparticle targeting, in which pretargeting molecules that bind both selected epitopes on target cells and nanocarriers are first administered, followed by the drug-loaded nanocarriers. Bispecific antibodies (bsAb) represent a promising class of pretargeting molecules, but how different bsAb formats may impact the efficiency of pretargeting remains poorly understood, in particular Fab valency and Fc receptor (FcR)-binding of bsAb. We found the tetravalent bsAb markedly enhanced PEGylated nanoparticle binding to target HER2 + cells relative to the bivalent bsAb in vitro. Pretargeting with tetravalent bsAb with abrogated FcR binding increased tumor accumulation of PEGylated liposomal doxorubicin (PLD) 3-fold compared to passively targeted PLD alone, and 5-fold vs pretargeting with tetravalent bsAb with normal FcR binding in vivo. Our work demonstrates that multivalency and elimination of FcRn recycling are both important features of pretargeting molecules, and further supports pretargeting as a promising nanoparticle delivery strategy., (Published by Elsevier Inc.)

Hepatitis C virus (HCV)-specific T cell responses are critical for immune control of infection. Viral adaptation to these responses, via mutations within regions of the virus targeted by CD8 + T cells, is associated with viral persistence. However, identifying viral adaptation to HCV-specific CD4 + T cell responses has been difficult although key to understanding anti-HCV immunity. In this context, HCV sequence and host genotype from a single source HCV genotype 1B cohort (n = 63) were analyzed to identify viral changes associated with specific human leucocyte antigen (HLA) class II alleles, as these variable host molecules determine the set of viral peptides presented to CD4 + T cells. Eight sites across the HCV genome were associated with HLA class II alleles implicated in infection outcome in this cohort (p ≤ 0.01; Fisher's exact test). We extended this analysis to chronic HCV infection (n = 351) for the common genotypes 1A and 3A. Variation at 38 sites across the HCV genome were associated with specific HLA class II alleles with no overlap between genotypes, suggestive of genotype-specific T cell targets, which has important implications for vaccine design. Here we show evidence of HCV adaptation to HLA class II-restricted CD4 + T cell pressure across the HCV genome in chronic HCV infection without a priori knowledge of CD4 + T cell epitopes.

Major advances in carrier-mediated agents (CMAs), which include nanoparticles, nanosomes, and conjugates, have revolutionized drug delivery capabilities over the past decade. While providing numerous advantages, such as greater solubility, duration of exposure, and delivery to the site of action over their small molecule counterparts, there is substantial variability in systemic clearance and distribution, tumor delivery, and pharmacologic effects (efficacy and toxicity) of these agents. In this chapter, we focus on the analytical and phenotypic methods required to design a study that characterizes the pharmacokinetics (PK) and pharmacodynamics (PD) of all forms of these nanoparticle-based drug agents. These methods include separation of encapsulated and released drugs, ultrafiltration for measurement of non-protein bound active drug, microdialysis to measure intra-tumor drug concentrations, immunomagnetic separation and flow cytometry for sorting cell types, and evaluation of spatial distribution of drug forms relative to tissue architecture by mass spectrometry imaging and immunohistochemistry.

The mononuclear phagocyte system (MPS) has previously been shown to significantly affect the clearance, tumor delivery, and efficacy of nanoparticles (NPs). This study profiled MPS cell infiltration in murine preclinical tumor models and evaluated how these differences may affect tumor disposition of PEGylated liposomal doxorubicin (PLD) in models sensitive and resistant to PLD. Significant differences in MPS presence existed between tumor types (e.g. ovarian versus endometrial), cell lines within the same tumor type, and location of tumor implantation (i.e. flank versus orthotopic xenografts). Further, the differences in MPS presence of SKOV-3 ovarian and HEC1A endometrial orthotopic cancer models may account for the 2.6-fold greater PLD tumor exposure in SKOV-3, despite similar plasma, liver and spleen exposures. These findings suggest that profiling the presence of MPS cells within and between tumor types is important in tumor model selection and in tumor types and patients likely to respond to NP treatment., (Copyright © 2016. Published by Elsevier Inc.)

Nanoparticles (NP) including liposomes are cleared by phagocytes of the mononuclear phagocyte system. High inter-patient variability in pharmacokinetics of PEGylated liposomal doxorubicin (PLD) has been reported. We hypothesized that genetic factors may be associated with the variable disposition of PLD. We evaluated plasma and tissue disposition of doxorubicin after administration of PLD at 6mg/kg IV ×1 via tail vein in 23 different male inbred mouse strains. An approximately 13-fold difference in plasma clearance of PLD was observed among inbred strains. We identified a correlation between strain-specific differences in PLD clearance and genetic variation within a genomic region encoding GULP1 (PTB domain containing engulfment adapter 1) protein using haplotype associated mapping and the efficient mixed-model association algorithms. Our results also show that Gulp1 expression in adipose tissue was associated with PLD disposition in plasma. Our findings suggest that genetic variants may be associated with inter-individual pharmacokinetic differences in NP clearance., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Major advances in carrier-mediated agents (CMAs), which include nanoparticles and conjugates, have revolutionized drug delivery capabilities over the past decade. While providing numerous advantages over their small-molecule counterparts, there is substantial variability in how individual CMA formulations and patient characteristics affect the pharmacology, pharmacokinetics (PK), and pharmacodynamics (PD) (efficacy and toxicity) of these agents. Development or selection of animal models is used to predict the effects within a particular human disease. A breadth of studies have begun to emphasize the importance of preclinical animal models in understanding and evaluating the interaction between CMAs and the immune system and tumor matrix, which ultimately influences CMA PK (clearance and distribution) and PD (efficacy and toxicity). It is fundamental to study representative preclinical tumor models that recapitulate patients with diseases (e.g., cancer) and evaluate the interplay between CMAs and the immune system, including the mononuclear phagocyte system (MPS), chemokines, hormones, and other immune modulators. Furthermore, standard allometric scaling using body weight does not accurately predict drug clearance in humans. Future studies are warranted to better understand the complex pharmacology and interaction of CMA carriers within individual preclinical models and their biological systems, such as the MPS and tumor microenvironment, and their application to allometric scaling across species. WIREs Nanomed Nanobiotechnol 2016, 8:642-653. doi: 10.1002/wnan.1394 For further resources related to this article, please visit the WIREs website., (© 2016 Wiley Periodicals, Inc.)

Background: Chemokines are important mediators of inflammatory cell recruitment that play a significant role in atherosclerosis. Fractalkine (CX3CL1) is an unusual membrane-bound chemokine that mediates chemotaxis through the CX3CR1 receptor. Recently, functional polymorphisms in the human CX3CR1 gene have been described that are associated with coronary artery disease., Methods and Results: We investigated the expression of the CX3C chemokine fractalkine and its receptor CX3CR1 in human coronary artery plaques by immunocytometry. We show that a subset of mononuclear cells expresses high levels of fractalkine in human coronary atherosclerotic plaques and that smooth muscle cells within the neointima express the fractalkine receptor CX3CR1. There is a positive correlation between the number of fractalkine-expressing cells and the number of CX3CR1-positive cells in human atherosclerotic plaques (r=0.70, n=15 plaques). Furthermore, we demonstrate that cultured vascular smooth muscle cells express the CX3CR1 receptor and undergo chemotaxis to fractalkine that can be inhibited by G protein inactivation by pertussis toxin., Conclusions: These results suggest that in human atherosclerosis, fractalkine, rather than mediating inflammatory cell recruitment, can act as a mediator of smooth muscle cell migration.