Parallel hippocampal-parietal circuits for self- and goal-oriented processing

The hippocampus is critically important for a diverse range of cognitive processes, such as episodic memory, prospective memory, affective processing, and spatial navigation. Using individual-specific precision functional mapping of resting-state functional MRI data, we found the anterior hippocampus (head and body) to be preferentially functionally connected to the default mode network (DMN), as expected. The hippocampal tail, however, was strongly preferentially functionally connected to the parietal memory network (PMN), which supports goal-oriented cognition and stimulus recognition. This anterior–posterior dichotomy of resting-state functional connectivity was well-matched by differences in task deactivations and anatomical segmentations of the hippocampus. Task deactivations were localized to the hippocampal head and body (DMN), relatively sparing the tail (PMN). The functional dichotomization of the hippocampus into anterior DMN-connected and posterior PMN-connected parcels suggests parallel but distinct circuits between the hippocampus and medial parietal cortex for self- versus goal-oriented processing.

The hippocampus is critically important for a diverse range of cognitive processes, such as episodic and prospective memory, affective processing, and spatial navigation (1–7). The hippocampus’ diverse functions rely on its pattern of connectivity (8). Atypical cortico-hippocampal functional connectivity is associated with cognitive and affective deficits (9–12). A precise understanding of the functional organization of the hippocampus is crucial for understanding the neurobiology underlying hippocampally related diseases.The hippocampus seems to exhibit functional heterogeneity along its longitudinal axis (anterior–posterior in humans; ventral–dorsal in rodents). Studies of the rodent hippocampus have demonstrated modular differentiation along its longitudinal axis in patterns of gene expression, function, and anatomical projections (2, 13, 14). The rodent ventral hippocampus (anterior in humans) plays a role in the modulation of stress and affect (2, 4), whereas the dorsal hippocampus (posterior in humans) is important for spatial navigation. Hippocampal place field representation sizes in rodent models also follow a ventral–dorsal gradient reflecting large-to-small spatial resolution (13, 14). The ventral hippocampus in rats is anatomically interconnected with the amygdala, temporal pole, and ventromedial prefrontal cortex (4, 15), while the dorsal hippocampus is connected with the anterior cingulate and retrosplenial cortex (4, 15).In humans, evidence for structural differentiation between the anterior and posterior hippocampus is provided by age and Alzheimer’s disease–related hippocampal volume reduction differences (16) and diffusion tractography (17). Functional MRI (fMRI) research has suggested an anterior–posterior gradient in coarse-to-fine mnemonic spatiotemporal representations (18), such that anterior hippocampus supports schematics, while specific details associated with a given event are represented in posterior hippocampus (6, 7). Similarly, other studies have suggested anterior–posterior hippocampal differences in pattern completion (i.e., integrating indirectly related events) and pattern separation (i.e., discriminating between separate but similar events) (19).Resting-state functional connectivity (RSFC) studies in humans have provided additional insights into the hippocampal connectivity that underlies hippocampus-mediated cognition. RSFC exploits the phenomenon that even in the absence of overt tasks, spatially separated but functionally related regions exhibit correlations in blood oxygen level–dependent (BOLD) signal (20–24). Group-averaged RSFC studies have found the hippocampus to be functionally connected to the default mode network (DMN) (25–28). The DMN is deactivated by attention-demanding tasks and thought to be important for self-referential processes, such as autobiographical memory, introspection, emotional processing, and motivation (26). Other group-averaged RSFC studies have reported the anterior hippocampus to be preferentially functionally connected to anterior parts of the DMN, while the posterior hippocampus was more strongly connected to the posterior DMN via the perirhinal and parahippocampal gyri (29–32).Recent precision functional mapping studies have highlighted that RSFC group-averaging approaches obscure individual differences in network architecture in both the cortex and subcortical structures (33–41). The large amounts of RSFC data utilized (>300 min per subject) in precision functional mapping improve the signal-to-noise ratio and allow for the replicable detection of additional functional neuroanatomical detail in the cerebral cortex (34), cerebellum (33), basal ganglia, thalamus (35, 42), and amygdala (36). In a small, deep-lying structure like the hippocampus, group-averaging RSFC data may be even more problematic.The medial parietal cortex is one of the main targets of hippocampal anatomical and functional connectivity (4, 15, 43–47) and was previously considered part of the DMN (25–28). The medial parietal cortex encompasses the swath of posterior midline neocortex between motor and visual regions. It includes the retrosplenial cortex, posterior cingulate, and precuneus (Brodmann Area 7, 23, 26, 29, 30, and 31). More recent studies revealed that parts of the medial parietal cortex belong to the parietal memory network (PMN) and the contextual association network (CAN) (23, 34, 39, 41, 48, 49). The PMN and CAN are immediately adjacent to the DMN in medial parietal cortex and therefore easily confounded in group-averaged data. The CAN (34, 41) corresponds to Braga et al.’s DMN subnetwork B (39). The identification of multiple different networks (DMN, PMN, CAN, and FPN [fronto-parietal network]) in medial parietal cortex reflects the ongoing recognition of novel networks, subnetworks, and organizational principles driven by precision functional mapping (23, 34, 39, 41, 50–52).The DMN, PMN, and CAN are all thought to be important for memory. The DMN and PMN have been associated with different aspects of episodic memory processing. Autobiographical retrieval (i.e., memory over a lifetime) preferentially increases activity in the DMN, whereas memory for recently experienced events preferentially engages the PMN (27, 48, 53, 54). During explicit memory tasks, activity within the PMN decreases in response to novel stimuli but increases in response to familiar stimuli, such that increased activity seems to reflect attention to internal memory representations during retrieval (48, 55). The CAN processes associations between objects or places and their scenes (41, 56).Here, we utilized precision functional mapping to examine individual-specific, hippocampal-cortical functional connectivity. We utilized both the Midnight Scan Club (MSC) dataset (n = 10 participants; 300 min. of resting-state fMRI data/subject) (34) and additional extremely highly sampled, higher-resolution resting-state fMRI data (2.6 mm isotropic voxels; 2,610 min; MSC06-Rep) from an independent dataset (57, 58). We generated individual-specific RSFC parcellations of the hippocampus, drawing on several advantages over group-averaging, including the following: (1) higher signal-to-noise ratio in deeper subcortical structures without blurring individual differences in network features and (2) more precise definition of individual-specific cortical functional network maps (i.e., DMN, PMN, CAN, and FPN).     

Engineering genetic devices for in vivo control of therapeutic T cell activity triggered by the dietary molecule resveratrol

Chimeric antigen receptor (CAR)–engineered T cell therapies have been recognized as powerful strategies in cancer immunotherapy; however, the clinical application of CAR-T is currently constrained by severe adverse effects in patients, caused by excessive cytotoxic activity and poor T cell control. Herein, we harnessed a dietary molecule resveratrol (RES)–responsive transactivator and a transrepressor to develop a repressible transgene expression (RES_rep) device and an inducible transgene expression (RES_ind) device, respectively. After optimization, these tools enabled the control of CAR expression and CAR-mediated antitumor function in engineered human cells. We demonstrated that a resveratrol-repressible CAR expression (RES_rep-CAR) device can effectively inhibit T cell activation upon resveratrol administration in primary T cells and a xenograft tumor mouse model. Additionally, we exhibit how a resveratrol-inducible CAR expression (RES_ind-CAR) device can achieve fine-tuned and reversible control over T cell activation via a resveratrol-titratable mechanism. Furthermore, our results revealed that the presence of RES can activate RES_ind-CAR T cells with strong anticancer cytotoxicity against cells in vitro and in vivo. Our study demonstrates the utility of RES_rep and RES_ind devices as effective tools for transgene expression and illustrates the potential of RES_rep-CAR and RES_ind-CAR devices to enhance patient safety in precision cancer immunotherapies.

T cell therapy with tumor-targeted chimeric antigen receptor (CAR)–engineered T cells has proven to be a transformative cancer treatment for a range of target indications (1, 2). CARs are constructed via a surface-displayed single-chain antibody variable domain (scFv) coupled to intracellular signaling components, to endow patient-derived T cells with the ability to recognize antigens and subsequently eliminate tumor cells (3). Ever since the approval of CD19-specific CAR T cells for the treatment of B cell leukemias and lymphomas, dramatic clinical successes have been achieved and numerous CAR T cell products are emerging (4–7).Despite initial encouraging results, several challenges remain for CD19 CAR T cells, one main challenge being a lack of control over these engineered cells (8, 9). Rapid responses after large cell infusion doses can induce several immune-mediated side effects, such as cytokine release syndrome (CRS), tumor lysis syndrome, and neurotoxicity (10, 11). However, achieving potent therapeutic effects requires the robust expansion and sequential activation of a sufficient number of CAR T cells. Accordingly, it is a significant challenge to administrate appropriate doses of this “living drug” in order to balance in vivo efficacy and toxicity, further complicated by the highly divergent responses of patients (12–14).Synthetic devices have been shown to improve the safety and feasibility of CAR T cell therapy by regulating CAR expression and controlling T cell activation (15, 16). To mitigate immunotherapy toxicity, several safety devices have been developed to control engineered T cells in a “function-off” or “function-on” manner. Previous studies have reported several user-controlled function-off devices to eliminate infused T cells from patients exhibiting severe toxicity, including suicide devices (17, 18), antibody-based elimination devices (9, 19, 20), small molecule-controlled STOP-CAR devices (21), and photoswitchable CAR devices (22). However, function-off devices may be insufficient to ensure safety against toxicities induced immediately upon cell infusion.Complementary strategies using a function-on approach include several inducible devices with tunable CAR T cell function control: small molecule-inducible CAR devices (23–27), intermediary antibody or protein-based CAR devices (28–30), as well as light/ultrasound-responsive noninvasive devices (31–33). Synthetic Notch (synNotch) receptor-based circuits were also designed to enhance the precision of tumor recognition (34–38). Although these devices theoretically enable safer CAR T cell therapies, synthetic modules controlled by even safer natural molecules capable of diffusing throughout the entire body would offer a more versatile mechanism of control. Further development of orthogonally regulated devices that enable facile control of CAR T cell functions to ensure safer device control in immunotherapy is needed.The stilbenoid natural product resveratrol (RES, 3,4′,5-trihydroxystilbene), notably present in red wine, grapes, peanuts, and berries, has been shown to be a safe inducer compound for genetic devices designed for therapeutic applications (39). Beyond its demonstrated utility in genetic engineering applications, this molecule possesses wide-ranging beneficial effects, including clinical evidence for activities against aging, cancer, cardiovascular diseases, and inflammation (40–43).To enable safer strategies for cancer immunotherapy with both a function-off and function-on modality, we designed a resveratrol-repressible transgene expression (RES_rep) device and a resveratrol-inducible transgene expression (RES_ind) device based on resveratrol-responsive regulatory elements. We demonstrate that our RES_rep and RES_ind devices can reversibly and flexibly control transgene expression in vitro and in vivo in a highly tunable manner. We further apply these devices to control CAR expression and CAR-mediated cell activities by developing a resveratrol-repressible CAR expression (RES_rep-CAR) device and a resveratrol-inducible transgene expression (RES_ind-CAR) device. We then demonstrate that the RES_rep-CAR device can repress CAR expression and CAR-mediated cell activation in primary human T cells and a xenograft mouse model of leukemia, all with triggerable T cell inactivity in case of severe toxicity. We further confirm the titratable and reversible capabilities of the RES_ind-CAR device for both CAR expression and T cell activity in vitro and in vivo; this is a feature that could allow physicians to precisely control T cell activity by adjusting the dosage of resveratrol according to the clinical responses of individual patients. These resveratrol-controlled transgene expression devices extend synthetic biology-inspired tools to clinically relevant applications and provide potential strategies for improving the safety of T cell immunotherapies by preventing fatal toxicity in clinical settings.     

Complex drug interactions of HIV protease inhibitors 2: in vivo induction and in vitro to in vivo correlation of induction of cytochrome P450 1A2, 2B6, and 2C9 by ritonavir or nelfinavir

Drug-drug interactions (DDIs) with the HIV protease inhibitors (PIs) are complex, paradoxical (e.g., ritonavir/alprazolam), and involve multiple mechanisms. As part of a larger study to better understand these DDIs and to devise a framework for in vitro to in vivo prediction of these DDIs, we determined the inductive effect of ～2 weeks of administration of two prototypic PIs, nelfinavir (NFV), ritonavir (RTV), and rifampin (RIF; induction positive control) on the cytochrome P450 enzymes CYP1A2, CYP2B6, CYP2C9, and CYP2D6 and the inductive or inductive plus inhibitory effect of NFV, RTV, or RIF on CYP3A and P-glycoprotein in healthy human volunteers. Statistically significant induction of CYP1A2 (2.1-, 2.9-, and 2.2-fold), CYP2B6 (1.8-, 2.4-, and 4-fold), and CYP2C9 (1.3-, 1.8-, and 2.6-fold) was observed after NFV, RTV, or RIF treatment, respectively (as expected, CYP2D6 was not induced). Moreover, we accurately predicted the in vivo induction of these enzymes by quantifying their induction by the PIs in human hepatocytes and by using RIF as an in vitro to in vivo scalar. On the basis of the modest in vivo induction of CYP1A2, CYP2B6, or CYP2C9, the in vivo paradoxical DDIs with the PIs are likely explained by mechanisms other than induction of these enzymes such as induction of other metabolic enzymes, transporters, or both.     

Effect of different durations and formulations of diltiazem on the single-dose pharmacokinetics of midazolam: how long do we go?

Understanding how inhibition of cytochrome P4503A (CYP3A) affects the metabolism of a new drug is critical in determining if a clinically relevant drug interaction will occur. Diltiazem interaction studies assess a given compound's sensitivity to moderate CYP3A inhibition. The present study compared the effect different durations and formulations of diltiazem (extended release [XR] and conventional release [CR]) had on the single-dose pharmacokinetics of midazolam. The geometric mean ratio (GMR; midazolam + diltiazem(XR × 5 days)/midazolam + diltiazem(XR × 2 days)) for midazolam AUC(0-∞) was 0.98 (90% confidence interval [CI], 0.87, 1.10). The GMR (midazolam + diltiazem(XR × 2 days)/midazolam + diltiazem(CR × 2 days)) for midazolam AUC(0-∞) was 0.82 (90% CI, 0.73, 0.92). Simcyp simulations accurately predicted the observed clinical results only when a hepatic CYP3A degradation rate (k(deg)) different from that provided by the software was used. The data suggest that dosing diltiazem XR for 2 days predicts the change in midazolam AUC as reliably as 5 days of XR dosing and 2 days of CR dosing. In addition, the authors believe that a hepatic CYP3A kdeg of 0.03 h(-1) should be considered for future Simcyp studies.     

The evolution of histamine H₃ antagonists/inverse agonists

This article describes our efforts along with recent advances in the development, biological evaluation and clinical proof of concept of small molecule histamine H? antagonists/inverse agonists. The H3 receptor is a presynaptic autoreceptor within the Class A GPCR family, but also functions as a heteroreceptor modulating levels of neurotransmitters such as dopamine, acetylcholine, norepinephrine, serotonin, GABA and glutamate. Thus, H?R has garnered a great deal of interest from the pharmaceutical industry for the possible treatment of obesity, epilepsy, sleep/wake, schizophrenia, Alzheimer's disease, neuropathic pain and ADHD. Within the two main classes of H? ligands, both imidazole and non-imidazole derived, have shown sufficient potency and specificity which culminated with efficacy in preclinical models for various CNS disorders. Importantly, conserved elements have been identified within the small molecule H? ligand scaffolds that resulted in a highly predictive pharmacophore model. Understanding of the pharmacophore model has allowed several groups to dial H?R activity into scaffolds designed for other CNS targets, and engender directed polypharmacology. Moreover, Abbott, GSK, Pfizer and several others have reported positive Phase I and/or Phase II data with structurally diverse H?R antagonists/inverse agonists.     

Hospital racial composition and the treatment of localized prostate cancer

BACKGROUND:

Racial differences in the treatment of men with localized prostate cancer remain poorly understood. This study examines whether hospital racial composition is associated with the type of treatment black and white men receive.

METHODS:

The authors performed a retrospective cohort study of men in Surveillance, Epidemiology, and End Results‐Medicare diagnosed with localized prostate cancer from 1995 to 2005 linked to hospital and census data. A total of 134,291 men were assigned to the hospital where they received care. Generalized estimating equations were used to determine whether hospital racial composition was associated with the receipt of definitive therapy and type of treatment.

RESULTS:

Black men were less likely to receive radiation and/or prostatectomy compared with white men (55.5% vs 63.7%, P < .001) and, among those who received definitive therapy, were less likely to undergo prostatectomy (27.5% vs 31.9%, P < .001). The percentage of black men who received their care at hospitals with a high proportion of black patients was 48.0%, compared with only 5.2% of white patients who received care in this subset of hospitals. Men were significantly less likely to receive definitive treatment (odds ratio, 0.81; 95% confidence interval, 0.74‐0.90) in hospitals with a high proportion of black patients compared with men seen at hospitals with fewer black patients. The association between hospital racial composition and treatment did not significantly differ by patient race.

CONCLUSIONS:

Hospital racial composition is consistently associated with the care that men receive for localized prostate cancer. Better understanding of the factors that determine where men receive care is an important component in reducing variation in treatment. Cancer 2011;. © 2011 American Cancer Society.     

The PHSCN dendrimer as a more potent inhibitor of human breast cancer cell invasion, extravasation, and lung colony formation

The ??5??1 integrin fibronectin receptor is an attractive therapeutic target in breast cancer because it plays key roles in invasion and metastasis. While its inactive form is widely expressed, activated ??5??1 occurs only on tumor cells and their associated vasculature. The PHSCN peptide has been shown to bind activated ??5??1 preferentially, thereby blocking invasion in vitro, and inhibiting growth, metastasis and tumor recurrence in preclinical models. Moreover in a recent Phase I clinical trial, systemic PHSCN monotherapy was well tolerated, and metastatic disease failed to progress for 4?C14?months in 38% of patients receiving it. A significantly more potent PHSCN derivative, the PHSCN?Cpolylysine dendrimer (Ac-PHSCNGGK-MAP) has recently been developed. We report that it is 1280- to 6700-fold more potent than the PHSCN peptide at blocking ??5??1 mediated SUM-149 PT and MDA-MB-231 human breast cancer cell invasion of naturally occurring basement membranes in vitro. Chou?CTalalay analysis of these data suggested that invasion inhibition by the PHSCN dendrimer was highly synergistic. We also report that, consistent with its enhanced invasion-inhibitory potency, the PHSCN dendrimer is 700- to 1100-fold more effective than the PHSCN peptide at preventing SUM-149 PT and MDA-MB-231 extravasation in the lungs of athymic, nude mice. Our results also show that many extravasated SUM-149 PT and MDA-MB-231 cells go on to develop into metastatic colonies, and that pretreatment with the PHSCN dendrimer is more than 100-fold more effective at reducing lung colony formation. Since many patients newly diagnosed with breast cancer already have locally advanced or metastatic disease, the availability of a well-tolerated, nontoxic systemic therapy that can prevent metastatic progression by blocking invasion could be very beneficial.     

Potent kinetic stabilizers that prevent transthyretin-mediated cardiomyocyte proteotoxicity

A valine-to-isoleucine mutation at position 122 of the serum protein transthyretin (TTR), found in 3 to 4% of African Americans, alters its stability, leading to amyloidogenesis and cardiomyopathy. In addition, 10 to 15% of individuals older than 65 years develop senile systemic amyloidosis and cardiac TTR deposits because of wild-type TTR amyloidogenesis. Although several drugs are in development, no approved therapies for TTR amyloid cardiomyopathy are yet available, so the identification of additional compounds that prevent amyloid-mediated cardiotoxicity is needed. To this aim, we developed a fluorescence polarization-based high-throughput screen and used it to identify several new chemical scaffolds that target TTR. These compounds were potent kinetic stabilizers of TTR and prevented TTR tetramer dissociation, partial unfolding, and aggregation of both wild type and the most common cardiomyopathy-associated TTR mutant, V122I-TTR. High-resolution co-crystal structures and characterization of the binding energetics revealed how these diverse structures bound to tetrameric TTR. These compounds effectively inhibited the proteotoxicity of V122I-TTR toward human cardiomyocytes. Several of these ligands stabilized TTR in human serum more effectively than diflunisal, which is a well-studied inhibitor of TTR aggregation, and may be promising leads for the treatment or prevention of TTR-mediated cardiomyopathy.