Conceptualization of a Parasympathetic Endocrine System.

We here propose a parasympathetic endocrine system (PES) comprised of circulating peptides released from secretory cells in the gut, significantly modulated by vagal projections from the dorsal motor nucleus of the vagus (DMV). While most of these gut peptides mediate well-described satiety and digestive effects that increase parasympathetic control of digestion (Lee et al., 1994; Gutzwiller et al., 1999; Klok et al., 2007), they also have actions that are far-reaching and increase parasympathetic signaling broadly throughout the body. The actions beyond satiety that peptides like somatostatin, cholecystokinin, glucagon-like peptide 1, and vasoactive intestinal peptide have been well-examined, but not in a systematic way. Consideration has been given to the idea that these and other gut-derived peptides are part of an endocrine system has been partially considered (Rehfeld, 2012; Drucker, 2016), but that it is coordinated through parasympathetic control and may act to increase the actions of parasympathetic projections has not been formalized before. Here only gut-derived hormones are included although there are potentially other parasympathetically mediated factors released from other sites like lung and liver (Drucker, 2016). The case for the existence of the PES with the DMV as its integrative controller will be made through examination of an anatomical substrate and evidence of physiological control mechanisms as well as direct examples of PES antagonism of sympathetic signaling in mammals, including humans. The implications for this conceptual understanding of a PES reframe diseases like metabolic syndrome and may help underscore the role of the autonomic nervous system in the associated symptoms

Input-output signal processing plasticity of vagal motor neurons in response to cardiac ischemic injury.

Vagal stimulation is emerging as the next frontier in bioelectronic medicine to modulate peripheral organ health and treat disease. The neuronal molecular phenotypes in the dorsal motor nucleus of the vagus (DMV) remain largely unexplored, limiting the potential for harnessing the DMV plasticity for therapeutic interventions. We developed a mesoscale single-cell transcriptomics data from hundreds of DMV neurons under homeostasis and following physiological perturbations. Our results revealed that homeostatic DMV neuronal states can be organized into distinguishable input-output signal processing units. Remote ischemic preconditioning induced a distinctive shift in the neuronal states toward diminishing the role of inhibitory inputs, with concomitant changes in regulatory microRNAs miR-218a and miR-495. Chronic cardiac ischemic injury resulted in a dramatic shift in DMV neuronal states suggestive of enhanced neurosecretory function. We propose a DMV molecular network mechanism that integrates combinatorial neurotransmitter inputs from multiple brain regions and humoral signals to modulate cardiac health

A Physiologically-Based Pharmacokinetic Model for Targeting Calcitriol-Conjugated Quantum Dots to Inflammatory Breast Cancer Cells.

Quantum dots (QDs) conjugated with 1,25 dihydroxyvitamin D3 (calcitriol) and Mucin-1 (MUC-1) antibodies (SM3) have been found to target inflammatory breast cancer (IBC) tumors and reduce proliferation, migration, and differentiation of these tumors in mice. A physiologically-based pharmacokinetic model has been constructed and optimized to match experimental data for multiple QDs: control QDs, QDs conjugated with calcitriol, and QDs conjugated with both calcitriol and SM3 MUC1 antibodies. The model predicts continuous QD concentration for key tissues in mice distinguished by IBC stage (healthy, early-stage, and late-stage). Experimental and clinical efforts in QD treatment of IBC can be augmented by in silico simulations that predict the short-term and long-term behavior of QD treatment regimens

The Emergence of Cardioprotection from the Brain-Gut-Heart Network

Cardiovascular disease is the largest cause of mortality with more than 2,200 individuals dying daily in the United States alone. Many of these patients suffer from heart failure, the treatments for which have not been able to improve the 50% five year mortality. The use of nonpharmacological interventions like vagal stimulation and ischemic preconditioning have demonstrated great potential, but poor consistency, in treating patients, highlighting the need to better understand the mechanisms by which these treatments work in order to improve consistency and efficacy. The dorsal motor nucleus of the vagus (DMV), which gives rise to vagal efferent projections, has been shown to be essential in mediating these effects. However there is currently limited understanding of the functional heterogeneity of neurons in the DMV, which limits the ability to design better vagal stimulation treatments or to capitalize on recapitulating other vagally mediated cardioprotective effects. In order to develop a better understanding of DMV heterogeneity and elucidate how this heterogeneity might shift to drive cardioprotection, we have taken molecular profiling approach on a single cell level. Such an approach takes advantage of gene regulatory networks and transcriptional patterns to discern biological function. We start with a first-of-its-kind manipulation of gene regulatory networks in the dorsal vagal complex using antisense locked nucleic acids targeted against two specific microRNAs that renormalizes blood pressure in the spontaneously hypertensive rat. These effects are specific to the hypertensive strain with little effect on the normotensive strains due in part to different underlying regulatory network structure. Such networks can be nudged by altering microRNA expression enough to drive physiological effects in the whole body system of hypertensive animals without appreciable perturbation of the already healthy networks of the normotensive animals. From here we develop a framework for understanding the transcriptional heterogeneity in DMV neurons specifically, generating phenotypic classifications. The results suggest that the traditional means of classifying neurons, by neurotransmitters or connectivity, does not have a strong underlying rationale based upon the transcriptional patterns we have observed. The rate limiting enzymes that generate neurotransmitters are often coexpressed with several others in the same neuron. This foundation permits even subtle shifts in neuronal populations to be observed, as is the case under remote ischemic preconditioning. We observe an increase in the number of neurons expressing excitatory H1 histamine receptors, which also have increased expression of tachykinin precursors and atrial naturetic peptide. This suggests a novel role for tuberomammillary projections to the DMV in the mediation of cardioprotection. Over several weeks in the development of heart failure after myocardial infarction, we observe a phenotypic shift in DMV neurons toward a neurosecretory phenotype, driven in part by transcription factors primarily active during embryonic development. This suggests not only that the DMV is responsive to heart failure, but also that the neurons are able to change phenotype to do so. Such phenotypic plasticity leads to consideration of the DMV, and the autonomic nervous system, as capable of adaptive responses rather than mere reflex mediation. Given the large number of DMV projections to the gut, there is further evidence of a brain-gut-heart network that mediates vagal cardioprotection and cardiovascular health as a whole. If we are to find more successful treatments of cardiovascular disease, it is important to consider this and not just treat the heart, but treat the whole network supporting it

Investigating the Effects of Brainstem Neuronal Adaptation on Cardiovascular Homeostasis.

Central coordination of cardiovascular function is accomplished, in part, by the baroreceptor reflex, a multi-input multi-output physiological control system that regulates the activity of the parasympathetic and sympathetic nervous systems via interactions among multiple brainstem nuclei. Recent single-cell analyses within the brain revealed that individual neurons within and across brain nuclei exhibit distinct transcriptional states contributing to neuronal function. Such transcriptional heterogeneity complicates the task of understanding how neurons within and across brain nuclei organize and function to process multiple inputs and coordinate cardiovascular functions within the larger context of the baroreceptor reflex. However, prior analysis of brainstem neurons revealed that single-neuron transcriptional heterogeneity reflects an adaptive response to synaptic inputs and that neurons organize into distinct subtypes with respect to synaptic inputs received. Based on these results, we hypothesize that adaptation of neuronal subtypes support robust biological function through graded cellular responses. We test this hypothesis by examining the functional impact of neuronal adaptation on parasympathetic activity within the context of short-term baroreceptor reflex regulation. In this work, we extend existing quantitative closed-loop models of the baroreceptor reflex by incorporating into the model distinct input-driven neuronal subtypes and neuroanatomical groups that modulate parasympathetic activity. We then use this extended model to investigate, via simulation, the functional role of neuronal adaptation under conditions of health and systolic heart failure. Simulation results suggest that parasympathetic activity can be modulated appropriately by the coordination of distinct neuronal subtypes to maintain normal cardiovascular functions under systolic heart failure conditions. Moreover, differing degrees of adaptation of these neuronal subtypes contribute to cardiovascular behaviors corresponding to distinct clinical phenotypes of heart failure, such as exercise intolerance. Further, our results suggest that an imbalance between sympathetic and parasympathetic activity regulating ventricular contractility contributes to exercise intolerance in systolic heart failure patients, and restoring this balance can improve the short-term cardiovascular performance of these patients

A simple and accurate rule-based modeling framework for simulation of autocrine/paracrine stimulation of glioblastoma cell motility and proliferation by L1CAM in 2-D culture

Abstract Background Glioblastoma multiforme (GBM) is a devastating brain cancer for which there is no known cure. Its malignancy is due to rapid cell division along with high motility and invasiveness of cells into the brain tissue. Simple 2-dimensional laboratory assays (e.g., a scratch assay) commonly are used to measure the effects of various experimental perturbations, such as treatment with chemical inhibitors. Several mathematical models have been developed to aid the understanding of the motile behavior and proliferation of GBM cells. However, many are mathematically complicated, look at multiple interdependent phenomena, and/or use modeling software not freely available to the research community. These attributes make the adoption of models and simulations of even simple 2-dimensional cell behavior an uncommon practice by cancer cell biologists. Results Herein, we developed an accurate, yet simple, rule-based modeling framework to describe the in vitro behavior of GBM cells that are stimulated by the L1CAM protein using freely available NetLogo software. In our model L1CAM is released by cells to act through two cell surface receptors and a point of signaling convergence to increase cell motility and proliferation. A simple graphical interface is provided so that changes can be made easily to several parameters controlling cell behavior, and behavior of the cells is viewed both pictorially and with dedicated graphs. We fully describe the hierarchical rule-based modeling framework, show simulation results under several settings, describe the accuracy compared to experimental data, and discuss the potential usefulness for predicting future experimental outcomes and for use as a teaching tool for cell biology students. Conclusions It is concluded that this simple modeling framework and its simulations accurately reflect much of the GBM cell motility behavior observed experimentally in vitro in the laboratory. Our framework can be modified easily to suit the needs of investigators interested in other similar intrinsic or extrinsic stimuli that influence cancer or other cell behavior. This modeling framework of a commonly used experimental motility assay (scratch assay) should be useful to both researchers of cell motility and students in a cell biology teaching laboratory

A Comprehensive Integrated Anatomical and Molecular Atlas of Rat Intrinsic Cardiac Nervous System.

We have developed and integrated several technologies including whole-organ imaging and software development to support an initial precise 3D neuroanatomical mapping and molecular phenotyping of the intracardiac nervous system (ICN). While qualitative and gross anatomical descriptions of the anatomy of the ICN have each been pursued, we here bring forth a comprehensive atlas of the entire rat ICN at single-cell resolution. Our work precisely integrates anatomical and molecular data in the 3D digitally reconstructed whole heart with resolution at the micron scale. We now display the full extent and the position of neuronal clusters on the base and posterior left atrium of the rat heart, and the distribution of molecular phenotypes that are defined along the base-to-apex axis, which had not been previously described. The development of these approaches needed for this work has produced method pipelines that provide the means for mapping other organs