Cross-species Model Research Articles

549. Endogenous Functional Organization and Clinical Extension of a Cross-Species Model of Persistent Avoidance in Obsessive Compulsive Disorder (OCD)

549. Endogenous Functional Organization and Clinical Extension of a Cross-Species Model of Persistent Avoidance in Obsessive Compulsive Disorder (OCD)

Time-series biological responses toward decellularized bovine tendon graft and autograft for 52 consecutive weeks after rat anterior cruciate ligament reconstruction

There is an essential demand for developing biocompatible grafts for knee anterior cruciate ligament reconstruction (ACLR). This study investigated cell infiltration into decellularized bovine tendon xenografts using a rat knee ACLR model. Twelve-week-old Sprague–Dawley rats were used. At weeks 1, 2, 4, 8, 16, 26, and 52 (each period, n = 6) after ACLR, rats receiving decellularized bovine tendon (group D, n = 42) or autologous tendon (group A, n = 42) as grafts underwent peritibial bone tunnel bone mineral density (BMD), histological, and immunohistological assessments. BMD increased over time in both the groups until week 16 and then remained unchanged without exhibiting significant differences between the groups. Initially, cellularity in group D was lower than that in group A; however, by weeks 4–8, both the groups were comparable to the native anterior cruciate ligament group and cellularity remained unchanged until week 52. Initially, group A had more M1 macrophages, indicating inflammation, whereas group D had more M2 macrophages, indicating tissue regeneration. Nonetheless, the M1 and M2 macrophage counts of both the groups were comparable at most times. This study revealed the excellent recellularization and tendon–bone integration abilities of decellularized tendons using a cross-species model.

Domain-adaptive neural networks improve cross-species prediction of transcription factor binding.

The intrinsic DNA sequence preferences and cell type–specific cooperative partners of transcription factors (TFs) are typically highly conserved. Hence, despite the rapid evolutionary turnover of individual TF binding sites, predictive sequence models of cell type–specific genomic occupancy of a TF in one species should generalize to closely matched cell types in a related species. To assess the viability of cross-species TF binding prediction, we train neural networks to discriminate ChIP-seq peak locations from genomic background and evaluate their performance within and across species. Cross-species predictive performance is consistently worse than within-species performance, which we show is caused in part by species-specific repeats. To account for this domain shift, we use an augmented network architecture to automatically discourage learning of training species–specific sequence features. This domain adaptation approach corrects for prediction errors on species-specific repeats and improves overall cross-species model performance. Our results show that cross-species TF binding prediction is feasible when models account for domain shifts driven by species-specific repeats.

Mouse Lymphoma Model-Based Senescence Exploitation to Predict Treatment Outcome of DLBCL Patients

Introduction: Molecularly informed treatment decisions are the basis of personalized cancer precision medicine. While gene expression profiling has been used to map the molecular landscape of tumors and to study the impact of molecularly defined subtypes on treatment outcome, biological effector principles, specifically cellular senescence, remain largely understudied. Syngeneic mouse models of cancer that recapitulate core molecular features of human malignancies could serve as useful models to explore mechanisms of drug sensitivity, and, likewise, to dissect molecular mechanisms of treatment failure. In particular, we focus here on the role of therapy-induced senescence, a histone H3 lysine 9 trimethylation (H3K9me3)-governed terminal cell-cycle arrest program.Methods: The Eµ- myc transgenic lymphoma mouse was used as a cross-species model of chemoresistance for patients diagnosed with diffuse large B-cell lymphoma (DLBCL). Gene expression profiles (GEP) of primary Eµ- myc lymphomas were obtained at diagnosis and after exposure to cyclophosphamide chemotherapy in vivo, with long-term outcome monitored in a clinical trial-like fashion. Lymphoma senescence capacity, a pivotal drug effector principle, was interrogated in mice by unbiased approaches as well as genetic perturbations.Results: DLBCL-established gene expression-based classifiers related to cell-of-origin (COO - i.e. GCB/ABC) subtypes and distinct DLBCL biologies (e.g. comprehensive consensus clusters [CCC]) were instrumental to identify comparable lymphoma subsets in the murine system. In turn, mice carrying senescence-defective lymphomas due to engineered loss of the H3K9me3 methyltransferase Suv39h1 or overexpression of the H3K9-active demethylase LSD1 succumbed faster to chemotherapy, as DLBCL patients with high LSD1 or low H3K9me3 expression in their lymphomas presented with significantly inferior outcome. Likewise, cross-species application of senescence-associated characteristics identified in unengineered primary mouse lymphomas unveiled molecular features important for treatment outcome in human DLBCL. Ongoing mouse model-based work aims at specific targeting of aberrant H3K9 demethylase activity to assess therapeutic long-term effects and to determine the conditions for future early-phase clinical testing in DLBCL patients.Conclusions: Primary Eµ- myc transgenic lymphomas serve as a faithful model for human DLBCL, since they share key pathologic and genetic features, including CCC/COO-based clustering. In turn, mouse lymphoma-based molecular exploration, genetic dissection and functional interrogation of treatment effector mechanisms, which is difficult to conduct in patient material, can be re-applied to molecularly and clinically co-annotated datasets from DLBCL patients to inform novel, lesion- and state-driven personalized treatment approaches and the design of future clinical trials. DisclosuresNo relevant conflicts of interest to declare.

A Cross-species Model of Dual-Task Walking in Young and Older Humans and Rats.

Introduction: Dual-task walking is common in daily life but becomes more difficult with aging. Little is known about the neurobiological mechanisms affecting competing cognitive demands. Translational studies with human and animal models are needed to address this gap. This pilot study investigated the feasibility of implementing a novel cross-species dual-task model in humans and rats and aimed to establish preliminary evidence that the model induces a dual-task cost.Methods: Young and older humans and rats performed an object discrimination task (OD), a baseline task of typical walking (baseline), an alternation turning task on a Figure 8 walking course (Alt), and a dual-task combining object discrimination with the alternation task (AltOD). Primary behavioral assessments including walking speed and correct selections for object discrimination and turning direction. In humans, left prefrontal cortex activity was measured with functional near-infrared spectroscopy (fNIRS).Results: Human subjects generally performed well on all tasks, but the older adults exhibited a trend for a slowing of walking speed immediately before the turning decision for Alt and AltOD compared to baseline. Older adults also had heightened prefrontal activity relative to young adults for the Alt and AltOD tasks. Older rodents required more training than young rodents to learn the alternation task. When tested on AltOD with and without a 15-s delay between trials, older rodents exhibited a substantial performance deficit for the delayed version on the initial day of testing. Old rats, however, did not show a significant slowing in walking speed with increasing task demand, as was evident in the young rats.Discussion: This study demonstrates the feasibility and challenges associated with implementing a cross-species dual-task model. While there was preliminary evidence of dual-task cost in both humans and rats, the magnitude of effects was small and not consistent across species. This is likely due to the relative ease of each task in humans and the walking component in rats not being sufficiently challenging. Future versions of this test should make the cognitive tasks more challenging and the motor task in rats more complex.

A novel cross-species model of Barlow's disease to biomechanically analyze repair techniques in an ex vivo left heart simulator

ObjectiveBarlow's disease remains challenging to repair, given the complex valvular morphology and lack of quantitative data to compare techniques. Although there have been recent strides in ex vivo evaluation of cardiac mechanics, to our knowledge, there is no disease model that accurately simulates the morphology and pathophysiology of Barlow's disease. The purpose of this study was to design such a model. MethodsTo simulate Barlow's disease, a cross-species ex vivo model was developed. Bovine mitral valves (n = 4) were sewn into a porcine annulus mount to create excess leaflet tissue and elongated chordae. A heart simulator generated physiologic conditions while hemodynamic data, high-speed videography, and chordal force measurements were collected. The regurgitant valves were repaired using nonresectional repair techniques such as neochord placement. ResultsThe model successfully imitated the complexities of Barlow's disease, including redundant, billowing bileaflet tissues with notable regurgitation. After repair, hemodynamic data confirmed reduction of mitral leakage volume (25.9 ± 2.9 vs 2.1 ± 1.8 mL, P < .001) and strain gauge analysis revealed lower primary chordae forces (0.51 ± 0.17 vs 0.10 ± 0.05 N, P < .001). In addition, the maximum rate of change of force was significantly lower postrepair for both primary (30.80 ± 11.38 vs 8.59 ± 4.83 N/s, P < .001) and secondary chordae (33.52 ± 10.59 vs 19.07 ± 7.00 N/s, P = .006). ConclusionsThis study provides insight into the biomechanics of Barlow's disease, including sharply fluctuating force profiles experienced by elongated chordae prerepair, as well as restoration of primary chordae forces postrepair. Our disease model facilitates further in-depth analyses to optimize the repair of Barlow's disease.

Enhancing Executive Functions Through Social Interactions: Causal Evidence Using a Cross-Species Model.

It has long been theorized that humans develop higher mental functions, such as executive functions (EFs), within the context of interpersonal interactions and social relationships. Various components of social interactions, such as interpersonal communication, perspective taking, and conforming/adhering to social rules, may create important (and perhaps even necessary) opportunities for the acquisition and continued practice of EF skills. Furthermore, positive and stable relationships facilitate the development and maintenance of EFs across the lifespan. However, experimental studies investigating the extent to which social experiences contribute causally to the development of EFs are lacking. Here, we present experimental evidence that social experiences and the acquisition of social skills influence the development of EFs. Specifically, using a rat model, we demonstrate that following exposure to early-life adversity, a socialization intervention causally improves working memory in peri-adolescence. Our findings combined with the broader literature promote the importance of cultivating social skills in support of EF development and maintenance across the lifespan. Additionally, cross-species research will provide insight into causal mechanisms by which social experiences influence cognitive development and contribute to the development of biologically sensitive interventions.

Survey design for quantifying perfluoroalkyl acid concentrations in fish, prawns and crabs to assess human health risks

Per and polyfluoroalkyl substances (PFASs) are emerging contaminants that have potential implications for human health. Perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) are perfluoroalkyl acids (PFAAs) that commonly bioaccumulate in aquatic species exposed to PFAS contaminant sources. Sampling programs aimed at measuring PFAA concentrations in free ranging aquatic animals to assess human health risk are not yet supported by any quantitative analyses to refine sampling effort required to provide a reasonable estimate of summary statistics for a species in a particular area. Here, an extensive, multi-species PFOS and PFHxS data set measured in free-ranging fish and crustaceans is employed to examine the effect of sample size on summary statistics estimated from sample data which are commonly employed in dietary exposure assessments. A unifying, cross-species model suggested that sample sizes between 20 and 40 individuals per species per location should provide a reasonable estimate of mean PFOS concentrations in free-ranging fish or crustaceans, but slightly larger sample sizes (30–50 individuals) may be required if sample medians are to be used in dietary exposure assessments. PFHxS concentrations were highly variable, so larger sample sizes should also be considered if this contaminant is of interest. The results are discussed in light of the levels of sampling effort reported in recent manuscripts, and other important considerations for designing sampling programs.

T134. The Neurocircuitry of Approach-Avoidance Decisions in Depression: Towards a Cross Species Model

T134. The Neurocircuitry of Approach-Avoidance Decisions in Depression: Towards a Cross Species Model

Development and Translational Application of an Integrated, Mechanistic Model of Antibody-Drug Conjugate Pharmacokinetics.

Antibody drug conjugates (ADC), in which small molecule cytotoxic agents are non-specifically linked to antibodies, can enable targeted delivery of chemotherapeutics to tumor cells. ADCs are often produced and administered as a mixture of conjugated antibodies with different drug to antibody ratios (DAR) resulting in complex and heterogeneous disposition kinetics. We developed a mechanism-based platform model that can describe and predict the complex pharmacokinetic (PK) behavior of ADCs with protease-cleavable valine-citrulline (VC) linker linked to Monomethylmonomethyl auristatin F/E by incorporating known mechanisms of ADC disposition. The model includes explicit representation of all DAR species; DAR-dependent sequential deconjugation of the drug, resulting in the conversion of higher DAR to lower DAR species; and DAR-dependent antibody/ADC clearance. PK profiles of multiple analytes (total antibody, drug-conjugated antibody, and/or antibody-conjugated drug) for different ADC molecules and targets in rodents and cynomolgus monkeys were used for model development. The integrated cross-species model was successful in capturing the multi-analyte PK profiles after administration of purified ADCs with defined DAR species and ADCs with mixtures of DAR. Human PK predictions for DSTP3086S (anti-STEAP1-vc-MMAE) with the platform model agreed well with PK (total antibody and antibody-conjugated drug concentrations) measurements in the dose-ranging phase I clinical study. The integrated model is applicable to various other ADCs with different formats, conjugated drugs, and linkers, and provides a valuable tool for the exploration of mechanisms governing disposition of ADCs and enables translational predictions.

A Cross-species Model for Radiation Myelopathy

A Cross-species Model for Radiation Myelopathy

Mycobacterium tuberculosis and Clostridium difficille interactomes: demonstration of rapid development of computational system for bacterial interactome prediction

BackgroundProtein-protein interaction (PPI) networks (interactomes) of most organisms, except for some model organisms, are largely unknown. Experimental methods including high-throughput techniques are highly resource intensive. Therefore, computational discovery of PPIs can accelerate biological discovery by presenting "most-promising" pairs of proteins that are likely to interact. For many bacteria, genome sequence, and thereby genomic context of proteomes, is readily available; additionally, for some of these proteomes, localization and functional annotations are also available, but interactomes are not available. We present here a method for rapid development of computational system to predict interactome of bacterial proteomes. While other studies have presented methods to transfer interologs across species, here, we propose transfer of computational models to benefit from cross-species annotations, thereby predicting many more novel interactions even in the absence of interologs. Mycobacterium tuberculosis (Mtb) and Clostridium difficile (CD) have been used to demonstrate the work.ResultsWe developed a random forest classifier over features derived from Gene Ontology annotations and genetic context scores provided by STRING database for predicting Mtb and CD interactions independently. The Mtb classifier gave a precision of 94% and a recall of 23% on a held out test set. The Mtb model was then run on all the 8 million protein pairs of the Mtb proteome, resulting in 708 new interactions (at 94% expected precision) or 1,595 new interactions at 80% expected precision. The CD classifier gave a precision of 90% and a recall of 16% on a held out test set. The CD model was run on all the 8 million protein pairs of the CD proteome, resulting in 143 new interactions (at 90% expected precision) or 580 new interactions (at 80% expected precision). We also compared the overlap of predictions of our method with STRING database interactions for CD and Mtb and also with interactions identified recently by a bacterial 2-hybrid system for Mtb. To demonstrate the utility of transfer of computational models, we made use of the developed Mtb model and used it to predict CD protein-pairs. The cross species model thus developed yielded a precision of 88% at a recall of 8%. To demonstrate transfer of features from other organisms in the absence of feature-based and interaction-based information, we transferred missing feature values from Mtb orthologs into the CD data. In transferring this data from orthologs (not interologs), we showed that a large number of interactions can be predicted.ConclusionsRapid discovery of (partial) bacterial interactome can be made by using existing set of GO and STRING features associated with the organisms. We can make use of cross-species interactome development, when there are not even sufficient known interactions to develop a computational prediction system. Computational model of well-studied organism(s) can be employed to make the initial interactome prediction for the target organism. We have also demonstrated successfully, that annotations can be transferred from orthologs in well-studied organisms enabling accurate predictions for organisms with no annotations. These approaches can serve as building blocks to address the challenges associated with feature coverage, missing interactions towards rapid interactome discovery for bacterial organisms.AvailabilityThe predictions for all Mtb and CD proteins are made available at: http://severus.dbmi.pitt.edu/TB and http://severus.dbmi.pitt.edu/CD respectively for browsing as well as for download.

Analysing lodging of the panicle bearing cereal teff (Eragrostis tef)

Lodging, the permanent displacement of crop plants from their vertical because of root or shoot failure, is a major yield constraint of the gluten free, panicle bearing cereal teff. The objective of this paper was to analyse the causes of lodging of teff by using, modifying and validating conventional biomechanical models. The model parameters were obtained from a field trial with two contrasting teff cultivars, using novel in situ and laboratory measurements under wet and dry conditions. Cross-species model validation was done with rice (Oryza sativa). Teff is more susceptible to root lodging than to shoot lodging, although the data indicated that shoot strength is also insufficient. Hence, simultaneously breeding for both improved root anchorage and shoot strength is advocated. The study showed that the lodging model, derived for the spike-bearing cereal wheat, needed modifications in order to be able to deal with panicle-bearing plants such as teff and rice. Water adhering to plants owing to rain or dew increased calculated lodging susceptibility. To prevent underestimation of lodging susceptibility, future lodging research should be done under completely wet conditions (water saturated soil and wetted shoots).

Continued evaluation of a new semen collection technique/container in subfertile and infertile individuals using a cross-species model

To date, the common thread in the use of semen collection/extension techniques, whether being used for intrauterine insemination, cryopreserved semen, or advanced reproductive techniques such as in vitro fertilization, is that the samples are collected into a dry, unprotected specimen container. This container, by its nature, allows for drastic shifts in temperature and pH resulting in damage to the spermatozoa. Preliminary studies from this laboratory using a new collection container/technique to collect semen from canines and humans demonstrated an improvement in most semen parameters. The modified collection device optimizes semen parameters by controlling temperature, pH, and osmotic stress. The objective of the current study was to further investigate the usefulness of the modified device in improving semen parameters using a cross-species model focusing on sub- and infertile individuals. A cross-species evaluation of a new semen collection technology. Semen samples were collected from canine (n=10), equine (n=8) and human (n=12) donors using standard techniques. In the case of the equine and canine donors, a splitter was placed in the artificial vagina to produce a true split sample into a standard collection vessel and the modified collection unit. Human donors were collected into both devices in sequential samples at three day intervals. Standard semen parameters (viability, motility, morphology, concentration) and biochemical markers were evaluated for all donors at 0, 1, 3, 6, 12, 18, and 24 hr post-processing. Canine and Equine samples were further evaluated at 24 hr intervals until the samples had reached 0% motility. All donors were then classified as either fertile or sub-fertile based upon species standard for count and/or motility. Data analysis within species were performed with SPSS using the general linear model and appropriate t-tests. As in previous studies, semen quality at 24 hr (as reflected by motility) was significantly higher in samples collected in the new collection container as compared to the control regardless of species (human 20% vs 14%, P < .001; canine 38% vs 8%, P < .001; equine 55% vs 37%, P< .001; treatment vs control respectively). Further, collection of the samples into the new device extended the time to last full insemination dose (dose is species specific) an average of 7 fold (7 hrs vs 50 hrs) P<.03 in the canine and 2 fold (148 hrs vs 228 hrs) P<.001in the equine over their respective control. This improvement was even more dramatic in animals classified as sub-fertile, where collection into the new device extended the time to last full insemination dose an average of 15 fold (6 hrs vs 91 hrs) in the canine and 3.5 fold (120 hrs vs 312 hrs) in the equine over their respective controls. Improvement was also seen in viability and biochemical parameters which will be discussed in detail at presentation. Modification of the semen collection/extension procedure resulted in improved semen parameters for extended time-periods post-collection. The data suggests the described technique can yield significantly more motile sperm by placing the sample into a physiologically favorable environment (eliminating pH and cold shock), thus making more sperm available for use in a variety of infertility treatments. Further studies, evaluating pregnancy rates, will be needed to confirm these observations.

Neural circuit regulation of prepulse inhibition of startle in the rat: current knowledge and future challenges.

Sensorimotor gating of the startle reflex can be assessed across species, using similar stimuli to elicit similar responses. Prepulse inhibition (PPI), a measure of sensorimotor gating, is reduced in patients with some neuropsychiatric disorders, and in rats after manipulations of limbic cortex, striatum, pallidum or pontine tegmentum ("CSPP" circuitry). To review the current knowledge of the neural circuit regulation of PPI in rats, and to anticipate the future challenges facing this line of inquiry. The published literature was reviewed and critically evaluated. Limbic CSPP circuitry has been studied in rats to reveal the neurochemical and neuroanatomical substrates regulating PPI at a high level of resolution. In translational cross-species research, this detailed circuit information is used as a "blueprint" to identify substrates that may lead to PPI deficits in psychiatrically disordered humans. Some human disorders with identifiable, localized lesions in CSPP circuitry may provide direct validation for the contribution of CSPP circuitry to this cross-species model. The rapid collection of experimental data supporting this cross-species PPI circuit "blueprint" has supported continuing advances in the development of theoretical models for understanding how this circuitry normally functions to regulate PPI. Such models are needed for building a conceptual framework for understanding the role of this circuitry in the regulation of sensorimotor gating in normal humans, and in the relative loss of sensorimotor gating, and the resulting clinical consequences, in individuals with particular neuropsychiatric disorders. Our understanding of the neural regulation of PPI has increased tremendously over the past 15 years. Progress has come in "broad strokes", and a number of important details and complex questions remain to be addressed. It is anticipated that this is a "work in progress", and that the precise models for the neural regulation of PPI will evolve substantially in the coming years.

Cross-species studies of sensorimotor gating of the startle reflex.

Sensorimotor gating of the startle reflex can be assessed across species, using similar stimuli to elicit comparable response characteristics. As measured by prepulse inhibition (PPI), gating is reduced in patients with some neuropsychiatric disorders, and in rats after manipulations of limbic cortex, striatum, pallidum, or pontine tegmentum. This limbic "CSPP" circuitry can be studied in rats to reveal the neurochemical and neuroanatomical substrates regulating PPI at a high level of resolution. This detailed circuit information is used as a "blueprint" to identify substrates that may lead to PPI deficits in psychiatric-disordered humans. Some human disorders with identifiable, localized lesions in CSPP circuitry, for example, Huntington's disease, provide direct validation for this cross-species model. Studies have begun to assess the pharmacological homology of PPI across species, as an initial step towards translating detailed neural circuit information from rats to humans. These initial studies suggest the possibility that the effects of dopaminergic (DAergic) drugs on PPI (reducing PPI) may be homologous across species; nicotinic drugs may also produce similar effects on PPI across species (increasing PPI). By contrast, the effects of glutamatergic and serotonergic drugs may exhibit disparate effects on PPI across species. The use of DAergic agonists in human studies is complicated by their significant side effects, but new studies demonstrate that several "human friendly" direct DA agonists disrupt PPI in rats and are thus good candidates for further studies of the cross-species homology of the DAergic regulation of PPI. In this manner, PPI can be used to probe the sensitivity of DAergic systems, and perhaps other CSPP elements, across normal and neuropsychiatric-disordered populations.