2056-P: In Vivo Human Islet Compensation and Dysfunction to Diet-Induced Obesity: A Phase 0 Preclinical Model

Recently, novel inbred mouse strains that are genetically distinct from the commonly used models have been developed from wild-caught mice. These wild-derived inbred strains have been included in many of the large-scale genomic projects, but their potential as models of altered obesity and diabetes susceptibility has not been assessed. We examined obesity and diabetes-related traits in response to high-fat feeding in two of these strains, PWD/PhJ (PWD) and WSB/EiJ (WSB), in comparison with C57BL/6J (B6). Young PWD mice displayed high fasting insulin levels, although they had normal insulin sensitivity. PWD mice subsequently developed a much milder and delayed-onset obesity compared with B6 mice but became as insulin resistant. PWD mice had a robust first-phase and increased second-phase glucose-stimulated insulin secretion in vivo, rendering them more glucose tolerant. WSB mice were remarkably resistant to diet-induced obesity and maintained very low fasting insulin throughout the study. WSB mice exhibited more rapid glucose clearance in response to an insulin challenge compared with B6 mice, consistent with their low percent body fat. Interestingly, in the absence of a measurable in vivo insulin secretion, glucose tolerance of WSB mice was better than B6 mice, likely due to their enhanced insulin sensitivity. Thus PWD and WSB are two obesity-resistant strains with unique insulin secretion phenotypes. PWD mice are an interesting model that dissociates hyperinsulinemia from obesity and insulin resistance, whereas WSB mice are a model of extraordinary resistance to a high-fat diet.

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TMOD-31. AN ORGANOTYPIC TISSUE PLATFORM TO BRIDGE IN VITRO AND IN VIVO ASSAYS FOR BRAIN CANCER TREATMENT

Neuro-Oncology ◽

10.1093/neuonc/noab196.892 ◽

2021 ◽

Vol 23 (Supplement_6) ◽

pp. vi222-vi222

Author(s):

Breanna Mann ◽

Noah Bell ◽

Denise Dunn ◽

Scott Floyd ◽

Shawn Hingtgen ◽

...

Keyword(s):

Cell Lines ◽

Brain Cancer ◽

Brain Slice ◽

Brain Slices ◽

In Vitro Assays ◽

Preclinical Model ◽

Short Period ◽

The Brain

Abstract Brain cancers remain one of the greatest medical challenges. The lack of experimentally tractable models that recapitulate brain structure/function represents a major impediment. Platforms that enable functional testing in high-fidelity models are urgently needed to accelerate the identification and translation of therapies to improve outcomes for patients suffering from brain cancer. In vitro assays are often too simple and artificial while in vivo studies can be time-intensive and complicated. Our live, organotypic brain slice platform can be used to seed and grow brain cancer cell lines, allowing us to bridge the existing gap in models. These tumors can rapidly establish within the brain slice microenvironment, and morphologic features of the tumor can be seen within a short period of time. The growth, migration, and treatment dynamics of tumors seen on the slices recapitulate what is observed in vivo yet is missed by in vitro models. Additionally, the brain slice platform allows for the dual seeding of different cell lines to simulate characteristics of heterogeneous tumors. Furthermore, live brain slices with embedded tumor can be generated from tumor-bearing mice. This method allows us to quantify tumor burden more effectively and allows for treatment and retreatment of the slices to understand treatment response and resistance that may occur in vivo. This brain slice platform lays the groundwork for a new clinically relevant preclinical model which provides physiologically relevant answers in a short amount of time leading to an acceleration of therapeutic translation.

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Tumor spheroids and organoids as preclinical model systems

Medizinische Genetik ◽

10.1515/medgen-2021-2093 ◽

2021 ◽

Vol 33 (3) ◽

pp. 229-234

Author(s):

Aria Baniahmad

Keyword(s):

Apoptotic Cell ◽

Model Systems ◽

Adherent Cell ◽

Preclinical Model ◽

Cancer Tissue ◽

Tumor Spheroids ◽

Cancer Models ◽

Cancer Multiple ◽

Cell Cell

Abstract The generation of three-dimensional (3D) cancer models is a novel and fascinating development in the study of personalized medicine and tumor-specific drug delivery. In addition to the classical two-dimensional (2D) adherent cell culture models, 3D spheroid and organoid cancer models that mimic the microenvironment of cancer tissue are emerging as an important preclinical model system. 3D cancer models form, similar to cancer, multiple cell–cell and cell–extracellular matrix interactions and activate different cellular cascades/pathways, like proliferation, quiescence, senescence, and necrotic or apoptotic cell death. Further, it is possible to analyze genetic variations and mutations, the microenvironment of cell–cell interactions, and the uptake of therapeutics and nanoparticles in nanomedicine. Important is also the analysis of cancer stem cells (CSCs), which could play key roles in resistance to therapy and cancer recurrence. Tumor spheroids can be generated from one tumor-derived cell line or from co-culture of two or more cell lines. Tumor organoids can be derived from tumors or may be generated from CSCs that differentiate into multiple facets of cancerous tissue. Similarly, tumorspheres can be generated from a single CSC. By transplanting spheroids and organoids into immune-deficient mice, patient-derived xenografts can serve as a preclinical model to test therapeutics in vivo. Although the handling and analysis of 3D tumor spheroids and organoids is more complex, it will provide insights into various cancer processes that cannot be provided by 2D culture. Here a short overview of 3D tumor systems as preclinical models is provided.

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Human Islet Amyloid Polypeptide Fibril Binding to Catalase: A Transmission Electron Microscopy and Microplate Study

The Scientific World JOURNAL ◽

10.1100/tsw.2010.73 ◽

2010 ◽

Vol 10 ◽

pp. 879-893 ◽

Cited By ~ 10

Author(s):

Nathaniel G. N. Milton ◽

J. Robin Harris

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Islet Amyloid Polypeptide ◽

Amyloid Β ◽

Human Islet ◽

Islet Amyloid ◽

Human Islet Amyloid Polypeptide ◽

Transmission Electron

The diabetes-associated human islet amyloid polypeptide (IAPP) is a 37-amino-acid peptide that forms fibrilsin vitroandin vivo. Human IAPP fibrils are toxic in a similar manner to Alzheimer's amyloid-β (Aβ) and prion protein (PrP) fibrils. Previous studies have shown that catalase binds to Aβ fibrils and appears to recognize a region containing the Gly-Ala-Ile-Ile sequence that is similar to the Gly-Ala-Ile-Leu sequence found in human IAPP residues 24-27. This study presents a transmission electron microscopy (TEM)—based analysis of fibril formation and the binding of human erythrocyte catalase to IAPP fibrils. The results show that human IAPP 1-37, 8-37, and 20-29 peptides form fibrils with diverse and polymorphic structures. All three forms of IAPP bound catalase, and complexes of IAPP 1-37 or 8-37 with catalase were identified by immunoassay. The binding of biotinylated IAPP to catalase was high affinity with a KDof 0.77nM, and could be inhibited by either human or rat IAPP 1-37 and 8-37 forms. Fibrils formed by the PrP 118-135 peptide with a Gly-Ala-Val-Val sequence also bound catalase. These results suggest that catalase recognizes a Gly-Ala-Ile-Leu—like sequence in amyloid fibril-forming peptides. For IAPP 1-37 and 8-37, the catalase binding was primarily directed towards fibrillar rather than ribbon-like structures, suggesting differences in the accessibility of the human IAPP 24-27 Gly-Ala-Ile-Leu region. This suggests that catalase may be able to discriminate between different structural forms of IAPP fibrils. The ability of catalase to bind IAPP, Aβ, and PrP fibrils demonstrates the presence of similar accessible structural motifs that may be targets for antiamyloid therapeutic development.

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Diet, Obesity, and Cancer Progression: Are Adipocytes the Link?

Lipid Insights ◽

10.4137/lpi.s10871 ◽

2013 ◽

Vol 6 ◽

pp. LPI.S10871 ◽

Cited By ~ 11

Author(s):

Paul Toren ◽

Benjamin C. Mora ◽

Vasundara Venkateswaran

Keyword(s):

Tumor Microenvironment ◽

Cancer Progression ◽

Tumor Biology ◽

Model Systems ◽

In Vivo Model ◽

Diet Induced Obesity ◽

Breast And Prostate Cancer ◽

Obesity And Cancer

Obesity has been linked to more aggressive characteristics of several cancers, including breast and prostate cancer. Adipose tissue appears to contribute to paracrine interactions in the tumor microenvironment. In particular, cancer-associated adipocytes interact reciprocally with cancer cells and influence cancer progression. Adipokines secreted from adipocytes likely form a key component of the paracrine signaling in the tumor microenvironment. In vitro coculture models allow for the assessment of specific adipokines in this interaction. Furthermore, micronutrients and macronutrients present in the diet may alter the secretion of adipokines from adipocytes. The effect of dietary fat and specific fatty acids on cancer progression in several in vivo model systems and cancer types is reviewed. The more common approaches of caloric restriction or diet-induced obesity in animal models establish that such dietary changes modulate tumor biology. This review seeks to explore available evidence regarding how diet may modulate tumor characteristics through changes in the role of adipocytes in the tumor microenvironment.

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Prediction of Minocycline Activity in the Gut From a Pig Preclinical Model Using a Pharmacokinetic -Pharmacodynamic Approach

Frontiers in Microbiology ◽

10.3389/fmicb.2021.671376 ◽

2021 ◽

Vol 12 ◽

Author(s):

Quentin Vallé ◽

Béatrice B. Roques ◽

Alain Bousquet-Mélou ◽

David Dahlhaus ◽

Felipe Ramon-Portugal ◽

...

Keyword(s):

Intestinal Content ◽

Multidrug Resistant ◽

Preclinical Model ◽

Intestinal Contents ◽

Potential Activity ◽

Potential Impact ◽

The Impact ◽

Pharmacodynamic Approach

The increase of multidrug-resistant (MDR) bacteria has renewed interest in old antibiotics, such as minocycline, that can be active against various MDR Gram-negative pathogens. The elimination of minocycline by both kidneys and liver makes it suitable for impaired renal function patients. However, the drawback is the possible elimination of a high amount of drug in the intestines, with potential impact on the digestive microbiota during treatment. This study aimed to predict the potential activity of minocycline against Enterobacterales in the gut after parenteral administration, by combining in vivo and in vitro studies. Total minocycline concentrations were determined by UPLC-UV in the plasma and intestinal content of piglets following intravenous administration. In parallel, the in vitro activity of minocycline was assessed against two Escherichia coli strains in sterilized intestinal contents, and compared to activity in a standard broth. We found that minocycline concentrations were 6–39 times higher in intestinal contents than plasma. Furthermore, minocycline was 5- to 245-fold less active in large intestine content than in a standard broth. Using this PK-PD approach, we propose a preclinical pig model describing the link between systemic and gut exposure to minocycline, and exploring its activity against intestinal Enterobacterales by taking into account the impact of intestinal contents.

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Pharmacological Inhibition of NOX4 Improves Mitochondrial Function and Survival in Human Beta-Cells

Biomedicines ◽

10.3390/biomedicines9121865 ◽

2021 ◽

Vol 9 (12) ◽

pp. 1865

Author(s):

Andris Elksnis ◽

Jing Cen ◽

Per Wikström ◽

Per-Ola Carlsson ◽

Nils Welsh

Keyword(s):

Cell Death ◽

Beta Cell ◽

Insulin Release ◽

Mitochondrial Function ◽

High Glucose ◽

Human Islet ◽

Sodium Palmitate ◽

Nadph Oxidase 4

Previous studies have reported beneficial effects of NADPH oxidase 4 (NOX4) inhibition on beta-cell survival in vitro and in vivo. The mechanisms by which NOX4 inhibition protects insulin producing cells are, however, not known. The aim of the present study was to investigate the effects of a pharmacological NOX4 inhibitor (GLX7013114) on human islet and EndoC-βH1 cell mitochondrial function, and to correlate such effects with survival in islets of different size, activity, and glucose-stimulated insulin release responsiveness. We found that maximal oxygen consumption rates, but not the rates of acidification and proton leak, were increased in islets after acute NOX4 inhibition. In EndoC-βH1 cells, NOX4 inhibition increased the mitochondrial membrane potential, as estimated by JC-1 fluorescence; mitochondrial reactive oxygen species (ROS) production, as estimated by MitoSOX fluorescence; and the ATP/ADP ratio, as assessed by a bioluminescent assay. Moreover, the insulin release from EndoC-βH1 cells at a high glucose concentration increased with NOX4 inhibition. These findings were paralleled by NOX4 inhibition-induced protection against human islet cell death when challenged with high glucose and sodium palmitate. The NOX4 inhibitor protected equally well islets of different size, activity, and glucose responsiveness. We conclude that pharmacological alleviation of NOX4-induced inhibition of beta-cell mitochondria leads to increased, and not decreased, mitochondrial ROS, and this was associated with protection against cell death occurring in different types of heterogeneous islets. Thus, NOX4 inhibition or modulation may be a therapeutic strategy in type 2 diabetes that targets all types of islets.

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Increased Energy Expenditure and Protection from Diet-Induced Obesity in Mice Lacking the cGMP-Specific Phosphodiesterase PDE9

10.2337/figshare.16701997 ◽

2021 ◽

Author(s):

Ryan P. Ceddia ◽

Dianxin Liu ◽

Fubiao Shi ◽

Mark K. Crowder ◽

Sumita Mishra ◽

...

Keyword(s):

Energy Expenditure ◽

Second Messengers ◽

Diet Induced Obesity ◽

Brown Adipose ◽

Elevated Expression ◽

Obesity In Mice ◽

Ucp1 Expression ◽

Global Increase ◽

Fat Diets

Cyclic nucleotides, cAMP and cGMP, are important second messengers for the regulation of adaptive thermogenesis. Their levels are controlled not only by their synthesis but also their degradation. Since pharmacological inhibitors of cGMP-specific phosphodiesterase 9 (PDE9) can increase PKG signaling and UCP1 expression in adipocytes, we sought to elucidate the role of PDE9 on energy balance and glucose homeostasis in vivo. Mice with targeted disruption of the PDE9 gene, Pde9a, were fed nutrient matched high-fat (HFD) or low-fat diets (LFD). Pde9a‑/‑ mice were resistant to HFD induced obesity, exhibiting a global increase in energy expenditure, while brown adipose tissue (AT) had increased respiratory capacity and elevated expression of Ucp1 and other thermogenic genes. Reduced adiposity of HFD-fed Pde9a‑/‑ mice was associated with improvements in glucose handling and hepatic steatosis. Cold exposure or treatment with β-adrenergic receptor agonists markedly decreased Pde9a expression in brown AT and cultured brown adipocytes, while Pde9a‑/‑ mice exhibited a greater increase in AT browning; together suggesting that the PDE9-cGMP pathway augments classical cold-induced β-adrenergic/cAMP AT browning and energy expenditure. These findings suggest PDE9 is a previously unrecognized regulator of energy metabolism and that its inhibition may be a valuable avenue to explore for combating metabolic disease.

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Exposure to the Widely Used Pyrethroid Pesticide Deltamethrin, Does Not Exacerbate High Fat Diet Induced Obesity or Insulin Resistance in C57BL/6J Mice

Journal of the Endocrine Society ◽

10.1210/jendso/bvab048.090 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. A45-A46

Author(s):

Evangelia Evelyn Tsakiridis ◽

Marisa Morrow ◽

Andrea Llanos ◽

Bo Wang ◽

Alison Holloway ◽

...

Keyword(s):

Insulin Resistance ◽

Glycemic Control ◽

Metabolic Diseases ◽

Uncoupling Protein ◽

Diet Induced Obesity ◽

Brown Adipose ◽

Pyrethroid Pesticide ◽

First Time

Abstract Deltamethrin is a commonly used pesticide for the control of mosquito populations. Despite widespread use, the effects of deltamethrin on adiposity and glucose homeostasis have been equivocal with some studies showing increased, decreased and no effect on adiposity and glycemic control. However, no study to date has investigated the effect of deltamethrin in mice housed at thermoneutral temperatures, which is important for modelling metabolic diseases in rodents due to reduced thermal stress and constitutive activation of brown adipose tissue. In the current study we demonstrate for the first time that deltamethrin reduces uncoupling protein-1 expression in brown adipocytes cultured in vitro at concentrations as low as 1pm. Meanwhile, in-vivo deltamethrin does not appear to alter glycemic control or promote adiposity at exposures equivalent to 0.01, 0.1 or 1.0 mg/kg/day. Together, our study demonstrates environmentally relevant exposure to deltamethrin does not exacerbate diet induced obesity or insulin resistance.

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