Progressive nature of obesity and diabetes in nonhuman primates

Diet-induced shifts in the gut microbiota influence anastomotic healing in a murine model of colonic surgery

Host diet and gut microbiota interact to contribute to perioperative complications, including anastomotic leak (AL). Using a murine surgical model of colonic anastomosis, we investigated how diet and fecal microbial transplantation (FMT) impacted the intestinal microbiota and if a predictive signature for AL could be determined. We hypothesized that a Western diet (WD) would impact gut microbial composition and that the resulting dysbiosis would correlate with increased rates of AL, while FMT from healthy, lean diet (LD) donors would reduce the risk of AL. Furthermore, we predicted that surgical outcomes would allow for the development of a microbial preclinical translational tool to identify AL. Here, we show that AL is associated with a dysbiotic microbial community characterized by increased levels of Bacteroides and Akkermansia. We identified several key taxa that were associated with leak formation, and developed an index based on the ratio of bacteria associated with the absence and presence of leak. We also highlight a modifiable connection between diet, microbiota, and anastomotic healing, potentially paving the way for perioperative modulation by microbiota-targeted therapeutics to reduce AL.

A human antibody against pathologic IAPP aggregates protects beta cells in type 2 diabetes models

In patients with type 2 diabetes, pancreatic beta cells progressively degenerate and gradually lose their ability to produce insulin and regulate blood glucose. Beta cell dysfunction and loss is associated with an accumulation of aggregated forms of islet amyloid polypeptide (IAPP) consisting of soluble prefibrillar IAPP oligomers as well as insoluble IAPP fibrils in pancreatic islets. Here, we describe a human monoclonal antibody selectively targeting IAPP oligomers and neutralizing IAPP aggregate toxicity by preventing membrane disruption and apoptosis in vitro. Antibody treatment in male rats and mice transgenic for human IAPP, and human islet-engrafted mouse models of type 2 diabetes triggers clearance of IAPP oligomers resulting in beta cell protection and improved glucose control. These results provide new evidence for the pathological role of IAPP oligomers and suggest that antibody-mediated removal of IAPP oligomers could be a pharmaceutical strategy to support beta cell function in type 2 diabetes.

Low serum creatinine, a surrogate marker of muscle mass, correlates with insulin sensitivity in nonhuman primates

OBJECTIVES

Decreased serum creatinine levels are associated with increased risk of type 2 diabetes (T2DM) in humans, however, its association with muscle mass and insulin sensitivity have not been studied in NHPs.

METHODS

Retrospective data of 229 adult NHPs were studied for association of serum creatinine levels with muscle mass and onset of T2DM.

RESULTS

Serum creatinine levels were positively correlated with lean muscle mass in nondiabetic (non-DM), male and female NHPs. Aged NHPs had significantly reduced lean muscle mass and corresponding creatinine levels compared to young age groups (p < .001). Creatinine was positively correlated with insulin sensitivity in nonDM male NHPs and significant decrease in creatinine was observed in T2DM (p < .001) compared to same age group nonDM NHPs.

CONCLUSIONS

The pathophysiology of T2DM in NHPs is similar to humans, low creatinine further provides utility of surrogate biomarkers of lower muscle mass and risk factor for T2DM NHPs.

Commentary on Metabolic Health Disparities Affecting the Rio Grande Valley Mexican American Population: Seeking Answers Using Animal Models

Mexican Americans living in the Rio Grande Valley (RGV) have a high prevalence of type 2 diabetes (T2D). The US-Mexico border frontier has a unique blended culture of American lifestyle and Mexican traditions. Some examples of the cultural traditions are the food and the use of herbal medicine, but these traditions are in danger of disappearing after a very short number of generations living in the United States. This article describes the use of animal models under experimental conditions to solve practical questions (etiology or treatment). We performed studies with murine (ie, mouse and rat) models to elucidate the characteristics of medicinal plants that modulate glucose metabolism and inflammation and protect from bone loss, complications related to T2D. The University of Texas Rio Grande Valley researchers also have collaborated with the University of Texas Health Science Center at San Antonio researchers in performing studies in nonhuman primates (NHP) (ie, baboon) to understand the effect of T2D and diets on organs and tissues. With the new knowledge gained from the use of animal models (murine and NHP), new therapies are discovered for the prevention and treatment of T2D and its related complications, such as bone loss and nonalcoholic fatty liver disease, all of which the Mexican American and other human populations are at high risk of developing.

The Influence of Diet on Metabolism and Health Across the Lifespan in Nonhuman Primates

The macro and micronutrient composition and the overall quantity of the diet are important predictors of physical and psychological health and, as a consequence, behavior. Translational preclinical models are critical to identifying the mechanisms underlying these relationships. Nonhuman primate models are particularly instrumental to this line of research as they exhibit considerable genetic, social, and physiological similarities, as well as similarities in their developmental trajectories to humans. This review aims to discuss recent contributions to the field of diet and metabolism and health using nonhuman primate models. The influence of diet composition on health and physiology across the lifespan will be the primary focus, including recent work examining the impact of maternal diet programming of offspring physiologic and behavioral developmental outcomes.

Habitual Exposure to Trigeminal Stimuli and Its Effects on the Processing of Chemosensory Stimuli

Our objective was to compare brain responses to trigeminal and olfactory stimuli in frequent and non-frequent gum chewers in order to explore whether habitual exposure to trigeminal stimuli affects their central-nervous processing. In healthy subjects, fMRI brain scans were obtained for 20 frequent gum chewers (GC) and 20 non-frequent gum chewers (N'GC), in response to four odorous stimuli; 2 'trigeminal' (peppermint and spearmint) and 2 non-trigeminal or 'olfactory' (cherry and strawberry). During measurements, subjects reported intensity and pleasantness ratings for all stimuli. In addition, a test for general trigeminal sensitivity test (lateralization test) and an odor threshold test was performed. Brain activations in response to individual odors were investigated for the total study population followed by group wise (GC and N'GC) analysis separately for responses to trigeminal (peppermint + spearmint) and olfactory (cherry + strawberry) odors. (1) The GC group exhibited higher trigeminal sensitivity compared to the N'GC group. (2) Olfactory odors activated bilateral insular cortex and amygdala. Apart from olfactory areas (amygdala, insular cortex), trigeminal odors also produced activations in right thalamus and right substantia nigra. (3) In the GC group, olfactory odors produced higher bilateral insular cortex activation than in N'GC group, but no such differences were observed for trigeminal odors. GC subjects appeared to be more responsive to trigeminal chemosensory stimuli. However, this did not directly translate into differences in central-nervous activations to trigeminal stimuli; instead, the use of chewing gum was associated with stronger brain activation towards olfactory stimuli.

Comparison of the anatomical morphology of cervical vertebrae between humans and macaques: related to a spinal cord injury model

Non-human primates are most suitable for generating cervical experimental models, and it is necessary to study the anatomy of the cervical spine in non-human primates when generating the models. The purpose of this study was to provide the anatomical parameters of the cervical spine and spinal cord in long-tailed macaques (Macaca fascicularis) as a basis for cervical spine-related experimental studies. Cervical spine specimens from 8 male adult subjects were scanned by micro-computed tomography, and an additional 10 live male subjects were scanned by magnetic resonance imaging. The measurements and parameters from them were compared to those of 12 male adult human subjects. Additionally, 10 live male subjects were scanned by magnetic resonance imaging, and the width and depth of the spinal cord and spinal canal and the thickness of the anterior and posterior cerebrospinal fluid were measured and compared to the relevant parameters of 10 male adult human subjects. The tendency of cervical parameters to change with segmental changes was similar between species. The vertebral body, spinal canal, and spinal cord were significantly flatter in the human subjects than in the long-tailed macaques. The cerebrospinal fluid space in the long-tailed macaques was smaller than that in the human subjects. The anatomical features of the cervical vertebrae of long-tailed macaques provide a reference for establishing a preclinical model of cervical spinal cord injury.

Use and Importance of Nonhuman Primates in Metabolic Disease Research: Current State of the Field

Obesity and its multiple metabolic sequelae, including type 2 diabetes, cardiovascular disease, and fatty liver disease, are becoming increasingly widespread in both the developed and developing world. There is an urgent need to identify new approaches for the prevention and treatment of these costly and prevalent metabolic conditions. Accomplishing this will require the use of appropriate animal models for preclinical and translational investigations in metabolic disease research. Although studies in rodent models are often useful for target/pathway identification and testing hypotheses, there are important differences in metabolic physiology between rodents and primates, and experimental findings in rodent models have often failed to be successfully translated into new, clinically useful therapeutic modalities in humans. Nonhuman primates represent a valuable and physiologically relevant model that serve as a critical translational bridge between basic studies performed in rodent models and clinical studies in humans. The purpose of this review is to evaluate the evidence, including a number of specific examples, in support of the use of nonhuman primate models in metabolic disease research, as well as some of the disadvantages and limitations involved in the use of nonhuman primates. The evidence taken as a whole indicates that nonhuman primates are and will remain an indispensable resource for evaluating the efficacy and safety of novel therapeutic strategies targeting clinically important metabolic diseases, including dyslipidemia and atherosclerosis, type 2 diabetes, hepatic steatosis, steatohepatitis, and hepatic fibrosis, and potentially the cognitive decline and dementia associated with metabolic dysfunction, prior to taking these therapies into clinical trials in humans.