Exploratory Dual PET imaging of [18F] fluorodeoxyglucose and [11C]acetoacetate in type 2 diabetic nonhuman primates.

Despite recent advancements in imaging (amyloid-PET & tau-PET) and fluid (Aß42/Aß40 & Aß42/ptau) biomarkers, the current standard for in vivo assessment of AD, diagnosis and prediction of Alzheimer's disease (AD) remains challenging. We demonstrated in nonhuman primates (NHP) that increased plasma and cerebrospinal fluid (CSF) glucose correlated with decreased CSF Aß42 and CSF Aß40, a hallmark of plaque promoting pathogenesis. Together, our findings demonstrate that altered glucose homeostasis and insulin resistance are associated with Aß and amyloid in rodent and NHP models. This warranted further exploration into the dynamics of altered brain metabolism in the NHP model of T2D, cross referenced with CSF and blood-based AD markers. Preliminary dual PET ([11C]acetoacetate ([11C]AcAc) and [18F]fluorodeoxyglucose ([18F]FDG) imaging studies were conducted in an aged cohort of NHPs classified as T2D (n = 5) and pre-diabetic (n = 1) along with corresponding plasma and CSF samples for metabolite analysis. [11C]AcAc and [18F]FDG PET brain standard uptake values (SUV) were highly positively associated (r = 0.88, p = 0.02) in the T2D and pre-diabetic NHPs. Age was not significantly associated with brain SUV (age range 16.5-23.5 years old). Metabolic measures were positively correlated with brain [18F]FDG and CSF Aß42:40 was positively correlated to fasting glucose values. Although our findings suggest moderate correlations, this study further elucidates that peripheral insulin resistance and poor glycemia control alter AD-related pathology, illustrating how T2D is a risk factor for AD.

Long-term dasatinib plus quercetin effects on aging outcomes and inflammation in nonhuman primates: implications for senolytic clinical trial design.

Cellular senescence increases with aging and results in secretion of pro-inflammatory factors that induce local and systemic tissue dysfunction. We conducted the first preclinical trial in a relevant middle-aged nonhuman primate (NHP) model to allow estimation of the main translatable effects of the senolytic combination dasatinib (D) and quercetin (Q), with and without caloric restriction (CR). A multi-systemic survey of age-related changes, including those on immune cells, adipose tissue, the microbiome, and biomarkers of systemic organ and metabolic health are reported. Age-, weight-, sex-, and glycemic control-matched NHPs (D + Q, n = 9; vehicle [VEH] n = 7) received two consecutive days of D + Q (5 mg/kg + 50 mg/kg) monthly for 6 months, where in month six, a 10% CR was implemented in both D + Q and VEH NHPs to induce equal weight reductions. D + Q reduced senescence marker gene expressions in adipose tissue and circulating PAI-1 and MMP-9. Improvements were observed in immune cell types with significant anti-inflammatory shifts and reductions in microbial translocation biomarkers, despite stable microbiomes. Blood urea nitrogen showed robust improvements with D + Q. CR resulted in significant positive body composition changes in both groups with further improvement in immune cell profiles and decreased GDF15 (p = 0.05), and the interaction of D + Q and CR dramatically reduced glycosylated hemoglobin A1c (p = 0.03). This work indicates that 6 months of intermittent D + Q exposure is safe and may combat inflammaging via immune benefits and improved intestinal barrier function. We also saw renal benefits, and with CR, improved metabolic health. These data are intended to provide direction for the design of larger controlled intervention trials in older patients.

Brief Communication: Histological Assessment of Nonhuman Primate Brown Adipose Tissue Highlights the Importance of Sympathetic Innervation.

Objective: The objective of this study was to functionally analyze the correlation of key histological features in brown adipose tissue (BAT) with clinical metabolic traits in nonhuman primates. Methods: Axillary adipose tissue biopsies were collected from a metabolically diverse nonhuman primate cohort with clinical metabolism-related data. Expression of tyrosine hydroxylase (TH), uncoupling protein 1 (UCP1), cluster of differentiation 31 (CD31), cytochrome c oxidase subunit 4 (COX IV), beta-3 adrenergic receptor (ß3-AR), and adipose cell size were quantified by immunohistochemical analysis. Computed tomography scans were performed to assess body composition. Results: Tyrosine hydroxylase was negatively correlated with whole body fat mass as a percentage of body weight (p = 0.004) and was positively correlated with the density of UCP1 (p = 0.02), COX IV (p = 0.006), CD31 (p = 0.007), and cell density (p = 0.02) of the BAT samples. Beta-3 adrenergic receptor abundance had a weak positive correlation with COX IV (p = 0.04) in BAT but did not significantly correlate to UCP1 or TH expression in BAT. Conclusions: Our findings highlight that there is a disparity in innervation provided to BAT based on body composition, as seen with the negative association between TH, a marker for innervation, and adiposity. These findings also support the importance of innervation in the functionality of BAT, as TH abundance not only supports leaner body composition but is also positively correlated with known structural elements in BAT (UCP1, COX IV, CD31, and cell density). Based on our observations, ß3-AR abundance does not strongly drive these structural elements or TH, all of which are known to be important in the function of brown adipose tissue. In effect, while the role of other receptors, such as ß2-AR, should be reviewed in BAT function, these results support the development of safe sympathetic nervous system stimulants to activate brown adipose tissue for obesity treatment.