Green Methodologies for Copper(I)-Catalyzed Azide-Alkyne Cycloadditions: A Comparative Study.

Successful copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reactions may be achieved by several methods. In this paper, four synthetic protocols were performed for direct comparison of time required for the synthesis, yield, and purity of the 1H-1,2,3-triazole products. The methods with Cu(I) catalysts were conventional, microwave heating, solvent-free, and a method using glycerol solvent. The compounds synthesized in this paper were known non-fluorinated triazoles and new fluorinated triazoles. The results lead to the conclusion that the microwave method should be strongly considered for CuAAC syntheses.

Lipidomics of infant mesenchymal stem cells associate with the maternal milieu and child adiposity.

Our objective was to interrogate infant mesenchymal stem cell (MSC) lipid metabolism and gestational exposures that may contribute to child obesity risk. MSCs were cultured from term infants of mothers with obesity (n=16) or normal-weight (n=15). In MSCs undergoing myogenesis in vitro, we used lipidomics to distinguish phenotypes by unbiased cluster analysis and lipid challenge (24h excess fatty acid, 24hFA). We measured MSC AMP-activated protein kinase (AMPK) activity and fatty acid oxidation (FAO), and a composite index of maternal glucose, insulin, triglycerides, free fatty acids, tumor necrosis factor-α, high density lipoprotein- and total- cholesterol in fasting blood from mid- and late-gestation (~17, ~27wks). We measured child adiposity at birth (n=29), 4-6m (n=29), and 4-6y (n=13). Three MSC clusters were distinguished by triacylglycerol (TAG) stores, with greatest TAGs in Cluster-2. All Clusters increased acylcarnitines and TAGs with 24hFA, though Cluster-2 was more pronounced and corresponded to AMPK activation and FAO. Maternal metabolic markers predicted MSC Clusters and child adiposity at 4-6y (both highest in Cluster-3). Our data supports that MSC phenotypes are predicted by comprehensive maternal metabolic milieu exposures, independent of maternal BMI, and suggest utility as an at-birth predictor for child adiposity, though validation with larger longitudinal samples is warranted.

Fat content in infant mesenchymal stem cells prospectively associates with childhood adiposity and fasting glucose.

OBJECTIVE: In human studies, new model systems are needed for improved mechanistic investigation of developmental predisposition for metabolic disease but also to serve as benchmarks in early life prevention or intervention efforts. In this regard, human infant umbilical cord-derived mesenchymal stem cells (MSCs) are an emerging tool. However, long-term clinical relevance to in vivo markers of metabolic disease is unknown. METHODS: In a cohort of 124 mother/child dyads, this study tested the hypothesis that triglyceride content (TG) of infant MSCs undergoing adipogenesis in vitro (MSC-TG) is associated with in vivo adiposity (percent fat mass) from birth to early childhood and with fasting glucose and insulin in early childhood. RESULTS: MSC-TG was positively associated with in vivo child adiposity at birth, age 4 to 6 months, and age 4 to 6 years. MSC-TG was associated with fasting glucose, but not insulin, at 4 to 6 years. Importantly, MSC-TG explained an additional 13% variance in child adiposity at 4 to 6 years, after accounting for other established birth predictors (weight and percent fat mass at birth) and other established covariates related to child adiposity (e.g., breastfeeding exposure, physical activity). CONCLUSIONS: This work demonstrates the strength of the MSC model for predicting offspring metabolic phenotype into childhood, even when considering the important contribution of other early life risk factors.

Adipocyte hypertrophy in mesenchymal stem cells from infants of mothers with obesity.

OBJECTIVE: Fat content of adipocytes derived from infant umbilical cord mesenchymal stem cells (MSCs) predicts adiposity in children through 4 to 6 years of age. This study tested the hypothesis that MSCs from infants born to mothers with obesity (Ob-MSCs) exhibit adipocyte hypertrophy and perturbations in genes regulating adipogenesis compared with MSCs from infants of mothers with normal weight (NW-MSCs). METHODS: Adipogenesis was induced in MSCs embedded in three-dimensional hydrogel structures, and cell size and number were measured by three-dimensional imaging. Proliferation and protein markers of proliferation and adipogenesis in undifferentiated and adipocyte differentiating cells were measured. RNA sequencing was performed to determine pathways linked to adipogenesis phenotype. RESULTS: In undifferentiated MSCs, greater zinc finger protein (Zfp)423 protein content was observed in Ob- versus NW-MSCs. Adipocytes from Ob-MSCs were larger but fewer than adipocytes from NW-MSCs. RNA sequencing analysis showed that Zfp423 protein correlated with mRNA expression of genes enriched for cell cycle, MSC lineage specification, inflammation, and metabolism pathways. MSC proliferation was not different before differentiation but declined faster in Ob-MSCs upon adipogenic induction. CONCLUSIONS: Ob-MSCs have an intrinsic propensity for adipocyte hypertrophy and reduced hyperplasia during adipogenesis in vitro, perhaps linked to greater Zfp423 content and changes in cell cycle pathway gene expression.

Suppression of food intake by Glp1r/Lepr-coexpressing neurons prevents obesity in mouse models.

The adipose-derived hormone leptin acts via its receptor (LepRb) in the brain to control energy balance. A potentially unidentified population of GABAergic hypothalamic LepRb neurons plays key roles in the restraint of food intake and body weight by leptin. To identify markers for candidate populations of LepRb neurons in an unbiased manner, we performed single-nucleus RNA-Seq of enriched mouse hypothalamic LepRb cells, identifying several previously unrecognized populations of hypothalamic LepRb neurons. Many of these populations displayed strong conservation across species, including GABAergic Glp1r-expressing LepRb (LepRbGlp1r) neurons, which expressed more Lepr than other LepRb cell populations. Ablating Lepr from LepRbGlp1r cells provoked hyperphagic obesity without impairing energy expenditure. Similarly, improvements in energy balance caused by Lepr reactivation in GABA neurons of otherwise Lepr-null mice required Lepr expression in GABAergic Glp1r-expressing neurons. Furthermore, restoration of Glp1r expression in LepRbGlp1r neurons in otherwise Glp1r-null mice enabled food intake suppression by the GLP1R agonist, liraglutide. Thus, the conserved GABAergic LepRbGlp1r neuron population plays crucial roles in the suppression of food intake by leptin and GLP1R agonists.

Maternal metabolic health drives mesenchymal stem cell metabolism and infant fat mass at birth.

Exposure to maternal obesity may promote metabolic dysfunction in offspring. We used infant mesenchymal stem cells (MSCs) to experimentally examine cellular mechanisms of intergenerational health transmission. Our earlier reports show MSCs collected from infants of mothers with obesity had a dichotomous distribution in metabolic efficiency; they were either efficient (Ef-Ob) or inefficient (In-Ob) with respect to fatty acid oxidation (FAO). Here, we sought to determine if this was due to a primary defect in FAO. Accordingly, we measured FAO in myogenic differentiating MSCs under 3 conditions: (a) myogenesis alone, (b) excess fatty acid exposure, and (c) excess fatty acid exposure plus a chemical uncoupler to increase metabolic rate. Compared with normal weight and Ef-Ob MSCs, In-Ob displayed lower FAO in myogenesis alone and after fatty acid plus uncoupler, indicating In-Ob were less metabolically flexible after increasing lipid availability and metabolic rate, demonstrating a primary deficit in FAO. MSC FAO was negatively associated with fasting maternal glucose and insulin and positively associated with fasting HDL-cholesterol. MSC FAO was negatively associated with infant fat mass. These data indicate a less favorable maternal metabolic milieu, independent of maternal BMI, reduces intrinsic MSC FAO and is linked to higher infant adiposity as early as birth.