Glycoursodeoxycholic Acid Ameliorates Diet-induced Metabolic Disorders with Inhibiting Endoplasmic Reticulum Stress

Recent studies reveal that bile acid metabolite composition and its metabolism are changed in metabolic disorders, such as obesity, type 2 diabetes and metabolic associated fatty liver disease (MAFLD), yet its role and the mechanism remain largely unknown. In the present study, metabolomic analysis of 163 serum and stool samples of our metabolic disease cohort was performed and we identified glycoursodeoxycholic acid (GUDCA), glycine-conjugated bile acid produced from intestinal bacteria, were decreased in both serum and stool samples from patients with hyperglycemia. RNA-sequencing and quantitative PCR results indicated that GUDCA alleviated endoplasmic reticulum (ER) stress in livers of high fat diet (HFD)-fed mice without alteration of liver metabolism. In vitro, GUDCA reduced palmitic acid induced-ER stress and -apoptosis, as well as stabilized calcium homeostasis. In vivo, GUDCA exerted effects on amelioration of HFD-induced insulin resistance and hepatic steatosis. In parallel, ER stress and apoptosis were decreased in GUDCA-treated mice as compared to vehicle-treated mice in liver. These findings demonstrate that reduced GUDCA is an indicator of hyperglycemia. Supplementation of GUDCA could be an option for the treatment of diet-induced metabolic disorders, including insulin resistance and hepatic steatosis, with inhibiting ER stress.

Recovery of Depleted miR-146a in ALS Cortical Astrocytes Reverts Cell Aberrancies and Prevents Paracrine Pathogenicity on Microglia and Motor Neurons

Reactive astrocytes in Amyotrophic Lateral Sclerosis (ALS) change their molecular expression pattern and release toxic factors that contribute to neurodegeneration and microglial activation. We and others identified a dysregulated inflammatory miRNA profile in ALS patients and in mice models suggesting that they represent potential targets for therapeutic intervention. Such cellular miRNAs are known to be released into the secretome and to be carried by small extracellular vesicles (sEVs), which may be harmful to recipient cells. Thus, ALS astrocyte secretome may disrupt cell homeostasis and impact on ALS pathogenesis. Previously, we identified a specific aberrant signature in the cortical brain of symptomatic SOD1-G93A (mSOD1) mice, as well as in astrocytes isolated from the same region of 7-day-old mSOD1 mice, with upregulated S100B/HMGB1/Cx43/vimentin and downregulated GFAP. The presence of downregulated miR-146a on both cases suggests that it can be a promising target for modulation in ALS. Here, we upregulated miR-146a with pre-miR-146a, and tested glycoursodeoxycholic acid (GUDCA) and dipeptidyl vinyl sulfone (VS) for their immunoregulatory properties. VS was more effective in restoring astrocytic miR-146a, GFAP, S100B, HMGB1, Cx43, and vimentin levels than GUDCA, which only recovered Cx43 and vimentin mRNA. The miR-146a inhibitor generated typical ALS aberrancies in wild type astrocytes that were abolished by VS. Similarly, pre-miR-146a transfection into the mSOD1 astrocytes abrogated aberrant markers and intracellular Ca2+ overload. Such treatment counteracted miR-146a depletion in sEVs and led to secretome-mediated miR-146a enhancement in NSC-34-motor neurons (MNs) and N9-microglia. Secretome from mSOD1 astrocytes increased early/late apoptosis and FGFR3 mRNA in MNs and microglia, but not when derived from pre-miR-146a or VS-treated cells. These last strategies prevented the impairment of axonal transport and synaptic dynamics by the pathological secretome, while also averted microglia activation through either secretome, or their isolated sEVs. Proteomic analysis of the target cells indicated that pre-miR-146a regulates mitochondria and inflammation via paracrine signaling. We demonstrate that replenishment of miR-146a in mSOD1 cortical astrocytes with pre-miR-146a or by VS abrogates their phenotypic aberrancies and paracrine deleterious consequences to MNs and microglia. These results propose miR-146a as a new causal and emerging therapeutic target for astrocyte pathogenic processes in ALS.

Glycoursodeoxycholic Acid Ameliorates Atherosclerosis and Alters Gut Microbiota in Apolipoprotein E–Deficient Mice

Background Although glycoursodeoxycholic acid (GUDCA) has been associated with the improvement of metabolic disorders, its effect on atherosclerosis remains elusive. This study aimed to investigate the role of GUDCA in the development of atherosclerosis and its potential mechanisms. Methods and Results Human THP‐1 macrophages were used to investigate the effect of GUDCA on oxidized low‐density lipoprotein–induced foam cell formation in vitro. We found that GUDCA downregulated scavenger receptor A1 mRNA expression, reduced oxidized low‐density lipoprotein uptake, and inhibited macrophage foam cell formation. In an in vivo study, apolipoprotein E–deficient mice were fed a Western diet for 10 weeks to induce atherosclerosis, and then were gavaged once daily with or without GUDCA for 18 weeks. Parameters of systemic metabolism and atherosclerosis were detected. We found that GUDCA improved cholesterol homeostasis and protected against atherosclerosis progression as evidenced by reduced plaque area along with lipid deposition, ameliorated local chronic inflammation, and elevated plaque stability. In addition, 16S rDNA sequencing showed that GUDCA administration partially normalized the Western diet–associated gut microbiota dysbiosis. Interestingly, the changes of bacterial genera ( Alloprevotella , Parabacteroides , Turicibacter , and Alistipes ) modulated by GUDCA were correlated with the plaque area in mice aortas. Conclusions Our study for the first time indicates that GUDCA attenuates the development of atherosclerosis, probably attributable to the inhibition of foam cell formation, maintenance of cholesterol homeostasis, and modulation of gut microbiota.

Ursodeoxycholic Acid Halts Pathological Neovascularization in a Mouse Model of Oxygen-Induced Retinopathy

Retinopathy of prematurity (ROP) is the leading cause of blindness in infants. We have investigated the efficacy of the secondary bile acid ursodeoxycholic acid (UDCA) and its taurine and glycine conjugated derivatives tauroursodeoxycholic acid (TUDCA) and glycoursodeoxycholic acid (GUDCA) in preventing retinal neovascularization (RNV) in an experimental model of ROP. Seven-day-old mice pups (P7) were subjected to oxygen-induced retinopathy (OIR) and were treated with bile acids for various durations. Analysis of retinal vascular growth and distribution revealed that UDCA treatment (50 mg/kg, P7–P17) of OIR mice decreased the extension of neovascular and avascular areas, whereas treatments with TUDCA and GUDCA showed no changes. UDCA also prevented reactive gliosis, preserved ganglion cell survival, and ameliorated OIR-induced blood retinal barrier dysfunction. These effects were associated with decreased levels of oxidative stress markers, inflammatory cytokines, and normalization of the VEGF–STAT3 signaling axis. Furthermore, in vitro tube formation and permeability assays confirmed UDCA inhibitory activity toward VEGF-induced pro-angiogenic and pro-permeability effects on human retinal microvascular endothelial cells. Collectively, our results suggest that UDCA could represent a new effective therapy for ROP.

Circulating Lysophosphatidylcholines in Early Pregnancy and Risk of Gestational Diabetes in Chinese Women

Objectives This study aimed to explore associations of lysophosphatidylcholines (LPCs) in early pregnancy with gestational diabetes mellitus (GDM), and whether LPCs mediated the associations of bile acids with GDM risk or had interactive effects with bile acids on GDM risk. Design We conducted a 1:1 nested case-control study (n = 486) from a large prospective pregnant women cohort in urban Tianjin, China. Blood samples were collected at their first antenatal care visit (median at 10th gestational week). LPCs were measured by liquid chromatography-tandem mass spectrometry analysis. Conditional binary logistic regression and restricted cubic spline analysis were used to identify cutoff points of these metabolites for GDM risk. Results Of the 6 detectable LPCs, LPC14:0 less than 0.24 nmol/mL, LPC15:0 at 0.45 nmol/mL or greater, and LPC18:0 at 18.00 nmol/mL or greater were independently associated with GDM risk. Adjustment for LPC18:0 slightly attenuated odds ratios (ORs) of deoxycholic acid (DCA, ≤ 0.36 nmol/mL) and glycoursodeoxycholic acid (GUDCA, ≤ 0.07 nmol/mL) for GDM, and the correlations of DCA and GUDCA with LPC18:0 were weak. However, the presence of DCA at 0.36 nmol/mL or less greatly amplified the adjusted OR of LPC18:0 at 18.00 nmol/mL or greater alone for GDM from 8.18 (2.51-26.7) up to 17.7 (6.64-47.1), with significant additive interaction. Similarly, the presence of GUDCA at 0.07 nmol/mL or less also greatly amplified the adjusted OR of LPC18:0 at 18.00 nmol/mL or greater alone for GDM from 17.2 (1.77-168) up to 73.8 (12.7-429), with significant additive interaction. Conclusions LPCs in early pregnancy were associated with GDM risk. Low DCA or GUDCA greatly amplified the effect of high LPC18:0 on GDM, and its molecular mechanism is worth further investigations.

Liquid Chromatography/Tandem Mass Spectrometry for the Simultaneous Determination of Ursodiol and its Major Metabolites, Tauroursodeoxycholic Acid and Glycoursodeoxycholic Acid in Human Plasma

A rapid and sensitive method is described for the quantification of ursodiol and its major metabolites glycoursodeoxycholic acid (GUDCA) and tauroursodeoxycholic acid (TUDCA) in human plasma using single internal standard (Ursodeoxycholic Acid d4). Solid phase extraction was performed and chromatographic separation of 5µL injected sample was achieved using Waters Xterra, 5µm column with a mobile phase comprised of methanol and 5 mM ammonium formate with 0.1 % acetic acid ( 70 : 30, v/v ). The mass spectrometer was used in negative ion mode and multiple reactions monitoring using electro spray ionization mode as an interface. The method was fully validated and the calibration curves were linear over the concentration range of 25.9 to 15300.1 ng/mL for ursodiol, 2.7 to 1587.5ng/mLfor tauroursodeoxycholicacid and 25.4 to 15040.9 ng/mL for glycoursodeoxycholic acid. The method was sensitive and specific, with the lower limit of quantification of 25.9, 2.7 and 25.4 ng/ml for ursodiol, tauroursodeoxycholic acid and glycoursodeoxycholic acid respectively. The present method includes a simple and rapid sample preparation with shorter analysis run time and less flow rate compared to previously reported methods. The method was applied successfully for a bioequivalence study in healthy subjects.