Common dietary emulsifiers promote metabolic disorders and intestinal microbiota dysbiosis in mice.

Dietary emulsifiers are linked to various diseases. The recent discovery of the role of gut microbiota-host interactions on health and disease warrants the safety reassessment of dietary emulsifiers through the lens of gut microbiota. Lecithin, sucrose fatty acid esters, carboxymethylcellulose (CMC), and mono- and diglycerides (MDG) emulsifiers are common dietary emulsifiers with high exposure levels in the population. This study demonstrates that sucrose fatty acid esters and carboxymethylcellulose induce hyperglycemia and hyperinsulinemia in a mouse model. Lecithin, sucrose fatty acid esters, and CMC disrupt glucose homeostasis in the in vitro insulin-resistance model. MDG impairs circulating lipid and glucose metabolism. All emulsifiers change the intestinal microbiota diversity and induce gut microbiota dysbiosis. Lecithin, sucrose fatty acid esters, and CMC do not impact mucus-bacterial interactions, whereas MDG tends to cause bacterial encroachment into the inner mucus layer and enhance inflammation potential by raising circulating lipopolysaccharide. Our findings demonstrate the safety concerns associated with using dietary emulsifiers, suggesting that they could lead to metabolic syndromes.

Microfluidic platforms for rapid screening of cancer affinity reagents by using tissue samples.

Cancer is the most serious disease worldwide, and ovarian cancer (OvCa) is the second most common type of gynecological cancer. There is consequently an urgent need for early-stage detection of OvCa, which requires affinity reagent biomarkers for OvCa. Systematic evolution of ligands by exponential enrichment (SELEX) and phage display technology are two powerful technologies for identifying affinity reagent biomarkers. However, the benchtop protocols for both screening technologies are relatively lengthy and require well-trained personnel. We therefore developed a novel, integrated microfluidic system capable of automating SELEX and phage display technology. Instead of using cancer cell lines, it is the first work which used tissue slides as screening targets, which possess more complicated and uncovered information for affinity reagents to recognize. This allowed for the identification of aptamer (nucleic acid) and peptide probes specific to OvCa cells and tissues. Furthermore, this developed system could be readily modified to uncover affinity reagents for diagnostics or even target therapy of other cancer cell types in the future.

Characterization of the role of global regulator FliA in the pathophysiology of Pseudomonas aeruginosa infection.

FliA is known to be a sigma factor that regulates bacterial flagella gene expression. Accumulating evidence suggests that FliA is involved in bacterial behavior other than motility. To elucidate the contribution of FliA to Pseudomonas aeruginosa pathophysiology, we analyzed the biological properties and gene expression profiles of a ΔfliA mutant. Transcriptome analysis results demonstrated that the expression levels of flagella biogenesis genes decreased dramatically in the mutant; consequently, the ΔfliA mutant failed to synthesize flagella and exhibited reduced motility. The ΔfliA mutant displayed stronger hemolytic and caseinolytic activities, as well as pyocyanin production. The expression of type 6 secretion system-II genes and interbacterial competition activity was decreased in the ΔfliA mutant. Direct evidence of fliA participation in virulence was obtained from analysis of hypervirulent strain B136-33. Adhesion to and cytotoxicity toward mammalian cells and penetration through cell layers were noted; furthermore, the colonization ability of the fliA::Tn5 mutant in the intestines of laboratory mice was compromised. Notably, the fliA-overexpressing strain displayed phenotypes similar to that of the fliA-defective strain, indicating that optimal FliA levels are critical to bacterial physiology. Our findings indicate that FliA plays diverse roles in P. aeruginosa, not only in flagella biosynthesis, but also in pathophysiology.

Regulation of Motility and Phenazine Pigment Production by FliA Is Cyclic-di-GMP Dependent in Pseudomonas aeruginosa PAO1.

The transcription factor FliA, also called sigma 28, is a major regulator of bacterial flagellar biosynthesis genes. Growing evidence suggest that in addition to motility, FliA is involved in controlling numerous bacterial behaviors, even though the underlying regulatory mechanism remains unclear. By using a transcriptional fusion to gfp that responds to cyclic (c)-di-GMP, this study revealed a higher c-di-GMP concentration in the fliA deletion mutant of Pseudomonas aeruginosa than in its wild-type strain PAO1. A comparative analysis of transcriptome profiles of P. aeruginosa PAO1 and its fliA deletion mutant revealed an altered expression of several c-di-GMP-modulating enzyme-encoding genes in the fliA deletion mutant. Moreover, the downregulation of PA4367 (bifA), a Glu-Ala-Leu motif-containing phosphodiesterase, in the fliA deletion mutant was confirmed using the ß-glucuronidase reporter gene assay. FliA also altered pyocyanin and pyorubin production by modulating the c-di-GMP concentration. Complementing the fliA mutant strain with bifA restored the motility defect and pigment overproduction of the fliA mutant. Our results indicate that in addition to regulating flagellar gene transcription, FliA can modulate the c-di-GMP concentration to regulate the swarming motility and phenazine pigment production in P. aeruginosa.

Cholesterol-3-beta, 5-alpha, 6-beta-triol induced PI(3)K-Akt-eNOS-dependent cyclooxygenase-2 expression in endothelial cells.

Oxidized cholesterols belong to a subgroup of oxLDLs which play major roles in atherosclerosis. In order to investigate the contribution of oxysterols from oxLDLs in atherosclerosis, cholesterol-3-beta, 5-alpha, 6-beta-triol (alpha-Triol) was studied in human umbilical vein endothelial cells. We found that alpha-Triol concentration- and time-dependently enhanced COX-2 protein expression and mRNA production followed by PGE(2) generation in human umbilical vein endothelial cells. In addition, alpha-Triol upregulated peNOS(1177) protein phosphorylation and concentration-dependently increased nitric oxide production. eNOS(1177) phosphorylation was abrogated by the PI3K inhibitor, LY294002. In studying the mechanisms involved in alpha-Triol-induced COX-2/PGE(2) production, inhibitors of NOS, PI3K, p38, and NF-kappaB, effectively attenuated COX-2 protein induction and mRNA expression, suggesting that the PI(3)K-Akt-eNOS pathway, p38MAPK, and NF-kappaB are involved in alpha-Triol-induced COX-2 expression, and following increases in p38 and Akt phosphorylation, the concentration-dependent inhibition of COX-2 protein expression by L-NAME further suggested their involvement at the translation level. We concluded that alpha-Triol increases COX-2 mRNA and protein expression via coordination with the PI(3)K-Akt-eNOS pathway and NF-kappaB. Moreover, COX-2 gene expression might be regulated by activated p38 MAPK in another unknown regulation pathway. Our findings also suggested that alpha-Triol might contribute to the effect of induced atherosclerosis in humans through COX-2 production in endothelial cells.