Adverse effects of Microcystis aeruginosa exudates on the filtration, digestion, and reproduction organs of benthic bivalve Corbicula fluminea

Cyanobacteria bloom and the secondary metabolites released by the microorganism are extremely harmful to aquatic animals, yet study on their adverse effects in zoobenthos is rare. Corbicula fluminea widely distributed in freshwater environment with algal blooms. It is a typical filter feeding zoobenthos that may be affected by the secondary metabolites of cyanobacteria due to its high filtering rate. In this study, C. fluminea was exposed to Microcystis aeruginosa exudates (MaE) for 96 h, which was obtained from 5 × 105 cells/mL and 2.5 × 106 cells/mL exponential stage M. aeruginosa culture solution that represented cyanobacteria cell density needs environmental risk precaution control and emergent control, respectively. The responses of C. fluminea critical organs to MaE were analyzed and evaluated based on histopathological sections, antitoxicity biomarkers, and organ function biomarkers. The results showed that all the organs underwent structural disorders, cell vacuolization, apoptosis, and necrosis, and the damage levels increased as MaE concentration increased. The detoxification and antioxidant defense systems biomarkers in each organ response to MaE exposure differently and the level of reaction improved when MaE concentration increased. The siphon rate and acetylcholinesterase activity showed that the filtration function decreased significantly as the MaE concentration increased. Increased activity of glutathione S-transferase and amylase in the digestive gland indicate that it is the major detoxification organ of C. fluminea. Increased vitellogenin concentration and enlarged oocytes in the gonad indicate that MaE may have an estrogenic effect on C. fluminea. This study demonstrates that cyanobacteria threat benthic bivalves by inducing oxidative stress, inhibiting filtering feeding system, and disturbing digestion system and reproduction potential of C. fluminea.

Stromal Vascular Fraction Restores Vasodilatory Function by Reducing Oxidative Stress in Aging-Induced Coronary Microvascular Disease

Aims: The objective of this study is to identify mechanisms for adipose stromal vascular fraction's (SVF) restorative effects on vasodilation in aging-induced coronary microvascular disease (CMD). We hypothesize that reactive oxygen species (ROS) diminish β1-adrenergic receptor (β1ADR)- and flow-mediated dilation (FMD) in coronary arterioles, reversible by SVF and adipose-derived stem cells (ADSCs). Results: SVF attenuates aging-induced chronic accumulation of ROS and pro-oxidant gene and protein expression with enhancement of antioxidant gene and protein expression and glutathione, but not nitric oxide. ADSCs attenuate hydrogen peroxide while restoring nitric oxide and glutathione. Mass spectrometry of SVF- and ADSC-conditioned media reveals abundant antioxidant proteins suggesting a paracrine mechanism. FMD and β1ADR-mediated dilation diminished with aging, restored with SVF and ADSCs. FMD was restored by a switch in the acute signaling mediator from hydrogen peroxide in aging to peroxynitrite with SVF and ADSCs. Vasorelaxation to β1ADR-agonism was mechanistically linked with hydrogen peroxide, nitric oxide, and glutathione. Exogenous ROS eliminates isoproterenol-mediated dilation in youth that is blocked by inhibition of pro-desensitization and internalization proteins while nitric oxide enhances isoproterenol-mediated dilation in aging. Innovation: We introduce a novel mechanism by which ROS impacts β1ADR trafficking: the ROS/RNS-β1ADR desensitization and internalization axis. Aging-induced ROS shunts β1ADR from the plasma membrane into endosomes. SVF reduces oxidative burden, restoring functional β1ADR. Conclusions: SVF (and ADSCs to a lesser extent) reduce oxidative stress, and restore flow- and β1ADR-mediated vasodilation in aging. SVF represents a promising therapeutic strategy for CMD by addressing root cause of pathology; that is, oxidative stress-mediated hyperconstriction. Antioxid. Redox Signal. 38, 261-281.

Induction of Salivary Gland-Like Cells from Dental Follicle Epithelial Cells

The dental follicle (DF), most often associated with unerupted teeth, is a condensation of ectomesenchymal cells that surrounds the tooth germ in early stages of tooth development. In the present study, we aim to isolate epithelial stem-like cells from the human DF and explore their potential differentiation into salivary gland (SG) cells. We demonstrated the expression of stem cell-related genes in the epithelial components of human DF tissues, and these epithelial progenitor cells could be isolated and ex vivo expanded in a reproducible manner. The human DF-derived epithelial cells possessed clonogenic and sphere-forming capabilities, as well as expressed a panel of epithelial stem cell-related genes, thus conferring stem cell properties (hDF-EpiSCs). When cultured under in vitro 3-dimensional induction conditions, hDF-EpiSCs were capable to differentiate into SG acinar and duct cells. Furthermore, transplantation of hDF-EpiSC-loaded native de-cellularized rat parotid gland scaffolds into the renal capsule of nude mice led to the differentiation of transplanted hDF-EpiSCs into salivary gland-like cells. These findings suggest that hDF-EpiSCs might be a promising source of epithelial stem cells for the development of stem cell-based therapy or bioengineering SG tissues to repair/regenerate SG dysfunction.

Particulate matter promotes in vitro receptor-recognizable low-density lipoprotein oxidation and dysfunction of lipid receptors

Particulate matter may promote cardiovascular disease, possibly as a consequence of its oxidative potential. Studies using susceptible animals indicate that particulate matter aggravates atherosclerosis by increasing lipid/macrophage content in plaques. Macrophage lipid uptake requires oxidized low-density lipoprotein and scavenger receptors; same receptors are involved in particulate matter uptake. We studied in vitro particulate matter potential to oxidize low-density lipoproteins and subsequent cell uptake through scavenger receptors. Particulate matter-induced low-density lipoproteins oxidation was evaluated by the thiobarbituric acid assay. Binding/internalization was tested in wild type and scavenger receptor-transfected Chinese hamster ovary cells, and in RAW264.7 cells using fluorescently labeled low-density lipoproteins. Dose-dependent binding/internalization only occurred in scavenger receptor-transfected Chinese hamster ovary cells and RAW264.7 cells. Competition binding/internalization using particles showed that particulate matter induced decreased binding (∼50%) and internalization (∼70%) of particle-oxidized low-density lipoproteins and native low-density lipoproteins. Results indicate that particulate matter was capable of oxidizing low-density lipoproteins, favoring macrophage internalization, and also altered scavenger and low-density lipoproteins receptor function.