Glycated high-density lipoprotein regulates reactive oxygen species and reactive nitrogen species in endothelial cells

Nonenzymatic glycosylation of plasma proteins may contribute to the excess risk of developing atherosclerosis in patients with diabetes mellitus. Although it is believed that high-density lipoprotein (HDL) is glycosylated at an increased level in diabetic individuals, little is known about a possible linkage between glycated HDL and endothelial dysfunction in diabetes. To clarify whether glucose-modified HDL affects the function of endothelial cells, we first examined herein the level of H(2)O(2) generation from cultured human aortic endothelial cells (HAECs) exposed to a glycated oxidized HDL (gly-ox-HDL) prepared in vitro. Incubation for 48 hours with 100 microg/mL of gly-ox-HDL induced significant release of H(2)O(2) from cells and gly-ox-HDL-induced H(2)O(2) formation was inhibited in the presence of diphenyleneiodonium, an inhibitor of NADPH oxidase. In addition, stimulation of HAECs with gly-ox-HDL for 48 hours elicited a marked downregulation of catalase and Cu(2+), Zn(2+)-superoxide dismutase (CuZn-SOD), suggesting H(2)O(2) formation by gly-ox-HDL to be due to a disturbance involving oxidant and antioxidant enzymes in the cells. Treatment of HAECs with gly-ox-HDL attenuated the expression of endothelial nitric oxide synthase (eNOS), but not inducible nitric oxide synthase (iNOS), and this was followed by decreased production of nitric oxide (NO) by the cells. Furthermore, in vitro experiments with glycated HDL (gly-HDL) in the presence of 2 mmol/L EDTA and Cu(2+)-oxidized HDL suggested the effect of gly-HDL on endothelial function to be possibly potentiated by additional oxidative modification. Taking all of the above findings together, gly-ox-HDL may lead to the deterioration of vascular function through altered production of reactive oxygen species and reactive nitrogen species in endothelial cells.     

Functional heterogeneity of colony-stimulating factor-induced human monocyte-derived macrophages

Objectives:   Macrophages (Mφs) have various functions and play a critical role in host defense and the maintenance of homeostasis. Mφs exist in every tissue in the body, but Mφs from different tissues exhibit a wide range of phenotypes with regard to their morphology, cell surface antigen expression and function, and are called by different names. However, the precise mechanism of the generation of macrophage heterogeneity is not known. In the present study, the authors examined the functional heterogeneity of Mφs generated from human monocytes under the influence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage-CSF (M-CSF).
Methodology:   CD14 positive human monocytes (Mos) were incubated with M-CSF and GM-CSF for 6–7 days to stimulate the generation of M-CSF-induced monocyte-derived Mφs (M-Mφs) and GM-CSF-induced monocyte-derived Mφs (GM-Mφs), respectively. The expression of cell surface antigens and several functions such as antigen presenting cell activity, susceptibility to oxidant stress, and the susceptibility to HIV-1 and mycobacterium tuberculosis infection were examined.
Results:   GM-Mφs and M-Mφs are distinct in their morphology, cell surface antigen expression, and functions examined. The phenotype of GM-Mφs closely resembles that of human Alveolar-Mφs (A-Mφs), indicating that CSF-induced human monocyte-derived Mφs are useful to clarify the molecular mechanism of heterogeneity of human Mφs, and GM-Mφs will become a model of human A-Mφs.     

Vaccination with clumping factor A and fibronectin binding protein A to prevent Staphylococcus aureus infection of an aortic patch in mice

Staphylococcus aureus is a leading cause of ventricular assist device-related infections. This study evaluated the protective effect against S. aureus infection of active and passive immunization that targeted 3 proteins involved in bacterial attachment to a murine intra-aortic polyurethane patch. Active immunization of mice with a combination of the A domains of clumping factor A (ClfA), fibronectin-binding protein A (FnBPA) and fibronectin-binding protein B or passive immunization with monoclonal antibodies against ClfA and FnBPA resulted in a higher level of protection than that obtained by vaccination with either protein or antibody alone. The combination of antibodies or protein antigens appears to provide enhanced protection against prosthetic-device infection.     

Infection of sabA-positive H. pylori does not induce anti-Lewis X antibody in host

BACKGROUND/AIMS: H. pylori uses the sialic acid-binding adhesin (SabA) to recognize Lewis X (LeX) antigen of gastric epithelial cells. SabA is associated with nonopsonic activation of human neutrophils. The aims of this study were to examine the association of bacterial sabA status to the presence of anti-LeX antibody in host and the grade of gastritis. METHODOLOGY: 44 H. pylori strains cultured from gastric biopsies were examined by PCR for presence of 23SrRNA, cagA, and sabA. Serum samples were obtained from all the patients to measure the level of anti-LeX antibody. Histological grade of gastritis was graded according to the updated Sydney System. RESULTS: 23SrRNA gene and the cagA gene were seen in all the samples while 21 strains were sabA positive. The mean titer of anti-LeX antibody was 0.09 and 0.18 in patients infected with sabA-positive and -negative strain, respectively (NS). The grade of inflammatory infiltration was not significantly different between groups in both the corpus and the antral mucosa. CONCLUSIONS: Possession of the sabA gene by infected H. pylori strain might not associate with the presence of anti-LeX antibody in the host. Possession of sabA gene by infected H. pylori might not associate with severity of gastric mucosal inflammation.     

Contribution of the baroreflex afferent nerves to the production of vasoconstricted hypertension in volume-expanded dogs

Dextran in lactated Ringer's solution (20 ml/kg) was infused for 1 hour into anesthetized dogs with sinoaortic denervation and vagotomy (deafferentation; n = 10) and dogs treated with hexamethonium (de-efferentation; n = 13) to compare with our previous observation in dogs with an intact autonomic nervous system (control, n = 34). During the infusion, increase in blood pressure associated with increase in cardiac output was observed in all three groups. The increases in blood pressure were larger in the two groups with an impaired autonomic nervous system. In the recovery period, the control dogs and the hexamethonium-treated dogs showed gradual increases in total peripheral resistance and in vasoconstricted hypertension 3 hours after stopping the infusion. In contrast, the dogs with sinoaortic denervation and vagotomy did not show any increase in total peripheral resistance. The vasoconstricted groups showed peaks of natriuresis soon after the infusion, not 3 hours after the infusion when vasoconstriction was observed, although the dogs with deafferentation did not show a significant increase in natriuresis. Norepinephrine (0.5 micrograms/kg) was administered intravenously before and after volume expansion, and the pressor responses in the three groups after volume expansion were enhanced similarly (143%, 128%, and 136%, respectively). These results indicate that the afferent signals from peripheral vessels to the brain contribute to the production of vasoconstricted hypertension after acute volume expansion and that the vasoconstriction is independent of pressor hypersensitivity and is dissociated in time from the natriuresis.