cyclic-gmp and Cytomegalovirus-Infections

Intracellular infections with cytomegalovirus (CMV) or Chlamydia pneumoniae (Cp) may play a role in the aetiology of atherosclerosis. Nitric oxide (NO) is a key regulator of endothelial function. Under pathological conditions uncoupling of endothelial nitric oxide synthase (eNOS) leads to vessel damage as a result of production of oxygen radicals instead of NO. We hypothesized that infection-induced atherosclerosis is initiated by changes in NO metabolism and may be reversed by azithromycin treatment.. Confluent human umbilical vein endothelial cells (HUVECs) were infected with Cp or CMV. After 48 h of infection, production of eNOS, cyclic guanosine monophosphate (cGMP) and reactive oxygen species (ROS) was measured. Detection of cGMP was used as a reporter assay for the bioavailability of NO. Subsequently, Cp- and CMV-infected HUVECs were coincubated with 0.016 mg L(-1) and 1 mg L(-1) azithromycin.. Infection with Cp (MOI 1 and MOI 0.1) and CMV (MOI 1) caused a dose- and time-dependent reduction of eNOS production in the HUVECs: Cp MOI 1: 1141 +/- 74 pg mL(-1) (P < 0.01); Cp MOI 0.1: 3189 +/- 30 pg mL(-1) (P < 0.01); CMV: 3213 +/- 11 pg mL(-1) (P < 0.01) vs. 3868 +/- 83 pg mL(-1) for uninfected HUVECs. Chlamydia pneumoniae- but not CMV-infection also reduced cGMP-production (Cp: 0.195 +/- 0.030 pmol mL(-1) (P < 0.01); CMV: 0.371 +/- 27 pmol mL(-1) (P > 0.05) vs. 0.378 +/- 0.019 pmol mL(-1) for uninfected HUVECs). CMV-infection did not affect ROS production either, but Cp-infection reduced ROS-production by 21% (P > 0.05; Cp MOI 0.1) to 68% (P < 0.01; Cp MOI 1). Azithromycin treatment restored Cp-induced eNOS, cGMP and ROS production in a dose-dependent manner.. Infection with Cp in endothelial cells in vitro attenuates eNOS, cGMP and ROS production in HUVECs and azithromycin reverses Cp-induced effects on eNOS, cGMP and ROS-production. The results from our in vitro research support the role of antibiotic therapy for infection-induced atherosclerosis by indicating that azithromycin does actually improve endothelial function.

Topics: Anti-Bacterial Agents; Azithromycin; Cell Survival; Cells, Cultured; Chlamydophila Infections; Chlamydophila pneumoniae; Cyclic GMP; Cytomegalovirus Infections; Endothelial Cells; Humans; Nitric Oxide Synthase Type III; Reactive Oxygen Species

We hypothesized that cytomegalovirus (CMV) may contribute to the vasculopathy observed in cardiac allograft recipients by impairing the endothelial nitric oxide synthase pathway. We focused on asymmetric dimethylarginine (ADMA, the endogenous inhibitor of nitric oxide synthase) as a potential mediator of the adverse vascular effect of CMV.. Heart transplant recipients manifested elevated plasma ADMA levels compared with healthy control subjects. Transplant patients with CMV DNA-positive leukocytes had higher plasma ADMA concentrations and more extensive transplant arteriopathy (TA). Human microvascular endothelial cells infected with the CMV isolates elaborated more ADMA. The increase in ADMA was temporally associated with a reduction in the activity of dimethylarginine dimethylaminohydrolase (DDAH, the enzyme that metabolizes ADMA). Infected cultures showed high levels of oxidative stress with enhanced endothelial production of superoxide anion.. CMV infection in human heart transplant recipients is associated with higher ADMA elevation and more severe TA. CMV infection in endothelial cells increases oxidative stress, impairs DDAH activity, and increases ADMA elaboration. CMV infection may contribute to endothelial dysfunction and TA by dysregulation of the endothelial nitric oxide synthase pathway.

Topics: Amidohydrolases; Arginine; Cardiovascular Diseases; Cells, Cultured; Coronary Angiography; Coronary Artery Disease; Cyclic GMP; Cytomegalovirus Infections; Endothelium, Vascular; Female; Heart Transplantation; Humans; Male; Middle Aged; Nitric Oxide Synthase; Nitrites; Oxidative Stress; Risk Factors; Signal Transduction

An intraperitoneal (rat) cytomegalovirus (RCMV) infection in the rat caused an influx of mononuclear cells, which have been altered in functions and arachidonic acid (AA) metabolism. Phagocytosis has been increased considerably 3 days postinfection (p.i.), whereas the release of prostacyclin, thromboxane A2, 12-hydroxyheptadecatrienoic acid (HHT), 5-hydroxyeicosatetraenoic acid (5-HETE), and leukotriene B4 (LTB4) was inhibited for more than 80%. The release of superoxide anions and the chemiluminescence response (CL) upon opsonized zymosan stimulation did not differ from those observed in resident peritoneal macrophages. Additionally, the levels of cyclic nucleotides (cAMP and cGMP) were low in both resident and influx macrophages (day 3 p.i.). In contrast, peritoneal macrophages harvested on day 10 p.i. still showed a high level of phagocytosis. However, the intracellular level of cyclic AMP had decreased fivefold, whereas CL response and superoxide anion release were inhibited significantly. Moreover, the production of prostacyclin, LTB4, and 5-HETE was still suppressed in contrast to thromboxane synthesis, which has selectively been restored in these macrophages. A direct regulatory role of AA metabolites in changes in macrophage functions that were due to a RCMV infection could not be demonstrated.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Cyclic AMP; Cyclic GMP; Cytomegalovirus Infections; Epoprostenol; Fatty Acids, Unsaturated; In Vitro Techniques; Luminescent Measurements; Macrophages; Male; Rats; Rats, Inbred Strains; Superoxides; Thromboxane A2