Azithromycin inhibits interleukin-6 but not fibrinogen production in hepatocytes infected with cytomegalovirus and chlamydia pneumoniae

Chlamydia pneumoniae and cytomegalovirus (CMV) have been associated with the development of atherosclerosis. Inflammatory stimuli initiate the biosynthesis of fibrinogen, interleukin (IL)-6 and plasminogen activator inhibitor (PAI)-1 in the liver. Chronic infection may perpetuate the inflammatory status. We hypothesized that infection of human hepatocytes with the intracellular pathogens C pnemoniae and CMV accelerates biosynthesis of fibrinogen, IL-6, and PAI-1 but that this biosynthesis can be reduced with the use of azithromycin. HepG2 human hepatocytes were infected with C pneumoniae and CMV in vitro in the presence of 0, 0.016, 0.125, or 1 μg/mL azithromycin. We measured IL-6, PAI-1, and fibrinogen after 24, 48, 72, and 96 hours. C pneumoniae-infected hepatocytes produce IL-6 (2667 ± 309 pg/mL vs 137 ± 120 pg/mL in uninfected cells after 96 hours. Incubation with 0.016 μg/mL azithromycin decreased IL-6 levels to a mean of 1516 ± 402 pg/mL, and incubation with 0.125 and 1 μg/mL azithromycin decreased IL-6 to 871 ± 364 and 752 ± 403 pg/mL, respectively. C pneumoniae-induced IL-6 production was time- and dose-dependent. The interaction of C pneumoniae with azithromycin treatment was significant, indicating an inhibitory effect of azithromycin on C pnemoniae-induced IL-6 production. CMV infection did not lead to IL-6 production by hepatocytes. C pneumoniae and CMV infection did not induce any changes in PAI-1 production. Fibrinogen production was increased by CMV infection after 72 hours (838 ± 88 ng/mL; P < .01) and after 96 hours by infection with both C pneumoniae and CMV (765 ± 100 and 846 ± 123 ng/mL, respectively; P < .05). Azithromycin did not suppress CMV- or C pneumoniae-induced fibrinogen production. Moreover, we could not confirm an antiinflammatory effect of azithromycin in experiments with cross-titrations of azithromycin against either IL-1 or IL-6 (P > .05). Azithromycin reduces C pneumoniae-induced IL-6 production, but not fibrinogen production, by human hepatocytes. This is a result of the antimicrobial properties of azithromycin and not a direct antiinflammatory effect.     

Procoagulant and inflammatory response of virus-infected monocytes

BACKGROUND: Monocytes play a prominent role in inflammation, coagulation and atherosclerosis by their ability to produce tissue factor (TF) and cytokines. The aim of the present study was to establish whether virus-infected monocytes initiate coagulation. In addition, the production of cytokines by monocytes may accelerate the chronic process of atherosclerosis and may contribute to coronary syndromes by eliciting plaque instability. MATERIALS AND METHODS: Monocytes were isolated by Vacutainer(R), BD Biosciences, Alphen aan den Rijn, Netherlands and subsequent magnetic cell sorting (MACS(R), Milteny Biotec, Bergish Gladbach, Germany). Coagulation times in normal pooled plasma and Factor VII-deficient plasma were measured after infection with cytomegalovirus (CMV), Chlamydia pneumoniae (Cp) and influenza A\H1N1. Anti-TF antibodies were added to neutralize TF expressed on monocytes. Interleukins (IL) 6, 8 and 10 were measured in the supernatants. RESULTS: Chlamydia pneumoniae- and CMV-infected monocytes decreased the clotting time by 60%, and influenza-infected monocytes by 19%, as compared to uninfected monocytes. Procoagulant activity was absent when Factor VII-deficient plasma or anti-TF antibodies were used. Monocytes produced both IL-6 and IL-8 after infection with CMV (317 pg mL-1 and 250 pg mL-1) or Cp (733 pg mL-1 and 268 pg mL-1). Similar results were obtained for influenza virus-infected monocytes, but the levels of both cytokines were 3-5-fold higher (1797 pg mL-1 and 725 pg mL-1). Interleukin-10 was not produced by infected monocytes. CONCLUSION: The procoagulant activity of virus-infected monocytes is TF-dependent. Although influenza infection did not generate a significant reduction in clotting time, the pronounced expression of IL-6 and IL-8 may induce local and/or systemic inflammatory reactions, which may be associated with plaque rupture and atherosclerosis. The lack of production of the anti-inflammatory cytokine IL-10 may even accelerate these processes.     

巨细胞病毒对多发性骨髓瘤细胞系KM3细胞的感染及其对IL-6 mRNA表达的影响

目的　探讨人巨细胞病毒 (CMV)对多发性骨髓瘤细胞系KM3细胞的感染及其对细胞IL 6mRNA表达的影响。方法　以 10 0 ,10 ,1半数组织培养感染量 (TCID50 )滴度的CMV与KM3细胞共培养 ,RT PCR法检测细胞CMV即刻早期抗原基因 (IE)、甘油醛 3 磷酸脱氢酶基因 (GAPDH)及IL 6mRNA的表达 ,流式细胞术检测细胞CMVpp6 5抗原的表达 ,透射电镜检测细胞内CMV病毒颗粒。结果　CMV感染的KM3细胞可明显地表达IEmRNA ,同时该细胞IL 6mRNA水平明显升高 ;10 0 ,10TCID50滴度的CMV感染的KM3细胞CMVpp6 5抗原表达率分别为 (5 .5 8± 1.5 5 ) %、(3.75± 0 .85 ) % ,与对照组的 (1.5 8± 0 .33) %相比 ,差异有显著性 (P <0 .0 5 ) ;透射电镜下 ,10 0TCID50 滴度的CMV感染的KM3细胞内及胞膜表面可见到CMV病毒颗粒。结论　CMV可感染多发性骨髓瘤细胞系KM3细胞 ,并在其中活化复制 ;该病毒可提高KM3细胞IL 6mRNA的表达     

Levofloxacin kills Chlamydia pneumoniae and modulates interleukin 6 production by HEp-2 cells

BACKGROUND: Chlamydia pneumoniae is known to cause acute respiratory infection and more recently it has been studied as a pathogen causing inflammatory changes in chronic diseases such as atherosclerosis. This study addresses the antichlamydial effect of levofloxacin and its role in modulation of a proinflammatory cytokine IL-6 production by uninfected and infected HEp-2 cells. METHODS: HEp-2 cell monolayers were infected with previously prepared and frozen aliquots of C.pneumoniae [1 x 10(3) inclusion-forming units (IFU)/ml] by centrifugation for 30 min and incubation at 37 degrees C for 1 h. Infected monolayers were treated with levofloxacin (3 or 8 microg/ml) immediately after infection (0 h) or 24 h after infection. Monolayers were examined daily for 96 h after infection by counting inclusions with fluorescently labeled antichlamydial monoclonal antibody. Aliquots of disrupted monolayers were titrated to determine the numbers of viable C. pneumoniae IFU/ml. IL-6 concentrations in cell supernatants were determined by ELISA assays. RESULTS: Infected HEp-2 cells produced IL-6. Noninfected HEp-2 cells demonstrated modulation of IL-6 production by levofloxacin. No viable C. Pneumoniae were detected in infected HEp-2 cells when the monolayer was treated with levofloxacin immediately after infection (0 h). In contrast, when cells were treated 24 h after infection, a gradual decline in the number of viable C. pneumoniae occurred; by 96 h into the assay >or=98% of C. pneumoniae were killed. IL-6 concentrations were similar in the supernatants of levofloxacin-treated and nontreated HEp-2 cells. CONCLUSIONS: (1). Levofloxacin is effective in eliminating C. pneumoniae from infected HEp-2 cells; (2). although levofloxacin modulates the production of IL-6 in untreated HEp-2 cells, no evidence for such modulation was observed in HEp-2 cells infected with C. pneumoniae. (3). Presence of viable C. pneumoniae may not be necessary for IL-6 production by infected and treated HEp-2 cells.     

Susceptibility to cytomegalovirus infection may be dependent on the cytokine response to the virus.

BACKGROUND: Cytomegalovirus (CMV) infection is an important cause of morbidity and mortality in an immunocompromised host. Pulmonary infection with CMV results in an inflammatory response, which includes the local production of cytokines. Cytokine production stimulated by CMV infection serves to activate a series of immunologic responses involved in viral clearance. Previous work has demonstrated that different mouse strains express variable sensitivity to CMV infection. METHODS: Using mouse strains that express sensitive (BALB/cj) and resistant (C57BL/6) CMV phenotypes, we asked whether the differences in susceptibility to infection were caused by differences in pulmonary cytokine production after intraperitoneal infection with CMV. RESULTS: C57 mice demonstrated a higher total bronchoalveolar lavage (BAL) and BAL lymphocyte count at 3 and 7 days after intraperitoneal infection compared with BALB mice. There were no differences in BAL cytokine production; however, we were able to demonstrate differences in CMV DNA load in the lungs of BALB mice compared with that of C57 mice. In addition, there appeared to be increased whole-lung production of the TH2 cytokine IL-10 in the BALB mice versus the C57 mice. CONCLUSIONS: This observation suggests that the genetic susceptibility to CMV infection may, in part, be regulated by differences in cytokines production within the local environment.     

Effect of levofloxacin on the viability of intracellular Chlamydia pneumoniae and modulation of proinflammatory cytokine production by human monocytes

Although antibiotics are known to affect the intracellular growth of Chlamydia pneumoniae in acute infections, their efficacy in therapy for chronic infections, including atherosclerosis, remains debatable. Human monocyte-derived macrophages (MDM) obtained from monocytes of healthy donors were infected with C. pneumoniae AR-39 and treated with levofloxacin (8 microg/mL) immediately after infection (0 hours) or 24 hours after infection. Levofloxacin treatment at 24 hours, but not at 0 hours, resulted in a significant decrease in the number of C. pneumoniae inclusions within the MDM (p < 0.05). Also decreased were concentrations of proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, IL-6, and IL-8 in the extracellular medium (p < 0.01). Viable counts in titrations remained similar to those in untreated controls. In summary, levofloxacin administered to MDM at serum-attainable levels 24 hours after C. pneumoniae infection significantly decreased inclusion counts and proinflammatory cytokine production, but did not eliminate the C. pneumoniae infection.     

Interleukin-6 production by endothelial cells after infection with influenza virus and cytomegalovirus

Inflammation plays a role in the pathogenesis of cardiovascular diseases. Viruses may be a cause of chronic inflammation, and both influenza virus and CMV have been associated with cardiovascular diseases. IL-6, a proinflammatory cytokine with antiviral effects, has a pivotal role in the immune response, and under pathologic conditions, prohemostatic effects of IL-6 could lead to pathologic thrombosis and vascular plaque instability. To investigate this role of IL-6, we measured the production of IL-6 by human endothelial cells after infection with influenza virus and CMV. After infection with influenza virus or CMV, IL-6 release into the medium increased (1756.5+/-156.9 pg/mL vs 284.4+/-55.3 pg/mL; P < .001) for influenza-Infected compared with uninfected cells after 36 hours' incubation. Ultracentrifuged influenza virus supernatants, heat-inactivated virus, and purified hemagglutinin were not able to elicit IL-6 synthesis by human endothelial cells. These findings show that CMV and influenza virus are capable of modulating the in vitro production of IL-6, a cytokine involved in vascular inflammation, by human endothelial cells.     

Hepatic insulin resistance,metabolic syndrome and cardiovascular disease

BackgroundThe metabolic syndrome is a constellation of common metabolic disorders that is associated with cardiovascular disease. Insulin resistance has a central role in the pathophysiology of metabolic syndrome.Recent advancesIt is now commonly accepted that chronic inflammation associated with visceral obesity induces insulin resistance in the liver. Chronic inflammation is characterized by the production of abnormal adipokines and cytokines such as TNF-α, FFA, IL-1, IL-6, leptin and resistin. These factors inhibit insulin signalling in hepatocytes by activating SOCS proteins, several kinases such as JNK, IKK-β and PKC and protein tyrosine phosphatases such as PTP1B and PTEN, that in turn impair insulin signalling at insulin receptor and insulin receptor substrate (IRS) level. Hepatic insulin resistance in turn causes impaired suppression of glucose production by insulin in hepatocytes leading to hyperglycemia. An important and early complication of hepatic insulin resistance is the induction of hepatic VLDL production, via changes in the rate of apoB synthesis and degradation and de novo lipogenesis, or increased FFA flux from adipose tissue into the liver. Insulin resistance also stimulates the production of CRP and PAI-1, both markers of an inflammatory state. All metabolic abnormalities related to hepatic insulin resistance have been shown to directly or indirectly promote atherosclerosis. Hyperglycemia induces a series of alterations including endothelial dysfunction, cellular proliferation, changes in extracellular matrix conformation and impairment of LDL receptor-mediated uptake decreasing the in vivo clearance of LDL. Small dense LDLs associated with high circulating VLDL have higher affinity to the intimal proteoglycans leading to the penetration of more LDL particles into the arterial wall. CRP can also accelerate atherosclerosis by increasing the expression of PAI-1 and adhesion molecules in endothelial cells, inhibition of nitric oxide formation and increasing LDL uptake into macrophages.ConclusionsOverall, growing evidence suggests that hepatic insulin resistance is sufficient to induce several components of the metabolic syndrome and promote progression to cardiovascular disease. Many unresolved questions remain however on the molecular and cellular mechanisms that trigger hepatic insulin resistance and promote the development of clinical metabolic syndrome.     

Chlamydia LPS and MOMP seropositivity are associated with different cytokine profiles in patients with coronary heart disease

BACKGROUND: Persistent Chlamydia pneumoniae infection within atherosclerotic plaques are possible stimulators of inflammation in atherosclerosis. Why the microbe develops persistency in some individuals is unknown, but experimental studies in cell cultures and animals have demonstrated the levels of gamma interferon (IFNgamma) and interleukin 10 (IL-10) to be of crucial importance. DESIGN: We wanted to evaluate whether Chlamydia seropositivity in patients with coronary heart disease (CHD) (n = 193) was associated with elevated IFNgamma and IL-10. Two methods for detection of Chlamydia antibodies were included as well as analysis of tumour necrosis factor alpha (TNFalpha), soluble vascular cell adhesion molecule 1 (sVCAM-1) and soluble E-selectin for the evaluation of vascular inflammation. RESULTS: We found that patients with IgA antibodies towards Chlamydia lipopolysaccharide (LPS) had elevated levels of IFNgamma (P = 0.048), IL-10 (P = 0.029), TNFalpha (P = 0.009) and sE-selectin (P = 0.045), while Chlamydia LPS IgG seropositivity predicted elevated levels of IL-10 (P = 0.013). Patients with IgA antibodies towards C. pneumoniae major outer membrane protein (MOMP) without simultaneous LPS IgA seropositivity had lower levels of IFNgamma and sVCAM-1 when compared to patients with Chlamydia LPS IgA alone (P = 0.005 for IFNgamma, P = 0.016 for VCAM-1) and patients with combined Chlamydia MOMP and LPS IgA seropositivity (P = 0.046 and P = 0.013, respectively). CONCLUSIONS: In summary, we demonstrated an association between Chlamydia LPS IgA seropositivity and elevated levels of IFNgamma, IL-10, TNFalpha, sVCAM-1 and sE-selectin in CHD patients that might indicate persistent Chlamydia infection and a proinflammatory state. On the other hand, C. pneumoniae MOMP antibodies were not associated with elevated inflammatory markers and might merely be indicative of past infection, possibly with successful microbe clearance.     

Iron enhances endothelial cell activation in response to Cytomegalovirus or Chlamydia pneumoniae infection

BACKGROUND: Chronic inflammation has been implemented in the pathogenesis of inflammatory diseases like atherosclerosis. Several pathogens like Chlamydia pneumoniae (Cp) and cytomegalovirus (CMV) result in inflammation and thereby are potentially artherogenic. Those infections could trigger endothelial activation, the starting point of the atherogenic inflammatory cascade. Considering the role of iron in a wide range of infection processes, the presence of iron may complicate infection-mediated endothelial activation. MATERIALS AND METHODS: Endothelial intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and endothelial selectin (E-selectin) expression were measured using flow cytometry, as an indication of endothelial activation. Cytotoxicity was monitored using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Immunostaining was applied to measure Cp and CMV infectivity to endothelial cells. RESULTS: An increased number of infected endothelial cells in a monolayer population leads to a raised expression of adhesion molecules of the whole cell population, suggesting paracrine interactions. Iron additively up-regulated Cp-induced VCAM-1 expression, whereas synergistically potentiated Cp-induced ICAM-1 expression. Together with CMV, iron also enhanced ICAM-1 and VCAM-1 expression. These iron effects were observed without modulation of the initial infectivity of both microorganisms. Moreover, the effects of iron could be reversed by intracellular iron chelation or radical scavenging, conforming modulating effects of iron on endothelial activation after infections. CONCLUSIONS: Endothelial response towards chronic infections depends on intracellular iron levels. Iron status in populations positive for Cp or CMV infections should be considered as a potential determinant for the development of atherosclerosis.     

Interaction between Chlamydia pneumoniae seropositivity, inflammation and risk factors for atherosclerosis in patients with severe coronary stenosis

OBJECTIVE: To investigate whether Chlamydia pneumoniae (Cpn) seropositivity in patients with suspected coronary artery disease (CAD) (n = 81) is associated with increases in markers of inflammation, the severity of coronary atherosclerosis, and traditional risk factors for cardiovascular events. MATERIAL AND METHODS: The severity of coronary atherosclerosis was ranked by Gensini score. Inflammation and endothelial dysfunction were evaluated using white blood cell counts and levels of high-sensitivity C-reactive protein (hs-CRP), ferritin, tumour necrosis factor-alpha (TNF-alpha), interleukins 1beta and 6 (IL-1beta, IL-6), soluble intercellular adhesion molecule-1 (sICAM-1), E-selectin and oxidized LDL (oxLDL), and these were compared between Cpn-seropositive and seronegative individuals. RESULTS: IgA and IgG Cpn seropositivity were significantly associated with the presence of CAD (p = 0.005) and were independent predictive factors for the severity of coronary atherosclerosis (p = 0.005). Elevated levels of IL-6 (p = 0.027) and triglyceride (p = 0.038) and low levels of high-density lipoprotein cholesterol (HDL-C) (p = 0.038) were significantly predicted by Cpn IgA and IgG seropositivity. CONCLUSIONS: Seropositivity for Cpn is a risk factor for patients with significant angiographically documented coronary stenosis. Additionally, Cpn seropositivity was significantly associated with dyslipidemia and elevated IL-6, known risk factors for CAD. These observations indicate that Cpn infection may be one entry point to the causal or contributory pathways that lead to atherosclerosis and its clinical manifestations.     

L'infection à cytomégalovirus chez le patient immunocompétent de réanimation : fièvre banale ou maladie grave ?

Cytomegalovirus (CMV) infection is a current pathology but complex and rather unknown. Primary infection occurs in 60 to 100% of the developed countries population, generally during childhood and often causes little or no symptoms, unlike exceptional cases. Like other herpesviridae, CMV remains in the organism and can be responsible for serious infections in immunocompromised patients. Several studies performed last decade have been also observed that CMV reactivation could occurred in the Intensive Care Unit (ICU) settings in patients who were immunocompetent at time of the admission. Trigger factors, currently present in ICU, would be inflammation or sepsis, associated or not to an immunity decrease. Cytomegalovirus reactivation could represent a biological marker because it could be associated with a higher morbidity and mortality. Pathogenic properties of CMV could interfere with pathological pattern of the complex ICU patient because of direct tissue injury or immunity and inflammation disequilibrium. Hence, CMV infection should be checked in ICU patients after several days of hospitalisation, developing a prolonged fever without other causes, or in the case or ARDS, MOF or every suggestive end-organ disease (interstitial pneumonia, inflammation of the digestive tract, hepatitis…). Further studies are needed to determine the utility of an antiviral treatment and the level of antigenemia necessary to treat.     

Chlamydia pneumoniae DNA in peripheral blood mononuclear cells in peritoneal dialysis patients.

OBJECTIVE: The aim of the present study was to examine the association between infection with Chlamydia pneumoniae and symptomatic atherosclerosis in peritoneal dialysis (PD) patients. DESIGN: Cross-sectional study. SETTING: Peritoneal Dialysis Unit of Kingston General Hospital. PATIENTS: Fifty-five prevalent PD patients. OUTCOME MEASURES: (1) Infection with C. pneumoniae diagnosed by detection of DNA in peripheral blood mononuclear cells (PBMCs) using polymerase chain reaction. (2) Symptomatic atherosclerosis involving the coronary, cerebral, or peripheral circulation. RESULTS: The DNA of C. pneumoniae was detected in PBMCs in 33 patients (60.0%). Atherosclerosis was present in 16 of 33 (48%) PBMC C. pneumoniae DNA-positive patients, and in 10 of 22 (45%) PBMC C. pneumoniae DNA-negative patients (p = 0.83). Using multiple logistic regression and controlling for a number of known cardiovascular risk factors, PBMC C. pneumoniae DNA status was not predictive of atherosclerosis. The only significant independent predictors of atherosclerosis were diabetes and age. CONCLUSIONS: In prevalent PD patients, a high prevalence of symptomatic atherosclerosis and of Chlamydia pneumoniae DNA in PBMCs were seen; however, the results of the present study do not support the presence of an association between infection with C. pneumoniae and atherosclerosis.     

Azithromycin reduces Chlamydia pneumoniae-induced attenuation of eNOS and cGMP production by endothelial cells

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.     

Inflammation,infection and antimicrobial therapy in coronary heart disease – where do we currently stand?

Traditional atherosclerotic risk factors such as hypertension, smoking, hyperlipidaemia and diabetes mellitus, account for only about 50% of the clinical occurrence of coronary heart disease (CHD). The infectious hypothesis proposes that various microorganisms, in particular, Chlamydia pneumoniae, may serve as potential etiological factors, linking inflammation and atherosclerosis (or its clinical manifestations). Evidence from seroepidemiology, pathology, animal models, molecular biology and immunology, and human antibiotic intervention studies, collectively have suggested a largely positive association between C. pneumoniae infection and CHD. As CHD is a multifactorial disease, it is possible that C. pneumoniae may interact with conventional cardiovascular risk factors and predispose certain genetically susceptible people to atherosclerotic disease. However, the precise nature of a causal or coincidental link between C. pneumoniae and CHD remains to be determined. The results of ongoing antibiotic intervention studies may help to further clarify the role of infection and inflammation in CHD, but until such a role is proven beyond reasonable doubt, antimicrobial therapy cannot yet be justified in the treatment or prevention of CHD. A current perspective is presented in this review.     

微生物感染、炎症与动脉粥样硬化

微生物感染参与动脉粥样硬化的形成过程，从而成为缺血性心、脑血管病的新的危险因子。本文概括近年来国内外关于肺炎衣原体，幽门螺杆菌以及病毒感染(包括CMV、EBV、HIV、柯萨奇B、单纯疱疹和风疹病毒等)促动脉粥样硬化的证据。这些证据包括自动脉斑块处用先进手段检出病原体的抗原或核酸；患者血清中抗体水平；患者血清中的炎症标志物，动物试验结果以及抗微生物感染治疗效果等。同时指出围绕此问题的争论和有待解决的疑点。     

Cooperation between cytotoxic and helper T lymphocytes in protection against lethal Sendai virus infection. Protection by T cells is MHC-restricted and MHC-regulated; a model for MHC-disease associations

The in vivo importance of class I MHC regulation of the Tc response to a natural pathogenic agent of high virulence was studied on the basis of our previous demonstration of a major difference in the capacity to generate a Sendai virus-specific Tc response between C57BL/6 (B6, H-2b) mice and H-2Kb mutant B6.C-H-2bm1 (bm 1) mice. These two mouse strains differ from each other only in three amino acids in the crucial H-2Kb restriction element for this response. bm 1 mice, in contrast to B6 mice, are Tc nonresponders against this virus, but show Sendai-specific T cell proliferation, antibody production, and DTH reactions, as well as NK cell activity, equal to those of B6 mice. B6, Sendai Tc-deficient bm 1 and T cell-deficient B6 nu/nu mice differ from each other in susceptibility to lethal pneumonia induced by i.n. inoculation of virulent Sendai virus. The lethal dose (LD50) in B6 mice averaged 152 TCID50, in bm 1 mice, 14 TCID50 and in B6 nu/nu mice 0.5 TCID50. The importance of Tc was also shown by the complete protection of B6 nu/nu mice against infection with a lethal virus dose by i.v. injection of a Sendai virus-specific, IL-2-dependent and H-2Kb-restricted B6 Tc clone. In vivo protection by this Tc clone was H-2Kb-restricted. Apart from Tc, an important role for virus-specific Th cells is evident from the difference in susceptibility between bm 1 and B6 nu/nu mice. This conclusion was supported by the demonstration that the mean survival time of B6 nu/nu and bm 1 nu/nu mice could be significantly prolonged, in an I-Ab-restricted manner, by the injection of in vitro-propagated, Sendai-specific B6 or bm 1 Th clones after a lethal dose of Sendai virus, and by the demonstration that inoculation of these Th clones provided help to virus-specific Tc by means of IL-2 production. Strikingly, Th and Tc cooperate in anti-Sendai virus immunity, since permanent survival of lethally infected nu/nu mice was only achieved by inoculation of a mixture of Tc and Th clones or a mixture of a Tc clone and rIL-2. This study provides a unique model for the study of MHC-disease associations.     

Chlamydia pneumoniae and coronary artery disease: the antibiotic trials

Parallel with the mounting evidence that atherosclerosis has a major inflammatory component, provoking agents that may initiate and drive this process have been sought. Infectious agents such as Chlamydia pneumoniae have been alleged to be activators of inflammation that may contribute to atherosclerosis and thus coronary artery disease (CAD) and its associated complications. A logical pneumoniae extension of this theory whether treating C pneumoniae infection with antibiotics and/or modulating inflammatory processes can affect CAD and its sequelae. This article discusses the potential role of C pneumoniae in atherosclerosis, its detection, and the rationale for antibiotics. Additionally, it summarizes the current randomized clinical trials of antichlamydial antibiotics in patients with CAD and draws conclusions based on the results.     

The effect of virus infection on the adherence of leukocytes or platelets to endothelial cells

It has been reported that atherosclerotic lesions contain genomic material belonging to members of the herpes family. This suggests that latent viral infection may be one of the atherogenic triggers. In this study we show that early infection of endothelial cell monolayers with Herpes Simplex virus type 1 (HSV-1) or Cytomegalovirus (CMV) results in an increased monocyte (MC) and polymorphonuclear leukocyte (PMN) adherence, but not in an increased platelet adhesion. Further, is demonstrated that MC and PMN respond differently to virus infected endothelial cell monolayers: PMN adhesion to CMV infected cells is approximately 430% of the control adherence, while the MC adherence is increased to 160%. Also, a difference in virus acting is observed: the adherence of MC or PMN to HSV-1 infected endothelial cells is caused by a secreted adherence promoting factor, while the adherence of MC or PMN to CMV infected endothelial cells seems to be a cell-bound phenomenon. In addition, it was demonstrated that the augmentation of MC or PMN adherence to virus infected endothelial cells is sensitive to tunicamycin, suggesting that both virus infections induce the expression of glycoproteins on the endothelial cell membrane, which is responsible for the MC and PMN adhesion. Thus, HSV-1 and CMV infection of endothelium results in an increased adherence of leukocytes which is suggested, irrespective of the precise nature of the mechanism of virus induced atherosclerosis, to be the earliest event associated with endothelium cell damage.     

重症患者巨细胞病毒活动性感染与Th1/Th2型细胞因子的研究进展

重症患者巨细胞病毒(CMV)感染率极高,并且CMV感染后多呈潜伏性感染,同时感染CMV的重症患者往往缺乏典型的临床表现。但是当CMV再激活,即CMV活动性感染,此时可严重影响重症患者病情转归,导致多种不良预后的发生。究其机制为,CMV可通过影响辅助性T淋巴细胞1型和2型细胞(Th1/Th2)的功能,即通过调控Th1/Th2产生的细胞因子的数量及比例,来改变机体免疫状态,使CMV难以清除及易于再激活。因此Th1/Th2细胞因子的表达对CMV的再激活、复制和散播有着极其重要的作用及意义。本文就重症患者CMV活动性感染与Th1/Th2型细胞因子相互作用机制的研究进展作一综述。