Chlamydia pneumoniae infection of vascular smooth muscle and endothelial cells activates NF-kappaB and induces tissue factor and PAI-1 expression: a potential link to accelerated arteriosclerosis

The Probable Role of Chlamydia pneumoniae Infection in Acute Stroke

Cardiovascular diseases are the most leading cause of worldwide mortality. According to USA statistics, about 1 of 6 cardiovascular deaths is due to stroke. Stroke is the second most common cause of death and a chief cause of disability due to EU data. Treatment, care providing, rehabilitation costs and with the labor loss, the overall cost in EU due to stroke was estimated about €45 billion in year 2017. Acute stroke due to infectious diseases via several possible mechanisms with various clinical presentations were previously reported in the literature. Chlamydia pneumoniae is an obligate intracellular bacteria and extremely common in adult individuals. Besides it being a major cause of pneumonia in adults, association between atherosclerosis and vascular diseases was demonstrated by several sero-epidemiological studies and by direct detection of organism in atherosclerotic lesions by electron microscopy, immunohistochemistry, polymerase chain reaction. Also, several sero-epidemiological studies have demonstrated a link between Chlamydia pneumoniae infection and acute stroke. In this chapter, we will summarize the data in literature regarding the association between Chlamydia pneumoniae infection and acute stroke and we will try to explain the possible mechanisms that could be responsible in pathophysiology of stroke in these patients.

Association of Chlamydophila pneumoniae infection and hypertension during pregnancy - A case control study

BACKGROUND

The association of Chlamydophila pneumoniae infection with essential hypertension is known but its association with hypertension during pregnancy is controversial. Hence, this study aimed to explore the association of C. pneumoniae infection with hypertension during pregnancy. The objectives were to compare the presence of C. pneumoniae DNA in trophoblastic cells of placenta between hypertensive and normotensive pregnant women and to find out the presence of inflammatory marker (HSP-60) and the seropositivity (IgG and IgA) of C. pneumoniae in them.

MATERIALS AND METHODS

The study was conducted at a tertiary-care institute, in South-India between 2018 and 2020. Women with hypertension during pregnancy were study group (75) and normotensive pregnant women were control group (75). IgG and IgA antibodies, HSP-60 against C. pneumoniae were estimated by ELISA from 5 ml of venous blood. C. pneumoniae DNA was extracted from placental tissue after delivery and tested by RT-PCR.

STATISTICAL ANALYSIS

The association between C. pneumoniae DNA, seropositivity and hypertension was determined by student test and univariate regression analysis.

RESULTS

C. pneumoniae DNA was detected in the placenta of 29.3% with hypertension and none in controls and the odds was 6.5 (OR-6.5, CI 95%). HSP-60 was elevated in women with preeclampsia and not in gestational hypertension and controls. IgA was not detected and IgG was positive in 15.2% of women with preeclampsia.

CONCLUSION

There is a significant association between C. pneumoniae infection and hypertension during pregnancy and further studies are required to fulfil the Koch's postulates to prove or disprove it as a causative agent.

Chlamydia psittaci Plasmid-Encoded CPSIT_P7 Elicits Inflammatory Response in Human Monocytes via TLR4/Mal/MyD88/NF-κB Signaling Pathway

The chlamydial plasmid, an essential virulence factor, encodes plasmid proteins that play important roles in chlamydial infection and the corresponding immune response. However, the virulence factors and the molecular mechanisms of Chlamydia psittaci are not well understood. In the present study, we investigated the roles and mechanisms of the plasmid-encoded protein CPSIT_P7 of C. psittaci in regulating the inflammatory response in THP-1 cells (human monocytic leukemia cell line). Based on cytokine arrays, CPSIT_P7 induces the expression of interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemoattractant protein-1 (MCP-1) in THP-1 cells. Moreover, the expression levels of IL-6, IL-8, and MCP-1 stimulated by CPSIT_P7 declined after silencing of the Toll-like receptor 4 (TLR4) gene using small interfering RNA and transfection of a dominant negative plasmid encoding TLR4 (pZERO-hTLR4). We further demonstrated that transfection with the dominant negative plasmid encoding MyD88 (pDeNy-hMyD88) and the dominant negative plasmid encoding Mal (pDeNy-hMal) could also abrogate the expression of the corresponding proteins. Western blot and immunofluorescence assay results showed that CPSIT_P7 could activate nuclear factor κB (NF-κB) signaling pathways in THP-1 cells. Altogether, our results indicate that the CPSIT_P7 induces the TLR4/Mal/MyD88/NF-κB signaling axis and therefore contributes to the inflammatory cytokine response.

Mechanisms of Trained Innate Immunity in oxLDL Primed Human Coronary Smooth Muscle Cells

Objective: Damage and pathogen associated molecular patterns such as oxidized low-density lipoprotein (oxLDL) or bacillus Calmette-Guerin (BCG) vaccine can induce long term pro-inflammatory priming in monocytes and macrophages due to metabolic and epigenetic reprogramming—an emerging new concept called trained innate immunity. Vascular smooth muscle cells express pattern recognition receptors involved in trained innate immunity in monocytes. Here we investigated whether the mechanisms of trained innate immunity also control a proinflammatory phenotype in human coronary smooth muscle cells.

Methods: Human coronary smooth muscle cells were primed with oxLDL or BCG for 24 h. After a resting time of 4 to 7 days, the cells were restimulated with either PAM3cys4, LPS or TNFα and cytokine production or mRNA expression were measured. Then, mechanisms of monocyte trained innate immunity were analyzed in smooth muscle cells, including receptors, intracellular pathways as well as metabolic and epigenetic reprogramming.

Results: Priming with oxLDL or BCG lead to a significantly increased production of IL6, IL8 and MCP-1 following restimulation. OxLDL priming had little effect on the expression of macrophage or SMC marker genes. Proinflammatory priming of smooth muscle cells induced mTOR-HIF1α-signaling and could be blocked by mTOR-, TLR2-, and TLR4-inhibition. Finally, metabolic and epigenetic mechanisms of trained innate immunity in monocytes could be replicated in smooth muscle cells, including increased glucose consumption, lactate production, responsiveness to 6-fluoromevalonate and mevalonate treatment and inhibition of priming by the histone methyltransferase inhibitor methylthioadenosine (MTA).

Conclusion: We demonstrate for the first time that mechanisms of the so called trained innate immunity control a proinflammatory phenotype in non-immune cells of the vascular wall. Our findings warrant further research into the specificity of trained innate immunity as an immune cell response as well as the mechanisms of vascular smooth muscle cells inflammation.

Low-Dose Aspirin May Prevent Trophoblast Dysfunction in Women With Chlamydia Pneumoniae Infection

OBJECTIVE

Previously, we demonstrated that live Chlamydia pneumoniae (Cp) impaired extravillous trophoblast (EVT) viability and invasion and that Cp DNA was detected in placentas from cases with preeclampsia. We sought to elucidate whether (1) inactive forms of Cp also affect EVT function; (2) potential therapeutic interventions protect against the effects of Cp; and (3) anti-Cp antibodies are associated with preeclampsia.

METHODS

Human first-trimester EVTs were infected with ultraviolet light-inactivated Cp. Subgroups of EVTs were pretreated with low-dose acetyl-salicylic acid (ASA), dexamethasone, heparin, and indomethacin. We conducted functional assays after infection with inactivated Cp and measured interleukin 8 (IL8), C-reactive protein (CRP), heat shock protein 60 (HSP60), and tumor necrosis factor-α (TNFα) in culture media. We measured anti-Cp IgG serum levels from women who developed preeclampsia (N = 105) and controls (N = 121).

RESULTS

Inactivated Cp reduced EVT invasion when compared to noninfected cells (P < .00001) without adversely affecting cell viability. Increased levels of IL8, CRP, HSP60, and TNFα were detected in EVTs infected with inactivated Cp compared to noninfected cells (P < .0001). Only pretreatment with low-dose ASA prevented reduced EVT invasion and decreased release of inflammatory mediators (P < .01). Elevated anti-Cp IgG antibodies were more prevalent in serum from cases with preeclampsia compared to controls (67/105 vs 53/121; adjusted P = .013); elevated IgG correlated significantly with elevated serum CRP and elevated soluble fms-like tyrosine kinase-1-placental growth factor ratio.

CONCLUSION

Inactivated Cp induces decreased EVT invasion and a proinflammatory response; these effects were abrogated by pretreatment with low-dose ASA. Our results suggest an association between Cp infection, trophoblast dysfunction, and preeclampsia.

Pathogen interactions with endothelial cells and the induction of innate and adaptive immunity

There are over 10 trillion endothelial cells (EC) that line the vasculature of the human body. These cells not only have specialized functions in the maintenance of homeostasis within the circulation and various tissues but they also have a major role in immune function. EC also represent an important replicative niche for a subset of viral, bacterial, and parasitic organisms that are present in the blood or lymph; however, there are major gaps in our knowledge regarding how pathogens interact with EC and how this influences disease outcome. In this article, we review the literature on EC-pathogen interactions and their role in innate and adaptive mechanisms of resistance to infection and highlight opportunities to address prominent knowledge gaps.

Non-diagnostic anti-C. burnetii phase I IgG titres: Should they be discarded in elderly patients?

BACKGROUND

High anti-Coxiella burnetii phase I IgG titres are associated with chronic Q fever; an infectious disease with high mortality. Prognostic significance of lower or medium IgG phase I titres remain uncertain. The aim of this study was to explore this issue in a high-risk population.

METHODS

Sero-epidemiological and prospective study of 456 hospitalised patients aged 65 and older (Burgos; Spain). Serum IgG antibody phase I and II were determined by immunofluorescence assay.

RESULTS

A lower or medium IgG phase I titres (<1:1024) was observed in 180 (39.4%) patients. Atherosclerotic cardiovascular disease was associated with these titres, but not the traditional risk factors of chronic Q fever (cardiac valve disease, and vascular grafts or valvular prosthesis) (adjusted OR 1.75, 95% CI 1.18-2.61). Lower or medium IgG phase I titres were also associated with decreased survival at 30 months follow-up in patients with atherosclerotic cardiovascular disease (but not in the total sample) after adjusting for others comorbidities: IgG phase I titres≥1:32 (HR 1.77; 95% CI 1.14 4-2.74), ≥1:64 (HR 1.90; 95% CI 1.21-2.99)-3.25), and ≥1:128 (HR 2.00; 95% CI 1.23-3.25).

CONCLUSION

Lower or medium IgG phase I titres against C. burnetii, even the lowest, should not be discarded in elderly patients with atherosclerotic cardiovascular disease. Serological follow-up should be recommended in this group of patients.

Labor prediction based on the expression patterns of multiple genes related to cervical maturation in human term pregnancy

PROBLEM

This study explored the possibility of evaluating cervical maturation using swabbed cervical cell samples at term pregnancy, and aimed to develop a novel approach to predict labor onset.

METHOD OF STUDY

Women with uncomplicated pregnancies (n=117 from 62 women at term pregnancy) were recruited. Messenger RNA expression levels of cervical cells for ten genes were quantified by qPCR. Principal component analysis (PCA) was conducted, and principal components that significantly contributed to the prediction of days to delivery were determined.

RESULTS

PCA demonstrated that 76% of the expression information from the ten genes can be represented by three principal components (PC1-3). By the multiple regression analysis, PC2 and Bishop score but not PC1 or PC3 were significant variables in the prediction of days to delivery.

CONCLUSION

These findings support the concurrent assessment of multiple gene activities in cervical cells as a promising approach to predict the initiation of labor.

An Unsettled Debate About the Potential Role of Infection in Pathogenesis of Atherosclerosis

Association of infection with atherosclerosis is by no means new. Several sero-epidemiological and pathologic studies as well as animal models have shown a link between infection and atherosclerosis. Exciting discoveries in recent times related to role of inter-individual genetic variation in modulating inflammatory response to infection have reignited the enthusiasm in proving a causal link between infection and atherosclerosis. The purpose of this article was to review and analyze the available evidence linking infection with atherosclerosis.

Productive and Penicillin-Stressed Chlamydia pecorum Infection Induces Nuclear Factor Kappa B Activation and Interleukin-6 Secretion In Vitro

Nuclear factor kappa B (NFκB) is an inflammatory transcription factor that plays an important role in the host immune response to infection. The potential for chlamydiae to activate NFκB has been an area of interest, however most work has focused on chlamydiae impacting human health. Given that inflammation characteristic of chlamydial infection may be associated with severe disease outcomes or contribute to poor overall fitness in farmed animals, we evaluated the ability of porcine chlamydiae to induce NFκB activation in vitro. C. pecorum infection induced both NFκB nuclear translocation and activation at 2 hours post infection (hpi), an effect strongly enhanced by suppression of host de novo protein synthesis. C. suis and C. trachomatis showed less capacity for NFκB activation compared to C. pecorum, suggesting a species-specific variation in NFκB activation. At 24 hpi, C. pecorum induced significant NFκB activation, an effect not abolished by penicillin (beta lactam)-induced chlamydial stress. C. pecorum-dependent secretion of interleukin 6 was also detected in the culture supernatant of infected cells at 24 hpi, and this effect, too, was unchanged by penicillin-induced chlamydial stress. Taken together, these results suggest that NFκB participates in the early inflammatory response to C. pecorum and that stressed chlamydiae can promote inflammation.

Chlamydia pneumoniae Infection and Inflammatory Diseases

Chlamydia pneumoniae, an obligate intracellular bacterial pathogen, has long been investigated as a potential developmental or exacerbating factor in various pathologies. Its unique lifestyle and ability to disseminate throughout the host while persisting in relative safety from the immune response has placed this obligate intracellular pathogen in the crosshairs as a potentially mitigating factor in chronic inflammatory diseases. Many animal model and human correlative studies have been performed to confirm or deny a role for C. pneumoniae infection in these disorders. In some cases, antibiotic clinical trials were conducted to prove a link between bacterial infections and atherosclerosis. In this review, we detail the latest information regarding the potential role that C. pneumoniae infection may have in chronic inflammatory diseases.

Helicobacter pylori infection and eye diseases: a systematic review

The connection between Helicobacter pylori (Hp) infection and eye diseases has been increasingly reported in the literature and in active research. The implication of this bacterium in chronic eye diseases, such as blepharitis, glaucoma, central serous chorioretinopathy and others, has been hypothesized. Although the mechanisms by which this association occurs are currently unknown, this review describes shared pathogenetic mechanisms in an attempt to identify a lowest common denominator between eye diseases and Hp infection. The aim of this review is to assess whether different studies could be compared and to establish whether or not Hp infection and Eye diseases share common pathogenetic aspects. In particular, it has been focused on oxidative damage as a possible link between these pathologies. Text word search in Medline from 1998 to July 2014. 152 studies were included in our review. Were taken into considerations only studies that related eye diseases more frequent and/or known. Likely oxidative stress plays a key role. All of the diseases studied seem to follow a common pattern that implicates a cellular response correlated with a sublethal dose of oxidative stress. These alterations seem to be shared by both Hp infections and ocular diseases and include the following: decline in mitochondrial function, increases in the rate of reactive oxygen species production, accumulation of mitochondrial DNA mutations, increases in the levels of oxidative damage to DNA, proteins and lipids, and decreases in the capacity to degrade oxidatively damaged proteins and other macromolecules. This cascade of events appears to repeat itself in different diseases, regardless of the identity of the affected tissue. The trabecular meshwork, conjunctiva, and retina can each show how oxidative stress may acts as a common disease effector as the Helicobacter infection spreads, supported by the increased oxidative damage and other inflammation.

Chlamydia pneumoniae negatively regulates ABCA1 expression via TLR2-Nuclear factor-kappa B and miR-33 pathways in THP-1 macrophage-derived foam cells

OBJECTIVES

ATP-binding cassette transporter A1 (ABCA1) is critical in exporting cholesterol from macrophages and plays a protective role in the development of atherosclerosis. This study was to determine the effects and potential mechanisms of Chlamydia pneumoniae (C. pneumoniae) on ABCA1 expression and cellular cholesterol efflux in THP-1 macrophage-derived foam cells.

METHODS AND RESULTS

C. pneumoniae significantly decreased the expression of ABCA1 and reduced cholesterol efflux. Furthermore, we found that C. pneumoniae suppressed ABCA1 expression via up-regulation of miR-33s. The inhibition of C. pneumoniae-induced NF-κB activation decreased miR-33s expression and enhanced ABCA1 expression. In addition, C. pneumoniae increased Toll-like receptor 2 (TLR2) expressions, inhibition of which by siRNA could also block NF-κB activation and miR-33s expression, and promot the expression of ABCA1.

CONCLUSION

Taken together, these results reveal that C. pneumoniae may negatively regulate ABCA1 expression via TLR2-NF-κB and miR-33 pathways in THP-1 macrophage-derived foam cells, which may provide new insights for understanding the effects of C. pneumoniae on the pathogenesis of atherosclerosis.

Association between Chlamydophila pneumoniae infection and risk of coronary heart disease for Japanese: the JPHC study

BACKGROUND

Chlamydophila pneumoniae infection is considered a risk factor for atherosclerosis and coronary heart disease in western countries. However, evidence of it being a risk for Japanese is very limited because of a lower risk of coronary heart disease than for western people. The aim of this study was to examine further the association between C. pneumoniae infection and risk of coronary heart disease in Japanese.

METHODS

We conducted a nested case-control study of 49,011 Japanese men and women who participated in The Japan Public Health Center (JPHC) study. By the end of 2004, 196 cases of coronary heart disease and 155 cases of myocardial infarction had been documented among the participants. Two controls were selected for each case. For these subjects, we examined the association between serum anti C. pneumoniae IgA and IgG on the one hand and risk of coronary heart disease on the other.

RESULTS

Concentration of C. pneumoniae IgA antibody was positively associated with risk of coronary heart disease and more specifically myocardial infarction. Subjects with the highest quartile of IgA antibody showed 2.29 (95%CI, 1.21-4.33) times higher risk of coronary heart disease and 2.58 (95%CI, 1.29-5.19) times higher risk of myocardial infarction than those with lowest quartile. However, no such association was detected for IgG antibody.

CONCLUSION

C. pneumoniae infection was found to be positively associated with risk of coronary heart disease.

Chlamydia pneumoniae infection induces vascular smooth muscle cell migration via Rac1 activation

Chlamydia pneumoniae infection has been shown to be associated with the development of atherosclerosis by promoting the migration of vascular smooth muscle cells (VSMCs). However, how C. pneumoniae infection induces VSMC migration is not fully understood. A primary role of Ras-related C3 botulinum toxin substrate 1 (Rac1) is to generate a protrusive force at the leading edge that contributes to cell migration. Whether Rac1 activation plays a role in C. pneumoniae infection-induced VSMC migration is not well defined. In the present study, we therefore examined Rac1 activation in C. pneumoniae-infected rat primary VSMCs and the role of Rac1 activation in C. pneumoniae infection-induced VSMC migration. Glutathione S-transferase pull-down assay results showed that Rac1 was activated in C. pneumoniae-infected rat primary VSMCs. A Rac1 inhibitor, NSC23766 (50 µM,) suppressed Rac1 activation stimulated by C. pneumoniae infection, and thereby inhibited C. pneumoniae infection-induced VSMC migration. In addition, C. pneumoniae infection-induced Rac1 activation in the VSMCs was blocked by LY294002 (25 µM), an inhibitor of phosphatidylinositol 3-kinase (PI3K). Taken together, these data suggest that C. pneumoniae infection promotes VSMC migration, possibly through activating Rac1 via PI3K.

Thioredoxin-1 attenuates early graft loss after intraportal islet transplantation in mice

AIMS

Recent studies suggest that decreasing oxidative stress is crucial to achieve successful islet transplantation. Thioredoxin-1 (TRX), which is a multifunctional redox-active protein, has been reported to suppress oxidative stress. Furthermore, it also has anti-inflammatory and anti-apoptotic effects. In this study, we investigated the effects of TRX on early graft loss after islet transplantation.

METHODS

Intraportal islet transplantation was performed for two groups of streptozotocin-induced diabetic mice: a control and a TRX group. In addition, TRX-transgenic (Tg) mice were alternately used as islet donors or recipients.

RESULTS

The changes in blood glucose levels were significantly lower in the TRX group compared with the TRX-Tg donor and control groups (p<0.01). Glucose tolerance and the residual graft mass were considerably better in the TRX group. TRX significantly suppressed the serum levels of interleukin-1β (p<0.05), although neither anti-apoptotic nor anti-chemotactic effects were observed. Notably, no increase in the 8-hydroxy-2'-deoxyguanosine level was observed after islet infusion, irrespective of TRX administration.

CONCLUSIONS

The present study demonstrates that overexpression of TRX on the islet grafts is not sufficient to improve engraftment. In contrast, TRX administration to the recipients exerts protective effects on transplanted islet grafts by suppressing the serum levels of interleukin-1β. However, TRX alone appears to be insufficient to completely prevent early graft loss after islet transplantation. We therefore propose that a combination of TRX and other anti-inflammatory treatments represents a promising regimen for improving the efficacy of islet transplantation.

Chlamydia pneumoniae infection in atherosclerotic lesion development through oxidative stress: a brief overview

Chlamydia pneumoniae, an obligate intracellular pathogen, is known as a leading cause of respiratory tract infections and, in the last two decades, has been widely associated with atherosclerosis by seroepidemiological studies, and direct detection of the microorganism within atheroma. C. pneumoniae is presumed to play a role in atherosclerosis for its ability to disseminate via peripheral blood mononuclear cells, to replicate and persist within vascular cells, and for its pro-inflammatory and angiogenic effects. Once inside the vascular tissue, C. pneumoniae infection has been shown to induce the production of reactive oxygen species in all the cells involved in atherosclerotic process such as macrophages, platelets, endothelial cells, and vascular smooth muscle cells, leading to oxidative stress. The aim of this review is to summarize the data linking C. pneumoniae-induced oxidative stress to atherosclerotic lesion development.

Atherosclerosis Induced by Chlamydophila pneumoniae: A Controversial Theory

More than a century ago, inflammation and infection were considered to have atherogenic effects. The old idea that coronary heart disease (CHD) possibly has an infectious etiology has only reemerged in recent years. Atherosclerosis is the main pathological process involved in CHD and is, logically, the first place to look for infectious etiology. The process of atherosclerosis itself provides the first hints of potential infectious cause. Smooth muscle proliferation, with subsequent intimal thickening, luminal narrowing, and endothelial degeneration, constitutes the natural history of atherosclerosis, being with the severity and speed of these changes. Both viral and bacterial pathogens have been proposed to be associated with the inflammatory changes found in atherosclerosis. Recently, Chlamydophila pneumoniae (C. pneumoniae) has been implicated as a possible etiologic agent of coronary artery disease and atherosclerosis. New evidence which supports a role for C. pneumoniae in the pathogenesis of atherosclerosis has emerged. C. pneumoniae has been detected in atherosclerotic arteries by several techniques, and the organism has been isolated from both coronary and carotid atheromas. Recent animal models have suggested that C. pneumoniae is capable of inducing atherosclerosis in both rabbit and mouse models of atherosclerosis. Furthermore, human clinical treatment studies which examined the use of antichlamydial macrolide antibiotics in patients with coronary atherosclerosis have been carried out. The causal relationship has not yet been proven, but ongoing large intervention trials and research on pathogenetic mechanisms may lead to the use of antimicrobial agents in the treatment of CHD in the future.

Atherosclerosis and infection: is the jury still not in?

Atherosclerosis is a chronic inflammatory process accounting for increased cardiovascular and cerebrovascular morbidity and mortality. A wealth of recent data has implicated several infectious agents, mainly Chlamydophila pneumoniae, Helicobacter pylori, CMV and periodontal pathogens, in atherosclerosis. Thus, we sought to comprehensively review the available data on the topic, exploring in particular the pathogenetic mechanisms, and discuss anticipated future directions.

Transcription factor complex AP-1 mediates inflammation initiated by Chlamydia pneumoniae infection

Chlamydia pneumoniae is responsible for a high prevalence of respiratory infections worldwide and has been implicated in atherosclerosis. Inflammation is regulated by transcription factor (TF) networks. Yet, the core TF network triggered by chlamydiae remains largely unknown. Primary human coronary artery endothelial cells were mock-infected or infected with C. pneumoniae to generate human transcriptome data throughout the chlamydial developmental cycle. Using systems network analysis, the predominant TF network involved receptor, binding and adhesion and immune response complexes. Cells transfected with interfering RNA against activator protein-1 (AP-1) members FOS, FOSB, JUN and JUNB had significantly decreased expression and protein levels of inflammatory mediators interleukin (IL)6, IL8, CD38 and tumour necrosis factor compared with controls. These mediators have been shown to be associated with C. pneumoniae disease. Expression of AP-1 components was regulated by MAPK3K8, a MAPK pathway component. Additionally, knock-down of JUN and FOS showed significantly decreased expression of Toll-like receptor (TLR)3 during infection, implicating JUN and FOS in TLR3 regulation. TLR3 stimulation led to elevated IL8. These findings suggest that C. pneumoniae initiates signalling via TLR3 and MAPK that activate AP-1, a known immune activator in other bacteria not previously shown for chlamydiae, triggering inflammation linked to C. pneumoniae disease.

Airway bacterial colonization: the missing link between COPD and cardiovascular events?

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death worldwide and, according to the World Health Organization, its prevalence will double by 2020. COPD is a chronic inflammatory disease of the lung characterized by poorly reversible airflow limitation and, frequently, by extrapulmonary manifestations. In particular, the cardiovascular manifestations are responsible for high morbidity and mortality.

METHODS AND RESULTS

A systematic literature search was performed of studies published in Medline until December 2010, using the key-words: COPD, bacterial colonization, COPD exacerbation, atherosclerosis, systemic inflammation, cardiovascular event and risk factors. In addition to the studies identified in the primary search, reference lists of included articles were analyzed for additional papers related to the topic. The pathogenetic mechanisms underlying atherosclerosis - namely inflammation, oxidative stress and endothelial dysfunction - are in common with COPD. Moreover, they are increased in the presence of COPD, especially in patients who present airway bacterial colonization, increased rate of exacerbations and elevated levels of both airway and systemic inflammation.

CONCLUSION

COPD is associated with an increased burden of atherosclerotic disease. Systemic inflammation and oxidative stress play key roles in this association. COPD patients with airway bacterial colonization, as compared to patients without airway colonization, generally present more frequent exacerbations and higher levels of both airway and systemic inflammation. This COPD subgroup should be considered at particularly increased risk of developing cardiovascular complications and receive more attention concerning diagnosis, treatment, prevention and research.

The treatment of traumatic brain injury with velcade

Traumatic brain injury (TBI) elicits a strong inflammatory response that contributes to the acute pathological processes seen following TBI, including cerebral edema and disruption of the blood-brain barrier (BBB), in addition to longer-term neurological damage and cognitive impairment. Proteasome inhibitors reduce vascular thrombotic and inflammatory events and consequently protect vascular function. In the present study we evaluated the neuroprotective effect of Velcade (bortezomib), a potent and selective inhibitor of proteasomes, which is in clinical use for the treatment of multiple myeloma. When administered within 2 h after TBI onset, Velcade reduced inflammatory responses, lesion volume, and neurological functional deficits, and enhanced neuronal survival. Western blot and ELISA showed that Velcade decreased the expression of NF-κB. These results suggest that in the experimental setting, Velcade is an effective neuroprotective agent for the treatment of TBI.

Association of Chlamydia pneumoniae serology and ischemic stroke

BACKGROUND

Stroke is one of the major causes of morbidity and mortality throughout the world. Reports about the role of Chlamydia pneumoniae infection in the development of atherosclerosis have been reported in many studies. The aim of the study was to evaluate the association between Chlamydia pneumoniae infection and ischemic stroke.

METHODS

We evaluated 50 patients with ischemic stroke (32 males and 18 females) and 40 control subjects (22 males and 18 females). They were age- and sex-matched. All enrolled subjects underwent an enzyme-linked immunosorbent assay (ELISA) serologic test for IgG and IgA antibodies for Chlamydia pneumoniae.

RESULTS

Eighteen (36%) patients with ischemic stroke have positive IgA, in comparison with 6 (15%) among the control group (OR 3.18; CI 1.12-9.04; P = 0.03). This translates into the fact that there was a more than three-fold risk of developing ischemic stroke in those with Chlamydia pneumoniae infection compared to those who without. The IgG seropositivity was increased in patients with ischemic stroke, but it did not reach statistical significance (OR = 2.32; CI = 0.97-5.58; P = 0.078).

CONCLUSIONS

Chronic Chlamydia pneumoniae infection demonstrated by positive IgA-type antibody can be considered a significant risk for ischemic stroke.

The Differential Effect of Toxoplasma Gondii Infection on the Stability of BCL2-Family Members Involves Multiple Activities

The regulation of mitochondrial permeability, a key event in the initiation of apoptosis is governed by the opposing actions of the pro- and anti-apoptotic members of the BCL2-family of proteins. The BCL2-family can be classified further based on the number of BCL-homology (BH) domains they encode. Pathogen mediated modulation of BCL2-family members play a significant role in their ability to affect the apoptotic pathways in the infected host cell. The protozoan parasite Toxoplasma gondii establishes a profound blockade of apoptosis noted by a requirement for host NFκB activity and correlating with the selective degradation of pro-apoptotic BCL2-family members. In this study, we explore the potential activities associated with the inherent stability of the anti-apoptotic BCL2 as well as the selective degradation of the pro-apoptotic proteins BAX, BAD, and BID. We find that multiple activities govern the relative stability of BCL2-family members suggesting a complex and balanced network of stability-enhancing and–destabilizing activities are perturbed by parasite infection. The data leave open the possibility for both parasite induced host activities as well as the direct consequence of parasite effectors in governing the relative levels of BCL2-proteins in the course of infection.

Chlamydophila pneumoniae infection in patients undergoing carotid artery stent

Although several reports have correlated Chlamydophila pneumoniae (CP) infection with carotid endarterectomy and coronary stent, no data have been reported on the potential relationship between this pathogen and carotid artery stenting (CAS). Hence, we evaluated 47 subjects, 27 symptomatic and 20 asymptomatic, before CAS intervention and during the follow up, for the presence of CP DNA and anti-CP antibodies, including chlamydial HSP60 (Cp-HSP60). Before stent placement, CP DNA was detected exclusively in symptomatic patients, all of whom were also positive for CP IgG and IgA and 85.7 percent of them also had CP-HSP60 antibodies. At the follow-up, all CP DNA positive and 11 out of the 13 symptomatic patients with Cp-HSP60 antibodies became negatives. In contrast, no change was observed for CP- IgA antibodies. Despite the small number of patients, the present study advocates an important role of CP infection in symptomatic patients with carotid artery disease. Our findings also suggest that stent placement and/or therapy might have a role in favouring resolution of inflammation, though not affecting persistence of CP infection.

Hydrodynamic regulation of monocyte inflammatory response to an intracellular pathogen

Systemic bacterial infections elicit inflammatory response that promotes acute or chronic complications such as sepsis, arthritis or atherosclerosis. Of interest, cells in circulation experience hydrodynamic shear forces, which have been shown to be a potent regulator of cellular function in the vasculature and play an important role in maintaining tissue homeostasis. In this study, we have examined the effect of shear forces due to blood flow in modulating the inflammatory response of cells to infection. Using an in vitro model, we analyzed the effects of physiological levels of shear stress on the inflammatory response of monocytes infected with chlamydia, an intracellular pathogen which causes bronchitis and is implicated in the development of atherosclerosis. We found that chlamydial infection alters the morphology of monocytes and trigger the release of pro-inflammatory cytokines TNF-α, IL-8, IL-1β and IL-6. We also found that the exposure of chlamydia-infected monocytes to short durations of arterial shear stress significantly enhances the secretion of cytokines in a time-dependent manner and the expression of surface adhesion molecule ICAM-1. As a functional consequence, infection and shear stress increased monocyte adhesion to endothelial cells under flow and in the activation and aggregation of platelets. Overall, our study demonstrates that shear stress enhances the inflammatory response of monocytes to infection, suggesting that mechanical forces may contribute to disease pathophysiology. These results provide a novel perspective on our understanding of systemic infection and inflammation.

Possibilities for therapeutic interventions in disrupting Chlamydophila pneumoniae involvement in atherosclerosis

Strong sero-epidemiologic, pathologic, and experimental evidence suggests that Chlamydophila pneumoniae (Cpn) infection may play a causative role in the development of atherosclerosis. Cpn is an obligate intracellular gram-negative bacterium that is responsible for 10% of cases of community-acquired pneumonia. In addition to its presence in the respiratory tract, live Cpn has been found within atherosclerotic plaques. Experimental findings have established Cpn's ability to infect vascular cells and elicit important atherogenic responses. Furthermore, Cpn infection can promote atherosclerotic development in different animal models. To date however, large-scale antibiotic clinical trials have not been effective in preventing major cardiovascular events. It is becoming apparent that Cpn undergoes a persistent state of infection, which is refractory to current chlamydial antibiotics. New treatment strategies that are effective toward acute and persistent forms of Cpn infection are needed in order to effectively eradicate the bacterium within the vascular wall. Possible therapeutics targets include Cpn-specific proteins and machinery directly involved in their survival, replication and maintenance. Alternatively, selectively targeting host cell pathways and machinery required for Cpn's actions in vascular cells also represent potential treatment strategies for atherosclerosis.

Essential role of mitochondrial antiviral signaling, IFN regulatory factor (IRF)3, and IRF7 in Chlamydophila pneumoniae-mediated IFN-beta response and control of bacterial replication in human endothelial cells

Chlamydophila pneumoniae infection of the vascular wall as well as activation of the transcription factor IFN regulatory factor (IRF)3 have been linked to development of chronic vascular lesions and atherosclerosis. The innate immune system detects invading pathogens by use of pattern recognition receptors, some of which are able to stimulate IRF3/7 activation and subsequent type I IFN production (e. g., IFN-beta). In this study, we show that infection of human endothelial cells with C. pneumoniae-induced production of IFN-beta, a cytokine that so far has been mainly associated with antiviral immunity. Moreover, C. pneumoniae infection led to IRF3 and IRF7 nuclear translocation in HUVECs and RNA interference experiments showed that IRF3 and IRF7 as well as the mitochondrial antiviral signaling (MAVS) were essential for IFN-beta induction. Finally, C. pneumoniae replication was enhanced in endothelial cells in which IRF3, IRF7, or MAVS expression was inhibited by small interfering RNA and attenuated by IFN-beta treatment. In conclusion, C. pneumoniae infection of endothelial cells activates an MAVS-, IRF3-, and IRF7-dependent signaling, which controls bacterial growth and might modulate development of vascular lesions.

Chlamydophila pneumoniae enhances secretion of VEGF, TGF-beta and TIMP-1 from human bronchial epithelial cells under Th2 dominant microenvironment

Purpose

Chlamydophila pneumoniae infection in the airways is thought to be associated with the pathogenesis of asthma, especially in non-atopic severe asthma with irreversible airway obstruction that may be related to airway remodeling. Here, we investigated whether C. pneumoniae infection enhances the secretion of critical chemical mediators for airway remodeling, such as VEGF, TGF-β, and TIMP-1, in human bronchial epithelial cells (BECs) in a Th2-dominant microenvironment.

Methods

Human bronchial epithelial cells (BEAS-2B cells) were infected with C. pneumoniae strain TW183 and cultured in both a Th1-dominant microenvironment with INF-γ and a Th2-dominant microenvironment with IL-4 or IL-13 added to the culture medium. The VEGF, TGF-β, and TIMP-1 levels in the culture supernatants were measured using enzyme-linked immunosorbent assays (ELISA). The activation of NF-κB in each experimental condition was determined using an electrophoretic mobility shift assay.

Results

Chlamydophila pneumoniae-infected BECs showed enhanced secretion of VEGF, TGF-β, and TIMP-1 compared with non-infected BECs. The levels of cytokines secreted from BECs were increased more when IL-13 was added to the culture medium. C. pneumoniae-infected BECs also showed increased NF-κB activation.

Conclusions

These results suggest that C. pneumoniae plays a role in the pathogenesis of airway remodeling in asthma, revealing a Th2-dominant immune response. Further studies are required to clarify the precise mechanism of C. pneumoniae infection in airway remodeling.

Role for nuclear factor-kappaB in augmented lung injury because of interaction between hyperoxia and high stretch ventilation

High-tidal-volume mechanical ventilation and hyperoxia used in patients with acute lung injury (ALI) can induce alveolar coagulopathy and fibrin depositions within the airways. Hyperoxia has been shown to increase ventilator-induced lung injury (VILI), but the mechanisms that regulate interaction between high-tidal-volume mechanical ventilation and hyperoxia are unclear. We hypothesized that mechanical stretch with hyperoxia synergistically augmented neutrophil infiltration and production of plasminogen activator inhibitor-1 (PAI-1) via the nuclear factor-kappaB (NF-kappaB) pathway. C57BL/6 mice (n=5 per group) were exposed to high-tidal-volume (30 mL/kg) or low-tidal-volume (6 mL/kg) mechanical ventilation with room air or hyperoxia for 1 to 5h after 2-microg/g NF-kappaB inhibitor (SN-50) administration. Nonventilated mice with room air or hyperoxia served as control groups. Evans blue dye, myeloperoxidase, electrophoretic mobility shifting of nuclear protein, and inflammatory cytokine were measured. The expression of tumor necrosis factor-alpha (TNF-alpha) and PAI-1 were studied by immunohistochemistry. The addition of hyperoxia to high-tidal-volume ventilation-augmented lung injury, as demonstrated by increased microvascular leak, neutrophil migration into the lung, TNF-alpha and active PAI-1 production, DNA binding activity of NF-kappaB, and NF-kappaB activation. No statistically significant increase of neutrophil infiltration and inflammatory cytokine production was found in the mice ventilated at 6 mL/kg using hyperoxia. Hyperoxia-induced augmentation of VILI was attenuated in mice with pharmacologic inhibition of NF-kappaB activity by SN-50. We conclude that hyperoxia increased high-tidal-volume-induced cytokine production and neutrophil influx through activation of the NF-kappaB pathway.

Molecular pathogenesis of chronic Chlamydia pneumoniae infection: a brief overview

Owing to its unique host cell-dependent development cycle, Chlamydia pneumoniae occupies an intracellular niche that enables the bacterium to survive and to multiply, secluded from both the extracellular and the cytoplasmic environments. Within its separate chlamydial inclusion, it is able to genetically switch between a replicative and a persisting non-replicative state, linking the pathogen to acute as well as chronic diseases. Although its role in acute respiratory infection has been established, a potential link between chronic vascular infection with C. pneumoniae and the development of atherosclerosis remains enigmatic, in particular because chronic chlamydial infection cannot be eradicated by antibiotics. C. pneumoniae has developed numerous mechanisms to establish an adequate growth milieu involving the type III secretion-mediated release of chlamydial effector proteins that interact with cellular structures and reprogram host cell regulatory pathways. This brief overview of these pathomechanisms focuses on chronic vascular infection.

New perspectives of infections in cardiovascular disease

Infections have been recognized as significant causes of cardiac diseases for many decades. Various microorganisms have been implicated in the etiology of these diseases involving all classes of microbial agents. All components of the heart structure can be affected by infectious agents, i.e. pericardium, myocardium, endocardium, valves, autonomic nervous system, and some evidence of coronary arteries. A new breed of infections have evolved over the past three decades involving cardiac implants and this group of cardiac infectious complications will likely continue to increase in the future, as more mechanical devices are implanted in the growing ageing population. This article will review the progress made in the past decade on understanding the pathobiology of these infectious complications of the heart, through advances in genomics and proteomics, as well as potential novel approach for therapy.An up-to-date, state-of-the-art review and controversies will be outlined for the following conditions: (i) perimyocarditis; (ii) infective endocarditis; (iii) cardiac device infections; (iv) coronary artery disease and potential role of infections.

Expression of chemokines and adhesion molecules in human coronary artery endothelial cells infected with Chlamydia (Chlamydophila) pneumoniae

Chlamydia pneumoniae has during recent years been associated with cardiovascular disease and atherosclerosis. Chemokines, leukocyte adhesion proteins and metalloproteinases are significant for chemotaxis and attachment of leukocytes to vessel walls, and for stability of atherosclerotic plaques. To determine the ability of C. pneumoniae to elicit inflammation in a relevant target host cell, we infected human coronary artery endothelial cells (HCAEC) with a clinical isolate of C. pneumoniae. Extracellular release of five chemokines, two adhesion proteins and a metalloproteinase was measured at different time points after infection using a cytometric bead assay and ELISA. Secretion of IL-8, MCP-1, MIG, IP-10 and ICAM-1 was significantly increased 48 h after C. pneumoniae infection of HCAEC in comparison with uninfected controls. Release of RANTES occurred already 6 h after infection. C. pneumoniae did not elicit release of E-selectin or MMP-1. We conclude that C. pneumoniae induces expression of proinflammatory components in HCAEC, which would promote migration of leukocytes towards endothelial cells. This suggests that C. pneumoniae initiates and propagates vascular inflammation in ways that contribute to coronary artery disease.

Intracellular signaling pathways involved in inhibition of PAI-1 expression by CNP in endothelial cells

PAI-1 is a multifunctional protein stimulated by infectious agents and its activation is mediated by inflammatory cytokines such as TNFalpha. Recent studies demonstrate that natriuretic peptides, particularly C-type (CNP), can affect PAI-1 expression in bovine aortic smooth muscle cells and rat aortic endothelial cells. We have previously shown that CNP inhibits both basal and TNFalpha induced expression of PAI-1 in human endothelial cells. Herein, we describe mechanism by which CNP modulates signaling engaged in controlling PAI-1 expression in human endothelial cells. To examine which pathway initiated by TNFalpha is influenced, we tested kinase activity of MAP, PI3K/AKT and involvement of cGMP in endothelial cells exposed to CNP. CNP significantly increased cGMP level in endothelial cells. Its analogue, 8-Br-cGMP alone had no effect but significantly inhibited TNFalpha induced expression of PAI-1. Similarly, CNP and the inhibitors of ERK1/2 (PD098059) and PI3K (LY294002) attenuated PAI-1 expression induced by TNFalpha. CNP almost abolished TNFalpha induced phosphorylation of ERK1/2 but did not affect JNK phosphorylation, indicating that its effect on ERK1/2 was specific. These data suggest that CNP might function as the natural defense of vascular wall against cytokine induced PAI-1 release through its ability to inactivate PI3K/AKT and MEK/ERK pathways.

Assessment of subclinical atherosclerosis and cardiovascular risk

Conventional cardiac risk factors do not fully explain the incidence of coronary artery disease and coronary events. Risk stratification and therapy based solely on these conventional risk factors may exclude a population who would otherwise benefit from lifestyle and risk factor modification. Recent efforts to improve our ability to recognize individuals and populations at increased risk of coronary events have focused on the noninvasive imaging of atherosclerosis, both in coronary and extracoronary arterial beds, or the identification of "non-traditional" serum markers. We review the complimentary role of these newer methods of risk stratification in the context of conventional risk factor evaluation.

Differential induction of MyD88- and TRIF-dependent pathways in equine monocytes by Toll-like receptor agonists

Our understanding of the innate immune response in the horse has been limited by a lack of definitive data concerning cell signaling in response to microbial products. Toll-like receptors (TLRs) recognize conserved molecular motifs of microbes and elicit immune responses through their coupling with intracellular adaptor molecules, particularly MyD88 and TRIF. To provide a more definitive characterization of TLR signaling in the horse, the objectives of this study were to: (1) characterize the responses of equine monocytes to TLR ligands that signal through MyD88, TRIF or both in other species, and (2) determine the profiles of gene expression initiated utilizing these adaptor molecules. Monocytes were used to establish concentration response curves for Escherichia coli lipopolysaccharide (LPS; TLR4 ligand) and N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-[R]-cysteinyl-[S]-seryl-[S]-lysyl-[S]-lysyl-[S]-lysyl-[S]-lysine x 3 HCl (Pam(3)CSK(4); TLR2 ligand) based on expression of procoagulant activity (PCA) and production of tumor necrosis factor-alpha (TNF-alpha); effects of polyinosine-polycytidylic acid (Poly I:C; TLR3 ligand) were determined by quantifying expression of mRNA for interferon-beta (IFN-ss). Expression of genes associated with the MyD88- (TNF-alpha, IL-1ss, IL-6 and IL-10) and TRIF-dependent pathways (IFN-ss, IP-10, RANTES and TRAF1) were measured at intervals spanning 20 h. LPS and Pam(3)CSK(4) induced significantly higher expression of TNF-alpha, IL-1ss, and IL-10 than did Poly I:C. Poly I:C induced significantly higher expression of IFN-ss, IP-10 and RANTES than did either the TLR2 or TLR4 ligands. High concentrations of E. coli LPS did not significantly increase expression of genes associated with the TRIF-dependent pathway. The results of this study suggest that equine monocytes utilize a common intracellular pathway in response to TLR2 and TLR4 ligands, but a distinct pathway in response to TLR3 ligands.

Increased infiltration of Chlamydophila pneumoniae in the vessel wall of human veins after perfusion

BACKGROUND

Several studies have suggested an association between Chlamydophila pneumoniae (Cp) infection and atherosclerosis. A recent study detected Cp DNA in the saphenous vein of 12% of all patients before bypass grafting and in 38% of failed grafts. We used a system in which human veins were perfused with autologous blood under arterial pressure.

MATERIALS AND METHODS

Veins were surplus segments of saphenous veins of coronary artery bypass grafting (CABG) patients. Vein grafts were perfused with the blood of the same patient after CABG procedures. Veins were analysed for Cp-specific membrane protein using immunohistochemical and PCR analysis. Veins were analysed before and after perfusion (up to 4 h). The number of Cp positive cells was then quantified in the vein layers.

RESULTS

Cp protein was detected within macrophages only. In non-perfused veins, Cp was present in the adventitia in 91% of all patients, in the circular (64%) and longitudinal (23%) layer of the media. No positivity was found in the intima. Perfusion subsequently resulted in a significant increase of Cp positive cells within the circular layer of the media that, however, differed strongly between different patients. Cp DNA was not detected by PCR in those specimens.

CONCLUSION

Cp protein was present in 91% of veins, but the number of positive cells differed remarkably between patients. Perfusion of veins resulted in increased infiltration of Cp into the circular layer. These results may point to a putative discriminating role of Cp with respect to graft failure between different patients.

Selective cyclooxygenase inhibitors prevent the growth of Chlamydia pneumoniae in HL cells

The effects of the selective cyclooxygenase (COX) inhibitors SC-560 and PTPBS were studied in Chlamydia pneumoniae-infected HL cell cultures. Chlamydia pneumoniae growth and viability were assessed by quantifying inclusions and re-passages. COX-1 and COX-2 mRNA expression in HL cells during chlamydial infection was quantified with real-time polymerase chain reaction. SC-560 (10 microg/mL) and PTPBS (18 microg/mL) completely inhibited the growth of C. pneumoniae and the effect was dose-dependent between 4-9 microg/mL and 2-16 microg/mL, respectively. Inclusion size was reduced from 11.5+/-1.3 microm to 1.9+/-0.7 microm in the presence of the drugs. Removing the drugs returned the size to normal and increased the number of inclusions. Selective COX inhibitors appear to have a chlamydiostatic but not chlamydiacidic effect; they inhibit the growth of C. pneumoniae in vitro but do not prevent infection or eradicate C. pneumoniae from host cells.

Microbial risk factors of cardiovascular and cerebrovascular diseases: potential therapeutical options

Infection and inflammation may have a crucial role in the pathogenesis of atherosclerosis. This hypothesis is supported by an increasing number of reports on the interaction between chronic infection, inflammation, and atherogenesis. Assessment of serological and inflammatory markers of infection may be useful adjuncts in identifying those patients who are at a higher risk of developing vascular events, and in whom more aggressive treatments might be warranted.

The effect of Chlamydia pneumoniae on the expression of peroxisome proliferator-activated receptor-gamma in vascular smooth muscle cells

PURPOSE

This study was designed to investigate the change of peroxisome proliferator-activated receptor gamma (PPARgamma) after the infection of the human coronary artery smooth muscle cells (HCSMCs) with Chlamydia pneumoniae (C. pneumoniae) and the effect of PPARgamma agonist on the expression of PPARgamma of C. pneumoniae-infected HCSMCs.

MATERIALS AND METHODS

To determine the effect of PPARgamma agonist on the proliferation of C. pneumoniae-infected HCSMCs, rosiglitazone at various concentrations was applied 1 hour before inoculation of HCSMCs.

RESULTS

The expression of PPARgamma mRNA in HCSMCs increased from 3 hours after C. pneumoniae infection and reached that of noninfected HCSMCs at 24 hours (p<0.05). The expression of PPARgamma protein in HCSMCs also increased from 3 hours after C. pneumoniae and persisted until 24 hours as compared with that of noninfected HCSMCs (p<0.05). The pretreatment of HCSMCs with rosiglitazone followed by the infection with C. pneumoniae augmented the expression of PPARgamma mRNA and protein (p<0.05) and decreased cell proliferation.

CONCLUSION

Our results showed that the expression of PPARgamma increases in response to C. pneumoniae infection and rosiglitazone further augmented the expression of PPARgamma. It is suggested that rosiglitazone could ameliorate the chronic inflammation in the vessel wall induced by C. pneumoniae by augmenting PPARgamma expression.

Chlamydia pneumoniae GroEL1 protein is cell surface associated and required for infection of HEp-2 cells

Chlamydia pneumoniae is an important obligate intracellular pathogen that replicates within an inclusion in the eukaryotic cell. The initial event of a chlamydial infection is the adherence to and subsequent uptake of the infectious elementary bodies (EBs) by the human cell. These processes require yet-unidentified bacterial and eukaryotic surface proteins. The GroEL1 protein, which exhibits a very strong antigenicity and in vitro can activate various eukaryotic cells, is a potential pathogenicity factor. We localized the protein during the infection process and found it in the inclusion but outside the chlamydial particles. GroEL1 was also localized on the surface of EBs, and the protein could be washed off the EBs. Latex beads coated with recombinantly produced GroEL1 (rGroEL1) bound in a dose-dependent manner to HEp-2 cells. Likewise, GroEL1, when expressed and displayed on the yeast cell surface, mediated adhesion to HEp-2 cells. Interestingly, the homologous GroEL2 and GroEL3 proteins showed no adhesive properties. Incubation of primary umbilical vein endothelial cells with soluble GroEL1 and GroEL1-coated latex beads activated the translocation of the general transcription factor NF-kappaB into the nucleus. Finally, preincubation of HEp-2 cells with rGroEL1 significantly reduced subsequent infection with C. pneumoniae, although adhesion of infectious bacteria to eukaryotic cells was not affected. Taken together, these data support a role for extracellular GroEL1 in the establishment of the chlamydial infection.

Common community infections and the risk for coronary artery disease and acute myocardial infarction: evidence for chronic over-expression of tumor necrosis factor alpha and vascular cells adhesion molecule-1

BACKGROUND

Although several common community infections have been associated with the risk for coronary artery disease (CAD), their role in the development of acute myocardial infarction (AMI) is still unclear. We examined the prevalence of IgG and IgM (or IgA) antibodies against common infections such as HSV, Hepatitis A (HAV), Helicobacter pylori (HP), cytomegalovirus (CMV) and Chlamydia pneumoniae (CP), in CAD and AMI patients, and their relationship with pro-atherogenic inflammatory molecules.

METHODS

A total number of 337 subjects were included in this study: 150 patients with angiographically documented stable CAD, 138 patients admitted with AMI and 49 healthy individuals. Serum IgG and IgM against HAV, CMV and HSV, IgG against HP and IgG/IgA against CP were determined in all participants. Serum tumor necrosis factor alpha (TNF-alpha) and soluble vascular cells adhesion molecule (sVCAM-1), were determined by ELISA.

RESULTS

Patients with CAD were more likely to have anti-HAV IgG (94.4%), anti-HSV IgG (97.2%) and anti-HP IgG (55.1%) compared to healthy individuals (70.8%, 89.6% and 39.6% respectively, p<0.05 for all). In multivariate analysis, anti-HAV IgG was an independent predictor of CAD (beta(SE): 0.187(0.075), p=0.015). Among the CAD patients, the presence of anti-CP IgA was more frequent in those admitted with AMI (39%) compared to those with stable CAD (21%, p<0.05). Finally, both patients and controls had significantly higher levels of sVCAM-1 and TNF-alpha in the presence of anti-HAV IgG, compared to those without anti-HAV IgG (p<0.05 for all).

CONCLUSION

Past infections with HAV, HSV and HP are associated with higher risk for coronary atherosclerosis, while the presence of anti-HAV IgG is also associated with higher levels of TNF-alpha and sVCAM-1. Furthermore, the presence of recent infection by CP is associated with higher risk for AMI among CAD patients. These findings are important since they demonstrate that past HAV, HSV and HP infections may affect cardiovascular risk, while recent CP infection may be implicated in the triggering of AMI among CAD patients.

Chlamydophila pneumoniae induces a sustained airway hyperresponsiveness and inflammation in mice

Background

It has been reported that Chlamydophila (C.) pneumoniae is involved in the initiation and promotion of asthma and chronic obstructive pulmonary diseases (COPD). Surprisingly, the effect of C. pneumoniae on airway function has never been investigated.

Methods

In this study, mice were inoculated intranasally with C. pneumoniae (strain AR39) on day 0 and experiments were performed on day 2, 7, 14 and 21.

Results

We found that from day 7, C. pneumoniae infection causes both a sustained airway hyperresponsiveness and an inflammation. Interferon-γ (IFN-γ) and macrophage inflammatory chemokine-2 (MIP-2) levels in bronchoalveolar lavage (BAL)-fluid were increased on all experimental days with exception of day 7 where MIP-2 concentrations dropped to control levels. In contrast, tumor necrosis factor-α (TNF-α) levels were only increased on day 7. From day 7 to 21 epithelial damage and secretory cell hypertrophy was observed. It is suggested that, the inflammatory cells/mediators, the epithelial damage and secretory cell hypertrophy contribute to initiation of airway hyperresponsiveness.

Conclusion

Our study demonstrates for the first time that C. pneumoniae infection can modify bronchial responsiveness. This has clinical implications, since additional changes in airway responsiveness and inflammation-status induced by this bacterium may worsen and/or provoke breathlessness in asthma and COPD.

Correlation of hyperhomocysteinaemia and Chlamydia pneumoniae IgG seropositivity with coronary artery disease in a general population

BACKGROUND

Both Chlamydia pneumoniae infection and hyperhomocysteinaemia have been assumed to increase the atherosclerotic risk independently of each other and independently of the classic risk factors. The correlation between hyperhomocysteinaemia, C. pneumoniae infection and coronary artery disease (CAD) have not been investigated in the general population.

METHODS

In an ancillary study to the Persian Gulf Healthy Heart Study, a cohort study of men and women aged >or=25 years, a random sample of 1699 (48.9% males, 51.1% females) subjects were evaluated. Total homocysteine, high sensitivity C-reactive protein (CRP) and IgG antibodies to C. pneumoniae were determined by ELISA. Minnesota coding criteria of a 12-lead resting electrocardiogram was used for evaluation of CAD.

RESULTS

A total of 12.4% of the subjects had electrocardiogram-defined (Minnesota-coding criteria) coronary artery disease. Hyperhomocysteinaemia (>14 micromol/l) and IgG seropositivity were found in 50.8% and 37.7%, respectively. Neither of hyperhomocysteinaemia nor C. pneumoniae IgG seropositivity showed a significant association with CAD after adjusting of sex and age. Concurrent elevated CRP level (>8.2mg/l) and C. pneumoniae seropositivity (chronic C. pneumoniae infection) had a significant association with CAD [OR=1.73, CI (1.09-2.75); p=0.01] after adjusting for age, sex, systolic and diastolic blood pressures, BMI, and serum levels of LDL-cholesterol, fasting blood sugar and triglyceride as covariates in a logistic regression model. This odds ratio increased to 2.11, CI (1.18-4.12; p=0.02) when concurrent hyperhomocysteinaemia and chronic C. pneumoniae infection, as a single covariate entity; was adjusted for multiple risk factors in another logistic regression model.

CONCLUSION

Concurrent hyperhomocysteinaemia and chronic C. pneumoniae infection, as a single entity, was independently associated with coronary artery disease in the general population. This synergism may have important implications for risk-stratification and intervention trials.