Endothelial cells' activation and apoptosis induced by a subset of antibodies against human cytomegalovirus: relevance to the pathogenesis of atherosclerosis

Fatal attractions that trigger inflammation and drive atherosclerotic disease

BACKGROUND

Atherosclerosis is the salient, underlying cause of cardiovascular diseases, such as arrhythmia, coronary artery disease, cardiomyopathy, pulmonary embolism and myocardial infarction. In recent years, atherosclerosis pathophysiology has evolved from a lipid-based to an inflammation-centric ideology.

METHODS

This narrative review is comprised of review and original articles that were found through the PubMed search engine. The following search terms or amalgamation of terms were used: "cardiovascular disease," "atherosclerosis," "inflammation," "GRP78," "Hsp60," "oxidative low-density lipoproteins," "aldehyde dehydrogenase," "β2-glycoprotein," "lipoprotein lipase A," "human cytomegalovirus." "SARS-CoV-2," "chlamydia pneumonia," "autophagy," "thrombosis" and "therapeutics."

RESULTS

Emerging evidence supports the concept that atherosclerosis is associated with the interaction between cell surface expression of stress response chaperones, including GRP78 and Hsp60, and their respective autoantibodies. Moreover, various other autoantigens and their autoantibodies have displayed a compelling connection with the development of atherosclerosis, including oxidative low-density lipoproteins, aldehyde dehydrogenase, β2-glycoprotein and lipoprotein lipase A. Atherosclerosis progression is also concurrent with viral and bacterial activators of various diseases. This narrative review will focus on the contributions of human cytomegalovirus as well as SARS-CoV-2 and chlamydia pneumonia in atherosclerosis development. Notably, the interaction of an autoantigen with their respective autoantibodies or the presence of a foreign antigen can enhance inflammation development, which leads to atherosclerotic lesion progression.

CONCLUSION

We will highlight and discuss the complex role of the interaction between autoantigens and autoantibodies, and the presence of foreign antigens in the development of atherosclerotic lesions in relationship to pro-inflammatory responses.

CMV-encoded GPCRs in infection, disease, and pathogenesis

G protein coupled receptors (GPCRs) are seven-transmembrane domain proteins that modulate cellular processes in response to external stimuli. These receptors represent the largest family of membrane proteins, and in mammals, their signaling regulates important physiological functions, such as vision, taste, and olfaction. Many organisms, including yeast, slime molds, and viruses encode GPCRs. Cytomegaloviruses (CMVs) are large, betaherpesviruses, that encode viral GPCRs (vGPCRs). Human CMV (HCMV) encodes four vGPCRs, including UL33, UL78, US27, and US28. Each of these vGPCRs, as well as their rodent and primate orthologues, have been investigated for their contributions to viral infection and disease. Herein, we discuss how the CMV vGPCRs function during lytic and latent infection, as well as our understanding of how they impact viral pathogenesis.

UCHL1 deficiency upon HCMV infection induces vascular endothelial inflammatory injury mediated by mitochondrial iron overload

Human cytomeglovirus (HCMV) infection predisposes blood vessels to atherosclerosis (AS) and post-transplantation restenosis, but the underlying molecular basis remains elusive. Here, we found that HCMV infection activates AIM2 inflammasome and pyroptosis in vascular endothelial cells by inducing mitochondrial iron overload. Mechanistically, under normal conditions, ubiquitin carboxyl terminal hydrolase-L1 (UCHL1) was identified as a DUB enzyme that interacts with, deubiquitylates, and stabilizes ferredoxin reductase (FDXR), an important mitochondrial protein that regulates mitochondral iron homeostasis. However, HCMV infection induces the aberrantly elevated m6A modification and R-loops, the three-stranded DNA-DNA:RNA hybrid structures. The expression of UCHL1 was remarkably reduced by m6A modification-mediated mRNA decay and R-loop-dependent transcriptional termination after HCMV infection. Deficiency of UCHL1 causes ubiquitination and degradation of FDXR. Loss of FDXR induces the mitochondrial iron overload, which consequently leads to AIM2 inflammasome activation and endothelial injury. Moreover, both downregulation expression of UCHL1 and related inflammatory injury in vascular endothelium was observed in MCMV-infected mice. Notably, STM2457, a METTL3 specific inhibitor, restores the expression of UCHL1 upon HCMV infection, thereby inhibiting the inflammatory injury of vascular endothelial cells. Our findings delineate a novel mechnism involved in HCMV-induced inflammatory injury to vascular endothelium and implicate the role of METTL3 inhibitor as a potential therapeutic approach.

Human cytomegalovirus infection is associated with stroke in women: the US National Health and Nutrition Examination Survey 1999-2004

BACKGROUND

Increasing evidence indicated that infection factors play important roles in stroke development. Human cytomegalovirus (HCMV) infection was positively associated with atherosclerosis and hypertension which are stroke risk factors. Therefore, we aimed to explore the relationship between HCMV infection and stroke using the data of US National Health and Nutrition Examination Survey (NHANES).

METHODS

We analysed data on 2844 men and 3257 women in the NHANES 1999-2004. We included participants aged 20-49 years who had valid data on HCMV infection and stroke.

RESULTS

54.1% of participants had serological evidence of HCMV infection and 0.8% of them had a previous diagnosis of stroke. There were ethnic differences in the prevalence of HCMV seropositivity (p<0.001). There was no significant association between HCMV seropositivity and stroke in men in any of the models. In women, HCMV seropositivity was associated with stroke before adjustment (OR=3.45, 95% CI 1.09 to 10.95, p=0.036). After adjusting for race/ethnicity, the association remained significant (OR=4.40, 95% CI 1.37 to 14.09, p=0.014). After further adjustment for body mass index, diabetes, hypercholesterolaemia, hypertension, alcohol consumption, smoking and physical activity, the association still existed (OR=3.58, 95% CI 1.14 to 11.25, p=0.030). The association was significant consistently in adjusted model for age (OR=3.39, 95% CI 1.08 to 10.64, p=0.037).

CONCLUSIONS

We found a strong association between HCMV and stroke in women from the nationally representative population-based survey. This provide additional motivation for undertaking the difficult challenge to reduce the prevalence of stroke.

Apoptosis Disorder, a Key Pathogenesis of HCMV-Related Diseases

Human cytomegalovirus (HCMV) belongs to the β-herpesvirus family, which is transmitted in almost every part of the world and is carried by more than 90% of the general population. Increasing evidence indicates that HCMV infection triggers numerous diseases by disrupting the normal physiological activity of host cells, particularly apoptosis. Apoptosis disorder plays a key role in the initiation and development of multiple diseases. However, the relationship and molecular mechanism of HCMV-related diseases and apoptosis have not yet been systematically summarized. This review aims to summarize the role of apoptosis in HCMV-related diseases and provide an insight into the molecular mechanism of apoptosis induced by HCMV infection. We summarize the literature on HCMV-related diseases and suggest novel strategies for HCMV treatment by regulating apoptosis.

Novel Strategies to Combat CMV-Related Cardiovascular Disease

Cytomegalovirus (CMV), a ubiquitous human pathogen that is never cleared from the host, has long been thought to be relatively innocuous in immunocompetent adults, but causes severe complications including blindness, end-organ disease, and death in newborns and in immuno-compromised individuals, such as organ transplant recipients and those suffering from AIDS. Yet even in persons with intact immunity, CMV infection is associated with profound stimulation of immune and inflammatory pathways. Carriers of CMV infection also have an elevated risk of developing cardiovascular complications. In this review, we define the proposed mechanisms of how CMV contributes to cardiovascular disease (CVD), describe current approaches to target CMV, and discuss how these strategies may or may not alleviate cardiovascular complications in those with CMV infection. In addition, we discuss the special situation of CMV coinfection in people with HIV infection receiving antiretroviral therapy, and describe how these 2 viral infections may interact to potentiate CVD in this especially vulnerable population.

[Cardiovascular risk calculators for people living with human immunodeficiency virus]

The increasing access and efficacy of antiretroviral therapy has allowed people living with human immunodeficiency virus to achieve a life expectancy similar to that of the general population. However, this goal may be affected by the increased risk of cardiovascular disease in this group. This risk is multifactorial, involving the high prevalence of traditional risk factors, the development of a pro-inflammatory state related to chronic infection, and the use of antiretroviral drugs with an adverse metabolic profile. In daily practice, in order to estimate this risk and guide medical decision-making, different calculators are available. These are based on data from population cohorts, many of them from human immunodeficiency virusnegative subjects. The main aim of this review is to describe the epidemiology of cardiovascular disease in people living with human immunodeficiency virus, the available risk calculators and their use.

The role of human cytomegalovirus in atherosclerosis: a systematic review

Atherosclerosis is a progressive vascular disease with increasing morbidity and mortality year by year in modern society. Human cytomegalovirus (HCMV) infection is closely associated with the development of atherosclerosis. HCMV infection may accelerate graft atherosclerosis and the development of transplant vasculopathy in organ transplantation. However, our current understanding of HCMV-associated atherosclerosis remains limited and is mainly based on clinical observations. The underlying mechanism of the involvement of HCMV infection in atherogenesis remains unclear. Here, we summarized current knowledge regarding the multiple influences of HCMV on a diverse range of infected cells, including vascular endothelial cells, vascular smooth muscle cells, monocytes, macrophages, and T cells. In addition, we described potential HCMV-induced molecular mechanisms, such as oxidative stress, endoplasmic reticulum stress, autophagy, lipid metabolism, and miRNA regulation, which are involved in the development of HCMV-associated atherogenesis. Gaining an improved understanding of these mechanisms will facilitate the development of novel and effective therapeutic strategies for the treatment of HCMV-related cardiovascular disease.

Productive Cytomegalovirus Infection Is Associated With Impaired Endothelial Function in ST-Elevation Myocardial Infarction

BACKGROUND

An association between productive cytomegalovirus infection and atherosclerosis was shown recently in several trials, including a previous study of ours. However, the mechanism involved in this association is still under investigation. Here, we addressed the interaction between productive cytomegalovirus infection and endothelial function in patients with ST-elevation myocardial infarction (STEMI).

METHODS

We analyzed the presence of cytomegaloviral DNA in plasma and endothelial function in 33 patients with STEMI and 33 volunteers without cardiovascular diseases, using real-time polymerase chain reaction (PCR) and a noninvasive test of flow-mediated dilation.

RESULTS

Both the frequency of presence and the load of cytomegaloviral DNA were higher in plasma of patients with STEMI than those in controls. This difference was independent of other cardiovascular risk factors (7.38 [1.36-40.07]; P = 0.02). The results of the flow-mediated dilation test were lower in patients in STEMI than in controls (5.0% [2.65%-3.09%] vs 12. %5 [7.5%-15.15%]; P = 0.004) and correlated negatively with the cytomegaloviral DNA load (Spearman R = -0.407; P = 0.019) independently of other cardiovascular risk factors.

CONCLUSIONS

Productive cytomegalovirus infection in patients with STEMI correlated negatively with endothelial function independently of other cardiovascular risk factors. The impact of cytomegalovirus on endothelial function may explain the role of cytomegalovirus in cardiovascular prognosis.

A comprehensive analysis of antigen-specific antibody responses against human cytomegalovirus in patients with systemic sclerosis

Anti-human cytomegalovirus (HCMV) antibodies are considered triggers of systemic sclerosis (SSc), but such a hypothesis has been assessed in limited sub-dominant epitopes. Our aim was to systematically assess the potential association of HCMV antibodies targeting most immunodominant and subdominant viral antigens, as this would reveal immunopathogenic associations. Our study included 110 SSc patients, 60 multiple sclerosis (MS) patients, and 51 healthy controls (HC). Anti-HCMV abs were tested by immunoblotting. IgG anti-HCMV was broader in SSc and MS compared to HC. Anti- UL57 and UL55 were more frequent in SSc versus MS forms. Reactivity to multiple viral antigens was more frequent in SSc than MS forms. Anti-viral antibodies levels were higher in specific autoantibody-positive SSc patients compared to seronegative cases. In conclusion, more prevalent and/or stronger antigen-specific HCMV responses are noted in SSc compared to controls, implying a role of these viral responses in SSc development.

Zika Virus Transmission Through Blood Tissue Barriers

The recent Zika virus (ZIKV) epidemic in the Americas and the Caribbean revealed a new deadly strain of the mosquito-borne virus, which has never been associated with previous outbreaks in Asia. For the first time, widespread ZIKV infection was shown to cause microcephaly and death of newborns, which was most likely due to the mutation acquired during the large outbreak recorded in French Polynesia in 2013–2014. Productive ZIKV replication and persistence has been demonstrated in placenta and fetal brains. Possible association between ZIKV and microcephaly and fetal death has been confirmed using immunocompetent mouse models in vitro and in vivo. Having crossed the placenta, ZIKV directly targets neural progenitor cells (NPCs) in developing human fetus and triggers apoptosis. The embryonic endothelial cells are exceptionally susceptible to ZIKV infection, which causes cell death and tissue necrosis. On the contrary, ZIKV infection does not affect the adult brain microvascular cell morphology and blood–brain barrier function. ZIKV is transmitted primarily by Aedes mosquito bite and is introduced into the placenta/blood through replication at the site of the entry. Also, virus can be transmitted through unprotected sex. Although, multiple possible routes of virus infection have been identified, the exact mechanism(s) utilized by ZIKV to cross the placenta still remain largely unknown. In this review, the current understanding of ZIKV infection and transmission through the placental and brain barriers is summarized.

Cytomegalovirus Infection in Cardiovascular Diseases

Atherosclerosis underlies the development of many cardiovascular diseases that continue to hold a leading place among the causes of death in developed countries. The role of activated immune cells in atherosclerosis progression has been convincingly demonstrated, but the mechanism of their action remains poorly investigated. Since atherosclerosis is associated with chronic inflammatory response, involvement of viral and bacterial infections in atherogenesis has been examined. A special place among the infectious agents is held by human herpesviruses as the most common persistent viruses in human population coupled to chronic inflammation during atherosclerosis. We found that activation of cytomegalovirus (CMV, human herpesvirus 5) infection is associated with the emergence of acute coronary syndrome, which is in a good agreement with the data on productive CMV infection published elsewhere. In this review, we discuss the data obtained by us and other researchers regarding the role of cytomegalovirus infection and related potential mechanisms resulting in the expansion of atherosclerotic plaques during ischemic heart disease and stroke, including virus transfer to immune and endothelial cells via extracellular vesicles. In particular, the data presented in the review demonstrate that virus spreading in the vascular wall triggers immune system activation in atherosclerotic plaques and causes endothelial dysfunction. Moreover, productive CMV infection in patients with acute myocardial infarction correlates with the extent of endothelial dysfunction. The mechanisms described by us and other researchers may explain the role of CMV infection in atherosclerosis and development of ischemic heart disease.

Viral infection and atherosclerosis

Several risk factors have been described for the pathogenesis of atherosclerosis. Infectious diseases are suggested to be a causative factor, and some viruses have been studied for their relation with atherosclerotic diseases. Studies report two hypotheses, direct and indirect effects, for the role of viral infections in atherogenesis. Viruses are able to initiate atherosclerosis by two different pathways. They can exert their direct effects on atherogenesis by infecting vascular cells and then inducing inflammation in the endothelium and smooth muscle cells. Alternatively, they can also apply indirect effects by infecting non-vascular cells and inducing systemic inflammation. In this review, we consider the available data about the effects and correlations of DNA and RNA viruses on atherosclerosis.

Human cytomegalovirus infection and coronary heart disease: a systematic review

Background

Human cytomegalovirus (HCMV) infection is closely associated with coronary heart disease.

Main body of the abstract

In 1987, Adam et al. were the first to report an association between HCMV infection and atherosclerosis (AS), and later, many serum epidemiology and molecular biology studies showed that HCMV-infected endothelial cells play an important role in the development of AS. As patients with HCMV are generally susceptible to coronary heart disease, and with the increasing elderly population, a review of recent studies focusing on the relationships of HCMV infection and coronary heart disease is timely and necessary.

Short conclusion

The role of HCMV infection in the development of AS needs further study, since many remaining issues need to be explored and resolved. For example, whether HCMV promotes the development of coronary AS, and what the independent factors that lead to coronary artery AS by viral infection are. A comprehensive understanding of HCMV infection is needed in order to develop better strategies for preventing AS.

Human cytomegalovirus (HCMV) UL44 and UL57 specific antibody responses in anti-HCMV-positive patients with systemic sclerosis

The role of human cytomegalovirus (HCMV) has been postulated as a trigger of systemic sclerosis (SSc). The aim of the study was to assess the prevalence of antibodies against HCMV UL44 and UL57 antigens not tested in the past. Sixty SSc patients, 40 multiple sclerosis and 17 normal controls (NCs), all anti-HCMV positive, were tested by immunoblotting. Reactivity to HCMV antigens, expressed as arbitrary units (AUs), was assessed for correlation with clinical and immunological parameters, including types of SSc-related autoantibodies. Anti-UL44 and anti-UL57 HCMV antibodies were present in 3/60 (5%) and 58/60 (96.7%) SSc patients, respectively (p < 0.001). Anti-UL57 antibodies were present in 35/40 (87.5%) MS patients and 16/17 (94.1%) NCs (SSc vs MS, MS vs NC, p = ns). Strong (50-75 AU) and very strong (75-100 AU) anti-UL57 immunoreactivity was found in 24 (41.4%) and 22 (37.9%) SSc patients, respectively (p = ns). Dilution experiments showed anti-UL57 antibody persistence in up to 1/5000. Overall, there was no difference in the frequency or the magnitude of anti-UL57 immunoreactivity between diffuse cutaneous systemic sclerosis and limited cutaneous systemic sclerosis patients (96.67 vs 96.67%; 65.45 ± 20.19 vs 64.31 ± 21.11 AU, p > 0.05) but strong anti-UL57 reactivity were more frequent in SSc compared to NCs (p = 0.007). Anti-UL57 reactivity was not inhibited by SSc-specific autoantigens. Anti-UL57 seropositivity did not correlate with demographic, clinical or immunological features of SSc. Anti-HCMV UL57 antibodies are universally present in anti-HCMV-positive patients with SSc, while those against UL44 are rarely seen. Because anti-UL57 lack disease specificity and are not involved in cross-reactive responses, their immunopathogenetic potential is to be questioned.

Infectious and coronary artery disease

BACKGROUND

Atherosclerotic event is one of the most causes of death in the world. Coronary artery disease (CAD) is one manifestation of atherosclerosis. It is well-known that several risk factors, such as diabetes mellitus (DM), smoking, hypertension (HTN), have effects on it. It is proposed that infection can lead to atherosclerosis or even make its process faster. Here, we discuss about the effect of some of infectious agents on the atherosclerosis and CAD.

METHODS

In this study, first we did a comprehensive search in PubMed, Scopus, and Science Direct using some related keywords such as atherosclerosis, CAD, myocardial infarction (MI), infection, and name of viruses and bacteria. After finding the related papers, we reviewed the correlation between some microbial agents and risk of CAD.

RESULTS

Literature has reported several infectious agents (viruses, bacteria, and parasites) that can be associated with risk of CAD. This association for some of them like Helicobacter pylori (H. pylori), Chlamydia pneumonia (C. pneumoniae), and Cytomegalovirus (CMV) is a very strong. On the other hand, there are some other agents like influenza that still need to be more investigated through original studies. Furthermore, different mechanisms (general and special) have been reported for the association of each agent with CAD.

CONCLUSION

Based on the studies in databases and our literature review, it is so clear that some microbes and infectious agents can be involved in the process of atherosclerosis. Therefore, controlling each type of infections especially among people with a traditional risk factor for atherosclerosis should be taken into account for reducing the risk of CAD and atherosclerosis.

High Human Cytomegalovirus IgG Level is Associated with Increased Incidence of Diabetic Atherosclerosis in Type 2 Diabetes Mellitus Patients

Background

At present, whether human cytomegalovirus (HCMV) infection is associated with type 2 diabetes mellitus (T2DM) is debatable. The effect of active HCMV infection on glucose regulation has been poorly studied. Although HCMV infection is correlated with atherosclerosis in cardiovascular disease, the role of HCMV infection in the development of diabetic atherosclerosis in T2DM is unclear and is usually neglected by endocrinologists. The aim of this study was to assess the effects of HCMV infection on glucose regulation and the development of diabetic atherosclerosis in T2DM patients.

Material/Methods

A total of 222 hospitalized T2DM patients were enrolled. Nested polymerase chain reactions were used to detect HCMV DNA extracted from peripheral blood leukocytes. Quantitative real-time PCR was used to determine viral load. HCMV IgG antibody concentrations were analyzed by chemiluminescence immunoassay.

Results

HCMV active infection, viral load, and HCMV IgG titers were not correlated with glucose regulation. Binary logistic regression demonstrated that the highest quartile of HCMV IgG concentration (>500 U/ml) was correlated with the incidence of diabetic atherosclerosis (OR: 8.0, 95%CI: 2.3–27.2), and that titer >127U/ml of HCMV IgG is an independent predictor for the development of diabetic atherosclerosis in T2DM patients (OR: 4.6, 95%CI: 1.9–11.3) after adjustment for all potential confounding factors.

Conclusions

Active HCMV infection is unlikely to influence glucose regulation in T2DM. However, HCMV IgG titers are associated with the incidence of diabetic atherosclerosis, and titer >127U/ml of HCMV IgG might be an independent risk factor for the development of diabetic atherosclerosis in T2DM patients.

Gene expression profiling in peripheral blood mononuclear cells of patients with common variable immunodeficiency: modulation of adaptive immune response following intravenous immunoglobulin therapy

Background

Regular intravenous immunoglobulin treatment is used to replace antibody deficiency in primary immunodeficiency diseases; however the therapeutic effect seems to be related not only to antibody replacement but also to an active role in the modulation of the immune response. Common variable immunodeficiency is the most frequent primary immunodeficiency seen in clinical practice.

Methods

We have studied the effect of intravenous immunoglobulin replacement in patients with common variable immunodeficiency by evaluating the gene-expression profiles from Affimetrix HG-U133A. Some of the gene array results were validated by real time RT-PCR and by the measurement of circulating cytokines and chemokines by ELISA. Moreover we performed FACS analysis of blood mononuclear cells from the patients enrolled in the study.

Results

A series of genes involved in innate and acquired immune responses were markedly up- or down-modulated before therapy. Such genes included CD14, CD36, LEPR, IRF-5, RGS-1, CD38, TNFRSF25, IL-4, CXCR4, CCR3, IL-8. Most of these modulated genes showed an expression similar to that of normal controls after immunoglobulin replacement. Real time RT-PCR of selected genes and serum levels of IL-4, CXCR4 before and after therapy changed accordingly to gene array results. Interestingly, serum levels of IL-8 remained unchanged, as the corresponding gene, before and after treatment. FACS analysis showed a marked decrease of CD8+T cells and an increase of CD4+T cells following treatment. Moreover we observed a marked increase of CD23⁻CD27⁻IgM⁻IgG⁻ B cells (centrocytes).

Conclusions

Our results are in accordance with previous reports and provide further support to the hypothesis that the benefits of intravenous immunoglobulin therapy are not only related to antibody replacement but also to its ability to modulate the immune response in common variable immunodeficiency.

Synergistic interactions between heregulin and peroxisome proliferator-activated receptor-gamma (PPARgamma) agonist in breast cancer cells

Here, we demonstrate that troglitazone (Rezulin), a peroxisome proliferator-activated receptor agonist, acted in synergy with heregulin to induce massive cell death in breast cancer cells. Although the combination of heregulin and troglitazone (HRG/TGZ) induced both apoptosis and necrosis, the main mode of cell death was caspase-independent and occurred via necrosis. This combination increased generation of superoxide in mitochondria, which in turn destabilized mitochondria potential. Pretreatment with N-acetyl-l-cysteine and catalase expression ameliorated cell death induced by the combination treatment, indicating a role of oxidative stress in mediating HRG/TGZ-induced cell death. Notably, pretreatment with pyruvate significantly prevented the cell death, suggesting a potential mechanistic link between metabolic stress and HRG/TGZ-induced cell death. The activation of the HRG signaling axis has been considered as a poor prognostic factor in breast cancer and confers resistance to gefitinib (Iressa) and tamoxifen. However, our data presented here paradoxically suggest that HRG expression can actually be beneficial when it comes to treating breast cancer with peroxisome proliferator-activated receptor-γ ligands. Taken together, the combination of HRG and TGZ may provide a basis for the development of a novel strategy in the treatment of apoptosis-resistant and/or hormone-refractory breast cancer.

Seropositivity to cytomegalovirus, inflammation, all-cause and cardiovascular disease-related mortality in the United States

BACKGROUND

Studies have suggested that CMV infection may influence cardiovascular disease (CVD) risk and mortality. However, there have been no large-scale examinations of these relationships among demographically diverse populations. The inflammatory marker C-reactive protein (CRP) is also linked with CVD outcomes and mortality and may play an important role in the pathway between CMV and mortality. We utilized a U.S. nationally representative study to examine whether CMV infection is associated with all-cause and CVD-related mortality. We also assessed whether CRP level mediated or modified these relationships.

METHODOLOGY/PRINCIPAL FINDINGS

Data come from subjects ≥ 25 years of age who were tested for CMV and CRP level and were eligible for mortality follow-up on December 31(st), 2006 (N = 14153) in the National Health and Nutrition Examination Survey (NHANES) III (1988-1994). Cox proportional hazard models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for all-cause and CVD-related mortality by CMV serostatus. After adjusting for multiple confounders, CMV seropositivity remained statistically significantly associated with all-cause mortality (HR 1.19, 95% CI: 1.01, 1.41). The association between CMV and CVD-related mortality did not achieve statistical significance after confounder adjustment. CRP did not mediate these associations. However, CMV seropositive individuals with high CRP levels showed a 30.1% higher risk for all-cause mortality and 29.5% higher risk for CVD-related mortality compared to CMV seropositive individuals with low CRP levels.

CONCLUSIONS/SIGNIFICANCE

CMV was associated with a significant increased risk for all-cause mortality and CMV seropositive subjects who also had high CRP levels were at substantially higher risk for both for all-cause and CVD-related mortality than subjects with low CRP levels. Future work should target the mechanisms by which CMV infection and low-level inflammation interact to yield significant impact on mortality.

Are autoantibodies triggering endothelial cell apoptosis really pathogenic?

Anti-endothelial cell (EC) antibodies (AECA) are a heterogeneous group of antibodies directed against a variety of EC membrane proteins. A pathogenic role for AECA in diseases that involve the vascular system has not been clearly demonstrated. Induction of EC apoptosis appears to be one of the mechanisms by which AECA may exert their effect. AECA from some patients trigger the translocation of anionic phospholipids, most notably phosphatidylserine, from the inner to the outer leaflet of the plasma membrane, and thereafter activation of caspase 3 and cleavage of poly (ADP-ribose) polymerase, hallmarks of apoptosis. Apoptotic cell death generates oxidatively modified moieties, which can induce autoimmune and local inflammatory responses. While a sole AECA target involved in the apoptotic process of ECs has not been identified, some evidence suggests that Heat Shock Proteins may be an outstanding antigen.

Antiflagellin antibodies recognize the autoantigens Toll-Like Receptor 5 and Pals 1-associated tight junction protein and induce monocytes activation and increased intestinal permeability in Crohn's disease

BACKGROUND AND OBJECTIVES

Bacterial flagellin is considered an important antigen in Crohn's disease (CD) as it activates innate immunity through Toll-Like Receptor 5 (TLR5) engagement and induces an elevated adaptive immune response. Little is known about the presence of an autoimmune process in CD. We aimed to identify pathogenically relevant autoantigen targets in CD.

METHODS

We screened a random peptide library with pooled sera of patients with active CD. Transepithelial flux of [3H] mannitol in T84 human intestinal epithelial cell line was used to study the epithelial barrier function. Monocyte activation was evaluated by surface expression of activation markers and by production of pro-inflammatory cytokines. Gene modulation of T84 cells exposed to antipeptide antibodies was analysed by gene array.

RESULTS

We identified a peptide that shares homology with Salmonella typhimurium flagellin and with self-antigens such as TLR5 and cell junction protein, Pals 1-associated tight junction protein. The affinity-purified antipeptide antibodies recognized the self-antigens and induced increased intestinal epithelial cell permeability. Moreover, the antibodies induced monocyte activation upon binding TLR5. Finally, in cultured intestinal cells (T84) the purified antibodies induced the modulation of clusters of proinflammatory genes similar to the one induced by the engagement of TLR5 by its natural ligand flagellin.

CONCLUSIONS

Antibodies directed against an immunodominant peptide of flagellin recognize self-antigens and are functionally active suggesting the presence of an autoimmune process that can both facilitate loss of tolerance to intestinal microflora by increasing cell permeability and amplify the innate immunity involvement through a novel mechanism of TLR5 activation.