The infectious etiology of the antiphospholipid syndrome: links between infection and autoimmunity

Antiphospholipid antibody-induced trophoblast responses are differentially modulated by viral dsRNA and viral ssRNA

PROBLEM

Women with antiphospholipid antibodies (aPL) are at increased risk for pregnancy loss and preeclampsia. aPL target the trophoblast and induce a pro-inflammatory, anti-angiogenic and anti-migratory profile. Since infection during pregnancy can increase the risk for preeclampsia, a viral infection could further increase this in women with aPL. The goal of this study was to characterize the effect of viral components on trophoblast responses to aPL.

METHOD OF STUDY

A human first trimester trophoblast cell line was treated with or without aPL or control IgG in the presence of media, viral dsRNA or viral ssRNA. Supernatants were measured for inflammatory IL-1β and IL-8; inflammasome-associated uric acid and caspase-1 activity; and anti-angiogenic sFlt-1. Trophoblast migration was measured using a two-chamber assay.

RESULTS

Viral dsRNA augmented aPL-induced trophoblast caspase-1 activity, and IL-1β and IL-8 secretion in an additive manner. Viral ssRNA inhibited aPL-induced uric acid, IL-1β and sFlt-1 secretion, and further exacerbated aPL-inhibition of trophoblast migration.

CONCLUSION

While viral ssRNA may have some protective effects on aPL-induced inflammation and anti-angiogenic responses, viral dsRNA exacerbated aPL-mediated inflammation and viral ssRNA further limited cell migration, which could prove detrimental to placentation. Thus, viral infections may contribute to adverse pregnancy outcomes in women with aPL.

Maternal COVID-19 Vaccination and Its Potential Impact on Fetal and Neonatal Development

Vaccines have been developed at "warp speed" to combat the COVID-19 pandemic caused by the SARS-CoV-2 coronavirus. Although they are considered the best approach for preventing mortality, when assessing the safety of these vaccines, pregnant women have not been included in clinical trials. Thus, vaccine safety for this demographic, as well as for the developing fetus and neonate, remains to be determined. A global effort has been underway to encourage pregnant women to get vaccinated despite the uncertain risk posed to them and their offspring. Given this, post-hoc data collection, potentially for years, will be required to determine the outcomes of COVID-19 and vaccination on the next generation. Most COVID-19 vaccine reactions include injection site erythema, pain, swelling, fatigue, headache, fever and lymphadenopathy, which may be sufficient to affect fetal/neonatal development. In this review, we have explored components of the first-generation viral vector and mRNA COVID-19 vaccines that are believed to contribute to adverse reactions and which may negatively impact fetal and neonatal development. We have followed this with a discussion of the potential for using an ovine model to explore the long-term outcomes of COVID-19 vaccination during the prenatal and neonatal periods.

Anti-Phospholipid Antibodies and COVID-19 Thrombosis: A Co-Star, Not a Supporting Actor

Background: COVID-19 clinical features include a hypercoagulable state that resembles the antiphospholipid syndrome (APS), a disease characterized by thrombosis and presence of antiphospholipid antibodies (aPL). The relationship between aPL-presence and the appearance of thrombi as well as the transience or permanence of aPL in COVID-19 patients is not sufficiently clear. Methods: A group of 360 COVID-19 patients were followed-up for 6 months. Classic aPL, anti-B2GPI IgA, anti-phosphatidylserine/prothrombin IgG/M and anti-SARS-CoV-2 antibodies were determined at acute phase and >12 weeks later. The reference group included 143 healthy volunteers of the same age-range distribution. Results: aPL prevalence was similar in COVID-19 patients and the reference population. aPL presence in both determinations was significantly associated with thrombosis (OR: 2.33 and 3.71), strong agreement being found for classic aPL and anti-B2GPI IgA (Weighted kappa: 0.85–0.91). Thrombosis-associated aPL occurred a median of 17 days after hospital admission (IQR: 6–28) vs. 4 days for the rest (IQR: 3–7). Although anti-SARS-CoV-2 antibodies levels increased during convalescence, aPL hardly changed. Conclusions: Most COVID-19 patients would carry these aPL before the infection. At least two mechanisms could be behind thrombosis, early immune-dysregulation-mediated thrombosis after infection and belated-aPL-mediated thrombosis, with SARS-CoV-2 behaving as a second hit.

Antiphospholipid antibodies and risk of post-COVID-19 vaccination thrombophilia: The straw that breaks the camel's back?

Antiphospholipid antibodies (aPLs), present in 1–5 % of healthy individuals, are associated with the risk of antiphospholipid syndrome (APS), which is the most common form of acquired thrombophilia. APLs may appear following infections or vaccinations and have been reported in patients with COronaVIrus Disease-2019 (COVID-19). However, their association with COVID-19 vaccination is unclear. Notably, a few cases of thrombocytopenia and thrombotic events resembling APS have been reported to develop in recipients of either adenoviral vector- or mRNA-based COVID-19 vaccines.

The aim of this review is therefore to speculate on the plausible role of aPLs in the pathogenesis of these rare adverse events.

Adenoviral vector-based vaccines can bind platelets and induce their destruction in the reticuloendothelial organs. Liposomal mRNA-based vaccines may instead favour activation of coagulation factors and confer a pro-thrombotic phenotype to endothelial cells and platelets. Furthermore, both formulations may trigger a type I interferon response associated with the generation of aPLs. In turn, aPLs may lead to aberrant activation of the immune response with participation of innate immune cells, cytokines and the complement cascade. NETosis, monocyte recruitment and cytokine release may further support endothelial dysfunction and promote platelet aggregation. These considerations suggest that aPLs may represent a risk factor for thrombotic events following COVID-19 vaccination, and deserve further investigations.

Role of NOD2 in antiphospholipid antibody-induced and bacterial MDP amplification of trophoblast inflammation

Women with antiphospholipid antibodies (aPL) are at high risk for pregnancy complications, such as preeclampsia. We previously demonstrated that aPL recognizing β₂GPI promote an extravillous trophoblast pro-inflammatory, anti-migratory and anti-angiogenic profile similar to that seen in preeclampsia. Since preeclampsia in the absence of aPL may have an underlying infectious element, women with aPL may be at increased risk for preeclampsia or other adverse outcomes if an infection is present. Our objective was to determine the impact the common bacterial component, muramyl dipeptide (MDP), has on trophoblast responses to aPL. Herein, we report that bacterial MDP amplifies trophoblast IL-1β expression, processing, and secretion in the presence of aPL through activation of NOD2. In the absence of MDP, NOD2 also mediates anti- β₂GPI antibody-induced trophoblast IL-1β and VEGF secretion. Additionally, we report a role for extravillous trophoblast vimentin as a novel danger signal that contributes to the aPL-induced trophoblast IL-1β production. Together our data indicate that NOD2 mediates trophoblast inflammatory and angiogenic responses to aPL alone, and mediates trophoblast inflammation in the presence of bacterial MDP. These findings suggest that a bacterial infection at the maternal-fetal interface may exacerbate the impact aPL have on trophoblast inflammation and, thus, on pregnancy outcome.

Anti-phospholipid Antibodies and Smoking: An Overview

Antiphospholipid syndrome is characterized by the presence of antiphospholipid antibodies, specifically lupus anticoagulant, anticardiolipin antibodies, and anti-β2 glycoprotein-I antibodies. Antiphospholipid syndrome can occur on its own or in association with other autoimmune diseases, most commonly systemic lupus erythematosus (SLE). A connection between cigarette smoking and anti-phospholipid antibodies (aPL) was first reported in the late1980s. Systemic lupus erythematosus patients with aPL are more likely to be smokers than those without aPL. These patients have a particularly high frequency of vascular events. Recently, a potential link between periodontitis, tobacco, and aPL has been proposed. Research has also suggested that periodontitis and Porphyromonas gingivalis infection are associated with citrullination through the action of peptidylarginine deiminase. A strong correlation between smoking and the presence of citrillunated autoantibodies, which are characteristic of rheumatoid arthritis, has also been observed. While many studies have investigated possible links between infection and aPL in patients with autoimmune diseases, the association of smoking with aPL has not been systematically examined. The fact that both aPL and tobacco are risk factors for thrombosis has complicated efforts to evaluate these factors separately. Also, there has been great variability in measurement techniques, and laboratories lack routine methods for differentiating transient and persistent aPL; both of these factors can make interpretation of autoantibody results quite challenging. This review summarizes the clinical evidence supporting a posited link between aPL and smoking, both in patients with a systemic autoimmune disease and in patients with other medical conditions.

Immunological Tolerance, Pregnancy, and Preeclampsia: The Roles of Semen Microbes and the Father

Although it is widely considered, in many cases, to involve two separable stages (poor placentation followed by oxidative stress/inflammation), the precise originating causes of preeclampsia (PE) remain elusive. We have previously brought together some of the considerable evidence that a (dormant) microbial component is commonly a significant part of its etiology. However, apart from recognizing, consistent with this view, that the many inflammatory markers of PE are also increased in infection, we had little to say about immunity, whether innate or adaptive. In addition, we focused on the gut, oral and female urinary tract microbiomes as the main sources of the infection. We here marshall further evidence for an infectious component in PE, focusing on the immunological tolerance characteristic of pregnancy, and the well-established fact that increased exposure to the father's semen assists this immunological tolerance. As well as these benefits, however, semen is not sterile, microbial tolerance mechanisms may exist, and we also review the evidence that semen may be responsible for inoculating the developing conceptus (and maybe the placenta) with microbes, not all of which are benign. It is suggested that when they are not, this may be a significant cause of PE. A variety of epidemiological and other evidence is entirely consistent with this, not least correlations between semen infection, infertility and PE. Our view also leads to a series of other, testable predictions. Overall, we argue for a significant paternal role in the development of PE through microbial infection of the mother via insemination.

Study of β2-Glycoprotein I Polymorphisms in Patients With Chronic Renal Failure as a Predisposing Factor for the Development of Anti-β2-Glycoprotein I Auto-Antibodies

BACKGROUND

Immunoglobulin (Ig)A anti-β₂-glycoprotein I (aB2GP1) antibodies are associated with thrombotic events, cardiovascular morbidity, and death in dialysis patients. About 30% of patients with chronic renal disease are positive for IgA aB2GP1; however, the origin of these antibodies is unknown. It has been speculated that dialysis membranes, age, or etiology of renal base disease are possible precipitating factors, although these factors do not appear to be the source of antibodies. B2GP1 is a protein of 326 amino acids grouped into five domains. Eight polymorphisms have been described; the most important are Val/Leu²⁴⁷, which appears to predispose aB2GP1 antibody production in patients with anti-phospholipid syndrome, and Trp/Ser³¹⁶, which appears to have protective antibody production of aB2GP1.

METHODS

DNA samples from 92 patients with renal failure on hemodialysis were randomly collected with a 1:1 ratio for the positivity for IgA aB2GP1. Forty-six samples were positive for IgA aB2GP1 (group 1) and 46 negative for IgA aB2GP1 (group 2). All samples were anonymized to study polymorphism Val/Leu²⁴⁷ and polymorphism Trp/Ser³¹⁶.

RESULTS

No significant differences were observed between those who were positive or negative for IgA aB2GP1 in patients with renal failure treated with hemodialysis and the polymorphism located in codons 247 and 316.

CONCLUSIONS

The two groups of patients have the same prevalence in polymorphisms 247 and 316, and therefore there appears not to be a genetic predisposition in our population. New trigger factors must be studied.

Systematic review of case reports of antiphospholipid syndrome following infection

OBJECTIVE

The objective of this study was to conduct a systematic review of case reports documenting the development of antiphospholipid syndrome or antiphospholipid syndrome-related features after an infection.

METHODS

We searched Medline, EMBASE, Web of Science, PubMed ePubs, and The Cochrane Library - CENTRAL through March 2015 without restrictions. Studies reporting cases of antiphospholipid syndrome or antiphospholipid syndrome-related features following an infection were included.

RESULTS

Two hundred and fifty-nine publications met inclusion criteria, reporting on 293 cases. Three different groups of patients were identified; group 1 included patients who fulfilled the criteria for definitive antiphospholipid syndrome (24.6%), group 2 included patients who developed transient antiphospholipid antibodies with thromboembolic phenomena (43.7%), and group 3 included patients who developed transient antiphospholipid antibodies without thromboembolic events (31.7%). The most common preceding infection was viral (55.6%). In cases that developed thromboembolic events Human immunodeficiency and Hepatitis C viruses were the most frequently reported. Parvovirus B19 was the most common in cases that developed antibodies without thromboembolic events. Hematological manifestations and peripheral thrombosis were the most common clinical manifestations. Positive anticardiolipin antibodies were the most frequent antibodies reported, primarily coexisting IgG and IgM isotypes. Few patients in groups 1 and 2 had persistent antiphospholipid antibodies for more than 6 months. Outcome was variable with some cases reporting persistent antiphospholipid syndrome features and others achieving complete resolution of clinical events.

CONCLUSIONS

Development of antiphospholipid antibodies with all traditional manifestations of antiphospholipid syndrome were observed after variety of infections, most frequently after chronic viral infections with Human immunodeficiency and Hepatitis C. The causal relationship between infection and antiphospholipid syndrome cannot be established, but the possible contribution of various infections in the pathogenesis of antiphospholipid syndrome need further longitudinal and controlled studies to establish the incidence, and better quantify the risk and the outcomes of antiphospholipid-related events after infection.

Fulminant ecchymosis as the initial manifestation of antiphospholipid syndrome (APS) triggered by respiratory syncytial virus (RSV) infection: A case report and review of the literature

We present a unique and informative instance of respiratory syncytial virus (RSV) infection associated with antiphospholipid syndrome (APS), and discuss this case in the context of the literature addressing the immunopathogenesis of APS associated with diverse infections. We describe the case of a 43-year-old man with no significant past medical history who presented with the acute onset of fever, hemoptysis, and extensive bullous, ecchymotic lesions in both lower extremities. Punch biopsy of the lesion demonstrated thrombotic vasculopathy. Further evaluation revealed serum antiphospholipid antibodies as well as a positive RSV PCR in a nasal swab specimen. Clinical manifestations, positive laboratory and pathological findings were strongly suggestive of APS associated with a recent RSV infection. When an infectious etiology is considered for APS, RSV should also be included in the differential diagnosis.

Antiphospholipid Syndrome and Kidney Involvement: New Insights

Antiphospholipid syndrome is an autoimmune disorder characterized by vascular thromboses and pregnancy morbidity associated with antiphospholipid antibodies: lupus anticoagulant, IgG or IgM anticardiolipin or anti-beta 2-glycoprotein I. The kidney is one of the major target organs in antiphospholipid syndrome (APS). However, beyond the known involvement of the kidney in primary and associated APS, we may be observing a new form of APS within the context of renal failure. This review describes the classical kidney manifestations of APS and provides new considerations to be taken into account.

The environment and antiphospholipid syndrome

The etiology of autoimmune diseases is multifactorial. The degree to which genetic and environmental factors influence susceptibility to autoimmune diseases is poorly defined. It is believed that versatile clinical presentations of autoimmune diseases stem from various combinations of the genetic and environmental factors. One of the newly diagnosed autoimmune diseases is the antiphospholipid syndrome (APS). APS is characterized by vascular thrombosis, and/or pregnancy morbidity associated with anticardiolipin (aCL), anti-β2-glycoprotein-I (anti-β2GPI) and lupus anticoagulant (LAC).

A Dormant Microbial Component in the Development of Preeclampsia

Preeclampsia (PE) is a complex, multisystem disorder that remains a leading cause of morbidity and mortality in pregnancy. Four main classes of dysregulation accompany PE and are widely considered to contribute to its severity. These are abnormal trophoblast invasion of the placenta, anti-angiogenic responses, oxidative stress, and inflammation. What is lacking, however, is an explanation of how these themselves are caused. We here develop the unifying idea, and the considerable evidence for it, that the originating cause of PE (and of the four classes of dysregulation) is, in fact, microbial infection, that most such microbes are dormant and hence resist detection by conventional (replication-dependent) microbiology, and that by occasional resuscitation and growth it is they that are responsible for all the observable sequelae, including the continuing, chronic inflammation. In particular, bacterial products such as lipopolysaccharide (LPS), also known as endotoxin, are well known as highly inflammagenic and stimulate an innate (and possibly trained) immune response that exacerbates the inflammation further. The known need of microbes for free iron can explain the iron dysregulation that accompanies PE. We describe the main routes of infection (gut, oral, and urinary tract infection) and the regularly observed presence of microbes in placental and other tissues in PE. Every known proteomic biomarker of "preeclampsia" that we assessed has, in fact, also been shown to be raised in response to infection. An infectious component to PE fulfills the Bradford Hill criteria for ascribing a disease to an environmental cause and suggests a number of treatments, some of which have, in fact, been shown to be successful. PE was classically referred to as endotoxemia or toxemia of pregnancy, and it is ironic that it seems that LPS and other microbial endotoxins really are involved. Overall, the recognition of an infectious component in the etiology of PE mirrors that for ulcers and other diseases that were previously considered to lack one.

The beneficial effect of plasmapheresis in mixed connective tissue disease with coexisting antiphospholipid syndrome

The authors report a rare case of a female patient with mixed connective tissue disease (MCTD) with coexisting antiphospholipid syndrome (APS). Five years after the diagnosis of MCTD high concentrations of anticardiolipin (anti-CL) and anti-β2-glycoprotein (anti-β2GPI) autoantibodies were present in the patient’s serum without thrombotic events. Epstein-Barr virus (EBV) reactivation provoked APS, with the clinical manifestations of livedo reticularis, digital gangrene and leg ulcers. Skin biopsy from the necrotic area showed multiple fibrin microthrombi in the superficial vessels. Corticosteroid pulse therapy, and plasma exchange in combination with synchronized cyclophosphamide was administered, which led to improvement of the digital gangrenes, while no new lesions developed. The number of CD27high plasma cells decreased, and the previous high levels of autoantibodies also normalized in the peripheral blood. In the case of MCTD with coexisting APS combination therapy, including plasmapheresis has beneficial effects.

Infection-induced autoantibodies and pregnancy related pathology: an animal model

In addition to being the main cause of mortality worldwide, bacterial and viral infections can be the cause of autoimmune and pregnancy disorders as well. The production of autoantibodies during infection can be explained by various mechanisms, including molecular mimicry, bystander cell activation and epitope spreading. Conversely, bacterial and viral infections during pregnancy are especially dangerous for the fetus. It is documented that infection-induced inflammatory processes mediated by Toll-like receptors (TLR) represent the main cause of preterm labour. We used two crucial bacterial components and TLR ligands, namely peptidoglycan and lipopolysaccharide, to stimulate BALB/c mice before immunisation with tetanus toxoid. Tetanus toxoid is an inactive form of the toxin produced by bacterium Clostridium tetani and shares structural similarity with plasma protein β2-glycoprotein I. Treatment with peptidoglycan and lipopolysaccharide in combination with tetanus toxoid induced the production of pathological autoantibodies, different fluctuations in natural autoantibodies and different types of reproductive pathology in treated animals, with peptidoglycan treatment being more deleterious. We propose that the production of pathological autoantibodies, TLR activation and changes in natural autoantibodies play crucial roles in infection-induced reproductive pathology in our animal model.

Q Fever with transient antiphospholipid antibodies associated with cholecystitis and splenic infarction

We describe a case of Q fever associated with the transient presence of antiphospholipid antibodies in a 9-year-old boy presenting with acalculous cholecystitis and splenic infarction. Antiphospholipid antibodies are commonly associated with acute Q fever in adults but have previously been thought to be of little clinical significance. Recent data suggest that antiphospholipid antibodies may be responsible for certain clinical manifestations of acute Q fever.

Vascular Pathophysiology in Hearing Disorders

The inner ear vasculature is responsible for maintenance of the blood-labyrinth barrier, transport of systemic hormones for ion homeostasis, and supplying nutrients for metabolic functions. Unfortunately, these blood vessels also expose the ear to circulating inflammatory factors resulting from systemic diseases. Thus, while the inner ear blood vessels are critical for normal function, they also are facilitating pathologic mechanisms that result in hearing and vestibular dysfunction. In spite of these numerous critical roles of inner ear vasculature, little is known of its normal homeostatic functions and how these are compromised in disease. The objective of this review is to discuss the current concepts of vascular biology, how blood vessels naturally respond to circulating inflammatory factors, and how such mechanisms of vascular pathophysiology may cause hearing loss.

Annexin A5 binds to lipopolysaccharide and reduces its endotoxin activity

Annexin A5 (AnxA5) has a high affinity for phosphatidylserine. The protein is widely used to detect apoptotic cells because phosphatidylserine, a phospholipid that is normally present in the inner leaflets of cytoplasmic membranes, becomes translocated to the outer leaflets during programmed cell death. Here we report the novel observation that AnxA5 binds to Gram-negative bacteria via the lipid A domain of lipopolysaccharide (LPS). Binding of AnxA5 to bacteria was measured quantitatively, confirmed by fluorescence microscopy, and found to be inhibited by antibodies against lipid A. AnxA5 also bound to purified dot-blotted LPS and lipid A. Through ellipsometry, we found that the binding of AnxA5 to purified LPS was calcium dependent and rapid and showed a high affinity—characteristics similar to those of AnxA5 binding to phosphatidylserine. Initial functional studies indicated that AnxA5 can affect LPS activities. AnxA5 inhibited LPS-mediated gelation in the Limulus amebocyte lysate assay. Incubation of LPS with the protein reduced the quantity of tumor necrosis factor alpha (TNF-α) released by cultured monocytes compared to that released upon incubation with LPS alone. Initial in vivo experiments indicated that injection of mice with LPS preincubated with AnxA5 produced serum TNF-α levels lower than those seen after injection of LPS alone. These data demonstrate that AnxA5 binds to LPS and open paths to investigation of the potential biological and therapeutic implications of this interaction.

AnxA5 is highly expressed in cells that have a barrier function—including, among others, vascular endothelium, placental trophoblasts, and epithelial cells lining bile ducts, renal tubules, mammary ducts, and nasal epithelium. The protein has been well characterized for its binding to phospholipid bilayers that contain phosphatidylserine. This report of a previously unrecognized activity of AnxA5 opens the door to investigation of the possibility that this binding may have biological and therapeutic ramifications. In view of the tissue expression of the protein, the present results suggest the possibility that AnxA5 plays a role in modulating the host defense against lipopolysaccharide at these anatomic sites, where cells may interface with microorganisms. These results also raise the intriguing possibility that AnxA5 or analogous proteins or peptides could provide novel approaches to addressing the difficult clinical problem of Gram-negative sepsis.

Superior vena cava syndrome – changing etiology in the third millennium

Superior vena cava syndrome (SVCS), is diagnosed following different degrees of central venous system obstruction, which traditionally was caused by infections, tumors or fibrosing mediastinitis. Recently the role of SVC thrombosis secondary to indwelling central venous devices or pacemaker leads as well as different hypercoagulable states have drawn much attention. In the current review we present a 58-year-old female patient who underwent recurrent pacemaker replacements due to recurrent infections. The patient was hospitalized with superior vena cava syndrome and multiple thrombi in the upper body circulation. Additionally the evaluation was conducted for thrombophilia, which revealed the presence of high titers of antiphospholipid antibodies, suggesting the concurrent diagnosis of the antiphospholipid syndrome (APS). This case reflects the changes in the etiology of SVCS, and the need for a comprehensive evaluation of patients, in the search for additional factors that may complicate a pacemaker insertion, such as the presence of antiphospholipid antibodies. We review the relevant literature and highlight the importance for an interdisciplinary approach in the treatment of SVCS nowadays.

Characterization of antiphospholipid antibodies in chronic hepatitis B infection

BACKGROUND

Many infections are associated with antiphospholipid antibodies (aPLs). The purpose of this study was to investigate the prevalence, persistence, clinical significance, and characteristics of aPLs in hepatitis B virus (HBV)-infected patients.

METHODS

This study included 143 patients with HBV infection and 32 healthy individuals as controls. The presence of anticardiolipin antibodies (aCL Ab), anti-β(2)-glycoprotein I antibodies (β(2)GPI Ab), and lupus anticoagulant (LA) was assessed.

RESULTS

The total prevalence of aPLs in HBV-infected patients was 12.6% (18 of 143). Of these 18 patients, 15 had low to medium titers of aCL Ab (10 with IgM, 4 with IgG, and 1 with both isotypes). β(2)GPI Ab and LA were detected in 3 (2.1%) and 2 (1.4%) patients with HBV infection, respectively. In follow-up specimens from 14 patients with elevated levels of aCL Ab or β(2)GPI Ab, 10 (71.4%) showed the persistent presence of aPLs. No clinical manifestations related to aPLs were identified.

CONCLUSION

In HBV-infected patients, the most frequently detected antiphospholipid antibodies were IgM aCL Ab, which have a weak association with the clinical manifestations of APS. Unlike the transient presence reported for other infection-associated aPLs, most aPLs were persistently detected over a 12-week period in patients with HBV infection.

The role of infections in the immunopathogensis of systemic sclerosis--evidence from serological studies

Infections are believed to often play a role in the immunopathogenesis of autoimmune disorders; such is the case in systemic sclerosis (SSc). In order to evaluate the potential role infections may have on the pathogenesis of SSc, we assessed serological reactivity against various infectious agents in patients with SSc and compared them with healthy controls. Serological samples obtained from 80 patients with SSc were compared with 296 compatible healthy controls. Both groups were of European origin. All samples were tested for the presence of antibodies directed against hepatitis B virus, hepatitis C virus, toxoplasmosis, rubella, CMV, EBV, and Treponema pallidum. We applied Bio-Rad commercial and experimental kits to assess most antigens and ELISA assays to complete the panel. Patients with SSc had elevated IgM and IgG against Toxoplasma gondii and against CMV. Higher titers were also detected against the hepatitis B virus core protein (recombinant HBc antigen) using MONOLISA anti-HBc Plus commercial kit (Bio-Rad). A significantly higher rate of IgM antibodies against the capsid antigen of the EBV was detected in SSc patients compared with healthy controls, as well. These data demonstrate that antibodies against CMV, HBV, and toxoplasmosis were detected more often in patients with SSc. This association implies that infectious agents may have a role in disease pathogenesis and expression.

Infections and the antiphospholipid syndrome

Currently, the origin of autoimmune diseases is considered to be multifactorial. Genetic predisposition, immune system malfunction or even backfire, hormonal regulation, and environmental factors, i.e. infections, all play important roles in the pathogenesis of autoimmune diseases such as the antiphospholipid syndrome (APS). New drugs and strategies aimed at preventing infections could further improve the outcome of APS and other autoimmune diseases.

Unravelling autoimmune pathogenesis by screening random peptide libraries with human sera

The incidence of autoimmunity is increasing worldwide. The long preclinical period of autoimmune disorders is characterised by an enhanced exposure over time of autoreactive T cells to an increased number of autoantigenic determinants and autoantibodies production. The discovery of novel autoimmune-disease related epitopes is a task that remains extremely challenging in order to establish predictive and preventive strategies of the disease onset. In this Opinion article we highlight the contribution of screening combinatorial random peptide libraries with patients sera in unravelling the etiopathogenesis of autoimmunity.

Andes virus antigens are shed in urine of patients with acute hantavirus cardiopulmonary syndrome

Hantavirus cardiopulmonary syndrome (HCPS) is a highly pathogenic emerging disease (40% case fatality rate) caused by New World hantaviruses. Hantavirus infections are transmitted to humans mainly by inhalation of virus-contaminated aerosol particles of rodent excreta and secretions. At present, there are no antiviral drugs or immunotherapeutic agents available for the treatment of hantaviral infection, and the survival rates for infected patients hinge largely on early virus recognition and hospital admission and aggressive pulmonary and hemodynamic support. In this study, we show that Andes virus (ANDV) interacts with human apolipoprotein H (ApoH) and that ApoH-coated magnetic beads or ApoH-coated enzyme-linked immunosorbent assay plates can be used to capture and concentrate the virus from complex biological mixtures, such as serum and urine, allowing it to be detected by both immunological and molecular approaches. In addition, we report that ANDV-antigens and infectious virus are shed in urine of HCPS patients.

Increased expression of Matrix Metalloproteinase 9 in liver from NZB/W F1 mice received antibody against human parvovirus B19 VP1 unique region protein

Background

Human parvovirus B19 infection has been postulated to the anti-phospholipid syndrome (APS) in autoimmunity. However, the influence of anti-B19-VP1u antibody in autoimmune diseases is still obscure.

Methods

To elucidate the effect of anti-B19-VP1u antibodies in systemic lupus erythematosus (SLE), passive transfer of rabbit anti-B19-VP1u IgG was injected intravenously into NZB/W F1 mice.

Results

Significant reduction of platelet count and prolonged thrombocytopenia time were detected in anti-B19-VP1u IgG group as compared to other groups, whereas significant increases of anti-B19-VP1u, anti-phospholipid (APhL), and anti-double strand DNA (dsDNA) antibody binding activity were detected in anti-B19-VP1u group. Additionally, significant increases of matrix metalloproteinase-9 (MMP9) activity and protein expression were detected in B19-VP1u IgG group. Notably, phosphatidylinositol 3-phosphate kinase (PI3K) and phosphorylated extracellular signal-regulated kinase (ERK) proteins were involved in the induction of MMP9.

Conclusion

These experimental results firstly demonstrated the aggravated effects of anti-B19-VP1u antibody in disease activity of SLE.

[Infectious agents in the etiopathogenesis of rheumatic diseases]

This article is an author's view of how to face the knowledge about infectious agents and their pathogenic role in the starting immune mechanisms, trying to clarify its role in the origin of some rheumatic diseases. From the basic immune responds, recent evidence and newly molecular mechanisms are dissected as well as diagnostic and therapeutic implications.

Relationship and significance between anti-β2-glycoproteinI antibodies and platelet activation state in patients with ulcerative colitis

AIM: To study the relationship between anti-β₂-glycoprotein I (aβ₂GPI) antibodies and platelet activation state in patients with ulcerative colitis (UC) and its significance.

METHODS: Peripheral blood samples were collected from 56 UC patients (34 males and 22 females, aged 43.5 years, range 21-66 years), including 36 at active stage and 20 at remission stage, and 25 sex-and age-matched controls. The level of aβ₂GPI was measured by ELISA. The platelet activation markers, platelet activation complex-I (PAC-I) and P-selectin (CD62P) were detected by flow cytometry.

RESULTS: The A value for IgG aβ₂GPI in the active UC group was 0.61 ± 0.13, significantly higher than that in the remittent UC and control groups (0.50 ± 0.13 and 0.22 ± 0.14, P < 0.01). There was a significant difference between the two groups (P < 0.01). The A value for IgM aβ₂GPI in the active and remittent UC groups was 0.43 ± 0.13 and 0.38 ± 0.12, significantly higher than that in the control group (0.20 ± 0.12, P < 0.01). However, there was no significant difference between the two groups (P > 0.05). The PAC-I positive rate for the active and remittent UC groups was 30.6% ± 7.6% and 19.6% ± 7.8% respectively, significantly higher than that for the control group (6.3% ± 1.7%, P < 0.01). There was a significant difference between the two groups (P < 0.01). The CD62P positive rate for the active and remittent UC groups was 45.0% ± 8.8% and 31.9% ± 7.8% respectively, significantly higher than that for the control group (9.2% ± 2.7%, P < 0.01). There was a significant difference between the two groups (P < 0.01). In the active UC group, the more severe the state of illness was, the higher the A value for IgG aβ₂GPI was, and the positive rate for PAC-I and CD62P was positively correlated with the state of illness (Faβ₂GPI = 3.679, P < 0.05; FPAC-I (%) = 5.346, P < 0.01; and FCD62P (%) = 5. 418, P < 0.01). Meanwhile, in the same state of illness, the A value for IgG aβ₂GPI was positively correlated to the positive rates for PAC-I and CD62P.

CONCLUSION: aβ₂GPI level, platelet activation state and their relationship of them are closely correlated with the pathogenesis and development of UC.

Antiphospholipid antibodies, antiphospholipid syndrome and infections

Since the association between antiphospholipid antibodies (aPL) and syphilis was first described, many other viral, bacterial and parasitic infections have been shown to induce antiphospholipid antibodies, notably anticardiolipin antibodies (aCL). A review of the literature shows that while aCL occur frequently in viral infections, particularly in HIV (49.75%), HBV (24%) and HCV (20%), it is very rarely associated with anti-beta2 glycoprotein I antibodies (anti-beta2GPI) and is not correlated with thrombosis risk or hematological manifestations of the antiphospholipid syndrome (APS). Concerning bacterial infections, aCL is often present in leprosy (42.7%), where it is frequently associated with the presence of anti-beta2GPI (44.8%), and in syphilis infections (8 to 67%), though without correlation with thrombotic events. Though few individual patients with unequivocal infection-induced aPL satisfy criteria for APS, the lack of statistical association with thrombotic events strongly argues against the identification of a true APS subset in this context. However, physicians should keep in mind the fact that an infection, generally bacterial, in patients with confirmed APS, may lead to catastrophic antiphospholipid syndrome with a possible fatal outcome.

Clearance deficiency and systemic lupus erythematosus (SLE)

Systemic lupus erythematosus (SLE) is a fairly heterogeneous autoimmune disease. Impaired clearance functions for dying cells may explain accumulation of nuclear autoantigens in various tissues of SLE patients. Our data show that in a subgroup of patients with SLE, apoptotic cells accumulated in the germinal centres of the lymph nodes. Apoptotic material was attached to the surfaces of follicular dendritic cells. Furthermore, we found an accumulation of apoptotic cells in the skin of patients with cutaneous lupus after UV exposure. Granulocytes and monocytes in whole blood of SLE patients showed a reduced uptake of albumin- and polyglobin-coated beads. Furthermore, we analysed sera from SLE patients in migration assays and observed that the attraction signals for macrophages were reduced by sera of approximately 25% of the SLE patients. Analyses of high-affinity DNA binding IgG autoantibodies of SLE patients revealed that those antibodies had gained their DNA reactivity in a germinal centre reaction. We suggest a stepwise maturation from a non-anti-DNA reactive B cell to an anti-dsDNA autoreactive B cell. We conclude that impaired clearance in early phases of apoptosis leads to a secondary necrotic status of the cells. Danger signals are released; modified autoantigens are accessible, favouring an autoimmune reaction.

Induction of antiphospholipid antibodies and antiphospholipid syndrome-like autoimmunity in naive mice with antibody against human parvovirus B19 VP1 unique region protein

BACKGROUND

Previous studies have postulated a connection between human parvovirus B19 (B19) infection and anti-phospholipid antibodies (APhL). B19 infection and anti-phospholipid syndrome (APS) exhibit congruent symptoms. Recently, phospholipase A2 (PLA2)-like activity has been linked to the VP1 unique region (VP1u) of B19. However, the precise role of B19-VP1u in pathogenesis of autoimmunity is still obscure.

METHODS

To elucidate the roles of VP1u in B19 infection and autoimmunity, the reactivity of B19-VP1u proteins with various autoantibodies were evaluated by ELISA and immunoblotting. Rabbits were immunized with purified recombinant B19-VP1u protein to generate anti-sera. Absorption experiments were conducted to determine the binding specificity of rabbit anti-sera against B19-VP1u, cardiolipin (CL) and beta-2-glycoprotein I (beta2GPI). Moreover, the effects of passive transfer of polyclonal rabbit anti-B19-VP1u IgG antibodies on platelets, activated partial thromboplastin time (aPTT), and autoantibodies were assessed.

RESULTS

Autoantibodies against CL, beta2GPI, and phospholipid (PhL) in sera from patients with B19 infection, were cross-reactive with B19-VP1u. Consistently, sera from rabbits immunized with recombinant B19-VP1u protein displayed raised detectable immunoglobulins against B19-VP1u, CL, beta2GPI and PhL. Additionally, the mice immunized with anti-B19-VP1u IgG developed thrombocytopenia, prolongation of aPTT, and autoantibody against beta2GPI and PhL.

CONCLUSIONS

These experimental results suggested the association between B19-VP1u and production of anti-beta2GPI antibodies, APhL, and APS-like autoimmunity. Altogether, it may provide a clue in understanding the role of B19-VP1u in inducing autoantibodies and B19-associated APS manifestations.

The association of VP1 unique region protein in acute parvovirus B19 infection and anti-phospholipid antibody production

BACKGROUND

Previous studies have postulated a connection between human parvovirus B19 (B19) infection and anti-phospholipid antibodies (aPL). Recently, the phospholipase domain of B19 has been linked to B19-VP1 unique region (VP1u). To elucidate the roles of VP1u in B19 infection and aPL production, the major reactivity of anti-B19-VP1u, anti-cardiolipin antibody (aCL), and anti-beta2-glycoprotein I (beta2GPI) antibody was evaluated.

METHODS

Sera from 102 clinically suspected cases of B19 infection were analyzed by nested PCR and ELISA. Humoral responses of anti-B19-VP1u and anti-B19-VP1uD175A IgM/IgG antibodies, aCL and the anti-beta2GPI antibody were assessed by Western blot and ELISA. Absorption experiments were also performed to determine the binding specificity of immunoglobulins to B19-VP1u, CL and beta2GPI.

RESULTS

Sera from patients with the diagnostic pattern DNA+/IgM+/IgG+ had a high frequency (57%) for recognition of CL and beta2GPI. Furthermore, adsorption experiments were performed by adding purified B19-VP1u, which partially suppressed the reactivity of anti-B19VP1u to CL and beta2GPI.

CONCLUSIONS

Serum from patients with acute B19 infection has a high frequency in recognition of CL and beta2GPI, and the phospholipase domain observed in the B19-VP1u may have contributed to the production of aPL. These findings may provide a clue for understanding the roles of B19-VP1u in B19 infection and aPL production.

Expression of beta-2-glycoprotein Ⅰ receptor on membranes of hepatoma cell line SMMC-7721

AIM: To further study the interaction between beta-2-glycoprotein Ⅰ(β₂GPⅠ) and the membrane of hepatoma SMMC-7721 cells, and to explore the mechanism of hepatitis B virus (HBV) infection.

METHODS: Fluorescence microscopy and fluorescence activated cell sorter (FACS) was used to observe the interaction of β₂GPⅠ with the hepatoma cell line SMMC-7721, gastric carcinoma cell line SGC-7901 and lymphoma cell line HL-60.

RESULTS: Fluorescence microscopy revealed specific binding of FITC-β₂GPⅠ to SMMC-7721 cells, but neither to HL-60 nor SGC-7901 cells. FACS analysis demonstrated that the binding rate of FITC-β₂GPⅠ (20 μL) to SMMC-7721 cells was significantly higher than that in HL-60 or SGC-7901 cells (19% vs 1.7%, 1.9%, both P < 0.01). When 50 μL FITC-β₂GPⅠ was used, the binding rate of FITC-β₂GPⅠ to SMMC-7721 cells was 20.8%, which was not significantly higher than 19%. The binding rate to SMMC-7721 cells did not increase with the increasing amounts of FITC-β₂GPⅠ.

CONCLUSION: There exists the specific β₂GPⅠbinding protein in the membrane of SMMC-7721 cells.

Annexin A5 in cardiovascular disease and systemic lupus erythematosus

Atherosclerosis, a major cause of disease and death from cardiovascular disease (CVD), is an inflammatory disease characterized by T cell and monocyte/macrophage infiltration in the intima of large arteries. During recent years and with improved treatment of acute disease manifestations, it has become clear that the risk of CVD is very high in systemic lupus erythematosus (SLE), often considered a prototypic autoimmune disease. A combination of traditional and non-traditional risk factors, including dyslipidemia, inflammation, antiphospholipid antibodies (aPL) and lipid oxidation are related to CVD in SLE. aPL are highly thrombogenic, and possible mechanisms include direct effects of aPL on endothelial and other cells, and interference with coagulation reactions. More than a thousand proteins of the annexin-superfamily are expressed in eukaryotes. Annexins are ubiquitous, highly conserved, predominantly intracellular proteins, widely distributed in tissues. Annexin A5 (ANXA5) is an important member of the annexin family due to its antithrombotic properties. These are believed to be caused by it forming a two-dimensional protective shield, covering exposed potentially thrombogenic cell surfaces. Recently, ANXA5 has been implicated in SLE since aPL interfere with ANXA5 binding to placental trophoblasts, causing microthrombosis and miscarriage, a rather common complication in SLE. We recently demonstrated that ANXA5 may play a role in CVD and is abundant in late-stage atherosclerotic lesions. Sera from SLE-patients with a history of CVD inhibited ANXA5 binding to endothelium, caused by IgG antibodies, to a significant degree aPL. This review will focus on potential involvement of ANXA5 in pathogenesis of CVD, particularly caused by underlying atherosclerosis and atherothrombosis.