Induction of endothelial cell apoptosis by heat-shock protein 60-reactive antibodies from anti-endothelial cell autoantibody-positive systemic lupus erythematosus patients

The bidirectional relationship of depression and disturbances in B cell homeostasis: Double trouble

Major depressive disorder (MDD) is a recurrent, persistent, and debilitating neuropsychiatric syndrome with an increasing morbidity and mortality, representing the leading cause of disability worldwide. The dysregulation of immune systems (including innate and adaptive immune systems) has been identified as one of the key contributing factors in the progression of MDD. As the main force of the humoral immunity, B cells have an essential role in the defense against infections, antitumor immunity and autoimmune diseases. Several recent studies have suggested an intriguing connection between disturbances in B cell homeostasis and the pathogenesis of MDD, however, the B-cell-dependent mechanism of MDD remains largely unexplored compared to other immune cells. In this review, we provide an overview of how B cell abnormality regulates the progression of MMD and the potential consequence of the disruption of B cell homeostasis in patients with MDD. Abnormalities of B-cell homeostasis not only promote susceptibility to MDD, but also lead to an increased risk of developing infection, malignancy and autoimmune diseases in patients with MDD. A better understanding of the contribution of B cells underlying MDD would provide opportunities for identification of more targeted treatment approaches and might provide an overall therapeutic benefit to improve the long-term outcomes of patients with MDD.

Endothelial cell activation and glycocalyx shedding - potential as biomarkers in patients with lupus nephritis

Lupus nephritis (LN) is a common and severe manifestation of systemic lupus erythematosus and an important cause of acute and chronic kidney injury. Early diagnosis of LN and preventing relapses are key to preserving renal reserve. However, due to the complexity and heterogeneity of the disease, clinical management remains challenging. Kidney biopsy remains the gold standard for confirming the diagnosis of LN and subsequent assessment of kidney histopathology, but it is invasive and cannot be repeated frequently. Current clinical indicators of kidney function such as proteinuria and serum creatinine level are non-specific and do not accurately reflect histopathological changes, while anti-dsDNA antibody and C3 levels reflect immunological status but not kidney injury. Identification of novel and specific biomarkers for LN is prerequisite to improve management. Renal function deterioration is associated with changes in the endothelial glycocalyx, a delicate gel-like layer located at the interface between the endothelium and bloodstream. Inflammation induces endothelial cell activation and shedding of glycocalyx constituents into the circulation. This review discusses the potential role of soluble glycocalyx components as biomarkers of active LN, especially in patients in whom conventional serological and biochemical markers do not appear helpful.

Mining Autoimmune-Disorder-Linked Molecular-Mimicry Candidates in Clostridioides difficile and Prospects of Mimic-Based Vaccine Design: An In Silico Approach

Molecular mimicry, a phenomenon in which microbial or environmental antigens resemble host antigens, has been proposed as a potential trigger for autoimmune responses. In this study, we employed a bioinformatics approach to investigate the role of molecular mimicry in Clostridioides difficile-caused infections and the induction of autoimmune disorders due to this phenomenon. Comparing proteomes of host and pathogen, we identified 23 proteins that exhibited significant sequence homology and were linked to autoimmune disorders. The disorders included rheumatoid arthritis, psoriasis, Alzheimer's disease, etc., while infections included viral and bacterial infections like HIV, HCV, and tuberculosis. The structure of the homologous proteins was superposed, and RMSD was calculated to find the maximum deviation, while accounting for rigid and flexible regions. Two sequence mimics (antigenic, non-allergenic, and immunogenic) of ≥10 amino acids from these proteins were used to design a vaccine construct to explore the possibility of eliciting an immune response. Docking analysis of the top vaccine construct C2 showed favorable interactions with HLA and TLR-4 receptor, indicating potential efficacy. The B-cell and T-helper cell activity was also simulated, showing promising results for effective immunization against C. difficile infections. This study highlights the potential of C. difficile to trigger autoimmunity through molecular mimicry and vaccine design based on sequence mimics that trigger a defensive response.

An update on autoantibodies in systemic lupus erythematosus

PURPOSE OF REVIEW

Autoantibodies are cornerstone biomarkers in systemic lupus erythematosus (SLE), an autoimmune disease characterized by autoantibody-mediated tissue damage. Autoantibodies can inform about disease susceptibility, clinical course, outcomes and the cause of SLE. Identifying pathogenic autoantibodies in SLE, however, remains a significant challenge. This review summarizes recent advances in the field of autoantibodies in SLE.

RECENT FINDINGS

High-throughput technologies and innovative hypothesis have been applied to identify autoantibodies linked to pathogenic pathways in SLE. This work has led to the discovery of functional autoantibodies targeting key components is SLE pathogenesis (e.g. DNase1L3, cytokines, extracellular immunoregulatory receptors), as well as the identification of endogenous retroelements and interferon-induced proteins as sources of autoantigens in SLE. Others have reinvigorated the study of mitochondria, which has antigenic parallels with bacteria, as a trigger of autoantibodies in SLE, and identified faecal IgA to nuclear antigens as potential biomarkers linking gut permeability and microbial translocation in SLE pathogenesis. Recent studies showed that levels of autoantibodies against dsDNA, C1q, chromatin, Sm and ribosomal P may serve as biomarkers of proliferative lupus nephritis, and identified novel autoantibodies to several unique species of Ro52 overexpressed by SLE neutrophils.

SUMMARY

Autoantibodies hold promise as biomarkers of pathogenic mechanisms in SLE.

Neuropsychiatric lupus erythematosus: Focusing on autoantibodies

Patients with systemic lupus erythematosus (SLE) frequently suffer from nervous system complications, termed neuropsychiatric lupus erythematosus (NPLE). NPLE accounts for the poor prognosis of SLE. Correct attribution of NP events to SLE is the primary principle in managing NPLE. The vascular injuries and neuroinflammation are the fundamental neuropathologic changes in NPLE. Specific autoantibody-mediated central nerve system (CNS) damages distinguish NPLE from other CNS disorders. Though the central antibodies in NPLE are generally thought to be raised from the periphery immune system, they may be produced in the meninges and choroid plexus. On this basis, abnormal activation of microglia and disease-associated microglia (DAM) should be the common mechanisms of NPLE and other CNS disturbances. Improved understanding of both characteristic and sharing features of NPLE might yield further options for managing this disease.

Abnormal Mitochondrial Physiology in the Pathogenesis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by abnormalities within the innate and adaptive immune systems. Activation and proliferation of a wide array of immune cells require significant up-regulation in cellular energy metabolism, with the mitochondria playing an essential role in the initiation and maintenance of this response. This article highlights how abnormal mitochondrial function may occur in SLE and focuses on how energy metabolism, oxidative stress, and impaired mitochondrial repair play a role in the pathogenesis of the disease. How this may represent an appealing novel therapeutic target for future drug therapy in SLE also is discussed.

Effects of Atorvastatin on T-Cell Activation and Apoptosis in Systemic Lupus Erythematosus and Novel Simulated Interactions With C-Reactive Protein and Interleukin 6

Objective

We study activation of T helper 17 (Th17) and regulatory T (Treg) cells and induction of apoptosis in cells from patients with systemic lupus erythematosus (SLE) compared with controls and effects of atorvastatin and its simulated interactions with other compounds.

Methods

Mononuclear cells from 10 patients with SLE and 10 controls were cultured in conditions that induce Th17 and/or Treg cell polarization and/or apoptosis and were studied by FACScan. Gene expression was determined by quantitative real‐time reverse transcription–polymerase chain reaction. Cytokines in plasma were determined by enzyme‐linked immunosorbent assay. The Search Tool for Interactions of Chemicals (STITCH) was used to retrieve information regarding the binding properties of atorvastatin.

Results

Among patients with SLE, the proportion of Th17 (CD4⁺IL17⁺) cells was higher compared with controls after activation, with Th17 or Treg polarizing cytokines, phorbol myristate acetate, and ionomycin. In contrast, Treg cells (CD4⁺CD25⁺CD127^dim/−) frequencies were lower. CD95 stimulation induced relatively more apoptosis in Treg cells and less in Th17 cells, as compared with controls. Addition of atorvastatin normalized Th17/Treg cell balance and apoptosis induction. Accordingly, the ratio of RORC/FoxP3 decreased in patients with SLE. Interleukin 17 and interleukin 6 (IL‐6) levels were increased in patients with SLE. Atorvastatin interacted strongly with C‐reactive protein (CRP) and also significantly with IL‐6.

Conclusion

There is a higher proportion of Th17 cells and a lower proportion of Treg cells in patients with SLE after activation. Th17 cells were more resistant than Treg cells to CD95‐induced apoptosis in SLE. Atorvastatin normalized these effects. Our findings reveal a novel mechanism behind the imbalance of Th17/Treg cells with implications for treatment in SLE. We determine for the first time simulated interaction between atorvastatin, CRP, and IL‐6, implying a novel role of atorvastatin.

Sperm-bound antisperm antibodies are associated with poor cryosurvival of stallion spermatozoa

Different stallions exhibit a high level of variation in the ability of their sperm to survive cryopreservation. A large fraction of stallions show poor post-thaw sperm motility, and their semen is not suitable for commercial freezing. In this study, we hypothesized that the presence of sperm-bound antisperm antibodies (ASAs) was associated with poor cryosurvival of stallion sperm. Our objective was to assess the level of ASA binding to stallion sperm, and determine if it was associated with good or poor sperm cryosurvival. In Experiment 1, cooled shipped semen from 27 stallions was frozen using three commercial semen extenders. Sperm motility, membrane integrity, acrosome integrity and apoptosis were evaluated before and after freezing for each aliquot. In addition, the percentage of ASA-bound sperm was evaluated post-thaw. In Experiment 2, semen from 22 stallions was frozen immediately after collection a single formulation of semen extender. Sperm motility and ASA binding were evaluated post-thaw. The results of both experiments showed similar findings. The frequency of ASA-positive samples was higher among stallions with poor sperm cryosurvival (Exp. 1 and 2 = 6/11, 54.5%) than for good sperm cryosurvival (Exp. 1 = 0/16, 0%; Exp. 2 = 1/11, 9.1%). The percentage of IgG- and IgA-bound sperm was also higher in stallions with poor sperm cryosurvival in both experiments (P < 0.05). Post-thaw sperm motility, velocity and distance parameters were lower in ASA-positive than ASA-negative stallions (P < 0.005). No effect of the semen extender used was observed. In addition, stallions with ASAs had a higher percentage of apoptotic sperm than stallions without ASAs. The presence of sperm-bound ASAs was associated with poor cryosurvival for stallion spermatozoa. Thus, it may be beneficial to evaluate stallions for binding of ASAs prior to freezing to offer and indicator of the prognosis for cryosurvival.

Cardiovascular Consequences of Autoimmune Rheumatic Diseases

The increased risk of cardiovascular disease (CVD) among patients with autoimmune rheumatic diseases such as rheumatoid arthritis, spondyloarthritis and systemic lupus erythematosus has been extensively documented. Sub-clinical atherosclerosis can be assessed using various non-invasive imaging techniques. However, the mechanisms underlying the higher risk of atherosclerotic CVD in patients with autoimmune rheumatic diseases are not fully known, although they seem to include chronic low-grade systemic inflammation leading to prolonged endothelial activation, accompanied by a pro-thrombotic/pro-coagulant and autoantibody state. Furthermore, sub-clinical atherosclerosis is also influenced by other traditional risk factors for CVD. Including the individual components of the metabolic syndrome (MetS: obesity, impaired glucose metabolism, dyslipidemia and high blood pressure), the degree of which is higher in these patients than in controls. The aim of this narrative review is to discuss the CV manifestations and risk factors involved in the increased risk of CVD among patients with autoimmune rheumatic diseases.

Vaccination Strategies and Immune Modulation of Atherosclerosis

Adaptive as well as innate immune responses contribute to the development of atherosclerosis. Studies performed in experimental animals have revealed that some of these immune responses are protective while others contribute to the progression of disease. These observations suggest that it may be possible to develop novel therapies for cardiovascular disease by selectively modulating such atheroprotective and proatherogenic immunity. Recent advances in cancer treatment using immune check inhibitors and CAR (chimeric antigen receptor) T-cell therapy serve as excellent examples of the possibilities of targeting the immune system to combat disease. LDL (low-density lipoprotein) that has accumulated in the artery wall is a key autoantigen in atherosclerosis, and activation of antigen-specific T helper 1–type T cells is thought to fuel plaque inflammation. Studies aiming to prove this concept by immunizing experimental animals with oxidized LDL particles unexpectedly resulted in activation of atheroprotective immunity involving regulatory T cells. This prompted several research groups to try to develop vaccines against atherosclerosis. In this review, we will discuss the experimental and clinical data supporting the possibility of developing immune-based therapies for lowering cardiovascular risk. We will also summarize ongoing clinical studies and discuss the challenges associated with developing an effective and safe atherosclerosis vaccine.

Anti-mitochondrial autoantibodies in systemic lupus erythematosus and their association with disease manifestations

Mitochondria are organelles that govern energy supply and control cell death. Mitochondria also express bacterial features, such as the presence of inner membrane cardiolipin and a circular genome rich in hypomethylated CpG motifs. While mitochondrial extrusion by damaged organs or activated cells is thought to trigger innate immunity, it is unclear whether extracellular mitochondria also stimulate an adaptive immune response. We describe the development of novel assays to detect autoantibodies specific to two distinct components of the mitochondrion: the mitochondrial outer membrane and mitochondrial DNA. Antibodies to these two mitochondrial constituents were increased in both human and murine systemic lupus erythematosus (SLE), compared to controls, and were present at higher levels than in patients with antiphospholipid syndrome or primary biliary cirrhosis. In both bi- and multi-variate regression models, antibodies to mitochondrial DNA, but not whole mitochondria, were associated with increased anti-dsDNA antibodies and lupus nephritis. This study describes new and optimized methods for the assessment of anti-mitochondrial antibodies, and demonstrates their presence in both human and murine SLE. These findings suggest that different mitochondrial components are immunogenic in SLE, and support the concept that extracellular mitochondria may provide an important source of circulating autoantigens in SLE.

Relationship between serum vascular cell adhesion molecule-1 and endothelin-1 levels with organ involvement and disease activity in systemic lupus erythematosus patients

Background

Endothelial dysfunction plays an important role in pathogenesis of systemic lupus erythematosus (SLE). Considering the importance of serum soluble vascular cell adhesion molecule-1 as the most abundant of the circulating adhesion molecules increased as a result of endothelial dysfunction and the role of endothelin-1 in pathophysiology of SLE, this study aimed to evaluate serum soluble vascular cell adhesion molecule-1 and endothelin-1 levels in SLE patients compared to healthy subjects.

Methods

In this cross-sectional study, 60 SLE patients according to the Systemic Lupus International Collaborating Clinics classification criteria for SLE and 40 age and sex-matched healthy controls were included. In patients, clinical examination was performed and SLE disease activity index was assessed. Serum endothelin-1 and soluble vascular cell adhesion molecule-1 levels were measured using ELISA kits.

Results

The mean ± standard deviation age of patients and controls was 31.91 ± 7.66 and 33.20 ± 10.08 years, respectively. Compared to healthy controls, serum soluble vascular cell adhesion molecule-1 (1023.8 ± 352.96 vs. 866.06 ± 109.91) and endothelin-1 (77.83 ± 16.27 vs. 54.45 ± 12.01) was significantly higher in SLE patients ( P = 0.003 and P < 0.001, respectively). The most common organs involved in patients were skin, joint and kidney. There were no significant differences in serum soluble vascular cell adhesion molecule-1 and endothelin-1 levels according to organ involvement, activity of disease and the conventional serum markers of disease activity ( P > 0.05). There was no significant correlation between disease activity, organ involvement and negative or positivity of autoantibodies as well as serum complement with endothelin-1 and vascular cell adhesion molecule-1 levels ( P > 0.05).

Conclusions

Although our study revealed higher serum soluble vascular cell adhesion molecule-1 and endothelin-1 levels in SLE patients compared to healthy controls, there were no significant correlations between their serum levels with organ involvement and disease activity.

Multiple target autoantigens on endothelial cells identified in juvenile dermatomyositis using proteomics

Objective

Although generally classified within the group of inflammatory myopathies, JDM displays many pathological features of vasculitis. Previous work has shown that AECA are abundant in other forms of vasculitis. We therefore investigated whether such antibodies might also be detected in JDM.

Methods

We screened plasma from children with JDM for the presence of AECA by western blotting and 2D gel electrophoresis (2DE) using proteins extracted from human aortic endothelial cells as the substrate. We performed mass spectrometry to identify candidate antigens from 2DE gels and used ELISA to confirm the presence of specific antibodies.

Results

We identified 22 candidate target autoantigens for AECA probed with JDM plasma. Interestingly, 17 of these 22 target antigens were proteins associated with antigen processing and protein trafficking. ELISA confirmed the presence of antibodies to heat shock cognate 71 kDa protein in JDM plasma, particularly in children with active, untreated disease.

Conclusion

Children with JDM express antibodies to autoantigens in endothelial cells. The clinical and pathological significance of such autoantibodies require further investigation.

Oxidative Stress Induces HSP90 Upregulation on the Surface of Primary Human Endothelial Cells: Role of the Antioxidant 7,8-Dihydroxy-4-methylcoumarin in Preventing HSP90 Exposure to the Immune System

We have previously demonstrated that human heat shock protein 90 (HSP90), an intracellular self protein, is the target of cellular and humoral autoimmune responses in patients with carotid atherosclerosis. In this study, we evaluated in vitro whether oxidative stress, a feature of atherosclerotic plaque, alters HSP90 expression in endothelial cells, thus inducing surface localization of this molecule and whether the antioxidant compound 7,8-dihydroxy-4-methylcoumarin (7,8-DHMC) is able to prevent oxidative stress-induced alterations of HSP90 localization. By the use of flow cytometry, immunofluorescence, enzyme-linked immunosorbent assay, and semiquantitative reverse-transcription polymerase chain reaction, we demonstrated that exposure of human umbilical vein endothelial cells (HUVEC) to the prooxidant compound H₂O₂ upregulated HSP90 surface expression and reduced its secretion without altering HSP90 gene expression and intracytoplasmic protein levels. Pretreatment of HUVEC with 7,8-DHMC prevented H₂O₂-induced alterations of HSP90 cellular distribution and secretion. Our results suggest that the strong oxidative conditions of atherosclerotic plaques promote the upregulation of HSP90 surface expression on endothelial cells, thus rendering the protein a possible target of autoimmune reactions. The antioxidant 7,8-DHMC, by preventing oxidative-stress-triggered HSP90 surface upregulation, may be useful to counteract possible autoreactive reactions to HSP90.

Cardiovascular disease in systemic lupus erythematosus: A comprehensive update

Heightened rates of both cardiovascular (CV) events and subclinical atherosclerosis, documented by imaging and vascular function techniques are well established in systemic lupus erythematosus (SLE). While traditional CV factors such as smoking, dyslipidemia, diabetes mellitus (DM), hypertension, central obesity and hyperhomocysteinemia have been reported to be prevalent in lupus patients, they do not fully explain the high rates of ischemic events so far reported, implying that other factors inherent to disease itself could account for the enhanced risk, including disease duration, activity and chronicity, psychosocial factors, medications, genetic variants and altered immunological mechanisms. Though the exact pathogenesis of atherosclerosis in the setting of lupus remains ill defined, an imbalance between endothelial damage and atheroprotection seems to be a central event. Insults leading to endothelial damage in the setting of lupus include oxidized low density lipoprotein (oxLDL), autoantibodies against endothelial cells and phospholipids, type I interferons (IFN) and neutrophil extracellular traps (NETs) directly or through activation of type I IFN pathway. Increased oxidative stress, reduced levels of the normally antioxidant high density lipoprotein (HDL), increased levels of proinflammatory HDL (piHDL) and reduced paraoxonase activity have been related to increased oxLDL levels. On the other hand, impaired atheroprotective mechanisms in lupus include decreased capacity of endothelial repair-partly mediated by type I IFN- and dampened production of atheroprotective autoantibodies. In the present review, traditional and disease related risk factors for CV disease (CVD) in the setting of chronic autoimmune disorders with special focus on SLE will be discussed.

Detection of Antibodies In Vitro Binding to Endothelial Cells in the Sera from Women with Normal Pregnancy and Preeclampsia

Activity of serum antibodies in vitro binding to endothelial cells in women with normal pregnancy and preeclampsia was studied. Flow cytometry detected peculiarities of antibody binding to endothelial cells in health and disease. Detection of antiendothelial antibodies in trimesters II and III can be diagnostically important in preeclampsia.

Anti-citrullinated protein antibodies promote apoptosis of mature human Saos-2 osteoblasts via cell-surface binding to citrullinated heat shock protein 60

We hypothesized that anti-citrullinated protein antibodies (ACPAs) react with osteoblast surface citrullinated proteins and affect cell function, leading to joint damage in patients with rheumatoid arthritis (RA). First, we purified ACPAs by cyclic citrullinated peptide (CCP)-conjugated affinity column chromatography. The cognate antigens of ACPAs on Saos-2 cells, a sarcoma osteogenic cell line generated from human osteoblasts, were probed by ACPAs, and the reactive bands were analyzed using proteomic analyses. We found that ACPAs bind to Saos-2 cell membrane, and several protein candidates, including HSP60, were identified. We then cloned and purified recombinant heat shock protein 60 (HSP60) and citrullinated HSP60 (citHSP60) and investigated the effect of ACPAs on Saos-2 cell. We confirmed that HSP60 obtained from Saos-2 cell membrane were citrullinated and reacted with ACPAs, which induces Saos-2 cells apoptosis via binding to surface-expressed citHSP60 through Toll-like receptor 4 signaling. ACPAs promoted interleukin (IL)-6 and IL-8 expression in Saos-2 cells. Finally, sera from patients with RA and healthy controls were examined for their titers of anti-HSP60 and anti-citHSP60 antibodies using an enzyme-linked immunosorbent assay. The radiographic change in patients with RA was evaluated using the Genant-modified Sharp scoring system. Patients with RA showed higher sera titers of anti-citHSP60, but not anti-HSP60, antibodies when compared with controls. In addition, the anti-citHSP60 level was positively associated with increased joint damage in patients with RA. In conclusion, Saos-2 cell apoptosis was mediated by ACPAs via binding to cell surface-expressed citHSP60 and the titer of anti-citHSP60 in patients with RA positively associated with joint damage.

Identification of target antigens of naturally occurring autoantibodies in cerebrospinal fluid

Naturally occurring autoantibodies have natural physiologic functions related to normal cell processes. However, the repertoire of naturally occurring autoantibodies against neuronal antigens in CSF is unclear. The purpose of this study was to identify naturally occurring autoantibodies against neuronal antigens in CSF from patients with various neurologic diseases by proteomics-based analysis. The CSF samples were collected from 77 patients with various neurologic disorders. The antigen source for 2-dimensional immunoblotting was the SH-SY5Y human neuroblastoma cell line. There were 8 spots recognized in CSF from more than one-fourth of the 77 patients including all patient groups and these spots were recognized in intravenous immunoglobulin preparations. These antigen spots were identified as heat shock 105-kDa/110-kDa protein 1, isoform CRA_b, 78-kDa glucose-regulated protein, heat shock cognate 71-kDa protein, tubulin beta chain, vimentin (2 spots), and 60-kDa heat shock protein, mitochondrial; we could not identify the protein name corresponding to 1 of the 8 spots. In summary, there were 6 proteins identified that were main target antigens that reacted with naturally occurring autoantibodies in CSF from patients with varied neurologic disorders; the functions of autoantibodies against the identified antigens are unknown and may be clarified with further studies.

BIOLOGICAL SIGNIFICANCE

Naturally occurring autoantibodies may have important functions in tissue homeostasis. In this study, we identified 6 common target antigens that reacted with autoantibodies in cerebrospinal fluid (CSF) from patients, independent of disease type. These findings may clarify the importance of naturally occurring autoantibodies in CSF and the use of these antibodies potentially may be a novel therapy for various neurologic disorders.

Association between panel reactive antibody and antiendothelial cell antibody positivity in kidney transplant patients

OBJECTIVES

Endothelium is the major tissue for hyperacute and acute rejection. Binding of antibody to endothelium activates several immunologic mechanisms. Antiendothelial cell antibodies are a group of nonhuman leukocyte antigen antibodies that may play a role in the induction of an immunologic reaction that triggers inflammation. The aim of this study was to investigate whether there was an association between antiendothelial cell antibody positivity and panel reactive antibody positivity in renal transplant patients.

MATERIALS AND METHODS

In this study, we investigated the association between antiendothelial cell antibodies and panel reactive antibody Class I class II crossmatch positivity in patients, and compared these results with results from 100 healthy volunteers. All serum samples were analyzed by bead-based technology for calculated panel reactive antibody positivity; in addition, slides were used, each containing human umbilical vein endothelial cells and capillary-rich tissue for antiendothelial cell antibody positivity.

RESULTS

Antiendothelial cell antibodies was positive in 48 of 89 patients (panel reactive antibody Class I class II negative), 22 of 35 patients (class I-positive), 25 of 39 patients (class II-positive), 26 of 40 (class I class II positive), and 37 of 57 serologic and flow cytometry crossmatch-positive patients (P ≤ .016), and ultimately, in 122 of 205 patients and 25 of 100 volunteers (P ≤ .001). Antiendothelial cell antibody positivity was more frequent in panel reactive antibody-positive than negative patients and the control group.

CONCLUSIONS

Binding of antiendothelial cell antibodies to endothelial cells may activate complement by the classical pathway and cause upregulation of adhesion molecules. This study questioned the antigenic specificity of antiendothelial cell antibodies. Our study results showed that antiendothelial cell antibodies may play an important role for graft destruction, independent of panel reactive antibody and crossmatch positivity.

Connective tissue disease-associated pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by vascular remodeling of pulmonary arterioles that leads to increased pulmonary vascular resistance, right heart failure, and death. It is associated with connective tissue diseases, including systemic sclerosis, systemic lupus erythematosus, and mixed connective tissue disease. PAH is characterized by dyspnea on exertion and fatigue. Syncopal events suggest severe disease. Patients may present with signs of right heart failure. One- and 3-year survival rates are approximately 81% and 52%, respectively. Given the high prevalence and mortality, algorithms for screening are currently under investigation and will hopefully lead to earlier diagnosis and improved survival.

[Atherosclerosis in systemic lupus erythematosus]

CONTEXT

Evidence from epidemiological studies demonstrates that patients with systemic lupus erythematosus (SLE) are at increased risk for the development of cardiovascular disease. Traditional cardiovascular risk factors' play an important role in this phenomenon but do not account for the entire risk in lupus patients.

OBJECTIVES

The incidence and prevalence of cardiovascular events and infraclinical atherosclerosis are reviewed. Combinations of traditional risk factors with lupus-specific and treatment-related variables are detailed.

RESULTS

Atherosclerosis is more prevalent and occurs prematurely in lupus patients. Relative risk of myocardial infarction is between 5 to 8 times greater that of general population, and may exceed 50 in women between 35 and 44 years old. SLE was also found as an independent risk factor for subclinical atherosclerosis, and more than one third of lupus patient show evidence of carotid plaques of coronary artery calcifications. Lupus patients have more frequent traditional risk factors compared with general population of similar age and sex. Besides the traditional risk factors, SLE specific risk factors have been identified among witch advanced age at diagnosis, current disease activity, duration of the disease and renal activity. Moreover, lipid abnormalities in patients with SLE are common and likely are one of the major causes of premature atherosclerosis in these patients; the dyslipoprotein associated increased triglycerides and depressed HDL-cholesterol with proinflammatory HDL production. Autoimmunity may have a part of responsibility, but data's in favour of this hypothesis are not strong. Other mechanisms such as vascular inflammation, oxidative stress, immune complexes and complement activation may also elicit endothelial damage and promote atherosclerosis are associated with the pathogenesis of both SLE and atherosclerosis. Steroids may have a true double-edged role with a pro-atherogenic risk regarding the exacerbation of metabolic risk factors and a "beneficial" anti-inflammatory role. It is becoming increasingly apparent that antimalarials treatment in SLE has an atheroprotective and a cardioprotective effect. The other immunosuppressive drugs may reduce progression of atherosclerosis and cardiovascular events but their precise role remains to be elucidated. Despite their role in primary prevention in target general population, for now, systematic prescription of statins does not show a great benefit in the cardiovascular risk in lupus patients.

CONCLUSION

Mechanisms of atherosclerosis in SLE remain elusive. It is partially explained by the interaction of traditional cardiovascular risk factors, lupus-specific factors and therapy specially corticosteroids. Management strategies of lupus should include early all those items.

An innovative method to identify autoantigens expressed on the endothelial cell surface: serological identification system for autoantigens using a retroviral vector and flow cytometry (SARF)

Autoantibodies against integral membrane proteins are usually pathogenic. Although anti-endothelial cell antibodies (AECAs) are considered to be critical, especially for vascular lesions in collagen diseases, most molecules identified as autoantigens for AECAs are localized within the cell and not expressed on the cell surface. For identification of autoantigens, proteomics and expression library analyses have been performed for many years with some success. To specifically target cell-surface molecules in identification of autoantigens, we constructed a serological identification system for autoantigens using a retroviral vector and flow cytometry (SARF). Here, we present an overview of recent research in AECAs and their target molecules and discuss the principle and the application of SARF. Using SARF, we successfully identified three different membrane proteins: fibronectin leucine-rich transmembrane protein 2 (FLRT2) from patients with systemic lupus erythematosus (SLE), intercellular adhesion molecule 1 (ICAM-1) from a patient with rheumatoid arthritis, and Pk (Gb3/CD77) from an SLE patient with hemolytic anemia, as targets for AECAs. SARF is useful for specific identification of autoantigens expressed on the cell surface, and identification of such interactions of the cell-surface autoantigens and pathogenic autoantibodies may enable the development of more specific intervention strategies in autoimmune diseases.

Improved Metabolic Control in Diabetes, HSP60, and Proinflammatory Mediators

The diabetes-atherosclerosis relationship remains to be fully defined. Repeated prolonged hyperglycemia, increased ROS production and endothelial dysfunction are important factors. One theory is that increased blood levels of heat shock protein (HSP)60 are proinflammatory, through activation of innate immunity, and contribute to the progression of vascular disease. It was hypothesized that improvement of diabetes control in patients presenting with metabolic syndrome would lower HSP60, and anti-HSP60 antibody levels and decrease inflammatory markers. Paired sera of 17 Italian patients, before and after intensive treatment, were assayed for cytokines, HSP60 and anti-HSP60 antibodies. As expected, intensive treatment was associated with a decrease in HgbA1C (P < 0.001) and BMI (P < 0.001). After treatment, there was a significant decrease in IL-6 (P < 0.05). HSP60 levels were before treatment −6.9 + 1.9, after treatment −7.1 + 2.0 ng/mL (P = ns). Overall HSP60 concentrations were lower than published reports. Anti-HSP60 antibody titers were high and did not decrease with treatment. In conclusion, improvement of diabetic control did not alter HSP60 concentrations or antiHSP60 antibody titers, but led to a reduction of IL-6 levels.

A novel autoantibody against fibronectin leucine-rich transmembrane protein 2 expressed on the endothelial cell surface identified by retroviral vector system in systemic lupus erythematosus

Introduction

Anti-endothelial cell antibodies (AECAs) are thought to be critical for vasculitides in collagen diseases, but most were directed against molecules localized within the cell and not expressed on the cell surface. To clarify the pathogenic roles of AECAs, we constructed a retroviral vector system for identification of autoantigens expressed on the endothelial cell surface.

Methods

AECA activity in sera from patients with collagen diseases was measured with flow cytometry by using human umbilical vein endothelial cells (HUVECs). A cDNA library of HUVECs was retrovirally transfected into a rat myeloma cell line, from which AECA-positive clones were sorted with flow cytometry. cDNA of the cells was analyzed to identify an autoantigen, and then the clinical characteristics and the functional significance of the autoantibody were evaluated.

Results

Two distinct AECA-positive clones were isolated by using serum immunoglobulin G (IgG) from a patient with systemic lupus erythematosus (SLE). Both clones were identical to cDNA of fibronectin leucine-rich transmembrane protein 2 (FLRT2). HUVECs expressed FLRT2 and the prototype AECA IgG bound specifically to FLRT2-transfected cells. Anti-FLRT2 antibody activity accounted for 21.4% of AECAs in SLE. Furthermore, anti-FLRT2 antibody induced complement-dependent cytotoxicity against FLRT2-expressing cells.

Conclusions

We identified the membrane protein FLRT2 as a novel autoantigen of AECAs in SLE patients by using the retroviral vector system. Anti-FLRT2 antibody has the potential to induce direct endothelial cell cytotoxicity in about 10% of SLE patients and could be a novel molecular target for intervention. Identification of such a cell-surface target for AECAs may reveal a comprehensive mechanism of vascular injury in collagen diseases.

Contributions of mass spectrometry-based proteomics to defining cellular mechanisms and diagnostic markers for systemic lupus erythematosus

Systematic lupus erythematosus (SLE) is a complex disease for which molecular diagnostics are limited and pathogenesis is not clearly understood. Important information is provided in this regard by identification and characterization of more specific molecular and cellular targets in SLE immune cells and target tissue and markers of early-onset and effective response to treatment of SLE complications. In recent years, advances in proteomic technologies and applications have facilitated such discoveries. Here we provide a review of insights into SLE pathogenesis, diagnosis and treatment that have been provided by mass spectrometry-based proteomic approaches.

HSP60: issues and insights on its therapeutic use as an immunoregulatory agent

Heat shock proteins 60 (HSP60) is one of the most well studied member of the HSP family. Although found to be a target self antigen in pathological autoimmunity and HSP60-reactive T and B cells are part of immune responses in several infectious diseases, there is consistent experimental evidence that HSP60 displays dominant immunoregulatory properties. There are a series of reports on animal models showing that the administration of HSP60 can modulate inflammatory diseases. However, HSP60 has both immune-regulatory and inflammatory properties placing it as an essentially homeostatic antigen, but with potentially harmful effects as well. There have been a series of reports on the successful use of HSP60 and its peptides as immune-modulatory agent for several models of autoimmune diseases and in some clinical trials as well. We believe that the potential risks of HSP60 as a therapeutic agent can be controlled by addressing important factors determining its effects. These factors would be route of administration, appropriate peptides, time point of administration in the course of the disease, and possible association with other modulatory agents.

Association of autoantibodies to heat-shock protein 60 with arterial vascular events in patients with antiphospholipid antibodies

OBJECTIVE

Anti-heat shock protein 60 autoantibodies (anti-Hsp60) are associated with cardiovascular disease and are known to affect endothelial cells in vitro, and we have recently shown that anti-Hsp60 promote thrombosis in a murine model of arterial injury. Based on those findings, we undertook the present study to investigate the hypothesis that the presence of anti-Hsp60, alone or in combination with other thrombogenic risk factors, is associated with an elevated risk of vascular events.

METHODS

The study population was derived from 3 ongoing cohort studies: 2 independent systemic lupus erythematosus (SLE) registries and 1 cohort comprising SLE patients and non-SLE patients. Data from a total of 402 participants were captured; 199 of these participants had had confirmed vascular events (arterial vascular events in 102, venous vascular events in 76, and both arterial and venous vascular events in 21). Anti-Hsp60 were detected by enzyme-linked immunoassay, and association with vascular events was assessed by regression analysis.

RESULTS

Multiple regression analysis revealed that arterial vascular events were associated with male sex, age, and hypertension. Analyses of the vascular events according to their origin showed an association of anti-Hsp60 with arterial vascular events (odds ratio 2.26 [95% confidence interval 1.13-4.52]), but not with venous vascular events. Anti-Hsp60 increased the risk of arterial vascular events (odds ratio 5.54 [95% confidence interval 1.89-16.25]) in antiphospholipid antibody (aPL)-positive, but not aPL-negative, individuals.

CONCLUSION

We demonstrate that anti-Hsp60 are associated with an increased risk of arterial vascular events, but not venous vascular events, in aPL-positive individuals. These data suggest that anti-Hsp60 may serve as a useful biomarker to distinguish risk of arterial and venous vascular events in patients with aPL.

Peroxiredoxin 2 is a novel autoantigen for anti-endothelial cell antibodies in systemic vasculitis

Anti-endothelial cell antibodies (AECA) have been frequently detected in systemic vasculitis, which affects blood vessels of various sizes. To understand the pathogenic roles of AECA in systemic vasculitis, we attempted to identify target antigens for AECA comprehensively by a proteomic approach. Proteins extracted from human umbilical vein endothelial cells (HUVEC) were separated by two-dimensional electrophoresis, and Western blotting was subsequently conducted using sera from patients with systemic vasculitis. As a result, 53 autoantigenic protein spots for AECA were detected, nine of which were identified by mass spectrometry. One of the identified proteins was peroxiredoxin 2 (Prx2), an anti-oxidant enzyme. Frequency of anti-Prx2 autoantibodies, measured by enzyme-linked immunosorbent assay (ELISA), was significantly higher in systemic vasculitis (60%) compared to those in collagen diseases without clinical vasculitis (7%, P < 0·01) and healthy individuals (0%, P < 0·01). Further, the titres changed in parallel with the disease activity during time-courses. The presence of anti-Prx2 autoantibodies correlated significantly with elevation of serum d-dimers and thrombin-antithrombin complex (P < 0·05). Immunocytochemical analysis revealed that live endothelial cells expressed Prx2 on their surface. Interestingly, stimulation of HUVEC with rabbit anti-Prx2 antibodies increased secretion of interleukin (IL)-6, IL-1β, IL-1ra, growth regulated oncogene (GRO)-α, granulocyte colony-stimulating factor (G-CSF), granulocyte macrophage colony-stimulating factor (GM-CSF), IL-8 and monocyte chemoattractant protein (MCP)-1 more than twofold compared to that of with rabbit immunoglobulin (Ig)G. Taken together, our data suggest that anti-Prx2 autoantibodies would be a useful marker for systemic vasculitis and would be involved in the inflammatory processes of systemic vasculitis.

The HSP60 immune system network

Heat shock proteins (HSPs) were initially discovered as participants in the cellular response to stress. It is now clear, however, that self and microbial HSPs also play an important role in the control of the immune response. Here, we focus on HSP60 and its interactions with both the innate and adaptive immune system in mammals. We also consider that circulating HSP60 and the quantities and specificities of serum antibodies to HSP60 provide a biomarker to monitor the immune status of the individual. Thus, the dual role of HSP60 as an immune modulator and a biomarker, provides an opportunity to modulate immunity for therapeutic purposes, and to monitor the immune response in health and disease.

Elevated anti-heat shock protein 60 antibody titer is related to white matter hyperintensities

BACKGROUND

There are many reports that the antibody against heat shock protein 60 (Hsp60) is present in most patients with coronary artery disease and atherosclerosis, and that its titer correlates with disease severity. However, few reports have described the association between anti-Hsp60 antibody and cerebrovascular disease.

METHODS

We determined the anti-Hsp60 antibody titer in patients with neurologic diseases and healthy subjects using enzyme-linked immunosorbent assay (ELISA) and evaluated their findings of brain magnetic resonance imaging (MRI) of the white matter. White matter hyperintensities (WMHs) on T2-weighted and fluid-attenuated inversion recovery (FLAIR) images were classified into 2 categories: periventricular hyperintensity (PVH) and deep white matter hyperintensity (DWMH). The lesions in each category were then divided into 4 grades (grades 0-3) according to the Fazekas rating scale.

RESULTS

There were no significant differences in the titer between patients with neurologic diseases and healthy subjects. The mean grade of DWMHs (mean ± SD, 1.56 ± 0.70) was significantly higher in 18 subjects in the high-titer group (≥39.8 ng/mL; mean titer + 2 SD in sera from 23 healthy subjects) than in 86 subjects (mean ± SD, 0.09 ± 0.76) in the normal-titer group (<39.8 ng/mL; P < .003). The mean grade of PVHs (mean ± SD, 1.50 ± 0.71) was also significantly higher in the high-titer group than in the normal-titer group (mean ± SD, 1.17 ± 0.62; P < .02).

CONCLUSIONS

A significant correlation was noted between anti-Hsp60 antibody titer and the severity of WMHs on brain MR images. We suggest that an elevated titer of the anti-Hsp60 antibody could be a risk factor for cerebral small-vessel disease.

IgA anti-beta2-glycoprotein I autoantibodies are associated with an increased risk of thromboembolic events in patients with systemic lupus erythematosus

BACKGROUND

The clinical utility of testing for antiphospholipid antibodies (aPL) of IgA isotype remains controversial.

METHODOLOGY/PRINCIPAL FINDINGS

To address this issue, we reasoned that if IgA aPL contribute to the clinical manifestations of the antiphospholipid syndrome, then an association with thromboembolic events should manifest in patients whose only aPL is of IgA isotype. We performed a retrospective chart review of 56 patients (31 with systemic lupus erythematosus [SLE] and 25 without SLE) whose only positive aPL was IgA anti-beta2-glycoprotein I (isolated IgA anti-beta2GPI) and compared their clinical features with 56 individually matched control patients without any aPL. Patients with isolated IgA anti-beta2GPI had a significantly increased number of thromboembolic events, as compared to controls. When patients were stratified into those with and without SLE, the association between isolated IgA anti-beta2GPI and thromboembolic events persisted for patients with SLE, but was lost for those without SLE. Titers of IgA anti-beta2GPI were significantly higher in SLE patients who suffered a thromboembolic event. Among patients with isolated IgA anti-beta2GPI, there was an increased prevalence of diseases or morbidities involving organs of mucosal immunity (i.e., gastrointestinal system, pulmonary system, and skin).

CONCLUSIONS/SIGNIFICANCE

The presence of isolated IgA anti-beta2GPI is associated with an increased risk of thromboembolic events, especially among patients with SLE. IgA anti-beta2GPI is associated with an increased prevalence of morbidities involving organs of mucosal immunity.

Genetically determined serum levels of mannose-binding lectin correlate negatively with common carotid intima-media thickness in systemic lupus erythematosus

OBJECTIVE

Patients with systemic lupus erythematosus (SLE) have excess cardiovascular morbidity and mortality due to accelerated atherosclerosis that cannot be attributed to traditional cardiovascular risk factors alone. Variant alleles of the mannose-binding lectin gene (MBL2) causing low serum concentrations of functional mannose-binding lectin (MBL) are associated with SLE and development of atherosclerosis. Recent studies show that these variant alleles are associated with increased risk of arterial thrombosis and cardiovascular disease in patients with SLE. Intima-media thickness of the common carotid artery (ccIMT) is a validated noninvasive anatomic measure of subclinical atherosclerosis. In a cross-sectional study we examined the relation among ccIMT, MBL2 genotypes, and serum concentrations of MBL.

METHODS

The MBL2 extended genotypes (YA/YA, YA/XA, XA/XA, YA/YO, XA/YO, YO/YO) and serum concentrations of MBL were determined in 41 outpatients with SLE. ccIMT was measured by means of ultrasonography. Traditional and nontraditional cardiovascular risk modifiers were assessed and controlled for.

RESULTS

Using nonparametric Mann-Whitney tests we found a significant difference in ccIMT between low-expressing (XA/XA+YA/YO+XA/YO+YO/YO) and high-expressing (YA/YA+YA/XA) MBL2 genotypes (p = 0.034). The difference in ccIMT remained significant in multivariable analysis adjusting for traditional and nontraditional cardiovascular risk modifiers (p = 0.049). ccIMT was negatively correlated to serum concentrations of MBL (Spearman rho = -0.33, p = 0.037). This relation also remained significant in multivariable analysis (p = 0.042).

CONCLUSION

In this group of SLE patients, MBL2 low-expressing genotypes and low serum levels of MBL were correlated with ccIMT, independent of the effects of traditional and nontraditional cardiovascular risk modifiers.

The dual role of innate immunity in the antiphospholipid syndrome

The antiphospholipid syndrome (APS), as both a primary syndrome and a syndrome in association with systemic lupus erythematosus (SLE), can be a devastating disease. It is unclear what factors (genetic and/or environmental) lead to the generation of antiphospholipid antibodies (aPL). It is equally unclear why only certain individuals with aPL develop clinical events. We hypothesize that innate immune activation plays a critical role at two distinct stages of APS, namely, the initiation phase, in which aPL first appear, and the effector phase, in which aPL precipitate a thrombotic event. According to the model we propose, aPL alone are insufficient to cause thrombosis and a concomitant trigger of innate immunity, e.g. a toll-like receptor (TLR) ligand, must be present for thrombosis to occur. Here, we discuss our findings that mice immunized with beta(2)-glycoprotein I (beta(2)GPI) and lipopolysaccharide (LPS), a TLR ligand, produce high levels of aPL and other SLE-associated autoantibodies, and develop lupus-like glomerulonephritis. We also discuss our data showing that autoantibodies to heat shock protein 60 (HSP60), an 'endogenous TLR ligand', promote thrombus generation in a murine model of arterial injury. Thus, both pathogen-derived TLR ligands (e.g. LPS) and endogenous TLR ligands (e.g. HSP60) may contribute to the pathogenesis of APS. This putative dual role of innate immunity provides new insight into the generation of aPL as well as the enigma of why some individuals with aPL develop APS, while others do not.

Heat-shock protein 60 and cardiovascular disease: a paradoxical role

Heat-shock proteins (HSPs) are members of a highly conserved group of proteins that are induced in response to stress and injury. These proteins have protective properties, and can protect the heart from injury. HSP60 is found in the mitochondria and cytosol, and has essential intracellular functions including folding key proteins after their import into the mitochondria. In the cytosol, HSP60 binds to proapoptotic proteins, sequestering them. HSPs are highly conserved and, thus, are similar to bacterial proteins. Many individuals have antibodies to HSP60, possibly from prior infections. HSP60 can be found in the plasma membrane and in the serum in disease states. Serum HSP60 may be a marker for coronary artery disease. Once extracellular, HSP60 can cause cell injury. Thus, this protein has dichotomous functions for which the role in disease remains to be fully elucidated.

[High cardiovascular complications in systemic lupus erythematosus: physiopathology and risk management]

Today, cardiovascular mortality is the first cause of mortality in systemic lupus erythematosus (SLE). A 40-year-old woman with SLE is over 50 times more likely to have a myocardial infraction than a healthy woman of similar age. The high CV risk has a double origin: an early and progressive atherosclerosis and a prothrombotic propensity. Multiple factors are incriminated, including a higher prevalence of traditional CV risk factors in SLE population, as well as SLE-specific factors. Autoantibodies can modify lipid profile, induce tissue factor synthesis, favour clotting and endothelial apoptosis. Moreover, endothelial dysfunction and permanent chronic inflammation are present. Treatments are occasionally involved. To reduce more efficiently CV risk in SLE patients, we propose to consider SLE has a complete CV risk factor that should be implemented for CV risk management. This medical procedure of CV risk estimation is unusual in young patients. Its implementation in SLE patients requires a modification of medical practices. CV risk management in SLE patients include identification of optimal targets for each traditional risk factor and SLE specific treatments.

Mitochondrial heat shock protein (HSP) 70 synergizes with HSP60 in transducing endothelial cell apoptosis induced by anti-HSP60 autoantibody

Heat shock protein (HSP) 60, up-regulated by endothelial cells (ECs) to resist stress, is the target of a subgroup of apoptosis-inducing anti-EC autoantibodies (Abs) in human vasculitides. Given that HSP60 is not a transmembrane protein, the mechanism by which these auto-Abs induces apoptosis is unclear. EC membrane proteins were analyzed using bidimensional electrophoresis and Far Western blot, and the HSP60 receptor was identified by mass spectrometry. Heat stress-dependent synthesis of HSP60 and receptor was examined by semiquantitative RT-PCR, and expression was examined by flow cytometry and indirect immunofluorescence. Interaction was demonstrated by coimmunoprecipitations. Lipid rafts were purified to evaluate specific localization, and the apoptotic response was investigated by blocking monoclonal Ab. Mitochondrial HSP70 (mtHSP70) was identified as an HSP60 receptor. Stress was required for ECs to up-regulate mRNA and express mtHSP70 on their surface. HSP60 and mtHSP70 colocalized and interacted within lipid rafts. They were associated with chemokine CC motif receptor 5 (CCR5), also induced at the mRNA and protein levels in stressed ECs. CCR5 was involved in the anti-HSP60-triggered apoptosis of ECs. These results provide new insights into the mechanism by which anti-EC auto-Abs from vasculitides induce apoptosis of ECs.

Autoantibodies to heat shock protein 60 promote thrombus formation in a murine model of arterial thrombosis

BACKGROUND AND OBJECTIVES

Anti-heat shock protein (HSP)60 autoantibodies are associated with atherosclerosis and are known to affect endothelial cells in vitro. However, their role in thrombus formation remains unclear. We hypothesized that anti-HSP60 autoantibodies could potentiate thrombosis, and evaluated the effect of anti-murine HSP60 antibodies in a ferric chloride (FeCl3)-induced murine model of carotid artery injury.

METHODS

Anti-HSP60, or control, IgG was administered to BALB/c mice 48 h prior to inducing carotid artery injury, and blood flow was monitored using an ultrasound probe.

RESULTS

Thrombus formation was more rapid and stable in anti-HSP60 IGG-treated mice than in controls (blood flow=1.7%+/-0.6% vs. 34%+/-12.6%, P=0.0157). Occlusion was complete in all anti-HSP60 IgG-treated mice (13/13), with no reperfusion being observed. In contrast, 64% (9/14) of control mice had complete occlusion, with reperfusion occurring in 6/9 mice. Thrombi were significantly larger in anti-HSP60 IgG-treated mice (P=0.0001), and contained four-fold more inflammatory cells (P=0.0281) than in controls. Non-injured contralateral arteries of anti-HSP60 IgG-treated mice were also affected, exhibiting abnormal endothelial cell morphology and significantly greater von Willebrand factor (VWF) and P-selectin expression than control mice (P=0.0024 and P=0.001, respectively).

CONCLUSIONS

In summary, the presence of circulating anti-HSP60 autoantibodies resulted in increased P-selectin and VWF expression and altered cell morphology in endothelial cells lining uninjured carotid arteries, and promoted thrombosis and inflammatory cell recruitment in FeCl3-injured carotid arteries. These findings suggest that anti-HSP60 autoantibodies may constitute an important prothrombotic risk factor in cardiovascular disease in human vascular disease.

The altered expression of inflammation-related molecules and secretion of IL-6 and IL-8 by HUVEC from newborns with maternal inactive systemic lupus erythematosus is modified by estrogens

Systemic lupus erythematosus (SLE) predominantly affects women, especially those in reproductive age. Genetic contributions to disease susceptibility as well as immune dysregulation, particularly persistent inflammatory responses, are considered essential features. Our aim was to determine whether human umbilical vein endothelial cells (HUVEC) isolated from healthy newborns to women with inactive SLE show inflammation-related abnormalities that might lead to an early development of SLE in the offsprings. HUVEC isolated from six women with inactive SLE were stimulated with 2.5 ng/mL of TNF-alpha and/or physiological and pharmacological doses of 17-I(2) estradiol (E2). Then the expression of VCAM-1, ICAM-1, E-selectin, toll-like receptor-9 (TLR-9), heat shock protein 70 (HSP70) and HSP90 were measured. The concentrations of IL-6, IL-8, and IL-10 were also determined in maternal serum and in TNF-alpha stimulated and non-stimulated HUVEC culture supernatant. HUVEC from children with no family history of autoimmune disease served as controls. Our results showed that in HUVEC from SLE+ mothers, a constitutively low expression of adhesion molecules was enhanced by TNF-alpha treatment. The E2 (1 ng/mL) increased the expression of adhesion molecules but had no effect upon TNF-alpha-treated cells. IL-6 was constitutively higher in SLE+ HUVEC, whereas IL-8 was lower; E2 treatment diminished the latter. The E2 had no effect upon IL-6 and IL-8 secretions in TNF-alpha-treated cells. SLE+ HUVEC showed a disordered cytoskeleton and overexpressed HSP70, HSP90, and TLR-9. Our results indicate that endothelial cells of newborns to SLE+ mothers are in a proinflammatory condition which can be upregulated by estrogens.

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.

Antiendothelial cells autoantibodies in vasculitis-associated systemic diseases

Antiendothelial cell antibodies (AECA) have been detected in healthy individuals, as well as in autoimmune and systemic inflammatory diseases, including systemic vasculitides. AECA have been reported in large vessel vasculitides such as giant cell arteritis and Takayasu arteritis; medium-sized vessel vasculitides, such as polyarteritis nodosa related to hepatitis B virus infection and Kawasaki disease; and small-sized vessel vasculitides, such as Wegener's granulomatosis, microscopic polyangiitis, and Henoch-Schonlein purpura. In Takayasu arteritis and antineutrophil cytoplasm antibody-positive vasculitides, AECA have been reported to correlate with disease activity. A cell-based enzyme-linked immunosorbent assay (ELISA) using cultured human umbilical vein endothelial cells (HUVEC) represent one of the reference techniques for AECA detection, although flow cytometry and immunobloting have also been proposed. AECA might contribute to the pathogenesis of systemic vasculitides and vasculitis-associated diseases through (1) activation of endothelial cells (EC), (2) direct cytotoxic effect due to complement-dependent cytotoxicity or indirect cytotoxic effect secondary to antibody-dependent cytotoxicity, (3) induction of coagulation, (4) induction of apoptosis through the binding of phospholipids or heat-shock protein 60, and (5) induction of EC activation. None of the identified target antigens of AECA is specific for EC, and EC-specific target antigens of AECA remain to be identified in systemic vasculitides.

Malignant hypertension in IgA nephropathy was not associated with background pathological phenotypes of glomerular lesions

BACKGROUND

It was reported that IgA nephropathy (IgAN) was the major cause of secondary malignant hypertension (MHT). However, the pathogenesis of MHT secondary to IgAN (IgAN-MHT) is unknown and its association with glomerular pathological phenotypes remains inconclusive. The present study aimed to investigate whether glomerular pathological phenotypes and anti-endothelial cell antibodies (AECA) were associated with the occurrence of IgAN-MHT.

METHODS

The glomerular pathological phenotypes of 45 patients with IgAN-MHT were analysed using Haas' histologic grading system of IgAN. Sera were collected from 34 of the 45 patients with IgAN-MHT, 19 patients with primary MHT, 41 patients with non-MHT IgAN and 10 healthy volunteers. AECA of both IgG and IgA isotypes were detected by western blot analysis using human umbilical vein endothelial cell lysate as antigen.

RESULTS

In the 45 patients with IgAN-MHT, 7 (15.56%), 5 (11.11%), 13 (28.89%), 9 (20%) and 11 (24.44%) patients were graded as Hass I, II, III, IV and V, respectively. Although the severity of non-ischaemic sclerosis, crescents and mesangial proliferation were significantly different between patients with different grades, the levels of blood pressure, SCr and proteinuria at presentation were comparable. Eleven and four protein bands of endothelial proteins could be blotted by AECA-IgG and AECA-IgA in sera from patients with IgAN-MHT. The prevalences of anti-121 kD AECA-IgG (15/34) and anti-92 kD AECA-IgA (10/34) in IgAN-MHT were significantly higher than that of primary MHT, non-MHT IgAN and normal controls, respectively. Patients with anti-92 kD AECA-IgA had more severe glomerular ischaemic sclerosis (6.25-92.86%, median 39.61%) than those without (0-91.67%, median 18.18%, P = 0.035). There was no significant difference in the prevalence of AECA between IgAN-MHT patients with different background glomerular lesions. Only one IgAN patient with MHT was found with both anti-121 kD AECA-IgG and anti-92 kD AECA-IgA. No particular manifestations were found.

CONCLUSIONS

The occurrence of IgAN-MHT was not associated with the background glomerular pathological phenotypes of IgAN. AECA might play a role in the pathogenesis of IgAN-MHT.

Proteomic analysis of autoantibodies in neuropsychiatric systemic lupus erythematosus patient with white matter hyperintensities on brain MRI

The pathogenesis of neuropsychiatric systemic lupus erythematosus (NPSLE) may be related to autoantibody-mediated neural dysfunction, vasculopathy and coagulopathy. We encountered an NPSLE patient whose brain showed characteristic diffuse symmetrical hyperintensity lesions in the cerebral white matter, cerebellum and middle cerebellar peduncles on T2-weighted magnetic resonance (MR) images. In this study, we investigated all the antigens that reacted strongly with autoantibodies in this patient's serum by two-dimensional electrophoresis (2DE), followed by western blotting (WB) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) using rat brain proteins as the antigen source. As a result, we identified four antigens as beta-actin, alpha-internexin, 60 kDa heat-shock protein (Hsp60) and glial fibrillary acidic protein (GFAP). There are several reports on the detection of anti-endothelial cell antibodies (AECAs) in an SLE patients. Recently, one of the antigens reacting with AECAs in SLE patient's sera has been identified as human Hsp60. We speculated that the abnormal findings on brain MR images of our patient may be due to impairment of microcirculation associated with vascular endothelial cell injury mediated by the antibody against Hsp60. This proteomic analysis is a useful tool for identifying autoantigens in autoimmune diseases involving autoantibodies.

Antiphospholipid antibodies: laboratory and pathogenetic aspects

Antiphospholipid antibodies (aPL) constitute a heterogeneous group of autoantibodies that share the ability to bind phospholipids (PL) alone, protein-PL complexes, or PL-binding proteins. They have been detected in isolation, in association with autoimmune diseases such as systemic lupus erythematosus (SLE), and during the course of different infections. aPL have been associated with an array of clinical manifestations in virtually every organ, although deep vein and arterial thrombosis as well as pregnancy morbidity are predominant. The co-occurrence of these clinical findings with aPL constitutes the so-called antiphospholipid syndrome (APS). aPL can be detected by immunological methods [e.g., anticardiolipin antibodies (aCL)] or by functional methods that exploit the effect of aPL on blood coagulation [lupus anticoagulant (LA)]. Since aPL are heterogeneous, numerous immunological and coagulation assays have been developed. These assays have not been fully standardized, and, therefore, problems such as high interlaboratory variation are relatively frequent. Recently, recommendations have been published regarding LA and aCL testing. Not all aPL are pathogenic. However, when they are not associated with infections, they have a role in the pathogenesis of APS. Clinical and experimental data have shown that aPL exert their pathogenic activity by interfering with the function of coagulation factors, such as thrombin and factors X, XI and XII, and with the function of anticoagulant proteins of the protein C system. In addition, aPL interaction with platelets and endothelial cells induces a pro-adhesive activated phenotype.