Oxidized β2-glycoprotein I induces human dendritic cell maturation and promotes a T helper type 1 response

T cell involvement in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by arterial and venous thrombosis, and obstetric complications in the presence of antiphospholipid antibodies (aPL), including lupus anticoagulant, anticardiolipin and anti-β2-glycoprotein I antibodies. APS manifests as single, often as recurrent events, and rarely as a catastrophic condition. Most studies of APS pathogenesis to date have focused on the prothrombotic role of aPL, while innate immune responses such as monocyte, complement and neutrophil activation have been also recognized as part of the thrombo-inflammatory cascade in APS. While the presence of autoreactive T cells against β2-glycoprotein I has been long known, less data are available on their pathogenetic role in APS. In this review, we summarize current knowledge on the involvement of T cells in APS pathophysiology, alterations of T cell subsets in peripheral blood, and clinical associations. We also highlight potential therapeutic opportunities by targeting T helper-B cell interactions in these patients.

Identification of the key immune-related genes and immune cell infiltration changes in renal interstitial fibrosis

Background

Chronic kidney disease (CKD) is the third-leading cause of premature mortality worldwide. It is characterized by rapid deterioration due to renal interstitial fibrosis (RIF) via excessive inflammatory infiltration. The aim of this study was to discover key immune-related genes (IRGs) to provide valuable insights and therapeutic targets for RIF in CKD.

Materials and methods

We screened differentially expressed genes (DEGs) between RIF samples from CKD patients and healthy controls from a public database. Least absolute shrinkage and selection operator regression analysis and receiver operating characteristic curve analysis were applied to identify significant key biomarkers. The single-sample Gene Set Enrichment Analysis (ssGSEA) algorithm was used to analyze the infiltration of immune cells between the RIF and control samples. The correlation between biomarkers and immune cell composition was assessed.

Results

A total of 928 DEGs between CKD and control samples from six microarray datasets were found, 17 overlapping immune-correlated DEGs were identified by integration with the ImmPort database, and six IRGs were finally identified in the model: apolipoprotein H (APOH), epidermal growth factor (EGF), lactotransferrin (LTF), lysozyme (LYZ), phospholipid transfer protein (PLTP), and secretory leukocyte peptidase inhibitor (SLPI). Two additional datasets and in vivo experiments indicated that the expression levels of APOH and EGF in the fibrosis group were significantly lower than those in the control group, while the expression levels of LTF, LYZ, PLTP, and SLPI were higher (all P < 0.05). These IRGs also showed a significant correlation with renal function impairment. Moreover, four upregulated IRGs were positively associated with various T cell populations, which were enriched in RIF tissues, whereas two downregulated IRGs had opposite results. Several signaling pathways, such as the "T cell receptor signaling pathway" and "positive regulation of NF-κB signaling pathway", were discovered to be associated not only with immune cell infiltration, but also with the expression levels of six IRGs.

Conclusion

In summary, six IRGs were identified as key biomarkers for RIF, and exhibited a strong correlation with various T cells and with the NF-κB signaling pathway. All these IRGs and their signaling pathways may evolve as valuable therapeutic targets for RIF in CKD.

Advances in the Pathophysiology of Thrombosis in Antiphospholipid Syndrome: Molecular Mechanisms and Signaling through Lipid Rafts

The pathological features of antiphospholipid syndrome (APS) are related to the activity of circulating antiphospholipid antibodies (aPLs) associated with vascular thrombosis and obstetric complications. Indeed, aPLs are not only disease markers, but also play a determining pathogenetic role in APS and exert their effects through the activation of cells and coagulation factors and inflammatory mediators for the materialization of the thromboinflammatory pathogenetic mechanism. Cellular activation in APS necessarily involves the interaction of aPLs with target receptors on the cell membrane, capable of triggering the signal transduction pathway(s). This interaction occurs at specific microdomains of the cell plasma membrane called lipid rafts. In this review, we focus on the key role of lipid rafts as signaling platforms in the pathogenesis of APS, and propose this pathogenetic step as a strategic target of new therapies in order to improve classical anti-thrombotic approaches with "new" immunomodulatory drugs.

Gas Plasma Protein Oxidation Increases Immunogenicity and Human Antigen-Presenting Cell Maturation and Activation

Protein vaccines rely on eliciting immune responses. Inflammation is a prerequisite for immune responses to control infection and cancer but is also associated with disease onset. Reactive oxygen species (ROSs) are central during inflammation and are capable of inducing non-enzymatic oxidative protein modifications (oxMods) associated with chronic disease, which alter the functionality or immunogenicity of proteins that are relevant in cancer immunotherapy. Specifically, antigen-presenting cells (APCs) take up and degrade extracellular native and oxidized proteins to induce adaptive immune responses. However, it is less clear how oxMods alter the protein's immunogenicity, especially in inflammation-related short-lived reactive species. Gas plasma technology simultaneously generates a multitude of ROSs to modify protein antigens in a targeted and controlled manner to study the immunogenicity of oxMods. As model proteins relevant to chronic inflammation and cancer, we used gas plasma-treated insulin and CXCL8. We added those native or oxidized proteins to human THP-1 monocytes or primary monocyte-derived cells (moDCs). Both oxidized proteins caused concentration-independent maturation phenotype alterations in moDCs and THP-1 cells concerning surface marker expression and chemokine and cytokine secretion profiles. Interestingly, concentration-matched H2O2-treated proteins did not recapitulate the effects of gas plasma, suggesting sufficiently short diffusion distances for the short-lived reactive species to modify proteins. Our data provide evidence of dendric cell maturation and activation upon exposure to gas plasma- but not H2O2-modified model proteins. The biological consequences of these findings need to be elucidated in future inflammation and cancer disease models.

Effects of anti-beta 2-glycoprotein 1 antibodies and its association with pregnancy-related morbidity in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by venous, arterial, or small-vessel thrombosis and/or pregnancy-related morbidity, associated with persistent positivity of antiphospholipid antibodies (aPL). Pregnancy-related morbidity in APS patients is characterized by unexplained fetal deaths, premature birth of morphologically normal newborns, and/or consecutive pregnancy losses before the 10^th week of gestation. Beta 2-glycoprotein 1 (ß2GP1) is the main antigen recognized by aPL and plays an essential role in the pathogenesis of APS. Antibodies against ß2GP1 (aß2GP1) are involved in damage-generating mechanisms in APS due to their interaction with trophoblasts, decidua, and endothelial cells. aß2GP1 might be used as a prognostic tool for obstetric risk stratification and ß2GP1 could be a target for molecular-targeted treatment to prevent pregnancy morbidity in APS. This review describes these aspects of aß2GP1, including effects on different cellular targets, its association with the severity of obstetric manifestations and the potential of ß2GP1-targeted therapies for APS.

Dendritic Cells and Antiphospholipid Syndrome: An Updated Systematic Review

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by autoreactive B and T cells against β2-glycoprotein I (B2GPI), with vascular thrombosis or obstetrical complications. Dendritic cells (DCs) are crucial in the generation of autoimmunity. Here, we conducted a comprehensive systematic review on the relationship between DC and APS. We performed a literature search of PubMed as of 26 March 2021. A total of 33 articles were extracted. DCs are pivotal in inducing inflammatory responses and orchestrating adaptive immunity. DCs contribute to the local inflammation regarding vascular thrombosis or obstetrical complications. Both B2GPI and antiphospholipid antibodies (aPL) can promote antigen presentation by DCs and the generation or maintenance of autoimmunity. In addition, plasmacytoid DC activation is enhanced by aPL, thereby augmenting the inflammatory response. In line with these findings, DC modulation appears promising as a future treatment for APS. In conclusion, our review indicated the crucial role of DCs in the pathogenesis of APS. Deeper understanding of the complex relationship would help in developing new treatment strategies.

Crassolide Suppresses Dendritic Cell Maturation and Attenuates Experimental Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by the production of β2-glycoprotein I (β2GPI)-dependent autoantibodies, with vascular thrombosis or obstetrical complications. Around 20% of APS patients are refractory to current treatments. Crassolide, a cembranoid diterpene extracted from soft corals, is a potential therapeutic candidate. Here, to examine the anti-inflammatory properties of crassolide, we first determined its effects on bone marrow-derived and splenic dendritic cells (DC). Specifically, we applied lipopolysaccharide (LPS) or β2GPI stimulation and measured the expressions of CD80 and CD86, and secretions of cytokines. We also determined in the OT-II mice, if bone marrow-derived DC was able to stimulate antigen-specific T cells. Moreover, we examined the therapeutic potential of crassolide postimmunization in a murine model of APS that depended on active immunization with β2GPI. The vascular manifestations were evaluated in terms of fluorescein-induced thrombi in mesenteric microvessels, whereas the obstetric manifestations were evaluated based on the proportion of fetal loss after pregnancy. We also measured blood titers of anti-β2GPI antibody, splenic cell proliferative responses and cytokine secretions after β2GPI stimulation ex vivo. Finally, we determined in these mice, hematological, hepatic and renal toxicities of crassolide. Crassolide after LPS stimulation suppressed DC maturation and secretion of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-12 and IL-23, and downstream T cell activation. Crassolide could partially ameliorate both the vascular and obstetric manifestations of APS in BALB/c mice. Both blood titers of anti-β2GPI antibody and splenic cell proliferation after β2GPI stimulation were reduced. Splenic Th1 and Th17 responses were also lowered after β2GPI stimulation. Finally, within therapeutic doses of crassolide, we found no evidence of its toxicity. In conclusion, we showed the ability of crassolide to suppress DC and downstream T cell responses. Crassolide is therefore a potential candidate for adjunctive therapy in APS.

T Cell Proliferative Responses and IgG Antibodies to β2GPI in Patients with Diabetes and Atherosclerosis

BACKGROUND

Diabetes increases the risk of myocardial infarction (MI) by 2 to 3 folds. Tlymphocytes play a role in atherosclerosis, which is the main pathology behind MI. Cellular immune responses to beta-2 glycoprotein I (β2GPI) are shown in carotid atherosclerosis.

OBJECTIVE

To investigate the self-reactive, β2GPI-specific T-lymphocytes in patients with and without diabetes and atherosclerosis.

METHODS

Collectively, 164 subjects with and without diabetes that underwent coronary angiography were divided into four groups based on their diabetes status and coronary stenosis. Group I=Diabetic with ≥50% stenosis: A+D+ (n=66); Group II=Non-diabetic with ≥50% stenosis, A+D- (n=39); Group III=Diabetic with <50% stenosis: A-D+ (n=28); and Group IV=Non-diabetic with <50% stenosis: AD- (n=31). All groups were evaluated for anti-β2GPI IgG antibody by ELISA method. Then, PBMCs were isolated from 18 subjects and were stimulated with β2GPI-derived peptides to assess their proliferation in accordance with their HLA-DRB1 alleles.

RESULTS

Mean β2GPI IgG levels were higher in groups with ≥50% stenosis (A+) compared to those with <50% stenosis (A-), (P=0.02). The co-presence of diabetes in A+ individuals increased mean β2GPI-specific IgG. Auto-reactive β2GPI-specific T cells were detected in the repertoire of T-lymphocytes in all groups. β2GPI-peptides showed promiscuous restriction by various HLADRB1.

CONCLUSION

β2GPI is the target of cellular and humoral immune responses in patients with atherosclerosis. Since the T cell responses but not antibodies were detectable in A-D+ and A-D- groups, it is reasonable to assume that cellular responses preceded the humoral responses. Post-translation modifications of β2GPI under oxidative and glycemic stresses may have increased the IgG levels in patients with diabetes. Finally, identification of antigens that trigger immuno-pathogenesis in atherosclerosis and diabetes may help the development of immunomodulation methods to prevent or treat these debilitating diseases.

Molecular Mechanisms of "Antiphospholipid Antibodies" and Their Paradoxical Role in the Pathogenesis of "Seronegative APS"

Antiphospholipid Syndrome (APS) is an autoimmune disease characterized by arterial and/or venous thrombosis and/or pregnancy morbidity, associated with circulating antiphospholipid antibodies (aPL). In some cases, patients with a clinical profile indicative of APS (thrombosis, recurrent miscarriages or fetal loss), who are persistently negative for conventional laboratory diagnostic criteria, are classified as "seronegative" APS patients (SN-APS). Several findings suggest that aPL, which target phospholipids and/or phospholipid binding proteins, mainly β-glycoprotein I (β-GPI), may contribute to thrombotic diathesis by interfering with hemostasis. Despite the strong association between aPL and thrombosis, the exact pathogenic mechanisms underlying thrombotic events and pregnancy morbidity in APS have not yet been fully elucidated and multiple mechanisms may be involved. Furthermore, in many SN-APS patients, it is possible to demonstrate the presence of unconventional aPL ("non-criteria" aPL) or to detect aPL with alternative laboratory methods. These findings allowed the scientists to study the pathogenic mechanism of SN-APS. This review is focused on the evidence showing that these antibodies may play a functional role in the signal transduction pathway(s) leading to thrombosis and pregnancy morbidity in SN-APS. A better comprehension of the molecular mechanisms triggered by aPL may drive development of potential therapeutic strategies in APS patients.

β2-Glycoprotein I-Reactive T Cells in Autoimmune Disease

Anti-phospholipid syndrome (APS) and systemic lupus erythematosus (SLE) are autoimmune diseases characterized by autoantibody production and autoantibody-related pathology. Anti-phospholipid antibodies (aPL) are found in all patients with APS and in 20-30% of individuals with SLE. aPL recognize a number of autoantigens, but the primary target in both APS and SLE is β2-glycoprotein I (β2GPI). The production of IgG aPL in APS and SLE, as well as the association of aPL with certain MHC class II molecules, has led to investigation of the role of β2GPI-reactive T helper (Th). β2GPI-reactive CD4 Th cells have been associated with the presence of aPL and/or APS in both primary APS and secondary APS associated with SLE, as well as in SLE patients and healthy controls lacking aPL. CD4 T cells reactive with β2GPI have also been associated with atherosclerosis and found within atherosclerotic plaques. In most cases, the epitopes targeted by autoreactive β2GPI-reactive CD4 T cells in APS and SLE appear to arise as a consequence of antigenic processing of β2GPI that is structurally different from the soluble native form. This may arise from molecular interactions (e.g., with phospholipids), post-translational modification (e.g., oxidation or glycation), genetic alteration (e.g., β2GPI variants), or molecular mimicry (e.g., microbiota). A number of T cell epitopes have been characterized, particularly in Domain V, the lipid-binding domain of β2GPI. Possible sources of negatively charged lipid that bind β2GPI include oxidized LDL, activated platelets, microbiota (e.g., gut commensals), and dying (e.g., apoptotic) cells. Apoptotic cells not only bind β2GPI, but also express multiple other cellular autoantigens targeted in both APS and SLE. Dying cells that have bound β2GPI thus provide a rich source of autoantigens that can be recognized by B cells across a wide range of autoantigen specificities. β2GPI-reactive T cells could potentially provide T cell help to autoantigen-specific B cells that have taken up and processed apoptotic (or other dying) cells, and subsequently present β2GPI on their surface in the context of major histocompatibility complex (MHC) class II molecules. Here, we review the literature on β2GPI-reactive T cells, and highlight findings supporting the hypothesis that these T cells drive autoantibody production in both APS and SLE.

Oxidative post-translational modification of βeta 2-glycoprotein I in the pathophysiology of the anti-phospholipid syndrome

The anti-phospholipid syndrome (APS) is a prothrombotic autoimmune disorder characterized by either thrombosis or pregnancy complications in the setting of persistent anti-phospholipid antibodies (aPL). βeta 2-glycoprotein I (β2-GPI) is the major autoantigen in APS that binds anionic phospholipids as well as specific receptors on platelets and endothelial cells resulting in activation of prothrombotic pathways. β2-GPI consists of 5 Domains that exist in a circular or linear form, with the latter occurring after binding to anionic phospholipids. β2-GPI also undergoes dynamic posttranslational modification between oxidized and free thiol forms. The relationship between posttranslational modification and structural conformation is yet to be definitively clarified. Compared with controls, patients with the APS have higher levels of total β2-GPI and lower levels of free thiol β2-GPI. This raises the possibility of using quantification of β2-GPI posttranslational modification as a redox biomarker in the management and diagnosis of the APS.

Effects of Toll-like receptor 4 on β2-glycoprotein I-induced splenic T cell subsets differentiation

Our previous study demonstrated that beta 2-glycoprotein I (β2GPI) stimulation promotes bone marrow derived dendritic cells (BMDCs) maturation and T cell proliferation in a Toll-like receptor 4 (TLR4) dependent manner. However, β2GPI induced T cell differentiation and the role of TLR4 in this process have rarely been reported. In the present study, we focused on the differentiation of splenic T cells in β2GPI immunized Balb/c, C3H/HeN and C3H/HeJ mice. According to our results, Th2 dominated differentiation was observed in β2GPI immunized Balb/c and C3H/HeN mice than in those treated with normal saline (NS), namely the up-regulated levels of Th2 markers GATA3 and IL-4 (p < 0.05). Meanwhile, reduced Th1 markers T-bet and IFN-γ, and Treg marker Foxp3 were observed in β2GPI immunized mice (p < 0.05). C3H/HeJ mice have the same gene background with C3H/HeN mice except a functional mutant in TLR4 gene. However, the described Th2 differentiation was not detected in these TLR4 deficient mice, indicating the importance of TLR4 in immune response against β2GPI. In addition, we found that β2GPI-induced Th2 differentiation could be strengthened by cytokines secreted by dendritic cells (DCs) and DCs-T cells interaction. However, DCs-T cells contact was indispensable during this process because of its unique role in suppressing Th1 function. Furthermore, this Th2 biased differentiation pattern was more noticeable in mice received 4 times β2GPI immunization than those received 2 times, suggesting the amplifying effects of anti-β2GPI Ab on β2GPI induced Th2 response. These findings may partly explain the immune imbalance in APS patient through the view angle of T cell differentiation and anti-β2GPI antibody production.

Cellular immune response to β2-glycoprotein-I valine/leucine247 phenotypes in Mexican patients with primary antiphospholipid syndrome

Homozygote genotype V²⁴⁷ of the β₂-glycoprotein-I (β₂GP-I) gene has been associated with anti-β₂GP-I and thrombosis in patients with primary anti-phospholipid syndrome APS (PAPS). However, the cellular immune response to β₂GP-I²⁴⁷ has been little studied.

OBJECTIVE

To evaluate the immune cellular proliferation in response to native and non-native β₂GP-I²⁴⁷ valine/leucine phenotype from Mexican patients with PAPS.

METHODS

We studied 10 patients with PAPS and 10 healthy control subjects (HC). The polymorphism at position 247 of the β₂GP-I gene was determined by PCR-RFLP and the corresponding β₂GP-I protein was subsequently purified from normal human plasma by affinity chromatography. PBMC purified from patients and controls were stimulated with β₂GP-I under native and in non native (reduced) conditions. We also determined the anti-β₂GP-I production in vitro by B cell clones (EBV) generated in cocultures experiments. Differential Scanning Calorimetry (DSC) was studied to determine the structural differences between the β₂GP-I²⁴⁷ valine/leucine isoforms. Cytokine profile (IL-2, IL-4, IL-6, TNFα, INFγ) was evaluated in culture supernatants.

RESULTS

PAPS and healthy control PBMCs had a higher proliferative response when stimulated with β₂GP-I under reduced cultures conditions compared to non-denatured conditions. PBMCs response from PAPS patients was higher. We observed more cell proliferation in response to β₂GP-I²⁴⁷ valine/leucine or valine isoforms in non-native conditions. In contrast, this response was not significant against β₂GP-I²⁴⁷ leucine. These findings were T CD4⁺-dependent. Similar results were obtained with B cell clones derived from PAPS patients, which showed more pronounced proliferation in non native conditions and higher against β₂GP-I²⁴⁷ valine. No differences were found in anti-β₂GP-I production, but high levels of IL-6 in vitro were identified. The structural analysis of both β₂GP-I²⁴⁷ isoforms by DSC showed a major conformational change due to a single mutation in the β₂GP-I variants.

CONCLUSIONS

PAPS PBMCs had a higher cellular response against β₂GP-I²⁴⁷ in non-native culture conditions preferentially to the β₂GP-I²⁴⁷ valine phenotype. This effect is T CD4⁺ dependent and appears to be driven by tertiary structural changes adopted by β₂GP-I²⁴⁷ polymorphism.

Redox Status of β2GPI in Different Stages of Diabetic Angiopathy

We explored the redox status of beta 2 glycoprotein I (β₂GPI) in different stages of diabetic angiopathy. Type 2 diabetes mellitus (T2DM) had a significantly lower proportion of reduced β₂GPI as compared to healthy controls (p < 0.05). There was a trend that the mild coronal atherosclerosis heart disease (CAD) had higher proportion of reduced β₂GPI than non-CAD and severe-CAD groups, however without significances (p > 0.05). The mild-A-stenosis group and mild-diabetic retinopathy (DR) groups had higher proportion of reduced β₂GPI than their severely affected counterparts. The mild-slow nerve conduction velocity (NCVS) group had higher proportion of reduced β₂GPI than normal nerve conduction velocity (NCVN group) and severe-NCVS groups. The proportion of reduced β₂GPI was in positive correlation with 24 h urine microalbumin and total urine protein, and the proportion of reduced β₂GPI was in negative correlation with serum and skin advanced glycation end products (AGEs). Taken together, our data implicate that the proportion of reduced β₂GPI increased in the early stage of angiopathy and decreased with the aggravation of angiopathy.

Posttranslational forms of beta 2-glycoprotein I in the pathogenesis of the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is an autoimmune disease characterised by a procoagulant state that predisposes to recurrent thrombosis and miscarriages. Two major discoveries have advanced our understanding of the underlying complex pathogenesis of the APS. The first was the discovery that beta-2 glycoprotein-1 (β2GPI) is the major auto antigen in APS. The second was the discovery in more recent years that β2GPI contains allosteric disulphide bonds susceptible to posttranslational modification that may be involved in the development of autoantibodies in APS. The main allosteric disulphide bond in the fifth domain of β2GPI can exist in two redox states: free thiol or oxidised. It is the conformational transformation of β2GPI from its free thiol form to its more immunogenic oxidised form that exposes neo-epitopes on the first and fifth domains. The purpose of this review is to highlight the recent findings on the posttranslational forms of β2GPI in the pathogenesis of APS. We suggest that novel assays quantitating the different redox forms of β2GPI in plasma or serum may be used to supplement existing clinical and laboratory assays to more accurately stratify risk of thrombosis or miscarriage in APS patients.

Antibodies to age-β2 glycoprotein I in patients with anti-phospholipid antibody syndrome

Anti-phospholipid antibody syndrome (APS) is a systemic autoimmune disease characterized clinically by arterial and/or venous thromboses, recurrent abortions or fetal loss and serologically by the presence of 'anti-phospholipid antibodies' (aPL). The main target antigen of the antibodies is β2 glycoprotein I (β2 GPI). Post-translational oxidative modifications of the protein have been widely described. In this study we aimed to analyse sera reactivity to glucose-modified β2 GPI (G-β2 GPI). Sera collected from 43 patients with APS [15 primary APS (PAPS) and 28 APS associated with systemic lupus erythematosus (SLE) (SAPS)], 30 with SLE, 30 with rheumatoid arthritis (RA) and 40 healthy subjects were analysed by an enzyme-linked immunosorbent assay (ELISA) using a G-β2 GPI. Nine of 15 consecutive PAPS out-patients (60%) and 16 of 28 SAPS (57.1%) showed serum antibodies [immunoglobulin (Ig)G class] against G-β2 GPI (anti-G-β2 GPI) by ELISA. The occurrence of anti-G-β2 GPI was significantly higher in APS patients compared to patients suffering from SLE. No RA patients or control healthy subjects resulted positive for anti-G-β2 GPI. Of note, aG-β2 GPI prompted to identify some APS patients (four PAPS and seven SAPS), who were negative in the classical anti-β2 GPI test. Moreover, in APS patients, anti-G-β2 GPI titre was associated significantly with venous thrombosis and seizure in APS patients. This study demonstrates that G-β2 GPI is a target antigen of humoral immune response in patients with APS, suggesting that β2 GPI glycation products may contain additional epitopes for anti-β2 GPI reactivity. Searching for these antibodies may be useful for evaluating the risk of clinical manifestations.

Delineating the deranged immune system in the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is a systemic autoimmune disease that is characterized serologically by the presence of antiphospholipid antibodies (aPL) and clinically by vascular thrombosis and obstetric complications. The protein β2 glycoprotein I (β2GPI) is identified as the most important autoantigen in this syndrome. Activation of endothelial cells, thrombocytes and placental tissue by anti-β2GPI antibodies relates to the clinical manifestations of APS. This review describes genetic and environmental factors in relation to APS and summarizes the current knowledge on abnormalities in components of both the innate and adaptive immune system in APS. The role of dendritic cells, T-cells, B-cells, monocytes, neutrophils and NK-cells as well as the complement system in APS are discussed. Several gaps in our knowledge on the pathophysiology of APS are identified and a plea is made for future extensive immune cell profiling by a systems medicine approach in order to better unravel the pathogenesis of APS, to gain more insight in the role of the immune system in APS as well as having the potential to reveal biomarkers or novel therapeutic targets.

Binding of plasma proteins to titanium dioxide nanotubes with different diameters

Titanium and titanium alloys are considered to be one of the most applicable materials in medical devices because of their suitable properties, most importantly high corrosion resistance and the specific combination of strength with biocompatibility. In order to improve the biocompatibility of titanium surfaces, the current report initially focuses on specifying the topography of titanium dioxide (TiO2) nanotubes (NTs) by electrochemical anodization. The zeta potential (ζ-potential) of NTs showed a negative value and confirmed the agreement between the measured and theoretically predicted dependence of ζ-potential on salt concentration, whereby the absolute value of ζ-potential diminished with increasing salt concentrations. We investigated binding of various plasma proteins with different sizes and charges using the bicinchoninic acid assay and immunofluorescence microscopy. Results showed effective and comparatively higher protein binding to NTs with 100 nm diameters (compared to 50 or 15 nm). We also showed a dose-dependent effect of serum amyloid A protein binding to NTs. These results and theoretical calculations of total available surface area for binding of proteins indicate that the largest surface area (also considering the NT lengths) is available for 100 nm NTs, with decreasing surface area for 50 and 15 nm NTs. These current investigations will have an impact on increasing the binding ability of biomedical devices in the body leading to increased durability of biomedical devices.

Relationship between redox status and cell fate in immunity and autoimmunity

SIGNIFICANCE

The signaling function of redox molecules is essential for an efficient and proper execution of a large number of cellular processes, contributing to the maintenance of cell homeostasis. Excessive oxidative stress is considered as playing an important role in the pathogenesis of autoimmune diseases by enhancing inflammation and breaking down the immunological tolerance through protein structural modifications that induce the appearance of neo/cryptic epitopes.

RECENT ADVANCES

There is a complex reciprocal relationship between oxidative stress and both apoptosis and autophagy, which is essential to determine cell fate. This is especially relevant in the context of autoimmune disorders in which apoptosis and autophagy play a crucial pathogenic role.

CRITICAL ISSUES

In this review, we describe the latest developments with regard to the involvement of redox molecules in the initiation and progression of autoimmune disorders, focusing on their role in cell fate regulation. We also discuss new therapeutic approaches that target oxidative stress in the treatment of these disorders. The administration of antioxidants is scarcely studied in autoimmunity, and future analyses are needed to assess its beneficial effects in preventing or ameliorating these diseases.

FUTURE DIRECTIONS

Deciphering the intricate relationships between oxidative stress and both apoptosis and autophagy in the context of autoimmunity could be critical in elucidating key pathogenic mechanisms and could lead to novel interventions for the clinical management of autoimmune diseases.

Neuropeptide Y induces potent migration of human immature dendritic cells and promotes a Th2 polarization

Neuropeptide Y (NPY), a major autonomic nervous system and stress mediator, is emerging as an important regulator of inflammation, implicated in autoimmunity, asthma, atherosclerosis, and cancer. Yet the role of NPY in regulating phenotype and functions of dendritic cells (DCs), the professional antigen-presenting cells, remains undefined. Here we investigated whether NPY could induce DCs to migrate, mature, and polarize naive T lymphocytes. We found that NPY induced a dose-dependent migration of human monocyte-derived immature DCs through the engagement of NPY Y1 receptor and the activation of ERK and p38 mitogen-activated protein kinases. NPY promoted DC adhesion to endothelial cells and transendothelial migration. It failed to induce phenotypic DC maturation, whereas it conferred a T helper 2 (Th2) polarizing profile to DCs through the up-regulation of interleukin (IL)-6 and IL-10 production. Thus, during an immune/inflammatory response NPY may exert proinflammatory effects through the recruitment of immature DCs, but it may exert antiinflammatory effects by promoting a Th2 polarization. Locally, at inflammatory sites, cell recruitment could be amplified in conditions of intense acute, chronic, or cold stress. Thus, altered or amplified signaling through the NPY-NPY-Y1 receptor-DC axis may have implications for the development of inflammatory conditions.-Buttari, B., Profumo, E., Domenici, G., Tagliani, A., Ippoliti, F., Bonini, S., Businaro, R., Elenkov, I., Riganò, R. Neuropeptide Y induces potent migration of human immature dendritic cells and promotes a Th2 polarization.

Oxidative stress, prooxidants, and antioxidants: the interplay

Oxidative stress is a normal phenomenon in the body. Under normal conditions, the physiologically important intracellular levels of reactive oxygen species (ROS) are maintained at low levels by various enzyme systems participating in the in vivo redox homeostasis. Therefore, oxidative stress can also be viewed as an imbalance between the prooxidants and antioxidants in the body. For the last two decades, oxidative stress has been one of the most burning topics among the biological researchers all over the world. Several reasons can be assigned to justify its importance: knowledge about reactive oxygen and nitrogen species production and metabolism; identification of biomarkers for oxidative damage; evidence relating manifestation of chronic and some acute health problems to oxidative stress; identification of various dietary antioxidants present in plant foods as bioactive molecules; and so on. This review discusses the importance of oxidative stress in the body growth and development as well as proteomic and genomic evidences of its relationship with disease development, incidence of malignancies and autoimmune disorders, increased susceptibility to bacterial, viral, and parasitic diseases, and an interplay with prooxidants and antioxidants for maintaining a sound health, which would be helpful in enhancing the knowledge of any biochemist, pathophysiologist, or medical personnel regarding this important issue.

Subclinical atherosclerosis in systemic lupus erythematosus and antiphospholipid syndrome: focus on β2GPI-specific T cell response

OBJECTIVE

Systemic Lupus Erythematosus (SLE) and antiphospholipid syndrome (APS) are associated with a high prevalence of atherosclerosis. β2 glycoprotein I (β2GPI) represents a link between autoimmunity and endothelial dysfunction. Recently, β2GPI reactive T cells have been identified; however, their role in atherosclerosis is still under investigation. We evaluated early atherosclerosis in patients with SLE and APS and investigated T cell reactivity to β2GPI and its relationship with atherosclerotic process.

APPROACH AND RESULTS

Fifty SLE, 18 patients with primary APS (PAPS), and 25 healthy controls were enrolled. Demographic and clinical data, including traditional cardiovascular risk factors, were recorded. Monocyte β2GPI and Tissue Factor (TF) expression and peripheral blood mononuclear cell response to β2GPI stimulation were evaluated. Doppler ultrasound was performed to investigate flow-mediated dilatation (FMD) and carotid intima-media thickness (IMT). We detected an increase in mean IMT and a decrease in FMD in patients with SLE versus controls (P<0.05 and P=0.0001, respectively) and a decrease in FMD in patients with PAPS versus controls (P<0.05). Monocyte β2GPI and TF expression was higher in patients with SLE and PAPS than in controls (P=0.006 and P=0.001, respectively); no correlation of monocyte β2GPI and TF with IMT or FMD was detected. β2GPI induced peripheral blood mononuclear cell proliferation in 32% of patients with SLE, 25% of patients with PAPS yet in none of the controls. Proliferative response to β2GPI correlated with a history of arterial thrombosis, thrombocytopenia, and IMT >0.9 mm.

CONCLUSIONS

A significant percentage of patients with SLE and PAPS show a β2GPI-specific T cell reactivity, which is associated with subclinical atherosclerosis.

Actin is a target of T-cell reactivity in patients with advanced carotid atherosclerotic plaques

Atherosclerosis is a chronic inflammatory disease of the arterial wall associated with autoimmune reactions. In a previous study, we observed the presence of actin-specific antibodies in sera from patients with carotid atherosclerosis. To extend our previous results we evaluated the possible role of actin as antigenic target of cell-mediated immune reactions in carotid atherosclerosis. Peripheral blood mononuclear cells (PBMC) from 17 patients and 16 healthy subjects were tested by cell proliferation assay and by ELISA for cytokine production. Actin induced a proliferative response in 47% of patients' PBMC samples, with SI ranging from 2.6 to 21.1, and in none of the healthy subjects' samples (patients versus healthy subjects, P = 0.02). The presence of diabetes in patients was significantly associated with proliferative response to actin (P = 0.04). IFN-γ and TNF-α concentrations were higher in PBMC from patients than in those from healthy subjects and in PBMC proliferating to actin than in nonproliferating ones. Our data demonstrate for the first time a role of actin as a target autoantigen of cellular immune reactions in patients with carotid atherosclerosis. The preferential proinflammatory Th1 activation suggests that actin could contribute to endothelial dysfunction, tissue damage, and systemic inflammation in carotid atherosclerosis.

Resveratrol prevents dendritic cell maturation in response to advanced glycation end products

Advanced glycation end products (AGEs), generated through nonenzymatic glycosylation of proteins, lipids, and nucleic acids, accumulate in the body by age thus being considered as biomarkers of senescence. Senescence is characterized by a breakdown of immunological self-tolerance, resulting in increased reactivity to self-antigens. Previous findings suggest that AGE and its receptor RAGE may be involved in the pathogenesis of autoimmune reactions through dendritic cell (DC) activation. The aim of this study was to investigate whether resveratrol, a polyphenolic antioxidant compound with tolerogenic effects on DCs, was able to counteract the mechanisms triggered by AGE/RAGE interaction on DCs. By immunochemical and cytofluorimetric assays, we demonstrated that in vitro pretreatment of human monocyte-derived DCs with resveratrol prevents DC activation in response to glucose-treated albumin (AGE-albumin). We found that resveratrol exerts an inhibitory effect on DC surface maturation marker and RAGE up-regulation in response to AGE-albumin. It also inhibited proinflammatory cytokine expression, allostimulatory ability upregulation, mitogen-activated protein (MAP) kinases, and NF-κB activation in AGE-albumin-stimulated DCs. We suggest that resveratrol, by dismantling AGE/RAGE signaling on DCs may prevent or reduce increased reactivity to self-molecules in aging.

Free radicals and endothelial dysfunction: potential positive effects of TNF-α inhibitors

OBJECTIVES

During the last decade many new biological immune modulators have entered the market as new therapeutic principles. Tumor necrosis factor (TNF)-α is a pro-inflammatory cytokine known to a have a key role in the pathogenic mechanisms of various immune-mediated or inflammatory diseases. However, TNF-α also plays a key role in endothelial dysfunction and, thus, in the development and progression of atherosclerosis. What, then, is the potential therapeutic role of TNF-α inhibitors?

METHODS

We analysed the current literature concerning the administration of TNF-α inhibitors and their potential benefits upon endothelial function.

RESULTS

TNF-α inhibitors decrease the serum levels of inflammatory markers such as TNF-α itself, CRP, IL-6, and increased the tissue expression of endothelial NO synthase and the vasodilatory response to bradykinin.

DISCUSSION

TNF-α inhibitors may change the progression of endothelial dysfunction and, thus, slow down the atherosclerotic process.

Long-term treatment of rheumatoid arthritis with adalimumab

Rheumatoid arthritis (RA) is a chronic inflammatory disease that is associated with joint damage and progressive disability, an increased risk of morbidity related to comorbid conditions and substantial socioeconomic costs. Tumor necrosis factor-alpha (TNF-α) is a proinflammatory cytokine known to have a central role in the initial host response to infection and in the pathogenesis of various immune-mediated diseases, such as RA, ankylosing spondylitis, psoriasis and/or psoriatic arthritis, Crohn’s disease, and systemic lupus erythematosus. Five TNF-α inhibitors are available for the clinical use: infliximab; adalimumab; etanercept; golimumab; and certolizumab pegol. Infliximab is a chimeric human/murine IgG1 monoclonal antibody (mAb); adalimumab, and golimumab are human mAbs; certolizumab pegol is composed of the fragment antigen-binding anti-binding domain of a humanized anti-TNF-α mAb, combined with polyethylene glycol to increase its half-life in the body; etanercept is a fusion protein that acts as a “decoy receptor” for TNF-α. In this paper, we will briefly review the current data on efficacy and safety of adalimumab in patients with RA, its potential beneficial effects upon comorbid conditions, such as endothelial dysfunction and accelerated atherosclerosis in RA, and the immunogenicity.

Dendritic cells: an important link between antiphospholipid antibodies, endothelial dysfunction, and atherosclerosis in autoimmune and non-autoimmune diseases

The presence of dendritic cells, antigen-presenting cells that link innate and adaptive immunity, is necessary to generate and maintain the production of antiphospholipid antibodies in response to exposed intracellular phospholipids on the outer surface of apoptotic cells. In turn, antiphospholipid antibodies enhance dendritic cell-induced inflammatory and proatherogenic responses in a number of conditions that are associated with accelerated atherosclerosis, including diabetes, chronic kidney disease, periodontal infections, and aging. While altering dendritic cells by modifying the ubiquitin-proteasome system enhances antiphospholipid antibody production and leads to development of accelerated atherosclerosis and autoimmune features, inducing tolerance by dendritic cell manipulation leads to decreased atherosclerosis and thrombosis. Therefore, further translational studies are needed to understand the interplay between dendritic cells and antiphospholipid antibodies, and to develop potential new therapies for antiphospholipid syndrome and atherosclerosis. Here we review current experimental and translational studies that have examined the role of dendritic cells in antiphospholipid antibody formation and in antiphospholipid-associated atherosclerosis and thrombosis.

T lymphocyte autoreactivity in inflammatory mechanisms regulating atherosclerosis

Atherosclerosis has been clearly demonstrated to be a chronic inflammatory disease of the arterial wall. Both cells of the innate and the acquired immune system, particularly monocytes and T lymphocytes, are implicated in the atherogenic process, producing different cytokines with pro- and anti-inflammatory effects. The majority of pathogenic T cells involved in atherosclerosis are of the Th1 profile, that has been correlated positively with coronary artery disease. Many studies conducted to evaluate the molecular factors responsible for the activation of T cells have demonstrated that the main antigenic targets in atherosclerosis are modified endogenous structures. These self-molecules activate autoimmune reactions mainly characterized by the production of Th1 cytokines, thus sustaining the inflammatory mechanisms involved in endothelial dysfunction and plaque development. In this paper we will summarize the different T-cell subsets involved in atherosclerosis and the best characterized autoantigens involved in cardiovascular inflammation.

Human β2-glycoprotein I attenuates mouse intestinal ischemia/reperfusion induced injury and inflammation

Intestinal ischemia-reperfusion (IR)-induced injury results from a complex cascade of inflammatory components. In the mouse model of intestinal IR, the serum protein, β2-glycoprotein I (β2-GPI) binds to the cell surface early in the cascade. The bound β2-GPI undergoes a conformational change which exposes a neoantigen recognized by naturally occurring antibodies and initiates the complement cascade. We hypothesized that providing additional antigen with exogenous β2-GPI would alter IR-induced tissue injury. Administration of human but not mouse β2-GPI attenuated IR-induced tissue damage and prostaglandin E(2) production indicating a physiological difference between β2-GPI isolated from the two species. To investigate whether structural features were responsible for this physiological difference, we compared the chemical, physical and biochemical properties of the two proteins. Despite possessing 76% amino acid identity and 86% sequence homology, we found that mouse β2-GPI differs from the human protein in size, carbohydrate chain location, heterogeneity and secondary structural content. These data suggest that the structural differences result in mouse Ab recognition of soluble human but not mouse β2-GPI and attenuated IR-induced injury. We conclude that caution should be exercised in interpreting results obtained by using human β2-GPI in a mouse model.

Endothelial dysfunction in rheumatic autoimmune diseases

Rheumatic autoimmune diseases have been associated with accelerated atherosclerosis and various types of vasculopathies. Atherosclerosis is an inflammatory condition which starts as a "response to injury" favoring endothelial dysfunction which is associated with increased expression of adhesion molecules, pro-inflammatory cytokines, pro-thrombotic factors, oxidative stress upregulation and abnormal vascular tone modulation. Endothelial dysfunction in rheumatic autoimmune diseases involves innate immune responses, including macrophages and dendritic cells expression of scavenger and toll-like receptors for modified or native LDL as well as neutrophil and complement activation, and dysregulation of adaptive immune responses, including proliferation of autoreactive T-helper-1 lymphocytes and defective function of dendritic and regulatory T cells. Specific differences for endothelial function among different disorders include: a) increased amounts of pro-atherogenic hormones, decreased amounts of anti-atherogenic hormones and increased insulin resistance in rheumatoid arthritis; b) autoantibodies production in systemic lupus erythematosus and antiphospholipid syndrome; c) smooth muscle cells proliferation, destruction of internal elastic lamina, fibrosis and coagulation and fibrinolytic system dysfunction in systemic sclerosis. Several self-antigens (i.e. high density lipoproteins, heat shock proteins, β2-glycoprotein1) and self-molecules modified by oxidative events (i.e. low density lipoproteins and oxidized hemoglobin) have been identified as targets of autoimmune responses. Endothelial dysfunction leads to accelerated atherosclerosis in rheumatoid arthritis, systemic lupus erythematosus and spondyloarthropaties whereas obliterative vasculopathy is associated with systemic sclerosis. In this paper, we will briefly review the most relevant information upon endothelial dysfunction and inflammatory mechanisms in atherosclerosis and we will summarize the similarities and differences in vascular disease patterns underlying different rheumatic autoimmune diseases.

Molecular pathophysiology of the antiphospholipid syndrome: the role of oxidative post-translational modification of beta 2 glycoprotein I

It has been well established that antiphospholipid antibodies and specifically those directed against beta 2 glycoprotein I (β2GPI) are pathogenic for the development of thrombosis in the antiphospholipid syndrome (APS). Several groups have shown that anti-β2GPI antibodies, in complex with β2GPI, elicit effects on blood cells and coagulation-fibrinolysis proteins, which prime the arterial and venous vasculature for the development of thrombosis. However, much less is known about the mechanism initiating the production of autoantibodies against β2GPI, a physiological abundant protein of blood. In the current review, novel findings are presented regarding the structure and oxidative post-translational modifications of β2GPI, which trigger the immune response. The majority of circulating β2GPI exists in a form containing unpaired cysteines (free thiols), which constitutes the reduced form of β2GPI. The free thiols exposed on β2GPI are involved in the interaction with platelets and endothelial cells. We propose that this abundant pool of free thiols may serve as an antioxidant reservoir protecting cells or critical molecules from oxidative stress. Oxidation of β2GPI confers an increase in its immunogenicity through a Th1 immunological mechanism. The clinical significance of these observations is that serum from patients with APS, assessed by a novel ELISA assay, have a significant increase in oxidised β2GPI. These findings hold promise, not only for the delineation of the role of β2GPI as an immunological target, but also for the development of improved diagnostic and prognostic assays for APS.

β(2) -Glycoprotein I: evolution, structure and function

β(2) -Glycoprotein I (β(2) -GPI) is a protein that circulates in blood at high concentrations. The function of β(2) -GPI has long been an enigma. More than 20 years ago, it was discovered that β(2) -GPI is the major antigen for the circulating antibodies in the antiphospholipid syndrome. However, this knowledge has not advanced our understanding of the physiologic role of the protein. In recent years, new insights have suggested an important function of this protein in innate immunity. β(2) -GPI was found to scavenge lipopolysaccharide and was able to clear unwanted anionic cellular remnants such as microparticles from the circulation. The function of β(2) -GPI seems to depend on the structural conformation of the protein, and it has been established that β(2) -GPI can exist in at least two conformations. In this review, we will highlight and summarize the current knowledge on this protein.

Oxidative stress in cardiovascular inflammation: its involvement in autoimmune responses

Recently, it has become clear that atherosclerosis is a chronic inflammatory disease in which inflammation and immune responses play a key role. Accelerated atherosclerosis has been reported in patients with autoimmune diseases, suggesting an involvement of autoimmune mechanisms in atherogenesis. Different self-antigens or modified self-molecules have been identified as target of humoral and cellular immune responses in patients with atherosclerotic disease. Oxidative stress, increasingly reported in these patients, is the major event causing structural modification of proteins with consequent appearance of neoepitopes. Self-molecules modified by oxidative events can become targets of autoimmune reactions, thus sustaining the inflammatory mechanisms involved in endothelial dysfunction and plaque development. In this paper, we will summarize the best characterized autoantigens in atherosclerosis and their possible role in cardiovascular inflammation.

Toll-like receptors play a crucial part in the pathophysiological activity of antiphospholipid antibodies

The antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by thrombosis, recurrent fetal loss and the presence of a variety of antiphospholipid antibodies (aPL), directed to phospholipids like Cardiolipin and phospholipid binding proteins like β2-glycoprotein I. Till date, the pathophysiological processes underlying these thrombotic events were still not fully understood. Recent data support the idea that the aPL might act via enhanced cytokine release due to activation of certain Toll-like receptors. The investigation of some of those mechanisms in more detail enlightens the involvement of the intracellular receptors TLR7 and TLR8 in a central point. Using patients’ IgG fractions and/or monoclonal aPL, either generated from mouse or from human B-cells for the stimulation experiments of monocytes, endothelial cells or dendritic cells, all these stimuli induced an enhanced expression and secretion of cytokines, especially TNFα, caused by specific regulation or activation of Toll-like receptors. Using specific agonists or inhibitors could confirm the causal connection of these stimulatory effects. This review focuses on the recent developments connecting the binding of aPL with the activity of Toll-like receptors, especially in monocytes, endothelial cells and dendritic cells.

Advanced glycation end products of human β₂ glycoprotein I modulate the maturation and function of DCs

In chronic disorders related to endothelial cell dysfunction, plasma β₂ glycoprotein I (β₂GPI) plays a role as a target antigen of pathogenetic autoimmune responses. However, information is still lacking to clarify why β₂GPI triggers autoimmunity. It is possible that posttranslational modification of the protein, such as nonenzymatic glycosylation, leads to the formation of advanced glycation end products (AGEs). The aim of our study was to explore whether glucose-modified β₂GPI is able to interact and activate monocyte-derived immature dendritic cells (iDCs) from healthy human donors. SDS-PAGE and spectrofluorometric analyses indicated that β₂GPI incubated with glucose was sugar modified, and that this modification likely consisted of AGE formation, resulting in AGE-β₂GPI. AGE-β₂GPI caused phenotypical and functional maturation of iDCs involving the activation of p38 MAPK, ERK, and NF-κB. It also induced on DCs a significant up-regulation of RAGE, the receptor for AGEs. Evidence for RAGE involvement comes from blocking experiments with an anti-RAGE mAb, confocal analysis, and coimmunoprecipitation experiments. AGE-β₂GPI-stimulated DCs had increased allostimulatory ability and primed naive T lymphocytes toward a Th2 polarization. These findings might explain in part the interactive role of β₂GPI, AGEs, and DCs in chronic disorders related to endothelial cell dysfunction.

Pollen-induced oxidative stress influences both innate and adaptive immune responses via altering dendritic cell functions

It has been demonstrated that pollen grains contain NAD(P)H oxidases that induce oxidative stress in the airways, and this oxidative insult is critical for the development of allergic inflammation in sensitized mice. On the basis of this observation, we have examined whether pollen grain exposure triggers oxidative stress in dendritic cells (DCs), altering their functions. To test this hypothesis, human monocyte-derived DCs were treated with ragweed pollen grains. Our findings show that exposure to pollen grains induces an increase in the intracellular levels of reactive oxygen species in DCs. Our data also indicate that besides the NAD(P)H oxidases, other component(s) of pollen grains contributes to this phenomenon. Elevated levels of intracellular reactive oxygen species triggered the production of IL-8 as well as proinflammatory cytokines, such as TNF-alpha and IL-6. Treatment with pollen grains initiated the maturation of DCs, strongly upregulated the membrane expression of CD80, CD86, CD83, and HLA-DR, and caused only a slight increase in the expression of CD40. The pollen-treated DCs induced the development of naive T lymphocytes toward effector T cells with a mixed profile of cytokine production. Antioxidant inhibited both the phenotypic and functional changes of DCs, underlining the importance of oxidative stress in these processes. Collectively, these data show that pollen exposure-induced oxidative stress may contribute to local innate immunity and participate in the initiation of adaptive immune responses to pollen Ags.

Beta2-Glycoprotein I is a Target of T Cell Reactivity in Patients with Advanced Carotid Atherosclerotic Plaques

Evidence in animal models that beta2-glycoprotein I (β2GPI), the principal target of autoimmune antiphospholipid antibodies, is involved in the initiation and progression of atherosclerosis, prompted us to investigate the possible role of this self protein as a target autoantigen of immune reactions in patients with carotid atherosclerosis. Plaque-infiltrating T lymphocytes from patients, and circulating T lymphocytes from patients and healthy subjects were tested by cell proliferation assay and by flow cytometry for intracellular cytokine expression in response to β2GPI. ELISA was used to detect cytokine production in culture supernatants and anti-β2GPI/anti-cardiolipin antibodies in serum samples. Eight of 35 PBMC samples and 1 of 5 plaque-infiltrating T lymphocyte samples from patients proliferated in response to β2GPI, whereas PBMC from healthy subjects did not. Patients' PBMC samples that proliferated in response to β2GPI produced significantly higher IFN-γ and TNF-α than non-proliferating PBMC. β2GPI-specific plaque-derived T lymphocytes expressed IFN-γ, TNF-α and IL-4, suggesting concomitant Th1 and Th2 activation. Only one patient's serum was positive for anti-β2GPI and anti-cardiolipin IgM antibodies. These new findings indicate that β2GPI induces a cellular immune response in a subpopulation of patients with carotid atherosclerosis thus contributing to the inflammatory responses involved in carotid atherosclerotic disease.

T cells demonstrate a Th1-biased response to native beta2-glycoprotein I in a murine model of anti-phospholipid antibody induction

Anti-phospholipid syndrome (APS) is an autoimmune disorder characterized by the presence of autoantibody (AAb) to phospholipid (PL)-binding proteins, such as beta2-glycoprotein I (beta2GPI), and clinical manifestations including thrombosis and/or recurrent pregnancy loss. beta2GPI-reactive T cells are clearly implicated in the generation of these AAb, but the mechanism responsible for their activation remains unclear. We hypothesized that immunization of mice with human beta2GPI, in the context of a potent innate immune activator lipopolysaccharide (LPS), would generate not only high titers of anti-PL AAb, but also a strong beta2GPI-specific T cell response. Healthy, nonautoimmune C57BL/6 mice were immunized repeatedly with human beta2GPI in the presence of LPS. High titers of anti-PL to beta2GPI appeared after the second immunization, with T cell reactivity to beta2GPI detectable only after the fourth immunization. Splenic T cells from these mice proliferated in response to native beta2GPI, alone or bound to anionic PL. These T cells produced IL-2 and IFN-gamma, but not IL-4 or IL-10, indicating a Th1 bias of the beta2GPI-specific response. These findings suggest that T cells responsive to beta2GPI may become activated in APS patients by exposure to their cognate Ag in the context of innate immune activation and a pro-inflammatory environment.

Immunology and genetics of type 1 diabetes

Type 1 diabetes is one of the most well-characterized autoimmune diseases. Type 1 diabetes compromises an individual's insulin production through the autoimmune destruction of pancreatic beta-cells. Although much is understood about the mechanisms of this disease, multiple potential contributing factors are thought to play distinct parts in triggering type 1 diabetes. The immunological diagnosis of type 1 diabetes relies primarily on the detection of autoantibodies against islet antigens in the serum of type 1 diabetes mellitus patients. Genetic analyses of type 1 diabetes have linked human leukocyte antigen, specifically class II alleles, to susceptibility to disease onset. Environmental catalysts include various possible factors, such as viral infections, although the evidence linking infections with type 1 diabetes remains inconclusive. Imbalances within the immune system's system of checks and balances may promote immune activation, while undermining immune regulation. A lack of proper regulation and overactive pathogenic responses provide a framework for the development of autoimmune abnormalities. Type 1 diabetes is a predictable and potentially treatable disease that still requires much research to fully understand and pinpoint the exact triggering events leading to autoimmune activation. In silico research can aid the comprehension of the etiology of complex disease pathways, including Type I diabetes, in order to and help predict the outcome of therapeutic strategies aimed at preserving beta-cell function.

Oxidized haemoglobin as antigenic target of cell-mediated immune reactions in patients with carotid atherosclerosis

Atherosclerosis is a chronic inflammatory disease in which immune responses play a crucial role. Evidence exist demonstrating the involvement of autoimmune mechanisms in atherogenesis. Our aim in this study was to evaluate the possible role of human oxidized haemoglobin (Hb) as antigenic target of cell-mediated immune reactions in carotid atherosclerosis. PBMC from 44 patients and 24 healthy subjects, and T lymphocytes isolated from 9 carotid atherosclerotic plaques were tested by cell proliferation assay and by ELISA for cytokine production in response to oxidized Hb. This molecule induced a proliferative response in 21 of 44 (48%) patients' PBMC samples, in 12 of 24 (50%) healthy subjects' PBMC samples and in 2 of 9 (22%) infiltrating T lymphocyte samples. Cells from patients proliferating in response to oxidized Hb showed high levels of the pro-inflammatory cytokines interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha. Our findings implicate oxidized Hb as a possible antigenic target of cell-mediated immune responses contributing to inflammation in the pathogenesis of carotid atherosclerosis.

Chronic and Acute Alcohol Exposure Prevents Monocyte-Derived Dendritic Cells from Differentiating and Maturing

Increasing evidence suggests that alcohol abuse may be linked to adverse immunomodulatory effects on immune responses. Our study was undertaken to clarify the immunological consequences of chronic and acute alcohol exposure on differentiation and maturation of human dendritic cells (DCs). Using immunochemical and cytofluorimetric analysis we determined the phenotype and functions of monocyte-derived DCs from alcoholics and healthy subjects and analyzed their ability to respond to lipopolysaccharide (LPS) in the presence or absence of ethanol (EtOH) exposure. Our results showed that alcoholics' monocytes differentiated to immature DCs with altered phenotype and functions (alc-iDCs). Alc-iDCs showed fewer CD1a+ cells, weaker CD86 expression and higher HLA-DR expression associated with lower endocytosis and allostimulatory functions than iDCs from healthy subjects (control-iDCs). Despite these impairments, alc-iDCs produced TNF-α and IL-6 in large amounts. LPS stimulation failed to induce full phenotypical and functional alc-iDC maturation. In vitro acute EtOH exposure also prevented alc-iDCs and control-iDCs from maturing in response to LPS. T-cell priming experiments showed that EtOH treatment prevented LPS-stimulated control-iDCs from priming and polarizing naïve allogeneic T cells into Th1 cells, thus favouring a predominant Th2 environment. Collectively, our results provide evidence that chronic and acute alcohol exposure prevents DCs from differentiating and maturing in response to a microbial stimulus.

Vascular cells contribute to atherosclerosis by cytokine- and innate-immunity-related inflammatory mechanisms

Cardiovascular diseases are the human diseases with the highest death rate and atherosclerosis is one of the major underlying causes of cardiovascular diseases. Inflammatory and innate immune mechanisms, employing monocytes, innate receptors, innate cytokines, or chemokines are suggested to be involved in atherogenesis. Among the inflammatory pathways the cytokines are central players. Plasma levels of cytokines and related proteins, such as CRP, have been investigated in cardiovascular patients, tissue mRNA expression was analyzed and correlations to vascular diseases established. Consistent with these findings the generation of cytokine-deficient animals has provided direct evidence for a role of cytokines in atherosclerosis. In vitro cell culture experiments further support the suggestion that cytokines and other innate mechanisms contribute to atherogenesis. Among the initiation pathways of atherogenesis are innate mechanisms, such as toll-like-receptors (TLRs), including the endotoxin receptor TLR4. On the other hand, innate cytokines, such as IL-1 or TNF, or even autoimmune triggers may activate the cells. Cytokines potently activate multiple functions relevant to maintain or spoil homeostasis within the vessel wall. Vascular cells, not least smooth muscle cells, can actively contribute to the inflammatory cytokine-dependent network in the blood vessel wall by: (i) production of cytokines; (ii) response to these potent cell activators; and (iii) cytokine-mediated interaction with invading cells, such as monocytes, T-cells, or mast cells. Activation of these pathways results in accumulation of cells and increased LDL- and ECM-deposition which may serve as an 'immunovascular memory' resulting in an ever-growing response to subsequent invasions. Thus, vascular cells may potently contribute to the inflammatory pathways involved in development and acceleration of atherosclerosis.