Antiphospholipid antibodies affect trophoblast gonadotropin secretion and invasiveness by binding directly and through adhered beta2-glycoprotein I

OBJECTIVE

To investigate the in vitro ability of antiphospholipid antibodies (aPL) to bind human trophoblast cells and to affect gonadotropin secretion and invasiveness.

METHODS

Antiphospholipid antibody IgG from women with recurrent miscarriages, beta2-glycoprotein I (beta2GPI)-independent IgG aPL human monoclonal antibody (mAb) (519), and IgM anti-beta2GPI human mAb (TMIG2) were investigated for their binding to trophoblasts cultured for various amounts of time, their ability to affect invasiveness of Matrigel-coated filters, and their release of human chorionic gonadotropin (hCG).

RESULTS

Polyclonal IgG aPL, as well as mAb 519 and TMIG2, bound to trophoblasts, the highest binding being found when cells displayed the greatest amount of syncytium formation. TM1G2 binding was found to be betaGPI dependent. Both polyclonal and monoclonal aPL, but not the controls, significantly reduced hCG release and Matrigel invasiveness.

CONCLUSION

These findings suggest that aPL recognition of both anionic PL and adhered beta2GPI on trophoblast cell structures might represent a potential pathogenetic mechanism for defective placentation in women with the antiphospholipid syndrome.

Statins prevent endothelial cell activation induced by antiphospholipid (anti-beta2-glycoprotein I) antibodies: effect on the proadhesive and proinflammatory phenotype

OBJECTIVE

To investigate the ability of statins, the inhibitors of the hydroxymethylglutaryl-coenzyme A reductase enzyme, to affect endothelial cell activation induced by anti-beta2-glycoprotein I (anti-beta2GPI) antibodies in vitro.

METHODS

Human umbilical vein endothelial cell (HUVEC) activation was evaluated as U937 monocyte adhesion, E-selectin, and intercellular adhesion molecule I (ICAM-1) expression by cell enzyme-linked immunosorbent assay and as interleukin-6 (IL-6) messenger RNA (mRNA) expression by RNA protection assay. E-selectin-specific nuclear factor kappaB (NF-kappaB) DNA-binding activity was evaluated by the gel-shift assay. HUVECs were activated by polyclonal affinity-purified IgG, human monoclonal IgM anti-beta2GPI antibodies, human recombinant IL-1beta, tumor necrosis factor alpha, or lipopolysaccharide (LPS).

RESULTS

Fluvastatin reduced, in a concentration-dependent manner (1-10 microM), the adhesion of U937 to HUVECs and the expression of E-selectin and ICAM-1 induced by anti-beta2GPI antibodies as well as by cytokines or LPS. Another lipophilic statin, simvastatin, displayed similar effects but to a lesser extent than fluvastatin. The inhibition of E-selectin expression exerted by fluvastatin was related to the impairment of NF-kappaB binding to DNA. Moreover, the drug attenuated the expression of IL-6 mRNA in HUVEC exposed to anti-beta2GPI antibodies or cytokines. Incubation of HUVECs with mevalonate (100 microM), concomitantly with fluvastatin, greatly prevented the inhibitory effect of statin.

CONCLUSION

Endothelial activation mediated by anti-beta2GPI antibody can be inhibited by statins. Because of the suggested role of endothelial cell activation in the pathogenesis of antiphospholipid syndrome (APS), our data provide, for the first time, a rationale for using statins as an additional therapeutic tool in APS.

Infectious origin of the antiphospholipid syndrome

From a systemic disease towards the infectious aetiology

Anti-C1q antibodies may help in diagnosing a renal flare in lupus nephritis

It is still uncertain which, if any, immunologic parameters may help diagnose a renal flare of lupus nephritis. Anti-C1q antibody (Ab) titers have been elevated in patients with lupus with renal involvement, but little information is available on whether the titers are different in quiescent and active phases of lupus nephritis. In this study, we compared anti-C1q Ab titers with other serological test results in 48 patients with biopsy-proven lupus nephritis to assess which parameter could offer the best reliability for differentiating between quiescent and active phases of lupus nephritis. Serum C3 and C4 levels, as well as anti-double-stranded DNA, antiendothelial cell, anti-C1q, and antiphospholipid Ab titers, were evaluated in patients with quiescent renal disease (38 samples) and those with clinical evidence of renal activity (23 samples). Only anti-C1q Ab titers correlated with active renal disease in both univariate (P < 0.0001) and multivariate analysis (P < 0.0001), with a sensitivity of 87% and a specificity of 92%. In six patients, immunologic parameters were measured serially. In all patients, the high anti-C1q Ab titers returned to normal values after treatment-induced remission. The other serological parameters did not show a significant association with renal disease activity. In patients with biopsy-proven lupus nephritis, anti-C1q Ab titers appear to be strongly related to renal disease activity. Their measurement may be useful for confirming the diagnosis of renal flares of lupus nephritis.

Adverse cardiovascular events associated with triptans and ergotamines for treatment of migraine: systematic review of observational studies

BACKGROUND

Apart from the underlying cardiovascular (CV) risk associated with migraine, both triptans and ergotamines can induce vasoconstriction and potentially increase the risk of serious ischemic events. Because of the low frequency of such events in eligible patients, randomized controlled trials are not exhaustive to assess the drug-related CV risk. Observational studies are, therefore, an essential source of information to clarify this matter of concern.

AIM

The aim of this study was to systematically review the available published observational studies investigating the risk of serious CV events in triptan or ergotamine users, as compared to unexposed migraineur controls.

METHODS

We systematically searched MEDLINE and EMBASE electronic databases for cohort or case-control studies up to December 1, 2013. Studies retrieved from CDSR, DARE and HTA databases of the Cochrane Library were used for snowballing. Studies investigating the risk of any CV outcome in patients with a migraine diagnosis and exposed to triptans or ergotamines were considered for inclusion. Selection of studies, data extraction, and risk of bias assessment were conducted independently by two reviewers. Pooled odds ratios (ORs) with 95% confidence interval (95% CI) were computed using a random-effects model for studies and outcomes judged eligible for quantitative data synthesis.

RESULTS

From a total of 3370 citations retrieved, after duplicate removal and screening, only four studies met the inclusion criteria (three nested case-control analyses and one retrospective cohort study). These studies investigated the risk of different CV outcomes associated with either the recency or the intensity of exposure to the studied drugs. As for the intensity of use, the pooled OR of serious ischemic events was 2.28 (95% CI 1.18-4.41; I (2 )= 0%) for ergotamine use (two studies), whereas for triptans (three studies) it was 0.86 (95% CI 0.52-1.43; I (2 )= 24.5%). Recent use of ergotamines was not significantly associated with any CV outcome (only one available study). Two studies investigated the risk of stroke related to recent triptan use: the first study reported an OR of 0.90 (0.64-1.26), and the second one suggested an increased risk of 2.51 (1.10-5.71). In this case, because of the high degree of heterogeneity, results were not pooled.

CONCLUSIONS

To date, few comparative observational studies have investigated the CV safety of migraine-specific drugs in clinical practice. Evidence gathered here suggests that intense consumption of ergotamines may be associated with an increased risk of serious ischemic complications. As for triptans, available studies do not suggest strong CV safety issues, although no firm conclusions can be drawn. In particular, evidence on stroke risk is conflicting. However, if an increase of the absolute stroke risk in recently exposed patients does actually exist, it must be small. Overall, residual uncontrolled confounding factors reduce the confidence in the risk estimates collected from the included studies. Further investigations are needed to better define the risk for rare but serious CV events related to triptan and ergotamine use for treatment of migraine.

Endothelium and the brain in CNS lupus

Central nervous system (CNS) involvement in systemic lupus erythematosus (SLE) is common and results in different clinical manifestations. Several pathogenic mechanisms have been suggested to play a rolein determiningsuch a varietyof clinicalsymptoms.The thrombophilicstateassociatedto the presence of antiphospholipidantibodies has been suggested to be responsible for a noninflammatory vasculopathywhichcauses clear ischaemiceventsas well as alterationsof the cerebralmicrocirculation that are likely associated to seizures, cognitive dysfunction or psychosis. Although less frequent, a true vasculitic process affecting cerebral circulation has also been reported. In both cases, brain endothelium does represent the target of the pathogenic mechanisms. Brain endothelial cells display peculiar functional and phenotypical characteristics in comparison with endothelial cells from other anatomical districts, raising the possibility that this might be the reason for its susceptibility in lupus disease. We review and present data suggesting that a higher and firmer expression of beta 2 glycoprotein I on endothelialcell membranes can be responsiblefor a selective damage/activation by circulating anti-beta 2 glycoprotein I, and that antiendothelial cell antibodies crossreact with brain endothelium and in some cases, specifically bind brain endothelial cells only in lupus patients with central nervous involvement.

Pharmacovigilance of sodium-glucose co-transporter-2 inhibitors: What a clinician should know on disproportionality analysis of spontaneous reporting systems

Sodium-glucose co-transporter-2 inhibitors (SGLT2-Is) have consistently demonstrated a clinically significant reduction of cardiovascular mortality. However, their safety in clinical practice is still incompletely characterized, and post-marketing monitoring is required considering the expected increase in clinical use. Different analyses of international spontaneous reporting systems, known as disproportionality analyses (DAs), have highlighted the occurrence of ketoacidosis, amputations, acute renal failure and skin toxicity. In this viewpoint, we critically appraise these pharmacovigilance data on SGLT2-Is, with the aim of supporting clinicians in proper interpretation of these studies, and discussing their risk-benefit profile. To this aim, we offer a broad perspective on basic technical aspects subtending DAs of spontaneous reporting databases (describing peculiarities of the Food and Drug Administration Adverse Event Reporting System), their common and evolving uses, key pitfalls in presenting study results (in terms of "risk" or "association") and relevant strategies to account for major confounders. This will also facilitate reviewers and editors in proper evaluation of DAs, and prompt pharmacovigilance experts in converging towards a set of minimum requirements in standardization of design, performance and reporting of DAs. A consensus on quality assessment of DAs will finally establish their transferability to clinical practice. It is anticipated that DAs cannot be used per se as a standalone approach to assess a drug-related risk and cannot replace clinical judgment in the individual patient.

Pathogenic role of anti-beta 2-glycoprotein I antibodies in antiphospholipid associated fetal loss: characterisation of beta 2-glycoprotein I binding to trophoblast cells and functional effects of anti-beta 2-glycoprotein I antibodies in vitro

BACKGROUND

Antiphospholipid antibodies reacting with beta2-glycoprotein I (beta 2GPI) have been associated with recurrent fetal loss and pregnancy complications.

OBJECTIVE

To investigate whether specific mutations in the phospholipid binding site of beta 2GPI might affect its binding to trophoblast and in turn the anti-beta 2GPI antibody induced functional effects.

METHODS

beta 2GPI adhesion to trophoblast was evaluated as human monoclonal IgM or polyclonal IgG anti-beta 2GPI antibody binding to trophoblast monolayers cultured (1) in complete medium; (2) in serum-free medium; (3) after serum starvation in the presence of purified human beta 2GPI; or (4) in the presence of beta 2GPI with single or multiple mutations in the amino acid loop Cys(281)-Lys-Asn-Lys-Glu-Lys-Lys-Cys(288). The effect of anti-beta 2GPI binding to trophoblast was evaluated as chorionic gonadotropin (hCG) mRNA expression, and protein release by RT-PCR and radioimmunoassay, respectively.

RESULTS

beta 2GPI adhesion to trophoblast and its consequent recognition by the specific antibodies were inversely proportional to the mutation number in the phospholipid binding site. Anti-beta 2GPI antibodies reduced gonadotropin release, hormone dependent hCG mRNA expression, and protein synthesis in the presence of beta 2GPI, while the addition of the mutants or the absence of beta 2GPI had no effect.

CONCLUSIONS

beta 2GPI binds to trophoblast in vitro through its fifth domain, as reported for endothelial cells, and can be recognised by anti-beta 2GPI antibodies; the antibody binding downregulates trophoblast hCG synthesis and secretion. Such a mechanism might contribute to defective placentation in women with fetal loss associated with the antiphospholipid syndrome.

The association of pancreatitis with antidiabetic drug use: gaining insight through the FDA pharmacovigilance database

In patients with diabetes, disease per se, co-morbidities and drugs, including novel agents acting on the incretin system, have all been associated with pancreatitis with controversial data. We investigated the publicly available FDA Adverse Event Reporting System (FDA_AERS) database to gain insight into the possible association between antidiabetic agents and pancreatitis. To this aim, a case/non-case method was retrospectively performed on the FDA_AERS database (2004-2009 period). Cases were defined as reports of pancreatitis according to the Medical Dictionary for Regulatory Activities (MedDRA) terminology. All other reports associated with antidiabetics were considered non-cases. The Reporting Odds Ratio (RORs), with corresponding 95% confidential interval (CI) and Mantel-Haenszel corrected P value, was calculated as a measure of disproportionality, with subsequent time-trend analysis. We retrieved 86,938 reports related to antidiabetics, corresponding to 159,226 drug-report combinations: 2,625 cases and 156,601 non-cases. Disproportionality was found only for exenatide (number of cases, 709; ROR, 1.76; 95% CI, 1.61-1.92; P MH < 0.001) and sitagliptin (128; 1.86; 1.54-2.24; <0.001). For exenatide, significant disproportionality appeared in the first quarter of 2008 (ROR, 1.24; 95% CI, 1.10-1.40; P MH < 0.001), soon after the FDA alert; for sitagliptin in the second quarter of 2008 (1.41; 1.05-1.90; 0.021). This temporal analysis found a striking influence of relevant FDA warnings on reporting of pancreatitis (the so-called notoriety bias) and is, therefore, recommended to avoid transforming a pharmacovigilance signal of alert automatically into an alarm. The precise quantification of the risk of pancreatitis associated with antidiabetics deserves assessment through specific disease-based registries.

Endothelial cell activation by antiphospholipid antibodies

Antiphospholipid antibodies are mainly directed against beta 2 glycoprotein I, a phospholipid-binding protein expressed on endothelial cell membranes of different anatomical localizations and recognized by the specific autoantibodies. Antibody binding induces an endothelial activation both in in vitro and in vivo experimental models that might contribute to the prothrombotic state. Endothelial beta 2 glycoprotein I adhesion is mediated by the electrostatic interaction between its cationic phospholipid binding site and anionic structures on the cell membrane; however, binding to annexin II--the endothelial cell receptor for tissue plasminogen activator--plays also a role. Anti-beta-2 glycoprotein I antibodies up-regulate mRNA expression of pro-inflammatory mediators through NF-kappaB translocation and the signaling cascade triggered by Toll-like receptors. Because of the molecular mimicry between beta 2 glycoprotein I and viral/bacterial structures-the natural ligands for Toll-like receptors (TLR)-antibodies might cross-link the molecule associated to the receptors eventually triggering their signaling.

Anti-endothelial cell IgG fractions from systemic lupus erythematosus patients bind to human endothelial cells and induce a pro-adhesive and a pro-inflammatory phenotype in vitro

Affinity purified immunoglobulin G (IgG) fractions from systemic lupus erythematosus (SLE) patients positive for anti-endothelial cell antibodies (AECA) bind human umbilical vein endothelial cell (HUVEC) monolayers. In vitro incubation of serial protein concentrations of SLE AECA IgG induces a dose-dependent endothelial activation: i) increase of functional adhesion of the monocytic cell line U937; ii) upregulation of E-Selectin, ICAM-1, VCAM-1 expression evaluated by a cell solid-phase enzyme linked immunoassay; and iii) increased secretion of interleukin (IL)-6 in the culture supernatants. Control experiments carried out with HUVEC monolayers incubated with IgG fractions from normal healthy controls or from AECA negative SLE sera do not affect at all endothelial adhesion molecule expression or pro-inflammatory cytokine secretion. The AECA IgG effects are not related to both anti-phospholipid or anti-DNA activities. Taken together the findings suggest that these autoantibodies might be important in recruiting and in activating mononuclear leukocytes responsible for vessel wall infiltration and raise the possibility that AECA might display a pathogenic role in SLE vessel damage.

Inflammatory response and the endothelium

Antiphospholipid-mediated endothelium perturbation plays a role in antiphospholipid syndrome (APS)-associated vasculopathy. Antiphospholipid antibodies activate endothelium both in vitro and in vivo experimental models by inducing a pro-inflammatory/-coagulant phenotype; the antibodies recognize beta2 glycoprotein I (beta2GPI) on human endothelial cells (EC) from different parts of the vasculature. In spite of such large in vitro evidence, few studies have addressed the issue whether or not a comparable endothelial perturbation might be detectable in vivo. We investigated several indirect ex vivo parameters of endothelial dysfunction: plasma levels of soluble adhesion molecules (sADM), soluble thrombomodulin (sTM), von Willebrand factor (vWF) and tissue plasminogen activator (t-PA) by solid-phase assays. The study included: patients with primary antiphospholipid syndrome (n=32), with the syndrome secondary to non-active systemic lupus erythematosus (SLE, n=10), six patients with persistent antiphospholipid positivity at medium/high titre without any clinical manifestation of the syndrome. Fifty-two age and sex matched healthy subjects have been enrolled as controls. In addition, circulating endothelial cells identified by flow cytometry and the brachial artery flow-mediated vasodilation (FMV) were evaluated in 26 patients (20 primary and 6 lupus syndromes) and 30 healthy controls. Plasma levels of soluble adhesion molecules did not differ from controls, while a significant increase in von Willebrand factor titres (P<0.05) was found. No significant difference was found regarding the number of circulating endothelial cells and flow-mediated vasodilation. As a whole, these findings do suggest that antiphospholipid antibodies per se are not able to support a full-blown endothelial perturbation in vivo. As shown in antiphospholipid syndrome experimental animal models, a two-hit hypothesis is suggested.

Toll-like receptors: another player in the pathogenesis of the anti-phospholipid syndrome

The anti-phospholipid syndrome (APS) is a systemic autoimmune disease characterized by an adaptive immune response against self phospholipid (PL)--binding proteins. Although APS is considered as an autoantibody-mediated disease, there is now evidence that anti-phospholipid antibodies (aPL) are necessary but not sufficient to trigger some of the clinical manifestations of the syndrome. For example, mediators of the innate immunity are recognized to be additional second hits able to induce the thrombotic events in the presence of aPL. Finally, environmental agents - in particular infectious ones - were reported to act as triggers for the production of autoantibodies cross-reacting with PL-binding proteins as well as inflammatory stimuli that potentiate the aPL thrombogenic effect. Altogether, these findings suggest a role for the innate immunity in APS pathogenesis. Toll-like receptors (TLR) are receptors that induce prompt inflammatory responses and mediate functional activation in immune effector cells. There is evidence that aPL, and in particular anti-beta(2) glycoprotein I (beta(2)GPI) antibodies, may activate endothelial cells and monocytes through TLR-4-dependent signalling. Whether or not TLR may behave as surface receptors for beta(2)GPI is still matter of research. Drugs or molecules able to interfere with TLR involvement may represent new therapeutic approaches for APS.

Endothelial cells as a target for antiphospholipid antibodies: role of anti-beta 2 glycoprotein I antibodies

PROBLEM

To investigate the role of the plasma cofactor for antiphospholipid antibodies in antibody binding to endothelial cells.

METHOD OF STUDY

a) Evaluation of endothelial cell binding of polyclonal and monoclonal anti-beta 2 glycoprotein I antibodies; and b) study of the effects of antibody binding: adhesion molecule expression, leukocyte adhesion, and interleukin-1 beta secretion.

RESULTS

Anti-beta 2 glycoprotein I antibodies bind endothelial cell monolayers in vitro by reacting with the cofactor adhered to the cell membranes. Antibody binding induces an up-regulation of adhesion molecules, favours leukocyte adherence, and increases interleukin-1 beta secretion. Interleukin-1 beta plays an active role to mediate adhesion molecule expression through an autocrine loop, as shown by the inhibitory effect of interleukin 1 receptor antagonist.

CONCLUSIONS

Antiphospholipid antibodies do react with endothelium through the co-factor adhered to their cell membranes and induces a pro-adhesive cell phenotype.

Innate immunity in the antiphospholipid syndrome: role of toll-like receptors in endothelial cell activation by antiphospholipid antibodies

Antiphospholipid antibodies are mainly directed against beta 2 glycoprotein I (beta2GPI), a plasma phospholipid-binding protein expressed on endothelial cells of different anatomical localizations. Anti-beta2GPI antibodies recognize the molecule on endothelial monolayers in vitro, and, once bound, might activate the cells both in vitro and in vivo experimental models inducing a proinflammatory and a procoagulant phenotype. Cell activation is associated with nuclear factor-kappaB (NF-kappaB) translocation and with a signaling cascade comparable to that triggered by the toll-like receptors (TLRs)-4. The cell membrane receptor(s) for beta2GPI adhesion is still under investigation. It has been suggested that beta2GPI might adhere through electrostatic interaction between its cationic phospholipid binding site and anionic structures on the cell membrane; however, binding to annexin II-the endothelial cell receptor for tissue plasminogen activator-plays also a role. Because annexin II does not display any transmembrane protein, it has been suggested that it requires a yet unknown "adaptor" protein to signal the cells. Because of the molecular mimicry between beta2GPI and viral/bacterial structures-the natural ligands for TLRs-antibodies might cross-link the molecule associated to annexin II and TLR-4 eventually triggering the signaling.

Antiphospholipid antibodies and the endothelium

The interaction between aPL (particularly anti-beta 2GPI antibodies) and endothelium does represent a potential pathogenetic mechanism for the thrombotic manifestations of the syndrome. The autoantibody-mediated EC activation probably plays a role in sustaining the appearance of a proadhesive, proinflammatory, and procoagulant phenotype. The heterogeneity of the APS clinical manifestations is likely linked to the varied effects that aPL can induce on ECs and to the different functions that ECs display depending on the anatomic localization.

Beta2-glycoprotein I as a 'cofactor' for anti-phospholipid reactivity with endothelial cells

Beta2-glycoprotein I (beta2GPI) is a cofactor for anti-phospholipid (aPL) binding to cardiolipin (CL)-coated plates. Beta2GPI is also able to bind to endothelial cell (EC) membranes as supported by in-vivo as well as by in-vitro studies. The PL-binding site in the fifth domain of the molecule is involved in the adhesion to endothelium. Actually, specific mutations in this molecular portion abolish endothelium binding and a synthetic peptide spanning the sequence Glu274-Cys288 of the CL-binding site displays comparable adhesion to EC monolayers. Heparan sulphate appears to be one of the anionic EC membrane structures with which cationic beta2GPI interacts, as supported by studies with heparitinase-treated EC. Beta2GPI binding to EC might be related to its activity as endothelial growth factor or as a lipid-carrying glycoprotein. Adhesion of beta2GPI to endothelial membranes offers suitable epitopes for circulating aPL that, once bound, can induce cell activation

Decreased expression of heparin-binding epidermal growth factor-like growth factor as a newly identified pathogenic mechanism of antiphospholipid-mediated defective placentation

OBJECTIVE

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) plays a role in blastocyst implantation and is down-regulated in preeclampsia and in hypertensive pregnancy disorders associated with defective extravillous trophoblast invasion. Defective placentation and severe preeclampsia are also features of the antiphospholipid syndrome (APS). The purpose of this study was to investigate whether abnormal HB-EGF expression plays a pathogenic role in antiphospholipid antibody (aPL)-mediated defective placentation.

METHODS

HB-EGF expression in placental tissue was evaluated by Western blotting and messenger RNA analysis in normal and APS placentae. Polyclonal IgG fractions or monoclonal beta(2)-glycoprotein I-dependent aPL and their respective controls were investigated for the following 4 features: their binding to human trophoblast monolayers, as determined by cell enzyme-linked immunosorbent assay (ELISA); their effect on HB-EGF expression by Western blotting in trophoblast cell extracts as well as by ELISA as a protein secreted in the culture supernatants; their inhibitory effect on in vitro trophoblast invasiveness, as evaluated by Matrigel assay; and their inhibitory effect on matrix metalloproteinase (MMP) levels, as measured by gelatin zymography. Experiments were also performed in the presence of serial concentrations of heparin or recombinant HB-EGF.

RESULTS

Placental APS tissue displayed reduced expression of HB-EGF. Polyclonal and monoclonal aPL bound to trophoblast monolayers and significantly reduced the in vitro synthesis and secretion of HB-EGF. Heparin inhibited aPL binding and restored HB-EGF expression in a dose-dependent manner. Addition of recombinant HB-EGF reduced the in vitro aPL-induced inhibition of Matrigel invasiveness as well as MMP-2 levels.

CONCLUSION

These preliminary findings suggest that the reduction of aPL-mediated HB-EGF represents an additional mechanism that is responsible for the defective placentation associated with APS and that heparin protects from aPL-induced damage by inhibiting antibody binding.

Obstetric and vascular APS: Same autoantibodies but different diseases?

Beta2 glycoprotein I (β2GPI)-dependent antiphospholipid antibodies (aPLs) are the main pathogenic autoantibody population and at the same time the laboratory diagnostic tool for the antiphospholipid syndrome (APS).

These antibodies are responsible for both the vascular and the obstetric manifestations of the syndrome but the pathogenic mechanisms behind these manifestations are not the same. For example, thrombotic events do not appear to play a major role in APS miscarriages and a direct reactivity of β2GPI-dependent aPLs on decidual and trophoblast cells was reported. A local expression of β2GPI on these tissues was reported both in physiological conditions and in APS women, thus explaining the local tropism of the autoantibodies.

The two hit hypothesis was suggested to explain why the vascular manifestations of APS may occur only occasionally in spite of the persistent presence of aPLs. This is not apparently the case for the obstetric variant of the syndrome, making the difference even more striking. A different pathogenesis may also provide the rationale for the well-known fact that the vascular and the obstetric manifestations may occur independently although in a minority of cases.

Human monoclonal anti-endothelial cell IgG-derived from a systemic lupus erythematosus patient binds and activates human endothelium in vitro

Our objectives were to obtain monoclonal anti-endothelial cell antibodies (AECA) from systemic lupus erythematosus (SLE) patients, to characterize their antigen specificity, and their capability to induce a pro-inflammatory and pro-adhesive endothelial phenotype, and to investigate the mechanism of endothelial cell (EC) activation in vitro. Monoclonal IgG AECA were generated by hybridoma formation with human SLE B cells. Antigen specificity was characterized by immunoblotting with enriched cell membrane fractions, by cytofluorimetry and by cell solid-phase ELISA. Endothelial activation was evaluated by measuring increases in U937 cell adhesiveness, adhesion molecule (E-selectin and ICAM-1) expression and IL-6 production. In addition, mechanisms of endothelial activation were investigated by assessment of NF-kappaB by measuring the loss of its inhibitor I-kappaB. mAb E-3 bound live EC and recognized a 42 kDa EC membrane protein, it enhanced U937 adhesiveness, E-selectin and ICAM-1 expression and IL-6 production, and caused the loss of I-kappaB. We conclude this is the first in vitro demonstration that a human monoclonal AECA from a SLE patient reacts with a constitutive endothelial membrane antigen and induces a pro-inflammatory endothelial phenotype through NF-kappaB activation.

Dipeptidyl peptidase-4 inhibitors and heart failure: Analysis of spontaneous reports submitted to the FDA Adverse Event Reporting System

BACKGROUND AND AIMS

We tested the possible association between dipeptidyl peptidase-4 inhibitors (DPP-4-I) use and heart failure (HF) occurrence by assessing the publicly available US-FDA Adverse Event Reporting System (FAERS).

METHODS

FAERS data reporting HF and DPP-4-Is use in the period from the fourth quarter of 2006 through 2013 were extracted, using the Standardized MedDRA Query "Cardiac failure". Disproportionality (case/non-case method) was implemented by calculating Reporting Odds Ratios (RORs) with 95% Confidence Interval (CI): (1) exploratory analysis on the entire FAERS (using rosiglitazone as positive control); (2) consolidated analyses by therapeutic area (within antidiabetics), correcting for event- and drug-related competition bias and adjusting for co-reported drugs as confounders.

RESULTS

HF during DPP4-I use was recorded in 390 reports (4.4% of total reports). In exploratory analysis, statistically significant ROR emerged for DPP-4-I as a class (ROR = 1.17; 95% CI = 1.05-1.29), saxagliptin (1.68; 1.29-2.17), vildagliptin (2.39; 1.38-4.14), and rosiglitazone (13.98; 13.30-14.70). In consolidated analyses, the ROR for saxagliptin (2.60; 1.92-3.50) and vildagliptin (4.07; 2.28-7.27) increased, and became also significant for sitagliptin (1.61; 1.40-1.86). Concomitant drugs were reported in more than 50% of cases; the adjusted RORs of saxagliptin (2.30; 1.70-3.10), vildagliptin (3.15; 1.76-5.63), and sitagliptin (1.48; 1.28-1.71) were nonetheless significant.

CONCLUSION

FAERS data are consistent with clinical studies on a possible association between saxagliptin and HF. The disproportionate reporting of HF with sitagliptin, conflicting with a recent phase IV trial, suggests that cardiovascular safety requires close post-marketing vigilance by clinicians of individual DPP-4-I in the community until the issue of class effect is solved.

Protection from concanavalin A (Con A)-induced T cell-dependent hepatic lesions and modulation of cytokine release in mice by sodium fusidate

The immunomodulatory effects of the antibiotic sodium fusidate (SF) were tested in a model of T cell-dependent hepatic injury that can be induced in normal mice by a single i.v. injection of Con A. Signs of hepatitis with elevated transaminase activities in plasma, severe infiltration of the liver by neutrophil granulocytes, lymphocytes and monocytes, and necrotic areas were observed in control mice treated intraperitoneally with PBS 24 h and 1 h before Con A challenge. T cell- and macrophage-derived cytokines (IL-2, interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha, IL-1beta, IL-6) were released with different kinetics in the circulation of these mice. SF, 20, 40 or 80 mg/kg, administered 24 h and 1 h before Con A challenge, protected the mice against the hepatitic effects of Con A. The protective effects of SF were dose-dependent and accompanied by profound modifications of blood levels of cytokines induced by Con A, so that, relative to control mice, SF (80 mg/kg)-treated animals showed markedly diminished plasma levels of IL-2, IFN-gamma and TNF-alpha, along with augmented levels of IL-6. These results suggest that SF might be useful in the treatment of immunoinflammatory liver diseases in humans.

Anti-endothelial cell antibodies in patients with coronary atherosclerosis

Anti-endothelial cell antibodies (AECA) have been shown to possess endothelial cell activation properties and to harbor pathogenic potential in experimental animal models of autoimmune systemic disorders. Atherosclerosis is a form of an inflammatory condition in which the immune system has been shown to be involved. The aim of the present study was to assess the presence of AECA in patients with coronary atherosclerosis. A total of 134 patients admitted for chest pain of suspected anginal origin were evaluated for coronary artery atherosclerosis by angiography. Sera were drawn prior to the procedure for the determination of AECA employing cyto-ELISA. AECA positive sera were further evaluated for its ability to promote in vitro E-selectin expression by HUVEC using a cell-based ELISA. Patients with no coronary artery involvement had levels of AECA that did not differ from those obtained for patients with confirmed coronary atherosclerosis (one, two or three vessel disease). Furthermore, AECA positive sera from patients, with or without coronary atherosclerosis displayed similar capacity of inducing E-selectin expression by endothelial cells. AECA may not stand as an optimal mean of discriminating atherosclerotic from non-atherosclerotic patients. The ability of AECA to activate endothelial cells is also not unique to patients with atherosclerosis and is evident also in age-matched control subjects.