Autoantibodies testing in autoimmunity: Diagnostic, prognostic and classification value

Diagnosis of autoimmune diseases is in most cases challenging for clinicians as there is not a single specific laboratory or histological marker to diagnose or exclude the presence of the conditions. This review focused on the current knowledge of the role of autoantibodies' testing in various diseases, such as systemic lupus erythematosus, rheumatoid arthritis, antiphospholipid syndrome, undifferentiated connective tissues disease, primary biliary cirrhosis and primary sclerosing cholangitis. Similarly, the prognostic and diagnostic values of autoantibodies testing in patients with interstitial lung disease have been reviewed. In-depth research on the molecular action of these autoantibodies on immune regulation and diseases pathogenesis has been explored beyond their correlation with disease phenotypes, highlighting the impact of autoantibodies targeting on disease outcomes and etiopathogenesis.

POS0187 DRUG REPURPOSING FOR TREATING LUPUS NEPHRITIS BASED ON TRANSCRIPTOME PROFILING AND AUTOIMMUNITY-RELATED SEROLOGICAL MARKERS

Background

Lupus nephritis (LN) is one of the most severe organ manifestations of systemic lupus erythematosus (SLE) and constitutes an important cause of morbidity and death among patients with SLE [1]. The associated renal injury, and ultimately damage, is the result of an immune-mediated process which involves leukocytes, immune complexes, complement and cytokines [2].

Objectives

Lupus nephritis (LN) is one of the most severe organ manifestations of systemic lupus erythematosus (SLE) and constitutes an important cause of morbidity and death among patients with SLE [1]. The associated renal injury, and ultimately damage, is the result of an immune-mediated process which involves leukocytes, immune complexes, complement and cytokines [2].

Methods

We analysed differentially expressed genes (DEGs), pathways and their druggability via the Drug Gene Interaction database (DGIdb) [3] in active LN (n=41) versus healthy controls (HC; n=497), and eQTLs in active or past LN (n=87), based on validated (identified in two independent SLE populations) DEGs in SLE (n=350) vs HC (n=497), in whole blood collected within the frame of the European PRECISESADS consortium [4]. Genome-wide RNA-sequencing and genotyping was previously performed by Illumina assays, and serum levels of 17 cytokines and 18 autoantibodies were analysed using a Luminex assay, ELISA, IDS-iSYS and SPAPLUS analyser [4].

Results

A total of 6 869 significant and validated DEGs were identified in active LN patients compared with HC. Of these, 1010 validated DEGs were tagged to 34 KEGG pathways including 24 DEGs with a |fold change (FC)| > 1.5, genes of 18 cis-eQTLs and 3 trans-eQTLs, and 1 gene from cytokines that differed significantly between active LN and HC. Moreover, 2446 validated DEGs were tagged to 216 Reactome pathways included 85 DEGs with a |FC| > 1.5, genes of 21 cis-eQTLs and 5 trans-eQTLs, and 1 gene from cytokines that differed significantly between active LN and HC. These genes could be targeted by 203 different drugs, with the proteasome inhibitor bortezomib interfering with cathepsin B (CTSB) regulation and cyclophosphamide interfering with the regulation of tumour necrosis factor receptor superfamily member 1A (TNFRSF1A) being of particular interest.

Conclusion

Integrated multilevel omics analysis in LN revealed a set of enriched pathways of potential interest for future drug investigation. A prospect for proteasome inhibition was implicated.

References

[1]Croca SC, Rodrigues T, Isenberg DA. Assessment of a lupus nephritis cohort over a 30-year period. Rheumatology (Oxford). 2011 Aug; 50(8):1424-1430.

[2]Anders HJ, Saxena R, Zhao MH, Parodis I, Salmon JE, Mohan C. Lupus nephritis. Nat Rev Dis Primers. 2020 Jan 23; 6(1):7.

[3]Wagner AH, Coffman AC, Ainscough BJ, Spies NC, Skidmore ZL, Campbell KM, et al. DGIdb 2.0: mining clinically relevant drug-gene interactions. Nucleic Acids Res. 2016 Jan 4; 44(D1):D1036-1044.

[4]Barturen G, Babaei S, Català-Moll F, Martínez-Bueno M, Makowska Z, Martorell-Marugán J, et al. Integrative Analysis Reveals a Molecular Stratification of Systemic Autoimmune Diseases. Arthritis Rheumatol. 2021 Jun; 73(6):1073-1085.

[5]Kanehisa M, Furumichi M, Tanabe M, Sato Y, Morishima K. KEGG: new perspectives on genomes, pathways, diseases and drugs. Nucleic Acids Res. 2017 Jan 4; 45(D1):D353-d361.

[6]Jassal B, Matthews L, Viteri G, Gong C, Lorente P, Fabregat A, et al. The reactome pathway knowledgebase. Nucleic Acids Res. 2020 Jan 8; 48(D1):D498-d503.

Acknowledgements

The PRECISESADS Clinical Consortium

Disclosure of Interests

None declared

POS0188 TRANSCRIPTOME PROFILING AND AUTOIMMUNITY-RELATED SEROLOGICAL MARKERS IDENTIFY TP53 and C3aR AS DRUG TARGETS IN NEUROPSYCHIATRIC SYSTEMIC LUPUS ERYTHEMATOSUS

Background

Involvement of the nervous system is a common but poorly understood manifestation of systemic lupus erythematosus (SLE), termed neuropsychiatric SLE (NPSLE). Although studies have reported varying prevalence estimates [1], NPSLE affects at least 20% of patients with SLE within the first years of the disease course [2]. The management of neuropsychiatric SLE (NPSLE) is poorly optimised and specific treatment is lacking.

Objectives

The aim of this study was to investigate expression quantitative trait loci (eQTLs), the transcriptome, and autoimmunity-related cytokines and autoantibodies in patients with central nervous system (CNS) lupus to gain insights into underlying genetics and biologic mechanisms towards identification of novel drug targets.

Methods

We analysed differentially expressed genes (DEGs), pathways and their druggability via the Drug Gene Interaction database (DGIdb) [3] in active CNS lupus (n=26) versus healthy controls (HC; n=497), and eQTLs in active or past CNS lupus (n=53), based on validated (identified in two independent SLE populations) DEGs in SLE (n=350) versus HC (n=497), in whole blood collected within the frame of the European PRECISESADS consortium [4]. CNS lupus was defined according to SLE Disease Activity Index 2000 (SLEDAI-2K) [5] CNS items or by CNS manifestations such as chorea, acute confusional state, transverse myelitis, aseptic meningitis, and optic neuritis in the absence of predisposing conditions unrelated to SLE. Genome-wide RNA-sequencing and genotyping was previously performed by Illumina assays, and serum levels of 17 cytokines were analysed using a Luminex assay and ELISA [4].

Results

Among 5631 significant and validated DEGs in active CNS patients compared with HC, 1922 unique DEGs were tagged to 21 and 176 significant KEGG [6] and Reactome [7] pathways, respectively. Pathways included “Interferon signalling”, “TNF signalling” and “Toll-like Receptor Cascades”. The pathways included 29 of 59 DEGs with a |fold change (FC)| > 1.5, 6 genes from 14 significant cis-eQTLs and 10 genes from 22 trans-eQTLs, and 2 genes from 8 cytokines that differed significantly between active CNS lupus and HC. These genes could be targeted by 496 different drugs, with the Bruton tyrosine kinase (BTK) inhibitor ibrutinib and the anti-CD20 B cell depleting monoclonal rituximab with ability to interfere with tumour protein P53 (TP53) activity, and a complement C3a Receptor (C3aR) antagonist being of particular interest.

Conclusion

Integrated multilevel omics analysis revealed a set of enriched pathways of potential interest for future drug investigation in CNS lupus, including BTK and C3aR inhibition, and B cell depletion.

References

[1]Unterman A, Nolte JE, Boaz M, Abady M, Shoenfeld Y, Zandman-Goddard G. Neuropsychiatric syndromes in systemic lupus erythematosus: a meta-analysis. Semin Arthritis Rheum. 2011 Aug; 41(1):1-11

[2]Hanly JG, Urowitz MB, Su L, Bae SC, Gordon C, Wallace DJ, et al. Prospective analysis of neuropsychiatric events in an international disease inception cohort of patients with systemic lupus erythematosus. Ann Rheum Dis. 2010 Mar; 69(3):529-535

[3]Wagner AH, Coffman AC, Ainscough BJ, Spies NC, Skidmore ZL, Campbell KM, et al. DGIdb 2.0: mining clinically relevant drug-gene interactions. Nucleic Acids Res. 2016 Jan 4; 44(D1):D1036-1044

[4]Barturen G, Babaei S, Català-Moll F, Martínez-Bueno M, Makowska Z, Martorell-Marugán J, et al. Integrative Analysis Reveals a Molecular Stratification of Systemic Autoimmune Diseases. Arthritis Rheumatol. 2021 Jun; 73(6):1073-1085

[5]Gladman DD, Ibanez D, Urowitz MB. Systemic lupus erythematosus disease activity index 2000. J Rheumatol. 2002 Feb; 29(2):288-291

[6]Kanehisa M, Furumichi M, Tanabe M, Sato Y, Morishima K. KEGG: new perspectives on genomes, pathways, diseases and drugs. Nucleic Acids Res. 2017 Jan 4; 45(D1):D353-d361

[7]Jassal B, Matthews L, Viteri G, Gong C, Lorente P, Fabregat A, et al. The reactome pathway knowledgebase. Nucleic Acids Res. 2020 Jan 8; 48(D1):D498-d503

Acknowledgements

The PRECISESADS clinical consortium

Disclosure of Interests

None declared

Long-term effects of somatostatin analogues in rat GH-secreting pituitary tumor cell lines

PURPOSE

First-generation somatostatin analogs, octreotide (OCT) and lanreotide, are the cornerstone for the medical treatment of growth hormone (GH)-secreting pituitary tumors. A new multireceptor analog, such as pasireotide (PAS), showed better activity than OCT in long-term treatment of patients with acromegaly, but modulation of intracellular key processes is still unclear in vitro. In this study, we evaluated the antitumor activity of OCT and PAS in two GH-secreting pituitary tumor cell lines, GH3 and GH4C1, after a long-term incubation.

METHODS

The effects of PAS and OCT on the cell viability, cell cycle, apoptosis, GH secretion, and tumor-induced angiogenesis have been evaluated through a colorimetric method (MTS Assay), DNA flow cytometry with propidium iodide, and Annexin V-FITC/propidium iodide staining, ELISA assay and zebrafish platform, respectively.

RESULTS

PAS showed a more potent antitumor activity compared to OCT in GH3 cell line exerted through inhibition of cell viability, perturbation of cell cycle progression, and induction of apoptosis after 6 days of incubation. A concomitant decrease in GH secretion has been observed after 2 days of incubation only with PAS. No effect on tumor-induced angiogenesis has been reported after treatment with OCT or PAS in zebrafish/tumor xenograft model.

CONCLUSION

Long-term incubation with PAS showed a more potent antitumor activity than that reported after OCT in GH3 cells, mainly modulated by a cell cycle perturbation and a relevant induction in apoptosis.

FRI0154 SHOULD BE OLDER PATIENTS TESTED FOR ANTIPHOSPHOLIPID ANTIBODIES? 695 CASES FROM THE RETROSPECTIVE SERIES HIBISCUS

Background:

Although guidelines do not recommend antiphospholipid antibodies testing after 60 yo, recent data reported late onset antiphospholipid syndrome (APS).

Objectives:

To comparatively analyse the clinical, laboratory features and outcomes in 695 cases with primary APS between patients older and younger than 70 yo.

Methods:

we have performed an international study within the framework of the International Registry of primary APS patients treated with Hydroxychloroquine, HIBISCUS (an ongoing retrospective and prospective register launched in 2016). 28 centres from 17 countries participate. Data about late onset APS were analysed in 695 patients and were obtained from a standardized form registered in the database containing 66 items with respect to demographics, clinical and biological features.

Results:

Arterial events and especially stroke represented the main initial and recurrent clinical manifestation in 40 primary APS patients older than 70 yo. There were not statistically significant differences with respect to cardiovascular risk factors between the two groups of patients. A significant male predominance, a familial APS history, a higher prevalence of triple positivity, lower complement levels, and anticardiolipin antibodies (aCL) IgA isotype were found in older patients. Low anticoagulation regimens were safe and efficient, with a low relapse rate in older patients.

Conclusion:

we suggest that the detection of aPL antibodies should be included into the initial screening panel tests in elderly with thrombotic events, especially arterial, in particular those with recurrent stroke and familial APS.

Our study further suggests that lower intensity anticoagulation regimens could be a therapeutic option in older APS patients, as no differences in outcomes and relapse rate were found between patients with high and low intensity anticoagulation regimens.

References:

[1]Grimaud F et al. Rheumatology. 2019;58:1006-10.

[2]Goldman-Mazur S et al. Thromb Res. 2019;176:67-73.

[3]Hirmerova J et al. 2017;36:167-73.

Disclosure of Interests:

Cristina Belizna: None declared, Omar Latino: None declared, Ljudmila Stojanovich: None declared, Patrick Saulnier: None declared, Katrien Devreese: None declared, Sebastien Udry: None declared, Natasa Stanisavljevic: None declared, Aleksandra Djokovic Speakers bureau: KRKA, Astra Zeneca, Actavis, Jaume Alijotas-Reig: None declared, Enrique Esteve-Valverde: None declared, Raquel Ferrer-Oliveras: None declared, Angela Tincani: None declared, Laura Andreoli: None declared, Francesca Regola: None declared, Maarten Limper: None declared, Alexander Makatsariya: None declared, Jamilya Khizroeva: None declared, Viktoria Bitsadze: None declared, Cecilia Chighizola: None declared, Francesca Pregnolato: None declared, Maria Orietta Borghi: None declared, Pier Luigi Meroni: None declared

Antitumor activity of interferon-β1a in hormone refractory prostate cancer with neuroendocrine differentiation

PURPOSE

Type I interferons (IFN-α and IFN-β) are a class of cytokines that exert several biological activities, such as modulation of cell proliferation and differentiation and of the immune system. Although these cytokines interact with a common receptor complex, IFN-β showed a more potent antitumor activity than IFN-α in several tumor models. New recombinant human IFN-β products, such as IFN-β1a and IFN-β1b, have been produced in order to improve the stability and bioavailability of natural IFN-β. In this report, we analyzed the effects of recombinant IFN-β1a on the cell proliferation of two human androgen-resistant prostate cancer cell lines with neuroendocrine differentiation (DU-145, PC-3) and related mechanisms of action.

METHODS

The effects of IFN-β1a on the cell growth proliferation, cell cycle, and apoptosis have been evaluated in DU-145 and PC-3 cells through MTT assay, DNA flow cytometry with propidium iodide, and Annexin V-FITC/propidium iodide staining, respectively. Moreover, the expression of neuron-specific enolase (NSE), cleaved caspase-3, caspase-8, and PARP was evaluated through Western blotting.

RESULTS

IFN-β1a showed a significant anti-proliferative activity in both androgen-resistant cell lines. This effect was related to cell cycle perturbation and induction in apoptosis, as shown by flow cytometric analysis, the activation of caspase-3 and caspase-8 and PARP cleavage during incubation with IFN-β1a. Moreover, this cytokine reduced the expression of NSE in both cell lines.

CONCLUSIONS

Recombinant IFN-β1a (Rebif) showed a potent in vitro anti-proliferative activity in androgen-resistant prostate cancer cells, and it could represent a promising tool for the treatment of this tumor.

Immune function in children born to mothers with autoimmune diseases and exposed in utero to immunosuppressants

The administration of immunosuppressive drugs during pregnancy is often necessary in women with autoimmune diseases. Teratogenicity of immunosuppressives during pregnancy has been evaluated, only few data exist about the effects on immune systems. We therefore performed a pilot study on the influence of foetal exposure to immunosuppressives on immune function of babies born to mothers with autoimmune disorders. We investigated serological and cellular parameters as indicators of immune system status. We included in the study 14 babies (mean age 11 months, range 1—24) born to mothers with autoimmune diseases and exposed in utero to different immunosuppressants and, as controls, 14 babies whose mothers had autoimmune manifestations but did not receive immunosuppressive therapy. We evaluated: (i) complete blood count, (ii) immunoglobulin levels and IgG subclasses, (iii) antibody response to hepatitis B vaccine, (iv) leukocyte subpopulations and (v) interleukin-2 and interferon γ in vitro production by resting or activated peripheral blood mononuclear cells. We did not find statistically significant differences between exposed and not exposed babies or among treatments for the tested parameters. Immunosuppressive regimens currently in use for controlling maternal autoimmune disorders do not significantly affect the immune status of the offspring. Lupus (2007) 16, 651—656.

Autoantibody profiling in APS

The international consensus for the classification of antiphospholipid syndrome (APS) requires clinical and laboratory criteria to be considered at an equal level for diagnosing APS. Thus, detection of antiphospholipid antibodies (aPL) being a hallmark of APS has been the object of intensive investigation over the past 40 years. However, appropriate detection of aPL still remains a laboratory challenge due to their heterogeneity comprising autoantibodies reactive to different phospholipid-binding plasma proteins, such as beta-2 glycoprotein I (β2GPI) and prothrombin. The relevance of aPL interacting with phospholipids other than cardiolipin (CL, diphosphatidylglycerol), such as phosphatidylserine (PS), remains elusive with regard to the diagnosis of APS. Recently, the concept of aPL profiling has been introduced to assess the risk of thrombotic complications in patients with APS. New assay techniques, apart from enzyme-linked immunosorbent assays (ELISAs) recommended by the international consensus for the classification of APS, have been proposed for multiplexing of aPL testing. Line immunoassays (LIAs) employing a novel hydrophobic solid phase for the simultaneous detection of different aPL seem to be an intriguing alternative. We evaluated a novel multiplex LIA employing a hydrophobic membrane coated with different phospholipid (PL)-binding proteins or PLs. The performance characteristics of this new multiplexing assay technique demonstrated its usefulness for aPL profiling.

Toll-like receptor 4 and β2 glycoprotein I interaction on endothelial cells

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by thrombotic events and/or pregnancy morbidity in the persistent presence of antiphospholipid antibodies (aPL). aPL targeting β2 glycoprotein I (anti-β2GPI Abs) provide the main pathogenic autoantibody subset. In monocytes, platelets and endothelial cells (ECs), the interaction of circulating aPL with membrane-bound β2GPI results in cell activation, and EC perturbation provides an important player in clotting. Several receptors have been suggested to mediate β2GPI/EC binding. AnnexinA2 provides a high-affinity binding site for β2GPI but, since it does not span the cell membrane, an adaptor protein is required to trigger signal. Consistent evidence supports the role of Toll-like receptor (TLR) 4 as co-receptor for β2GPI on ECs. β2GPI was recently reported to behave as lipopolysaccharide (LPS) scavenger. In monocytes, TLR4 activation was shown to be apparent, due to LPS/β2GPI complexes. Conversely, our findings in ECs demonstrate that β2GPI interacts directly with TLR4, and that such interaction may contribute to β2GPI-dependent aPL-mediated EC activation. LPS enhanced anti-β2GPI Ab binding to EC only at cell-activating concentrations, able to up-regulate TLR4. This in vitro model may explain why LPS behaves as a second hit increasing the expression of β2GPI in vascular tissues and triggering aPL-mediated thrombosis in vivo.

Immune parameters identify Italian centenarians with a longer five-year survival independent of their health and functional status

Centenarians are rare and exceptional individuals characterized by a peculiar phenotype. They are the best example of healthy aging in humans as most of them have escaped or substantially delayed the onset of major age-related diseases. Within this scenario, the purpose of the present work was to understand if immune status is associated with survival and health status in centenarians. To this aim, 116 centenarians were concomitantly characterized for their immunological, health and functional status, and followed-up for five-year survival. On the basis of previous knowledge we focused on a core of fundamental and basic immune parameters (number of leukocytes, monocytes, total lymphocytes, CD3(+) T lymphocytes, CD4(+) helper T lymphocytes, CD8(+) cytotoxic T lymphocytes, CD19(+) B lymphocytes and plasma levels of IgM), and the most important findings can be summarized as follows: i. a hierarchical cluster analysis was able to define Cluster1 (88 centenarians) and Cluster2 (28 centenarians) characterized by low and high values of all these immune parameters, respectively; ii. centenarians of Cluster2 showed a statistically longer five-year survival and more favorable values of other important immune (naïve, activated/memory and effector/memory T cells) and metabolic (glycemia, insulin and HOMA-IR) parameters, in accord with previous observations that centenarians have a peculiar immune profile, a preserved insulin pathway and a lower incidence of type 2 diabetes; and iii. unexpectedly, parameters related to frailty, as well as functional and cognitive status, did not show any significant correlation with the immune clustering, despite being capable per se of predicting survival. In conclusion, high values of basic immunological parameters and important T cell subsets correlate with five-year survival in centenarians, independent of other phenotypic characteristics. This unexpected biological scenario is compatible with the general hypothesis that in centenarians a progressive disconnection and loss of biological coherence among the different functions of the body occur, where survival/mortality result from the failure of any of these domains which apparently follow an independent age-related trajectory.

Everolimus is an active agent in medullary thyroid cancer: a clinical and in vitro study

Everolimus, an mTOR inhibitor, which has been demonstrated to induce anti-tumour effects in different types of neuroendocrine tumours, has never been evaluated in patients with medullary thyroid cancer (MTC). The aim of this study was to evaluate the in vitro and in vivo effects of everolimus in combination with octreotide in MTC. Two patients with progressive metastatic MTC and high calcitonin levels were treated with everolimus 5–10 mg/day. Both patients were under treatment with octreotide LAR at the study entry. An in vitro study was also performed to assess everolimus effects on MTC cell lines (TT and MZ-CRC-1 cells). A tumour response was observed in both patients. Serum calcitonin decreased by 86% in patient 1 and by 42% in patient 2. In TT and MZ-CRC-1 cells, everolimus induced a significant dose-dependent inhibition in cell proliferation. This effect seems to be related to a cell cycle arrest in G₀/G₁ phase in both cell lines and to the induction of cellular senescence in TT cells. Everolimus in combination with octreotide may be active as anti-tumour therapy in patients with progressive metastatic MTC, suggesting to further evaluate this agent in MTC patients in a large prospective study.

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.

Anti-phospholipid antibody mediated fetal loss: still an open question from a pathogenic point of view

Antiphospholipid antibodies (aPL) are associated with recurrent miscarriages and pregnancy complications, however their pathogenic mechanisms are still matter of research. Thrombotic events at the placental level cannot explain all of the clinical manifestations. It has been suggested that aPL may be responsible for a local acute inflammatory response mediated by complement activation and neutrophil infiltration eventually leading to fetal loss. However histological and immunohistological studies on human placental samples do support such a mechanism only in part and with no any clear relationship with the pregnancy outcome. A direct effect of aPL on both maternal and fetal placental tissues has been reported through the reactivity of the antibodies with beta2 glycoprotein I (beta2GPI) expressed on the cell membranes. These events do not require an inflammatory response and can be in part related to the inhibition of growth factors favouring a physiological placentation. Understanding the different pathogenic mechanisms of aPL-associated miscarriages may help in improving our therapeutic approach particularly in recurrent cases not responsive to the usual treatment.

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.

European Forum on Antiphospholipid Antibodies: research in progress

The research projects of the European Forum on Antiphospholipid Antibodies are representative of how dynamic is this area of investigation. The present review is focused on the most recent projects of the Forum on the aetiopathogenic aspects of the antiphospholipid syndrome (APS). Studies on the genetic background of the APS are ongoing in order to better define the proximity between APS and full-blown systemic lupus erythematosus. However, the analysis of the polymorphisms of genes coding for inflammatory mediators may offer new information on the role of inflammatory processes in triggering thrombotic events as well as the whole susceptibility for developing the vascular manifestations. A systematic and wide detection of serological markers of infectious processes will give new insight on the role of infectious agents in favouring autoimmunity in APS. Owing to the well-known role of vitamin D3 defect in autoimmune disease, the detection of vitamin plasma levels in APS patients will offer the rationale for a possible therapeutic supplementation. Additional projects are aimed to better characterize the diagnostic/prognostic value of antiphospholipid antibodies (aPL) by defining their epitope specificity and binding avidity. Pregnancy complications represent the obstetric side of APS. Research projects are focussed on the role of complement activation in placenta damage and on the potential ability of aPL to affect the fertility. Finally, a study has been planned in order to draw definitive conclusions on the associations between aPL and atherosclerosis.

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.

Pro-inflammatory genotype as a risk factor for aPL-associated thrombosis: Report of a family with multiple anti-phospholipid positive members

OBJECTIVE

Inflammation might represent a second hit for anti-phospholipid antibody (aPL)-mediated thrombosis. Inflammatory responses have been linked to gene polymorphisms of several cytokines and Toll Like Receptors (TLRs). We examined IL1 beta, TNFalpha, TGFbeta, IL6, IFN gamma, IL10, tlr4 gene polymorphisms in a family with several members positive for IgG anti-beta2 glycoprotein I (beta 2GPI) antibodies but with recurrent thrombosis in one member only.

METHODS

Lupus anticoagulant, anti-cardiolipin, anti-beta 2GPI IgG/IgM antibodies, IL1beta, TNFalpha, TGF beta1, IL6, IL10, IFN gamma, tlr4 gene polymorphisms (by allele-specific polymerase chain reaction) in addition to standard thrombophilic risk factors and cytokine serum levels (IL-1 beta, TNFalpha, IL-10) were evaluated.

RESULTS

Recurrent thrombotic events was reported only in the proband, but not in three healthy siblings persistently positive for IgG anti-beta2GPI antibodies, respectively. The wild type tlr4 gene and cytokine polymorphisms associated with a high pro-inflammatory response (IL-1 beta promoter-511C/T; TNFalpha G/A; TGFbeta+10T/C, +25C/G; IL-6 -174C/G) were found only in the proband. Serum cytokine levels were normal.

CONCLUSION

This case report confirms that protective tlr4 gene polymorphisms are more frequent in asymptomatic aPL carriers. In line with the role of inflammatory mediators as second hits for aPL-associated thrombosis, the polymorphisms of cytokines linked to higher inflammatory response were found in the proband only.

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.

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.

Prevalence of autoantibodies against structure specific recognition protein 1 in systemic lupus erythematosus

Antibodies (Abs) against the structure specific recognition protein 1 (SSRP1) were reported in a small systemic lupus erythematosus (SLE) series but not in other systemic autoimmune diseases. The aim of the study was to confirm the selective presence of anti-SSRP1 Abs in a larger SLE series and to evaluate their relationship with disease activity and other immune markers. Anti-SSRP1 Abs were investigated by a 'home made' ELISA in: 120 SLE, 65 rheumatoid arthritis (RA), 51 systemic sclerosis (SSc), 23 Churg-Strauss syndrome (CSS) and 40 idiopathic autoimmune urticaria (IAU) patients and 190 healthy controls. Sera from MRL lpr/lpr and Balb-c mice were also tested. Anti-SSRP1 Abs were detected in 43 SLE (35.8%), nine SSc (17.6%), eight RA (12.3%), six IAU (15%), three CSS (13%) patients and five healthy controls (2.6%). Antibody prevalence and titers were significantly higher in SLE patients than in sera from both normal and disease controls. Anti-SSRP1 Ab activity was also detected in sera from MRL lpr/lpr but not Balb-c mice. The antibodies did not correlate with the disease activity evaluated as the ECLAM index score and were more prevalent in patients without renal involvement. No correlation was found with other serum autoantibodies. Our results confirm that anti-SSRP1 Abs are associated with but not specific for the lupus disease.

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.

Endothelium activation in the anti-phospholipid syndrome

Anti-phospholipid syndrome is an autoimmune systemic disease characterized by the persistent presence of anti-phospholipid antibodies and by the occurrence of thrombosis, fetal loss and thrombocytopenia. Anti-phospholipid antibodies are widely accepted as pathogenic antibodies mainly directed against the phospholipid-binding protein beta 2 glycoprotein I. Beta 2 glycoprotein I can be expressed on the endothelial cell membranes of different anatomical localizations and recognized by the autoantibodies. The antibody binding might induce an endothelial activation both in vitro and in vivo experimental models, that was suggested to represent one of the pathogenic mechanisms leading to the prothrombotic state of the syndrome. Beta 2 glycoprotein I endothelial adhesion was found to take place through the interaction of the cationic phospholipid binding site of the molecule with anionic endothelial structures and through annexin II, the endothelial cell receptor for tissue plasminogen activator. Anti-beta 2 glycoprotein I antibodies can directly activate the cells via NF-kB translocation and the signaling cascade triggered by toll like receptors. It has been suggested that beta 2 glycoprotein I might be associated with toll like receptors because of its molecular mimicry with bacterial structures, the natural ligands of toll like receptors. The binding of the antibodies is thought to cross-link beta 2 glycoprotein I and the toll like receptors, eventually switching their signaling pathway.

Prevalence and clinical significance of anti-cyclic citrullinated peptide antibodies in juvenile idiopathic arthritis

BACKGROUND

Antibodies against cyclic citrullinated peptide (anti-CCP) are considered to be specific for rheumatoid arthritis (RA).

OBJECTIVE

To assess the clinical significance of anti-CCP in a cohort of patients with juvenile idiopathic arthritis (JIA).

METHODS

Anti-CCP were tested by an enzyme linked immunosorbent assay (ELISA) in serum samples from 109 patients with JIA (30 boys, 79 girls), with a mean age of 8.7 years (range 0.6-20.3) and mean disease duration of 3.6 years (range 3 months to 15.6 years). As control groups, anti-CCP were also tested in sera of 30 healthy children, 25 patients with juvenile onset systemic lupus erythematosus (SLE), and 50 adult patients (30 with RA, 20 with SLE).

RESULTS

Positive anti-CCP values were found in sera of two patients with JIA (2%), one with polyarthritis, and one with oligoarthritis. Statistical analysis showed that anti-CCP were not associated with the presence of antinuclear antibodies, raised erythrocyte sedimentation rate, or erosions. In the control groups, none of the patients with juvenile onset SLE and only one of 20 adults with SLE were positive for anti-CCP, but 19/30 (63%) adults with RA showed anti-CCP positivity.

CONCLUSIONS

Anti-CCP can be detected in children with JIA, but are less frequently present than in adults with RA.

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.

Interaction between chronically HIV-infected promonocytic cells and human umbilical vein endothelial cells: role of proinflammatory cytokines and chemokines in viral expression modulation

HIV type 1 expression was significantly up-regulated in chronically infected promonocytic cell line (U1) co-cultured with human umbilical vein endothelial cells (HUVEC). Virus replication, evaluated as supernatant p24 release, was higher when U1 were co-cultured with IL-1beta-activated HUVEC than with unstimulated HUVEC. When non-adherent U1 were removed from co-cultures, the remaining U1 cells adherent to the endothelial monolayer still showed enhanced HIV replication in comparison with an equal number of U1 cultured alone. While addition of adhesion molecule blocking antibodies (anti-intercellular adhesion molecule-1 (ICAM-1), -vascular cell adhesion molecule-1 (VCAM-1), -CD18 and -very late antigen-4 (VLA-4)) strongly inhibited adherence of U1 cells to endothelial monolayers, such treatment resulted in only a partial reduction in p24 release. Furthermore, HIV replication in U1 cells was enhanced on culture in HUVEC-conditioned media. Such data suggest that soluble mediators secreted by endothelial monolayers may modulate HIV-1 expression. Indeed, addition of cytokine and chemokine antagonists to both U1/HUVEC co-cultures and to U1 cultured in HUVEC-conditioned media clearly down-regulated p24 release. Anti-IL-6, anti-tumour necrosis factor-alpha (TNF-alpha) and, particularly, anti-MCP-1 MoAbs reduced p24 release, while anti-IL-8 polyclonal antiserum and IL-1 receptor antagonist (IL-1Ra) had no significant effect. Thus, the interaction between HUVEC and infected monocytic cells up-regulates HIV-1 replication predominantly through production of endothelium-derived soluble factors including MCP-1, TNF-alpha and IL-6. This phenomenon may influence the passage of HIV-1 from latency to productive replication and enhance virus spreading during physiological and/or pathological contact of monocytes with endothelium.

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.

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

Antiphospholipid and antiendothelial antibodies

A lot of attention has recently been paid to antiphospholipid and antiendothelial cell antibodies as serological markers for systemic autoimmune diseases. Antiphospholipid antibodies appear to display a prognostic value for recurrent thrombosis and fetal loss both in a subset of systemic lupus erythematosus and in patients with the primary antiphospholipid syndrome. The range of diagnostic tests for the antiphospholipid syndrome is now becoming larger with the inclusion of assays suitable for identifying antibodies against phospholipids other than cardiolipin and especially against phospholipid-binding proteins. Antiendothelial cell antibodies have been suggested as serological markers for immune-mediated vascular damage. In vitro and in vivo experimental models as well as epidemiological studies seem to support this. However, the assays for their detection still lack standardization.

Immunosuppressive activity of 15-deoxyspergualin on normal and autoimmune peripheral blood mononuclear cells

Several experimental conditions were used in this study to evaluate the in vitro effects of 15-deoxyspergualin on the function of T lymphocytes, B lymphocytes and monocytes from healthy subjects and patients suffering from systemic lupus erythematosus. Whilst the secretion of polyclonal immunoglobulin (Ig) M and IgG from the B lymphocytes of the healthy subjects was diminished by 15-deoxyspergualin, neither the proliferative response of normal T and B cells to mitogenic stimulation nor the cytokine secretory capacity of these cells (e.g. interleukin-2, -4, -6 and gamma-interferon) and monocytes (e.g. interleukin-1 beta and -6) were affected by the drug. In contrast, on the mononuclear cells obtained from the lupus patients not only did 15-deoxyspergualin inhibit the spontaneous production of polyclonal and anti-DNA IgG antibodies but also suppressed interleukin-1 beta secretion from the monocytes. Other functional responses of T and B cells and monocytes from lupus patients, including mitogenic activation and cytokine secretion, were not altered by the drug. These data suggest that 15-deoxyspergualin possesses a novel mechanism of pharmacological immunosuppression apparently different from that of other immunosuppressants, such as cyclosporin A, FK506 and corticosteroids, that seems to be primarily displayed at the level of autoreactive B cells and monocytes.

In vitro type-1 and type-2 cytokine production in systemic lupus erythematosus: lack of relationship with clinical disease activity

OBJECTIVE

To investigate the relationship between disease activity and in vitro cytokine, soluble(s)CD23 and polyclonal and anti-DNA antibody production by PBMC from patients with active systemic lupus erythematosus (SLE).

METHODS

Cytokines, sCD23 and immunoglobulins were estimated by ELISA in unstimulated and polyclonal mitogen-stimulated culture supernatants.

RESULTS

PHA-induced IL-2 and IFN-gamma production were decreased, whereas spontaneous and PHA-induced IL-6 and IL-10 production were increased in cultures of SLE lymphocytes. Conversely, spontaneous and PHA-stimulated IL-4 and sCD23 production was comparable between patients and controls. Finally, we found an increase in in vitro spontaneous polyclonal and anti-DNA IgG secretion.

CONCLUSIONS

We demonstrated an expanded type-2 cytokine profile with no correlation with parameters of disease activity.

In vitro production of type 1 and type 2 cytokines by peripheral blood mononuclear cells from high-risk HIV-negative intravenous drug users

OBJECTIVE

To study type 1 and type 2 cytokine patterns in HIV-negative high-risk intravenous drug users (IVDU).

DESIGN

We investigated interleukin (IL)-2, interferon (IFN)-gamma, IL-4, IL-6 and IL-10 production by phytohaemagglutinin (PHA)-stimulated and unstimulated peripheral blood mononuclear cell (PBMC) cultures from HIV-negative high-risk IVDU, HIV-negative controls and HIV-positive subjects.

METHODS

Cytokine production was measured in supernatants using enzyme-linked immunosorbent assay (ELISA) in 10 HIV-negative high-risk IVDU, 25 HIV-negative controls, and 12 HIV-positive IVDU. We also determined spontaneous in vitro immunoglobulin (Ig) G and IgM production.

RESULTS

HIV-negative high-risk IVDU showed increased IFN-gamma and decreased IL-4, IL-10 and IL-2, although the latter was not significant compared with HIV-negative controls. Further, HIV-negative high-risk IVDU had reduced IgG production and impaired IgM-IgG switch.

CONCLUSIONS

The reduced IL-2 and IL-4 production suggest an impaired CD4+ T-cell function in HIV-negative high-risk IVDU. The increased IFN-gamma production along with the decreased type 2 cytokine profile is consistent with the hypothesis that protective immunity against HIV may reside in type 1 responses and cell-mediated immunity.

Relationship between anti-phospholipid and anti-endothelial cell antibodies III: beta 2 glycoprotein I mediates the antibody binding to endothelial membranes and induces the expression of adhesion molecules

OBJECTIVE

To investigate the role of antibodies reacting with beta 2 glycoprotein I (beta 2GPI) in the antiendothelial cell binding activity present in sera from patients with the anti-phospholipid syndrome.

METHODS

Sera positive for anti-phospholipid, anti-endothelial and anti-beta 2 GPI antibodies were studied for their binding activity on endothelial monolayers cultured in the presence or absence of media containing bovine serum as a source of beta 2GPI. Anti-endothelial activity was also evaluated on endothelial cells cultured without serum and supplemented with exogenous human purified beta 2GPI. Affinity purified anti-beta 2 GPI antibodies were investigated under the same experimental conditions. Finally, the effect of the incubation of these affinity purified fractions on the expression of adhesion molecules (ELAM-1) was studied.

RESULTS

The reactivity of the sera decreased on endothelial cells incubated in serum-free medium, while endothelial cell binding was restored in a dose dependent manner after the addition of exogenous purified human beta 2 GPI. Affinity purified anti-beta 2 GPI antibodies obtained from the same sera retained their endothelial cell binding and were able to activate endothelial cells by inducing the ex novo surface expression of adhesion molecules (ELAM-1).

CONCLUSIONS

These findings indicate that the close association between anti-endothelial and anti-phospholipid antibodies is sustained by antibodies which recognize beta 2 GPI adhering to the endothelial cells, and can promote their activation.

TH1 and TH2 cytokine production by peripheral blood mononuclear cells from HIV-infected patients

OBJECTIVE

To study the TH1-->TH2 cytokine switch, thought to occur during the progression of HIV infection.

DESIGN

We investigated interleukin (IL)-2, interferon (IFN)-gamma, IL-4, IL-6 and IL-10 production by phytohaemagglutinin (PHA)-stimulated and unstimulated peripheral blood mononuclear cell (PBMC) cultures from HIV-negative controls and HIV-positive subjects, stratified according to the Centers for Disease Control and Prevention (CDC) criteria. We correlated the above parameters with markers of disease progression.

METHODS

Cytokine production was measured in supernatants using enzyme-linked immunosorbent assay (ELISA) in 40 patients and 17 controls. To evaluate disease progression, we also determined CD4+ cell counts, PHA-induced proliferative response, p24 release and spontaneous immunoglobulin (Ig) G and IgM production.

RESULTS

In agreement with the TH1-->TH2 switch hypothesis, we found that in the course of HIV disease mitogen-stimulated IL-2 production decreased, spontaneous and stimulated IL-6 production and spontaneous IL-10 secretion increased; IL-4 showed an increasing trend, although it was reduced in HIV-positive subjects. Finally, immunoglobulin production increased over time. In contrast, mitogen-stimulated IFN-gamma and IL-10 production did not change among the CDC categories, although the former decreased and the latter increased in comparison with HIV-negative controls.

CONCLUSIONS

Our data partially agree with the TH1-->TH2 switch hypothesis. Since IL-6 and IL-10 are produced by different cell types, whose proportions and functional features vary in the course of the disease, further experiments with purified lymphocyte subsets and monocytes are required. Nevertheless, as already suggested, we believe that a switch from a type 1 to a type 2 response occurs in HIV infection.

Protection from experimental autoimmune thyroiditis in CBA mice with the novel immunosuppressant deoxyspergualin

The effects of the novel immunosuppressant Deoxyspergualin (DSP) on the development of experimental autoimmune thyroiditis (EAT) in CBA mice were studied. For EAT induction, the mice were immunized with 100 micrograms of porcine thyroglobulin (p Tg) emulsified in CFA on day 0 and in IFA, for boosting, on day 14. Twenty-eight days after primary immunization, histological and serological signs of EAT occurred in control mice treated with PBS which showed marked lymphoid infiltration of the thyroid glands along with increased serum titres of anti-pTg antibodies. Development of both these EAT features was significantly suppressed when the mice were treated with 2.5 mg/kg body weight DSP, given daily, five times a week, from day -2 to day +28 after immunization. The effect appeared to be dose-dependent and DSP was ineffective when given under the same experimental conditions at the dose of 0.5 mg/kg body weight. No DSP-toxic effects could be observed during the experiment. These results provide further evidence for the powerful immunosuppressive properties of DSP and suggest that this drug may be used in the treatment of autoimmune thyroid diseases and other T-cell mediated autoimmune disorders in humans.

Beta-endorphin content in HIV-infected HuT78 cell line and in peripheral lymphocytes from HIV-positive subjects

We investigated beta-endorphin (BE) content in an HIV-infected cell line and in peripheral blood mononuclear cells (PBM) from HIV-positive subjects. HIV infection increased BE content in HuT78 cell line compared to uninfected cells. Accordingly, BE content was greater in HIV-positive subjects than in healthy controls, both in fresh PBM and in mitogen-stimulated or unstimulated cultured cells. Further, in PHA-stimulated cultures, BE increase was correlated with disease progression. Opioids are known to decrease immune responsiveness in vivo, and it may be that the increased BE concentrations contribute to HIV-associated immune deficiency. In HIV-positive subjects, but not in healthy controls, intracellular BE concentration was positively correlated with PHA-induced PBM proliferation. The latter data suggest an alternative explanation: that the increased BE content represents a paradoxical response of the host in an attempt to balance virus-induced immunodepression. Thus, BE may be important in fine-tuning of the immune response with its up- and downregulation dependent upon differences in immune status.

Autoantibodies against beta 2-microglobulin-free HLA antigens in AIDS patients

Serum samples from 88 human immunodeficiency virus (HIV)-positive drug addicts have been investigated for the presence of antibodies to both beta 2-microglobulin (beta 2m)-free and beta 2m-associated HLA class I molecules. Using HIV-negative drug addicts as background control, we found that none of the Centers for Disease Control (CDC) stage II, 9.1% of CDC III, 36.4% of CDC IV A, and 45.5% of CDC IV C1 patients had significant levels of autoantibodies competing with the binding of the monoclonal antibody specific for beta 2m-free HLA I (L31 mAb). Using the mAb 01.65, recognizing the beta 2m-associated form of HLA class I molecules, a similar percentage of positive samples was found in the CDC II, CDC III, and CDC IV A patient groups; conversely, the percentage of positive serum samples was lower in the CDC IV C1 group. A lower number of systemic lupus erythematosus serum samples and none of the specimens from healthy adult subjects or patients suffering from recurrent Epstein-Barr virus infections were positive in both assays. Our data demonstrate the existence of an ongoing HLA class I-specific autoimmune response during AIDS disease development, which probably reflects a molecular mimicry between autologous histocompatibility antigens and HIV components. The relationship between the prevalence of autoantibodies against beta 2m-free HLA class I and disease progression suggests a possible pathogenetic role of these antibodies in the induction of the HIV-associated immune deficiency.

Prevention of cyclophosphamide-induced diabetes in the NOD/WEHI mouse with deoxyspergualin

Ten out of 20 (50%) 17-week-old female NOD/WEHI mice developed an acute form of autoimmune diabetes when injected with two large doses of cyclophosphamide (CY), given at 14-day intervals. If these mice were treated under a prophylactic regimen with 2.5 mg/kg body weight per day of the novel immunosuppressant deoxyspergualin (DSP) the onset of diabetes was completely prevented. Moreover, DSP-treated animals showed reduced signs of pancreatic insulitis, had lower percentages of splenic lymphoid cells (SLC) expressing IL-2 receptors and Ly-6C antigens on their surfaces, and these cells released lower amounts of interferon-gamma (IFN) when stimulated in vitro. These data, providing evidence for the capacity of DSP to protect NOD/WEHI mice from experimental autoimmune diabetes and to modulate histo-immunological pathogenic pathways, indicate DSP as a drug of potential interest in the treatment of human insulin-dependent diabetes mellitus.

In vitro and ex vivo effect of tiaprofenic acid on human peripheral blood mononuclear cells

The effect of the non-steroidal anti-inflammatory drug (NSAID) tiaprofenic acid on different human immune parameters was investigated in vitro or following in vivo administration in healthy adult volunteers. Results from the in vitro study demonstrated an increased mitogen-induced blastogenesis and interleukin 2 (IL-2) production together with a reduced polyclonal immunoglobulin (Ig) secretion in the presence of the drug. Results from the ex vivo study showed that treatment with tiaprofenic acid had no significant effects on the immune parameters investigated, i.e. unstimulated and mitogen-induced proliferation and IL-2 production, spontaneous and stimulated Ig synthesis, lymphocyte subpopulations, serum Ig and complement levels.

Enrichment of IgG anti-DNA-producing lymphoblastoid cell lines by antigen-coated immunomagnetic beads

In this paper we describe the establishment of four anti-DNA-producing lymphoblastoid cell lines (LCL) by Epstein-Barr virus (EBV) infection of peripheral blood B-cells from a patient with systemic lupus erythematosus. The LCL showed a heterogeneous cell composition: the frequencies of cells in active proliferation, cells secreting IgG or IgM, and cells effectively producing IgG or IgM anti-DNA were estimated by limiting dilution analysis. The cells producing anti-DNA antibodies were a small fraction of the whole cell population constituting the LCL. In order to enrich the fraction of cells producing the desired antibody we performed a positive selection by DNA-coated immunomagnetic beads. Results show that in two out of three IgG anti-DNA-secreting LCL the frequency of DNA-producing cells increased after incubation with DNA-coated beads. At variance, IgM anti-DNA-secreting cells were completely lost after immunomagnetic separation. This approach could represent a further tool to obtain better fusion partners to construct stable hybrids secreting human monoclonal antibodies. The advantages of the presented technique would be: (a) removing of the fraction of low-affinity IgM-producing cells, which is often prevalent in EBV-induced LCL; and (b) the enrichment of IgG anti-DNA producing cells, which better represent the antibodies involved in the pathogenesis of the disease.

The effects of deoxyspergualin on the development of diabetes in diabetes-prone BB rats

The effects of the administration of the recently discovered immunosuppressant 15-Deoxyspergualin (DSP) on the development of insulin-dependent diabetes mellitus (IDDM) in diabetes-prone BB rats were studied. The data show that 2 mg/kg body weight DSP, administered six times a week from the 30th day up to the 105th day of age, significantly reduced the incidence of diabetes in diabetes-prone BB rats as compared with the PBS-injected controls. The drug was also able to reduce the signs of pancreatic insulitis and the percentages of W3/25+ and OX6+ splenocytes. Interruption of the treatment resulted in a later onset of diabetes in a high percentage of animals within 41 days. These findings suggest that 15-DSP may temporarily reverse the pathogenic mechanisms leading to beta cell destruction and autoimmune diabetes in a well-known experimental model of human insulin-dependent diabetes mellitus.

In vivo treatment with a monoclonal antibody to interferon-gamma neither affects the survival nor the incidence of lupus-nephritis in the MRL/lpr-lpr mouse

The effects of the in vitro treatment with a mAb (DB-1) that neutralizes mouse IFN-gamma on the development of the SLE-like syndrome in MRL/lpr-lpr (MRL-lpr) mice were studied. The results show that the i.p. administration of 2.6 mg/week of DB-1 from the 12th to the 20th week of age neither affected the survival nor the incidence and severity of lupus nephritis in MRL-lpr mice. This study argues against the pathogenic relevance of IFN-gamma in this experimental model of human SLE.

Antiphospholipid antibodies cross-reacting with erythrocyte membranes. A case report

We describe a patient with primary antiphospholipid syndrome (PAPS) and haemolytic anemia with cryoagglutinins, in whom antibodies eluted from red blood cells (RBC) displayed anti-cardiolipin (CL) binding activity. This activity was confined to the IgG isotype and was directed to the negatively-charged phospholipids only. In addition, the patient's IgG fraction displayed a higher binding to RBC in comparison to normal control IgG and this reactivity was inhibited after absorption of the anti-CL activity with CL-micelles. These findings further sustain the association between antiphospholipid antibodies (APA) and Coombs' positivity with or without haemolytic anemia and suggest that APA could be at least in part responsible for anti-RBC activity.

Antibodies to endothelial cells in primary vasculitides mediate in vitro endothelial cytotoxicity in the presence of normal peripheral blood mononuclear cells

Twenty-eight out of 62 patients with Wegener's granulomatosis and micropolyarteritis display circulating antiendothelial cell antibodies (AECA) detectable by a cell surface radioimmunoassay. These antibodies do not induce an in vitro endothelial damage either alone or in the presence of fresh complement; however, 50% of IgG-AECA positive sera can be cytotoxic in the presence of human normal peripheral blood mononuclear cells (PBM) at high effector/target ratios. The specificity of the PBM-mediated cytotoxicity is supported by the absence of the phenomenon in AECA negative sera, by the disappearance of the lytic effect after absorption of AECA, and by the finding that cellular-mediated cytotoxicity can be reproduced by purified IgG-AECA positive fractions. On the contrary, polymorphonuclear leukocytes or adherent mononuclear cells are not involved in such a cytotoxic activity. AECA seem to be directed against determinants consitutively expressed on the endothelial surface since the activation of endothelial cells by interleukin-1 beta or interferon-gamma affects neither the antibody binding nor their ability to mediate 51Cr release in the presence of PBM. These findings favor the hypothesis for a possible direct pathogenetic role of circulating AECA in the in vivo vascular damage.

Immunopharmacological activity of cefodizime in young and elderly subjects: in vitro and ex vivo studies

The biological response modifying activities of cefodizime (CDZ), a new third-generation cephalosporin, were investigated in vitro and ex vivo. In vitro investigations using cells isolated from the blood of young healthy donors showed no stimulating activity of CDZ on peripheral blood lymphocytes, natural killer cell activity, IL-1 production by adherent mononuclear cells, PMN chemiluminescence or PMN chemotaxis. A slight but statistically insignificant increase in PMN phagocytosis and phagocytic index was observed in the same population. IL-1 production was increased in three subjects with low resting state values. In a controlled ex vivo study, 20 healthy elderly subjects selected on the basis of depressed phagocytic function were treated with CDZ 1 g i.m. b.i.d. or placebo for eight days. PMN function was determined at baseline and on the day after the last dose. In the CDZ group a significant increase in both phagocytosis and phagocytic index was found, while there were no changes in the placebo group. In conclusion, CDZ restored depressed PMN phagocytic function in a population of elderly subjects. Patients with impaired PMN function who require antibiotic treatment may benefit from this activity of CDZ.

Relationship between anti-phospholipid and anti-endothelial cell antibodies: further characterization of the reactivity on resting and cytokine-activated endothelial cells

Sera positive for autoimmune anti-phospholipid antibodies were studied by a cell surface radioimmunoassay for their cross-reactivity with resting or activated human endothelial cells. The endothelial cell activation by interleukin 1 beta, gamma-interferon, lipopolysaccharide or phorbol-12 myristate-13 acetate did not affect the cross-reactivity. Comparable findings were also found by testing anti-cardiolipin affinity purified preparations. Taken together these data indicate that endothelial cell activation is not sufficient per se to modulate the expression of antigenic determinants recognizable by the anti-phospholipid antibodies. However, anti-cardiolipin affinity purified preparations displayed enhanced cell binding after cell membrane perturbation by paraformaldehyde fixation, suggesting that an alteration in endothelial cell integrity might further trigger the reaction of circulating anti-phospholipid antibodies with vessel walls in vivo.

FK-506 prevents diabetes in diabetes-prone BB/Wor rats

The effect of the immunosuppressant FK-506 on the development of diabetes in BB/Wor rats was investigated. Using a treatment schedule (25 micrograms i.m. from day 27 to 120), not associated with detectable general ill effects, this drug was found to completely inhibit the appearance hyperglycemia and to reduce the histological signs of pancreatic insulitis. The treatment was also able to reduce the percentages of Ia+ T-lymphocytes and to block the appearance of detectable serum levels of gamma interferon (IFN).