Welcome to the 13th International Congress on Autoimmunity interactive program

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Based on cytokine expression T_h-cells can be subdivided in multiple subsets. This has helped to further unravel the pathogenicity of many immune-mediated diseases. However, the distinction between subsets is rather artificial and, therefore, there is a need for an holistic view on the T_h-cell compartment. Since successful mechanisms seem to be conserved in nature, analogies were searched for and found in the form of clouds of starling and schools of herrings. Also for the T_h-cell compartment it might be better to consider it as a continuum that is able to move freely within well-defined limits in order to optimize immunity and prevent excessive pathogenic responses. Neighboring cells will, like the starlings and herrings, influence the direction of T_h-cell differentiation. The limits of movement may be typically controlled by T_reg. The challenge of this model is to define a grading system that, first, represents the skewing of the T_h-cell compartment, and, second, that indicates if the T_h-cell compartment has passed the limits of plasticity and homeostasis.

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Antibody-producing cells and memory B cells are terminally differentiated B cells that arise during adaptive humoral immune responses in germinal centers (GCs) under the supervision of T follicular helper (TFH) cells. TFH cells differentiate from CD4+ T cells in the T cell zone of secondary lymphoid organs following priming up-regulating Bcl-6 and CXCR5 expression. After entry into B cell follicles, they up-regulate PD-1 and terminally differentiate into TFH cells expressing high IL-21. Herein, TFH cells provide survival and selection signals to GC B cells inducing their terminal differentiation into plasma cells and memory B cells. We have previously demonstrated that regulatory B (Breg) cells control TFH cell maturation and inhibit TFH cell-mediated antibody secretion (Achour A et al. JACI, 2017;140:21522). The current study was aimed at evaluating their ability to modulate TFH-dependent humoral response in the context of autoimmune situations, especially in primary Sjögren’s syndrome (pSS) and systemic lupus erythematosus (SLE) patients.

Purified autologous T cells were cultured in the presence of IL12 and IL-21 cocktail and of anti-CD3 and anti-CD28 Abs to induce their polarization into TFH cells. Differentiated TFH cells were co-cultured with autologous unstimulated B cells to trigger their terminal differentiation into plasma and memory B cells. Concomitantly, purified B cells from healthy donors, pSS and SLE patients were stimulated with CpG-ODN on CD40L-transfected fibroblasts to induce their differentiation into Breg cells.

In vitro differentiated TFH cells from healthy donors co-cultured with unstimulated B cells increased the frequencies of plasma cells and memory B cells, and triggered the secretions of IgM, IgG and IgA. In the presence of autologous Bregs, TFH differentiation was inhibited, the frequencies of plasma and memory B cells remained low in the coculture system and the secretion of IgM, IgG and IgA was abrogated. Bregs from pSS patients were also efficient in the inhibition of TFH cell differentiation whilst SLE Bregs were unable to control TFH cell differentiation. Furthermore, pSS Bregs were efficient in their capacity to dampen TFH-dependent B cell terminal differentiation as well as immunoglobulin secretion. In contrast, SLE Breg were defective and unable to restrain the TFH-dependent humoral response.

Overall, Bregs are functionally effective in pSS but defective in SLE for the control of the TFH-dependent immune responses, suggesting that different mechanism involving the Bregs may be responsible for the aberrant autoreactive humoral responses seen in pSS and in SLE patients.

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For the diagnosis of an existing immunity or an immune response taking place against an acute or chronic infection, specific antibodies but also antigen-specific T cells can be detected. While serology is well established, the detection of specific T cells in routine diagnostics is still a challenge. Since T cells need to have their antigen peptides presented, tetramers can be used, but they must match the patient's HLA type and are different for CD4+ and CD8+ T cells. Assays measuring proliferation or cytokine secretion after stimulation are widely used, but often take too long and have high requirements for antigen qualities and quantities. Among current technological approaches, flow cytometric methods are the most informative, although they require some technical expertise. To offer such assays within one day, we have developed a protocol that allows quantitative measurement of virus-specific CD4+ and CD8+ T cells. For this purpose, the cells are incubated with the respective antigens. Afterwards, the phosphorylation of STAT-5 is determined intracellularly. This correlates very well with the subsequent proliferation of the T cells and provides a reliable information on cellular immunity.

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Background and aims: Allergy and autoimmunity are two potential outcomes of a dysregulated immune system. The relationship between allergy and autoimmune

disorders is complex and poorly understood.

The aim of this presentation is to summarize similarities and differences of factors influencing the pathogenesis of autoimmune and allergic disease

Methods: The current literature was reviewed using key words: Autoimmunity, allergy, HLA, cytokines, autoantigens, GWAS, SNP, Tregs.

Results: Autoimmune diseases, can reflect the interplay of both Th1- and Th2-associated mechanisms. Epidemiological data indicate that the prevalence of both allergies and autoimmune diseases increase in parallel. IgE autoreactivity exists in allergy and autoimmunityAutoantigens can trigger IgE-dependent inflammation in allergy.

Evidence for non-IgE-mediated inflammation in allergy via autoimmune mechanisms was found.

Shared genetic susceptibility loci and commonalities in pathways between allergy and autoimmune diseases exist, suggesting shared disease mechanisms.

In addition to its role in the development of autoimmune diseases, IL-17 may play a role in the development of various allergic diseases that have classically been considered to be Th2-mediated disorders.

Conclusions: Allergic and autoimmune diseases display different facets of immune dysregulation, and may coexist.

Allergic and autoimmune diseases share common aspects: genes, cytokines, mast cell involvement, Treg.

A reduction in number or activity of Foxp3+ Tregs triggers the activation of Th1 and/or Th2 responses, and may induce allergic and autoimmune diseases.

The dichotomy between TH1 and TH2 is challenged.

Background and Aims

Autoantibodies against alpha-3 nicotinic acetylcholine receptors (alpha3-nAChR), usually measured by radioimmunoprecipitation assay (RIPA), are detected in autoimmune autonomic ganglionopathy (AAG) patients, but also in patients with other neurological diseases, albeit in lower levels. Our aim is to develop a sensitive and specific method for the selective detection of the potentially pathogenic alpha3-nAChR antibodies, seemingly present only in AAG patients.

Methods

The detection of the autoantibodies against the cell-exposed alpha3-nAChR domain was performed by a live cell-based assay (CBA), which was developed with alpha3-nAChR transfected cells. The study included sera from 55 patients suspected of autonomic failure, 13 patients diagnosed with autonomic failure, positive for alpha3-nAChR antibodies by RIPA, 52 patients with Ca2+-channel or Hu antibodies and 2628 control patients with various neuroimmune diseases.

Results

RIPA detected alpha3-nAChR antibodies in 25 patient sera. 15/25 were also positive by CBA. Remarkably, all CBA-positive patients had AAG, while all CBA-negative had other neurological diseases. RIPA antibody levels of the CBA-negative sera were low, even though our CBA could detect equally low antibody levels. No serum bound to control cells, and none of the 2628 control sera was found alpha3-CBA-positive.

Conclusions

This study showed that in contrast to the established, but moderately disease-specific RIPA for alpha3-nAChR antibodies, our CBA seems AAG-specific, while at least equally sensitive with the RIPA.

Background and Aims

We hypothesize that increased numbers and/or stability of Topoisomerase 1 cleavage complexes (Top1cc) render Top1 abnormally immunogenic in SCL70 positive patients.

The physical link between Top1 and DNA might activate autoreactive B-cells in a T-cell independent way as Top1cc are self-antigen and adjuvant, as has been described for other nuclear self-antigens.

It has been shown that unrepaired ribonucleotides accumulating in the absence of RNase H2 are a substrate for Top1 which cuts the strand at these positions. We thus hypothesized that partial loss of function alleles of RNaseH2 genes contributes to the genetic risk for developing Ssc by causing DNA damage and increased numbers and/or stability of Top1cc.

Methods

We established two assays: the ICE (in vivo omplex of enzyme) and the RADAR (rapid approach to DNA adduct recovery) for detection and quantification of Top1cc in cultured cells and in mouse tissue.

Cultured cells were HeLA or MEF cells. Knock out of RNaseH2 in HeLas were introduced via CRISPR/Cas9 system, in MEFs we used the Rnaseh2b^FLOX Cre-ERT2 for inducible knock out.

For conditional cell type-specific knock outs in mice we used the Cre/loxP system for epidermal, spleen and B-cells. We used tissue of mouse embryos completely defective for RNase H2.

Positive controls were HeLas treated with Camptothecin, HeLa deficient for Tyrosyl-DNA-phosphodiesterase 1 (TDP1) and TDP1 deficient mouse embryos, all proven to show a higher amount of Top1cc.

Results

No Signal for Top1cc in tissue lacking RNaseH2.

Conclusions

Collectively these experiments could not demonstrate that cells lacking RNase H2 contain higher numbers of Top1cc.

Background and Aims

Viral infections such as COVID-19, Zika, Measles, and Dengue activate several immunological mechanisms that can evolve to autoimmune phenomena during severe disease. Particularly, the infection caused by the dengue virus (DENV) is a global health problem that affects approximately 400 million people yearly and is highly associated with the risk to develop autoimmune diseases. Nevertheless, the signatures and molecular pathways by which DENV can trigger autoimmunity remain unknown. Here, we performed a multi-study analysis of publicly available RNA sequencing data of T cell subsets isolated from peripheral blood leukocytes of Dengue patients (n = 40) to investigate these mechanisms.

Methods

We assessed the immunotranscriptomic profile of T effector and memory cells, finding patterns according to cell type and disease severity using an integrative systems immunology approach and machine learning predictive analysis.

Results

We identified 108 differentially expressed genes (DEGs) that enrich negative regulation of T-helper 17 type immune response (GO:2000317) as well as the regulation of T-helper 17 cells differentiation (GO:2000319) and/or regulation of regulatory T cell differentiation. Furthermore, while these processes and pathways appear upregulated in CD4+ TCM, TEM, and TEMRA cells, they are downregulated in CD8+ effector cells. Of note, these DEGs are mostly dysregulated in patients with severe Dengue. Among them, IRF4, VDAC1, UQCRQ, CTLA4, NDUFC2, RARA, and BCL6, are the most consistently dysregulated genes.

Conclusions

Thus, this study suggests new immunomodulatory signatures which might be involved in the development of autoimmunity in patients with DENV infections.

Background and Aims

Background: Wiskott-Aldrich syndrome (WAS) is an X-linked combined immunodeficiency characterized by a triad of thrombocytopenia, eczema, and immunodeficiency. Patients with WAS are not only prone to recurrent infections but are at risk of developing autoimmunity and malignancy.

AIM: To compare Helper T1 (Th1)/Th2 axis, Regulatory T (Treg)/Th17 axis, and Follicular helper T (Tfh) cells in patients with or without autoimmunity and controls.

Methods

Case records of 8 children with WAS, who were been followed up in Pediatric Immunodeficiency Clinic of Advanced Pediatrics Centre, PGIMER, Chandigarh, India were reviewed. After genetic confirmation, T cell subsets were estimated flowcytometric in these patients along with age/sex match healthy controls. One-way ANOVA test was applied (p-value<0.1 was considered significant).

Results

Out of a cohort of 50 patients, 8 patients were enrolled in the study. Among 8, 4 patients developed autoimmune manifestations and 4 were without autoimmunity. In the autoimmune group, 2 patients had autoimmune hemolytic anemia (AIHA), out of which 1 was positive for Direct Coombs test. One patient had leukocytoclastic vasculitis and 1 had Guillain-Barre syndrome-like disease. Th1/Th2 axis was out of proportion in all 8 patients. Th2 cells were increased as compared to controls and patients without autoimmunity (p<0.1). Treg cells in patients with autoimmunity were increased as compared to controls and patients without autoimmunity (p=). Tfh were significantly reduced in patients with autoimmunity than in controls and patients without autoimmunity (p<0.01).

Conclusions

Severely affected Th1/Th2 axis along with reduced Tfh cells may result in susceptibility towards autoimmunity.

Background and Aims

Background: Holocaust-survivors suffer from higher rates of various morbidities. It is speculated that this phenomenon is due to exposure to the extreme stress and horrors of that era. In this study we hypothesized that these factors contributed to higher rates of autoimmune disease in Holocaust-survivors.

Objective: To evaluate the prevalence rate of several autoimmune diseases among Israeli Holocaust-survivors in comparison with their peer group within the general population.

Methods

Design: A cross-sectional study, based on Israel’s biggest HMO digital health records, spanning from January 2002 up to March 2019.

Population: Members of Clalit Healthcare services that survived the Holocaust were matched by age and gender, in a 1:1 ratio, to non-survivor members.

Statistics: Autoimmune diseases were analyzed separately and as a composite autoimmunity variable. Prevalence rates were calculated for both the Holocaust-survivor group and their matched controls. Then crude and adjusted prevalence odds ratios (POR) were calculated.

Results

Results: 105,995 Holocaust-survivors and another 105,995 matched controls were included in the analysis. We found a prevalence rate of autoimmune disease among Holocaust-survivors of 87 per 1,000 (0.087). Psoriasis was the most prevalent disease among both the survivor and control groups, with a prevalence of 46 per 1,000 (0.046) and 14 per 1,000 (0.014) respectively. The adjusted POR for autoimmunity was 3.6 (95% CI, 3.4-3.8); and as high as 3.9 (95% CI, 2.8-5.5) for Graves’ disease.

Conclusions

Conclusions: We found that Holocaust-survivors suffer from higher rates of autoimmune morbidity. Furthermore, we found a strong association between exposure to the horrors of the Holocaust and autoimmunity.