Expression Of HLA-DR Molecules Research Articles

HLA-DR-Expressing Fibroblast-Like Synoviocytes Are Inducible Antigen Presenting Cells That Present Autoantigens in Lyme Arthritis.

HLA-DR-expressing fibroblast-like synoviocytes (FLS) are a prominent cell type in synovial tissue in chronic inflammatory forms of arthritis. FLS-derived extracellular matrix (ECM) proteins, including fibronectin-1 (FN1), contain immunogenic CD4+ T cell epitopes in patients with postinfectious Lyme arthritis (LA). However, the role of FLS in presentation of these T cell epitopes remains uncertain. Primary LA FLS and primary murine FLS stimulated with interferon gamma (IFNγ), Borrelia burgdorferi, and/or B burgdorferi peptidoglycan (PG) were assessed for properties associated with antigen presentation. HLA-DR-presented peptides from stimulated LA FLS were identified by immunopeptidomics analysis. OT-II T cells were co-cultured with stimulated murine FLS in the presence of cognate ovalbumin antigen to determine the potential of FLS to act as inducible antigen presenting cells (APCs). FLS expressed HLA-DR molecules within inflamed synovial tissue and tendons from patients with postinfectious LA in situ. Major histocompatibility complex (MHC) class II and co-stimulatory molecules were expressed by FLS following in vitro stimulation with IFNγ and B burgdorferi and presented both foreign and self-MHC-II peptides, including an immunogenic T cell epitope derived from Lyme autoantigen FN1. Stimulated FLS induced proliferation of naive OT-II CD4+ T cells that were dependent on OT-II antigen and CD40. Stimulation with B burgdorferi PG enhanced FLS-mediated T cell activation. MHC-II+ FLS are inducible APCs that can induce CD4+ T cell activation in an antigen- and CD40-dependent manner. Activated FLS can also present ECM-derived Lyme autoantigens, implicating FLS in amplifying tissue-localized autoimmunity in LA.

The CD4+ T cell repertoire specific for citrullinated peptides shows evidence of immune tolerance.

Rheumatoid arthritis occurs most often in people who express HLA-DR molecules containing a five aa "shared epitope" in the β chain. These MHCII molecules preferentially bind citrullinated peptides formed by posttranslational modification of arginine. Citrullinated peptide:HLA-DR complexes may act as arthritis-initiating neo-antigens for CD4+ T cells. Here, we used fluorophore-conjugated HLA-DR tetramers containing citrullinated peptides from human cartilage intermediate layer protein, fibrinogen, vimentin, or enolase 1 to track cognate CD4+ T cells. Immunization of HLA-DR transgenic mice with citrullinated peptides from vimentin or enolase 1 failed to cause any expansion of tetramer-binding cells, whereas immunization with citrullinated peptides from cartilage intermediate layer protein or fibrinogen elicited some expansion. The expanded tetramer-binding populations, however, had lower T helper 1 and higher regulatory T cell frequencies than populations elicited by viral peptides. These results indicate that HLA-DR-bound citrullinated peptides are not neo-antigens and induce varying degrees of immune tolerance that could pose a barrier to rheumatoid arthritis.

HLA-monomorphic determinants of the primary tumor in breast cancer patients

Background. Molecules of the major histocompatibility complex in cancer are currently being widely studied, and their clinical significance is still the subject of controversy. It is reported that they might have an important predictive value in the effectiveness of immunotherapy. The study of the expression HLA molecules status in breast cancer provides a deeper understanding of the biological properties of the tumor, in particular to identify the features of its immunological phenotype, which may further influence on breast cancer therapy.Aim. To evaluate the frequency of HLA-immunophenotypes in breast cancer and their relationship with the clinical and morphological features of the primary tumor.Materials and methods. This study included 82 patients with breast cancer who received treatment at the N.N. Blokhin National Medical Research Center of Oncology, Ministry of Health of Russia. Immunophenotyping of the primary tumor was performed by immunofluorescence on cryostat sections. The reaction was evaluated using a ZEISS Axioscope 5 luminescent microscope (Zeiss AG, Germany). The study was dominated by patients with stage IIB 54 %, stage IIA was detected in 5 % of cases, IIIA – in 12 % of cases, IIIB – in 21 % of cases, IIIC – 8 %. Infiltrative ductal breast cancer was diagnosed in 67 % of patients (n = 55), infiltrative-lobular – in 22 % of cases (n = 18), other types – in 11 % (n = 9). The frequency of immunophenotypes was studied depending on the clinical and morphological characteristics of breast cancer.Results. It was found that in the group as a whole, the HLA-binegative immunophenotype of breast cancer was predominant. It dominated at stage T4 compared to the HLA-I+/HLA-DR+ phenotype (100 and 0 %), p = 0.042. At the same time, it should be noted that in T4 primary tumor the HLA-I+/HLA-DR– immunophenotype was also observed. The relationship this immunophenotype was noted with the stage: frequency at stage IIIA was higher than the HLA-I+/HLA-DR+ phenotype, 60 and 40 %, p = 0.01. Both HLA-DR-negative immunophenotypes were characterized by a high incidence of lymph node involvement and the absence of estrogen receptor expression. 80 % of receptor-negative tumors were noted in HLA-binegative immunophenotype compared to phenotype HLA-I+/HLA-DR+, p = 0.022; the similar data were obtained for the HLA-I+/HLA-DR– immunophenotype (p = 0.037).Conclusion. HLA immunophenotypes analysis of breast cancer revealed the HLA-binegative immunophenotype of breast cancer was predominant. The second most common immunophenotype was the absence of expression of HLA-DR molecules. The association of HLA-immunophenotypes with the stage of the tumor process, the size of the primary tumor, and the expression status of estrogen receptors was revealed.

The transcription factor RFX5 coordinates antigen-presenting function and resistance to nutrient stress in synovial macrophages.

Tissue macrophages (Mϕ) are essential effector cells in rheumatoid arthritis (RA), contributing to autoimmune tissue inflammation through diverse effector functions. Their arthritogenic potential depends on their proficiency to survive in the glucose-depleted environment of the inflamed joint. Here, we identify a mechanism that links metabolic adaptation to nutrient stress with the efficacy of tissue Mϕ to activate adaptive immunity by presenting antigen to tissue-invading T cells. Specifically, Mϕ populating the rheumatoid joint produce and respond to the small cytokine CCL18, which protects against cell death induced by glucose withdrawal. Mechanistically, CCL18 induces the transcription factor RFX5 that selectively upregulates glutamate dehydrogenase 1 (GLUD1), thus enabling glutamate utilization to support energy production. In parallel, RFX5 enhances surface expression of HLA-DR molecules, promoting Mϕ-dependent expansion of antigen-specific T cells. These data place CCL18 at the top of a RFX5-GLUD1 survival pathway and couple adaptability to nutrient conditions in the tissue environment to antigen-presenting function in autoimmune tissue inflammation.

Circulating Memory B Cells in Early Multiple Sclerosis Exhibit Increased IgA+ Cells, Globally Decreased BAFF-R Expression and an EBV-Related IgM+ Cell Signature.

Multiple sclerosis (MS) is an immune-mediated inflammatory disease of the central nervous system that results in demyelination of axons, inefficient signal transmission and reduced muscular mobility. Recent findings suggest that B cells play a significant role in disease development and pathology. To further explore this, B cell profiles in peripheral blood from 28 treatment-naive patients with early MS were assessed using flow cytometry and compared to 17 healthy controls. Conventional and algorithm-based analysis revealed a significant increase in MS patients of IgA+ memory B cells (MBC) including CD27+, CD27- and Tbet+ subsets. Screening circulating B cells for markers associated with B cell function revealed a significantly decreased expression of the B cell activation factor receptor (BAFF-R) in MS patients compared to controls. In healthy controls, BAFF-R expression was inversely associated with abundance of differentiated MBC but this was not observed in MS. Instead in MS patients, decreased BAFF-R expression correlated with increased production of proinflammatory TNF following B cell stimulation. Finally, we demonstrated that reactivation of Epstein Barr Virus (EBV) in MS patients was associated with several phenotypic changes amongst MBCs, particularly increased expression of HLA-DR molecules and markers of a T-bet+ differentiation pathway in IgM+ MBCs. Together, these data suggest that the B cell compartment is dysregulated in MS regarding aberrant MBC homeostasis, driven by reduced BAFF-R expression and EBV reactivation. This study adds further insights into the contribution of B cells to the pathological mechanisms of MS, as well as the complex role of BAFF/BAFF-R signalling in MS.

Circulating Placental Vesicles Carry HLA-DR in Pre-Eclampsia: A New Potential Marker of the Syndrome.

BackgroundPre-eclampsia (PE) is a common disorder of pregnancy that usually presents with hypertension and proteinuria. The clinical presentation arises from soluble factors released into the maternal circulation from the placenta owing to the stress of syncytiotrophoblast, consequence of defective placentation occurring in the first half of pregnancy. Reduced tolerance of the semiallogeneic fetus by the maternal immune system has been proposed as first trigger leading to poor placentation. We previously observed aberrant expression of human leukocyte antigen (HLA)-DR molecules in the syncytiotrophoblast of a subset of women with PE. Aim of this study was to investigate abnormal expression of circulating HLA-DR in syncytiotrophoblast-derived extracellular vesicles (STBEVs) in women with PE compared to normal pregnant women.Methodsperipheral venous blood was collected from 22 women with PE and 22 normal pregnant women. Circulating STBEVs were collected by ultra-centrifugation (120000 g) and analyzed for the expression of HLA-DR and placental alkaline phosphatase (PLAP), a specific marker of the placenta, by Western blot analysis and flow cytometry.Resultscirculating STBEVs positive for HLA-DR were observed in 64% of PE women while no HLA-DR positivity was detected in any of the controls (P<0.01).ConclusionsAberrant expression of HLA-DR in circulating STBEVs is specifically associated to PE. Further studies are required: a) to define the role of aberrant placental expression of HLA-DR molecules in the pathogenesis of PE; b) evaluate a possible application of detecting circulating HLA-DR positive STBEVs in the diagnosis and prediction of PE in the first and second trimester of pregnancy.

Monocyte HLA-DR Measurement by Flow Cytometry in COVID-19 Patients: An Interim Review.

Several months after the sudden emergence of SARS-CoV-2 and COVID-19, the understanding of the appropriate host immune response to a virus totally unknown of human immune surveillance is still of major importance. By international definition, COVID-19 falls in the scope of septic syndromes (organ dysfunction due to dysregulated host response to an infection) in which immunosuppression is a significant driver of mortality. Sepsis-induced immunosuppression is mostly defined and monitored by the measurement of decreased expression of HLA-DR molecules on circulating monocytes (mHLA-DR). In this interim review, we summarize the first mHLA-DR results in COVID-19 patients. In critically ill patients, results homogenously indicate a decreased mHLA-DR expression, which, along with profound lymphopenia and other functional alterations, is indicative of a status of immunosuppression. © 2020 International Society for Advancement of Cytometry.

Effect of thermal spring water on human dendritic cell inflammatory response.

BackgroundHydrotherapy appears as a valuable therapeutic tool in the management of patients suffering from chronic skin inflammatory diseases. Nevertheless, the underlying immune mechanisms of these beneficial effects remain poorly understood. To better understand the biological effects of thermal spring water on the immune system, we investigated the effects of Avène thermal spring water (ASW) on dendritic cells as key cells participating in the control of the immune response.MethodsDendritic cells (DCs) were generated from human monocytes and matured with LPS in ASW-based culture medium or in dexamethasone supplemented culture medium as an anti-inflammatory treatment. The phenotypes and abilities of these DCs to produce cytokines and induce allogeneic T cell response was next assessed.ResultsWe showed that ASW modulated the differentiation of monocytes into DCs and impacted the DC maturation upon LPS priming. We observed a reduction of the CD83, CD86, CD1a and HLA-DR molecule expression and a decrease of IL-12 and IL-23 production whereas IL-10 production was increased. LPS-primed DCs generated in presence of ASW exhibited a reduced capacity to induce naive CD4+ T cell proliferation and IFN-γ and IL-17 production.ConclusionOur study showed that ASW is endowed with an immunomodulatory potential. ASW limits the DC stimulatory capacity of Th1 and Th17 cell responses by impairing their maturation, IL-12 and IL-23 production and accessory cell function.

Alterations of the iNKT cell compartment in brain-injured patients

BackgroundBrain injury (BI) induces a state of immunodepression leading to pneumonia. We investigated the invariant natural killer T (iNKT) cell compartment.MethodsThis is an observational study in two surgical intensive care units (ICUs) of a single institution and a research laboratory. Clinical data and samples from a prospective cohort were extracted. Severe brain-injured patients (n = 33) and sex- and age-matched healthy donors (n = 40) were studied.ResultsWe observed the presence of IL-10 in serum, a loss of IFN-γ and IL-13 production by peripheral blood mononuclear cells (PBMCs) following IL-2 stimulation, and downregulation of HLA-DR expression on both monocytes and B cells early after BI. Inversely, CD1d, the HLA class I-like molecule involved in antigen presentation to iNKT cells, was over-expressed on patients’ monocytes and B cells. The antigen-presenting activity to iNKT cells of PBMCs was increased in the patients who developed pneumonia, but not in those who remained free of infection. Frequencies of iNKT cells among PBMCs were dramatically decreased in patients regardless of their infection status. Following amplification, an increased frequency of CD4+ iNKT cells producing IL-4 was noticed in the group of patients free of infection compared with those who became infected and with healthy donors. Finally, serum from BI patients inhibited the iNKT cells’ specific response as well as the non-specific IL-2 stimulation of PBMCs, and the expression of the beta-2 adrenergic receptor was elevated at the surface of patients T lymphocytes.ConclusionsWe observed severe alterations of the iNKT cell compartment, including the presence of inhibitory serum factors. We demonstrate for the first time that the decreased capacity to present antigens is not a generalized phenomenon because whereas the expression of HLA-DR molecules is decreased, the capacity for presenting glycolipids through CD1d expression is higher in patients.

MONOCYTE SUBSETS IN HEALTHY ADULTS AND SEPSIS PATIENTS

Monocytes play a key role in the development of immune response in bacterial infection, because of their phagocytic, antigen-presenting and secretory functions. There are three subpopulations of monocytes: “classical” CD14+CD16-, “intermediate” CD14+CD16+, and “nonclassical” CD14+dimCD16+. These monocyte subtypes have different phenotypes and functions. The ratio of appropriate subpopulations varies with development of the antibacterial response. The aim of the present research was to study phenotypes of the monocyte subpopulations in the patients with sepsis, and changes in the monocyte subpopulation ratio, depending on the presence of bacteria in circulating blood of the patients, as well as to estimate contribution of the monocyte subpopulations to the cytokine production. We observed 16 patients with sepsis (10 men and 6 women; mean age, 58±14 years, SOFA 9.4±2.1; a total of 44 blood samples) examined in dynamics. The control group included healthy adults (n = 23, 12 men and 11 women; mean age, 51±13 years). Laboratory studies included bacteriological cultures, determination of absolute and relative numbers of subpopulations of classical, intermediate and non-classical monocytes and their expression of HLA-DR and CD64, determination of IL-6, TNFα, IL-1β, IL-10 concentration in blood serum. Absolute number of monocytes was increased in the sepsis patients, the ratio of classical monocytes was also increased, like as relative and absolute numbers of intermediate cells. Meanwhile, the subpopulation of non-classical monocytes did not change significantly. The monocyte subpopulation ratio depended on the presence of bacteria in blood, i.e., a higher proportion of intermediate cells was observed in the samples positive for bacteria in blood cultures. The ratio of subpopulations was restored after elimination of bacteria from the circulation. The expression density of LPS receptor (CD14), IgG receptors (CD16 and CD64) was found to be increased, especially in the subpopulations of intermediate and nonclassical monocytes. In all subpopulations of monocytes, expression of HLA-DR is reduced, most notably in classical monocytes, least in intermediate cells. There was a significant increase in serum levels of IL-6, IL-1β, TNFα and IL-10 cytokines. Direct correlation between the absolute number of classical monocytes and IL-6 concentration was revealed, as well as intensity of multiple organ dysfunction. Increase in absolute amount of classical monocytes and IL-6 concentration might serve as an indirect criterion for evaluation of endothelial activation, an active producer of IL-6 and myeloid cell growth factors. A direct correlation between the percentage of CD14+CD16+ cells and IL-10 concentration in blood serum indicates to an important role of intermediate monocytes in IL-10 production. IL-10 suppresses the antigen-presenting function of intermediate cells, namely, expression of HLA-DR molecules, as suggested by inverse correlation between the IL-10 concentration and HLA-DR expression density on CD14+CD16+ cells. We have also determined an inverse correlation between the degree of multi-organ dysfunction and relative amount of HLA-DR+ monocytes. The larger was a classical monocyte subpopulation, the more noticeable was a decrease of this index. The studies in ratios of monocyte subpopulations help to understand the mechanisms of antibacterial protection in sepsis. Monitoring of classical monocyte numbers and serum concentrations of IL-6 is necessary for a comprehensive assessment of inflammatory response in sepsis. Determination of HLADR expression on monocytes allows us to evaluate the intensity of immune suppression in critically ill patients.

Individual Differences of Multipotent Mesenchymal Stromal Cells Manifesting in during Interaction with Lymphocytes.

Analysis of changes in lymphocyte subpopulations during co-culturing with multipotent mesenchymal stromal cells (MSC) revealed two distinct MSC groups: one group (A) increased HLA-DR expression on lymphocytes during co-culturing and the other (B) did not change it in comparison with lymphocyte monoculture. In stromal cells interacting with lymphocytes, expression of HLA-DR molecules was initiated, but only in samples that induced enhanced expression on lymphocytes and irrespectively of whether allogeneic or autologous lymphocytes were used for co-culturing with MSC. In group A, the relative expression of IDO1 significantly increased in comparison with group B. The revealed individual differences in MSC can explain why not all MSC samples are effective in the treatment of autoimmune diseases, acute "graft-versus-host" disease, and other pathologies.

Co-Culturing of Multipotent Mesenchymal Stromal Cells with Autological and Allogenic Lymphocytes.

We studied the effect of autologous and allogeneic lymphocytes on multipotent mesenchymal stromal cells in co-culture. It is shown that changes in multipotent mesenchymal stromal cells and in lymphocytes did not depend on the source of lymphocytes. Contact with lymphocytes triggers expression of HLA-DR molecules on multipotent mesenchymal stromal cells and these cells lose their immune privilege. In multipotent mesenchymal stromal cells, the relative level of expression of factors involved in immunomodulation (IDO1, PTGES, and IL-6) and expression of adhesion molecule ICAM1 increased, while expression of genes involved in the differentiation of multipotent mesenchymal stromal cells remained unchanged. Priming of multipotent mesenchymal stromal cells with IFN did not affect these changes. In turn, lymphocytes underwent activation, expression of HLA-DR increased, subpopulation composition of lymphocytes changed towards the increase in the content of naïve T cells. These findings are important for cell therapy.

Selenium supplementation in thyroid associated ophthalmopathy: an update.

The therapeutic effect of selenium (Se) has already been proven in thyroid disease and thyroid associated ophthalmopathy (TAO). In spite of clear scientific proof of its benefits in TAO, there appears to be no clear agreement among the clinicians regarding its optimum dose, duration of the treatment, efficacy and safety to date. In this review, the author summarises the findings of 135 English language articles published on this subject over the past four decades from 1973 to 2013. The regulation and metabolism of thyroid hormones require a steady supply of Se and recent studies have revealed several possible mechanisms by which Se improves the severity of thyroid disease and TAO. These mechanisms include 1) inhibitory effect of HLA-DR molecule expression on thyrocytes; 2) profound reductions of thyroid stimulating hormone (TSH) receptor antibodies (TSHR-Ab) and TPO antibodies (TPO-Ab); 3) prevention of dysregulation of cell-mediated immunity and B cell function; 4) neutralising reactive oxygen species (ROS) and inhibition of redox control processes required for the activation, differentiation and action of lymphocytes, macrophages, neutrophils, natural killer cells involved in both acute and chronic orbital inflammation in TAO; 5) inhibition of expression of pro-inflammatory cytokines and 6) inhibition of prostaglandin and leukotriene synthesis. An increased oxidative stress has been observed in both acute and chronic phases of thyroid disease with raised tissue concentrations of ROS. The benefits of Se supplementation in individuals with TAO appear to be proportionate to the degree of systemic activity of the thyroid disease. The maximal benefit of Se supplementation is therefore seen in the subjects who are hyperthyroid. Restoration of euthyroidism is one of the main goals in the management of TAO and when anti-thyroid drugs are combined with Se, the patients with Graves' disease (GD) and autoimmune thyroiditis (AIT) achieved euthyroidism faster than those treated with anti-thyroid drugs alone. Se status of normal adult humans can vary widely and Se supplementation may confer benefit only if serum Se levels are insufficient. The author recommends that serum Se levels of patients with TAO to be assessed prior to and during Se supplementation at regular intervals to avoid potential iatrogenic chronic Se overdose.

Analysis of inflammatory processes in diffuse thickening of human aorta intima

It is generally recognized that accumulation of lipids and immune inflammatory cells is an early sign of atherosclerosis. In the present study, we investigated the relationship between the deposition of lipids, immune inflammatory cell content and expression of HLA-DR molecules, and class II major histocompatibility complex (MHC) (a marker of immune activation) in diffuse intima thickening (DIT). Lipids, including triglycerides, cholesterol esters, free cholesterol, and phospholipids were studied by chromatography and Oil Red O histochemistry, as well as by electron microscopy. Immune inflammatory cells and the expression of HLA-DR were investigated by immunohistochemistry in serial sections of the same tissue samples. It has been shown that the lipids were unevenly distributed in DIT. In the juxtaluminal sublayer, lipids were detected in the cytoplasm of intima cells and the extracellular area. In the juxtamedial musculoelastic sublayer of the intima, lipids were present predominantly along elastic fibers. The positive correlation between the presence of lipids and the expression of HLA-DR was revealed (r = 0.79; p < 0.001). A positive correlation was also found between the deposition of lipids and the number of immune inflammatory cells, although correlation was different for different sublayers of the intima. In particular, the correlation between the deposition of lipids and immune inflammatory cells in the juxtaluminal sublayer of the intima was higher (r = 0.69; p < 0.001) than in the juxtamedial musculoelastic layer (r = 0.28; p < 0.001). These data support the hypothesis that the accumulation of lipids in the intima is a key factor in the initiation of inflammatory reactions. At the preatherosclerotic stage of development of this disease, earlier pathological processes associated with lipid-dependent activation of immune cells occur mainly in the juxtaluminal portion of the intima.

Abstract 4709: EGFR inhibition augments anti-tumor immune responses by HER family-specific human CD4 helper T cells in vitro.

Abstract Despite immunotherapy is a promising approach for cancer treatment, there are many obstacles remain to be overcome. The characteristics of tumor evasion of immune surveillance are produced by decreased expression of immune molecules and secretion of immunoregulatory cytokines. To break these tumor microenvironment which act as suppressor of antitumor immunology, we evaluated the value of EGFR inhibitors as immune-modulators. Following two days EGFR tyrosine kinase inhibitor treatment, expression of HLA-DR molecule of head and neck squamous cancer (HNSCC) cell lines were increased, meanwhile EGFR blocking antibody treatment augmented HLA-DR expression. Furthermore, EGFR inhibitors decreased spontaneous secretion of IL-8 and TGF-β from HNSCC cell lines. To confirm the immune supporting activity of EGFR inhibitors, tumor antigen specific CD4 helper T lymphocyte (HTL) responses to EGFR-expressing tumor were investigated. We identified novel EGFR HTL epitope using MHC class II binding algorithms. The candidate EGFR peptide elicited HTL responses against EGFR-expressing HNSCC in vitro. The EGFR peptide shares high homology to HER2, HER-3 and c-Met, so that these were able to stimulate EGFR peptide reactive HTLs responses in a HLA-DR restricted manner indicating that the EGFR peptide serves a universal tumor-associated peptide in HER family and c-Met. Finally, we evaluated EGFR reactive HTL responses against HNSCC cell lines treated with EGFR inhibitors. As a result, EGFR inhibitors drastically increased HTL IFN-γ production and cytotoxic response. Since HER family and c-MET have been considered as targets of alternative pathway of EGFR inhibition, therapeutic strategy combining EGFR inhibitors with novel HTL epitope identified in this study might be attractive option for antitumor immunotherapy. Citation Format: Takumi Kumai, Yasuaki Harabuchi, Hiroya Kobayashi. EGFR inhibition augments anti-tumor immune responses by HER family-specific human CD4 helper T cells in vitro. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4709. doi:10.1158/1538-7445.AM2013-4709

Effect of Selenium on HLA-DR Expression of Thyrocytes.

Autoimmune thyroid diseases (ATDs) represent the most frequent forms of the organ-specific autoimmune thyroid disorders that result from interaction between genetic and environmental factors. Selenium has been shown to exert a beneficial effect on the autoimmune thyroiditis. In spite of therapeutical effect of selenium on autoimmunity, the mechanism of its action has not been revealed. Objective. To determine whether selenium in vitro thyrocytes cultures are able to influence the HLA-DR molecule expression of human thyrocytes and production of free oxygen radicals. Method. Thyrocytes were prepared from human thyroid gland and cultured in vitro in the presence of interferon-γ and sodium selenite. The expression of HLA-DR molecules induced by interferon-γ in the presence of sodium selenite of various concentration was measured by fluorescence-activated cell sorter. Results. Selenium has a dose-dependent inhibitory effect on the expression of HLA-DR molecules of thyrocytes induced by interferon-γ. This effect of selenium was in the inverse correlation with antioxidative capacity. Conclusion. Beneficial effect of selenium on autoimmune mechanism is a complex mechanism in which the inhibitory effect on HLA-DR molecule expression and antioxidative capacity are involved into therapy of autoimmune thyroiditis.

Peptides Presented by HLA-DR Molecules in Synovia of Patients with Rheumatoid Arthritis or Antibiotic-Refractory Lyme Arthritis

Disease-associated HLA-DR molecules, which may present autoantigens, constitute the greatest genetic risk factor for rheumatoid arthritis (RA) and antibiotic-refractory Lyme arthritis (LA). The peptides presented by HLA-DR molecules in synovia have not previously been defined. Using tandem mass spectrometry, rigorous database searches, and manual spectral interpretation, we identified 1,427 HLA-DR-presented peptides (220-464 per patient) from the synovia of four patients, two diagnosed with RA and two diagnosed with LA. The peptides were derived from 166 source proteins, including a wide range of intracellular and plasma proteins. A few epitopes were found only in RA or LA patients. However, two patients with different diseases who had the same HLA allele had the largest number of epitopes in common. In one RA patient, peptides were identified as originating from source proteins that have been reported to undergo citrullination under other circumstances, yet neither this post-translational modification nor anti-cyclic citrullinated peptide antibodies were detected. Instead, peptides with the post-translational modification of S-cysteinylation were identified. We conclude that a wide range of proteins enter the HLA-DR pathway of antigen-presenting cells in the patients' synovial tissue, and their HLA-DR genotype, not the disease type, appears to be the primary determinant of their HLA-DR-peptide repertoire. New insights into the naturally presented HLA-DR epitope repertoire in target tissues may allow the identification of pathogenic T cell epitopes, and this could lead to innovative therapeutic interventions.

Development and preliminary clinical evaluation of a peptide immunotherapy vaccine for cat allergy

Allergic sensitization to cat allergens is common and represents a major risk factor for asthma. Specific immunotherapy (SIT) is effective but cumbersome and associated with IgE-dependent adverse events. Immunotherapy targeting allergen-specific T cells, with synthetic peptides representing T-cell epitopes, might improve safety and reduce the duration of treatment. We sought to define major T-cell epitopes of Fel d 1 for peptide immunotherapy, generate a peptide vaccine, and evaluate its safety and tolerability in subjects with cat allergy. We determined the binding affinities of Fel d 1 peptides for 10 commonly expressed HLA-DR molecules. Functionally immunodominant peptides were identified by means of proliferation and cytokine secretion. Histamine-releasing activity was assessed, and a peptide vaccine was formulated. Safety and tolerability were evaluated in a dose-ranging phase IIa clinical trial. MHC-binding sequences were identified throughout Fel d 1. Some regions contained multiple overlapping T-cell epitopes that bound multiple MHC molecules. Immunodominant sequences were identified on the basis of proliferative and cytokine (IFN-γ, IL-10, and IL-13) responses. Cat allergen extract, but not peptides, induced histamine release in blood basophils. A single administration of peptide vaccine was safe and well tolerated. The dose of vaccine resulting in the greatest inhibition of the late-phase skin response to intradermal whole allergen challenge was 3 nmol. Fel d 1 contains multiple overlapping MHC-binding motifs. A peptide vaccine comprising the immunodominant regions of the allergen was safe and well tolerated when given to subjects with cat allergy as a single dose. The dose of vaccine resulting in the greatest reduction in late-phase skin response was defined for future clinical development.

Regulation of HLA class II expression prevents allogeneic T‐cell responses

Human leukocyte antigen (HLA) class II molecules are polymorphic heterodimers that present peptides to CD4+ T-cells. The HLA-DM molecule contributes to assemble HLA class II-peptide complexes. We investigated the effect of silencing either HLA-DR or HLA-DM expression in the allogeneic T-cell responses. The delivery of HLA-DR- or HLA-DM-specific short hairpin RNAs (shRNAs) in a monocytic cell line caused a decrease by up to 85% and 75% at the respective mRNA level. Allogeneic T-cells stimulated with HLA-DM-silenced monocytes decreased to 30% granzyme B mRNA and interferon gamma (IFN-γ) production in comparison with T-cells stimulated with monocytes expressing a non-specific shRNA. By contrast, HLA-DR-silenced monocytes did not induce proliferation, up-regulation of granzyme B mRNA levels or high IFN-γ secretion by allogeneic T-cells vs HLA-DR expressing cells. Direct targeting of HLA-DR expression prevented more efficiently an allogeneic T-cell response in comparison with the knockdown of the expression of HLA-DM molecules. Silencing the expression of HLA-DR molecules might contribute to the development of new allogeneic cell-based therapeutic approaches.

Dose Finding Study of Lenalidomide as Maintenance Therapy In Multiple Myeloma After Allogeneic Stem Cell Transplantation

AbstractAbstract 2376Allogeneic stem cell transplantation (HSCT) for multiple myeloma is a potential curative treatment approach. A high number of relapses after allogeneic stem cell transplantation after reduced intensity conditionings underlying the need of post transplant strategies to improve remission rates and disease free survival.Lenalidomide is an effective drug in treatment of multiple myeloma patients. The efficacy and the immunmodulatory properties on T- and NK- cells may augment the Graft versus Myeloma effect after HSCT, but myelosuppression as well as induction of GvHD is a concern of using the drug early after allogeneic stem cell transplantation.Study objective was to determine the maximal tolerable dose (evaluating three dose levels) of lenalidomid after HSCT in patients with multiple myeloma. A total of 18 patients with multiple myeloma were enrolled so far.Lenalidomide as single agent maintenance treatment was started between 100 and 180 days after HSCT. In the first subgroup three patients started with dose of 5 mg daily from day 1 till 21 for duration of four cycles. In this group dose limited toxicities not appear. The next higher dose level was 10 mg/d lenalidomide for a total of 6 patients. In this cohort of patients, 3 patients showed dose limiting toxicities, which were caused by an acute pancreatitis in one case, elevated liver enzymes (CTC grade III), attribute to liver GvHD in one case and renal insufficiency in one patient. Because 3 patients in 10 mg cohort developed DLT, the maximum tolerate dose has been declared as 5 mg.So far 6 additional patients were treated with this dose level (5 mg/d, day 1–21). In these cohort four patients experienced CTC grad III toxicity was observed: two cases with acute GvHD, one case with elevated liver enzymes and one case with intolerance and dizziness.Beside lenalidomide's effect on myeloma cells, the drug is a known immune modulator. We therefore, analysed T- and NK cell subsets of patient peripheral blood by flow cytometry after lenalidomide treatment. An increase of 6% in activated CD3 cells was observed, as indicated by expression of HLA-DR molecules. Furthermore, except for the increase of whole CD8 cell number, we also observed increased proinflammatory CD8/INFg+ T cell numbers (1,5% to 4,5% p=ns). Along with the T cell date, NK cells expressed more activating receptors, like NKp44 and less inhibitory receptors, like NKG2A, support the immunmodulatory efficacy of lenalidomide.We concluded 5 mg lenalidomide as a single agent is the maximum tolerate dose if used early after allogeneic stem cell transplantation (day 100 – 180). Lenalidomide has high immune modulatory properties that might increase the risk of GvHD by activating CD8 cell. Combining lenalidomide with immunosuppressive drugs such as dexamethasone or bortezomib may reduce the risk of GvHD. Disclosures:Schonland: Celgene: Research Funding. Kröger: celgene: Research Funding.