Luxury brands consumption: The segment of “Chandlers”

The purpose of this paper is to introduce the segment of “chandlers” to the Russian academic society and to describe the specifics of their contemporary consumer behavior. The term “chandler” for this study was borrowed from American classical literature and applied to marketing. The study was conducted in April 2016 and comprised of two stages. The first stage was a series of in-depth interviews with seven representatives of the target audience from Moscow. It allowed to formulate the hypotheses which were proved/disproved by these hypotheses during the online survey. 117 relevant respondents were chosen for the study (72 — from Moscow, 45 — from regional city Ufa). The results allowed to formulate a preliminary conclusion there are no сhandlers in Ufa now. The most popular luxury brands for the Moscow сhandlers and specifics of their consumption were determined. This research is the first descriptive step to understanding the specifics of contemporary сhandlers — how they manage to consume luxury in the form of material artefacts and services, while being kept on a shoestring budget. The research entails a few limitations. The investigation comprised only a limited numbers of the respondents from Russian cities as Moscow and Ufa. In future, more consumers will be involved in the sample to cover more cities in Russia and respondents from other countries will be included. Upon the research completion a range of the recommendations has been provided to the luxury producers whose brands are already presented in Moscow and also for those who are planning to open their stores there. The results may serve as a guide for marketing tools development in the luxury industry. The originality of the paper lies in the term “chandlers’ segment” which is introduced in marketing theory for the first time

Interaction between the beta-cell and the immune system in type 1 diabetes: role for post-translational modifications

Diabetes mellitus is one of the most common endocrine diseases in the world and the incidence is still increasing rapidly. Clinical characteristic of diabetes include hyperglycemia and glucosuria, as a result of relative or absolute shortage in insulin. This is the hormone secreted by the beta-cell in the islets of Langerhans upon elevated blood glucose concentrations after a meal. Where the most prevalent type, T2D, is rather considered as a metabolic disease involving insulin resistance and beta-cell dysfunction, T1D, accounting for 5-10% of all diabetic patients, is an autoimmune disease where the body’s own immune system attacks the insulin-secreting pancreatic beta-cells. The mechanisms responsible for loss of tolerance against the beta-cells are not yet completely understood. The immune system is supposed to be of major importance, but more and more evidence point to the beta-cells themselves as active partners in their own destruction. Aspecific inflammation in the islets, indicated as the first trigger for T1D, results in upregulation of HLA-I molecules on the surface and release of chemokines and cytokines. In addition, ER and oxidative stress are induced, resulting in beta-cell dysfunction, apoptosis and the generation of molecular changes like alternative splicing and PTMs. This PhD project, with the general objective to study how the interaction between the beta-cell and immune system participates in the development of T1D, put specifically the importance of PTMs of beta-cell antigens in the spotlight. In the first project (Chapter 3) we investigated if at early age before onset of insulitis, there are differences in islets of Langerhans from NOD mice compared to two healthy mouse strains namely the NOR mice, showing 88% sequence similarity with NOD mice, and the more distant C57Bl/6 mice, that could potentially contribute to an intrinsic higher risk for auto-immune attack or dysfunction. Analysis of the transcriptome and proteome, combined with integrated pathway and network analyses, indicated that islets of NOD mice are subjected to higher levels of stress due to an inefficient supply of energy and by a higher probability that misfolded proteins will accumulate, mainly due to lower expression of PDIA3, PDIA4 and PDIA6, enzymes implicated in S-S bond formation. However, the most remarkable finding in NOD islets at this early pre-insulitic age was the high expression of Padi2 mRNA. Padi2 is one of the five Ca2+ dependent enzymes responsible for the modification of arginine to citrulline, known as citrullination. This modification that highly impacts protein conformation and HLA binding, is known to be implicated in the generation of autoantigens is several autoimmune diseases, most importantly RA, but also in T1D citrullination of GAD65 results in autoantigen generation. In order to examine both aspects of the interaction between the beta-cell and immune system, the aim of the second project (Chapter 4) was to investigate how inflammation affects the beta-cell proteome resulting in an active contribution to T1D development. We build further on a previous finding from our lab that demonstrated PTM of GRP78 in a rat beta-cell line (INS-1E) upon exposure to pro-inflammatory cytokines, a model that is used to mimic T1D ex-vivo. Further, we characterized this PTM as a citrullination on arginine 510 of GRP78. In addition, it was also shown that cytokines induce the translocation of GRP78 from the ER to the plasma-membrane of INS-1E cells and mouse islets, a process mediated by ER stress. While intracellularly we identified 3 isoforms of GRP78, much more modified isoforms of GRP78 were expressed on the cell surface. Finally, citrullination of GRP78 results in loss of immune tolerance in diabetic NOD mice by the presence of autoantibodies and auto-reactive T-cells. The aim of the third project (Chapter 5) was to translate these findings from INS-1E cells and NOD mice to the human situation. This pointed to a similar PTM of GRP78 in human islets exposed to pro-inflammatory cytokines in three out of five healthy donors. Furthermore, proteome analysis by LC-MS/MS indicated that inflammation in general induced citrullination and deamidation, another PTM known to be involved in autoantigen generation. The identification of two citrullinated and deamidated peptides of GRP78 showed evidence for the implication of these PTMs in human islets as well. To investigate the relevance in terms of autoantigen recognition, modified GRP78 epitopes were designed that were predicted to bind to the T1D susceptibility HLA-DR4 molecule and these peptides were further on used in immunological assays. The first indication for the implication of citrullinated GRP78 as autoantigen in human T1D patients came from the presence of reactive CD4+ T-cells in infiltrated T1D islets. Next, higher CD4+ T-cell frequencies recognizing a citrullinated epitope were also present in peripheral blood of T1D patients compared to healthy controls, indicating a possible application as biomarker for T1D. To conclude, this PhD project clearly demonstrated the importance of the interaction that connects beta-cells and immune system in the pathogenesis of T1D. PTMs of beta-cell antigens, especially citrullination, appeared to have substantial importance for the break of tolerance. Furthermore, the ability to detect autoreactive T-cells against citrullinated GRP78 in blood of NOD mice and T1D patients emphasizes its possible use as a biomarker and opens the road to the development of new therapeutic applications.Table of contents Dankwoord - Acknowledgements iii List of abbreviations ix Chapter 1 Introduction 1 1. Diabetes Mellitus 2 1.1. Types of diabetes 2 1.2. Pathogenesis of type 1 diabetes (T1D) 3 2. Autoimmunity: break of tolerance against autoantigens 3 2.1. The immune system 3 2.2. Risk factors for T1D 6 2.3. Break of tolerance against autoantigens: different theories 7 3. The beta-cell in T1D: from victim to culprit 8 3.1. Models to study the beta-cell 8 3.2. How does the beta-cell die in T1D? 9 4. Post-translational modifications (PTMs) 12 4.1. Physiological functions of PTMs in the cell 12 4.2. Generation of PTMs upon cellular stress 13 4.3. PTMs as a mechanism for autoantigen generation 14 4.4. Post-translationally modified autoantigens in T1D 16 4.5. Citrullination, one form of PTM 20 4.5.1. PAD enzymes 20 4.5.2. Citrullination in autoimmune diseases 21 5. GRP78: role in health and disease 23 5.1. Endoplasmic reticulum chaperone with multiple functions 23 5.2. GRP78: a protein involved in several diseases 25 Chapter 2 Aims and objectives 29 Chapter 3 Early differences in islets from prediabetic NOD mice: combined microarray and proteomic analysis 33 Abstract 35 Introduction 36 Materials and Methods 36 Results 38 Discussion 57 Supplementary data 62 Chapter 4 Citrullinated GRP78 is an autoantigen in type 1 diabetes 81 Abstract 83 Introduction 84 Materials and Methods 85 Results 87 Discussion 99 Supplementary data 103 Chapter 5 PTM of GRP78 in human islets of Langerhans generates autoreactive T-cells against citrullinated epitopes 109 Abstract 111 Introduction 112 Materials and Methods 113 Results 116 Discussion 128 Supplementary data 133 Chapter 6 General discussion and future perspectives 151 Chapter 7 Summary 161 Chapter 8 Samenvatting 167 Chapter 6 References 173 Curriculum Vitae 195nrpages: 222status: publishe

The beta-cell in type 1 diabetes: What have we learned from proteomic studies?

Pancreatic beta-cells have a crucial role in the regulation of blood glucose homeostasis by the production and secretion of insulin. In type 1 diabetes (T1D), an autoimmune reaction against the beta-cells together with the presence of inflammatory cytokines and ROS in the islets leads to beta-cell dysfunction and death. This review gives an overview of proteomic studies that lead to better understanding of beta-cell functioning in T1D. Protein profiling of isolated islets and beta-cell lines in health and T1D contributed to the unraveling of pathways involved in cytokine-induced cell death. In addition, by studying the serological proteome of T1D patients, new biomarkers and beta-cell autoantigens were discovered, which may improve screening tests and follow-up of T1D development. Interestingly, an important role for PTMs was demonstrated in the generation of beta-cell autoantigens. To conclude, proteomic techniques are of indispensable value to improve the knowledge on beta-cell function in T1D and the search toward therapeutic targets.status: publishe

Understanding type 1 diabetes through proteomics

Auto-immunity against pancreatic beta-cells leads to an absolute shortage of the hormone insulin, resulting in hyperglycemia and the onset of type 1 diabetes (T1D). Proteomic approaches have been used to elucidate the mechanisms of beta-cell dysfunction and death. Areas covered: In the present review, we discuss discoveries in the beta-cell proteome that have contributed to better insights in the role of the beta-cell in T1D. Techniques, such as 2D-DIGE and MALDI imaging, together with new approaches for sample preparation, including laser capture microdissection and immunopeptidomics, have resulted in novel mechanistic insights in the pathogenesis of T1D. We describe how proteomic studies in beta-cell lines as well as isolated islets from animal models and humans have discovered intracellular signaling pathways leading to beta-cell destruction, the generation of neo-antigens through post-translational modifications of beta-cell antigens as well as better biomarkers of disease progression. Expert commentary: Proteomics has contributed to the discovery of beta-cell neo-autoantigen generation through post-translational modifications, hybrid insulin peptide formation and the generation of defective ribosomal gene products. These concepts are revolutionizing our insights in the pathogenesis of T1D, acknowledging a central role for the beta-cell in its own destruction.status: publishe

A proteomic study of the regulatory role for STAT-1 in cytokine-induced beta-cell death

Signal transducer and activator of transcription 1 (STAT-1) plays a crucial role in cytokine-induced beta-cell destruction. However, its precise downstream pathways have not been completely clarified. We performed a proteome analysis of cytokine-exposed C57Bl/6 and STAT-1(-/-) mouse islets and prioritized proteins for their potential in relation to type 1 diabetes (T1D).status: publishe

Cytokine-induced translocation of GRP78 to the plasma membrane triggers a pro-apoptotic feedback loop in pancreatic beta cells

The 78-kDa glucose-regulated protein (GRP78) is an ubiquitously expressed endoplasmic reticulum chaperone, with a central role in maintaining protein homeostasis. Recently, an alternative role for GRP78 under stress conditions has been proposed, with stress-induced extracellular secretion and translocation of GRP78 to the cell surface where it acts as a multifunctional signaling receptor. Here we demonstrate translocation of GRP78 to the surface of human EndoC-βH1 cells and primary human islets upon cytokine exposure, in analogy to observations in rodent INS-1E and MIN6 beta cell lines. We show that GRP78 is shuttled via the anterograde secretory pathway, through the Golgi complex and secretory granules, and identify the DNAJ homolog subfamily C member 3 (DNAJC3) as a GRP78-interacting protein that facilitates its membrane translocation. Evaluation of downstream signaling pathways, using N- and C-terminal anti-GRP78 blocking antibodies, demonstrates that both GRP78 signaling domains initiate pro-apoptotic signaling cascades in beta cells. Extracellular GRP78 itself is identified as a ligand for cell surface GRP78 (sGRP78), increasing caspase 3/7 activity and cell death upon binding, which is accompanied by enhanced Chop and Bax mRNA expression. These results suggest that inflammatory cytokines induce a self-destructive pro-apoptotic feedback loop through the secretion and membrane translocation of GRP78. This proapoptotic function distinguishes the role of sGRP78 in beta cells from its reported anti-apoptotic and proliferative role in cancer cells, opening the road for the use of compounds that block sGRP78 as potential beta cell-preserving therapies in type 1 diabetes.status: Published onlin

Cytokine-induced translocation of GRP78 to the plasma membrane triggers a pro-apoptotic feedback loop in pancreatic beta cells

The 78-kDa glucose-regulated protein (GRP78) is an ubiquitously expressed endoplasmic reticulum chaperone, with a central role in maintaining protein homeostasis. Recently, an alternative role for GRP78 under stress conditions has been proposed, with stress-induced extracellular secretion and translocation of GRP78 to the cell surface where it acts as a multifunctional signaling receptor. Here we demonstrate translocation of GRP78 to the surface of human EndoC-βH1 cells and primary human islets upon cytokine exposure, in analogy to observations in rodent INS-1E and MIN6 beta cell lines. We show that GRP78 is shuttled via the anterograde secretory pathway, through the Golgi complex and secretory granules, and identify the DNAJ homolog subfamily C member 3 (DNAJC3) as a GRP78-interacting protein that facilitates its membrane translocation. Evaluation of downstream signaling pathways, using N- and C-terminal anti-GRP78 blocking antibodies, demonstrates that both GRP78 signaling domains initiate pro-apoptotic signaling cascades in beta cells. Extracellular GRP78 itself is identified as a ligand for cell surface GRP78 (sGRP78), increasing caspase 3/7 activity and cell death upon binding, which is accompanied by enhanced Chop and Bax mRNA expression. These results suggest that inflammatory cytokines induce a self-destructive pro-apoptotic feedback loop through the secretion and membrane translocation of GRP78. This proapoptotic function distinguishes the role of sGRP78 in beta cells from its reported anti-apoptotic and proliferative role in cancer cells, opening the road for the use of compounds that block sGRP78 as potential beta cell-preserving therapies in type 1 diabetes.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Citrullinated glucose-regulated protein 78 is an autoantigen in type 1 diabetes

Post-translational modifications of self-proteins play a substantial role in the initiation or propagation of the autoimmune attack in several autoimmune diseases, but their contribution to type 1 diabetes is only recently emerging. In the present study we demonstrate that inflammatory stress, induced by the cytokines IL-1β and IFNγ, leads to citrullination of GRP78 in beta-cells. This is coupled with translocation of this endoplasmic reticulum chaperone to the beta-cell plasma membrane and subsequent secretion. Importantly, expression and activity of peptidylarginine deiminase 2, one of the 5 enzymes responsible for citrullination and a candidate gene for type 1 diabetes in mice, is increased in islets from diabetes-prone NOD mice. Finally, (pre-)diabetic NOD mice have autoantibodies and effector T-cells that react against citrullinated GRP78, indicating that inflammation-induced citrullination of GRP78 in beta-cells generates a novel autoantigen in type 1 diabetes, opening new avenues for biomarker development and therapeutic intervention.status: publishe

Foodborne cereulide causes beta cell dysfunction and apoptosis.

status: publishe

Citrullinated glucose-regulated protein 78 is an autoantigen in type 1 diabetes

Posttranslational modifications of self-proteins play a substantial role in the initiation or propagation of the autoimmune attack in several autoimmune diseases, but their contribution to type 1 diabetes is only recently emerging. In the current study, we demonstrate that inflammatory stress, induced by the cytokines interleukin-1β and interferon-γ, leads to citrullination of GRP78 in β-cells. This is coupled with translocation of this endoplasmic reticulum chaperone to the β-cell plasma membrane and subsequent secretion. Importantly, expression and activity of peptidylarginine deiminase 2, one of the five enzymes responsible for citrullination and a candidate gene for type 1 diabetes in mice, is increased in islets from diabetes-prone nonobese diabetic (NOD) mice. Finally, (pre)diabetic NOD mice have autoantibodies and effector T cells that react against citrullinated GRP78, indicating that inflammation-induced citrullination of GRP78 in β-cells generates a novel autoantigen in type 1 diabetes, opening new avenues for biomarker development and therapeutic intervention.SCOPUS: ar.jinfo:eu-repo/semantics/publishe