HLA class II induction in human islet cells by interferon-gamma plus tumour necrosis factor or lymphotoxin

Targeting of Non-Classical Human Leukocyte Antigens as Novel Therapeutic Strategies in Cancer

Human leukocyte antigens (HLAs) are essential regulators of immune responses against cancer, with classical HLAs well-documented for their role in tumor recognition and immune surveillance. In recent years, non-classical HLAs-including HLA-E, HLA-F, HLA-G, and HLA-H-have emerged as critical players in the immune landscape of cancer due to their diverse and less conventional functions in immune modulation. These molecules exhibit unique mechanisms that enable tumors to escape immune detection, promote tumor progression, and contribute to therapeutic resistance. This review provides a comprehensive examination of the current understanding of non-classical HLAs in solid cancers, focusing on their specific roles in shaping the tumor microenvironment and influencing immune responses. By analyzing how HLA-E, HLA-F, HLA-G, and HLA-H modulate interactions with immune cells, such as T cells, natural killer cells, and antigen-presenting cells, we highlight key pathways through which these molecules contribute to immune evasion and metastasis. Additionally, we review promising therapeutic strategies aimed at targeting non-classical HLAs, including emerging immunotherapies that could potentially enhance cancer treatment outcomes by reversing immune suppression within tumors. Understanding the influence of these non-classical HLAs in solid cancers may offer new insights into cancer immunology and may lead to the development of innovative and more effective immunotherapeutic approaches. This review underscores the importance of non-classical HLAs as potential therapeutic targets, providing a necessary foundation for future studies in the evolving field of cancer immunotherapy.

Repositioning the Early Pathology of Type 1 Diabetes to the Extraislet Vasculature

Type 1 diabetes (T1D) is a prototypic T cell-mediated autoimmune disease. Because the islets of Langerhans are insulated from blood vessels by a double basement membrane and lack detectable lymphatic drainage, interactions between endocrine and circulating T cells are not permitted. Thus, we hypothesized that initiation and progression of anti-islet immunity required islet neolymphangiogenesis to allow T cell access to the islet. Combining microscopy and single cell approaches, the timing of this phenomenon in mice was situated between 5 and 8 wk of age when activated anti-insulin CD4 T cells became detectable in peripheral blood while peri-islet pathology developed. This "peri-insulitis," dominated by CD4 T cells, respected the islet basement membrane and was limited on the outside by lymphatic endothelial cells that gave it the attributes of a tertiary lymphoid structure. As in most tissues, lymphangiogenesis seemed to be secondary to local segmental endothelial inflammation at the collecting postcapillary venule. In addition to classic markers of inflammation such as CD29, V-CAM, and NOS, MHC class II molecules were expressed by nonhematopoietic cells in the same location both in mouse and human islets. This CD45- MHC class II+ cell population was capable of spontaneously presenting islet Ags to CD4 T cells. Altogether, these observations favor an alternative model for the initiation of T1D, outside of the islet, in which a vascular-associated cell appears to be an important MHC class II-expressing and -presenting cell.

Medication-Related Osteonecrosis of the Jaw: A Case Report of an Unusual Side Effect of Adalimumab

Background

Medication-related osteonecrosis of the jaw (MRONJ) is a serious adverse drug reaction characterized by progressive bone destruction and necrosis of mandibular and/or maxillary jaw bone that occurs in patients undergoing treatments with antiresorptive drugs such as bisphosphonates or denosumab, antiangiogenic agents such as bevacizumab, or other kinds of monoclonal antibodies such as rituximab and ipilimumab, for different oncologic and nononcologic diseases. The aim of this study was to report a case of MRONJ in a patient affected by rheumatoid arthritis disease in treatment with adalimumab. Case Presentation. A 70-year-old female patient affected by rheumatoid arthritis (RA), who had been undergoing adalimumab (40 mg subcutaneous injection) every two weeks for 5 years, with no history of antiresorptive or antiangiogenic agent administration, came to our attention for intraoral necrotic bone exposures of the anterior mandible. After drug withdrawal and antibiotic cycles, the patient underwent surgical treatment with bone resection and debridement of necrotic tissues. After an observation period of 8 months, a complete healing without signs of recurrence was detected.

Conclusions

Based on this study, a correlation between adalimumab and MRONJ is possible. Therefore, we believe that an oral cavity examination should be done in every patients, before starting therapy with adalimumab, to possibly avoid MRONJ onset. Further studies are required to confirm the role of adalimumab in MRONJ.

The beta cell-immune cell interface in type 1 diabetes (T1D)

BACKGROUND

T1D is an autoimmune disease in which pancreatic islets of Langerhans are infiltrated by immune cells resulting in the specific destruction of insulin-producing islet beta cells. Our understanding of the factors leading to islet infiltration and the interplay of the immune cells with target beta cells is incomplete, especially in human disease. While murine models of T1D have provided crucial information for both beta cell and autoimmune cell function, the translation of successful therapies in the murine model to human disease has been a challenge.

SCOPE OF REVIEW

Here, we discuss current state of the art and consider knowledge gaps concerning the interface of the islet beta cell with immune infiltrates, with a focus on T cells. We discuss pancreatic and immune cell phenotypes and their impact on cell function in health and disease, which we deem important to investigate further to attain a more comprehensive understanding of human T1D disease etiology.

MAJOR CONCLUSIONS

The last years have seen accelerated development of approaches that allow comprehensive study of human T1D. Critically, recent studies have contributed to our revised understanding that the pancreatic beta cell assumes an active role, rather than a passive position, during autoimmune disease progression. The T cell-beta cell interface is a critical axis that dictates beta cell fate and shapes autoimmune responses. This includes the state of the beta cell after processing internal and external cues (e.g., stress, inflammation, genetic risk) that that contributes to the breaking of tolerance by hyperexpression of human leukocyte antigen (HLA) class I with presentation of native and neoepitopes and secretion of chemotactic factors to attract immune cells. We anticipate that emerging insights about the molecular and cellular aspects of disease initiation and progression processes will catalyze the development of novel and innovative intervention points to provide additional therapies to individuals affected by T1D.

Single cell transcriptomic analysis of Graves' disease thyroid glands reveals the broad immunoregulatory potential of thyroid follicular and stromal cells and implies a major re-interpretation of the role of aberrant HLA class II expression in autoimmunity

The study of the immune response in thyroid autoimmunity has been mostly focused on the autoantibodies and lymphocytes, but there are indications that intrinsic features of thyroid tissue cells may play a role in disrupting tolerance that needs further investigation. The overexpression of HLA and adhesion molecules by thyroid follicular cells (TFC) and our recent demonstration that PD-L1 is also moderately expressed by TFCs in autoimmune thyroid indicates that TFCs they may activate but also inhibit the autoimmune response. Intriguingly, we have recently found that in vitro cultured TFCs are able to suppress the proliferation of autologous lymphocyte T in a contact-dependent manner which is independent of the PD-1/PD-L1 signaling pathway. To get a more comprehensive picture of TFC activating and inhibitory molecules/pathways driving the autoimmune response in the thyroid glands, preparations of TFCs and stromal cells from five Graves' disease (GD) and four control thyroid glands were compared by scRNA-seq. The results confirmed the previously described interferon type I and type II signatures in GD TFCs and showed unequivocally that they express the full array of genes that intervene in the processing and presentation of endogenous and exogeneous antigens. GD TFCs lack however expression of costimulatory molecules CD80 and CD86 required for priming T cells. A moderate overexpression of CD40 by TFCs was confirmed. GD Fibroblasts showed widespread upregulation of cytokine genes. The results from this first single transcriptomic profiling of TFC and thyroid stromal cells provides a more granular view of the events occurring in GD. The new data point at an important contribution of stromal cells and prompt a major re-interpretation of the role of MHC over-expression by TFC, from deleterious to protective. Most importantly this re-interpretation could also apply to other tissues, like pancreatic beta cells, where MHC over-expression has been detected in diabetic pancreas.

CD4+ Cytotoxic T Cells Involved in the Development of EBV-Associated Diseases

Activated cytotoxic CD4 T cells (HLA-DR+) play an important role in the control of EBV infection, especially in cells with latency I (EBNA-1). One of the evasion mechanisms of these latency cells is generated by gp42, which, via peripherally binding to the β1 domain of the β chain of MHC class II (HLA-DQ, -DR, and -DP) of the infected B lymphocyte, can block/alter the HLA class II/T-cell receptor (TCR) interaction, and confer an increased level of susceptibility towards the development of EBV-associated autoimmune diseases or cancer in genetically predisposed individuals (HLA-DRB1* and DQB1* alleles). The main developments predisposing the factors of these diseases are: EBV infection; HLA class II risk alleles; sex; and tissue that is infiltrated with EBV-latent cells, forming ectopic lymphoid structures. Therefore, there is a need to identify treatments for eliminating cells with EBV latency, because the current treatments (e.g., antivirals and rituximab) are ineffective.

Lymphotoxins Serve as a Novel Orchestrator in T1D Pathogenesis

Type 1 diabetes (T1D) stems from pancreatic β cell destruction by islet reactive immune cells. Similar as other autoimmune disorders, there is no curative remedy for T1D thus far. Chronic insulitis is the hallmark of T1D, which creates a local inflammatory microenvironment that impairs β cell function and ultimately leads to β cell death. Immune regulation shows promise in T1D treatment by providing a time window for β cell recovery. However, due to the complex nature of T1D pathogenesis, the therapeutic effect of immune regulation is often short-lasting and unsatisfying in monotherapies. Lymphotoxins (LTs) were first identified in 1960s as the lymphocyte-producing cytokine that can kill other cell types. As a biological cousin of tumor necrosis factor alpha (TNFα), LTs play unique roles in T1D development. Herein in this review, we summarized the advancements of LTs in T1D pathogenesis. We particularly highlighted their effect on the formation of peri-islet tertiary lymphoid organs (TLOs), and discussed their synergistic effect with other cytokines on β cell toxicity and autoimmune progression. Given the complex and dynamic crosstalk between immune cells and β cells in T1D setting, blockade of lymphotoxin signaling applied to the existing therapies could be an efficient approach to delay or even reverse the established T1D.

Upregulation of HLA class II in pancreatic beta cells from organ donors with type 1 diabetes

AIMS/HYPOTHESIS

We aimed to characterise and quantify the expression of HLA class II (HLA-II) in human pancreatic tissue sections and to analyse its induction in human islets.

METHODS

We immunostained human pancreatic tissue sections from non-diabetic (n = 5), autoantibody positive (Aab+; n = 5), and type 1 diabetic (n = 5) donors, obtained from the Network of Pancreatic Organ Donors (nPOD), with HLA-II, CD68 and insulin. Each tissue section was acquired with a widefield slide scanner and then analysed with QuPath software. In total, we analysed 7415 islets that contained 338,480 cells. Widefield microscopy was further complemented by high resolution imaging of 301 randomly selected islets, acquired using a Zeiss laser scanning confocal (LSM880) to confirm our findings. Selected beta cells were acquired in enhanced resolution using LSM880 with an Airyscan detector. Further, we cultured healthy isolated human islets and reaggregated human islet microtissues with varying concentrations of proinflammatory cytokines (IFN-γ, TNF-α and IL-1β). After proinflammatory cytokine culture, islet function was measured by glucose-stimulated insulin secretion, and HLA-I and HLA-II expression was subsequently evaluated with immunostaining or RNA sequencing.

RESULTS

Insulin-containing islets (ICIs) of donors with type 1 diabetes had a higher percentage of HLA-II positive area (24.31%) compared with type 1 diabetic insulin-deficient islets (IDIs, 0.67%), non-diabetic (3.80%), and Aab+ (2.31%) donors. In ICIs of type 1 diabetic donors, 45.89% of the total insulin signal co-localised with HLA-II, and 27.65% of the islet beta cells expressed both HLA-II and insulin, while in non-diabetic and Aab+ donors 0.96% and 0.59% of the islet beta cells, respectively, expressed both markers. In the beta cells of donors with type 1 diabetes, HLA-II was mostly present in the cell cytoplasm, co-localising with insulin. In the experiments with human isolated islets and reaggregated human islets, we observed changes in insulin secretion upon stimulation with proinflammatory cytokines, as well as higher expression of HLA-II and HLA-I when compared with controls cultured with media, and an upregulation of HLA-I and HLA-II RNA transcripts.

CONCLUSIONS/INTERPRETATION

After a long-standing controversy, we provide definitive evidence that HLA-II can be expressed by pancreatic beta cells from patients with type 1 diabetes. Furthermore, this upregulation can be induced in vitro in healthy isolated human islets or reaggregated human islets by treatment with proinflammatory cytokines. Our findings support a role for HLA-II in type 1 diabetes pathogenesis since HLA-II expressing beta cells can potentially become a direct target of autoreactive CD4+ lymphocytes.

Selective deletion of human leukocyte antigens protects stem cell-derived islets from immune rejection

Stem cell-based replacement therapies hold the promise to restore function of damaged or degenerated tissue such as the pancreatic islets in people with type 1 diabetes. Wide application of these therapies requires overcoming the fundamental roadblock of immune rejection. To address this issue, we use genetic engineering to create human pluripotent stem cells (hPSCs) in which the majority of the polymorphic human leukocyte antigens (HLAs), the main drivers of allogeneic rejection, are deleted. We retain the common HLA class I allele HLA-A2 and less polymorphic HLA-E/F/G to allow immune surveillance and inhibition of natural killer (NK) cells. We employ a combination of in vitro assays and humanized mouse models to demonstrate that these gene manipulations significantly reduce NK cell activity and T-cell-mediated alloimmune response against hPSC-derived islet cells. In summary, our approach produces hypoimmunogenic hPSCs that can be readily matched with recipients to avoid alloimmune rejection.

Revisiting the Antigen-Presenting Function of β Cells in T1D Pathogenesis

Type 1 diabetes (T1D) is characterized by the unresolved autoimmune inflammation and islet β cell destruction. The islet resident antigen-presenting cells (APCs) including dendritic cells and macrophages uptake and process the β cell-derived antigens to prime the autoreactive diabetogenic T cells. Upon activation, those autoreactive T cells produce copious amount of IFN-γ, TNF-α and IL-1β to induce β cell stress and death. Autoimmune attack and β cell damage intertwine together to push forward this self-destructive program, leading to T1D onset. However, β cells are far beyond a passive participant during the course of T1D development. Herein in this review, we summarized how β cells are actively involved in the initiation of autoimmune responses in T1D setting. Specifically, β cells produce modified neoantigens under stressed condition, which is coupled with upregulated expression of MHC I/II and co-stimulatory molecules as well as other immune modules, that are essential properties normally exhibited by the professional APCs. At the cellular level, this subset of APC-like β cells dynamically interacts with plasmacytoid dendritic cells (pDCs) and manifests potency to activate autoreactive CD4 and CD8 T cells, by which β cells initiate early autoimmune responses predisposing to T1D development. Overall, the antigen-presenting function of β cells helps to explain the tissue specificity of T1D and highlights the active roles of structural cells played in the pathogenesis of various immune related disorders.

HLA DR Genome Editing with TALENs in Human iPSCs Produced Immune-Tolerant Dendritic Cells

Although human induced pluripotent stem cells (iPSCs) can serve as a universal cell source for regenerative medicine, the use of iPSCs in clinical applications is limited by prohibitive costs and prolonged generation time. Moreover, allogeneic iPSC transplantation requires preclusion of mismatches between the donor and recipient human leukocyte antigen (HLA). We, therefore, generated universally compatible immune nonresponsive human iPSCs by gene editing. Transcription activator-like effector nucleases (TALENs) were designed for selective elimination of HLA DR expression. The engineered nucleases completely disrupted the expression of HLA DR on human dermal fibroblast cells (HDF) that did not express HLA DR even after stimulation with IFN-γ. Teratomas formed by HLA DR knockout iPSCs did not express HLA DR, and dendritic cells differentiated from HLA DR knockout iPSCs reduced CD4⁺ T cell activation. These engineered iPSCs might provide a novel translational approach to treat multiple recipients from a limited number of cell donors.

Identification of Critical Transcriptomic Signaling Pathways in Patients with H Syndrome and Rosai-Dorfman Disease

Biallelic mutations in SLC29A3 cause histiocytosis-lymphadenopathy plus syndrome, also known as H syndrome (HS). HS is a complex disorder, with ~ 25% of patients developing autoinflammatory complications consisting of unexplained fevers, persistently elevated inflammatory markers, and unusual lymphadenopathies, with infiltrating CD68⁺, S100⁺, and CD1a^- histiocytes, resembling the immunophenotype found in Rosai-Dorfman disease (RDD). We investigated the transcriptomic profiles of monocytes, non-activated (M0), classically activated (M1), and alternatively activated macrophages (M2) in two patients with HS, one without autoinflammatory (HS1) and one with autoinflammatory complications (HS2). RNA sequencing revealed a dysregulated transcriptomic profile in both HS patients compared to healthy controls (HC). HS2, when compared to HS1, had several differentially expressed genes, including genes associated with lymphocytic-histiocytic predominance (e.g. NINL) and chronic immune activation (e.g. B2M). The transcriptomic and cytokine profiles of HS patients were comparable to patients with SAID with high levels of TNF. SERPINA1 gene expression was found to be upregulated in all patients studied. Moreover, higher levels of IFNγ were found in the serum of both HS patients when compared to HC. Gene ontology (GO) enrichment analysis of the DEGs in HS patients revealed the terms "type I IFN," "IFNγ signaling pathway," and "immune responses" as the top 3 most significant terms for monocytes. Gene expression analysis of lymph node biopsies from sporadic and H syndrome-associated RDD suggests common underlying pathological process. In conclusion, monocytes and macrophages from both HS patients showed transcriptomic profiles similar to SAIDs and also uniquely upregulated IFNγ signature. These findings may help find better therapeutic options for this rare disorder.

Macrophage Depletion Improves Chronic Rejection in Rats With Allograft Heart Transplantation

BACKGROUND

Macrophages may be important in chronic rejection after organ transplantation. This study aimed to investigate the possibility of depleting macrophages for a certain amount of time to alleviate chronic rejection in a heart transplant model of Fischer to Lewis rats.

METHODS

Clodronate liposome was injected abdominally to deplete macrophages for 2 time frames. The expression levels of ectodysplasin 1, arginase 1 (Arg1), chitinase-like lectin (Ym1), interferon gamma, tumor necrosis factor α (TNF-α), smooth muscle α-actin (α-SMA), monocyte chemoattractant protein 1 (MCP-1), and interleukin 10 (IL-10) were detected.

RESULTS

1. The expression levels of α-SMA, interferon gamma, TNF-α, and MCP-1 and the transformation of peripheral T cells were lower after macrophage depletion for 2 or 4 weeks. 2. The expression levels of α-SMA, TNF-α, and MCP-1 and the transformation of peripheral T cells were even lower after 4 weeks compared with 2 weeks, except for interferon gamma. 3. A higher level of expression of Arg1 and Ym1 after macrophage depletion for 2 weeks was observed. 4. A higher level of expression of IL-10 after macrophage depletion for 2 weeks, but not 4 weeks, was also observed.

CONCLUSIONS

Macrophage clearance after heart transplantation alleviated chronic rejection probably via M2 polarization of regenerated macrophages, reduced T-lymphocyte proliferation, and changed the expression levels of interferon gamma, TNF-α, MCP-1, and IL-10.

What the HLA-I!-Classical and Non-classical HLA Class I and Their Potential Roles in Type 1 Diabetes

PURPOSE OF REVIEW

Hyperexpression of classical HLA class I (HLA-I) molecules in insulin-containing islets has become a widely accepted hallmark of type 1 diabetes pathology. In comparison, relatively little is known about the expression, function and role of non-classical subtypes of HLA-I. This review focuses on the current understanding of the non-classical HLA-I subtypes: HLA-E, HLA-F and HLA-G, within and outside the field of type 1 diabetes, and considers the possible impacts of these molecules on disease etiology.

RECENT FINDINGS

Evidence is growing to suggest that non-classical HLA-I proteins are upregulated, both at the RNA and protein levels in the pancreas of individuals with recent-onset type 1 diabetes. Moreover, associations between non-classical HLA-I genotypes and age at onset of type 1 diabetes have been reported in some studies. As with classical HLA-I, it is likely that hyperexpression of non-classical HLA-I is driven by the release of diffusible interferons by stressed β cells (potentially driven by viral infection) and exacerbated by release of cytokines from infiltrating immune cells. Non-classical HLA-I proteins predominantly (but not exclusively) transduce negative signals to immune cells infiltrating at the site of injury/inflammation. We propose a model in which the islet endocrine cells, through expression of non-classical HLA-I are fighting back against the infiltrating immune cells. By inhibiting the activity and function on NK, B and select T cells, the non-classical HLA-I, proteins will reduce the non-specific bystander effects of inflammation, while at the same time still allowing the targeted destruction of β cells by specific islet-reactive CD8+ T cells.

Stem Cell Therapies for Treating Diabetes: Progress and Remaining Challenges

Restoration of insulin independence and normoglycemia has been the overarching goal in diabetes research and therapy. While whole-organ and islet transplantation have become gold-standard procedures in achieving glucose control in diabetic patients, the profound lack of suitable donor tissues severely hampers the broad application of these therapies. Here, we describe current efforts aimed at generating a sustainable source of functional human stem cell-derived insulin-producing islet cells for cell transplantation and present state-of-the-art efforts to protect such cells via immune modulation and encapsulation strategies.

Position β57 of I-Ag7 controls early anti-insulin responses in NOD mice, linking an MHC susceptibility allele to type 1 diabetes onset

The class II region of the major histocompatibility complex (MHC) locus is the main contributor to the genetic susceptibility to type 1 diabetes (T1D). The loss of an aspartic acid at position 57 of diabetogenic HLA-DQβ chains supports this association; this single amino acid change influences how TCRs recognize peptides in the context of HLA-DQ8 and I-Ag7 using a mechanism termed the P9 switch. Here, we built register-specific insulin peptide MHC tetramers to examine CD4+ T cell responses to Ins12-20 and Ins13-21 peptides during the early prediabetic phase of disease in nonobese diabetic (NOD) mice. A single-cell analysis of anti-insulin CD4+ T cells performed in 6- and 12-week-old NOD mice revealed tissue-specific gene expression signatures. TCR signaling and clonal expansion were found only in the islets of Langerhans and produced either classical TH1 differentiation or an unusual Treg phenotype, independent of TCR usage. The early phase of the anti-insulin response was dominated by T cells specific for Ins12-20, the register that supports a P9 switch mode of recognition. The presence of the P9 switch was demonstrated by TCR sequencing, reexpression, mutagenesis, and functional testing of TCRαβ pairs in vitro. Genetic correction of the I-Aβ57 mutation in NOD mice resulted in the disappearance of D/E residues in the CDR3β of anti-Ins12-20 T cells. These results provide a mechanistic molecular explanation that links the characteristic MHC class II polymorphism of T1D with the recognition of islet autoantigens and disease onset.

Extracellular Vesicles in Type 1 Diabetes: Messengers and Regulators

PURPOSE OF REVIEW

Theories about the pathogenesis of type 1 diabetes (T1D) refer to the potential of primary islet inflammatory signaling as a trigger for the loss of self-tolerance leading to disease onset. Emerging evidence suggests that extracellular vesicles (EV) may represent the missing link between inflammation and autoimmunity. Here, we review the evidence for a role of EV in the pathogenesis of T1D, as well as discuss their potential value in the clinical sphere, as biomarkers and therapeutic agents.

RECENT FINDINGS

EV derived from β cells are enriched in diabetogenic autoantigens and miRNAs that are selectively sorted and packaged. These EV play a pivotal role in antigen presentation and cell to cell communication leading to activation of autoimmune responses. Furthermore, recent evidence suggests the potential of EV as novel tools in clinical diagnostics and therapeutic interventions. In-depth analysis of EV cargo using modern multi-parametric technologies may be useful in enhancing our understanding of EV-mediated immune mechanisms and in identifying robust biomarkers and therapeutic strategies for T1D.

HLA Class II Antigen Processing and Presentation Pathway Components Demonstrated by Transcriptome and Protein Analyses of Islet β-Cells From Donors With Type 1 Diabetes

Type 1 diabetes studies consistently generate data showing islet β-cell dysfunction and T cell-mediated anti-β-cell-specific autoimmunity. To explore the pathogenesis, we interrogated the β-cell transcriptomes from donors with and without type 1 diabetes using both bulk-sorted and single β-cells. Consistent with immunohistological studies, β-cells from donors with type 1 diabetes displayed increased Class I transcripts and associated mRNA species. These β-cells also expressed mRNA for Class II and Class II antigen presentation pathway components, but lacked the macrophage marker CD68. Immunohistological study of three independent cohorts of donors with recent-onset type 1 diabetes showed Class II protein and its transcriptional regulator Class II MHC trans-activator protein expressed by a subset of insulin⁺CD68^- β-cells, specifically found in islets with lymphocytic infiltrates. β-Cell surface expression of HLA Class II was detected on a portion of CD45^-insulin⁺ β-cells from donors with type 1 diabetes by immunofluorescence and flow cytometry. Our data demonstrate that pancreatic β-cells from donors with type 1 diabetes express Class II molecules on selected cells with other key genes in those pathways and inflammation-associated genes. β-Cell expression of Class II molecules suggests that β-cells may interact directly with islet-infiltrating CD4⁺ T cells and may play an immunopathogenic role.

Sleeve Gastrectomy Induced Remission of Slowly Progressive Type 1 Diabetes in a Morbidly Obese Japanese Patient

The effects of bariatric/metabolic surgery on glycemic control in obese type 1 diabetic patients are controversial. We herein report a case of a morbidly obese 35-year-old woman who completely recovered from slowly progressive type 1 diabetes (SPIDDM) following laparoscopic sleeve gastrectomy. Preoperatively, her body mass index (BMI) was 49.8 kg/m² and hemoglobin A1c was 5.7% with intensive insulin therapy. Six months after bariatric/metabolic surgery, her BMI decreased to 33.2 kg/m² and her glycemic control was normal despite the discontinuation of all diabetic medicine. This case demonstrates the usefulness of bariatric/metabolic surgery for achieving glycemic control in morbidly obese patients with SPIDDM in Japan.

Dexamethasone during pregnancy impairs maternal pancreatic β-cell renewal during lactation

Pancreatic islets from pregnant rats develop a transitory increase in the pancreatic β-cell proliferation rate and mass. Increased apoptosis during early lactation contributes to the rapid reversal of those morphological changes. Exposure to synthetic glucocorticoids during pregnancy has been previously reported to impair insulin secretion, but its impacts on pancreatic islet morphological changes during pregnancy and lactation have not been described. To address this issue, we assessed the morphological and molecular characteristics of pancreatic islets from rats that underwent undisturbed pregnancy (CTL) or were treated with dexamethasone between the 14th and 19th days of pregnancy (DEX). Pancreatic islets were analyzed on the 20th day of pregnancy (P20) and on the 3rd, 8th, 14th and 21st days of lactation (L3, L8, L14 and L21, respectively). Pancreatic islets from CTL rats exhibited transitory increases in cellular proliferation and pancreatic β-cell mass at P20, which were reversed at L3, when a transitory increase in apoptosis was observed. This was followed by the appearance of morphological features of pancreatic islet neogenesis at L8. Islets from DEX rats did not demonstrate an increase in apoptosis at L3, which coincided with an increase in the expression of M2 macrophage markers relative to M1 macrophage and T lymphocyte markers. Islets from DEX rats also did not exhibit the morphological characteristics of pancreatic islet neogenesis at L8. Our data demonstrate that maternal pancreatic islets undergo a renewal process during lactation that is impaired by exposure to DEX during pregnancy.

Neutralization Versus Reinforcement of Proinflammatory Cytokines to Arrest Autoimmunity in Type 1 Diabetes

As physiological pathways of intercellular communication produced by all cells, cytokines are involved in the pathogenesis of inflammatory insulitis as well as pivotal mediators of immune homeostasis. Proinflammatory cytokines including interleukins, interferons, transforming growth factor-β, tumor necrosis factor-α, and nitric oxide promote destructive insulitis in type 1 diabetes through amplification of the autoimmune reaction, direct toxicity to β-cells, and sensitization of islets to apoptosis. The concept that neutralization of cytokines may be of therapeutic benefit has been tested in few clinical studies, which fell short of inducing sustained remission or achieving disease arrest. Therapeutic failure is explained by the redundant activities of individual cytokines and their combinations, which are rather dispensable in the process of destructive insulitis because other cytolytic pathways efficiently compensate their deficiency. Proinflammatory cytokines are less redundant in regulation of the inflammatory reaction, displaying protective effects through restriction of effector cell activity, reinforcement of suppressor cell function, and participation in islet recovery from injury. Our analysis suggests that the role of cytokines in immune homeostasis overrides their contribution to β-cell death and may be used as potent immunomodulatory agents for therapeutic purposes rather than neutralized.

Autoreactive T cells in type 1 diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease that causes severe loss of pancreatic β cells. Autoreactive T cells are key mediators of β cell destruction. Studies of organ donors with T1D that have examined T cells in pancreas, the diabetogenic insulitis lesion, and lymphoid tissues have revealed a broad repertoire of target antigens and T cell receptor (TCR) usage, with initial evidence of public TCR sequences that are shared by individuals with T1D. Neoepitopes derived from post-translational modifications of native antigens are emerging as novel targets that are more likely to evade self-tolerance. Further studies will determine whether T cell responses to neoepitopes are major disease drivers that could impact prediction, prevention, and therapy. This Review provides an overview of recent progress in our knowledge of autoreactive T cells that has emerged from experimental and clinical research as well as pathology investigations.

Islet Allograft Rejection in Rats: a Time Course Study Characterizing Adhesion Molecule Expression, Mhc Expression, and Infiltrate Immunophenotypes

Wistar Furth (RT1u) islets transplanted under the renal capsules of streptozotocin-diabetic Lewis (RT1l) rats reject after 5–6 days of normoglycemia. Hand-picked WF islets (1500–2000) were transplanted under the kidney capsules of diabetic Lew or WF rats. Rats bearing iso- or allografts were killed on posttransplant days 2, 4, and 6. Serial frozen sections of grafts and controls were stained by immunoperoxidase for rat MAC-1, class II MHC, CD2, CD4, CD8, B-cells, VLA-4, LFA-1, L-selectin, ICAM-1, and VCAM-1. Infiltrating cells, parenchymal cells, and endothelial cells in five distinct compartments (i.e., peritoneal reflection, subcapsular perivascular space, islet grafts, graft–kidney interface, and kidney) were evaluated for expression of the various markers at each interval. Significant infiltrates arrived in three distinct waves in both iso- and allografts. First, macrophages blanketed the peritoneal capsular reflection and infiltrated by day 2. Second, the first wave of lymphocytes arrived in the edematous subcapsular soft tissue via capsular vessels by day 2 (allo > iso). Third, the second wave of lymphocytes arrived from the renal parenchyma to form a dense band at the graft–kidney interface and around grafts by days 4 and 6 (allo >>> iso); CD4+ cells vastly outnumbered CD8+ cells, with CD4+ cells being mobilized first and from interstitial vessels throughout the entire kidney. CD8+ cells emigrated only from renal interstitial vessels adjacent to the graft. Large numbers of L-selectin+, VLA-4+, and LFA-1+ cells were seen in the infiltrates with the most intensely staining cells being intravascular. B-cells composed a very small proportion of infiltrating cells in both allo- and isografts. Endothelial staining for ICAM-1 and VCAM-1 was prominent throughout. Both class II MHC and ICAM-1 expression were induced on renal tubular epithelial cells, but neither was found on islet parenchymal cells. In conclusion, this study shows that islet allograft rejection is more complex than previously realized.

The Potential Contribution of Rejection to Survival of Transplanted Human Islets

Clinical islet transplantation is potentially the treatment of choice for people with type I diabetes. Rates of insulin independence in islet transplant recipients are disappointingly low, and the relative contribution of the rejection response compared with the loss of islet function is still unclear. We have compared the mixed lymphocyte islet coculture (MLIC) with the mixed lymphocyte acinar cell coculture (MLAC) and the mixed lymphocyte response (MLR) as in vitro models of allograft rejection to MHC and tissue-specific antigens expressed by human islets and acinar cells. The reduced number of MHC class II antigen-positive cells in islets and acinar tissue compared to those in the stimulator lymphocyte population of the MLR, correlated with a reduced proliferative response in the MLIC and MLAC. Enhancement of MHC class II antigen expression by islets using TNFα and IFNγ did not increase their stimulatory capacity in the islet cocultures, which may have been due to a corresponding absence of B7 expression. The lack of T cell proliferation to acinar cells despite cytokine-induced enhancement of MHC class II expression and detectable B7 expression appeared to be due to the inhibitory effect of exocrine enzymes on lymphocyte proliferation. In conclusion, we suggest that a rejection response to islets and acinar tissue is possible due to the accompanying MHC class II-positive cells and that, in this model, islet and acinar-specific antigens do not significantly contribute to that response. Acinar cells may have the potential to stimulate lymphocytes directly, but this was not evident by proliferation in the MLAC. Rejection appears to contribute to the low survival rate of human islet allografts, but it is unlikely that this is the sole explanation, and other factors should be considered. © 1998 Elsevier Science Inc.

Systematic review and meta-analysis: pharmacogenetics of anti-TNF treatment response in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease that affects ~1% of the Caucasian population. Over the last decades, the availability of biological drugs targeting the proinflammatory cytokine tumour necrosis factor α, anti-TNF drugs, has improved the treatment of patients with RA. However, one-third of the patients do not respond to the treatment. We wanted to evaluate the status of pharmacogenomics of anti-TNF treatment. We performed a PubMed literature search and all studies reporting original data on associations between genetic variants and anti-TNF treatment response in RA patients were included and results evaluated by meta-analysis. In total, 25 single nucleotide polymorphisms were found to be associated with anti-TNF treatment response in RA (19 from genome-wide association studies and 6 from the meta-analyses), and these map to genes involved in T cell function, NFκB and TNF signalling pathways (including CTCN5, TEC, PTPRC, FCGR2A, NFKBIB, FCGR2A, IRAK3). Explorative prediction analyses found that biomarkers for clinical treatment selection are not yet available.

Mechanisms of diabetic autoimmunity: II--Is diabetes a central or peripheral disorder of effector and regulatory cells?

Two competing hypotheses aiming to explain the onset of autoimmune reactions are discussed in the context of genetic and environmental predisposition to type 1 diabetes (T1D). The first hypothesis has evolved along characterization of the mechanisms of self-discrimination and attributes diabetic autoimmunity to escape of reactive T cells from central regulation in the thymus. The second considers frequent occurrence of autoimmune reactions within the immune homunculus, which are adequately suppressed by regulatory T cells originating from the thymus, and occasionally, insufficient suppression results in autoimmunity. Besides thymic dysfunction, deregulation of both effector and suppressor cells can in fact result from homeostatic aberrations at the peripheral level during initial stages of evolution of adaptive immunity. Pathogenic cells sensitized in the islets are efficiently expanded in the target tissue and pancreatic lymph nodes of lymphopenic neonates. In parallel, the same mechanisms of peripheral sensitization contribute to tolerization through education of naïve/effector T cells and expansion of regulatory T cells. Experimental evidence presented for each individual mechanism implies that T1D may result from a primary effector or suppressor immune abnormality. Disturbed self-tolerance leading to T1D may well result from peripheral deregulation of innate and adaptive immunity, with variable contribution of central thymic dysfunction.

Analysis of T Lymphocytes Cloned from Rejected Kidney Allograft: High Frequency of Cytotoxic T Cell Precursor

A high proportion of CD8 positive cells and inverted CD4/CD8 ratio were found in peripheral blood mononuclear cells and in freshly isolated kidney-graft infiltrating cells in two patients who underwent irreversible acute rejection.

Seventy seven T cell clones were generated from the T cell blasts infiltrating rejected kidney allografts. The majority of T cell clones obtained showed CD8 phenotype in accordance to uncloned graft infiltrating cells. All clones (both CD8 and CD4) displayed cytolytic activity evaluated by lectin-dependent cell-mediated cytotoxicity and natural killer (NK) activities. None of the clones presented lymphokine activated killer phenomenon.

These data suggest that the graft infiltrate is characterized by T cell clones with cytolytic potential and that these T cell clones may be responsible for the killing of graft cells by a CTL or NK type mechanism.

Mouse pancreatic beta cells express MHC class II and stimulate CD4(+) T cells to proliferate

Type 1 diabetes results from destruction of pancreatic beta cells by autoreactive T cells. Both CD4(+) and CD8(+) T cells have been shown to mediate beta-cell killing. While CD8(+) T cells can directly recognize MHC class I on beta cells, the interaction between CD4(+) T cells and beta cells remains unclear. Genetic association studies have strongly implicated HLA-DQ alleles in human type 1 diabetes. Here we studied MHC class II expression on beta cells in nonobese diabetic mice that were induced to develop diabetes by diabetogenic CD4(+) T cells with T-cell receptors that recognize beta-cell antigens. Acute infiltration of CD4(+) T cells in islets occurred with rapid onset of diabetes. Beta cells from islets with immune infiltration expressed MHC class II mRNA and protein. Exposure of beta cells to IFN-γ increased MHC class II gene expression, and blocking IFN-γ signaling in beta cells inhibited MHC class II upregulation. IFN-γ also increased HLA-DR expression in human islets. MHC class II(+) beta cells stimulated the proliferation of beta-cell-specific CD4(+) T cells. Our study indicates that MHC class II molecules may play an important role in beta-cell interaction with CD4(+) T cells in the development of type 1 diabetes.

Adipocyte-derived players in hematologic tumors: useful novel targets?

INTRODUCTION

Adipocytes and their products play essential roles in tumor establishment and progression. As the main cellular component of the bone marrow, adipocytes may contribute to the development of hematologic tumors.

AREAS COVERED

This review summarizes experimental data on adipocytes and their interaction with various cancer cells. Special focus is set on the interactions of bone marrow adipocytes and normal and transformed cells of the hematopoietic system such as myeloma and leukemia cells. Current in vitro and in vivo data are summarized and the potential of novel therapeutic targets is critically discussed.

EXPERT OPINION

Targeting lipid metabolism of cancer cells and adipocytes in combination with standard therapeutics might open novel therapeutic avenues in these cancer entities. Adipocyte-derived products such as free fatty acids and specific adipokines such as adiponectin may be vital anti-cancer targets in hematologic malignancies. However, available data on lipid metabolism is currently mostly referring to peripheral fat cell/cancer cell interactions and results need to be evaluated specifically for the bone marrow niche.

Inflammatory response in islet transplantation

Islet cell transplantation is a promising beta cell replacement therapy for patients with brittle type 1 diabetes as well as refractory chronic pancreatitis. Despite the vast advancements made in this field, challenges still remain in achieving high frequency and long-term successful transplant outcomes. Here we review recent advances in understanding the role of inflammation in islet transplantation and development of strategies to prevent damage to islets from inflammation. The inflammatory response associated with islets has been recognized as the primary cause of early damage to islets and graft loss after transplantation. Details on cell signaling pathways in islets triggered by cytokines and harmful inflammatory events during pancreas procurement, pancreas preservation, islet isolation, and islet infusion are presented. Robust control of pre- and peritransplant islet inflammation could improve posttransplant islet survival and in turn enhance the benefits of islet cell transplantation for patients who are insulin dependent. We discuss several potent anti-inflammatory strategies that show promise for improving islet engraftment. Further understanding of molecular mechanisms involved in the inflammatory response will provide the basis for developing potent therapeutic strategies for enhancing the quality and success of islet transplantation.

Role of major histocompatibility complex class II expression by non-hematopoietic cells in autoimmune and inflammatory disorders: facts and fiction

It is well established that interactions between CD4(+) T cells and major histocompatibility complex class II (MHCII) positive antigen-presenting cells (APCs) of hematopoietic origin play key roles in both the maintenance of tolerance and the initiation and development of autoimmune and inflammatory disorders. In sharp contrast, despite nearly three decades of intensive research, the functional relevance of MHCII expression by non-hematopoietic tissue-resident cells has remained obscure. The widespread assumption that MHCII expression by non-hematopoietic APCs has an impact on autoimmune and inflammatory diseases has in most instances neither been confirmed nor excluded by indisputable in vivo data. Here we review and put into perspective conflicting in vitro and in vivo results on the putative impact of MHCII expression by non-hematopoietic APCs--in both target organs and secondary lymphoid tissues--on the initiation and development of representative autoimmune and inflammatory disorders. Emphasis will be placed on the lacunar status of our knowledge in this field. We also discuss new mouse models--developed on the basis of our understanding of the molecular mechanisms that regulate MHCII expression--that constitute valuable tools for filling the severe gaps in our knowledge on the functions of non-hematopoietic APCs in inflammatory conditions.

Application of the multiplex cytokine analysis to monitor xenogeneic immune responses to the porcine islet graft in non-human primate

Non-human primate studies must be conducted prior to the clinical trial of xenotransplantation. In order to develop clinically applicable immune-modulatory regimen through non-human primate studies, close monitoring of xenogeneic immune responses is required. We adopted multiplex cytokine analysis in assessment of the immune status during the course of pig-to-non-human primate islet transplantation. This study aimed to assess the feasibility of this multiplex cytokine assay in the development of immune-modulatory regimen. Using this assay, we were able to detect different cytokines with a minimal usage of blood samples, and this allowed us to detect various immunological situations in the recipients. Detection of TNF-α surge (347.8 pg/mL) guided us to block TNF-α in the early phase of transplantation. Supportive information for in vivo efficacy of cytokine neutralizing antibody could be speculated by in vitro neutralization assay (1,250 pg/mL → 0 pg/mL). In addition, periodic monitoring of cytokines in peripheral blood allowed the detection of the infection episode prior to other routine assays. These benefits of multiplex cytokine assay may be generally applied to other pre-clinical research, which is a prerequisite for clinical trials.

Viruses and Type 1 diabetes: a dynamic labile equilibrium

Type 1 diabetes (T1D) results from the specific immune-mediated destruction of the insulin-producing β-cells of the pancreas. In genetically susceptible individuals, a still undetermined initiating 'hit' triggers a cascade of events that eventually leads to autoreactive CD8 T cells infiltrating the pancreatic islets and, subsequently, destroying them. There is increasing evidence that viruses, especially enteroviruses, are major environmental candidates; however, despite decades of investigation, we still lack certainty with regard to the causation of T1D. Moreover, studies in animal models of diabetes suggest a protective role of certain enteroviral infections upon diabetes contraction, making the quest for viral involvement in T1D even more difficult. Analyzing the foundation and the results of the most current work in the field, this article gives a brief overview of current knowledge, as well as providing an outlook for future directions.

Beyond the hormone: insulin as an autoimmune target in type 1 diabetes

Insulin is not only the hormone produced by pancreatic β-cells but also a key target antigen of the autoimmune islet destruction leading to type 1 diabetes. Despite cultural biases between the fields of endocrinology and immunology, these two facets should not be regarded separately, but rather harmonized in a unifying picture of diabetes pathogenesis. There is increasing evidence suggesting that metabolic factors (β-cell dysfunction, insulin resistance) and immunological components (inflammation and β-cell-directed adaptive immune responses) may synergize toward islet destruction, with insulin standing at the crossroad of these pathways. This concept further calls for a revision of the classical dichotomy between type 1 and type 2 diabetes because metabolic and immune mechanisms may both contribute to different extents to the development of different forms of diabetes. After providing a background on the mechanisms of β-cell autoimmunity, we will explain the role of insulin and its precursors as target antigens expressed not only by β-cells but also in the thymus. Available knowledge on the autoimmune antibody and T-cell responses against insulin will be summarized. A unifying scheme will be proposed to show how different aspects of insulin biology may lead to β-cell destruction and may be therapeutically exploited. We will argue about possible reasons why insulin remains the mainstay of metabolic control in type 1 diabetes but has so far failed to prevent or halt β-cell autoimmunity as an immune modulatory reagent.

The central role of calcium in the effects of cytokines on beta-cell function: implications for type 1 and type 2 diabetes

The appropriate regulation of intracellular calcium is a requirement for proper cell function and survival. This review focuses on the effects of proinflammatory cytokines on calcium regulation in the insulin-producing pancreatic beta-cell and how normal stimulus-secretion coupling, organelle function, and overall beta-cell viability are impacted. Proinflammatory cytokines are increasingly thought to contribute to beta-cell dysfunction not only in type 1 diabetes (T1D), but also in the progression of type 2 diabetes (T2D). Cytokine-induced disruptions in calcium handling result in reduced insulin release in response to glucose stimulation. Cytokines can alter intracellular calcium levels by depleting calcium from the endoplasmic reticulum (ER) and by increasing calcium influx from the extracellular space. Depleting ER calcium leads to protein misfolding and activation of the ER stress response. Disrupting intracellular calcium may also affect organelles, including the mitochondria and the nucleus. As a chronic condition, cytokine-induced calcium disruptions may lead to beta-cell death in T1D and T2D, although possible protective effects are also discussed. Calcium is thus central to both normal and pathological cell processes. Because the tight regulation of intracellular calcium is crucial to homeostasis, measuring the dynamics of calcium may serve as a good indicator of overall beta-cell function.

Targeting TNF for Treatment of Cancer and Autoimmunity

Tumor necrosis factor-alpha (TNF-alpha) was first isolated two decades ago as a macrophageproduced protein that can effectively kill tumor cells. TNF-alpha is also an essential component of the immune system and is required for hematopoiesis, for protection from bacterial infection and for immune cell-mediated cytotoxicity. Extensive research, however, has revealed that TNF-alpha is one of the major players in tumor initiation, proliferation, invasion, angiogenesis and metastasis. The proinflammatory activities link TNF-alpha with a wide variety of autoimmune diseases, including psoriasis, inflammatory bowel disease, rheumatoid arthritis, systemic sclerosis, systemic lupus erythematosus, multiple sclerosis, diabetes and ankylosing spondylitis. Systemic inhibitors of TNF such as etanercept (Enbrel) (a soluble TNF receptor) and infliximab (Remicade) and adalimumab (Humira) (anti-TNF antibodies) have been approved for the treatment inflammatory bowel disease, psoriasis and rheumatoid arthritis. These drugs, however, exhibit severe side effects and are expensive. Hence orally active blockers of TNF-alpha that are safe, efficacious and inexpensive are urgently needed. Numerous products from fruits, vegetable and traditional medicinal plants have been described which can suppress TNF expression and TNF signaling but their clinical potential is yet uncertain.

A case of type 1 diabetes onset and recurrence of Graves' disease during pegylated interferon-α plus ribavirin treatment for chronic hepatitis C

We report a case of type 1 diabetes onset and recurrence of Graves' disease during pegylated interferon (PEG-IFN)-alpha plus ribavirin treatment for chronic hepatitis C. The patient was a 55-year-old woman diagnosed with chronic hepatitis at age 46 years. She was treated for Graves' disease at 50 years of age. Because Graves' disease remitted, PEG-IFN-alpha plus ribavirin treatment was started for chronic hepatitis C. She was examined because of complaints of general fatigue, weight loss, and palpitations after 24 weeks of the treatment. She was diagnosed with a recurrence of Graves' disease, and methimazole treatment was started. However, she complained of malaise, thirst, polyuria, and loss of body weight. Her fasting blood glucose level was 292 mg/dL and HbA1c was 9.3%. Serum anti-GAD (glutamic acid decarboxylase) antibodies were 2.2 U/mL. She was diagnosed with type 1 diabetes with ketosis, and insulin treatment was started. Serum anti-GAD antibodies gradually increased to 15.1 U/mL. Graves' disease and type 1 diabetes are often complicated, and the coincidental occurrence of these 2 diseases is known as autoimmune polyglandular syndrome type III. However, only a few cases have shown that these diseases occur after IFN treatment.

Translating molecular insights in autoimmunity into effective therapy

Autoimmunity and the pathogenesis of autoimmune diseases were a major focus of the Walter and Eliza Hall Institute, where I started my research career. After my initial studies on immune cell culture and immune regulation, I returned to an analysis of the pathogenesis of human autoimmunity in London. Linking upregulated antigen presentation to autoimmunity led to an investigation of the role of cytokines in rheumatoid arthritis (RA), in collaboration with Ravinder Maini. These experiments defined the concept of a TNF-dependent cytokine cascade driving the manifestations of RA, which led to successful clinical trials of anti-TNF monoclonal antibody in RA patients, heralding a major change in medical practice. This success was made possible by enthusiastic support from many laboratory and clinical colleagues and taught us that cytokines are important rate-limiting steps and hence good therapeutic targets. My current scientific challenge is exploring the hypothesis of whether all major medical needs can be approached via cytokine blockade.

Evidence for Induced Expression of HLA Class II on Human Islets: Possible Mechanism for HLA Sensitization in Transplant Recipients

Recent reports have shown that islet transplant recipients develop antibodies against donor human leukocyte antigen (HLA) class I and II. Because human islets do not express HLA class II under normal conditions, mechanisms underlying induction of the anti-class II response are unclear. We hypothesized that under inflammatory conditions, islets will have induced expression of HLA class II leading to sensitization. Isolated human islets were divided into two groups. Group 1 was cultured at 37 degrees C as control; group 2 was cultured similarly in presence of tumor necrosis factor alpha and interferon gamma. After treatment, islets were analyzed for expression of HLA class II using real-time polymerase chain reaction, immunofluorescence and flow cytometry. Furthermore, serum from an islet transplant recipient who developed anti-class II antibody was tested by flow cytometry for immunoglobulin (Ig) binding to cytokine-stimulated islets. Real-time polymerase chain reaction analysis for gene transcripts of class II transactivator, HLA-DRagr;, and HLA-DRbeta1 showed maximum 9.38-, 18.95-, and 46.5-fold increase, respectively in group 2 when compared with control at 24 hr. Cytokine treatment increased HLA class II expression markedly on both alpha and beta cells in islets as evidenced by fluorescent imaging and flow cytometric analysis. When patient serum was analyzed by flow cytometry, both IgM and IgG binding was observed in cytokine-treated, HLA class II matched islet cells alone. We conclude that inflammation leads to induced expression of HLA class II on transplanted islet cells potentially causing antidonor sensitization and adversely impacting islet transplant outcomes.

First Observation of an Hashimoto Thyroiditis-Like Disease in Horses from Eastern Europe: Histopathological and Immunological Findings

Among 622 slaughtered horses from eastern Europe, 156 thyroid glands were selected on the basis of macroscopic alterations (e.g., determination of volume and weight). In the 80% of these thyroids, microscopic alterations consistent with a diagnosis of Hashimoto thyroiditis-like disease were found. In particular, a subverted architecture of the thyroid gland with colloid rarefaction, lymphocytic infiltration, and fibrosis was noted. The confirmation of the histopathological diagnosis of an equine Hashimoto thyroiditis-like disease was provided by the increased serum concentration of thyroglobulin, of antithyroglobulin, and of antithyroid peroxidase autoantibodies. Despite evidence consistent with an Hashimoto thyroiditis-like disease in eastern European horses, the etiopathogenesis of this autoimmune disorder deserves further investigation. In this respect, in some horses histopathological alterations in the pituitary gland may suggest an as-yet-unidentified disorder within the hypothalamus-pituitary adrenal axis associated with Hashimoto thyroiditis.

Regulation of HLA class II expression and its role in autoimmune disease

Excessive HLA class II expression is found on the target tissues of the majority of human autoimmune diseases, together with activated (interleukin 2 receptor-expressing) T lymphocytes, suggesting that the target tissues act as antigen-presenting cells for infiltrating autoreactive cells, which in turn produce molecules that maintain class II expression. This vicious cycle has been shown to operate in Graves' thyroiditis, because interferon-gamma (IFN-gamma) induces class II expression on thyrocytes, and thyrocytes expressing class II antigens present their autoantigens to T cells cloned from thyroid tissue of Graves' disease patients. These results led us to consider whether the same mechanisms operate in other autoimmune diseases. In investigations into class II induction in other cell types we found that IFN-gamma is not the only regulator of HLA class II expression and that synergy exists among mediators regulating class II differentially on different cell types. This concept makes it possible to envisage selective diminution of class II antigens on target tissues without loss of class II on antigen-presenting cells. The study of mediators regulating class II expression on cells in vitro led us to ask whether the appropriate regulator molecules are important in disease states. To investigate this question we have developed the use of cDNA probes to analyse the expression of lymphokines, other cytokines, and receptors in small local biopsy samples of tissue from patients with autoimmune diseases. Results obtained so far indicate that mRNAs for many lymphokines are present in synovial fluid cell samples from patients with rheumatoid arthritis.

Immunopathogenic role of TH1 cells in autoimmune diabetes: Evidence from a T1 and T2 doubly transgenic non-obese diabetic mouse model

To improve the feasibility of in vivo monitoring of autoreactive T cells in the diabetogenic process, we generated T1 and T2 doubly transgenic non-obese diabetic (NOD) mice in which transgenic human CD90 (hCD90) is simultaneously expressed on IFN-gamma-producing cells or murine CD90.1 (mCD90.1) is expressed on IL-4-producing cells. These transgenic NOD mice develop diabetes with the same kinetics and incidence as wild type NOD mice, permitting the physiological characterization of CD4(+)hCD90(+) cells, which represent T(H)1 cells in lymphoid organs and at the site of insulitis. CD4(+)hCD90(+) cells had a higher capacity to secret IFN-gamma than CD4(+)hCD90(-) cells in an autoantigen-specific manner. Transgenic mice treated with GAD65 plasmid were protected from autoimmune diabetes, and had a lower number of CD4(+)hCD90(+) cells, confirming the pathogenic role of CD4(+)hCD90(+) cells in autoimmune diabetes. To further investigate the effect of IL-12 on the development of T(H)1 cells in autoimmune diabetes, we crossed these doubly transgenic mice to IL-12p35-deficient NOD mice. Despite severe disturbance of diabetes in p35(-/-) mice, the frequency of T(H)1 cells in these mice was slightly lower than in wild type mice. These data support the pathological role of IL-12 in autoimmune diabetes and suggest the existence an IL-12-independent pathway of T(H)1 development.

Death effectors of beta-cell apoptosis in type 1 diabetes

While it is generally agreed that apoptosis of pancreatic beta-cells is the most important and final step in the progression of type 1 diabetes without which clinical diabetes does not develop, it has not been elucidated which molecule(s) are the real culprit(s) in type 1 diabetes. Perforin, FasL, TNFalpha, IL-1, IFNgamma, and NO have been claimed as the effector molecules; however, they, as a single agent, might explain only part of beta-cell death in type 1 diabetes. While FasL was initially considered as a strong candidate for the most important death effector, following experiments cast doubt on such a hypothesis. Combinations or synergism between IFNgamma and TNFalpha or IL-1beta are being revisited as the death effectors, and molecular mechanism explaining such a synergism was addressed in several recent papers. The role of NF-kappaB for pancreatic beta-cell death in type 1 diabetes is also controversial. While NF-kappaB plays anti-apoptotic roles in most other death models, its role in type 1 diabetes might be different probably due to the involvement of multiple cytokines at different stages of the disease progression and the peculiarity of pancreatic beta-cells. Recent papers also suggested a role for Ca2+ in cytokine-mediated pancreatic beta-cell death. Such participation of Ca2+ in beta-cell death appears to have a close relevance to the mitochondrial events or ER stress that constitutes an important part of cell death machinery recently identified.

Inhibitor of kappaB kinase is required to activate a subset of interferon gamma-stimulated genes

IkappaB kinase (IKK), discovered as the major activator of NF-kappaB, plays additional roles in signaling. By using mouse embryo fibroblasts (MEFs) lacking both the alpha and beta subunits of IKK, we find that these proteins are required for induction of a major subset of IFNgamma-stimulated genes and that this requirement is independent of NF-kappaB activation. Furthermore, there is no defect in IFNgamma-stimulated signal transducer and activator of transcription 1 (Stat1) activation or function in the IKKalpha/beta-null MEFs. Therefore, although activated Stat1 dimers are necessary for the activation of these genes in response to IFNgamma, they are not sufficient. These results reveal an important additional pathway for IFNgamma-stimulated gene expression in which an NF-kappaB-independent function of IKK is required.

Evidence of expression of endotoxin receptors CD14, toll-like receptors TLR4 and TLR2 and associated molecule MD-2 and of sensitivity to endotoxin (LPS) in islet beta cells

CD14, a GPI-linked membrane protein, is a component of the lipopolysaccharide (LPS) receptor complex, one of the pattern-recognizing receptors (PRR) expressed by myeloid lineage cells. Here we report that CD14, the functionally linked toll-like receptor molecules, TLR2 and TLR4, and the associated molecule MD-2 are expressed in endocrine cells of the human pancreatic islets. CD14 expression in human pancreatic islets was determined by immunofluorescence staining of tissue sections and primary cultures, and confirmed by flow cytometry of dispersed normal islets and SV40-transformed islet cells (HP62). The latter cells synthesized and secreted CD14 in response to lipopolysaccharide (LPS) in a time- and dose-dependent manner. Reverse transcription polymerase chain reaction (RT-PCR)-Southern was positive for CD14, TLR2, TLR4 and MD-2 in human pancreas, purified islets and HP62 cells. In vitro experiments using rat islets (also positive for CD14 by RT-PCR) and HP62 cells showed that LPS regulates glucose-dependent insulin secretion and induces inflammatory cytokines [interleukin (IL)-1alpha, IL-6 and tumour necrosis factor (TNF)-alpha]. The functional expression of CD14 and associated molecules in islet beta cells adds a new pathway that islet cells may follow to adjust their function to endotoxaemia situations and become vulnerable to the inflammatory events that occur during diabetogenic insulitis.