Nous conceptes sobre la diabetis autoimmunitària

La diabetis mellitus de tipus 1 (DT1) és una malaltia metabòlica provocada per la destrucció de les cèl·lules productores d'insulina, les cèl·lules β dels illots pancreàtics. De base autoimmunitària, no es coneix l'etiologia d'aquesta malaltia, tot i que s'han identificat factors genètics, ambientals i immunitaris de susceptibilitat. En aquest article fem un repàs dels mecanismes d'autoimmunitat i els nous conceptes en aquest camp. També destaquem els models experimentals utilitzats en l'estudi de la DT1 i les noves teràpies desenvolupades amb aquests. Per acabar, fem una ullada al present i al futur de la immunoteràpia preventiva i de tractament en aquesta malaltia, i insistim en la necessitat d'aturar el procés autoimmunitari, restaurar la tolerància immunitària, identificar nous biomarcadors de progressió i aplicar conjuntament estratègies de regeneració i neogènesi de les cèl·lules β.Type 1 diabetes (DT1) is a metabolic disease caused by the selective destruction of the insulin producing β cells by the immune system. The etiology of the disease is still unknown, but several genetic, environmental and immunological factors of susceptibility have been identified. In this chapter we describe the autoimmune mechanisms involved in this disease, as well as the experimental models used for the study of DT1 and for the development of new strategies of immune intervention. Lastly, we explain the recent assays in immunotherapies aimed at preventing and curing the disease, based on breaking autoimmune response, restoring immunological tolerance and identifying new biomarkers of disease progression, as well as strategies for regenerating β cells

L'estimulació sensorial millora el dany cerebral en ratolins models de prematurs

Investigadores de l'INc­UAB han demostrat per primera vegada en un model murí de nadons prematurs que una lesió cerebral per hipòxia i isquèmia condiciona de forma diferent les capacitats funcionals neurològiques, cognitives i emocionals depenent del sexe, l'edat i la tasca a realitzar, tot i tenir el mateix grau de severitat neuropatològica en mascles i femelles. Alhora, mostren que l'estimulació sensorial tàctil i propioceptiva dels prematurs pot ajudar a millorar alguns d'aquests aspectes, especialment en el sexe masculí, on sovint els tractaments són menys efectius.Investigadores del INc-UAB han demostrado por primera vez en un modelo murino de bebés prematuros que una lesión cerebral por hipoxia e isquemia condiciona de forma diferente las capacidades funcionales neurológicas, cognitivas y emocionales dependiendo del sexo, la edad y la tarea a realizar, a pesar de tener el mismo grado de severidad neuropatológica en machos y hembras. Asimismo, muestran que la estimulación sensorial táctil y propioceptiva de los prematuros puede ayudar a mejorar algunos de estos aspectos, especialmente en el sexo masculino, donde a menudo los tratamientos son menos efectivos.A research conducted by the INc-UAB shows that the same perinatal brain injury caused by hypoxia and ischemia have differentiated effects on each gender, but can be improved through tactile and proprioceptive stimuli. Petting and massaging the mice in the first stages of their life provided neurological protection in their adult life, especially in male mice in which the injury was reduced by half

Use of autoantigen-loaded phosphatidylserine-liposomes to arrest autoimmunity in type 1 diabetes

This is an open access article distributed under the terms of the Creative Commons Attribution License.-- et al.[Introduction]: The development of new therapies to induce self-tolerance has been an important medical health challenge in type 1 diabetes. An ideal immunotherapy should inhibit the autoimmune attack, avoid systemic side effects and allow β-cell regeneration. Based on the immunomodulatory effects of apoptosis, we hypothesized that apoptotic mimicry can help to restore tolerance lost in autoimmune diabetes.[Objective]: To generate a synthetic antigen-specific immunotherapy based on apoptosis features to specifically reestablish tolerance to β-cells in type 1 diabetes.[Methods]: A central event on the surface of apoptotic cells is the exposure of phosphatidylserine, which provides the main signal for efferocytosis. Therefore, phosphatidylserine-liposomes loaded with insulin peptides were generated to simulate apoptotic cells recognition by antigen presenting cells. The effect of antigen-specific phosphatidylserine-liposomes in the reestablishment of peripheral tolerance was assessed in NOD mice, the spontaneous model of autoimmune diabetes. MHC class II-peptide tetramers were used to analyze the T cell specific response after treatment with phosphatidylserine-liposomes loaded with peptides.[Results]: We have shown that phosphatidylserine-liposomes loaded with insulin peptides induce tolerogenic dendritic cells and impair autoreactive T cell proliferation. When administered to NOD mice, liposome signal was detected in the pancreas and draining lymph nodes. This immunotherapy arrests the autoimmune aggression, reduces the severity of insulitis and prevents type 1 diabetes by apoptotic mimicry. MHC class II tetramer analysis showed that peptide-loaded phosphatidylserine-liposomes expand antigen-specific CD4+ T cells in vivo. The administration of phosphatidylserine-free liposomes emphasizes the importance of phosphatidylserine in the modulation of antigen-specific CD4+ T cell expansion.[Conclusions]: We conclude that this innovative immunotherapy based on the use of liposomes constitutes a promising strategy for autoimmune diseases.This work was supported by a grant from Spanish Government (FIS PI12/00195). IPA was supported by AGAUR, Generalitat de Catalunya. MVP and RA are supported by the Health Dept. of the Catalan Government, Generalitat de Catalunya.Peer reviewe

Immune System Remodelling by Prenatal Betamethasone : Effects on β-Cells and Type 1 Diabetes

Type 1 diabetes (T1D) is a multifactorial disease of unknown aetiology. Studies focusing on environment-related prenatal changes, which might have an influence on the development of T1D, are still missing. Drugs, such as betamethasone, are used during this critical period without exploring possible effects later in life. Betamethasone can interact with the development and function of the two main players in T1D, the immune system and the pancreatic β-cells. Short-term or persistent changes in any of these two players may influence the initiation of the autoimmune reaction against β-cells. In this review, we focus on the ability of betamethasone to induce alterations in the immune system, impairing the recognition of autoantigens. At the same time, betamethasone affects β-cell gene expression and apoptosis rate, reducing the danger signals that will attract unwanted attention from the immune system. These effects may synergise to hinder the autoimmune attack. In this review, we compile scattered evidence to provide a better understanding of the basic relationship between betamethasone and T1D, laying the foundation for future studies on human cohorts that will help to fully grasp the role of betamethasone in the development of T1D

How apoptotic β-cells direct immune response to tolerance or to autoimmune diabetes : a review

Type 1 diabetes (T1D) is a metabolic disease that results from the autoimmune attack against insulin-producing β-cells in the pancreatic islets of Langerhans. Currently, there is no treatment to restore endogenous insulin secretion in patients with autoimmune diabetes. In the last years, the development of new therapies to induce long-term tolerance has been an important medical health challenge. Apoptosis is a physiological mechanism that contributes to the maintenance of immune tolerance. Apoptotic cells are a source of autoantigens that induce tolerance after their removal by antigen presenting cells (APCs) through a process called efferocytosis. Efferocytosis will not cause maturation in dendritic cells, one of the most powerful APCs, and this process could induce tolerance rather than autoimmunity. However, failure of this mechanism due to an increase in the rate of β-cells apoptosis and/or defects in efferocytosis results in activation of APCs, contributing to inflammation and to the loss of tolerance to self. In fact, T1D and other autoimmune diseases are associated to enhanced apoptosis of target cells and defective apoptotic cell clearance. Although further research is needed, the clinical relevance of immunotherapies based on apoptosis could prove to be very important, as it has translational potential in situations that require the reestablishment of immunological tolerance, such as autoimmune diseases. This review summarizes the effects of apoptosis of β-cells towards autoimmunity or tolerance and its application in the field of emerging immunotherapies

Prenatal Betamethasone Exposure and its Impact on Pediatric Type 1 Diabetes Mellitus : A Preliminary Study in a Spanish Cohort

Betamethasone, a glucocorticoid used to induce lung maturation when there is a risk of preterm delivery, can affect the immune system maturation and type 1 diabetes (T1D) incidence in the progeny. It has been described that prenatal betamethasone protects offspring from experimental T1D development. The main aim of this study was to evaluate the possible association between betamethasone prenatal exposure and T1D in humans. Research Design and Methods. A retrospective case-control study with a total of 945 children, including 471 patients with T1D and 474 healthy siblings, was performed. Participants were volunteers from the Germans Trias i Pujol Hospital and DiabetesCero Foundation. Parents of children enrolled in the study completed a questionnaire that included questions about weeks of gestation, preterm delivery risk, weight at birth, and prenatal betamethasone exposure of their children. Multiple logistic regression was used to detect the association between betamethasone exposure and T1D. We compared T1D prevalence between subjects prenatally exposed or unexposed to betamethasone. The percent of children with T1D in the exposed group was 37.5% (21 of 56), and in the unexposed group was 49.52% (410 of 828) (p = 0.139). The percentage of betamethasone-treated subjects with T1D in the preterm group (18.05%, 13 of 72) was significantly higher than that found in the control group (12.5%, 9 of 72) (p = 0.003). The odds ratio for T1D associated with betamethasone in the univariate logistic regression was 0.59 (95% confidence interval, 0.33; 1.03 [ p = 0.062]) and in the multivariate logistic regression was 0.83 (95% confidence interval, 0.45; 1.52 [ p = 0.389]). The results demonstrate that the prenatal exposure to betamethasone does not increase T1D susceptibility, and may even be associated with a trend towards decreased risk of developing the disease. These preliminary findings require further prospective studies with clinical data to confirm betamethasone exposure effect on T1D risk

The G1/S Specific Cyclin D2 Is a Regulator of HIV-1 Restriction in Non-proliferating Cells

Macrophages are a heterogeneous cell population strongly influenced by differentiation stimuli that become susceptible to HIV-1 infection after inactivation of the restriction factor SAMHD1 by cyclin-dependent kinases (CDK). Here, we have used primary human monocyte-derived macrophages differentiated through different stimuli to evaluate macrophage heterogeneity on cell activation and proliferation and susceptibility to HIV-1 infection. Stimulation of monocytes with GM-CSF induces a non-proliferating macrophage population highly restrictive to HIV-1 infection, characterized by the upregulation of the G1/S-specific cyclin D2, known to control early steps of cell cycle progression. Knockdown of cyclin D2, enhances HIV-1 replication in GM-CSF macrophages through inactivation of SAMHD1 restriction factor by phosphorylation. Co-immunoprecipitation experiments show that cyclin D2 forms a complex with CDK4 and p21, a factor known to restrict HIV-1 replication by affecting the function of the downstream cascade that leads to SAMHD1 deactivation. Thus, we demonstrate that cyclin D2 acts as regulator of cell cycle proteins affecting SAMHD1-mediated HIV-1 restriction in non-proliferating macrophage

Efferocytosis promotes suppressive effects on dendritic cells through prostaglandin E2 production in the context of autoimmunity

Introduction: Efferocytosis is a crucial process by which apoptotic cells are cleared by phagocytes, maintaining immune tolerance to self in the absence of inflammation. Peripheral tolerance, lost in autoimmune processes, may be restored by the administration of autologous dendritic cells loaded with islet apoptotic cells in experimental type 1 diabetes. Objective: To evaluate tolerogenic properties in dendritic cells induced by the clearance of apoptotic islet cells, thus explaining the re-establishment of tolerance in a context of autoimmunity. Methods: Bone marrow derived dendritic cells from non-obese diabetic mice, a model of autoimmune diabetes, were generated and pulsed with islet apoptotic cells. The ability of these cells to induce autologous T cell proliferation and to suppress mature dendritic cell function was assessed, together with cytokine production. Microarray experiments were performed using dendritic cells to identify differentially expressed genes after efferocytosis. Results: Molecular and functional changes in dendritic cells after the capture of apoptotic cells were observed. 1) Impaired ability of dendritic cells to stimulate autologous T cell proliferation after the capture of apoptotic cells even after proinflammatory stimuli, with a cytokine profile typical for immature dendritic cells. 2) Suppressive ability of mature dendritic cell function. 3) Microarray-based gene expression profiling of dendritic cells showed differential expression of genes involved in antigen processing and presentation after efferocytosis. 4) Prostaglandin E2 increased production was responsible for immunosuppressive mechanism of dendritic cells after the capture of apoptotic cells. Conclusions: The tolerogenic behaviour of dendritic cells after islet cells efferocytosis points to a mechanism of silencing potential autoreactive T cells in the microenvironment of autoimmunity. Our results suggest that dendritic cells may be programmed to induce specific immune tolerance using apoptotic cells; this is a viable strategy for a variety of autoimmune diseases.This work was supported by grants from the Fondo de Investigaciones Sanitarias (PS09/00253 and PI12/00195) of the Carlos III Institute of Health, www.isciii.es. RP was supported by the Instituto de Salud Carlos III of the Spanish National Institute of Health (FIS05/00418). MVP is funded by the stabilization program of Miguel Servet biomedical researchers and RMA by the program of research technicians of the Instituto de Salud Carlos III and Direcció d’Estrategia i Coordinacio, Health Dept. of the Catalonian Government. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Impact of Betamethasone Pretreatment on Engrafment of Cord Blood-Derived Hematopoietic Stem Cells

Hematopoietic stem cell (HSC) transplantation is crucial to cure hematologic malignancies. Umbilical cord blood (UCB) is a source of stem cells, but 90% of UCB units are discarded due to low cellularity. Improving the engraftment capacities of CD34 + stem cells would allow the use of UCB that were so far rejected. Betamethasone induces long-term transcriptomic and epigenomic changes in immune cells through glucocorticoid receptor. We hypothesize that discarded UCB could be used owing to improvements induced by betamethasone. Isolated CD34 + HSC from UCB were exposed to the synthetic glucocorticoids betamethasone and fluticasone for 20 h, and cell phenotype was determined before transplantation. NSG mice were sub-lethally irradiated (1 Gy or 2 Gy) 6 h before intravenously transferring 2-5 × 10 5 CD34 + HSC. The peripheral blood engraftment levels and the leukocyte subsets were followed up for 20 weeks using flow cytometry. At end point, the engraftment and leukocyte subsets were determined in the spleen and bone marrow. We demonstrated that betamethasone has surprising effects in recovering immune system homeostasis. Betamethasone and fluticasone increase CXCR4 and decrease HLA class II and CD54 expression in CD34 + HSCs. Both glucocorticoids-exposed cells showed a similar engraftment in 2 Gy-irradiated NSG mice. Interestingly, betamethasone-exposed cells showed enhanced engraftment in 1 Gy-irradiated NSG mice, with a trend to increase regulatory T cell percentage when compared to control. Betamethasone induces alterations in CD34 + HSCs and improve the engraftment, leading to a faster immune system recovery, which will contribute to engrafted cells survival