Leveraging current insights on IL-10-producing dendritic cells for developing effective immunotherapeutic approaches.

Dendritic cells (DC) are professional antigen-presenting cells involved in promoting and controlling immune responses. Different subsets of DC, named tolerogenic (tol)DC, play a critical role in the maintenance of tissue homeostasis and in fostering tolerance. These unique skills make tolDC especially attractive for strategies aimed at re-establishing/inducing tolerance in immune-mediated conditions. The generation of potent tolDC in vitro from peripheral blood monocytes has seen remarkable advancements. TolDC modulate T cell dynamics by favoring regulatory T cells (Tregs) and curbing effector/pathogenic T cells. Among the several methods developed for in vitro tolDC generation, IL-10 conditioning has been proven to be the most efficient, as IL-10-modulated tolDC were demonstrated to promote Tregs with the strongest suppressive activities. Investigating the molecular, metabolic, and functional profiles of tolDC uncovers essential pathways that facilitate their immunoregulatory functions. This Review provides an overview of current knowledge on the role of tolDC in health and disease, focusing on IL-10 production, functional characterization of in vitro generated tolDC, molecular and metabolic changes occurring in tolDC induced by tolerogenic agents, clinical applications of tolDC-based therapy, and finally new perspectives in the generation of effective tolDC.

A GLB1 transgene with enhanced therapeutic potential for the preclinical development of ex-vivo gene therapy to treat mucopolysaccharidosis type IVB.

Mucopolysaccharidosis type IVB (MPSIVB) is a lysosomal storage disorder caused by ß-galactosidase (ß-GAL) deficiency characterized by severe skeletal and neurological alterations without approved treatments. To develop hematopoietic stem progenitor cell (HSPC) gene therapy (GT) for MPSIVB, we designed lentiviral vectors (LVs) encoding human ß-GAL to achieve supraphysiological release of the therapeutic enzyme in human HSPCs and metabolic correction of diseased cells. Transduced HSPCs displayed proper colony formation, proliferation, and differentiation capacity, but their progeny failed to release the enzyme at supraphysiological levels. Therefore, we tested alternative LVs to overexpress an enhanced ß-GAL deriving from murine (LV-enhGLB1) and human selectively mutated GLB1 sequences (LV-mutGLB1). Only human HSPCs transduced with LV-enhGLB1 overexpressed ß-GAL in vitro and in vivo without evidence of overexpression-related toxicity. Their hematopoietic progeny efficiently released ß-GAL, allowing the cross-correction of defective cells, including skeletal cells. We found that the low levels of human GLB1 mRNA in human hematopoietic cells and the improved stability of the enhanced ß-GAL contribute to the increased efficacy of LV-enhGLB1. Importantly, the enhanced ß-GAL enzyme showed physiological lysosomal trafficking in human cells and was not associated with increased immunogenicity in vitro. These results support the use of LV-enhGLB1 for further HSPC-GT development and future clinical translation to treat MPSIVB multisystem disease.

Microglia-specific IL-10 gene delivery inhibits neuroinflammation and neurodegeneration in a mouse model of Parkinson's disease.

Neuroinflammation plays a key role in exacerbating dopaminergic neuron (DAN) loss in Parkinson's disease (PD). However, it remains unresolved how to effectively normalize this immune response given the complex interplay between the innate and adaptive immune responses occurring within a scarcely accessible organ like the brain. In this study, we uncovered a consistent correlation between neuroinflammation, brain parenchymal lymphocytes, and DAN loss among several commonly used mouse models of PD generated by a variety of pathological triggers. We validated a viral therapeutic approach for the microglia-specific expression of interleukin 10 (IL-10) to selectively mitigate the excessive inflammatory response. We found that this approach induced a local nigral IL-10 release that alleviated DAN loss in mice overexpressing the human SNCA gene in the substantia nigra. Single-cell transcriptomics revealed that IL-10 induced the emergence of a molecularly distinct microglial cell state, enriched in markers of cell activation with enhanced expression of prophagocytic pathways. IL-10 promoted microglial phagocytotic and clearance activities in vitro and reduced αSYN aggregate burden in the nigral area in mice overexpressing SNCA. Furthermore, IL-10 stimulated the differentiation of CD4+ T lymphocytes into active T regulatory cells and promoted inhibitory characteristics in CD8+ T cells. In summary, our results show that local and microglia-specific IL-10 transduction elicited strong immunomodulation in the nigral tissue with enhanced suppression of lymphocyte toxicity that was associated with DAN survival. These results offer insights into the therapeutic benefits of IL-10 and showcase a promising gene delivery approach that could minimize undesired side effects.

CD32 captures committed haemogenic endothelial cells during human embryonic development.

During embryonic development, blood cells emerge from specialized endothelial cells, named haemogenic endothelial cells (HECs). As HECs are rare and only transiently found in early developing embryos, it remains difficult to distinguish them from endothelial cells. Here we performed transcriptomic analysis of 28- to 32-day human embryos and observed that the expression of Fc receptor CD32 (FCGR2B) is highly enriched in the endothelial cell population that contains HECs. Functional analyses using human embryonic and human pluripotent stem cell-derived endothelial cells revealed that robust multilineage haematopoietic potential is harboured within CD32+ endothelial cells and showed that 90% of CD32+ endothelial cells are bona fide HECs. Remarkably, these analyses indicated that HECs progress through different states, culminating in FCGR2B expression, at which point cells are irreversibly committed to a haematopoietic fate. These findings provide a precise method for isolating HECs from human embryos and human pluripotent stem cell cultures, thus allowing the efficient generation of haematopoietic cells in vitro.

IL-10-producing regulatory cells impact on celiac disease evolution.

Celiac Disease (CD) is a T-cell mediated disorder caused by immune response to gluten, although the mechanisms underlying CD progression are still elusive. We analyzed immune cell composition, plasma cytokines, and gliadin-specific T-cell responses in patients with positive serology and normal intestinal mucosa (potential-CD) or villous atrophy (acute-CD), and after gluten-free diet (GFD). We found: an inflammatory signature and the presence of circulating gliadin-specific IFN-γ+ T cells in CD patients regardless of mucosal damage; an increased frequency of IL-10-secreting dendritic cells (DC-10) in the gut and of circulating gliadin-specific IL-10-secreting T cells in potential-CD; IL-10 inhibition increased IFN-γ secretion by gliadin-specific intestinal T cells from acute- and potential-CD. On GFD, inflammatory cytokines normalized, while IL-10-producing T cells accumulated in the gut. We show that IL-10-producing cells are fundamental in controlling pathological T-cell responses to gluten: DC-10 protect the intestinal mucosa from damage and represent a marker of potential-CD.

IL-10-Engineered Dendritic Cells Modulate Allogeneic CD8+ T Cell Responses.

Tolerogenic dendritic cells (tolDC) play a central role in regulating immune homeostasis and in promoting peripheral tolerance. These features render tolDC a promising tool for cell-based approaches aimed at inducing tolerance in T-cell mediated diseases and in allogeneic transplantation. We developed a protocol to generate genetically engineered human tolDC overexpressing IL-10 (DCIL-10) by means of a bidirectional lentiviral vector (LV) encoding for IL-10. DCIL-10 promote allo-specific T regulatory type 1 (Tr1) cells, modulate allogeneic CD4+ T cell responses in vitro and in vivo, and are stable in a pro-inflammatory milieu. In the present study, we investigated the ability of DCIL-10 to modulate cytotoxic CD8+ T cell responses. We demonstrate that DCIL-10 reduces allogeneic CD8+ T cell proliferation and activation in primary mixed lymphocyte reactions (MLR). Moreover, long-term stimulation with DCIL-10 induces allo-specific anergic CD8+ T cells without signs of exhaustion. DCIL-10-primed CD8+ T cells display limited cytotoxic activity. These findings indicate that stable over-expression of IL-10 in human DC leads to a population of cells able to modulate cytotoxic allogeneic CD8+ T cell responses, overall indicating that DCIL-10 represent a promising cellular product for clinical applications aimed at inducing tolerance after transplantation.

Constitutive IL-1RA production by modified immune cells protects against IL-1-mediated inflammatory disorders.

Dysregulation of the interleukin-1 (IL-1) pathway leads to immune diseases that can result in chronic tissue and organ inflammation. Although IL-1 blockade has shown promise in ameliorating these symptoms and improving patients' quality of life, there is an urgent need for more effective, long-lasting treatments. We developed a lentivirus (LV)-mediated gene transfer strategy using transplanted autologous hematopoietic stem/progenitor cells (HSPCs) as a source of IL-1 receptor antagonist (IL-1RA) for systemic delivery to tissues and organs. Transplantation of mouse and human HSPCs transduced with an IL-1RA-encoding LV ensured stable IL-1RA production while maintaining the clonogenic and differentiation capacities of HSPCs in vivo. We examined the efficacy of cell-mediated IL-1RA delivery in three models of IL-1-dependent inflammation, for which treatment hindered neutrophil recruitment in an inducible model of gout, prevented systemic and multi-tissue inflammation in a genetic model of cryopyrin-associated periodic syndromes, and reduced disease severity in an experimental autoimmune encephalomyelitis model of multiple sclerosis. Our findings demonstrate HSPC-mediated IL-1RA delivery as a potential therapeutic modality that can be exploited to suppress tissue and organ inflammation in diverse immune-related diseases involving IL-1-driven inflammation.

Tolerogenic IL-10-engineered dendritic cell-based therapy to restore antigen-specific tolerance in T cell mediated diseases.

Tolerogenic dendritic cells play a critical role in promoting antigen-specific tolerance via dampening of T cell responses, induction of pathogenic T cell exhaustion and antigen-specific regulatory T cells. Here we efficiently generate tolerogenic dendritic cells by genetic engineering of monocytes with lentiviral vectors co-encoding for immunodominant antigen-derived peptides and IL-10. These transduced dendritic cells (designated DCIL-10/Ag) secrete IL-10 and efficiently downregulate antigen-specific CD4+ and CD8+ T cell responses from healthy subjects and celiac disease patients in vitro. In addition, DCIL-10/Ag induce antigen-specific CD49b+LAG-3+ T cells, which display the T regulatory type 1 (Tr1) cell gene signature. Administration of DCIL-10/Ag resulted in the induction of antigen-specific Tr1 cells in chimeric transplanted mice and the prevention of type 1 diabetes in pre-clinical disease models. Subsequent transfer of these antigen-specific T cells completely prevented type 1 diabetes development. Collectively these data indicate that DCIL-10/Ag represent a platform to induce stable antigen-specific tolerance to control T-cell mediated diseases.

Aryl hydrocarbon receptor activity downstream of IL-10 signaling is required to promote regulatory functions in human dendritic cells.

Interleukin (IL)-10 is a main player in peripheral immune tolerance, the physiological mechanism preventing immune reactions to self/harmless antigens. Here, we investigate IL-10-induced molecular mechanisms generating tolerogenic dendritic cells (tolDC) from monocytes. Using genomic studies, we show that IL-10 induces a pattern of accessible enhancers exploited by aryl hydrocarbon receptor (AHR) to promote expression of a set of core genes. We demonstrate that AHR activity occurs downstream of IL-10 signaling in myeloid cells and is required for the induction of tolerogenic activities in DC. Analyses of circulating DCs show that IL-10/AHR genomic signature is active in vivo in health. In multiple sclerosis patients, we instead observe significantly altered signature correlating with functional defects and reduced frequencies of IL-10-induced-tolDC in vitro and in vivo. Our studies identify molecular mechanisms controlling tolerogenic activities in human myeloid cells and may help in designing therapies to re-establish immune tolerance.

Testosterone in males with COVID-19: a 12-month cohort study.

BACKGROUND: Male patients with COVID-19 have been found with reduced serum total testosterone (tT) levels and with more severe clinical outcomes. OBJECTIVES: To assess total testosterone (tT) levels and the probability of recovering eugonadal tT levels during a minimum 12-month timespan in a cohort of men who have been followed over time after the recovery from laboratory-confirmed COVID-19. MATERIALS AND METHODS: Demographic, clinical and hormonal values were collected for the overall cohort. Hypogonadism was defined as tT ≤9.2 nmol/l. The Charlson Comorbidity Index was used to score health-significant comorbidities. Descriptive statistics was used to compare hormonal levels at baseline versus 7-month (FU1) versus 12-month (FU2) follow-up, respectively. Multivariate cox proportional hazards regression model was used to identify the potential predictors of eugonadism recovery over time among patients with hypogonadism at the time of infection. RESULTS: Of the original cohort of 286 patients, follow-up data were available for 121 (42.3%) at FU1 and 63 (22%) patients at FU2, respectively. Higher median interquartile range (IQR) tT levels were detected at FU2 (13.8 (12.3-15.3) nmol/L) versus FU1 (10.2 [9.3-10.9] nmol/L) and versus baseline (3.6 [3.02-4.02] nmol/L) (all p < 0.0001), whilst both LH and E2 levels significantly decreased over the same time frame (all p ≤ 0.01). Circulating IL-6 levels further decreased at FU2 compared to FU1 levels (19.3 vs. 72.8 pg/ml) (p = 0.02). At multivariable cox regression analyses, baseline tT level (HR 1.19; p = 0.03 [1.02-1.4]) was independently associated with the probability of tT level normalization over time, after adjusting for potential confounders. CONCLUSIONS: Circulating tT levels keep increasing over time in men after COVID-19. Still, almost 30% of men who recovered from COVID-19 had low circulating T levels suggestive for a condition of hypogonadism at a minimum 12-month follow-up.

Combined plasma levels of IL-10 and testosterone, but not soluble HLA-G5, predict the risk of death in COVID-19 patients.

BACKGROUND: The identification of biomarkers correlated with coronavirus disease 2019 (COVID-19) outcomes is a relevant need for clinical management. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is characterized by elevated interleukin (IL)-6, IL-10, HLA-G, and impaired testosterone production. OBJECTIVES: We aimed at defining the combined impact of sex hormones, interleukin-10, and HLA-G on COVID-19 pathophysiology and their relationship in male patients. MATERIALS AND METHODS: We measured by chemiluminescence immunoassay, electrochemiluminescent assays, and enzyme-linked immunosorbent assay circulating total testosterone, 17ß-estradiol (E2 ), IL-10, and -HLAG5 as well as SARS-CoV-2 S1/S2 Immunoglobulin G from 292 healthy controls and 111 COVID-19 patients with different disease severity at hospital admission, and in 53 COVID-19 patients at 7-month follow-up. RESULTS AND DISCUSSION: We found significantly higher levels of IL-10, HLA-G, and E2 in COVID-19 patients compared to healthy controls and an inverse correlation between IL-10 and testosterone, with IL-10, progressively increasing and testosterone progressively decreasing with disease severity. This correlation was lost at the 7-month follow-up. The risk of death in COVID-19 patients with low testosterone increased in the presence of high IL-10. A negative correlation between SARS-CoV-2 Immunoglobulin G and HLA-G or IL-10 at hospitalization was observed. At the 7-month follow-up, IL-10 and testosterone normalized, and  HLA-G decreased. CONCLUSION: Our findings indicate that combined evaluation of IL-10 and testosterone predicts the risk of death in men with COVID-19 and support the hypothesis that IL-10 fails to suppress excessive inflammation by promoting viral spreading.

Natural history of type 1 diabetes on an immunodysregulatory background with genetic alteration in B-cell activating factor receptor: A case report.

The immunological events leading to type 1 diabetes (T1D) are complex and heterogeneous, underscoring the necessity to study rare cases to improve our understanding. Here, we report the case of a 16-year-old patient who showed glycosuria during a regular checkup. Upon further evaluation, stage 2 T1D, autoimmune thrombocytopenic purpura (AITP), and common variable immunodeficiency (CVID) were diagnosed. The patient underwent low carb diet, losing > 8 kg, and was placed on Ig replacement therapy. Anti-CD20 monoclonal antibody (Rituximab, RTX) was administered 2 years after diagnosis to treat peripheral polyneuropathy, whereas an atypical mycobacteriosis manifested 4 years after diagnosis and was managed with prolonged antibiotic treatment. In the fifth year of monitoring, the patient progressed to insulin dependency despite ZnT8A autoantibody resolution and IA-2A and GADA autoantibody decline. The patient had low T1D genetic risk score (GRS = 0.22817) and absence of human leukocyte antigen (HLA) DR3/DR4-DQ8. Genetic analysis identified the monoallelic mutation H159Y in TNFRSF13C, a gene encoding B-cell activating factor receptor (BAFFR). Significant reduced blood B-cell numbers and BAFFR levels were observed in line with a dysregulation in BAFF-BAFFR signaling. The elevated frequency of PD-1+ dysfunctional Tfh cells composed predominantly by Th1 phenotype was observed at disease onset and during follow-up. This case report describes a patient progressing to T1D on a BAFFR-mediated immunodysregulatory background, suggesting a role of BAFF-BAFFR signaling in islet-specific tolerance and T1D progression.

Alteration of interleukin-10-producing Type 1 regulatory cells in autoimmune diseases.

PURPOSE OF REVIEW: This review highlights findings describing the role of interleukin (IL)-10-producing Type 1 regulatory T (Tr1) cells in controlling autoimmune diseases and possible approaches to restore their function and number. RECENT FINDINGS: Reduced frequency and/or function of cell subsets playing a role in Tr1 cell induction (e.g., DC-10 and Bregs), was found in patients with autoimmunity and may impact on Tr1 cell frequency. SUMMARY: IL-10 is a pleiotropic cytokine with fundamental anti-inflammatory functions acting as negative regulator of immune responses. IL-10 is critically involved in the induction and functions of Tr1 cells, a subset of memory CD4+ T cells induced in the periphery to suppress immune responses to a variety of antigens (Ags), including self-, allogeneic, and dietary Ags. Alterations in IL-10-related pathways and/or in the frequency and activities of Tr1 cells have been associated to several autoimmune diseases. We will give an overview of the alterations of IL-10 and IL-10-producing Tr1 cells in Multiple Sclerosis, Type 1 Diabetes, and Celiac Disease, in which similarities in the role of these tolerogenic mechanisms are present. Current and future approaches to overcome Tr1 cell defects and restore tolerance in these diseases will also be discussed.

Editing T cell repertoire by thymic epithelial cell-directed gene transfer abrogates risk of type 1 diabetes development.

Insulin is the primary autoantigen (Ag) targeted by T cells in type 1 diabetes (T1D). Although biomarkers precisely identifying subjects at high risk of T1D are available, successful prophylaxis is still an unmet need. Leaky central tolerance to insulin may be partially ascribed to the instability of the MHC-InsB9-23 complex, which lowers TCR avidity, thus resulting in defective negative selection of autoreactive clones and inadequate insulin-specific T regulatory cell (Treg) induction. We developed a lentiviral vector (LV)-based strategy to engineer thymic epithelial cells (TECs) to correct diabetogenic T cell repertoire. Intrathymic (it) LV injection established stable transgene expression in EpCAM+ TECs, by virtue of transduction of TEC precursors. it-LV-driven presentation of the immunodominant portion of ovalbumin allowed persistent and complete negative selection of responsive T cells in OT-II chimeric mice. We successfully applied this strategy to correct the diabetogenic repertoire of young non-obese diabetic mice, imposing the presentation by TECs of the stronger agonist InsulinB9-23R22E and partially depleting the existing T cell compartment. We further circumscribed LV-driven presentation of InsulinB9-23R22E by micro-RNA regulation to CD45- TECs without loss of efficacy in protection from diabetes, associated with expanded insulin-specific Tregs. Overall, our gene transfer-based prophylaxis fine-tuned the central tolerance processes of negative selection and Treg induction, correcting an autoimmune prone T cell repertoire.

Testosterone in males with COVID-19: A 7-month cohort study.

BACKGROUND: Circulating testosterone levels have been found to be reduced in men with severe acute respiratory syndrome coronavirus 2 infection, COVID-19, with lower levels being associated with more severe clinical outcomes. OBJECTIVES: We aimed to assess total testosterone levels and the prevalence of total testosterone still suggesting for hypogonadism at 7-month follow-up in a cohort of 121 men who recovered from laboratory-confirmed COVID-19. MATERIALS AND METHODS: Demographic, clinical, and hormonal values were collected for all patients. Hypogonadism was defined as total testosterone ≤9.2 nmol/L. The Charlson Comorbidity Index was used to score health-significant comorbidities. Descriptive statistics and multivariable linear and logistic regression models tested the association between clinical and laboratory variables and total testosterone levels at follow-up assessment. RESULTS: Circulating total testosterone levels increased at 7-month follow-up compared to hospital admittance (p < 0.0001), while luteinizing hormone and 17ß-estradiol levels significantly decreased (all p ≤ 0.02). Overall, total testosterone levels increased in 106 (87.6%) patients, but further decreased in 12 (9.9%) patients at follow-up, where a total testosterone level suggestive for hypogonadism was still observed in 66 (55%) patients. Baseline Charlson Comorbidity Index score (OR 0.36; p = 0.03 [0.14, 0.89]) was independently associated with total testosterone levels at 7-month follow-up, after adjusting for age, BMI, and IL-6 at hospital admittance. CONCLUSIONS: Although total testosterone levels increased over time after COVID-19, more than 50% of men who recovered from the disease still had circulating testosterone levels suggestive for a condition of hypogonadism at 7-month follow-up. In as many as 10% of cases, testosterone levels even further decreased. Of clinical relevance, the higher the burden of comorbid conditions at presentation, the lower the probability of testosterone levels recovery over time.

Hematopoietic Stem- and Progenitor-Cell Gene Therapy for Hurler Syndrome.

BACKGROUND: Allogeneic hematopoietic stem-cell transplantation is the standard of care for Hurler syndrome (mucopolysaccharidosis type I, Hurler variant [MPSIH]). However, this treatment is only partially curative and is associated with complications. METHODS: We are conducting an ongoing study involving eight children with MPSIH. At enrollment, the children lacked a suitable allogeneic donor and had a Developmental Quotient or Intelligence Quotient score above 70 (i.e., none had moderate or severe cognitive impairment). The children received autologous hematopoietic stem and progenitor cells (HSPCs) transduced ex vivo with an α-L-iduronidase (IDUA)-encoding lentiviral vector after myeloablative conditioning. Safety and correction of blood IDUA activity up to supraphysiologic levels were the primary end points. Clearance of lysosomal storage material as well as skeletal and neurophysiological development were assessed as secondary and exploratory end points. The planned duration of the study is 5 years. RESULTS: We now report interim results. The children's mean (±SD) age at the time of HSPC gene therapy was 1.9±0.5 years. At a median follow-up of 2.10 years, the procedure had a safety profile similar to that known for autologous hematopoietic stem-cell transplantation. All the patients showed prompt and sustained engraftment of gene-corrected cells and had supraphysiologic blood IDUA activity within a month, which was maintained up to the latest follow-up. Urinary glycosaminoglycan (GAG) excretion decreased steeply, reaching normal levels at 12 months in four of five patients who could be evaluated. Previously undetectable levels of IDUA activity in the cerebrospinal fluid became detectable after gene therapy and were associated with local clearance of GAGs. Patients showed stable cognitive performance, stable motor skills corresponding to continued motor development, improved or stable findings on magnetic resonance imaging of the brain and spine, reduced joint stiffness, and normal growth in line with World Health Organization growth charts. CONCLUSIONS: The delivery of HSPC gene therapy in patients with MPSIH resulted in extensive metabolic correction in peripheral tissues and the central nervous system. (Funded by Fondazione Telethon and others; ClinicalTrials.gov number, NCT03488394; EudraCT number, 2017-002430-23.).

Altered Frequency and Phenotype of HLA-G-Expressing DC-10 in Type 1 Diabetes Patients at Onset and in Subjects at Risk to Develop the Disease.

Type 1 diabetes (T1D) is a chronic autoimmune disease resulting in progressive destruction of ß-cells. Several factors affecting lymphocyte and antigen-presenting cells, including dendritic cells (DCs), contribute to defective maintenance of tolerance in T1D. DC-10 are a subset of human DCs involved in IL-10-mediated tolerance. A precise monitoring of DC-10 in the peripheral blood is possible thanks to the discovery of specific biomarkers. DC-10, being cells that naturally express HLA-G, may be used for the appropriate staging of the disease. By enumerating and phenotypically characterizing DC-10 in the peripheral blood of subjects at different stages of T1D development-first-degree relatives (FDRs) of T1D patients, without (Abneg) or with (Abpos) autoantibodies, T1D patients at onset, and age-matched healthy controls (HCs)-we showed that DC-10 contain a high proportion of HLA-G-expressing cells as compared with monocytes. We reported that a low frequency of DC-10 during disease development is paralleled with the increased proportion of pro-inflammatory cDC2 cells. Moreover, DC-10 number and phenotype differ from Abneg FDRs, Abpos FDRs, and T1D patients compared with HCs, and DC-10 from T1D patients express low levels of CD83. Finally, multiple regression analysis, considering DC-10 and HLA-G-related parameters, showed that Abneg FDRs are more similar to subjects with autoimmunity than to HCs. This is the first demonstration that impairment in DC-10 number and phenotype, specifically CD83 expression, is associated with risk of developing T1D, suggesting a possible use of CD83+ DC-10 to stratify individuals at risk of T1D in conjunction with classical prognostic factors.

Microglia-specific overexpression of α-synuclein leads to severe dopaminergic neurodegeneration by phagocytic exhaustion and oxidative toxicity.

Recent findings in human samples and animal models support the involvement of inflammation in the development of Parkinson's disease. Nevertheless, it is currently unknown whether microglial activation constitutes a primary event in neurodegeneration. We generated a new mouse model by lentiviral-mediated selective α-synuclein (αSYN) accumulation in microglial cells. Surprisingly, these mice developed progressive degeneration of dopaminergic (DA) neurons without endogenous αSYN aggregation. Transcriptomics and functional assessment revealed that αSYN-accumulating microglial cells developed a strong reactive state with phagocytic exhaustion and excessive production of oxidative and proinflammatory molecules. This inflammatory state created a molecular feed-forward vicious cycle between microglia and IFNγ-secreting immune cells infiltrating the brain parenchyma. Pharmacological inhibition of oxidative and nitrosative molecule production was sufficient to attenuate neurodegeneration. These results suggest that αSYN accumulation in microglia induces selective DA neuronal degeneration by promoting phagocytic exhaustion, an excessively toxic environment and the selective recruitment of peripheral immune cells.