Autoimmune amelogenesis imperfecta in patients with APS-1 and coeliac disease.

Ameloblasts are specialized epithelial cells in the jaw that have an indispensable role in tooth enamel formation-amelogenesis1. Amelogenesis depends on multiple ameloblast-derived proteins that function as a scaffold for hydroxyapatite crystals. The loss of function of ameloblast-derived proteins results in a group of rare congenital disorders called amelogenesis imperfecta2. Defects in enamel formation are also found in patients with autoimmune polyglandular syndrome type-1 (APS-1), caused by AIRE deficiency3,4, and in patients diagnosed with coeliac disease5-7. However, the underlying mechanisms remain unclear. Here we show that the vast majority of patients with APS-1 and coeliac disease develop autoantibodies (mostly of the IgA isotype) against ameloblast-specific proteins, the expression of which is induced by AIRE in the thymus. This in turn results in a breakdown of central tolerance, and subsequent generation of corresponding autoantibodies that interfere with enamel formation. However, in coeliac disease, the generation of such autoantibodies seems to be driven by a breakdown of peripheral tolerance to intestinal antigens that are also expressed in enamel tissue. Both conditions are examples of a previously unidentified type of IgA-dependent autoimmune disorder that we collectively name autoimmune amelogenesis imperfecta.

The Role of Interferon-γ in Autoimmune Polyendocrine Syndrome Type 1.

BACKGROUND: Autoimmune polyendocrine syndrome type 1 (APS-1) is a life-threatening, autosomal recessive syndrome caused by autoimmune regulator (AIRE) deficiency. In APS-1, self-reactive T cells escape thymic negative selection, infiltrate organs, and drive autoimmune injury. The effector mechanisms governing T-cell-mediated damage in APS-1 remain poorly understood. METHODS: We examined whether APS-1 could be classified as a disease mediated by interferon-γ. We first assessed patients with APS-1 who were participating in a prospective natural history study and evaluated mRNA and protein expression in blood and tissues. We then examined the pathogenic role of interferon-γ using Aire-/-Ifng-/- mice and Aire-/- mice treated with the Janus kinase (JAK) inhibitor ruxolitinib. On the basis of our findings, we used ruxolitinib to treat five patients with APS-1 and assessed clinical, immunologic, histologic, transcriptional, and autoantibody responses. RESULTS: Patients with APS-1 had enhanced interferon-γ responses in blood and in all examined autoimmunity-affected tissues. Aire-/- mice had selectively increased interferon-γ production by T cells and enhanced interferon-γ, phosphorylated signal transducer and activator of transcription 1 (pSTAT1), and CXCL9 signals in multiple organs. Ifng ablation or ruxolitinib-induced JAK-STAT blockade in Aire-/- mice normalized interferon-γ responses and averted T-cell infiltration and damage in organs. Ruxolitinib treatment of five patients with APS-1 led to decreased levels of T-cell-derived interferon-γ, normalized interferon-γ and CXCL9 levels, and remission of alopecia, oral candidiasis, nail dystrophy, gastritis, enteritis, arthritis, Sjögren's-like syndrome, urticaria, and thyroiditis. No serious adverse effects from ruxolitinib were identified in these patients. CONCLUSIONS: Our findings indicate that APS-1, which is caused by AIRE deficiency, is characterized by excessive, multiorgan interferon-γ-mediated responses. JAK inhibition with ruxolitinib in five patients showed promising results. (Funded by the National Institute of Allergy and Infectious Diseases and others.).

Breakdown of Immune Tolerance in AIRE-Deficient Rats Induces a Severe Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy-like Autoimmune Disease.

Autoimmune regulator (AIRE) deficiency in humans induces a life-threatening generalized autoimmune disease called autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), and no curative treatments are available. Several models of AIRE-deficient mice have been generated, and although they have been useful in understanding the role of AIRE in central tolerance, they do not reproduce accurately the APECED symptoms, and thus there is still a need for an animal model displaying APECED-like disease. We assessed, in this study, the potential of the rat as an accurate model for APECED. In this study, we demonstrate that in rat, AIRE is expressed by MHC class II (MCH-II)+ and MHC-II- medullary thymic epithelial cells in thymus and by CD4int conventional dendritic cells in periphery. To our knowledge, we generated the first AIRE-deficient rat model using zinc-finger nucleases and demonstrated that they display several of the key symptoms of APECED disease, including alopecia, skin depigmentation, and nail dystrophy, independently of the genetic background. We observed severe autoimmune lesions in a large spectrum of organs, in particular in the pancreas, and identified several autoantibodies in organs and cytokines such as type I IFNs and IL-17 at levels similar to APECED. Finally, we demonstrated a biased Ab response to IgG1, IgM, and IgA isotypes. Altogether, our data demonstrate that AIRE-deficient rat is a relevant APECED animal model, opening new opportunity to test curative therapeutic treatments.

Portuguese Results of the ETICC Study: Impact of the Pandemic COVID-19 in the Diagnosis and Management of Colorectal Cancer in 2020 in Portuguese Hospitals.

Introduction: The outbreak of coronavirus disease 2019 (COVID-19) had affected clinical practice in several ways, including the restriction of nonessential endoscopic procedures. Therefore, our aim was to evaluate how colorectal cancer (CRC) diagnosis and management was affected during the first year of pandemics in Portugal. Methods: This is a Portuguese substudy of the French retrospective multicentric study ETICC (Etude de l'Impact de la pandémie COVID-19 sur le diagnostic et la prise en charge du Cancer Colorectal). We compared patients' characteristics, clinical manifestations, CRC staging at diagnosis, delay to first medical appointment, histological diagnosis, surgical and medical treatments between the year previous to the pandemics (control) and the first year of pandemics. Results: We included 766 patients: 496 in the control group and 270 in the COVID group. There was no significant difference in CRC staging at diagnosis between both groups, with 21% being diagnosed as metastatic in the control group and 22% in the first year of pandemics (p = 0.770). Contrary to what happened in France, there was a significant decrease in CRC diagnosis in asymptomatic patients (25-8.4%; p < 0.001) and after a positive fecal immunochemical test (20.8-11.3%; p = 0.002) during the pandemics. Although the increase in the overall complication rate at diagnosis was nonsignificant, in Portugal, there was a significant increase in diagnosis of abdominal occlusion (12.1-18.1%; p = 0.033). In Portugal, time between the beginning of symptoms and the first medical appointment significantly increased from a median of 50 days to 64 days during COVID (p < 0.001). On the contrary, time between histological diagnosis and tumor resection had significantly decreased from a median of 65 to 39 days (p < 0.001). Time between histological diagnosis and neoadjuvant treatment was not statistically different (median of 64-67 days; p = 0.590), as was time between histological diagnosis and palliative chemotherapy (median of 50-51 days; p = 1.000). Time from CRC resection and adjuvant treatment has significantly decreased from a median of 54 to 43 days (p = 0.001). Discussion: We found a significant impact in CRC diagnosis in the first year of pandemics, more pronounced than what was found in France. These are likely related not only with the closing of endoscopy units but also with the difficulties patients had in finding an appointment with their general practitioners. On the other hand, both in France and Portugal, the first year of pandemics did not worsen CRC staging at diagnosis and did not significantly affect medical and surgical treatments once the diagnosis was made.

Introdução: A pandemia provocada pelo coronovírus (COVID-19) condicionou a prática clínica de múltiplas formas, incluindo a restrição a exames endoscópicos não urgentes. Por este motivo, decidimos avaliar o impacto do primeiro ano de pandemia no diagnóstico e tratamento do cancro colorretal (CCR) em Portugal. Métodos: Este é um subestudo do estudo Francês retrospetivo multicêntrico ETICC (Etude de l'Impact de la pandémie COVID-19 sur le diagnostic et la prise en charge du Cancer Colorectal). Foram comparadas as características dos doentes, manifestações clínicas, estadiamento do CCR ao diagnóstico, intervalos entre primeiro contacto médico neste contexto, diagnóstico histológico e tratamentos, entre o primeiro ano de pandemia e o ano precedente. Resultados: Foram incluídos 766 doentes, 496 no grupo controlo e 270 no grupo COVID. Em França e em Portugal não se verificou um agravamento no estadiamento do CCR à data do diagnóstico no primeiro ano de pandemia, com 21% dos casos metastáticos à data de diagnóstico no grupo controlo e 22% no primeiro ano da pandemia (p = 0.770). Contudo, apenas em Portugal se constatou uma redução significativa do número de CCR em doentes assintomáticos (25% para 8.4%; p < 0.001) ou após uma pesquisa de sangue oculto positiva (20.8% para 11.3%; p = 0.002) durante a pandemia. Apesar do aumento na taxa de complicações ao diagnóstico não ser significativa, em Portugal a taxa de diagnósticos em contexto de oclusão intestinal aumentou significativamente (12.1% para 18.1%; p = 0.033). Em Portugal, o tempo entre início dos sintomas e a primeira consulta médica aumentou significativamente, de uma mediana de 50 para 64 dias durante o COVID (p < 0.001). Por outro lado, o tempo entre diagnóstico histológico e resseção tumoral reduziu significativamente de 65 para 39 dias (p < 0.001). O tempo entre diagnóstico histológico e tratamento neoadjuvante (mediana de 64 para 67 dias; p = 0.590) ou quimioterapia paliativa (mediana de 50 para 51 dias; p = 1.000) não foi estatisticamente significativo, tendo decrescido significativamente o tempo entre resseção e adjuvância (mediana de 54 para 43 dias, p = 0.001). Discussão: Este estudo evidenciou um impacto significativo no diagnóstico de CCR durante o primeiro ano de pandemia, mais pronunciado que em França. Este achado dever-se-á não só à limitação do acesso aos exames endoscópicos, mas também à dificuldade da população portuguesa em aceder aos Cuidados de Saúde Primários. Por outro lado, tanto em França como em Portugal, no primeiro ano de pandemia não se verificou um agravamento no estadiamento ou atraso no tratamento médico e cirúrgico do CCR.

Anti-CD45RC antibody immunotherapy prevents and treats experimental autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome.

Targeted monoclonal antibody (mAb) therapies show great promise for the treatment of transplant rejection and autoimmune diseases by inducing more specific immunomodulatory effects than broadly immunosuppressive drugs routinely used. We recently described the therapeutic advantage of targeting CD45RC, expressed at high levels by conventional T (Tconv) cells (CD45RChi), their precursors, and terminally differentiated T (TEMRA) cells, but not by regulatory T cells (Tregs; CD45RClo/-). We demonstrated efficacy of anti-CD45RC mAb treatment in transplantation, but its potential has not been examined in autoimmune diseases. Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare genetic syndrome caused by loss-of-function mutations of autoimmune regulator (AIRE), a key central tolerance mediator, leading to abnormal autoreactive T cell responses and autoantibody production. Herein, we show that, in a rat model of APECED syndrome, anti-CD45RC mAb was effective for both prevention and treatment of autoimmune manifestations and inhibited autoantibody development. Anti-CD45RC mAb intervention depleted CD45RChi T cells, inhibited CD45RChi B cells, and restored the Treg/Tconv cell ratio and the altered Treg transcriptomic profile. In APECED patients, CD45RC was significantly increased in peripheral blood T cells, and lesioned organs from APECED patients were infiltrated by CD45RChi cells. Our observations highlight the potential role for CD45RChi cells in the pathogenesis of experimental and human APECED syndrome and the potential of anti-CD45RC antibody treatment.

AIRE deficiency, from preclinical models to human APECED disease.

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) is a rare life-threatening autoimmune disease that attacks multiple organs and has its onset in childhood. It is an inherited condition caused by a variety of mutations in the autoimmune regulator (AIRE) gene that encodes a protein whose function has been uncovered by the generation and study of Aire-KO mice. These provided invaluable insights into the link between AIRE expression in medullary thymic epithelial cells (mTECs), and the broad spectrum of self-antigens that these cells express and present to the developing thymocytes. However, these murine models poorly recapitulate all phenotypic aspects of human APECED. Unlike Aire-KO mice, the recently generated Aire-KO rat model presents visual features, organ lymphocytic infiltrations and production of autoantibodies that resemble those observed in APECED patients, making the rat model a main research asset. In addition, ex vivo models of AIRE-dependent self-antigen expression in primary mTECs have been successfully set up. Thymus organoids based on pluripotent stem cell-derived TECs from APECED patients are also emerging, and constitute a promising tool to engineer AIRE-corrected mTECs and restore the generation of regulatory T cells. Eventually, these new models will undoubtedly lead to main advances in the identification and assessment of specific and efficient new therapeutic strategies aiming to restore immunological tolerance in APECED patients.

Cross-Reactive Donor-Specific CD8+ Tregs Efficiently Prevent Transplant Rejection.

To reduce the use of non-specific immunosuppressive drugs detrimental to transplant patient health, therapies in development aim to achieve antigen-specific tolerance by promoting antigen-specific regulatory T cells (Tregs). However, identification of the natural antigens recognized by Tregs and the contribution of their dominance in transplantation has been challenging. We identify epitopes derived from distinct major histocompatibility complex (MHC) class II molecules, sharing a 7-amino acid consensus sequence positioned in a central mobile section in complex with MHC class I, recognized by cross-reactive CD8+ Tregs, enriched in the graft. Antigen-specific CD8+ Tregs can be induced in vivo with a 16-amino acid-long peptide to trigger transplant tolerance. Peptides derived from human HLA class II molecules, harboring the rat consensus sequence, also activate and expand human CD8+ Tregs, suggesting its potential in human transplantation. Altogether, this work should facilitate the development of therapies with peptide epitopes for transplantation and improve our understanding of CD8+ Treg recognition.