T follicular regulatory cells in human adaptive immunity and autoimmunity

Tese de doutoramento, Medicina (Imunologia), Universidade de Lisboa, Faculdade de Medicina, 2018Germinal centres (GC) are formed during adaptive immune responses to defend our body against invading pathogens. During GC reactions antigen-specific high-affinity antibodies are produced through an intricated T – B cell crosstalk. In the last decades, the identification of a T cell subset specialized in controlling GC reactions, the T follicular helper (Tfh) cells, was a major scientific breakthrough. Within GCs, Tfh cells support B cell affinity maturation and class switch recombination. In addition, T follicular regulatory (Tfr) cells were recently described as GC regulators. Tfr cells are derived from thymic Foxp3+ Treg cells and undergo a still poorly defined, Bcl-6-dependent, multistep differentiation pathway within secondary lymphoid tissues.« Throughout this process, Tfr cells enforce tolerance and limit autoantibody-mediated autoimmune diseases by regulating Tfh – GC B cell interactions. Although the biology of human blood and tissue Tfh cells has been established, the biology and ontogeny of human blood Tfr cells, defined as CXCR5+Foxp3+ T cells, still remains elusive. This work focused on Tfr cells in human adaptive immunity and autoimmunity. We have shown that human blood CXCR5+Foxp3+ Treg cells constitute a circulating counterpart of GC bona fide tissue Tfr cells. Indeed, those blood Tfr cells increase after the induction of GC responses by vaccination, and they are absent from human umbilical cord blood, where non-maternal foreign antigens are not present. However, blood Tfr cells are immature cells which fail to fully regulate humoral responses, suggesting these cells are not fully competent Tfr cells. To address the biological significance of blood Tfr cells in autoimmunity, we studied patients with a systemic autoimmune disease (Sjögren’s syndrome) characterized by abnormal generation of autoantibodies within lymphoid structures ectopically formed in exocrine glands. Unexpectedly, Sjögren’s syndrome patients had a striking increase in blood Tfr cells, as well as an increase in blood Tfr/Tfh ratio. In addition, we established the relationship between blood Tfr and Tfh cells and abnormal immune responses in the target organ of an autoimmune disease. Patients with ectopic lymphoid structures in their salivary glands had the highest blood Tfr/Tfh ratio, suggesting this ratio may be a novel biomarker of ectopic lymphoid activity in Sjögren syndrome. Autoimmunity of follicular origin poses a considerable clinical challenge. Following the discovery of Tfr cells as GC “fine tune” regulators, targeting Tfr cell responses may constitute a novel and highly selective approach for the treatment of autoantibody-mediated autoimmune diseases.Durante as respostas imunológicas adaptativas formam-se centros germinativos, onde, através de interações celulares complexas, entre linfócitos T e linfócitos B, são produzidos anticorpos. Os anticorpos produzidos nos centros germinativos apresentam elevada afinidade e especificidade contra os antigénios que iniciaram a resposta imunológica, constituindo, por isso, um elemento essencial na defesa do organismo face a agentes invasores. Nas últimas décadas foi identificado o tipo de linfócitos T que, por interagir com linfócitos B de forma especializada, é responsável pela formação dos centros germinativos: as células T foliculares de ajuda (Tfh). No centro germinativo, as células Tfh são responsáveis pela maturação de afinidade e mudança de classe das imunoglobulinas dos linfócitos B. Recentemente foi descrito um outro tipo de linfócitos T especializado na regulação das interações entre as células Tfh e os linfócitos B que ocorrem nos centros germinativos, evitando a desregulação destas respostas e prevenindo o desenvolvimento de doenças autoimunes. Estes linfócitos designam-se células T foliculares reguladoras (Tfr). As células Tfr diferenciam-se nos órgãos linfoides secundários a partir de células T reguladoras formadas no timo e que expressam Foxp3. Esta via de diferenciação é ainda pouco conhecida, mas envolve vários processos que dependem da aquisição de expressão de Bcl-6 por parte das células T reguladoras. Contudo, o significado biológico e a função destas células (definidas como células T CXCR5+Foxp3+) no sangue dos seres humanos não é conhecido, contrariamente ao que acontece com as células Tfh, cuja biologia já foi estabelecida em humanos. Este trabalho foi desenvolvido com o objetivo de estudar as células Tfr nas respostas imunológicas adaptativas (fisiológicas) e nas doenças autoimunes, em seres humanos. O trabalho experimental desenvolvido permitiu estabelecer, pela primeira vez, que as células T CXCR5+Foxp3+ existentes no sangue humano constituem um compartimento circulante das células Tfr formadas nos órgãos linfoides secundários. De facto, verificou-se um aumento destas células sanguíneas estas células após a vacinação e a sua ausência no sangue do cordão umbilical, onde não existem antigénios exógenos, para além dos maternos. Contudo, as células Tfr do sangue são imaturas e não são capazes de regular eficazmente a produção de anticorpos, pelo que as células T CXCR5+Foxp3+ do sangue humano não apresentam a mesma diferenciação funcional que as células Tfr dos órgãos linfoides secundários. Para estudar a importância destas células nas doenças autoimunes estudaram-se doentes com síndrome de Sjögren. Esta doença autoimune sistémica é caracterizada pela formação ectópica de estruturas linfoides nas glândulas exócrinas. A produção de autoanticorpos ocorre maioritariamente nestas estruturas onde existem interações T – B patológicas. Contrariamente ao esperado, as células Tfr, descritas como apresentando funções reguladores, encontram-se aumentadas no sangue dos doentes com síndrome de Sjögren, tal como o rácio Tfr/Tfh. Este trabalho permitiu ainda estabelecer a relação entre as células Tfh e Tfr e os fenómenos imunológicos que ocorrem nos órgão-alvo desta doença autoimune. De facto, os doentes com formação ectópica de estruturas linfoides nas glândulas salivares são os que apresentam os valores mais elevados do rácio Tfr/Tfh, pelo que este rácio pode constituir um novo marcador para a identificação de doentes com formação ectópica de estruturas linfoides. As doenças autoimunes cuja patogénese está relacionada com a perda de tolerância nos centros germinativos continuam a ser um desafio clinico e terapêutico. O desenvolvimento de fármacos capazes de modular a resposta células Tfr pode constituir uma nova abordagem terapêutica para estas doenças autoimunes.Fundação para a Ciência e a Tecnologia (FCT), SFRH/SINTD/96663/201

Regulation of the Germinal Center Response

The germinal center (GC) is a specialized microstructure that forms in secondary lymphoid tissues, producing long-lived antibody secreting plasma cells and memory B cells, which can provide protection against reinfection. Within the GC, B cells undergo somatic mutation of the genes encoding their B cell receptors which, following successful selection, can lead to the emergence of B cell clones that bind antigen with high affinity. However, this mutation process can also be dangerous, as it can create autoreactive clones that can cause autoimmunity. Because of this, regulation of GC reactions is critical to ensure high affinity antibody production and to enforce self-tolerance by avoiding emergence of autoreactive B cell clones. A productive GC response requires the collaboration of multiple cell types. The stromal cell network orchestrates GC cell dynamics by controlling antigen delivery and cell trafficking. T follicular helper (Tfh) cells provide specialized help to GC B cells through cognate T-B cell interactions while Foxp3+ T follicular regulatory (Tfr) cells are key mediators of GC regulation. However, regulation of GC responses is not a simple outcome of Tfh/Tfr balance, but also involves the contribution of other cell types to modulate the GC microenvironment and to avoid autoimmunity. Thus, the regulation of the GC is complex, and occurs at multiple levels. In this review we outline recent developments in the biology of cell subsets involved in the regulation of GC reactions, in both secondary lymphoid tissues, and Peyer's patches (PPs). We discuss the mechanisms which enable the generation of potent protective humoral immunity whilst GC-derived autoimmunity is avoided

Stability of hybrid versus vaccine immunity against BA.5 infection over 8 months

© 2022 Elsevier Ltd. All rights reserved.The coverage of SARS-CoV-2 vaccination in large parts of the world, together with the high number of breakthrough infections, especially following the emergence of Omicron subvariants, makes hybrid immunity (resulting from vaccine and infection) common. Hybrid immunity, particularly after BA.1 or BA.2 infection, confers substantial protection against the BA.5 infection. However, although the waning of protection afforded by natural infection in non-vaccinated individuals or by vaccination has been well documented, the stability of hybrid immunity, specifically against the BA.5 subvariant, now dominant in many countries, has not been thoroughly addressed.info:eu-repo/semantics/publishedVersio

Rapidly progressive coronary aneurysm: a rare case of isolated coronary vasculitis with recurrent myocardial infarction

© 2022 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation. This article is available under the Creative Commons CC-BY-NC-ND license and permits non-commercial use of the work as published, without adaptation or alteration provided the work is fully attributed.Isolated coronary arteritis without systemic involvement in adults is exceedingly rare. A 60-year-old patient developed recurrent non–ST-segment elevation myocardial infarctions for 1 year. After an initial coronary angiogram that was normal, serial angiograms showed de novo aneurysm formation. The patient responded favorably to corticosteroids, supporting the diagnosis of isolated coronary arteritis.info:eu-repo/semantics/publishedVersio

Different antibody-associated autoimmune diseases have distinct patterns of T follicular cell dysregulation

© The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Autoantibodies are produced within germinal centers (GC), in a process regulated by interactions between B, T follicular helper (Tfh), and T follicular regulatory (Tfr) cells. The GC dysregulation in human autoimmunity has been inferred from circulating cells, albeit with conflicting results due to diverse experimental approaches. We applied a consistent approach to compare circulating Tfr and Tfh subsets in patients with different autoimmune diseases. We recruited 97 participants, including 72 patients with Hashimoto's thyroiditis (HT, n = 18), rheumatoid arthritis (RA, n = 16), or systemic lupus erythematosus (SLE, n = 32), and 31 matched healthy donors (HD). We found that the frequency of circulating T follicular subsets differed across diseases. Patients with HT had an increased frequency of blood Tfh cells (p = 0.0215) and a reduced Tfr/Tfh ratio (p = 0.0338) when compared with HD. This was not observed in patients with systemic autoimmune rheumatic diseases (RA, SLE), who had a reduction in both Tfh (p = 0.0494 and p = 0.0392, respectively) and Tfr (p = 0.0003 and p = 0.0001, respectively) cells, resulting in an unchanged Tfr/Tfh ratio. Activated PD-1+ICOS+Tfh and CD4+PD-1+CXCR5-Tph cells were raised only in patients with SLE (p = 0.0022 and p = 0.0054), without association with disease activity. Our data suggest that GC dysregulation, assessed by T follicular subsets, is not uniform in human autoimmunity. Specific patterns of dysregulation may become potential biomarkers for disease and patient stratification.This work was supported by the Fundação para a Ciência e Tecnologia, Portugal (EJPRD/0003/2019).info:eu-repo/semantics/publishedVersio

Genotyping of polymorphisms associated with male-sterility systems in onion accessions adapted for cultivation in Brazil

A produção em escala comercial de sementes híbridas de cebola (Allium cepa) tem sido conduzida com o emprego de dois sistemas de macho-esterilidade do tipo genética-citoplasmática (CMS-S e CMS-T) em associação ao citoplasma normal (macho-fértil). No entanto, a análise molecular desses diferentes tipos citoplasmáticos ainda não está disponível para um grande número de acessos de cebola adaptados para cultivo em regiões tropicais. Além de adaptação às condições edafoclimáticas do Brasil, muitos desses acessos apresentam tolerância a doenças, sendo de potencial valor como genitores de híbridos. O presente trabalho visou identificar os tipos citoplasmáticos de acessos de cebola de diferentes grupos morfoagronômicos de interesse para o melhoramento genético no Brasil, usando a reação da polimerase em cadeia (PCR) com 'primers' específicos para regiões polimórficas do genoma mitocondrial de cebola. Foi observada, nos 66 acessos amostrados, a presença dos três principais tipos de citoplasma descritos para cebola (S, N e T). Foi constatada maior frequência do citoplasma S (56%) seguido do citoplasma T (25,8%). Em 18,2% das amostras, foi encontrado exclusivamente o citoplasma N. Essa caracterização pode ser útil para guiar a escolha de materiais genéticos dentro dos programas de melhoramento com objetivo de desenvolver cultivares híbridas adaptadas às condições tropicais

The Brazilian Developments on the Regional Atmospheric Modeling System (BRAMS 5.2): An Integrated Environmental Model Tuned for Tropical Areas

We present a new version of the Brazilian developments on the Regional Atmospheric Modeling System where different previous versions for weather, chemistry and carbon cycle were unified in a single integrated software system. The new version also has a new set of state-of-the-art physical parameterizations and greater computational parallel and memory usage efficiency. Together with the description of the main features are examples of the quality of the transport scheme for scalars, radiative fluxes on surface and model simulation of rainfall systems over South America in different spatial resolutions using a scale-aware convective parameterization. Besides, the simulation of the diurnal cycle of the convection and carbon dioxide concentration over the Amazon Basin, as well as carbon dioxide fluxes from biogenic processes over a large portion of South America are shown. Atmospheric chemistry examples present model performance in simulating near-surface carbon monoxide and ozone in Amazon Basin and Rio de Janeiro megacity. For tracer transport and dispersion, it is demonstrated the model capabilities to simulate the volcanic ash 3-d redistribution associated with the eruption of a Chilean volcano. Then, the gain of computational efficiency is described with some details. BRAMS has been applied for research and operational forecasting mainly in South America. Model results from the operational weather forecast of BRAMS on 5 km grid spacing in the Center for Weather Forecasting and Climate Studies, INPE/Brazil, since 2013 are used to quantify the model skill of near surface variables and rainfall. The scores show the reliability of BRAMS for the tropical and subtropical areas of South America. Requirements for keeping this modeling system competitive regarding on its functionalities and skills are discussed. At last, we highlight the relevant contribution of this work on the building up of a South American community of model developers

The Brazilian developments on the Regional Atmospheric Modeling System (BRAMS 5.2): an integrated environmental model tuned for tropical areas

We present a new version of the Brazilian developments on the Regional Atmospheric Modeling System (BRAMS), in which different previous versions for weather, chemistry, and carbon cycle were unified in a single integrated modeling system software. This new version also has a new set of state-of-the-art physical parameterizations and greater computational parallel and memory usage efficiency. The description of the main model features includes several examples illustrating the quality of the transport scheme for scalars, radiative fluxes on surface, and model simulation of rainfall systems over South America at different spatial resolutions using a scale aware convective parameterization. Additionally, the simulation of the diurnal cycle of the convection and carbon dioxide concentration over the Amazon Basin, as well as carbon dioxide fluxes from biogenic processes over a large portion of South America, are shown. Atmospheric chemistry examples show the model performance in simulating near-surface carbon monoxide and ozone in the Amazon Basin and the megacity of Rio de Janeiro. For tracer transport and dispersion, the model capabilities to simulate the volcanic ash 3-D redistribution associated with the eruption of a Chilean volcano are demonstrated. The gain of computational efficiency is described in some detail. BRAMS has been applied for research and operational forecasting mainly in South America. Model results from the operational weather forecast of BRAMS on 5 km grid spacing in the Center for Weather Forecasting and Climate Studies, INPE/Brazil, since 2013 are used to quantify the model skill of near-surface variables and rainfall. The scores show the reliability of BRAMS for the tropical and subtropical areas of South America. Requirements for keeping this modeling system competitive regarding both its functionalities and skills are discussed. Finally, we highlight the relevant contribution of this work to building a South American community of model developers.CNPqFAPESPEarth System Research Laboratory at the National Oceanic and Atmospheric Administration (ESRL/NOAA), Boulder, USAInst Nacl Pesquisas Espaciais, Ctr Previsao Tempo & Estudos Climat, Cachoeira Paulista, SP, BrazilDiv Ciência da Computação, Instituto Tecnológico de Aeronáutica, São José dos Campos, SP, BrazilUniv Estadual Paulista Unesp, Fac Ciencias, Bauru, SP, BrazilCtr Meteorol Bauru IPMet, Bauru, SP, BrazilUniv Fed Sao Paulo, Dept Ciencias Ambientais, Diadema, SP, BrazilUniv Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Sao Paulo, SP, BrazilUniv Fed Campina Grande, Dept Ciencias Atmosfer, Campina Grande, PB, BrazilEmbrapa Informat Agr, Campinas, SP, BrazilUniv Fed Sao Paulo, Inst Ciencia & Tecnol, Sao Jose Dos Campos, SP, BrazilUniv Fed Rio Grande do Norte, Dept Ciencias Atmosfer & Climat, Programa Pos Grad Ciencias Climat, Natal, RN, BrazilInst Nacl Pesquisas Espaciais, Ctr Ciencias Sistema, Sao Jose Dos Campos, SP, BrazilUniv Fed Sao Joao Del Rei, Dept Geociencias, Sao Joao Del Rei, MG, BrazilInst Nacl Pesquisas Espaciais, Lab Associado Computacao & Matemat Aplica, Sao Jose Dos Campos, BrazilUniv Evora, Inst Ciencias Agr & Ambientais Mediterr, Evora, PortugalUniv Lusofona Humanidades & Tecnol, Ctr Interdisciplinar Desenvolvimento Ambient Gest, Lisbon, PortugalUniv Fed Pelotas, Fac Meteorol, Pelotas, RS, BrazilUnive Tecnol Fed Parana, Londrina, PR, BrazilNASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Goddard Earth Sci Technol & Res Global Modeling &, Greenbelt, MD USAUniv Fed Sao Paulo, Inst Ciencia & Tecnol, Sao Jose Dos Campos, SP, BrazilUniv Fed Sao Paulo, Inst Ciencia & Tecnol, Sao Jose Dos Campos, SP, BrazilCNPq: 306340/2011-9FAPESP: 2014/01563-1FAPESP: 2015/10206-0FAPESP: 2014/01564-8Web of Scienc