Submitted by Chaylane Marques (chaylane.marques@ufpe.br) on 2015-03-12T19:35:48Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_Jaqueline de Azevedo Silva.pdf: 1480397 bytes, checksum: b38b99c8bc543a2c2b3933d0bb630f45 (MD5) / Made available in DSpace on 2015-03-12T19:35:48Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_Jaqueline de Azevedo Silva.pdf: 1480397 bytes, checksum: b38b99c8bc543a2c2b3933d0bb630f45 (MD5) Previous issue date: 2012 / CNPQ; CAPES; FACEPE / O Lúpus Eritematoso Sistêmico (LES) é uma das mais relevantes desordens autoimunes no mundo com a prevalência variando entre 20 a 150 casos a cada 100.000 indivíduos. A formação de autoanticorpos e a deposição de imunocomplexos na circulação sanguínea é um dos principais mecanismos patogênicos da doença. Além disso, o LES é caracterizado por um diversificado quadro de manifestações clínicas que varia de paciente para paciente. A genética do LES é complexa e caracteriza-se pela participação de diversos genes atuando em conjunto na etiopatogênese da doença. Neste trabalho foi estudada a susceptibilidade dos polimorfismos nos genes LIG4, RAD52, VDR e IFIH1 ao LES e suas manifestações clínicas. Os genes LIG4 e RAD52 são codificadores de enzimas de reparo do DNA e os danos ao DNA são potenciais ativadores da resposta imune. O VDR (receptor de vitamina D) atua como modulador da resposta imune através da ação da vitamina D. Uma vez que pacientes com LES apresentam com frequência alterações dos níveis séricos da vitamina D e o VDR está presente em importantes células do sistema imune, o VDR aparece como um candidato promissor à susceptibilidade ao LES. O gene IFIH1 é capaz de induzir a ativação do IFN e, como esta citocina apresenta papel chave na patogênese do LES, a ação deste gene tem papel importante na resposta imune. Nos gene LIG4 e RAD52 foram analisados quatro (rs10131, rs1805386, rs1805388 e rs3093740) e três (rs1051669, rs1106467 e rs3748522) SNPs respectivamente, em 158 pacientes e 212 controles da população do Sudeste Brasileiro. Os polimorfismos nos genes LIG4 e RAD52 não apresentaram associação ao LES nem às suas manifestações clínicas na população analisada. Os polimorfismos analisados no gene VDR (rs11168268, rs2248098, rs1540339, rs4760648 e rs3890733) não apresentaram associação com o LES, no entanto apresentaram associação com as seguintes manifestações clínicas: alterações cutâneas com genótipo G/G (rs11168269, OR=3,01e p=0,035), anticorpo anti ds-DNA com o genótipo C/T (rs4760648, OR=0,369 e p=0,03), alterações imunológicas com o genótipo G/G (rs2248098, OR=2,82 e p=0,04) e artrite com o genótipo T/T (rs3890733, OR=17,05 e p= 0,001). No gene IFIH1 foram analisados dois polimorfismos (rs6432714 e rs10930046) e o genótipo C/C (rs10930046) foi associado com ao LES (p=0.032), no entanto, não foi encontrada associação com as manifestações clínicas. Os resultados obtidos neste estudo forneceram dados para o primeiro estudo de associação com LES e os genes de reparo LIG4 e RAD52. Além disso, os genes VDR e IFIH1 foram testados pela primeira vez na população brasileira, contribuindo como marcadores não somente na doença, mas nas manifestações clínicas do LES.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19625号 / 医博第4132号 / 新制||医||1015(附属図書館) / 32661 / 京都大学大学院医学研究科医学専攻 / (主査)教授 高田 穣, 教授 松田 文彦, 教授 小泉 昭夫 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Les maladies inflammatoires de l’intestin (MII), incluant la maladie de Crohn et la colite ulcéreuse, sont des maladies chroniques qui résultent d’un dérèglement de la réponse immunitaire aux microorganismes de la lumière intestinale. Des études de séquençages réalisées par le laboratoire du Dr. Rioux, avec ses collègues du International IBD Genetics Consortium ont identifié quatre variants rares, indépendants et causals pour les MII, dans le gène IFIH1. La protéine d’IFIH1 (MDA5) interagit avec certains virus à ARN, afin de déclencher une réponse antivirale de l’immunité innée. Nous avions émis l’hypothèse que ces variants dans IFIH1 diminuaient la réponse antivirale de l’épithélium intestinal, suite à une infection. Nous avons d’abord travaillé avec des lignées cellulaires lymphoblastoïdes (LCLs) obtenues à partir d’individus atteints de MII et qui sont homozygotes ou hétérozygotes composés pour ces variants, ainsi qu’à partir d’individus contrôles (IFIH1 wt). Ces LCLs ont été reprogrammées en cellules souches pluripotentes induites humaines, avant d’être différenciées en cultures épithéliales intestinales. Nos résultats ont d’abord confirmé l’impact des variants sur la structure génique et protéique (IFIH1/MDA5), dans ces modèles cellulaires. Puis, la réponse antivirale a été induite, grâce à la stimulation avec des agents (moléculaire et viral) connus pour stimulés la protéine MDA5. Nous avons démontré que ces variants dans IFIH1 induisaient effectivement une moins grande réponse antivirale, caractérisée par une plus faible expression d’IFNs, comparativement aux contrôles. Finalement, la modulation des IFNs constituerait une avenue potentiellement intéressante pour le traitement des patients atteints des MII et porteurs des variants causals. / Inflammatory Bowel Disease (IBD), including Cronh’s disease and ulcerative colitis, are chronic inflammatory diseases of the gastro-intestinal tract. IBD is associated with a disturbance of the immune response to the microorganisms of the intestinal lumen. Sequencing studies conducted by the laboratory of Dr. John Rioux, in collaboration with his colleagues of the International IBD Genetics Consortium, identified four rare and independent variants in IFIH1, associated to IBD. The protein of IFIH1 (MDA5) interacts with certain RNA viruses to trigger the innate mechanism of antiviral defense. Our hypothesis was that these IFIH1 variants decreased the intestinal epithelial antiviral response, following an infection. We first worked with lymphoblastoid cell lines (LCLs) obtained from IBD patients who are homozygotes or compound heterozygotes for the different variants, as well as from control individuals (IFIH1 wt). These LCLs were reprogrammed into human induced Pluripotent Stem Cells (hiPSCs), before being differentiated into intestinal epithelial cultures. Our results first confirmed the impact the variants on the genetic and protein structure for these models. Then, the antiviral response was triggered by the stimulation of LCLs and intestinal epithelial cells, with agents (molecular and viral) known to stimulate MDA5. We have demonstrated that these IFIH1 variants did indeed induce a lower antiviral response, characterized by lower IFNs expression, compared to control cell lines. Finally, modulation of IFNs could be an interesting avenue for the treatment of IBD patients with the causal variants.

Human immunodeficiency virus type 1 (HIV-1) is a lentivirus that causes acquired immunodeficiency syndrome (AIDS). Since the first cases of AIDS were described in 1981, HIV-1 has become one of the most serious public health threats in the world. There are approximately 38 million people worldwide currently living with HIV-1. 28 million of these people have access to antiretroviral therapy (ART) that is highly effective in reducing viral load to undetectable levels, thereby curbing the risk of viral transmission and preventing progression to AIDS. Despite their effectiveness in suppressing HIV-1 viremia, systemic inflammation remains as a hallmark of HIV-1 infection in vivo. This persistent immune activation is often associated with non-AIDS related complications, including elevated risk of neurocognitive and cardiovascular disorders. Several different mechanisms may contribute to this chronic immune activation and inflammation in people living with HIV-1 on ART. One of the contributing factors might be HIV-1 RNA expressed from the provirus. Even though ART potently suppresses HIV-1 replication, it fails to eradicate proviruses established prior to initiation of ART. Ongoing activation of CD4+ T cells and macrophages by HIV-1 proviral transcripts might contribute to the persistent inflammation that remains even after HIV-1 suppression by ART. Previously, our laboratory has shown that induction of innate immune signaling after HIV-1 challenge of primary human dendritic cells (DCs), macrophages, or CD4+ T cells requires integration, transcription from the nascent provirus, and nuclear export of intron-containing HIV-1 RNA through the Rev-CRM1 pathway. However, these studies failed to identify the innate immune sensor of intron-containing HIV-1 RNA. Here we conducted a targeted loss-of-function screen, using shRNA-expressing lentivectors in human DCs to identify this innate immune receptor. Of the twenty-one candidate genes targeted for knockdown by shRNA, the innate immune response to HIV-1 was inhibited only by knockdown of IFIH1, MAVS, and XPO1. The effect of IFIH1 and MAVS knockdowns on HIV-1-induced immune activation was confirmed in macrophages, and rescue of the knockdown with non-targetable coding sequence showed that IFIH1 protein was required. IFIH1 mutants that are defective for interaction with MAVS blocked activation, demonstrating that MAVS acts downstream of IFIH1 in this system. Since both IFIH1 and DDX58 signal via MAVS, the specificity of HIV-1 RNA detection by IFIH1 was demonstrated by the fact that DDX58 knockdown had no effect on activation; the IFIH1-specific inhibitor Nipah virus V protein blocked the activation by HIV-1. RNA-Seq showed that IFIH1-knockdown in DCs globally disrupted the induction of IFN-1-stimulated genes. Altogether, results presented in this thesis reveal that IFIH1 is required for innate immune activation by intron-containing RNA from the HIV-1 provirus, and potentially contributes to chronic inflammation in people living with HIV-1.