Objetivo: Uma série de casos sugerindo uma possível associação de pancreatite aguda (PA) e síndrome de ativação macrofágica (SAM) em lúpus eritematoso sistêmico pediátrico (LESP) foi reportada em dez crianças no nosso serviço, no entanto, não existem dados relativos à comparação entre PA e SAM em grandes populações de LESP e LES adulto (LESA). Métodos: Este estudo incluiu 362 pacientes LESP e 1.830 pacientes LESA. SAM foi diagnosticada de acordo com os critérios diagnósticos preliminares e PA de acordo com a presença de dor abdominal e/ou vômitos associados a um aumento de enzimas pancreáticas e/ou alterações radiológicas pancreáticas nos exames de ultrassonografia e/ou tomografia abdominal. Dados demográficos, características clínicas, SLEDAI-2K, SLICC/ACR-DI e tratamento foram avaliados. Resultados: A frequência de PA foi significantemente aumentada no LESP em comparação ao LESA [12/362 (3,3%) vs. 20/1830 (1,1%), p=0,003], com similar duração da PA nos dois grupos [22 (6-60) vs. 15 (4-90), dias, p=0,534]. As frequências de SAM (85% vs 30%, p=0,003) e óbito (31% vs. 0%; p=0,017) foram significantemente elevadas em crianças com PA comparadas com adultos com PA. Na análise dos pacientes com PA e SAM em comparação com os com somente PA sem SAM demonstrou que a idade dos pacientes com PA e SAM foi significantemente menor em comparação com aqueles sem SAM [15 (8,8- 55) vs. 33,5 (10,2-45,7) anos, p=0,007]. As frequências de febre (94% vs. 37%, p=0,001), leucopenia (82% vs. 19%, p=0,0001), trombocitopenia (65% vs. 19%, p=0,013), hipertrigliceridemia (87% vs. 42%, p=0,037) e hiperferritinemia (93% vs. 37%, p=0,011) foram significantemente aumentadas nos pacientes com PA e SAM comparados aos pacientes com somente PA. A concomitância de febre e hiperferritinemia foi significantemente mais freqüente no primeiro grupo (86% vs. 12%, p=0,0015). Conclusões: Este estudo forneceu novos dados que evidenciaram que SAM ocorreu na maioria dos LESP com PA com uma maior mortalidade em comparação com LESA. Além disso, foram identificados em pacientes com PA e SAM, um conjunto de parâmetros clínicos e laboratoriais associado com as duas complicações / Objective: We previously reported a case series of acute pancreatitis (AP) and macrophage activation syndrome (MAS) in childhood (cSLE) patients, however there are no data regarding the comparison of AP and MAS in large populations of cSLE and adult SLE (aSLE). Methods: This study included 362 cSLE and 1,830 aSLE patients. MAS was diagnosed according to preliminary diagnostic guidelines and AP according to the presence of abdominal pain or vomiting associated to an increase of pancreatic enzymes and/or pancreatic radiological abnormalities. Demographic data, clinical features, SLEDAI-2K, SLICC/ACR-DI and treatment were assessed. Results: Higher and significant frequency of AP in cSLE compared to aSLE patients [12/362(3.3%) vs. 20/1830(1.1%), p=0.003], with similar AP duration [22(6- 60) vs. 15(4-90) days, p=0.534]. MAS (85% vs. 30%, p=0.003) and death by MAS complication (31% vs. 0%, p=0.017) were significantly higher in children with AP compared with aSLE with AP. Further analysis of patients with AP and MAS compared with AP without MAS demonstrated that age in MAS patients was significantly lower compared with those without this complication [15(8.8-55) vs. 33.5(10.2-45.7) years, p=0.007]. The frequencies of fever (94% vs. 37%,p=0.001), leucopenia (82% vs. 19%,p=0.0001), thrombocytopenia (65% vs. 19%,p=0.013), hypertriglyceridemia (87% vs. 42%,p=0.037) and hyperferritinemia (93% vs. 37%,p=0.011) were also more frequently observed in AP patients with MAS compared in AP patients without MAS. Fever and hyperferritinemia concomitantly were more frequent in the former group (86% vs. 12%, p=0.0015). Conclusions: This study provides novel data demonstrating that MAS occur in the majority of cSLE with AP with a higher mortality compared to aSLE. In addition, we identified in AP patients, a cluster of MAS clinical and laboratorial parameters more associated with this complication

Objetivo: Uma série de casos sugerindo uma possível associação de pancreatite aguda (PA) e síndrome de ativação macrofágica (SAM) em lúpus eritematoso sistêmico pediátrico (LESP) foi reportada em dez crianças no nosso serviço, no entanto, não existem dados relativos à comparação entre PA e SAM em grandes populações de LESP e LES adulto (LESA). Métodos: Este estudo incluiu 362 pacientes LESP e 1.830 pacientes LESA. SAM foi diagnosticada de acordo com os critérios diagnósticos preliminares e PA de acordo com a presença de dor abdominal e/ou vômitos associados a um aumento de enzimas pancreáticas e/ou alterações radiológicas pancreáticas nos exames de ultrassonografia e/ou tomografia abdominal. Dados demográficos, características clínicas, SLEDAI-2K, SLICC/ACR-DI e tratamento foram avaliados. Resultados: A frequência de PA foi significantemente aumentada no LESP em comparação ao LESA [12/362 (3,3%) vs. 20/1830 (1,1%), p=0,003], com similar duração da PA nos dois grupos [22 (6-60) vs. 15 (4-90), dias, p=0,534]. As frequências de SAM (85% vs 30%, p=0,003) e óbito (31% vs. 0%; p=0,017) foram significantemente elevadas em crianças com PA comparadas com adultos com PA. Na análise dos pacientes com PA e SAM em comparação com os com somente PA sem SAM demonstrou que a idade dos pacientes com PA e SAM foi significantemente menor em comparação com aqueles sem SAM [15 (8,8- 55) vs. 33,5 (10,2-45,7) anos, p=0,007]. As frequências de febre (94% vs. 37%, p=0,001), leucopenia (82% vs. 19%, p=0,0001), trombocitopenia (65% vs. 19%, p=0,013), hipertrigliceridemia (87% vs. 42%, p=0,037) e hiperferritinemia (93% vs. 37%, p=0,011) foram significantemente aumentadas nos pacientes com PA e SAM comparados aos pacientes com somente PA. A concomitância de febre e hiperferritinemia foi significantemente mais freqüente no primeiro grupo (86% vs. 12%, p=0,0015). Conclusões: Este estudo forneceu novos dados que evidenciaram que SAM ocorreu na maioria dos LESP com PA com uma maior mortalidade em comparação com LESA. Além disso, foram identificados em pacientes com PA e SAM, um conjunto de parâmetros clínicos e laboratoriais associado com as duas complicações / Objective: We previously reported a case series of acute pancreatitis (AP) and macrophage activation syndrome (MAS) in childhood (cSLE) patients, however there are no data regarding the comparison of AP and MAS in large populations of cSLE and adult SLE (aSLE). Methods: This study included 362 cSLE and 1,830 aSLE patients. MAS was diagnosed according to preliminary diagnostic guidelines and AP according to the presence of abdominal pain or vomiting associated to an increase of pancreatic enzymes and/or pancreatic radiological abnormalities. Demographic data, clinical features, SLEDAI-2K, SLICC/ACR-DI and treatment were assessed. Results: Higher and significant frequency of AP in cSLE compared to aSLE patients [12/362(3.3%) vs. 20/1830(1.1%), p=0.003], with similar AP duration [22(6- 60) vs. 15(4-90) days, p=0.534]. MAS (85% vs. 30%, p=0.003) and death by MAS complication (31% vs. 0%, p=0.017) were significantly higher in children with AP compared with aSLE with AP. Further analysis of patients with AP and MAS compared with AP without MAS demonstrated that age in MAS patients was significantly lower compared with those without this complication [15(8.8-55) vs. 33.5(10.2-45.7) years, p=0.007]. The frequencies of fever (94% vs. 37%,p=0.001), leucopenia (82% vs. 19%,p=0.0001), thrombocytopenia (65% vs. 19%,p=0.013), hypertriglyceridemia (87% vs. 42%,p=0.037) and hyperferritinemia (93% vs. 37%,p=0.011) were also more frequently observed in AP patients with MAS compared in AP patients without MAS. Fever and hyperferritinemia concomitantly were more frequent in the former group (86% vs. 12%, p=0.0015). Conclusions: This study provides novel data demonstrating that MAS occur in the majority of cSLE with AP with a higher mortality compared to aSLE. In addition, we identified in AP patients, a cluster of MAS clinical and laboratorial parameters more associated with this complication

Le dysfonctionnement de l'exocytose des granules cytotoxiques est responsable d'une susceptibilité accrue aux pathogènes intracellulaires qui s'accompagne de l'activation continue et anarchique des lymphocytes cytotoxiques et des macrophages. Ce phénomène conduit à la lymphohistiocytose hémophagocytique (HLH), un syndrome auto-inflammatoire fatal en absence d'intervention thérapeutique. Les mutations des gènes codant pour la perforine (PRF-1) ou pour certaines des protéines impliquées dans la biogénèse ou le transport vésiculaire des granules cytotoxiques sont causales des formes familiales ou primaires de la HLH (FHL). La HLH fait également partie des complications secondaires aux infections à herpesviridae et à certains désordres immunologiques importants tels que l'arthrite juvénile idiopathique (SoJIA). Au moment d'entreprendre les travaux présentés dans ce manuscrit, le premier cas de HLH induite par une mutation menant à l'activation constitutive de la composante NLRC4 de l'inflammasome était décrit. L'inflammasome est une structure multimérique composée d'un récepteur cytosolique, de la protéine échafaud ASC et de la Caspase-1. Son activation mène à la maturation des pro-formes de l'IL-1β et l'IL-18 ainsi qu'à leur sécrétion. L'activation constitutive de NLRC4 étant suffisante au déclenchement de la HLH, nous avons tenté de comprendre si cette structure y était essentielle dans le cadre des défauts génétiques de cytotoxicité. Nous avons donc invalidé la protéine ASC ou Caspase-1 dans le modèle murin de HLH déficient pour la perforine (PRF1 -/-). Nous avons également testé l'hypothèse qu'un déficit de cytotoxicité pouvait expliquer le développement de la HLH chez les patients souffrant de SoJIA. Nos résultats montrent que l'inflammasome est nécessaire à la production d'IL-18 lors de la HLH mais qu'il n'est pas essentiel au développement de la maladie dans le cadre des FHL. Par ailleurs, nous montrons que la cytotoxicité des cellules NK semble normale chez les patients atteints de SoJIA, ce qui suggère que les mécanismes immunologiques à l'origine de la HLH dans les FHL et dans les maladies autoinflammatoires comme la SoJIA sont distincts. Dans la seconde partie de ce manuscrit, nous avons étudié sur le rôle de la sérine/thréonine/tyrosine kinase Styk1 dans la régulation des lymphocytes cytotoxiques NK. Ces derniers sont responsables du contrôle immunitaire précoce des pathogènes intracellulaires et contribuent à l'immunosurveillance des cellules tumorales. Suite à leur activation, ils relâchent de très grandes quantités d'IFN-y et de TNF-α, faisant ainsi le lien entre l'immunité innée et adaptative. La reconnaissance des cellules cibles par les lymphocytes NK est gouvernée par l'expression d'un éventail de récepteurs qui transduisent des signaux, activateurs ou inhibiteurs, et dont la balance se traduit par l'activation ou la tolérance. Ces récepteurs sont codés au sein de deux complexes génétiques très denses, le complexe de cytotoxicité naturelle (NCR) et le complexe des récepteurs des leucocytes (LRC). Au moment de commencer ces travaux, nous avions révélé que l'expression de la kinase Styk1 fait partie de la signature transcriptionnelle des lymphocytes NK. Sa fonction dans le système immunitaire demeure toutefois inconnue. Néanmoins, la localisation génétique favorable de Styk1, près du NCR, ainsi que son implication dans la voie PI3K-AKT, en faisaient un candidat potentiel de régulation des lymphocytes NK. Afin de connaître le rôle de Styk1 dans le développement et les fonctions effectrices des lymphocytes NK, nous avons donc généré une souris pour laquelle Styk1 est invalidé. Nos résultats confirment que Styk1 est exprimée de façon spécifique par les cellules NK. Nous avons également détecté une diminution de l'activité constitutive de la voie AKT/mTOR dans les cellules NK, mais le développement, l'homéostasie et la fonction des cellules NK sont cependant normaux dans les souris déficientes en Styk1 / Upon recognition of infected or target cells, CD8+ T and Natural Killer (NK) lymphocytes initiate a polarized degranulation of vesicle storing cytotoxic molecules (perforin: PRF1 and granzyme B). By altering the target cell’s cellular membrane integrity, perforine allows granzyme B to translocate to its cytosol. Genetic anomalies may affect normal cytotoxic functions and severely hamper the control of intracellular pathogens. In this context, the pathogenic signal remains uninterrupted and both cytotoxic lymphocytes and macrophages are continuously stimulated. This auto-inflammatory pathological condition is named hemophagocytic lymphohistiocytosis (HLH) and is fatal without therapeutic intervention. HLH can also occur secondary to infection with viruses from the herpesviridae family, or be concomitant to important immune alterations such as systemic onset juvenile idiopathic arthritis (SoJIA), with no clear etiological cause identified. In 2014, a case of HLH mediated by the constitutive activation of the NLRC4 inflammasome receptor was first described. The inflammasome is a multimeric structure involving a cytosolic receptor, a scaffold protein – ASC – and Caspase-1. In the immune system, the inflammasome is expressed in macrophages and dendritic cells and senses pathogenic (PAMP) and danger (DAMP) associated signals. Once activated, inflammasome’s protein Caspase-1 catalyzes the maturation of pro-IL-1b and pro-IL-18 and leads to their secretion. Since NLRC4 constitutive activation appears to be sufficient for triggering HLH, we aimed to understand if the inflammasome structure was essential to the development of the syndrome. In order to address this question, we invalidated the inflammasome through the abrogation of ASC or Caspase-1 in PRF1 -/- HLH mouse model. We also tested the hypothesis that an altered cytotoxic function could explain the high prevalence of HLH in the proinflammatory context of SoJIA. The results we present here show that the inflammasome is responsible for the elevated levels of IL-18 in the serum of HLH patients. However, the inflammasome is facultative for its development. We also demonstrate that in patients suffering from SoJIA, NK cells show normal cytotoxicity, suggesting that immunological mechanisms involved in FHL and secondary HLH are distinct. In the second part of this manuscript, we aim at understanding the role of Styk1 serine/threonine/tyrosine kinase in NK cells’ regulation. NK cells are in charge of eliminating stressed, virally infected or transformed cells. Upon activation, they secrete large amounts of IFN-γ and TNF-α, thus bridging innate and adaptive immunity. Capabilities for recognition of target cells is endowed by the expression of numerous stochastically expressed activating and inhibitory receptors. The balance between activating and inhibitory signal allows for self-tolerance or activation upon engagement of abnormal cells. Activating and inhibitory receptor are germline encoded in two dense, large complexes, the Natural Killer Complex (NKC) and the Leukocyte Receptor Complex (LRC). At the moment of starting this work, we had recently identified that Styk1 was a signature transcript of NK cells. However, its function in NK cells and more generally in the immune system remains unknown. Nevertheless, its genetic localisation near the NKC and its potential implication in the PI3K-AKT pathway prompt that it may play a role in NK cell development and/or functions. In order to evaluate the role of Styk1 in NK cells’ regulation, we generated a mouse model in which its expression is abrogated. Our data confirms that amongst all immune subsets, Styk1 is specifically expressed by NK cells. Styk1 was also able to discriminate NK cells from other ILCs. In this study, we show that Styk1 invalidation lead to a decrease of activity in the AKT/mTOR pathway. However, NK cells development, homeostasis and function were surprisingly normal in Styk1 -/- mice