Macrophages are mononuclear phagocytes which derive either from blood-borne monocytes or reside as resident macrophages in peripheral (Kupffer cells of the liver, marginal zone macrophages of the spleen, alveolar macrophages of the lung) and central tissue (microglia). They occur as M1 (pro-inflammatory; classic) or M2 (anti-inflammatory; alternatively activated) phenotypes. Macrophages possess P2X7 receptors (Rs) which respond to high concentrations of extracellular ATP under pathological conditions by allowing the non-selective fluxes of cations (Na+, Ca2+, K+). Activation of P2X7Rs by still higher concentrations of ATP, especially after repetitive agonist application, leads to the opening of membrane pores permeable to ~900 Da molecules. For this effect an interaction of the P2X7R with a range of other membrane channels (e.g., P2X4R, transient receptor potential A1 [TRPA1], pannexin-1 hemichannel, ANO6 chloride channel) is required. Macrophagelocalized P2X7Rs have to be co-activated with the lipopolysaccharide-sensitive toll-like receptor 4 (TLR4) in order to induce the formation of the inflammasome 3 (NLRP3), which then activates the pro-interleukin-1 (pro-IL-1)-degrading caspase-1 to lead to IL-1 release. Moreover, inflammatory diseases (e.g., rheumatoid arthritis, Crohn’s disease, sepsis, etc.) are generated downstream of the P2X7R-induced upregulation of intracellular second messengers (e.g., phospholipase A2, p38 mitogen-activated kinase, and rho G proteins). In conclusion, P2X7Rs at macrophages appear to be important targets to preserve immune homeostasis with possible therapeutic consequences.

Le syndrome périodique lié à NLRP12 (NLRP12-AD) est une maladie rare appartenant au groupe des maladies auto-inflammatoires systémiques héréditaires. Ces maladies sont causées par des anomalies du système immunitaire inné. Les cryopyrinopathies (CAPS) sont une famille de maladie auto-inflammatoire liées à des mutations gain de fonction du gène NLRP3. NLRP3 fait partie d’un composant central de l’inflammation, l’inflammasome. En 2007, Jéru et al. ont décrit un premier patient présentant des symptômes évocateurs d’un CAPS qui n’était pas porteur de mutation de NLRP3 mais présentait une mutation de NLRP12. Depuis, 33 patients pédiatriques atteints de NLRP12-AD ont été décrits dans la littérature. Les signes cliniques de la maladie sont variables et ne permettent pas d’établir de critères cliniques diagnostics fiables. La pathogénicité des mutations observées chez les patients est difficile à établir. Les patients atteints de NLRP12-AD représentent également un défi thérapeutique, un certain nombre d’entre eux ne répondant pas aux anti-IL1, un traitement pourtant efficace dans la plupart des inflammasomopathies. De nombreuses études se sont intéressées au rôle de NLPR12, qui posséderait à la fois des propriétés pro et anti-inflammatoires par sa capacité à inhiber les voies canoniques et non canoniques de NFkb mais aussi à former un inflammasome. Le rôle exact de NLRP12 reste controversé, avec des résultats différents selon les cellules ou les stimuli utilisés lors des expériences. L’objectif de notre étude est de créer un modèle in vitro fiable et reproductible afin de mieux comprendre la physiopathologie de NLRP12. Il permettra ensuite d’étudier les mutations de NLRP12 retrouvées chez des patients présentant des symptômes de maladie auto-inflammatoire pour améliorer les performances et la fiabilité du diagnostic et proposer des traitements personnalisés aux patients concernés. Nous avons créé un modèle de cellules THP1 NLRP12 KO en utilisant la technologie de CRISPR/Cas9 qui a permis d’induire une délétion homozygote à la jonction entre le 2ème intron et le 3ème exon de NLRP12, qui code pour le domaine fonctionnel de la protéine. Nos cellules KO semblent sécréter moins de cytokine pro-inflammatoire (IL-1β et TNFα) que les cellules WT, suggérant un rôle pro-inflammatoire de NLRP12 dans notre modèle. Nous avons par ailleurs décrit une cohorte nord-américaine de 17 patients porteurs de mutations de NLRP12 afin d’étudier leurs mutations et produit des vecteurs lentiviraux contenant ces mutations. Nous prévoyons d’explorer le rôle de NLRP12 sur l’activation de la voie NFkB et la formation d’un inflammasome puis de transduire nos cellules KO avec les différentes mutations de nos patients et d’analyser leurs conséquences sur ces mêmes voies et sur la sécrétion cytokinique. / NLRP12-AD is part of a new group of rheumatics’ diseases: the systemic autoinflammatory diseases. Those diseases are caused by defect or dysfunction in the innate immune system. Cryopyrin-associated periodic syndromes (CAPS) is a family of systemic autoinflammatory disease initially linked to NLRP3 gain-of-function heterozygous mutations. NLRP3 is part of a key component of inflammation, the inflammasome. In 2007, Jeru et al. described the first patient with CAPS phenotype, but without NLRP3 mutations. This patient had NLRP12 mutations. Since then, 33 pediatric patients with NLRP12-AD have been published. There is no specific clinical presentation that allow homogenous diagnosis. Determination of the causality of the mutations remains tricky. Lastly, some patients have shown resistance to anti-IL1 treatment, a medication that is highly effective in other inflammasomopathies such as CAPS, a puzzling observation as to the role of NLRP12. NLRP12 has been described with both anti- and pro- inflammatory roles, by its ability to inhibit the canonical and non-canonical NFkB pathways, but also through its hypothetic capacity to form an inflammasome. Hence, the exact role of NLRP12 remains controversial and its role might be stimuli- or cell-dependant. Our objective is to create a reliable and reproductible in vitro model to better understand the role of NLRP12. This model will then allow us to study NLRP12 mutations found in patients with auto-inflammatory symptoms. This will improve our diagnostic performance and help to offer to patients the most suitable therapy. We created NLRP12 knockout THP-1 cells by using the CRPISP-Cas 9 gene editing technology. We were able to induce a homozygous deletion at the intron 2/exon 3 junction that encodes the protein functional domain. Our KO cells seems to secrete less pro-inflammatory cytokines (IL-1β and TNFα) than WT cells. This suggests a pro-inflammatory role of NLRP12. We described a North American cohort of 17 pediatric patients with NLRP12 mutations to study their mutations in our model and produced lentiviral vectors containing those mutations. We planned to study the effects of NLRP12 on NFkB activation and on inflammasome formation. Then, we will transduce our KO cells with the patient’s mutations and compare their consequences on inflammation pathways and cytokine secretion.

Procoagulant extracellular vesicles (EV) and platelet activation have been associated with gestational vascular complications. EV-induced platelet-mediated placental inflammasome activation has been shown to cause preeclampsia-like symptoms in mice. However, the effect of EV-mediated placental thrombo-inflammation on trophoblast differentiation remains unknown. Here, we identify that the EV-induced thrombo-inflammatory pathway modulates trophoblast morphology and differentiation. EVs and platelets reduce syncytiotrophoblast differentiation while increasing giant trophoblast and spongiotrophoblast including the glycogen-rich cells. These effects are plateletdependent and mediated by the NLRP3 inflammasome. In humans, inflammasome activation was negatively correlated with trophoblast differentiation marker GCM1 and positively correlated with blood pressure. These data identify a crucial role of EV-induced placental thrombo-inflammation on altering trophoblast differentiation and suggest platelet activation or inflammasome activation as a therapeutic target in order to achieve successful placentation.

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