FLT3L governs the development of partially overlapping hematopoietic lineages in humans and mice

FMS-related tyrosine kinase 3 ligand (FLT3L), encoded by FLT3LG, is a hematopoietic factor essential for the development of natural killer (NK) cells, B cells, and dendritic cells (DCs) in mice. We describe three humans homozygous for a loss-of-function FLT3LG variant with a history of various recurrent infections, including severe cutaneous warts. The patients' bone marrow (BM) was hypoplastic, with low levels of hematopoietic progenitors, particularly myeloid and B cell precursors. Counts of B cells, monocytes, and DCs were low in the patients' blood, whereas the other blood subsets, including NK cells, were affected only moderately, if at all. The patients had normal counts of Langerhans cells (LCs) and dermal macrophages in the skin but lacked dermal DCs. Thus, FLT3L is required for B cell and DC development in mice and humans. However, unlike its murine counterpart, human FLT3L is required for the development of monocytes but not NK cells.

Malignant Peritoneal Mesothelioma Complicating Familial Mediterranean Fever on 18 F-FDG PET/CT

ABSTRACT

A 77-year-old man with a personal history of familial Mediterranean fever presented with a slowly enlarging tumefaction of the left abdominal wall and persistent inflammatory syndrome despite good adherence to colchicine. 18 F-FDG PET/CT showed a hypermetabolic muscular mass of the abdominal wall along with other hypermetabolic lesions including a peritoneal mass and several subcutaneous soft tissue nodules. CT-guided needle biopsy led to the diagnosis of a muscular localization of a malignant peritoneal mesothelioma, which is an extremely rare complication of familial Mediterranean fever. Six courses of chemotherapy with carboplatin and pemetrexed allowed an almost complete response.

Pathogenic variants in the NLRP3 LRR domain at position 861 are responsible for a boost-dependent atypical CAPS phenotype

BACKGROUND

Cryopyrin-associated periodic syndrome (CAPS) is associated with NLRP3 pathogenic variants, mostly located in the NACHT (neuronal apoptosis inhibitor protein, MHC class 2 transcription activator, incompatibility locus protein from Podospora anserina, telomerase-associated protein) domain. Cold-induced urticarial rash is among the main clinical features. However, this study identified a series of 14 patients with pathogenic variants of the Y861 residue (p.Tyr861) of the LRR domain of NLRP3 and minimal prevalence of cold-induced urticarial rash.

OBJECTIVES

This study aimed to address a possible genotype/phenotype correlation for patients with CAPS and to investigate at the cellular levels the impact of the Y861C substitution (p.Tyr861Cys) on NLRP3 activation.

METHODS

Clinical features of 14 patients with CAPS and heterozygous substitution at position 861 in the LRR domain of NLRP3 were compared to clinical features of 48 patients with CAPS and pathogenic variants outside the LRR domain of NLRP3. IL-1β secretion by PBMCs and purified monocytes from patients and healthy donors was evaluated following LPS and monosodium urate crystal stimulation.

RESULTS

Patients with substitution at position 861 of NLRP3 demonstrated a higher prevalence of sensorineural hearing loss while being less prone to skin urticarial. In contrast to patients with classical CAPS, cells from patients with a pathogenic variant at position 861 required an activation signal to secrete IL-1β but produced more IL-1β during the early and late phase of secretion than cells from healthy donors.

CONCLUSIONS

Pathogenic variants of Y861 of NLRP3 drive a boost-dependent oversecretion of IL-1β associated with an atypical CAPS phenotype.

Successful treatment of JAK1-associated inflammatory disease

BACKGROUND

Gain-of-function variants of JAK1 drive a rare immune dysregulation syndrome associated with atopic dermatitis, allergy, and eosinophilia.

OBJECTIVES

This study sought to describe the clinical and immunological characteristics associated with a new gain-of-function variant of JAK1 and report the therapeutic efficacy of Janus kinase (JAK) inhibition.

METHODS

The investigators identified a family affected by JAK1-associated autoinflammatory disease and performed clinical assessment and immunological monitoring on 9 patients. JAK1 signaling was studied by flow and mass cytometry in patients' cells at basal state or after immune stimulation. A molecular disease signature in the blood was studied at the transcriptomic level. Patients were treated with 1 of 2 JAK inhibitors: either baricitinib or upadacitinib. Clinical, cellular, and molecular response were evaluated over a 2-year period.

RESULTS

Affected individuals displayed a syndromic disease with prominent allergy including atopic dermatitis, ichthyosis, arthralgia, chronic diarrhea, disseminated calcifying fibrous tumors, and elevated whole blood histamine levels. A variant of JAK1 localized in the pseudokinase domain was identified in all 9 affected, tested patients. Hyper-phosphorylation of STAT3 was found in 5 of 6 patients tested. Treatment of patients' cells with baricitinib controlled most of the atypical hyper-phosphorylation of STAT3. Administration of baricitinib to patients led to rapid improvement of the disease in all adults and was associated with reduction of systemic inflammation.

CONCLUSIONS

Patients with this new JAK1 gain-of-function pathogenic variant displayed very high levels of blood histamine and showed a variable combination of atopy with articular and gastrointestinal manifestations as well as calcifying fibrous tumors. The disease, which appears to be linked to STAT3 hyperactivation, was well controlled under treatment by JAK inhibitors in adult patients.

Diagnostic and therapeutic algorithms for monogenic autoinflammatory diseases presenting with recurrent fevers among adults

Autoinflammatory diseases (AIDs) are defined as disorders of innate immunity. They were initially defined in contrast to autoimmune diseases because of the lack of involvement of the adaptive immune system and circulating autoantibodies. The four monogenic AIDs first described are called the "historical" AIDs and include: Familial Mediterranean Fever (associated with MEFV mutations), cryopyrinopathies (associated with NLRP3 mutations), Tumor Necrosis Factor Receptor-associated Periodic Syndrome (associated with TNFRSF1A mutations) and Mevalonate Kinase Deficiency (associated with MVK mutations). In the last 10 years, >50 new monogenic AIDs have been discovered due to genetic advances. The most important discovery for adult patients is VEXAS syndrome associated with somatic UBA1 mutations leading to an autoinflammatory disease affecting mostly elderly men. Diagnosis of monogenic AIDs is based on personal and family history and detailed analysis of symptoms associated with febrile attacks, in the context of elevated peripheral inflammatory markers. This review proposes a practical approach of the diagnosis of the main monogenic AIDs among adult patients to guide the clinician.

DADA2 diagnosed in adulthood versus childhood: A comparative study on 306 patients including a systematic literature review and 12 French cases

BACKGROUND

Deficiency of adenosine deaminase 2 (DADA2) is a rare autoinflammatory disease usually presenting before the age of 10 years. Non-specific clinical features or late-onset presentation may delay its diagnosis until adulthood.

OBJECTIVE

To determine whether DADA2 diagnosed in adulthood is associated with specific characteristics compared to DADA2 diagnosed in childhood.

METHODS

We pooled a cohort of 12 adult DADA2 patients followed in France with cases identified through a systematic literature review. For each patient, we determined the type of clinical presentation and assessed six key organ involvements.

RESULTS

A total of 306 cases were included. Among the 283 patients with available data regarding age at diagnosis, 140 were diagnosed during adulthood and 143 during childhood. The vascular presentation of DADA2 was more frequent in the adult diagnosis group (77.9% vs. 62.9%, p < 0.01), whereas the hematological presentation (bone marrow failure) prevailed in the pediatric diagnosis group (10.0% vs. 20.3% p = 0.02). In patients with vasculopathy, severe skin manifestations developed in 35% and 10% of the adult and pediatric diagnosis groups, respectively. Conversely, fewer strokes occurred in the adult group presenting with systemic vasculopathy (54% vs. 81%). Symptomatic humoral immune deficiency (HID) was rarely a clinical presentation in itself (5% and 2.8%) but accompanied other phenotypes of DADA2, especially the hematological phenotype in the adult group (33% vs. 4%).

CONCLUSION

DADA2 diagnosed in adulthood presents more often with a vascular phenotype and less often with bone marrow failure than DADA2 diagnosed in childhood. Adults diagnosed with DADA2 vasculopathy display more severe skin involvement but fewer strokes.

Efficacité du Tocilizumab dans la COVID-19 modérée à sévère : une cohorte française exposé-non exposé

Introduction

L’infection par le SARS-CoV-2 peut mener à un syndrome de détresse respiratoire aigu dont la mortalité était estimée à 50 % au début de l’épidémie. Ces formes sévères étant significativement associées à un état d’hyperinflammation, et notamment à un niveau élevé d’interleukine-6, il a été proposé que cibler la voie de signalisation de cette interleukine majoritairement pro-inflammatoire, puisse réduire la mortalité de la COVID-19. Pour autant, un an après le début de la pandémie, la place de ces inhibiteurs, dont le Tocilizumab, un anticorps monoclonal dirigé contre le récepteur de l’interleuline-6, reste à déterminer.

Patients et méthodes

Cohorte exposé-non exposé en vie réelle, monocentrique et menée à l’hôpital Saint-Antoine, Paris, France, avant la mise en place de l’essai randomisé CORIMUNO-TOCI. Etaient inclus les patients de plus de 18 ans qui présentaient une forme modérée à sévère de COVID-19, selon la définition de l’OMS, et qui nécessitaient une oxygéno-requerance ≥ 4 L/min, associée à un syndrome inflammatoire biologique (CRP > 50 mg/L). Etaient exclus les patients qui portaient des contre-indications au Tocilizumab (antécédent de sigmoïdite ou de diverticulite, une cytolyse hépatique supérieure à 5 N, une allergie connue au Tocilizumab, ou une infection bactérienne active.) Par ailleurs, les patients qui étaient transférés en soins intensifs dans les premières 24 h après l’injection de Tocilizumab étaient exclus de notre étude, puisque ils étaient inclus dans une étude qui évaluait le Tocilizumab en réanimation. Les patients du groupe Tocilizumab recevaient une injection de 8 mg/kg (maximum 800 mg) de Tocilizumab associée aux soins courants et les patients du groupe soins courants ne recevaient que les soins courants. Pour assurer la comparabilité des deux groupes nous avons utilisé le score de propension. Notre critère de jugement principal était le délai de sevrage en oxygène. Les critères de jugement secondaire étaient : le transfert en soins intensifs, le besoin de ventilation mécanique, le décès toutes causes confondues, le décès au dixi^e jour, la durée d’hospitalisation ainsi que les scores composites intubation ou décès et transfert en soins intensifs ou décès.

Résultats

Cinquante patients ont été inclus dans le groupe Tocilizumab et 52 patients dans le groupe soins courants. L’âge moyen était de 68,9 ± 2 ans et 71 % des patients étaient des hommes. Les patients du groupe Tocilizumab étaient plus fréquemment diabétique (34 % vs 13 % ; p = 0,02), et avaient un niveau d’oxygène moyen plus élevé (9,1 L/min vs 6,8 L/min ; p = 0,0002). Les patients du groupe Tocilizumab avaient reçu plus de corticoïdes que les patients du groupe soins courants (53 % vs 6 % ; p < 0,0001). Le délai de sevrage en oxygène n’était pas diffèrent dans les deux groupes, 14,1 [IQR 7-19] jours dans le groupe Tocilizumab versus 12,2 [IQR 7,5-14] jours dans le groupe soins courants, hazard ratio ajusté à 1,53 (IC95 % (0,96-2,45) ; p = 0,073). Il n’y avait pas non plus de différence concernant les critères de jugement secondaires.

Discussion

Dans cet essai, nous rapportons une absence de bénéfice du Tocilizumab dans les formes modérées à sévères de la COVID-19. L’injection de Tocilizumab à la posologie de 8 mg/kg n’améliorait pas le délai de sevrage en oxygène, et ne réduisait pas la nécessité d’intubation, de transfert en soins intensifs ou la mortalité. Cette absence de différence peut être expliquée, en partie, par le fait que les patients du groupe Tocilizumab étaient plus graves (oxygéno-requerance plus élevée) et comorbides (plus fréquemment diabétiques). En revanche, ces patients avaient reçu plus de corticoides qui est aujourd’hui un traitement recommandé dans la prise en charge des patients sous oxygène, atteints de la COVID-19. Notre étude manque aussi de puissance, une récente méta-analyse estimait à 2300 patients (dans chaque bras) le nombre de sujet nécessaire pour mettre en évidence une différence significative si celle-ci existait.

Conclusion

Un essai randomisé récent qui incluait un nombre de sujet suffisant, en cours de publication, a montré des résultats encourageants, avec une diminution de la mortalité à 28 jours chez les patients traités par Tocilizumab (majoritairement en associations au corticoïdes). Toutefois la question du meilleur moment de l’injection de Tocilizumab chez les patients atteints de COVID-19 reste entière.

The Use of Interleukine-1 Inhibitors in Familial Mediterranean Fever Patients: A Narrative Review

Purpose: Familial Mediterranean fever (FMF) is the most common monogenic auto-inflammatory disease characterized by recurrent attacks of fever and serositis. It is associated with mutation in pyrin inflammasome leading to interleukin-1 (IL-1) over secretion. Although colchicine is the first line treatment in FMF, 5-10% of patients are reported in literature as non-responders. Colchicine is not always well-tolerated due either to its direct toxicity or to co-morbidities that preclude the administration of its proper dosage. For these patients an alternative or additional treatment to colchicine is necessary. This literature review reports the published data regarding the use of IL-1 inhibitors in Familial Mediterranean Fever. Results: There is no uniform definition of colchicine resistance, but the different studies of treatment with IL-1 inhibitors provide evidence of IL-1 pathogenic role in colchicine-resistant FMF. IL-1 inhibition is an efficacious option for controlling and preventing flares -at least at the short term- in FMF patients who are insufficiently controlled with colchicine alone. Although canakinumab is the only approved drug in Europe for colchicine resistant FMF treatment, experience with anakinra is also substantial. In the absence of comparative studies both treatments seem to be an equal option for the management of these patients. Overall the safety profile of IL-1 inhibitors seems not different in FMF patients than in the other diseases and can be considered as globally safe. The main side effects are local injection site reactions and infections. Conclusion: IL-1 inhibitors have the potential to improve patient outcome even in FMF patients with co-morbidities or severe complications in whom inflammation control is difficult to achieve with colchicine alone. Nevertheless, current data are limited and further evaluation of long-term efficacy and safety of IL-1 inhibitors are necessary, in order to provide robust evidence in this domain.

Epidemiology of Castleman disease associated with AA amyloidosis: description of 2 new cases and literature review

Introduction: HHV8-negative Castleman disease (CD) is classified as hyaline vascular (HV) type, or mixed or plasma cell (PC) types. It may present as multicentric CD (MCD) or unicentric CD (UCD). CD is a rare cause of AA amyloidosis (AAA). We aimed to report the main features of CD with secondary AAA through a description of new cases and a systematic literature review. Patients and methods: New cases were identified from the French National Reference Center for AAA. A systematic literature review was performed to identify HHV8-negative CD cases associated with AAA. Results: Thirty-seven patients were analysed, consisting of two new cases and 35 from literature. Twenty-three had UCD and 14 had MCD. PC was the main histologic subtype (n = 25; 68%) in both UCD and MCD patients. Surgical excision of UCD was performed in 21 patients (91%) with a favourable outcome, except for four patients (19%). Clinical and biologic remission was achieved in six patients with MCD (43%), all of whom were treated with anti-interleukin-6 (IL-6) therapy. Conclusions: AAA is a rare complication of CD, namely idiopathic MCD and UCD presenting with the PC histologic subtype. Surgical excision of UCD should be the first-line treatment whenever possible, while anti-IL-6 therapies seem effective for MCD.

Autoinflammatory diseases: State of the art

Autoinflammatory diseases are characterized by innate immunity abnormalities. In autoinflammatory diseases (AID), inflammatory blood biomarkers are elevated during crisis without infection and usually without autoantibodies. The first 4 described AID were familial Mediterranean fever, cryopyrin-associated periodic fever syndrome (CAPS) or NLRP3-associated autoinflammatory disease (NRLP3-AID), mevalonate kinase deficiency (MKD) and TNFRSF1A-receptor associated periodic fever syndrome (TRAPS). Since their description 20 years ago, and with the progresses of genetic analysis, many new diseases have been discovered; some with recurrent fever, others with predominant cutaneous symptoms or even immune deficiency. After describing the 4 historical recurrent fevers, some polygenic inflammatory diseases will also be shortly described such as Still disease and periodic fever with adenitis, pharyngitis and aphtous (PFAPA) syndrome. To better explore AID, some key anamnesis features are crucial such as the family tree, the age at onset, crisis length and organs involved in the clinical symptoms. An acute phase response is mandatory in crisis.

[Clinical overview of auto-inflammatory diseases]

Monogenic auto-inflammatory diseases are characterized by genetic abnormalities coding for proteins involved in innate immunity. They were initially described in mirror with auto-immune diseases because of the absence of circulating autoantibodies. Their main feature is the presence of peripheral blood inflammation in crisis without infection. The best-known auto-inflammatory diseases are mediated by interleukines that consisted in the 4 following diseases familial Mediterranean fever, cryopyrinopathies, TNFRSF1A-related intermittent fever, and mevalonate kinase deficiency. Since 10 years, many other diseases have been discovered, especially thanks to the progress in genetics. In this review, we propose the actual panorama of the main known auto-inflammatory diseases. Some of them are recurrent fevers with crisis and remission; some others evaluate more chronically; some are associated with immunodeficiency. From a physiopathological point of view, we can separate diseases mediated by interleukine-1 and diseases mediated by interferon. Then some polygenic inflammatory diseases will be shortly described: Still disease, Schnitzler syndrome, aseptic abscesses syndrome. The diagnosis of auto-inflammatory disease is largely based on anamnesis, the presence of peripheral inflammation during attacks and genetic analysis, which are more and more performant.

[Multiple facets of ADA2 deficiency: Vasculitis, auto-inflammatory disease and immunodeficiency: A literature review of 135 cases from literature]

Deficiency of adenosine deaminase 2 (DADA2) is a recently described auto-inflammatory disorder. It is an autosomal recessive inherited disease, caused by mutations in the ADA2 gene (formerly known as CECR1) encoding ADA2 enzyme. Besides its role in the purine metabolism, it has been postulated that ADA2 may act as a growth factor for endothelial cells and in the differenciation of monocytes. Thus, deficiency of ADA2 would lead to endothelial damage and a skewing of monocytes into M1 pro-inflammatory macrophage, causing DADA2 manifestations. Three core clinical features have been described: inflammatory-vascular signs, hematologic abnormalities and immunodeficiency. Clinically, patients display intermittent fever, cutaneous vascular manifestations, such as livedo, ischemic strokes, arthralgia and abdominal pain crisis. Corticosteroids and immunosuppressive agents (i.e. cyclophosphamide, azathioprine, ciclosporin, methotrexate) appear to be poorly effective. Although the mechanism has not been elucidated, anti-TNF agents have been proven efficient in DADA2 and should therefore be used as first line therapy for vasculitis. Role of anti-platelet and anticoagulant therapies in stroke-prophylaxis remains to be discussed, as those patients display a high risk of intracranial bleeding.