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Background Children have a low rate of COVID-19 and secondary severe multisystem inflammatory syndrome (MIS) but present a high prevalence of symptomatic seasonal coronavirus infections. Aim We tested if prior infections by seasonal coronaviruses (HCoV) NL63, HKU1, 229E or OC43 as assessed by serology, provide cross-protective immunity against SARS-CoV-2 infection. Methods We set a cross-sectional observational multicentric study in pauci- or asymptomatic children hospitalised in Paris during the first wave for reasons other than COVID (hospitalised children (HOS), n = 739) plus children presenting with MIS (n = 36). SARS-CoV-2 antibodies directed against the nucleoprotein (N) and S1 and S2 domains of the spike (S) proteins were monitored by an in-house luciferase immunoprecipitation system assay. We randomly selected 69 SARS-CoV-2-seropositive patients (including 15 with MIS) and 115 matched SARS-CoV-2-seronegative patients (controls (CTL)). We measured antibodies against SARS-CoV-2 and HCoV as evidence for prior corresponding infections and assessed if SARS-CoV-2 prevalence of infection and levels of antibody responses were shaped by prior seasonal coronavirus infections. Results Prevalence of HCoV infections were similar in HOS, MIS and CTL groups. Antibody levels against HCoV were not significantly different in the three groups and were not related to the level of SARS-CoV-2 antibodies in the HOS and MIS groups. SARS-CoV-2 antibody profiles were different between HOS and MIS children. Conclusion Prior infection by seasonal coronaviruses, as assessed by serology, does not interfere with SARS-CoV-2 infection and related MIS in children.

International audience; Primary infection with varicella-zoster virus (VZV) causes chickenpox, a benign and self-limited disease in healthy children. In patients with primary or acquired immunodeficiencies, primary infection can be life-threatening, due to rapid dissemination of the virus to various organs [lung, gastrointestinal tract, liver, eye, central nervous system (CNS)]. We retrospectively described and compared the clinical presentations and outcomes of disseminated varicella infection (DV) in patients with acquired (AID) (n= 7) and primary (PID) (n= 12) immunodeficiencies. Patients with AID were on immunosuppression (mostly steroids) for nephrotic syndrome, solid organ transplantation or the treatment of hemopathies, whereas those with PID had combined immunodeficiency (CID) or severe CID (SCID). The course of the disease was severe and fulminant in patients with AID, with multiple organ failure, no rash or a delayed rash, whereas patients with CID and SICD presented typical signs of chickenpox, including a rash, with dissemination to other organs, including the lungs and CNS. In the PID group, antiviral treatment was prolonged until immune reconstitution after bone marrow transplantation, which was performed in 10/12 patients. Four patients died, and three experienced neurological sequelae. SCID patients had the worst outcome. Our findings highlight substantial differences in the clinical presentation and course of DV between children with AID and PID, suggesting differences in pathophysiology. Prevention, early diagnosis and treatment are required to improve outcome.

Methicillin-resistant staphylococcal infections are a global burden. Area under the concentration-time curve to MIC (AUC/MIC) ratio is the pharmacokinetic (PK) parameter that best predicts vancomycin efficacy. Its therapeutic range is narrow, difficult to achieve because of a wide intersubject variability, especially in children, and is not routinely targeted since the AUC is rarely available. We investigated if an early Bayesian dose adjustment would increase the rate of vancomycin target attainment in the first 24 hours of treatment (H24) in children. We conducted a single-center randomized controlled trial in 4 pediatric departments of Necker-Enfants Malades Hospital (Paris, France). Patients aged 3 months to 17 years for whom intravenous vancomycin was started were eligible and randomized in a 1:1 ratio; routine care was compared with an early vancomycin therapeutic drug monitoring (3 h after treatment initiation) followed by an early Bayesian dose adjustment using a previously published population-based PK model that included age, body weight, and serum creatinine as covariates. The primary outcome was the proportion of patients of each group achieving vancomycin therapeutic range at H24, defined by AUC(0–24)/MIC of ≥400 and AUC(0–24) of ≤800 mg-h/liter. Ninety-nine patients were enrolled and 49 were randomized to the Bayesian group and 50 to the control group. Modified intention-to-treat analysis included 82 patients; 85% of Bayesian group patients achieved H24 vancomycin target versus 57% of control group patients (P = 0.007) with no difference regarding iatrogenic events. Early Bayesian dose adjustment increased the proportion of children achieving vancomycin target at H24, which may improve clinical outcomes of methicillin-resistant staphylococcal infections. (This study has been registered at ClinicalTrials.gov under identifier NCT02694458.)

The cyclin-dependent kinases CDK4 and CDK6 promote progression through the cell cycle, where their functions are considered to be redundant. Recent studies have identified an additional role for CDK6 in the transcriptional regulation of cancer-relevant genes such as VEGF-A and EGR1 in hematopoietic malignancies. We show that the CDK4/6 inhibitor PD0332991 causes a significant decrease in tumor growth in a xenotransplantation mouse model of human melanoma. shRNA knockdown of either CDK4 or CDK6 significantly reduces cell proliferation and impedes their migratory capacity in vitro, which translates into a strong inhibition of tumor growth in xenotransplantation experiments. CDK4/6 inhibition results not only in the pronounced reduction of cell proliferation but also in an impaired tumor angiogenesis. CDK6 knockdown in melanoma cell lines impairs VEGF-A expression and reduces the potential stimulation of endothelial cell growth. The knockdown of CDK4 ends in similar results. The effect is caused by changes of CDK6 localization, less CDK6 is detected on the VEGF-A promoter. Bioinformatic analysis of human melanoma patient data verifies the key role of CDK6 in tumor angiogenesis in melanoma. The results highlight the importance of the delicate balance between CDK4 and CDK6 in regulating the cell cycle and transcription.

The type I interferonopathies, Mendelian disorders characterised by constitutive upregulation of the type I interferon (IFN) pathway, are associated with a spectrum of phenotypes particularly involving the brain and the skin.1 Mutations in the 3′−5′ DNA exonuclease TREX1 were the first described cause of the severe encephalopathy Aicardi-Goutieres syndrome (AGS),2 of which acral vasculitic lesions are a well-recognised feature. Familial chilblain lupus (FCL) is the name given where such lesions occur in the absence of neurological disease.3 TREX1 dysfunction, due to biallelic loss of function or dominant negative heterozygous mutations, is postulated to lead to aberrant immune recognition of self-nucleic acids inducing the production of type I IFNs. These potent cytokines drive the expression of IFN-stimulated genes (ISGs) through the engagement of a common receptor and the subsequent activation of Janus kinase 1 (JAK1) and tyrosine kinase 2. We describe, to our knowledge for the first time, the efficacy of the JAK1/2 inhibitor ruxolitinib in a patient with TREX1-related skin disease. Parental consent was obtained for the use of ruxolitinib on a compassionate basis. The patient carried a previously recorded dominant negative heterozygous mutation in TREX1 (c.52G>A, …

Cyril Schweitzer (CS) : A 1.5-year-old girl was referred to the Paediatric Pneumology Department of the University Hospital of Nancy, France, for progressive tachypnoea and hypoxia. She suffered from intrauterine growth retardation, and was born prematurely at 31 weeks’ gestation; birth weight: 1.160 kg (≤2 SD); birth length: 37 cm (≤2 SD). The patient presented with acute respiratory distress syndrome at birth, requiring treatment with a dose of surfactant, 9 days of mechanical ventilation and 8 weeks of oxygen therapy. On arrival to our centre, she was dyspnoeic on exertion and oxygen saturations were between 91% and 94%. Further investigations included a high-resolution CT scan and a bronchoalveolar lavage (BAL). Laureline Berteloot (LB) and Julie Bruneau (JB) : CT imaging of the chest revealed a ‘crazy paving’ pattern whereas analysis of BAL fluid failed to identify any underlying disease. CS : Hypoxia transiently improved after initiation of inhaled corticosteroids and antireflux therapy but relapsed after a few months, so that a second BAL was performed. JB : The second BAL fluid revealed the presence of extracellular lipid and protein deposits and foamy alveolar macrophages. CS and Cecile Bonnet (CeB) : These abnormalities led to a diagnosis of pulmonary alveolar proteinosis (PAP) at the age of 2.6 years, which was confirmed by genetic testing; complex chromosome abnormalities were detected, with (1) deletion of CSF2RA and CRLF2 on the X chromosome inherited from the mother, and (2) a de novo rearrangement of the paternal X chromosome, resulting in loss of both CSF2RA alleles.1 CS, Christophe Delacourt (CD) and Jacques De Blic (JDB) : Recessive mutations in the α or β subunits of the granulocyte macrophage colony-stimulating factor receptor (GM-CSF-R, encoded respectively by CSF2RA and CSF2RB ) cause two subtypes of hereditary PAP.2 Impairment of GM-CSF-dependent surfactant clearance by alveolar macrophages leads to the progressive accumulation of surfactant in the alveolar space …

Background Hemophagocytic lymphohistiocytosis (HLH) is an inflammatory condition caused by uncontrolled proliferation of activated lymphocytes and macrophages secreting an excess of inflammatory cytokines. When untreated, primary HLH is invariably fatal. Treatment requires the achievement of remission of HLH prior to allogeneic hematopoietic stem cell transplantation. Despite significant treatment progress, pre-HSCT mortality remains a challenge. In the Etoposide-based HLH-94 and HLH-2004 studies pre-HSCT mortality was 27% and 19%, respectively. A better understanding of the pathophysiology of primary HLH has opened new avenues for targeted immunotherapy. Based on our previous observation concerning the use of Antithymoglobulin in HLH, we propose a new therapeutic strategy with Alemtuzumab in association with steroids and cyclosporine A (CSA) as first line treatment in primary HLH. In contrast to ATG, Alemtuzumab does not activate T lymphocytes while killing them. Therefore, we expect a better tolerance and efficacy of Alemtuzumab. This may have a positive impact not only on survival until HSCT, but also on overall survival and quality of life, especially with regard to long-term neurological sequelae. Methods 24 consecutive treatment naïve patients with genetically confirmed primary HLH had received first line Alemtuzumab in association to steroids and CSA from 01/2009 to 06/2015 in the Unit for Pediatric Immunology in Necker Hospital Paris, as well as two additional patients in 10/2016 and 10/2018 respectively, who could not be included in the prospective trial. From 06/2015 to 06/2019, 29 patients have been enrolled in a multicenter, open, phase I/II, non-comparative, non randomized study (NCT02472054). Patients with lymphohistiocytic activation syndrome who had not received any specific treatment prior to enrollment except steroids and CSA were included. Treatment consisted in intravenous administration of Alemtuzumab in association to Methylprednisolone and CSA. The primary outcome measures is the number of surviving patients until HSCT, secondary outcome measures the number of complete remissions following treatment at Day (D)14, D21, D28. To assess the efficacy of the Alemtuzumab, the time of delay between the first administration of Alemtuzumab and complete remission will be determined. Alemtuzumab Pharmacokinetics will be done. All adverse events are reported. Results Retrospective analysis of 26 patients (pilot study): The median age of patients was 1.9 months (birth - 7 years), 6 patients were neonates. When Alemtuzumab was started, out of 26 patients 12 (46.1%) required intensive care, 8 (30.7%) mechanical ventilation, 13 (50%) had neurological involvement, 9 (34.6%) hepatocellular insufficiency. One 2-month-old Munc13-4 patient died at H+48 after two administrations of Alemtuzumab (total dose 1.5mg/kg) for hepatic failure and acute renal failure. A second patient with Perforin deficiency did not respond neither to three courses of Alemtuzumab (cumulative dose 6.5mg/kg) nor repeated Etoposid, 40mg/kg ATG, or Ruxulotinib. He died at D+65. The 24 remaining patients survived until HSCT (survival 92.3%). As shown in the figure, two patients required additional treatment. Overall 22 patients achieved CR, 2 PR at the time of HSCT. The prospective study enrolled 29 patients from 06/2015 to 06/2019. Median age at onset of HLH was 0.5 years (range 0.02 to 17.2 years), one patient withdrawed consent. 12 patients received one course, 13 two, 2 three and one patient 4 courses of Alemtuzumab. 24 patients with a genetic confirmed HLH predisposition reached the primary endpoint with 22 surviving until HSCT (91,6%). One patient is still awaiting HSCT. The three remaining patients are one CA-EBV patient and a newborn with secondary HLH due to fulminant HSV hepatitis, who both died, as well as a patient with predominant neurological HLH without genetic diagnosis who is in sustained remission without any specific treatment. Detailed results from the completed study will be presented. Conclusions This is the first report on Alemtuzumab as first line approach in the treatment of primary HLH. Our results in more than 50 pediatric patients treated in a pilot study and prospective trial indicate that Alemtuzumab allows controlling HLH activity with a favorable safety and tolerability profile in a very fragile population. 92.3% and 91.6% of patients respectively survived to HSCT. Figure Disclosures No relevant conflicts of interest to declare. Off Label Disclosure: Alemtuzumab (Campath) has been used in a prospective trial to evaluate its efficacy as first line treatment in Familial Lymphohistiocytosis.