Revisiting autoimmune lymphoproliferative syndrome caused by Fas ligand mutations.

BACKGROUND: Fas ligand (FasL) is expressed by activated T cells and induces death in target cells upon binding to Fas. Loss-of-function FAS or FASLG mutations cause autoimmune-lymphoproliferative syndrome (ALPS) characterized by expanded double-negative T cells (DNT) and elevated serum biomarkers. While most ALPS patients carry heterozygous FAS mutations, FASLG mutations are rare and usually biallelic. Only 2 heterozygous variants were reported, associated with an atypical clinical phenotype. OBJECTIVE: We revisited the significance of heterozygous FASLG mutations as a cause of ALPS. METHODS: Clinical features and biomarkers were analyzed in 24 individuals with homozygous or heterozygous FASLG variants predicted to be deleterious. Cytotoxicity assays were performed with patient T cells and biochemical assays with recombinant FasL. RESULTS: Homozygous FASLG variants abrogated cytotoxicity and resulted in early-onset severe ALPS with elevated DNT, raised vitamin B12, and usually no soluble FasL. In contrast, heterozygous variants affected FasL function by reducing expression, impairing trimerization, or preventing Fas binding. However, they were not associated with elevated DNT and vitamin B12, and they did not affect FasL-mediated cytotoxicity. The dominant-negative effects of previously published variants could not be confirmed. Even Y166C, causing loss of Fas binding with a dominant-negative effect in biochemical assays, did not impair cellular cytotoxicity or cause vitamin B12 and DNT elevation. CONCLUSION: Heterozygous loss-of-function mutations are better tolerated for FASLG than for FAS, which may explain the low frequency of ALPS-FASLG.

[Sweet syndrome of childhood with acquired cutis laxa (Marshall syndrome) as primary manifestation of Takayasu arteritis]. / Sweet-Syndrom des Kindesalters mit erworbener Cutis laxa (Marshall-Syndrom) als Erstmanifestation einer Takayasu-Arteriitis.

A special form of the rare infantile Sweet syndrome (acute febrile neutrophilic dermatosis) is facultative healing in the form of postinflammatory elastolysis with acquired cutis laxa, named "Marshall" syndrome after the authors who first described it. We report the case of a 3-year-old child in whom the cutaneous manifestation led to diagnosis of Takayasu arteritis. Postinflammatory elastolysis with acquired cutis laxa is a clinically relevant cutaneous indicator of life-threatening cardiovascular complications such as aortitis, aortic aneurysm, coronary stenosis and heart failure in children with Sweet's syndrome. Cutis laxa usually precedes cardiac complications or, as in our case, occurs simultaneously; thus, immediate cardiac and rheumatologic examinations are important to initiate systemic therapy with anti-inflammatory and immunomodulatory agents early to prevent complications.

Clinical manifestations and outcome of SARS-CoV-2 infections in children and adolescents with rheumatic musculoskeletal diseases: data from the National Paediatric Rheumatology Database in Germany.

OBJECTIVES: This study aimed to investigate the clinical manifestations, course and outcome of SARS-CoV-2 infection among children and adolescents with rheumatic and musculoskeletal diseases (RMD). Due to their underlying disease as well due to therapeutic immunosuppression, these patients may be at risk for a severe course of COVID-19 or for a flare of the underlying disease triggered by SARS-CoV-2 infection. METHODS: Demographic, clinical and treatment data from juvenile patients with RMD as well as data about SARS-CoV-2 infection like test date and method, clinical characteristics, disease course, outcome and impact on the disease activity of the RMD were documented on a specific SARS-CoV-2 questionnaire implemented in the National Paediatric Rheumatology Database (NPRD) in Germany. The survey data were analysed descriptively. RESULTS: From 17 April 2020 to 16 February 2021, data were collected from 76 patients (52% female) with RMD and laboratory-proven SARS-CoV-2 infection with median age of 14 years, diagnosed with juvenile idiopathic arthritis (58%), autoinflammatory (24%) and connective tissue disease (8%). Fifty-eight patients (76%) received disease-modifying antirheumatic drugs (DMARDs), 41% biological DMARDs and 11% systemic glucocorticoids. Fifty-eight (76%) had symptoms of COVID-19. Disease course of SARS-CoV-2 infection (classified as asymptomatic, mild, moderate, severe, life-threatening) was mild and outcome of COVID-19 (classified as recovered, not yet recovered, permanent damage or deceased) was good (recovered) in the majority of patients. Two patients were hospitalised, one of whom required intensive care and died of cardiorespiratory failure. In 84% of SARS-CoV-2-positive patients, no relevant increase in disease activity of the RMD was observed. CONCLUSIONS: In our cohort, SARS-CoV-2 infection in juvenile patients with RMD under various medications was mild with good outcome in the majority of cases and does not appear to have a relevant impact on disease activity of the underlying condition.

Cleavage of the Ewing tumour-specific EWSR1-FLI1 mRNA by hammerhead ribozymes.

BACKGROUND: Ewing family tumours (EFT) are the second most common bone tumours in children and adolescents. In the majority of EFT, EWSR1-FLI1 (Ewing sarcoma breakpoint region 1-Friend leukaemia virus integration 1) fusion proteins can be detected and EWSR1-FLI1 substantially contributes to the malignant phenotype of EFT. Therefore, inactivation of EWSR1-FLI1 is an interesting strategy for EFT therapy. MATERIALS AND METHODS: A ribozyme with specificity for EWSR1-FLI1 was developed and the activity in vitro was investigated. Synthetic RNAs corresponding to EWSR1-FLI1 were used as substrates. In addition, the total RNA from EFT cells was used as substrate and the rapid amplification of cDNA ends method for the detection of the cleavage products was used. RESULTS: The ribozyme cleaved the synthetic RNA in a sequence specific manner with high efficiency in vitro. Furthermore, the expected cleavage products were detected after digestion of the total cellular RNA with this ribozyme. A point mutation in the catalytic centre of the ribozyme abolished enzymatic activity. CONCLUSION: The RNA corresponding to EWSR1-FLI1 is accessible for ribozyme mediated inactivation and ribozymes are able to cleave EWSR1-FLI1 specific RNA in the presence of a high background of normal cellular RNAs.