Case Report: Characterizing the Role of the STXBP2-R190C Monoallelic Mutation Found in a Patient With Hemophagocytic Syndrome and Langerhans Cell Histiocytosis
Por:
Viñas-Giménez L, Rincón R, Colobran R, de la Cruz X, Celis-Passini V, Dapena JL, Alsina L, Sayós J and Martínez-Gallo M
Publicada:
23 sep 2021
Ahead of Print:
23 sep 2021
Resumen:
Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory disorder. HLH can be considered as a threshold disease depending on the trigger and the residual NK-cell cytotoxicity. In this study, we analyzed the molecular and functional impact of a novel monoallelic mutation found in a patient with two episodes of HLH. A 9-month-old child was diagnosed at 2 months of age with cutaneous Langerhans cell histiocytosis (LCH). After successful treatment, the patient developed an HLH episode. At 16 month of age, the patient went through an HSCT losing the engraftment 5 months later concomitant with an HLH relapse. The genetic study revealed a monoallelic mutation in the STXBP2 gene (.pArg190Cys). We transfected COS7 cells to analyze the STXBP2-R190C expression and to test the interaction with STX11. We used the RBL-2H3 cell line expressing STXBP2-WT-EGFP or R190C-EGFP for degranulation assays. Mutation STXBP2-R190C did not affect protein expression or interaction with syntaxin-11. However, we have demonstrated that STXBP2-R190C mutation diminishes degranulation in the RBL-2H3 cell line compared with the RBL-2H3 cell line transfected with STXBP2-WT or nontransfected. These results suggest that STXBP2-R190C mutation acts as a modifier of the degranulation process producing a decrease in degranulation. Therefore, under homeostatic conditions, the presence of one copy of STXBP2-R190 could generate sufficient degranulation capacity. However, it is likely that early in life when adaptive immune system functions are not sufficiently developed, an infection may not be resolved with this genetic background, leading to a hyperinflammation syndrome and eventually develop HLH. This analysis highlights the need for functional testing of new mutations to validate their role in genetic susceptibility and to establish the best possible treatment for these patients.
Filiaciones:
Viñas-Giménez L:
Immunology Division, Hospital Universitari Vall d'Hebron (HUVH), Jeffrey Model Foundation Excellence Center, Barcelona, Spain
Diagnostic Immunology Research Group Vall d'Hebron Research Institute (VHIR), Barcelona, Spain
Department of Cell Biology, Physiology and Immunology, Autonomous University of Barcelona (UAB), Barcelona, Spain
Rincón R:
Immunology Division, Hospital Universitari Vall d'Hebron (HUVH), Jeffrey Model Foundation Excellence Center, Barcelona, Spain
Colobran R:
Immunology Division, Hospital Universitari Vall d'Hebron (HUVH), Jeffrey Model Foundation Excellence Center, Barcelona, Spain
Diagnostic Immunology Research Group Vall d'Hebron Research Institute (VHIR), Barcelona, Spain
Department of Cell Biology, Physiology and Immunology, Autonomous University of Barcelona (UAB), Barcelona, Spain
Genetics Department, Hospital UniversitariVall d'Hebron (HUVH), Barcelona, Spain
de la Cruz X:
Research Unit in Translational Bioinformatics in Neurosciences, Universitat Autònoma de Barcelona, Barcelona, Spain
Institut Catala per la Recerca i Estudis Avançats (ICREA), Barcelona, Spain
Celis-Passini V:
Hematology Department, Pediatric Cancer Center, Hospital Sant Joan de Déu, Esplugues de Llobregat, Spain
Dapena JL:
Hematology Department, Pediatric Cancer Center, Hospital Sant Joan de Déu, Esplugues de Llobregat, Spain
Alsina L:
Clinical Immunology and Primary Immunodeficiencies Unit, Allergy and Clinical Immunology Department, Hospital Sant Joan de Déu, University of Barcelona, Pediatric Research Institute Sant Joan de Déu, Barcelona, Spain
Sayós J:
Immune Regulation and Immunotherapy Group, CIBBIM-Nano medicine, Vall d'Hebron Institut de Recerca, Universitat Autonoma de Barcelona, Barcelona, Spain
Martínez-Gallo M:
Immunology Division, Hospital Universitari Vall d'Hebron (HUVH), Jeffrey Model Foundation Excellence Center, Barcelona, Spain
Diagnostic Immunology Research Group Vall d'Hebron Research Institute (VHIR), Barcelona, Spain
Department of Cell Biology, Physiology and Immunology, Autonomous University of Barcelona (UAB), Barcelona, Spain
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