Case report : characterizing the role of the STXBP2-R190C monoallelic mutation found in a patient with hemophagocytic syndrome and Langerhans cell histiocytosis
Viñas Gimenez, Laura (Universitat Autònoma de Barcelona. Departament de Biologia Cel·lular, de Fisiologia i d'Immunologia)
Rincón, Rafael (Hospital Universitari Vall d'Hebron)
Colobrán Oriol, Roger (Universitat Autònoma de Barcelona. Departament de Biologia Cel·lular, de Fisiologia i d'Immunologia)
de la Cruz, Xavier (Institució Catalana de Recerca i Estudis Avançats)
Celis, Verónica Paola (Hospital Sant Joan de Déu (Barcelona, Catalunya). Servei d'Hematologiai Oncologia Pediàtrica)
Dapena, José Luis (Hospital Sant Joan de Déu (Barcelona, Catalunya). Servei d'Hematologiai Oncologia Pediàtrica)
Alsina Manrique, Laia (Hospital Sant Joan de Déu (Barcelona, Catalunya). Servei d'Al·lèrgia i Immunologia Clínica)
Sayós, Joan (Hospital Universitari Vall d'Hebron. Institut de Recerca)
Martínez Gallo, Mónica (Universitat Autònoma de Barcelona. Departament de Biologia Cel·lular, de Fisiologia i d'Immunologia)

Fecha:	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.
Ayudas:	Instituto de Salud Carlos III PI17/00660 Instituto de Salud Carlos III PI18/00346
Derechos:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Materia:	HLH ; STXBP2 ; Langerhans-cell-histiocytosis ; Degranulation ; NK ; Familial hemophagocytic lymphohistiocytosis−5 (f-HLH) ; Lytic granule exocytosis ; STX11
Publicado en:	Frontiers in immunology, Vol. 12 (September 2021) , art. 723836, ISSN 1664-3224

DOI: 10.3389/fimmu.2021.723836
PMID: 34630398

5 p, 2.4 MB

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