Syntaxin 11 is required for NK and CD8⁺ T‐cell cytotoxicity and neutrophil degranulation

Abstract

Syntaxin 11 (STX11) controls vesicular trafficking and is a key player in exocytosis. SinceStx11 mutations are causally associated with a familial hemophagocytic lymphohistiocytosis, we wanted to clarify whether STX11 is functionally important for key immune cell populations. This was studied in primary cells obtained from newly generated Stx11 −/− mice. Our data revealed that STX11 is not only widely expressed in different immune cells, but also induced upon LPS or IFN-γ treatment. However, Stx11 deficiency does not affect macrophage phagocytic function and cytokine secretion, mast cell activation, or antigen presentation by DCs. Instead, STX11 selectively controls lymphocyte cytotoxicity in NK and activated CD8 + T cells and degranulation in neutrophils. Stx11 −/− NK cells and CTLs show impaired degranulation, despite a comparable activation, maturation and expression of the complex-forming partners MUNC18-2 and VTI1B. In addition, Stx11 −/− CTLs and NK cells produce abnormal levels of IFN-γ. Since functional reconstitution rescues the defective phenotype of Stx11 −/− CTLs, we suggest a direct, specific and key role of STX11 in controlling lymphocyte cytotoxicity, cytokine production and secretion. Finally, we show that these mice are a very useful tool for dissecting the role of STX11 in vesicular trafficking and secretion. Keywords: CTL r Cytokines r Exocytosis r N-ethylmaleimide-sensitive factor attachment protein receptorSee accompanying Commentary by Lopez and Voskoboinik.Additional supporting information may be found in the online version of this article at the publisher's web-site IntroductionSyntaxin 11 (STX11) belongs to the family of N-ethylmaleimidesensitive factor attachment protein receptor (SNARE) proteins Correspondence: Prof. Silvia Bulfone-Paus e-mail: sbulfone@fz-borstel.de and is involved in intracellular membrane trafficking events by interacting with other family members or by associating with membranes by palmitoylation of cysteine residues [1][2][3]. STX11 is expressed in a wide variety of cells including human monocytes/macrophages, neutrophils, B cells, NK cells and CD8 + T cells [2][3][4][5][6][7][8][9]. STX11 is enriched in immune tissues such as thymus, spleen C 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.eji-journal.eu Eur. J. Immunol. 2013. 43: 194-208 Immunomodulation 195 Values represent the mean ± SEM percentage of cell subsets in the spleen (n = 8) and lymph nodes (WT n = 7; Stx11 −/− n = 6) and are the summary of three experiments performed.and lymph nodes, but lower levels of protein are detectable also in heart, kidney and liver [2]. STX11 localizes mainly in the vesicular tubular clusters, an organelle complex between the endoplasmic reticulum and the Golgi, and displays, in addition, a spotted staining pattern throughout the cell periphery [2,9]. While STX11 has been recognized to act as a negative regulator of both phagocytosis and intracellular trafficking between endosomes, lysosomes and the outer membrane in macrophages [6,9], in human NK cells and CTLs, ST...

Hemophagocytic lymphohistiocytosis (HLH): A heterogeneous spectrum of cytokine-driven immune disorders

“…To study fHLH4, two independent research groups developed Stx11-deficient mouse lines by complete deletion of exon 3, the only coding exon, in the Stx11 gene. This resulted in a defective degranulation of NK cells as well as CD8 + T cells, even though weak residual T cell cytotoxicity remained detectable [23,40,41].…”

“…1). Roughly 10% of fHLH patients carry an STX11 mutation [7,8,40]. To study fHLH4, two independent research groups developed Stx11-deficient mouse lines by complete deletion of exon 3, the only coding exon, in the Stx11 gene.…”

Hemophagocytic lymphohistiocytosis in syntaxin-11–deficient mice: T-cell exhaustion limits fatal disease

“…They exhibit no pigmentation defects, and their primary and secondary lymphoid organs appear normal in size and composition (supplemental Table 1, available on the Blood Web site; see the Supplemental Materials link at the top of the online article). 25 Mice with deficiencies in genes of the cytolytic machinery do not develop HLH spontaneously. [26][27][28][29] However, after LCMV infection, these mice exhibit clinical symptoms and laboratory abnormalities characteristic for HLH patients, with the exception that fever diagnosed in patients is mirrored by a drop in ear temperature in mice.…”

“…Stx11 Ϫ/Ϫ mice were generated by Udo zur Stadt on a C57BL/6 background by deletion of the only coding exon. 25 Perforin-deficient C57BL/6-Prf1 tm1Sdz (PKO) mice were obtained from Dr Hengartner (Zurich). Mice were kept under specific pathogen-free conditions.…”

Mouse Cytomegalovirus Infection in BALB/c Mice Resembles Virus-Associated Secondary Hemophagocytic Lymphohistiocytosis and Shows a Pathogenesis Distinct from Primary Hemophagocytic Lymphohistiocytosis

“…With regard to primary HLH, considerable progress has been made in deciphering its pathogenesis, largely by studying mouse strains that carry similar mutations as those occurring in the different subtypes of primary HLH (3)(4)(5)(6)(7)(8)(9). In HLH disease models using these mouse strains, hyperactivated CD8 + T cells, producing large amounts of IFN-g, were pinpointed as major pathogenic players.…”