The sphingosine kinase 1 and S1P1 axis specifically counteracts LPS-induced IL-12p70 production in immune cells of the spleen☆
Introduction
Sphingosine kinase (Sphk) 1 is a highly conserved enzyme that catalyzes the conversion of sphingosine to sphingosine-1-phosphate (S1P) (Vadas et al., 2008). The mSphK1 gene is located on chromosome 11 E2 and encodes for a 43-kDa protein for which the highest expression levels are found in the lungs, liver, and spleen (Wadgaonkar et al., 2009). Deletion mutant mice for SphK1 showed no obvious phenotype. These findings led to the assumption that the second SphK subtype, SphK2, which is located on chromosome 7 and exhibits different enzymatic kinetic properties (Liu et al., 2000) and substrate specificity (Olivera et al., 1998, Wattenberg et al., 2006), may functionally compensate for the lack of SphK1; this however has only been shown during embryogenesis and under resting conditions. SphK1 and SphK2 are also located in different compartments inside the cell. Several studies have shown that SphK1 is activated rapidly by cytokines and growth factors (Cuvillier et al., 1996) and then translocates to the plasma membrane or to the outer nucleus membrane which has not been observed for SphK2 (Alemany et al., 2007, Kleuser et al., 2001). Recent studies suggested an involvement of calcium signaling (Ghosh et al., 1990), MAPK (Bu et al., 2006) and the LPS-TLR pathway for the induction of SphK1 expression (Wadgaonkar et al., 2009). Together with other studies showing a coordinated regulation of SphK1 in parallel to external and internal stimuli, this points to a modulatory role either directly of SphK1 or via its product S1P.
Since the first description of its effect in cellular signaling in 1991 (Zhang et al., 1991) the knowledge about S1P as extra- and intracellular messenger has grown exponentially. S1P, generated by either of the two kinases, has pleiotropic effects within several different tissues. The extra- and intracellular sphingolipid levels are additionally regulated by catabolic enzymes dephosporylating or cleaving S1P (Brindley, 2004, Melendez, 2008, Saba and Hla, 2004). Its prominent role for immune regulation has been uncovered by its partial analog FTY720 (Kappos et al., 2010) and more recent studies with S1P-lyase−/−, S1P-lyase−/+ and humanized S1P-lyaseh/h mice showing different lyase activities (Vogel et al., 2009). While rescue of S1P-lyase deficiency with hS1P-lyase could compensate the lethal non-lymphoid lesion formation, T cell development and trafficking could not be restored, indicating that immunologic processes may be more sensitive than others. S1P is predominantly produced and secreted by macrophages, platelets, mast cells and dendritic cells (DC) (Goetzl et al., 2004). Whereas increasing evidence of intracellular functions/targets for S1P exist (Alvarez et al., 2010, Hait et al., 2009, Itagaki et al., 2007, Olivera and Spiegel, 1993) the most well-characterized functions of S1P are mediated via five different G-protein-coupled-receptors (GPCR) named S1P1-5 (Spiegel and and Milstien, 2003). Thus depending on the subset of receptors, which are expressed on the surface of the cell, different intracellular pathways are triggered upon S1P-binding, regulating physiological and pathophysiological functions.
Research on the function of SphK/S1P in different immune cells or its involvement in clinical relevant diseases like colitis, rheumatoid arthritis and sepsis have shown that SphK activity, and subsequently altered S1P concentrations, can not easily be attributed to either pro- or anti-inflammatory responses. While SphK1, rather than SphK2 activity, has been linked to the release of pro-inflammatory cytokines such as IL-1β, IL-6 and TNFα in monocytes (Puneet et al., 2010, Zhi et al., 2006) and macrophages (Puneet et al., 2010, Yadav et al., 2006) and also promoted inflammation in rheumatoid arthritis (Baker et al., 2010, Kitano et al., 2006), colitis (Maines et al., 2008) and sepsis models (Puneet et al., 2010) contrasting investigations exist showing e.g. that Th1 cells overexpressing SphK1 produced less IL-2, IFNγ and TNFα (Wang et al., 2005, Yang et al., 2005).
The spleen is the largest secondary lymphoid organ containing about one-fourth of the body's lymphocytes and is involved in immune responses to blood-derived microbes (Nolte et al., 2002). Thus, given the conflicting results regarding a pro- or anti-inflammatory function of SphK1 and its product S1P we sought to analyze in detail their role for the specific DC cytokine IL-12p70 compared to other above mentioned cytokines in this organ. Therefore, we used SphK1-deficient mice and S1P1-specific agonists to investigate in detail how SphK1 and the product derived from its activity, S1P, and the subsequent S1P signaling affects TLR ligand-induced IL-12p35 and IL-12p40 expression of DCs in a complex mixture of splenocytes and in Flt3-ligand differentiated CD8α+ cDCs which are supposed to be the main producers of biological active IL-12p70 (Shortman and Heath, 2010). Herein, we will demonstrate that SphK1 deficiency enhanced LPS-induced IL-12p70 but not IL-6 or IL-10 production, and that S1P1-specific agonists are sufficient to compensate for SphK1 deficiency in spleen-derived immune cells.
Section snippets
Preparation and cultivation of splenocytes and bone marrow cells
WT C57BL/6 mice were purchased from Harlan Winkelmann; SphK1 knockout (SphK1−/−) mice, backcrossed to the C57BL/6 background were bred at the local animal facility under specific pathogen-free conditions.
Whole spleens were dissected from mice, gently homogenized with a glass tissue homogenizer, and cultured in Iscove‘s medium supplemented with 5% FCS (PAA Laboratories), 2 mM l-glutamine, 100 IU/ml penicillin, 100 μg/ml streptomycin, 1 mM sodium pyruvate, 100 μM nonessential amino acids and 50 μM 2-ME
Genetic deletion of SphK1 and its impact on TLR-dependent activation of immune cells
In recent years several studies have reported about the important role of S1P in various clinical aspects of diseases especially by preventing apoptosis and inducing cell growth and consequently promoting cancer growth and progression (see Section 1). Additionally, it has been shown that SphK1 but not SphK2 is upregulated in many cancer tissues. Given these divergent characteristics of SphK1 and SphK2 and the suggested opposing function of IL-12p70 and IL-23 in inflammation-derived cancer, we
Discussion
The immune suppressive effects of disrupting the gradient of S1P concentrations have been well established, e.g. in governing the lymphocyte migration between blood and secondary lymphatic organs or within the thymus with subsequent lymphocyte sequestration (Mandala et al., 2002). All three of the major S1P level determining sphingolipid enzymes, i.e. S1P lyase, sphingosine kinase-1 and -2 are involved. However recently additional and more direct cytokine or gene regulatory functions of both
Conflict of interest
The authors have no financial conflict of interest.
Acknowledgements
We like to thank Dagmar Meyer zu Heringdorf for their valuable and thoughtful input, as well as Alexander Koch for his support in animal supply.
References (54)
- et al.
Phosphoinositide-mediated adaptor recruitment controls Toll-like receptor signaling
Cell
(2006) - et al.
Stimulation of nuclear sphingosine kinase activity by platelet-derived growth factor
FEBS Lett.
(2001) - et al.
Molecular cloning and functional characterization of a novel mammalian sphingosine kinase type 2 isoform
J. Biol. Chem.
(2000) Sphingosine kinase signalling in immune cells: potential as novel therapeutic targets
Biochim. Biophys. Acta
(2008)Unraveling the complexities of sphingosine-1-phosphate function: the mast cell model
Prostaglandins Other Lipid Mediat.
(2008)- et al.
Purification and characterization of rat kidney sphingosine kinase
J. Biol. Chem.
(1998) - et al.
The role of sphingosine kinase 1 in cancer: oncogene or non-oncogene addiction?
Biochim. Biophys. Acta
(2008) - et al.
Sphingosine 1-phosphate and platelet-derived growth factor (PDGF) act via PDGF beta receptor-sphingosine 1-phosphate receptor complexes in airway smooth muscle cells
J. Biol. Chem.
(2003) - et al.
c-Src is involved in regulating signal transmission from PDGFbeta receptor-GPCR(s) complexes in mammalian cells
Cell Signal.
(2005) - et al.
The sphingosine and diacylglycerol kinase superfamily of signaling kinases: localization as a key to signaling function
J. Lipid Res.
(2006)
Normal neutrophil functions in sphingosine kinase type 1 and 2 knockout mice
Immunol. Lett.
Regulation and functional roles of sphingosine kinases
Naunyn Schmiedebergs Arch. Pharmacol.
Sphingosine-1-phosphate is a missing cofactor for the E3 ubiquitin ligase TRAF2
Nature
Genetic sphingosine kinase 1 deficiency significantly decreases synovial inflammation and joint erosions in murine TNF-alpha-induced arthritis
J. Immunol.
Lipid phosphate phosphatases and related proteins: signaling functions in development, cell division, and cancer
J. Cell Biochem.
Dihydrosphingosine 1-phosphate stimulates MMP1 gene expression via activation of ERK1/2-Ets1 pathway in human fibroblasts
FASEB J.
Interleukin-35: odd one out or part of the family?
Immunol. Rev.
Platelet-derived-growth-factor stimulation of the p42/p44 mitogen-activated protein kinase pathway in airway smooth muscle: role of pertussis-toxin-sensitive G-proteins, c-Src tyrosine kinases and phosphoinositide 3-kinase
Biochem. J.
Suppression of ceramide-mediated programmed cell death by sphingosine-1-phosphate
Nature
Sphingosine 1-phosphate 1 and TLR4 mediate IFN-beta expression in human gingival epithelial cells
J. Immunol.
TLR4 and S1P receptors cooperate to enhance inflammatory cytokine production in human gingival epithelial cells
Eur. J. Immunol.
Intracellular calcium release mediated by sphingosine derivatives generated in cells
Science
Mouse interleukin-12 (IL-12) p40 homodimer: a potent IL-12 antagonist
Eur. J. Immunol.
Sphingosine 1-phosphate and its G protein-coupled receptors constitute a multifunctional immunoregulatory system
J. Cell Biochem.
Full pharmacological efficacy of a novel S1P1 agonist that does not require S1P-like headgroup interactions
Mol. Pharmacol.
Regulation of histone acetylation in the nucleus by sphingosine-1-phosphate
Science
Sphingosine-1-phosphate induces an antiinflammatory phenotype in macrophages
Circ. Res.
Cited by (30)
Host sphingolipids: Perspective immune adjuvant for controlling SARS-CoV-2 infection for managing COVID-19 disease
2021, Prostaglandins and Other Lipid MediatorsCitation Excerpt :On the basis of this report, it is possible that a crosstalk of these receptors may contribute to fibrosis in COVID-19 patients as well. Interestingly, S1PR1 signaling is associated with Th1/ Th2 / 17 responses [24,25] in context dependent manner. Apart from this, S1PR1 signaling promotes hypoxia, asthmatic reactions [26] and anti-inflammatory response [27,28] in cancer patients.
Sphingosine kinase 2 cooperating with Fyn promotes kidney fibroblast activation and fibrosis via STAT3 and AKT
2018, Biochimica et Biophysica Acta - Molecular Basis of DiseaseCitation Excerpt :Sphingosine kinases (Sphks) are the major rate-limiting enzymes in the generation of biologically active sphingosine-1-phosphate (S1P) [18]. In mammals, two distinct Sphk isoforms, Sphk1 and Sphk2, have been characterized: Sphk1 is expressed primarily in the lung and spleen, where it promotes cell survival and inhibits apoptosis [19,20], and Sphk2 is highly expressed in the liver and heart [21,22]. Both Sphk1 and Sphk2 are found in the kidney [23].
Sphingosine metabolism as a therapeutic target in cutaneous melanoma
2017, Translational ResearchCitation Excerpt :Disrupting the gradient by topical application of S1P prevented the migration of dendritic cells from the epidermis to the lymph nodes.92 Finally, S1P exerts anti-inflammatory roles in the skin by decreasing the levels of IL-12 release from activated dendritic cells and by decreasing the activation of T helper cells.93 Although S1P inhibits the proliferation of keratinocytes, this is not the case in human melanoma cells.
Antigen delivery via hydrophilic PEG-b-PAGE-b-PLGA nanoparticles boosts vaccination induced T cell immunity
2016, European Journal of Pharmaceutics and BiopharmaceuticsCitation Excerpt :Myeloid antigen presenting cells (mAPC) used in this study have all been generated from bone marrow of C57BL/6J mice. The bone marrow isolation protocol was performed as published previously [30]. Briefly, bone marrow cells were isolated from the hind legs of the mice and cultured in Roswell Park Memorial Institute (RPMI) medium supplemented with 10% FCS, 100 IU/mL penicillin, 100 μg/mL streptomycin, 50 μM β-mercaptoethanol and 100 nM macrophage colony-stimulating factor (M-CSF), for differentiation, in a humidified incubator (5% CO2 and 37 °C) at a cell concentration of 0.8 × 106 cells/mL in an untreated Petri dish.
Sphingosine-1-phosphate differently regulates the cytokine production of IL-12, IL-23 and IL-27 in activated murine bone marrow derived dendritic cells
2014, Molecular ImmunologyCitation Excerpt :S1P acts as an intracellular second messenger (Meyer zu Heringdorf et al., 1999) but also via 5 G-protein coupled receptors, which explains the complexity of S1P mediated action (Spiegel and Milstien, 2003). The ability of S1P to affect immune-cell functions such as lymphocyte trafficking and dendritic cell (DC) migration has been thoroughly investigated (Matloubian et al., 2004; Davis and Kehrl, 2009; Reines et al., 2009; Schroder et al., 2011). For instance, it has been shown that S1P receptor 1 (S1PR1) is needed for the egress of T- and B-cells from lymphoid organs (Schwab and Cyster, 2007) and that S1P impairs Langerhans cell migration through the skin in a murine model of allergic contact dermatitis (Reines et al., 2009).
Sphk1 deficiency induces apoptosis and developmental defects and premature death in zebrafish
2023, Fish Physiology and Biochemistry
- ☆
This work was supported by the Deutsche Forschungsgemeinschaft (Graduate College 1172), Merck KGaA, the Swiss National Foundation and the Lipid Signaling Forschungszentrum Frankfurt (LIFF).