Project area II

P04: Role of acid sphingomyelinase in experimental inflammatory bowel disease

• Prof. Dr. Astrid M. Westendorf

Institute of Medical Microbiology, E-Mail: astrid.westendorf@uk-essen.de

• Prof. Dr. Richard Kolesnick

Memorial Sloan-Kettering Cancer Center, NY, USA,
E-Mail: r-kolesnick@ski.mskcc.org

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder, which is characterized by repeated cycles of mucosal damage, ulceration and regeneration. Although the pathogenesis is not fully understood, impairment of the epithelial barrier function plays an important physiological role. Intestinal permeability is not only influenced by epithelial cells but also by endothelial cells and intestinal stem cells, cells crucial for providing oxygen and nutrients to the intestine by blood flow and for rapidly self-renewing the intestinal tract, respectively. Increasing evidence implicates a function of acid sphingomyelinase (Asm) in development of IBD as inhibition of Asm has been shown to reduce DSS-induced colitis in mice. In the present project, we will analyze the pathogenic function of Asm on acute and chronic intestinal inflammation and delineate the differential contribution of epithelial cell-, endothelial cell-, and intestinal stem cell-derived Asm. Detailing Asm impact in intestinal inflammation will allow development of new and more specific therapeutic strategies in IBD.
 

P05: Molecular mechanisms of altered sphingolipid homeostasis in Graves’ Orbitopathy

• Prof. Dr. Anja Eckstein

Center of Ophthalmology, E-Mail: anja.eckstein@uk-essen.de

• PD Dr. Utta Berchner-Pfannschmidt

Laboratory of Molecular Ophthalmology,
E-Mail: utta.berchner-pfannschmidt@uk-essen.de 

• Prof. Dr. Edward H. Schuchman

Department of Genetics and Genomic Sciences, NY, USA,
E-Mail: edward.schuchman@mssm.edu

Graves orbitopathy (GO), characterized by orbital inflammation, proptosis and restrictive myositis, occurs in about 50% of patients with thyroid autoimmunity. Myositis evolves with yet unexplained regional differences, i.e. only levator palpebrae, medial and inferior rectus muscles are affected. Orbital fibroblasts are activated by the autoimmune process of GO leading to inflammation, fibrosis and/or increased adipogenesis and seem to be central in the pathogenicity of GO. Our data show that cultured GO orbital fibroblasts exhibit a constitutive increase of acid sphingomyelinase (Asm) activity and ceramide as well as sphingosine 1-phosphate (S1P) levels compared to orbital fibroblasts from healthy individuals. The changes of the Asm/ceramide/S1P system in these cells are further enhanced by ligation of CD40. Suppression of Asm activity reduced ceramide levels and pathologic hallmarks of GO such as cell proliferation, hyaluronic acid (HA) production and reactive oxygen species (ROS) release. These studies indicate that the sphingomyelin cycle is dysregulated in GO orbital fibroblasts. Thus, we aim to define the molecular mechanisms and functions of the Asm/ceramide/S1P system in GO orbital fibroblasts and test whether genetic or pharmacologic interference with this system prevents or cures GO in an animal model.

P06: Role of acid sphingomyelinase in mycobacterial infections

• Prof. Dr. Karl S. Lang

Institute of Immunology, E-Mail: karlsebastian.lang@uk-essen.de

• Dr. Heike Grassmé

Institute of Molecular Biology, E-Mail: heike.gulbins@uni-due.de

• Prof. Dr. Frederick Maxfield

Department of Biochemistry, E-Mail: frmaxfie@med.cornell.edu

We have shown that acid sphingomyelinase (Asm) is crucially involved in the interaction of mammalian host cells with N. gonorrhoeae, P. aeruginosa, and S. aureus. How ceramide regulates uptake, intracellular processing, and immune response against Mycobacterium bovis Bacillus Calmette Guérin (BCG) is unknown. Preliminary work has shown that infecting murine macrophages with BCG results in the activation of Asm and the release of ceramide, both of which are important for the uptake and intracellular killing of the pathogen. In vivo, unlike wild-type (wt) mice, Asm^-/- mice fail to produce TNF-α, IL-8, and IFN-gamma; to trigger sufficient CD4+ T-cell expansion; and to form granulomas in spleen and liver after infection. In the proposed studies we will determine the role of the Asm/ceramide system in (i) the formation of a lysosomal synapse at the interaction site of macrophages with the pathogen and the uptake and intracellular processing of BCG, (ii) the local control and elimination of BCG in granulomas, and (iii) the activation of the adaptive immune system by BCG.

P07: Preventing infection in cystic fibrosis with acid ceramidase

• Prof. Dr. Erich Gulbins

Institute of Molecular Biology, E-Mail: erich.gulbins@uni-due.de

• Prof. Dr. Edward H. Schuchman

Department of Genetics and Genomic Sciences Mount Sinai School of Medicine 
NY, USA, E-Mail: edward.schuchman@mssm.edu

Cystic fibrosis (CF) is characterized by pulmonary inflammation, decreased mucociliary clearance, and chronic pulmonary infections with Pseudomonas aeruginosa or Staphylococcus aureus. We have previously shown that a mutation of the CFTR gene in CF patients and mice causes the accumulation of ceramide in bronchial and tracheal epithelial cells (Pewzner-Jung Y, Tavakoli Tabazavareh S, Grassmé H, Becker KA, Japtok L, Steinmann J, Joseph T, Lang S, Tuemmler B, Schuchman EH, Lentsch AB, Kleuser B, Edwards MJ, Futerman AH, Gulbins E. Sphingoid long chain bases prevent lung infection by Pseudomonas aeruginosa. EMBO Mol Med 2014;6:1205-1).Ceramide mediates chronic inflammation, bronchial epithelial cell death and determines susceptibility of CF mice to pulmonary P. aeruginosa infections (Teichgräber V, Ulrich M, Endlich N, Riethmüller J, Wilker B, De Oliveira-Munding CC, van Heeckeren AM, Barr ML, von Kürthy G, Schmid KW, Weller M, Tümmler B, Lang F, Grassmé H, Döring G, Gulbins E. Ceramide accumulation mediates inflammation, cell death and infection susceptibility in cystic fibrosis. Nat Med 2008;14:382-91). Further data indicate that inhalation of acid ceramidase normalizes bronchial ceramide levels, and this normalization prevents P. aeruginosa infections in CF mice; in fact, inhalation of acid ceramidase promotes the resolution of established pulmonary infection in these mice. We now aim to (i) determine the effect of acid ceramidase on bronchial epithelial cells from CF mice, (ii) define the effect of acid ceramidase on chronic inflammation in CF, (iii) perform detailed kinetic studies of the effect of acid ceramidase inhalation on acute and chronic pneumonia in CF mice, and (iv) identify potential adverse effects of acid ceramidase inhalation. These studies will facilitate the transfer of this novel CF treatment to the clinic.