Cell-intrinsic sphingosine kinase 2 promotes macrophage polarization and renal inflammation in response to unilateral ureteral obstruction

• Published in: PloS one Vol. 13; no. 3; p. e0194053
• Main Authors: Ghosh, Mallika, Thangada, Shobha, Dasgupta, Oisharya, Khanna, Kamal M, Yamase, Harold T, Kashgarian, Michael, Hla, Timothy, Shapiro, Linda H, Ferrer, Fernando A
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 08-03-2018; Public Library of Science (PLoS)
• Subjects: Actins - biosynthesis; Actins - genetics; Analysis; Animals; Biology; Biology and Life Sciences; Bone marrow; Bone marrow transplantation; Cell adhesion & migration; Cellular Microenvironment; Children & youth; Comparative analysis; Cytokines; Cytokines - biosynthesis; Cytokines - genetics; Cytometry; Damage; Fibrosis; Flow cytometry; Gene Expression Regulation - immunology; Glycolysis; Health aspects; Immunology; Inflammation; Injury prevention; Interleukin 13; Interleukin 4; Kidney; Kidney - enzymology; Kidney - pathology; Kidney diseases; Kidneys; Kinases; Lysophospholipids - blood; Lysophospholipids - physiology; Macrophage Activation; Macrophages; Macrophages - physiology; Male; Medicine; Medicine and Health Sciences; Metabolism; Mice; Mice, Inbred C57BL; mRNA; Nephritis, Interstitial - enzymology; Nephritis, Interstitial - etiology; Nephritis, Interstitial - immunology; Nephritis, Interstitial - pathology; Occupant injuries; Pathology; Pharmacology; Phenotypes; Phosphotransferases (Alcohol Group Acceptor) - antagonists & inhibitors; Phosphotransferases (Alcohol Group Acceptor) - deficiency; Phosphotransferases (Alcohol Group Acceptor) - physiology; Promoters (Genetics); Protein Isoforms - physiology; Protein Kinase Inhibitors - pharmacology; Research and Analysis Methods; RNA, Messenger - biosynthesis; RNA, Messenger - genetics; Rodents; Sphingosine - analogs & derivatives; Sphingosine - blood; Sphingosine - physiology; Sphingosine kinase; Stem cell transplantation; Transforming Growth Factor beta1 - biosynthesis; Transforming Growth Factor beta1 - genetics; Transforming growth factor-b1; Tumor necrosis factor-α; Ureteral obstruction; Ureteral Obstruction - complications; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0194053

Sphingosine Kinase-2 (Sphk2) is responsible for the production of the bioactive lipid Sphingosine-1 Phosphate, a key regulator of tissue repair. Here we address the in vivo significance of Sphingosine Kinase -2 in renal inflammation/fibrosis in response to unilateral ureteral obstruction using both genetic and pharmacological strategies. Obstructed kidneys of Sphk2-/- mice showed reduced renal damage and diminished levels of the renal injury markers TGFβ1 and αSMA when compared to wild type controls. We found a consistently significant increase in anti-inflammatory (M2) macrophages in obstructed Sphk2-/- kidneys by flow cytometry and a decrease in mRNA levels of the inflammatory cytokines, MCP1, TNFα, CXCL1 and ILβ1, suggesting an anti-inflammatory bias in the absence of Sphk2. Indeed, metabolic profiling showed that the pro-inflammatory glycolytic pathway is largely inactive in Sphk2-/- bone marrow-derived macrophages. Furthermore, treatment with the M2-promoting cytokines IL-4 or IL-13 demonstrated that macrophages lacking Sphk2 polarized more efficiently to the M2 phenotype than wild type cells. Bone marrow transplant studies indicated that expression of Sphk2-/- on either the hematopoietic or parenchymal cells did not fully rescue the pro-healing phenotype, confirming that both infiltrating M2-macrophages and the kidney microenvironment contribute to the damaging Sphk2 effects. Importantly, obstructed kidneys from mice treated with an Sphk2 inhibitor recapitulated findings in the genetic model. These results demonstrate that reducing Sphk2 activity by genetic or pharmacological manipulation markedly decreases inflammatory and fibrotic responses to obstruction, resulting in diminished renal injury and supporting Sphk2 as a novel driver of the pro-inflammatory macrophage phenotype.