title: Alkaline Cytosolic pH and High Sodium Hydrogen Exchanger 1 (NHE1) Activity in Th9 Cells.
abstract: CD4+T helper 9 (Th9) cells are a newly discovered Th cell subset that produce the pleiotropic cytokine IL-9. Th9 cells can protect against tumors and provide resistance against helminth infections. Given their pivotal role in the adaptive immune system, understanding Th9 cell development and the regulation of IL-9 production could open novel immunotherapeutic opportunities. The Na+/H+exchanger 1 (NHE1; gene name Slc9α1)) is critically important for regulating intracellular pH (pHi), cell volume, migration, and cell survival. The pHiinfluences cytokine secretion, activities of membrane-associated enzymes, ion transport, and other effector signaling molecules such as ATP and Ca2+levels. However, whether NHE1 regulates Th9 cell development or IL-9 secretion has not yet been defined. The present study explored the role of NHE1 in Th9 cell development and function. Th cell subsets were characterized by flow cytometry and pHiwas measured using 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein-acetoxymethyl ester (BCECF-AM) dye. NHE1 functional activity was estimated from the rate of realkalinization following an ammonium pulse. Surprisingly, in Th9 cells pHiand NHE1 activity were significantly higher than in all other Th cell subsets (Th1/Th2/Th17 and induced regulatory T cells (iTregs)). NHE1 transcript levels and protein abundance were significantly higher in Th9 cells than in other Th cell subsets. Inhibition of NHE1 by siRNA-NHE1 or with cariporide in Th9 cells down-regulated IL-9 and ATP production. NHE1 activity, Th9 cell development, and IL-9 production were further blunted by pharmacological inhibition of protein kinase Akt1/Akt2. Our findings reveal that Akt1/Akt2 control of NHE1 could be an important physiological regulator of Th9 cell differentiation, IL-9 secretion, and ATP production.
authors.affiliation: From the Departments of Cardiology, Cardiovascular Medicine and Physiology, Eberhard-Karls-Tübingen University, Tübingen, Gmelinstraße5, D-72076 Tübingen, Germany, ysinghbt@gmail.com.
authors.forename: Yogesh
authors.identifier: http://orcid.org/0000-0001-6919-6273
authors.initials: Y
authors.lastname: Singh
authors.affiliation: From the Departments of Cardiology, Cardiovascular Medicine and Physiology, Eberhard-Karls-Tübingen University, Tübingen, Gmelinstraße5, D-72076 Tübingen, Germany.
authors.forename: Yuetao
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: From the Departments of Cardiology, Cardiovascular Medicine and Physiology, Eberhard-Karls-Tübingen University, Tübingen, Gmelinstraße5, D-72076 Tübingen, Germany.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Shi
authors.affiliation: From the Departments of Cardiology, Cardiovascular Medicine and Physiology, Eberhard-Karls-Tübingen University, Tübingen, Gmelinstraße5, D-72076 Tübingen, Germany.|the Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, China, and.
authors.forename: Shaqiu
authors.initials: S
authors.lastname: Zhang
authors.affiliation: From the Departments of Cardiology, Cardiovascular Medicine and Physiology, Eberhard-Karls-Tübingen University, Tübingen, Gmelinstraße5, D-72076 Tübingen, Germany.
authors.forename: Anja T
authors.initials: AT
authors.lastname: Umbach
authors.affiliation: From the Departments of Cardiology, Cardiovascular Medicine and Physiology, Eberhard-Karls-Tübingen University, Tübingen, Gmelinstraße5, D-72076 Tübingen, Germany.
authors.forename: Madhuri S
authors.initials: MS
authors.lastname: Salker
authors.affiliation: the Institute of Immunology, Medical Faculty, University of Duisburg-Essen, Hufelandstraße 55, 45147 Essen, Germany.
authors.forename: Karl S
authors.initials: KS
authors.lastname: Lang
authors.affiliation: From the Departments of Cardiology, Cardiovascular Medicine and Physiology, Eberhard-Karls-Tübingen University, Tübingen, Gmelinstraße5, D-72076 Tübingen, Germany, florian.lang@uni-tuebingen.de.
authors.forename: Florian
authors.identifier: http://orcid.org/0000-0003-2962-1540
authors.initials: F
authors.lastname: Lang
mesh_terms: D000255:Adenosine Triphosphate / Q000276:immunology; D000818:Animals; D027682:Cation Transport Proteins / Q000235:genetics / Q000276:immunology*; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D006019:Glycolysis; D006863:Hydrogen-Ion Concentration; D016906:Interleukin-9 / Q000235:genetics / Q000276:immunology*; D008810:Mice, Inbred C57BL; D051057:Proto-Oncogene Proteins c-akt / Q000276:immunology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000166:cytology / Q000276:immunology* / Q000378:metabolism
chemical_list: D027682:Cation Transport Proteins; D016906:Interleukin-9; D034741:RNA, Small Interfering; C490997:Slc9a1 protein, mouse; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers; D000255:Adenosine Triphosphate; D051057:Proto-Oncogene Proteins c-akt
keywords: NHE1; T helper cells; Th9 cells; cancer; cellular regulation; iTregs; interleukin; pH regulation