title: Phosphoinositide 3-kinase β, phosphoinositide 3-kinase δ, and phosphoinositide 3-kinase γ mediate the anti-inflammatory effects of magnesium sulfate.
abstract: BACKGROUND
  We previously demonstrated that inhibiting phosphoinositide 3-kinase (PI3K) or activating L-type calcium channels blocked the anti-inflammatory effects of magnesium sulfate (MgSO₄). However, the question as which class I PI3K isoform (PI3Kα, PI3Kβ, PI3Kδ, or PI3Kγ) is involved in this regard remains unstudied. The question as whether MgSO₄ and L-type calcium channels interact to influence PI3K activation also remains unstudied. We therefore designed this study to test two hypotheses: (1) inhibiting PI3Kα, PI3Kβ, PI3Kδ, or PI3Kγ would block the anti-inflammatory effects of MgSO₄ and (2) activating L-type calcium channels would block the effects of MgSO₄ on activating PI3K.
  
  
  METHODS
  PI3K isoform investigation: macrophages (RAW264.7 cells) were treated with endotoxin, endotoxin plus MgSO₄, or endotoxin plus MgSO₄ plus the selective inhibitor of PI3Kα (PIK-75), PI3Kβ (TGX-221), PI3Kδ (IC-87114), or PI3Kγ (AS-252424). Calcium channel investigation: macrophages were treated with endotoxin, endotoxin plus MgSO₄, or endotoxin plus MgSO₄ plus the L-type calcium channel activator BAY-K8644.
  
  
  RESULTS
  The endotoxin plus MgSO₄ group presented lower concentrations of inflammatory mediators (macrophage inflammatory protein 2, tumor necrosis factor α, and interleukin 6, lower nuclear concentration of phosphorylated nuclear factor κB, lower cytosolic concentration of phosphorylated inhibitor κBα, and higher concentration of phosphorylated Akt (PI3K activation marker) than the endotoxin group (all P < 0.05). These effects of MgSO₄ were significantly reduced by TGX-221, IC-87114, or AS-252424, but not PIK-75. Additionally, BAY-K8644 blocked the effect of MgSO₄ on activating PI3K.
  
  
  CONCLUSIONS
  MgSO₄ exerts its anti-inflammatory effects through activating PI3Kβ, PI3Kδ, and PI3Kγ. The underlying mechanism appears to involve inhibition of L-type calcium channels.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Mackay Memorial Hospital, Taipei, Taiwan; Mackay Medicine, Nursing, and Management College, Taipei, Taiwan.
authors.forename: Ping-Ying
authors.initials: PY
authors.lastname: Lee
authors.affiliation: Department of Anesthesiology, Taipei Tzu Chi Hospital, Taipei, Taiwan; School of Medicine, Tzu Chi University, Hualien, Taiwan.
authors.forename: Chen-Hsien
authors.initials: CH
authors.lastname: Yang
authors.affiliation: Department of Anesthesiology, Taipei Tzu Chi Hospital, Taipei, Taiwan; School of Medicine, Tzu Chi University, Hualien, Taiwan.
authors.forename: Ming-Chang
authors.initials: MC
authors.lastname: Kao
authors.affiliation: Department of Anesthesiology, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Nuan-Yen
authors.initials: NY
authors.lastname: Su
authors.affiliation: Graduate Institute of Nursing, College of Nursing, Taipei Medical University, Taipei, Taiwan.
authors.forename: Pei-Shan
authors.initials: PS
authors.lastname: Tsai
authors.affiliation: Department of Anesthesiology, Taipei Tzu Chi Hospital, Taipei, Taiwan; School of Medicine, Tzu Chi University, Hualien, Taiwan. Electronic address: huangcj1112@gmail.com.
authors.forename: Chun-Jen
authors.initials: CJ
authors.lastname: Huang
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D002478:Cells, Cultured; D018925:Chemokines / Q000378:metabolism; D058534:Class I Phosphatidylinositol 3-Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016207:Cytokines / Q000378:metabolism; D004731:Endotoxins; D008262:Macrophage Activation; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D008278:Magnesium Sulfate / Q000494:pharmacology*; D051379:Mice
chemical_list: D000893:Anti-Inflammatory Agents; D020746:Calcium Channels, L-Type; D018925:Chemokines; D016207:Cytokines; D004731:Endotoxins; D008278:Magnesium Sulfate; D058534:Class I Phosphatidylinositol 3-Kinases
keywords: Chemokine; Cytokine; Endotoxin; Macrophages; MgSO(4); NF-κB