title: Macrophage alteration induced by inflammatory toxins isolated from Tityus discrepans scorpion venom. The role of Na(+)/Ca(2+) exchangers.
abstract: We study the effect of all Tityus discrepans venom components on macrophage alterations. Only seven toxins called "Inflammatory Toxin" (InfTx1-7) induced cell changes. Incubation with InfTx1 through InfTx5 rose macrophage NO level at 2 h toxin exposure. Cells rose NO release by 4 h exposure with InfTx2 and InfTx5, the NO levels reached concentrations similar or higher than the induced by lipopolysaccharides (LPS) incubation. InfTx2, -6 and -7 increased cell TNF-α release. InfTx2 as LPS roses cell TNF-α secretion gradually in time. Macrophages were loaded with fluorescent dyes, exposed to all toxins and observed with a 3D wide field deconvolution setup. Cells exposed to whole venom or InfTx4 through InfTx7 developed pseudopodia, cytoplasm prolongations, blebs, and loss their rounded form. The molecular masses and N-terminal sequences of InfTx4 through InfTx7 were analyzed by MALDI-TOF mass spectrometry and Edman degradation. InfTx4-7 induced a remarkable increase of intracellular Ca(2+) levels ([Ca(2+)]i), measured as a rise of normalized cell green fluorescence intensity (FI) ×2.7, ×2.6, ×95 and ×2.9 the controls, respectively. InfTx6-7 action mechanisms were studied under different conditions. Results suggested that InfTx6 interact with a membrane sodium channel inducing cell depolarization with a consequent increase on intracellular [Na(+)], this would activate Na(+)/Ca(2+) exchanger 3 (NCX) in the reverse mode and the phospholipase C inositol 1,4,5-trisphosphate (PLC-IP3) signaling pathway inducing [Ca(2+)]i overload. Inftx7 should activate the NCX in reverse mode and/or should activate the Na(+)/H(+) exchanger, increasing intracellular [Na(+)] which indirectly induce the activation of NCX3rv and the PLC-IP3 signaling pathway. All these mechanisms would cooperate with the [Ca(2+)]i overload. A rise of [Ca(2+)]i activates the synthesis and secretion of inflammatory molecules like TNF-α, which in turn, increases the gene transcription for inducible nitric oxide synthase, resulting on NO production.
authors.affiliation: Laboratory of Cellular Neuropharmacology, Biophysics and Biochemistry Center, Instituto Venezolano de Investigaciones Científicas (IVIC), Apdo 20632, Caracas 1020-A, Venezuela.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Ramírez-Bello
authors.affiliation: Laboratory of Cellular Neuropharmacology, Biophysics and Biochemistry Center, Instituto Venezolano de Investigaciones Científicas (IVIC), Apdo 20632, Caracas 1020-A, Venezuela.
authors.forename: Carlos
authors.initials: C
authors.lastname: Sevcik
authors.affiliation: Laboratory of Toxicology and Pharmacology, University of Leuven (KU Leuven), Campus Gasthuisberg O&N2, Herestraat 49, P.O. Box 922, B-3000 Leuven, Belgium.
authors.forename: Steve
authors.initials: S
authors.lastname: Peigneur
authors.affiliation: Laboratory of Toxicology and Pharmacology, University of Leuven (KU Leuven), Campus Gasthuisberg O&N2, Herestraat 49, P.O. Box 922, B-3000 Leuven, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Tytgat
authors.affiliation: Laboratory of Cellular Neuropharmacology, Biophysics and Biochemistry Center, Instituto Venezolano de Investigaciones Científicas (IVIC), Apdo 20632, Caracas 1020-A, Venezuela. Electronic address: gina.dsuze@gmail.com.
authors.forename: Gina
authors.initials: G
authors.lastname: D'Suze
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009569:Nitric Oxide / Q000378:metabolism; D012604:Scorpion Venoms / Q000737:chemistry / Q000633:toxicity*; D019831:Sodium-Calcium Exchanger / Q000378:metabolism*; D014118:Toxins, Biological / Q000737:chemistry / Q000633:toxicity*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D012604:Scorpion Venoms; D019831:Sodium-Calcium Exchanger; D014118:Toxins, Biological; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D002118:Calcium
keywords: Inflammatory toxins; Macrophage alteration; Na(+)/Ca(2+) membrane exchanger; Scorpion venom; Tityus discrepans