title: Cytosolic and Calcium-Independent Phospholipases A2 Activation and Prostaglandins E2 Are Associated with Escherichia coli-Induced Reduction of Insulin Secretion in INS-1E Cells.
abstract: It is suspected that microbial infections take part in the pathogenesis of diabetes mellitus type 1 (T1DM). Glucose-induced insulin secretion is accompanied by the release of free arachidonic acid (AA) mainly by cytosolic- and calcium independent phospholipases A2 (cPLA2 and iPLA2). Insulinoma cell line (INS-1E) was infected with E. coli isolated from the blood culture of a patient with sepsis. Invasion assay, Scanning Electron Microscopy and Transmission Electron Microscopy demonstrated the capacity of E. coli to enter cells, which was reduced by PLA2 inhibitors. Glucose-induced insulin secretion was significantly increased after acute infection (8h) but significantly decreased after chronic infection (72h). PLA2 activities, cPLA2, iPLA2, phospho-cPLA2, and COX-2 expressions were increased after acute and, even more, after chronic E. coli infection. The silencing of the two isoforms of PLA2s, with specific cPLA2- or iPLA2-siRNAs, reduced insulin secretion after acute infection and determined a rise in insulin release after chronic infection. Prostaglandins E2 (PGE2) production was significantly elevated in INS-1E after long-term E. coli infection and the restored insulin secretion in presence of L798106, a specific EP3 antagonist, and NS-398, a COX-2 inhibitor, and the reduction of insulin secretion in presence of sulprostone, a specific EP3 agonist, revealed their involvement in the effects triggered by bacterial infection. The results obtained demonstrated that cPLA2 and iPLA2 play a key role in insulin secretion process after E. coli infection. The high concentration of AA released is transformed into PGE2, which could be responsible for the reduced insulin secretion.
authors.affiliation: Dept. of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.
authors.forename: Nunzia
authors.initials: N
authors.lastname: Caporarello
authors.affiliation: Dept. of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Salmeri
authors.affiliation: Dept. of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Scalia
authors.affiliation: Dept. of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Motta
authors.affiliation: Dept. of Clinical and Experimental Medicine, School of Medicine, University of Catania, Catania, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Parrino
authors.affiliation: Dept. of Clinical and Experimental Medicine, School of Medicine, University of Catania, Catania, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Frittitta
authors.affiliation: Dept. of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.
authors.forename: Melania
authors.initials: M
authors.lastname: Olivieri
authors.affiliation: Dept. of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.
authors.forename: Martina
authors.initials: M
authors.lastname: Cristaldi
authors.affiliation: Dept. of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Avola
authors.affiliation: Dept. of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Bramanti
authors.affiliation: Dept. of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: Toscano
authors.affiliation: Dept. of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.
authors.forename: Carmelina Daniela
authors.initials: CD
authors.lastname: Anfuso
authors.affiliation: Dept. of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Lupo
mesh_terms: D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism*; D015232:Dinoprostone / Q000378:metabolism*; D004789:Enzyme Activation; D004926:Escherichia coli / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D054467:Phospholipases A2 / Q000378:metabolism*
chemical_list: D007328:Insulin; D054467:Phospholipases A2; D015232:Dinoprostone; D002118:Calcium