RESUMO
Calcium signaling in phagocytes is essential for cellular activation, migration, and the potential resolution of infection or inflammation. The generation of reactive oxygen species (ROS) via activation of NADPH (nicotinamide adenine dinucleotide phosphate)-oxidase activity in macrophages has been linked to altered intracellular calcium concentrations. Because of its role as an oxidative stress sensor in phagocytes, we investigated the function of the cation channel transient receptor potential melastatin 2 (TRPM2) in macrophages during oxidative stress responses induced by Helicobacter pylori infection. We show that Trpm2-/- mice, when chronically infected with H. pylori, exhibit increased gastric inflammation and decreased bacterial colonization compared with wild-type (WT) mice. The absence of TRPM2 triggers greater macrophage production of inflammatory mediators and promotes classically activated macrophage M1 polarization in response to H. pylori. TRPM2-deficient macrophages upon H. pylori stimulation are unable to control intracellular calcium levels, which results in calcium overloading. Furthermore, increased intracellular calcium in TRPM2-/- macrophages enhanced mitogen-activated protein kinase and NADPH-oxidase activities, compared with WT macrophages. Our data suggest that augmented production of ROS and inflammatory cytokines with TRPM2 deletion regulates oxidative stress in macrophages and consequently decreases H. pylori gastric colonization while increasing inflammation in the gastric mucosa.
Assuntos
Gastrite/genética , Infecções por Helicobacter/imunologia , Helicobacter pylori/imunologia , Macrófagos/imunologia , Canais de Cátion TRPM/metabolismo , Animais , Sinalização do Cálcio , Diferenciação Celular , Células Cultivadas , Citocinas/metabolismo , Gastrite/imunologia , Infecções por Helicobacter/genética , Mediadores da Inflamação/metabolismo , Ativação de Macrófagos/genética , Macrófagos/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , NADP/metabolismo , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Canais de Cátion TRPM/genéticaRESUMO
Experiments were performed in Cave C of GSI (Gesellschaft für Schwerionenforschung) using the LAND (Large Area Neutron Detector) in combination with the deflection magnet ALADIN (A LArge DIpol magNet) in front of the LAND where charged particles and neutrons can be separated. This arrangement is used to create high-energetic neutron fields by irradiation of a thick lead target (5 cm) with deuteron beams with the energies of 500 or 800 MeV per nucleon. In break-up reactions the neutron is separated from the proton which is deflected in the magnetic field of the ALADIN. The produced neutron radiation, which has a pronounced peak at the nucleon energy, is used to measure the fluence response of the GSI neutron ball. A thermoluminescence (TL) based spherical neutron dosemeter was developed for the area monitoring for the quantity H(10) at high-energy accelerators. In the same experiment, the spectral neutron fluence Phi(E) is measured with the LAND in the energy range from 100 MeV to 1 GeV. The measured fluence responses are compared with results of FLUKA calculations and the corresponding fluence-to-dose conversion coefficients. The measured dosemeter responses are too high in comparison to the calculated ones (up to approximately 50%), the dosemeter reading gives dose values which are too high by a factor of 1.1-2.2 related to the corresponding fluence-to-dose conversion factors.
