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Contact hypersensitivity (CHS) is an experimental model of allergic contact dermatitis (ACD) that can be studied in mice. This study aims to present an objective laboratory method that may help to study the CHS reaction in mice, which can be measured and quantified by various tests. To induce CHS, on day "0", mice were sensitized on a previously shaved spot by abdominal skin painting with the hapten 2,4,6-trinitrochlorobenzene (TNCB) in an acetone-ethanol mixture, whereas negative control mice were sham sensitized with vehicle alone-acetone-ethanol mixture. On day "4", the baseline ear thickness was measured with a micrometer prior to the elicitation of CHS (challenge) by painting both ears with diluted TNCB both in the test and control groups. After 24 h, the ear swelling was measured with a micrometer. CHS is an example of a T cell-mediated immune response that causes swelling in inflamed tissue, peaking 24 h after the skin challenge with the same hapten. An increase in ear edema correlated with augmented ear weight, myeloperoxidase (MPO) activity, pro-inflammatory cytokine concentration in the ear extracts, increased thickening of the edematous dermis in the histological examination, and ear vascular permeability. There was also an increase in the concentration of TNP-specific IgG1 antibodies in the sera of the test group when compared with the control mice. Additionally, CHS can be successfully transferred with the CHS-effector cells obtained from donors previously sensitized with TNCB. The CHS-effector cells were administered intravenously into naïve recipient mice, which were subsequently challenged with the same diluted hapten. Ear swelling was measured with a micrometer 24 h later.

Tumour tissue is infiltrated by myeloid cells that are reprogrammed into alternatively activated/regenerative (M2) macrophages. The contribution of major signalling pathways and their modulators/targets involved in the macrophage reprogramming is poorly known. Glioblastoma (malignant brain tumour) attracts and reprograms brain-resident microglia and peripheral macrophages into cells that increase invasion, angiogenesis and suppress antitumour immunity. Using a 'function-first' approach and glioma secretome proteomics we identified osteopontin and lactadherin as proteins that cooperatively activate amoeboid transformation, phagocytosis and motility of primary microglia cultures via integrins and FAK-Akt (focal adhesion kinase-Akt) signalling. A synthetic peptide interfering with integrin ligands blocks glioma-microglia communication, functional activation and M2 gene expression. We found that osteopontin/secreted phosphoprotein 1 (Spp1) produced by non-transformed cells acts as a proinflammatory factor inducing inflammatory signalling and M1 genes, and counteracts the action of lactadherin. Using constructs encoding functional mutants of osteopontin, we demonstrated sequential processing of Spp1 by thrombin and matrix metalloproteinase-3 and/or -7 (MMP-3 and/or -7) in glioma cells, which generates a microglia-activating form devoid of the inflammatory activity, while retaining the M2 reprogramming potential. A similar form of osteopontin is secreted by human glioma cells but not normal human astrocytes. Knockdown of osteopontin or lactadherin in glioma cells reduces intracranial glioma growth, blocks amoeboid transformation of myeloid cells and affects M2 reprogramming of microglia/macrophages. Our findings demonstrate how glioma cells misuse macrophage-activating signals and redesign primarily proinflammatory signals towards their advantage to induce M2 reprogramming of tumour-infiltrating brain macrophages.

Molecular development together with advances in information technologies as well electronic medical records provide excellent opportunity to create a new system of disease nomenclature (disease taxonomy). The aim of this chapter is to classify hypersensitivity diseases according to the current understanding of the pathomechanisms. Proposed classification is not based on specific disease or clinical manifestation (visible properties=disease phenotype) because many of these are induced by multiple underlying mechanisms, which can overlap in complex endotypes. We do not pursue into this classification the phenomena of autoimmunity or toxicity, however they can contribute to symptoms of hypersensitivity.

There is strong evidence of the role of house dust mite (HDM) and human rhinovirus (HRV-16) in exacerbations of asthma. Airway epithelium provides protection against inhaled factors through various pattern recognition receptors (PRRs). Some of PRRs were shown to assemble into inflammasomes, leading to secretion of mature IL-1β and IL-18. There are limited data on activation of inflammasome in differentiated human bronchial epithelium in asthma and its exacerbations. First, we performed next generation sequencing of bronchial epithelial cells from asthmatic and healthy donors. There were several inflammasome-related pathways enriched in asthma patients. Next, we performed air-liquid interface cultures of bronchial epithelium with HDM stimulation and HRV-16 infection, analyzed by RT-PCR, WB, ELISA and confocal microscopy. We found significantly increased inflammasome activation in asthmatics, confirmed by the presence of ASC specks, activated caspase-1 and elevated expression of secreted mature IL-1β upon HRV-16 alone and combined HDM and HRV-16 stimulation, blocked by caspase-1 inhibitor. Moreover, ASC expression in the bronchial wall biopsies of asthmatic patients was enhanced in the upper layers of epithelium and was accompanied with the increased IL-1β levels in BAL. Moreover, we found that in acute and chronic high dose-HDM-induced model of airway inflammation in mice ASC, caspase-1 and IL-1β mRNA is significantly increased in the lungs. Our findings highlight the role of bronchial epithelium as essential inflammatory reservoir upon HRV infection combined with HDM exposure. Induction of rapid IL-1β secretion might have an impact on asthma exacerbations.

International audience; Potassium (K+) is an important nutrient for plants. It serves as a cofactor of various enzymes and as the major inorganic solute maintaining plant cell turgor. In a recent study, an as yet unknown role of K+ in plant homeostasis was shown. It was demonstrated that K+ gradients in vascular tissues can serve as an energy source for phloem (re)loading processes and that the voltage-gated K+ channels of the AKT2-type play a unique role in this process. The AKT2 channel can be converted by phosphorylation of specific serine residues (S210 and S329) into a non-rectifying channel that allows a rapid efflux of K+ from the sieve element/companion cells (SE/CC) complex. The energy of this flux is used by other transporters for phloem (re)loading processes. Nonetheless, the results do indicate that post-translational modifications at S210 and S329 alone cannot explain AKT2 regulation. Here, we discuss the existence of multiple post-translational modification steps that work in concert to convert AKT2 from an inward-rectifying into a non-rectifying K+ channel.

Malignant gliomas attract resident microglia and macrophages and re-program these cells into pro-invasive, immunosuppressive cells. It results in formation of tumor supportive microenvironment and evasion of antitumor responses. The analysis of marker genes in microglia and macrophages infiltrating experimental gliomas indicates different kinetics and functions of various myeloid subpopulations during glioma progression. Signals responsible for recruitment and polarization of tumor infiltrating myeloid cells are poorly known. Proteomic analysis of glioma secretome revealed a presence of osteopontin (SPP1) and lactadherin (MGF-E8) in microglia-activating fractions. Both proteins stimulated microglia via αvβ3 integrin signaling that results in activation of PI-3K/Akt and FAK, enhancement of microglial migration, phagocytosis and transcriptional responses. Inhibition of ligand-integrin interactions with short interfering peptides abolished pro-invasive polarization in glioma-microglia co-cultures. We found that SPP1, highly overexpressed in glioma cells, was specifically processed by sequential thrombin and metalloproteinase-dependent cleavage. This type of processing results in losing SPP1 pro-inflammatory activity leaving intact its pro-tumorigenic activity and does not occur in non-transformed cells. Knockdown of SPP1 in glioma cells strongly reduced growth of intracranial gliomas. The number of infiltrating microglia/macrophages (Iba1+) was not affected, but amoeboid transformation, expression of the alternative phenotype markers and angiogenesis were reduced in SPP1-depleted gliomas. Interestingly, infiltrating Iba1+ cells did not undergo pro-invasive polarization. Moreover, SPP1-depleted tumors were infiltrated with T cytotoxic lymphocytes, while accumulation of T regulatory cells was significantly reduced. The expression of SPP1 is up-regulated in human glioblastoma and inversely correlated with patient's survival. Our findings demonstrate that glioma-derived and specifically processed osteopontin/SPP1 polarizes glioma-infiltrating microglia and contributes to transformation of tumor microenvironment. This defines osteopontin/SPP1 a new biomarker and target for glioma therapy, and shows that targeting glioma-microglia interactions within tumor microenvironment is a promising strategy to fight these tumors. Studies were supported by a grant 2012/04/A/NZ3/00630 from the National Science Center.

International audience; Potassium (K(+)) channel function is fundamental to many physiological processes. However, components and mechanisms regulating the activity of plant K(+) channels remain poorly understood. Here, we show that the calcium (Ca(2+)) sensor CBL4 together with the interacting protein kinase CIPK6 modulates the activity and plasma membrane (PM) targeting of the K(+) channel AKT2 from Arabidopsis thaliana by mediating translocation of AKT2 to the PM in plant cells and enhancing AKT2 activity in oocytes. Accordingly, akt2, cbl4 and cipk6 mutants share similar developmental and delayed flowering phenotypes. Moreover, the isolated regulatory C-terminal domain of CIPK6 is sufficient for mediating CBL4- and Ca(2+)-dependent channel translocation from the endoplasmic reticulum membrane to the PM by a novel targeting pathway that is dependent on dual lipid modifications of CBL4 by myristoylation and palmitoylation. Thus, we describe a critical mechanism of ion-channel regulation where a Ca(2+) sensor modulates K(+) channel activity by promoting a kinase interaction-dependent but phosphorylation-independent translocation of the channel to the PM.

The essential mineral nutrient potassium (K + ) is the most important inorganic cation for plants and is recognized as a limiting factor for crop yield and quality. Nonetheless, it is only partially understood how K + contributes to plant productivity. K + is used as a major active solute to maintain turgor and to drive irreversible and reversible changes in cell volume. K + also plays an important role in numerous metabolic processes, for example, by serving as an essential cofactor of enzymes. Here, we provide evidence for an additional, previously unrecognized role of K + in plant growth. By combining diverse experimental approaches with computational cell simulation, we show that K + circulating in the phloem serves as a decentralized energy storage that can be used to overcome local energy limitations. Posttranslational modification of the phloem-expressed Arabidopsis K + channel AKT2 taps this “potassium battery,” which then efficiently assists the plasma membrane H + -ATPase in energizing the transmembrane phloem (re)loading processes.

Reactive oxygen species (ROS) are essential for development and stress signalling in plants. They contribute to plant defense against pathogens, regulate stomatal transpiration and influence nutrient uptake and partitioning. Although both Ca2+ and K+ channels of plants are known to be affected, virtually nothing is known of the targets for ROS at a molecular level. Here we report that a single cysteine (Cys) residue within the Kv-like SKOR K+ channel of Arabidopsis thaliana is essential for channel sensitivity to the ROS H2O2. We show that H2O2 rapidly enhanced current amplitude and activation kinetics of heterologouslyexpressed SKOR, and the effects were reversed by the reducing agent dithiothreitol (DTT). Both H2O2 and DTT were active at the outer face of the membrane and current enhancement was strongly dependent on membrane depolarization, consistent with a H2O2-sensitive site on the SKOR protein which is exposed to the outside when the channel is in the open conformation. Cys substitutions identified a single residue, C168 located within the S3 α-helix of the voltage sensor complex, to be essential for sensitivity to H2O2. The same Cys residue was a primary determinant for current block by covalent Cys S-methioylation with aqueous methanethiosulfonates. These, and additional data identify C168 as a critical target for H2O2, and implicate ROSmediated control of the K+ channel in regulating mineral nutrient partitioning within the plant. Fil: Garcia-Mata, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina Fil: Wan, Jianwen. Soochow University; China Fil: Gajdanowicz, Pawel. Universität Potsdam; Alemania Fil: Gonzalez, Wendy. Universidad de Talca; Chile Fil: Hills, Adrian. Fil: Donald, Naomi. Fil: Riedelsberger, Janin. Fil: Amtmann, Anna. Universität Potsdam; Alemania Fil: Dreyer, Ingo. Universität Potsdam; Alemania Fil: Blatt, Michael R..

The family of voltage-gated (Shaker-like) potassium channels in plants includes both inward-rectifying (Kin) channels that allow plant cells to accumulate K+ and outward-rectifying (Kout) channels that mediate K+ efflux. Despite their close structural similarities, Kin and Kout channels differ in their gating sensitivity towards voltage and the extracellular K+ concentration. We have carried out a systematic program of domain swapping between the Kout channel SKOR and the Kin channel KAT1 to examine the impacts on gating of the pore regions, the S4, S5, and the S6 helices. We found that, in particular, the N-terminal part of the S5 played a critical role in KAT1 and SKOR gating. Our findings were supported by molecular dynamics of KAT1 and SKOR homology models. In silico analysis revealed that during channel opening and closing, displacement of certain residues, especially in the S5 and S6 segments, is more pronounced in KAT1 than in SKOR. From our analysis of the S4–S6 region, we conclude that gating (and K+-sensing in SKOR) depend on a number of structural elements that are dispersed over this ∼145-residue sequence and that these place additional constraints on configurational rearrangement of the channels during gating. Fil: Riedelsberger, Janin . Universität Potsdam; Alemania. Max-Planck Institute of Molecular Plant Physiology; Alemania Fil: Sharma, Tripti . Universität Potsdam; Alemania. Max-Planck Institute of Molecular Plant Physiology; Alemania Fil: Gonzalez, Wendy . Universidad de Talca; Chile Fil: Gajdanowicz, Pawel . Universität Potsdam; Alemania Fil: Morales Navarro, Samuel Elías . Universidad de Talca; Chile Fil: Garcia-Mata, Carlos. University Of Glasgow; Reino Unido. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Mueller Roeber, Bernd. Max-Planck Institute of Molecular Plant Physiology; Alemania. Universität Potsdam; Alemania Fil: González Nilo, Fernando Danilo . Universidad de Talca; Chile Fil: Blatt, Michael R. . University Of Glasgow; Reino Unido Fil: Dreyer, Ingo . Universität Potsdam; Alemania

• The family of voltage-gated potassium channels in plants presumably evolved from a common ancestor and includes both inward-rectifying (Kin) channels that allow plant cells to accumulate K+ and outward-rectifying (Kout) channels that mediate K+ efflux. Despite their close structural similarities, the activity of Kin channels is largely independent of K+ and depends only on the transmembrane voltage, whereas that of Kout channels responds to the membrane voltage and the prevailing extracellular K+ concentration. Gating of potassium channels is achieved by structural rearrangements within the last transmembrane domain (S6). • Here we investigated the functional equivalence of the S6 helices of the Kin channel KAT1 and the Kout channel SKOR by domain-swapping and site-directed mutagenesis. Channel mutants and chimeras were analyzed after expression in Xenopus oocytes. • We identified two discrete regions that influence gating differently in both channels, demonstrating a lack of functional complementarity between KAT1 and SKOR. Our findings are supported by molecular models of KAT1 and SKOR in the open and closed states. • The role of the S6 segment in gating evolved differently during specialization of the two channel subclasses, posing an obstacle for the transfer of the K+-sensor from Kout to Kin channels. Fil: Gajdanowicz, Pawel. Universität Potsdam; Alemania Fil: Garcia-Mata, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas. Laboratorio de Fisiología Molecular e Integrativa; Argentina. University of Glasgow; Reino Unido Fil: Gonzalez, Wendy. Universidad de Talca; Chile. Universität Potsdam; Alemania Fil: Morales Navarro, Samuel Elías. Universidad de Talca; Chile Fil: Sharma, Tripti. Max Planck Institute of Molecular Plant Physiology; Alemania. Universität Potsdam; Alemania Fil: Gonzalez Nilo, Fernando Danilo. Universidad de Talca; Chile Fil: Gutowicz, Jan. University of Wroclaw; Polonia Fil: Mueller Roeber, Bernd. Max Planck Institute of Molecular Plant Physiology; Alemania. Universität Potsdam; Alemania Fil: Blatt, Michael R.. University of Glasgow; Reino Unido Fil: Dreyer, Ingo. Universität Potsdam; Alemania

Plant outward-rectifying K+ channels mediate K+ efflux from guard cells during stomatal closure and from root cells into the xylem for root-shoot allocation of potassium (K). Intriguingly, the gating of these channels depends on the extracellular K+ concentration, although the ions carrying the current are derived from inside the cell. This K+ dependence confers a sensitivity to the extracellular K+ concentration ([K+]) that ensures that the channels mediate K+ efflux only, regardless of the [K+] prevailing outside. We investigated the mechanism of K+-dependent gating of the K+ channel SKOR of Arabidopsis by site-directed mutagenesis. Mutations affecting the intrinsic K+ dependence of gating were found to cluster in the pore and within the sixth transmembrane helix (S6), identifying an 'S6 gating domain' deep within the membrane. Mapping the SKOR sequence to the crystal structure of the voltage-dependent K+ channel KvAP from Aeropyrum pernix suggested interaction between the S6 gating domain and the base of the pore helix, a prediction supported by mutations at this site. These results offer a unique insight into the molecular basis for a physiologically important K+-sensory process in plants.