Background and aims Gap junction-coupled cells form networks in different organs in the body. The... more Background and aims Gap junction-coupled cells form networks in different organs in the body. These networks can be affected by inflammatory stimuli and become dysregulated. Cell signaling is also changed through connexin-linked gap junctions. This alteration affects the surrounding cells and extracellular matrix in organs. These changes can cause the spread of inflammatory substances, thus affecting other network-linked cells in other organs in the body, which can give rise to systemic inflammation, which in turn can lead to pain that can turn into chronic. Methods This is a review based on literature search and our own research data of inflammatory stimuli that can affect different organs and particularly gap-junction-coupled cells throughout the body. Conclusions A remaining question is which cell type or tissue is first affected by inflammatory stimuli. Can endotoxin exposure through the air, water and body start the process and are mast cells the first target cells that have th...
Chondrocytes are effectively involved in the pathophysiological processes of inflammation in join... more Chondrocytes are effectively involved in the pathophysiological processes of inflammation in joints. They form cellular processes in the superficial layer of the articular cartilage and form gap junction coupled syncytium to facilitate cell-to-cell communication. However, very little is known about their physiological cellular identity and communication. The aim with the present work is to evaluate the physiological behavior after stimulation with the inflammatory inducers interleukin-1β and lipopolysaccharide. The cytoskeleton integrity and intracellular Ca release were assessed as indicators of inflammatory state. Cytoskeleton integrity was analyzed through cartilage oligomeric matrix protein and actin labeling with an Alexa 488-conjugated phalloidin probe. Ca responses were assessed through the Ca sensitive fluorophore Fura-2/AM. Western blot analyses of several inflammatory markers were performed. The results show reorganization of the actin filaments. Glutamate, 5-hydoxytryptam...
Objective Chondrocytes are responsible for remodeling and maintaining the structural and function... more Objective Chondrocytes are responsible for remodeling and maintaining the structural and functional integrity of the cartilage extracellular matrix. Because of the absence of a vascular supply, chondrocytes survive in a relatively hypoxic environment and thus have limited regenerative capacity during conditions of cellular stress associated with inflammation and matrix degradation, such as osteoarthritis (OA). Glucose is essential to sustain chondrocyte metabolism and is a precursor for key matrix components. In this study, we investigated the importance of glucose as a fuel source for matrix repair during inflammation as well as the effect of glucose on inflammatory mediators associated with osteoarthritis. Design To create an OA model, we used equine chondrocytes from 4 individual horses that were differentiated into cartilage pellets in vitro followed by interleukin-1β (IL-1β) stimulation for 72 hours. The cells were kept at either normoglycemic conditions (5 mM glucose) or supra...
Cardiac fibroblasts, which are abundant in heart tissue, are involved not only in extracellular m... more Cardiac fibroblasts, which are abundant in heart tissue, are involved not only in extracellular matrix homeostasis and repair, but also in cardiac remodeling after a myocardial infarction that, in turn, can lead to loss of cardiac function and heart failure. Casignaling is functionally important in many cell types, but the roles of fibroblast signaling and inflammation in the pathogenesis of heart disease are unclear. Here, we tested the hypothesis that inflammatory activation affects cardiac fibroblasts, both in terms of Casignaling and their capacity for intercellular communication through the gap junction channel protein connexin 43 (Cx43). We examined Caresponses induced by known modulators of cardiac function such as glutamate, ATP and 5-hydroxytryptamine (5-HT) in human cardiac fibroblasts, under normal and inflammatory conditions. We showed that activation of human cardiac fibroblasts by lipopolysaccharide (LPS) for 24 h altered Casignaling, increased TLR4 and decreased Cx43 ...
Aims In inflammation-reactive astrocytes the cell parameters, Ca2+ signalling, Na+ transporters, ... more Aims In inflammation-reactive astrocytes the cell parameters, Ca2+ signalling, Na+ transporters, cytoskeleton, and release of proinflammatory cytokines are affected. We want to re-establish these parameters with agents, which might have a potential to restore the cells back to a normal non-inflammatory level. Methods Astrocytes in primary cultures were incubated with lipopolysaccharide (LPS) (10 ng/ml) for 24 h to become inflammation-reactive. Different parameters were analysed to verify this inflammation: Ca2+ signalling, Na+/K+-ATPase expression, actin filament organization, and interleukin-1beta release (IL-1β). Results We have used an opioid agonist, endomorphin-1, that stimulates the Gi/o protein of the μ-opioid receptor, an opioid antagonist, naloxone, that inhibits the Gs protein of the μ-opioid receptor in ultralow concentrations, and an anti-epileptic agent, levetiracetam, that counteracts the release of IL-1β. The combination of these three agents managed to activate the G...
The competitive taurine uptake inhibitor 2-guanidinoethane sulfonate (GES) is frequently used to ... more The competitive taurine uptake inhibitor 2-guanidinoethane sulfonate (GES) is frequently used to deplete cerebral pools of taurine. Previous work has revealed that extracellular glutamate increases during GES administration. In view of this, accumulation of glutamate in the absence or presence of 10 or 100 microM GES was measured in primary astroglial cultures from the rat cerebral cortex. At 100 microM, GES reduced Km as well as Vmax for glutamate uptake. A similar tendency was seen at 10 microM GES, but this was not statistically significant. The data suggest that GES is an uncompetitive inhibitor of reuptake of glutamate in astrocytes, which may underlie the previously noted GES-induced elevation of extracellular glutamate in vivo.
The exogenous release of glutamate has been successfully studied in the cochlear nucleus of guine... more The exogenous release of glutamate has been successfully studied in the cochlear nucleus of guinea-pigs after physiological sound stimulation of the ear (frequency 2000--20,000 Hz at 100 dBA).
Primary neuronal enriched cultures were incubated with mu (morphine, 10(-5) M), delta (DPDPE, 10(... more Primary neuronal enriched cultures were incubated with mu (morphine, 10(-5) M), delta (DPDPE, 10(-6) M) and kappa (U-50,488H, 10(-5) M) receptor agonists for 5 days, respectively. Thereafter the acute inhibitory actions of mu, delta or kappa receptor agonists on forskolin stimulated cAMP accumulation was assayed. The effect of long term opioid treatment on the steady-state level of G-protein mRNA (G alpha s, G alpha i-1 and G alpha i-2) was analyzed using an RNAase protection hybridization assay. Incubation for 5 days with kappa receptor agonist resulted in an attenuated ability to decrease the accumulation of cAMP by kappa receptors, as well as mu and delta receptors, which was also observed after 5 days of incubation with the delta receptor agonist. Furthermore, the adenylate cyclase responsiveness to forskolin stimulation was markedly reduced in cultures treated with either delta or kappa receptor agonists. Five days of incubation with kappa receptor agonist resulted in an increase in the levels of G alpha s and G alpha i-2 mRNAs. No effects on the amounts of G alpha s mRNA, G alpha i-1 mRNA or G alpha i-2 mRNA were detected after 5 days of delta receptor stimulation. On the other hand, 5 days of mu receptor stimulation decreased the amounts of G alpha s, G alpha i-1 and G alpha i-2 mRNA. Incubation with kappa receptor agonist for 24 h resulted in a significant decrease in the forskolin-stimulated accumulation of cAMP. The stimulatory effect of forskolin was further decreased after 3 days incubation with kappa receptor agonist.(ABSTRACT TRUNCATED AT 250 WORDS)
Astrocytes are coupled via gap junctions, predominantly formed by connexin-43 proteins, into cell... more Astrocytes are coupled via gap junctions, predominantly formed by connexin-43 proteins, into cellular networks. This coupling is important for the propagation of intercellular calcium waves and for the spatial buffering of K+. Using the scrape-loading/dye transfer technique, we studied gap junction permeability in rat astrocytes cultured from four different brain regions. The cultures were shown to display regional heterogeneity with the following ranking of the gap junction coupling strengths: hippocampus = hypothalamus > cerebral cortex = brain stem. Similar relative patterns were found in connexin-43 messenger RNA and protein levels using solution hybridization/RNase protection assay and western blots, respectively. The percentages of the propagation area of mechanically induced intercellular calcium waves for cortical, brain stem and hypothalamic astrocytes compared with hippocampal astrocytes were approximately 77, 42, and 52, respectively. Thus, the extent of calcium wave propagation was due to more than just gap junctional permeability as highly coupled hypothalamic astrocytes displayed relatively small calcium wave propagation areas. Incubation with 5-hydroxytryptamine decreased and incubation with glutamate increased the calcium wave propagation area in hippocampal (67% and 170% of the control, respectively) and in cortical astrocytes (82% and 163% of the control, respectively). Contrary to hippocampal and cortical astrocytes, the calcium wave propagation in brain stem astrocytes was increased by 5-hydroxytryptamine incubation (158% of control), while in hypothalamic astrocytes, no significant effects were seen. Similar effects from 5-hydroxytryptamine or glutamate treatments were observed on dye transfer, indicating an effect on the junctional coupling strength. These results demonstrate a strong relationship between connexin-43 messenger RNA levels, protein expression, and gap junction permeability among astroglial cells. Furthermore, our results suggest heterogeneity among astroglial cells from different brain regions in intercellular calcium signaling and in its differential modulation by neurotransmitters, probably reflecting functional requirements in various brain regions.
Background and aims Gap junction-coupled cells form networks in different organs in the body. The... more Background and aims Gap junction-coupled cells form networks in different organs in the body. These networks can be affected by inflammatory stimuli and become dysregulated. Cell signaling is also changed through connexin-linked gap junctions. This alteration affects the surrounding cells and extracellular matrix in organs. These changes can cause the spread of inflammatory substances, thus affecting other network-linked cells in other organs in the body, which can give rise to systemic inflammation, which in turn can lead to pain that can turn into chronic. Methods This is a review based on literature search and our own research data of inflammatory stimuli that can affect different organs and particularly gap-junction-coupled cells throughout the body. Conclusions A remaining question is which cell type or tissue is first affected by inflammatory stimuli. Can endotoxin exposure through the air, water and body start the process and are mast cells the first target cells that have th...
Chondrocytes are effectively involved in the pathophysiological processes of inflammation in join... more Chondrocytes are effectively involved in the pathophysiological processes of inflammation in joints. They form cellular processes in the superficial layer of the articular cartilage and form gap junction coupled syncytium to facilitate cell-to-cell communication. However, very little is known about their physiological cellular identity and communication. The aim with the present work is to evaluate the physiological behavior after stimulation with the inflammatory inducers interleukin-1β and lipopolysaccharide. The cytoskeleton integrity and intracellular Ca release were assessed as indicators of inflammatory state. Cytoskeleton integrity was analyzed through cartilage oligomeric matrix protein and actin labeling with an Alexa 488-conjugated phalloidin probe. Ca responses were assessed through the Ca sensitive fluorophore Fura-2/AM. Western blot analyses of several inflammatory markers were performed. The results show reorganization of the actin filaments. Glutamate, 5-hydoxytryptam...
Objective Chondrocytes are responsible for remodeling and maintaining the structural and function... more Objective Chondrocytes are responsible for remodeling and maintaining the structural and functional integrity of the cartilage extracellular matrix. Because of the absence of a vascular supply, chondrocytes survive in a relatively hypoxic environment and thus have limited regenerative capacity during conditions of cellular stress associated with inflammation and matrix degradation, such as osteoarthritis (OA). Glucose is essential to sustain chondrocyte metabolism and is a precursor for key matrix components. In this study, we investigated the importance of glucose as a fuel source for matrix repair during inflammation as well as the effect of glucose on inflammatory mediators associated with osteoarthritis. Design To create an OA model, we used equine chondrocytes from 4 individual horses that were differentiated into cartilage pellets in vitro followed by interleukin-1β (IL-1β) stimulation for 72 hours. The cells were kept at either normoglycemic conditions (5 mM glucose) or supra...
Cardiac fibroblasts, which are abundant in heart tissue, are involved not only in extracellular m... more Cardiac fibroblasts, which are abundant in heart tissue, are involved not only in extracellular matrix homeostasis and repair, but also in cardiac remodeling after a myocardial infarction that, in turn, can lead to loss of cardiac function and heart failure. Casignaling is functionally important in many cell types, but the roles of fibroblast signaling and inflammation in the pathogenesis of heart disease are unclear. Here, we tested the hypothesis that inflammatory activation affects cardiac fibroblasts, both in terms of Casignaling and their capacity for intercellular communication through the gap junction channel protein connexin 43 (Cx43). We examined Caresponses induced by known modulators of cardiac function such as glutamate, ATP and 5-hydroxytryptamine (5-HT) in human cardiac fibroblasts, under normal and inflammatory conditions. We showed that activation of human cardiac fibroblasts by lipopolysaccharide (LPS) for 24 h altered Casignaling, increased TLR4 and decreased Cx43 ...
Aims In inflammation-reactive astrocytes the cell parameters, Ca2+ signalling, Na+ transporters, ... more Aims In inflammation-reactive astrocytes the cell parameters, Ca2+ signalling, Na+ transporters, cytoskeleton, and release of proinflammatory cytokines are affected. We want to re-establish these parameters with agents, which might have a potential to restore the cells back to a normal non-inflammatory level. Methods Astrocytes in primary cultures were incubated with lipopolysaccharide (LPS) (10 ng/ml) for 24 h to become inflammation-reactive. Different parameters were analysed to verify this inflammation: Ca2+ signalling, Na+/K+-ATPase expression, actin filament organization, and interleukin-1beta release (IL-1β). Results We have used an opioid agonist, endomorphin-1, that stimulates the Gi/o protein of the μ-opioid receptor, an opioid antagonist, naloxone, that inhibits the Gs protein of the μ-opioid receptor in ultralow concentrations, and an anti-epileptic agent, levetiracetam, that counteracts the release of IL-1β. The combination of these three agents managed to activate the G...
The competitive taurine uptake inhibitor 2-guanidinoethane sulfonate (GES) is frequently used to ... more The competitive taurine uptake inhibitor 2-guanidinoethane sulfonate (GES) is frequently used to deplete cerebral pools of taurine. Previous work has revealed that extracellular glutamate increases during GES administration. In view of this, accumulation of glutamate in the absence or presence of 10 or 100 microM GES was measured in primary astroglial cultures from the rat cerebral cortex. At 100 microM, GES reduced Km as well as Vmax for glutamate uptake. A similar tendency was seen at 10 microM GES, but this was not statistically significant. The data suggest that GES is an uncompetitive inhibitor of reuptake of glutamate in astrocytes, which may underlie the previously noted GES-induced elevation of extracellular glutamate in vivo.
The exogenous release of glutamate has been successfully studied in the cochlear nucleus of guine... more The exogenous release of glutamate has been successfully studied in the cochlear nucleus of guinea-pigs after physiological sound stimulation of the ear (frequency 2000--20,000 Hz at 100 dBA).
Primary neuronal enriched cultures were incubated with mu (morphine, 10(-5) M), delta (DPDPE, 10(... more Primary neuronal enriched cultures were incubated with mu (morphine, 10(-5) M), delta (DPDPE, 10(-6) M) and kappa (U-50,488H, 10(-5) M) receptor agonists for 5 days, respectively. Thereafter the acute inhibitory actions of mu, delta or kappa receptor agonists on forskolin stimulated cAMP accumulation was assayed. The effect of long term opioid treatment on the steady-state level of G-protein mRNA (G alpha s, G alpha i-1 and G alpha i-2) was analyzed using an RNAase protection hybridization assay. Incubation for 5 days with kappa receptor agonist resulted in an attenuated ability to decrease the accumulation of cAMP by kappa receptors, as well as mu and delta receptors, which was also observed after 5 days of incubation with the delta receptor agonist. Furthermore, the adenylate cyclase responsiveness to forskolin stimulation was markedly reduced in cultures treated with either delta or kappa receptor agonists. Five days of incubation with kappa receptor agonist resulted in an increase in the levels of G alpha s and G alpha i-2 mRNAs. No effects on the amounts of G alpha s mRNA, G alpha i-1 mRNA or G alpha i-2 mRNA were detected after 5 days of delta receptor stimulation. On the other hand, 5 days of mu receptor stimulation decreased the amounts of G alpha s, G alpha i-1 and G alpha i-2 mRNA. Incubation with kappa receptor agonist for 24 h resulted in a significant decrease in the forskolin-stimulated accumulation of cAMP. The stimulatory effect of forskolin was further decreased after 3 days incubation with kappa receptor agonist.(ABSTRACT TRUNCATED AT 250 WORDS)
Astrocytes are coupled via gap junctions, predominantly formed by connexin-43 proteins, into cell... more Astrocytes are coupled via gap junctions, predominantly formed by connexin-43 proteins, into cellular networks. This coupling is important for the propagation of intercellular calcium waves and for the spatial buffering of K+. Using the scrape-loading/dye transfer technique, we studied gap junction permeability in rat astrocytes cultured from four different brain regions. The cultures were shown to display regional heterogeneity with the following ranking of the gap junction coupling strengths: hippocampus = hypothalamus > cerebral cortex = brain stem. Similar relative patterns were found in connexin-43 messenger RNA and protein levels using solution hybridization/RNase protection assay and western blots, respectively. The percentages of the propagation area of mechanically induced intercellular calcium waves for cortical, brain stem and hypothalamic astrocytes compared with hippocampal astrocytes were approximately 77, 42, and 52, respectively. Thus, the extent of calcium wave propagation was due to more than just gap junctional permeability as highly coupled hypothalamic astrocytes displayed relatively small calcium wave propagation areas. Incubation with 5-hydroxytryptamine decreased and incubation with glutamate increased the calcium wave propagation area in hippocampal (67% and 170% of the control, respectively) and in cortical astrocytes (82% and 163% of the control, respectively). Contrary to hippocampal and cortical astrocytes, the calcium wave propagation in brain stem astrocytes was increased by 5-hydroxytryptamine incubation (158% of control), while in hypothalamic astrocytes, no significant effects were seen. Similar effects from 5-hydroxytryptamine or glutamate treatments were observed on dye transfer, indicating an effect on the junctional coupling strength. These results demonstrate a strong relationship between connexin-43 messenger RNA levels, protein expression, and gap junction permeability among astroglial cells. Furthermore, our results suggest heterogeneity among astroglial cells from different brain regions in intercellular calcium signaling and in its differential modulation by neurotransmitters, probably reflecting functional requirements in various brain regions.
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Papers by Elisabeth Hansson