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Combustible Cigarette and Smokeless Tobacco Product Preparations Differentially Regulate Intracellular Calcium Mobilization in HL60 Cells.
Arimilli, S, Makena, P, Prasad, GL
Inflammation. 2019;(5):1641-1651
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Abstract
Changes in the level of intracellular calcium ([Ca2+]i) are central to leukocyte signaling and immune response. Although evidence suggests that cigarette smoking affects inflammatory response via an increase in intracellular calcium, it remains unclear if the use of smokeless tobacco (e.g., moist snuff) elicits a similar response. In this study, we evaluated the effects of tobacco product preparations (TPPs), including total particulate matter (TPM) from 3R4F reference cigarettes, smokeless tobacco extract (STE) from 2S3 reference moist snuff, and nicotine alone on Ca2+ mobilization in HL60 cells. Treatment with TPM, but not STE or nicotine alone, significantly increased [Ca2+]i in a concentration-dependent manner in HL60 cells. Moreover, TPM-induced [Ca2+]i increase was not related to extracellular Ca2+ and did not require the activation of the IP3 pathway nor involved the transient receptor potential (TRP) channels. Our findings indicate that, in cells having either intact or depleted endoplasmic reticulum (ER) Ca2+ stores, TPM-mediated [Ca2+]i increase involves cytosolic Ca2+ pools other than thapsigargin-sensitive ER Ca2+ stores. These results, for the first time, demonstrate that TPM triggers [Ca2+]i increases, while significantly higher nicotine equivalent doses of STE or nicotine alone, did not affect [Ca2+]i under the experimental conditions. In summary, our study suggests that in contrast with STE or nicotine preparations, TPM activates Ca2+ signaling pathways in HL60 cells. The differential effect of combustible and non-combustible TPPs on Ca2+ mobilization could be a useful in vitro endpoint for tobacco product evaluation.
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Calcium signalling in T cells.
Trebak, M, Kinet, JP
Nature reviews. Immunology. 2019;(3):154-169
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Abstract
Calcium (Ca2+) signalling is of paramount importance to immunity. Regulated increases in cytosolic and organellar Ca2+ concentrations in lymphocytes control complex and crucial effector functions such as metabolism, proliferation, differentiation, antibody and cytokine secretion and cytotoxicity. Altered Ca2+ regulation in lymphocytes leads to various autoimmune, inflammatory and immunodeficiency syndromes. Several types of plasma membrane and organellar Ca2+-permeable channels are functional in T cells. They contribute highly localized spatial and temporal Ca2+ microdomains that are required for achieving functional specificity. While the mechanistic details of these Ca2+ microdomains are only beginning to emerge, it is evident that through crosstalk, synergy and feedback mechanisms, they fine-tune T cell signalling to match complex immune responses. In this article, we review the expression and function of various Ca2+-permeable channels in the plasma membrane, endoplasmic reticulum, mitochondria and endolysosomes of T cells and their role in shaping immunity and the pathogenesis of immune-mediated diseases.
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Ca(2+) -related signaling events influence TLR9-induced IL-10 secretion in human B cells.
Ziegler, S, Gartner, K, Scheuermann, U, Zoeller, T, Hantzschmann, J, Over, B, Foermer, S, Heeg, K, Bekeredjian-Ding, I
European journal of immunology. 2014;(5):1285-98
Abstract
Suppressory B-cell function controls immune responses and is mainly dependent on IL-10 secretion. Pharmacological manipulation of B-cell-specific IL-10 synthesis could, thus, be therapeutically useful in B-cell chronic lymphocytic leukemia, transplantation, autoimmunity and sepsis. TLR are thought to play a protagonistic role in the formation of IL-10-secreting B cells. The aim of the study was to identify the molecular events selectively driving IL-10 production in TLR9-stimulated human B cells. Our data highlight the selectivity of calcineurin inhibitors in blocking TLR9-induced B-cell-derived IL-10 transcription and secretion, while IL-6 transcription and release, B-cell proliferation, and differentiation remain unaffected. Nevertheless, TLR9-induced IL-10 production was found to be independent of calcineurin phosphatase activity and was even negatively regulated by NFAT. In contrast to TLR9-induced IL-6, IL-10 secretion was highly sensitive to targeting of spleen tyrosine kinase (syk) and Bruton's tyrosine kinase. Further analyses demonstrated increased phosphorylation of Ca(2+) /calmodulin kinase II (CaMKII) in TLR9-stimulated B cells and selective reduction of TLR9-induced secretion of IL-10 upon treatment with CaMKII inhibitors, with negligible impact on IL-6 levels. Altogether, our results identify calcineurin antagonists as selective inhibitors of IL-10 transcription and syk/BrutonĀ“s tyrosine kinase-induced Ca(2+) /calmodulin- and CaMKII-dependent signaling as a pathway regulating the release of TLR9-induced B-cell-derived IL-10.
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Ion channels and anti-cancer immunity.
Panyi, G, Beeton, C, Felipe, A
Philosophical transactions of the Royal Society of London. Series B, Biological sciences. 2014;(1638):20130106
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Abstract
The outcome of a malignant disease depends on the efficacy of the immune system to destroy cancer cells. Key steps in this process, for example the generation of a proper Ca(2+) signal induced by recognition of a specific antigen, are regulated by various ion channel including voltage-gated Kv1.3 and Ca(2+)-activated KCa3.1 K(+) channels, and the interplay between Orai and STIM to produce the Ca(2+)-release-activated Ca(2+) (CRAC) current required for T-cell proliferation and function. Understanding the immune cell subset-specific expression of ion channels along with their particular function in a given cell type, and the role of cancer tissue-dependent factors in the regulation of operation of these ion channels are emerging questions to be addressed in the fight against cancer disease. Answering these questions might lead to a better understanding of the immunosuppression phenomenon in cancer tissue and the development of drugs aimed at skewing the distribution of immune cell types towards killing of the tumour cells.
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T-cell artificial focal triggering tools: linking surface interactions with cell response.
Carpentier, B, Pierobon, P, Hivroz, C, Henry, N
PloS one. 2009;(3):e4784
Abstract
T-cell activation is a key event in the immune system, involving the interaction of several receptor ligand pairs in a complex intercellular contact that forms between T-cell and antigen-presenting cells. Molecular components implicated in contact formation have been identified, but the mechanism of activation and the link between molecular interactions and cell response remain poorly understood due to the complexity and dynamics exhibited by whole cell-cell conjugates. Here we demonstrate that simplified model colloids grafted so as to target appropriate cell receptors can be efficiently used to explore the relationship of receptor engagement to the T-cell response. Using immortalized Jurkat T cells, we monitored both binding and activation events, as seen by changes in the intracellular calcium concentration. Our experimental strategy used flow cytometry analysis to follow the short time scale cell response in populations of thousands of cells. We targeted both T-cell receptor CD3 (TCR/CD3) and leukocyte-function-associated antigen (LFA-1) alone or in combination. We showed that specific engagement of TCR/CD3 with a single particle induced a transient calcium signal, confirming previous results and validating our approach. By decreasing anti-CD3 particle density, we showed that contact nucleation was the most crucial and determining step in the cell-particle interaction under dynamic conditions, due to shear stress produced by hydrodynamic flow. Introduction of LFA-1 adhesion molecule ligands at the surface of the particle overcame this limitation and elucidated the low TCR/CD3 ligand density regime. Despite their simplicity, model colloids induced relevant biological responses which consistently echoed whole cell behavior. We thus concluded that this biophysical approach provides useful tools for investigating initial events in T-cell activation, and should enable the design of intelligent artificial systems for adoptive immunotherapy.
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CD38/cyclic ADP-ribose regulates astrocyte calcium signaling: implications for neuroinflammation and HIV-1-associated dementia.
Banerjee, S, Walseth, TF, Borgmann, K, Wu, L, Bidasee, KR, Kannan, MS, Ghorpade, A
Journal of neuroimmune pharmacology : the official journal of the Society on NeuroImmune Pharmacology. 2008;(3):154-64
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Abstract
CD38 is a 45-kD ectoenzyme involved in the synthesis of potent calcium (Ca(2+))-mobilizing agents, cyclic adenosine diphosphate-ribose (cADPR), and nicotinic acid adenine dinucleotide phosphate (NAADP+). In HIV-1-infected patients, increased CD38 expression on CD8+ T cells is linked to immune system activation and progression of HIV-1 infection. However, the role of CD38 upregulation in astrocyte function and HIV-1-associated dementia (HAD-now called HAND HIV-1-associated neurocognitive disorder) neuropathogenesis is unclear. To these ends, we used interleukin (IL)-1beta and HIV-1gp120 to activate primary human astrocytes and measured CD38 expression using real-time polymerase chain reaction and CD38 function by ADP-ribosyl cyclase activity. We also determined cADPR-mediated changes in single-cell intracellular Ca(2+) transients in activated astrocytes in presence or absence of ethylene glycol tetraacetic acid. CD38 levels were downregulated using CD38 small-interfering RNA (siRNA) and intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured. We previously reported a approximately 20-fold rise in CD38 messenger RNA levels in IL-1beta-activated astrocytes. We extend this observation and report that HIV-1gp120 potentiated CD38 expression in a dose-dependent manner and also increased CD38 enzyme activity in control and IL-1beta-activated astrocytes. We demonstrate higher cADPR levels in IL-1beta-activated astrocytes with a corresponding rise in [Ca(2+)](i) upon cADPR application and its non-hydrolysable analog, 3-deaza-cADPR. In activated astrocytes, pre-treatment with the cADPR-specific antagonist 8-Br-cADPR and CD38 siRNA transfection returned elevated [Ca(2+)](i) to baseline, thus confirming a CD38-cADPR specific response. These data are important for unraveling the mechanisms underlying the role of astrocyte-CD38 in HAD and have broader implications in other inflammatory diseases involving astrocyte activation and CD38 dysregulation.