Different activation signals induce distinct mast cell degranulation strategies
Nicolas Gaudenzio, … , Eric Espinosa, Stephen J. Galli
Nicolas Gaudenzio, … , Eric Espinosa, Stephen J. Galli
Published September 19, 2016
Citation Information: J Clin Invest. 2016;126(10):3981-3998. https://doi.org/10.1172/JCI85538.
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Research Article Immunology Inflammation

Different activation signals induce distinct mast cell degranulation strategies

Abstract

Mast cells (MCs) influence intercellular communication during inflammation by secreting cytoplasmic granules that contain diverse mediators. Here, we have demonstrated that MCs decode different activation stimuli into spatially and temporally distinct patterns of granule secretion. Certain signals, including substance P, the complement anaphylatoxins C3a and C5a, and endothelin 1, induced human MCs rapidly to secrete small and relatively spherical granule structures, a pattern consistent with the secretion of individual granules. Conversely, activating MCs with anti-IgE increased the time partition between signaling and secretion, which was associated with a period of sustained elevation of intracellular calcium and formation of larger and more heterogeneously shaped granule structures that underwent prolonged exteriorization. Pharmacological inhibition of IKK-β during IgE-dependent stimulation strongly reduced the time partition between signaling and secretion, inhibited SNAP23/STX4 complex formation, and switched the degranulation pattern into one that resembled degranulation induced by substance P. IgE-dependent and substance P–dependent activation in vivo also induced different patterns of mouse MC degranulation that were associated with distinct local and systemic pathophysiological responses. These findings show that cytoplasmic granule secretion from MCs that occurs in response to different activating stimuli can exhibit distinct dynamics and features that are associated with distinct patterns of MC-dependent inflammation.

Authors

Nicolas Gaudenzio, Riccardo Sibilano, Thomas Marichal, Philipp Starkl, Laurent L. Reber, Nicolas Cenac, Benjamin D. McNeil, Xinzhong Dong, Joseph D. Hernandez, Ronit Sagi-Eisenberg, Ilan Hammel, Axel Roers, Salvatore Valitutti, Mindy Tsai, Eric Espinosa, Stephen J. Galli

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Figure 2

Human MC activation by SP or anti-IgE induces distinct [Ca2+]i signaling and degranulation dynamics.

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Human MC activation by SP or anti-IgE induces distinct [Ca2+]i signaling...
IgE-sensitized or nonsensitized PBCMCs were loaded with Fluo-4 and stimulated with anti-IgE antibodies or SP in the presence of Av.SRho. Fluo-4 (green, [Ca2+]i) and Av.SRho (red, identifying exteriorized granule structures) fluorescence was measured, at the single-cell level, using time-lapse confocal microscopy in a controlled atmosphere (37°C and 5% CO2). (A) Representative time-lapse of a single IgE-sensitized PBCMC activated with anti-IgE. (B) Representative time-lapse of a single PBCMC activated with SP. (A and B) Scale bars: 5 μm; white insets show a budding granule structure at higher magnification; arrows indicate first budding granule structures; time scale reflects the kinetics of the responses induced by the 2 stimuli. (C and D) Single-cell analyses of Fluo-4 mean fluorescence intensity (MFI) following anti-IgE (C) or SP (D) stimulation. (E) Mean curves of Fluo-4 MFI following anti-IgE (blue) or SP (pink) stimulation. (F and G) Single-cell analyses of Av.SRho MFI following anti-IgE (F) or SP (G) stimulation. (H) Mean curves of Av.SRho MFI following anti-IgE (blue) or SP (pink) stimulation. Mean; 2-way ANOVA; ****P < 0.0001. Data are from the 3 independent experiments performed, each of which gave similar results. (I and J) Mean curves of Fluo-4 and Av.SRho MFI following anti-IgE (I) or SP (J) stimulation; dotted lines and arrows indicate the lag time (ΔT) measured between the increase in [Ca2+]i and the detection of the first budding granule structures. (K) Mean ΔT measured following anti-IgE (blue) or SP (pink) stimulation. Mean ± SEM; 2-tailed, unpaired t test; ****P < 0.0001. Data are from 3 independent experiments performed with PBCMCs from 3 donors (at least 30 single PBCMCs analyzed per condition), each of which gave similar results.