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Suppression of mast cell activation by glucocorticoid

100%

Yoshikawa H., Tasaka K.

Archivum Immunologiae et Therapiae Experimentalis

2000

vol. 48

issue 5

487-496

Mast cells play a critical role in allergic diseases. When mast cells are activated by cross-linking of their high affinity IgE receptors by the antigen and IgE antibodies, release of chemical mediators is followed by secretion of multiple cytokines. We report that IL-3-dependent mucosal-type mast cells undergo apoptosis when IL-3 is withdrawn. In addition, cross-linking of high affinityIgE receptors prevents apoptosis of mast cells by paractine mechanisms, producing IL-3, IL-4 and granulocyte/macrophage colony-stimulating factor (GM-CSF). However, the secretion of endogenous growth factors are not enough for cell survival, whereas IL-4 induces cell aggregation by expressing adhesion molecules such as leukocyte function-associated antigen 1 (LFA-1), and makes it reactive to endogenous growth factors by contact cell to cell interaction. On the other hand, dexamethazone down-regulates the expression of intracellular adhesion molecule 1 (ICAM-1) and IL-4 in activated mast cells, by which the self-aggregation of mast cells is inhibited and poptosis is induced. Thus, glucocorticoids suppress mast cell survival by inhibiting IL-4 production and expression of adhesion molecules.

Photon Force-Induced Phase Transition Dynamics of Single Hydrogel Nanoparticles in Water

71%

Hosokawa C., Matsumura Y., Yoshikawa H., Iwai K., Masuhara H.

Acta Physica Polonica A

2007

vol. 112

issue S

S-57-S-70

We investigated laser-induced phase transition dynamics of μm sized single poly(N-isopropylacrylamide) hydrogel particles in water. Single poly(N-isopropylacrylamide) gel particles labeled with a polarity-sensitive fluorescent probe monomer were optically trapped by a focused laser beam and its fluorescence dynamics was analyzed. The fluorescence intensity of trapped single gel particles was increased with the trapping laser power, while the fluorescence peak wavelength was not changed. Temperature-induced changes of fluorescence properties of the single particle were confirmed to be similar to those of the bulk solution. These behaviors are well interpreted by considering that the fluorescence intensity and fluorescence peak reflect local interactions between the fluorescent probe and attaching (bound) water molecules and effective polarity determined by (free) water content in the particle, respectively. A change in the fluorescence peak wavelength after laser trapping was followed and its blue-shift was confirmed to occur within a few hundreds seconds, indicating that a single gel particle gradually attains to a globular state on this timescale, expelling initially free water molecules and then bound ones.

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1 Acta Physica Polonica A

1 Archivum Immunologiae et Therapiae Experimentalis

1 2007

1 2000

2 Yoshikawa H.

1 Hosokawa C.

1 Iwai K.

1 Masuhara H.

1 Matsumura Y.

1 Tasaka K.

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Suppression of mast cell activation by glucocorticoid

Photon Force-Induced Phase Transition Dynamics of Single Hydrogel Nanoparticles in Water