Tetsuo Fukumoto

Inflammatory and Anti-inflammatory Cytokines Regulate the Recovery from Sublethal X Irradiation in Rat Thymus

Abstract Mizutani, N., Fujikura, Y., Wang, Y-H., Tamechika, M., Tokuda, N., Sawada, T. and Fukumoto, T. Inflammatory and Anti-inflammatory Cytokines Regulate the Recovery from Sublethal X Irradiation in Rat Thymus. Radiat. Res. 157, 281u200a–u200a289 (2002). We investigated the regeneration of rat thymus after sublethal X irradiation (6 Gy). The number of thymocytes was much lower on day 3 after irradiation, and many apoptotic cells were observed. However, by day 5, there had been a rapid proliferation of thymocytes. Since cytokines are considered to be important regulatory factors in postirradiation recovery, we performed in vivo cytokine assays using semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and found serial changes in the cytokine message. The messenger RNA (mRNA) expression of the pro-inflammatory cytokines interleukin 1 beta (Il1b), Il6 and tumor necrosis factor alpha (Tnf) was higher than normal on day 3, lower on day 5, and higher again on day 7. In particular, Tnf was completely absent on day 5 and was expressed again on day 7. Of the anti-inflammatory cytokines Il4, transforming growth factor beta (Tgfb) and Il10, only the Il10 message changed substantially. Il10 expression was very high on day 5 but was completely absent on day 7. Thus the Tnf and Il10 messages were expressed alternately. The changes in the distribution of macrophages detected by the immunohistochemical analysis may be related to the changes in the cytokines. Analysis of cytokine messages in the regenerating thymus in vivo may provide new insights into potential therapies for radiation-induced damage.

Semiquantitative Detection of Cytokine Messages in X-Irradiated and Regenerating Rat Thymus

Abstract Adachi, Y., Tokuda, N., Sawada, T. and Fukumoto, T. Semiquantitative Detection of Cytokine Messages in X-Irradiated and Regenerating Rat Thymus. Radiat. Res. 163, 400– 407 (2005). We investigated the expression of cytokine mRNA derived from thymocytes or thymic epithelial cells in X-irradiated (8 Gy) and recovering rat thymuses, according to our previous observation (Mizutani et al., Radiat. Res. 157, 281–289, 2002). The changes in mRNA expression level of interleukin 2 (Il2), Il4, tumor necrosis factor α (Tnf), interferon γ (Ifng), and transforming growth factor β (Tgfb) were examined. The mRNA expression of Il2 and Il4 decreased from day 5 to day 14 after irradiation. Thereafter, the expression level of Il2 mRNA recovered to normal control levels; however, the expression of Il4 mRNA tended toward significantly low levels. Tnf mRNA expression decreased on day 5 after irradiation and then showed a gradual increase back to normal control levels. Tgfb mRNA expression did not change significantly. Ifng mRNA expression was transiently enhanced from day 11 to day 14. The mRNA expression levels of Il10 increased significantly from day 3 to day 7 after irradiation. In addition, the mRNA expression of thymic epithelial cell-derived Il7 showed a transient decrease on day 3; however, then it showed a continuous increase from day 5 to day 21, finally reaching twice the normal control levels after X irradiation. These observations suggest that the expression of cytokine messages in the irradiated thymus changed significantly and did not return to normal for a long time after 8 Gy irradiation.

Expression of PAC1 receptor in rat thymus after irradiation

In the present work, PAC1-R (G-protein-coupled receptor specific for PACAP) was detected on cells in the normal thymus. Immunohistochemically PAC1-R was expressed strongly in stromal cells of the thymic medulla. Positive cells were also observed in the thymus of fetal and old adult rats. After 8 Gy irradiation to 9-week-old rats, PAC1-R expressions in the thymus decreased and almost recovered by day 21. The expression of PAC1-R mRNA was weak in the thymus and decreased further after irradiation. The expression almost recovered by day 28. Hip and hip/hop variants, which were not expressed in the normal thymus, were expressed in the thymus on days 3, 5 and 21 after irradiation. The expressions of IL-6 and IL-10 tended to increase initially after irradiation then decreased. Histologically, the thymic structures were destroyed on day 3 after irradiation and the thymus almost recovered by day 21. Thus PACAP is thought to be one of the important factors for cross-talk between cells involved in thymic regeneration.

PACAP Receptor (PAC1‐R) Expression in Rat and Rhesus Monkey Thymus

Abstract:u2002 The expression of PACAP receptor (PAC1‐R) was investigated in the thymus of rats and rhesus monkeys. In the rat thymus, PAC1‐R positive cells were found in the intermediate type of thymic epithelial cells of the medulla. PAC1‐R‐positive cells were also seen in the thymic medulla of the rhesus monkey. The thymus showed unusual structures in some rhesus monkey dams (F0) and offspring (F1) exposed to 2, 3, 7, 8‐tetrachlorodibenzo‐p‐dioxin (TCDD). Additionally, in these rhesus monkeys, PAC1‐R expression was different from that in the control thymus.

Spatial relation between major histocompatibility complex‐restricted antigen receptor‐bearing thymocytes and subtypes of thymic epithelial cells

R73, a monoclonal antibody that recognizes a rat T cell surface antigen of TCRαβ, was used to identify thymocytes that express major histocompatibility complex‐restricted antigen receptors, and to define the spatial relation between these receptor‐bearing thymocytes and individual thymic cortical and medullary epithelial subtypes by ultrastructural immunohistochemistry. We show that in both the cortex and medulla 1) the thymocytes that reacted with R73 antibodies exhibited three staining patterns: cytoplasmic‐only staining, simultaneous cytoplasmic and surface membrane staining, and surface membrane‐only staining; 2) the subcapsular/perivascular epithelial cells (ECs) were usually associated with thymocytes expressing perinuclear staining only; and 3) the surface membrane areas of thymocytes that expressed antigen receptors made contact with pale and intermediate ECs, but not with dark cells. These results suggest that thymic selection of major histocompatibility complex restriction and/or tolerance may occur by interaction of the receptors on maturing thymocytes with major histocompatibility complex antigens on thymic ECs in general, and on pale and intermediate subtypes in particular. Anat Rec 267:131–136, 2002.

Thermoluminescence of X-Ray-Irradiated CdS-Doped Glass

Thermoluminescence has been observed in X-ray-irradiated CdS-doped glass. The intensity of thermoluminescence is proportional to the X-ray dose up to 10 Gy. The intensity of thermoluminescence for Asahi Y-44 is approximately 0.5% of that of phosphor for a commercial radiation dosimeter: MSO-S (Mg2SiO4:Tb). Photofading of Y-44 is markedly lower than that for MSO-S.