| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2005: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2004: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
Tryptophanyl-tRNA synthetase (TrpRS) was isolated as a gene whose expression was elevated during elicitation of skin delayed-type hypersensitivity (DTH) reaction in guinea pig. The expression of TrpRS protein was increased up to 48h and kept at 72h after the elicitation. In addition to full-length of TrpRS, truncated forms of TrpRS were also detected. These bands were likely to correspond to T1 and T2-TrpRS which are produced by polymorphonuclear leukocytes (PMN) elastase cleavage and have an angiostatic activity in vitro. A portion of full-length TrpRS was secreted from dexamethasone-treated (apoptosis-induced) guinea pig thymocytes and TUNEL assay showed that apoptosis was induced in DTH-reactive skin sites. These results therefore suggest that TrpRS is released from apoptotic cells and processed into T1, T2-TrpRS by PMN elastase in response to the elicitation of DTH reaction. Further, the injection of recombinant T2-TrpRS slightly diminished the edema accompanied with DTH reaction, suggesting that T1, T2-TrpRS is involved in the suppression of the DTH reaction.
It was reported that the expression of TrpRS was elevated by interferon (IFN)-γ and that IFN-γ was produced in skin CD4^+ T cells. To analyze whether DTH reaction is affected by in vivo expression of IFN-γ, the expression plasmid of IFN-γ fused to green fluorescent protein (IFN-γ/GFP), was subcutaneously injected by gene gun, followed by the elicitation of DTH reaction. The increase of IFN-γ expression led to the rise in edema, skinfold thickness and the numbers of infiltrating cells. In contrast, those subcutaneous changes were suppressed when the expression of IFN-γ driven by IFN-γ/GFP was inhibited by co-injection of DNA constructs encoding GFP-specific short-hairpin RNAs. These results suggest that DTH reactions can be controlled by in vivo expression of IFN-γ.
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