ABSTRACT
Objective@#To test whether the tryptophan metabolism was abnormal in newly diagnosed ITP patients as well as in these patients after treatment with dexamethasone.@*Methods@#Newly diagnosed patients with ITP between Jan 2014 and May 2015 were enrolled, including 14 females and 11 males, with a median age of 57 years and a median PLT count of 16 (0-32) ×109/L. All patients were treated with oral dexamethasone. The expression levels of IDO mRNA and TTS mRNA in peripheral blood mononuclear cells (PBMC) were analyzed by real-time quantitative polymerase chain reaction. ELISA was used to test the concentrations of IDO and TTS in serum. The concentrations of plasma kynurenine and tryptophan were detected by high-pressure liquid chromatography. Samples from healthy individuals were tested as controls.@*Results@#①After dexamethasone treatment, 17 patients resulted in persistent remission, 2 cases were ineffective, and relapse occurred in 6 cases at a median follow-up of 11 (6-18) months. ②Before and after dexamethasone treatment, the relative expression of indoleamine2,3-dioxygenase (IDO) mRNA and tryptophanyl t-RNA synthetase (TTS) mRNA showed that there were significant decline in persistent remission group (2.54±0.86 vs 19.85±5.36, t=3.188, P=0.003; 0.68±0.19 vs 45.39±15.83, t=2.842, P=0.008) , compared with the normal control group, the difference was not statistically significant (t=2.313, P=0.027; t=1.127, P=0.268) . After treatment, the IDO concentration decreased [ (19.34±0.42) U/ml] and the TTS concentration was markedly increased [ (13.37±0.54) μg/L] in sustained remission group compared with that before treatment [ (21.91±0.37) U/ml] as well as that in normal controls. In particularly, abnormal tryptophan catabolism could be recovered in these 17 patients with persistent remission [Try: (19.85±5.36) μmol/L vs (19.65±4.55) μmol/L, t=1.027, P=0.311; Kyn: (0.56±0.26) μmol/L vs (0.58±0.23) μmol/L, t=2.075, P=0.448]. ③There was no obviously difference in the relative expression of IDO mRNA and TTS mRNA, the concentration of IDO and TTS and the abnormal tryptophan catabolism between before and after treatment of dexamethasone in patients without response and relapsed patients (all P>0.01) .@*Conclusion@#The tryptophan catabolism was abnormal in ITP patients, and it could be recovered in patients with persistent remission.
ABSTRACT
Objective To discuss the role of indoleamine 2, 3-dioxygenas e (IDO) and tryptophanyl-tRNA synthetase (TTS) mediated tryptophan catabolism in immune thrombocytopenia (ITP) patients treated with high doses of dexamethasone through the expressions of IDO and TTS in T cells , and the concentrations of plasma kynurenine and tryptophan. Methods 20 newly diagnosed or relapse ITP patients were treated with 40 mg/d × 4 d dose of dexamethasone. The heparin anticoagulant blood samples were obtained before treatment and the 5th day after treatment. 20 healthy subjects were selected as the control group. The IDO and TTS expressions in CD4+and CD8+ T cells were analyzed by flow cytometry. The concentrations of plasma kynurenine and tryptophan were detected by liquid-mass spectrometry system. Results Compared with healthy controls group, the plasma tryptophan and kynurenine concentration and the ratio of Kyn/Trp were significantly elevated in ITP patients (P <0.05); the IDO expressions of CD4+ and CD8+ T cells in ITP patients were significantly lower than those in healthy controls (P < 0.05), but the TTS expressions were significantly higher (P < 0.05). The concentration of tryptophan in effective group was significantly lower than before treatment (P < 0.05), in contrast, the kynurenine concentration and the ratio of Kyn/Trp were significantly higher than before (P < 0.05). The expression of IDO in effective group were significantly higher than that before treatment (P < 0.05), conversely, the expression of TTS in effective group were significantly decreased (P < 0.05). No significant difference can be found in ineffective group. Conclusion IDO/TTS-mediated tryptophan catabolism pathway could indicate the onset of ITP. The sensitivity of ITP patients with high dose of dexamethasone treatment can be observed through the level of IDO and TTS.
ABSTRACT
Objective To investigate the effect of interferon-γ(IFN-γ) on the expression of indoleamine 2,3-dioxygenase(IDO),and tryptophanyl-tRNA-synthetase (TTS) in thyrocytes; and to study the relevant immunopathological significance in Graves' disease.Methods The expressions of IDO and TTS genes in IFN-γ stimulated Nthy-ori3-1 cell line and human thyrocytes,as well as in human thyroid tissues were determined by realtime quantitative PCR.Results IDO and TTS genes were expressed slightly in both Nthy-ori3-1 cell line and human thyrocytes,and were significantly up-regulated after IFN-γ stimulation(P＜0.01).Compared to healthy controls,TTS mRNA level was higher in thyroid tissues of patients with Graves' disease (P =0.018 2),while IDO mRNA level showed no difference,but was notably correlated with IFN-γ mRNA level (R2 =0.716,P =0.002).Conclusion In the early stage of Graves' disease,thyrocytes may decompose local tryptophan by enhancing the expression of IDO and TTS under IFN-γstimulation,thus inhibit auto-reactive function of lymphocytes and balance excessive autoimmune reaction.
ABSTRACT
The kinetoplast genetic code deviates from the universal code in that 90 percent of mitochondrial tryptophans are specified by UGA instead of UGG codons. A single nucleus-encoded tRNA Trp(CCA) is used by both nuclear and mitochondria genes, since all kinetoplast tRNAs are imported into the mitochondria from the cytoplasm. To allow decoding of the mitochondrial UGA codons as tryptophan, the tRNA Trp(CCA) anticodon is changed to UCA by an editing event. Two tryptophanyl tRNA synthetases (TrpRSs) have been identified in Trypanosoma brucei: TbTrpRS1 and TbTrpRS2 which localize to the cytoplasm and mitochondria respectively. We used inducible RNA interference (RNAi) to assess the role of TbTrpRSs. Our data validates previous observations of TrpRS as potential drug design targets and investigates the RNAi effect on the mitochondria of the parasite.