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The immune mechanism of chronic hepatitis B (CHB) persistent infection is closely associated with T cells, and the development of T cells requires the coordination of a variety of cytokines. The proteins of the signal transducer and activator of transcription (STAT) family are mainly involved in the signal transduction of cytokines, and STAT5a/b and STAT3 play an important role in the differentiation and development of regulatory T cells (Treg) and T helper 17 cells (Th17). This article analyzes the association of STAT3 and STAT5 with Treg/Th17 balance in CHB and investigates the chronicity of hepatitis B virus infection and the regulatory mechanism of liver inflammation.
ABSTRACT
Objective To investigate the effects of polycyclic aromatic hydrocarbons ( PAHs) on regulatory T ( Treg) cells in newborns.Methods Blood samples were taken from the umbilical cord of sev-en newborn babies.CD4+CD25+T cells were isolated and treated with or without 300 nmol/L of phenan-threne for 72 hours in the presence of 100 IU/ml of IL-2.The expression of forkhead box P3 (Foxp3), sig-nal transducer and activator of transcription 3 (STAT3) and STAT5 were analyzed by 8-color flow cytometry. RT-PCR was performed to detect the expression of DNA ( cytosine-5 )-methyltransferase 1 ( DNMT1 ) , DNMT3a, DNMT3b and IL-4 at mRNA level.Pyrosequencing in combination with bisulphite sequencing was used to evaluate the methylation within the promoter and the Treg-specific demethylated region ( TSDR) of Foxp3 locus.Treg cells were cultured for 7 hours with autologous Tresp at Tresp/Treg ratios of 1 ∶1, 2 ∶1, 4 ∶1 and 8 ∶1 and stimulated with anti-CD3/CD28 beads and IL-2 for the evaluation of the immunosuppres-sive activities of Treg cells.Results (1) PAHs inhibited the expression of Foxp3 and the function of Treg cells collected from newborns.(2) PAHs significantly decreased the expression of STAT5 and Foxp3, but increased the expression of STAT3 (P<0.05).(3)PAHs enhanced the methylation of the promoter and the TSDR within Foxp3 gene.(4) The transcription levels of DNMT1, DNMT3a and DNMT3b in PAHs treated group were significantly higher than those of the control group (P<0.05).(5) More IL-4 was secreted by PAHs treated CD4+CD25+T cells, indicating that IL-4 was negatively correlated with STAT5, but positively correlated with STAT3.Conclusion PAHs decreased the number and inhibited the function of Treg cells in newborns.The possible mechanism might be related to the abnormal expression of STAT3 and STAT5 in-duced by IL-4 as well as the methylation within Foxp3 gene.
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Objective To investigate the expression of pSTAT5 in 7 pancreatic carcinoma cell lines,and the change of expression of pSTAT5 in pancreatic carcinoma cells SW1990 after growth hormone (GH) treatment, and explore its molecular mechanism. Methods Human pancreatic carcinoma cell lines (SW1990, Cap-1, Colo, Mia, AsPc, P3, PANC1) were cultured in vitro, and Western blotting was used to detect the expression of pSTAT5 in these cell lines. SW1990 in exponential growth phase was collected and nude Balb/c mice were inoculated with SW1990 cells. When tumors became palpable after inoculation, mice (normal saline group). 1 h, 2 h and 24 h after the last dose of GH treatment, the mice were sacrificed.Western blotting was used to detect the expression of pSTAT5 in SW1990 and inoculation tumor cells after GH injection. Results Positive expression of pSTAT5 was observed in all human pancreatic carcinoma cell lines (SW1990, Cap-1, Colo, Mia, Aspc, P3, PANC1). 5 minutes after GH (50 ng/ml) stimulation, the expression of pSTAT5 in SW1990 was 0.57 ±0.05, which was significantly increased; and it reached 0.64 ±0.04 at 10 minutes, then decreased to 0.39 ±0.03 at 15 minutes, however, it remained higher than that in the control group at 1 h (0.33 ± 0.02 vs 0.25 ± 0.06), and its expression at 2 h was 0.26 ± 0.03 and returned to the normal level. The expression of pSTAT5 in xenograft was not significantly changed. Conclusions GH could rapidly up-regulate the expression of pSTAT5 in SW1990 but the effect lasted for a relatively short period. GH had no significant effect on the expression of pSTAT5 in xenograft.
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Objective: As a potential gene therapeutic method, transcription factor decoy strategy has been used to block the transcription function of multi-transcription factors. This study aims to further verify the inhibitory effect of signal transducer and activator of transcription 5 (STAT 5) decoy oligodeoxynucleotides (ODN) on tumor growth in nude mice. Methods: The xenografted tumor model was established by subcutaneously injecting leukemia K 562 cells in nude mice. Liposome-ODN complex was directly injected into tumor body once daily every 3 days. The tumor growth and tumor size were measured everyday. Nude mice were sacrificed at the end of the experiment. The tumor was removed and weighed. RT-PCR and Western blotting were performed to detect mRNA and protein expression of bcl-xL, cyclin D1, and c-myc, respectively. Results: The tumorigenicity of K 562 cells was significantly inhibited by decoy ODN. The tumor weight was markedly reduced in decoy ODN group than mutant ODN group [(0.485 ± 0.178) g vs (0.928 ± 0.223) g, P < 0.05 ]. The tumor growth inhibition rate was 47.7%. RT-PCR and Western blotting showed that the mRNA and protein expression level of bcl-xL, cyclinD1, and c-myc were down-regulated. Conclusion: Transcription factor decoy strategy effectively blocks transcription of STAT 5 target genes in xenografted tumor of nude mice.