Toxoplasma gondii provokes rapid and sustained nuclear translocation of the signal transducer and activator of transcription 6 (STAT6) in HeLa cells. We observed activation of STAT6 as early as 2 hr after infection with T. gondii by the nuclear translocation of fluorescence expressed from exogenously transfected pDsRed2-STAT6 plasmid and by the detection of phosphotyrosine-STAT6 in Western blot. STAT6 activation occurred only by infection with live tachyzoites but not by co-culture with killed tachyzoites or soluble T. gondii extracts. STAT6 phosphorylation was inhibited by small interfering RNA of STAT6 (siSTAT6). In view of the fact that STAT6 is a central mediator of IL-4 induced gene expression, activation of STAT6 by T. gondii infection resembles that infected host cells has been stimulated by IL-4 treatment. STAT1 was affected to increase the transcription and expression by the treatment of siSTAT6. STAT6 activation was not affected by any excess SOCS's whereas that with IL-4 was inhibited by SOCS-1 and SOCS-3. T. gondii infection induced Eotaxin-3 gene expression which was reduced by IFN-gamma. These results demonstrate that T. gondii exploits host STAT6 to take away various harmful reactions by IFN-gamma. This shows, for the first time, IL-4-like action by T. gondii infection modulates microbicidal action by IFN-gamma in infected cells.
Active Transport, Cell Nucleus ; Animals ; Chemokines, CC/biosynthesis ; Hela Cells ; Humans ; Interleukin-4/*immunology ; Mice ; Mice, Inbred BALB C ; STAT6 Transcription Factor/*immunology/*metabolism ; Toxoplasma/*immunology

In intestinal helminth infections, Th2 immune respones are generally associated with mucin secretion for worm expulsion from the host intestine. In particular, IL-4 and IL-13 are the important cytokines related with intestinal mucus production via STAT6 signalling in nematode infections. However, this perspective has never been studied in Gymnophalloides seoi infection. The present study aimed to observe the STAT6 signalling and cytokine responses in C57BL/6 mice, a mouse strain resistant to infection with this trematode. The results showed that worm expulsion occurred actively during days 1-2 post-infection (PI), when goblet cells began to proliferate in the small intestine. The STAT6 gene expression in the mouse spleen became remarkable from day 2 PI. Moreover, G. seoi infection induced a significant increase of IL-13 from day 4 PI in the spleen of infected mice. Our results suggested that goblet cell hyperplasia and worm expulsion in G. seoi-infected mice should be induced by STAT6 signalling, in which IL-13 may be involved as a dominant triggering cytokine.
Animals ; Crassostrea ; Female ; Goblet Cells/*pathology ; Hyperplasia/pathology ; Interleukin-13/*metabolism ; Interleukin-4/*metabolism ; Intestine, Small/immunology ; Metacercariae ; Mice ; Mice, Inbred C57BL ; STAT6 Transcription Factor/*metabolism ; Signal Transduction ; Specific Pathogen-Free Organisms ; Spleen/immunology ; Trematoda/*immunology ; Trichinellosis/*immunology/parasitology

The study was aimed to explore the effects of T-bet (T-box expressed in T cell), GATA-3(GATA binding protein 3) and relevant signal transduction pathways on the immune-related pathogenesis of chronic aplastic anemia (CAA), and to investigate the immunological regulation mechanism in the treatment of CAA by using cyclosporine A (CsA) at the level of Th cell imbalance, transcriptional factors, and relevant signal pathways. The real-time fluorescent quantitative polymerase chain reaction (real-time FQ-PCR) was used to determine the mRNA expression of T-bet, GATA-3, signal transducers and activators of transcription 4 (STAT4) and signal transducers and activators of transcription 6 (STAT6) in peripheral blood mononuclear cell (PBMNC) of CAA patients before and after treatment with CsA; the flow cytometry (FCM) and enzyme linked immunosorbent assay (ELISA) were used to determine the Th1/Th2 proportion in peripheral blood, and levels of IFN-γ, IL-12 and IL-4 in PBMNC-cultured supernatant. Healthy people were included to test the above indexes. The results showed that the mRNA expression of PBMNC T-bet, STAT4, T-bet/GATA-3 ratio, Th1 proportion, Th1/Th2 ratio and levels of IFN-γ and IL-12 in PBMNC-cultured supernatant of CAA patients were significantly higher than those of healthy people (p < 0.01). After treating with CsA for 6 months of CsA treatment, expression of T-bet, STAT4, T-bet/GATA-3 ratio, Th1 proportion, IFN-γ and IL-12 levels were lower than before, however, the expression of T-bet, STAT4, T-bet/GATA-3 ratio, Th1 proportion and IFN-γ had not been reduced to normal state. Compared to healthy people, no significant difference existed in the mRNA expression of GATA-3, STAT6, Th2 proportion, as well as level of IL-4 before and after treatment (p>0.05). It is concluded that the abnormal activation of IFN-γ/T-bet and IL-12/STAT4 pathways, as well as Th balance deviating to Th1 excursion play vital roles in the immunological pathogenesis of AA. CsA lowers the abnormal activation of IFN-γ/T-bet and IL-12/STAT4 pathways to correct Th1 hyperpolarization, which may reduce the abnormally activated cell-mediated immunity and relax hematopoietic depression of AA patients.
Adolescent ; Adult ; Aged ; Anemia, Aplastic ; drug therapy ; immunology ; metabolism ; Case-Control Studies ; Cyclosporine ; pharmacology ; Female ; GATA3 Transcription Factor ; metabolism ; Humans ; Interferon-gamma ; metabolism ; Interleukin-12 ; metabolism ; Interleukin-4 ; metabolism ; Male ; Middle Aged ; STAT4 Transcription Factor ; metabolism ; STAT6 Transcription Factor ; metabolism ; Signal Transduction ; T-Box Domain Proteins ; metabolism ; Th1 Cells ; drug effects ; Th2 Cells ; drug effects ; Young Adult

Initial skirmishes between the host and pathogen result in spillage of the contents of the bacterial cell. Amongst the spillage, the secondary messenger molecule, cyclic dimeric guanosine monophosphate (c di-GMP), was recently shown to be bound by stimulator of interferon genes (STING). Binding of c di-GMP by STING activates the Tank Binding Kinase (TBK1) mediated signaling cascades that galvanize the body's defenses for elimination of the pathogen. In addition to c di-GMP, STING has also been shown to function in innate immune responses against pathogen associated molecular patterns (PAMPs) originating from the DNA or RNA of pathogens. The pivotal role of STING in host defense is exemplified by the fact that STING(-/-) mice die upon infection by HSV-1. Thus, STING plays an essential role in innate immune responses against pathogens. This opens up an exciting possibility of targeting STING for development of adjuvant therapies to boost the immune defenses against invading microbes. Similarly, STING could be targeted for mitigating the inflammatory responses augmented by the innate immune system. This review summarizes and updates our current understanding of the role of STING in innate immune responses and discusses the future challenges in delineating the mechanism of STING-mediated responses.
Animals ; Cyclic GMP ; physiology ; Dimerization ; Herpes Simplex ; immunology ; pathology ; Humans ; Immunity, Innate ; Membrane Proteins ; chemistry ; genetics ; metabolism ; Protein Binding ; RNA, Viral ; metabolism ; STAT6 Transcription Factor ; metabolism ; Second Messenger Systems

OBJECTIVETo investigate the levels of cytokines related to T-helper (Th) 17 cells in serum and signal transducers in the psoriatic lesions of patients with psoriasis vulgaris of blood-heat syndrome (BHS) and blood-stasis syndrome (BSS).

METHODSSixty patients with psoriasis vulgaris were divided into the BHS and BSS groups according to the syndrome differentiation of Chinese medicine (CM). Ten healthy subjects were considered as the control group. Cytokine levels of interleukin (IL)-17, IL-23 and IL-6 in serum were determined by enzyme-linked immunosorbent assay. Expression levels of signal transducer and activator of transcription 3 (STAT3), p38-mitogen-activated protein kinase (MAPK) and STAT6 in the psoriatic lesions were determined using immunohistochemistry (IHC), Western blot, and real-time quantitative reverse transcription polymerase chain reaction, respectively.

RESULTSProduction of IL-17, IL-23 and IL-6 in the BHS group and BSS group were significantly increased compared with those in the control group (P<0.05). Levels of IL-17 and IL-23 in the BHS group were higher than those in the BSS group (P<0.05). Compared with the control group, IHC positive expressions and protein expressions of STAT3 and p38-MAPK, and the STAT3 mRNA expressions in the BHS and BSS groups were significantly higher (P<0.05 or P<0.01). The protein expression of STAT3 in the BHS group was significantly higher than that in the BSS group (P<0.05).

CONCLUSIONSCytokines in serum and signal transducers in the psoriatic lesions alter with various CM syndromes of psoriasis. The results provide scientific basis for the treatment based on syndrome differentiation of CM in treating psoriasis vulgaris.

Adult ; Female ; Gene Expression Regulation ; Humans ; Immunohistochemistry ; Interleukin-17 ; blood ; Interleukin-23 ; blood ; Interleukin-6 ; blood ; Male ; Psoriasis ; blood ; enzymology ; genetics ; immunology ; RNA, Messenger ; genetics ; metabolism ; STAT3 Transcription Factor ; genetics ; metabolism ; STAT6 Transcription Factor ; genetics ; metabolism ; Signal Transduction ; Syndrome ; Th17 Cells ; immunology ; p38 Mitogen-Activated Protein Kinases ; genetics ; metabolism

OBJECTIVETo study the expression of signal transducer and activator of transcription 6 and its mRNA in rat asthma model and the modulatory effect of dexamethasone (DXM).

METHODSThirty male SD rats were randomly divided into three groups: the control group, asthma group and DXM group. The rats in each group were sacrificed 24 h after the last challenge. In the experiment, the rat model of asthma was established by ovalbumin (OVA) challenge method. The lung tissue was taken from the left lung, and bronchoalveolar lavage fluid (BALF) was collected from the right lung. The total cell numbers, eosinophils (EOS) count and differentiated cell counts in BALF were performed on different count fluids. The concentrations of IL-4 in serum and BALF were measured by using sandwich ELISA. The protein expressions of STAT6 were detected with immunohistochemical techniques. The mRNA expressions of STAT6 were detected with in situ hybridization.

RESULTS(1) The total cell counts in BALF, the absolute counts of EOS, and the ratios of eosinophils to the total cell numbers (EOS%) of asthma group were all significantly higher than those of the control group (P < 0.01). The total cell counts in BALF, the absolute counts of EOS, and EOS% of DXM group were all significantly lower than those of asthma group (P < 0.01). (2) The concentrations of IL-4 in BALF and serum of asthma group [(25.7 +/- 7.4) ng/L, (34.2 +/- 10.5) ng/L] were significantly higher than those of control group [(8.6 +/- 3.0) ng/L, (12.1 +/- 2.9) ng/L] (P < 0.01). The concentrations of IL-4 in BALF and serum of DXM group were significantly lower than those of asthma group. (3) Immunohistochemistry showed that the protein content of STAT6 around the bronchus of asthma group (0.171 +/- 0.025) was significantly higher than that of the control group (0.082 +/- 0.022) (P < 0.01), while that of DXM group (0.114 +/- 0.013) was significantly lower than that of asthma group. The epithelial cells were the cells. In situ hybridization showed that the mRNA expression of STAT6 around the bronchus of asthma group (0.180 +/- 0.013) was significantly higher than that of the control group (0.091 +/- 0.012) (P < 0.01), while that of DXM group (0.114 +/- 0.010) was significantly lower than that of asthma group. (4) There was a significant correlation between the concentration of IL-4 in BALF, the content of STAT6 and STAT6 mRNA, respectively, in the epithelial cells of bronchus. There was a significant correlation between the absolute numbers of EOS and EOS% in BALF, the content of STAT6 and STAT6 mRNA, respectively, in the epithelial cells of bronchus.

CONCLUSIONSSTAT6 protein and STAT6 mRNA were found strongly expressed in rat asthma model and the epithelial cells were the chief expressing cells. Dexamethasone had an inhibitory effect on airway inflammatory cells infiltration. It significantly depressed STAT6 and mRNA expression. Which may be a key process in modulatory mechanism of asthma.

Animals ; Anti-Inflammatory Agents ; pharmacology ; Asthma ; drug therapy ; genetics ; metabolism ; Bronchi ; cytology ; Bronchoalveolar Lavage Fluid ; cytology ; Cell Count ; Dexamethasone ; pharmacology ; Disease Models, Animal ; Enzyme-Linked Immunosorbent Assay ; Eosinophils ; drug effects ; Epithelial Cells ; drug effects ; metabolism ; Glucocorticoids ; pharmacology ; Immunohistochemistry ; In Situ Hybridization ; Interleukin-4 ; metabolism ; Male ; RNA, Messenger ; Rats ; Rats, Sprague-Dawley ; STAT6 Transcription Factor ; genetics ; immunology ; metabolism