GATA-3 is a master regulator for TH2 differentiation. It is however poorly understood if GATA-3 controls mature T cell function beyond TH2 determination. We show that TCR signals and cytokine stimulation promoted GATA-3 expression in CD8 T cells, which controlled cell proliferation. While GATA-3-deficient CD8 T cells were generated, their peripheral maintenance was impaired with reduced IL-7R expression. GATA-3-deficient T cells had defective responses to viral infection and alloantigen. c-Myc was a critical target of GATA-3 in promoting the proliferation of activated T cells. This study thus demonstrates an essential role of GATA-3 in controlling T cell maintenance and expansion beyond TH2 differentiation, providing insights into immune regulation.

Th17 cells are critically involved in host defense, inflammation, and autoimmunity1–5. TGF-β is instrumental in Th17 differentiation by cooperating with IL-66,7. Yet, the mechanism of how TGF-β enables Th17 differentiation remains elusive. Here we reveal that TGF-β licenses Th17 differentiation by releasing Ski-Smad4-complex suppressed RORγt expression. We found serendipitously that, unlike wild-type T cells, Smad4-deficient T cells differentiated into Th17 cells in the absence of TGF-β signaling in a RORγt-dependent manner. Ectopic Smad4 expression suppressed the RORγt expression and Th17 differentiation of Smad4-deficient T cells. Unexpectedly however, TGF-β neutralized Smad4 mediated suppression without affecting Smad4 binding to Rorc locus. Proteomic analysis revealed that Smad4 interacted with Ski, a transcriptional repressor degraded upon TGF-β stimulation. Ski controlled the histone acetylation/de-acetylation of Rorc locus and Th17 differentiation via Smad4 because ectopic Ski expression inhibited H3K9Ac of Rorc locus, Rorc expression and Th17 differentiation in a Smad4-dependent manner. Therefore, TGF-β-induced disruption of Ski releases Ski-Smad4 complex imposed suppression of RORγt to license Th17 differentiation. This study reveals a critical mechanism by which TGF-β controls Th17 differentiation and uncovers Ski-Smad4 axis as a potential therapeutic target for treating Th17 related diseases.

Dihydroartemisinin (DHA) is an important derivative of an herb medicine Artemisia annua L., used in ancient China. DHA is currently used world-wide to treat malaria by killing malaria-causing parasites. In addition to this prominent effect, DHA is suggested to regulate cellular functions, such as angiogenesis, tumor cell growth and immunity. Nonetheless, how DHA affects T cell function remains poorly understood. We found that DHA potently suppressed Th cell differentiation in vitro. Unexpectedly however, DHA greatly promoted Treg cell generation, in a manner dependent on TGF-βR:Smad signal. In addition, DHA treatment effectively reduced EAE onset and ameliorated ongoing EAE in mice. Administration of DHA significantly decreased Th but increased Treg cells in EAE-inflicted mice without apparent global immune suppression. Moreover, DHA modulated mTOR pathway, because mTOR signal was attenuated in T cells upon DHA treatment. Importantly, enhanced Akt activity neutralized DHA-mediated effects on T cells in an mTOR dependent fashion. This study therefore reveals a novel immune regulatory function of DHA to reciprocally regulate Th and Treg cell generation through modulating mTOR pathway. It addresses how DHA regulates immune function and suggests a new type of drug for treating diseases where mTOR activity to be tempered.

TGF-β modulates immune response by suppressing non-regulatory T (Treg) function and promoting Treg function. The question of whether TGF-β achieves distinct effects on non-Treg and Treg cells through discrete signaling pathways remains outstanding. In this study, we investigated the requirements of Smad-dependent and -independent TGF-β signaling for T-cell function. Smad2 and Smad3 double deficiency in T cells led to lethal inflammatory disorder in mice. Non-Treg cells were spontaneously activated and produced effector cytokines in vivo on deletion of both Smad2 and Smad3. In addition, TGF-β failed to suppress T helper differentiation efficiently and to promote induced Treg generation of non-Treg cells lacking both Smad2 and Smad3, suggesting that Smad-dependent signaling is obligatory to mediate TGF-β function in non-Treg cells. Unexpectedly, however, the development, homeostasis, and function of Treg cells remained intact in the absence of Smad2 and Smad3, suggesting that the Smad-independent pathway is important for Treg function. Indeed, Treg-specific deletion of TGF-β–activated kinase 1 led to failed Treg homeostasis and lethal immune disorder in mice. Therefore, Smad-dependent and -independent TGF-β signaling discretely controls non-Treg and Treg function to modulate immune tolerance and immune homeostasis.

Interferons, which transduce pivotal signals through signal transducer and activator of transcription (Stat)1 and Stat2, effectively suppress the replication of Legionella pneumophila in primary murine macrophages. Whereas the ability of IFN-γ to impede L. pneumophila growth is fully dependent on Stat1, IFN-α/β unexpectedly suppresses L. pneumophila growth in both Stat1 and Stat2 deficient macrophages. New studies demonstrating that the robust response to IFN-α/β is lost in Stat1-Stat2 double knockout macrophages, suggest that Stat1 and Stat2 are functionally redundant in their ability to direct an innate response towards L. pneumophila. Since the ability of IFN-α/β to signal through Stat1-dependent complexes (i.e., Stat1-Stat1 and Stat1-Stat2 dimers) has been well characterized, the current studies focus on how Stat2 is able to direct a potent response to IFN-α/β in the absence of Stat1. These studies reveal that IFN-α/β is able to drive the formation of a Stat2 and IRF9 complex that drives the expression of a subset of IFN stimulated genes (ISGs), but with substantially delayed kinetics. These observations raise the possibility that this pathway evolved in response to microbes that have devised strategies to subvert Stat1 dependent responses.

Summary Transforming growth factor-beta (TGF-β) suppresses T cell function to maintain self-tolerance and to promote tumor immune evasion. Yet how Smad4, a transcription factor component of TGF-β signaling, regulates T cell function remains unclear. Here we have demonstrated an essential role for Smad4 in promoting T cell function during autoimmunity and anti-tumor immunity. Smad4 deletion rescued the lethal autoimmunity resulting from transforming growth factor-beta receptor (TGF-βR) deletion and compromised T-cell-mediated tumor rejection. While Smad4 was dispensable for T cell generation, homeostasis and effector function, it was essential for T cell proliferation following activation in vitro and in vivo. The transcription factor Myc was identified to mediate Smad4-controlled T cell proliferation. This study thus reveals a requirement of Smad4 for T-cell-mediated autoimmunity and tumor rejection, which is beyond the current paradigm. It highlights a TGF-βR-independent role for Smad4 in promoting T cell function, autoimmunity and anti-tumor immunity.

Immunoglobulin (Ig) A and/or IgG reactivities to several Epstein-Barr virus (EBV) antigens have been used to facilitate diagnosis of nasopharyngeal carcinoma (NPC). However, antibodies against gp78, an EBV membrane glycoprotein, have not been examined to this day. In this study, we utilized Luminex multi-analyte profiling (xMAP) technology to analyse antibody responses to a synthetic peptide of gp78 in sera samples from 95 NPC patients and 91 healthy controls. Our results showed the sensitivity and specificity of IgA-gp78 for NPC diagnosis were 79 and 71 %, respectively, while those of IgG-gp78 were 74 and 73 %, respectively. The IgA and IgG responses to different EBV antigens were not identical within an individual and IgA-gp78 and IgG-gp78 could be complementary to antibodies against viral capsid antigen (VCA), the diffused early antigen (EA-D) and the nuclear antigen EBNA1 for NPC diagnosis. When the six EBV parameters for NPC prediction, i.e. IgA-gp78, IgG-gp78, IgA-VCA, IgA-EBNA1, IgA-EA-D and IgG-EA-D, are combined, the combined predictors were able to reach overall sensitivity and specificity of 91 and 95 %, respectively. Thus, simultaneous detection of these EBV serological markers could improve the predictive values of NPC using xMAP technology. INTRODUCTIONEpstein-Barr virus (EBV) is a ubiquitous gammaherpes virus composed of a protein core enclosed by DNA, an inner nucleocapsid with 162 capsomeres, a middle protein tegument, and an outer envelope carrying various membrane glycoproteins (Dolyniuk et al., 1976;Epstein et al., 1965;Khanna et al., 1995). EBV infects more than 90 % of the population worldwide and usually establishes a lifelong persistence in the host (Cohen, 2000). Most populations get primary infection in childhood and are asymptomatic, but Westerners whose primary infection is delayed until adolescence may develop infectious mononucleosis (Amon & Farrell, 2005). More strikingly, the virus is associated with a spectrum of cancers presenting endemic features, such as Burkitt's lymphoma in Africa and nasopharyngeal carcinoma (NPC) in Southern China and South-East Asia (Pattle & Farrell, 2006;Raab-Traub et al., 1987).EBV is closely correlated with NPC, which could be reflected by consistent expression of EBV gene products in NPC tumour cells and general elevation of serum antibody levels against EBV antigens in NPC patients (Busson et al., 2004;Gastpar et al., 1981;Henle & Henle, 1976;Old et al., 1966;Raab-Traub, 2002). In comparison with healthy EBV carriers, NPC patients typically show strong IgG and especially IgA reactivities to lytic antigens (Fachiroh et al., 2004;Henle & Henle, 1976), so an EBV serological assay could facilitate diagnosis and prognosis of NPC. IgA antibody titres against the EBV viral capsid antigen (VCA) and the diffused early antigens (EA-D) are regularly tested in many clinical centres (Deng et al., 1995; Hadar et al., 1986;Henle & Henle, 1976;Ho et al., 1998 et al., 2004). However, few of them have been shown as valuable markers for NPC diagnosis. gp350/220 is t...

Background: Serological examination of Epstein-Barr virus (EBV) antibodies has been performed for screening nasopharyngeal carcinoma (NPC) and other EBV-associated diseases.