Center domains and their phenomenological consequences.

We argue that the domain structure of deconfined QCD matter, which can be inferred from the properties of the Polyakov loop, can simultaneously explain the two most prominent experimentally verified features of the quark-gluon plasma, namely its large opacity as well as its near ideal fluid properties.

Third moments of conserved charges as probes of QCD phase structure.

The third moments of conserved charges, the baryon and electric charge numbers, and energy, as well as their mixed moments, carry more information on the state around the QCD phase boundary than previously proposed fluctuation observables and higher order moments. In particular, their signs give plenty of information on the location of the state created in relativistic heavy ion collisions in the temperature and baryon chemical potential plane. We demonstrate this with an effective model.

STAT3 is indispensable to IL-27-mediated cell proliferation but not to IL-27-induced Th1 differentiation and suppression of proinflammatory cytokine production.

IL-27, a member of the IL-6/IL-12 family, activates both STAT1 and STAT3 through its receptor, which consists of WSX-1 and gp130 subunits, resulting in augmentation of Th1 differentiation and suppression of proinflammatory cytokine production. In the present study, we investigated the role of STAT3 in the IL-27-mediated immune functions. IL-27 induced phosphorylation of STAT1, -2, -3 and -5 in wild-type naive CD4+ T cells, but failed to induce that of STAT3 and STAT5 in STAT3-deficient cohorts. IL-27 induced not only proinflammatory responses including up-regulation of ICAM-1, T-box expressed in T cells, and IL-12Rbeta2 and Th1 differentiation, but also anti-inflammatory responses including suppression of proinflammatory cytokine production such as IL-2, IL-4, and IL-13 even in STAT3-deficient naive CD4+ T cells. In contrast, IL-27 augmented c-Myc and Pim-1 expression and induced cell proliferation in wild-type naive CD4+ T cells but not in STAT3-deficient cohorts. Moreover, IL-27 failed to activate STAT3, augment c-Myc and Pim-1 expression, and induce cell proliferation in pro-B BaF/3 transfectants expressing mutant gp130, in which the putative STAT3-binding four Tyr residues in the YXXQ motif of the cytoplasmic region was replaced by Phe. These results suggest that STAT3 is activated through gp130 by IL-27 and is indispensable to IL-27-mediated cell proliferation but not to IL-27-induced Th1 differentiation and suppression of proinflammatory cytokine production. Thus, IL-27 may be a cytokine, which activates both STAT1 and STAT3 through distinct receptor subunits, WSX-1 and gp130, respectively, to mediate its individual immune functions.

Interleukin-27 directly induces differentiation in hematopoietic stem cells.

Interleukin (IL)-27, one of the most recently discovered IL-6 family cytokines, activates both the signal transducer and activator of transcription (STAT)1 and STAT3, and plays multiple roles in pro- and anti-inflammatory immune responses. IL-27 acts on various types of cells including T, B, and macrophage through the common signal-transducing receptor gp130 and its specific receptor WSX-1, but the effect of IL-27 on hematopoietic stem cells (HSCs) remains unknown. Here, we show that IL-27 together with stem cell factor (SCF) directly acts on HSCs and supports their early differentiation in vitro and in vivo. CD34(-/low)c-Kit(+)Sca-1(+)lineage marker(-) (CD34(-)KSL) cells, a population highly enriched in mouse HSCs, were found to express both IL-27 receptor subunits. In vitro cultures of CD34(-)KSL cells with IL-27 and SCF resulted in an expansion of progenitors including short-term repopulating cells, while some of their long-term repopulating activity also was maintained. To examine its in vivo effect, transgenic mice expressing IL-27 were generated. These mice exhibited enhanced myelopoiesis and impaired B lymphopoiesis in the bone marrow with extramedullary hematopoiesis in the spleen. Moreover, IL-27 similarly acted on human CD34(+) cells. These results suggest that IL-27 is one of the limited cytokines that play a role in HSC regulation.

IL-27 induces Th1 differentiation via p38 MAPK/T-bet- and intercellular adhesion molecule-1/LFA-1/ERK1/2-dependent pathways.

IL-27, a novel member of the IL-6/IL-12 family, activates both STAT1 and STAT3 through its receptor, which consists of WSX-1 and gp130 subunits, resulting in positive and negative regulations of immune responses. We recently demonstrated that IL-27 induces Th1 differentiation through ICAM-1/LFA-1 interaction in a STAT1-dependent, but T-bet-independent mechanism. In this study, we further investigated the molecular mechanisms by focusing on p38 MAPK and ERK1/2. IL-27-induced Th1 differentiation was partially inhibited by lack of T-bet expression or by blocking ICAM-1/LFA-1 interaction with anti-ICAM-1 and/or anti-LFA-1, and further inhibited by both. Similarly, the p38 MAPK inhibitor, SB203580, or the inhibitor of ERK1/2 phosphorylation, PD98059, partially suppressed IL-27-induced Th1 differentiation and the combined treatment completely suppressed it. p38 MAPK was then revealed to be located upstream of T-bet, and SB203580, but not PD98059, inhibited T-bet-dependent Th1 differentiation. In contrast, ERK1/2 was shown to be located downstream of ICAM-1/LFA-1, and PD98059, but not SB203580, inhibited ICAM-1/LFA-1-dependent Th1 differentiation. Furthermore, it was demonstrated that STAT1 is important for IL-27-induced activation of ERK1/2, but not p38 MAPK, and that IL-27 directly induces mRNA expression of growth arrest and DNA damage-inducible 45gamma, which is known to mediate activation of p38 MAPK. Finally, IL-12Rbeta2 expression was shown to be up-regulated by IL-27 in both T-bet- and ICAM-1/LFA-1-dependent mechanisms. Taken together, these results suggest that IL-27 induces Th1 differentiation via two distinct pathways, p38 MAPK/T-bet- and ICAM-1/LFA-1/ERK1/2-dependent pathways. This is in contrast to IL-12, which induces it via only p38 MAPK/T-bet-dependent pathway.

Oligomerizing potential of a focal adhesion LIM protein Hic-5 organizing a nuclear-cytoplasmic shuttling complex.

Hic-5 is a focal adhesion LIM protein serving as a scaffold in integrin signaling. The protein comprises four LD domains in its N-terminal half and four LIM domains in its C-terminal half with a nuclear export signal in LD3 and is shuttled between the cytoplasmic and nuclear compartments. In this study, immunoprecipitation and in vitro cross-linking experiments showed that Hic-5 homo-oligomerized through its most C-terminal LIM domain, LIM4. Strikingly, paxillin, the protein most homologous to Hic-5, did not show this capability. Gel filtration analysis also revealed that Hic-5 differs from paxillin in that it has multiple forms in the cellular environment, and Hic-5 but not paxillin was capable of hetero-oligomerization with a LIM-only protein, PINCH, another molecular scaffold at focal adhesions. The fourth LIM domain of Hic-5 and the fifth LIM domain region of PINCH constituted the interface for the interaction. The complex included integrin-linked kinase, a binding partner of PINCH, which also interacted with Hic-5 through the region encompassing the pleckstrin homology-like domain and LIM domains of Hic-5. Of note, Hic-5 marginally affected the subcellular distribution of PINCH but directed its shuttling between the cytoplasmic and nuclear compartments in the presence of integrin-linked kinase. Uncoupling of the two signaling platforms of Hic-5 and PINCH through interference with the hetero-oligomerization resulted in impairment of cellular growth. Hic-5 is, thus, a molecular scaffold with the potential to dock with another scaffold through the LIM domain, organizing a mobile supramolecular unit and coordinating the adhesion signal with cellular activities in the two compartments.

Antiangiogenic and antitumor activities of IL-27.

IL-27 is a novel IL-6/IL-12 family cytokine playing an important role in the early regulation of Th1 responses. We have recently demonstrated that IL-27 has potent antitumor activity, which is mainly mediated through CD8(+) T cells, against highly immunogenic murine colon carcinoma. In this study, we further evaluated the antitumor and antiangiogenic activities of IL-27, using poorly immunogenic murine melanoma B16F10 tumors, which were engineered to overexpress single-chain IL-27 (B16F10 + IL-27). B16F10 + IL-27 cells exerted antitumor activity against not only s.c. tumor but also experimental pulmonary metastasis. Similar antitumor and antimetastatic activities of IL-27 were also observed in IFN-gamma knockout mice. In NOD-SCID mice, these activities were decreased, but were still fairly well-retained, suggesting that different mechanisms other than the immune response are also involved in the exertion of these activities. Immunohistochemical analyses with Abs against vascular endothelial growth factor and CD31 revealed that B16F10 + IL-27 cells markedly suppressed tumor-induced neovascularization in lung metastases. Moreover, B16F10 + IL-27 cells clearly inhibited angiogenesis by dorsal air sac method, and IL-27 exhibited dose-dependent inhibition of angiogenesis on chick embryo chorioallantoic membrane. IL-27 was revealed to directly act on HUVECs and induce production of the antiangiogenic chemokines, IFN-gamma-inducible protein (IP-10) and monokine induced by IFN-gamma. Finally, augmented mRNA expression of IP-10 and monokine induced by IFN-gamma was detected at the s.c. B16F10 + IL-27 tumor site, and antitumor activity of IL-27 was partially inhibited by the administration of anti-IP-10. These results suggest that IL-27 possesses potent antiangiogenic activity, which plays an important role in its antitumor and antimetastatic activities.

IL-27 suppresses CD28-mediated [correction of medicated] IL-2 production through suppressor of cytokine signaling 3.

IL-27 is a novel IL-6/IL-12 family cytokine that not only plays a role in the early regulation of Th1 differentiation, but also exerts an inhibitory effect on immune responses, including the suppression of proinflammatory cytokine production. However, the molecular mechanism by which IL-27 exerts the inhibitory effect remains unclear. In this study we demonstrate that IL-27 inhibits CD28-mediated IL-2 production and that suppressor of cytokine signaling 3 (SOCS3) plays a critical role in the inhibitory effect. Although IL-27 enhanced IFN-gamma production from naive CD4+ T cells stimulated with plate-coated anti-CD3 and anti-CD28 in the presence of IL-12, IL-27 simultaneously inhibited CD28-mediated IL-2 production. Correlated with the inhibition, IL-27 was shown to augment SOCS3 expression. Analyses using various mice lacking a signaling molecule revealed that the inhibition of IL-2 production was dependent on STAT1, but not on STAT3, STAT4, and T-bet, and was highly correlated with the induction of SOCS3 expression. Similar inhibition of CD28-mediated IL-2 production and augmentation of SOCS3 expression by IL-27 were observed in a T cell hybridoma cell line, 2B4. Forced expression of antisense SOCS3 or dominant negative SOCS3 in the T cell line blocked the IL-27-inudced inhibition of CD28-mediated IL-2 production. Furthermore, pretreatment with IL-27 inhibited IL-2-mediated cell proliferation and STAT5 activation, although IL-27 hardly affected the induction level of CD25 expression. These results suggest that IL-27 inhibits CD28-mediated IL-2 production and also IL-2 responses, and that SOCS3, whose expression is induced by IL-27, plays a critical role in the inhibitory effect in a negative feedback mechanism.

A role for IL-27 in early regulation of Th1 differentiation.

IL-27 is a novel IL-6/IL-12 family cytokine that is considered to play a role in Th1 differentiation, whereas the exact role of IL-27 in Th1 differentiation and its molecular mechanism remain unclear. In this study we demonstrate a role for IL-27 in the early regulation of Th1 differentiation and its possible molecular mechanism. The ability of IL-27 to induce Th1 differentiation was most prominent under Th1-polarizing conditions, but without IL-12 in a STAT4- and IFN-gamma-independent manner, and was overruled by IL-12 dose dependently. IL-27 rapidly up-regulated the expression of ICAM-1 on naive CD4+ T cells, but not on APCs, and blocking Abs against ICAM-1 and LFA-1 inhibited the IL-27-induced Th1 differentiation. Although IL-27 augmented T-bet expression in naive CD4+ T cells as previously reported, T-bet was not necessary for the IL-27-induced rapid up-regulation of ICAM-1 expression and Th1 differentiation. In contrast, STAT1 was revealed to be required for the rapid up-regulation of ICAM-1 expression and Th1 differentiation by directly mediating the transcriptional enhancement of ICAM-1 gene expression. These results indicate that IL-27 efficiently induces Th1 differentiation under Th1-polarizing conditions, but without IL-12, and that the rapid up-regulation of ICAM-1 expression on naive CD4+ T cells is important for the IL-27-induced Th1 differentiation. Considering that IL-27 is produced from macrophages and DCs earlier than IL-12, the present results suggest that IL-27 may play a pivotal role in early efficient induction of Th1 differentiation until sufficient IL-12 is produced.

Augmentation of effector CD8+ T cell generation with enhanced granzyme B expression by IL-27.

IL-27 is a novel IL-12 family member that plays a role in the early regulation of Th1 initiation. We have recently demonstrated that IL-27 has a potent antitumor activity, which is mainly mediated through CD8+ T cells, and also has an adjuvant activity to induce epitope-specific CTL in vivo. In this study, we further investigated the in vitro effect of IL-27 on CD8+ T cells of mouse spleen cells. In a manner similar to CD4+ T cells, IL-27 activated STAT1, -2, -3, -4, and -5, and augmented the expression of T-bet, IL-12Rbeta2, and granzyme B, and slightly that of perforin in naive CD8+ T cells stimulated with anti-CD3. IL-27 induced synergistic IFN-gamma production with IL-12 and proliferation of naive CD8+ T cells. Moreover, IL-27 enhanced proliferation of CD4+ T cell-depleted spleen cells stimulated by allogeneic spleen cells and augmented the generation of CTL. In STAT1-deficient naive CD8+ T cells, IL-27-induced proliferation was not reduced, but synergistic IFN-gamma production with IL-12 was diminished with decreased expression of T-bet, IL-12Rbeta2, granzyme B, and perforin. In T-bet-deficient naive CD8+ T cells, IL-27-induced proliferation was hardly reduced, but synergistic IFN-gamma production with IL-12 was diminished with decreased expression of IL-12Rbeta2, granzyme B, and perforin. However, IL-27 still augmented the generation of CTL from T-bet-deficient CD4+ T cell-depleted spleen cells stimulated by allogeneic spleen cells with increased granzyme B expression. These results suggest that IL-27 directly acts on naive CD8+ T cells in T-bet-dependent and -independent manners and augments generation of CTL with enhanced granzyme B expression.

Induction of IgG2a class switching in B cells by IL-27.

IL-27 is a novel IL-12 family member that plays a role in the early regulation of Th1 initiation. However, its role in B cells remains unexplored. We here show a role for IL-27 in the induction of T-bet expression and regulation of Ig class switching in B cells. Expression of WSX-1, one subunit of IL-27R, was detected at the mRNA level in primary mouse spleen B cells, and stimulation of these B cells by IL-27 rapidly activated STAT1. IL-27 then induced T-bet expression and IgG2a, but not IgG1, class switching in B cells activated with anti-CD40 or LPS. In contrast, IL-27 inhibited IgG1 class switching induced by IL-4 in activated B cells. Similar induction of STAT1 activation, T-bet expression and IgG2a class switching was observed in IFN-gamma-deficient B cells, but not in STAT1-deficient ones. The induction of IgG2a class switching was abolished in T-bet-deficient B cells activated with LPS. These results suggest that primary spleen B cells express functional IL-27R and that the stimulation of these B cells by IL-27 induces T-bet expression and IgG2a, but not IgG1, class switching in a STAT1-dependent but IFN-gamma-independent manner. The IL-27-induced IgG2a class switching is highly dependent on T-bet in response to T-independent stimuli such as LPS. Thus, IL-27 may be a novel attractive candidate as a therapeutic agent against diseases such as allergic disorders by not only regulating Th1 differentiation but also directly acting on B cells and inducing IgG2a class switching.

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors prevent the development of cardiac hypertrophy and heart failure in rats.

OBJECTIVES: The aim of the present study was to determine whether 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have preventive effects on the development of cardiac hypertrophy and heart failure. BACKGROUND: Statins have been reported to have various pleiotropic effects, such as inhibition of inflammation and cell proliferation. METHODS: Dahl rats were divided into three groups: LS, the rats fed the low-salt diet (0.3% NaCl); HS, the rats fed the high-salt diet (8% NaCl) from the age of 6 weeks; and CERI, the rats fed the high-salt diet with cerivastatin 1 mg/kg/d by gavage from the age of 6 weeks. RESULTS: In HS rats, cardiac function was markedly impaired and all rats showed the signs of heart failure within 17 weeks of age. In CERI rats, cardiac function was better than that of HS and no rats were dead up to 17 weeks of age. The development of cardiac hypertrophy and fibrosis was attenuated, and the number of apoptotic cells and expression of proinflammatory cytokine interleukin (IL)-1beta gene were less as compared with HS rats. Pretreatment of cerivastatin suppressed the adriamycin-induced apoptosis of cultured cardiomyocytes of neonatal rats. CONCLUSIONS: These results suggest that statins have a protective effect on cardiac myocytes and may be useful to prevent the development of hypertensive heart failure.

Inhibitory molecules in signal transduction pathways of cardiac hypertrophy.

Cardiac hypertrophy is induced by a variety of diseases, such as hypertension, valvular diseases, myocardial infarction, and endocrine disorders. Although cardiac hypertrophy may initially be a beneficial response that normalizes wall stress and maintains normal cardiac function, prolonged hypertrophy is a leading cause of heart failure and sudden death. A number of studies have elucidated molecules responsible for the development of cardiac hypertrophy, including the mitogen-activated protein (MAP) kinases pathway, Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway, and calcium/calmodulin-dependent protein phosphatase calcineurin pathway. These molecules may be targets for therapies designed to prevent the progression of cardiac hypertrophy. Numerous studies have focused on characterization of the intracellular signal transduction molecules that promote cardiac hypertrophy in order to clarify the molecular mechanisms, but there have been only a few reports on the inhibitory regulators of hypertrophic response. Recently, several molecules have attracted much attention as endogenous inhibitory regulators of cardiac hypertrophy. Enhancement of these inhibitory regulators would also seem to be a potential approach for the pharmacological treatment of hypertrophy. In this review, we summarize the inhibitory molecules of cardiac hypertrophy.

Peroxisome proliferator-activated receptor gamma plays a critical role in inhibition of cardiac hypertrophy in vitro and in vivo.

BACKGROUND: Peroxisome proliferator-activated receptors (PPARs) are transcription factors of the nuclear receptor superfamily. It has been reported that the thiazolidinediones, which are antidiabetic agents and high-affinity ligands for PPARgamma, regulate growth of vascular cells. In the present study, we examined the role of PPARgamma in angiotensin II (Ang II)-induced hypertrophy of neonatal rat cardiac myocytes and in pressure overload-induced cardiac hypertrophy of mice. METHODS AND RESULTS: Treatment of cultured cardiac myocytes with PPARgamma ligands such as troglitazone, pioglitazone, and rosiglitazone inhibited Ang II-induced upregulation of skeletal alpha-actin and atrial natriuretic peptide genes and an increase in cell surface area. Treatment of mice with a PPARgamma ligand, pioglitazone, inhibited pressure overload-induced increases in the heart weight-to-body weight ratio, wall thickness, and myocyte diameter in wild-type mice and an increase in the heart weight-to-body weight ratio in heterozygous PPARgamma-deficient mice. In contrast, pressure overload-induced increases in the heart weight-to-body weight ratio and wall thickness were more prominent in heterozygous PPARgamma-deficient mice than in wild-type mice. CONCLUSIONS: These results suggest that the PPARgamma-dependent pathway is critically involved in the inhibition of cardiac hypertrophy.