Interferon regulatory factor 3 in adaptive immune responses.

Interferon regulatory factor (IRF) 3 plays a key role in innate responses against viruses. Indeed, activation of this transcription factor triggers the expression of type I interferons and downstream interferon-stimulated genes in infected cells. Recent evidences indicate that this pathway also modulates adaptive immune responses. This review focuses on the different mechanisms that are implicated in this process. We discuss the role of IRF3 within antigen-presenting cells and T lymphocytes in the polarization of the cellular immune response and its implication in the pathogenesis of immune disorders.JOURNAL ARTICLESCOPUS: re.jinfo:eu-repo/semantics/publishe

STAT3 signaling induces the differentiation of human ICOS(+) CD4 T cells helping B lymphocytes.

The generation of high-affinity antibodies and the development of B cell memory are dependent on the help provided by CD4 T cells. Mouse studies indicate that STAT3 signaling in CD4 T cells promotes the acquisition of the B cell help function. However, the role of STAT3 in humans has been controversial. In this study, we show that IL-6 and other STAT3 activating cytokines (IL-21 and IL-27) induce the differentiation of CD4 T cells promoting antibody production by B cells. The acquisition of B cell stimulating properties by naive cord blood CD4 T cells required the STAT3-dependent expression of ICOS and IL-21. Gene reporter and ChIP experiments unambiguously demonstrated that upon IL-6 stimulation, STAT3 induces the transcription of the ICOS gene through direct recruitment to the proximal promoter region indicating that STAT3 acts in part through the direct activation of the ICOS gene.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

An Aspergillus myocardial abscess diagnosed by echocardiography.

This is a rare case of Aspergillus myocardial abscess in 19-year-old woman with acute lymphoblastic leukemia treated by chemotherapy. During pancytopenia she developed invasive aspergillosis with myocardial abscess. The presence of specific antigen in the pericardial effusion was diagnostic. She died despite vigorous antifungal therapy.Case ReportsJournal Articleinfo:eu-repo/semantics/publishe

Interferon regulatory factor 3 controls interleukin-17 expression in CD8 T lymphocytes.

IFN regulatory factor (IRF) 3 plays a key role in innate responses against viruses. Herein we assessed its contribution to T-cell activation. We observed that poly(I:C)-induced IRF3 activation in CD8 T cells represses IL-17 expression in a type I IFN-independent fashion. Even in the absence of poly(I:C), polyclonally activated naïve IRF3(-/-) CD8 T cells expressed high levels of IL-17 and IL-23R in comparison with wild-type cells. Furthermore, IRF3(-/-) OT1 cells adoptively transferred into wild-type hosts also produced higher IL-17 levels upon immunization than their wild-type counterparts. This phenotype could be reversed by ectopic expression of IRF3, confirming that this effect is intrinsic to T cells. We show that IRF3 directly interacts with RORγt in the cytoplasm through its IRF interaction domain and limits its ability to bind and transactivate the IL-17 promoter. These observations uncover an unexpected role of IRF3 in the control of CD8 T-cell polarization.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

STAT3 promotes <i>ICOS</i> transcription through direct interaction with the STAT#1 binding site.

<p>A) Naive cord blood CD4 T cells were stimulated with anti-CD3 and anti-CD28 mAbs in the presence or absence of rIL-6 before measuring ICOS mRNA expression by qRT-PCR. Data are one representative out of 3 experiments on different donors. B) EL4 cells were co-transfected with the (−684/+20) ICOS reporter construct containing a luciferase element and STAT3C or control plasmids. Data are mean ± SEM of triplicates of one experiment out of 5 independent experiments. C) EL4 cells were co-transfected with the indicated reporter plasmid and STAT3C. Twenty-four hours after transfection, cells were incubated with rIL-6 or medium alone for an additional 24 hours before measuring luciferase activity. Data were normalized against unstimulated conditions for each construct and are mean ± SEM of triplicates of 4 independent experiments. D) EL4 cells were co-transfected with the (−174/+20) WT or mutated ICOS reporter construct and STAT3C. Cells were then incubated with rIL-6 or medium alone for an additional 24 hours before measuring luciferase activity. Data are mean ± SEM of triplicates of 4 independent experiments. The sequences of the STAT#1 binding site (nt −57/−43) and the mutation introduced in (−174/+20) MUT constructs are depicted. E and F) ChIP experiments. Naive cord blood CD4 T cells were stimulated with anti-CD3 mAb in the presence of rIL-6 or rIL-21. Chromatin samples were immunoprecipitated with anti-STAT3 or control antibodies. Purified DNA samples were subjected to qPCR amplification using primers encompassing the STAT#1 site from the ICOS promoter or specific for the proximal GAPDH promoter region. Data are mean ± SEM of triplicates of one representative out of two experiments on different donors. R.U.: relative units.</p

Induction of IL-21 and ICOS expression by IL-6 is STAT3-dependent.

<p>Naive cord blood CD4 T cells were transfected with STAT3 specific or control siRNAs in the presence of IL-2. After 48 h, cells were stimulated for 72 hours with plate bound anti-CD3 (5 µg/ml) and soluble anti-CD28 (1 µg/ml) mAbs in the presence of rIL-6 or medium alone before measuring IL-21 production by qRT-PCR (A), membrane expression of ICOS by flow cytometry (A and B), membrane expression of CD69 by flow cytometry and IFN-γ production by ELISA (D). Data are individual results or mean ± SEM of 3 independent experiments on different donors. R.U.: relative units. *p<0.05 as determined by Student's t-test.</p

STAT3 is critical for the differentiation of CD4 T cells helping B cells induced by IL-6.

<p>A) Naive cord blood CD4 T cells were stimulated with the indicated cytokines before measuring phospho (p)STAT3 expression by flow cytometry. B and C) Naive cord blood CD4 T cells were incubated with STAT3 specific or control siRNAs in the presence of IL-2 for 48 hours. Transfected cells were stimulated for an additional 48 hours with plate-bound anti-CD3 (5 µg/ml) and soluble anti-CD28 (1 µg/ml) mAbs in the presence of rIL-6 or medium alone. We then assessed the expression of STAT3 mRNA by qRT-PCR and of pSTAT3 by flow cytometry. D) CD4 T cells were incubated in the presence of heterologous B cells before measuring the production of Ig as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071029#pone-0071029-g001" target="_blank">Fig. 1</a>. Data are individual results or mean ± SEM of one representative of two experiments on different donors.</p

IL-6, IL-12 and IL-27 promote the differentiation of CD4 T cells helping B cells.

<p>A) Naive cord blood CD4 T cells were primed with plate bound anti-CD3 (5 µg/ml) and soluble anti-CD28 (1 µg/ml) mAbs during 72 hours in the presence of supernatant from immature moDCs activated with LPS, Poly(I∶C) or incubated with medium alone. T cells were then thoroughly washed before T/B co-culture to avoid potential carry-over effect of the DC supernatants and were incubated with anti-CD3 mAb and heterologous B cells before measuring Ig production. B) Experiments were performed as in (A) except that anti-IL-6, anti-IL-12 or control mAbs (10 µg/ml) were added to DC culture supernatants before CD4 T cell priming. C) Experiments were performed as in (A) except that recombinant cytokines were used instead of DC culture supernatants. D) Experiments were performed as in (C) except that TSST was used in the T/B co-culture instead of anti-CD3 mAb. Data are mean ± SEM of triplicates from one representation of 3 (A), of 4 (B) or 6 (C and D) independent experiments on different donors. FI/None: fold increase as compared to no cytokine. *p<0.05, **p<0.01 and ***p<0.001 as determined by paired Wilcoxon signed-rank test (A, C and D) or paired Student's t-test (B).</p