T-bet is a member of the T-box family of transcription factors that appears to regulate lineage commitment in CD4 T helper (TH) lymphocytes in part by activating the hallmark TH1 cytokine, interferon-gamma (IFN-gamma). IFN-gamma is also produced by natural killer (NK) cells and most prominently by CD8 cytotoxic T cells, and is vital for the control of microbial pathogens. Although T-bet is expressed in all these cell types, it is required for control of IFN-gamma production in CD4 and NK cells, but not in CD8 cells. This difference is also apparent in the function of these cell subsets. Thus, the regulation of a single cytokine, IFN-gamma, is controlled by distinct transcriptional mechanisms within the T cell lineage.

Key Points Ibrutinib is the first clinically viable irreversible ITK inhibitor. Ibrutinib inhibits the formation of Th2 but not Th1 immunity.

To study the biologic role of migration inhibitory factor (MIF), a pleiotropic cytokine, we generated a mouse strain lacking MIF by gene targeting in embryonic stem cells. Analysis of the role of MIF during sepsis showed that MIF−/− mice were resistant to the lethal effects of high dose bacterial lipopolysaccharide (LPS), or Staphylococcus aureus enterotoxin B (SEB) with d-galactosamine and had lower plasma levels of tumor necrosis factor α (TNF-α) than did wild-type mice, but normal levels of interleukin (IL)-6 and IL-10. When stimulated with LPS and interferon γ, macrophages from MIF−/− mice showed diminished production of TNF-α, normal IL-6 and IL-12, and increased production of nitric oxide. MIF−/− animals cleared gram-negative bacteria Pseudomonas aeruginosa instilled into the trachea better than did wild-type mice and had diminished neutrophil accumulation in their bronchoalveolar fluid compared to the wild-type mice. Thioglycollate elicited peritoneal exudates in uninfected MIF−/− mice, but showed normal neutrophil accumulation. Finally, the findings of enhanced resistance to P. aeruginosa and resistance to endotoxin-induced lethal shock suggest that the counteraction or neutralization of MIF may serve as an adjunct therapy in sepsis.

Interleukin-35 (IL-35) belongs to the IL-12 family of heterodimeric cytokines but has a distinct functional profile. IL-35 suppresses T cell proliferation and converts naïve T cells into IL-35-producing iTr35. Here we show that IL-35 signals through a unique IL-12Rβ2:gp130 heterodimer or via homodimers. Conventional T cells are sensitive to IL-35-mediated suppression in the absence of one but not both receptor chains, whereas signaling through both chains is required for IL-35 expression and iTr35 conversion. IL35R signaling requires the transcription factors STAT1 and STAT4, which form a unique heterodimer that binds to distinct sites within the Il12a and Ebi3 promoters. This unconventional mode of signaling, which is distinct from other members of the IL-12 family, may broaden the spectrum and specificity of IL-35-mediated suppression.

Leishmaniasis is a global term for cutaneous and visceral anthroponotic and zoonotic diseases caused by the vector-borne parasites of the genus Leishmania. These diseases afflict at least 2 million people each year with more than 350 million at risk in 98 countries worldwide. These are diseases mostly of the impoverished making prevention, diagnosis and treatment difficult. Therapy of leishmaniasis ranges from local treatment of cutaneous lesions to systemic, often toxic, therapy for disseminated cutaneous, mucocutaneous and deadly visceral disease. This review is a summary of the clinical syndromes caused by Leishmania and treatment regimens currently used for various forms of leishmaniasis.

Pancreatic cancers with aberrant expression of macrophage migration inhibitory factor (MIF) are particularly aggressive. To identify key signaling pathways that drive disease aggressiveness in tumors with high MIF expression, we analyzed the expression of coding and non-coding genes in high and low MIF-expressing tumors in multiple cohorts of pancreatic ductal adenocarcinoma (PDAC) patients. The key genes and pathways identified were linked to patient survival and were mechanistically, functionally and clinically characterized using cell lines, a genetically engineered mouse model and PDAC patient cohorts. Here we report evidence of a novel MIF-driven signaling pathway that inhibits the orphan nuclear receptor NR3C2, a previously undescribed tumor suppressor that impacts aggressiveness and survival in PDAC. Mechanistically, MIF upregulated miR-301b which targeted NR3C2 and suppressed its expression. PDAC tumors expressing high levels of MIF displayed elevated levels of miR-301b and reduced levels of NR3C2. Additionally, reduced levels of NR3C2 expression correlated with poorer survival in multiple independent cohorts of PDAC patients. Functional analysis showed that NR3C2 inhibited epithelial-to-mesenchymal transition and enhanced sensitivity to the gemcitabine, a chemotherapeutic drug used in PDAC standard of care. Furthermore, genetic deletion of MIF disrupted a MIF-mir-301b-NR3C2 signaling axis, reducing metastasis and prolonging survival in a genetically engineered mouse model of PDAC. Taken together, our results offer a preclinical proof-of-principle for candidate therapies to target a newly described MIF-miR-301b-NR3C2 signaling axis for PDAC management.

BackgroundThe development of insulin resistance (IR) in mouse models of obesity and type 2 diabetes mellitus (DM) is characterized by progressive accumulation of inflammatory macrophages and subpopulations of T cells in the visceral adipose. Regulatory T cells (Tregs) may play a critical role in modulating tissue inflammation via their interactions with both adaptive and innate immune mechanisms. We hypothesized that an imbalance in Tregs is a critical determinant of adipose inflammation and investigated the role of Tregs in IR/obesity through coordinated studies in mice and humans.Methods and Findings Foxp3-green fluorescent protein (GFP) “knock-in” mice were randomized to a high-fat diet intervention for a duration of 12 weeks to induce DIO/IR. Morbidly obese humans without overt type 2 DM (n = 13) and lean controls (n = 7) were recruited prospectively for assessment of visceral adipose inflammation. DIO resulted in increased CD3+CD4+, and CD3+CD8+ cells in visceral adipose with a striking decrease in visceral adipose Tregs. Treg numbers in visceral adipose inversely correlated with CD11b+CD11c+ adipose tissue macrophages (ATMs). Splenic Treg numbers were increased with up-regulation of homing receptors CXCR3 and CCR7 and marker of activation CD44. In-vitro differentiation assays showed an inhibition of Treg differentiation in response to conditioned media from inflammatory macrophages. Human visceral adipose in morbid obesity was characterized by an increase in CD11c+ ATMs and a decrease in foxp3 expression.ConclusionsOur experiments indicate that obesity in mice and humans results in adipose Treg depletion. These changes appear to occur via reduced local differentiation rather than impaired homing. Our findings implicate a role for Tregs as determinants of adipose inflammation.

SH2D1A, which encodes signaling lymphocyte activation molecule (SLAM)-associated protein (SAP), is altered in patients with X-linked lymphoproliferative disease (XLP), a primary immunodeficiency. SAP-deficient mice infected with lymphocytic choriomeningitis virus had greatly increased numbers of CD8+ and CD4+ interferon-gamma-producing spleen and liver cells compared to wild-type mice. The immune responses of SAP-deficient mice to infection with Leishmania major together with in vitro studies showed that activated SAP-deficient T cells had an impaired ability to differentiate into T helper 2 cells. The aberrant immune responses in SAP-deficient mice show that SAP controls several distinct key T cell signal transduction pathways, which explains in part the complexity of the XLP phenotypes.