A major challenge in vaccinology is to prospectively determine vaccine efficacy. Here we have used a systems biology approach to identify early gene ‘signatures’ that predicted immune responses in humans vaccinated with yellow fever vaccine YF-17D. Vaccination induced genes that regulate virus innate sensing and type I interferon production. Computational analyses identified a gene signature, including complement protein C1qB and eukaryotic translation initiation factor 2 alpha kinase 4—an orchestrator of the integrated stress response—that correlated with and predicted YF-17D CD8+ T cell responses with up to 90% accuracy in an independent, blinded trial. A distinct signature, including B cell growth factor TNFRS17, predicted the neutralizing antibody response with up to 100% accuracy. These data highlight the utility of systems biology approaches in predicting vaccine efficacy.

In atherosclerosis and Alzheimer’s disease, deposition of the altered-self components oxidized low-density lipoprotein (LDL) and β-amyloid triggers a protracted sterile inflammatory response. Although chronic stimulation of the innate immune system is believed to underlie the pathology of these diseases, the molecular mechanisms of activation remain unclear. Here we show that oxidized LDL and β-amyloid trigger inflammatory signaling through a heterodimer of Toll-like receptors 4 and 6. Assembly of this novel heterodimer is regulated by signals from the scavenger receptor CD36, a common receptor for these disparate ligands. Our results identify CD36-TLR4-TLR6 activation as a common molecular mechanism by which atherogenic lipids and β-amyloid stimulate sterile inflammation and suggest a new model of TLR heterodimerization triggered by co-receptor signaling events.

Phagocyte recognition and clearance of bacteria play essential roles in the host response to infection. In an on-going forward genetic screen, we identify the Drosophila melanogaster scavenger receptor Croquemort as a receptor for Staphylococcus aureus, implicating for the first time the CD36 family as phagocytic receptors for bacteria. In transfection assays, the mammalian Croquemort paralogue CD36 confers binding and internalization of Gram-positive and, to a lesser extent, Gram-negative bacteria. By mutational analysis, we show that internalization of S. aureus and its component lipoteichoic acid requires the COOH-terminal cytoplasmic portion of CD36, specifically Y463 and C464, which activates Toll-like receptor (TLR) 2/6 signaling. Macrophages lacking CD36 demonstrate reduced internalization of S. aureus and its component lipoteichoic acid, accompanied by a marked defect in tumor necrosis factor-α and IL-12 production. As a result, Cd36 −/− mice fail to efficiently clear S. aureus in vivo resulting in profound bacteraemia. Thus, response to S. aureus requires CD36-mediated phagocytosis triggered by the COOH-terminal cytoplasmic domain, which initiates TLR2/6 signaling.

Background-In giant cell arteritis (GCA), vasculitic damage of the aorta and its branches is combined with a syndrome of intense systemic inflammation. Therapeutically, glucocorticoids remain the gold standard because they promptly and effectively suppress acute manifestations; however, they fail to eradicate vessel wall infiltrates. The effects of glucocorticoids on the systemic and vascular components of GCA are not understood. Methods and Results-The immunoprofile of untreated and glucocorticoid-treated GCA was examined in peripheral blood and temporal artery biopsies with protein quantification assays, flow cytometry, quantitative real-time polymerase chain reaction, and immunohistochemistry. Plasma interferon-␥ and interleukin (IL)-17 and frequencies of interferon-␥-producing and IL-17-producing T cells were markedly elevated before therapy. Glucocorticoid treatment suppressed the Th17 but not the Th1 arm in the blood and the vascular lesions. Analysis of monocytes/macrophages in the circulation and in temporal arteries revealed glucocorticoid-mediated suppression of Th17-promoting cytokines (IL-1␤, IL-6, and IL-23) but sparing of Th1-promoting cytokines (IL-12). In human artery-severe combined immunodeficiency mouse chimeras, in which patient-derived T cells cause inflammation of engrafted human temporal arteries, glucocorticoids were similarly selective in inhibiting Th17 cells and leaving Th1 cells unaffected. Conclusions-Two Clinical Perspective on p 915Glucocorticoids remain the gold standard of therapy; attempts to introduce steroid-sparing agents, including antitumor necrosis factor blockers, have not been successful. 3,4 Methotrexate may have minor benefits when given over prolonged periods. 5 In a double-blind, placebo-controlled study employing glucocorticoid pulse therapy, patients pulsed at diagnosis had fewer disease flares and discontinued therapy earlier than patients without initial pulse therapy. However, benefits of pulse glucocorticoids were delayed until 12 to 18 months into treatment. 6 Acetylsalicylic acid has a role as adjuvant therapy, partially by inhibiting inflammation and partially through antiplatelet effects. 7,8 Steroid withdrawal after Ͼ2 years of therapy is often accompanied by recurrence of inflammatory markers, and vascular inflammation persists despite glucocorticoid treatment. 9 -11 In essence, despite their prompt, impressive therapeutic effects, glucocorticoids fail to abrogate vasculitis. Improved disease management and avoidance of severe glucocorticoid side effects will require a better understanding of underlying immune abnormalities.Both the innate and adaptive immune system contribute to GCA pathogenesis. 12 Granulomatous inflammatory infiltrates composed of CD4 T cells, activated macrophages, and multinucleated giant cells induce intimal hyperplasia and luminal compromise. 13 In cell-depletion studies, dendritic cells (DCs) have emerged as the predominant antigen-presenting cell. 14,15 DCs are now recognized as an indigenous cell

Immune sensing of a microbe occurs via multiple receptors. How signals from different receptors are coordinated to yield a specific immune response is poorly understood. We demonstrate that the different pathogen recognition receptors, TLR2 and dectin-1, recognizing the same microbial stimulus, stimulate distinct innate and adaptive responses. TLR2 signaling induced splenic dendritic cells (DCs) to express the retinoic acid (RA) metabolizing enzyme Raldh2 and IL-10, and to metabolize vitamin A and stimulate Foxp3+ T regulatory cells (Treg cells). RA acted on DCs to induce Socs3 expression, which suppressed activation of p38 MAPK and pro-inflammatory cytokines. Consistent with this, TLR2 signaling induced Treg cells, and suppressed IL-23 and TH-17/ TH-1 mediated autoimmune responses in vivo. In contrast, dectin-1 signaling mostly induced IL-23 and pro-inflammatory cytokines, and augmented TH-17/ TH-1 mediated autoimmune responses in vivo. These data define a new mechanism for the systemic induction of RA and immune suppression against autoimmunity.

Background-Giant cell arteritis is a granulomatous vasculitis of the aorta and its branches that causes blindness, stroke, and aortic aneurysm. CD4 T cells are key pathogenic regulators, instructed by vessel wall dendritic cells to differentiate into vasculitic T cells. The unique pathways driving this dendritic cell-T-cell interaction are incompletely understood, but may provide novel therapeutic targets for a disease in which the only established therapy is long-term treatment with high doses of corticosteroids. Methods and Results-Immunohistochemical and gene expression analyses of giant cell arteritis-affected temporal arteries revealed abundant expression of the NOTCH receptor and its ligands, Jagged1 and Delta1. Cleavage of the NOTCH intracellular domain in wall-infiltrating T cells indicated ongoing NOTCH pathway activation in large-vessel vasculitis. NOTCH activation did not occur in small-vessel vasculitis affecting branches of the vasa vasorum tree. We devised 2 strategies to block NOTCH pathway activation: ␥-secretase inhibitor treatment, preventing nuclear translocation of the NOTCH intracellular domain, and competing for receptor-ligand interactions through excess soluble ligand, Jagged1-Fc.In a humanized mouse model, NOTCH pathway disruption had strong immunosuppressive effects, inhibiting T-cell activation in the early and established phases of vascular inflammation. NOTCH inhibition was particularly effective in downregulating Th17 responses, but also markedly suppressed Th1 responses. Conclusions-Blocking

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Engineered chimeric cytokines can generate gain-of-function activity in immune cells. Here we report potent antitumor activity for a novel fusion cytokine generated by N-terminal coupling of GM-CSF to IL-4, generating a fusokine termed GIFT4. B cells treated with GIFT4 clustered GM-CSF and IL-4 receptors on the cell surface and displayed a pan-STAT hyperphosphorylation associated with acquisition of a distinct phenotype and function described to date. In C57BL/6J mice, administration of GIFT4 expanded endogenous B cells and suppressed the growth of B16F0 melanoma cells. Further, B16F0 melanoma cells engineered to secrete GIFT4 were rejected immunologically in a B cell-dependent manner. This effect was abolished when GIFT4-expressing B16F0 cells were implanted in B cell-deficient mice, confirming a B cell-dependent antitumor effect. Human GIFT4-licensed B cells primed cytotoxic T cells and specifically killed melanoma cells in vitro and in vivo. Taken together, our results demonstrated that GIFT4 could mediate expansion of B cells with potent antigen-specific effector function. GIFT4 may offer a novel immunotherapeutic tool and define a previously unrecognized potential for B cells in melanoma immunotherapy.