Lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNF[alfa]) blunt the response of Neuropeptide Y/Agouti-related peptide (NPY/AgRP) glucose inhibited (GI) neurons to decreased glucose

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HLA-C and HIV-1: friends or foes?

The major histocompatibility complex class I protein HLA-C plays a crucial role as a molecule capable of sending inhibitory signals to both natural killer (NK) cells and cytotoxic T lymphocytes (CTL) via binding to killer cell Ig-like receptors (KIR). Recently HLA-C has been recognized as a key molecule in the immune control of HIV-1. Expression of HLA-C is modulated by a microRNA binding site. HLA-C alleles that bear substitutions in the microRNA binding site are more expressed at the cell surface and associated with the control of HIV-1 viral load, suggesting a role of HLA-C in the presentation of antigenic peptides to CTLs. This review highlights the role of HLA-C in association with HIV-1 viral load, but also addresses the contradiction of the association between high cell surface expression of an inhibitory molecule and strong cell-mediated immunity. To explore additional mechanisms of control of HIV-1 replication by HLA-C, we address specific features of the molecule, like its tendency to be expressed as open conformer upon cell activation, which endows it with a unique capacity to associate with other cell surface molecules as well as with HIV-1 proteins

Interleukin-27-Mediated Suppression of Human Th17 Cells Is Associated with Activation of STAT1 and Suppressor of Cytokine Signaling Protein 1

Accumulating evidence indicates that interleukin (IL)-27, a member of the IL-12 family of cytokines, antagonizes pathological Th17 effector cell responses. Relatively little is known about the cytokines that regulate human Th17 cells. In this study, we investigated the effect of IL-27 on the differentiation of human Th17 cells and on committed memory Th17 cells. We demonstrate that IL-27 suppresses the development of human Th17 cells by downregulating retinoid orphan nuclear receptor C expression and that this inhibition is associated with the induction of the intracellular signaling factors STAT1 and induction of the suppressor of cytokine signaling protein 1. The IL-27-mediated inhibition of IL-17 is independent of IL-10. We show that IL-27 inhibits differentiation of naïve T cells into IL-17+ T cells under different Th17 polarizing conditions. IL-27 suppresses other Th17 subset cytokines such as IL-22 and IL-21 but not tumor necrosis factor-α. Moreover, we also show that IL-27 inhibits IL-17 production by committed Th17 memory cells, which is independent of IL-10. These studies show that IL-27 negatively regulates both the developing and committed human Th17 responses and therefore may be a promising therapeutic approach in the treatment of Th17-mediated diseases