Gpr174-deficient regulatory T cells decrease cytokine storm in septic mice.

G protein-coupled receptor 174 (GPR174) is mainly expressed in thymus, spleen, lymph nodes, and leukocytes, and genetic variation in GPR174 is associated with susceptibility to autoimmune diseases, indicating that GPR174 is involved in the immune response. However, the function of GPR174 in regulating inflammatory responses against bacterial infection in sepsis remains unclear. In this study, we investigated the role of GPR174 in regulating suppressive function of regulatory T cells (Treg cells) and the underlying mechanism of Gpr174-deficient Treg cells in controlling cytokine storm of sepsis. We showed that Gpr174-dedicient mice were resistant to inflammatory shock induced by lipopolysaccharide (LPS) and cecal ligation and puncture (CLP). Moreover, Gpr174 was highly expressed in Treg cells, and its deficiency in mice promoted the expression of cytotoxic T lymphocyte associated antigen 4 (CTLA-4) and interleukin (IL)-10 in Treg cells. By using the LPS-induced sepsis model, we demonstrated that anti-inflammatory macrophages (M2 macrophages) induction was Treg cell-dependent and Gpr174-deficient Treg cells protected mice against sepsis-induced lung damage through prompting M2 macrophages polarization. In vitro, Gpr174-deficient Treg cells also promoted the polarization of macrophages toward M2 cells and dampened the secretions of pro-inflammatory cytokines (IL-6 and tumor necrosis factor-α (TNF-α)) in macrophages. In conclusion, these findings suggested that GPR174 plays an important role in the initial period of sepsis through the regulation of macrophage polarization and pro- and anti-inflammatory cytokine secretions. Therefore, GPR174 may be a promising target for therapeutic agents to regulate inflammatory disorders.

Novel Serine 176 Phosphorylation of YBX1 Activates NF-κB in Colon Cancer.

Y box protein 1 (YBX1) is a well known oncoprotein that has tumor-promoting functions. YBX1 is widely considered to be an attractive therapeutic target in cancer. To develop novel therapeutics to target YBX1, it is of great importance to understand how YBX1 is finely regulated in cancer. Previously, we have shown that YBX1 could function as a tumor promoter through phosphorylation of its Ser-165 residue, leading to the activation of the NF-κB signaling pathway (1). In this study, using mass spectrometry analysis, we discovered a distinct phosphorylation site, Ser-176, on YBX1. Overexpression of the YBX1-S176A (serine-to-alanine) mutant in either HEK293 cells or colon cancer HT29 cells showed dramatically reduced NF-κB-activating ability compared with that of WT-YBX1, confirming that Ser-176 phosphorylation is critical for the activation of NF-κB by YBX1. Importantly, the mutant of Ser-176 and the previously reported Ser-165 sites regulate distinct groups of NF-κB target genes, suggesting the unique and irreplaceable function of each of these two phosphorylated serine residues. Our important findings could provide a novel cancer therapy strategy by blocking either Ser-176 or Ser-165 phosphorylation or both of YBX1 in colon cancer.

Cytokine-dependent induction of CD4+ T cells with cytotoxic potential during influenza virus infection.

Recent evidence has identified the role of granzyme B- and perforin-expressing CD4(+) T cells with cytotoxic potential in antiviral immunity. However, the in vivo cytokine cues and downstream pathways governing the differentiation of these cells are unclear. Here, we have identified that CD4(+) T cells with cytotoxic potential are specifically induced at the site of infection during influenza virus infection. The development of CD4(+) T cells with cytotoxic potential in vivo was dependent on the cooperation of the STAT2-dependent type I interferon signaling and the interleukin-2/interleukin-2 receptor alpha pathway for the induction of the transcription factors T-bet and Blimp-1. We showed that Blimp-1 promoted the binding of T-bet to the promoters of cytolytic genes in CD4(+) T cells and was required for the cytolytic function of the in vitro- and in vivo-generated CD4(+) T cells with cytotoxic potential. Thus, our data define the molecular basis of regulation of the in vivo development of this functionally cytotoxic Th subset during acute respiratory virus infection. The potential implications for the functions of these cells are discussed.