Bile acids acutely stimulate insulin secretion of mouse β-cells via farnesoid X receptor activation and K(ATP) channel inhibition

Type 2 diabetes mellitus is associated with alterations in bile acid (BA) signaling. The aim of our study was to test whether pancreatic β-cells contribute to BA-dependent regulation of glucose homeostasis. Experiments were performed with islets from wild-type, farnesoid X receptor (FXR) knockout (KO), and β-cell ATP-dependent K(+) (K(ATP)) channel gene SUR1 (ABCC8) KO mice, respectively. Sodium taurochenodeoxycholate (TCDC) increased glucose-induced insulin secretion. This effect was mimicked by the FXR agonist GW4064 and suppressed by the FXR antagonist guggulsterone. TCDC and GW4064 stimulated the electrical activity of β-cells and enhanced cytosolic Ca(2+) concentration ([Ca(2+)](c)). These effects were blunted by guggulsterone. Sodium ursodeoxycholate, which has a much lower affinity to FXR than TCDC, had no effect on [Ca(2+)](c) and insulin secretion. FXR activation by TCDC is suggested to inhibit K(ATP) current. The decline in K(ATP) channel activity by TCDC was only observed in β-cells with intact metabolism and was reversed by guggulsterone. TCDC did not alter insulin secretion in islets of SUR1-KO or FXR-KO mice. TCDC did not change islet cell apoptosis. This is the first study showing an acute action of BA on β-cell function. The effect is mediated by FXR by nongenomic elements, suggesting a novel link between FXR activation and K(ATP) channel inhibition.     

Inflammatory cells of immunosuppressive phenotypes in oral lichen planus have a proinflammatory pattern of expression and are associated with clinical parameters

Objectives

We sought to investigate the expression of cells with immunosuppressive/protumorigenic phenotypes in oral lichen planus (OLP), such as M2-tumor-associated macrophages (TAM2), myeloid-derived suppressive cells (MDSCs), and regulatory T cells (Tregs) in association with clinical parameters.

Materials and methods

Cases of hyperkeratotic (HK)-OLP (n?=?23) and erosive (E)-OLP (n?=?26) were immunohistochemically stained to determine the percentages of CD163-TAM2, CD80-MDSCs, and FOXP3-Tregs of proinflammatory CD121a-Th17, CD4 and CD8 lymphocytes, and of cells positive for nuclear factor kappa B (NF-κB) and transforming growth factor beta. Clinical parameters included symptoms, treatment approach, treatment response, and others.

Results

The inflammatory infiltrate in HK-OLP and E-OLP contained immunosuppressive cells; however, their pattern of expression was compatible with a proinflammatory response [membranous CD163-TAM2 staining (not extracellular), CD80+ lymphocytes (not macrophages), and a few Tregs]. The presence of CD4+, CD8+, and CD121a+ T lymphocytes was extensive. TAM2 were more frequent in E-OLP than in HK-OLP (P?=?0.017). A higher frequency of CD80+ lymphocytes was associated with partial to no response to treatment (P?=?0.028). Nuclear expression of NF-κB in the inflammatory cells was absent.

Conclusions

The pattern of expression of the immunosuppressive cells, together with numerous CD4+, CD8+, and Th17-CD121a+ lymphocytes, suggest an extensive proinflammatory response rather than an immunosuppressive/protumorigenic response.

Clinical relevance

The frequency of selective types of inflammatory cells calls for individual profile analyses of inflammatory infiltrates and individually adjusted treatment.     

Effective guidance of collective migration based on differences in cell states

Directed cell migration is important for normal animal development and physiology. The process can also be subverted by tumor cells to invade other tissues and to metastasize. Some cells, such as leukocytes, migrate individually; other cells migrate together in groups or sheets, called collective cell migration. Guidance of individually migrating cells depends critically on subcellularly localized perception and transduction of signals. For collective cell migration, guidance could result from cells within a group achieving different signaling levels, with directionality then encoded in the collective rather than in individual cells. Here we subject this collective guidance hypothesis to direct tests, using migration of border cells during Drosophila oogenesis as our model system. These cells normally use two receptor tyrosine kinases (RTKs), PDGF/VEGF-related receptor (PVR) and EGFR, to read guidance cues secreted by the oocyte. Elevated but delocalized RTK signaling in one cell of the cluster was achieved by overexpression of PVR in the absence of ligand or by overexpression of fusion receptors unable to detect Drosophila ligands; alternatively, Rac was photoactivated centrally within a single cell. In each case, one cell within the group was in a high signal state, whereas others were in low signal states. The high signal cell directed cluster movement effectively. We conclude that differences in cell signaling states are sufficient to direct collective migration and are likely a substantial contributor to normal guidance. Cell signaling states could manifest as differences in gene expression or metabolite levels and thus differ substantially from factors normally considered when analyzing eukaryotic cell guidance.     

17beta-estradiol promotes breast cancer cell proliferation-inducing stromal cell-derived factor-1-mediated epidermal growth factor receptor transactivation: reversal by gefitinib pretreatment

The coordinated activity of estrogens and epidermal growth factor receptor (EGFR) family agonists represents the main determinant of breast cancer cell proliferation. Stromal cell-derived factor-1 (SDF-1) enhances extracellular signal-regulated kinases 1 and 2 (ERK1/2) activity via the transactivation of EGFR and 17beta-estradiol (E2) induces SDF-1 production to exert autocrine proliferative effects. On this basis, we evaluated whether the inhibition of the tyrosine kinase (TK) activity of EGFR may control different mitogenic stimuli in breast tumors using the EGFR-TK inhibitor gefitinib to antagonize the proliferation induced by E2 in T47D human breast cancer cells. EGF, E2, and SDF-1 induced a dose-dependent T47D cell proliferation, that being nonadditive suggested the activation of common intracellular pathways. Gefitinib treatment inhibited not only the EGF-dependent proliferation and ERK1/2 activation but also the effects of SDF-1 and E2, suggesting that these activities were mediated by EGFR transactivation. Indeed, both SDF-1 and E2 caused EGFR tyrosine phosphorylation. The molecular link between E2 and SDF-1 proliferative effects was identified because 1,1'-(1,4-phenylenebis(methylene))-bis-1,4,8,11-tetraazacyclotetradecane octahydrochloride (AMD3100), a CXCR4 antagonist, inhibited SDF-1- and E2-dependent proliferation and EGFR and ERK1/2 phosphorylation. EGFR transactivation was dependent on c-Src activation. E2 treatment caused a powerful SDF-1 release from T47D cells. Finally, in SKBR3, E2-resistant cells, EGFR was constitutively activated, and AMD3100 reduced EGFR phosphorylation and cell proliferation, whereas HER2-neu was transactivated by SDF-1 in SKBR3 but not in T47D cells. In conclusion, we show that activation of CXCR4 transduces proliferative signals from the E2 receptor to EGFR, whose inhibition is able to revert breast cancer cell proliferation induced by multiple receptor activation.     

Birth and life of tissue macrophages and their migration in embryogenesis and inflammation in medaka

Macrophages detecting and migrating toward sites of injury and infection represent one of the first steps in an immune response. Here we directly image macrophage birth and migration in vivo in transgenic medaka fish. Macrophages are born as frequently dividing, immotile cells with spherical morphology that differentiate into flat, highly motile cells. They retain mitotic activity while spreading over the entire body. Cells follow restricted paths not only in directed migration, but also during patrolling. Along those paths the macrophages rapidly patrol the tissue and respond to wounding and bacterial infection from long distances. Upon injury they increase their speed and migratory persistence. Specifically targeting PI3-kinase isoforms efficiently blocks the wounding response and results in a distinct inhibition of cell motility and chemotaxis. Our study provides in situ insights into the properties of immature and migratory macrophages and presents a unique model to further test modulating compounds in vivo.