Pathogenic Mouse Hepatitis Virus or Poly(I:C) Induce IL-33 in Hepatocytes in Murine Models of Hepatitis.

International audienceThe IL-33/ST2 axis is known to be involved in liver pathologies. Although, the IL-33 levels increased in sera of viral hepatitis patients in human, the cellular sources of IL-33 in viral hepatitis remained obscure. Therefore, we aimed to investigate the expression of IL-33 in murine fulminant hepatitis induced by a Toll like receptor (TLR3) viral mimetic, poly(I:C) or by pathogenic mouse hepatitis virus (L2-MHV3). The administration of poly(I:C) plus D-galactosamine (D-GalN) in mice led to acute liver injury associated with the induction of IL-33 expression in liver sinusoidal endothelial cells (LSEC) and vascular endothelial cells (VEC), while the administration of poly(I:C) alone led to hepatocyte specific IL-33 expression in addition to vascular IL-33 expression. The hepatocyte-specific IL-33 expression was down-regulated in NK-depleted poly(I:C) treated mice suggesting a partial regulation of IL-33 by NK cells. The CD1d KO (NKT deficient) mice showed hepatoprotection against poly(I:C)-induced hepatitis in association with increased number of IL-33 expressing hepatocytes in CD1d KO mice than WT controls. These results suggest that hepatocyte-specific IL-33 expression in poly(I:C) induced liver injury was partially dependent of NK cells and with limited role of NKT cells. In parallel, the L2-MHV3 infection in mice induced fulminant hepatitis associated with up-regulated IL-33 expression as well as pro-inflammatory cytokine microenvironment in liver. The LSEC and VEC expressed inducible expression of IL-33 following L2-MHV3 infection but the hepatocyte-specific IL-33 expression was only evident between 24 to 32h of post infection. In conclusion, the alarmin cytokine IL-33 was over-expressed during fulminant hepatitis in mice with LSEC, VEC and hepatocytes as potential sources of IL-33

Tumor necrosis factor-inducible gene 6 promotes liver regeneration in mice with acute liver injury

INTRODUCTION: Tumor necrosis factor-inducible gene 6 protein (TSG-6), one of the cytokines released by human mesenchymal stem/stromal cells (hMSC), has an anti-inflammatory effect and alleviates several pathological conditions; however, the hepatoprotective potential of TSG-6 remains unclear. We investigated whether TSG-6 promoted liver regeneration in acute liver failure. METHODS: The immortalized hMSC (B10) constitutively over-expressing TSG-6 or empty plasmid (NC: Negative Control) were established, and either TSG-6 or NC-conditioned medium (CM) was intraperitoneally injected into mice with acute liver damage caused by CCl(4). Mice were sacrificed at 3 days post-CM treatment. RESULTS: Higher expression and the immunosuppressive activity of TSG-6 were observed in CM from TSG-6-hMSC. The obvious histomorphological liver injury and increased level of liver enzymes were shown in CCl(4)-treated mice with or without NC-CM, whereas those observations were markedly ameliorated in TSG-6-CM-treated mice with CCl(4). Ki67-positive hepatocytic cells were accumulated in the liver of the CCl(4) + TSG-6 group. RNA analysis showed the decrease in both of inflammation markers, tnfα, il-1β, cxcl1 and cxcl2, and fibrotic markers, tgf-β1, α-sma and collagen α1, in the CCl(4) + TSG-6 group, compared to the CCl(4) or the CCl(4) + NC group. Protein analysis confirmed the lower expression of TGF-β1 and α-SMA in the CCl(4) + TSG-6 than the CCl(4) or the CCl(4) + NC group. Immunostaining for α-SMA also revealed the accumulation of the activated hepatic stellate cells in the livers of mice in the CCl(4) and CCl(4) + NC groups, but not in the livers of mice from the CCl(4) + TSG-6 group. The cultured LX2 cells, human hepatic stellate cell line, in TSG-6-CM showed the reduced expression of fibrotic markers, tgf-β1, vimentin and collagen α1, whereas the addition of the TSG-6 antibody neutralized the inhibitory effect of TSG-6 on the activation of LX2 cells. In addition, cytoplasmic lipid drops, the marker of inactivated hepatic stellate cell, were detected in TSG-6-CM-cultured LX2 cells, only. The suppressed TSG-6 activity by TSG-6 antibody attenuated the restoration process in livers of TSG-6-CM-treated mice with CCl(4). CONCLUSIONS: These results demonstrated that TSG-6 contributed to the liver regeneration by suppressing the activation of hepatic stellate cells in CCl(4)-treated mice, suggesting the therapeutic potential of TSG-6 for acute liver failure. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13287-015-0019-z) contains supplementary material, which is available to authorized users

Targeting Lysophosphatidic Acid Signaling Retards Culture-Associated Senescence of Human Marrow Stromal Cells

Marrow stromal cells (MSCs) isolated from mesenchymal tissues can propagate in vitro to some extent and differentiate into various tissue lineages to be used for cell-based therapies. Cellular senescence, which occurs readily in continual MSC culture, leads to loss of these characteristic properties, representing one of the major limitations to achieving the potential of MSCs. In this study, we investigated the effect of lysophosphatidic acid (LPA), a ubiquitous metabolite in membrane phospholipid synthesis, on the senescence program of human MSCs. We show that MSCs preferentially express the LPA receptor subtype 1, and an abrogation of the receptor engagement with the antagonistic compound Ki16425 attenuates senescence induction in continually propagated human MSCs. This anti-aging effect of Ki16425 results in extended rounds of cellular proliferation, increased clonogenic potential, and retained plasticity for osteogenic and adipogenic differentiation. Expressions of p16Ink4a, Rb, p53, and p21Cip1, which have been associated with cellular senescence, were all reduced in human MSCs by the pharmacological inhibition of LPA signaling. Disruption of this signaling pathway was accompanied by morphological changes such as cell thinning and elongation as well as actin filament deformation through decreased phosphorylation of focal adhesion kinase. Prevention of LPA receptor engagement also promoted ubiquitination-mediated c-Myc elimination in MSCs, and consequently the entry into a quiescent state, G0 phase, of the cell cycle. Collectively, these results highlight the potential of pharmacological intervention against LPA signaling for blunting senescence-associated loss of function characteristic of human MSCs

Genome-Wide Transcriptomic Analysis of Intestinal Tissue to Assess the Impact of Nutrition and a Secondary Nematode Challenge in Lactating Rats

Gastrointestinal nematode infection is a major challenge to the health and welfare of mammals. Although mammals eventually acquire immunity to nematodes, this breaks down around parturition, which renders periparturient mammals susceptible to re-infection and an infection source for their offspring. Nutrient supplementation reduces the extent of periparturient parasitism, but the underlying mechanisms remain unclear. Here, we use a genome wide approach to assess the effects of protein supplementation on gene expression in the small intestine of periparturient rats following nematode re-infection.The use of a rat whole genome expression microarray (Affymetrix Gene 1.0ST) showed significant differential regulation of 91 genes in the small intestine of lactating rats, re-infected with Nippostrongylus brasiliensis compared to controls; affected functions included immune cell trafficking, cell-mediated responses and antigen presentation. Genes with a previously described role in immune response to nematodes, such as mast cell proteases, and intelectin, and others newly associated with nematode expulsion, such as anterior gradient homolog 2 were identified. Protein supplementation resulted in significant differential regulation of 64 genes; affected functions included protein synthesis, cellular function and maintenance. It increased cell metabolism, evident from the high number of non-coding RNA and the increased synthesis of ribosomal proteins. It regulated immune responses, through T-cell activation and proliferation. The up-regulation of transcription factor forkhead box P1 in unsupplemented, parasitised hosts may be indicative of a delayed immune response in these animals.This study provides the first evidence for nutritional regulation of genes related to immunity to nematodes at the site of parasitism, during expulsion. Additionally it reveals genes induced following secondary parasite challenge in lactating mammals, not previously associated with parasite expulsion. This work is a first step towards defining disease predisposition, identifying markers for nutritional imbalance and developing sustainable measures for parasite control in domestic mammals

A Protein Inventory of Human Ribosome Biogenesis Reveals an Essential Function of Exportin 5 in 60S Subunit Export

A systematic search for human ribosome biogenesis factors shows conservation of many aspects of eukaryotic ribosome synthesis with the well-studied process in yeast and identifies an export route of 60S subunits that is specific for higher eukaryotes