15-deoxy-Δ12,14-prostaglandin J2 relieved acute liver injury by inhibiting macrophage migration inhibitory factor expression via PPARγ in hepatocyte.

15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) exhibited potential to alleviate liver inflammation in chronic injury but was less studied in acute injury. Acute liver injury was associated with elevated macrophage migration inhibitory factor (MIF) levels in damaged hepatocytes. This study aimed to investigate the regulatory mechanism of hepatocyte-derived MIF by 15d-PGJ2 and its subsequent impact on acute liver injury. In vivo, mouse models were established by carbon tetrachloride (CCl4) intraperitoneal injection, with or without 15d-PGJ2 administration. 15d-PGJ2 treatment reduced the necrotic areas induced by CCl4. In the same mouse model constructed using enhanced green fluorescent protein (EGFP)-labeled bone marrow (BM) chimeric mice, 15d-PGJ2 reduced CCl4 induced BM-derived macrophage (BMM, EGFP+F4/80+) infiltration and inflammatory cytokine expression. Additionally, 15d-PGJ2 down-regulated liver and serum MIF levels; liver MIF expression was positively correlated with BMM percentage and inflammatory cytokine expression. In vitro, 15d-PGJ2 inhibited Mif expression in hepatocytes. In primary hepatocytes, reactive oxygen species inhibitor (NAC) showed no effect on MIF inhibition by 15d-PGJ2; PPARγ inhibitor (GW9662) abolished 15d-PGJ2 suppressed MIF expression and antagonists (troglitazone, ciglitazone) mimicked its function. In Pparg silenced AML12 cells, the suppression of MIF by 15d-PGJ2 was weakened; 15d-PGJ2 promoted PPARγ activation in AML 12 cells and primary hepatocytes. Furthermore, the conditioned medium of recombinant MIF- and lipopolysaccharide-treated AML12 respectively promoted BMM migration and inflammatory cytokine expression. Conditioned medium of 15d-PGJ2- or siMif-treated injured AML12 suppressed these effects. Collectively, 15d-PGJ2 activated PPARγ to suppress MIF expression in injured hepatocytes, reducing BMM infiltration and pro-inflammatory activation, ultimately alleviating acute liver injury.

Cannabinoid Receptor 1 Participates in Liver Inflammation by Promoting M1 Macrophage Polarization via RhoA/NF-κB p65 and ERK1/2 Pathways, Respectively, in Mouse Liver Fibrogenesis.

Macrophage M1/M2 polarization mediates tissue damage and inflammatory responses. Cannabinoid receptor (CB) 1 participated in liver fibrogenesis by affecting bone marrow (BM)-derived monocytes/macrophages (BMMs) activation. However, the knowledge of whether CB1 is involved in the polarization of BMMs remains limited. Here, we found M1 gene signatures (including CD86, MIP-1ß, tumor necrosis factor, IL-6, and inducible nitric oxide synthase) and the amount of M1 macrophages (CD86+ cells, gated by F4/80) were significantly elevated in carbon tetrachloride (CCl4)-induced mouse injured livers, while that of M2 type macrophages had little change by RT-qPCR and fluorescence-activated cell sorting (FACS). Our preceding study confirmed CB1 was involved in CCl4-induced liver fibrogenesis. Our results noted CB1 expression showed positive correlation with CD86. Blockade of CB1 by its antagonist or siRNA in vivo downregulated the mRNA and protein levels of M1 markers using RT-qPCR, western blot, and Cytometric Bead Array (CBA) assays, and reduced the proportion of M1 macrophages. Moreover, chimera mouse models, which received BM transplants from EGFP-transgenic mice or clodronate liposome injection mouse models, in which Kupffer cells were depleted, were performed to clarify the role of CB1 on the polarization of Kupffer cells and BMMs. We found that CB1 was especially involved in BMM polarization toward M1 phenotype but have no effect on that of Kupffer cells. The reason might due to the lower CB1 expression in Kupffer cells than that of BMMs. In vitro, we discovered CB1 was involved in the polarization of BMMs toward M1. Furthermore, CB1-induced M1 polarization was apparently impaired by PTX [G(α)i/o protein inhibitor], Y27632 (ROCK inhibitor), and PD98059 [extracellular signal-regulated kinase (ERK) inhibitor], while SB203580 (p38 inhibitor) and compound C (AMPK inhibitor) had no such effect. ACEA (CB1 agonist) activated G(α)i/o coupled CB1, then enlarged GTP-bound Rho and phosphor-ERK1/2, independently. NF-κB p65 nuclear translocation is also a marker of M1 phenotype macrophages. We found that CB1 switched on NF-κB p65 nuclear translocation only depending on G(α)i/o/RhoA signaling pathway. CONCLUSION: CB1 plays a crucial role in regulating M1 polarization of BMMs in liver injury, depending on two independent signaling pathways: G(α)i/o/RhoA/NF-κB p65 and G(α)i/o/ERK1/2 pathways.

miR-27b-3p, miR-181a-1-3p, and miR-326-5p are involved in the inhibition of macrophage activation in chronic liver injury.

Macrophages are central players in inflammation, which leads to liver injury. It has been reported that continuous macrophage activation initiates this process. Our previous data show that the anti-inflammatory factor, 15-deoxy-Δ12, 14-prostaglandin J2 (15d-PGJ2), inhibits bone marrow (BM)-derived macrophage (BMM) migration and inflammatory cytokine production. However, the underlying mechanism of 15d-PGJ2 inhibited BMM activation is still unclear. Here, we evaluate the role of 15d-PGJ2/PPARγ axis in BMM activation. 15d-PGJ2 reduced activated BMM population in injured livers. Inflammatory cytokine expressions (MIP-1ß, TNF-α, NOS2) were depressed by 15d-PGJ2 in macrophages isolated from treated livers. In vitro, 15d-PGJ2 inhibited BMM activation via PPARγ. Moreover, miR-27b-3p, miR-181a-1-3p, and miR-326-5p target MIP-1ß, TNF-α, and NOS2 mRNA, respectively. The miRNA expressions were decreased in damaged livers, macrophages isolated from injured livers, and activated BMMs, which were renewed by 15d-PGJ2/PPARγ axis. In activated BMMs, the miRNA inhibitors attenuated inhibitory effect of PPARγ agonist (troglitazone or ciglitazone), while replenishing the lack of miRNAs induced by PPARγ deficiency using miRNA mimics caused a decline of inflammatory cytokines. In conclusion, these data suggest that 15d-PGJ2/PPARγ axis regulates BMM activation via promoting miR-27b-3p, miR-181a-1-3p, and miR-326-5p expressions. KEY MESSAGES: 15d-PGJ2 inhibits BMM activation via PPARγ activation. 15d-PGJ2/PPARγ axis promotes expression of miR-27b-3p, miR-181a-1-3p, and miR-326-5p. miR-27b-3p, miR-181a-1-3p, and miR-326-5p have an inhibitory effect on BMM activation via 15d-PGJ2/PPARγ axis.

HuR mediates motility of human bone marrow-derived mesenchymal stem cells triggered by sphingosine 1-phosphate in liver fibrosis.

Sphingosine 1-phosphate (S1P) participates in migration of bone marrow (BM)-derived mesenchymal stem cells (BMSCs) toward damaged liver via upregulation of S1P receptor 3 (S1PR3) during mouse liver fibrogenesis. But, the molecular mechanism is still unclear. HuR, as an RNA-binding protein, regulates tumor cell motility. Here, we examined the role of HuR in migration of human BMSCs (hBMSCs) in liver fibrosis. Results showed that HuR messenger RNA (mRNA) level was increased in human or mouse fibrotic livers, and correlated with S1PR3 mRNA expression. Using immunofluorescence, we found that HuR mainly localized in the nuclei of hepatocytes and non-parenchymal cells in normal livers. However, in fibrotic livers, we detected an increased HuR cytoplasmic localization in non-parenchymal cells. In chimeric mice of BM cell-labeled by EGFP, significant numbers of EGFP-positive cells (BM origin) were positive for HuR in fibrotic areas. Meanwhile, HuR-positive cells were also positive for α-SMA (myofibroblasts). In vitro, S1P induced hBMSCs migration via S1PR3 upregulation. HuR involved in S1P-induced hBMSCs migration and increased stabilization of S1PR3 mRNA via competing with miR-30e. RNA immunoprecipitation showed that HuR interacted with S1PR3 mRNA 3'UTR. Moreover, S1P resulted in phosphorylation and cytoplasmic translocation of HuR via S1PR3 and p38MAPK. Furthermore, we transplanted EGFP+ BMSCs with or without HuR small interfering RNA (siRNA) into carbon tetrachloride-treated mice and found that knockdown of HuR inhibited the migration of BMSCs toward injured livers by flow cytometric analysis in vivo. We identified a positive feedback regulation mechanism between HuR and S1PR3 in S1P-induced BMSCs migration. HuR participates in upregulation of S1PR3 induced by S1P. S1P results in phosphorylation and translocation of HuR via S1PR3. Our results provide a new regulatory manner to the mechanism of liver fibrogenesis. KEY MESSAGE: HuR expression and cytoplasmic localization were increased in fibrotic livers. S1P induced migration of human bone marrow Mesenchymal Stem Cells via S1PR3 and HuR. HuR regulated S1PR3 mRNA expression by binding with S1PR3 mRNA 3'UTR. S1P induced HuR phosphorylation and cytoplasmic translocation via S1PR3. HuR regulated S1PR3 expression by competing with miR-30e.

Macrophage Migration Inhibitor Factor Upregulates MCP-1 Expression in an Autocrine Manner in Hepatocytes during Acute Mouse Liver Injury.

Macrophage migration inhibitor factor (MIF), a multipotent innate immune mediator, is an upstream component of the inflammatory cascade in diseases such as liver disease. Monocyte chemoattractant protein-1 (MCP-1), a highly representative chemokine, is critical in liver disease pathogenesis. We investigated the role of MIF in regulating hepatocytic MCP-1 expression. MIF and MCP-1 expression were characterized by immunochemistry, RT-PCR, ELISA, and immunoblotting in CCl4-treated mouse liver and isolated hepatocytes. MIF was primarily distributed in hepatocytes, and its expression increased upon acute liver injury. Its expression was also increased in injured hepatocytes, induced by LPS or CCl4, which mimic liver injury in vitro. MIF was expressed earlier than MCP-1, strongly inducing hepatocytic MCP-1 expression. Moreover, the increase in MCP-1 expression induced by MIF was inhibited by CD74- or CD44-specific siRNAs and SB203580, a p38 MAPK inhibitor. Further, CD74 or CD44 deficiency effectively inhibited MIF-induced p38 activation. MIF inhibitor ISO-1 reduced MCP-1 expression and p38 phosphorylation in CCl4-treated mouse liver. Our results showed that MIF regulates MCP-1 expression in hepatocytes of injured liver via CD74, CD44, and p38 MAPK in an autocrine manner, providing compelling information on the role of MIF in liver injury, and implying a new regulatory mechanism for liver inflammation.

Peroxisome Proliferator-Activated Receptor Gamma Negatively Regulates the Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells Toward Myofibroblasts in Liver Fibrogenesis.

BACKGROUND/AIMS: Bone marrow-derived mesenchymal stem cells (BMSCs) have been confirmed to have capacity to differentiate toward hepatic myofibroblasts, which contribute to fibrogenesis in chronic liver diseases. Peroxisome proliferator-activated receptor gamma (PPARx03B3;), a ligand-activated transcription factor, has gained a great deal of recent attention as it is involved in fibrosis and cell differentiation. However, whether it regulates the differentiation of BMSCs toward myofibroblasts remains to be defined. METHODS: Carbon tetrachloride or bile duct ligation was used to induce mouse liver fibrosis. Expressions of PPARx03B3;, α-smooth muscle actin, collagen α1 (I) and collagen α1 (III) were detected by real-time RT-PCR and Western blot or immunofluorescence assay. RESULTS: PPARx03B3; expression was decreased in mouse fibrotic liver. In addition, PPARx03B3; was declined during the differentiation of BMSCs toward myofibroblasts induced by transforming growth factor ß1. Activation of PPARx03B3; stimulated by natural or synthetic ligands suppressed the differentiation of BMSCs. Additionally, knock down of PPARx03B3; by siRNA contributed to BMSC differentiation toward myofibroblasts. Furthermore, PPARx03B3; activation by natural ligand significantly inhibited the differentiation of BMSCs toward myofibroblasts in liver fibrogenesis and alleviated liver fibrosis. CONCLUSIONS: PPARx03B3; negatively regulates the differentiation of BMSCs toward myofibroblasts, which highlights a further mechanism implicated in the BMSC differentiation.

In vitro biological characterization of DCUN1D5 in DNA damage response.

BACKGROUND: Novel prognostic biomarkers or therapeutic molecular targets for laryngeal squamous cell carcinoma (LSCC) are an urgent priority. We here sought to identify multiple novel LSCC-associated genes. METHODS: Using high-density microarray expression profiling, we identified multiple genes that were significantly altered between human LSCCs and paired normal tissues. Potential oncogenic functions of one such gene, DCUN1D5, were further characterized in vitro. RESULTS: Our results demonstrated that DCUN1D5 was highly expressed in LSCCs. Overexpression of DCUN1D5 in vitro resulted in 2.7-fold increased cellular migration, 67.5% increased invasive capacity, and 2.6-fold increased proliferation. Endogenous DCUN1D5 expression was decreased in a time-dependent manner after genotoxic stress, and silencing of DCUN1D5 by siRNA decreased the number of cells in the S phase by 10.2% and increased apoptosis by 11.7%. CONCLUSION: Our data suggest that DCUN1D5 in vitro might have vital roles in DNA damage response, but further studies are warranted to assess its significance in vivo.

Human HS1BP3 induces cell apoptosis and activates AP-1.

In the present study, we characterized the function of HS1-binding protein 3 (HS1BP3), which is mutated in essential tremor and may be involved in lymphocyte activation. We found that HS1BP3 localized to the mitochondria and endoplasmic reticulum partially. Overexpression of HS1BP3 induced apoptosis in HEK293T and HeLa cell lines. When these cell lines were transfected with HS1BP3, they exhibited nuclear DNA condensation, externalization of phosphatidylserine (PS), and cleavage of poly ADP ribose polymerase (PARP). Furthermore, suppression of HS1BP3 or HS1 expression attenuates HS1BP3 induced apoptosis. In addition, HS1BP3 enhanced activator protein 1 (AP-1)-mediated transcription in a dose-dependent manner. Therefore, we conclude that HS1BP3 regulates apoptosis via HS1 and stimulates AP-1-mediated transcription.