Xiaoping Luo

Increased Killing of Liver NK Cells by Fas/Fas Ligand and NKG2D/NKG2D Ligand Contributes to Hepatocyte Necrosis in Virus-Induced Liver Failure

The role of liver NK cells in virus-induced severe viral hepatitis and, subsequently, hepatic failure is not well defined. In this study, we investigated the role of liver NK cells in the development of hepatocyte necrosis in fulminant hepatic failure (FHF)and acute-on-chronic liver failure (ACLF) because of viral infection. A mouse model of FHF induced by murine hepatitis virus strain 3 (MHV-3) was used to study the role of liver NK cells. Samples from patients with hepatitis B virus-related ACLF (HBV-ACLF) were examined. After MHV-3 infection, the number of NK cells in livers of BALB/cJ mice increased markedly, peaked at 48 h postinfection, and remained at a high level until sacrifice. In peripheral blood, spleen, and bone marrow, this number decreased significantly. Expression of CD69, cytotoxic activity, and intracellular IFN-γ and TNF-α production by liver NK cells at 48 h postinfection were all significantly upregulated. Depletion of NK cells 24 h post-MHV-3 infection increased the mice survival from 0 of 18 (0%) to 4 of 18 (22.2%). Highly activated liver NK cells were cytotoxic to MHV-3-infected hepatocytes and this effect was markedly inhibited by anti-Fas ligand (FasL) plus anti-NKG2D mAbs. Furthermore, the accumulation of hepatic NK cells and increased expression of FasL and natural cytotoxicity receptors (NKp30 and NKp46) on the peripheral NK cells from patients with HBV-ACLF were correlated with disease progression. These results indicate NK cells play a pivotal role in the pathogenesis of FHF and HBV-ACLF, in which process Fas/FasL and NKG2D/NKG2D ligand pathway contribute to the liver NK cell-mediated hepatocyte injury.

Role of Fibrinogen-Like Protein 2 Prothrombinase/Fibroleukin in Experimental and Human Allograft Rejection

Immune coagulation is a major contributor to the pathogenesis of xenograft rejection, viral-induced hepatocellular injury and cytokine-induced fetal loss syndrome. In this study, we investigated the contribution of the novel gene product, fibrinogen-like protein 2 (fgl2) prothrombinase, in mediating immune injury in experimental and human acute allograft rejection. Using a mouse heterotopic cardiac transplant model, mouse fgl2(mfgl2)/fibroleukin mRNA transcripts and protein were highly expressed in macrophages, CD4- and CD8-positive T lymphocytes, and endothelial cells in rejecting cardiac allografts in association with deposits of fibrin. Although mfgl2-deficient mice rejected allografts at similar rates to littermate controls, survival of grafts from mfgl2-deficient mice were prolonged and deposition of intravascular fibrin was diminished. Treatment of wild-type mice with a neutralizing anti-fgl2 Ab ameliorated histological evidence for allorejection and intravascular fibrin deposition, and resulted in an increase in graft survival. To address further the relevance of fgl2 in acute allograft rejection, we examined kidney biopsies from patients who had undergone renal transplantation. Human fgl2 mRNA transcripts and protein were markedly expressed mainly in renal tubule cells, infiltrating lymphoid cells including macrophages, CD8+ T cells, mature B cells (plasma cells), and endothelial cells. Dual staining showed fibrin deposition was localized mainly to blood vessels, in the glomerulus and interstitium and the lumen of tubules, and occurred in association with human fgl2 expression. These data collectively suggest that fgl2 accounts for the fibrin deposition seen in both experimental and human allograft rejection and provide a rationale for targeting fgl2 as adjunctive therapy to treat allograft rejection.

Hepatitis B Virus-induced hFGL2 Transcription Is Dependent on c-Ets-2 and MAPK Signal Pathway

Fibrinogen-like protein 2 (FGL2)/fibroleukin plays a pivotal role in the pathogenesis of experimental and human fulminant and chronic viral hepatitis. To define the transcription factor(s) and upstream signal transduction pathways involved in the transcription of human FGL2 (hFGL2) in response to hepatitis B (HB) virus, hepatitis B core (HBc), hepatitis B virus S protein (HBs), or hepatitis B virus X protein (HBx) protein, expression plasmids were cotransfected with an hFGL2 promoter luciferase reporter construct into Chinese hamster ovary and HepG2 cells, respectively. HBc and HBx proteins, but not HBs protein, enhanced hFGL2 transcription in both cell lines. A strong regulatory region from -712 to -568 (relative to the transcriptional starting site) was shown to be responsible for hFGL2 gene transcription in response to both HBc and HBx proteins. c-Ets-2 was shown to be translocated to the nucleus in association with hFGL2 expression in response to both HBc and HBx proteins. Short hairpin RNA (shRNA) interference of c-Ets-2 expression inhibited hFGL2 gene transcription by 64.8 and 60.0% in response to HBc and HBx, respectively. c-Ets-2 protein was highly expressed in peripheral blood mononuclear cells from patients with severe chronic hepatitis B (CHB) in contrast to patients with mild CHB. Increased phosphorylation of ERK and JNK was detected in peripheral blood mononuclear cells from patients with severe CHB. ERK inhibitor PD098059 or ERK shRNA abolished the nuclear c-Ets-2 DNA binding activity and hFGL2 induction in response to HBc, whereas JNK inhibitor SP600125 or JNK shRNA abolished the nuclear c-Ets-2 DNA binding activity and hFGL2 induction in response to HBx. In conclusion, HBc and HBx proteins enhance transcription of hFGL2 through c-Ets-2 dependent on MAPK signal pathways.

Downregulation of FGL2/prothrombinase delays HCCLM6 xenograft tumour growth and decreases tumour angiogenesis

Fibrinogen‐like protein 2 (FGL2), which directly generates thrombin from prothrombin without activation of the conventional coagulation cascade, was shown to be overexpressed in various human malignant tumours.

The detection of HBV DNA with gold nanoparticle gene probes

Abstract Objective Gold nanoparticle Hepatitis B virus(HBV) DNA probes were prepared, and their application for HBV DNA measurement was studied. Methods Alkanethiol modified oligonucleotide was bound with self-made Au nanoparticles to form nanoparticle HBV DNA gene probes, through covalent binding of Au-S. By using a fluorescence-based method, the number of thiolderivatized, single-stranded oligonucleotides and their hybridization efficiency with complementary oligonucleotides in solution was determined. With the aid of Au nanoparticle-supported mercapto-modified oligonucleotides serving as detection probes, and oligonucleotides im-mobilized on a nylon membrane surface acting as capturing probes, HBV DNA was detected visually by sandwich hybridization based on highly sensitive aggregation and silver staining. The modified nanoparticle HBV DNA gene probes were also used to detect the HBV DNA extracted from serum in patients with hepatitis B. Results Compared with bare Au nanoparticles, oligonucleotide modified nanoparticles had a higher stability in NaCl solution or under high temperature environment and the absorbance peak of modified Au nanoparticles shifted from 520 nm to 524 nm. For Au nanoparticles, the maximal oligonucleotide surface coverage of hexaethiol 30-mer oligonucleotide was(132 ± 10) oligonucleotides per nanoparticle, and the percentage of hybridization strands on nanoparticles was(22 ± 3%). Based on a two-probe sandwich hybridization/nanoparticle amplification/silver staining enhancement method, Au nanoparticle gene probes could detect as low as 10−11 mol/L composite HBV DNA molecules on a nylon membrane and the PCR products of HBV DNA visually. As made evident by transmission electron microscopy, the nanoparticles assembled into large network aggregates when nanoparticle HBV DNA gene probes were applied to detect HBV DNA molecules in liquid. Conclusion Our results showed that successfully prepared Au nanoparticle HBV DNA gene probes could be used to detect HBV DNA directly. The detection-visuallized method has many advantages, including high sensitivity, simple operation and low cost. This technique has potential applications in many fields, especially in multi-gene detection chips.

Valproate pretreatment protects pancreatic β-cells from palmitate-induced ER stress and apoptosis by inhibiting glycogen synthase kinase-3β

BackgroundReduction of pancreatic β-cells mass, major secondary to increased β-cells apoptosis, is increasingly recognized as one of the main contributing factors to the pathogenesis of type 2 diabetes (T2D), and saturated free fatty acid palmitate has been shown to induce endoplasmic reticulum (ER) stress that may contribute to promoting β-cells apoptosis. Recent literature suggests that valproate, a diffusely prescribed drug in the treatment of epilepsy and bipolar disorder, can inhibit glycogen synthase kinase-3β (GSK-3β) activity and has cytoprotective effects in neuronal cells and HepG2 cells. Thus, we hypothesized that valproate may protect INS-1 β-cells from palmitate-induced apoptosis via inhibiting GSK-3β.ResultsValproate pretreatment remarkable prevented palmitate-mediated cytotoxicity and apoptosis (lipotoxicity) as well as ER distension. Furthermore, palmitate triggered ER stress as evidenced by increased mRNA levels of C/EBP homologous protein (CHOP) and activating transcription factor 4 (ATF4) in a time-dependent fashion. However, valproate not only reduced the mRNA and protein expression of CHOP but also inhibited GSK-3β and caspase-3 activity induced by palmitate, whereas, the mRNA expression of ATF4 was not affected. Interestingly, TDZD-8, a specific GSK-3β inhibitor, also showed the similar effect on lipotoxicity and ER stress as valproate in INS-1 cells. Finally, compared with CHOP knockdown, valproate displayed better cytoprotection against palmitate.ConclusionsValproate may protect β-cells from palmitate-induced apoptosis and ER stress via GSK-3β inhibition, independent of ATF4/CHOP pathway. Besides, GSK-3β, rather than CHOP, may be a more promising therapeutic target for T2D.

A Chinese patient with acquired partial lipodystrophy caused by a novel mutation with LMNB2 gene.

Abstract Acquired partial lipodystrophy (APL) is a rare disorder, mainly characterized by progressive loss of subcutaneous fatty tissue, starting from the face and spreading to the upper part of the body. The etiology of APL is unknown. It may be caused by mutations in the lamin B 2 (LMNB2) gene on 19p13.3. We present a Chinese patient who had APL for 12 years, which initially affected her face. She also suffered from marked fatty liver and a mild metabolic disorder. We identified a heterozygous T to C transition in exon 5 of the LMNB2 gene (c.694T>C), and, consequently, tyrosine for histidine (p.Y232H). However, these features and the mutation were absent in her parents. The p.Y232H has not been described previously. We provide clinical data to the genotype-phenotype discussion and further expanded the number of LMNB2 mutations.

Investigations of single nucleotide polymorphisms in folate pathway genes in Chinese families with neural tube defects

AIMS We investigated the hypothesis that there are interactions between SNPs in folate metabolism pathway genes and environmental risk factors to the etiology of neural tube defects (NTDs). METHOD In 602 Chinese families, 609 aborted fetus tissues or blood samples were collected from NTD individuals, and 1106 parental blood samples were detected as controls. We analyzed 28 SNPs in 12 folate pathway genes. Folate supplementation, gestational diabetes mellitus (GDM) and medicine administration before and during pregnancy were investigated. Case-parental control study and transmission/disequilibrium tests were performed according to environmental cofactor stratification. RESULTS Association between 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C>T and NTDs was significant in all stratifications (all P<.05), and synergistic effects of no folate supplementation and GDM were shown on NTD occurrence. 5-Methyltetrahydrofolate-homocysteine methyltransferase (MTHM) 501A>G in case of GDM, and betaine-homocysteine methyltransferase (BHMT) 716G>A in case of no folate supplementation significantly associated with NTDs (both P<.05), whereas the two genotypes alone did not significantly associate with NTDs (both P>.05). CONCLUSIONS MTHFR 677C>T genotype, especially in case of no folate supplementation and GDM, promotes NTD occurrence. MTHM 501A>G only in case of GDM, and BHMT 716G>A only in case of no folate supplementation contribute to the etiology of NTDs.

Dual Interference with Novel Genes mfgl2 and mTNFR1 Ameliorates Murine Hepatitis Virus Type 3-Induced Fulminant Hepatitis in BALB/cJ Mice

Our studies and those of many others have implicated hepatocyte necrosis and apoptosis mediated by fibrinogen-like protein-2 (fgl2) prothrombinase and tumor necrosis factor receptor (TNFR) in the development of fulminant viral hepatitis, a disease with a mortality rate greater than 80% in cases lacking immediate organ transplantation. This study was designed to explore the efficacy of dual short hairpin RNA (shRNA) interference with fgl2 and TNFR1 in the treatment of murine hepatitis virus strain 3 (MHV-3)-induced fulminant hepatitis in mice. Plasmids p-mfgl2shRNA and p-mTNFR1shRNA, complementary to the sequences for mfgl2 and mTNFR1, were constructed. Plasmids pEGFP-mfgl2 and pEGFP-mTNFR1 expressing mfgl2-EGFP (enhanced green fluorescent protein) and mTNFR1-EGFP fusion proteins were also constructed to screen the inhibitory effect of p-mfgl2shRNA and p-mTNFR1shRNA on mfgl2 and mTNFR1 expression. Cotransfection of individual shRNA plasmids and pcDNA3.0-mfgl2 and pcDNA3.0-mTNFR1 expression constructs into Chinese hamster ovary (CHO) cells significantly inhibited mfgl2 and mTNFR1 gene expression, as evidenced by fluorescence microscopy, reverse transcription-polymerase chain reaction, and Western blotting. In vivo hydrodynamic delivery of dual-interference shRNA plasmids for mfgl2 and mTNFR1 significantly decreased mfgl2 and mTNFR1 expression; markedly ameliorated fibrin deposition, hepatocyte necrosis, and apoptosis; and prolonged survival against fulminant viral hepatitis induced by MHV-3 in BALB/cJ mice compared with mfgl2 or TNFR1 single-gene interference. These results indicate that in vivo interference with genes for more than one key target provides superior treatment efficacy compared with single-gene interference.

Characterisation of betatrophin concentrations in childhood and adolescent obesity and insulin resistance

Betatrophin, a novel hormone, is correlated with insulin resistance and promotes pancreatic β‐cell growth in mice. The aim of this study was to determine circulating betatrophin levels in overweight or obese children and adolescents.